Subjects -> CHEMISTRY (Total: 986 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (713 journals)
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    - INORGANIC CHEMISTRY (45 journals)
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    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (713 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 29)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 9)
ACS Catalysis     Hybrid Journal   (Followers: 51)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 21)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Materials Letters     Open Access   (Followers: 2)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 43)
ACS Nano     Hybrid Journal   (Followers: 189)
ACS Photonics     Hybrid Journal   (Followers: 15)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 28)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 8)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 70)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 3)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 1)
Advanced Science Focus     Free   (Followers: 5)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 104)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 34)
Advances in Chemistry     Full-text available via subscription   (Followers: 4)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 16)
Advances in Environmental Chemistry     Open Access   (Followers: 9)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 31)
Advances in Nanoparticles     Open Access   (Followers: 17)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 50)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access  
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 43)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 19)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 7)
Analyst     Hybrid Journal   (Followers: 36)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 155)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 227)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 6)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Surface Science     Hybrid Journal   (Followers: 30)
Arabian Journal of Chemistry     Open Access   (Followers: 4)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 7)
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: 203)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 22)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 3)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 93)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 66)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 15)
Biosensors     Open Access   (Followers: 3)
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: 24)
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 Journal of Chemistry     Hybrid Journal   (Followers: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 65)
Carbon Capture Science & Technology     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 11)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 8)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 9)
Chem Catalysis     Hybrid Journal   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 21)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 81)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 25)
Chemical Physics Impact     Full-text available via subscription   (Followers: 5)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 176)
Chemical Science     Open Access   (Followers: 39)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 74)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 7)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 54)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 5)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Full-text available via subscription   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 125)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 17)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 6)
Chemistry Education Review     Open Access   (Followers: 1)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 5)
Chemistry of Materials     Hybrid Journal   (Followers: 160)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Hybrid Journal   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal   (Followers: 1)
Chemistry–Methods     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 13)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPhysMater     Full-text available via subscription   (Followers: 8)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access  
ChemSystemsChem     Hybrid Journal   (Followers: 1)
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: 9)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 7)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 6)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 2)
Combustion Science and Technology     Hybrid Journal   (Followers: 26)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comptes Rendus : Chimie     Open Access  
Comptes Rendus : Physique     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 11)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 13)
Computational Chemistry     Open Access   (Followers: 4)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 11)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 6)
Corrosion Communications     Open Access   (Followers: 5)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 17)
Croatica Chemica Acta     Open Access  
CrystEngComm     Hybrid Journal   (Followers: 10)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Catalysts
Number of Followers: 11  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2073-4344
Published by MDPI Homepage  [78 journals]
  • Catalysts, Vol. 12, Pages 108: Synthesis, Crystal Structure, and
           Electrochemical Properties of an Isopolyoxovanadate Compound Modified
           Transition-Metal Complex Based on [V4O12]4−

    • Authors: Yongxiu Wang, Bingjie Zhang, Huili Guo, Yanhua Fan, Haiyan Li, Jingyu Pang, Dongbin Dang, Yan Bai
      First page: 108
      Abstract: A new isopolyoxovanadate compound [Zn(phen)3]2·(V4O12)·phen·20H2O (phen = 1,10-phenathroline) (1) has been synthesized in aqueous solution and characterized using IR and UV/Vis spectroscopy, elemental analysis, thermal gravimetric analysis, powder, single-crystal X-ray diffractions, and field emission scanning electron microscopy. The molecular structure of 1 exists as two kinds of [V4O12]4− polyoxoanions: distorted chair-like and coplanar conformations, two independent [Zn(phen)3]2+ units and free phen. In the solid state, compound 1 forms a stable three-dimensional supramolecular structure through electrostatic interactions, π–π stacking interactions and multiform hydrogen bonds. The electrocatalytic activity and determination of DA of compound 1 have been studied by cyclic voltammetry and differential pulse voltammetry, respectively.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020108
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 109: Catalytic Upgrading of Clean Biogas to
           Synthesis Gas

    • Authors: Nicola Schiaroli, Martina Battisti, Patricia Benito, Giuseppe Fornasari, Amalio Giovanni Di Gisi, Carlo Lucarelli, Angelo Vaccari
      First page: 109
      Abstract: Clean biogas, produced by anaerobic digestion of biomasses or organic wastes, is one of the most promising substitutes for natural gas. After its purification, it can be valorized through different reforming processes that convert CH4 and CO2 into synthesis gas (a mixture of CO and H2). However, these processes have many issues related to the harsh conditions of reaction used, the high carbon formation rate and the remarkable endothermicity of the reforming reactions. In this context, the use of the appropriate catalyst is of paramount importance to avoid deactivation, to deal with heat issues and mild reaction conditions and to attain an exploitable syngas composition. The development of a catalyst with high activity and stability can be achieved using different active phases, catalytic supports, promoters, preparation methods and catalyst configurations. In this paper, a review of the recent findings in biogas reforming is presented. The different elements that compose the catalytic system are systematically reviewed with particular attention on the new findings that allow to obtain catalysts with high activity, stability, and resistance towards carbon formation.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020109
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 110: Insight into the Photocatalytic Activity of
           Cobalt-Based Metal–Organic Frameworks and Their Composites

    • Authors: Aleksander Ejsmont, Agata Jankowska, Joanna Goscianska
      First page: 110
      Abstract: Nowadays, materials with great potential for environmental protection are being sought. Metal–organic frameworks, in particular those with cobalt species as active sites, have drawn considerable interest due to their excellent properties. This review focuses on describing cobalt-based MOFs in the context of light-triggered processes, including dye degradation, water oxidation and splitting, carbon dioxide reduction, in addition to the oxidation of organic compounds. With the use of Co-based MOFs (e.g., ZIF-67, Co-MOF-74) as photocatalysts in these reactions, even over 90% degradation efficiencies of various dyes (e.g., methylene blue) can be achieved. Co-based MOFs also show high TOF/TON values in water splitting processes and CO2-to-CO conversion. Additionally, the majority of alcohols may be converted to aldehydes with efficiencies exceeding 90% and high selectivity. Since Co-based MOFs are effective photocatalysts, they can be applied in the elimination of toxic contaminants that endanger the environment.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020110
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 111: Co and Ni Incorporated γ-Al2O3 (110)
           Surface: A Density Functional Theory Study

    • Authors: Huaxi Li, Liu Shi, Chengkai Jin, Runping Ye, Rongbin Zhang
      First page: 111
      Abstract: Investigation into the state and mechanisms of the active metal substitution into the γ-Al2O3 support is the basis for design of many catalysts. Periodic density functional theory (DFT) +U calculations were used to investigate the surface properties of transition metals Co3+ and Ni3+ cations substitute for the Al3+ cations of γ-Al2O3 (110) surface. It was found that the substitution energy of one Al3+ substituted by Co3+ and Ni3+ are −61 and −57 kJ/mol, respectively. The Co and Ni preferentially substitute the tetrahedral Al sites instead of the octahedral Al sites. Using thermodynamics, the Al atoms in the top layer of γ-Al2O3 (110) can be 100% substituted by Co and Ni. Ni is easier to substitute the Al atom than Co. There is no obvious structural distortion that occurs after Co and Ni substituted all the top layer Al atoms. While the band gaps of the substituted surface become narrower, resulting in the increase of surface Lewis acidity. In addition, the oxygen vacancy formation energies of the Co and Ni substituted surface are 268 and 53 kJ/mol, respectively. The results provide interface structure and physical chemistry properties of metal-doped catalysts.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020111
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 112: Monolithic Stirrer Reactors for the
           Sustainable Production of Dihydroxybenzenes over 3D Printed
           Fe/γ-Al2O3 Monoliths: Kinetic Modeling and CFD Simulation

    • Authors: Pablo López, Asunción Quintanilla, Alma D. Salazar-Aguilar, Sofía M. Vega-Díaz, Irene Díaz-Herrezuelo, Manuel Belmonte, Jose A. Casas
      First page: 112
      Abstract: The aim of this work is to evaluate the performance of the stirring 3D Fe/Al2O3 monolithic reactor in batch operation applied to the liquid-phase hydroxylation of phenol by hydrogen peroxide (H2O2). An experimental and numerical investigation was carried out at the following operating conditions: CPHENOL,0 = 0.33 M, CH2O2,0 = 0.33 M, T = 75–95 °C, P = 1 atm, ω = 200–500 rpm and WCAT ~ 1.1 g. The kinetic model described the consumption of the H2O2 by a zero-order power-law equation, while the phenol hydroxylation and catechol and hydroquinone production by Eley–Rideal model; the rate determining step was the reaction between the adsorbed H2O2, phenol in solution with two active sites involved. The 3D CFD model, coupling the conservation of mass, momentum and species together with the reaction kinetic equations, was experimentally validated. It demonstrated a laminar flow characterized by the presence of an annular zone located inside and surrounding the monoliths (u = 40–80 mm s−1) and a central vortex with very low velocities (u = 3.5–8 mm s−1). The simulation study showed the increasing phenol selectivity to dihydroxybenzenes by the reaction temperature, while the initial H2O2 concentration mainly affects the phenol conversion.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020112
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 113: Kinetic Modeling and Quantum Yields:
           Hydrogen Production via Pd-TiO2 Photocatalytic Water Splitting under
           Near-UV and Visible Light

    • Authors: Bianca Rusinque, Salvador Escobedo, Hugo de Lasa
      First page: 113
      Abstract: A palladium (Pd) doped mesoporous titanium dioxide (TiO2) photocatalyst was used to produce hydrogen (H2) via water splitting under both near-UV and visible light. Experiments were carried out in the Photo-CREC Water-II Reactor (PCW-II) using a 0.25 wt% Pd-TiO2 photocatalyst, initial pH = 4 and 2.0 v/v% ethanol, as an organic scavenger. After 6 h of near-UV irradiation, this photocatalyst yielded 113 cm3 STP of hydrogen (H2). Furthermore, after 1 h of near-UV photoreduction followed by 5 h of visible light, the 0.25 wt% Pd-TiO2 photocatalyst yielded 5.25 cm3 STP of H2. The same photocatalyst, photoreduced for 24 h under near-UV and subsequently exposed to 5 h of visible light, yielded 29 cm3 STP of H2. It was observed that the promoted redox reactions led to the production of hydrogen and by-products such as methane, ethane, ethylene, acetaldehyde, carbon monoxide, carbon dioxide and hydrogen peroxide. These redox reactions could be modeled using an “in series-parallel” reaction network and Langmuir Hinshelwood based kinetics. The proposed rate equations were validated using statistical analysis for the experimental data and calculated kinetic parameters. Furthermore, Quantum yields (QYH•%) based on the H• produced were also established at promising levels: (a) 34.8% under near-UV light and 1.00 g L−1 photocatalyst concentration; (b) 8.8% under visible light and 0.15 g L−1. photocatalyst concentration following 24 h of near-UV.
      Citation: Catalysts
      PubDate: 2022-01-18
      DOI: 10.3390/catal12020113
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 114: Photocatalytic Degradation of Organic
           Wastes in Water

    • Authors: María Victoria López-Ramón, José Rivera-Utrilla, Manuel Sánchez-Polo
      First page: 114
      Abstract: Over recent years, public concerns have arisen about environmental pollution by so-called emerging organic pollutants (EOPs) in water sources and factory effluents, because of their potentially adverse effects on human health and aquatic ecosystems [...]
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020114
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 115: Efficient Visible-Light-Responsive
           Ag3PO4/g-C3N4/Hydroxyapatite Photocatalyst (from Oyster Shells) for the
           Degradation of Methylene Blue: Preparation, Properties and Mechanism

    • Authors: Cui Song, Changyu Shang, Shuqian Li, Wenhao Wang, Mingying Qi, Jingdi Chen, Haijun Liu
      First page: 115
      Abstract: A novel ternary Ag3PO4/g-C3N4/hydroxyapatite photocatalyst was prepared, and its morphology, composition and structure were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and electron spin resonance, etc. The results show that g-C3N4 is evenly dispersed in the interior of hydroxyapatite, forming a homogeneous composite, and significantly improves the band gap structure of the material as a whole. Ag3PO4/g-C3N4/hydroxyapatite has good electron transfer ability and an appropriate energy band structure, which shows that the material has a good degradation effect and stability. Finally, based on the characterization and experimental results, a possible Z-scheme mechanism was proposed, and the active species involved in the reaction are mainly O2− and h+.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020115
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 116: TiO2-Acetylacetone as an Efficient Source
           of Superoxide Radicals under Reduced Power Visible Light: Photocatalytic
           Degradation of Chlorophenol and Tetracycline

    • Authors: Lucas A. Almeida, Anja Dosen, Juliana Viol, Bojan A. Marinkovic
      First page: 116
      Abstract: Visible light-sensitive TiO2-based nanomaterials are widely investigated for photocatalytic applications under high power (≥300 W) UV and visible light. The formation of charge transfer complexes (CTCs) between bidentate ligands and nanocrystalline TiO2 promotes visible light absorption and constitutes a promising alternative for environmental remediation under reduced visible light power. However, the efficiency of photodegradation, the volatilization profile of bidentates, and the role of reactive oxidizing species (ROS) are not fully understood. In this study, thermogravimetric analyses coupled with mass spectroscopy (TGA-MS) were performed on TiO2-Acetylacetone (ACAC) CTC. TiO2-ACAC CTC calcined at 300 °C (TiO2-A300) was applied for the photocatalytic degradation of chlorophenol (4-CP) and tetracycline (TC) under low power visible light (26 W). Furthermore, the ROS scavengers isopropanol and benzoquinone were added for studying the photocatalytic role of •OH and •O2− radicals. The TGA-MS showed the release of ACAC fragments, such as ethyl ions and acetone, in the range between 150 °C and 265 °C, while between 300 °C and 450 °C only CO2 and H2O were released during oxidation of ACAC. The photocatalytic abatement of tetracycline (68.6%), performed by TiO2-A300, was ~two times higher than that observed for chlorophenol (31.3%) after 6 h, indicating a distinct participation of ROS in the degradation of these pollutants. The addition of the ROS scavenger revealed •O2− radicals as primarily responsible for the high efficiency of TiO2-ACAC CTC under reduced visible light. On the other hand, the •OH radicals are not efficiently generated in the CTC. Therefore, the development of heterostructures based on TiO2-ACAC CTC can increase the generation of ROS through coupling with semiconductors capable of generating •OH under visible light.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020116
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 117: Graded Preparation and Industrial
           Applications of Large-Ball Polyolefin Catalyst Carriers

    • Authors: Xinfeng Lv, Yuhao Du, Shanjun Du, Lan Xiang
      First page: 117
      Abstract: In the process of preparing polyolefin catalyst carrier, the particle size is often unqualified because of the adhesion of smaller particles to each other and the crushing effect of mechanical vibration. To improve the output of target products, reduce loss, and improve yield, a high-precision and high-efficiency carrier particle classification process was developed according to the embedded principle. The hydraulic hydrocyclone equipment designed in this work could eliminate short-circuit flow and achieve good integration of the internal flow field, thereby enhancing the separation accuracy and high separation efficiency. The process was successfully applied to the industry with smooth operation. The large-ball polyolefin catalyst carrier prepared by grading showed a small distribution coefficient, high yield, and excellent polymerization performance, and the average particle size of the graded large ball catalyst support was 65–75 μm with the SPAN < 0.7, which could meet the needs of DQC700 series catalyst products.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020117
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 118: Magnesium as a Methanation Suppressor for
           Iron- and Cobalt-Based Oxide Catalysts during the Preferential Oxidation
           of Carbon Monoxide

    • Authors: Mohamed I. Fadlalla, Thulani M. Nyathi, Michael Claeys
      First page: 118
      Abstract: The preferential oxidation of CO (CO-PrOx) to CO2 is an effective catalytic process for purifying the H2 utilized in proton-exchange membrane fuel cells for power generation. Our current work reports on the synthesis, characterization and CO-PrOx performance evaluation of unsubstituted and magnesium-substituted iron- and cobalt-based oxide catalysts (i.e., Fe3O4, Co3O4, MgFe2O4 and MgCo2O4). More specifically, the ability of Mg to stabilize the MgFe2O4 and MgCo2O4 structures, as well as suppress CH4 formation during CO-PrOx was of great importance in this study. The cobalt-based oxide catalysts achieved higher CO2 yields than the iron-based oxide catalysts below 225 °C. The highest CO2 yield (100%) was achieved over Co3O4 between 150 and 175 °C, however, undesired CH4 formation was only observed over this catalyst due to the formation of bulk fcc and hcp Co0 between 200 and 250 °C. The presence of Mg in MgCo2O4 suppressed CH4 formation, with the catalyst only reducing to a CoO-type phase (possibly containing Mg). The iron-based oxide catalysts did not undergo bulk reduction and did not produce CH4 under reaction conditions. In conclusion, our study has demonstrated the beneficial effect of Mg in stabilizing the active iron- and cobalt-based oxide structures, and in suppressing CH4 formation during CO-PrOx.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020118
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 119: Cr(III) Complexes Bearing a
           β-Ketoimine Ligand for Olefin Polymerization: Are There Differences
           between Coordinative and Covalent Bonding'

    • Authors: Alessia Amodio, Giorgia Zanchin, Fabio De Stefano, Alessandro Piovano, Benedetta Palucci, Virginia Guiotto, Rocco Di Girolamo, Giuseppe Leone, Elena Groppo
      First page: 119
      Abstract: β-ketoimines are extensively applied for the synthesis of organometallic complexes intended as (pre)catalysts for a variety of chemical transformations. We were interested in the synthesis of two Cr complexes bearing a simple bidentate β-ketoimine (L), with different ligand binding modes, as well as their application as a precatalyst in the polymerization of olefins. Complex 1 (L2CrCl3) was obtained by direct reaction of L with CrCl3(THF)3, while, for the synthesis of complex 2 (LCrCl2), the ligand was first deprotonated with nBuLi, giving the β-ketoiminato ligand L─Li+, and then reacted with CrCl3(THF)3. Characterization of the complexes proved that the Cr(III) ion is coordinatively bonded to L in 1, while it is covalently bonded to L in 2. The complexes were then used as precatalysts for the polymerization of ethylene and various cyclic olefins. Upon activation with methylaluminoxane, both the complexes exhibited poor activity in the polymerization of ethylene, whilst they exhibit good productivity in the polymerization of cyclic olefins, affording semicrystalline oligomers, without a significant difference between 1 and 2. To gain more insight, we investigated the reaction of the complexes with the Al-cocatalyst by IR and UV-Vis spectroscopies. The results proved that, in case of 1, the Al-activator deprotonates the ligand, bringing to the formation of an active species analogous to that of 2.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020119
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 120: Identification of Active Species in
           Photodegradation of Aqueous Imidacloprid over g-C3N4/TiO2 Nanocomposites

    • Authors: Thawanrat Kobkeatthawin, Jirawat Trakulmututa, Taweechai Amornsakchai, Puangrat Kajitvichyanukul, Siwaporn Meejoo Smith
      First page: 120
      Abstract: In this work, g-C3N4/TiO2 composites were fabricated through a hydrothermal method for the efficient photocatalytic degradation of imidacloprid (IMI) pesticide. The composites were fabricated at varying loading of sonochemically exfoliated g-C3N4 (denoted as CNS). Complementary characterization results indicate that the heterojunction between the CNS and TiO2 formed. Among the composites, the 0.5CNS/TiO2 material gave the highest photocatalytic activity (93% IMI removal efficiency) under UV-Vis light irradiation, which was 2.2 times over the pristine g-C3N4. The high photocatalytic activity of the g-C3N4/TiO2 composites could be ascribed to the band gap energy reduction and suppression of photo-induced charge carrier recombination on both TiO2 and CNS surfaces. In addition, it was found that the active species involved in the photodegradation process are OH• and holes, and a possible mechanism was proposed. The g-C3N4/TiO2 photocatalysts exhibited stable photocatalytic performance after regeneration, which shows that g-C3N4/TiO2 is a promising material for the photodegradation of imidacloprid pesticide in wastewater.
      Citation: Catalysts
      PubDate: 2022-01-19
      DOI: 10.3390/catal12020120
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 121: Organocatalysis for the Asymmetric Michael
           Addition of Aldehydes and α,β-Unsaturated Nitroalkenes

    • Authors: Jae Ho Shim, Seok Hyun Cheun, Hyeon Soo Kim, Deok-Chan Ha
      First page: 121
      Abstract: Michael addition is an important reaction because it can be used to synthesize a wide range of natural products or complex compounds that exhibit biological activities. In this study, a mirror image of an aldehyde and α,β-unsaturated nitroalkene were reacted in the presence of (R,R)-1,2-diphenylethylenediamine (DPEN). Herein, thiourea was introduced as an organic catalyst, and a selective Michael addition reaction was carried out. The primary amine moiety of DPEN reacts with aldehydes to form enamines, which is activated by the hydrogen bond formation between the nitro groups of α,β-unsaturated nitroalkenes and thiourea. Our aim was to obtain an asymmetric Michael product by adding 1,4-enamine to an alkene to form a new carbon–carbon bond. As a result, the primary amine of the chiral diamine was converted to an enamine. The reaction proceeded with a relatively high degree of enantioselectivity, which was achieved using double activation via hydrogen bonding of the nitro group and thiourea. Michael products with a high degree of enantioselectivity (97–99% synee) and diastereoselectivity (syn/anti = 9/1) were obtained in yields ranging from 94–99% depending on the aldehydes.
      Citation: Catalysts
      PubDate: 2022-01-20
      DOI: 10.3390/catal12020121
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 122: Study of Influence Factors in the
           Evaluation of the Performance of a Photocatalytic Fibre Reactor
           (TiO2/SiO2) for the Removal of Organic Pollutants from Water

    • Authors: Juan C. García-Prieto, Luis A. González-Burciaga, José B. Proal-Nájera, Manuel García-Roig
      First page: 122
      Abstract: The performance of a photocatalytic fibre reactor (UBE Chemical Europe), made of cartridges of fine particles of TiO2 dispersed within silicon fibres and irradiated by ultraviolet light, for the removal of organic pollutants from synthetic waters was evaluated. In the sensitivity analysis carried out, the factors catalytic surface area, fibre state, temperature and initial substrate concentration were studied using 4-chlorophenol as a test compound. The percentage of titanium in the fibre remained practically invariable after a series of experiments and cleaning procedures. Furthermore, the kinetics of removal of pyrene, phenol, 4-chlorophenol and bisphenol A (BPA) from water were evaluated by means of HPLC, UV-absorption and fluorescence techniques. Kinetic operational parameters were determined from a mathematical model proposed by Langmuir–Hinshelwood. Results show that catalytic surface, initial substrate concentration and temperature directly affect the degradation rate of organic compounds, whereas fibre state does not have a significant effect on that. It is proposed that removal of organic compounds from water mainly depends on the adsorption of the specific pollutant on the photocatalytic fibre and on the physical diffusion of the substrate towards the photocatalytic TiO2 active sites on the fibre, with the heterogeneous phase reaction prevailing over the homogeneous phase reaction.
      Citation: Catalysts
      PubDate: 2022-01-20
      DOI: 10.3390/catal12020122
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 123: Recent Advances in Seawater Electrolysis

    • Authors: Jiang, Suo, Zhang, Liao, Wang, Zhao, Lai
      First page: 123
      Abstract: Hydrogen energy, as a clean and renewable energy, has attracted much attention in recent years. Water electrolysis via the hydrogen evolution reaction at the cathode coupled with the oxygen evolution reaction at the anode is a promising method to produce hydrogen. Given the shortage of freshwater resources on the planet, the direct use of seawater as an electrolyte for hydrogen production has become a hot research topic. Direct use of seawater as the electrolyte for water electrolysis can reduce the cost of hydrogen production due to the great abundance and wide availability. In recent years, various high-efficiency electrocatalysts have made great progress in seawater splitting and have shown great potential. This review introduces the mechanisms and challenges of seawater splitting and summarizes the recent progress of various electrocatalysts used for hydrogen and oxygen evolution reaction in seawater electrolysis in recent years. Finally, the challenges and future opportunities of seawater electrolysis for hydrogen and oxygen production are presented.
      Citation: Catalysts
      PubDate: 2022-01-20
      DOI: 10.3390/catal12020123
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 124: En Route to CO2-Based (a)Cyclic Carbonates
           and Polycarbonates from Alcohols Substrates by Direct and Indirect
           Approaches

    • Authors: Brege, Grignard, Méreau, Detrembleur, Jerome, Tassaing
      First page: 124
      Abstract: This review is dedicated to the state-of-the art routes used for the synthesis of CO2-based (a)cyclic carbonates and polycarbonates from alcohol substrates, with an emphasis on their respective main advantages and limitations. The first section reviews the synthesis of organic carbonates such as dialkyl carbonates or cyclic carbonates from the carbonation of alcohols. Many different synthetic strategies have been reported (dehydrative condensation, the alkylation route, the “leaving group” strategy, the carbodiimide route, the protected alcohols route, etc.) with various substrates (mono-alcohols, diols, allyl alcohols, halohydrins, propargylic alcohols, etc.). The second section reviews the formation of polycarbonates via the direct copolymerization of CO2 with diols, as well as the ring-opening polymerization route. Finally, polycondensation processes involving CO2-based dimethyl and diphenyl carbonates with aliphatic and aromatic diols are described.
      Citation: Catalysts
      PubDate: 2022-01-20
      DOI: 10.3390/catal12020124
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 125: Controlled Growth of Unusual Nanocarbon
           Allotropes by Molten Electrolysis of CO2

    • Authors: Xinye Liu, Gad Licht, Xirui Wang, Stuart Licht
      First page: 125
      Abstract: This study describes a world of new carbon “fullerene” allotropes that may be synthesized by molten carbonate electrolysis using greenhouse CO2 as the reactant. Beyond the world of conventional diamond, graphite and buckyballs, a vast array of unique nanocarbon structures exist. Until recently, CO2 was thought to be unreactive. Here, we show that CO2 can be transformed into distinct nano-bamboo, nano-pearl, nano-dragon, solid and hollow nano-onion, nano-tree, nano-rod, nano-belt and nano-flower morphologies of carbon. The capability to produce these allotropes at high purity by a straightforward electrolysis, analogous to aluminum production splitting of aluminum oxide, but instead nanocarbon production by splitting CO2, opens an array of inexpensive unique materials with exciting new high strength, electrical and thermal conductivity, flexibility, charge storage, lubricant and robustness properties. Commercial production technology of nanocarbons had been chemical vapor deposition, which is ten-fold more expensive, generally requires metallo-organics reactants and has a highly carbon-positive rather than carbon-negative footprint. Different nanocarbon structures were prepared electrochemically by variation of anode and cathode composition and architecture, electrolyte composition, pre-electrolysis processing and current ramping and current density. Individual allotrope structures and initial growth mechanisms are explored by SEM, TEM, HAADF EDX, XRD and Raman spectroscopy.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020125
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 126: Continuous-Flow Sunlight-Powered CO2
           Methanation Catalyzed by γ-Al2O3-Supported Plasmonic Ru Nanorods

    • Authors: Jelle Rohlfs, Koen W. Bossers, Nicole Meulendijks, Fidel Valega Mackenzie, Man Xu, Marcel A. Verheijen, Pascal Buskens, Francesc Sastre
      First page: 126
      Abstract: Plasmonic CO2 methanation using γ-Al2O3-supported Ru nanorods was carried out under continuous-flow conditions without conventional heating, using mildly concentrated sunlight as the sole and sustainable energy source (AM 1.5, irradiance 5.5–14.4 kW·m−2 = 5.5–14.4 suns). Under 12.5 suns, a CO2 conversion exceeding 97% was achieved with complete selectivity towards CH4 and a stable production rate (261.9 mmol·gRu−1·h−1) for at least 12 h. The CH4 production rate showed an exponential increase with increasing light intensity, suggesting that the process was mainly promoted by photothermal heating. This was confirmed by the apparent activation energy of 64.3 kJ·mol−1, which is very similar to the activation energy obtained for reference experiments in dark (67.3 kJ·mol−1). The flow rate influence was studied under 14.4 suns, achieving a CH4 production plateau of 264 µmol min−1 (792 mmol·gRu−1·h−1) with a constant catalyst bed temperature of approximately 204 °C.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020126
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 127: Palladium-Catalyzed Domino
           Cycloisomerization/Double Condensation of Acetylenic Acids with
           Dinucleophiles

    • Authors: Nerea Conde, María Teresa Herrero, Garazi Urgoitia, Raul SanMartin
      First page: 127
      Abstract: Metal-catalyzed cascade processes based on hydrofunctionalization of alkynes are receiving much more attention because of their potential to provide advantageous approaches to otherwise synthetically challenging compounds. An alternative catalyst system has been found for the domino cycloisomerization/cyclocondensation reaction involving acetylenic acids and heterodinucleophiles. A CNN pincer palladium(II) complex, acting as a homogeneous catalyst, provides the corresponding polyheterocycles with a higher substrate/catalyst ratio. Other palladium sources were also tested and discarded, and a number of mechanistic studies including poisoning assays, kinetic plots, TEM images, XRD spectra and UPLC-MS analysis of reaction intermediates were conducted in order to shed light on the role of this pincer catalyst and the catalytic cycle involved in the cascade reaction. As a result, a more nuanced mechanism is tentatively proposed.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020127
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 128: Fabrication of Polyaniline Ni-Complex
           Catalytic Electrode by Plasma Deposition for Electrochemical Detection of
           Phosphate through Glucose Redox Reaction as Mediator

    • Authors: Hyun-Woong Lee, Jae-Ni Yoo, In-Keun Yu, Seong-Ho Choi
      First page: 128
      Abstract: We report here the preparation and characterization of polyaniline Ni-complex catalytic electrode by one-pot plasma deposition for the electrochemical detection of phosphate via the redox reaction of glucose. We first prepared a precursory solution by combining NiCl2 and 3-aminobenzoic acid in a mixed solution of methanol (MeOH) and water, and adding aniline as a conductive polymeric precursor for increasing the electron transfer potential. We then synthesized the catalytic electrode in a one-step cold plasma process by preparing the precursors on ITO glass. We characterized the obtained Ni-coordinate catalytic electrode via X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM), and electrochemical methods. Electrochemical characterization produced stable redox properties of Ni3+/Ni2+ couples in a 0.1 M NaOH solution. Cyclic voltametric experiments have drastically increased electrocatalytic oxidation and reduction of glucose by increasing the concentration of phosphate (PO43−) ions using the prepared Ni-modified catalytic electrodes. From these results, the prepared catalytic electrode could be used as the electrochemical sensor for phosphate in actual water.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020128
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 129: A Short Review of Aerobic Oxidative
           Desulfurization of Liquid Fuels over Porous Materials

    • Authors: Bo Yuan, Xiaolin Li, Yinyong Sun
      First page: 129
      Abstract: Oxidative desulfurization (ODS) has attracted much attention owing to the mild working conditions and effective removal of the aromatic sulfur-containing compounds which are difficult to desulfurize using the industrial hydrodesulfurization (HDS) technique. Molecular oxygen in ambient air have been recognized as an ideal oxidant in ODS due to its easy availability, non-toxicity and low cost in recent years. However, molecular oxygen activation under mild operating conditions is still a challenge. Porous materials and their composites have drawn increasing attention due to their advantages, such as high surface area and confined pore space, along with their stability. These merits contribute to the fast diffusion of oxygen molecules and the formation of more exposed active sites, which make them ideal catalysts for aerobic oxidation reactions. The confined space pore size offers a means of catalytic activity and durability improvement. This gives rise to copious attention toward the porous catalysts in AODS. In this review, the progress in the characteristics and AODS catalytic activities of porous catalysts is summarized. Then, emphasis on the molecular oxygen activation mechanism is traced. Finally, the breakthroughs and challenges of various categories of porous catalysts are concluded.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020129
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 130: Enhanced Photocatalytic Activity of
           Hierarchical Bi2WO6 Microballs by Modification with Noble Metals

    • Authors: Li, Wang, Zhang, Chang, Kowalska, Wei
      First page: 130
      Abstract: Visible-responsive photocatalysts for environmental purification and fuel generation are, currently, highly sought after. Among the possible candidates, Bi2WO6 (BWO) has been considered due to its efficient light harvesting, stability, and promising activities. Here, hierarchical BWO microballs have been prepared using a hydrothermal method, and additionally modified with deposits of noble metals (gold, silver, copper, palladium and platinum) by the photodeposition method. The structure, morphology, photoabsorption properties, and surface composition of bare and metal-modified BWO samples were investigated by XRD, SEM, DRS and XPS analyses. The photocatalytic activity was evaluated by the oxidative degradation of model dye (methyl orange (MO)) under UV/vis, and hydrogen generation under vis and/or UV irradiation. It was found that hierarchical morphology is detrimental for high photocatalytic activity in both tested systems, resulting in the improved degradation of MO (ca. 65% during 90 min of UV/vis irradiation), and hydrogen evolution (0.1 and 0.4 μmol h−1 under vis and UV/vis irradiation, respectively). Moreover, the type of noble metal and its properties influence the overall photocatalytic performance. It was found that, under UV/vis irradiation, only platinum accelerates hydrogen evolution, whereas under vis irradiation the activity follows the order: BWO < BWO/Cu < BWO/Ag < BWO/Pt < BWO/Pd < BWO/Au. It was concluded that zero-valent metal is recommended for high vis response, probably due to plasmonic photocatalysis, efficient light harvesting ability, and co-catalytic role.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020130
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 131: Hydrogen-Rich Gas Production from Two-Stage
           Catalytic Pyrolysis of Pine Sawdust with Calcined Dolomite

    • Authors: Xu, Xu, Wu
      First page: 131
      Abstract: The potential of catalytic pyrolysis of biomass for hydrogen and bio-oil production has drawn great attention due to the concern of clean energy utilization and decarbonization. In this paper, the catalytic pyrolysis of pine sawdust with calcined dolomite was carried out in a novel moving bed reactor with a two-stage screw feeder. The effects of pyrolysis temperature (700–900 °C) and catalytic temperature (500–800 °C) on pyrolysis performance were investigated in product distribution, gas composition, and gas properties. The results showed that with the temperature increased, pyrolysis gas yield increased, but the yield of solid and liquid products decreased. With the increase in temperature, the CO and H2 content increased significantly, while the CO2 and CH4 decreased correspondingly. The calcined dolomite can remove the tar by 44% and increased syngas yield by 52.9%. With the increasing catalytic temperature, the catalytic effect of calcined dolomite was also enhanced.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020131
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 132: Solar Heterogenous Photocatalytic
           Degradation of Methylthionine Chloride on a Flat Plate Reactor: Effect of
           pH and H2O2 Addition

    • Authors: Pablo E. Zaruma-Arias, Cynthia M. Núñez-Núñez, Luis A. González-Burciaga, José B. Proal-Nájera
      First page: 132
      Abstract: Methylthionine chloride (MTC) is a compound with several applications both in the clinical and medical industries. Nevertheless, such compounds can become an environmental problem, as they are not properly treated by wastewater treatment plants. This objective of this work was to study MTC degradation in a flat plate reactor through solar photolysis and heterogeneous photocatalysis processes with TiO2 as a catalyst. In addition to the processes, three pH (3.5, 6.5, and 9) and the effect of H2O2 addition (no dose, 0.5, and 1 mM/L) were tested. The results show that acidic pH is the most appropriate for MTC degradation, which ranged between 56% and 68.7% for photolysis and between 76% and 86.7% in photocatalysis. The H2O2 addition resulted in lower degradation in all cases, leading the authors to conclude that the presence of peroxide actually hinders degradation in solar photolysis and photocatalysis processes. Statistical analysis showed that the constant rate reactions calculated for every process, under the same conditions of pH and H2O2 addition, are significantly different from one another, and the three factors considered for experimental design (process, pH, and H2O2) have a statistically significant effect on MTC degradation. The collector area per order confirmed higher efficiency for photocatalysis when compared to photolysis processes.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020132
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 133: Effect of Water and Formic Acid on
           ·OH + CH4 Reaction: An Ab Initio/DFT Study

    • Authors: Ali, Muthiah
      First page: 133
      Abstract: In this work, we used ab initio/DFT method coupled with statistical rate theory to answer the question of whether or not formic acid (HCOOH) and water molecules can catalyze the most important atmospheric and combustion prototype reaction, i.e., ·OH (OH radical) + CH4. The potential energy surface for ·OH + CH4 and ·OH + CH4 (+X) (X = HCOOH, H2O) reactions were calculated using the combination of hybrid-density functional theory and coupled-cluster theory with Pople basis set [(CCSD(T)/ 6-311++G(3df,3pd)//M06-2X/6-311++G(3df,3pd)]. The results of this study show that the catalytic effect of HCOOH (FA) and water molecules on the ·OH +CH4 reaction has a major impact when the concentration of FA and H2O is not included. In this situation the rate constants for the CH4 + HO···HCOOH (3 × 10−9 cm3 molecule−1 s−1) reaction is ~105 times and for CH4 + H2O···HO reaction (3 × 10−14 cm3 molecule−1 s−1 at 300 K) is ~20 times higher than ·OH +CH4 (~6 × 10−15 cm3 molecule−1 s−1). However, the total effective rate constants, which include the concentration of both species in the kinetic calculation has no effect under atmospheric condition. As a result, the total effective reaction rate constants are smaller. The rate constants when taking the account of the FA and water for CH4 + HO···HCOOH (4.1 × 10−22 cm3 molecule−1 s−1) is at least seven orders magnitude and for the CH4 + H2O···HO (7.6 × 10−17 cm3 molecule−1 s−1) is two orders magnitude smaller than ·OH +CH4 reaction. These results are also consistent with previous experimental and theoretical studies on similar reaction systems. This study helps to understand how FA and water molecules change the reaction kinetic under atmospheric conditions for ·OH +CH4 reaction.
      Citation: Catalysts
      PubDate: 2022-01-21
      DOI: 10.3390/catal12020133
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 134: Methanol to Gasoline (MTG): Preparation,
           Characterization and Testing of HZSM-5 Zeolite-Based Catalysts to Be Used
           in a Fluidized Bed Reactor

    • Authors: Andrés Sanz-Martínez, Javier Lasobras, Jaime Soler, Javier Herguido, Miguel Menéndez
      First page: 134
      Abstract: The preparation of catalysts suitable for MTG processes in a fluidized bed reactor has been studied with emphasis on improving the textural, physico-chemical, morphological, structural and mechanical properties. A mixture of HZSM-5 zeolite (active material), boehmite or bentonite (binder) and alumina (inert filler) was used to prepare different catalysts. After preparation, characterization by physical adsorption of N2, XRF, XRD and SEM-EDX techniques was carried out. The screening of catalysts was performed in a fluidized bed reactor. The distribution of products was very similar in all cases, with the yield of light hydrocarbons always being higher than that of gasoline. Among the catalysts tested, the one containing boehmite as a binder (HZ_Boeh) was found as the most appropriate due to its high mechanical strength, high yield to aromatics and lower yield to durene.
      Citation: Catalysts
      PubDate: 2022-01-22
      DOI: 10.3390/catal12020134
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 135: Particle Recognition on Transmission
           Electron Microscopy Images Using Computer Vision and Deep Learning for
           Catalytic Applications

    • Authors: Anna V. Nartova, Mikhail Yu. Mashukov, Ruslan R. Astakhov, Vitalii Yu. Kudinov, Andrey V. Matveev, Alexey G. Okunev
      First page: 135
      Abstract: Recognition and measuring particles on microscopy images is an important part of many scientific studies, including catalytic investigations. In this paper, we present the results of the application of deep learning to the automated recognition of nanoparticles deposited on porous supports (heterogeneous catalysts) on images obtained by transmission electron microscopy (TEM). The Cascade Mask-RCNN neural network was used. During the training, two types of objects were labeled on raw TEM images of ‘real’ catalysts: visible particles and overlapping particle projections. The trained neural network recognized nanoparticles in the test dataset with 0.71 precision and 0.72 recall for both classes of objects and 0.84 precision and 0.79 recall for visible particles. The developed model is integrated into the open-access web service ‘ParticlesNN’, which can be used by any researcher in the world. Instead of hours, TEM data processing per one image analysis is reduced to a maximum of a couple of minutes and the divergence of mean particle size determination is approximately 2% compared to manual analysis. The proposed tool encourages accelerating catalytic research and improving the objectivity and accuracy of analysis.
      Citation: Catalysts
      PubDate: 2022-01-22
      DOI: 10.3390/catal12020135
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 136: Metal-Organic Frameworks (MOFs) and
           Materials Derived from MOFs as Catalysts for the Development of Green
           Processes

    • Authors: Gonzalo Valdebenito, Marco Gonzaléz-Carvajal, Luis Santibañez, Patricio Cancino
      First page: 136
      Abstract: This review will be centered around the work that has been reported on the development of metal–organic frameworks (MOFs) serving as catalysts for the conversion of carbon dioxide into short-chain hydrocarbons and the generation of clean energies starting from biomass. MOFs have mainly been used as support for catalysts or to prepare catalysts derived from MOFs (as sacrifice template), obtaining interesting results in the hydrogenation or oxidation of biomass. They have presented a good performance in the hydrogenation of CO2 into light hydrocarbon fuels. The common patterns to be considered in the performance of the catalysts are the acidity of MOFs, metal nodes, surface area and the dispersion of the active sites, and these parameters will be discussed in this review.
      Citation: Catalysts
      PubDate: 2022-01-22
      DOI: 10.3390/catal12020136
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 137: Controlled Transition Metal Nucleated
           Growth of Carbon Nanotubes by Molten Electrolysis of CO2

    • Authors: Xinye Liu, Gad Licht, Xirui Wang, Stuart Licht
      First page: 137
      Abstract: The electrolysis of CO2 in molten carbonate has been introduced as an alternative mechanism to synthesize carbon nanomaterials inexpensively at high yield. Until recently, CO2 was thought to be unreactive, making its removal a challenge. CO2 is the main cause of anthropogenic global warming and its utilization and transformation into a stable, valuable material provides an incentivized pathway to mitigate climate change. This study focuses on controlled electrochemical conditions in molten lithium carbonate to split CO2 absorbed from the atmosphere into carbon nanotubes (CNTs), and into various macroscopic assemblies of CNTs, which may be useful for nano-filtration. Different CNT morphologies were prepared electrochemically by variation of the anode and cathode composition and architecture, variation of the electrolyte composition pre-electrolysis processing, and variation of the current application and current density. Individual CNT morphologies’ structures and the CNT molten carbonate growth mechanisms are explored using SEM (scanning electron microscopy), TEM (transmission electron micrsocopy), HAADF (high angle annular dark field), EDX (energy dispersive xray), x-ray diffraction), and Raman methods. The principle commercial technology for CNT production had been chemical vapor deposition, which is an order of magnitude more expensive, generally requires metallo-organics, rather than CO2 as reactants, and can be highly energy and CO2 emission intensive (carries a high carbon positive, rather than negative, footprint).
      Citation: Catalysts
      PubDate: 2022-01-22
      DOI: 10.3390/catal12020137
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 138: The Impact of Alternative Fuels on Ship
           Engine Emissions and Aftertreatment Systems: A Review

    • Authors: Feng, Xu, Yuan, Xing, Shen, Li, Zhang, Wang, Wang, Ma, Kong
      First page: 138
      Abstract: Marine engines often use diesel as an alternative fuel to improve the economy. In recent years, waste oil, biodiesel and alcohol fuel are the most famous research directions among the alternative fuels for diesel. With the rapid development of the shipping industry, the air of coastal areas is becoming increasingly polluted. It is now necessary to reduce the emission of marine engines to meet the strict emission regulations. There are many types of alternative fuels for diesel oil and the difference of the fuel may interfere with the engine emissions; however, PM, HC, CO and other emissions will have a negative impact on SCR catalyst. This paper reviews the alternative fuels such as alcohols, waste oils, biodiesel made from vegetable oil and animal oil, and then summarizes and analyzes the influence of different alternative fuels on engine emissions and pollutant formation mechanism. In addition, this paper also summarizes the methods that can effectively reduce the emissions of marine engines; it can provide a reference for the study of diesel alternative fuel and the reduction of marine engine emissions.
      Citation: Catalysts
      PubDate: 2022-01-23
      DOI: 10.3390/catal12020138
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 139: Purification and Structural
           Characterization of the Auxiliary Activity 9 Native Lytic Polysaccharide
           Monooxygenase from Thermoascus aurantiacus and Identification of Its C1-
           and C4-Oxidized Reaction Products

    • Authors: Weishuai Yu, Imran Mohsin, Anastassios C. Papageorgiou, Duochuan Li
      First page: 139
      Abstract: Auxiliary activity 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) are copper-dependent oxidoreductases that use O2 or H2O2 to perform oxidative cleavage of cellulose in the presence of an electron donor. Combined with cellulases, they can assist in a more efficient cleavage of cellulose. AA9 LPMOs have therefore attracted considerable attention in recent years for use in biotechnological applications. Here, a native AA9 LPMO (nTaAA9A) from the thermophilic fungus Thermoascus aurantiacus was purified and characterized. The enzyme was shown to be active and able to cleave cellulose and xylan to produce C1- and C4-oxidized products. It was also found to retain about 84.3, 63.7, and 35.3% of its activity after incubation for 30 min at 60, 70, and 80 °C, respectively, using quantitative activity determination. The structure was determined to 1.36 Å resolution and compared with that of the recombinant enzyme expressed in Aspergillus oryzae. Structural differences in the glycosylated Asn138 and in solvent-exposed loops were identified.
      Citation: Catalysts
      PubDate: 2022-01-23
      DOI: 10.3390/catal12020139
      Issue No: Vol. 12, No. 2 (2022)
       
  • Catalysts, Vol. 12, Pages 46: Photocatalytic Performance of
           Carbon-Containing CuMo-Based Catalysts under Sunlight Illumination

    • Authors: Paula Muñoz-Flores, Po S. Poon, Catherine Sepulveda, Conchi O. Ania, Juan Matos
      First page: 46
      Abstract: Carbon-doped nanostructured CuMo-based photocatalysts were prepared by solvothermal synthesis. Two thermal treatments—oxidative and inert atmosphere—were used for the synthesis of the catalysts, and the influence of spherical carbon structures upon the crystalline phases on the photocatalytic activity and stability was studied. XRD showed the catalysts are nanostructured and composed by a mixture of copper (Cu, Cu2O, and CuO) and molybdenum (MoO2 and MoO3) crystalline phases. The catalysts were used for the degradation of yellow 5 under solar light. A remarkable leaching of Mo both in dark and under solar irradiation was observed and quantified. This phenomenon was responsible for the loss of photocatalytic activity for the degradation of the dye on the Mo-containing series. Conversely, the Cu-based photocatalysts were stable, with no leaching observed after 6 h irradiation and with a higher conversion of yellow 5 compared with the Mo- and CuMo series. The stability of Cu-based catalysts was attributed to a protective effect of spherical carbon structures formed during the solvothermal synthesis. Regarding the catalysts’ composition, sample Cu4-800-N2 prepared by pyrolysis exhibited up to 4.4 times higher photoactivity than that of the pristine material, which is attributed to a combined effect of an enhanced surface area and micropore volume generated during the pyrolytic treatment due to the presence of the carbon component in the catalyst. Scavenger tests have revealed that the mechanism for tartrazine degradation on irradiated Cu-based catalysts involves successive attacks of •OH radicals.
      Citation: Catalysts
      PubDate: 2022-01-01
      DOI: 10.3390/catal12010046
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 47: Chiral Ionic Liquids Based on l-Cysteine
           Derivatives for Asymmetric Aldol Reaction

    • Authors: Karolina Zalewska, Małgorzata E. Zakrzewska, Luis C. Branco
      First page: 47
      Abstract: Structure, and consequently properties, of ionic liquids can be easily tailored by changing cation/anion combinations and/or attaching functional groups. By grafting enantiopure moieties to the framework of ionic liquid it is possible to prepare bioinspired chiral molecules that can serve as a reaction medium, additive or even asymmetric catalyst. In this context, new chiral ionic liquids (CILs), based on biomolecules, such as aminoacids (l-Cysteine derivatives), have been synthesised and tested in asymmetric aldol condensation of aldehydes and ketones. The best results were obtained for CILs composed of S-methyl-l-cysteine cation and bis(trifluoromethane)sulfonimide anion, in the reaction of 2- or 4-nitrobenzaldehyde with acetone or cyclohexanone, giving the aldol product in moderate yields 70–76% and high ee values (up to 96%).
      Citation: Catalysts
      PubDate: 2022-01-01
      DOI: 10.3390/catal12010047
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 48: Eucalyptol, an All-Purpose Product

    • Authors: Joana F. Campos, Sabine Berteina-Raboin
      First page: 48
      Abstract: Eucalyptus plants have attracted the attention of researchers and environmentalists worldwide because they are a rapidly growing source of wood and a source of oil used for multiple purposes. The main and the most important oil component is 1,8-cineole (eucalyptol: 60–85%). This review summarizes the literature reported to date involving the use of 1,8-cineole for the treatment of disorders. Additionally, we describe our efforts in the use of eucalyptol as a solvent for the synthesis of O,S,N-heterocycles. Solvents used in chemistry are a fundamental element of the environmental performance of processes in corporate and academic laboratories. Their influence on costs, safety and health cannot be neglected. Green solvents such as bio-based systems hold considerable additional promise to reduce the environmental impact of organic chemistry. The first section outlines the process leading to our discovery of an unprecedented solvent and its validation in the first coupling reactions. This section continues with the description of its properties and characteristics and its reuse as reported in the various studies conducted. The second section highlights the use of eucalyptol in a series of coupling reactions (i.e., Suzuki–Miyaura, Sonogashira–Hagihara, Buchwald–Hartwig, Migita–Kosugi–Stille, Hiyama and cyanation) that form O,S,N-heterocycles. We describe the optimization process applied to reach the ideal conditions. We also show that eucalyptol can be a good alternative to build heterocycles that contain oxygen, sulfur and nitrogen. These studies allowed us to demonstrate the viability and potential that bio solvents can have in synthesis laboratories.
      Citation: Catalysts
      PubDate: 2022-01-02
      DOI: 10.3390/catal12010048
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 49: Electrocatalytic Properties of a
           BaTiO3/MWCNT Composite for Citric Acid Detection

    • Authors: Siraprapa Pitiphattharabun, Nicha Sato, Gasidit Panomsuwan, Oratai Jongprateep
      First page: 49
      Abstract: Although barium titanate (BaTiO3) shows prominent dielectric properties for fabricating electronic devices, its utilization in electrochemical applications is limited. Thus, this study examined the potential of a BaTiO3-based composite in the detection of a food additive, i.e., citric acid. First, a submicron-scale BaTiO3 powder was synthesized using the solution combustion method. Then, a BaTiO3/multiwalled carbon nanotube (MWCNT) composite was hydrothermally synthesized at BaTiO3:MWCNT mass ratios of 1:1 and 2:1. This composite was used as a working electrode in a nonenzymatic sensor to evaluate its electrocatalytic activity. Cyclic voltammetric measurements revealed that the BaTiO3/MWCNT composite (2:1) exhibited the highest electrocatalytic activity. Reduction reactions were observed at applied voltages of approximately 0.02 and −0.67 V, whereas oxidation reactions were detected at −0.65 and 0.47 V. With acceptable sensitivity, decent selectivity, and fair stability, the BaTiO3/MWCNT composite (2:1) showed good potential for citric acid detection.
      Citation: Catalysts
      PubDate: 2022-01-02
      DOI: 10.3390/catal12010049
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 50: An Overview of the Latest Advances in the
           Catalytic Synthesis of Glycerol Carbonate

    • Authors: Debora Procopio, Maria Luisa Di Gioia
      First page: 50
      Abstract: In recent years, the development of renewable energy alternatives to traditional fossil fuels has become one of the major challenges all over the world, due to the decline of fossil fuel reserves and their effect on global warming. Biodiesel has become a popular alternative energy source to reduce gas emissions compared to traditional fossil fuels. According to statistics, a nine-fold increase in global biofuel production between 2000 and 2020 was observed. However, its production generates a large amount of glycerol as a by-product, posing an environmental problem when disposed directly in landfills or by incineration. Therefore, low-value glycerol should be converted into high value-added derivatives. As glycerol carbonate is one of the most important derivatives of glycerol, this review aims to discuss the studies over the last ten years about glycerol carbonate synthetic methods, including the typical routes such as phosgene, esterification reaction, urea, oxidative and direct carbonylation as well as several rare synthetic procedures. At the same time, it summarizes the different catalytic reaction systems of each route comparing the advantages and disadvantages of various catalysts and evaluating their catalytic activity. Finally, the future development of glycerol carbonate synthesis is prospected from the point of view of development, technology research and industrialization.
      Citation: Catalysts
      PubDate: 2022-01-02
      DOI: 10.3390/catal12010050
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 51: Influence of Substrate Concentration on
           Kinetic Parameters of Ethanol Dehydration in MFI and CHA Zeolites and
           Relation of These Kinetic Parameters to Acid–Base Properties

    • Authors: Pavel Čičmanec, Jiří Kotera, Jan Vaculík, Roman Bulánek
      First page: 51
      Abstract: The catalytic activity of zeolites is often related to their acid–base properties. In this work, the relationship between the value of apparent activation energy of ethanol dehydration, measured in a fixed bed reactor and by means of a temperature-programmed surface reaction (TPSR) depending on the amount of ethanol in the zeolite lattice and the value of activation energy of H/D exchange as a measure of acid–base properties of MFI and CHA zeolites, was studied. Tests in a fixed bed reactor were unable to provide reliable reaction kinetics data due to internal diffusion limitations and rapid catalyst deactivation. Only the TPSR method was able to provide activation energy values comparable to the activation energy values obtained from the H/D exchange rate measurements. In addition, for CHA zeolite, it has been shown that the values of ethanol dehydration activation energies depend on the amount of ethanol in the CHA framework, and this effect can be attributed to the substrate clustering effects supporting the deprotonation of zeolite Brønsted centers.
      Citation: Catalysts
      PubDate: 2022-01-03
      DOI: 10.3390/catal12010051
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 52: Realistic Modelling of Dynamics at
           Nanostructured Interfaces Relevant to Heterogeneous Catalysis

    • Authors: Kevin Rossi, Tzonka Mineva, Jean-Sebastien Filhol, Frederik Tielens, Hazar Guesmi
      First page: 52
      Abstract: The focus of this short review is directed towards investigations of the dynamics of nanostructured metallic heterogeneous catalysts and the evolution of interfaces during reaction—namely, the metal–gas, metal–liquid, and metal–support interfaces. Indeed, it is of considerable interest to know how a metal catalyst surface responds to gas or liquid adsorption under reaction conditions, and how its structure and catalytic properties evolve as a function of its interaction with the support. This short review aims to offer the reader a birds-eye view of state-of-the-art methods that enable more realistic simulation of dynamical phenomena at nanostructured interfaces by exploiting resource-efficient methods and/or the development of computational hardware and software.
      Citation: Catalysts
      PubDate: 2022-01-04
      DOI: 10.3390/catal12010052
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 53: Catalysis in Zeolites and
           Zeotypes—Cornerstone of Chemical Industry and Permanent Subject of
           Research

    • Authors: Roman Bulánek
      First page: 53
      Abstract: Mankind has been aware of zeolites since 1756, when the Swede, Axel Fredrik Cronstedt (1722–1765), observed the strange behavior of a certain natural mineral (probably stellerite with some amounts of stilbite) [...]
      Citation: Catalysts
      PubDate: 2022-01-04
      DOI: 10.3390/catal12010053
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 54: Raw Biogas as Feedstock for the OCM Process

    • Authors: Barbara Michorczyk, Jakub Sikora, Bogusława Kordon-Łapczyńska, Dorota Gaweł, Izabela Czekaj
      First page: 54
      Abstract: The paper presents the research results obtained in the process of oxidative coupling of methane, in which unpurified biogas was used as the feedstock. Biogas obtained from two kinds of biomass materials, i.e., plant materials (potato and beet pulp, Corn-Cob-Mix—biogas 1) and animal waste (waste from fish filleting—biogas 2) was considered. The influence of temperature, the ratio of methane/oxygen and total flows of feedstock on the catalytic performance in oxidative coupling of methane process was investigated. Comparative tests were carried out using pure methane and a mixture of methane-carbon dioxide to simulate the composition of biogas 2. The process was carried out in the presence of an Mn-Na2WO4/SiO2 catalyst. Fresh and used catalysts were characterised by means of powder X-ray diffraction, X-ray photoelectron spectroscopy, and low-temperature nitrogen adsorption techniques. In oxidative coupling of methane, the type of raw material used as the source of methane has a small effect on methane conversion (the differences in methane conversion are below 3%), but a significant effect on the selectivity to C2. Depending on the type of raw material, the differences in selectivity to C2 reach as high as 9%. However, the Mn-Na2WO4/SiO2 catalyst operated steadily in the tested period of time at any feedstock composition. Moreover, it was found that CO2, which is the second main component of biogas in addition to methane, has an effect on catalytic performance. Comparative results of catalytic tests indicate that the CO2 effect varies with temperature. Below 1073 K, CO2 exerts a small poisoning effect on methane conversion, while above this temperature the negative effect of CO2 disappears. In the case of selectivity to C2+, the negative effect of CO2 was observed only at 1023 K. At higher temperatures, CO2 enhances selectivity to C2+. The effect of CO2 was established by correlating the catalytic results with the temperature programmed desorption of CO2 investigation. The poisoning effect of CO2 was connected with the formation of surface Na2CO3, whose concentration depends on temperature.
      Citation: Catalysts
      PubDate: 2022-01-05
      DOI: 10.3390/catal12010054
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 55: Metabolomics-Guided Analysis of the
           Biocatalytic Conversion of Sclareol to Ambradiol by Hyphozyma roseoniger

    • Authors: Efficient N. Ncube, Paul A. Steenkamp, Chris W. van der Westhuyzen, Lucia H. Steenkamp, Ian A. Dubery
      First page: 55
      Abstract: The biocatalytic conversion of sclareol to ambradiol, a valuable component in the fragrance industry, using whole-cell biotransformation by the dimorphic yeast Hyphozyma roseoniger, was investigated using metabolomics tools. An integrated approach was used to identify and quantify the participating intermediates in this bioconversion using both nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography coupled to mass spectrometry (LC–MS). This study entailed growth stage-dependent analysis of H. roseoniger suspensions grown in batch culture over a 14-day period, beginning with a three-day induction period using 20 mg/200 mL sclareol, followed by a further 1 g/200 mL sclareol dose to enable ambradiol production. The progress of the bioconversion and the resulting dynamic changes to the metabolome were monitored using NMR analysis and semi-targeted LC–MS metabolomics. This outlined the molecular conversions occurring within the matrix and no novel intermediates participating in the sclareol to ambradiol conversion could be identified. This study presents new findings about the transformative capabilities of H. roseoniger as a whole cell biocatalyst, highlighting its potential utility in similar applications.
      Citation: Catalysts
      PubDate: 2022-01-04
      DOI: 10.3390/catal12010055
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 56: Closed-Form Formulation of the
           Thermodynamically Consistent Electrochemical Model Considering
           Electrochemical Co-Oxidation of CO and H2 for Simulating Solid Oxide Fuel
           Cells

    • Authors: Andraž Kravos, Tomaž Katrašnik
      First page: 56
      Abstract: Achieving efficient solid oxide fuel cell operation and simultaneous prevention of degradation effects calls for the development of precise on-line monitoring and control tools based on predictive, computationally fast models. The originality of the proposed modelling approach originates from the hypothesis that the innovative derivation procedure enables the development of a thermodynamically consistent multi-species electrochemical model that considers the electrochemical co-oxidation of carbon monoxide and hydrogen in a closed-form. The latter is achieved by coupling the equations for anodic reaction rates with the equation for anodic potential. Furthermore, the newly derived model is capable of accommodating the diffusive transport of gaseous species through the gas diffusion layer, yielding a computationally efficient quasi-one-dimensional model. This resolves a persistent knowledge gap, as the proposed modelling approach enables the modelling of multi-species fuels in a closed form, resulting in very high computational efficiency, and thus enable the model’s real-time capability. Multiple validation steps against polarisation curves with different fuel mixtures confirm the capability of the newly developed model to replicate experimental data. Furthermore, the presented results confirm the capability of the model to accurately simulate outside the calibrated variation space under different operating conditions and reformate mixtures. These functionalities position the proposed model as a beyond state-of-the-art tool for model supported development and control applications.
      Citation: Catalysts
      PubDate: 2022-01-04
      DOI: 10.3390/catal12010056
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 57: LaNiO3 Perovskite Synthesis through the
           EDTA–Citrate Complexing Method and Its Application to CO Oxidation

    • Authors: Daniela González-Varela, Daniel G. Araiza, Gabriela Díaz, Heriberto Pfeiffer
      First page: 57
      Abstract: A series of LaNiO3 materials were synthesized by the EDTA–citrate complexing method, modifying different physicochemical conditions. The LaNiO3 samples were calcined between 600 and 800 °C and characterized by XRD, SEM, XPS, CO-TPD, TG, DT, and N2 adsorption. The results evidence that although all the samples presented the same crystal phase, LaNiO3 as expected, some microstructural and superficial features varied as a function of the calcination temperature. Then, LaNiO3 samples were tested as catalysts of the CO oxidation process, a reaction never thoroughly analyzed employing this material. The catalytic results showed that LaNiO3 samples calcined at temperatures of 600 and 700 °C reached complete CO conversions at ~240 °C, while the sample thermally treated at 800 °C only achieved a 100% of CO conversion at temperatures higher than 300 °C. DRIFTS and XRD were used for studying the reaction mechanism and the catalysts’ structural stability, respectively. Finally, the obtained results were compared with different Ni-containing materials used in the same catalytic process, establishing that LaNiO3 has adequate properties for the CO oxidation process.
      Citation: Catalysts
      PubDate: 2022-01-05
      DOI: 10.3390/catal12010057
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 58: A Nickel Coated Copper Substrate as a
           Hydrogen Evolution Catalyst

    • Authors: Poshan Kumar Reddy Kuppam, K. M. M. D. K. Kimbulapitiya, Srikanth Vuppala, Kuangye Wang, G. Phaneendra Reddy, Krishna P. Pande, Po-Tsung Lee, Yun-Lun Chueh
      First page: 58
      Abstract: Replacing precious metals with low-cost metals is the best solution for large scale production. Copper is known for its excellent conductivity and thermal management applications. When it comes to hydrogen evolution reaction, it is highly unstable, especially in KOH solution. In this paper, we approached a simple method to reduce corrosion and improve the performance by depositing nickel-molybdenum oxide and nickel on copper substrates and the achieved tafel slopes of 115 mV/dec and 117 mV/dec at 10 mA/cm2. While at first, molybdenum oxide coated samples showed better performance after 100 cycles of stability tests, the onset potential rapidly changed. Cu-Ni, which was deposited using the electron gun evaporation (e-gun), has shown better performance with 0.28 V at 10 mA/cm2 and led to stability after 100 cycles. Our results show that when copper is alloyed with nickel, it acts as a promising hydrogen evolution reaction (HER) catalyst.
      Citation: Catalysts
      PubDate: 2022-01-05
      DOI: 10.3390/catal12010058
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 59: Highly Efficient and Ambient-Temperature
           Synthesis of Benzimidazoles via Co(III)/Co(II)-Mediated Redox Catalysis

    • Authors: Renyuan Zhong, Wulin Xiong, Haoyuan Zhang, Tongtong Zeng, Shanshan Gong, Qi Sun
      First page: 59
      Abstract: An efficient method for ambient-temperature synthesis of a variety of 2-substituted and 1,2-disubstituted benzimidazoles from aldehyde and phenylenediamine substrates has been developed by utilizing Co(III)/Co(II)-mediated redox catalysis. The combination of only 1 mol% of Co(acac)2 and stoichiometric amount of hydrogen peroxide provides a fast, green, and mild access to a diversity of benzimidazoles under solvent-free conditions.
      Citation: Catalysts
      PubDate: 2022-01-05
      DOI: 10.3390/catal12010059
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 60: Structure and Photocatalytic Activity of
           Copper and Carbon-Doped Metallic Zn Phase-Rich ZnO Oxide Films

    • Authors: Simona Tuckute, Sarunas Varnagiris, Marius Urbonavicius, Emilija Demikyte, Kristina Bockute, Martynas Lelis
      First page: 60
      Abstract: ZnO is one of the most important industrial metal oxide semiconductors. However, in order to fully realise its potential, the electronic structure of ZnO has to be modified to better fit the needs of specific fields. Recent studies demonstrated that reactive magnetron sputtering under Zn-rich conditions promotes the formation of intrinsic ZnO defects and allows the deposition of metallic Zn phase-rich ZnO films. In photocatalytic efficiency tests these films were superior to traditional ZnO oxide, therefore, the purposeful formation of intrinsic ZnO defects, namely Zn interstitials and oxygen vacancies, can be considered as advantageous self-doping. Considering that such self-doped ZnO remains a semiconductor, the natural question is if it is possible to further improve its properties by adding extrinsic dopants. Accordingly, in the current study, the metallic Zn phase-rich ZnO oxide film formation process (reactive magnetron sputtering) was supplemented by simultaneous sputtering of copper or carbon. Effects of the selected dopants on the structure of self-doped ZnO were investigated by X-ray diffractometer, scanning electron microscope, X-ray photoelectron spectroscope and photoluminescence techniques. Meanwhile, its effect on photocatalytic activity was estimated by visible light activated bleaching of Methylene Blue. It was observed that both dopants modify the microstructure of the films, but only carbon has a positive effect on photocatalytic efficiency.
      Citation: Catalysts
      PubDate: 2022-01-06
      DOI: 10.3390/catal12010060
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 61: Copper (II) Heterocyclic Thiosemicarbazone
           Complexes as Single-Source Precursors for the Preparation of Cu9S5
           Nanoparticles: Application in Photocatalytic Degradation of Methylene Blue
           

    • Authors: Adrien P. Yepseu, Thomas Girardet, Linda D. Nyamen, Solenne Fleutot, Kevin I. Y. Ketchemen, Franck Cleymand, Peter T. Ndifon
      First page: 61
      Abstract: In this study, two copper(II) complexes, [Cu(C6H8N3S2)2]Cl2 (1) and [Cu(C7H10N3S2)2]Cl2·H2O (2), were synthesized from 2-(thiophen-2-ylmethylene)hydrazine-1-carbothioamide (L1H) and 2-(1-(thiophen-2-yl)ethylidene)hydrazine-1-carbothioamide (L2H) respectively and characterized using various spectroscopic techniques and elemental analyses. The as-prepared complexes were used as single-source precursors for the synthesis of oleylamine-capped (OLA@CuxSy), hexadecylamine-capped (HDA@CuxSy), and dodecylamine-capped (DDA@CuxSy) copper sulphide nanoparticles (NPs) via the thermolysis method at 190 °C and 230 °C and then characterized using powder X-ray diffraction (p-XRD), UV-visible spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The p-XRD diffraction patterns confirmed the formation of crystalline rhombohedral digenite Cu9S5 with the space group R-3m. The TEM images showed the formation of nanoparticles of various shapes including hexagonal, rectangular, cubic, truncated-triangular, and irregularly shaped Cu9S5 nanomaterials. The SEM results showed aggregates and clusters as well as the presence of pores on the surfaces of nanoparticles synthesized at 190 °C. The UV-visible spectroscopy revealed a general blue shift observed in the absorption band edge of the copper sulphide NPs, as compared to bulk CuxSy, with energy band gaps ranging from 2.52 to 3.00 eV. Energy-dispersive X-ray spectroscopy (EDX) confirmed the elemental composition of the Cu9S5 nanoparticles. The nanoparticles obtained at 190 °C and 230 °C were used as catalysts for the photocatalytic degradation of methylene blue (MB) under UV irradiation. Degradation rates varying from 47.1% to 80.0% were obtained after 90 min of exposure time using only 10 mg of the catalyst, indicating that Cu9S5 nanoparticles have potential in the degradation of organic pollutants (dyes).
      Citation: Catalysts
      PubDate: 2022-01-06
      DOI: 10.3390/catal12010061
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 62: Hypercrosslinked Ionic Polymers with High
           Ionic Content for Efficient Conversion of Carbon Dioxide into Cyclic
           Carbonates

    • Authors: Xu Liao, Baoyou Pei, Ruixun Ma, Lingzheng Kong, Xilin Gao, Jiao He, Xiaoyan Luo, Jinqing Lin
      First page: 62
      Abstract: The effective conversion of carbon dioxide (CO2) into cyclic carbonates requires porous materials with high ionic content and large specific surface area. Herein, we developed a new systematic post-synthetic modification strategy for synthesizing imidazolium-based hypercrosslinked ionic polymers (HIPs) with high ionic content (up to 2.1 mmol g−1) and large specific surface area (385 m2 g−1) from porous hypercrosslinked polymers (HCPs) through addition reaction and quaternization. The obtained HIPs were efficient in CO2 capture and conversion. Under the synergistic effect of high ionic content, large specific surface area, and plentiful micro/mesoporosity, the metal-free catalyst [HCP-CH2-Im][Cl]-1 exhibited quantitative selectivities, high catalytic yields, and good substrate compatibility for the conversion of CO2 into cyclic carbonates at atmospheric pressure (0.1 MPa) in a shorter reaction time in the absence of cocatalysts, solvents, and additives. High catalytic yields (styrene oxide, 120 °C, 8 h, 94% yield; 100 °C, 20 h, 93% yield) can be achieved by appropriately extending the reaction times at low temperature, and the reaction times are shorter than other porous materials under the same conditions. This work provides a new strategy for synthesizing an efficient metal-free heterogeneous catalyst with high ionic content and a large specific surface area from HCPs for the conversion of CO2 into cyclic carbonates. It also demonstrates that the ionic content and specific surface area must be coordinated to obtain high catalytic activity for CO2 cycloaddition reaction.
      Citation: Catalysts
      PubDate: 2022-01-06
      DOI: 10.3390/catal12010062
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 63: Noble-Metal-Based Catalytic Oxidation
           Technology Trends for Volatile Organic Compound (VOC) Removal

    • Authors: Hyo-Sik Kim, Hyun-Ji Kim, Ji-Hyeon Kim, Jin-Ho Kim, Suk-Hwan Kang, Jae-Hong Ryu, No-Kuk Park, Dae-Sik Yun, Jong-Wook Bae
      First page: 63
      Abstract: Volatile organic compounds (VOCs) are toxic and are considered the most important sources for the formation of photochemical smog, secondary organic aerosols (SOAs), and ozone. These can also greatly affect the environment and human health. For this reason, VOCs are removed by applying various technologies or reused after recovery. Catalytic oxidation for VOCs removal is widely applied in the industry and is regarded as an efficient and economical method compared to other VOCs removal technologies. Currently, a large amount of VOCs are generated in industries with solvent-based processes, and the ratio of aromatic compounds is high. This paper covers recent catalytic developments in VOC combustion over noble-metal-based catalysts. In addition, this report introduces recent trends in the development of the catalytic mechanisms of VOC combustion and the deactivation of catalysts, such as coke formation, poisoning, sintering, and catalyst regeneration. Since VOC oxidation by noble metal catalysts depends on the support of and mixing catalysts, an appropriate catalyst should be used according to reaction characteristics. Moreover, noble metal catalysts are used together with non-noble metals and play a role in the activity of other catalysts. Therefore, further elucidation of their function and catalytic mechanism in VOC removal is required.
      Citation: Catalysts
      PubDate: 2022-01-07
      DOI: 10.3390/catal12010063
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 64: Recent Developments in Advanced Oxidation
           Processes for Organics-Polluted Soil Reclamation

    • Authors: Crina Calenciuc, Antía Fdez-Sanromán, Gabriela Lama, Sivasankar Annamalai, Angeles Sanromán, Marta Pazos
      First page: 64
      Abstract: Soil pollution has become a substantial environmental problem which is amplified by overpopulation in different regions. In this review, the state of the art regarding the use of Advanced Oxidation Processes (AOPs) for soil remediation is presented. This review aims to provide an outline of recent technologies developed for the decontamination of polluted soils by using AOPs. Depending on the decontamination process, these techniques have been presented in three categories: the Fenton process, sulfate radicals process, and coupled processes. The review presents the achievements of, and includes some reflections on, the status of these emerging technologies, the mechanisms, and influential factors. At the present, more investigation and development actions are still desirable to bring them to real full-scale implementation.
      Citation: Catalysts
      PubDate: 2022-01-07
      DOI: 10.3390/catal12010064
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 65: Activation of Cobalt Foil Catalysts for CO
           Hydrogenation

    • Authors: Erling Rytter, Christian Aaserud, Anne-Mette Hilmen, Edvard Bergene, Anders Holmen
      First page: 65
      Abstract: CO hydrogenation has been studied on cobalt foils as model catalysts for Fischer–Tropsch (FT) synthesis. The effect of pretreatment (number of calcinations and different reduction times) for cobalt foil catalysts at 220 °C, 1 bar, and H2/CO = 3 has been studied in a microreactor. The foils were examined by scanning electron microscopy (SEM). It was found that the catalytic activity of the cobalt foil increases with the number of pretreatments. The mechanism is likely an increase in the available cobalt surface area from progressively deeper oxidation of the foil, supported by surface roughness detected by SEM. The highest FT activity was obtained using a reduction time of only 5 min (compared to 1 and 30 min). Prolonged reduction caused the sintering of cobalt crystallites, while too short of a reduction time led to incomplete reduction and small crystallites susceptible to low turn-over frequency from structure sensitivity. Larger crystals from longer reduction times gave increased selectivity to heavier components. The paraffin/olefin ratio increased with the increasing number of pretreatments due to olefin hydrogenation favored by enhanced cobalt site density. From the results, it is suggested that olefin hydrogenation is not structure sensitive, and that mass transfer limitations may occur depending on the pretreatment procedure. Produced water did not influence the results for the low conversions experienced in the present study (<6%).
      Citation: Catalysts
      PubDate: 2022-01-08
      DOI: 10.3390/catal12010065
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 66: Dielectric Barrier Discharge Plasma-Assisted
           Catalytic CO2 Hydrogenation: Synergy of Catalyst and Plasma

    • Authors: Xingyuan Gao, Jinglong Liang, Liqing Wu, Lixia Wu, Sibudjing Kawi
      First page: 66
      Abstract: CO2 hydrogenation is an effective way to convert CO2 to value-added chemicals (e.g., CH4 and CH3OH). As a thermal catalytic process, it suffers from dissatisfactory catalytic performances (low conversion/selectivity and poor stability) and high energy input. By utilizing the dielectric barrier discharge (DBD) technology, the catalyst and plasma could generate a synergy, activating the whole process in a mild condition, and enhancing the conversion efficiency of CO2 and selectivity of targeted product. In this review, a comprehensive summary of the applications of DBD plasma in catalytic CO2 hydrogenation is provided in detail. Moreover, the state-of-the-art design of the reactor and optimization of reaction parameters are discussed. Furthermore, several mechanisms based on simulations and experiments are provided. In the end, the existing challenges of this hybrid system and corresponding solutions are proposed.
      Citation: Catalysts
      PubDate: 2022-01-08
      DOI: 10.3390/catal12010066
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 67: Kinetic Resolution in Transannular
           Morita-Baylis-Hillman Reaction: An Approximation to the Synthesis of
           Sesquiterpenes from Guaiane Family

    • Authors: Raquel Mato, Rubén Manzano, Efraím Reyes, Liher Prieto, Uxue Uria, Luisa Carrillo, Jose L. Vicario
      First page: 67
      Abstract: An approximation to the synthesis of several sesquiterpenes from the Guaiane family is described in which the core structure was obtained through a transannular Morita-Baylis-Hillman reaction performed under kinetic resolution. Several manipulations of the obtained MBH adduct have been carried out directed towards the total synthesis of γ-Gurjunene, to the formal synthesis of Clavukerin A, to the synthesis of a non-natural isomer of isoguaiane and to the synthesis of an advanced intermediate in the total synthesis of Palustrol.
      Citation: Catalysts
      PubDate: 2022-01-08
      DOI: 10.3390/catal12010067
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 68: Supported Metal Catalysts for the Synthesis
           of N-Heterocycles

    • Authors: Laura Antonella Aronica, Gianluigi Albano
      First page: 68
      Abstract: Nitrogen-containing heterocycles are important scaffolds for a large number of compounds with biological, pharmaceutical, industrial and optoelectronic applications. A wide range of different methodologies for the preparation of N-heterocycles are based on metal-catalyzed cyclization of suitable substrates. Due to the growing interest in Green Chemistry criteria over the past two decades, the use of supported metal catalysts in the preparation of N-heterocycles has become a central topic in Organic Chemistry. Here we will give a critical overview of all the solid supported metal catalysts applied in the synthesis of N-heterocycles, following a systematic approach as a function of the type of support: (i) metal catalysts supported on inorganic matrices; (ii) metal catalysts supported on organic matrices; (iii) metal catalysts supported on hybrid inorganic-organic matrices. In particular, we will try to emphasize the effective heterogeneity and recyclability of the described metal catalysts, specifying which studies were carried out in order to evaluate these aspects.
      Citation: Catalysts
      PubDate: 2022-01-09
      DOI: 10.3390/catal12010068
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 69: Production of Hydroxypyruvic Acid by
           Glycerol Oxidation over Pt/CeO2-ZrO2-Bi2O3-PbO/SBA-16 Catalysts

    • Authors: Yeon-Bin Choi, Naoyoshi Nunotani, Kunimitsu Morita, Nobuhito Imanaka
      First page: 69
      Abstract: Pt/CeO2-ZrO2-Bi2O3-PbO/SBA-16 (SBA-16: Santa Barbara Amorphous No. 16) catalysts were synthesized to produce hydroxypyruvic acid by glycerol oxidation. In the catalysts, the introduction of PbO into CeO2-ZrO2-Bi2O3 improved the oxygen release and storage abilities owing to the synergistic redox reaction of Pb2+/4+ and Ce3+/4+, which facilitated the oxidation ability of Pt. In addition, the oxidation of the secondary OH group in glycerol might be accelerated by the geometric effects of glycerol, Pt, and Bi3+ or Pb2+/4+. Furthermore, the moderate reaction conditions such as room temperature and open-air atmosphere enabled the suppression of further oxidation of hydroxypyruvic acid. The highest catalytic activity was obtained for 7 wt% Pt/16 wt% Ce0.60Zr0.15Bi0.20Pb0.05O2−δ/SBA-16, which provided a hydroxypyruvic acid yield maximum of 24.6%, after the reaction for 6 h at 30 °C in atmospheric air.
      Citation: Catalysts
      PubDate: 2022-01-09
      DOI: 10.3390/catal12010069
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 70: Challenging Conditions for Gasoline
           Particulate Filters (GPFs)

    • Authors: Barouch Giechaskiel, Anastasios Melas, Victor Valverde, Marcos Otura, Giorgio Martini
      First page: 70
      Abstract: The emission limit of non-volatile particles (i.e., particles that do not evaporate at 350 °C) with size >23 nm, in combination with the real driving emissions (RDE) regulation in 2017, resulted in the introduction of gasoline particulate filters (GPFs) in all light-duty vehicles with gasoline direct injection engines in Europe. Even though there are studies that have examined the particulate emissions at or beyond the current RDE boundary conditions, there is a lack of studies combining most or all worst cases (i.e., conditions that increase the emissions). In this study, we challenged a fresh (i.e., no accumulation of soot or ash) “advanced” prototype GPF at different temperatures (down to −9 °C), aggressive drive cycles and hard accelerations (beyond the RDE limits), high payload (up to 90%), use of all auxiliaries (air conditioning, heating of the seats and the rear window), and cold starts independently or simultaneously. Under hot engine conditions, the increase of the particulate emissions due to higher payload and lower ambient temperature was 30–90%. The cold start at low ambient temperature, however, had an effect on the emissions of up to a factor of 20 for particles >23 nm or 300 when considering particles <23 nm. We proposed that the reason for these high emissions was the incomplete combustion and the low efficiency of the three-way oxidation catalyst. This resulted in a high concentration of species that were in the gaseous phase at the high temperature of the close-coupled GPF and thus could not be filtered by the GPF. As the exhaust gas cooled down, these precursor species formed particles that could not be evaporated at 350 °C (the temperature of the particle number system). These results highlight the importance of the proper calibration of the engine out emissions at all conditions, even when a GPF is installed.
      Citation: Catalysts
      PubDate: 2022-01-09
      DOI: 10.3390/catal12010070
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 71: Mixed Metal Oxides of M1 MoVNbTeOx and TiO2
           as Composite Catalyst for Oxidative Dehydrogenation of Ethane

    • Authors: Yuxin Chen, Dan Dang, Binhang Yan, Yi Cheng
      First page: 71
      Abstract: Composite catalysts of mixed metal oxides were prepared by mixing a phase-pure M1 MoVNbTeOx with anatase-phase TiO2. Two methods were used to prepare the composite catalysts (the simple physically mixed or sol-gel method) for the improvement of the catalytic performance in the oxidative dehydrogenation of ethane (ODHE) process. The results showed that TiO2 particles with a smaller particle size were well dispersed on the M1 surface for the sol-gel method, which presented an excellent activity for ODHE. At the same operating condition (i.e., the contact time of 7.55 gcat·h/molC2H6 and the reaction temperature of 400 °C), the M1-TiO2-SM and M1-TiO2-PM achieved the space time yields of 0.67 and 0.52 kgC2H4/kgcat/h, respectively, which were about ~76% and ~35% more than that of M1 catalyst (0.38 kgC2H4/kgcat/h), respectively. The BET, ICP, XRD, TEM, SEM, H2-TPR, C2H6-TPSR, and XPS techniques were applied to characterize the catalysts. It was noted that the introduction of TiO2 raised the V5+ abundance on the catalyst surface as well as the reactivity of active oxygen species, which made contribution to the promotion of the catalytic performance. The surface morphology and crystal structure of used catalysts of either M1-TiO2-SM or M1-TiO2-PM remained stable as each fresh catalyst after 24 h time-on-stream tests.
      Citation: Catalysts
      PubDate: 2022-01-09
      DOI: 10.3390/catal12010071
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 72: Glycerol Hydrogenolysis to 1,2-Propanediol
           over Novel Cu/ZrO2 Catalysts

    • Authors: Giuseppina Luciani, Giovanna Ruoppolo, Gianluca Landi, Valentina Gargiulo, Michela Alfè, Almerinda Di Benedetto
      First page: 72
      Abstract: Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.
      Citation: Catalysts
      PubDate: 2022-01-10
      DOI: 10.3390/catal12010072
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 73: Tandem Reactions Based on the Cyclization of
           Carbon Dioxide and Propargylic Alcohols: Derivative Applications of
           α-Alkylidene Carbonates

    • Authors: Bowen Jiang, Xiangyu Yan, Yong Xu, Natalya Likhanova, Heriberto Díaz Velázquez, Yanyan Gong, Ye Yuan, Francis Verpoort
      First page: 73
      Abstract: As a well-known greenhouse gas, carbon dioxide (CO2) has attracted increasing levels of attention in areas of energy, environment, climate, etc. Notably, CO2 is an abundant, nonflammable, and renewable C1 feedstock in view of chemistry. Therefore, the transformation of CO2 into organic compounds is an extremely attractive research topic in modern green and sustainable chemistry. Among the numerous CO2 utilization methods, carboxylative cycloaddition of CO2 into propargylic alcohols is an ideal route due to the corresponding products, α-alkylidene cyclic carbonates, which are a series of highly functionalized compounds that supply numerous potential methods for the construction of various synthetically and biologically valuable agents. This cyclization reaction has been intensively studied and systematically summarized, in the past years. Therefore, attention has been gradually transferred to produce more derivative compounds. Herein, the tandem reactions of this cyclization with hydration, amination, alcoholysis, and isomerization to synthesize α-hydroxyl ketones, oxazolidinones, carbamates, unsymmetrical carbonates, tetronic acids, ethylene carbonates, etc. were systematically reviewed.
      Citation: Catalysts
      PubDate: 2022-01-10
      DOI: 10.3390/catal12010073
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 74: Cu/O Frustrated Lewis Pairs on Cu Doped
           CeO2(111) for Acetylene Hydrogenation: A First-Principles Study

    • Authors: Shulan Zhou, Qiang Wan, Sen Lin
      First page: 74
      Abstract: In this work, the H2 dissociation and acetylene hydrogenation on Cu doped CeO2(111) were studied using density functional theory calculations. The results indicated that Cu doping promotes the formation of oxygen vacancy (Ov) which creates Cu/O and Ce/O frustrated Lewis pairs (FLPs). With the help of Cu/O FLP, H2 dissociation can firstly proceed via a heterolytic mechanism to produce Cu-H and O-H by overcoming a barrier of 0.40 eV. The H on Cu can facilely migrate to a nearby oxygen to form another O-H species with a barrier of 0.43 eV. The rate-determining barrier is lower than that for homolytic dissociation of H2 which produces two O-H species. C2H2 hydrogenation can proceed with a rate-determining barrier of 1.00 eV at the presence of Cu-H and O-H species., While C2H2 can be catalyzed by two O-H groups with a rate-determining barrier of 1.06 eV, which is significantly lower than that (2.86 eV) of C2H2 hydrogenated by O-H groups on the bare CeO2(111), showing the high activity of Cu doped CeO2(111) for acetylene hydrogenation. In addition, the rate-determining barrier of C2H4 further hydrogenated by two O-H groups is 1.53 eV, much higher than its desorption energy (0.72 eV), suggesting the high selectivity of Cu doped CeO2(111) for C2H2 partial hydrogenation. This provides new insights to develop effective hydrogenation catalysts based on metal oxide.
      Citation: Catalysts
      PubDate: 2022-01-10
      DOI: 10.3390/catal12010074
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 75: Towards Catalysts Prepared by Cold Plasma

    • Authors: Jacek Tyczkowski, Hanna Kierzkowska-Pawlak
      First page: 75
      Abstract: Cold (non-equilibrium) plasma techniques have long been used as plasma deposition methods to create new materials, often with unique properties, which cannot be produced any other way, as well as plasma treatment methods for the sophisticated modification of conventional materials [...]
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010075
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 76: Biophotocatalytic Reduction of CO2 in
           Anaerobic Biogas Produced from Wastewater Treatment Using an Integrated
           System

    • Authors: Emmanuel Kweinor Tetteh, Sudesh Rathilal
      First page: 76
      Abstract: This study presents the bio-photocatalytic upgrading of biogas utilising carbon dioxide (CO2) as a potential option for beginning fossil fuel depletion and the associated environmental risks in the pursuit of sustainable development. Herein, magnetite photocatalyst (Fe-TiO2) was employed with an integrated anaerobic-photomagnetic system for the decontamination of municipality wastewater for biogas production. The Fe-TiO2 photocatalyst used, manufactured via a co-precipitation technique, had a specific surface area of 62.73 m2/g, micropore volume of 0.017 cm3/g and pore size of 1.337 nm. The results showed that using the ultraviolet-visible (UV-Vis) photomagnetic system as a post-treatment to the anaerobic digestion (AD) process was very effective with over 85% reduction in colour, chemical oxygen demand (COD) and turbidity. With an organic loading rate (OLR) of 0.394 kg COD/L·d and hydraulic retention time (HTR) of 21 days, a 92% degradation of the organic content (1.64 kgCOD/L) was attained. This maximised the bioenergy production to 5.52 kWh/m3 with over 10% excess energy to offset the energy demand of the UV-Vis lamp. Assuming 33% of the bioenergy produced was used as electricity to power the UV-Vis lamp, the CO2 emission reduction was 1.74 kg CO2 e/m3, with good potential for environmental conservation.
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010076
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 77: Biodegradable Composites with Functional
           Properties Containing Biopolymers

    • Authors: Miroslawa Prochon, Szymon Szczepanik, Oleksandra Dzeikala, Robert Adamski
      First page: 77
      Abstract: There is a major focus on natural biopolymers of bacterial, animal, or plant origin as ecological materials, replacing petrochemical products. Biologically derived polylactide (PLA), polyhydroxybutyrate (PHB), and polyhydroxyalkanoates (PHA) possess interesting properties, but they are currently too expensive for most applications. Therefore, researchers try to find other biopolymers that are both durable and cheap enough to replace plastics in some applications. One possible candidate is gelatin, which can be transformed into a thin, translucent film that is flexible and has stable and high mechanical properties. Here, we present a method of synthesizing a composite material from gelatin. For preparation of such material, we used gelatin of animal origin (pig skin) with the addition of casein, food gelatin, glycerin, and enzymes as biocatalysts of chemical modification and further extraction of gelatin from collagen. Compositions forming films with homogeneous shapes and good mechanical properties were selected (Tensile strength reaches 3.11 MPa, while the highest value of elongation at break is 97.96%). After administering the samples to microbial scaring, the composites completely decomposed under the action of microorganisms within 30 days, which proves their biodegradation.
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010077
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 78: Highly Photoactive Titanium Dioxide
           Supported Platinum Catalyst: Synthesis Using Cleaner Ultrasound Approach

    • Authors: Shital B. Potdar, Chao-Ming Huang, BVS Praveen, Sivakumar Manickam, Shirish H. Sonawane
      First page: 78
      Abstract: Catalysts increase reaction rates; however, the surface area to volume ratio of catalysts has a vital role in catalytic activity. The noble metals such as platinum (Pt) and gold (Au) are expensive; despite this, they have proven their existence in catalysis, motivating the synthesis of supported metal catalysts. Metal catalysts need to be highly dispersed onto the support. In this investigation, an ultrasound approach has been attempted to synthesise highly photoactive titanium dioxide (TiO2) nanoparticles by the hydrolysis of titanium tetraisopropoxide in an acetone/methanol mixture. To enhance its photocatalytic activity, TiO2 was doped with Pt. The synthesised photocatalyst was characterised by techniques such as particle size analysis (PSA), XRD, FE-SEM, TEM, and EDX. The enhancement in the surface characteristics of Pt-doped TiO2 compared with bare TiO2 support was confirmed with Brunauer–Emmett–Teller (BET) analysis. The enhanced surface area and uniformity in particle size distribution at the nanoscale level were due to the effects of ultrasonic irradiation. The obtained results corroborated the size and composition of the synthesised catalysts. The size of the catalysts is in the nanometre range, and good dispersion of Pt catalysts over the TiO2 support was observed. The UV-Visible spectroscopy analysis was performed to study the optical properties of the synthesised TiO2 and Pt/TiO2 photocatalysts. An increase in the absorbance was noted when Pt was added to TiO2, which is due to the decrease in the band gap energy.
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010078
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 79: Sustainable Electrochemical NO Capture and
           Storage System Based on the Reversible Fe2+/Fe3+-EDTA Redox Reaction

    • Authors: Heesung Eum, Seokhyeon Cheong, Jiyun Kim, Seo-Jung Han, Minserk Cheong, Hyunjoo Lee, Hae-Seok Lee, Dong Ki Lee
      First page: 79
      Abstract: The removal of nitric oxide (NO), which is an aggregation agent for fine dust that causes air pollution, from exhaust gas has been considered an important treatment in the context of environmental conservation. Herein, we propose a sustainable electrochemical NO removal system based on the reversible Fe2+/Fe3+-ethylenediamine tetraacetic acid (EDTA) redox reaction, which enables continuous NO capture and storage at ambient temperature without the addition of any sacrificial agents. We have designed a flow-type reaction system in which the NO absorption and emission can be separately conducted in the individual reservoirs of the catholyte and anolyte with the continuous regeneration of Fe2+-EDTA by the electrochemical reduction in Fe3+-EDTA. A continuous flow reaction using a silver cathode and glassy carbon anode showed that the concentrations of Fe2+ and Fe3+-EDTA in the electrolyte were successfully maintained at a 1:1 ratio, which demonstrates that the proposed system can be applied for continuous NO capture and storage.
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010079
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 80: Immobilization-Stabilization of
           β-Glucosidase for Implementation of Intensified Hydrolysis of
           Cellobiose in Continuous Flow Reactors

    • Authors: Celia Alvarez-Gonzalez, Victoria E. Santos, Miguel Ladero, Juan M. Bolivar
      First page: 80
      Abstract: Cellulose saccharification to glucose is an operation of paramount importance in the bioenergy sector and the chemical and food industries, while glucose is a critical platform chemical in the integrated biorefinery. Among the cellulose degrading enzymes, β-glucosidases are responsible for cellobiose hydrolysis, the final step in cellulose saccharification, which is usually the critical bottleneck for the whole cellulose saccharification process. The design of very active and stable β-glucosidase-based biocatalysts is a key strategy to implement an efficient saccharification process. Enzyme immobilization and reaction engineering are two fundamental tools for its understanding and implementation. Here, we have designed an immobilized-stabilized solid-supported β-glucosidase based on the glyoxyl immobilization chemistry applied in porous solid particles. The biocatalyst was stable at operational temperature and highly active, which allowed us to implement 25 °C as working temperature with a catalyst productivity of 109 mmol/min/gsupport. Cellobiose degradation was implemented in discontinuous stirred tank reactors, following which a simplified kinetic model was applied to assess the process limitations due to substrate and product inhibition. Finally, the reactive process was driven in a continuous flow fixed-bed reactor, achieving reaction intensification under mild operation conditions, reaching full cellobiose conversion of 34 g/L in a reaction time span of 20 min.
      Citation: Catalysts
      PubDate: 2022-01-11
      DOI: 10.3390/catal12010080
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 81: Acetalization of Glycerol with Citral over
           Heteropolyacids Immobilized on KIT-6

    • Authors: José Castanheiro
      First page: 81
      Abstract: Glycerol acetalization with citral was studied using a heteropolyacid (tungstophosphoric acid) supported on KIT-6, as a catalyst, at 100 °C. Different catalysts were synthesized. Catalysts were characterized by scanning electron microscopy (SEM), inductively coupled plasma (ICP), X-ray diffraction (XRD), attenuated total refletion-Fourier transform infrared spectroscopy (ATR-FTIR), and potentiometric titrations. At a fixed time, the glycerol conversion increased with the H3PW12O40 (PW) on KIT-6. PW4-KIT-6 material had a higher conversion than other catalysts. The optimization of glycerol’s acetalization with citral was studied under the PW4-KIT-6 catalyst. After 5 h, it was found that, at T = 100 °C, with m = 0.3 g of solid, molar glycerol:citral = 1:2.25, the conversion of glycerol was 89%. Moreover, the PW4-KTI-6 catalyst showed good catalytic stability.
      Citation: Catalysts
      PubDate: 2022-01-12
      DOI: 10.3390/catal12010081
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 82: Continuous Production of Fumaric Acid with
           Immobilised Rhizopus oryzae: The Role of pH and Urea Addition

    • Authors: Reuben Marc Swart, Dominic Kibet Ronoh, Hendrik Brink, Willie Nicol
      First page: 82
      Abstract: Fumaric acid is widely used in the food and beverage, pharmaceutical and polyester resin industries. Rhizopus oryzae is the most successful microorganism at excreting fumaric acid compared to all known natural and genetically modified organisms. It has previously been discovered that careful control of the glucose feed rate can eliminate the by-product formation of ethanol. Two key parameters affecting fumaric acid excretion were identified, namely the medium pH and the urea feed rate. A continuous fermentation with immobilised R. oryzae was utilised to determine the effect of these parameters. It was found that the selectivity for fumaric acid production increased at high glucose consumption rates for a pH of 4, different from the trend for pH 5 and 6, achieving a yield of 0.93 gg−1. This yield is higher than previously reported in the literature. Varying the urea feed rate to 0.255 mgL−1h−1 improved the yield of fumaric acid but experienced a lower glucose uptake rate compared to higher urea feed rates. An optimum region has been found for fumaric acid production at pH 4, a urea feed rate of 0.625 mgL−1h−1 and a glucose feed rate of 0.329 gL−1h−1.
      Citation: Catalysts
      PubDate: 2022-01-12
      DOI: 10.3390/catal12010082
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 83: Modified Cellulose with BINAP-Supported Rh
           as an Efficient Heterogeneous Catalyst for Asymmetric Hydrogenation

    • Authors: Cuiping Yu, Weilong Wu, Min Gao, Yu Liu
      First page: 83
      Abstract: Asymmetric catalysis is the preferred method for the synthesis of pure chiral molecules in the fine chemical industry. Cellulose has long been sought as a support in enantioselective catalysis. Dialdehyde cellulose (DAC) is produced by the selective oxidation of cellulose and is used to bind 5,5′-diamino Binap by forming a Schiff base. Here, we report the synthesis of modified cellulose-supported Rh as a novel biomass-supported catalyst and the characterization of its morphology, composition, and thermal stability. DAC-BINAP-Rh was a very effective catalyst in the asymmetric hydrogenation of enamides and could be easily recycled. This work provides a novel supported catalyst that broadens the applications of cellulose in asymmetric catalysis.
      Citation: Catalysts
      PubDate: 2022-01-12
      DOI: 10.3390/catal12010083
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 84: Enhanced Photocatalytic Activity of
           ZnO–CdS Composite Nanostructures towards the Degradation of
           Rhodamine B under Solar Light

    • Authors: Thirumala Rao Gurugubelli, R. V. S. S. N. Ravikumar, Ravindranadh Koutavarapu
      First page: 84
      Abstract: A simple chemical precipitation route was utilized for the synthesis of ZnO nanoparticles (NPs), CdS NPs and ZnO–CdS nanocomposites (NCs). The synthesized nanostructures were examined for the crystal structure, morphology, optical properties and photodegradation activity of rhodamine B (RhB) dye. The ZnO–CdS NCs showed a mixed phase of hexagonal wurtzite structure for both ZnO NPs and CdS NPs. Pure ZnO NPs and CdS NPs possessed bandgaps of 3.2617 and 2.5261 eV, respectively. On the other hand, the composite nanostructures displayed a more narrow bandgap of 2.9796 eV than pure ZnO NPs. When compared to bare ZnO NPs, the PL intensity of near-band-edge emission at 381 nm was practically suppressed, suggesting a lower rate of photogenerated electron–hole (e−/h+) pairs recombination, resulting in enhanced photocatalytic activity. Under solar light, the composite nanostructures displayed a photodegradation efficiency of 98.16% towards of RhB dye. After four trials, the structural stability of ZnO–CdS NCs was verified.
      Citation: Catalysts
      PubDate: 2022-01-12
      DOI: 10.3390/catal12010084
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 85: VOCs Photothermo-Catalytic Removal on
           MnOx-ZrO2 Catalysts

    • Authors: Roberto Fiorenza, Roberta Agata Farina, Enrica Maria Malannata, Francesca Lo Presti, Stefano Andrea Balsamo
      First page: 85
      Abstract: Solar photothermo-catalysis is a fascinating multi-catalytic approach for volatile organic compounds (VOCs) removal. In this work, we have explored the performance and the chemico-physical features of non-critical, noble, metal-free MnOx-ZrO2 mixed oxides. The structural, morphological, and optical characterizations of these materials pointed to as a low amount of ZrO2 favoured a good interaction and the ionic exchange between the Mn and the Zr ions. This favoured the redox properties of MnOx increasing the mobility of its oxygens that can participate in the VOCs oxidation through a Mars-van Krevelen mechanism. The further application of solar irradiation sped up the oxidation reactions promoting the VOCs total oxidation to CO2. The MnOx-5 wt.%ZrO2 sample showed, in the photothermo-catalytic tests, a toluene T90 (temperature of 90% of conversion) of 180 °C and an ethanol T90 conversion to CO2 of 156 °C, 36 °C, and 205 °C lower compared to the thermocatalytic tests, respectively. Finally, the same sample exhibited 84% toluene conversion and the best selectivity to CO2 in the ethanol removal after 5 h of solar irradiation at room temperature, a photoactivity similar to the most employed TiO2-based materials. The as-synthetized mixed oxide is promising for an improved sustainability in both catalyst design and environmental applications.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010085
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 86: Synthesis of Conjugated Dienes in Natural
           Compounds

    • Authors: Geoffrey Dumonteil, Sabine Berteina-Raboin
      First page: 86
      Abstract: This review describes the various synthetic methods commonly used to obtain molecules possessing conjugated dienes. We focus on methods involving cross-coupling reactions using various metals such as nickel, palladium, ruthenium, cobalt, cobalt/zinc, manganese, zirconium, or iron, mainly through examples that aimed to access natural molecules or their analogues. Among the natural molecules covered in this review, we discuss the total synthesis of a phytohormone, Acid Abscisic (ABA), carried out by our team involving the development of a conjugated diene chain.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010086
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 87: Bulk Co3O4 for Methane Oxidation: Effect of
           the Synthesis Route on Physico-Chemical Properties and Catalytic
           Performance

    • Authors: Andoni Choya, Beatriz de Rivas, Jose Ignacio Gutiérrez-Ortiz, Rubén López-Fonseca
      First page: 87
      Abstract: The synthesis of bulk pure Co3O4 catalysts by different routes has been examined in order to obtain highly active catalysts for lean methane combustion. Thus, eight synthesis methodologies, which were selected based on their relatively low complexity and easiness for scale-up, were evaluated. The investigated procedures were direct calcination of two different cobalt precursors (cobalt nitrate and cobalt hydroxycarbonate), basic grinding route, two basic precipitation routes with ammonium carbonate and sodium carbonate, precipitation-oxidation, solution combustion synthesis and sol-gel complexation. A commercial Co3O4 was also used as a reference. Among the several examined methodologies, direct calcination of cobalt hydroxycarbonate (HC sample), basic grinding (GB sample) and basic precipitation employing sodium carbonate as the precipitating agent (CC sample) produced bulk catalysts with fairly good textural and structural properties, and remarkable redox properties, which were found to be crucial for their good performance in the oxidation of methane. All catalysts attained full conversion and 100% selectivity towards CO2 formation at a temperature of 600 °C while operating at 60,000 h−1. Among these, the CC catalyst was the only one that achieved a specific reaction rate higher than that of the reference commercial Co3O4 catalyst.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010087
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 88: Lipases as Effective Green Biocatalysts for
           Phytosterol Esters’ Production: A Review

    • Authors: Adejanildo da S. Pereira, Aline Habibe de Souza, Jully L. Fraga, Pierre Villeneuve, Alexandre G. Torres, Priscilla F. F. Amaral
      First page: 88
      Abstract: Lipases are versatile enzymes widely used in the pharmaceutical, cosmetic, and food industries. They are green biocatalysts with a high potential for industrial use compared to traditional chemical methods. In recent years, lipases have been used to synthesize a wide variety of molecules of industrial interest, and extraordinary results have been reported. In this sense, this review describes the important role of lipases in the synthesis of phytosterol esters, which have attracted the scientific community’s attention due to their beneficial effects on health. A systematic search for articles and patents published in the last 20 years with the terms “phytosterol AND esters AND lipase” was carried out using the Scopus, Web of Science, Scielo, and Google Scholar databases, and the results showed that Candida rugosa lipases are the most relevant biocatalysts for the production of phytosterol esters, being used in more than 50% of the studies. The optimal temperature and time for the enzymatic synthesis of phytosterol esters mainly ranged from 30 to 101 °C and from 1 to 72 h. The esterification yield was greater than 90% for most analyzed studies. Therefore, this manuscript presents the new technological approaches and the gaps that need to be filled by future studies so that the enzymatic synthesis of phytosterol esters is widely developed.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010088
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 89: Catalytic Hydrofunctionalization Reactions
           of 1,3-Diynes

    • Authors: Victorio Cadierno
      First page: 89
      Abstract: Metal-catalyzed hydrofunctionalization reactions of alkynes, i.e., the addition of Y–H units (Y = heteroatom or carbon) across the carbon–carbon triple bond, have attracted enormous attention for decades since they allow the straightforward and atom-economic access to a wide variety of functionalized olefins and, in its intramolecular version, to relevant heterocyclic and carbocyclic compounds. Despite conjugated 1,3-diynes being considered key building blocks in synthetic organic chemistry, this particular class of alkynes has been much less employed in hydrofunctionalization reactions when compared to terminal or internal monoynes. The presence of two C≡C bonds in conjugated 1,3-diynes adds to the classical regio- and stereocontrol issues associated with the alkyne hydrofunctionalization processes’ other problems, such as the possibility to undergo 1,2-, 3,4-, or 1,4-monoadditions as well as double addition reactions, thus increasing the number of potential products that can be formed. In this review article, metal-catalyzed hydrofunctionalization reactions of these challenging substrates are comprehensively discussed.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010089
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 90: Heterocycles by Consecutive Multicomponent
           Syntheses via Catalytically Generated Alkynoyl Intermediates

    • Authors: Jonas Niedballa, Thomas J. J. Müller
      First page: 90
      Abstract: Multicomponent processes are beneficial tools for the synthesis of heterocycles. As densely substituted bifunctional electrophiles, ynones are essential intermediates by applying cyclocondensations or cycloadditions in numerous heterocycle syntheses. The respective alkynoyl intermediates are generally accessible by palladium-, copper- and palladium/copper-catalyzed alkynylation. In turn, the mild reaction conditions allow for a fast and versatile entry to functional heterocycles in the sense of consecutive multicomponent processes. This review collates and presents recent advances in accessing thirteen heterocycle classes and their applications by virtue of catalytic alkynoyl generation in diversity-oriented multicomponent syntheses in a one-pot fashion.
      Citation: Catalysts
      PubDate: 2022-01-13
      DOI: 10.3390/catal12010090
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 91: Solid Acid Catalysts for the Hock Cleavage
           of Hydroperoxides

    • Authors: Jan Drönner, Peter Hausoul, Regina Palkovits, Matthias Eisenacher
      First page: 91
      Abstract: The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol. In this mini-review, first a brief introduction and overview on the Hock process is given. Next, the mechanism, kinetics, and safety aspects are summarized and discussed. Following, the different types of heterogeneous catalysts and their performance as catalyst in the Hock process are illustrated. Finally, the different approaches to substitute sulfuric acid in the synthetic route to produce phenol are briefly concluded and a short outlook is given.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010091
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 92: Application of Raw and Chemically Modified
           Biomasses for Heterogeneous Cu-Catalysed Conversion of Aryl boronic Acids
           to Phenols Derivatives

    • Authors: Fernanda Guimarães Torres, Filipe Simões Teodoro, Leandro Vinícius Alves Gurgel, Flavien Bourdreux, Olfa Zayene, Anne Gaucher, Laurent Frédéric Gil, Damien Prim
      First page: 92
      Abstract: This work describes the application of raw and chemically modified cellulose and sugarcane bagasse for ipso-hydroxylation of aryl boronic acids in environmentally friendly reaction conditions. The catalytic efficiency of five support-[Cu] materials was compared in forming phenols from aryl boronic acids. Our investigation highlights that the CEDA-[Cu] material (6-deoxy-6-aminoethyleneamino cellulose loaded with Cu) leads to the best results under very mild reaction conditions. The optimized catalytic sequence, allowing a facile transformation of boronic acids to phenols, required the mandatory and joint presence of the support, Cu2O, and KOH at room temperature. CEDA-[Cu] was characterized using 13C solid-state NMR, ICP, and FTIR. The use of CEDA-[Cu] accounts for the efficacious synthesis of variously substituted phenol derivatives and presents very good recyclability after five catalytic cycles.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010092
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 93: Electrocatalysts Based on Novel Carbon Forms
           for the Oxidation of Sulphite

    • Authors: George Pchelarov, Dzhamal Uzun, Sasho Vassilev, Elena Razkazova-Velkova, Ognian Dimitrov, Aleksandar Tsanev, Adriana Gigova, Nadezhda Shukova, Konstantin Petrov
      First page: 93
      Abstract: Described herewith is an electrochemical method to decontaminate sulphur compounds. Studies were carried out of sulphites (SO32−) oxidation on a range of anode catalysts. The electrocatalysts were characterized by scanning electron microscopy, XRD, XPS and BET. Polarization curves were recorded of electrodes incorporating lyophilized higher fullerenes and manganese oxides. The experiments showed that lyophilized higher fullerenes and C60/C70 fullerene catalysts in conjunction with manganese oxides electrochemically convert sulphites (SO32−) to sulphates (SO42−). The oxidation products do not poison the electrodes. The XPS analysis shows that the catalysts incorporating DWCNTs, MWCNTs and higher fullerenes have a higher concentration of sp3C carbon bonding leading to higher catalytic activity. It is ascertained that higher fullerenes play a major role in the synthesis of more effective catalysts. The electrodes built by incorporating lyophilized catalysts containing higher fullerenes and manganese oxides are shown as most promising in the effective electrochemical decontamination of industrial and natural wastewaters.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010093
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 94: Recent Advances of Photocatalytic
           Hydrogenation of CO2 to Methanol

    • Authors: Gajanan Y. Shinde, Abhishek S. Mote, Manoj B. Gawande
      First page: 94
      Abstract: Constantly increasing hydrocarbon fuel combustion along with high levels of carbon dioxide emissions has given rise to a global energy crisis and environmental alterations. Photocatalysis is an effective technique for addressing this energy and environmental crisis. Clean and renewable solar energy is a very favourable path for photocatalytic CO2 reduction to value-added products to tackle problems of energy and the environment. The synthesis of various products such as CH4, CH3OH, CO, EtOH, etc., has been expanded through the photocatalytic reduction of CO2. Among these products, methanol is one of the most important and highly versatile chemicals widely used in industry and in day-to-day life. This review emphasizes the recent progress of photocatalytic CO2 hydrogenation to CH3OH. In particular, Metal organic frameworks (MOFs), mixed-metal oxide, carbon, TiO2 and plasmonic-based nanomaterials are discussed for the photocatalytic reduction of CO2 to methanol. Finally, a summary and perspectives on this emerging field are provided.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010094
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 95: Coke Deposition and Structural Changes of
           Pellet V2O5/NaY-SiO2 in Air Regeneration: The Effects of Temperature on
           Regeneration

    • Authors: Chu-Chin Hsieh, Jyong-Sian Tsai, Hwo-Shuenn Sheu, Jen-Ray Chang
      First page: 95
      Abstract: V2O5/NaY-SiO2 adsorbents were prepared by soaking up vanadium oxalate precursors into pellet NaY-SiO2. The NaY-SiO2 supports were prepared from NaY-SiO2 dough followed by extrusion and calcination at 450 °C. Ethanol was used as a model adsorbate to test the performance of the adsorbents. The regeneration efficacy, defined as the ratio of the adsorption capacity of a regenerated adsorbent to that of the fresh adsorbent, was investigated through the dynamics of fixed-bed adsorption (breakthrough curve). TPO, DSC, and FT-IR were used to characterize carbonaceous species on the adsorbents; meanwhile, synchrotron XRPD, XAS, and the N2 isotherm were used to characterize the zeolite, vanadia structure, and surface area, respectively. The results indicated that in low temperature (300 °C) regeneration, adsorption sites covered by alkylated aromatic coke formed during regeneration, causing adsorbent deactivation. In contrast, during regeneration at a high temperature (450 °C), the deactivation was caused by the destruction of the NaY framework concomitant with channel blockage, as suggested by the BET surface area combined with Rietvelt XRPD refinement results. In addition, the appearance of V-O-V contribution in the EXAFS spectra indicated the aggregation of isolated VO4, which led to a decrease in the combustion rate of the carbonaceous species deposited on the adsorbents. For regeneration at 350 and 400 °C, only trace coke formation and minor structural destruction were observed. Long-term life tests indicated that regeneration at 400 °C presents a higher maintenance of stability.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010095
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 96: PdAg/C Electrocatalysts Synthesized by
           Thermal Decomposition of Polymeric Precursors Improve Catalytic Activity
           for Ethanol Oxidation Reaction

    • Authors: Yonis Fornazier Filho, Ana Caroliny Carvalho da Cruz, Rolando Pedicini, José Ricardo Cezar Salgado, Rodrigo Vieira Rodrigues, Priscilla Paiva Luz, Sergi Garcia-Segura, Josimar Ribeiro
      First page: 96
      Abstract: An efficient ethanol oxidation reaction (EOR) is required to enhance energy production in alcohol-based fuel cells. The use of bimetallic catalysts promises decreasing reliance on platinum group metal (PGM) electrocatalysts by minimizing the use of these expensive materials in the overall electrocatalyst composition. In this article, an alternative method of bimetallic electrocatalyst synthesis based on the use of polymeric precursors is explored. PdAg/C electrocatalysts were synthesized by thermal decomposition of polymeric precursors and used as the anode electrocatalyst for EOR. Different compositions, including pristine Pd/C and Ag/C, as well as bimetallic Pd80Ag20/C, and Pd60Ag40/C electrocatalysts, were evaluated. Synthesized catalysts were characterized, and electrochemical activity evaluated. X-ray diffraction showed a notable change at diffraction peak values for Pd80Ag20/C and Pd60Ag40/C electrocatalysts, suggesting alloying (solid solution) and smaller crystallite sizes for Pd60Ag40/C. In a thermogravimetric analysis, the electrocatalyst Pd60Ag40/C presented changes in the profile of the curves compared to the other electrocatalysts. In the cyclic voltammetry results for EOR in alkaline medium, Pd60Ag40/C presented a more negative onset potential, a higher current density at the oxidation peak, and a larger electrically active area. Chronoamperometry tests indicated a lower poisoning rate for Pd60Ag40/C, a fact also observed in the CO-stripping voltammetry analysis due to its low onset potential. As the best performing electrocatalyst, Pd60Ag40/C has a lower mass of Pd (a noble and expensive metal) in its composition. It can be inferred that this bimetallic composition can contribute to decreasing the amount of Pd required while increasing the fuel cell performance and expected life. PdAg-type electrocatalysts can provide an economically feasible alternative to pure PGM-electrocatalysts for use as the anode in EOR in fuel cells.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010096
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 97: Hydrogenation of Carboxyl Nitrile Butadiene
           Rubber Latex Using a Ruthenium-Based Catalyst

    • Authors: Xiaodong Liu, Yunlei Fu, Defang Zhou, Hanchu Chen, Yanyan Li, Jianhui Song, Shouyan Zhang, Hui Wang
      First page: 97
      Abstract: Hydrogenated carboxyl nitrile rubber (HXNBR) is endowed with superior mechanical performance and heat–oxygen aging resistance via emulsion hydrogenation of its precursor, i.e., carboxyl nitrile rubber (XNBR). Herein, a ruthenium-based catalyst was prepared to achieve the direct catalytic hydrogenation of XNBR latex. The effects of a series of hydrogenation conditions, such as catalyst dosage, solid content and reaction temperature, as well as the hydrogen pressure, on the hydrogenation reaction were investigated in detail. We found that the hydrogenation rate fell upon increasing the solid content of the XNBR latex, with an XNBR conversion rate of 95.01 mol% in 7 h with 11.25 wt% solid content. As the reaction temperature was increased, the hydrogenation rate first increased and then decreased. The fastest reaction hydrogenation rate was reached at 140 °C, with an XNBR conversion of 95.10 mol% in 5 h. The hydrogenation rate was positively related with the hydrogen pressure employed in the reactor. In view of the safety and cost, a pressure rate of 1300 psi was considered optimal. Similarly, the hydrogenation rate can also be enhanced by adding more catalyst. When 0.05 wt% catalyst was added, the fastest hydrogenation rate was achieved. In summary, the following optimum hydrogenation conditions were determined by using a synthesized ruthenium-based catalyst: 11.25 wt% solid content of XNBR latex, 140 °C of reaction temperature, 1300 psi of hydrogen pressure and 0.05 wt% catalyst. The vulcanization, mechanical performance, aging resistance and oil resistance of the produced HXNBR under the above reaction conditions were systematically investigated.
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010097
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 98: A Model of Catalytic Cracking: Catalyst
           Deactivation Induced by Feedstock and Process Variables

    • Authors: Galina Y. Nazarova, Elena N. Ivashkina, Emiliya D. Ivanchina, Maria Y. Mezhova
      First page: 98
      Abstract: Changes in the quality of the feedstocks generated by involving various petroleum fractions in catalytic cracking significantly affect catalyst deactivation, which stems from coke formed on the catalyst surface. By conducting experimental studies on feedstocks and catalysts, as well as using industrial data, we studied how the content of saturates, aromatics and resins (SAR) in feedstock and the main process variables, including temperature, consumptions of the feedstock, catalyst and slops, influence the formation of catalytic coke. We also determined catalyst deactivation patterns using TG-DTA, N2 adsorption and TPD, which were further used as a basis for a kinetic model of catalytic cracking. This model helps predict the changes in reactions rates caused by coke formation and, also, evaluates quantitatively how group characteristics of the feedstock, the catalyst-to-oil ratio and slop flow influence the coke content on the catalyst and the degree of catalyst deactivation. We defined that a total loss of acidity changes from 8.6 to 30.4 wt% for spent catalysts, and this depends on SAR content in feedstock and process variables. The results show that despite enriching the feedstock by saturates, the highest coke yields (4.6–5.2 wt%) may be produced due to the high content of resins (2.1–3.5 wt%).
      Citation: Catalysts
      PubDate: 2022-01-14
      DOI: 10.3390/catal12010098
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 99: Fabrication and Characterization of a Marine
           Wet Solar Cell with Titanium Dioxide and Copper Oxides Electrodes

    • Authors: Htoo Nay Wunn, Shinichi Motoda, Motoaki Morita
      First page: 99
      Abstract: One of the effective ways of utilizing marine environments is to generate energy, power, and hydrogen via the effect of photocatalysts in the seawater. Since the ocean is vast, we are able to use its large area, but the power generation system must be of low cost and have high durability against both force and corrosion. In order to meet those requirements, this study focuses on the fabrication of a novel marine wet solar cell composed of a titanium dioxide photoanode and a copper oxide photocathode. These electrodes were deposited on type 329J4L stainless steel, which possesses relative durability in marine environments. This study focuses on the characterization of the photocatalytic properties of electrodes in seawater. Low-cost manufacturing processes of screen-printing and vacuum vapor deposition were applied to produce the titanium dioxide and copper oxides electrodes, respectively. We investigated the photopotential of the electrodes, along with the electrochemical properties and cell voltage properties of the cell. X-ray diffraction spectroscopy (XRD) of the copper oxides electrode was analyzed in association with the loss of photocatalytic effect in the copper oxides electrode. Although the conversion efficiency of the wet cell was less than 1%, it showed promising potential for use in marine environments with low-cost production. Electrochemical impedance spectroscopy (EIS) of the cell was also conducted, from which impedance values regarding the electrical properties of electrodes and their interfaces of charge-transfer processes were obtained. This study focuses on the early phase of the marine wet solar cell, which should be further studied for long-term stability and in actual marine environmental applications.
      Citation: Catalysts
      PubDate: 2022-01-15
      DOI: 10.3390/catal12010099
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 100: Thermal Stability of Potassium-Promoted
           Cobalt Molybdenum Nitride Catalysts for Ammonia Synthesis

    • Authors: Paweł Adamski, Wojciech Czerwonko, Dariusz Moszyński
      First page: 100
      Abstract: The application of cobalt molybdenum nitrides as ammonia synthesis catalysts requires further development of the optimal promoter system, which enhances not only the activity but also the stability of the catalysts. To do so, elucidating the influence of the addition of alkali metals on the structural properties of the catalysts is essential. In this study, potassium-promoted cobalt molybdenum nitrides were synthesized by impregnation of the precursor CoMoO4·3/4H2O with aqueous KNO3 solution followed by ammonolysis. The catalysts were characterized with the use of XRD and BET methods, under two conditions: as obtained and after the thermal stability test. The catalytic activity in the synthesis of ammonia was examined at 450 °C, under 10 MPa. The thermal stability test was carried out by heating at 650 °C in the same apparatus. As a result of ammonolysis, mixtures of two phases: Co3Mo3N and Co2Mo3N were obtained. The phase concentrations were affected by potassium admixture. The catalytical activity increased for the most active catalyst by approximately 50% compared to non-promoted cobalt molybdenum nitrides. The thermal stability test resulted in a loss of activity, on average, of 30%. Deactivation was caused by the collapse of the porous structure, which is attributed to the conversion of the Co2Mo3N phase to the Co3Mo3N phase.
      Citation: Catalysts
      PubDate: 2022-01-16
      DOI: 10.3390/catal12010100
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 101: Horizons in Asymmetric Organocatalysis: En
           Route to the Sustainability and New Applications

    • Authors: Sandra Ardevines, Eugenia Marqués-López, Raquel P. Herrera
      First page: 101
      Abstract: Nowadays, the development of new enantioselective processes is highly relevant in chemistry due to the relevance of chiral compounds in biomedicine (mainly drugs) and in other fields, such as agrochemistry, animal feed, and flavorings. Among them, organocatalytic methods have become an efficient and sustainable alternative since List and MacMillan pioneering contributions were published in 2000. These works established the term asymmetric organocatalysis to label this area of research, which has grown exponentially over the last two decades. Since then, the scientific community has attended to the discovery of a plethora of organic reactions and transformations carried out with excellent results in terms of both reactivity and enantioselectivity. Looking back to earlier times, we can find in the literature a few examples where small organic molecules and some natural products could act as effective catalysts. However, with the birth of this type of catalysis, new chemical architectures based on amines, thioureas, squaramides, cinchona alkaloids, quaternary ammonium salts, carbenes, guanidines and phosphoric acids, among many others, have been developed. These organocatalysts have provided a broad range of activation modes that allow privileged interactions between catalysts and substrates for the preparation of compounds with high added value in an enantioselective way. Here, we briefly cover the history of this chemistry, from our point of view, including our beginnings, how the field has evolved during these years of research, and the road ahead.
      Citation: Catalysts
      PubDate: 2022-01-16
      DOI: 10.3390/catal12010101
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 102: Island-Type Hybrid Catalysts Applied for
           Anion Exchange Membrane Water Electrolysis

    • Authors: Hsueh-Yu Chen, Guan-Cheng Chen, Kuo-Wei Liao, Wen-Hui Wei, Hsin-Chih Huang, Chen-Hao Wang
      First page: 102
      Abstract: A rapid, productive, and efficient process was invented to produce hybrid catalysts for transition metal oxide water electrolysis. The microwave-assisted hydrothermal method was applied to synthesize transition metal oxide catalysts by controlling the amount of cobalt and iron. This work solves the cracking problem for the catalytic layer during the water electrolysis. It uses Fe2O3 as the support and covers a catalytic layer outside it and a nanoscale gap between each catalyst, which can help to remove the gas and fill up the water. The unique structure of the catalysts can prevent them from accumulating gas and increasing their efficiency for long-term water electrolysis. By using unique catalysts in the water electrolyzer, the current density reaches higher than 200 mA cm−2 at 2.0 V and does not show a significant decay even after 200 h.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010102
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 103: Advanced Treatment of Phosphorus Pesticide
           Wastewater Using an Integrated Process of Coagulation and Ozone Catalytic
           Oxidation

    • Authors: Shengping Cao, Lei Chen, Minyan Zhao, Ankang Liu, Mingxiu Wang, Yongjun Sun
      First page: 103
      Abstract: Conventional pretreatment and secondary biochemical treatment are ineffective methods for removing phosphorus from phosphorus-containing pesticide wastewater. In this study, coagulation-coupled ozone catalytic oxidation was used to treat secondary biochemical tailwater of phosphorus-containing pesticide wastewater thoroughly. The effects of the coagulant type, coagulant dosage, coagulant concentration, wastewater pH, stirring rate, and stirring time on the removal efficiency of chemical oxygen demand (COD), total phosphorus (TP), and chromaticity were investigated during coagulation. When the dosage of the coagulant PAFS was equal to 100 mg/L, the concentration of the coagulant, pH, stirring rate, and stirring time were 5 wt%, 8, 100 rpm, and 5 min, respectively, and the removal rates of COD, TP, and chroma in wastewater reached the maximum value of 17.6%, 86.8%, and 50.0%, respectively. Effluent after coagulation was treated via ozone catalytic oxidation. When the respective ozone dosage, H2O2 dosage, catalyst dosage, and reaction time were 120 mg/L, 0.1 vt‰, 10 wt%, and 90 min, residual COD and chromaticity of the final effluent were 10.3 mg/L and 8, respectively. The coagulation-coupled ozone catalytic oxidation process has good application prospects in the treatment of secondary biochemical tailwater from phosphorus-containing pesticide wastewater.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010103
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 104: Catalytic Conversion of Glycerol to Methyl
           Lactate over Au-CuO/Sn-Beta: The Roles of Sn-Beta

    • Authors: Ying Duan, Qianqian Luo, Renfeng Nie, Jianshe Wang, Yongsheng Zhang, Tianliang Lu, Chunbao Xu
      First page: 104
      Abstract: The production of methyl lactate as a degradable polymer monomer from biomass was an important topic for a sustainable society. In this manuscript, glycerol was oxidated to methyl lactate catalyzed by the combination of Au-CuO and Sn-Beta. The influence of Sn content, Sn source, and the preparation conditions for Sn-β was studied. The Au content in Au/CuO was also investigated by varying the Au content in Au/CuO. The catalysts were characterized by XRD, FTIR spectroscopy of pyridine adsorption, and TEM to study the role of Sn and the influence of different parameters for catalyst preparation. After the optimization of reaction parameters, the yield of methyl lactate from glycerol reached 59% at 363 K after reacting in 1.6 MPa of O2 for 6 h.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010104
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 105: Bimetallic Co-Rh Systems as a Prospective
           Base for Design of CH4 Reforming Catalysts to Produce Syngas with a
           Controllable Composition

    • Authors: Sholpan S. Itkulova, Kirill A. Valishevskiy, Yerzhan A. Boleubayev
      First page: 105
      Abstract: Dry and bireforming (CO2-H2O) of methane are the most environmentally friendly routes involving two main greenhouse gases to produce syngas—an important building block for large-scale production of various commodity chemicals. The main drawback preventing their industrial application is the coke formation. Developing catalysts that do not favour or are resistant to coke formation is the only way to improve the catalyst stability. Designing an economically viable catalyst may be achieved by exploiting the synergic effects of combining noble (expensive but coke-resistant) and non-noble (cheap but prone to carbonisation) metals to form highly effective catalysts. This work deals with development of highly active and stable bimetallic Co-containing catalysts modified with small amount of Rh, 0.1–0.5 mass %. The catalysts were characterised by BET, XRD, TEM, SEM, XPS, and TPR-H2 methods and tested in dry, bi-, and for comparison in steam reforming of methane. It was revealed that the bimetallic Co-Rh systems is much more effective than monometallic ones due to Co-Rh interaction accompanied with increasing dispersion and reducibility of Co. The extents of CH4 and CO2 conversion over the 5%Co-Rh/Al2O3 are varied within 85–99%. Syngas with variable H2/CO = 0.9–3.9 was formed. No loss of activity was observed for 100 h of long-term stability test.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010105
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 106: Synthesis of Indoles by Palladium-Catalyzed
           Reductive Cyclization of β-Nitrostyrenes with Phenyl Formate as a CO
           Surrogate

    • Authors: Francesco Ferretti, Manar Ahmed Fouad, Fabio Ragaini
      First page: 106
      Abstract: The reductive cyclization of suitably substituted organic nitro compounds by carbon monoxide is a very appealing technique for the synthesis of heterocycles because of its atom efficiency and easiness of separation of the only stoichiometric byproduct CO2, but the need for pressurized CO has hampered its diffusion. We have recently reported on the synthesis of indoles by reductive cyclization of o-nitrostyrenes using phenyl formate as a CO surrogate, using a palladium/1,10-phenanthroline complex as catalyst. However, depending on the desired substituents on the structure, the use of β-nitrostyrenes as alternative reagents may be advantageous. We report here the results of our study on the possibility to use phenyl formate as a CO surrogate in the synthesis of indoles by reductive cyclization of β-nitrostyrenes, using PdCl2(CH3CN)2 + phenanthroline as the catalyst. It turned out that good results can be obtained when the starting nitrostyrene bears an aryl substituent in the alpha position. However, when no such substituent is present, only fair yield of indole can be obtained because the base required to decompose the formate also catalyzes an oligo-polymerization of the starting styrene. The reaction can be performed in a single glass pressure tube, a cheap and easily available piece of equipment.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010106
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 107: Recent Advances in the Application of
           Enzyme Processing Assisted by Ultrasound in Agri-Foods: A Review

    • Authors: Andrés Córdova, Paola Henríquez, Helena Nuñez, Fabián Rico-Rodriguez, Cecilia Guerrero, Carolina Astudillo-Castro, Andrés Illanes
      First page: 107
      Abstract: The intensification of processes is essential for the sustainability of the biorefinery concept. Enzyme catalysis assisted by ultrasound (US) may offer interesting opportunities in the agri-food sector because the cavitation effect provided by this technology has been shown to improve the efficiency of the biocatalysts. This review presents the recent advances in this field, focused on three main applications: ultrasound-assisted enzymatic extractions (UAEE), US hydrolysis reactions, and synthesis reactions assisted by US for the manufacturing of agri-food produce and ingredients, enabling the upgrading of agro-industrial waste. Some theoretical and experimental aspects of US that must be considered are also reviewed. Ultrasonic intensity (UI) is the main parameter affecting the catalytic activity of enzymes, but a lack of standardization for its quantification makes it unsuitable to properly compare results. Applications of enzyme catalysis assisted by US in agri-foods have been mostly concentrated in UAEE of bioactive compounds. In second place, US hydrolysis reactions have been applied for juice and beverage manufacturing, with some interesting applications for producing bioactive peptides. In last place, a few efforts have been performed regarding synthesis reactions, mainly through trans and esterification to produce structured lipids and sugar esters, while incipient applications for the synthesis of oligosaccharides show promising results. In most cases, US has improved the reaction yield, but much information is lacking on how different sonication conditions affect kinetic parameters. Future research should be performed under a multidisciplinary approach for better comprehension of a very complex phenomenon that occurs in very short time periods.
      Citation: Catalysts
      PubDate: 2022-01-17
      DOI: 10.3390/catal12010107
      Issue No: Vol. 12, No. 1 (2022)
       
  • Catalysts, Vol. 12, Pages 40: Sulfide-Based Photocatalysts Using Visible
           Light, with Special Focus on In2S3, SnS2 and ZnIn2S4

    • Authors: José C. Conesa
      First page: 40
      Abstract: Sulfides are frequently used as photocatalysts, since they absorb visible light better than many oxides. They have the disadvantage of being more easily photocorroded. This occurs mostly in oxidizing conditions; therefore, they are commonly used instead in reduction processes, such as CO2 reduction to fuels or H2 production. Here a summary will be presented of a number of sulfides used in several photocatalytic processes; where appropriate, some recent reviews will be presented of their behaviour. Results obtained in recent years by our group using some octahedral sulfides will be shown, showing how to determine their wavelength-dependent photocatalytic activities, checking their mechanisms in some cases, and verifying how they can be modified to extend their wavelength range of activity. It will be shown here as well how using photocatalytic or photoelectrochemical setups, by combining some enzymes with these sulfides, allows achieving the photo-splitting of water into H2 and O2, thus constituting a scheme of artificial photosynthesis.
      Citation: Catalysts
      PubDate: 2021-12-30
      DOI: 10.3390/catal12010040
      Issue No: Vol. 12, No. 1 (2021)
       
  • Catalysts, Vol. 12, Pages 41: Investigation of Photocatalysis by
           Mesoporous Titanium Dioxide Supported on Glass Fibers as an Integrated
           Technology for Water Remediation

    • Authors: Cristina De Ceglie, Sudipto Pal, Sapia Murgolo, Antonio Licciulli, Giuseppe Mascolo
      First page: 41
      Abstract: The photocatalytic efficiency of an innovative UV-light catalyst consisting of a mesoporous TiO2 coating on glass fibers was investigated for the degradation of pharmaceuticals (PhACs) in wastewater effluents. Photocatalytic activity of the synthesized material was tested, for the first time, on a secondary wastewater effluent spiked with nine PhACs and the results were compared with the photolysis used as a benchmark treatment. Replicate experiments were performed in a flow reactor equipped with a UV radiation source emitting at 254 nm. Interestingly, the novel photocatalyst led to the increase of the degradation of carbamazepine and trimethoprim (about 2.2 times faster than the photolysis). Several transformation products (TPs) resulting from both the spiked PhACs and the compounds naturally occurring in the secondary wastewater effluent were identified through UPLC-QTOF/MS/MS. Some of them, produced mainly from carbamazepine and trimethoprim, were still present at the end of the photolytic treatment, while they were completely or partially removed by the photocatalytic treatment.
      Citation: Catalysts
      PubDate: 2021-12-31
      DOI: 10.3390/catal12010041
      Issue No: Vol. 12, No. 1 (2021)
       
  • Catalysts, Vol. 12, Pages 42: Catalytic Synthesis of Methacrolein via the
           Condensation of Formaldehyde and Propionaldehyde with L-Proline
           Intercalated Layered Double Hydroxides

    • Authors: Longxin Ju, Gang Li, Hongxian Luo
      First page: 42
      Abstract: Aldol condensation reactions are very important C–C coupling reactions in organic chemistry. In this study, the catalytic performance of layered double hydroxides (LDHs) in the aldol condensation reaction of formaldehyde (FA) and propionaldehyde (PA) was investigated. The MxAl-LDHs (denoted as re-MxAl–LDHs; M = Ca and Mg; X = 2–4), as heterogeneous basic catalysts toward the aldol condensation reaction, were prepared via a two-step procedure. The catalyst exhibited a high PA conversion (82.59%), but the methacrolein (MAL) selectivity was only 36.01% due to the limitation of the alkali-catalyzed mechanism. On this basis, the direct intercalation of L-proline into LDHs also has been investigated. The influences of several operating conditions, including the temperature, reaction time, and substrate content, on the reaction results were systematically studied, and the optimized reaction conditions were obtained. The optimized Mg3Al–Pro-LDHs catalyst exhibited a much higher MAL selectivity than those of re-MgxAl–LDHs.
      Citation: Catalysts
      PubDate: 2021-12-31
      DOI: 10.3390/catal12010042
      Issue No: Vol. 12, No. 1 (2021)
       
  • Catalysts, Vol. 12, Pages 43: PtAu Nanoparticles Supported by Reduced
           Graphene Oxide as a Highly Active Catalyst for Hydrogen Evolution

    • Authors: Lazar Rakočević, Ivana Stojković Simatović, Aleksandar Maksić, Vladimir Rajić, Svetlana Štrbac, Irina Srejić
      First page: 43
      Abstract: PtAu nanoparticles spontaneously deposited on graphene support, PtAu/rGO, have shown remarkably high catalytic activity for hydrogen evolution reaction (HER) in sulfuric acid solution. SEM images of the PtAu/rGO electrode surface showed that Pt nanoparticles that are non-uniform in size occupy both the edges of previously deposited uniform Au nanoparticles and the edges of graphene support. XPS analysis showed that the atomic percentages of Au and Pt in PtAu/rGO were 0.6% and 0.3%, respectively. The atomic percentage of Au alone on previously prepared Au/rGO was 0.7%. Outstanding HER activity was achieved for the PtAu/rGO electrode, showing the initial potential close to the equilibrium potential for HER and a low Tafel slope of −38 mV/dec. This was confirmed by electrochemical impedance spectroscopy. The chronoamperometric measurement performed for 40 min for hydrogen evolution at a constant potential indicated good stability and durability of the PtAu/rGO electrode.
      Citation: Catalysts
      PubDate: 2021-12-31
      DOI: 10.3390/catal12010043
      Issue No: Vol. 12, No. 1 (2021)
       
  • Catalysts, Vol. 12, Pages 44: Cerium d-Block Element (Co, Ni) Bimetallic
           Oxides as Catalysts for the Methanation of CO2: Effect of Pressure

    • Authors: Joaquim Miguel Badalo Branco, Ana Cristina Ferreira, Joana Filipa Martinho
      First page: 44
      Abstract: Nickel– and cobalt–cerium bimetallic oxides were used as catalysts for the methanation of CO2 under pressure. The catalysts’ activity increases with pressure and an increase of just 10 bar is enough to double the yield of methane and to significantly improve the selectivity. The best results were those obtained over nickel–cerium bimetallic oxides, but the effect of pressure was particularly relevant over cobalt–cerium bimetallic oxides, which yield to methane increases from almost zero at atmospheric pressure to 50–60% at 30 bar. Both catalyst types are remarkably competitive, especially those containing nickel, which were always more active than a commercial rhodium catalyst used as a reference (5wt.% Rh/Al2O3) and tested under the same conditions. For the cobalt–cerium bimetallic oxides, the existence of a synergetic interaction between Co and CoO and the formation of cobalt carbides seems to play an important role in their catalytic behavior. Correlation between experimental reaction rates and simulated data confirms that the catalysts’ behavior follows the Langmuir–Hinshelwood–Hougen–Watson kinetic model, but Le Chatelier’s principle is also important to understand the catalysts’ behavior under pressure. A catalyst recycle study was also performed. The results obtained after five cycles using a nickel–cerium catalyst show insignificant variations in activity and selectivity, which are important for any type of practical application.
      Citation: Catalysts
      PubDate: 2021-12-31
      DOI: 10.3390/catal12010044
      Issue No: Vol. 12, No. 1 (2021)
       
  • Catalysts, Vol. 12, Pages 45: Heterogeneous Gold Nanoparticle-Based
           Catalysts for the Synthesis of Click-Derived Triazoles via the
           Azide-Alkyne Cycloaddition Reaction

    • Authors: Ivy L. Librando, Abdallah G. Mahmoud, Sónia A. C. Carabineiro, M. Fátima C. Guedes da Silva, Francisco J. Maldonado-Hódar, Carlos F. G. C. Geraldes, Armando J. L. Pombeiro
      First page: 45
      Abstract: A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC reaction, additional robust catalytic systems complementary to the copper catalyzed AAC remain in high demand. Herein, Au nanoparticles supported on Al2O3, Fe2O3, TiO2 and ZnO, along with gold reference catalysts (gold on carbon and gold on titania supplied by the World Gold Council) were used as catalysts for the AAC reaction. The supported Au nanoparticles with metal loadings of 0.7–1.6% (w/w relative to support) were able to selectively obtain 1,4-disubstituted-1,2,3-triazoles in moderate yields up to 79% after 15 min, under microwave irradiation at 150 °C using a 0.5–1.0 mol% catalyst loading through a one-pot three-component (terminal alkyne, organohalide and sodium azide) procedure according to the “click” rules. Among the supported Au catalysts, Au/TiO2 gave the best results.
      Citation: Catalysts
      PubDate: 2021-12-31
      DOI: 10.3390/catal12010045
      Issue No: Vol. 12, No. 1 (2021)
       
 
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