Subjects -> CHEMISTRY (Total: 1001 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (726 journals)
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    - INORGANIC CHEMISTRY (45 journals)
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CHEMISTRY (726 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal  
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 36)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 15)
ACS Catalysis     Hybrid Journal   (Followers: 78)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 25)
ACS Combinatorial Science     Hybrid Journal   (Followers: 25)
ACS Macro Letters     Hybrid Journal   (Followers: 34)
ACS Materials Letters     Open Access   (Followers: 4)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 452)
ACS Photonics     Hybrid Journal   (Followers: 19)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 40)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 81)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 15)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 14)
Advanced Science Focus     Free   (Followers: 7)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 108)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 39)
Advances in Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 27)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 13)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 20)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 20)
Advances in Polymer Science     Hybrid Journal   (Followers: 54)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 22)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 6)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Aggregate     Open Access   (Followers: 3)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 3)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 5)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 24)
American Journal of Chemistry     Open Access   (Followers: 41)
American Journal of Plant Physiology     Open Access   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 40)
Analytical Science Advances     Open Access   (Followers: 2)
Angewandte Chemie     Hybrid Journal   (Followers: 237)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 354)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 8)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 12)
Applied Spectroscopy     Full-text available via subscription   (Followers: 27)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 3)
Atomization and Sprays     Full-text available via subscription   (Followers: 8)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 486)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 3)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 4)
Biomacromolecules     Hybrid Journal   (Followers: 27)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 4)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 217)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 4)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 13)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 76)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 14)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 17)
Cereal Chemistry     Full-text available via subscription   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 11)
Chemical and Engineering News     Free   (Followers: 24)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 88)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 28)
Chemical Physics Letters : X     Open Access   (Followers: 4)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemical Reviews     Hybrid Journal   (Followers: 267)
Chemical Science     Open Access   (Followers: 44)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 71)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 225)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 20)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 8)
Chemistry Education Review     Open Access   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry Letters     Full-text available via subscription   (Followers: 49)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 338)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 14)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 13)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 25)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

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Catalysts
Number of Followers: 14  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2073-4344
Published by MDPI Homepage  [238 journals]
  • Catalysts, Vol. 11, Pages 1257: Characterization of a Novel Lutein
           Cleavage Dioxygenase, EhLCD, from Enterobacter hormaechei YT-3 for the
           Enzymatic Synthesis of 3-Hydroxy-β-ionone from Lutein

    • Authors: Zhangde Long, Naixin Duan, Yun Xue, Min Wang, Jigang Li, Zan Su, Qibin Liu, Duobin Mao, Tao Wei
      First page: 1257
      Abstract: 3-Hydroxy-β-ionone, a flavor and fragrance compound with fruity violet-like characteristics, is widely applied in foodstuff and beverages, and is currently produced using synthetic chemistry. In this study, a novel lutein cleavage enzyme (EhLCD) was purified and characterized from Enterobacter hormaechei YT-3 to convert lutein to 3-hydroxy-β-ionone. Enzyme EhLCD was purified to homogeneity by ammonium sulfate precipitation, Q-Sepharose, phenyl-Sepharose, and Superdex 200 chromatography. The molecular mass of purified EhLCD, obtained by SDS-PAGE, was approximately 50 kDa. The enzyme exhibited the highest activity toward lutein, followed by zeaxanthin, β-cryptoxanthin, and β-carotene, suggesting that EhLCD exhibited higher catalytic efficiency for carotenoid substrates bearing 3-hydroxy-ionone rings. Isotope-labeling experiments showed that EhLCD incorporated oxygen from O2 into 3-hydroxy-β-ionone and followed a dioxygenase reaction mechanism for different carotenoid substrates. These results indicated that EhLCD is the first characterized bacterial lutein cleavage dioxygenase. Active EhLCD was also confirmed to be a Fe2+-dependent protein with 1 molar equivalent of non-haem Fe2+. The purified enzyme displayed optimal activity at 45 °C and pH 8.0. The optimum concentrations of the substrate, enzyme, and Tween 40 for 3-hydroxy-β-ionone production were 60 mM lutein/L, 1.5 U/mL, and 2% (w/v), respectively. Under optimum conditions, EhLCD produced 3-hydroxy-β-ionone (637.2 mg/L) in 60 min with a conversion of 87.0% (w/w), indicating that this enzyme is a potential candidate for the enzymatic synthesis of 3-hydroxy-β-ionone in biotechnological applications.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111257
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1258: Green Synthesis of Pd Nanoparticles for
           Sustainable and Environmentally Benign Processes

    • Authors: Oriana Piermatti
      First page: 1258
      Abstract: Among transition metal nanoparticles, palladium nanoparticles (PdNPs) are recognized for their high catalytic activity in a wide range of organic transformations that are of academic and industrial importance. The increased interest in environmental issues has led to the development of various green approaches for the preparation of efficient, low-cost and environmentally sustainable Pd-nanocatalysts. Environmentally friendly solvents, non-toxic reducing reagents, biodegradable capping and stabilizing agents and energy-efficient synthetic methods are the main aspects that have been taken into account for the production of Pd nanoparticles in a green approach. This review provides an overview of the fundamental approaches used for the green synthesis of PdNPs and their catalytic application in sustainable processes as cross-coupling reactions and reductions with particular attention afforded to the recovery and reuse of the palladium nanocatalyst, from 2015 to the present.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111258
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1259: Cyanobacteria as Valuable Tool in
           Biotechnology

    • Authors: Agnieszka Śliżewska, Ewa Żymańczyk-Duda
      First page: 1259
      Abstract: Cyanobacteria constitute an interesting group of photosynthetic microorganisms due to their morphological and genetic diversity that is related to their extremely long evolution process, which created the need for them to adapt to immensely heterogeneous environmental conditions. Cyanobacteria grow in salt and fresh waters as well as on the surface of soils and rocks. The diverse cell structure is characterized by the fact that they occur in many morphological forms, from small single cells through to larger ones as well as branches, threads, or spirals. Taking into account the presence of cyanobacteria in virtually all possible conditions and places on Earth, cyanobacteria represent an unexplored potential that is worth investigating. This review presents the possibilities of using algae in chosen areas of biotechnology: e.g., as biocatalysts or in industries such as the pharmaceutical industry. It covers the characteristics of secondary metabolites along with their division and the potential of using them as sources of effective drugs for many diseases. It presents an overview of the possibilities of using cyanobacteria in biotransformation processes. These processes are of great importance in the case of, for example, the neutralization of municipal, industrial, or chemical waste, the amount of which is constantly growing every year, and they are also an easier and cheaper path to obtain chemical compounds.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111259
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1260: The Influence of Si/Al Ratio on the
           Physicochemical and Catalytic Properties of MgO/ZSM-5 Catalyst in
           Transesterification Reaction of Rapeseed Oil

    • Authors: Łukasz Szkudlarek, Karolina Chałupka, Waldemar Maniukiewicz, Jadwiga Albińska, Malgorzata I. Szynkowska-Jóźwik, Paweł Mierczyński
      First page: 1260
      Abstract: This work presents the comparative physicochemical and catalytic studies of metal oxide MgO catalysts in a transesterification reaction. The influence of the Si/Al ratio in the catalytic material on their catalytic properties in the studied process was extensively evaluated. In addition, the effect of the type of zeolite ZSM-5 form on the catalytic reactivity of MgO based catalysts was investigated. In order to achieve the main goals of this work, a series of MgO/ZSM-5 catalysts were prepared via the impregnation method. Their physicochemical properties were studied using X-ray diffraction (XRD), BET, FTIR and TPD-CO2 methods. The highest activity in the studied process exhibited MgO catalyst supported on ZSM-5 characterized by the highest ratio between silica and alumina. The most active catalyst system in the transesterification reaction was 10% MgO/ZSM-5 (Si/Al = 280), which showed the highest value of higher fatty acid methyl esters (94.6%) and high yield of triglyceride conversion (92.9%). The high activity of this system is explained by the alkalinity, sorption properties in relation to methanol and its high specific surface area compared to the rest of the investigated MgO based catalysts.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111260
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1261: A Short Review on Catalyst, Feedstock,
           Modernised Process, Current State and Challenges on Biodiesel Production

    • Authors: Abdulkareem G. Alsultan, Nurul Asikin-Mijan, Zueriani Ibrahim, Robiah Yunus, Siti Zulaika Razali, Nasar Mansir, Aminul Islam, Sivasangar Seenivasagam, Yun Hin Taufiq-Yap
      First page: 1261
      Abstract: Biodiesel, comprising mono alkyl fatty acid esters or methyl ethyl esters, is an encouraging option to fossil fuels or diesel produced from petroleum; it has comparable characteristics and its use has the potential to diminish carbon dioxide production and greenhouse gas emissions. Manufactured from recyclable and sustainable feedstocks, e.g., oils originating from vegetation, biodiesel has biodegradable properties and has no toxic impact on ecosystems. The evolution of biodiesel has been precipitated by the continuing environmental damage created by the deployment of fossil fuels. Biodiesel is predominantly synthesised via transesterification and esterification procedures. These involve a number of key constituents, i.e., the feedstock and catalytic agent, the proportion of methanol to oil, the circumstances of the reaction and the product segregation and purification processes. Elements that influence the yield and standard of the obtained biodiesel encompass the form and quantity of the feedstock and reaction catalyst, the proportion of alcohol to feedstock, the temperature of the reaction, and its duration. Contemporary research has evaluated the output of biodiesel reactors in terms of energy production and timely biodiesel manufacture. In order to synthesise biodiesel for industrial use efficaciously, it is essential to acknowledge the technological advances that have significant potential in this sector. The current paper therefore offers a review of contemporary progress, feedstock categorisation, and catalytic agents for the manufacture of biodiesel and production reactors, together with modernised processing techniques. The production reactor, form of catalyst, methods of synthesis, and feedstock standards are additionally subjects of discourse so as to detail a comprehensive setting pertaining to the chemical process. Numerous studies are ongoing in order to develop increasingly efficacious techniques for biodiesel manufacture; these acknowledge the use of solid catalytic agents and non-catalytic supercritical events. This review appraises the contemporary situation with respect to biodiesel production in a range of contexts. The spectrum of techniques for the efficacious manufacture of biodiesel encompasses production catalysed by homogeneous or heterogeneous enzymes or promoted by microwave or ultrasonic technologies. A description of the difficulties to be surmounted going forward in the sector is presented.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111261
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1262: Characterization of a New L-Glutaminase
           Produced by Achromobacter xylosoxidans RSHG1, Isolated from an Expired
           Hydrolyzed L-Glutamine Sample

    • Authors: Rabia Saleem, Safia Ahmed
      First page: 1262
      Abstract: As significant biocatalyst, L-glutaminases find potential applications in various fields, from nourishment to the pharmaceutical industry. Anticancer activity and flavor enhancement are the most promising applications of L-glutaminases. In this study, L-glutaminase was isolated and purified from an old glutamine sample. A selected bacterial isolate was characterized taxonomically by morphological characters, biochemical testing and 16S rDNA sequence homology testing. The taxonomical characterization of the isolate identified it as Achromobacter xylosoxidans strain RSHG1. The isolate showed maximum enzyme production at 30 °C, pH 9, with Sorbitol as a carbon source and L-Glutamine as a nitrogen and inducer source. L-Glutaminsae was purified by using column chromatography on a Sephadex G-75. The enzyme has a molecular weight of 40 KDa, pH optimal 7 and is stable in the pH range of 6–8. The optimum temperature for the catalyst was 40 °C and stable at 35–50 °C. The kinetic studies of the purified L-glutaminase exhibited Km and Vmax of 0.236 mM and 443.8 U/mg, respectively. L-Glutaminase activity was increased when incubated with 20 mM CaCl2, BaCl2, ZnSO4, KCl, MgSO4 and NaCl, whereas EDTA, CoCl2, HgCl, ZnSO4 and FeSO4 decreased the activity of the enzyme. The addition of 8% NaCl enhanced the glutaminase activity. L-Glutaminase immobilized on 3.6% agar was stable for up to 3 weeks.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111262
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1263: Phenylalanine, Tyrosine, and DOPA Are Bona
           Fide Substrates for Bambusa oldhamii BoPAL4

    • Authors: Chun-Yen Hsieh, Yi-Hao Huang, Hui-Hsuan Yeh, Pei-Yu Hong, Che-Jen Hsiao, Lu-Sheng Hsieh
      First page: 1263
      Abstract: Phenylalanine ammonia-lyase (PAL) links the plant primary and secondary metabolisms, and its product, trans-cinnamic acid, is derived into thousands of diverse phenylpropanoids. Bambusa oldhamii BoPAL4 has broad substrate specificity using L-phenylalanine, L-tyrosine, and L-3,4-dihydroxy phenylalanine (L-DOPA) as substrates to yield trans-cinnamic acid, p-coumaric acid, and caffeic acid, respectively. The optimum reaction pH of BoPAL4 for three substrates was measured at 9.0, 8.5, and 9.0, respectively. The optimum reaction temperatures of BoPAL4 for three substrates were obtained at 50, 60, and 40 °C, respectively. The Km values of BoPAL4 for three substrates were 2084, 98, and 956 μM, respectively. The kcat values of BoPAL4 for three substrates were 1.44, 0.18, and 0.06 σ-1, respectively. The major substrate specificity site mutant, BoPAL4-H123F, showed better affinity toward L-phenylalanine by decreasing its Km value to 640 μM and increasing its kcat value to 1.87 s-1. In comparison to wild-type BoPAL4, the specific activities of BoPAL4-H123F using L-tyrosine and L-DOPA as substrates retained 5.4% and 17.8% residual activities. Therefore, L-phenylalanine, L-tyrosine, and L-DOPA are bona fide substrates for BoPAL4.
      Citation: Catalysts
      PubDate: 2021-10-20
      DOI: 10.3390/catal11111263
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1264: One-Step Preparation of Nitrogen-Doped
           Platinum-Based Catalysts for Electrocatalytic Oxidation of Ethanol

    • Authors: Ruihua Guo, Na An, Shengli An, Jieyu Zhang, Kuochih Chou, Lili Guan, Xiao Tian
      First page: 1264
      Abstract: Pt/nitrogen-doped reduced graphene oxide (N-GO) catalysts were prepared by one-step microwave-assisted ethylene glycol reduction using N-methyl-2-pyrrolidone (NMP) as the nitrogen source. Nitrogen doping in GO and the deposition of highly dispersed platinum nanoparticles were completed at the same time. The effect of adding NMP on the microstructure and the electrocatalytic performance of Pt/N-GO catalysts were studied. The results show that Pt/N-GO catalysts have better particle size distribution and electrocatalytic performance than undoped catalysts. When the ratio of GO to NMP reaches 1:200, the peak current density of the catalyst is about 3 times that of the non-nitrogen-doped Pt/GO and Pt/C(JM) catalysts, indicating that the electrocatalytic performance of this catalyst is the best. Therefore, the development of a one-step synthesis of Pt/N-GO catalysts has a broad application prospects in direct ethanol fuel cells (DEFCs).
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111264
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1265: Constructing 1D Boron Chains in the
           Structure of Transition Metal Monoborides for Hydrogen Evolution Reactions
           

    • Authors: Yanli Chen, Yanping Ye, Qiang Tao, Lihua Yang, Jiaen Cheng, Xiaoyan Liu, Jian Cao, Hougang Fan, Maobin Wei, Pinwen Zhu, Lili Yang, Jinghai Yang
      First page: 1265
      Abstract: The forms of boron atoms are many and varied in the structure of transition metal borides (TMBs). The form of boron atoms determines the structure, morphology, and properties of borides. Herein, transition metal monoborides (CrB and WB) with different arrangement of one-dimensional (1D) boron chains were synthesized under high pressures and high temperatures. The 1D boron chains between the interlayers of CrB are parallel to one another, while the 1D boron chains between the interlayers of WB are perpendicular to one another. The morphologies of CrB and WB also show large differences due to the difference in 1D boron chain arrangement. As electrocatalysts for hydrogen evolution reactions (HERs), CrB and WB show good catalysis activity and durability. WB has the smallest overpotential (210 mV) and Tafel slope (90.09 mV dec−1), which is mainly attributed to the intercrossing boron chains improving the electrical properties of WB, as well as the 5d electrons of W being more chemically active. The TOF value of WB is 1.35 s−1, proving that WB has a higher intrinsic catalytic activity during HERs. This work provides a data reference for the development of high-efficiency electrocatalysts.
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111265
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1266: Recent Progress of Metal Nanoparticle
           Catalysts for C–C Bond Forming Reactions

    • Authors: Atsushi Ohtaka
      First page: 1266
      Abstract: Over the past few decades, the use of transition metal nanoparticles (NPs) in catalysis has attracted much attention and their use in C–C bond forming reactions constitutes one of their most important applications. A huge variety of metal NPs, which have showed high catalytic activity for C–C bond forming reactions, have been developed up to now. Many kinds of stabilizers, such as inorganic materials, magnetically recoverable materials, porous materials, organic–inorganic composites, carbon materials, polymers, and surfactants have been utilized to develop metal NPs catalysts. This review classified and outlined the categories of metal NPs by the type of support.
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111266
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1267: Expeditious Asymmetric Synthesis of
           Polypropionates Relying on Sulfur Dioxide-Induced C–C Bond Forming
           Reactions

    • Authors: Pierre Vogel, José Angel Sordo Gonzalo
      First page: 1267
      Abstract: For a long time, the organic chemistry of sulfur dioxide (SO2) consisted of sulfinates that react with carbon electrophiles to generate sulfones. With alkenes and other unsaturated compounds, SO2 generates polymeric materials such as polysulfones. More recently, H-ene, sila-ene and hetero-Diels–Alder reactions of SO2 have been realized under conditions that avoid polymer formation. Sultines resulting from the hetero-Diels–Alder reactions of conjugated dienes and SO2 are formed more rapidly than the corresponding more stable sulfolenes resulting from the cheletropic additions. In the presence of a protic or Lewis acid catalyst, the sultines derived from 1-alkoxydienes are ionized into zwitterionic intermediates bearing 1-alkoxyallylic cation moieties which react with electro-rich alkenes such as enol silyl ethers and allylsilanes with high stereoselectivity. (C–C-bond formation through Umpolung induced by SO2). This produces silyl sulfinates that react with carbon electrophiles to give sulfones (one-pot four component asymmetric synthesis of sulfones), or with Cl2, generating the corresponding sulfonamides that can be reacted in situ with primary and secondary amines (one-pot four component asymmetric synthesis of sulfonamides). Alternatively, Pd-catalyzed desulfinylation generates enantiomerically pure polypropionate stereotriads in one-pot operations. The chirons so obtained are flanked by an ethyl ketone moiety on one side and by a prop-1-en-1-yl carboxylate group on the other. They are ready for two-directional chain elongations, realizing expeditious synthesis of long-chain polypropionates and polyketides. The stereotriads have also been converted into simpler polypropionates such as the cyclohexanone moiety of baconipyrone A and B, Kishi’s stereoheptad unit of rifamycin S, Nicolaou’s C1–C11-fragment and Koert’s C16–CI fragment of apoptolidin A. This has also permitted the first total synthesis of (-)-dolabriferol.
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111267
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1268: BaF(p-BDC)0.5 as the Catalyst Precursor
           for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to
           Vinylidene Fluoride

    • Authors: Shucheng Wang, Chuanzhao Wang, Houlin Yu, Wei Yu, Yongnan Liu, Wucan Liu, Feixiang Zhou, Wanjin Yu, Jiuju Wang, Jianjun Zhang, Wenfeng Han
      First page: 1268
      Abstract: A BaF(p-BDC)0.5 catalyst was prepared by solid state reaction at room temperature with Ba(OH)2 as precursor, NH4F as F source, and H2(p-BDC) as organic ligand. The calcined samples were used as catalysts for dehydrochlorination of 1-chloro-1,1-difluoroethane to generate vinylidene fluoride (VDF) at 350 °C. Commercial production of VDF is carried out at 600–700 °C. Clearly, pyrolysis of the BaF(p-BDC)0.5 catalyst provided a promising way to prepare VDF at low temperatures. Prior to calcination, the activity of the BaF(p-BDC)0.5 catalyst was low. Following calcination at high temperatures, BaF(p-BDC)0.5 decomposed to BaF2 and BaCO3, and then the catalyst was chlorinated and fluorinated to BaClF, which showed high activity and stable VDF selectivity for dehydrochlorination of 1-Chloro-1,1-Difluoroethane to VDF.
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111268
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1269: Naphthyl-Naphthalimides as
           High-Performance Visible Light Photoinitiators for 3D Printing and
           Photocomposites Synthesis

    • Authors: Mahmoud Rahal, Bernadette Graff, Joumana Toufaily, Tayssir Hamieh, Malika Ibrahim-Ouali, Frédéric Dumur, Jacques Lalevée
      First page: 1269
      Abstract: In this article, five new organic dyes based on the naphthalimide scaffold (Napht-1–Napht-5) were synthesized and tested as high-performance photoinitiators for both the Free Radical Photopolymerization (FRP) of acrylates and the Cationic Polymerization (CP) of epoxides using blue Light-Emitting Diodes (LEDs) as a safe irradiation source (LED @405 nm and 455). In fact, very good photopolymerization profiles (high final conversions and high polymerization rates) were obtained once these photoinitiators were combined with an Iodonium salt (Iod) or Iod/amine NPG and NVK). Remarkably, these dyes were able to generate interpenetrating polymer networks (IPN) by polymerization of a blend of monomers. These experiments were carried out to improve the polymerization profiles as well as the mechanical properties of the obtained materials. Due to their high photoinitiation abilities, these compounds were used in some applications such as photocomposite synthesis, direct laser write, and 3D printing experiments. To determine the chemical mechanisms, the photochemical/photophysical properties of these compounds were studied using different characterization techniques such as UV–visible absorption spectroscopy, steady-state photolysis, Fluorescence quenching, time-resolved fluorescence spectroscopy, FTIR spectroscopy, and cyclic voltammetry
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111269
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1270: Efficiency of Microencapsulation of
           Proteolytic Enzymes

    • Authors: Sergey L. Tikhonov, Natalya V. Tikhonova, Leonid S. Kudryashov, Olga A. Kudryashova, Nadezhda V. Moskovenko, Irina N. Tretyakova
      First page: 1270
      Abstract: Currently, special attention is paid to the study of the effectiveness of the immobilization method—microencapsulation. The aim of the research is to obtain a complex enzyme preparation from pepsin and papain by sequential microencapsulation of enzymes in a pseudo-boiling layer and to evaluate its tenderizing effect on pork. The objects of research were enzymes: pepsin and papain, which were microencapsulated in a protective coating of maltodextrin. It was found that the biocatalytic activity of the complex enzyme preparation is higher than that of pure enzymes. Microencapsulation allows maintaining the high proteolytic activity of enzymes for a long storage period. It has been shown that the thickness of the protective layer during microencapsulation of pepsin and papain in the pseudo-boiling layer of maltodextrin should be in the range of 4–6 microns. During the research, the physicochemical properties of pork were studied depending on the duration of fermentation. It was found that the maximum activity of immobilized enzymes is shifted to the alkaline side. Pork salting with the use of a microencapsulated enzyme preparation in the brine increases the water-binding capacity of proteins to a greater extent in comparison with brine with pure enzymes. The presented data show the high efficiency of sequential microencapsulation of the enzyme pepsin and then papain into a protective layer of maltodextrin in order to preserve their activity during storage.
      Citation: Catalysts
      PubDate: 2021-10-21
      DOI: 10.3390/catal11111270
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1271: Performance Study of Zn-Co-Ni/AC Catalyst
           in Acetylene Acetylation

    • Authors: Zhuang Xu, Peijie He, Yuhao Chen, Mingyuan Zhu, Xugen Wang, Bin Dai
      First page: 1271
      Abstract: Zinc acetate (Zn(OAc)2) loaded on activated carbon (AC) is the most commonly used catalyst for the industrial synthesis of vinyl acetate (VAc) using the acetylene method. The aim of this study is to optimize the Zn(OAc)2/AC catalyst by adding co-catalysts to improve its activity and stability. Ternary catalysts were synthesized by adding Co and Ni to the Zn(OAc)2/AC catalyst (Zn-Co-Ni/AC). Due to the strong synergistic effect among promoter Co, Ni, and the active component of Zn(OAc)2, the resulting catalyst is capable to absorb more acetic acid and less acetylene. The stability and activity of Zn-Co-Ni/AC catalyst have been improved through electron transfer to alter the electron cloud density around the Zn element. Under the same reaction conditions, the activity of Zn-Co-Ni/AC catalyst was enhanced by 83% compared to that of Zn(OAc)2/AC, and the activity was still as high as 30.1% after 120 h of testing.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111271
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1272: Hydrotreating of Waste Tire Pyrolysis Oil
           over Highly Dispersed Ni2P Catalyst Supported on SBA-15

    • Authors: Gwang-Nam Yun, Ki-Duk Kim, Yong-Kul Lee
      First page: 1272
      Abstract: A highly dispersed nickel phosphide catalyst supported on SBA-15 was prepared and tested for the hydrotreating of tire pyrolysis oil (TPO). Physicochemical properties of the prepared catalyst were analyzed by CO uptake chemisorption, BET, TEM, and X-ray diffraction (XRD). An advanced technique with gas chromatography equipped with mass spectrometry and atomic emission detector was applied to investigate carbon-, sulfur-, and nitrogen-containing compounds in TPO. Hydrotreating tests were carried out in a fixed-bed continuous flow reactor at 350 °C, 3.0 MPa, and LHSV of 0.5 h−1. The Ni2P/SBA-15 exhibited an HDS conversion of 89.3% and an HDN conversion of 60.7%, which was comparable to the performance of a commercial NiMoS catalyst under the same conditions.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111272
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1273: Pd-HPW/SiO2 Bi-Functional Catalyst:
           Sonochemical Synthesis, Characterization, and Effect on
           Octahydroquinazolinone Synthesis

    • Authors: Md. Afroz Bakht, Mshari. Alotaibi, Abdulrahman I. Alharthi, Israf Ud Din, Abuzer Ali, Amena Ali, Mohamed Jawed Ahsan
      First page: 1273
      Abstract: A Palladium-doped silica-supported heteropoly acid (HPW) (1%Pd-HPW/SiO2) bi-functional catalyst was produced using ultrasonic and conventional procedures. Both forms of catalyst were characterized with distinct analytical approaches in order to access the advantages of each one. The presence of the required functional groups in the catalyst was confirmed using FT-IR. The crystallinity of ultrasonically generated 1%Pd-HPW/SiO2 was confirmed with XRD. The existence of necessary elements in the catalyst was also suggested by XPS and EDX data. BET was used to calculate the surface area of the ultrasonically synthesized catalyst (395 m2 g−1), and it was found to be greater than that of the non-ultrasonic synthesized catalyst (382 m2 g−1). The N2 adsorption-desorption isotherm indicated mesoporous structures. The SEM morphology at a similar magnification exhibited quite different shapes. In comparison to traditional methods, ultrasonic approaches produce higher yields in less time and use less energy. Furthermore, the effect of the preparation method of the 1%Pd-HPW/SiO2 catalyst was extensively studied with respect to the synthesis of octahydroquinazolinones. Excellent product yields, a fast reaction time, and simple work-up methods are some peculiarities associated with the ultrasonically synthesized catalyst. The recycling study was also investigated and found suitable for up to four reaction cycles.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111273
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1274: Enhancement of Biological Pretreatment on
           Biomass by an Ionic Liquid or Surfactant

    • Authors: Ken-Lin Chang, Chun-Hung Liu, Paripok Phitsuwan, Khanok Ratanakhanokchai, Yung-Chang Lin, Cheng-Di Dong, Ming-Hsun Lin, Gordon C. C. Yang
      First page: 1274
      Abstract: Fungal delignification can be a feasible process to pretreat biomass for bioethanol production if its performance is improved in terms of efficiency through a few modifications. The aim of this study was to enhance the biodelignification pretreatment of rice straw using laccase in the presence of ionic liquid (1-Allyl-3-methylimidazolium chloride, [AMIM]Cl) or surfactant (TritonX-100). Addition of 750 mg/L [AMIM]Cl and 500 mg/L TritonX-100 increases the lignin removal to 18.49% and 31.79%, which is higher than that of laccase only (11.97%). The enzymatic saccharification process was carried out based on different strategies. The highest cellulose conversion, 40.96%, 38.24%, and 37.91%, was obtained after 72 h of enzymatic saccharification when the substrate was washed with distilled water after pretreatment of rice straw with laccase + TritonX-100, laccase + [AMIM]Cl, and laccase only, respectively. In addition, the morphology and structure changes of pretreated and untreated rice straw were studied. Both surface area and cellulose crystallinity are substantially altered after laccase + [AMIM]Cl and laccase + TritonX-100 pretreatment. Enhanced saccharification efficiency of rice straw was achieved by laccase pretreatment with ionic liquid or surfactant in a single system.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111274
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1275: Recent Development in Sludge Biochar-Based
           Catalysts for Advanced Oxidation Processes of Wastewater

    • Authors: Chen, Fu, Yu, Wu, Li, Jin, Yang, Wang, Chen
      First page: 1275
      Abstract: Sewage sludge as waste of the wastewater treatment process contains toxic substances, and its conversion into sludge biochar-based catalysts is a promising strategy that merges the merits of waste reutilization and environmental cleanup. This study aims to systematically recapitulate the published articles on the development of sludge biochar-based catalysts in different advanced oxidation processes of wastewater, including sulfate-based system, Fenton-like systems, photocatalysis, and ozonation systems. Due to abundant functional groups, metal phases and unique structures, sludge biochar-based catalysts exhibit excellent catalytic behavior for decontamination in advanced oxidation systems. In particular, the combination of sludge and pollutant dopants manifests a synergistic effect. The catalytic mechanisms of as-prepared catalysts in these systems are also investigated. Furthermore, initial solution pH, catalyst dosage, reaction temperature, and coexisting anions have a vital role in advanced oxidation processes, and these parameters are systematically summarized. In summary, this study could provide relatively comprehensive and up-to-date messages for the application of sludge biochar-based catalysts in the advanced oxidation processes of wastewater treatment.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111275
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1276: Ambient Air Purification by
           Nanotechnologies: From Theory to Application

    • Authors: Cao, Huang, Zhang
      First page: 1276
      Abstract: Air pollution has been a recurring problem in northern Chinese cities, and high concentrations of PM2.5 in winter have been a particular cause for concern. Secondary aerosols converted from precursor gases (i.e., nitrogen oxides and volatile organic compounds) evidently account for a large fraction of the PM2.5. Conventional control methods, such as dust removal, desulfurization, and denitrification, help reduce emissions from stationary combustion sources, but these measures have not led to decreases in haze events. Recent advances in nanomaterials and nanotechnology provide new opportunities for removing fine particles and gaseous pollutants from ambient air and reducing the impacts on human health. This review begins with overviews of air pollution and traditional abatement technologies, and then advances in ambient air purification by nanotechnologies, including filtration, adsorption, photocatalysis, and ambient-temperature catalysis are presented—from fundamental principles to applications. Current state-of-the-art developments in the use of nanomaterials for particle removal, gas adsorption, and catalysis are summarized, and practical applications of catalysis-based techniques for air purification by nanomaterials in indoor, semi-enclosed, and open spaces are highlighted. Finally, we propose future directions for the development of novel disinfectant nanomaterials and the construction of advanced air purification devices.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111276
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1277: Roles of Nanostructured Bimetallic
           Supported on Alumina-Zeolite (AZ) in Light Cycle Oil (LCO) Upgrading

    • Authors: Pu, Zhang, Wang, Rogers, Wang, Wang, Ng, Sun
      First page: 1277
      Abstract: Light cycle oil (LCO) is one of the major products in Fluid catalytic cracking (FCC) processes, and has drawbacks such as high aromatics, sulfur, and nitrogen contents, and low cetane number (CN). Hydro-upgrading is one of the most typical processes for LCO upgrading, and alumina-zeolite (AZ) is an effective hydrotreating catalyst support. This paper examined the effects of different bimetallic catalysts (CoMo/AZ, NiMo/AZ, and NiW/AZ) supported by AZ on hydro-upgrading of both model compounds and real LCO. CoMo/AZ preferred the direct desulfurization (DDS) route while the NiMo/AZ and NiW/AZ catalysts favored the desulfurization route through hydrogenation (HYD). The presence of nitrogen compounds in the feed introduced a competitive adsorption mechanism and reduced the number of available acid sites. Aromatics were partially hydrogenated into methyltetralines at first, and then further hydrogenated, cracked, and isomerized into methyldecalins, monocyclic, and methyltetralines isomers. CoMo/AZ is the best hydrodesulfurization (HDS) catalyst for the model compounds at low H2 pressure (550 psi) and for LCO at lower temperature (573 K), while NiMo/AZ performs the best for LCO at higher temperature (648 K). NiMo/AZ is the best hydrodenitrogenation (HDN) catalyst for LCO. The hydrodearomatization (HDA) performances of NiMo/AZ and NiW/AZ improved significantly and overwhelmingly higher than that of the CoMo/AZ when the H2 pressure was increased to 1100 psi.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111277
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1278: Dual-Modified Cu2S with MoS2 and Reduced
           Graphene Oxides as Efficient Photocatalysts for H2 Evolution Reaction

    • Authors: Enna Ha, Zongyuan Xin, Danyang Li, Jingge Zhang, Tao Ji, Xin Hu, Luyang Wang, Junqing Hu
      First page: 1278
      Abstract: Noble metal-free cocatalysts have drawn great interest in accelerating the catalytic reactions of metal chalcogenide semiconductor photocatalyst. In particular, great efforts have been made on modifying a semiconductor with dual cocatalysts, which show synergistic effect of a fast transfer of exciton and energy simultaneously. Herein, we report the dual-modified Cu2S with MoS2 and reduced graphene oxides (Cu2S-MoS2/rGO). The in situ growth of Cu2S nanoparticles in the presence of MoS2/rGO resulted in high density of nanoscale interfacial contacts among Cu2S nanoparticles, MoS2, and rGO, which is beneficial for reducing the photogenerated electrons’ and holes’ recombination. The Cu2S-MoS2/rGO system also demonstrated stable photocatalytic activity for H2 evolution reaction for the long term.
      Citation: Catalysts
      PubDate: 2021-10-22
      DOI: 10.3390/catal11111278
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1279: Photocatalytic Activity of n-Alkylamine
           and n-Alkoxy Derivatives of Layered Perovskite-like Titanates H2Ln2Ti3O10
           (Ln = La, Nd) in the Reaction of Hydrogen Production From an Aqueous
           Solution of Methanol

    • Authors: Kurnosenko, Voytovich, Silyukov, Rodionov, Kirichenko, Minich, Malygina, Khramova, Zvereva
      First page: 1279
      Abstract: Two series of hybrid inorganic-organic derivatives, obtained via the modification of protonated Ruddlesden–Popper phases H2Ln2Ti3O10 (Ln = La, Nd) with intercalated n-alkylamines and grafted n-alkoxy groups, have been systematically investigated in relation to photocatalytic hydrogen production from a model of 1 mol % aqueous solution of methanol for the first time. Photocatalytic measurements were performed both for bare samples and for their composites with Pt nanoparticles as a cocatalyst using an advanced scheme, including dark stages, monitoring of the volume concentration of the sample in the reaction suspension during the experiment, shifts of its pH and possible exfoliation of layered compounds into nanolayers. It was found that the incorporation of organic components into the interlayer space of the titanates increases their photocatalytic activity up to 117 times compared with that of the initial compounds. Additional platinization of the hybrid samples’ surface allowed for achieving apparent quantum efficiency of hydrogen evolution of more than 40%. It was established that the photocatalytic activity of the hybrid samples correlates with the hydration degree of their interlayer space, which is considered a separate reaction zone in photocatalysis, and that hydrogen indeed generates from the aqueous methanol solution rather than from organic components of the derivatives.
      Citation: Catalysts
      PubDate: 2021-10-23
      DOI: 10.3390/catal11111279
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1280: Activation of Pt Nanoclusters on TiO2 via
           Tuning the Metallic Sites to Promote Low-Temperature CO Oxidation

    • Authors: Kailin He, Qingyue Wang
      First page: 1280
      Abstract: Metallic Pt sites are imperative in the CO oxidation reaction. Herein, we demonstrate the tuning of Pt sites by treating a Pt catalyst in various reductive atmospheres, influencing the catalyst activities in low-temperature CO oxidation. The H2 pretreatment of Pt clusters at 200 °C decreases the T50 from 208 °C to 183 °C in the 0.1 wt % Pt/TiO2 catalyst. The T50 shows a remarkable improvement using a CO pretreatment, which decreases the T50 further to 135 °C. A comprehensive characterization study reveals the integrated reasons behind this phenomenon: (i) the extent of PtO transition to metallic Pt sites, (ii) the ample surface active oxygen triggered by metallic Pt, (iii) the CO selectively adsorbs on metallic Pt sites which participate in low-temperature CO oxidation, and (iv) the formation of the unstable intermediate such as bicarbonate, contributes together to the enhanced activity of CO pretreated Pt/TiO2.
      Citation: Catalysts
      PubDate: 2021-10-23
      DOI: 10.3390/catal11111280
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1281: Impact of TiO2 Surface Defects on the
           Mechanism of Acetaldehyde Decomposition under Irradiation of a Fluorescent
           Lamp

    • Authors: Piotr Rychtowski, Beata Tryba, Hubert Fuks, Maria Ángeles Lillo-Ródenas, Maria Carmen Román-Martínez
      First page: 1281
      Abstract: TiO2 was placed in heat-treatment at the temperature of 400–500 °C under flow of hydrogen gas in order to introduce some titania surface defects. It was observed that hole centers in TiO2 were created during its heat treatment up to 450 °C, whereas at 500 °C some Ti3+ electron surface defects appeared. The type of titania surface defects had a great impact on the mechanism of acetaldehyde decomposition under irradiation of artificial visible light. Formation of O•− defects improved both acetaldehyde decomposition and mineralization due to the increased oxidation of adsorbed acetaldehyde molecules by holes. Contrary to that, the presence of electron traps and oxygen vacancies in titania (Ti3+ centers) was detrimental for its photocatalytic properties towards acetaldehyde decomposition. It was proved that transformation of acetaldehyde on the TiO2 with Ti3+ defects proceeded through formation of butene complexes, similar as on rutile-type TiO2. Formed acetic acid, upon further oxidation of butene complexes, was strongly bound with the titania surface and showed high stability under photocatalytic process. Therefore, titania sample heat-treated with H2 at 500 °C showed much lower photocatalytic activity than that prepared at 450 °C. This study indicated the great impact of titania surface defects (hole traps) in the oxidation of acetaldehyde and opposed one in the case of defects in the form of Ti3+ and oxygen vacancies. Oxidation abilities of TiO2 seem to be important in the photocatalytic decomposition of volatile organic compounds (VOCs) such as acetaldehyde.
      Citation: Catalysts
      PubDate: 2021-10-23
      DOI: 10.3390/catal11111281
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1282: Enhanced In Vitro Cascade Catalysis of
           Glycerol into Pyruvate and Acetoin by Integration with Dihydroxy Acid
           Dehydratase from Paralcaligenes ureilyticus

    • Authors: Shiting Guo, Xiaoxu Tan, Yuxian Wang, Kai Li, Chuanjuan Lü, Cuiqing Ma, Chao Gao
      First page: 1282
      Abstract: Recently, an in vitro enzymatic cascade was constructed to transform glycerol into the high-value platform chemical pyruvate. However, the low activity of dihydroxy acid dehydratase from Sulfolobus solfataricus (SsDHAD) limited the efficiency. In this study, the enzymatic reduction of pyruvate catalyzed by d-lactate dehydrogenase from Pseudomonas aeruginosa PAO1 was used to assay the activities of dihydroxy acid dehydratases. Dihydroxy acid dehydratase from Paralcaligenes ureilyticus (PuDHT) was identified as the most efficient candidate for glycerate dehydration. After the optimization of the catalytic temperature for the enzymatic cascade, comprising alditol oxidase from Streptomyces coelicolor A3, PuDHT, and catalase from Aspergillus niger, 20.50 ± 0.27 mM of glycerol was consumed in 4 h to produce 18.95 ± 0.97 mM of pyruvate with a productivity 12.15-fold higher than the previous report using SsDHAD. The enzymatic cascade was further coupled with the pyruvate decarboxylase from Zymomonas mobile for the production of another platform compound, acetoin. Acetoin at a concentration of 8.52 ± 0.12 mM was produced from 21.62 ± 0.19 mM of glycerol with a productivity of 1.42 ± 0.02 mM h−1.
      Citation: Catalysts
      PubDate: 2021-10-23
      DOI: 10.3390/catal11111282
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1283: Recent Advances in WS2 and Its Based
           Heterostructures for Water-Splitting Applications

    • Authors: Zeineb Thiehmed, Abdul Shakoor, Talal Altahtamouni
      First page: 1283
      Abstract: The energy from fossil fuels has been recognized as a main factor of global warming and environmental pollution. Therefore, there is an urgent need to replace fossil fuels with clean, cost-effective, long-lasting, and environmentally friendly fuel to solve the future energy crisis of the world. Therefore, the development of clean, sustainable, and renewable energy sources is a prime concern. In this regard, solar energy-driven hydrogen production is considered as an overriding opening for renewable and green energy by virtue of its high energy efficiency, high energy density, and non-toxicity along with zero emissions. Water splitting is a promising technology for producing hydrogen, which represents a potentially and environmentally clean fuel. Water splitting is a widely known process for hydrogen production using different techniques and materials. Among different techniques of water splitting, electrocatalytic and photocatalytic water splitting using semiconductor materials have been considered as the most scalable and cost-effective approaches for the commercial production of sustainable hydrogen. In order to achieve a high yield of hydrogen from these processes, obtaining a suitable, efficient, and stable catalyst is a significant factor. Among the different types of semiconductor catalysts, tungsten disulfide (WS2) has been widely utilized as a catalytic active material for the water-splitting process, owing to its layered 2D structure and its interesting chemical, physical, and structural properties. However, WS2 suffers from some disadvantages that limit its performance in catalytic water splitting. Among the various techniques and strategies that have been constructed to overcome the limitations of WS2 is heterostructure construction. In this process, WS2 is coupled with another semiconducting material in order to facilitate the charge transfer and prevent the charge recombination, which will enhance the catalytic performance. This review aims to summarize the recent studies and findings on WS2 and its heterostructures as a catalyst in the electrocatalytic and photocatalytic water-splitting processes.
      Citation: Catalysts
      PubDate: 2021-10-24
      DOI: 10.3390/catal11111283
      Issue No: Vol. 11, No. 11 (2021)
       
  • Catalysts, Vol. 11, Pages 1184: Efficient 1-Hydroxy-2-Butanone Production
           from 1,2-Butanediol by Whole Cells of Engineered E. coli

    • Authors: Hui Lin, Jiayin Xu, Wenlian Sun, Wujia Hu, Huifang Gao, Kaihui Hu, Junzhi Qiu, Binbin Huang, Liaoyuan Zhang
      First page: 1184
      Abstract: 1-Hydroxy-2-butanone (HB) is a key intermediate for anti-tuberculosis pharmaceutical ethambutol. Commercially available HB is primarily obtained by the oxidation of 1,2-butanediol (1,2-BD) using chemical catalysts. In present study, seven enzymes including diol dehydrogenases, secondary alcohol dehydrogenases and glycerol dehydrogenase were chosen to evaluate their abilities in the conversion of 1,2-BD to HB. The results showed that (2R, 3R)- and (2S, 3S)-butanediol dehydrogenase (BDH) from Serratia sp. T241 could efficiently transform (R)- and (S)-1,2-BD into HB respectively. Furthermore, two biocatalysts co-expressing (2R, 3R)-/(2S, 3S)-BDH, NADH oxidase and hemoglobin protein in Escherichia coli were developed to convert 1,2-BD mixture into HB, and the transformation conditions were optimized. Maximum HB yield of 341.35 and 188.80 mM could be achieved from 440 mM (R)-1,2-BD and 360 mM (S)-1,2-BD by E. coli (pET-rrbdh-nox-vgb) and E. coli (pET-ssbdh-nox-vgb) under the optimized conditions. In addition, two biocatalysts showed the ability in chiral resolution of 1,2-BD isomers, and 135.68 mM (S)-1,2-BD and 112.43 mM (R)-1,2-BD with the purity of 100 % could be obtained from 300 and 200 mM 1,2-BD mixture by E. coli (pET-rrbdh-nox-vgb) and E. coli (pET-ssbdh-nox-vgb), respectively. These results provided potential application for HB production from 1,2-BD mixture and chiral resolution of (R)-1,2-BD and (S)-1,2-BD.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101184
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1185: The Role of Heterogeneous Catalytic
           Processes in the Green Hydrogen Economy

    • Authors: Eva Díaz, Salvador Ordóñez
      First page: 1185
      Abstract: In a recent United Nations draft report (August 2021), a large number of scientists from the Intergovernmental Panel on Climate Change described the climate change over the past century as “unprecedented” and warned that the world will warm at an increasing rate, with unpredictable results, unless aggressive action to cut emissions of carbon dioxide and other heat-trapping gases is taken [...]
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101185
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1186: TiO2@MOF Photocatalyst for the Synergetic
           Oxidation of Microcystin-LR and Reduction of Cr(VI) in Aqueous Media

    • Authors: Yarui Wang, Wanchao Yu, Fanglan Geng, Lixia Zhao, Yawei Wang
      First page: 1186
      Abstract: The coexistence of pollutants presents a great challenge to the implementation of photocatalysts. In this work, a novel MIL-101(Fe)/TiO2 composite prepared by in situ growth of MIL-101(Fe) on TiO2 was developed for the synergetic oxidation of MC-LR and Cr(VI) reduction. The heterojunction material shows elevated photocatalytic behavior under ultraviolet compared with the unary pollutant system. Furthermore, quenching experiments and electron spin resonance confirm that the enhanced photodegradation behavior is related to the synergistic effect between the photocatalytic reduction and oxidation process, in which MC-LR consumes the holes and Cr(VI) captures electrons, followed by efficient charge separation through the conventional double-transfer mechanism between MIL-101(Fe) and TiO2. This investigation provides a deeper understanding of the construction of MOFs/semiconductor heterojunctions for the pollutants removal in multi-component contaminants system.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101186
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1187: Engineering Pt-Bi2O3 Interface to Boost
           Cyclohexanone Selectivity in Oxidative Dehydrogenation of KA-Oil

    • Authors: Qiuyue Zhou, Zhi-Qiang Wang, Wei Hong, Baohui Lou, Shihui Zou
      First page: 1187
      Abstract: Oxidative dehydrogenation of KA-oil (a mixture of cyclohexanone and cyclohexanol) is an economically attractive process to produce cyclohexanone because it provides a chance to avoid the energy-intensive alcohol-ketone separation process. The application of this process, however, is hampered by the low cyclohexanone selectivity which results from the competitive adsorption of cyclohexanol and cyclohexanone on the catalyst surface. Herein, by engineering Pt-Bi2O3 interface to tune the geometric and electronic structure of Pt, we successfully weaken the cyclohexanone adsorption without compromising the oxidation of cyclohexanol. As a result, Bi2O3-Pt/SiO2 with Bi-to-Pd ratio of 0.2 exhibits a 5 times higher cyclohexanone selectivity than Pt/SiO2 at the same conversion of KA oil. Long term test suggests that the Pt-Bi2O3 interface is stable in the oxidative dehydrogenation of KA-oil.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101187
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1188: Metal-Organic Frameworks Derived Catalyst
           for High-Performance Vanadium Redox Flow Batteries

    • Authors: Yun-Ting Ou, Daniel Manaye Kabtamu, Anteneh Wodaje Bayeh, Hung-Hsien Ku, Yu-Lin Kuo, Yao-Ming Wang, Ning-Yih Hsu, Tai-Chin Chiang, Hsin-Chih Huang, Chen-Hao Wang
      First page: 1188
      Abstract: Vanadium redox flow battery (VRFB) is one of the most promising technologies for grid-scale energy storage applications because of its numerous attractive features. In this study, metal-organic frameworks (MOF)-derived catalysts (MDC) are fabricated using carbonization techniques at different sintering temperatures. Zirconium-based MOF-derived catalyst annealed at 900 °C exhibits the best electrochemical activity toward VO2+/VO2+ redox couple among all samples. Furthermore, the charge-discharge test confirms that the energy efficiency (EE) of the VRFB assembled with MOF-derived catalyst modified graphite felt (MDC-GF-900) is 3.9% more efficient than the VRFB using the pristine graphite felt at 100 mA cm−2. Moreover, MDC-GF-900 reveals 31% and 107% higher capacity than the pristine GF at 80 and 100 mA cm−2, respectively. The excellent performance of MDC-GF-900 results from the existence of oxygen-containing groups active sites, graphite structure with high conductivity embedded with zirconium oxide, and high specific surface area, which are critical points for promoting the vanadium redox reactions. Because of these advantages, MDC-GF-900 also possesses superior stability performance, which shows no decline of EE even after 100 cycles at 100 mA cm−2.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101188
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1189: Amperometric Oxygen Sensor Based on
           Bimetallic Pd-Cu/C Electrocatalysts

    • Authors: Yuan-Gee Lee, Ya-Tian Hou, Yu-Ching Weng
      First page: 1189
      Abstract: A laminated Pd-Cu alloy/C/Nafion multilayer was prepared to sense O2 atmosphere in a metal-air structure. As a matrix, palladium was doped with various amounts of copper to conduct a preliminary test with optimum response, and four compositions, Pd, Pd8Cu2, Pd6Cu4, and Pd5Cu5, were selected as the candidate electrodes. It was found that the Pd6Cu4/C electrode showed higher sensitivity for all the electrodes. According to the phase identification of X-ray diffraction and X-ray photoelectron spectroscopy tests, the high sensitivity was attributed to the doped Cu, which was merged into the Pd matrix to repel the Pd out of the matrix as a Pd-skin layer on the surface. In the Pd-Cu alloy, the Cu site served as a template reaction site to break the O-O bond and reduce the interaction force of adsorbated oxygen on the Pd site. During the oxygen reduction reaction, not only did the decomposition of O2 molecules occur on the electrode, but the electrode itself proceeded with a phase transformation to high valance of oxide, PdO3. The sensing potential for O2 sensing was determined by polarization curves in which the flat region resulting from a diffusion-control was adopted. Chronoamperometric measurements were employed to construct calibration curves for the selected electrodes. A successive response was measured to test the endurance, which showed appreciable sensitivity decay. We also tested the selectivity by introducing a series of disturbance gases, CO, SO2, and NO2, in which the Pd6Cu4 electrode prevailed over the other electrodes.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101189
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1190: Six Flux Model for the Central Lamp
           Reactor Applied to an External Four-Lamp Reactor

    • Authors: Fernando J. Beltrán, Javier Rivas, Juan-Fernando Garcia-Araya
      First page: 1190
      Abstract: One of the difficulties of establishing the intrinsic kinetics of photocatalytic oxidation processes is due to the complex mathematical formula used to determine the rate of photon absorption. To solve this problem, some models have been proposed and checked, such as the Six Flux Model (SFM) confirmed in central lamp photoreactors. External lamp photoreactors are also one of the most used configurations to study the photocatalytic oxidation of contaminants in water, and complex mathematical solutions have been reported to solve the rate of photon absorption. In this work, SFM Equations already reported for the central lamp photoreactor have been adapted to determine the rate of photon absorption in an external four-lamp photoreactor. The results obtained show slight differences from those of the Monte Carlo method. Additionally, once the rate of photon absorption was validated, the intrinsic rate constant and scavenging factor of the photocatalytic oxidation of some contaminant compounds from results already published have been determined.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101190
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1191: Non-Solvent Synthesis of a Robust
           Potassium-Doped PdCu-Pd-Cu@C Nanocatalyst for High Selectively Tandem
           Reactions

    • Authors: Sanha Jang, Dicky Annas, Sehwan Song, Jong-Seong Bae, Sungkyun Park, Kang Hyun Park
      First page: 1191
      Abstract: A non-solvent synthesis of alkali metal-doped PdCu-Pd-Cu@C is presented that needs no mechanical grinding and utilizes heat treatment under an N2 gas flow. Pluronic® F127 is used to generate pores and a high surface area, and tannic acid is used as a carbon source for the PdCu-Pd-Cu@C nanocatalysts. Because some C is transferred to organic compounds during the nitrogen heat treatment, this demonstrated the advantage of raising the weight ratio of active metals comparatively. The PdCu-Pd-Cu@C nanocatalyst developed in this study outperformed commercial Pd/C catalysts by bimetallic PdCu-Pd-Cu nanoparticles and Pd nanoparticles in terms of catalytic activity (selectivity of commercial Pd/C: 45%; PdCu-Pd-Cu@C nanocatalyst: 76%). The alkali metal dopants increase the selectivity of the final product on the PdCu-Pd-Cu@C surface because they are electron-rich, which assists in the adsorption of the substrate (selectivity of PdCu-Pd-Cu@C nanocatalyst: 76%; K-doped PdCu-Pd-Cu@C nanocatalysts: 90%). Furthermore, even after being reused 5 times in this research, the final catalytic performance was comparable to that of the initial catalyst.
      Citation: Catalysts
      PubDate: 2021-09-29
      DOI: 10.3390/catal11101191
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1192: Constitutive Expression in Komagataella
           phaffii of Mature Rhizopus oryzae Lipase Jointly with Its Truncated
           

    • Authors: Josu López-Fernández, Maria Dolors Benaiges, Francisco Valero
      First page: 1192
      Abstract: Rhizopus oryzae lipase (ROL) containing 28 C-terminal amino acids of the prosequence fused to the N-terminal mature sequence in ROL (proROL) was successfully expressed in the methylotrophic yeast Komagataella phaffii (Pichia pastoris) under the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter (PGAP). Although the sequence encoding the mature lipase (rROL) was also transformed, no clones were obtained after three transformation cycles, which highlights the importance of the truncated prosequence to obtain viable transformed clones. Batch cultures of the K. phaffii strain constitutively expressing proROL scarcely influenced growth rate and exhibited a final activity and volumetric productivity more than six times higher than those obtained with proROL from K. phaffii under the methanol-inducible alcohol oxidase 1 promoter (PAOX1). The previous differences were less marked in fed-batch cultures. N-terminal analysis confirmed the presence of the 28 amino acids in proROL. In addition, immobilized proROL exhibited increased tolerance of organic solvents and an operational stability 0.25 and 3 times higher than that of immobilized rROL in biodiesel and ethyl butyrate production, respectively. Therefore, the truncated prosequence enables constitutive proROL production, boosts bioprocess performance and provides a more stable biocatalyst in two reactions in which lipases are mostly used at industrial level, esterification (ethyl butyrate) and transesterification (biodiesel).
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101192
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1193: Acesulfame K Photodegradation over
           Nitrogen-Doped TiO2

    • Authors: Katarzyna Pstrowska, Hanna Czapor-Irzabek, Daniel Borowiak, Ewa Burchacka
      First page: 1193
      Abstract: Acesulfame K is a zero-calorie alternative to sugar used worldwide. There is contradictory information on the toxicity of the compound, but its accumulation in the aquatic environment is undeniable. In this study, one-pot sol-gel synthesis was used to obtain nitrogen-doped TiO2 photocatalysts. Doping up to 6.29 wt % of nitrogen caused an increase in the surface area of the catalysts (48.55–58.23 m2∙g−1) and a reduction of the pHPZC value (5.72–5.05). Acesulfame K photodegradation was tested at the initial concentration of 20–100 ppm and the catalyst concentration at the level of 1 g∙L−1. Compared to the pure anatase, 4.83–6.29 wt % nitrogen-doped TiO2 showed an effective photodegradation of Acesulfame K. Ninety percent molecule removal was obtained after ~100 min, ~90 min, and ~80 min for initial concentrations of 20 ppm, 50 ppm, and 100 ppm, respectively. The increased activity of the catalysts is due to the modification of the TiO2 lattice structure and probably the limitation of the photogenerated electron/hole charge carrier recombination. It was shown that the electrostatic interactions between Acesulfame K and the catalyst surface play an important role in the photodegradation efficiency.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101193
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1194: Cutinases: Characteristics and Insights in
           Industrial Production

    • Authors: Alejandro Martínez, Sergi Maicas
      First page: 1194
      Abstract: Cutinases (EC 3.1.1.74) are serin esterases that belong to the α/β hydrolases superfamily and present in the Ser-His-Asp catalytic triad. They show characteristics between esterases and lipases. These enzymes hydrolyze esters and triacylglycerols and catalyze esterification and transesterification reactions. Cutinases are synthesize by plant pathogenic fungi, but some bacteria and plants have been found to produce cutinases as well. In nature they facilitate a pathogen’s invasion by hydrolyzing the cuticle that protects plants, but can be also used for saprophytic fungi as a way to nourish themselves. Cutinases can hydrolyze a wide range of substrates like esters, polyesters, triacylglycerols and waxes and that makes this enzyme very attractive for industrial purposes. This work discusses techniques of industrial interest such as immobilization and purification, as well as some of the most important uses of cutinases in industries.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101194
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1195: Synthesis and Characterization of Silver
           Nanoparticles Prepared with Carrasquilla Fruit Extract (Berberis hallii)
           and Evaluation of Its Photocatalytic Activity

    • Authors: Geovanna Arroyo, Yolanda Angulo, Alexis Debut, Luis Heriberto Cumbal
      First page: 1195
      Abstract: In this study, silver nanoparticles (AgNPs) were obtained using a green-chemistry procedure. For this protocol, the Carrasquilla extract (CE) (Berberis hallii) and a AgNO3 solution were used as the reducing agent and the metal precursor, respectively. The as-prepared AgNPs after characterization were then used to evaluate the degradation of the methylene blue (MB), the safranin (SF), and the mixture of both dyes in the aqueous phase under solar light irradiation. The photocatalytic activity of AgNPs for the degradation of the MB (k = 0.0092 min−1) was higher than the SF (k = 0.00016 min−1) due to the susceptibility of the thiazine ring of the MB to photodegradation contrasted to the phenyl phenazine of the SF. However, SF was mostly removed by adsorption with a maximum uptake of 2907 mg/g. Overall, this eco-friendly and green conversion of silver ions to metallic elements avoids the use of toxic chemicals and could be applied for the degradation/adsorption of dyes used in several industrial processes.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101195
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1196: Hybrid Structure of TiO2-Graphitic Carbon
           

    • Authors: Su-Jin Jang, Yun Chan Kang, Jin-Su Hyun, Tae Ho Shin, Young Wook Lee, Kwang Chul Roh
      First page: 1196
      Abstract: The durability of catalysts in fuel cells is a longstanding issue that needs to be resolved. Catalyst stability of the fuel cell has always been a problem, studies are underway to address them. Herein, to address this issue, we synthesize a hybrid structure consisting of SP carbon (SP) as the graphitic carbon and TiO2 as the metal oxide using a microwave method for use as a support for Pt nanoparticles. Anatase TiO2 and Pt nanoparticles with sizes of ~5 and 3.5 ± 1.4 nm, respectively, are uniformly dispersed on a modified graphitic SP carbon support (Pt-TiO2-SP). This supported Pt catalyst exhibits significantly improves durability in the oxygen reduction reaction (ORR). Furthermore, the Pt-TiO2-SP carbon hybrid catalyst manifests superior electrocatalytic stability and higher onset potential in ORR than those exhibited by Pt-SP carbon without TiO2. Pt-TiO2-SP exhibits an activity loss of less than 68 mV after 5000 electrochemical cycles, whereas an activity loss of ~100 mV is observed for Pt-SP carbon in a stability test. These results suggest that the strong metal–support interaction in TiO2-supported Pt catalyst significantly enhances the activity of Pt nanocatalyst.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101196
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1197: Enzymatic Hydrogen Electrosynthesis at
           Enhanced Current Density Using a Redox Polymer

    • Authors: John C. Ruth, Fabian M. Schwarz, Volker Müller, Alfred M. Spormann
      First page: 1197
      Abstract: High-temperature tolerant enzymes offer multiple advantages over enzymes from mesophilic organisms for the industrial production of sustainable chemicals due to high specific activities and stabilities towards fluctuations in pH, heat, and organic solvents. The production of molecular hydrogen (H2) is of particular interest because of the multiple uses of hydrogen in energy and chemicals applications, and the ability of hydrogenase enzymes to reduce protons to H2 at a cathode. We examined the activity of Hydrogen-Dependent CO2 Reductase (HDCR) from the thermophilic bacterium Thermoanaerobacter kivui when immobilized in a redox polymer, cobaltocene-functionalized polyallylamine (Cc-PAA), on a cathode for enzyme-mediated H2 formation from electricity. The presence of Cc-PAA increased reductive current density 340-fold when used on an electrode with HDCR at 40 °C, reaching unprecedented current densities of up to 3 mA·cm−2 with minimal overpotential and high faradaic efficiency. In contrast to other hydrogenases, T. kivui HDCR showed substantial reversibility of CO-dependent inactivation, revealing an opportunity for usage in gas mixtures containing CO, such as syngas. This study highlights the important potential of combining redox polymers with novel enzymes from thermophiles for enhanced electrosynthesis.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101197
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1198: Mo-doped CuO Nanomaterial for
           Photocatalytic Degradation of Water Pollutants under Visible Light

    • Authors: Mudassar Maraj, Ahmad Raza, Xinjie Wang, Jie Chen, Khalid Riaz, Wenhong Sun
      First page: 1198
      Abstract: Recently, metal oxide-based nano-photocatalysts have gained a great deal of attention in waste water remediation due to their outstanding properties. In this report, a novel Mo-doped CuO nanomaterial was successfully prepared and utilized for the degradation of methylene blue water pollutant. The molybdenum content was varied from 1–5 wt.% to obtain the desired modified CuO based nanomaterials. The crystalline structures of as prepared materials were investigated using the XRD technique, which explored the successful fabrication of monoclinic-structure-based CuO nanomaterials. For morphological studies, SEM and HRTEM were used, which proved the successful preparation of nanoparticles-based material. SAED was used to check the crystallinity of the sample. EDX and XPS analyses were performed to evaluate the elemental composition of Mo-doped CuO nanomaterials. The optical characteristics were explored via UV-vis and PL techniques. These studies showed that the energy bandgap of CuO decreased from 1.55 eV to 1.25 eV due to Mo doping. The photocatalytic efficiency of Mo-doped CuO nanomaterials was evaluated by degrading methylene blue (MB) under visible light-irradiation. Among different Mo-doped CuO based nanomaterials, the 4 wt.% Mo-doped CuO sample showed the highest degradation activity against MB dye. These results verified that the optimized material can be used for photocatalytic applications, especially for the purification of waste water.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101198
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1199: Enhanced Thermostability of Pseudomonas
           nitroreducens Isoeugenol Monooxygenase by the Combinatorial Strategy of
           Surface Residue Replacement and Consensus Mutagenesis

    • Authors: Xin-Yi Lu, Xiao-Mei Wu, Bao-Di Ma, Yi Xu
      First page: 1199
      Abstract: Vanillin has many applications in industries. Isoeugenol monooxygenase (IEM) can catalyze the oxidation of isoeugenol to vanillin in the presence of oxygen under mild conditions. However, the low thermal stability of IEM limits its practical application in the biosynthesis of natural vanillin. Herein, two rational strategies were combined to improve the thermostability of IEM from Pseudomonas nitroreducens Jin1. Two variants (K83R and K95R) with better thermostability and one mutant (G398A) with higher activity were identified from twenty candidates based on the Surface Residue Replacement method. According to the Consensus Mutagenesis method, one mutant (I352R) with better thermostability and another mutant (L273F) with higher activity were also identified from nine candidates. After combinatorial mutation, a triple mutant K83R/K95R/L273F with the best thermostability and catalytic efficiency was generated. Compared with the wild-type IEM, the thermal inactivation half-lives (t1/2) of K83R/K95R/L273F at 25 °C, 30 °C, and 35 °C increased 2.9-fold, 11.9-fold, and 24.7-fold, respectively. Simultaneously, it also exhibited a 4.8-fold increase in kcat, leading to a 1.2-fold increase in catalytic efficiency (kcat/Km). When the whole cell of K83R/K95R/L273F was applied to the biotransformation of isoeugenol on preparative scale, the vanillin concentration reached 240.1 mM with space-time yield of 109.6 g/L/d, and vanillin was achieved in 77.6% isolated yield and >99% purity.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101199
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1200: Synthesis of 2-Methylquinoxaline
           Derivatives from Glycerol and Diamines Catalyzed by Iridium Complexes
           Bearing an N-Heterocyclic Carbene Ligand

    • Authors: Toshiki Tanaka, Akane Enomoto, Shohichi Furukawa, Ken-ichi Fujita
      First page: 1200
      Abstract: 2-Methylquinoxaline derivatives are widely used as intermediates in the synthesis of pharmaceuticals, natural products, and dyes; however, their syntheses usually require excess reagents, making them environmentally burdensome. Meanwhile, glycerol can be sustainably obtained in large quantities as a by-product in the production of biodiesel fuel using waste oil as a raw material. Thus, it is worthwhile to develop a new catalytic system that utilizes glycerol as a C3 source. In this study, an efficient catalytic system was developed to obtain 2-methylquinoxaline derivatives from glycerol and 1,2-phenylenediamines. This system is beneficial because it is environmentally friendly and has excellent atom efficiency.
      Citation: Catalysts
      PubDate: 2021-09-30
      DOI: 10.3390/catal11101200
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1201: Optimization of Hydroperoxide Lyase
           Production for Recombinant Lipoxygenase Pathway Cascade Application

    • Authors: Veronika Kazimírová, Viktória Zezulová, Vladimír Krasňan, Vladimír Štefuca, Martin Rebroš
      First page: 1201
      Abstract: Cis-3-hexenal and its more stable isomer, trans-2-hexenal, are highly valued chemicals used in the food and perfume industries. They are produced by the plant lipoxygenase pathway, where two enzymes, lipoxygenase (LOX) and hydroperoxide lyase (HPL), are involved. However, the application of this pathway is limited, especially due to the instability of HPL. This enzyme belongs to the cytochrome P450 enzyme family and needs heme as a prosthetic group. Its synthesis must be effectively performed by a host organism in order to produce an active protein. In this work, Pseudomonas aeruginosa LOX was expressed in Escherichia coli BL21(DE3), and whole cells were used for the synthesis of 13(S)-hydroperoxy-(Z,E,Z)-9,11,15-octadecatrienoic acid (13-HPOT) as a substrate for HPL. Expression of Psidium guajava HPL was carried out by recombinant E. coli JM109(DE3) in autoinduction media, and the influence of the addition of heme precursors δ-ALA and FeII+ was studied. Specific activity of whole cells expressing HPL was measured by the direct use of a synthesized 13-HPOT solution (2.94 mM of total hydroperoxides, 75.35% of 13-HPOT (2.22 mM)) and increased 2.6-fold (from 61.78 U·mg−1 to 159.95 U·mg−1) with the addition of 1 mM FeII+ to the autoinduction media. Productivity and activity were further enhanced by an increase in the expression temperature, and a total of 3.30·105 U·dm−3 of culture media was produced in the optimized process.
      Citation: Catalysts
      PubDate: 2021-10-01
      DOI: 10.3390/catal11101201
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1202: Statistical Modeling and Performance
           Optimization of a Two-Chamber Microbial Fuel Cell by Response Surface
           Methodology

    • Authors: Muhammad Nihal Naseer, Asad A. Zaidi, Hamdullah Khan, Sagar Kumar, Muhammad Taha bin Owais, Yasmin Abdul Wahab, Kingshuk Dutta, Juhana Jaafar, Nor Aliya Hamizi, Mohammad Aminul Islam, Hanim Hussin, Irfan Anjum Badruddin, Hussein Alrobei
      First page: 1202
      Abstract: Microbial fuel cell, as a promising technology for simultaneous power production and waste treatment, has received a great deal of attention in recent years; however, generation of a relatively low power density is the main limitation towards its commercial application. This study contributes toward the optimization, in terms of maximization, of the power density of a microbial fuel cell by employing response surface methodology, coupled with central composite design. For this optimization study, the interactive effect of three independent parameters, namely (i) acetate concentration in the influent of anodic chamber; (ii) fuel feed flow rate in anodic chamber; and (iii) oxygen concentration in the influent of cathodic chamber, have been analyzed for a two-chamber microbial fuel cell, and the optimum conditions have been identified. The optimum value of power density was observed at an acetate concentration, a fuel feed flow rate, and an oxygen concentration value of 2.60 mol m−3, 0.0 m3, and 1.00 mol m−3, respectively. The results show the achievement of a power density of 3.425 W m−2, which is significant considering the available literature. Additionally, a statistical model has also been developed that correlates the three independent factors to the power density. For this model, R2, adjusted R2, and predicted R2 were 0.839, 0.807, and 0.703, respectively. The fact that there is only a 3.8% error in the actual and adjusted R2 demonstrates that the proposed model is statistically significant.
      Citation: Catalysts
      PubDate: 2021-10-01
      DOI: 10.3390/catal11101202
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1203: Synergistic Effects of Curcumin and
           Nano-Curcumin against Toxicity, Carcinogenicity, and Oxidative Stress
           Induced by Tartrazine at Normal and Cancer Cell Levels

    • Authors: Gaber E. El-Desoky, Saikh M. Wabaidur, Mohamed A. Habila, Zeid A. AlOthman
      First page: 1203
      Abstract: In this study, the cellular synergistic and antagonistic effects of mixing tartrazine (TZ) with curcumin (CUR) or curcumin-nanoparticles (CUR-NPs) were investigated. The in vivo administration of TZ, CUR, CUR-NPs, and TZ mixed with CUR or CUR-NPs at 75:25 or 50:50 ratios were tested. The results indicated that CUR and CUR -NPs reduced the cytotoxicity effects of TZ on skin fibroblast BJ-1 (ATCC® CRL-2522™) normal cells. However, among the tested materials, CUR-NPs had highest in vitro and in vivo antioxidant activity compared to TZ. Furthermore, CUR-NPs and CUR exhibited anticancer activity against HepG-2 liver cancer cells via apoptosis induction. The key apoptosis protein genes Caspase-3, p53, and Bax were upregulated, whereas Bc-2, which exhibits anti-apoptosis activity, was downregulated. Our results indicated that the nano-formulation of CUR alters its physicochemical properties, including the size and shape, and increases its antioxidant and anticancer properties. CUR-NPs also overcome the side effect of using TZ as a yellow color and food preservative additive, due to its reduced toxicity, oxidative stress, and carcinogenicity. In agreement with our previous findings, CUR and CUR-NPs were able to protect against cellular oxidative stress by stimulating endogenous antioxidant defense enzymes, including superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione-S-transferase (GST). We conclude that the nano-formulation of CUR exhibits economic benefits as a new strategy to use CUR as a food additive at the cellular level.
      Citation: Catalysts
      PubDate: 2021-10-01
      DOI: 10.3390/catal11101203
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1204: How Many Molecules Can Fit in a Zeolite
           Pore' Implications for the Hydrocarbon Pool Mechanism of the
           Methanol-to-Hydrocarbons Process

    • Authors: Stewart Parker, Aleena Kombanal
      First page: 1204
      Abstract: The methanol-to-hydrocarbons (MTH) process is a very advantageous way to upgrade methanol to more valuable commodity chemicals such as light alkenes and gasoline. There is general agreement that, at steady state, the process operates via a dual cycle “hydrocarbon pool” mechanism. This mechanism defines a minimum number of reactants, intermediates, and products that must be present for the reaction to occur. In this paper, we calculate (by three independent methods) the volume required for a range of compounds that must be present in a working catalyst. These are compared to the available volume in a range of zeolites that have been used, or tested, for MTH. We show that this straightforward comparison provides a means to rationalize the product slate and the deactivation pathways in zeotype materials used for the MTH reaction.
      Citation: Catalysts
      PubDate: 2021-10-03
      DOI: 10.3390/catal11101204
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1205: Mesoporous TiO2 Implanted ZnO QDs for the
           Photodegradation of Tetracycline: Material Design, Structural
           Characterization and Photodegradation Mechanism

    • Authors: Anwar Iqbal, Usman Saidu, Srimala Sreekantan, Mohammad Norazmi Ahmad, Marzaini Rashid, Naser M. Ahmed, Wan Hazman Danial, Lee D. Wilson
      First page: 1205
      Abstract: A sol-gel method was used to prepare a mesoporous TiO2 implanted with a ZnO quantum dot photocatalyst (TZQ) for the photodegradation of tetracycline (TC) under fluorescent light irradiation. Scanning electron microscopy (SEM) shows the presence of cavities on the photocatalyst surface due to the use of starch as a synthetic template, where the nitrogen sorption results indicate that TZQ contains mesopores with reduced size (ca. 4.3 nm) versus the pore size of the parent meso-TiO2 (ca. 7.5 nm). The addition of ZnO quantum dots (QDs) resulted in spherically-shaped binary composite particles in layers onto the surface of TiO2. The coexistence of the ZnO QDs and TiO2 phase was observed using high resolution-transmission electron microscopy (HR-TEM). The photodegradation of TC was carried out in a homemade reactor equipped with two fluorescent lights (24 W each) and within 90 min of irradiation, 94.6% of TC (40 mg L−1) was photodegraded using 250 mg L−1 of TZQ at pH 9. The major reactive oxygen species identified from the scavenging tests were O2●− followed by HO●. The deconvolution of the photoluminescence spectrum of TZQ indicates the presence of a strong quantum confinement effect (QCE) of the ZnO QDs, a defect related to Ti-species and oxygen. The analysis of the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS) suggest two photodegradation pathways. The pathways were validated using the Fukui function approach and the Wheland localisation approach. This simple and efficient photocatalytic technology is anticipated to benefit small-scale animal husbandries and aquaculture operators that have limited access to sustainable water treatment technology.
      Citation: Catalysts
      PubDate: 2021-10-08
      DOI: 10.3390/catal11101205
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1206: Photo-Fenton-Like Treatment of Municipal
           Wastewater

    • Authors: Yerkanat N. Kanafin, Ardak Makhatova, Vasilios Zarikas, Elizabeth Arkhangelsky, Stavros G. Poulopoulos
      First page: 1206
      Abstract: In this work, the photochemical treatment of a real municipal wastewater using a persulfate-driven photo-Fenton-like process was studied. The wastewater treatment efficiency was evaluated in terms of total carbon (TC), total organic carbon (TOC) and total nitrogen (TN) removal. Response surface methodology (RSM) in conjunction Box-Behnken design (BBD) and multilayer artificial neural network (ANN) have been utilized for the optimization of the treatment process. The effects of four independent factors such as reaction time, pH, K2S2O8 concentration and K2S2O8/Fe2+ molar ratio on the TC, TOC and TN removal have been investigated. The process significant factors have been determined implementing Analysis of Variance (ANOVA). Both RSM and ANN accurately found the optimum conditions for the maximum removal of TOC (100% and 98.7%, theoretically), which resulted in complete mineralization of TOC at the reaction time of 106.06 min, pH of 7.7, persulfate concentration of 30 mM and K2S2O8/Fe2+ molar ratio of 7.5 for RSM and at the reaction time of 104.93 min, pH of 7.7, persulfate concentration of 30 mM and K2S2O8/Fe2+ molar ratio of 9.57 for ANN. On the contrary, the attempts to find the optimal conditions for the maximum TC and TN removal using statistical, and neural network models were not successful.
      Citation: Catalysts
      PubDate: 2021-10-08
      DOI: 10.3390/catal11101206
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1207: What Is the Real State of Single-Atom
           Catalysts under Electrochemical Conditions—From Adsorption to Surface
           Pourbaix Plots'

    • Authors: Ana S. Dobrota, Tanja Đokić, Natalia V. Skorodumova, Slavko V. Mentus, Igor A. Pašti
      First page: 1207
      Abstract: The interest in single-atom catalysts (SACs) is increasing, as these materials have the ultimate level of catalyst utilization, while novel reactions where SACs are used are constantly being discovered. However, to properly understand SACs and to further improve these materials, it is necessary to consider the nature of active sites under operating conditions. This is particularly important when SACs are used as electrocatalysts due to harsh experimental conditions, including extreme pH values or high anodic and cathodic potential. In this contribution, density functional theory-based thermodynamic modelling is used to address the nature of metal centers in SACs formed by embedding single metal atoms (Ru, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au) into graphene monovacancy. Our results suggest that none of these SAC metal centers are clean at any potential or pH in the water thermodynamic stability region. Instead, metal centers are covered with Hads, OHads, or Oads, and in some cases, we observed the restructuring of the metal sites due to oxygen incorporation. Based on these findings, it is suggested that setting up theoretical models for SAC modelling and the interpretation of ex situ characterization results using ultra-high vacuum (UHV) techniques requires special care, as the nature of SAC active sites under operating conditions can significantly diverge from the basic models or the pictures set by the UHV measurements.
      Citation: Catalysts
      PubDate: 2021-10-08
      DOI: 10.3390/catal11101207
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1208: Asymmetric Henry Reaction of Nitromethane
           with Substituted Aldehydes Catalyzed by Novel In Situ Generated Chiral
           Bis(β-Amino Alcohol-Cu(OAc)2·H2O Complex

    • Authors: Abdullah Saleh Alammari, Abdullah Mohammed Al-Majid, Assem Barakat, Saeed Alshahrani, Mohammad Ali, Mohammad Shahidul Islam
      First page: 1208
      Abstract: Novel chiral thiophene-2,5-bis(β-amino alcohol) ligands (L1–L5) were designed and synthesized from thiophene-2,5-dicarbaldehyde (3) with chiral β-amino alcohols (4a–e) in 4 steps with overall 23% yields. An in situ generated L-Cu(OAc)2·H2O catalyst system was found to be highly capable catalyst for the asymmetric Henry reaction of nitromethane (7) with various substituted aromatic aldehydes (6a–m) producing chiral nitroaldols product (8a–m) with excellent enantiomeric purity (up to 94.6% ee) and up to >99% chemical yields. 20 mol% of L4-Cu(OAc)2 catalyst complex in EtOH was effective for the asymmetric Henry transformation in 24 h, at ambient temperature. Ease of ligand synthesis, use of green solvent, base free reaction, mild reaction conditions, high yields and excellent enantioselectivity are all key factors that make this catalytic system robust and highly desirable for the access of versatile building block β-nitro alcohol in practical catalytic usage via asymmetric Henry reaction.
      Citation: Catalysts
      PubDate: 2021-10-08
      DOI: 10.3390/catal11101208
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1209: Structural and Functional Behaviour of
           Ce-Doped Wide-Bandgap Semiconductors for Photo-Catalytic Applications

    • Authors: Giulia Forghieri, Danny Zanardo, Elena Ghedini, Federica Menegazzo, Alessia Giordana, Giuseppina Cerrato, Alessandro Di Michele, Giuseppe Cruciani, Michela Signoretto
      First page: 1209
      Abstract: Increasing the photocatalytic efficiency of earth-abundant wide-bandgap semiconductors is of high interest for the development of cheap but effective light-driven chemical conversion processes. In this study, the coupling of ZnO and TiO2 with low contents of the rare-earth Ce species aimed to assess the photo-catalytic performance of the two semiconductors (SC). Structural and optical characterizations were performed to estimate the effect of the different interactions between Zn2+, Ti4+ and Ce4+ ions, and how the photo-responsive behaviour of Ce-Ti and Ce-Zn composites was affected. Therefore, photo-catalytic tests were performed for all Ce-modified SC to assess both their photo-oxidative and photo-reductive properties. Amongst all the tested materials, only Zn-based samples resulted in being suitable for the photo-oxidation of the methylene blue (MB) organic pollutant in a synthetic-dependent fashion.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101209
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1210: Metal Nanoparticle Catalysis

    • Authors: Patricia Lara, Luis M. Martínez-Prieto
      First page: 1210
      Abstract: In recent years, the catalytic use of metal nanoparticles (MNPs) has experienced a growing interest [...]
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101210
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1211: Immobilization of Enzymes by Polymeric
           Materials

    • Authors: Xingyi Lyu, Rebekah Gonzalez, Andalwisye Horton, Tao Li
      First page: 1211
      Abstract: Enzymes are the highly efficient biocatalyst in modern biotechnological industries. Due to the fragile property exposed to the external stimulus, the application of enzymes is highly limited. The immobilized enzyme by polymer has become a research hotspot to empower enzymes with more extraordinary properties and broader usage. Compared with free enzyme, polymer immobilized enzymes improve thermal and operational stability in harsh environments, such as extreme pH, temperature and concentration. Furthermore, good reusability is also highly expected. The first part of this study reviews the three primary immobilization methods: physical adsorption, covalent binding and entrapment, with their advantages and drawbacks. The second part of this paper includes some polymer applications and their derivatives in the immobilization of enzymes.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101211
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1212: Cu/ZSM5-Geopolymer 3D-Printed Monoliths
           for the NH3-SCR of NOx

    • Authors: Elisabetta Maria Cepollaro, Renata Botti, Giorgia Franchin, Luciana Lisi, Paolo Colombo, Stefano Cimino
      First page: 1212
      Abstract: Geopolymer-based monoliths manufactured by direct ink writing, containing up to 60% by weight of presynthesized ZSM5 with low Si/Al ratio, were investigated as structured catalysts for the NH3-SCR of NOx. Copper was introduced as the active metal by ion exchange after a preliminary acid treatment of the monoliths. Monolithic catalysts were characterized by morphological (XRD and SEM), textural (BET and pore size distribution), mechanical (compressive strength), chemical (ICP–MS), redox (H2-TPR) and surface (NH3-TPD) analyses, showing the preservation of Cu-exchanged zeolite features in the composite monoliths. NH3-SCR tests, carried out on both monolithic and powdered samples in the temperature range 70–550 °C, confirmed that composite monoliths provide a very good activity and a high selectivity to N2 over the whole range of temperatures explored due to the hierarchical structure of the materials, in addition to a good mechanical resistance—mostly related to the geopolymer matrix.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101212
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1213: Novel Recyclable Pd/H-MOR Catalyst for
           Suzuki–Miyaura Coupling and Application in the Synthesis of Crizotinib

    • Authors: Enmu Zhou, Jianzhong Jin, Kai Zheng, Letian Zhang, Hao Xu, Chao Shen
      First page: 1213
      Abstract: In this paper, we report an effective ultrasound method for the synthesis of Pd/H-MOR, which was used as a catalyst in the Suzuki–Miyaura coupling of aryl halides with phenylboronic acid. The structure and morphology of the as-prepared catalysts were fully characterized by X-ray diffraction (XRD), N2 sorption isotherms, scanning electron microscopy (SEM), and an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The advantages of Pd/H-MOR in the coupling reaction are green solvents, high yields, absence of ligands, and recyclability. The catalysts were easily reused at least ten times without significant deterioration in catalytic activity. In addition, this protocol was used in the marketed anti-tumor drug crizotinib synthesis.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101213
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1214: Isolation and Identification of an
           Efficient Aerobic Denitrifying Pseudomonas stutzeri Strain and
           Characterization of Its Nitrite Degradation

    • Authors: Weilai Fu, Qiang Wang, Shuhui Chen, Yunshuang Wang, Yaru Wang, Peifeng Duan, Ganfeng Yi, Chao Liu, Xian Zhang, Zhiming Rao
      First page: 1214
      Abstract: Nitrogen pollution in water bodies is becoming increasingly serious, and how to remove nitrogen from water bodies economically and effectively has become a research hotspot. Especially in recent years, with the gradual expansion of aquaculture in China, the content of nitrite and other nitrogen-containing substances in water bodies has been increasing, which inhibits the growth of farm animals and is one of the causes of eutrophication in water bodies. In this study, a strain of bacteria was isolated from the sludge of an aquaculture fishpond and identified as Pseudomonas stutzeri, which can efficiently degrade nitrite. After continuous domestication in nitrite mixed solution, the nitrite nitrogen reduction capacity of P. stutzeri was significantly improved. Univariate experiments aiming to optimize the degradation conditions indicate that the optimal culture conditions for strain F2 are: medium with a carbon source of sodium succinate; C/N of 18; pH of 8; culture temperature of 28 °C; and shaking speed of 210 rpm in the shaker. Under the optimal culture conditions, the NO2−-N concentration of the culture solution was 300 mg/L, and the nitrite removal rate reached 98.67%. Meanwhile, the results of the nitrogen balance test showed that the strain converted 6.1% of the initial nitrogen into cellular organic nitrogen and 62.3% into gaseous nitrogen.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101214
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1215: Application of Agricultural Waste as
           Heterogeneous Catalysts for Biodiesel Production

    • Authors: Haris Mahmood Khan, Tanveer Iqbal, Saima Yasin, Chaudhry Haider Ali, Muhammad Mujtaba Abbas, Muhammad Asif Jamil, Abrar Hussain, Manzoore Elahi M. Soudagar, Muhammad Muhitur Rahman
      First page: 1215
      Abstract: In this modern era, it has become essential to transform waste materials into valuables because of their excessive availability, along with achieving the targets of environmental protocols and waste management policies. With a growing population, the utilization and consumption of agricultural products have been increased extensively. In addition, it has increased the probability of agricultural waste generation. Waste produced from agricultural sources is considered as a viable source for synthesizing economical and ecofriendly catalysts and suitable ways for its disposal are sought. This study is targeted at agricultural waste-derived heterogeneous catalysts, which have been effectively employed for biodiesel generation. The types of agricultural waste, catalyst synthesis techniques, recent literature stated for agricultural waste-derived catalysts to produce biodiesel, the elemental composition and catalytic activity of agricultural waste ashes, the effect of reaction parameters to maximize biodiesel yield and catalyst reusability have been discussed. This work concludes that catalysts derived from agricultural waste are efficient in transesterification reaction, and they are easy to produce, and are cheap and ecofriendly. Moreover, this study encourages researchers to see the options for unexplored agricultural waste, which can be potentially converted into useful materials
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101215
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1216: The Roles of Precursor-Induced
           Metal–Support Interaction on the Selective Hydrogenation of
           Crotonaldehyde Over Ir/TiO2 Catalysts

    • Authors: Aiping Jia, Hantao Peng, Yunshang Zhang, Tongyang Song, Yanwen Ye, Mengfei Luo, Jiqing Lu, Weixin Huang
      First page: 1216
      Abstract: Various supported Ir/TiO2 catalysts were prepared using different Ir precursors (i.e., H2IrCl6, (NH4)2IrCl6 and Ir(acac)3) and tested for vapor phase selective hydrogenation of crotonaldehyde. The choice of Ir precursor significantly altered the Ir-TiOx interaction in the catalyst, which thus had essential influences on the geometric and electronic properties of the Ir species, reducibility, and surface acidity, and, consequently, their reaction behaviors. The Ir/TiO2-N catalyst using (NH4)2IrCl6 as the precursor gave the highest initial reaction rates and turnover frequencies of crotyl alcohol formation. Such high performance was ascribed to the high Ir dispersion and high surface concentration of Ir0 species, as well as a higher surface acidity, in the Ir/TiO2-N catalyst compared to its counterparts, indicating the synergistic roles of the Ir-TiOx interface in the reaction, as the interfacial sites were responsible for the adsorption/activation of H2 and the C=O bond in the crotonaldehyde molecule.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101216
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1217: Promoting Role of Amorphous Carbon and
           Carbon Nanotubes Growth Modes of Methane Decomposition in One-Pot
           Catalytic Approach

    • Authors: Lifang Chen, Luis Enrique Noreña, Jin An Wang, Roberto Limas, Ulises Arellano, Oscar Arturo González Vargas
      First page: 1217
      Abstract: We report the simultaneous production of hydrogen fuel and carbon nanotubes (CNTs) via methane dehydrogenation catalyzed with Ni/SBA-15. Most Ni nanoparticles (NPs) with size between 10 and 30 nm were highly dispersed on SBA-15 and most of them had a strong interaction with the support. At temperatures ranging from 500 to 800 °C, methane could be decomposed to release hydrogen with 100% selectivity at conversion between 51 and 65%. There was no CO or CO2 detectable in the reaction fluent. In the initial stage of the reaction, amorphous carbon and dehydrogenated methane species adsorbed on the Ni NPs promoted the CH4 decomposition. The amorphous carbon atoms were then transformed into carbon nanotubes which chiefly consisted of a multiwall structure and grew towards different orientations via a tip-growth or a base-growth modes, controlled by the interaction strength between the Ni NPs and the SBA-15 support. Reaction temperature affected not only methane conversion, but also the diffusion of carbon atoms on/in the Ni NPs and their precipitation at the interfaces. At higher temperature, bamboo-like CNTs or onion-like metal-encapsulated carbons were formed, mainly due to the rate of carbon atom formation greater than that of carbon precipitation for CNTs construction. The CNTs formation mechanisms are discussed and their growth modes under different conditions are proposed.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101217
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1218: Recent Advances in the Catalytic Treatment
           of Volatile Organic Compounds: A Review Based on the Mixture Effect

    • Authors: Guillaume Rochard, Lilian Olivet, Mariebelle Tannous, Christophe Poupin, Stéphane Siffert, Renaud Cousin
      First page: 1218
      Abstract: Catalytic total oxidation is an efficient technique for treating VOCs, which are mainly emitted by solvent-based industrial processes. However, studies of the catalytic oxidation of VOCs in combination with other pollutants are very limited, despite the fact that this is a key step of knowledge before industrial application. During the oxidation reaction, the behavior of a molecule may change depending on the reaction mixture. For the treatment of an effluent loaded with VOCs, it is necessary to carefully select not only the catalytic material to be used but also the reaction conditions. Indeed, the catalytic oxidation of a component in a VOCs mixture is not predicted solely from the behavior of individual component. Thus, the objective of this small review is to carry out a study on the effect observed in the case of the oxidation of a VOCs mixture or in the presence of water, NOX or sulfur compounds.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101218
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1219: Magnetically Reusable Fe3O4@NC@Pt Catalyst
           for Selective Reduction of Nitroarenes

    • Authors: Jun Qiao, Tian Wang, Kai Zheng, Enmu Zhou, Chao Shen, Aiquan Jia, Qianfeng Zhang
      First page: 1219
      Abstract: A novel reusable Fe3O4@NC@Pt heterogeneous catalyst was synthesized by immobilizing platinum on nitrogen-doped carbon magnetic nanostructures. It was characterized by infrared analysis (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The catalytic efficiency of Fe3O4@NC@Pt was investigated by reduction of nitro aromatic compounds. The catalyst showed good catalytic activity, wide range of substrates, and good chemical selectivity, especially for the substrates of compounds containing halide and carbonyl groups. The magnetically catalyst can readily be reused up to ten cycles without loss of catalytic activity. Moreover, the key pharmaceutical intermediate Lorlatini can be facilely achieved through this strategy.
      Citation: Catalysts
      PubDate: 2021-10-09
      DOI: 10.3390/catal11101219
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1220: Electron Mediation and Photocurrent
           Enhancement in Dunalliela salina Driven Bio-Photo Electrochemical Cells

    • Authors: Yaniv Shlosberg, Tünde N. Tóth, Benjamin Eichenbaum, Lee Keysar, Gadi Schuster, Noam Adir
      First page: 1220
      Abstract: In recent years, finding alternatives for fossil fuels has become a major concern. One promising solution is microorganism-based bio-photo electrochemical cells (BPECs) that utilize photosynthetic solar energy conversion as an energy source while absorbing CO2 from the atmosphere. It was previously reported that in cyanobacterial-based BPECs, the major endogenous electron mediator that can transfer electrons from the thylakoid membrane photosynthetic complexes and external anodes is NADPH. However, the question of whether the same electron transfer mechanism is also valid for live eukaryotic microalgae, in which NADPH must cross both the chloroplast outer membrane and the cell wall to be secreted from the cell has remained elusive. In this work, we show that NADPH is also the major endogenous electron mediator in the microalgae Dunalliela salina (Ds). We show that the ability of Ds to tolerate high salinity enables the production of a photocurrent that is 5–6 times greater than previously reported for freshwater cyanobacterial-based BPECs in the presence or absence of exogenous electron mediators. Additionally, we show that the electron mediator Vitamin B1 can also function as an electron mediator enhancing photocurrent production. Finally, we show that the addition of both FeCN and NADP+ to Ds has a synergistic effect enhancing the photocurrent beyond the effect of adding each mediator separately.
      Citation: Catalysts
      PubDate: 2021-10-10
      DOI: 10.3390/catal11101220
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1221: The Effect of Preparation Method of
           Ni-Supported SiO2 Catalysts for Carbon Dioxide Reforming of Methane

    • Authors: Hua-Ping Ren, Si-Yi Ding, Qiang Ma, Wen-Qi Song, Yu-Zhen Zhao, Jiao Liu, Ye-Ming He, Shao-Peng Tian
      First page: 1221
      Abstract: Reforming methane to produce syngas is a subject that generates considerable interest. The process requires catalysts that possess high-performance active sites to activate stable C–H bonds. Herein, we report a facile synthetic strategy to prepare Ni-based catalysts by complexation–impregnation (Ni-G/SiO2-C) and precipitation–impregnation (Ni-G/SiO2-P) methods using glycine as a complexing agent. The particle size of Ni in both types of catalysts is decreased by adding glycine in the preparation process. Nevertheless, the preparation methods and amount of glycine play a significant role in the particle size and distribution of Ni over the Ni-based catalysts. The smaller particle size and narrower distribution of Ni were obtained in the Ni-G/SiO2-P catalyst. The catalysts were comparatively tested for carbon-dioxide reforming of methane (CDR). Ni-G/SiO2-P showed better CDR performance than Ni-G/SiO2-C and Ni/SiO2 and increased stability because of the smaller particle size and narrower distribution of Ni. Moreover, a high-performance Ni-based catalyst was prepared by optimizing the amount of glycine added. An unobservable deactivation was obtained over Ni-G-2/SiO2-P and Ni-G-3/SiO2-P for CDR during TOS = 20 h. Thus, a new promising method is described for the preparation of Ni-based catalysts for CDR.
      Citation: Catalysts
      PubDate: 2021-10-10
      DOI: 10.3390/catal11101221
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1222: Current Status and Future Perspectives of
           Supports and Protocols for Enzyme Immobilization

    • Authors: Francisco T. T. Cavalcante, Antônio L. G. Cavalcante, Isamayra G. de Sousa, Francisco S. Neto, José C. S. dos Santos
      First page: 1222
      Abstract: The market for industrial enzymes has witnessed constant growth, which is currently around 7% a year, projected to reach $10.5 billion in 2024. Lipases are hydrolase enzymes naturally responsible for triglyceride hydrolysis. They are the most expansively used industrial biocatalysts, with wide application in a broad range of industries. However, these biocatalytic processes are usually limited by the low stability of the enzyme, the half-life time, and the processes required to solve these problems are complex and lack application feasibility at the industrial scale. Emerging technologies create new materials for enzyme carriers and sophisticate the well-known immobilization principles to produce more robust, eco-friendlier, and cheaper biocatalysts. Therefore, this review discusses the trending studies and industrial applications of the materials and protocols for lipase immobilization, analyzing their advantages and disadvantages. Finally, it summarizes the current challenges and potential alternatives for lipases at the industrial level.
      Citation: Catalysts
      PubDate: 2021-10-11
      DOI: 10.3390/catal11101222
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1223: Rh-Catalyzed Reductive Amination of
           

    • Authors: Ariane Weber, Linus Porthun, Reinhard Schomäcker
      First page: 1223
      Abstract: The homogeneously catalyzed reductive amination of the long-chain aldehyde undecanal with diethylamine was performed in an aqueous microemulsion system using the non-ionic surfactant Marlophen NP8. The experiments showed that the used water-soluble rhodium/SulfoXantphos catalyst system is suitable for this reaction. The Rh-catalyzed formation of the alcohol by-product can be completely suppressed by the use of carbon monoxide with its stabilizing effect of the catalyst system. In addition to pressure and temperature, the most important parameters for the reaction performance of the reductive amination are the concentrations of reactants. Especially, the initial concentration of the aldehyde has a strong impact on the chemoselectivity, and the formation of aldol by-product due to the fact that both, the enamine condensation and the aldol condensation are equilibrium reactions.
      Citation: Catalysts
      PubDate: 2021-10-11
      DOI: 10.3390/catal11101223
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1224: Process Intensification of Methane
           Production via Catalytic Hydrogenation in the Presence of Ni-CeO2/Cr2O3
           Using a Micro-Channel Reactor

    • Authors: Vut Tongnan, Youssef Ait-lahcen, Chuthamas Wongsartsai, Chalempol Khajonvittayakul, Nuchanart Siri-Nguan, Navadol Laosiripojana, Unalome Wetwatana Hartley
      First page: 1224
      Abstract: A slight amount of Cr2O3 segregation in 40 wt% NiO/Ce0.5Cr0.5O2 was presented at the surface. The best catalytic performance towards the reaction was achieved at 74% of CO2 conversion and 100% CH4 selectivity at 310 °C, the reactant (H2/CO2) feed molar ratio was 4, and the WHSV was 56,500 mlN·h−1·g−1cat. The mechanistic pathway was proposed through carbonates and formates as a mediator during CO2 and H2 interaction. Activation energy was estimated at 4.85 kJ/mol, when the orders of the reaction were ranging from 0.33 to 1.07 for nth-order, and 0.40 to 0.53 for mth-order.
      Citation: Catalysts
      PubDate: 2021-10-11
      DOI: 10.3390/catal11101224
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1225: Investigation on the Suitability of
           Engelhard Titanium Silicate as a Support for Ni-Catalysts in the
           Methanation Reaction

    • Authors: Patrizia Frontera, Mariachiara Miceli, Francesco Mauriello, Pierantonio De Luca, Anastasia Macario
      First page: 1225
      Abstract: Methanation reaction of carbon dioxide is currently envisaged as a facile solution for the storage and transportation of low-grade energies, contributing at the same time to the mitigation of CO2 emissions. In this work, a nickel catalyst impregnated onto a new support, Engelhard Titanium Silicates (ETS), is proposed, and its catalytic performance was tested toward the CO2 methanation reaction. Two types of ETS material were investigated, ETS-4 and ETS-10, that differ from each other in the titanium content, with Si/Ti around 2 and 3% by weight, respectively. Catalysts, loaded with 5% of nickel, were tested in the CO2 methanation reaction in the temperature range of 300–500 °C and were characterized by XRD, SEM–EDX, N2 adsorption–desorption and H2-TPR. Results showed an interesting catalytic activity of the Ni/ETS catalysts. Particularly, the best catalytic performances are showed by Ni/ETS-10: 68% CO2 conversion and 98% CH4 selectivity at T = 400 °C. The comparison of catalytic performance of Ni/ETS-10 with those obtained by other Ni-zeolites catalysts confirms that Ni/ETS-10 catalyst is a promising one for the CO2 methanation reaction.
      Citation: Catalysts
      PubDate: 2021-10-12
      DOI: 10.3390/catal11101225
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1226: Influence of Pd and Pt Promotion in Gold
           Based Bimetallic Catalysts on Selectivity Modulation in Furfural Base-Free
           Oxidation

    • Authors: Hisham K. Al Rawas, Camila P. Ferraz, Joëlle Thuriot-Roukos, Svetlana Heyte, Sébastien Paul, Robert Wojcieszak
      First page: 1226
      Abstract: Furfural (FF) has a high potential to become a major renewable platform molecule to produce biofuels and bio-based chemicals. The catalytic performances of AuxPty and AuxPdy bimetallic nanoparticulate systems supported on TiO2 were studied in a base-free aerobic oxidation of furfural to furoic acid (FA) and maleic acid (MA) in water. The characterization of the catalysts was performed using standard techniques. The optimum reaction conditions were also investigated, including the reaction time, the reaction temperature, the metal ratio, and the metal loading. The present work shows a synergistic effect existing between Au, Pd, and Pt in the alloy, where the performances of the catalysts were strongly dependent on the metal ratio. The highest selectivity (100%) to FA was obtained using Au3-Pd1 catalysts, with 88% using 0.5% Au3Pt1 with about 30% of FF conversion at 80 °C. Using Au-Pd-based catalysts, the maximum yield of MA (14%) and 5% of 2(5H)-furanone (FAO) were obtained by using a 2%Au1-Pd1/TiO2 catalyst at 110 °C.
      Citation: Catalysts
      PubDate: 2021-10-12
      DOI: 10.3390/catal11101226
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1227: Ru-gC3N4 Catalyzed Hydrodebenzylation of
           Benzyl Protected Alcohol and Acid Groups Using Sodium Hypophosphite as a
           Hydrogen Source

    • Authors: Sourav Chakraborty, Ashish Bahuguna, Yoel Sasson
      First page: 1227
      Abstract: A straightforward process for hydrodebenzylation of benzyl protected acid and alcohol derivatives to the corresponding acids and alcohols using sodium hypophosphite in the presence of Ru-GCN catalyst is reported. The developed Ru-GCN catalyst is cost effective compared to other noble metal-based catalysts and has been explored to exhibit excellent activity for catalytic hydrodebenzylation reactions under moderate reaction conditions. The non-corrosive sodium hypophosphite has been found as a better hydrogen donor compared to alkali metal formats in presence of Ru-GCN catalyst. The stated catalyst was characterized using several spectrometric and material characterization methods such as PXRD, IR, SEM, TEM, XPS, and TGA. The Ru-GCN catalyst corroborated good reusability and stability for multiple cycles. The catalyst preparation is facile and the developed process is simple and safe as it avoids use of high hydrogen pressure. The developed protocol can also be replicated on industrial scale on account of excellent recyclability and retained activity after multiple cycles and makes the process sustainable. Gram scale reaction was performed to verify the industrial potential of reported catalyst.
      Citation: Catalysts
      PubDate: 2021-10-12
      DOI: 10.3390/catal11101227
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1228: Influence of Bio-Based Surfactants on TiO2
           Thin Films as Photoanodes for Electro-Photocatalysis

    • Authors: Fanny Duquet, Amr Ahmed Nada, Matthieu Rivallin, Florence Rouessac, Christina Villeneuve-Faure, Stéphanie Roualdes
      First page: 1228
      Abstract: Photocatalytic water splitting into hydrogen is considered as one of the key solutions to the current demand for eco-responsible energy. To improve the efficiency and sustainability of this process, the development of a TiO2-based photoanode by adding bio-sourced surfactants to the sol–gel preparation method has been considered. Three different polymeric biosurfactants (GB, GC, and BIO) have been tested, giving rise to three different materials being structurally and morphologically characterized by XRD, Rietveld refinement, BET, SEM, AFM, and XPS, which was completed by light absorption, photocatalytic (Pilkington test), electronic (EIS and C-AFM), and photoelectrochemical (cyclic voltammetry) measurements. Correlations between the structure/morphology of materials and their functional properties have been established. One specific surfactant has been proven as the most suitable to lead to materials with optimized photoelectrochemical performance in direct relation with their photocatalytic properties essentially controlled by their specific surface area.
      Citation: Catalysts
      PubDate: 2021-10-12
      DOI: 10.3390/catal11101228
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1229: Morphology and Catalytic Performance of
           MoS2 Hydrothermally Synthesized at Various pH Values

    • Authors: Seung-Jae Lee, Yang-Seung Son, Jin-Hoon Choi, Seong-Soo Kim, Sung-Youl Park
      First page: 1229
      Abstract: Although preparation conditions are known to affect the morphology and catalytic performance of hydrothermally synthesized MoS2, the influence of pH remains unclear. Herein, unsupported MoS2 was prepared from ammonium tetrathiomolybdate (ATTM) by a hydrothermal reaction at various pH values under a reaction pressure of 2 MPa. The physical and chemical properties of the MoS2 samples were characterized, and the catalytic performance for CO methanation was examined. With increasing pH, the morphology of the MoS2 particles transformed from aggregates of irregular grain-like particles to flower-like particles through the agglomeration of fine mesoporous nanoflakes. Hydrothermal synthesis at a pH of 9.5 increased the MoS2 crystallinity by enhancing the stacking of the (0 0 2) lattice plane. The MoS2 samples prepared at pH 7.0 and 9.5 showed increased CO conversion during methanation, which was associated with a low concentration of Mo5+ species and the presence of surface sulfate species. Thus, a high pH during catalyst preparation may promote the complete decomposition of ATTM to MoS2 and the formation of sulfur vacancies, which can facilitate methanation.
      Citation: Catalysts
      PubDate: 2021-10-12
      DOI: 10.3390/catal11101229
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1230: Al2O3-Supported Transition Metals for
           Plasma-Catalytic NH3 Synthesis in a DBD Plasma: Metal Activity and
           Insights into Mechanisms

    • Authors: Yury Gorbanev, Yannick Engelmann, Kevin van’t Veer, Evgenii Vlasov, Callie Ndayirinde, Yanhui Yi, Sara Bals, Annemie Bogaerts
      First page: 1230
      Abstract: N2 fixation into NH3 is one of the main processes in the chemical industry. Plasma catalysis is among the environmentally friendly alternatives to the industrial energy-intensive Haber-Bosch process. However, many questions remain open, such as the applicability of the conventional catalytic knowledge to plasma. In this work, we studied the performance of Al2O3-supported Fe, Ru, Co and Cu catalysts in plasma-catalytic NH3 synthesis in a DBD reactor. We investigated the effects of different active metals, and different ratios of the feed gas components, on the concentration and production rate of NH3, and the energy consumption of the plasma system. The results show that the trend of the metal activity (common for thermal catalysis) does not appear in the case of plasma catalysis: here, all metals exhibited similar performance. These findings are in good agreement with our recently published microkinetic model. This highlights the virtual independence of NH3 production on the metal catalyst material, thus validating the model and indicating the potential contribution of radical adsorption and Eley-Rideal reactions to the plasma-catalytic mechanism of NH3 synthesis.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101230
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1231: Catalytic Tar Conversion in Two Different
           Hot Syngas Cleaning Systems

    • Authors: Grazyna Straczewski, Robert Mai, Uta Gerhards, Krassimir Garbev, Hans Leibold
      First page: 1231
      Abstract: Tar in the product gas of biomass gasifiers reduces the efficiency of gasification processes and causes fouling of system components and pipework. Therefore, an efficient tar conversion in the product gas is a key step of effective and reliable syngas production. One of the most promising approaches is the catalytic decomposition of the tar species combined with hot syngas cleaning. The catalyst must be able to convert tar components in the synthesis gas at temperatures of around 700 °C downstream of the gasifier without preheating. A Ni-based doped catalyst with high activity in tar conversion was developed and characterized in detail. An appropriate composition of transition metals was applied to minimize catalyst coking. Precious metals (Pt, Pd, Rh, or a combination of two of them) were added to the catalyst in small quantities. Depending on the hot gas cleaning system used, both transition metals and precious metals were co-impregnated on pellets or on a ceramic filter material. In the case of a pelletized-type catalyst, the hot gas cleaning system revealed a conversion above 80% for 70 and 110 h. The catalyst composed of Ni, Fe, and Cr oxides, promoted with Pt and impregnated on a ceramic fiber filter composed of Al2O3(44%)/SiO2(56%), was the most active catalyst for a compact cleaning system. This catalyst was catalytically active with a naphthalene conversion of around 93% over 95 h without catalyst deactivation.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101231
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1232: Synthesis of Nano-ZnO/Diatomite Composite
           and Research on Photoelectric Application

    • Authors: Beibei Yang, Xuefei Liu, Zixu Ma, Qian Wang, Junjiao Yang
      First page: 1232
      Abstract: The key to the commercialization of sustainable energy conversion technologies is the development of high-performance catalysts. The discovery of a stable, efficient, and low-cost multi-function catalyst is key. We used a simple green precipitation method to load diatomite nanozinc oxide particles onto a diatomite substrate. The ZnO is nano-sized. This precipitation method produces ZnO nanoparticles in situ on diatomite. The catalyst degraded 90% of a Methylene blue solution and also degraded gaseous benzene and acetone. Not only can the catalyst be used for the organic degradation of wastewater, but it also has the potential to degrade volatile organic compounds. Photocatalytic efficiency is closely related to the generation and separation of photosynthetic electrons and holes. The effective suppression of the composite rate of photoliving carriers, and thus improvement of the photocatalytic activity, has become a key research area. At present, At present, photocatalysis is an effective technology to inhibit photocarrier synthesis, which is often studied in sewage treatment. Photocatalytic water treatment reduces the combination of photoelectrons and holes by applying an external bias, thus improving the quantum efficiency for the complete mineralization of organic pollutants. The composite catalyst was used for oxygen and hydrogen extraction reactions, and a comparison of the catalysts with various loading ratios showed that the electrolysis water activity of the in situ loaded catalyst is due to pure ZnO, and the efficiency is highest when the loading ratio is 10%. This work provides new methods for the design and further optimization of the preparation of electrolytic aqueous catalysts.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101232
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1233: Optimizing MgO Content for Boosting
           g-Al2O3-Supported Ni Catalyst in Dry Reforming of Methane

    • Authors: Abdulaziz Bagabas, Ahmed Sadeq Al-Fatesh, Samsudeen Olajide Kasim, Rasheed Arasheed, Ahmed Aidid Ibrahim, Rawan Ashamari, Khalid Anojaidi, Anis Hamza Fakeeha, Jehad K. Abu-Dahrieh, Ahmed Elhag Abasaeed
      First page: 1233
      Abstract: The dry reforming of methane (DRM) process has attracted research interest because of its ability to mitigate the detrimental impacts of greenhouse gases such as methane (CH4) and carbon dioxide (CO2) and produce alcohols and clean fuel. In view of this importance of DRM, we disclosed the efficiency of a new nickel-based catalyst, which was promoted with magnesia (MgO) and supported over gamma-alumina (g-Al2O3) doped with silica (SiO2), toward DRM. The synthesized catalysts were characterized by H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric analysis (TGA), and Transmission electron microscopy (TEM) techniques. The effect of MgO weight percent loading (0.0, 1.0, 2.0, and 3.0 wt. %) was examined because the catalytic performance was found to be a function of this parameter. An optimum loading of 2.0 wt. % of MgO was obtained, where the conversion of CH4 and CO2 at 800 °C were 86% and 91%, respectively, while the syngas (H2/CO) ratios relied on temperature and were in the range of 0.85 to 0.95. The TGA measurement of the best catalyst, which was operated over a 15-hour reaction time, displayed negligible weight loss (<9.0 wt. %) due to carbon deposition, indicating the good resistance of our catalyst system to the deposition of carbon owing to the dopant and the modifier. TEM images showed the presence of multiwalled carbon nanotubes, confirming the TGA.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101233
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1234: Innovative Ag–TiO2 Nanofibers with
           Excellent Photocatalytic and Antibacterial Actions

    • Authors: Petronela Pascariu, Corneliu Cojocaru, Anton Airinei, Niculae Olaru, Irina Rosca, Emmanouel Koudoumas, Mirela Petruta Suchea
      First page: 1234
      Abstract: Ag–TiO2 nanostructures were prepared by electrospinning, followed by calcination at 400 °C, and their photocatalytic and antibacterial actions were studied. Morphological characterization revealed the presence of one-dimensional uniform Ag–TiO2 nanostructured nanofibers, with a diameter from 65 to 100 nm, depending on the Ag loading, composed of small crystals interconnected with each other. Structural characterization indicated that Ag was successfully integrated as small nanocrystals without affecting much of the TiO2 crystal lattice. Moreover, the presence of nano Ag was found to contribute to reducing the band gap energy, which enables the activation by the absorption of visible light, while, at the same time, it delays the electron–hole recombination. Tests of their photocatalytic activity in methylene blue, amaranth, Congo red and orange II degradation revealed an increase by more than 20% in color removal efficiency at an almost double rate for the case of 0.1% Ag–TiO2 nanofibers with respect to pure TiO2. Moreover, the minimum inhibitory concentration was found as low as 2.5 mg/mL for E. coli and 5 mg/mL against S. aureus for the 5% Ag–TiO2 nanofibers. In general, the Ag–TiO2 nanostructured nanofibers were found to exhibit excellent structure and physical properties and to be suitable for efficient photocatalytic and antibacterial uses. Therefore, these can be suitable for further integration in various important applications.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101234
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1235: Study of the Photoelectrochemical
           Properties of 1D ZnO Based Nanocomposites

    • Authors: Bekbolat Seitov, Sherzod Kurbanbekov, Dina Bakranova, Nuriya Abdyldayeva, Nurlan Bakranov
      First page: 1235
      Abstract: Exploitation of common elements as photocatalysts for conversion of photons to electricity stimulates the development of a green energy strategy. In this paper, methods for the preparation of active coatings based on ZnO/Ag/CdS, which are used in the photocatalytic oxidation reaction, are examined. The physical and chemical properties of the resulting arrays were studied using optical spectrometers, an electron microscope, an X-ray diffractometer, and potentiostatic measurements and electrochemical impedance spectroscopy. The effectiveness of photocatalysts was calculated by the ability to liberate gas from aqueous solutions when exposed to light. The rate of degradation was indirectly measured with a conductometer.
      Citation: Catalysts
      PubDate: 2021-10-13
      DOI: 10.3390/catal11101235
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1236: Strategies for the Immobilization of
           Eversa® Transform 2.0 Lipase and Application for Phospholipid Synthesis

    • Authors: Bruno R. Facin, Ernestina G. Quinto, Alexsandra Valerio, Débora de Oliveira, Jose V. Oliveira, Gloria Fernandez-Lorente
      First page: 1236
      Abstract: Eversa® Transform 2.0 lipase (ET2) is a recent lipase formulation derived from the Thermomyces lanuginosus lipase cultivated on Aspergillus oryzae and specially designed for biodiesel production. Since it has not been available for a long time, research on the efficiency of this enzyme in other applications remains unexplored. Moreover, even though it has been launched as a free enzyme, its immobilization may extend the scope of ET2 applications. This work explored ET2 immobilization on octadecyl methacrylate beads (IB-ADS-3) and proved the efficiency of the derivatives for esterification of glycerophosphocholine (GPC) with oleic acid in anhydrous systems. ET2 immobilized via interfacial activation on commercial hydrophobic support Immobead IB-ADS-3 showed maximum enzyme loading of 160 mg/g (enzyme/support) and great stability for GPC esterification under 30% butanone and solvent-free systems. For reusability, yields above 63% were achieved after six reaction cycles for GPC esterification. Considering the very high enzyme loading and the number of reuses achieved, these results suggest a potential application of this immobilized biocatalyst for esterification reactions in anhydrous media. This study is expected to encourage the exploration of other approaches for this enzyme, thereby opening up several new possibilities.
      Citation: Catalysts
      PubDate: 2021-10-14
      DOI: 10.3390/catal11101236
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1237: Tuning the Electronic Structure of CoO
           Nanowire Arrays by N-Doping for Efficient Hydrogen Evolution in Alkaline
           Solutions

    • Authors: Maoqi Cao, Xiaofeng Li, Dingding Xiang, Dawang Wu, Sailan Sun, Hongjing Dai, Jun Luo, Hongtao Zou
      First page: 1237
      Abstract: Electrochemical hydrogen evolution reactions (HER) have drawn tremendous interest for the scalable and sustainable conversion of renewable electricity to clear hydrogen fuel. However, the sluggish kinetics of the water dissociation step severely restricts the high production of hydrogen in alkaline media. Tuning the electronic structure by doping is an effective method to boost water dissociation in alkaline solutions. In this study, N-doped CoO nanowire arrays (N-CoO) were designed and prepared using a simple method. X-ray diffraction (XRD), element mappings and X-ray photoelectron spectroscopy (XPS) demonstrated that N was successfully incorporated into the lattice of CoO. The XPS of Co 2p and O 1s suggested that the electronic structure of CoO was obviously modulated after the incorporation of N, which improved the adsorption and activation of water molecules. The energy barriers obtained from the Arrhenius relationship of the current density at different temperatures indicated that the N-CoO nanowire arrays accelerated the water dissociation in the HER process. As a result, the N-CoO nanowire arrays showed an excellent performance of HER in alkaline condition. At a current density of 10 mA cm−1, the N-CoO nanowire arrays needed only a 123 mV potential, which was much lower than that of CoO (285 mV). This simple design strategy provides some new inspiration to promote water dissociation for HER in alkaline solutions at the atomic level.
      Citation: Catalysts
      PubDate: 2021-10-14
      DOI: 10.3390/catal11101237
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1238: Photocatalytic Degradation of Tetracycline
           in Aqueous Solution Using Copper Sulfide Nanoparticles

    • Authors: Murendeni P. Ravele, Opeyemi A. Oyewo, Sam Ramaila, Lydia Mavuru, Damian C. Onwudiwe
      First page: 1238
      Abstract: In this paper, spherical-shaped pure phase djurleite (Cu31S16) and roxbyite (Cu7S4) nanoparticles were prepared by a solvothermal decomposition of copper(II) dithiocarbamate complex in dodecanthiol (DDT). The reaction temperature was used to control the phases of the samples, which were represented as Cu31S16 (120 °C), Cu31S16 (150 °C), Cu7S4 (220 °C), and Cu7S4 (250 °C) and were characterized by using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and absorption spectroscopy. The samples were used as photocatalysts for the degradation of tetracycline (TC) under visible light irradiation. The results of the study showed that Cu7S4 (250 °C) exhibited the best activity in the reaction system with the TC degradation rate of up to 99% within 120 min of light exposure, while the Cu31S16 (120 °C) system was only 46.5% at the same reaction condition. In general, roxbyite Cu7S4 (250 °C) could be considered as a potential catalyst for the degradation of TC in solution.
      Citation: Catalysts
      PubDate: 2021-10-14
      DOI: 10.3390/catal11101238
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1239: Carbon-Based Materials for Oxidative
           Desulfurization and Denitrogenation of Fuels: A Review

    • Authors: Fernanda F. Roman, Jose L. Díaz de Tuesta, Adrián M. T. Silva, Joaquim L. Faria, Helder T. Gomes
      First page: 1239
      Abstract: Sulfur (S) and nitrogen (N) are elements naturally found in petroleum-based fuels. S- and N-based compounds in liquid fuels are associated with a series of health and environmental issues. Thus, legislation has become stricter worldwide regarding their content and related emissions. Traditional treatment systems (namely hydrodesulfurization and hydrodenitrogenation) fail to achieve the desired levels of S and N contents in fuels without compromising combustion parameters. Thus, oxidative treatments (oxidative desulfurization–ODS, and oxidative denitrogenation-ODN) are emerging as alternatives to producing ultra-low-sulfur and nitrogen fuels. This paper presents a thorough review of ODS and ODN processes applying carbon-based materials, either in hybrid forms or as catalysts on their own. Focus is brought to the role of the carbonaceous structure in oxidative treatments. Furthermore, a special section related to the use of amphiphilic carbon-based catalysts, which have some advantages related to a closer interaction with the oily and aqueous phases, is discussed.
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101239
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1240: Screening of Acetyl Donors and the Robust
           Enzymatic Synthesis of Acetyl-CoA by 10-Deacetylbaccatin
           III-10-β-O-acetyltransferase

    • Authors: Boyong Zhang, Hao Wang, Ting Gong, Tianjiao Chen, Jingjing Chen, Jinling Yang, Ping Zhu
      First page: 1240
      Abstract: Acetyl-CoA is the precursor of many bio-manufacturing products and is also the hub of the cellular metabolism of energy and substances. However, acetyl-CoA is not a bulk commodity and its application is hindered due to its high cost and low yield. In this study, we screened acetyl donor candidates and utilized 10-deacetylbaccatin III-10-β-O-acetyltransferase (DBAT) in the synthesis of acetyl-CoA with CoASH as the acetyl acceptor. Among the tested candidates, acetylsalicylic acid methyl ester was identified to be the best acetyl donor, followed by acetyl-trans-resveratrol, acetylsalicylic acid ethyl ester, acetylsalicylsalicylic acid, and 4-acetoxyacetanilide. The enzymatic reaction conditions were optimized and the maximum yield of acetyl-CoA reached 14.82 mg/mL, which is the highest yield among all reported approaches to date. Meanwhile, 4.22 mg/mL of the by-product salicylic acid methyl ester, which is another industrial material, was produced. Additionally, a preliminary purification process for acetyl-CoA was established, in which 40 mg acetyl-CoA (HPLC purity > 98%) was acquired from the finished 20 mL reaction system (feeding 46 mg CoASH and 34 mg ASME) with a recovery rate of 86%. Our study lays the foundation for the large-scale production of acetyl-CoA by an enzymatic approach and will promote its application in different fields.
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101240
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1241: Cobalt Boride/g-C3N4 Nanosheets-Assisted
           Electrocatalytic Oxidation of 5-Hydroxymethylfurfural into
           2,5-Furandicarboxylic Acid

    • Authors: Mohammed A. Suliman, Chanbasha Basheer, Wasif Farooq
      First page: 1241
      Abstract: The electrochemical production of 2,5-furandicarboxylic acid (FDCA) from 5-(hydroxymethyl)furfural (HMF) is receiving growing attention. The FDCA-based polyethylene 2,5-furan dicarboxylate (PEF) polymer is a green candidate for substituting polyethylene terephthalate. This work demonstrated a highly efficient CoB/g-C3N4 nanosheet on the surface of the nickel foam as an electrode for the HMF electrooxidation reaction. Electrolysis at a constant potential combined with liquid chromatography showed the formation of FDCA with a yield of 97% with an excellent faradaic efficiency of near 95%. CoB/g-C3N4 achieved a current density of 20 mA cm−2 for HMF oxidation in 1.0 M KOH with 10 mM HMF at 1.37 V vs. RHE before the competing oxygen evolution reaction. The electrocatalyst was effectively reused up to three times without compromising efficiency. This work demonstrates a cheap and active electrocatalyst material for the electrochemical formation of FDCA from HMF and gives perception into the reaction mechanism.
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101241
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1242: Catalysts and Processes for H2S Conversion
           to Sulfur

    • Authors: Barba
      First page: 1242
      Abstract: Hydrogen sulfide is one of the main waste products of the petrochemical industry; it is produced by the catalytic hydrodesulfurization processes (HDS) of the hydrocarbon feedstocks, and it is a byproduct from the sweetening of sour natural gas and from the upgrading of heavy oils, bitumen, and coals [...]
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101242
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1243: Photocatalytic Degradation of Antibiotics
           by Superparamagnetic Iron Oxide Nanoparticles. Tetracycline Case

    • Authors: Sunday Joseph Olusegun, Gonzalo Larrea, Magdalena Osial, Krystyna Jackowska, Pawel Krysinski
      First page: 1243
      Abstract: The challenges associated with the uncontrolled presence of antibiotics such as tetracycline in the environment have necessitated their removal through different techniques. Tetracycline is hard to degrade in living organisms and can even be converted to more toxic substances. In view of this, we synthesized iron oxide nanoparticles with good magnetization (70 emu g−1) and 15 nm particle size for the adsorption and photocatalytic degradation of tetracycline. Characterization carried out on the synthesized iron oxides revealed a bandgap of 1.83 eV and an isoelectric point at pH 6.8. The results also showed that the pH of the solution does not directly influence the adsorption of tetracycline. The adsorption isotherm was consistent with the model proposed by Langmuir, having 97 mg g−1 adsorption capacity. Combined with the superparamagnetic behavior, this capacity is advantageous for the magnetic extraction of tetracycline from wastewater. The mechanisms of adsorption were proposed to be hydrogen bonding and n-π interactions. Photocatalytic degradation studies showed that approximately 40% of tetracycline degraded within 60 min of irradiation time with UV/vis light. The kinetics of photodegradation of tetracycline followed the pseudo-first-order mechanism, proceeding through hydroxyl radicals generated under illumination. Moreover, the photogenerated hydrogen peroxide could lead to heterogeneous photo-Fenton processes on the surface of iron oxide nanoparticles, additionally generating hydroxyl and hydroperoxyl radicals and facilitating photodegradation of tetracycline.
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101243
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1244: Facile Surfactant-Assisted Synthesis of
           BiVO4 Nanoparticulate Films for Solar Water Splitting

    • Authors: Laura Montañés, Camilo A. Mesa, Ana Gutiérrez-Blanco, Christian Robles, Beatriz Julián-López, Sixto Giménez
      First page: 1244
      Abstract: Bismuth vanadate (BiVO4), which has attractive applicability as a photoactive material, presents applications that range from catalysis to water treatment upon visible light irradiation. In this study, we develop a simple synthesis of < 200 nm monoclinic BiVO4 nanoparticles, which were further deposited on transparent conductive substrates by spin coating and calcination, obtaining nanostructured films. The obtained nanostructured BiVO4 photoanodes were tested for water oxidation, leading to promising photocurrents exhibiting competitive onset potentials (~0.3 V vs. RHE). These nanoparticulate BiVO4 photoanodes represent a novel class of highly potential materials for the design of efficient photoelectrochemical devices.
      Citation: Catalysts
      PubDate: 2021-10-15
      DOI: 10.3390/catal11101244
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1245: Dehydroisomerisation of α-Pinene and
           Limonene to p-Cymene over Silica-Supported ZnO in the Gas Phase

    • Authors: Aliyah Alsharif, Natalie Smith, Elena F. Kozhevnikova, Ivan V. Kozhevnikov
      First page: 1245
      Abstract: Silica-supported zinc oxide possessing acid and dehydrogenation functions is an efficient, noble-metal-free bifunctional catalyst for the environment-friendly synthesis of p-Cymene from renewable monoterpene feedstock by gas-phase dehydroisomerisation of α-pinene and limonene in a fixed-bed reactor. The reaction involves acid-catalysed terpene isomerisation to p-menthadienes followed by dehydrogenation to form p-Cymene. Dehydroisomerisation of α-pinene produces p-Cymene with 90% yield at 100% conversion at 370 °C and WHSV = 0.01–0.020 h−1. The reaction with limonene gives a 100% p-Cymene yield at 325 °C and WHSV = 0.080 h−1. ZnO/SiO2 catalyst shows stable performance for over 70 h without co-feeding hydrogen.
      Citation: Catalysts
      PubDate: 2021-10-16
      DOI: 10.3390/catal11101245
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1246: Pt Electrocatalyst Prepared by
           Hydrothermal Reduction onto the Gas Diffusion Layer for High-Temperature
           Formic Acid and Ethanol Fuel PEMFC

    • Authors: Rayane da Silva Cardoso, Bruna Sartório de Castro, Sophya de Andrade Dias, Maria Clara H. Clemente, Sílvia C. L. Dias, José A. Dias, Rudy Crisafulli, José J. Linares, Gesley A. Veloso Martins
      First page: 1246
      Abstract: An alternative method for the preparation of PEMFC electrodes is presented in this work based on the direct deposition of Pt particles onto the gas diffusion layer (Pt@GDL) by hydrothermal reduction of the H2PtCl6 precursor from formic acid, ethylene glycol, and ethanol reductive solutions. There is a successful anchorage of Pt particles via the formation of Pt crystal aggregates. The influence of the reducing agent concentration and temperature was studied to analyze their influence on the size, morphology, and distribution of the Pt particles on the gas GDL. The prepared Pt@GDL was tested for formic acid and ethanol high-temperature H3PO4-doped PEMFC. The Pt@GDL prepared in the formic acid reductive atmosphere presented the best performance associated with the formation of smaller Pt crystals and a more homogeneous dispersion of the Pt particles. For formic acid and ethanol-fed high-temperature PEMFC using a H3PO4-doped polybenzimidazole membrane as the solid electrolyte, maximum power densities of 0.025 and 0.007 W cm−2 were drawn at 200 °C, respectively.
      Citation: Catalysts
      PubDate: 2021-10-17
      DOI: 10.3390/catal11101246
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1247: Calcium Hydroxyapatite: A Highly Stable
           and Selective Solid Catalyst for Glycerol Polymerization

    • Authors: Negisa Ebadipour, Sébastien Paul, Benjamin Katryniok, Franck Dumeignil
      First page: 1247
      Abstract: Calcium-based catalysts are of high interest for glycerol polymerization due to their high catalytic activity and large availability. However, their poor stability under reaction conditions is an issue. In the present study, we investigated the stability and catalytic activity of Ca-hydroxyapatites (HAps) as one of the most abundant Ca-source in nature. A stochiometric, Ca-deficient and Ca-rich HAps were synthesized and tested as catalysts in the glycerol polymerization reaction. Deficient and stochiometric HAps exhibited a remarkable 100% selectivity to triglycerol at 15% of glycerol conversion at 245 °C after 8 h of reaction in the presence of 0.5 mol.% of catalyst. Moreover, under the same reaction conditions, Ca-rich HAp showed a high selectivity (88%) to di- and triglycerol at a glycerol conversion of 27%. Most importantly, these catalysts were unexpectedly stable towards leaching under the reaction conditions based on the ICP-OES results. However, based on the catalytic tests and characterization analysis performed by XRD, XPS, IR, TGA-DSC and ICP-OES, we found that HAps can be deactivated by the presence of the reaction products themselves, i.e., water and polymers.
      Citation: Catalysts
      PubDate: 2021-10-17
      DOI: 10.3390/catal11101247
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1248: Hot Spots of Phytoene Desaturase from
           Rhodobacter Sphaeroides Influencing the Desaturation of Phytoene

    • Authors: Bo Hyun Choi, Sung Hui Kim, Pyung Cheon Lee
      First page: 1248
      Abstract: Phytoene desaturase (CrtI, E.C. 1.3.99.31) shows variable desaturation activity, thereby introducing different numbers of conjugated double bonds (CDB) into the substrate phytoene. In particular, Rhodobacter sphaeroides CrtI is known to introduce additional 6 CDBs into the phytoene with 3 CDBs, generating neurosporene with 9 CDBs. Although in-depth studies have been conducted on the function and phylogenetic evolution of CrtI, little information exists on its range of CDB-introducing capabilities. We investigated the relationship between the structure and CDB-introducing capability of CrtI. CrtI of R. sphaeroides KCTC 12085 was randomly mutagenized to produce carotenoids of different CDBs (neurosporene for 9 CDBs, lycopene for 11 CDBs, and 3,4-didehydrolycopene for 13 CDBs). From six CrtI mutants producing different ratios of neurosporene/lycopene/3,4-didehydrolycopene, three amino acids (Leu163, Ala171, and Ile454) were identified that significantly determined carotenoid profiles. While the L163P mutation was responsible for producing neurosporene as a major carotenoid, A171P and I454T produced lycopene as the major product. Finally, according to the in silico model, the mutated amino acids are gathered in the membrane-binding domain of CrtI, which could distantly influence the FAD binding region and consequently the degree of desaturation in phytoene.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101248
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1249: Organocatalysis: A Tool of Choice for the
           Enantioselective Nucleophilic Dearomatization of Electron-Deficient
           Six-Membered Ring Azaarenium Salts

    • Authors: Claire Segovia, Pierre-Antoine Nocquet, Vincent Levacher, Jean-François Brière, Sylvain Oudeyer
      First page: 1249
      Abstract: Nucleophilic dearomatization of azaarenium salts is a powerful strategy to access 3D scaffolds of interest from easily accessible planar aromatic azaarene compounds. Moreover, this approach yields complex dihydroazaarenes by allowing the functionalization of the scaffold simultaneously to the dearomatization step. On the other side, organocatalysis is nowadays recognized as one of the pillars of the asymmetric catalysis field of research and is well-known to afford a high level of enantioselectivity for a myriad of transformations thanks to well-organized transition states resulting from low-energy interactions (electrostatic and/or H-bonding interactions…). Consequently, in the last fifteen years, organocatalysis has met great success in nucleophilic dearomatization of azaarenium salts. This review summarizes the work achieved up to date in the field of organocatalyzed nucleophilic dearomatization of azaarenium salts (mainly pyridinium, quinolinium, quinolinium and acridinium salts). A classification by organocatalytic mode of activation will be disclosed by shedding light on their related advantages and drawbacks. The versatility of the dearomatization approach will also be demonstrated by discussing several chemical transformations of the resulting dihydroazaarenes towards the synthesis of structurally complex compounds.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101249
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1250: Facile and Rapid Synthesis of Durable
           SSZ-13 Catalyst Using Choline Chloride Template for Methanol-to-Olefins
           Reaction

    • Authors: Xiongchao Lin, Sasha Yang, Xiaojia Li, Caihong Wang, Yonggang Wang
      First page: 1250
      Abstract: In the current study, a facile and rapid synthesis approach for a SSZ-13 catalyst using choline chloride (CC) as a template was proposed, and the catalytic performance for the methanol-to-olefins (MTO) reaction was examined. With a proper amount of CC addition (i.e., m(CC)/m(SiO2)=0.14), uniform and homogeneously distributed cubic SSZ-13 crystals were obtained within 4 h with lower aggregation. The synthesized catalyst demonstrated excellent porous features with a total specific surface area and mesopore volume of 641.71 m2·g−1 and 0.04 cm3·g−1, respectively. The optimized strong and weak acid sites on SSZ-13 were obtained by regulating the m(CC)/m(SiO2) ratio. The less strong acid sites and a larger amount of weak acid sites in the synthesized catalyst were conducive to the catalytic performance of the MTO reaction under a lower reaction temperature (450 °C). The appropriate acidity and well-developed pore structure of synthesized SSZ-13 could also slow down the carbon deposition rate and, thus, significantly improve the catalytic lifetime of the catalyst. The methanol conversion rate and initial selectivity of light olefin using the synthesized catalyst could maintain over 95% and 50%, respectively, and a lifetime of 172 min was achieved. Although the low olefin selectivity of the synthesized SSZ-13 catalyst was slightly lower than that of the purchased one, its desirable features were thought to have good potential for industrial application.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101250
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1251: Apiose-Relevant Glycosidases

    • Authors: Elena Karnišová Potocká, Mária Mastihubová, Vladimír Mastihuba
      First page: 1251
      Abstract: Apiose is a branched pentose naturally occurring either as a component of the plant cell wall polysaccharides or as a sugar moiety present in numerous plant secondary metabolites such as flavonoid and phenylethanoid glycosides, substrates in plant defense systems or as glycosylated aroma precursors. The enzymes catalyzing hydrolysis of such apiosylated substances (mainly glycosidases specific towards apiose or acuminose) have promising applications not only in hydrolysis (flavor development), but potentially also in the synthesis of apiosides and apioglucosides with pharmaceutical relevance. This review summarizes the actual knowledge of glycosidases recognizing apiose and their potential application in biocatalysis.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101251
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1252: Combustion-Synthesized Porous
           CuO-CeO2-SiO2 Composites as Solid Catalysts for the Alkenylation of
           C(sp3)-H Bonds Adjacent to a Heteroatom via Cross-Dehydrogenative Coupling
           

    • Authors: Ha V. Le, Vy B. Nguyen, Hai H. Pham, Khoa D. Nguyen, Phuoc H. Ho, Philippe Trens, Francesco Di Renzo
      First page: 1252
      Abstract: A series of mixed oxides of CuO, CeO2, and SiO2 were prepared by gel combustion and employed for the first time as efficient solid catalysts in a solvent-less liquid-phase cross-dehydrogenative coupling. The facile one-pot catalyst synthesis resulted in highly porous materials presenting large specific surface areas and strong metal–support interactions. The interaction with highly dispersed CeO2 enhanced the redox properties of the CuO species. The CuO-CeO2-SiO2 composites exhibited excellent catalytic performance for the selective coupling between 1,1-diphenylethylene and tetrahydrofuran with a yield up to 85% of 2-(2,2-diphenylvinyl)-tetrahydrofuran in the presence of di-tert-butyl peroxide (DTPB) and KI. Albeit both CuO and CeO2 species are proved to be responsible for the catalytic conversion, a great synergistic improvement in the catalytic activity was obtained by extended contact between the oxide phases by high porosity in comparison with the reactions using individual Cu or Ce catalysts. The activity of the composite catalyst was shown to be highly stable after five successive reaction cycles. Furthermore, the study scope was extended to the synthesis of different derivatives via composite-catalyzed coupling of C(sp2)-H with C(sp3-H) adjacent to a heteroatom. The good yields recorded proved the general validity of this composite for the cross-dehydrogenative coupling reaction rarely performed on solid catalysts.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101252
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1253: Facile Preparation of Carbon Nitride-ZnO
           Hybrid Adsorbent for CO2 Capture: The Significant Role of Amine Source to
           Metal Oxide Ratio

    • Authors: Siti Aishah Anuar, Khairul Naim Ahmad, Ahmed Al-Amiery, Mohd Shahbudin Masdar, Wan Nor Roslam Wan Isahak
      First page: 1253
      Abstract: The presence of CO2 in gaseous fuel and feedstock stream of chemical reaction was always considered undesirable. High CO2 content will decrease quality and heating value of gaseous fuel, such as biohydrogen, which needs a practical approach to remove it. Thus, this work aims to introduce the first C3N4-metal oxide hybrid for the CO2 cleaning application from a mixture of CO2-H2 gas. The samples were tested for their chemical and physical properties, using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), physical adsorption analysis (BET), fourier-transform infrared (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The CO2 capacity test was carried out by means of a breakthrough test at 1 atm and 25° C using air as a desorption system. Among the samples, amine/metal oxide mass ratio of 2:1 (CNHP500-2(2-1)) showed the best performance of 26.9 wt. % (6.11 mmol/g), with a stable capacity over 6 consecutive cycles. The hybrid sample also showed 3 times better performance than the raw C3N4. In addition, it was observed that the hydrothermal C3N4 synthesis method demonstrated improved chemical properties and adsorption performance than the conventional dry pyrolysis method. In summary, the performance of hybrid samples depends on the different interactive factors of surface area, pore size and distribution, basicity, concentration of amine precursors, ratio of amines precursors to metal oxide, and framework stability.
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101253
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1254: Catalytic Conversion of Lignins for
           Valuable Chemicals

    • Authors: Valery E. Tarabanko
      First page: 1254
      Abstract: Modern civilization is moving from fossil sources of raw materials and, consequently, energy to renewable resources: plant raw materials and solar and wind energy [...]
      Citation: Catalysts
      PubDate: 2021-10-18
      DOI: 10.3390/catal11101254
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1255: Underground Upgrading of the Heavy Crude
           Oil in Content-Saturated Sandstone with Aquathermolysis in the Presence of
           an Iron Based Catalyst

    • Authors: Sergey A. Sitnov, Irek I. Mukhamatdinov, Dmitry A. Feoktistov, Yaroslav V. Onishchenko, Vladislav A. Sudakov, Marat I. Amerkhanov, Alexey V. Vakhin
      First page: 1255
      Abstract: Increasing the efficiency of thermal recovery methods is an important and relevant task. This study is devoted to reducing heavy components (resins and asphaltenes) and quality improvement of heavy oil by catalytic hydrothermal treatment. The object of this study is a bituminous sandstone sample from the Ashal’cha reservoir. The catalytic (iron tallate) hydrothermal simulation was carried out under reservoir conditions (200 °C, 30 bar). The composition and physicochemical characteristics of the products were studied using elemental and SARA analysis, MALDI, GC-MS, FT-IR. Moreover, the extracted rock is analyzed in XRD and DSA (Drop Shape Analyzer). The introduction of catalyst in combination with a hydrogen donor reduces the content of resins by 22.0%wt. with an increase in the share of saturated hydrocarbons by 27%wt. The destructive hydrogenation leads to a decrease in the sulfur content of upgrading products. This is crucial for the oil reservoirs of the Tatarstan Republic, as their crude oils are characterized by high sulfur content. According to the wettability data, the hydrophilicity of the rock surface increases due to inhibition of the coke formation after the introduction of the catalytic complex. Thus, the oil recovery factor can be increased due to the alteration of the oil-wetting properties of reservoir rocks.
      Citation: Catalysts
      PubDate: 2021-10-19
      DOI: 10.3390/catal11101255
      Issue No: Vol. 11, No. 10 (2021)
       
  • Catalysts, Vol. 11, Pages 1256: The Effect of Transition Metal
           Substitution in the Perovskite-Type Oxides on the Physicochemical
           Properties and the Catalytic Performance in Diesel Soot Oxidation

    • Authors: Liliya V. Yafarova, Grigory V. Mamontov, Irina V. Chislova, Oleg I. Silyukov, Irina A. Zvereva
      First page: 1256
      Abstract: The paper is focused on the Fe for Co substitution effect on the redox and catalytic properties in the perovskite structure of GdFeO3. The solid oxides with the composition GdFe1−xCoxO3 (x = 0; 0.2; 0.5; 0.8; 1) were obtained by the sol-gel method and characterized by various methods: X-ray diffraction (XRD), temperature-programmed reduction (H2-TPR), N2 sorption, temperature-programmed desorption of oxygen (TPD-O2), simultaneous thermal analysis (STA), and X-ray photoelectron spectroscopy (XPS). The H2-TPR results showed that an increase in the cobalt content in the GdFe1−xCoxO3 (x = 0; 0.2; 0.5; 0.8; 1) leads to a decrease in the reduction temperature. Using the TPD-O2 and STA methods, the lattice oxygen mobility is increasing in the course of the substitution of Fe for Co. Thus, the Fe substitution in the perovskite leads to an improvement in the oxygen reaction ability. Experiments on the soot oxidation reveal that catalytic oxidation ability increases in the series: GdFe0.5Co0.5O3 ˂ GdFe0.2Co0.8O3 ˂ GdCoO3, which is in good correlation with the increasing oxygen mobility according to H2-TPR, TPD-O2, and STA results. The soot oxidation over GdFeO3 and GdFe0.8Co0.2O3 is not in this range due to the impurities of iron oxides and higher specific surface area.
      Citation: Catalysts
      PubDate: 2021-10-19
      DOI: 10.3390/catal11101256
      Issue No: Vol. 11, No. 10 (2021)
       
 
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