Subjects -> CHEMISTRY (Total: 1021 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (746 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (49 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (746 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: 14)
ACS Catalysis     Hybrid Journal   (Followers: 76)
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: 3)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 448)
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: 53)
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: 235)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 353)
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: 484)
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: 213)
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: 25)
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: 265)
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: 224)
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: 336)
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: 24)
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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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 1145: Evaluation of Goethite as a Catalyst for
           the Thermal Stage of the Westinghouse Process for Hydrogen Production

    • Authors: Carmen M. Fernández-Marchante, Alexandra Raschitor, Ismael F. Mena, Manuel A. Rodrigo, Justo Lobato
      First page: 1145
      Abstract: This work focuses on the evaluation of goethite as a catalyst for the transformation of sulfuric acid into sulfur dioxide, a reaction with great interest for the hybrid electrochemical-thermoelectrochemical Westinghouse cycle for hydrogen production. A comparison of the performance of goethite with that of CuO, Fe2O3, and SiC has been carried out. Moreover, a mixture of those catalysts was evaluated. The results demonstrate that goethite can be used as a catalyst for the thermal decomposition of sulfuric acid in the Westinghouse cycle, with an activity higher than that of SiC but lower than that of Fe2O3 and CuO. However, it does not undergo sintering during its use, but just produces small particles in its surface, which remain after the treatment. Mixtures of Fe2O3 with SiC or goethite do not produce synergism, thus operating each catalyst in an independent way.
      Citation: Catalysts
      PubDate: 2021-09-24
      DOI: 10.3390/catal11101145
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1146: Practical Approaches towards NOx Emission
           Mitigation from Fluid Catalytic Cracking (FCC) Units

    • Authors: Vjunov, Kharas, Komvokis, Dundee, Yilmaz
      First page: 1146
      Abstract: There appears to be consensus among the general public that curtailing harmful emissions resulting from industrial, petrochemical and transportation sectors is a common good. However, there is also a need for balancing operating expenditures for applying the required technical solutions and implementing advanced emission mitigation technologies to meet desired sustainability goals. The emission of NOx from Fluid Catalytic Cracking (FCC) units in refineries for petroleum processing is a major concern, especially for those units located in densely populated urban settings. In this work we strive to review options towards cost-efficient and pragmatic emissions mitigation using optimal amounts of precious metal while evaluating the potential benefits of typical promoter dopant packages. We demonstrate that at present catalyst development level the refinery is no longer forced to make a promoter selection based on preconceived notions regarding precious metal activity but can rather make decisions based on the best “total cost” financial impact to the operation without measurable loss of the CO/NOx emission selectivity.
      Citation: Catalysts
      PubDate: 2021-09-24
      DOI: 10.3390/catal11101146
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1147: Recent Manganese Oxide Octahedral
           Molecular Sieves (OMS–2) with Isomorphically Substituted Cationic
           Dopants and Their Catalytic Applications

    • Authors: Ferran Sabaté, María J. Sabater
      First page: 1147
      Abstract: The present report describes the structural and physical–chemical variations of the potassium manganese oxide mineral, α–MnO2, which is a specific manganese octahedral molecular sieve (OMS) named cryptomelane (K–OMS–2), with different transition metal cations. We will describe some frequently used synthesis methods to obtain isomorphic substituted materials [M]–K–OMS–2 by replacing the original manganese cationic species in a controlled way. It is important to note that one of the main effects of doping is related to electronic environmental changes, as well as to an increase of oxygen species mobility, which is ultimately related to the creation of new vacancies. Given the interest and the importance of these materials, here, we collect the most recent advances in [M]–K–OMS–2 oxides (M = Ag, Ce, Mo, V, Nb, W, In, Zr and Ru) that have appeared in the literature during the last ten years, leaving aside other metal–doped [M]–K–OMS–2 oxides that have already been treated in previous reviews. Besides showing the most important structural and physic-chemical features of these oxides, we will highlight their applications in the field of degradation of pollutants, fine chemistry and electrocatalysis, and will suggest potential alternative applications.
      Citation: Catalysts
      PubDate: 2021-09-24
      DOI: 10.3390/catal11101147
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1148: Catalytic Oxidations with
           meta-Chloroperoxybenzoic Acid (m-CPBA) and Mono- and Polynuclear Complexes
           of Nickel: A Mechanistic Outlook

    • Authors: Nesterov, Nesterova
      First page: 1148
      Abstract: Selective catalytic functionalization of organic substrates using peroxides as terminal oxidants remains a challenge in modern chemistry. The high complexity of interactions between metal catalysts and organic peroxide compounds complicates the targeted construction of efficient catalytic systems. Among the members of the peroxide family, m-chloroperoxybenzoic acid (m-CPBA) exhibits quite complex behavior, where numerous reactive species could be formed upon reaction with a metal complex catalyst. Although m-CPBA finds plenty of applications in fine organic synthesis and catalysis, the factors that discriminate its decomposition routes under catalytic conditions are still poorly understood. The present review covers the advances in catalytic C–H oxidation and olefine epoxidation with m-CPBA catalyzed by mono- and polynuclear complexes of nickel, a cheap and abundant first-row transition metal. The reaction mechanisms are critically discussed, with special attention to the O–O bond splitting route. Selectivity parameters using recognized model hydrocarbon substrates are summarized and important factors that could improve further catalytic studies are outlined.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101148
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1149: Entrapment of Phenylalanine Ammonia-Lyase
           in Nanofibrous Polylactic Acid Matrices by Emulsion Electrospinning

    • Authors: Gábor Koplányi, Evelin Sánta-Bell, Zsófia Molnár, Gergő Dániel Tóth, Muriel Józó, András Szilágyi, Ferenc Ender, Béla Pukánszky, Beáta G. Vértessy, László Poppe, Diána Balogh-Weiser
      First page: 1149
      Abstract: Immobilization of the recombinant, plant-derived Petroselinum crispum phenylalanine ammonia lyase (PcPAL) in electrospun matrices have the potential to create promising, easy-to-use biocatalysts. Polylactic acid (PLA) a biologically inert, commercial biopolymer, was chosen as the material of the carrier system. PLA could be electrospun properly only from water-immiscible organic solvents, which limits its application as a carrier of sensitive biological objects. The emulsion electrospinning is a proper solution to overcome this issue using non-ionic emulsifiers with different hydrophilic-lipophilic balance (HLB) values. The stabilized emulsion could protect the sensitive PcPAL dissolved in the aqueous buffer phase and improve fiber formation, plus help to keep the biocatalytic activity of enzymes. In this study, the first approach is described to produce PLA nanofibers containing PcPAL enzymes by emulsion electrospinning and to use the resulted biocatalyst in the ammonia elimination reaction from l-phenylalanine.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101149
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1150: Catalytic Hydrocracking of Fresh and Waste
           Frying Oil over Ni- and Mo-Based Catalysts Supported on Sulfated Silica
           for Biogasoline Production

    • Authors: Karna Wijaya, Asma Nadia, Arina Dinana, Amalia Febia Pratiwi, Alfrets Daniel Tikoalu, Arief Cahyo Wibowo
      First page: 1150
      Abstract: The synthesis of a sulfated silica catalyst and its modification with Ni and/or Mo metal, along with its application for the hydrocracking of fresh and waste frying oil into biogasoline, were conducted. Synthesis of the catalysts was initiated with the sulfation of silica (SiO2) material by H2SO4 using the sol-gel method. Ni and/or Mo metal were impregnated into the SO4/SiO2 matrix with concentration variations of 1, 2, and 3 wt%. The sulfation process and promotion by Molybdenum (Mo) metal in the modified catalyst successfully increased the catalytic activity and selectivity. Among the catalysts investigated, Ni-SS2 exhibited the best performance for the hydrocracking reaction with waste frying oil. This catalyst was able to achieve a conversion of the liquid product of 71.47% and a selectivity of 58.73% for the gasoline fraction (C5-C12). NiMo-SS3 showed the highest percentage of activity and selectivity in the hydrocracking of fresh frying oil at 51.50 and 43.22 wt%, respectively.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101150
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1151: CuO-In2O3 Catalysts Supported on
           Halloysite Nanotubes for CO2 Hydrogenation to Dimethyl Ether

    • Authors: Alexey Pechenkin, Dmitry Potemkin, Maria Rubtsova, Pavel Snytnikov, Pavel Plyusnin, Aleksandr Glotov
      First page: 1151
      Abstract: Hydrogenation of CO2 relative to valuable chemical compounds such as methanol or dimethyl ether (DME) is an attractive route for reducing CO2 emissions in the atmosphere. In the present work, the hydrogenation of CO2 into DME over CuO-In2O3, supported on halloysite nanotubes (HNT) was investigated in the temperature range 200–300 °C at 40 atm. HNT appears to be novel promising support for bifunctional catalysts due to its thermal stability and the presence of acidic sites on its surface. CuO-In2O3/HNT catalysts demonstrate higher CO2 conversion and DME selectivity compared to non-indium CuO/HNT catalysts. The catalysts were investigated by N2 adsorption, X-ray diffraction, hydrogen-temperature programmed reduction and transition electron microscopy. The acid sites were analyzed by temperature programmed desorption of ammonia. It was shown that CuO/HNT was unstable under reaction conditions in contrast to CuO-In2O3/HNT. The best CuO-In2O3/HNT catalyst provided CO2 conversion of 7.6% with 65% DME selectivity under P = 40 atm, T = 250 °C, gas hour space velocity 12,000 h−1 and H2:CO2 = 3:1.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101151
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1152: Investigation of the Characteristics of
           Catalysis Synergy during Co-Combustion for Coal Gasification Fine Slag
           with Bituminous Coal and Bamboo Residue

    • Authors: Yixin Zhang, Wenke Jia, Rumeng Wang, Yang Guo, Fanhui Guo, Jianjun Wu, Baiqian Dai
      First page: 1152
      Abstract: As a kind of solid waste from coal chemical production, the disposal of coal gasification fine slag poses a certain threat to the environment and the human body. It is essential for gasification slag (GS) to realize rational utilization. GS contains fewer combustible materials, and the high heating value is only 9.31 MJ/Kg, which is difficult to burn in combustion devices solely. The co-combustion behavior of the tri-fuel blends, including bituminous coal (BC), gasification slag (GS), and bamboo residue (BR), was observed by a thermogravimetric analyzer. The TGA results showed that the combustibility increased owing to the addition of BC and BR, and the ignition and burnout temperatures were lower than those of GS alone. The combustion characteristics of the blended samples became worse with the increase in the proportion of GS. The co-combustion process was divided into two main steps with obvious interactions (synergistic and antagonistic). The synergistic effect was mainly attributed to the catalysis of the ash-forming metals reserved with the three raw fuels and the diffusion of oxygen in the rich pore channels of GS. The combustion reaction of blending samples was dominated by O1 and D3 models. The activation energy of the blending combustion decreased compared to the individual combustion of GS. The analysis of the results in this paper can provide some theoretical guidance for the resource utilization of fine slag.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101152
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1153: Regeneration of an Aged
           Hydrodesulfurization Catalyst by Non-Thermal Plasma: Characterization of
           Refractory Coke Molecules

    • Authors: Hawraa Srour, Nadia Guignard, Mehrad Tarighi, Elodie Devers, Adrien Mekki-Berrada, Joumana Toufaily, Tayssir Hamieh, Catherine Batiot-Dupeyrat, Ludovic Pinard
      First page: 1153
      Abstract: This study describes the phenomena involved during the regeneration of an aged industrial hydrodesulfurization catalyst (CoMoP/Al2O3) using a non-thermal plasma at a low temperature (200 °C). The changes occurring during regeneration were studied by characterizing spent, partially, and fully regenerated catalysts by XRD, Raman, TEM spectroscopy, and the coke deposited on the catalyst surface by Laser desorption/ionization time-of-flight mass spectrometry (LDI TOF/MS). The coke is a mixture of several polycyclic molecules, the heaviest with a coronene backbone, containing up to seven sulfur atoms. This kinetic study shows that the oxidation rate depends on the nature of the coke. Hence, explaining the formation of VOCs from heavy polycyclic carbon molecules without complete oxidation to CO2. However, XRD and Raman spectroscopies evidence CoMoO4 formation after a long treatment time, indicating hot spots during the regeneration.
      Citation: Catalysts
      PubDate: 2021-09-25
      DOI: 10.3390/catal11101153
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1154: Comment on Weber et al. Mayenite-Based
           Electride C12A7e−: A Reactivity and Stability Study. Catalysts 2021, 11,

    • Authors: Yasunori Inoue, Masaaki Kitano, Hideo Hosono
      First page: 1154
      Abstract: In 2012, we reported that C12A7 electride (C12A7: e−) significantly promotes the catalytic activity of Ru nanoparticles for ammonia synthesis through the electron donation from the C12A7: e− with a low work function (2.4 eV) to Ru [...]
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101154
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1155: Reply to Inoue et al. Comment on “Weber
           et al. Mayenite-Based Electride C12A7e−: A Reactivity and Stability
           Study. Catalysts 2021, 11, 334”

    • Authors: Sebastian Weber, Stephan A. Schunk
      First page: 1155
      Abstract: With gratitude, we would like to thank Yasunori Inoue, Masaaki Kitano and Hideo Hosono for their comments on our recently published article and express our appreciation for the critical discussion of our results [...]
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101155
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1156: Pre-Coking Strategy Strengthening
           Stability Performance of Supported Nickel Catalysts in Chloronitrobenzene

    • Authors: Ping Wang, Shiyi Wang, Ronghe Lin, Xiaoling Mou, Yunjie Ding
      First page: 1156
      Abstract: Supported nickel catalysts represent a class of important catalytic materials in selective hydrogenations, but applications are frequently limited by metal agglomeration or active-site blocking induced by the presence of hydrogen halides. Herein, we report a novel pre-coking strategy, exposing the nickel nanoparticles under methane dry reforming conditions to manipulate performance in the continuous-flow hydrogenation of 1,2-dichloro-4-nitrobenzene. Compared with the pristine nickel catalyst, the nanotube-like coke-modified nickel catalyst showed weakened hydrogenating ability, but much improved stability and slightly better selectivity to the target product, 3,4-dichloroaniline. Characterization results revealed that the strengthened stability performance can be mainly linked to the reduced propensity to retain chlorine species, which seems to block the access of the substrate molecules to the active sites, and thus is a major cause of catalyst deactivation on the pristine nickel catalyst. Coke deposition can occur on the pre-coked nickel catalyst but not on the pristine analog; however, the impact on the stability performance is much milder compared with that on chlorine uptake. In addition, the presence of coke is also beneficial in restraining the growth of the nickel nanoparticles. Generally, the developed method might provide an alternative perspective on the design of novel transition-metal-based catalytic materials for other hydrogenation applications under harsh conditions.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101156
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1157: Structure-Function and Industrial
           Relevance of Bacterial Aminopeptidase P

    • Authors: Muhamad Nadzmi Omar, Raja Noor Zaliha Raja Abd Rahman, Noor Dina Muhd Noor, Wahhida Latip, Victor Feizal Knight, Mohd Shukuri Mohamad Ali
      First page: 1157
      Abstract: Aminopeptidase P (APPro, E.C cleaves N-terminal amino acids from peptides and proteins where the penultimate residue is proline. This metal-ion-dependent enzyme shares a similar fold, catalytic mechanism, and substrate specificity with methionine aminopeptidase and prolidase. It adopts a canonical pita bread fold that serves as a structural basis for the metal-dependent catalysis and assembles as a tetramer in crystals. Similar to other metalloaminopeptidase, APPro requires metal ions for its maximal enzymatic activity, with manganese being the most preferred cation. Microbial aminopeptidase possesses unique characteristics compared with aminopeptidase from other sources, making it a great industrial enzyme for various applications. This review provides a summary of recent progress in the study of the structure and function of aminopeptidase P and describes its various applications in different industries as well as its significance in the environment.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101157
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1158: Immobilization of Fusarium solani Cutinase
           onto Magnetic Genipin-Crosslinked Chitosan Beads

    • Authors: Zhanyong Wang, Tingting Su, Jingjing Zhao
      First page: 1158
      Abstract: Genipin was used as a crosslinking agent to prepare magnetic genipin-crosslinked chitosan beads, which were then used as a carrier for immobilizing recombinant cutinase from Fusarium solani (FSC) to obtain immobilized FSC. The optimal temperature for the immobilized FSC was 55 °C, which was 5 °C higher than that of the free enzyme, whereas its optimal pH was increased from 8.0 to 9.0; this indicates that the immobilized FSC had improved pH and thermal stability. After repeated use for 10 cycles, the activity of the immobilized FSC remained at more than 50%; after being stored at 4 °C for 30 days, its activity was still approximately 88%. We also found that the Km of the immobilized FSC was higher than that of the free enzyme. These results indicate that the performance of FSC was improved after immobilization, which is an important basis for the subsequent application of FSC in industrial production.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101158
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1159: CO2 Hydrogenation to Synthetic Natural Gas
           over Ni, Fe and Co–Based CeO2–Cr2O3

    • Authors: Chalempol Khajonvittayakul, Vut Tongnan, Suksun Amornraksa, Navadol Laosiripojana, Matthew Hartley, Unalome Wetwatana Hartley
      First page: 1159
      Abstract: CO2 methanation was studied over monometallic catalyst, i.e., Ni, Fe and Co; on CeO2-Cr2O3 support. The catalysts were prepared using one-pot hydrolysis of mixed metal nitrates and ammonium carbonate. Physicochemical properties of the pre- and post-exposure catalysts were characterized by X-Ray Powder Diffraction (XRD), Hydrogen Temperature Programmed Reduction (H2-TPR), and Field Emission Scanning Electron Microscope (FE-SEM). The screening of three dopants over CeO2-Cr2O3 for CO2 methanation was conducted in a milli-packed bed reactor. Ni-based catalyst was proven to be the most effective catalyst among all. Thus, a group of NiO/CeO2-Cr2O3 catalysts with Ni loading was investigated further. 40 % NiO/CeO2-Cr2O3 exhibited the highest CO2 conversion of 97.67% and CH4 selectivity of 100% at 290 °C. The catalytic stability of NiO/CeO2-Cr2O3 was tested towards the CO2 methanation reaction over 50 h of time-on-stream experiment, showing a good stability in term of catalytic activity.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101159
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1160: Impact of Doping and Additive Applications
           on Photocatalyst Textural Properties in Removing Organic Pollutants: A

    • Authors: Safia Syazana Mohtar, Farhana Aziz, Ahmad Fauzi Ismail, Nonni Soraya Sambudi, Hamidah Abdullah, Ahmad Nazrul Rosli, Bunsho Ohtani
      First page: 1160
      Abstract: The effect of ion doping and the incorporation of additives on photocatalysts’ textural properties have been reviewed. Generally, it can be summarised that ion doping and additives have beneficial effects on photocatalytic efficiency and not all have an increase in the surface area. The excessive amount of dopants and additives will produce larger aggregated particles and also cover the mesoporous structures, thereby increasing the pore size (Pd) and pore volume (Pv). An excessive amount of dopants also leads to visible light shielding effects, thus influence photocatalytic performance. Ion doping also shows some increment in the surface areas, but it has been identified that synergistic effects of the surface area, porosity, and dopant amount contribute to the photocatalytic performance. It is therefore important to understand the effect of doping and the application of additives on the textural properties of photocatalysts, thus, their performance. This review will provide an insight into the development of photocatalyst with better performance for wastewater treatment applications.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101160
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1161: Covalent Immobilisation of a Nanoporous
           Platinum Film onto a Gold Screen-Printed Electrode for Highly Stable and
           Selective Non-Enzymatic Glucose Sensing

    • Authors: Wesley McCormick, Pádraig McDonagh, John Doran, Denis McCrudden
      First page: 1161
      Abstract: Progress in the development of commercially available non-enzymatic glucose sensors continues to be problematic due to issues regarding selectivity, reproducibility and stability. Overcoming these issues is a research challenge of significant importance. This study reports a novel fabrication process using a double-layer self-assembly of (3 mercaptopropyl)trimethoxysilane (MPTS) on a gold substrate and co-deposition of a platinum–copper alloy. The subsequent electrochemical dealloying of the less noble copper resulted in a nanoporous platinum structure on the uppermost exposed thiol groups. Amperometric responses at 0.4 V vs. Ag/AgCl found the modification to be highly selective towards glucose in the presence of known interferants. The sensor propagated a rapid response time <5 s and exhibited a wide linear range from 1 mM to 18 mM. Additionally, extremely robust stability was attributed to enhanced attachment due to the strong chemisorption between the gold substrate and the exposed thiol of MPTS. Incorporation of metallic nanomaterials using the self-assembly approach was demonstrated to provide a more reproducible and controlled molecular architecture for sensor fabrication. The successful application of the sensor in real blood serum samples displayed a strong correlation with clinically obtained glucose levels.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101161
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1162: Bioethanol Upgrading to Renewable Monomers
           Using Hierarchical Zeolites: Catalyst Preparation, Characterization, and
           Catalytic Studies

    • Authors: Ploychanok Iadrat, Chularat Wattanakit
      First page: 1162
      Abstract: Bioethanol is one of the most promising renewable resources for the production of important monomers. To date, there have been various processes proposed for bioethanol conversion to renewable monomers. In this review, the catalytic bioethanol upgrading to various types of monomers using hierarchical zeolites as catalysts is illustrated, including the recent design and preparation of hierarchical zeolites for these catalytic processes. The characterizations of catalysts including textural properties, pore architectures, acidic properties, and active species are also exemplified. Moreover, the catalytic studies with various processes of monomer production from bioethanol including bioethanol dehydration, bioethanol to hydrocarbons, and bioethanol to butadiene are revealed in terms of catalytic activities and mechanistic studies. In addition, the future perspectives of these catalytic circumstances are proposed in both economic and sustainable development contexts.
      Citation: Catalysts
      PubDate: 2021-09-26
      DOI: 10.3390/catal11101162
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1163: Effect of Pyrolysis Conditions on the
           Performance of Co–Doped MOF–Derived Carbon Catalysts for Oxygen
           Reduction Reaction

    • Authors: Ning Cui, Kexiao Bi, Wei Sun, Qianqian Wu, Yinan Li, Tiewei Xu, Binjiang Lv, Shuling Zhang
      First page: 1163
      Abstract: MOF–derived porous carbon is a type of promising catalyst to replace expensive Pt–based catalysts for oxygen reduction reaction (ORR). The catalytic activity for ORR depends closely on pyrolysis conditions. In this work, a Co–doped ZIF–8 material was chosen as a research object. The effect of pyrolysis conditions (temperature, heating rate, two–step heating) on the ORR performance of ZIF–derived carbon catalysts was systematically studied. The Co–ZIF–8 catalyst carbonized at 900 °C exhibits better ORR catalytic activity than that carbonized at 800 °C and 1000 °C. Moreover, a low heating rate can enhance catalytic activity. Two–step pyrolysis is proven to be an effective way to improve the performance of catalysts. Reducing the heating rate in the low–temperature stage is more beneficial to the ORR performance, compared to the heating rate in the high–temperature stage. The results show that the Co–ZIF–8 catalyst exhibits the best performance when the precursor was heated to 350 °C at 2 °C/min, and then heated to 900 °C at 5 °C/min. The optimum Co–ZIF–8 catalyst shows a half–wave potential of 0.82 V and a current density of 5.2 mA·cm−2 in 0.1 M KOH solution. It also exhibits high content of defects and good graphitization. TEM mapping shows that Co and N atoms are highly dispersed in the polyhedral carbon skeleton. However, two–step pyrolysis has no significant effect on the stability of the catalyst.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101163
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1164: Iridium Oxide Enabled Sensors Applications

    • Authors: Qiuchen Dong, Xiangcheng Sun, Songbing He
      First page: 1164
      Abstract: There have been numerous studies applying iridium oxides in different applications to explore their proton-change-based reactions since the 1980s. Iridium oxide can be fabricated directly by applying electrodeposition, sputter-coating method, or oxidation of iridium wire. Generally, there have been currently two approaches in applying iridium oxide to enable its sensing applications. One was to improve or create different electrolytes with (non-)electrodeposition method for better performance of Nernst Constant with the temperature-related system. The mechanism behind the scenes were summarized herein. The other was to change the structure of iridium oxide through different kinds of templates such as photolithography patterns, or template-assisted direct growth methods, etc. to improve the sensing performance. The detection targets varied widely from intracellular cell pH, glucose in an artificial sample or actual urine sample, and the hydrogen peroxide, glutamate or organophosphate pesticides, metal-ions, etc. This review paper has focused on the mechanism of electrodeposition of iridium oxide in aqueous conditions and the sensing applications towards different biomolecules compounds. Finally, we summarize future trends on Iridium oxide based sensing and predict future work that could be further explored.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101164
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1165: Multifunctional Electrocatalysis on
           Single-Site Metal Catalysts: A Computational Perspective

    • Authors: Ritums Cepitis, Nadezda Kongi, Vitali Grozovski, Vladislav Ivaništšev, Enn Lust
      First page: 1165
      Abstract: Multifunctional electrocatalysts are vastly sought for their applications in water splitting electrolyzers, metal-air batteries, and regenerative fuel cells because of their ability to catalyze multiple reactions such as hydrogen evolution, oxygen evolution, and oxygen reduction reactions. More specifically, the application of single-atom electrocatalyst in multifunctional catalysis is a promising approach to ensure good atomic efficiency, tunability and additionally benefits simple theoretical treatment. In this review, we provide insights into the variety of single-site metal catalysts and their identification. We also summarize the recent advancements in computational modeling of multifunctional electrocatalysis on single-site catalysts. Furthermore, we explain each modeling step with open-source-based working examples of a standard computational approach.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101165
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1166: Remediation of Diethyl Phthalate in
           Aqueous Effluents with TiO2-Supported Rh0 Nanoparticles as Multicatalytic

    • Authors: Audrey Denicourt-Nowicki, Carl-Hugo Pélisson, Isabelle Soutrel, Lidia Favier, Alain Roucoux
      First page: 1166
      Abstract: An innovative “domino” process, based on an arene hydrogenation followed by a photocatalytic step, was designed for the remediation of endocrine disrupting compounds, in highly concentrated aqueous effluents. The novelty relies on the use of TiO2-supported zerovalent Rh nanoparticles as multicatalytic materials (MCMs) for this two-step treatment, applied on diethyl phthalate, which is a model aromatic pollutant frequently present in aquatic environments. This nanocomposite advanced material, which was easily prepared by a green, wet impregnation methodology, proved to be active in the successive reactions, the reduction in the aromatic ring, and the photodegradation step. This sustainable approach offers promising alternatives in the case of photoresistive compounds.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101166
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1167: Catalyst Replacement Policy on
           Multienzymatic Systems: Theoretical Study in the One-Pot Sequential Batch
           Production of Lactofructose Syrup

    • Authors: Pablo Silva, Vanessa Arancibia, Daniela Cid, Oscar Romero, Andrés Illanes, Lorena Wilson
      First page: 1167
      Abstract: One-pot systems are an interesting proposal to carry out multi-enzymatic reactions, though this strategy implies establishing an optimal balance between the activity and operability of the involved enzymes. This is crucial for enzymes with marked differences in their operational stability, such as one-pot production of lactofructose syrup from cheese whey permeate, which involves two enzymes—β-galactosidase (β-gal) and glucose isomerase (GI). The aim of this work was to study the behavior of one-pot sequential batch production of lactofructose syrup considering both enzymes immobilized individually, in order to evaluate and design a strategy of replacement of the catalysts according to their stabilities. To this end, the modelling and simulation of the process was carried out, considering simultaneously the kinetics of both reactions and the kinetics of inactivation of both enzymes. For the latter, it was also considered the modulating effect that sugars present in the medium may have on the stability of β-gal, which is the less stable enzyme. At the simulated reaction conditions of 40 °C, pH 7, and 0.46 (IUGI/IUβ-gal), the results showed that considering the stability of b-gal under non-reactive conditions, meaning in absence of the effect of modulation, it is necessary to carry out four replacements of β-gal for each cycle of use of GI. On the other hand, when considering the modulation caused by the sugars on the b-gal stability, the productivity increases up to 23% in the case of the highest modulation factor studied (η = 0.8). This work shows the feasibility of conducting a one-pot operation with immobilized enzymes of quite different operational stability, and that a proper strategy of biocatalyst replacement increases the productivity of the process.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101167
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1168: Atomically Dispersed Catalytic Sites: A
           New Frontier for Cocatalyst/Photocatalyst Composites toward Sustainable
           Fuel and Chemical Production

    • Authors: Zhang, Bai, Liu, Zhang
      First page: 1168
      Abstract: Photocatalysis delivers a promising pathway toward the clean and sustainable energy supply of the future. However, the inefficiency of photon absorption, rapid recombination of photogenerated electron-hole pairs, and especially the limited active sites for catalytic reactions result in unsatisfactory performances of the photocatalytic materials. Single-atom photocatalysts (SAPCs), in which metal atoms are individually isolated and stably anchored on support materials, allow for maximum atom utilization and possess distinct photocatalytic properties due to the unique geometric and electronic features of the unsaturated catalytic sites. Very recently, constructing SAPCs has emerged as a new avenue for promoting the efficiency of sustainable production of fuels and chemicals via photocatalysis. In this review, we summarize the recent development of SAPCs as a new frontier for cocatalyst/photocatalyst composites in photocatalytic water splitting. This begins with an introduction on the typical structures of SAPCs, followed by a detailed discussion on the synthetic strategies that are applicable to SAPCs. Thereafter, the promising applications of SAPCs to boost photocatalytic water splitting are outlined. Finally, the challenges and prospects for the future development of SAPCs are summarized.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101168
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1169: The Effect of Mass Transfer Rate-Time in
           Bubbles on Removal of Azoxystrobin in Water by Micro-Sized Jet Array

    • Authors: Feng Chen, Dezheng Yang, Feng Yu, Yang Kun, Ying Song
      First page: 1169
      Abstract: In this work, the azoxystrobin removal in water by using a micro-size discharge array was investigated, and the removal efficiency can reach as high as 98.1% after 9 min plasma treatment as well as the energy utilization being only 0.73 g/(kW·h). Based on the relationship between the generation of gas bubbles and parameters of gas-liquid discharge, it was found that the variation of applied voltage, gas flow rate and initial solution temperature could cause particle number change, mass transfer rate change and the mass transfer time change, which significantly affected the practical applications at last. The experimental results indicated that when gas flow rate was 0.7 SLM (Standard Liter per Minute) and the initial solution temperature was 297 K with the applied voltage of 8 kV and discharge frequency of 6 kHz, the removal efficiency of azoxystrobin achieved maximum. Based on the analysis results of liquid mass spectrometry, the removal pathways of azoxystrobin were supposed by the decomposed by-products. Toxicity tests indicated that the decomposed products were safe and non-toxic. So, this study may reveal an azoxystrobin degradation mechanism and provide a safe, reliable and effective way for azoxystrobin degradation.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101169
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1170: Selective Synthesis of 2-(1,2, 3-Triazoyl)
           Quinazolinones through Copper-Catalyzed Multicomponent Reaction

    • Authors: Manoela Sacramento, Luís Pedro A. Piúma, José Edmilson R. Nascimento, Roberta Cargnelutti, Raquel G. Jacob, Eder João Lenardão, Diego Alves
      First page: 1170
      Abstract: We describe here our results from the copper-catalyzed three component reaction of 2-azidobenzaldehyde, anthranilamide and terminal alkynes, using Et3N as base, and DMSO as solvent. Depending on the temperature and amount of Et3N used in the reactions, 1,2,3-triazolyl-quinazolinones or 1,2,3-triazolyl-dihydroquinazolinone could be obtained. When the reactions were performed at 100 °C using 2 equiv. of Et3N, 1,2,3-triazolyl-dihydroquinazolinone was formed in 82% yield, whereas reactions carried out at 120 °C using 1 equiv. of Et3N provided 1,2,3-triazolyl-quinazolinones in moderate-to-good yields.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101170
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1171: Insights into the Nature of the Active
           Sites of Pt-WOx/Al2O3 Catalysts for Glycerol Hydrogenolysis into

    • Authors: Clara Jarauta-Córdoba, Mikel Oregui Bengoechea, Iker Agirrezabal-Telleria, Pedro-Luis Arias, Inaki Gandarias
      First page: 1171
      Abstract: The chemo-selective hydrogenolysis of secondary hydroxyls is an important reaction for the production of biomass-derived α,ω-diols. This is the case for 1,3-propanediol production from glycerol. Supported Pt-WOx materials are effective catalysts for this transformation, and their activity is often related to the tungsten surface density and Brönsted acidity, although there are discrepancies in this regard. In this work, a series of Pt-WOx/γ-Al2O3 catalysts were prepared by modifying the pH of the solutions used in the active metal impregnation step. The activity–structure relationships, together with the results from the addition of in situ titrants, i.e., 2,6-di-tert-butyl-pyridine or pyridine, helped in elucidating the nature of the bifunctional active sites for the selective production of 1,3-propanediol.
      Citation: Catalysts
      PubDate: 2021-09-27
      DOI: 10.3390/catal11101171
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1172: Halloysite Nanoclay with High Content of
           Sulfonic Acid-Based Ionic Liquid: A Novel Catalyst for the Synthesis of

    • Authors: Samahe Sadjadi, Fatemeh Koohestani, Neda Abedian-Dehaghani, Majid M. Heravi
      First page: 1172
      Abstract: One of the main drawbacks of supported ionic liquids is their low loading and consequently, low activity of the resultant catalysts. To furnish a solution to this issue, a novel heterocyclic ligand with multi imine sites was introduced on the surface of amino-functionalized halloysite support via successive reactions with 2,4,6-trichloro-1,3,5-triazine and 2-aminopyrimidine. Subsequently, the imine sites were transformed to sulfonic acid-based ionic liquids via reaction with 1,4-butanesultone. Using this strategy, high loading of ionic liquid was loaded on halloysite nanoclay. The supported ionic liquid was then characterized with XRD, SEM, TEM, EDS, FTIR, BET, TGA and elemental mapping analysis and utilized as a metal-free Brønsted acid catalyst for promoting one-pot reaction of aldehydes, dimedone and malononitrile to furnish tetrahydrobenzo[b]pyrans. The catalytic tests confirmed high performance of the catalyst. Moreover, the catalyst was stable upon recycling.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101172
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1173: Utilization of Clay Materials as Support
           for Aspergillus japonicus Lipase: An Eco-Friendly Approach

    • Authors: Daniela Remonatto, Bárbara Ribeiro Ferrari, Juliana Cristina Bassan, Cassamo Ussemane Mussagy, Valéria de Carvalho Santos-Ebinuma, Ariela Veloso de Paula
      First page: 1173
      Abstract: Lipase is an important group of biocatalysts, which combines versatility and specificity, and can catalyze several reactions when applied in a high amount of industrial processes. In this study, the lipase produced by Aspergillus japonicus under submerged cultivation, was immobilized by physical adsorption, using clay supports, namely, diatomite, vermiculite, montmorillonite KSF (MKSF) and kaolinite. Besides, the immobilized and free enzyme was characterized, regarding pH, temperature and kinetic parameters. The most promising clay support was MKSF that presented 69.47% immobilization yield and hydrolytic activity higher than the other conditions studied (270.7 U g−1). The derivative produced with MKSF showed high stability at pH and temperature, keeping 100% of its activity throughout 12 h of incubation in the pH ranges between 4.0 and 9.0 and at a temperature from 30 to 50 °C. In addition, the immobilized lipase on MKSF support showed an improvement in the catalytic performance. The study shows the potential of using clays as support to immobilized lipolytic enzymes by adsorption method, which is a simple and cost-effective process.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101173
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1174: Influence of NiO/La2O3 Catalyst
           Preparation Method on Its Reactivity in the Oxy-Steam Reforming of LNG

    • Authors: Magdalena Mosinska, Waldemar Maniukiewicz, Malgorzata I. Szynkowska-Jozwik, Pawel Mierczynski
      First page: 1174
      Abstract: The oxy-steam reforming of liquefied natural gas reaction (OSR-LNG) is promising process for syngas generation. In this paper, the catalytic properties of NiO/La2O3 systems prepared by wet impregnation and co-precipitation methods were extensively investigated in OSR-LNG reaction. The physicochemical properties of the studied catalytic materials were determined using various techniques including Temperature programmed reduction (TPR-H2), Temperature programmed desorption (TPD-NH3), Brunauer, Emmett and Teller (BET), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) with an energy dispersive X-Ray spectrometer (EDS). Reactivity measurements performed in the OSR-LNG process showed that the catalyst preparation method and the calcination temperature significantly affected the activity of NiO/La2O3 catalysts in the OSR-LNG reaction. The catalytic activity tests showed that NiO/La2O3 system prepared by a wet impregnation method and calcined at 700 °C showed the total conversion of the LNG component at 900 °C and the highest H2 yield at 700 and 900 °C. The phase composition studies confirmed the formation of the LaNiO3 structure in the case of the NiO/La2O3 catalyst prepared by wet impregnation, calcined at the temperature of 700 °C. Catalytic activity measurements showed that the reactivity of the catalysts was related to their phase composition and acidity. SEM images of spent catalysts showed that the smallest amount of carbon deposit was detected on the surface of the most active systems.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101174
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1175: Sol-Gel Synthesis of Organically Modified
           Silica Particles as Efficient Palladium Catalyst Supports to Perform
           Hydrogenation Process

    • Authors: Adele R. Latypova, Maxim D. Lebedev, Ilya A. Tarasyuk, Alexander I. Sidorov, Evgeniy V. Rumyantsev, Artur S. Vashurin, Yuriy S. Marfin
      First page: 1175
      Abstract: Modern approaches to the production of new materials require the improvement of synthesis techniques towards simplifying the processes of their preparation and reducing the number of stages. Thus, in this study, one-stage synthesis of organomodified silica materials is developed using a special surfactant—dodecyldimethylamin N-oxide (DDAO). The peculiarity of this approach is that there is no need for heat treatment of the material, since DDAO is removed by washing in alcohol. Amino-, mercapto-, methyl-, and phenyl-modified silicas were synthesized using this method. The SEM images showed the morphology of all the obtained materials is close, all particles are spherical, and the diameter of individual particles is about 500 nm. Palladium particles were precipitated on these supports, then the experiments were carried out to study the catalytic activity of these materials in a model reaction of nitroaniline reduction. The phenyl modified matrix-based materials showed very low activity. This is due to the fact that the support and the substrate contain aromatic fragments, thus, hydrophobic interactions arise between them, which complicates the diffusion of the products. The leader is a matrix with an amino fragment, which is associated with its electron-donor effect. The XPS method revealed the amount of fixed palladium, as well as the binding energy shifts, which are 0.68 eV for 5% Pd/SiO2–C6H5; 0.56 eV for 5% Pd/SiO2–C3H6–NH2; 0.26 eV for 5% Pd/SiO2–CH3; and 0.13 eV for 5% Pd/SiO2.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101175
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1176: Covalently Bonded Ir(IV) on Conducted Blue
           TiO2 for Efficient Electrocatalytic Oxygen Evolution Reaction in Acid

    • Authors: Chau T. K. Nguyen, Ngoc Quang Tran, Thi Anh Le, Hyoyoung Lee
      First page: 1176
      Abstract: The stability of anode electrode has been a primary obstacle for the oxygen evolution reaction (OER) in acid media. We design Ir-oxygen of hydroxyl-rich blue TiO2 through covalent bonds (Ir–O2–2Ti) and investigate the outcome of favored exposure of different amounts of covalent Ir–oxygen linked to the conductive blue TiO2 in the acidic OER. The Ir-oxygen-blue TiO2 nanoclusters show a strong synergy in terms of improved conductivity and tiny amount usage of Ir by using blue TiO2 supporter, and enhanced stability using covalent Ir-oxygen-linking (i.e., Ir oxide) in acid media, leading to high acidic OER performance with a current density of 10 mA cm−2 at an overpotential of 342 mV, which is much higher than that of IrO2 at 438 mV in 0.1 M HClO4 electrolyte. Notably, the Ir–O2–2Ti has a great mass activity of 1.38 A/mgIr at an overpotential 350 mV, which is almost 27 times higher than the mass activity of IrO2 at the same overpotential. Therefore, our work provides some insight into non-costly, highly enhanced, and stable electrocatalysts for the OER in acid media.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101176
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1177: Gamma Carbonic Anhydrases from
           Hydrothermal Vent Bacteria: Cases of Alternating Active Site Due to a Long
           Loop with Proton Shuttle Residue

    • Authors: Colleen Varaidzo Manyumwa, Özlem Tastan Bishop
      First page: 1177
      Abstract: Accelerated CO2 sequestration uses carbonic anhydrases (CAs) as catalysts; thus, there is much research on these enzymes. The γ-CA from Escherichia coli (EcoCA-γ) was the first γ-CA to display an active site that switches between “open” and “closed” states through Zn2+ coordination by the proton-shuttling His residue. Here, we explored this occurrence in γ-CAs from hydrothermal vent bacteria and also the γ-CA from Methanosarcina thermophila (Cam) using molecular dynamics. Ten sequences were analyzed through multiple sequence alignment and motif analysis, along with three others from a previous study. Conservation of residues and motifs was high, and phylogeny indicated a close relationship amongst the sequences. All structures, like EcoCA-γ, had a long loop harboring the proton-shuttling residue. Trimeric structures were modeled and simulated for 100 ns at 423 K, with all the structures displaying thermostability. A shift between “open” and “closed” active sites was observed in the 10 models simulated through monitoring the behavior of the His proton-shuttling residue. Cam, which has two Glu proton shuttling residues on long loops (Glu62 and Glu84), also showed an active site switch affected by the first Glu proton shuttle, Glu62. This switch was thus concluded to be common amongst γ-CAs and not an isolated occurrence.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101177
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1178: Pd/Alumina Catalysts for Beneficial
           Transformation of Harmful Freon R-22

    • Authors: Monika Radlik, Wojciech Juszczyk, Erhard Kemnitz, Zbigniew Karpiński
      First page: 1178
      Abstract: Chlorodifluoromethane (R-22), the most abundant freon in the atmosphere, was subjected to successful hydrodechlorination in the presence of palladium supported on γ-alumina, at a relatively low reaction temperature (180 °C). The combination of catalytic actions of alumina (performing freon dismutation) and Pd nanoparticles (catalyzing C–Cl bond splitting in the presence of hydrogen) results in the transformation of freon into valuable, chlorine-free products: methane and fluoroform, the mixture of which is used in plasma etching of silicon and silicon nitride. Very highly metal dispersed Pt/Al2O3 catalysts, with metal particles of ~1.3 nm in size, are not as effective as Pd/Al2O3, resulting in only partial dechlorination. A long-term dechlorination screening (3–4 days) showed good catalytic stability of Pd/alumina catalysts.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101178
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1179: Construction of a Novel Chimeric
           Dextransucrase Fused to the Carbohydrate-Binding Module CBM2a

    • Authors: Reinaldo Fraga Vidal, Roberto Carlos Arísticas Ribalta, Lisandra Teresa Martínez Valdés, Meinardo Lafargue Gámez, Amanda Montes Alvarez, Arianne Rubio Sánchez, Eric Dubreucq, Benoît Moreau
      First page: 1179
      Abstract: Lactic acid bacteria (LAB) have the potential to produce homoexopolysaccharides (HoPS). Their health benefits and physicochemical properties have been the subject of extensive research. The HoPS functional properties are determined by molecular weight, the type of glycosidic linkages, degrees of branching and chemical composition. The dextransucrases (DSases) produce a kind of HoPS (dextrans), which are among the first biopolymers produced at industrial scale with applications in medicine and biotechnology. The glycodiversification opens additional applications for DSases. Therefore, the design and characterization of new DSases is of prime importance. Previously, we described the isolation and characterization of a novel extracellular dextransucrase (DSR-F) encoding gene. In this study, from DSR-F, we design a novel chimeric dextransucrase DSR-F-∆SP-∆GBD-CBM2a, where DSR-F-∆SP-∆GBD (APY repeats and a CW repeat deleted) was fused to the carbohydrate-binding module (CBM2a) of the β-1-4 exoglucanase/xylanase Cex (Xyn10A) of Cellulomonas fimi ATCC 484. This dextransucrase variant is active and the specificity is not altered. The DSR-F-∆SP-∆GBD-CBM2a was purified by cellulose affinity chromatography for the first time. This research showed that hybrids and chimeric biocatalyst DSases with novel binding capacity to cellulose can be designed to purify and immobilize using renewable lignocellulosic materials as supports.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101179
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1180: A Facile Synthesis of Bi2O3/CoFe2O4
           Nanocomposite with Improved Synergistic Photocatalytic Potential for Dye

    • Authors: Abdul Basit Naveed, Fakhira Riaz, Azhar Mahmood, Ammara Shahid, Saman Aqeel
      First page: 1180
      Abstract: Semiconductor-based photocatalysis is a probable approach to overcoming many pollution problems and eradicating toxic organic materials from wastewater. This research endeavor aimed to explore the synergistic potential of different semiconductor nanocomposites for photocatalytic degradation of organic pollutants in contaminated water. A facile hydrothermal approach was employed to synthesize bismuth oxide and cobalt ferrite nanoparticles from their precursors—bismuth nitrate pentahydrate, ferric chloride hexahydrate and cobalt chloride hexahydrate—with various concentrations and conditions to optimize the product. Subsequently, nanocomposites of bismuth oxide and cobalt ferrite were prepared by solid-state mixing in varying concentrations followed by calcination. UV/visible diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy and elemental dispersive X-ray spectroscopic techniques have corroborated the successful synthesis of nanocomposites. The energy gaps of bismuth oxide and cobalt ferrite nanocomposites were computed in the range of 1.58–1.62 eV by Tauc plots. These nanocomposite materials were ascertained for photocatalytic potential to degrade methyl orange organic dye in water. A nanocomposite with equiquantic proportions has shown the best photocatalytic degradation activity, which may be attributed to the type-II band configuration and a synergistic effect, because Bi2O3 acts as an electron sink. This synergism has reduced the cogent band gap, hindered electron hole recombination and increased electron hole availabilities for photodegradation reactions, thus ensuing an efficient photodegradation co-work of Bi2O3/CoFe2O4 nanocomposites.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101180
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1181: Deactivation of Zeolite Catalysts in the
           Prins Reaction between Propene and Formaldehyde in the Liquid Phase

    • Authors: Stanislav P. Bedenko, Konstantin I. Dement’ev, Valentin F. Tret’yakov
      First page: 1181
      Abstract: The Prins reaction between propene and formaldehyde was studied over H-BEA, H-FAU, H-MFI and H-MOR zeolites at 150 °C in liquid phase. It was found that the H-BEA sample is the most active and selective toward buta-1,3-diene; the H-MFI is a potential catalyst for 3-buten-1-ol synthesis, while H-FAU can be used for 4-methyl-1,3-dioxane production. It had been confirmed that zeolite textural and acidic properties influence catalyst behaviour: the acidic properties influence sample activity, while product distribution is controlled by pore volume and effective pore diameter. The sample’s deactivation process had been studied and the kinetic model of deactivation was proposed. It was shown that the deactivation rate for the H-MFI catalyst is four times greater than for the H-BEA catalyst, probably because its strong/weak acid sites ratio is much more high than for the H-BEA.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101181
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1182: Crystalline ZnO Photocatalysts Prepared at
           Ambient Temperature: Influence of Morphology on p-Nitrophenol Degradation
           in Water

    • Authors: Julien G. Mahy, Louise Lejeune, Tommy Haynes, Nathalie Body, Simon De Kreijger, Benjamin Elias, Raphael Henrique Marques Marcilli, Charles-André Fustin, Sophie Hermans
      First page: 1182
      Abstract: Since the Industrial Revolution, technological advances have generated enormous emissions of various pollutants affecting all ecosystems. The detection and degradation of pollutants has therefore become a critical issue. More than 59 different remediation technologies have already been developed, such as biological remediation, and physicochemical and electrochemical methods. Among these techniques, advanced oxidation processes (AOPs) have been popularized in the treatment of wastewater. The use of ZnO as a photocatalyst for water remediation has been developing fast in recent years. In this work, the goals are to produce ZnO photocatalysts with different morphologies, by using a green sol-gel process, and to study both the influence of the synthesis parameters on the resulting morphology, and the influence of these different morphologies on the photocatalytic activity, for the degradation of an organic pollutant in water. Multiple morphologies were produced (nanotubes, nanorods, nanospheres), with the same crystalline phase (wurtzite). The most important parameter controlling the shape and size was found to be pH. The photoactivity study on a model of pollutant degradation shows that the resulting activity is mainly governed by the specific surface area of the material. A comparison with a commercial TiO2 photocatalyst (Evonik P25) showed that the best ZnO produced with this green process can reach similar photoactivity without a calcination step.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101182
      Issue No: Vol. 11, No. 10 (2021)
  • Catalysts, Vol. 11, Pages 1183: Getting the Most Out of Enzyme Cascades:
           Strategies to Optimize In Vitro Multi-Enzymatic Reactions

    • Authors: Regine Siedentop, Christiane Claaßen, Dörte Rother, Stephan Lütz, Katrin Rosenthal
      First page: 1183
      Abstract: In vitro enzyme cascades possess great benefits, such as their synthetic capabilities for complex molecules, no need for intermediate isolation, and the shift of unfavorable equilibria towards the products. Their performance, however, can be impaired by, for example, destabilizing or inhibitory interactions between the cascade components or incongruous reaction conditions. The optimization of such systems is therefore often inevitable but not an easy task. Many parameters such as the design of the synthesis route, the choice of enzymes, reaction conditions, or process design can alter the performance of an in vitro enzymatic cascade. Many strategies to tackle this complex task exist, ranging from experimental to in silico approaches and combinations of both. This review collates examples of various optimization strategies and their success. The feasibility of optimization goals, the influence of certain parameters and the usage of algorithm-based optimizations are discussed.
      Citation: Catalysts
      PubDate: 2021-09-28
      DOI: 10.3390/catal11101183
      Issue No: Vol. 11, No. 10 (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

    • 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 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

    • 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

    • 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

    • 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

    • 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

    • 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

    • 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)
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