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  Subjects -> CHEMISTRY (Total: 845 journals)
    - ANALYTICAL CHEMISTRY (51 journals)
    - CHEMISTRY (595 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (25 journals)
    - INORGANIC CHEMISTRY (41 journals)
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CHEMISTRY (595 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 8)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 34)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 18)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 24)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 246)
ACS Photonics     Full-text available via subscription   (Followers: 11)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 56)
Advances in Chemical Science     Open Access   (Followers: 13)
Advances in Chemistry     Open Access   (Followers: 15)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 21)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 2)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 67)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 27)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 14)
Analyst     Full-text available via subscription   (Followers: 40)
Angewandte Chemie     Hybrid Journal   (Followers: 199)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 218)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
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: 15)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 23)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 310)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 19)
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: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 118)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 91)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
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: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 3)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 4)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 66)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 8)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 14)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 72)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 24)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 20)
Chemical Reviews     Full-text available via subscription   (Followers: 181)
Chemical Science     Open Access   (Followers: 22)
Chemical Technology     Open Access   (Followers: 16)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 58)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 26)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 146)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 255)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 9)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 10)
Chromatographia     Hybrid Journal   (Followers: 24)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 10)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 18)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 17)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 61)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecotoxicology and Environmental Contamination     Open Access  
Educación Química     Open Access   (Followers: 1)
Education for Chemical Engineers     Hybrid Journal   (Followers: 5)
EJNMMI Radiopharmacy and Chemistry     Open Access  
Elements     Full-text available via subscription   (Followers: 3)
Environmental Chemistry     Hybrid Journal   (Followers: 7)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)

        1 2 3 | Last

Journal Cover Catalysts
  [SJR: 1.123]   [H-I: 14]   [8 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2073-4344
   Published by MDPI Homepage  [156 journals]
  • Catalysts, Vol. 7, Pages 247: Fabrication of Crumpled Ball-Like Nickel
           Doped Palladium-Iron Oxide Hybrid Nanoparticles with Controlled Morphology
           as Effective Catalyst for Suzuki–Miyaura Coupling Reaction

    • Authors: Seongwan Jang, Taewoo Kim, Kang Park
      First page: 247
      Abstract: We report a facile synthetic strategy for nickel-doped palladium-iron oxide hybrid nanoparticles with controllable morphology. In this synthetic method, the morphology of the nanoparticles was regulated by the amount of triphenylphosphine used. When 1 mmol of triphenylphosphine was used as a capping agent, the main morphology of the nanoparticles was crumpled balls composed of nanosheets with an average particle size of 215 nm. The nanoparticles showed higher catalytic activity in the Suzuki–Miyaura coupling reaction than did other nanoparticles at equal amounts of Pd. This strategy allowed the reduction of the Pd loading in hybrid nanoparticles while still providing the performance level required for the reaction.
      Citation: Catalysts
      PubDate: 2017-08-24
      DOI: 10.3390/catal7090247
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 248: A Zero-Power, Low-Cost Ultraviolet-C
           Colorimetric Sensor Using a Gallium Oxide and Reduced Graphene Oxide
           Hybrid via Photoelectrochemical Reactions

    • Authors: Seungdu Kim, Kook Han, In Lee, Yeojoon Yoon, Won Park, Suck Hong, Woo Yang, Wan Hwang
      First page: 248
      Abstract: A zero-power, low-cost ultraviolet (UV)-C colorimetric sensor is demonstrated using a gallium oxide and reduced graphene oxide (rGO) hybrid via photoelectrochemical reactions. A wide bandgap semiconductor (WBS) such as gallium oxide with an energy bandgap of 4.9 eV generates electron-hole pairs (EHPs) when exposed under a mercury lamp emitting 254 nm. While the conventional UVC sensors employing WBS convert the generated EHPs into an electrical signal via a solid-state junction device (SSD), our newly proposed UVC sensory system works by converting EHPs into an electrochemical reaction. The electrochemical reaction causes the degradation of a cationic thiazine redox dye, methylene blue (MB) and thereby spontaneously changes its color. As more rGO was hybridized with the gallium oxide, MB degradation was effectively expedited. Thus, the level of MB degradation under UVC can be evaluated as a UVC indicator. Unlike conventional SSD-based UVC sensors, our responsive colorimetric sensor can be applied where needed inexpensively and zero power.
      Citation: Catalysts
      PubDate: 2017-08-24
      DOI: 10.3390/catal7090248
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 249: Cross-Aldol Condensation of Acetone and
           n-Butanol into Aliphatic Ketones over Supported Cu Catalysts on
           Ceria-Zirconia

    • Authors: Minseok Kim, Jongha Park, Hari Prasad Reddy Kannapu, Young-Woong Suh
      First page: 249
      Abstract: A long-chain hydrocarbon biofuel of jet fuel range can be produced via aldol condensation of fermented products such as acetone and alcohols over the catalysts containing both metallic sites for the dehydrogenation of alcohols and basic sites for the condensation reaction. However, an efficient catalyst system has not been studied widely yet the route is promising for biofuel production. In this work, Cu catalysts supported on ceria-zirconia (Cu/xCeZr) were prepared using coprecipitated CexZr1-xO2 supports with different Ce/Zr ratios for the cross-aldol condensation of acetone and n-butanol into mono- and di-alkylated aliphatic ketones, 2-heptanone and 6-undecanone. The acetone conversion and 6-undecanone selectivity increased with specific Cu surface area due to formation of the dehydrogenation product butyraldehyde at a higher concentration. The total yield of cross-aldol condensation products was strongly dependent on a combination of Cu sites and basic sites. This was confirmed by the results in the reaction between acetone and butyraldehyde over supported Cu catalysts that additionally examined the adsorbed acyl species on Cu surface taking part in the aldol condensation reaction. The best catalytic performance was achieved with Cu/0.8CeZr showing the largest Cu surface and the highest base site density among Cu/xCeZr catalysts. While the activity of Cu/0.8CeZ was comparable to or a little higher than that of Cu/MgO, the former catalyst was more stable than the latter suffering from the transformation of MgO to Mg(OH)2 by the reaction. Consequently, it is suggested that Cu supported on ceria-zirconia of ceria rich contains such a dual function that it can efficiently catalyze the cross-aldol condensation of acetone and n-butanol.
      Citation: Catalysts
      PubDate: 2017-08-24
      DOI: 10.3390/catal7090249
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 250: Exploiting the Versatility of Aminated
           Supports Activated with Glutaraldehyde to Immobilize β-galactosidase from
           Aspergillus oryzae

    • Authors: Hadjer Zaak, Sara Peirce, Tiago de Albuquerque, Mohamed Sassi, Roberto Fernandez-Lafuente
      First page: 250
      Abstract: The enzyme β-galactosidase from Aspergillus oryzae has been immobilized in aminated (MANAE)-agarose beads via glutaraldehyde chemistry using different strategies. The immobilization on MANAE-supports was first assayed at different pH values (this gave different stabilities to the immobilized enzymes) and further modified with glutaraldehyde. Dramatic drops in activity were found, even using 0.1% (v/v) glutaraldehyde. The use of a support with lower activation permitted to get a final activity of 30%, but stability was almost identical to that of the just adsorbed enzyme. Next, the immobilization on pre-activated glutaraldehyde beads was assayed at pH 5, 7 and 9. At pH 7, full, rapid immobilization and a high expressed enzyme activity were accomplished. At pH 9, some decrease in enzyme activity was observed. Direct covalent immobilization of the enzyme was very slow; even reducing the volume of enzyme/support ratio, the yield was not complete after 24 h. The stability of the biocatalyst using pre-activated supports was about 4–6 folds more stable than that of the enzyme immobilized via ion exchange at pH 5, with small differences among them. Thus, the immobilization of the enzyme at pH 7 at low ionic strength on pre-activated glutaraldehyde supports seems to be the most adequate in terms of activity, stability and immobilization rate.
      Citation: Catalysts
      PubDate: 2017-08-25
      DOI: 10.3390/catal7090250
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 251: The Kinetic Resolution of Racemic Amines
           Using a Whole-Cell Biocatalyst Co-Expressing Amine Dehydrogenase and NADH
           Oxidase

    • Authors: Hyunwoo Jeon, Sanghan Yoon, Md Ahsan, Sihyong Sung, Geon-Hee Kim, Uthayasuriya Sundaramoorthy, Seung-Keun Rhee, Hyungdon Yun
      First page: 251
      Abstract: Amine dehydrogenase (AmDH) possesses tremendous potential for the synthesis of chiral amines because AmDH catalyzes the asymmetric reductive amination of ketone with high enatioselectivity. Although a reductive application of AmDH is favored in practice, the oxidative route is interesting as well for the preparation of chiral amines. Here, the kinetic resolution of racemic amines using AmDH was first extensively studied, and the AmDH reaction was combined with an NADH oxidase (Nox) to regenerate NAD+ and to drive the reaction forward. When the kinetic resolution was carried out with 10 mM rac-2-aminoheptane and 5 mM rac-α-methylbenzylamine (α-MBA) using purified enzymes, the enantiomeric excess (ee) values were less than 26% due to the product inhibition of AmDH by ketone and the inhibition of Nox by the substrate amine. The use of a whole-cell biocatalyst co-expressing AmDH and Nox apparently reduces the substrate and product inhibition, and/or it increases the stability of the enzymes. Fifty millimoles (50 mM) rac-2-aminoheptane and 20 mM rac-α-MBA were successfully resolved into the (S)-form with >99% ee using whole cells. The present study demonstrates the potential of a whole-cell biocatalyst co-expressing AmDH and Nox for the kinetic resolution of racemic amines.
      Citation: Catalysts
      PubDate: 2017-08-25
      DOI: 10.3390/catal7090251
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 252: SnSx (x = 1, 2) Nanocrystals as Effective
           Catalysts for Photoelectrochemical Water Splitting

    • Authors: Po-Chia Huang, Yu-Min Shen, Sanjaya Brahma, Muhammad Omar Shaikh, Jow-Lay Huang, Sheng-Chang Wang
      First page: 252
      Abstract: Two-dimensional SnSx (x = 1, 2) nanocrystals are attractive catalysts for photoelectrochemical water splitting as their components are earth abundant and environmentally friendly. We have fabricated SnS thin-film photoelectrodes by spin coating mixed-phase SnS nanocrystals synthesized via a hot-injection technique on glass/Cr/Au substrates. The obtained SnS thin films can be transformed into SnS2 by introducing structural phase changes via a facile low-vacuum annealing protocol in the presence of sulfur. This sulfurization process enables the insertion of sulfur atoms between layers of SnS and results in the generation of shallow donors that alter the mechanism for water splitting. The SnS2 thin films are used as stable photocatalysts to drive the oxygen evolution reaction, and the light-current density of 0.195 mA/cm2 at 0.8 V vs. Ag/AgCl can be achieved due to the high carrier density, lower charge transfer resistance, and a suitable reaction band position. Based on a combination of UV-Vis spectroscopy (ultraviolet and visible spectroscopy), cyclic voltammetry and Mott–Schottky analysis, the band positions and band gaps of SnS and SnS2 relative to the electrolyte are determined and a detailed mechanism for water splitting is presented. Our results demonstrate the potential of layered tin sulfide compounds as promising photocatalysts for efficient and large-scale water splitting.
      Citation: Catalysts
      PubDate: 2017-08-25
      DOI: 10.3390/catal7090252
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 253: Nano-Array Integrated Structured Catalysts:
           A New Paradigm upon Conventional Wash-Coated Monolithic Catalysts'

    • Authors: Junfei Weng, Xingxu Lu, Pu-Xian Gao
      First page: 253
      Abstract: The monolithic catalyst, namely the structured catalyst, is one of the important categories of catalysts used in various fields, especially in catalytic exhaust after-treatment. Despite its successful application in conventional wash-coated catalysts in both mobile and stationary catalytic converters, washcoat-based technologies are facing multi-fold challenges, including: (1) high Pt-group metals (PGM) material loading being required, driving the market prices; (2) less-than ideal distribution of washcoats in typically square-shaped channels associated with pressure drop sacrifice; and (3) far from clear correlations between macroscopic washcoat structures and their catalytic performance. To tackle these challenges, the well-defined nanostructure array (nano-array)-integrated structured catalysts which we invented and developed recently have been proven to be a promising class of cost-effective and efficient devices that may complement or substitute wash-coated catalysts. This new type of structured catalysts is composed of honeycomb-structured monoliths, whose channel surfaces are grown in situ with a nano-array forest made of traditional binary transition metal oxide support such as Al2O3, CeO2, Co3O4, MnO2, TiO2, and ZnO, or newer support materials including perovskite-type ABO3 structures, for example LaMnO3, LaCoO3, LaNiO, and LaFeO3. The integration strategy parts from the traditional washcoat technique. Instead, an in situ nanomaterial assembly method is utilized, such as a hydro (solva-) thermal synthesis approach, in order to create sound structure robustness, and increase ease and complex-shaped substrate adaptability. Specifically, the critical fabrication procedures for nano-array structured catalysts include deposition of seeding layer, in situ growth of nano-array, and loading of catalytic materials. The generic methodology utilization in both the magnetic stirring batch process and continuous flow reactor synthesis offers the nano-array catalysts with great potential to be scaled up readily and cost-effectively. The tunability of the structure and catalytic performance could be achieved through morphology and geometry adjustment and guest atoms and defect manipulation, as well as composite nano-array catalyst manufacture. Excellent stabilities under various conditions were also present compared to conventional wash-coated catalysts.
      Citation: Catalysts
      PubDate: 2017-08-28
      DOI: 10.3390/catal7090253
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 254: Nature and Location of Carbonaceous Species
           in a Composite HZSM-5 Zeolite Catalyst during the Conversion of Dimethyl
           Ether into Light Olefins

    • Authors: María Ibáñez, Paula Pérez-Uriarte, Miguel Sánchez-Contador, Tomás Cordero-Lanzac, Andrés Aguayo, Javier Bilbao, Pedro Castaño
      First page: 254
      Abstract: The deactivation of a composite catalyst based on HZSM-5 zeolite (agglomerated in a matrix using boehmite as a binder) has been studied during the transformation of dimethyl ether into light olefins. The location of the trapped/retained species (on the zeolite or on the matrix) has been analyzed by comparing the properties of the fresh and deactivated catalyst after runs at different temperatures, while the nature of those species has been studied using different spectroscopic and thermogravimetric techniques. The reaction occurs on the strongest acid sites of the zeolite micropores through olefins and alkyl-benzenes as intermediates. These species also condensate into bulkier structures (polyaromatics named as coke), particularly at higher temperatures and within the meso- and macropores of the matrix. The critical roles of the matrix and water in the reaction medium have been proved: both attenuating the effect of coke deposition.
      Citation: Catalysts
      PubDate: 2017-08-30
      DOI: 10.3390/catal7090254
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 255: Continuous-Flow Monolithic Silica
           Microreactors with Arenesulphonic Acid Groups: Structure–Catalytic
           Activity Relationships

    • Authors: Agnieszka Ciemięga, Katarzyna Maresz, Janusz Malinowski, Julita Mrowiec-Białoń
      First page: 255
      Abstract: The performance of monolithic silica microreactors activated with sulphonic acid groups and a packed bed reactor with Amberlyst 15 resin were compared in the esterification of acetic acid with n-butanol. The monolithic microreactors were made of single silica rods with complex pore architecture, differing in the size of mesopores, and in particular, flow-through macropores which significantly affected the flow characteristic of the continuous system. The highest ester productivity of 105.2 mol·molH+−1·h−1 was achieved in microreactor M1 with the largest porosity, characterized by a total pore volume of 4 cm3·g−1, mesopores with 20 nm diameter, and large flow-through macropores 30–50 μm in size. The strong impact of the permeability of the monoliths on a reaction kinetics was shown.
      Citation: Catalysts
      PubDate: 2017-08-30
      DOI: 10.3390/catal7090255
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 256: Controllable and Large-Scale Synthesis of
           Carbon Nanostructures: A Review on Bamboo-Like Nanotubes

    • Authors: Zirui Jia, Kaichang Kou, Ming Qin, Hongjing Wu, Fabrizio Puleo, Leonarda Liotta
      First page: 256
      Abstract: Bamboo-like carbon nanotubes are members of the carbon nanotubes (CNTs) family, whose structure is made up of separated hollow compartments and bamboo knots. Due to the peculiar structure of the CNTs species, the growth mechanism and related features have been widely investigated. Bamboo-like carbon nanotubes are widely applied in several fields, such as sensors, adsorbents, catalysts, and lithium-ion battery electrodes materials. Different methods have been applied for the synthesis of carbon nanotubes, among them, catalytic chemical vapor deposition has been singled out as the most used procedure due to low cost with a high quality product. The present review is devoted to increasing the literature dealing with the design, synthesis, and characterization of bamboo-like carbon nanotubes grown over different catalysts. Results on the methane dry reforming reaction, hydrocarbon thermal decomposition, special chemical vapor deposition as well as other methods applied to the preparation of bamboo-like carbon nanotubes are discussed. The differences in the carbon deposits between the dry reforming reaction and other reaction methods are compared and possible formation mechanisms of bamboo-like carbon nanotubes are discussed.
      Citation: Catalysts
      PubDate: 2017-08-30
      DOI: 10.3390/catal7090256
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 257: Characterization of a Novel Nicotine
           Hydroxylase from Pseudomonas sp. ZZ-5 That Catalyzes the Conversion of
           6-Hydroxy-3-Succinoylpyridine into 2,5-Dihydroxypyridine

    • Authors: Tao Wei, Jie Zang, Yadong Zheng, Hongzhi Tang, Sheng Huang, Duobin Mao
      First page: 257
      Abstract: A novel nicotine hydroxylase was isolated from Pseudomonas sp. ZZ-5 (HSPHZZ). The sequence encoding the enzyme was 1206 nucleotides long, and encoded a protein of 401 amino acids. Recombinant HSPHZZ was functionally overexpressed in Escherichia coli BL21-Codon Plus (DE3)-RIL cells and purified to homogeneity after Ni-NTA affinity chromatography. Liquid chromatography-mass spectrometry (LC-MS) analyses indicated that the enzyme could efficiently catalyze the conversion of 6-hydroxy-3-succinoylpyridine (HSP) into 2,5-dihydroxypyridine (2,5-DHP) and succinic acid in the presence of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD). The kinetic constants (Km, kcat, and kcat/Km) of HSPHZZ toward HSP were 0.18 mM, 2.1 s−1, and 11.7 s−1 mM−1, respectively. The optimum temperature, pH, and optimum concentrations of substrate and enzyme for 2,5-DHP production were 30 °C, 8.5, 1.0 mM, and 1.0 μM, respectively. Under optimum conditions, 85.3 mg/L 2,5-DHP was produced in 40 min with a conversion of 74.9%. These results demonstrated that HSPHZZ could be used for the enzymatic production of 2,5-DHP in biotechnology applications.
      Citation: Catalysts
      PubDate: 2017-08-31
      DOI: 10.3390/catal7090257
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 258: Experimental Research of an Active Solution
           for Modeling In Situ Activating Selective Catalytic Reduction Catalyst

    • Authors: Tuo Ye, Donglin Chen, Yanshan Yin, Jing Liu, Xi Zeng
      First page: 258
      Abstract: The effect of active solutions suitable for the in situ activation of selective catalytic reduction (SCR) catalysts was experimentally investigated using a designed in situ activation modeling device. To gain further insight, scanning electron microscopy (SEM), specific surface area analysis (BET), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) analyses were used to investigate the effects of different reaction conditions on the characteristics of the deactivated catalysts. The activation effect of loading V2O5, WO3 and MoO3 on the surface of the deactivated catalysts was analyzed and the correlation to the denitrification activity was determined. The results demonstrate that the prepared activating solution of 1 wt % vanadium (V), 9 wt % tungsten (W), and 6 wt % molybdenum (Mo) has a beneficial effect on the deactivation of the catalyst. The activated catalyst resulted in a higher NO removal rate when compared to the deactivated catalyst. Furthermore, the NO removal rate of the activated catalyst reached a maximum of 32%. The activity of the SCR catalyst is closely linked to the concentration of the active ingredients. When added in optimum amounts, the active ingredients helped to restore the catalytic activity. In particular, the addition of active ingredients, the availability of labile surface oxygen, and the presence of small pores improved the denitrification efficiency. Based on these results, active solutions can effectively solve the problem of denitrification catalyst deactivation. These findings are a reference for the in-situ activation of the selective catalytic reduction of nitrogen oxides (SCR-DeNOx) catalyst.
      Citation: Catalysts
      PubDate: 2017-08-31
      DOI: 10.3390/catal7090258
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 259: The Role of Non-Framework Lewis Acidic Al
           Species of Alkali-Treated HZSM-5 in Methanol Aromatization

    • Authors: Po-Chen Lai, Chi-Ying Hsieh, Chao-Huang Chen, Yu-Chuan Lin
      First page: 259
      Abstract: Mesoporous HZSM-5 prepared by alkaline treatment (also termed desilication) has drawn significant attention due to its potential in large-scale production and in versatile applications, such as separation and catalysis. Alkali-treated HZSM-5 contains considerable amounts of non-framework (amorphous) Lewis acidic Al species on the external surface, and is deemed to be essential in affecting its catalytic performances. This study intends to clarify the catalytic nature of amorphous Al species of alkali-treated HZSM-5 in methanol aromatization. Physicochemical characterizations, including N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), magic-angle-spinning nuclear magnetic resonance (MAS NMR), inductively coupled plasma (ICP) analysis, NH3 temperature-programmed desorption (TPD), and methanol-TPD, were performed. The outcomes showed that non-framework Al promotes the hydride transfer in mesoporous HZSM-5, thereby facilitating the aromatization reaction. Among aromatic products, durene can be promoted by non-framework Al through methylation/transalkylation of other aromatics, particularly xylenes, instead of being promoted by reduced space confinement in mesoporous HZSM-5.
      Citation: Catalysts
      PubDate: 2017-09-01
      DOI: 10.3390/catal7090259
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 260: Polyoxometalate (POM)-Layered Double
           Hydroxides (LDH) Composite Materials: Design and Catalytic Applications

    • Authors: Tengfei Li, Haralampos Miras, Yu-Fei Song
      First page: 260
      Abstract: Layered double hydroxides (LDHs) are an important large class of two-dimensional (2D) anionic lamellar materials that possess flexible modular structure, facile exchangeability of inter-lamellar guest anions and uniform distribution of metal cations in the layer. Owing to the modular accessible gallery and unique inter-lamellar chemical environment, polyoxometalates (POMs) intercalated with LDHs has shown a vast array of physical properties with applications in environment, energy, catalysis, etc. Here we describe how polyoxometalate clusters can be used as building components for the construction of systems with important catalytic properties. This review article mainly focuses on the discussion of new synthetic approaches developed recently that allow the incorporation of the element of design in the construction of a fundamentally new class of materials with pre-defined functionalities in catalytic applications. Introducing the element of design and taking control over the finally observed functionality we demonstrate the unique opportunity for engineering materials with modular properties for specific catalytic applications.
      Citation: Catalysts
      PubDate: 2017-09-01
      DOI: 10.3390/catal7090260
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 261: The Beneficial Sinergy of MW Irradiation and
           Ionic Liquids in Catalysis of Organic Reactions

    • Authors: Barbara Floris, Federica Sabuzi, Pierluca Galloni, Valeria Conte
      First page: 261
      Abstract: The quest for sustainable processes is becoming more and more important, with catalysis playing a major role in improving atom economy and reducing waste. Organic syntheses with less need of protecting/de-protecting steps are highly desirable. The combination of microwave irradiation, as energy source, with ionic liquids, as both solvents and catalysts, offered interesting solutions in recent years. The literature data of the last 15 years concerning selected reactions are presented, highlighting the importance of microwave (MW) technology coupled with ionic liquids.
      Citation: Catalysts
      PubDate: 2017-09-01
      DOI: 10.3390/catal7090261
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 262: Expanding the Scope of Cu(I) Catalyzed
           “Click Chemistry” with Abnormal NHCs: Three-Fold Click to
           Tris-Triazoles

    • Authors: Nga Kim T. Ho, Sven O. Reichmann, Dennis Rottschäfer, Regine Herbst-Irmer, Rajendra S. Ghadwal
      First page: 262
      Abstract: Cationic copper(I) complexes [Cu(aIPrPh)(IPr)]I (3) and [Cu(aIPrPh)2]I (4) featuring an abnormal N-heterocyclic carbene (aNHC) (aIPrPh = 1,3-bis(2,6-diisopropylphenyl)-2-phenyl- imidazol-4-ylidene) and/or an NHC (IPr = 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) ligand(s) are reported. Treatment of Cu(aIPrPh)I (2) with IPr affords complex 3. Reaction of (IPrPh)I (1) (IPrPh = 1,3-bis(2,6-diisopropylphenyl)-2-phenyl-imidazolium) with CuI in the presence of K{N(SiMe3)2} leads to the formation of 4. Complexes 3 and 4 represent rare examples of mixed aNHC-NHC and bis-aNHC metal complexes, respectively. They are characterized by elemental analysis, NMR spectroscopic, and mass spectrometric studies. The solid-state molecular structures of 3 and 4 have been determined by single crystal X-ray diffraction analyses. The catalytic activity of 2, 3, and 4 has been investigated in the [3+2] cycloaddition of alkynes and organic azides, affording triazole derivatives in an almost quantitative yield. Notably, complexes 2, 3, and 4 are excellent catalysts for the three-fold cycloaddition of a tris-azide with various alkynes. This catalytic protocol offers a high yield access to tris-triazoles in a shorter reaction time and considerably reduces the experimental work-up compared to the classical synthetic method.
      Citation: Catalysts
      PubDate: 2017-09-01
      DOI: 10.3390/catal7090262
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 263: Regioselective Synthesis of Lactulose Esters
           by Candida antarctica and Thermomyces lanuginosus Lipases

    • Authors: Luis Chávez-Flores, Hiram Beltran, Daniel Arrieta-Baez, Dolores Reyes-Duarte
      First page: 263
      Abstract: The interest in sugar esters as emulsifiers has been increasing in recent years because they have tunable surfactant properties that depend on the chain length of the fatty acid and the type of the sugar, covering a wide range of hydrophilic-lipophilic balance (HLB). In this work, ten biocatalysts were used for the transesterification reaction screening of lactulose, a prebiotic sugar, with vinyl laurate. The reactions were followed by thin layer chromatography (TLC) analysis, identifying two major monoesters mixtures defined as monoester fraction 1 and monoester fraction 2. Candida antarctica lipase B (Novozym 435) produces “monoester fraction 1”, while Thermomyces lanuginosus lipase (Lipozyme® TL IM) and Mucor miehei lipase (Lipozyme®) seem to produce the same “monoester fraction 2”. These three enzymes were selected as model biocatalysts for a kinetic study, and monoester fractions 1 and 2 from Novozym 435 and Lipozyme® TL IM, respectively, were used for product characterization. Monoester fraction 1 contained 86.9% of the major monoester in position 1-O-, and monoester fraction 2 contained 91.4% of 6′-O-. Although these lipases acylated three positions of lactulose, they mainly synthesize a monoester presenting regioselectivity. These results contribute to the study of the chemical structure diversity of biosurfactants to enhance their applications in foods, pharmaceutical products, and cosmetics.
      Citation: Catalysts
      PubDate: 2017-09-03
      DOI: 10.3390/catal7090263
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 264: Mechanistic Insight into the 2° Alcohol
           Oxidation Mediated by an Efficient CuI/L-Proline-TEMPO Catalyst—A
           Density Functional Theory Study

    • Authors: Siyu Li, Lin Cheng, Qi Wu, Qiancheng Zhang, Jucai Yang, Juming Liu
      First page: 264
      Abstract: Density functional theory (DFT) calculations have been performed to investigate the 2° alcohol oxidation to acetophenone catalyzed by the CuI/L-Proline-2,2,6,6- tetramethylpiperidinyloxy (TEMPO) catalyst system. Seven possible pathways (paths A→F) are presented. Our calculations show that two pathways (path A and path B) are the potential mechanisms. Furthermore, by comparing with experimental observation, it is found that path A—in which substrate alcohol provides the proton to −OtBu to produce HOtBu followed by the oxidation of substrate directly to product acetophenone by O2—is favored in the absence of TEMPO. Correspondingly, path B is likely to be favored when TEMPO is involved. In path B, the O–O bond cleavage of CuI–OOH to CuII–OH species occurs, followed by acetophenone formation assisted by ligand (L)2ˉ. It is also found that the cooperation of ligand (L)2ˉ and TEMPO plays an important role in assisting the formation of the product acetophenone in path B.
      Citation: Catalysts
      PubDate: 2017-09-05
      DOI: 10.3390/catal7090264
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 265: Hydrodeoxygenation of Lignin-Derived
           Phenols: From Fundamental Studies towards Industrial Applications

    • Authors: Päivi Mäki-Arvela, Dmitry Murzin
      First page: 265
      Abstract: Hydrodeoxygenation (HDO) of bio-oils, lignin and their model compounds is summarized in this review. The main emphasis is put on elucidating the reaction network, catalyst stability and time-on-stream behavior, in order to better understand the prerequisite for industrial utilization of biomass in HDO to produce fuels and chemicals. The results have shown that more oxygenated feedstock, selection of temperature and pressure as well as presence of certain catalyst poisons or co-feed have a prominent role in the HDO of real biomass. Theoretical considerations, such as density function theory (DFT) calculations, were also considered, giving scientific background for the further development of HDO of real biomass.
      Citation: Catalysts
      PubDate: 2017-09-07
      DOI: 10.3390/catal7090265
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 266: Flower-Like Au–CuO/Bi2WO6 Microsphere
           Catalysts: Synthesis, Characterization, and Their Catalytic Performances
           for CO Oxidation

    • Authors: Lili Wang, Baolin Zhu, Shoumin Zhang, Weiping Huang
      First page: 266
      Abstract: The flower-like Bi2WO6 microsphere was synthesized through a simple hydrothermal route, and three catalysts, Au/Bi2WO6, CuO/Bi2WO6, and Au–CuO/Bi2WO6, were prepared by a deposition–precipitation method. The morphology and structure of the catalysts were characterized by X-ray powder diffraction, surface area analyzer, inductively coupled plasma optical emission spectrometer, scanning electron microscope, transmission electron microscopy, UV/Vis spectrometer, as well as X-ray photoelectron spectroscopy. Their catalytic performances in catalytic CO oxidation were evaluated. For Au/Bi2WO6 and CuO/Bi2WO6, Au and CuO nanoparticles highly dispersed on Bi2WO6 are 3 and 10 nm, respectively, in average size. For Au–CuO/Bi2WO6, a part of the Au nanoparticles (Au NPs) strongly adheres to the CuO, due to the strong interaction between Au NPs and CuO, which has a positive effect on catalytic activity of Au–CuO/Bi2WO6. Au–CuO/Bi2WO6 can convert CO into CO2 completely at 40 °C, as the contents of Au and Cu are 0.438 wt % and 4.85 wt %, respectively.
      Citation: Catalysts
      PubDate: 2017-09-11
      DOI: 10.3390/catal7090266
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 267: Heck Reaction—State of the Art

    • Authors: Sangeeta Jagtap
      First page: 267
      Abstract: The Heck reaction is one of the most studied coupling reactions and is recognized with the Nobel Prize in Chemistry. Thousands of articles, hundreds of reviews and a number of books have been published on this topic. All reviews are written exhaustively describing the various aspects of Heck reaction and refer to the work done hitherto. Looking at the quantum of the monographs published, and the reviews based on them, we found a necessity to summarize all reviews on Heck reaction about catalysts, ligands, suggested mechanisms, conditions, methodologies and the compounds formed via Heck reaction in one review and generate a resource of information. One can find almost all the catalysts used so far for Heck reaction in this review.
      Citation: Catalysts
      PubDate: 2017-09-11
      DOI: 10.3390/catal7090267
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 268: Pulse Microcalorimetry Study of Methane Dry
           Reforming Reaction on Ni/Ceria-Zirconia Catalyst

    • Authors: Mikhail Simonov, Vladimir Rogov, Marina Smirnova, Vladislav Sadykov
      First page: 268
      Abstract: For Ni/CeZrO catalyst prepared in supercritical isopropanol main features of methane dry reforming reaction mechanism were studied by the pulse microcalorimetric technique. The reaction scheme is described by a step-wise redox mechanism with independent stages of CH4 transformation on Ni/support interface producing syngas with participation of support oxygen bridging species (the rate-limiting stage) and fast reoxidation of support sites by CO2 yielding CO regenerating reactive oxygen species.
      Citation: Catalysts
      PubDate: 2017-09-12
      DOI: 10.3390/catal7090268
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 269: Selective Acetylation of Small Biomolecules
           and Their Derivatives Catalyzed by Er(OTf)3

    • Authors: Monica Nardi, Maria Luisa Di Gioia, Paola Costanzo, Antonio De Nino, Loredana Maiuolo, Manuela Oliverio, Fabrizio Olivito, Antonio Procopio
      First page: 269
      Abstract: It is of great significance to develop sustainable processes of catalytic reaction. We report a selective procedure for the synthesis of acetylated bioactive compounds in water. The use of 1-acetylimidazole combined with Er(OTf)3 as a Lewis acid catalyst gives high regioselectivity and good yields for the acetylation of primary hydroxyl groups, as well as amino groups. The protection is achieved in short reaction times under microwave irradiation, and is successful even in the case of base-sensitive substrates.
      Citation: Catalysts
      PubDate: 2017-09-12
      DOI: 10.3390/catal7090269
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 270: Promotion of Ca-Co Bifunctional
           Catalyst/Sorbent with Yttrium for Hydrogen Production in Modified Chemical
           Looping Steam Methane Reforming Process

    • Authors: Samira Akbari-Emadabadi, Mohammad Rahimpour, Ali Hafizi, Peyman Keshavarz
      First page: 270
      Abstract: In this study, the application of a calcium-based bifunctional catalyst/sorbent is investigated in modified chemical looping steam methane reforming (CLSMR) process for in situ CO2 sorption and H2 production. The yttrium promoted Ca-Co samples were synthesized and applied as bifunctional catalysts/sorbent. The influence of reduction temperature (500–750 °C), Ca/Co and Ca/Y ratios (1.5–∞ and 3–18, respectively) and catalyst life time are determined in CLSMR process. The physicochemical transformation of fresh, used and regenerated samples after 16 redox cycles are determined using X-ray powder diffraction (XRD), N2 adsorption–desorption, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) techniques. The effect of yttrium promoter on the structure of catalyst and regeneration step on the reversibility of bifunctional catalyst/sorbent was two important factors. The characterization results revealed that the presence of yttrium in the structure of Ca-9Co sample could improve the morphology and textural properties of catalyst/sorbents. The suitable reversibility of bifunctional catalyst/sorbents during the repeated cycles is confirmed by characterization of calcined samples. The Ca-9Co-4.5Y as optimal catalyst illustrated superior performance and stability. It showed about 95.8% methane conversion and 82.9% hydrogen yield at 700 °C and stable activity during 16 redox cycles.
      Citation: Catalysts
      PubDate: 2017-09-13
      DOI: 10.3390/catal7090270
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 271: Catalytic Characteristics of New
           Antibacterials Based on Hexahistidine-Containing Organophosphorus
           Hydrolase

    • Authors: Olga Maslova, Aysel Aslanli, Nikolay Stepanov, Ilya Lyagin, Elena Efremenko
      First page: 271
      Abstract: Catalytic characteristics of hexahistidine-containing organophosphorus hydrolase (His6-OPH) and its enzyme-polyelectrolyte complexes with poly-l-glutamic acid or poly-l-aspartic acid (His6-OPH/PLD50), hydrolyzing organophosphorous compounds, and N-acyl homoserine lactones were studied in the presence of various antibiotics (ampicillin, gentamicin, kanamycin, and rifampicin). The antibiotics at concentrations below 1 g·L−1 had a negligible inhibiting effect on the His6-OPH activity. Mixed inhibition of His6-OPH was established for higher antibiotic concentrations, and rifampicin was the most potent inhibitor. Stabilization of the His6-OPH activity was observed in the presence of antibiotics at a concentration of 0.2 g·L−1 during exposure at 25–41 °C. Molecular docking of antibiotics to the surface of His6-OPH dimer revealed the antibiotics binding both to the area near active centers of the enzyme subunits and to the region of contact between subunits of the dimer. Such interactions between antibiotics and His6-OPH were verified with Fourier-transform infrared (FTIR) spectroscopy. Considering all the results of the study, the combination of His6-OPH/PLD50 with β-lactam antibiotic ampicillin was established as the optimal one in terms of exhibition and persistence of maximal lactonase activity of the enzyme.
      Citation: Catalysts
      PubDate: 2017-09-14
      DOI: 10.3390/catal7090271
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 272: The Catalytic Hydrogenation of Maleic
           Anhydride on CeO2−δ-Supported Transition Metal Catalysts

    • Authors: Xin Liao, Yin Zhang, Junqiu Guo, Lili Zhao, Martyn Hill, Zheng Jiang, Yongxiang Zhao
      First page: 272
      Abstract: The proper selection of transition metals and support is pivotal to the design of active and selective catalysts for maleic anhydride hydrogenation (MAH). Herein, the M/CeO2−δ (M = Co, Ni, Cu, respectively) catalysts with pre-optimised metal loading of 10 wt % were prepared via a wet impregnation method and well characterized to corroborate their MAH performance with the properties of metal, support and the M/CeO2−δ catalysts. The results revealed that the metal dispersion on the catalyst declines in the order of Ni/CeO2−δ > Co/CeO2−δ > Cu/CeO2−δ, similar to the apparent activity for maleic anhydride (MA) transformation to succinic anhydride (SA). The hydrogenolysis of SA to γ-butyrolactone (GBL) occurs on Ni/CeO2−δ and Co/CeO2−δ only when the MA → SA transformation completing. The Ni/CeO2−δ displays superior activity and selectivity to Co/CeO2−δ in both MA → SA and SA → GBL reactions, while the Cu/CeO2−δ and CeO2−δ are both inert for SA → GBL hydrogenolysis. The MA hydrogenation to SA follows the first order kinetic law on the Ni/CeO2−δ and Co/CeO2−δ catalysts yet a more complex kinetic characteristics observed on the Cu/CeO2−δ. The distinct catalytic hydrogenation behaviours of the M/CeO2−δ catalysts are assigned to the synergism of dispersion and electronic configuration of the transition metals and oxygen vacancies.
      Citation: Catalysts
      PubDate: 2017-09-14
      DOI: 10.3390/catal7090272
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 273: The Isomerization of Limonene over the
           Ti-SBA-15 Catalyst—The Influence of Reaction Time, Temperature, and
           Catalyst Content

    • Authors: Monika Retajczyk, Agnieszka Wróblewska
      First page: 273
      Abstract: The isomerization of limonene over the Ti-SBA-15 catalyst, which was prepared by the hydrothermal method, was studied. The main products of limonene isomerization were terpinolene, α-terpinene, γ-terpinene, and p-cymene—products with numerous applications. The amount of these products depended on reaction time, temperature, and catalyst content. These parameters changed in the following range: reaction time 30–1380 min, temperature 140–160 °C, and catalyst content 5–15 wt %. Finally, the most favorable conditions for the limonene isomerization process were established: a reaction time of 180 min, temperature of 160 °C, and amount of the catalyst 15 wt %. In order to obtain p-cymene (dehydroaromatization product), the most favorable conditions are similar but the reaction time should be 1380 min. The application of such conditions allowed us to obtain the highest amounts of the desired products in the shortest time.
      Citation: Catalysts
      PubDate: 2017-09-14
      DOI: 10.3390/catal7090273
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 274: Electrocarboxylation of Dichlorobenzenes on
           a Silver Electrode in DMF

    • Authors: Pei-Pei Luo, Ying-Tian Zhang, Bao-Li Chen, Shu-Xian Yu, Hua-Wei Zhou, Kong-Gang Qu, Yu-Xia Kong, Xian-Qiang Huang, Xian-Xi Zhang, Jia-Xing Lu
      First page: 274
      Abstract: Carbon dioxide (CO2) is the largest contributor to the greenhouse effect, and fixing and using this greenhouse gas in a facile manner is crucial. This work investigates the electrocarboxylation of dichlorobenzenes with the atmospheric pressure of CO2 in an undivided cell with an Ag cathode and an Mg sacrificial anode. The corresponding carboxylic acids and their derivatives, which are important industrial and fine chemicals, are obtained. To deeply understand this reaction, we investigate the influence of various reaction conditions, such as supporting electrolyte, current density, electric charge, and reaction temperature, on the electrocarboxylation yield by using 1,4-dichlorobenzene as the model compound. The electrochemical behavior of dichlorobenzenes is studied through cyclic voltammetry. The relation among the distinct electronic effects of dichlorobenzenes, the electrochemical characteristics of their reduction, and the distribution law of target products is also established.
      Citation: Catalysts
      PubDate: 2017-09-15
      DOI: 10.3390/catal7090274
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 275: Improving the Indigo Carmine Decolorization
           Ability of a Bacillus amyloliquefaciens Laccase by Site-Directed
           Mutagenesis

    • Authors: Jiayi Wang, Lei Lu, Fujuan Feng
      First page: 275
      Abstract: Indigo carmine is a typical recalcitrant dye which is widely used in textile dyeing processes. Laccases are versatile oxidases showing strong ability to eliminate hazardous dyes from wastewater. However, most laccases require the participation of mediators for efficient decolorization of indigo carmine. Here we describe the improvement of the decolorization ability of a bacterial laccase through site-directed mutagenesis. A D501G variant of Bacillus amyloliquefaciens laccase was constructed and overexpressed in Escherichia coli. The laccase activity in the culture supernatant achieved 3374 U·L−1 for the mutant. Compared with the wild-type enzyme, the D501G exhibited better stability and catalytic efficiency. It could decolorize more than 92% of indigo carmine without additional mediators in 5 h at pH 9.0, which was 3.5 times higher than the wild-type laccase. Isatin sulfonic acid was confirmed to be the main product of indigo carmine degradation by UV-vis and LC-MS analyses.
      Citation: Catalysts
      PubDate: 2017-09-15
      DOI: 10.3390/catal7090275
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 276: The Preparation of a Highly Efficient
           Ag3PO4/Ag/Bi2O2CO3 Photo-Catalyst and the Study of Its Photo-Catalytic
           Organic Synthesis Reaction Driven by Visible Light

    • Authors: Zhi Guo, Hui Xin, Jingjing Ma, Meifen Bai, Yan Wang, Jingyi Li
      First page: 276
      Abstract: Ag3PO4/Ag/Bi2O2CO3 composites were prepared by a hydrothermal and precipitation method. The morphology, structure, and valence state of the photo-catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, and UV-vis diffuse reflectance spectra (UV-vis DRS). They were applied as heterogeneous catalysts in the synthesis of esters from aldehydes (or alcohols) and alcohols and the synthesis of imines from alcohols and amines under visible light irradiation. The photo-catalytic activities of the esterification reactions of aldehydes and alcohols were heavily dependent on the loading of Ag3PO4/Ag/Bi2O2CO3 as well as the intensity and wavelength of the visible light. Furthermore, their conversion under visible light irradiation was superior to that in the dark. Herein a reaction mechanism from aldehydes and alcohols to esters was proposed, and the Ag3PO4/Ag/Bi2O2CO3 catalysts could be used six times without a significant decrease in activity. Using these catalysts under visible light could motivate future studies to develop efficient recyclable photo-catalysts and facilitate many synthetic organic reactions.
      Citation: Catalysts
      PubDate: 2017-09-17
      DOI: 10.3390/catal7090276
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 277: A New Homo-Hexamer Mn-Containing Catalase
           from Geobacillus sp. WCH70

    • Authors: Hai-Chao Li, Qing Yu, Hui Wang, Xin-Yu Cao, Li Ma, Zheng-Qiang Li
      First page: 277
      Abstract: Catalase is an effective biocatalyst to degrade hydrogen peroxide to water and oxygen that can serve in textile effluent treatment to remove residual H2O2. Thermostable catalases are needed to withstand both the high temperature and pH of textile wastewater. We have cloned the Mn-containing catalase gene ACS24898.1 from Geobacillus sp. WCH70, which originated from thermophilic organisms, and expressed it in Escherichia coli in activated form. The recombinant protein has been purified to homogeneity and identified to be a new homo-hexamer Mn-containing catalase. The native molecular mass of the catalase has been measured to be 138 kDa by size-exclusion chromatography. The new enzyme has optimum catalyzed activity at pH 9.0 and a temperature of 75 °C. It is thermostable up to 70 °C for 8 h incubation and maintains 80% and 50% activity, respectively, at 80 °C after 5 h and 90 °C after 1 h. At 75 °C and pH 9.0, the Km is 67.26 mM for substrate H2O2 and the rate of reaction at H2O2 saturation, Vmax, is 75,300 U/mg. The thermophilic and alkaline preferred properties of this new Mn-catalase are valuable features in textile wastewater treatment.
      Citation: Catalysts
      PubDate: 2017-09-18
      DOI: 10.3390/catal7090277
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 278: S- and N-Doped Graphene Nanomaterials for
           the Oxygen Reduction Reaction

    • Authors: Luis Rivera, Sergio Fajardo, María Arévalo, Gonzalo García, Elena Pastor
      First page: 278
      Abstract: In the current work, heteroatom-doped graphene materials containing different atomic ratios of nitrogen and sulphur were employed as electrocatalysts for the oxygen reduction reaction (ORR) in acidic and alkaline media. To this end, the hydrothermal route and different chemical reducing agents were employed to synthesize the catalytic materials. The physicochemical characterization of the catalysts was performed by several techniques, such as X-ray diffraction, Raman spectroscopy and elemental analysis; meanwhile, the electrochemical performance of the materials toward the ORR was analyzed by linear sweep voltammetry (LSV), rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques. The main results indicate that the ORR using heteroatom-doped graphene is a direct four-electron pathway, for which the catalytic activity is higher in alkaline than in acidic media. Indeed, a change of the reaction mechanism was observed with the insertion of N into the graphenic network, by the rate determining step changes from the first electrochemical step (formation of adsorbed OOH) on glassy carbon to the removal of adsorbed O (Oad) from the N-graphene surface. Moreover, the addition of sulphur atoms into the N-graphene structure increases the catalytic activity toward the ORR, as the desorption of Oad is accelerated.
      Citation: Catalysts
      PubDate: 2017-09-18
      DOI: 10.3390/catal7090278
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 279: Surface Oxidation of Supported Ni Particles
           and Its Impact on the Catalytic Performance during Dynamically Operated
           Methanation of CO2

    • Authors: Benjamin Mutz, Andreas Gänzler, Maarten Nachtegaal, Oliver Müller, Ronald Frahm, Wolfgang Kleist, Jan-Dierk Grunwaldt
      First page: 279
      Abstract: The methanation of CO2 within the power-to-gas concept was investigated under fluctuating reaction conditions to gather detailed insight into the structural dynamics of the catalyst. A 10 wt % Ni/Al2O3 catalyst with uniform 3.7 nm metal particles and a dispersion of 21% suitable to investigate structural changes also in a surface-sensitive way was prepared and characterized in detail. Operando quick-scanning X-ray absorption spectroscopy (XAS/QEXAFS) studies were performed to analyze the influence of 30 s and 300 s H2 interruptions during the methanation of CO2 in the presence of O2 impurities (technical CO2). These conditions represent the fluctuating supply of H2 from renewable energies for the decentralized methanation. Short-term H2 interruptions led to oxidation of the most reactive low-coordinated metallic Ni sites, which could not be re-reduced fully during the subsequent methanation cycle and accordingly caused deactivation. Detailed evaluation of the extended X-ray absorption fine structure (EXAFS) spectra showed surface oxidation/reduction processes, whereas the core of the Ni particles remained reduced. The 300-s H2 interruptions resulted in bulk oxidation already after the first cycle and a more pronounced deactivation. These results clearly show the importance and opportunities of investigating the structural dynamics of catalysts to identify their mechanism, especially in power-to-chemicals processes using renewable H2.
      Citation: Catalysts
      PubDate: 2017-09-18
      DOI: 10.3390/catal7090279
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 280: Halide-Enhanced Catalytic Activity of
           Palladium Nanoparticles Comes at the Expense of Catalyst Recovery

    • Authors: Azzedine Bouleghlimat, Mazin Othman, Louis Lagrave, Soichiro Matsuzawa, Yoshinobu Nakamura, Syuji Fujii, Niklaas Buurma
      First page: 280
      Abstract: In this communication, we present studies of the oxidative homocoupling of arylboronic acids catalyzed by immobilised palladium nanoparticles in aqueous solution. This reaction is of significant interest because it shares a key transmetallation step with the well-known Suzuki-Miyaura cross-coupling reaction. Additives can have significant effects on catalysis, both in terms of reaction mechanism and recovery of catalytic species, and our aim was to study the effect of added halides on catalytic efficiency and catalyst recovery. Using kinetic studies, we have shown that added halides (added as NaCl and NaBr) can increase the catalytic activity of the palladium nanoparticles more than 10-fold, allowing reactions to be completed in less than half a day at 30 °C. However, this increased activity comes at the expense of catalyst recovery. The results are in agreement with a reaction mechanism in which, under conditions involving high concentrations of chloride or bromide, palladium leaching plays an important role. Considering the evidence for analogous reactions occurring on the surface of palladium nanoparticles under different reaction conditions, we conclude that additives can exert a significant effect on the mechanism of reactions catalyzed by nanoparticles, including switching from a surface reaction to a solution reaction. The possibility of this switch in mechanism may also be the cause for the disagreement on this topic in the literature.
      Citation: Catalysts
      PubDate: 2017-09-19
      DOI: 10.3390/catal7090280
      Issue No: Vol. 7, No. 9 (2017)
       
  • Catalysts, Vol. 7, Pages 312: Analysis of Anodes of Microbial Fuel Cells
           When Carbon Brushes Are Preheated at Different Temperatures

    • Authors: Qiao Yang, Shengna Liang, Jia Liu, Jiangwei Lv, Yujie Feng
      First page: 312
      Abstract: The anode electrode is one of the most important components in all microbial electrochemical technologies (METs). Anode materials pretreatment and modification have been shown to be an effective method of improving anode performance. According to mass loss analysis during carbon fiber heating, five temperatures (300, 450, 500, 600, and 750 °C) were selected as the pre-heating temperatures of carbon fiber brush anodes. Microbial fuel cell (MFC) reactors built up with these pre-heated carbon brush anodes performed with different power densities and Coulombic efficiencies (CEs). Two kinds of measuring methods for power density were applied, and the numerical values of maximum power densities diverged greatly. Reactors with 450 °C anodes, using both methods, had the highest power densities, and the highest CEs were found using 500 °C anode reactors. The surface elements of heat-treated carbon fibers were analyzed using X-ray photoelectron spectra (XPS), and C, O, and N were the main constituents of the carbon fiber. There were four forms of N1s at the surface of the polyacrylonitrile (PAN)-based carbon fiber, and their concentrations were different at different temperature samples. The microbial community of the anode surface was analyzed, and microbial species on anodes from every sample were similar. The differences in anode performance may be caused by mass loss and by the surface elements. For carbon brush anodes used in MFCs or other BESs, 450–500 °C preheating was the most suitable temperature range in terms of the power densities and CEs.
      Citation: Catalysts
      PubDate: 2017-10-25
      DOI: 10.3390/catal7110312
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 313: Photoactive Hybrid Film Photocatalyst of
           Polyethersulfone-ZnO for the Degradation of Methyl Orange Dye: Kinetic
           Study and Operational Parameters

    • Authors: Zul Mohd Hir, Abdul Abdullah, Zulkarnain Zainal, Hong Lim
      First page: 313
      Abstract: A facile and effective technique to immobilize photocatalyst nanoparticles by incorporating zinc oxide (ZnO) into polyethersulfone polymeric films by means of a phase inversion technique is reported. The degradation study of methyl orange (MO) dye was performed using a series of ZnO-embedded polymer hybrid systems. The photoactivity of the films increased in parallel with increased ZnO loading up to 17 wt%. The photodegradation process followed a pseudo first-order kinetics with an achievement of almost 100% MO removal in original conditions. The PZ-17 film demonstrated an excellent and comparable degradation performance up to five cycles, signifying the reliability of the film photocatalyst against ultraviolet irradiation and degradation.
      Citation: Catalysts
      PubDate: 2017-10-26
      DOI: 10.3390/catal7110313
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 314: Microwave-Assisted Silver-Catalyzed
           Protodecarboxylation and Decarboxylative Iodination of Aromatic Carboxylic
           Acids

    • Authors: Kun Zhan, Yi Li
      First page: 314
      Abstract: Carboxylic acids and their derivatives are readily available from both natural and synthetic sources. Apart from being used as direct substrates in the functional transformation, aryl carboxylic acids have found more applications in aromatic functionalization, especially in decarboxylation coupling reactions. Microwave-assisted protodecarboxylation and decarboxylative iodination of aromatic carboxylic acids were achieved with excellent yields in the presence of Ag2CO3 catalyst and K2S2O8. These reactions will be helpful for better understanding of decarboxylation-related coupling reactions and also have the potential of being used as a practical labeling method to synthesize regioselective deuterium and iodine-labelled compounds for chemical, biological, and medicinal research.
      Citation: Catalysts
      PubDate: 2017-10-26
      DOI: 10.3390/catal7110314
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 315: Efficient Degradation of Aqueous
           Carbamazepine by Bismuth Oxybromide-Activated Peroxide Oxidation

    • Authors: Tuqiao Zhang, Shipeng Chu, Jian Li, Lili Wang, Rong Chen, Yu Shao, Xiaowei Liu, Miaomiao Ye
      First page: 315
      Abstract: Bismuth oxyhalide, usually employed as a photocatalyst, has not been tested as an activator of peroxide for water purification. This work explores the potential application of bismuth oxyhalide (BiOX, X = Cl, Br, I)-activated peroxide (H2O2; peroxymonosulfate (PMS) and peroxydisulfate) systems for the degradation of carbamazepine (CBZ) in water destined for drinking water. BiOBr showed the highest activity toward the peroxides investigated, especially toward PMS. The most efficient combination, BiOBr/PMS, was selected to further research predominant species responsible for CBZ degradation and toxicity of transformation products. With repeated use of BiOBr, low bismuth-leaching and subtle changes in crystallinity and activity were observed. CBZ degradation was primarily (67.3%) attributable to attack by sulfate radical. Toxicity test and identification of the oxidation products indicated some toxic intermediates may be produced. A possible degradation pathway is proposed. Besides substitution of the hydroxyl groups on the surface of the catalyst particles, PMS’s complexation with the lattice Bi(III) through ion exchange with interlayer bromide ion was involved in the decomposition of PMS. The Bi(III)−Bi(V)−Bi(III) redox cycle contributed to the efficient generation of sulfate radicals from the PMS. Our findings provide a simple and efficient process to produce powerful radicals from PMS for refractory pollutant removal.
      Citation: Catalysts
      PubDate: 2017-10-26
      DOI: 10.3390/catal7110315
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 316: Production of 4-Ene-3-ketosteroids in
           Corynebacterium glutamicum

    • Authors: Julia García-Fernández, Beatriz Galán, Carmen Felpeto-Santero, José Barredo, José García
      First page: 316
      Abstract: Corynebacterium glutamicum has been widely used for the industrial production of amino acids and many value-added chemicals; however, it has not been exploited for the production of steroids. Using C. glutamicum as a cellular biocatalyst we have expressed the 3β-hydroxysteroid dehydrogenase/isomerase MSMEG_5228 from Mycobacterium smegmatis to demonstrate that the resulting recombinant strain is able to oxidize in vivo C19 and C21 3-OH-steroids to their corresponding keto-derivatives. This new approach constitutes a proof of concept of a biotechnological process for producing value-added intermediates such as 4-pregnen-16α,17α-epoxy-16β-methyl-3,20-dione.
      Citation: Catalysts
      PubDate: 2017-10-27
      DOI: 10.3390/catal7110316
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 317: On the Origin of Enhanced Photocatalytic
           Activity of Copper-Modified Titania in the Oxidative Reaction Systems

    • Authors: Marcin Janczarek, Ewa Kowalska
      First page: 317
      Abstract: Modification of titania with copper is a promising way to enhance the photocatalytic performance of TiO2. The enhancement means the significant retardation of charge carriers’ recombination ratio and the introduction of visible light activity. This review focuses on two main ways of performance enhancement by copper species—i.e., originated from plasmonic properties of zero-valent copper (plasmonic photocatalysis) and heterojunctions between semiconductors (titania and copper oxides). The photocatalytic performance of copper-modified titania is discussed for oxidative reaction systems due to their importance for prospective applications in environmental purification. The review consists of the correlation between copper species and corresponding variants of photocatalytic mechanisms including novel systems of cascade heterojunctions. The problem of stability of copper species on titania, and the methods of its improvement are also discussed as important factors for future applications. As a new trend in the preparation of copper-modified titania photocatalyst, the role of particle morphology (faceted particles, core-shell structures) is also described. Finally, in the conclusion section, perspectives, challenges and recommendations for future research on copper-modified titania are formulated.
      Citation: Catalysts
      PubDate: 2017-10-27
      DOI: 10.3390/catal7110317
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 318: Enzymatic Degradation of Poly(ethylene
           2,5-furanoate) Powders and Amorphous Films

    • Authors: Simone Weinberger, Judit Canadell, Felice Quartinello, Bahar Yeniad, Andrea Arias, Alessandro Pellis, Georg Guebitz
      First page: 318
      Abstract: Poly(ethylene 2,5-furanoate) (PEF) is arousing great interest as a biobased alternative to plastics like poly(ethylene terephthalate) (PET) due to its wide range of potential applications, such as food and beverage packaging, clothing, and in the car industry. In the present study, the hydrolysis of PEF powders of different molecular masses (Mn = 55, Mw = 104 kg/mol and Mn = 18, Mw = 29 kg/mol) and various particle sizes (180 < d and 180 < d < 425 µm) using cutinase 1 from Thermobifida cellulosilytica (Thc_cut1) was studied. Thereby, the effects of molecular mass, particle size and crystallinity on enzymatic hydrolysis were investigated. The results show that particles with lower molecular mass are hydrolyzed faster than those with higher masses, and that the higher the molecular mass, the lower the influence of the particle size on the hydrolysis. Furthermore, cutinases from Humicola insolens (HiC) and Thc_cut1 were compared with regard to their hydrolytic activity on amorphous PEF films (measured as release of 2,5-furandicarboxylic acid (FDCA) and weight loss) in different reaction media (1 M KPO pH 8, 0.1 M Tris-HCl pH 7) and at different temperatures (50 °C and 65 °C). A 100% hydrolysis of the PEF films was achieved after only 72 h of incubation with a HiC in 1 M KPO pH 8 at 65 °C. Moreover, the hydrolysis reaction was monitored by LC/TOF-MS analysis of the released reaction products and by Scanning Electron Microscopy (SEM) examination of the polymer surfaces. Enzymatic hydrolysis of PEF with Thc_cut1 and HiC has potential for use in surface functionalization and recycling purposes.
      Citation: Catalysts
      PubDate: 2017-10-27
      DOI: 10.3390/catal7110318
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 319: Metal Oxide Nanoparticles Supported on
           Macro-Mesoporous Aluminosilicates for Catalytic Steam Gasification of
           Heavy Oil Fractions for On-Site Upgrading

    • Authors: Daniel López, Lady J. Giraldo, Juan P. Salazar, Dioni M. Zapata, Diana C. Ortega, Camilo A. Franco, Farid B. Cortés
      First page: 319
      Abstract: Catalytic steam gasification of extra-heavy oil (EHO) fractions was studied using functionalized aluminosilicates, with NiO, MoO3, and/or CoO nanoparticles with the aim of evaluating the synergistic effect between active phase and the support in heavy oil on-site upgrading. Catalysts were characterized by chemical composition through X-ray Fluorescence, surface area, and pore size distribution through N2 adsorption/desorption, catalyst acidity by temperature programmed desorption (TPD), and metal dispersion by pulse H2 chemisorption. Batch adsorption experiments and catalytic steam gasification of adsorbed heavy fractions was carried out by thermogravimetric analysis and were performed with heavy oil model solutions of asphaltenes and resins (R–A) in toluene. Effective activation energy estimation was used to determine the catalytic effect of the catalyst in steam gasification of Colombian EHO. Additionally, R–A decomposition under inert atmosphere was conducted for the evaluation of oil components reactions with active phases and steam atmosphere. The presence of a bimetallic active phase Inc.reases the decomposition of the heavy compounds at low temperature by an increase in the aliphatic chains decomposition and the dissociation of heteroatoms bonds. Also, coke formation after steam gasification process is reduced by the application of the bimetallic catalyst yielding a conversion greater than 93%.
      Citation: Catalysts
      PubDate: 2017-10-29
      DOI: 10.3390/catal7110319
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 320: Synthesis of Isoquinolinones via
           Regioselective Palladium-Catalyzed C–H Activation/Annulation

    • Authors: Wenke Qi, Yimei Wu, Yongxu Han, Yi Li
      First page: 320
      Abstract: The isoquinoline motif and its derivatives are of significant interest due to their important biological activities. The effective synthesis of substituted isoquinoline compounds has historically been a significant challenge. A new palladium-catalyzed C–H activation/annulation of N-methoxy benzamides and 2,3-allenoic acid esters is described. For the first time, 2,3-allenoic acid esters are employed for the syntheses of 3,4-substituted hydroisoquinolones, the heteroannulation of allenes proceeded smoothly and afforded the products with good yields and excellent regioselectivity.
      Citation: Catalysts
      PubDate: 2017-10-30
      DOI: 10.3390/catal7110320
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 321: Highly Selective Catalytic Properties of
           HZSM-5 Zeolite in the Synthesis of Acetyl Triethyl Citrate by the
           Acetylation of Triethyl Citrate with Acetic Anhydride

    • Authors: Kyong-Hwan Chung, Sangmin Jeong, Hangun Kim, Sun-Jae Kim, Young-Kwon Park, Sang-Chul Jung
      First page: 321
      Abstract: The catalytic activities of acid catalysts for the acetylation of triethyl citrate with acetic anhydride in the preparation of acetyl triethyl citrate were evaluated. Microporous zeolites such as HZSM-5 and HY zeolites catalysts were introduced as heterogeneous acid catalysts. HZSM-5 zeolite catalysts showed a high conversion of triethyl citrate and excellent selectivity of acetyl triethyl citrate. The catalytic activities of HZSM-5 zeolites were superior to those of the HY zeolites. In particular, the selectivity of acetyl triethyl citrate on HZSM-5 zeolites exceeded 95%. The moderate acid strength of HZSM-5 (Si/Al = 75) zeolite led to the highest catalytic activities among the HZSM-5 zeolite catalysts, which have various acid strengths.
      Citation: Catalysts
      PubDate: 2017-10-30
      DOI: 10.3390/catal7110321
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 322: Enzymatically-Mediated Co-Production of
           Cellulose Nanocrystals and Fermentable Sugars

    • Authors: Dawit Beyene, Michael Chae, Jing Dai, Christophe Danumah, Frank Tosto, Abayneh Getachew Demesa, David C. Bressler
      First page: 322
      Abstract: Cellulose nanocrystals (CNCs) can be extracted from cellulosic materials through the degradation of non-crystalline cellulose domains in the feedstock via acid hydrolysis. However, the sugars released from the hydrolysis process cannot be easily recovered from the acid waste stream. In this study, cellulases were used to preferentially degrade non-crystalline domains with the objectives of recovering sugars and generating a feedstock with concentrated CNC precursors for a more efficient acid hydrolysis process. Filter paper and wood pulp substrates were enzyme-treated for 2–10 h to recover 20–40 wt % glucose. Substantial xylose yield (6–12 wt %) was generated from wood pulp. CNC yields from acid hydrolysis of cellulases-treated filter paper, and wood pulp improved by 8–18% and 58–86%, respectively, when compared with the original substrate. It was thought that CNC precursors accumulated in the cellulases-treated feedstock due to enzymatic digestion of the more accessible non-crystalline celluloses. Therefore, acid hydrolysis from enzyme-treated feedstock will require proportionally less water and reagents resulting in increased efficiency and productivity in downstream processes. This study demonstrates that an enzymatically-mediated process allows recovery of fermentable sugars and improves acid hydrolysis efficiency for CNC production.
      Citation: Catalysts
      PubDate: 2017-10-30
      DOI: 10.3390/catal7110322
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 323: Styrene Oxidation to Valuable Compounds over
           Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

    • Authors: Ana Paula Saraiva Oliveira, Igor Santos Gomes, Alcineia Conceição Oliveira, Josue M. Filho, Gilberto Dantas Saraiva, João Maria Soares, Francisco Ferreira de Sousa, Adriana Campos
      First page: 323
      Abstract: Nanosized FeCo-based solids were prepared via distinct preparation procedures. The catalytic performances of the solids for styrene oxidation in the presence of hydrogen peroxide were evaluated. The addition of promoters in FeCo such as Sn, Mo, or Cu was also investigated. The catalysts were characterized with XRD, Raman spectroscopy, TEM, chemical analyses, EPR and SEM-EDS. Of these solids obtained via four different methods, the catalyst prepared via the NC and CM procedures enabled a partial incorporation of the Sn into the FeCo matrix forming a very active phase, namely the Heusler alloy. This was ascribed to the high initial dispersion of Sn as a promoter into the FeCo matrix, which led to available FeCoSn (FCS) particles well dispersed and stable on the catalyst surface. In the case of incorporating Mo or Cu to the nanosized FeCo catalyst, a poor stability towards leaching was observed when operating under the same reaction conditions. Cu was much less active than both Sn and Mo, mainly leading to acetophenone, ethylbenzene, 2-phenyl ethanol, 2-phenyl acetic acid, and 2-phenyl acetaldehyde products. The best catalytic results under the optimized reaction conditions, especially at 50 °C and styrene/H2O2 molar ratio of 1 were achieved with nanosized FCS. This solid had a conversion of ca. 70% and selectivity for aldehydes of ca. 27%, and the selectivity for the condensation products was 29%.
      Citation: Catalysts
      PubDate: 2017-10-30
      DOI: 10.3390/catal7110323
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 324: Hydrogen Production via Water Dissociation
           Using Pt–TiO2 Photocatalysts: An Oxidation–Reduction Network

    • Authors: J. F. Guayaquil-Sosa, Alan Calzada, Benito Serrano, Salvador Escobedo, Hugo de Lasa
      First page: 324
      Abstract: Several TiO2 based semiconductors with different Pt loadings are prepared using incipient impregnation, wet impregnation and the sol-gel method. These photocatalysts are evaluated in the Photo-CREC-Water II Photoreactor for hydrogen production via water dissociation, using an organic renewable scavenger (ethanol). Results obtained show the influence of the photocatalyst preparation in the production of hydrogen and in the observed quantum yields. Furthermore, it is established that the reaction networks leading to hydrogen production, using various photocatalysts, share common features. This analysis is developed by both identifying and quantifying different chemical species and their changes with irradiation time. Key species in this oxidation–reduction network are hydrogen, hydrogen peroxide, ethanol, methane, ethane, acetaldehyde and carbon dioxide. On this basis, it is shown that under an inert gas atmosphere, ethanol consumption is sub-stoichiometric. This points towards simultaneous ethanol consumption and the formation of the ethanol scavenger.
      Citation: Catalysts
      PubDate: 2017-10-30
      DOI: 10.3390/catal7110324
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 325: Consideration of the Role of Plasma in a
           Plasma-Coupled Selective Catalytic Reduction of Nitrogen Oxides with a
           Hydrocarbon Reducing Agent

    • Authors: Byeong Lee, Ho-Chul Kang, Jin Jo, Young Mok
      First page: 325
      Abstract: The purpose of this study is to explain how plasma improves the performance of selective catalytic reduction (SCR) of nitrogen oxides (NOx) with a hydrocarbon reducing agent. In the plasma-coupled SCR process, NOx reduction was performed with n-heptane as a reducing agent over Ag/γ-Al2O3 as a catalyst. We found that the plasma decomposes n-heptane into several oxygen-containing products such as acetaldehyde, propionaldehyde and butyraldehyde, which are more reactive than the parent molecule n-heptane in the SCR process. Separate sets of experiments using acetaldehyde, propionaldehyde and butyraldehyde, one by one, as a reductant in the absence of plasma, have clearly shown that the presence of these partially oxidized compounds greatly enhanced the NOx conversion. The higher the discharge voltage, the more the amounts of such partially oxidized products. The oxidative species produced by the plasma easily converted NO into NO2, but the increase of the NO2 fraction was found to decrease the NOx conversion. Consequently, it can be concluded that the main role of plasma in the SCR process is to produce partially oxidized compounds (aldehydes), having better reducing power. The catalyst-alone NOx removal efficiency with n-heptane at 250 °C was measured to be less than 8%, but it increased to 99% in the presence of acetaldehyde at the same temperature. The NOx removal efficiency with the aldehyde reducing agent was higher as the number of carbons in the aldehyde was more; for example, the NOx removal efficiencies at 200 °C with butyraldehyde, propionaldehyde and acetaldehyde were measured to be 83.5%, 58.0% and 61.5%, respectively, which were far above the value (3%) obtained with n-heptane.
      Citation: Catalysts
      PubDate: 2017-10-31
      DOI: 10.3390/catal7110325
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 326: Synthesis of Phase Pure Hexagonal YFeO3
           Perovskite as Efficient Visible Light Active Photocatalyst

    • Authors: Mohammed Ismael, Engy Elhaddad, Dereje Taffa, Michael Wark
      First page: 326
      Abstract: Hexagonal perovskite YFeO3 was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS) and Tauc plots, the hexagonal YFeO3 exhibits a lower optical band gap (1.81 eV) than the orthorhombic structure (about 2.1 eV or even higher) being typically obtained at elevated temperatures (>700 °C), and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO3 perovskites were analyzed by powder X-ray diffraction (XRD) and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO3 with a hexagonal phase. The photocatalytic activity of the different YFeO3 phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO3 and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y2O3 might support the photocatalysis by improving the separation of photogenerated charge carriers.
      Citation: Catalysts
      PubDate: 2017-11-03
      DOI: 10.3390/catal7110326
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 327: In-Situ Self-Assembly of Zinc/Adenine Hybrid
           Nanomaterials for Enzyme Immobilization

    • Authors: Hao Liang, Shanshan Sun, Yan Zhou, Yanhui Liu
      First page: 327
      Abstract: In this study, a one-step and facile immobilization of enzymes by self-assembly of zinc ions and adenine in aqueous solution with mild conditions was reported. Enzymes, such as glucose oxidase (GOx) and horseradish peroxidase (HRP), could be efficiently encapsulated in Zn/adenine coordination polymers (CPs) with high loading capacity over 90%. When the enzyme was immobilized by CPs, it displayed high catalytic efficiency, high selectivity and enhanced stability due to the protecting effect of the rigid framework. As a result, the relative activity of Zn/adenine nano-CP-immobilized GOx increased by 1.5-fold at pH 3 and 4-fold at 70 to 90 °C, compared to free GOx. The immobilized GOx had excellent reusability (more than 90% relative activity after being reused eight times). Furthermore, the use of this system as a glucose biosensor was also demonstrated by co-immobilization of two enzymes, detecting glucose down to 1.84 µM with excellent selectivity. The above work indicated that in-situ self-assembly of Zn/adenine CPs could be a simple and efficient method for biocatalyst immobilization.
      Citation: Catalysts
      PubDate: 2017-11-03
      DOI: 10.3390/catal7110327
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 328: Metal-Catalyzed Intra- and Intermolecular
           Addition of Carboxylic Acids to Alkynes in Aqueous Media: A Review

    • Authors: Javier Francos, Victorio Cadierno
      First page: 328
      Abstract: The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions of this process. In order to reduce the environmental impact of these reactions, considerable efforts have been devoted in recent years to the development of catalytic systems able to operate in aqueous media, which represent a real challenge taking into account the tendency of alkynes to undergo hydration in the presence of transition metals. Despite this, different Pd, Pt, Au, Cu and Ru catalysts capable of promoting the intra- and intermolecular addition of carboxylic acids to alkynes in a selective manner in aqueous environments have appeared in the literature. In this review article, an overview of this chemistry is provided. The synthesis of β-oxo esters by catalytic addition of carboxylic acids to terminal propargylic alcohols in water is also discussed.
      Citation: Catalysts
      PubDate: 2017-11-06
      DOI: 10.3390/catal7110328
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 329: Synergetic Effect of Ni2P/SiO2 and γ-Al2O3
           Physical Mixture in Hydrodeoxygenation of Methyl Palmitate

    • Authors: Ivan Shamanaev, Irina Deliy, Evgeny Gerasimov, Vera Pakharukova, Evgeny Kodenev, Pavel Aleksandrov, Galina Bukhtiyarova
      First page: 329
      Abstract: The Ni2P/SiO2 catalyst, which was prepared by in situ temperature-programmed reduction and in the mixture with the inert (SiC, SiO2) or acidic (γ-Al2O3) material was studied in methyl palmitate hydrodeoxygenation (HDO). Methyl palmitate HDO was carried out at temperatures of 270–330 °C, H2/feed volume ratio of 600 Nm3/m3, and H2 pressure of 3.0 MPa. Ni2P/SiO2 catalyst, diluted with γ-Al2O3 showed a higher activity than Ni2P/SiO2 catalyst diluted with SiC or SiO2. The conversion of methyl palmitate increased significantly in the presence of γ-Al2O3 most probably due to the acceleration of the acid-catalyzed reaction of ester hydrolysis. The synergism of Ni2P/SiO2 and γ-Al2O3 in methyl palmitate HDO can be explained by the cooperation of the metal sites of Ni2P/SiO2 and the acid sites of γ-Al2O3 in consecutive metal-catalyzed and acid-catalyzed reactions of HDO. The obtained results let us conclude that the balancing of metal and acid sites plays an important role in the development of the efficient catalyst for the HDO of fatty acid esters over supported phosphide catalysts.
      Citation: Catalysts
      PubDate: 2017-11-06
      DOI: 10.3390/catal7110329
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 330: A Non-Precious Metal Promoting the Synthesis
           of 5-Hydroxymethylfurfural

    • Authors: Xinyuan Lu, Hongjie Zhao, Wei Feng, Peijun Ji
      First page: 330
      Abstract: In this work, a new kind of catalyst was prepared for synthesis of 5-hydroxymethylfurfural. Copper ions were incorporated into manganese oxide octahedral molecular sieves (K-OMS-2). The catalysts Cu-K-OMS-2 were characterized by measuring FTIR spectra, scanning electron microscope images, X-ray diffraction patterns, and temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) profiles. Thermogravimetric analysis (TGA) demonstrated that the stability of Cu-K-OMS-2 is almost the same as that of K-OMS-2. XRD patterns showed that introducing copper ions did not change the structure of K-OMS-2, but copper ions had an effect on the morphology of K-OMS-2 as illustrated by SEM images. TPD profiles demonstrated that both K-OMS-2 and Cu-K-OMS-2 possess basic and acidic sites, and Cu-K-OMS-2 has weak acidic sites. One-pot synthesis of 2,5-diformylfuran (DFF) from fructose was investigated under the catalysis of Cu-K-OMS-2 together with a commercial catalyst Amberlyst 15. The effect of reaction time and temperature on the DFF yield was investigated, and reaction temperature had an effect on the DFF yield. The effect of atomic ratio of Cu to Mn of Cu-K-OMS-2 on the DFF yield was also investigated. The DFF yield was improved 34.7% by Cu-K-OMS-2 in comparison to K-OMS-2, indicating the promotion effect of copper on the DFF yield. Consecutive use of Cu-K-OMS-2 demonstrated that after 6 cycles, the loss of DFF yield was 6.3%, indicating a good reusability of Cu-K-OMS-2.
      Citation: Catalysts
      PubDate: 2017-11-06
      DOI: 10.3390/catal7110330
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 331: Novel Ni-Ce-Zr/Al2O3 Cellular Structure for
           the Oxidative Dehydrogenation of Ethane

    • Authors: Juan Bortolozzi, Raquel Portela, Pedro Ávila, Viviana Milt, Eduardo Miró
      First page: 331
      Abstract: A novel γ-alumina-supported Ni-Ce-Zr catalyst with cellular structure was developed for oxidative dehydrogenation of ethane (ODHE). First, powdered samples were synthesized to study the effect of both the total metal content and the Ce/Zr ratio on the physicochemical properties and performance of these catalysts. All synthesized powdered samples were highly active and selective for ODHE with a maximum ethylene productivity of 6.94 µmolethylene gact cat−1 s−1. According to the results, cerium addition increased the most reducible nickel species population, which would benefit ethane conversion, whereas zirconium incorporation would enhance ethylene selectivity through the generation of higher amounts of the least reducible nickel species. Therefore, the modification of active site properties by addition of both promoters synergistically increases the productivity of the Ni-based catalysts. The most efficient formulation, in terms of ethylene productivity per active phase amount, contained 15 wt% of the mixed oxide with Ni0.85Ce0.075Zr0.075 composition. This formulation was selected to synthesize a Ni-Ce-Zr/Al2O3 structured body by deposition of the active phase onto a homemade γ-alumina monolith. The structured support was manufactured by extrusion of boehmite-containing dough. The main properties of the Ni0.85Ce0.075Zr0.075 powder were successfully preserved after the shaping procedure. In addition, the catalytic performance of the monolithic sample was comparable in terms of ethylene productivity to that of the powdered counterpart.
      Citation: Catalysts
      PubDate: 2017-11-08
      DOI: 10.3390/catal7110331
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 332: Development of an Efficient Methanol
           Production Process for Direct CO2 Hydrogenation over a Cu/ZnO/Al2O3
           Catalyst

    • Authors: Fereshteh Samimi, Mohammad Reza Rahimpour, Ali Shariati
      First page: 332
      Abstract: Carbon capture and utilization as a raw material for methanol production are options for addressing energy problems and global warming. However, the commercial methanol synthesis catalyst offers a poor efficiency in CO2 feedstock because of a low conversion of CO2 and its deactivation resulting from high water production during the process. To overcome these barriers, an efficient process consisting of three stage heat exchanger reactors was proposed for CO2 hydrogenation. The catalyst volume in the conventional methanol reactor (CR) is divided into three sections to load reactors. The product stream of each reactor is conveyed to a flash drum to remove methanol and water from the unreacted gases (H2, CO and CO2). Then, the gaseous stream enters the top of the next reactor as the inlet feed. This novel configuration increases CO2 conversion almost twice compared to one stage reactor. Also to reduce water production, a water permselective membrane was assisted in each reactor to remove water from the reaction side. The proposed process was compared with one stage reactor and CR from coal and natural gas. Methanol is produced 288, 305, 586 and 569 ton/day in CR, one-stage, three-stage and three-stage membrane reactors (MR), respectively. Although methanol production rate in three-stage MR is a bit lower than three stage reactors, the produced water, as the cause of catalyst poisoning, is notably reduced in this configuration. Results show that the proposed process is a strongly feasible way to produce methanol that can competitive with a traditional synthesis process.
      Citation: Catalysts
      PubDate: 2017-11-08
      DOI: 10.3390/catal7110332
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 333: Catalytic Deoxygenation of Hexadecyl
           Palmitate as a Model Compound of Euglena Oil in H2 and N2 Atmospheres

    • Authors: Yanyong Liu, Megumu Inaba, Koichi Matsuoka
      First page: 333
      Abstract: Hexadecyl palmitate (C15H31COOC16H33, used as a model compound for Euglena oil) was deoxygenated to hydrocarbons over various solid catalysts in autoclave reactors. In a H2 atmosphere, 1 wt.% of Pd/Mg(Al)O catalyst, derived from a hydrotalcite precursor, yielded a C15H31COOC16H33 conversion close to 100%, and a C10‒C16 (aviation fuel range) hydrocarbon yield of 90.2% for the deoxygenation of C15H31COOC16H33 at 300 °C for 2 h. In a N2 atmosphere, 1 wt.% of Pd/Mg(Al)O catalyst yielded a C10‒C16 hydrocarbon yield of 63.5%, which was much higher than those obtained with Mg(Al)O (15.1%), H-ZSM-5 (8.3%), and 1 wt.% Pd/C (26.2%) for the deoxygenation of C15H31COOC16H33 at 300 °C for 2 h. The Pd metal site and the solid base site in Mg(Al)O had a synergetic effect on the deoxygenation of C15H31COOC16H33 in N2 atmosphere over the Pd/Mg(Al)O catalyst. By prolonging the reaction time to 5 h for reaction at 300 °C in N2 atmosphere, the yield of C10‒C16 hydrocarbons increased to 80.4% with a C15H31COOC16H33 conversion of 99.1% over the 1 wt.% Pd/Mg(Al)O catalyst.
      Citation: Catalysts
      PubDate: 2017-11-09
      DOI: 10.3390/catal7110333
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 334: Reforming Catalysts

    • Authors: Simon Penner
      First page: 334
      Abstract: Steam and dry reforming of hydrocarbons (e.g., methane, ethane or propane), alcohols (e.g., methanol, ethanol or glycerol) or bio-compounds is one of the most promising and effective routes to enhanced hydrogen production and for the production of synthesis gas likewise.[...]
      Citation: Catalysts
      PubDate: 2017-11-09
      DOI: 10.3390/catal7110334
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 335: First-Row-Transition Ion Metals(II)-EDTA
           Functionalized Magnetic Nanoparticles as Catalysts for Solvent-Free
           Microwave-Induced Oxidation of Alcohols

    • Authors: Nuno Martins, Luísa Martins, Carlos Amorim, Vitor Amaral, Armando Pombeiro
      First page: 335
      Abstract: A series of first-row transition-metals combined with ethylenediamine tetraacetic acid (EDTA), as metal-based N,O-chelating ligands, at the surface of ferrite magnetic nanoparticles (MNPs) was prepared by a co-precipitation method. Those EDTA functionalized MNPs with general formula Fe3O4@EDTA-M2+ [M = Mn2+ (1), Fe2+ (2), Co2+ (3), Ni2+ (4), Cu2+ (5) or Zn2+ (6)] were characterized by FTIR (Fourier Transform Infrared) spectroscopy, powder XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectrometer), VSM (Vibrating Sample Magnetometer) and TGA (Thermal Gravity Analysis). The application of the magnetic NPs towards the microwave-assisted oxidation of several alcohol substrates in a solvent-free medium was evaluated. The influence of reaction parameters such as temperature, time, type of oxidant, and presence of organic radicals was investigated. This study demonstrates that these MNPs can act as efficient catalysts for the conversion of alcohols to the corresponding ketones or aldehydes with high selectivity and yields up to 99% after 2 h of reaction at 110 °C using t-BuOOH as oxidant. Moreover, they have the advantage of being magnetically recoverable catalysts that can be easily recycled in following runs.
      Citation: Catalysts
      PubDate: 2017-11-09
      DOI: 10.3390/catal7110335
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 336: Ultrasonic Monitoring of Biocatalysis in
           Solutions and Complex Dispersions

    • Authors: Vitaly Buckin, Margarida Altas
      First page: 336
      Abstract: The rapidly growing field of chemical catalysis is dependent on analytical methods for non-destructive real-time monitoring of chemical reactions in complex systems such as emulsions, suspensions and gels, where most analytical techniques are limited in their applicability, especially if the media is opaque, or if the reactants/products do not possess optical activity. High-resolution ultrasonic spectroscopy is one of the novel technologies based on measurements of parameters of ultrasonic waves propagating through analyzed samples, which can be utilized for real-time non-invasive monitoring of chemical reactions. It does not require optical transparency, optical markers and is applicable for monitoring of reactions in continuous media and in micro/nano bioreactors (e.g., nanodroplets of microemulsions). The technology enables measurements of concentrations of substrates and products over the whole course of reaction, analysis of time profiles of the degree of polymerization and molar mass of polymers and oligomers, evolutions of reaction rates, evaluation of kinetic mechanisms, measurements of kinetic and equilibrium constants and reaction Gibbs energy. It also provides tools for assessments of various aspects of performance of catalysts/enzymes including inhibition effects, reversible and irreversible thermal deactivation. In addition, ultrasonic scattering effects in dispersions allow real-time monitoring of structural changes in the medium accompanying chemical reactions.
      Citation: Catalysts
      PubDate: 2017-11-15
      DOI: 10.3390/catal7110336
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 337: Visible-Light Photocatalytic E to Z
           Isomerization of Activated Olefins and Its Application for the Syntheses
           of Coumarins

    • Authors: Kun Zhan, Yi Li
      First page: 337
      Abstract: Photocatalytic isomerization of thermodynamically stable E-alkene to less stable Z-alkene has been the subject of numerous studies, being successfully achieved mainly under UV irradiation. Recent development of visible light photoredox catalysis has witnessed it emerging as a powerful tool for the access of new structural complexity and many challenging targets. Herein, we report a visible light-promoted E to Z isomerization of cinnamates. When E-isomer of cinnamates was irradiated with blue light in the presence of an organo-photocatalyst, fac-Ir(ppy)3, Z-isomer was exclusively obtained in high yields and with good selectivity. The mild, convenient reaction condition has made this protocol an effective synthetic methodology, which was subsequently implemented in an efficient synthesis of coumarins.
      Citation: Catalysts
      PubDate: 2017-11-09
      DOI: 10.3390/catal7110337
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 338: Terpyridine-Containing Imine-Rich Graphene
           for the Oxygen Reduction Reaction

    • Authors: Min Lee, Mun Yang, Jong Park, Dong Chang
      First page: 338
      Abstract: We report a facile synthetic method for the preparation of a terpyridine-containing imine-rich graphene (IrGO-Tpy) using an acid-catalyzed dehydration reaction between graphene oxide (GO) and 4′-(aminophenyl)-2,2′:6′2″-terpyridine. Owing to the presence of terpyridine ligands, cobalt ions (Co2+) were readily incorporated into the IrGO-Tpy structures, affording a metal complex, denoted IrGo-Tpy-Co. Cyclic voltammetry and linear sweep voltammetry measurements confirm the noticeable oxygen reduction reaction (ORR) activities of the IrGo-Tpy and IrGo-Tpy-Co electroacatalysts in alkaline electrolytes, along with the additional merits of high selectivity, excellent long-term durability, and good resistance to methanol crossover. In addition, a remarkable improvement in the ORR performance was observed for IrGO-Tpy-Co compared with that of IrGo-Tpy, arising from the significant contribution of the cobalt-terpyridine complex in facilitating the ORR process.
      Citation: Catalysts
      PubDate: 2017-11-10
      DOI: 10.3390/catal7110338
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 339: Intrinsic Activity of MnOx-CeO2 Catalysts in
           Ethanol Oxidation

    • Authors: Dimitrios Delimaris, Theophilos Ioannides
      First page: 339
      Abstract: MnOx-CeO2 mixed oxides are considered efficient oxidation catalysts superior to the corresponding single oxides. Although these oxides have been the subject of numerous studies, their fundamental performance indicators, such as turnover frequency (TOF) or specific activity, are scarcely reported. The purpose of the present work is to investigate the effect of catalyst composition on the concentration of active sites and intrinsic activity in ethanol oxidation by the employment of temperature-programmed desorption and oxidation of isotopically-labelled ethanol, 12CH313CH2OH. The transformation pathways of preadsorbed ethanol in the absence of gaseous oxygen refer to dehydrogenation to acetaldehyde followed by its dissociation combined with oxidation by lattice oxygen. In the presence of gaseous oxygen, lattice oxygen is rapidly restored and the main products are acetaldehyde, CO2, and water. CO2 forms less easily on mixed oxides than on pure MnOx. The TOF of ethanol oxidation has been calculated assuming that the amount of adsorbed ethanol and CO2 produced during temperature-programmed oxidation (TPO) is a reliable indicator of the concentration of the active sites.
      Citation: Catalysts
      PubDate: 2017-11-10
      DOI: 10.3390/catal7110339
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 340: YCl3-Catalyzed Highly Selective Ring Opening
           of Epoxides by Amines at Room Temperature and under Solvent-Free
           Conditions

    • Authors: Wuttichai Natongchai, Rais Khan, Ali Alsalme, Rafik Shaikh
      First page: 340
      Abstract: A simple, efficient, and environmentally benign approach for the synthesis of β-amino alcohols is herein described. YCl3 efficiently carried out the ring opening of epoxides by amines to produce β-amino alcohols under solvent-free conditions at room temperature. This catalytic approach is very effective, with several aromatic and aliphatic oxiranes and amines. A mere 1 mol % concentration of YCl3 is enough to deliver β-amino alcohols in good to excellent yields with high regioselectivity.
      Citation: Catalysts
      PubDate: 2017-11-10
      DOI: 10.3390/catal7110340
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 341: Heterogeneous Catalysis on Metal Oxides

    • Authors: Jacques Védrine
      First page: 341
      Abstract: This review article contains a reminder of the fundamentals of heterogeneous catalysis and a description of the main domains of heterogeneous catalysis and main families of metal oxide catalysts, which cover acid-base reactions, selective partial oxidation reactions, total oxidation reactions, depollution, biomass conversion, green chemistry and photocatalysis. Metal oxide catalysts are essential components in most refining and petrochemical processes. These catalysts are also critical to improving environmental quality. This paper attempts to review the major current industrial applications of supported and unsupported metal oxide catalysts. Viewpoints for understanding the catalysts’ action are given, while applications and several case studies from academia and industry are given. Emphases are on catalyst description from synthesis to reaction conditions, on main industrial applications in the different domains and on views for the future, mainly regulated by environmental issues. Following a review of the major types of metal oxide catalysts and the processes that use these catalysts, this paper considers current and prospective major applications, where recent advances in the science of metal oxide catalysts have major economic and environmental impacts.
      Citation: Catalysts
      PubDate: 2017-11-10
      DOI: 10.3390/catal7110341
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 342: Green Synthesis of Ultraviolet Absorber
           2-Ethylhexyl Salicylate: Experimental Design and Artificial Neural Network
           Modeling

    • Authors: Shang-Ming Huang, Tzu-Hsiang Hung, Yung-Chuan Liu, Chia-Hung Kuo, Chwen-Jen Shieh
      First page: 342
      Abstract: 2-Ethylhexyl salicylate, an ultraviolet filter, is widely used to protect skin against sunlight-induced harmful effects in the cosmetic industry. In this study, the green synthesis of 2-ethylhexyl salicylate using immobilized lipase through a solvent-free and reduced pressure evaporation system was investigated. A Box–Behnken design was employed to develop an artificial neural network (ANN) model. The parameters for an optimal architecture of an ANN were set out: a quick propagation algorithm, a hyperbolic tangent transfer function, 10,000 iterations, and six nodes within the hidden layer. The best-fitting performance of the ANN was determined by the coefficient of determination and the root-mean-square error between the correlation of predicted and experimental data, indicating that the ANN displayed excellent data-fitting properties. Finally, the experimental conditions of synthesis were well established with the optimal parameters to obtain a high conversion of 2-ethylhexyl salicylate. In conclusion, this study efficiently replaces the traditional solvents with a green process for the synthesis of 2-ethylhexyl salicylate to avoid environmental contamination, and this process is well-modeled by a methodological ANN for optimization, which might be a benefit for industrial production.
      Citation: Catalysts
      PubDate: 2017-11-13
      DOI: 10.3390/catal7110342
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 343: Fine-Tuning Synthesis and Characterization
           of Mono-Sized H-Beta Zeolite-Supported Palladium-Iridium Nanoparticles and
           Application in the Selective Hydrogenation of Acetylene

    • Authors: Masood Sahooli, Mohammad Rahimpour, Mohammad Khorram
      First page: 343
      Abstract: In this research, a mono-sized Beta zeolite support synthesized by the solvothermal method was used in the selective acetylene to ethylene hydrogenation reaction with minimum coke build up on the catalyst surface. Tetrapropylammonium hydroxide (TPAOH), tetrapropylammonium bromide (TPABr), n-butylamine, and morpholine were used as structure direct agents (SDA) in the support to obtain various shapes. The characterization results show that although the Si/(Al+SDA) ratio has no effect on the phase purity of support, it has a remarkable effect on porosity, crystal size, shape, and structure of micropores. After comparing characterization results, the developed support, based on TPAOH, was selected and modified by different metals (Ce, Ir, Ag, and Pd) using the incipient wetness co-impregnation method. Since there is an interaction between selectivity and conversion, the optimum metal content in the synthesized catalysts and reaction condition were determined to achieve the desired acetylene conversion and ethylene selectivity. The physicochemical transformation of the developed optimum catalysts was determined using different techniques. Based on the characterization and cata-test results, the catalyst which contains 0.29% Ir and 0.08% Pd presents a better performance and higher stability compared to the other catalysts due to the moderate size and mono layer dispersion of the metals on the support. The experimental results show that acetylene conversion and ethylene selectivity approach 97% and 92% at 55 °C, respectively.
      Citation: Catalysts
      PubDate: 2017-11-13
      DOI: 10.3390/catal7110343
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 344: Fe-Doped TiO2 Supported on HY Zeolite for
           Solar Photocatalytic Treatment of Dye Pollutants

    • Authors: Ghania Foura, Nawel Chouchou, Ahcène Soualah, Kahina Kouachi, Matteo Guidotti, Didier Robert
      First page: 344
      Abstract: Zeolite-supported TiO2 and Fe-doped TiO2/zeolite photocatalysts were synthesized, aiming at improving the adsorption properties of the microporous support towards polluting dyes and the photocatalytic performance of TiO2 in the treatment of the adsorbed organics. The TiO2/HY zeolite catalyst exhibited the best performance in the photocatalytic degradation of methylene blue, MB, over 10 wt% TiO2/HY under UV light at 254 nm. The addition of Fe species in the synthesis mixture led to Fe-TiO2/HY catalyst. The combination of adequate zeolite, good titanium dioxide dispersion, and Fe doping led to a remarkable performance in the degradation of the model dye. Over a 10 wt% Fe-doped TiO2/HY catalyst a total removal of MB (>98%) was achieved after 60 min under very mild conditions and simple visible light irradiation.
      Citation: Catalysts
      PubDate: 2017-11-14
      DOI: 10.3390/catal7110344
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 345: Base Catalysis by Mono- and Polyoxometalates

    • Authors: Keigo Kamata, Kosei Sugahara
      First page: 345
      Abstract: In sharp contrast with acid-, photo-, and oxidation-catalysis by polyoxometalates, base catalysis by polyoxometalates has scarcely been investigated. The use of polyoxometalates as base catalysts have very recently received much attention and has been extensively investigated. Numerous mono- and polyoxometalate base catalyst systems effective for the chemical fixation of CO2, cyanosilylation of carbonyl compounds, and C–C bond forming reactions have been developed. Mono- and polyoxometalate base catalysts are classified into four main groups with respect to their structures: (a) monomeric metalates; (b) isopolyoxometalates; (c) heteropolyoxometalates; and (d) transition-metal-substituted polyoxometalates. This review article focuses on the relationship among the molecular structures, the basic properties, and the unique base catalysis of polyoxometalates on the basis of groups (a)–(d). In addition, reaction mechanisms including the specific activation of substrates and/or reagents such as the abstraction of protons, nucleophilic action toward substrates, and bifunctional action in combination with metal catalysts are comprehensively summarized.
      Citation: Catalysts
      PubDate: 2017-11-16
      DOI: 10.3390/catal7110345
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 346: Efficient Degradation of Refractory Organics
           Using Sulfate Radicals Generated Directly from WO3 Photoelectrode and the
           Catalytic Reaction of Sulfate

    • Authors: Jingyuan Zheng, Jinhua Li, Jing Bai, Xiaohan Tan, Qingyi Zeng, Linsen Li, Baoxue Zhou
      First page: 346
      Abstract: An environment-friendly method of efficiently degrading refractory organics using SO4−• generated directly from a WO3 photoelectrode and a catalytic reaction of sulfate was proposed, in which the cycling process of SO42− → SO4−• → SO42− was achieved in the treatment of organic pollutants without any other activator and without the continuous addition of sulfate. The results show that the removal efficiency for a typical refractory organics of methyl orange (MO) with 5 mg/L was up to 95% within 80 min, and merely 3% by photolysis and 19% by photocatalysis, respectively, under similar conditions. The rate constant for the disposal of MO at pH 2, in which SO4−• instead of HO• is the main oxidizer confirmed by radical scavenger experiment, is up to 5.21 × 10−4 s−1, which was ~6.6 times that (7.89 × 10−5 s−1) under neutral condition, in which HO• is the main oxidizer. The concentration of active persulfate (S2O82−, SO52−, and SO4−•) species at pH 2 was up to 0.38 mM, which was ~16-fold as much as that (0.023 mM) in neutral conditions. The method provides a new approach for the treatment and resource utilization of sulfate wastewater.
      Citation: Catalysts
      PubDate: 2017-11-17
      DOI: 10.3390/catal7110346
      Issue No: Vol. 7, No. 11 (2017)
       
  • Catalysts, Vol. 7, Pages 281: Hydroconversion of Waste Cooking Oil into
           Green Biofuel over Hierarchical USY-Supported NiMo Catalyst: A Comparative
           Study of Desilication and Dealumination

    • Authors: Zongwei Zhang, Qingfa Wang, Hao Chen, Xiangwen Zhang
      First page: 281
      Abstract: The hydroconversion of waste cooking oil into hydrocarbon fuel was investigated over the hierarchical USY zeolite-supported NiMo catalysts which were prepared by dealumination ((NH4)2SiF6)/desilication (NaOH). The physical and acidity properties of the hierarchical catalysts were characterized by X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) infrared spectroscopy of adsorbed pyridine (Py-IR), ammonia temperature-programmed desorption (NH3-TPD), and H2 temperature-programmed reduction (H2-TPR). The Brønsted/Lewis (B/L) acid distribution was little affected by dealumination and the acid density decreased significantly. However, the highly-desilicated catalysts decreased the B/L ratio obviously. Therefore, many more Mo species in the NiMoO4− and MoO3 phases were produced in the AHFS-treated catalysts, while more high-valence-state Mo species in the NiMoO4− phase were formed in the NaOH-treated catalysts. The AHFS-treated catalysts showed higher catalytic activity and better DCO2 selectivity and selective cracking for jet fuel. The 42.3% selectivity of jet fuel and 13.5% selectivity of jet-range aromatics was achieved over the 8 wt % (NH4)2SiF6-treated catalyst with 67% DCO2 selectivity.
      Citation: Catalysts
      PubDate: 2017-09-22
      DOI: 10.3390/catal7100281
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 282: Active Site Mimicry of Glutathione
           Peroxidase by Glutathione Imprinted Selenium-Containing Trypsin

    • Authors: Yi Huang, Dan-Yang Ge, Hui Zong, Ju-Xin Yin, Xiao-Nan Qu, Shao-Wu Lv
      First page: 282
      Abstract: In order to overcome the instability of natural glutathione peroxidase (GPx), scientists endeavor to produce GPx mimics. The popular method first uses biological imprinting (BI) to produce the substrate binding sites and then employs chemical mutation (CM) to obtain the catalytic site. However, BICM has a drawback in that the catalytic site is not clear. Some researchers therefore tried to change the order of the method. These new GPx mimics were prepared by first producing the catalytic site through chemical mutation, and then employing biological imprinting to produce the substrate binding sites (CMBI). It has a clear catalytic site, but its determination of enzyme activity and kinetic analysis are still not elucidated. In this study, we used CMBI to synthesize a GPx mimic using trypsin as the imprinted molecule and GSSG as the template molecule and compared the enzyme activity of the four intermediates (Trypsin-SeO2H (TSeO2H), Trypsin-Se-SG (TSeSG), Imprinted Trypsin-Se-SG (ITSeSG), Cross-linked Imprinted Trypsin-Se-SG (CITSeSG), we analyzed the properties of intermediate products. All values are the means of at least four determinations, ITSeSG was produced from TSeSG through bio-imprinting, the activity of GPx mimics synthesized by CMBI was 5.7 times greater than native GPx, because of bio-imprinting make KmGSH value of the mimics decreased from 4.82 ± 0.27 mM (TSeSG) to 0.52 ± 0.05 mM (ITSeSG). This proves that bio-imprinting is the reason for increased substrate binding capability.
      Citation: Catalysts
      PubDate: 2017-09-22
      DOI: 10.3390/catal7100282
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 283: Reactive Magnetron Sputter Deposition of
           Bismuth Tungstate Coatings for Water Treatment Applications under Natural
           Sunlight

    • Authors: Marina Ratova, Rafaela Marcelino, Patterson de Souza, Camila Amorim, Peter Kelly
      First page: 283
      Abstract: Bismuth complex oxides, in particular, bismuth tungstate, have recently attracted attention as promising photocatalytic materials for water treatment processes. In the present work, photocatalytic bismuth tungstate films were prepared by pulsed direct current (DC) reactive magnetron sputtering of Bi and W targets in an Ar/O2 atmosphere onto spherically-shaped glass beads. The uniform coverage of the substrate was enabled by the use of oscillating bowl placed underneath the magnetrons. The atomic ratio of Bi/W was varied through the variation of the power applied to the magnetrons. The deposited coatings were analyzed by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy and atomic force microscopy. The photocatalytic properties of the films were studied via the methylene blue (MB) degradation process under artificial (fluorescent light) and natural (sunlight) irradiation, and compared to the photocatalytic performance of titanium dioxide coatings deposited onto identical substrates. The results showed that the photocatalytic performance of bismuth tungstate and bismuth oxide-coated beads was superior to that exhibited by TiO2-coated beads. Overall, reactive magnetron co-sputtering has been shown to be a promising technique for deposition of narrow band gap bismuth-based semiconducting oxides onto irregularly-shaped substrates for potential use in water treatment applications.
      Citation: Catalysts
      PubDate: 2017-09-23
      DOI: 10.3390/catal7100283
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 284: Synthesis of Stereodiblock Polybutadiene
           Using Cp*Nd(BH4)2(thf)2 as a Catalyst

    • Authors: Ryo Tanaka, Yuto Shinto, Yuushou Nakayama, Takeshi Shiono
      First page: 284
      Abstract: Butadiene polymerization, in both a highly cis- and trans-specific manner, was achieved by using a Cp*Nd(BH4)2(thf)2–Bu2Mg system as an initiator. The cis-/trans- ratio can be tuned by the amount of trialkylaluminum-depleted modified methylaluminoxane (dMMAO). The cis-regularity of the polymer was much higher than those obtained by Nd(BH4)3(thf)3. The molecular weight of cis-regular polymer was increased according to polymer yield, showing that there was no termination or chain transfer reaction during the polymerization. Synthesis of stereodiblock polybutadiene, which showed a high melting temperature (Tm) compared with stereodiblock polyisoprene, was also performed by the addition dMMAO during the polymerization.
      Citation: Catalysts
      PubDate: 2017-09-25
      DOI: 10.3390/catal7100284
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 285: Two-Dimensional Material Molybdenum
           Disulfides as Electrocatalysts for Hydrogen Evolution

    • Authors: Lei Yang, Ping Liu, Jing Li, Bin Xiang
      First page: 285
      Abstract: Recently, transition metal dichalcogenides (TMDs), represented by MoS2, have been proven to be a fascinating new class of electrocatalysts in hydrogen evolution reaction (HER). The rich chemical activities, combined with several strategies to regulate its morphologies and electronic properties, make MoS2 very attractive for understanding the fundamentals of electrocatalysis. In this review, recent developments in using MoS2 as electrocatalysts for the HER with high activity are presented. The effects of edges on HER activities of MoS2 are briefly discussed. Then we demonstrate strategies to further enhance the catalytic performance of MoS2 by improving its conductivity or engineering its structure. Finally, the key challenges to the industrial application of MoS2 in electrocatalytic hydrogen evolution are also pointed out.
      Citation: Catalysts
      PubDate: 2017-09-25
      DOI: 10.3390/catal7100285
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 286: Hydrogen Production from Cyclic Chemical
           Looping Steam Methane Reforming over Yttrium Promoted Ni/SBA-16 Oxygen
           Carrier

    • Authors: Sanaz Daneshmand-Jahromi, Mohammad Rahimpour, Maryam Meshksar, Ali Hafizi
      First page: 286
      Abstract: In this work, the modification of Ni/SBA-16 oxygen carrier (OC) with yttrium promoter is investigated. The yttrium promoted Ni-based oxygen carrier was synthesized via co-impregnation method and applied in chemical looping steam methane reforming (CL-SMR) process, which is used for the production of clean energy carrier. The reaction temperature (500–750 °C), Y loading (2.5–7.4 wt. %), steam/carbon molar ratio (1–5), Ni loading (10–30 wt. %) and life time of OCs over 16 cycles at 650 °C were studied to investigate and optimize the structure of OC and process temperature with maximizing average methane conversion and hydrogen production yield. The synthesized OCs were characterized by multiples techniques. The results of X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) of reacted OCs showed that the presence of Y particles on the surface of OCs reduces the coke formation. The smaller NiO species were found for the yttrium promoted OC and therefore the distribution of Ni particles was improved. The reduction-oxidation (redox) results revealed that 25Ni-2.5Y/SBA-16 OC has the highest catalytic activity of about 99.83% average CH4 conversion and 85.34% H2 production yield at reduction temperature of 650 °C with the steam to carbon molar ratio of 2.
      Citation: Catalysts
      PubDate: 2017-09-25
      DOI: 10.3390/catal7100286
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 287: Enzymatic Systems for Cellulose Acetate
           Degradation

    • Authors: Oskar Haske-Cornelius, Alessandro Pellis, Gregor Tegl, Stefan Wurz, Bodo Saake, Roland Ludwig, Andries Sebastian, Gibson Nyanhongo, Georg Guebitz
      First page: 287
      Abstract: Cellulose acetate (CA)-based materials, like cigarette filters, contribute to landscape pollution challenging municipal authorities and manufacturers. This study investigates the potential of enzymes to degrade CA and to be potentially incorporated into the respective materials, enhancing biodegradation. Deacetylation studies based on Liquid Chromatography-Mass Spectrometry-Time of Flight (LC-MS-TOF), High Performance Liquid Chromatography (HPLC), and spectrophotometric analysis showed that the tested esterases were able to deacetylate the plasticizer triacetin (glycerol triacetate) and glucose pentaacetate (cellulose acetate model compound). The most effective esterases for deacetylation belong to the enzyme family 2 (AXE55, AXE 53, GAE), they deacetylated CA with a degree of acetylation of up to 1.8. A combination of esterases and cellulases showed synergistic effects, the absolute glucose recovery for CA 1.8 was increased from 15% to 28% when an enzymatic deacetylation was performed. Lytic polysaccharide monooxygenase (LPMO), and cellobiohydrolase were able to cleave cellulose acetates with a degree of acetylation of up to 1.4, whereas chitinase showed no activity. In general, the degree of substitution, chain length, and acetyl group distribution were found to affect CA degradation. This study shows that, for a successful enzyme-based deacetylation system, a cocktail of enzymes, which will randomly cleave and generate shorter CA fragments, is the most suitable.
      Citation: Catalysts
      PubDate: 2017-09-27
      DOI: 10.3390/catal7100287
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 288: Polycyclic Ketone Monooxygenase (PockeMO): A
           Robust Biocatalyst for the Synthesis of Optically Active Sulfoxides

    • Authors: Gonzalo de Gonzalo, Maximilian Fürst, Marco Fraaije
      First page: 288
      Abstract: A recently discovered, moderately thermostable Baeyer-Villiger monooxygenase, polycyclic ketone monooxygenase (PockeMO), from Thermothelomyces thermophila has been employed as a biocatalyst in a set of asymmetric sulfoxidations. The enzyme was able to catalyze the oxidation of various alkyl aryl sulfides with good selectivities and moderate to high activities. The biocatalytic performance was able to be further increased by optimizing some reaction parameters, such as the addition of 10% v v−1 of water miscible solvents or toluene, or by performing the conversion at a relatively high temperature (45 °C). PockeMO was found to display an optimum activity at sulfide concentrations of 50 mM, while it can also function at 200 mM. Taken together, the data show that PockeMO can be used as robust biocatalyst for the synthesis of optically active sulfoxides.
      Citation: Catalysts
      PubDate: 2017-09-27
      DOI: 10.3390/catal7100288
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 289: Study of 8 Types of Glutathione Peroxidase
           Mimics Based on β-Cyclodextrin

    • Authors: Liwu Wang, Xiaonan Qu, Ying Xie, Shaowu Lv
      First page: 289
      Abstract: Glutathione peroxidase is key for the removal of H2O2 and other hydroperoxides and therefore, it has an important role in the maintenance of the reactive oxygen species (ROS) metabolic balance in vivo. The native enzymes of the glutathione peroxidase family (GPx) have many defects, such as instability in vitro and poor availability. GPx mimetics has become a topic of considerable interest in artificial enzyme research. Many forms of GPx mimics have been synthesized, by including selenium and tellurium (double-bridged and single-bridged, 2-substituted and 6-substituted) in a mother molecule but differences the GPx mimics enzymatic activity have rarely been compared. We designed and synthesized eight cyclodextrin derivatives and used two types of enzyme assays to determine their activities. The results show that: (a) tellurium-containing GPx mimics have higher activity than that of selenium-containing GPx mimics; (b) dual-bridged mimics have higher activity than bis-bridged mimics; and (c) 2-position modified cyclodextrin has higher activity than 6-position modified cyclodextrin.
      Citation: Catalysts
      PubDate: 2017-09-28
      DOI: 10.3390/catal7100289
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 290: Co-Production of Ethanol and 1,2-Propanediol
           via Glycerol Hydrogenolysis Using Ni/Ce–Mg Catalysts: Effects of
           Catalyst Preparation and Reaction Conditions

    • Authors: Russel Menchavez, Matthew Morra, B. He
      First page: 290
      Abstract: Crude glycerol from biodiesel production is a biobased material capable of co-producing biofuels and chemicals. This study aimed to develop a line of Ni catalysts supported on cerium–magnesium (Ce–Mg) to improve the process efficiency of glycerol hydrogenolysis for ethanol and 1,2-propanediol (1,2-PDO). Results showed that catalytic activity was greatly improved by changing the preparation method from impregnation to deposition precipitation (DP), and by adjusting calcination temperatures. Prepared via DP, the catalysts of 25 wt % Ni supported on Ce–Mg (9:1 mol/mol) greatly improved the effectiveness in glycerol conversion while maintaining the selectivities to ethanol and 1,2-PDO. Calcination at 350 °C provided the catalysts better selectivities of 15.61% to ethanol and 67.93% to 1,2-PDO. Increases in reaction temperature and time improved the conversion of glycerol and the selectivity to ethanol, but reduced the selectivity to 1,2-PDO. A lower initial water content led to a higher conversion of glycerol, but lower selectivities to ethanol and 1,2-PDO. Higher hydrogen application affected the glycerol conversion rate positively, but the selectivities to ethanol and 1,2-PDO negatively. A comparison to the commercial Raney® Ni catalyst showed that the Ni/Ce–Mg catalyst developed in this study showed a better potential for the selective co-production of ethanol and 1,2-PDO from glycerol hydrogenolysis.
      Citation: Catalysts
      PubDate: 2017-09-29
      DOI: 10.3390/catal7100290
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 291: Conductive Cotton Filters for Affordable and
           Efficient Water Purification

    • Authors: Fang Li, Qin Xia, Qianxun Cheng, Mingzhi Huang, Yanbiao Liu
      First page: 291
      Abstract: It is highly desirable to develop affordable, energy-saving, and highly-effective technologies to alleviate the current water crisis. In this work, we reported a low-cost electrochemical filtration device composing of a conductive cotton filter anode and a Ti foil cathode. The device was operated by gravity feed. The conductive cotton filter anodes were fabricated by a facile dying method to incorporate carbon nanotubes (CNTs) as fillers. The CNTs could serve as adsorbents for pollutants adsorption, as electrocatalysts for pollutants electrooxidation, and as conductive additives to render the cotton filters highly conductive. Cellulose-based cotton could serve as low-cost support to ‘host’ these CNTs. Upon application of external potential, the developed filtration device could not only achieve physically adsorption of organic compounds, but also chemically oxide these compounds on site. Three model organic compounds were employed to evaluate the oxidative capability of the device, i.e., ferrocyanide (a model single-electron-transfer electron donor), methyl orange (MO, a common recalcitrant azo-dye found in aqueous environments), and antibiotic tetracycline (TC, a common antibiotic released from the wastewater treatment plants). The devices exhibited a maximum electrooxidation flux of 0.37 mol/h/m2 for 5.0 mmol/L ferrocyanide, of 0.26 mol/h/m2 for 0.06 mmol/L MO, and of 0.9 mol/h/m2 for 0.2 mmol/L TC under given experimental conditions. The effects of several key operational parameters (e.g., total cell potential, CNT amount, and compound concentration) on the device performance were also studied. This study could shed some light on the good design of effective and affordable water purification devices for point-of-use applications.
      Citation: Catalysts
      PubDate: 2017-09-29
      DOI: 10.3390/catal7100291
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 292: Morpholine-Modified Pd/γ-Al2O3@ASMA Pellet
           Catalyst with Excellent Catalytic Selectivity in the Hydrogenation of
           p-Chloronitrobenzene to p-Chloroaniline

    • Authors: Wei Wang, Wenlong Xu, Kedar Thapa, Xiaorui Yang, Jinhua Liang, Liyan Zhu, Jianliang Zhu
      First page: 292
      Abstract: An amino poly (styrene-co-maleic anhydride) polymer (ASMA) encapsulated γ-Al2O3 pellet material has been synthesized successfully. After loading with Pd species and modified with morpholine, the inorganic-organic hybrid material shows an excellent catalytic property in the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). In this procedure, morpholine can connect with the polymer layer in a form of amide bond and acts as an unparalleled immobilized dechlorination inhibitor, which can avoid further dechlorination efficiently and keeps stability due to the repulsive effect from the surviving C-O-C bond. The catalyst as prepared was characterized by using XRD, TGA, SEM, TEM, FT-IR, and ICP-OES, and it was further tested in the selective hydrogenation of p-CNB. It shows a supreme catalytic activity (almost 100%) and selectivity (up to 99.51%) after recycling for even 10 times, much superior to the blank alumina supported palladium (47.09%).
      Citation: Catalysts
      PubDate: 2017-09-30
      DOI: 10.3390/catal7100292
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 293: Total Oxidation of Naphthalene with
           Zirconia-Supported Cobalt, Copper and Nickel Catalysts

    • Authors: María Leguizamón Aparicio, Marco Ocsachoque, Delia Gazzoli, Irma Botto, Ileana Lick
      First page: 293
      Abstract: ZrO2 nH2O (hydrogel) impregnated with transition metals (Cu, Co, and Ni) was studied in this work as a precursor for the synthesis of CuO/ZrO2 (CuZ), CoOx/ZrO2 (CoZ), and NiO/ZrO2 (NiZ) catalysts, employed in the naphthalene oxidation reaction. Fresh and catalytically used materials were characterized by different physicochemical techniques, to compare the bulk and surface behavior, with particular attention to the effect of the supported metal species’ properties on the catalytic activity. Techniques such as X-ray diffraction (XRD), temperature programmed reduction (TPR), differential scanning calorimetry (DSC), Brunauer–Emmett–Teller (BET) surface area analyzer, diffuse reflectance spectroscopy (DRS UV–vis), and Raman spectroscopy, allow for establishing structural and textural aspects of the support, as well as the surface coordination and the accessibility of supported species. Results were in agreement with the CuZ > CoZ > NiZ sequence for the activity in naphthalene oxidation reaction. Electronic properties, ionic sizes, oxide phase deposition on the support surface, reducibility, metal–support interaction, and local site symmetry of metals seem to be decisive factors for the catalytic interaction with the gaseous phase.
      Citation: Catalysts
      PubDate: 2017-09-30
      DOI: 10.3390/catal7100293
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 294: Transformation of Sugar Maple Bark through
           Catalytic Organosolv Pulping

    • Authors: Georges Koumba-Yoya, Tatjana Stevanovic
      First page: 294
      Abstract: The catalytic organosolv pulping of sugar maple bark was performed adopting the concept of forest biorefinery in order to transform bark into several valuable products. Our organosolv process, consisting of pre-extracting the lignocellulosic material followed by pulping with ferric chloride as a catalyst, was applied to sugar maple bark. The pre-extraction step has yielded a mixture of phenolic extractives, applicable as antioxidants. The organosolv pulping of extractives-free sugar maple bark yielded a solid cellulosic pulp (42.3%) and a black liquor containing solubilized bark lignin (24.1%) and products of sugars transformation (22.9% of hemicelluloses), mainly represented by furfural (0.35%) and 5-hydroxymethyl furfural (HMF, 0.74%). The bark cellulosic pulp was determined to be mainly constituted of glucose, with a high residual lignin content, probably related to the protein content of the original bark (containing cambium tissue). The biorefinery approach to the transformation of a solid bark residue into valuable biopolymers (lignin and cellulose) along with phenolic antioxidants from pre-extraction and the HMF derivatives from black liquor (applicable for 2,5-diformylfuran production) is an example of a catalytic process reposing on sustainable engineering and green chemistry concepts.
      Citation: Catalysts
      PubDate: 2017-09-30
      DOI: 10.3390/catal7100294
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 295: Promoting the Synthesis of Ethanol and
           Butanol by Salicylic Acid

    • Authors: Jinxin Zou, Lei Wang, Peijun Ji
      First page: 295
      Abstract: Multiwalled carbon nanotubes (MWCNTs) were functionalized with salicylic acid (SA). The copper-cobalt catalyst was impregnated on the SA functionalized MWCNTs (SA-MWCNTs). The catalyst copper-cobalt/SA-MWCNTs was used to catalyze the synthesis of alcohols from synthesis gas. Salicylic acid can promote the synthesis of ethanol and butanol from synthesis gas, thus reducing the synthesis of methanol. This work demonstrated that salicylic acid not only can be used to functionalize carbon nanotubes, but also can enhance the production of ethanol and butanol from synthesis gas. On the other hand, the copper-cobalt catalyst supported on MWCNTs of 30 nm in diameter can synthesize more ethanol and butanol than supported on MWCNTs of 15 and 50 nm in diameter, indicating that the diameter of MWCNTs also has an effect on the synthesis of alcohols.
      Citation: Catalysts
      PubDate: 2017-10-01
      DOI: 10.3390/catal7100295
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 296: Immobilization of Pyrroloquinoline
           Quinone-Dependent Alcohol Dehydrogenase with a Polyion Complex and Redox
           Polymer for a Bioanode

    • Authors: Yuki Sakurada, Kouta Takeda, Hiroyuki Ohno, Nobuhumi Nakamura
      First page: 296
      Abstract: A bioanode for ethanol oxidation was prepared by immobilizing the recombinant pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase from Pseudomonas putida KT 2440 (PpADH) with polyion complex (PIC) and redox polymer. The PIC based on poly-l-lysine (PLL) and poly-l-glutamic acid (PGA) was suitable for immobilizing PpADH on the electrode. PpADH was immobilized using only one redox polymer, aminoferrocene, which was attached to the PGA backbone (PGA-AmFc) on the electrode. The anodic current density at 0.6 V (vs. Ag/AgCl) was 22.6 μA·cm−2. However, when the number of the cycles was increased, the catalytic current drastically decreased. PpADH was immobilized using PGA-AmFc and PIC on the electrode. The anodic current density at 0.5 V (vs. Ag/AgCl) was 47.3 μA·cm−2, and the performance maintained 74% of the initial value after five cycles. This result indicated that the combination of PIC and PGA-AmFc was suitable for the immobilization of PpADH on the electrode. In addition, the long-term stability and catalytic current density were improved by using the large surface area afforded by the gold nanoparticles.
      Citation: Catalysts
      PubDate: 2017-10-03
      DOI: 10.3390/catal7100296
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 297: A Review on the Production and Purification
           of Biomass-Derived Hydrogen Using Emerging Membrane Technologies

    • Authors: Hang Yin, Alex C.K. Yip
      First page: 297
      Abstract: Hydrogen energy systems are recognized as a promising solution for the energy shortage and environmental pollution crises. To meet the increasing demand for hydrogen, various possible systems have been investigated for the production of hydrogen by efficient and economical processes. Because of its advantages of being renewable and environmentally friendly, biomass processing has the potential to become the major hydrogen production route in the future. Membrane technology provides an efficient and cost-effective solution for hydrogen separation and greenhouse gas capture in biomass processing. In this review, the future prospects of using gas separation membranes for hydrogen production in biomass processing are extensively addressed from two perspectives: (1) the current development status of hydrogen separation membranes made of different materials and (2) the feasibility of using these membranes for practical applications in biomass-derived hydrogen production. Different types of hydrogen separation membranes, including polymeric membranes, dense metal membranes, microporous membranes (zeolite, metal-organic frameworks (MOFs), silica, etc.) are systematically discussed in terms of their fabrication methods, gas permeation performance, structure stability properties, etc. In addition, the application feasibility of these membranes in biomass processing is assessed from both practical and economic perspectives. The benefits and possibilities of using membrane reactors for hydrogen production in biomass processing are also discussed. Lastly, we summarize the limitations of the currently available hydrogen membranes as well as the gaps between research achievements and industrial application. We also propose expected research directions for the future development of hydrogen gas membrane technology.
      Citation: Catalysts
      PubDate: 2017-10-06
      DOI: 10.3390/catal7100297
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 298: HDO of Methyl Palmitate over
           Silica-Supported Ni Phosphides: Insight into Ni/P Effect

    • Authors: Irina Deliy, Ivan Shamanaev, Evgeny Gerasimov, Vera Pakharukova, Ilya Yakovlev, Olga Lapina, Pavel Aleksandrov, Galina Bukhtiyarova
      First page: 298
      Abstract: Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH3COO)2) and ((NH4)2HPO4) as a precursor. The NixPy/SiO2 catalysts were characterized using chemical analysis N2 physisorption, XRD, TEM, 31P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO) was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h−1. The Ni/P ratio was found to affect the nickel phosphide phase composition, POx groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of POx groups’ content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis), we proposed that the enhancement of acid POx groups’ content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis.
      Citation: Catalysts
      PubDate: 2017-10-04
      DOI: 10.3390/catal7100298
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 299: Biotransformation of Ergostane Triterpenoid
           Antcin K from Antrodia cinnamomea by Soil-Isolated Psychrobacillus sp. AK
           1817

    • Authors: Chien-Min Chiang, Tzi-Yuan Wang, An-Ni Ke, Te-Sheng Chang, Jiumn-Yih Wu
      First page: 299
      Abstract: Antcin K is one of the major ergostane triterpenoids from the fruiting bodies of Antrodia cinnamomea, a parasitic fungus that grows only on the inner heartwood wall of the aromatic tree Cinnamomum kanehirai Hay (Lauraceae). To search for strains that have the ability to biotransform antcin K, a total of 4311 strains of soil bacteria were isolated, and their abilities to catalyze antcin K were determined by ultra-performance liquid chromatography analysis. One positive strain, AK 1817, was selected for functional studies. The strain was identified as Psychrobacillus sp., based on the DNA sequences of the 16S rRNA gene. The biotransformation metabolites were purified with the preparative high-performance liquid chromatography method and identified as antcamphin E and antcamphin F, respectively, based on the mass and nuclear magnetic resonance spectral data. The present study is the first to report the biotransformation of triterpenoids from A. cinnamomea (Antrodia cinnamomea).
      Citation: Catalysts
      PubDate: 2017-10-11
      DOI: 10.3390/catal7100299
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 300: PEG1000-Based Dicationic Acidic Ionic
           Liquid/Solvent-Free Conditions: An Efficient Catalytic System for the
           Synthesis of Bis(Indolyl)methanes

    • Authors: Yi-Ming Ren, Mao-Dong Xu, Xiong Wang
      First page: 300
      Abstract: An efficient procedure has been researched for the solvent-free synthesis of bis(indolyl)methanes via a one-pot reaction of indoles and aldehydes or ketones promoted by PEG1000-based dicationic acidic ionic liquid (PEG1000-DAIL). The catalyst PEG1000-DAIL could be reused seven times with excellent results. Furthermore, through this method, a highly chemoselective reaction of benzaldehyde and acetophenone with indole could be achieved.
      Citation: Catalysts
      PubDate: 2017-10-11
      DOI: 10.3390/catal7100300
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 301: Flame-Made Cu/TiO2 and Cu-Pt/TiO2
           Photocatalysts for Hydrogen Production

    • Authors: Massimo Bernareggi, Maria Dozzi, Luca Bettini, Anna Ferretti, Gian Chiarello, Elena Selli
      First page: 301
      Abstract: The effect of Cu or Cu-Pt nanoparticles in TiO2 photocatalysts prepared by flame spray pyrolysis in one step was investigated in hydrogen production from methanol photo-steam reforming. Two series of titanium dioxide photocatalysts were prepared, containing either (i) Cu nanoparticles (0.05–0.5 wt%) or (ii) both Cu (0 to 0.5 wt%) and Pt (0.5 wt%) nanoparticles. In addition, three photocatalysts obtained either by grafting copper and/or by depositing platinum by wet methods on flame-made TiO2 were also investigated. High hydrogen production rates were attained with copper-containing photocatalysts, though their photoactivity decreased with increasing Cu loading, whereas the photocatalysts containing both Cu and Pt nanoparticles exhibit a bell-shaped photoactivity trend with increasing copper content, the highest hydrogen production rate being attained with the photocatalyst containing 0.05 wt% Cu.
      Citation: Catalysts
      PubDate: 2017-10-16
      DOI: 10.3390/catal7100301
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 302: Improved Catalytic Performance of Lipase
           Supported on Clay/Chitosan Composite Beads

    • Authors: Ni Tu, Jianxin Shou, Huaping Dong, Jin Huang, Yimin Li
      First page: 302
      Abstract: Clay/chitosan composite beads were prepared and used as the carrier to support lipase by adsorption, to improve the activity and stability of lipase in the hydrolysis of olive oil. Under conditions of pH 6.0, 25 °C and adsorption for 10 h, immobilized lipases on chitosan bead (CB–lipase) and three clay/chitosan composite beads, at different clay to chitosan proportions of 1:8 (CCB-8-lipase), 1:5 (CCB-5-lipase) and 1:3 (CCB-3-lipase), were prepared. By comparing the activity of these immobilized lipases, CCB-5-lipase showed the highest activity, followed by CCB-8-lipase > CCB-3-lipase > CB-lipase; this improvement was attributed to the synergetic effect of enrichment of olive oil by clay at the reaction surface and better biocompatibility of chitosan with lipase molecules. The optimum pH and temperature in the reaction respectively changed from 7.0 and 30 °C for free lipase to 7.5 and 35 °C for immobilized forms. Furthermore, the thermal stability and repeated usability of these immobilized lipases were sequenced as CCB-3-lipase > CCB-5-lipase > CCB-8-lipase > CB–lipase, due to greater rigidity of immobilized lipase with the addition of clay, which was further confirmed by SEM. The study shows that the incorporation of clay with chitosan creates a good synergetic effect to improve the catalytic performance of immobilized lipase on clay/chitosan composite.
      Citation: Catalysts
      PubDate: 2017-10-13
      DOI: 10.3390/catal7100302
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 303: Reactivity of Trapped and Accumulated
           Electrons in Titanium Dioxide Photocatalysis

    • Authors: Shigeru Kohtani, Akira Kawashima, Hideto Miyabe
      First page: 303
      Abstract: Electrons, photogenerated in conduction bands (CB) and trapped in electron trap defects (Tids) in titanium dioxide (TiO2), play crucial roles in characteristic reductive reactions. This review summarizes the recent progress in the research on electron transfer in photo-excited TiO2. Particularly, the reactivity of electrons accumulated in CB and trapped at Tids on TiO2 is highlighted in the reduction of molecular oxygen and molecular nitrogen, and the hydrogenation and dehalogenation of organic substrates. Finally, the prospects for developing highly active TiO2 photocatalysts are discussed.
      Citation: Catalysts
      PubDate: 2017-10-13
      DOI: 10.3390/catal7100303
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 304: Brookite: Nothing New under the Sun'

    • Authors: Matteo Monai, Tiziano Montini, Paolo Fornasiero
      First page: 304
      Abstract: Advances in the synthesis of pure brookite and brookite-based TiO2 materials have opened the way to fundamental and applicative studies of the once least known TiO2 polymorph. Brookite is now recognized as an active phase, in some cases showing enhanced performance with respect to anatase, rutile or their mixture. The peculiar structure of brookite determines its distinct electronic properties, such as band gap, charge–carrier lifetime and mobility, trapping sites, surface energetics, surface atom arrangements and adsorption sites. Understanding the relationship between these properties and the photocatalytic performances of brookite compared to other TiO2 polymorphs is still a formidable challenge, because of the interplay of many factors contributing to the observed efficiency of a given photocatalyst. Here, the most recent advances in brookite TiO2 material synthesis and applications are summarized, focusing on structure/activity relation studies of phase and morphology-controlled materials. Many questions remain unanswered regarding brookite, but one answer is clear: Is it still worth studying such a hard-to-synthesize, elusive TiO2 polymorph' Yes.
      Citation: Catalysts
      PubDate: 2017-10-13
      DOI: 10.3390/catal7100304
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 305: Recent Advances in Graphene Based TiO2
           

    • Authors: Rita Giovannetti, Elena Rommozzi, Marco Zannotti, Chiara Anna D’Amato
      First page: 305
      Abstract: Synthetic dyes are widely used in textile, paper, food, cosmetic, and pharmaceutical industries. During industrial processes, some of these dyes are released into the wastewater and their successive release into rivers and lakes produces serious environmental problems. TiO2 is one of the most widely studied and used photocatalysts for environmental remediation. However, it is mainly active under UV-light irradiation due to its band gap of 3.2 eV, while it shows low efficiency under the visible light spectrum. Regarding the exploration of TiO2 activation in the visible light region of the total solar spectrum, the incorporation of carbon nanomaterials, such as graphene, in order to form carbon-TiO2 composites is a promising area. Graphene, in fact, has a large surface area which makes it a good adsorbent for organic pollutants removal through the combination of electrostatic attraction and π-π interaction. Furthermore, it has a high electron mobility and therefore it reduces the electron-hole pair recombination, improving the photocatalytic activity of the semiconductor. In recent years, there was an increasing interest in the preparation of graphene-based TiO2 photocatalysts. The present short review describes the recent advances in TiO2 photocatalyst coupling with graphene materials with the aim of extending the light absorption of TiO2 from UV wavelengths into the visible region, focusing on recent progress in the design and applications in the photocatalytic degradation of synthetic dyes.
      Citation: Catalysts
      PubDate: 2017-10-16
      DOI: 10.3390/catal7100305
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 306: Application of Artificial Neural Networks
           for Catalysis: A Review

    • Authors: Hao Li, Zhien Zhang, Zhijian Liu
      First page: 306
      Abstract: Machine learning has proven to be a powerful technique during the past decades. Artificial neural network (ANN), as one of the most popular machine learning algorithms, has been widely applied to various areas. However, their applications for catalysis were not well-studied until recent decades. In this review, we aim to summarize the applications of ANNs for catalysis research reported in the literature. We show how this powerful technique helps people address the highly complicated problems and accelerate the progress of the catalysis community. From the perspectives of both experiment and theory, this review shows how ANNs can be effectively applied for catalysis prediction, the design of new catalysts, and the understanding of catalytic structures.
      Citation: Catalysts
      PubDate: 2017-10-18
      DOI: 10.3390/catal7100306
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 307: Concept of Vaporized Urea Dosing in
           Selective Catalytic Reduction

    • Authors: Rafal Sala, Piotr Bielaczyc, Marek Brzezanski
      First page: 307
      Abstract: This work tried to identify the influence of dosing vaporized urea solution in a selective catalytic reduction (SCR) system. In the SCR method, optimising the urea evaporation and mixing properties can significantly improve the NOx conversion efficiency in the catalyst. It can also exert a positive effect on the uniformity of NH3 concentration distribution across the catalyst face. The concept of an electrically evaporated urea-dosing system was investigated and it was found that urea pre-heating prior to introduction into the exhaust gas is favourable for enhancing NOx removal under steady-state and transient engine operation. In the urea evaporating system the heating chamber was of a cylindrical tube shape and the urea vapour was introduced into the exhaust by means of a Venturi orifice. The concept urea dosing was only a custom-made solution, but proved to be superior to the regular dosing system operating in the liquid phase.
      Citation: Catalysts
      PubDate: 2017-10-19
      DOI: 10.3390/catal7100307
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 308: Alcohol Dehydrogenation on Kraft
           Lignin-Derived Chars with Surface Basicity

    • Authors: Francisco García-Mateos, Imane Moulefera, Juana Rosas, Abdelghani Benyoucef, José Rodríguez-Mirasol, Tomás Cordero
      First page: 308
      Abstract: The properties of lignin and its potential as a renewable source make it an ideal precursor for carbon products. Specifically, the high content of Na observed in Kraft lignin makes this industrial by-product an interesting precursor for the preparation of catalysts for different applications. In this work, basic activated carbons with different textural properties and surface chemistry were obtained from Kraft lignin by direct carbonization at various temperatures. The influence of a further washing treatment and partial gasification with CO2 was also evaluated. The carbon catalysts were tested as catalysts for the alcohol decomposition reaction. In this sense, 2-propanol, a molecule widely used for testing the acidic-basic character of heterogeneous catalysts, was selectively transformed into acetone, meanwhile, ethanol and methanol yielded mainly acetaldehyde and formaldehyde, respectively.
      Citation: Catalysts
      PubDate: 2017-10-19
      DOI: 10.3390/catal7100308
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 309: Synthesis of Biolubricant Basestocks from
           Epoxidized Soybean Oil

    • Authors: Rosa Turco, Riccardo Tesser, Rosa Vitiello, Vincenzo Russo, Salvatore Andini, Martino Di Serio
      First page: 309
      Abstract: This work deals with the preparation of biolubricant basestocks through the ring-opening reaction of epoxidized soybean oil (ESO) by alcohols in presence of solid acid catalysts (SAC-13 resin). To this end, different experimental runs were carried out in a lab-scale reactor, analyzing the effect of the alcohol (methanol, ethanol, 2-propanol, 2-butanol), catalyst mass loading (from 1 to 10 wt % with respect to the oil mass) and operating temperature (60–90 °C). The main focus of investigation was oxirane conversion. The study was complemented by FT-IR, 1H NMR and kinematic viscosity characterization of the different products of the ring-opening reaction. Experimental conversion data were fitted through a suitable kinetic model. Values of the best-fitting parameters in terms of rate constant, activation energy and catalyst reaction order were obtained, and were potentially useful for the design of an industrial process.
      Citation: Catalysts
      PubDate: 2017-10-19
      DOI: 10.3390/catal7100309
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 310: Water–Gas Shift Reaction over Ni/CeO2
           Catalysts

    • Authors: Ludmilla Bobrova, Dmitry Andreev, Eugene Ivanov, Natalia Mezentseva, Mikhail Simonov, Lev Makarshin, Alexander Gribovskii, Vladislav Sadykov
      First page: 310
      Abstract: This paper reports the results of a study of a water–gas shift reaction over nickel–ceria catalysts with different metal loading. Within this study, the overall CO conversion and observed kinetic behavior were investigated over the temperature range of 250–550 °C in different reactor configurations (fixed-bed and microchannel reactors). The quasi-steady state kinetics of the CO water–gas shift reaction was studied for fractions of Ni-containing cerium oxide catalysts in fixed-bed experiments at lab-scale level using a very dilute gas (1% CO + 1.8% H2O in Не). A set of experiments with a microchannel reactor was performed using the feed composition (CO:H2O:H2:N2 = 1:2:2:2), representing a product gas from methane partial oxidation. The results were interpreted using computational models. The kinetic parameters were determined by regression analysis, while mechanistic aspects were considered only briefly. Simulation of the WGS reaction in the microreactor was also carried out by using the COMSOL Multiphysics program.
      Citation: Catalysts
      PubDate: 2017-10-20
      DOI: 10.3390/catal7100310
      Issue No: Vol. 7, No. 10 (2017)
       
  • Catalysts, Vol. 7, Pages 311: Activated Carbon-Supported
           Tetrapropylammonium Perruthenate Catalysts for Acetylene Hydrochlorination
           

    • Authors: Xing Li, Haiyang Zhang, Baochang Man, Lijuan Hou, Chuanming Zhang, Hui Dai, Mingyuan Zhu, Bin Dai, Yanzhao Dong, Jinli Zhang
      First page: 311
      Abstract: The Ru-based catalysts, including Ru/AC (activated carbon), TPAP (tetrapropylammonium perruthenate)/AC, TPAP/AC-HNO3, and TPAP/AC-HCl, were prepared and assessed for the direct synthesis of vinyl chloride monomer. The results indicate that the TPAP/AC-HCl catalyst exhibits the best performance with the conversion falling from 97% to 91% in 48 hours’ reaction under the conditions of 180 °C, a GHSV(C2H2) of 180 h−1, and the feed ratio VHCl/VC2H2 of 1.15. The substitution of RuCl3 precursor with high valent TPAP species leads to more ruthenium oxides active species in the catalysts; the acidification treatment of carrier in TPAP/AC catalyst can produce an enhanced interaction between the active species and the modified functional groups on the carrier, and it is beneficial to inhibit the carbon deposition and sintering of ruthenium species in the reaction process, greatly increase the adsorption ability of reactants, and further increase the amount of dominating active species in the catalysts, thus improving the catalytic performance. This also provides a promising strategy to explore high efficient and economic mercury-free catalysts for the hydrochlorination of acetylene.
      Citation: Catalysts
      PubDate: 2017-10-24
      DOI: 10.3390/catal7100311
      Issue No: Vol. 7, No. 10 (2017)
       
 
 
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