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  Subjects -> CHEMISTRY (Total: 846 journals)
    - ANALYTICAL CHEMISTRY (50 journals)
    - CHEMISTRY (597 journals)
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CHEMISTRY (597 journals)                  1 2 3 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 7)
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: 31)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 17)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 22)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 39)
ACS Nano     Full-text available via subscription   (Followers: 217)
ACS Photonics     Full-text available via subscription   (Followers: 10)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription  
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: 7)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 48)
Advanced Science Focus     Free   (Followers: 3)
Advances in Chemical Engineering and Science     Open Access   (Followers: 53)
Advances in Chemical Science     Open Access   (Followers: 12)
Advances in Chemistry     Open Access   (Followers: 12)
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: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 18)
Advances in Nanoparticles     Open Access   (Followers: 12)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Science and Technology     Full-text available via subscription   (Followers: 10)
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: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Chemistry     Open Access   (Followers: 25)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Full-text available via subscription   (Followers: 12)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 153)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 203)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 1)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 3)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 7)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal  
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 26)
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: 3)
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: 9)
Biochemistry     Full-text available via subscription   (Followers: 277)
Biochemistry Insights     Open Access   (Followers: 5)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 3)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access  
Biomacromolecules     Full-text available via subscription   (Followers: 18)
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: 4)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 107)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 99)
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: 2)
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Full-text available via subscription   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 3)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 67)
Catalysis for Sustainable Energy     Open Access   (Followers: 6)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 7)
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: 12)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 69)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 23)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 19)
Chemical Reviews     Full-text available via subscription   (Followers: 165)
Chemical Science     Open Access   (Followers: 21)
Chemical Technology     Open Access   (Followers: 15)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 55)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 25)
ChemInform     Hybrid Journal   (Followers: 7)
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: 136)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 15)
Chemistry and Materials Research     Open Access   (Followers: 17)
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: 43)
Chemistry of Materials     Full-text available via subscription   (Followers: 189)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 8)
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: 23)
Chromatography Research International     Open Access   (Followers: 7)
Clay Minerals     Full-text available via subscription   (Followers: 9)
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: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 3)
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: 2)
Copernican Letters     Open Access  
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Crystal Structure Theory and Applications     Open Access   (Followers: 3)
CrystEngComm     Full-text available via subscription   (Followers: 10)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 4)
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 48)
Dalton Transactions     Full-text available via subscription   (Followers: 18)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 11)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 3)
Eclética Química     Open Access   (Followers: 1)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
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: 2)
Environmental Chemistry     Hybrid Journal   (Followers: 8)
Environmental Chemistry Letters     Hybrid Journal   (Followers: 4)
Environmental Science & Technology Letters     Full-text available via subscription   (Followers: 5)
Environmental Science : Nano     Partially Free   (Followers: 1)
Environmental Toxicology & Chemistry     Hybrid Journal   (Followers: 19)

        1 2 3 | Last

Journal Cover Catalysts
  [SJR: 1.123]   [H-I: 14]   [7 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2073-4344
   Published by MDPI Homepage  [148 journals]
  • Catalysts, Vol. 7, Pages 126: Ion-Exchange of Cu2+ Promoted Layered
           Perovskite K2La2Ti3O10 for Photocatalytic Degradation Chlorobenzene under
           Simulated Solar Light Irradiation

    • Authors: Dandan Pang, Jie Gao, Feng Ouyang, Rongshu Zhu, Charlene Xie
      First page: 126
      Abstract: The layered perovskite, K2La2Ti3O10 was prepared by sol-gel method. Ion-exchange of Cu2+ was prepared to improve the photocatalytic activity of K2La2Ti3O10 for chlorobenzene degradation under simulated solar light irradiation. The original K2La2Ti3O10 and Cu2+/K2La2Ti3O10 were characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and specific surface area measurement. The XRD analysis shows that Cu2+ ions is incorporated in place of K+ ions and the grain growth is inhibited by ion-exchange. With the rise of calcination temperature, more interlayer Cu2+ was converted into new crystal phase CuO. The degradation ratio reaches 51.1% on Cu2+/K2La2Ti3O10 calcined at 500 °C in air, which is higher 16.9% than the original K2La2Ti3O10. It should be ascribed to the narrow interlayer distance, the formation of CuO, smaller grain size, and the high visible light absorption on the surface of Cu2+/K2La2Ti3O10 calcined at 500 °C. It is found that the exposure of CO2 could promote the photocatalytic activity of Cu2+/K2La2Ti3O10. It also suggests that CO2 is involved in the reduction to form benzaldehyde during decomposition of chlorobenzene.
      PubDate: 2017-04-26
      DOI: 10.3390/catal7050126
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 127: Well-Shaped Sulfonic Organosilica Nanotubes
           with High Activity for Hydrolysis of Cellobiose

    • Authors: Jing Sun, Xiao Liu, Xinli Zhu, Hua Wang, Sadegh Rostamnia, Jinyu Han
      First page: 127
      Abstract: Sulfonic organosilica nanotubes with different acidity densities could be synthesized through the co-condensation of ethenyl- or phenylene-bridged organosilane and 3-mercaptopropyltrimethoxysilane followed by sulfhydryl (–SH) oxidation. Transmission electron microscopy (TEM) analysis and nitrogen adsorption-desorption experiment clearly exhibit the hollow nanotube structures with the diameters of about 5 nm. The compositions of the nanotube frameworks are confirmed by solid state 13C nuclear magnetic resonance (NMR) while X-ray photoelectron spectroscopy (XPS) shows that about 60–80% of SH groups were oxidized to sulfonic acid (SO3H). The acid contents were measured by both elemental analysis (CHNS mode) and acid-base titration experiment, which revealed that the acid density was in the range of 0.74 to 4.37 μmol·m−2 on the solid. These nanotube-based acid catalysts exhibited excellent performances in the hydrolysis of cellobiose with the highest conversion of 92% and glucose selectivity of 96%. In addition, the catalysts could maintain high activity (65% conversion with 92% selectivity) even after six recycles.
      PubDate: 2017-04-27
      DOI: 10.3390/catal7050127
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 128: Highly Dispersed PdNPs/α-Al2O3 Catalyst for
           the Selective Hydrogenation of Acetylene Prepared with Monodispersed Pd
           Nanoparticles

    • Authors: Huoli Zhang, Youchao Wang, Yan Wang, Jianliang Cao, Peng Kang, Qingjie Tang, Mingjie Ma
      First page: 128
      Abstract: Pd nanoparticles (PdNPs) stabilized by methyl cellulose (MC) were synthesized in an aqueous solution, which are monodispersed nanoparticles. PdNPs/α-Al2O3 catalyst was prepared with monodispersed PdNPs and showed better catalytic performance than Pd/α-Al2O3 catalyst prepared by the incipient wetness impregnation method using Pd(NO3)2 as a precursor. The catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that monodispersed PdNPs were spherical or elliptical nanoparticles with exposed (111) and (100) facets, and the PdNPs/α-Al2O3 catalyst showed a more concentrated distribution of Pd particles on the surface of α-Al2O3 support than the Pd/α-Al2O3 catalyst. The preparation method achieved the highly dispersed PdNPs/α-Al2O3 catalyst with smaller Pd particle size and decreased the aggregation of Pd active sites, which was responsible for higher acetylene conversion and ethylene selectivity.
      PubDate: 2017-04-28
      DOI: 10.3390/catal7050128
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 129: A Study of Low-Temperature CO Oxidation over
           Mesoporous CuO-TiO2 Nanotube Catalysts

    • Authors: Abdallah Zedan, Nageh Allam, Siham AlQaradawi
      First page: 129
      Abstract: Supported copper oxide nanoparticles have attracted considerable attention as active and non-precious catalysts for many catalytic oxidation reactions. Herein, mesoporous xCuO-TiO2 nanotube catalysts were fabricated, and their activity and kinetics toward CO oxidation were studied. The morphology and structure of the prepared catalysts were systematically studied using SEM, TEM, EDS, EDX, XRD, TGA, BET, XPS, H2-TPR, and Raman techniques. The BET surface area study revealed the effect of the large surface area of the mesoporous TiO2 nanotubes on promoting the catalytic activity of prepared catalysts. The results also revealed the existence of strong metal-support interactions in the CuO-TiO2 nanotube catalyst, as indicated by the up-shift of the E2g vibrational mode of TiO2 from 144 cm−1 to 145 cm−1 and the down-shift of the binding energy (BE) of Ti 2p3/2 from 458.3 eV to 458.1 eV. The active phase of the catalyst consists of fine CuO nanoparticles dispersed on a mesoporous anatase TiO2 nanotube support. The 50-CuO-TiO2 nanotube catalyst demonstrated the highest catalytic activity with 100% CO conversion at T100 = 155 °C and a reaction rate of 36 µmole s−1 g−1. Furthermore, the catalyst demonstrated excellent long-term stability with complete CO conversion that was stable for 60 h under a continuous stream. The enhanced catalytic activity is attributed to the interplay at the interface between the active CuO phase and the TiO2 nanotubes support.
      PubDate: 2017-04-28
      DOI: 10.3390/catal7050129
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 130: Old Yellow Enzyme-Catalysed Asymmetric
           Hydrogenation: Linking Family Roots with Improved Catalysis

    • Authors: Anika Scholtissek, Dirk Tischler, Adrie Westphal, Willem van Berkel, Caroline Paul
      First page: 130
      Abstract: Asymmetric hydrogenation of activated alkenes catalysed by ene-reductases from the old yellow enzyme family (OYEs) leading to chiral products is of potential interest for industrial processes. OYEs’ dependency on the pyridine nucleotide coenzyme can be circumvented through established artificial hydride donors such as nicotinamide coenzyme biomimetics (NCBs). Several OYEs were found to exhibit higher reduction rates with NCBs. In this review, we describe a new classification of OYEs into three main classes by phylogenetic and structural analysis of characterized OYEs. The family roots are linked with their use as chiral catalysts and their mode of action with NCBs. The link between bioinformatics (sequence analysis), biochemistry (structure–function analysis), and biocatalysis (conversion, enantioselectivity and kinetics) can enable an early classification of a putative ene-reductase and therefore the indication of the binding mode of various activated alkenes.
      PubDate: 2017-04-29
      DOI: 10.3390/catal7050130
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 131: Treatment of Aqueous Bromate by
           Superparamagnetic BiOCl-Mediated Advanced Reduction Process

    • Authors: Xiaowei Liu, Lili Wang, Zhe Sun, Yu Shao, Tingchao Yu
      First page: 131
      Abstract: Bromate ( BrO 3 − ) contamination in drinking water is a growing concern. Advanced reduction processes (ARPs) are reportedly promising in relieving this concern. In this work, UV/superparamagnetic BiOCl (BiOCl loaded onto superparamagnetic hydroxyapatite) assisted with small molecule carboxylic acid (formate, citrate, and acetate), a carboxyl anion radical ( CO 2 • − )-based ARP, was proposed to eliminate aqueous BrO 3 − . Formate and citrate were found to be ideal CO 2 • − precursor, and the latter was found to be safe for practical use. BrO 3 − (10 μg·L−1, WHO guideline for drinking water) can be completely degraded within 3 min under oxygen-free conditions. In this process, BrO 3 − degradation was realized by the reduction of CO 2 • − (major role) and formyloxyl radical (minor role) in bulk solution. The formation mechanism of radicals and the transformation pathway of BrO 3 − were proposed based on data on electron paramagnetic resonance monitoring, competitive kinetics, and degradation product analysis. The process provided a sustainable decontamination performance (<5% deterioration for 10 cycles) and appeared to be more resistant to common electron acceptors (O2, NO 3 − , and Fe3+) than hydrated electron based-ARPs. Phosphate based-superparamagnetic hydroxyapatite, used to support BiOCl in this work, was believed to be applicable for resolving the recycling problem of other metal-containing catalyst.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050131
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 132: Transition Metal-Modified Zirconium
           Phosphate Electrocatalysts for the Oxygen Evolution Reaction

    • Authors: Joel Sanchez, Mario V. Ramos-Garcés, Ieva Narkeviciute, Jorge L. Colón, Thomas F. Jaramillo
      First page: 132
      Abstract: Zirconium phosphate (ZrP), an inorganic layered nanomaterial, is currently being investigated as a catalyst support for transition metal-based electrocatalysts for the oxygen evolution reaction (OER). Two metal-modified ZrP catalyst systems were synthesized: metal-intercalated ZrP and metal-adsorbed ZrP, each involving Fe(II), Fe(III), Co(II), and Ni(II) cations. Fourier transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy were used to characterize the composite materials and confirm the incorporation of the metal cations either between the layers or on the surface of ZrP. Both types of metal-modified systems were examined for their catalytic activity for the OER in 0.1 M KOH solution. All metal-modified ZrP systems were active for the OER. Trends in activity are discussed as a function of the molar ratio in relation to the two types of catalyst systems, resulting in overpotentials for metal-adsorbed ZrP catalysts that were less than, or equal to, their metal-intercalated counterparts.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050132
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 133: Sol-Gel-Assisted Microwave-Derived Synthesis
           of Anatase Ag/TiO2/GO Nanohybrids toward Efficient Visible Light Phenol
           Degradation

    • Authors: E. H. Alsharaeh, T. Bora, A. Soliman, Faheem Ahmed, G. Bharath, M. G. Ghoniem, Khalid M. Abu-Salah, J. Dutta
      First page: 133
      Abstract: Abstract: A simple microwave-assisted (MWI) wet chemical route to synthesize pure anatase phase titanium dioxide (TiO2) nanoparticles (NPs) is reported here using titanium tetrachloride (TiCl4) as starting material. The as-prepared TiO2 NPs were characterized by electron microscopy, X-ray diffraction, UV/visible absorption spectroscopy, and infrared and Raman spectroscopic techniques. Further modification of the anatase TiO2 NPs was carried out by incorporating plasmonic silver (Ag) NPs and graphene oxide (GO) in order to enhance the visible light absorption. The photocatalytic activities of the anatase TiO2, Ag/TiO2, and Ag/TiO2/GO nanocomposites were evaluated under both ultraviolet (UV) and visible light irradiation using phenol as a model contaminant. The presence of Ag NPs was found to play a significant role to define the photocatalytic activity of the Ag/TiO2/GO nanocomposite. It was found that the Ag performed like a sink under UV excitation and stored photo-generated electrons from TiO2, whereas, under visible light excitation, the Ag acted as a photosensitizer enhancing the photocatalytic activity of the nanocomposite. The detailed mechanism was studied based on photocatalytic activities of Ag/TiO2/GO nanocomposites. Therefore, the as-prepared Ag/TiO2/GO nanocomposite was used as photocatalytic materials under both UV and visible light irradiation toward degradation of organic molecules.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050133
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 134: Dynamic Processes on Gold-Based Catalysts
           Followed by Environmental Microscopies

    • Authors: Eric Genty, Luc Jacobs, Thierry Visart de Bocarmé, Cédric Barroo
      First page: 134
      Abstract: Since the early discovery of the catalytic activity of gold at low temperature, there has been a growing interest in Au and Au-based catalysis for a new class of applications. The complexity of the catalysts currently used ranges from single crystal to 3D structured materials. To improve the efficiency of such catalysts, a better understanding of the catalytic process is required, from both the kinetic and material viewpoints. The understanding of such processes can be achieved using environmental imaging techniques allowing the observation of catalytic processes under reaction conditions, so as to study the systems in conditions as close as possible to industrial conditions. This review focuses on the description of catalytic processes occurring on Au-based catalysts with selected in situ imaging techniques, i.e., PEEM/LEEM, FIM/FEM and E-TEM, allowing a wide range of pressure and material complexity to be covered. These techniques, among others, are applied to unravel the presence of spatiotemporal behaviours, study mass transport and phase separation, determine activation energies of elementary steps, observe the morphological changes of supported nanoparticles, and finally correlate the surface composition with the catalytic reactivity.
      PubDate: 2017-05-01
      DOI: 10.3390/catal7050134
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 135: Functional and Biochemical Analysis of
           Glucose-6-Phosphate Dehydrogenase (G6PD) Variants: Elucidating the
           Molecular Basis of G6PD Deficiency

    • Authors: Saúl Gómez-Manzo, Jaime Marcial-Quino, Daniel Ortega-Cuellar, Hugo Serrano-Posada, Abigail González-Valdez, America Vanoye-Carlo, Beatriz Hernández-Ochoa, Edgar Sierra-Palacios, Adriana Castillo-Villanueva, Horacio Reyes-Vivas
      First page: 135
      Abstract: G6PD deficiency is the most common enzymopathy, leading to alterations in the first step of the pentose phosphate pathway, which interferes with the protection of the erythrocyte against oxidative stress and causes a wide range of clinical symptoms of which hemolysis is one of the most severe. The G6PD deficiency causes several abnormalities that range from asymptomatic individuals to more severe manifestations that can lead to death. Nowadays, only 9.2% of all recognized variants have been related to clinical manifestations. It is important to understand the molecular basis of G6PD deficiency to understand how gene mutations can impact structure, stability, and enzymatic function. In this work, we reviewed and compared the functional and structural data generated through the characterization of 20 G6PD variants using different approaches. These studies showed that severe clinical manifestations of G6PD deficiency were related to mutations that affected the catalytic and structural nicotinamide adenine dinucleotide phosphate (NADPH) binding sites, and suggests that the misfolding or instability of the 3D structure of the protein could compromise the half-life of the protein in the erythrocyte and its activity.
      PubDate: 2017-05-02
      DOI: 10.3390/catal7050135
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 136: Photocatalytic Graphene-TiO2 Thin Films
           Fabricated by Low-Temperature Ultrasonic Vibration-Assisted Spin and Spray
           Coating in a Sol-Gel Process

    • Authors: Fatemeh Zabihi, Mohammad-Reza Ahmadian-Yazdi, Morteza Eslamian
      First page: 136
      Abstract: In this work, we communicate a facile and low temperature synthesis process for the fabrication of graphene-TiO2 photocatalytic composite thin films. A sol-gel chemical route is used to synthesize TiO2 from the precursor solutions and spin and spray coating are used to deposit the films. Excitation of the wet films during the casting process by ultrasonic vibration favorably influences both the sol-gel route and the deposition process, through the following mechanisms. The ultrasound energy imparted to the wet film breaks down the physical bonds of the gel phase. As a result, only a low-temperature post annealing process is required to eliminate the residues to complete the conversion of precursors to TiO2. In addition, ultrasonic vibration creates a nanoscale agitating motion or microstreaming in the liquid film that facilitates mixing of TiO2 and graphene nanosheets. The films made based on the above-mentioned ultrasonic vibration-assisted method and annealed at 150 °C contain both rutile and anatase phases of TiO2, which is the most favorable configuration for photocatalytic applications. The photoinduced and photocatalytic experiments demonstrate effective photocurrent generation and elimination of pollutants by graphene-TiO2 composite thin films fabricated via scalable spray coating and mild temperature processing, the results of which are comparable with those made using lab-scale and energy-intensive processes.
      PubDate: 2017-05-02
      DOI: 10.3390/catal7050136
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 137: Catalytic Abatement of Nitrous Oxide Coupled
           with Ethane Oxydehydrogenation over Mesoporous Cr/Al2O3 Catalyst

    • Authors: Yan Zhang, Suresh Kumar Megarajan, Xia Xu, Jingting Lu, Heqing Jiang
      First page: 137
      Abstract: Waste nitrous oxide (N2O) was utilized as an oxidant for ethane oxydehydrogenation reaction at the temperature range from 450 °C to 700 °C over the mesoporous Cr/Al2O3 catalyst synthesized via the one-pot evaporation-induced self-assembly (EISA) method. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption-desorption analysis. The obtained mesoporous material with favorable textural property and advantageous thermal stability was investigated as the catalyst for ethane oxydehydrogenation. It was found that the utilization of N2O as an oxidant for the oxydehydrogenation reaction of ethane resulted in simultaneous and complete N2O abatement. Moreover, the catalytic conversion of C2H6 to C2H4 was increased from 18% to 43% as the temperature increased from 450 °C to 700 °C. The increased N2O concentration from 5 vol % to 20 vol % resulted in an increased ethane conversion but decreased ethylene selectivity because the nonselective reactions occurred. Ethane was converted into ethylene with approximately 51% selectivity and 22% yield at 700 °C and N2O concentration of 10%. After a catalytic steady state was reached, no obvious decline was observed during a 15 h evaluation period.
      PubDate: 2017-05-04
      DOI: 10.3390/catal7050137
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 138: Cobalt-iron Oxide, Alloy and Nitride:
           Synthesis, Characterization and Application in Catalytic Peroxymonosulfate
           Activation for Orange II Degradation

    • Authors: Kaixin Zhu, Changzi Jin, Zoltán Klencsár, Ayyakannu Ganeshraja, Junhu Wang
      First page: 138
      Abstract: In meeting the need for environmental remediation in wastewater treatment and the development of popular sulfate-radical-based advanced oxidation processes (SR-AOPs), a series of Co/Fe-based catalysts with confirmed phase structure were prepared through extended soft chemical solution processes followed by atmosphere-dependent calcination. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and 57Fe Mössbauer spectroscopy were employed to characterize the composition, morphology, crystal structure and chemical state of the prepared catalysts. It was shown that calcination in air, nitrogen and ammonia atmospheres generated Co-Fe catalysts with cobalt ferrite (CoFe2O4), Co-Fe alloy and Co-Fe nitride as dominant phases, respectively. The prepared Co/Fe-based catalysts were demonstrated to be highly efficient in activating peroxymonosulfate (PMS) for organic Orange II degradation. The activation efficiency of the different catalysts was found to increase in the order CoFe2O4 < Co-Fe nitride < Co-Fe alloy. Sulfate radical was found to be the primary active intermediate species contributing to the dye degradation for all the participating catalysts. Furthermore, a possible reaction mechanism was proposed for each of the studied catalysts. This study achieves progress in efficient cobalt-iron catalysts using in the field of SR-AOPs, with potential applications in environment remediation.
      PubDate: 2017-05-04
      DOI: 10.3390/catal7050138
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 139: Tailoring the Oxygen Evolution Activity and
           Stability Using Defect Chemistry

    • Authors: Julius Scholz, Marcel Risch, Garlef Wartner, Christoph Luderer, Vladimir Roddatis, Christian Jooss
      First page: 139
      Abstract: Improving the activity of catalysts for the oxygen evolution reaction (OER) requires a detailed understanding of the surface chemistry and structure to deduce structure-function relationships (descriptors) for fundamental insight. We chose epitaxial (100)-oriented La0.6Sr0.4Mn1−δO3 (LSMO) thin films as a model system with high electrochemical activity comparable to (110)-oriented IrO2 to investigate the effect of Mn off-stoichiometry on both catalytic activity and stability. Extensive structural characterization was performed by microscopic and spectroscopic methods before and after electrochemical characterization using rotating ring-disk studies. Stoichiometric LSMO had the highest activity, while both Mn deficiency and excess reduced the catalytic activity. Furthermore, all samples preserved the crystal structure up to the very surface. Mn excess improved the long-term activity, and we hypothesize that excess Mn stabilizes the surface chemistry during catalysis. Our data show that the defect chemistry should be considered when designing catalysts with enhanced activity and rugged stability.
      PubDate: 2017-05-05
      DOI: 10.3390/catal7050139
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 140: Exploring Promising Catalysts for Chemical
           Hydrogen Storage in Ammonia Borane: A Density Functional Theory Study

    • Authors: Sateesh Bandaru, Niall English, Andrew Phillips, J. MacElroy
      First page: 140
      Abstract: Density functional theory (DFT) has been applied to study potential ammonia borane (AB) dehydrogenation pathways via new bifunctional ruthenium-based catalysts, alongside their computationally-designed iron-based counterparts (i.e., four catalysts), using the wB97XD (dispersion-included) functional. The efficiency of each catalyst was under scrutiny based on the addition of ammonia borane, with a focus on the associated activation-energy barriers, whilst hydrogen release from the catalyst was also studied in detail. Here, natural-population analysis charges were key quantities of interest. It was found that the iron-based catalysts display more promising dehydrogenation energy barriers vis-
      PubDate: 2017-05-05
      DOI: 10.3390/catal7050140
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 141: Post Synthesis of Aluminum Modified
           Mesoporous TUD-1 Materials and Their Application for FCC Diesel
           Hydrodesulfurization Catalysts

    • Authors: Zesheng Xia, Jianye Fu, Aijun Duan, Longnian Han, Huadong Wu, Zhen Zhao, Chunming Xu, Dong Wang, Bo Wang, Qian Meng
      First page: 141
      Abstract: Post-synthesis methods are a promising technology and have received much attention. In this paper, a series of post-synthesis aluminum modified TUD-1 (PAT) materials with different Al contents were successfully prepared by using aluminum isopropoxide to be Al sources, then the as-synthesized materials were adopted as support additives mixed with commercial γ-Al2O3 to prepare hydrodesulfurization (HDS) catalysts for FCC diesel. The supports and catalysts were analyzed using N2 adsorption-desorption, XRD, SEM, Py-IR, ICP, 27Al MAS NMR, UV-vis, H2-TPR and HRTEM techniques. The results of Py-IR and 27Al MAS NMR indicated that the addition of Al species could bring Lewis (L) and Brönsted (B) sites into Si-TUD-1, and that the material of PAT-3 had the highest total acidity sites and Brönsted acid sites among the series PAT composites. The HRTEM technique showed that, compared to the traditional catalyst NiMo/γ-Al2O3, the sulfided catalyst NiMo/APAT-3 had a relatively short length (3.2 nm) and suitable stacking number (2.5) of MoS2 slabs. The HDS efficiencies of all the catalysts were tested in a fixed bed micro-reactor with FCC diesel as feedstock. The catalytic results confirmed that the catalyst NiMo/APAT-3 possessed the highest HDS efficiency (97.0%), due to synergistic effects of advantageous properties such as higher acidity, moderate MSI, and relatively short length of the MoS2 slabs.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050141
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 142: Are Directed Evolution Approaches Efficient
           in Exploring Nature’s Potential to Stabilize a Lipase in Organic
           Cosolvents?

    • Authors: Ulrich Markel, Leilei Zhu, Victorine Frauenkron-Machedjou, Jing Zhao, Marco Bocola, Mehdi Davari, Karl-Erich Jaeger, Ulrich Schwaneberg
      First page: 142
      Abstract: Despite the significant advances in the field of protein engineering, general design principles to improve organic cosolvent resistance of enzymes still remain undiscovered. Previous studies drew conclusions to engineer enzymes for their use in water-miscible organic solvents based on few amino acid substitutions. In this study, we conduct a comparison of a Bacillus subtilis lipase A (BSLA) library—covering the full natural diversity of single amino acid substitutions at all 181 positions of BSLA—with three state of the art random mutagenesis methods: error-prone PCR (epPCR) with low and high mutagenesis frequency (epPCR-low and high) as well as a transversion-enriched Sequence Saturation Mutagenesis (SeSaM-Tv P/P) method. Libraries were searched for amino acid substitutions that increase the enzyme’s resistance to the water-miscible organic cosolvents 1,4-dioxane (DOX), 2,2,2-trifluoroethanol (TFE), and dimethyl sulfoxide (DMSO). Our analysis revealed that 5%–11% of all possible single substitutions (BSLA site-saturation mutagenesis (SSM) library) contribute to improved cosolvent resistance. However, only a fraction of these substitutions (7%–12%) could be detected in the three random mutagenesis libraries. To our knowledge, this is the first study that quantifies the capability of these diversity generation methods generally employed in directed evolution campaigns and compares them to the entire natural diversity with a single substitution. Additionally, the investigation of the BSLA SSM library revealed only few common beneficial substitutions for all three cosolvents as well as the importance of introducing surface charges for organic cosolvent resistance—most likely due to a stronger attraction of water molecules.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050142
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 143: Preparation of Salen–Metal Complexes
           (Metal = Co or Ni) Intercalated ZnCr-LDHs and Their Photocatalytic
           Degradation of Rhodamine B

    • Authors: Yue Meng, Wei Luo, Shengjie Xia, Zheming Ni
      First page: 143
      Abstract: Salen–metal complexes (SalenM) were successfully intercalated into ZnCr layered double hydroxides (LDHs) through coprecipitation method, then a series of novel organic–inorganic hybrid materials were obtained. The structure and properties of the materials were thoroughly characterized by inductively-coupled plasma atomic emission spectrometry (ICP-AES), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). Meanwhile, with Rhodamine B (RhB) as a target contaminant, the photocatalytic activities of SalenM-intercalated ZnCr-LDHs were investigated and compared with the traditional LDHs (ZnCr-LDHs, ZnCoCr-LDHs, and ZnNiCr-LDHs). Furthermore, the effect of the intercalation amount of SalenM (M = Co or Ni) on the photocatalytic activity was studied. The results showed that when the molar ratio of SalenM to Cr was 0.75, SalenM-intercalated ZnCr-LDHs exhibited significantly higher photocatalytic activities than the traditional LDHs. The degradation rates of RhB reached about 90%, and all of them had good recycling rates. In addition, the kinetics of photocatalytic process and the mechanism of photocatalysis are discussed.
      PubDate: 2017-05-07
      DOI: 10.3390/catal7050143
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 144: Catalysts Promoted with Niobium Oxide for
           Air Pollution Abatement

    • Authors: Wendi Xiang, Xiaochen Han, Jennifer Astorsdotter, Robert Farrauto
      First page: 144
      Abstract: Pt-containing catalysts are currently used commercially to catalyze the conversion of carbon monoxide (CO) and hydrocarbon (HC) pollutants from stationary chemical and petroleum plants. It is well known that Pt-containing catalysts are expensive and have limited availability. The goal of this research is to find alternative and less expensive catalysts to replace Pt for these applications. This study found that niobium oxide (Nb2O5), as a carrier or support for certain transition metal oxides, promotes oxidation activity while maintaining stability, making them candidates as alternatives to Pt. The present work reports that the orthorhombic structure of niobium oxide (formed at 800 °C in air) promotes Co3O4 toward the oxidation of both CO and propane, which are common pollutants in volatile organic compound (VOC) applications. This was a surprising result since this structure of Nb2O5 has a very low surface area (about 2 m2/g) relative to the more traditional Al2O3 support, with a surface area of 150 m2/g. The results reported demonstrate that 1% Co3O4/Nb2O5 has comparable fresh and aged catalytic activity to 1% Pt/γ-Al2O3 and 1% Pt/Nb2O5. Furthermore, 6% Co3O4/Nb2O5 outperforms 1% Pt/Al2O3 in both catalytic activity and thermal stability. These results suggest a strong interaction between niobium oxide and the active component—cobalt oxide—likely by inducing an oxygen defect structure with oxygen vacancies leading to enhanced activity toward the oxidation of CO and propane.
      PubDate: 2017-05-08
      DOI: 10.3390/catal7050144
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 145: Hydrogenation of Phenol over Pt/CNTs: The
           Effects of Pt Loading and Reaction Solvents

    • Authors: Feng Li, Bo Cao, Wenxi Zhu, Hua Song, Keliang Wang, Cuiqin Li
      First page: 145
      Abstract: Carbon nanotubes (CNTs)-supported Pt nanoparticles were prepared with selective deposition of Pt nanoparticles inside and outside CNTs (Pt–in/CNTs and Pt–out/CNTs). The effects of Pt loading and reaction solvents on phenol hydrogenation were investigated. The Pt nanoparticles in Pt–in/CNTs versus Pt–out/CNTs are smaller and better dispersed. The catalytic activity and reuse stability toward phenol hydrogenation both improved markedly. The dichloromethane–water mixture as the reaction solvent, compared with either pure medium, decreased the catalytic activity toward phenol hydrogenation and selectivity of cyclohexanone over Pt–in/CNTs, but significantly improved the catalytic activity toward phenol hydrogenation and selectivity of cyclohexanone over Pt–out/CNTs.
      PubDate: 2017-05-08
      DOI: 10.3390/catal7050145
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 146: Palladium-Catalyzed Suzuki–Miyaura
           Cross-Coupling in Continuous Flow

    • Authors: Christophe Len, Sophie Bruniaux, Frederic Delbecq, Virinder Parmar
      First page: 146
      Abstract: Carbon–carbon cross-coupling reactions are among the most important processes in organic chemistry and Suzuki–Miyaura reactions are the most widely used protocols. For a decade, green chemistry and particularly catalysis and continuous flow, have shown immense potential in achieving the goals of “greener synthesis”. To date, it seems difficult to conceive the chemistry of the 21st century without the industrialization of continuous flow process in the area of pharmaceuticals, drugs, agrochemicals, polymers, etc. A large variety of palladium Suzuki–Miyaura cross-coupling reactions have been developed using a continuous flow sequence for preparing the desired biaryl derivatives. Our objective is to focus this review on the continuous flow Suzuki–Miyaura cross-coupling using homogeneous and heterogeneous catalysts.
      PubDate: 2017-05-09
      DOI: 10.3390/catal7050146
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 147: Spongin-Based Scaffolds from Hippospongia
           communis Demosponge as an Effective Support for Lipase Immobilization

    • Authors: Jakub Zdarta, Małgorzata Norman, Wojciech Smułek, Dariusz Moszyński, Ewa Kaczorek, Allison Stelling, Hermann Ehrlich, Teofil Jesionowski
      First page: 147
      Abstract: The main purpose of the study was to achieve effective immobilization of lipase B from Candida antarctica (CALB) onto 3D spongin-based scaffolds from Hippospongia communis marine demosponge for rapeseed oil transesterification. Successful immobilization onto the marine sponge skeleton was confirmed for the first time. Lipase B-containing biocatalytic system exhibited the highest catalytic activity retention (89%) after 60 min of immobilization at pH 7 and temperature of 4 °C. Immobilization was found to improve the thermal and chemical stability compared to free lipase, and retain over 80% of its initial catalytic activity over a wide range of temperature (30–60 °C) and pH (6–9). Additionally, immobilized lipase has good storage stability and retains over 70% of its initial activity even after catalyzing of 25 reaction cycles. The obtained product was used in a transesterification reaction of rapeseed oil with methanol and proved to be an efficient biocatalyst for biofuel production. The highest conversion value and fatty acids methyl esters (FAME) concentration were observed after a process conducted at 40 °C and pH 10. The possible mechanism of interaction between the enzyme and the spongin-based support is proposed and discussed.
      PubDate: 2017-05-10
      DOI: 10.3390/catal7050147
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 148: Methanol Steam Reforming: Na Doping of
           Pt/YSZ Provides Fine Tuning of Selectivity

    • Authors: Michela Martinelli, Gary Jacobs, Uschi Graham, Burtron Davis
      First page: 148
      Abstract: In this work, we found that sodium doping can be used to improve CO2 selectivity for supported Pt catalyst during methanol steam reforming. These materials are usually very active in the low temperature range; however, they are characterized by high selectivity of CO, which is a poison in downstream polymer electrolyte membrane fuel cells (PEM-FC) application. With Na doping, we found that CO2 selectivity was higher than 90% when 2.5 wt.% of sodium was added to Pt/YSZ. We have speculated that the different product distribution is due to a different reaction pathway being opened for CH3OH decomposition. Methanol decarbonylation was favored when Na was absent or low, while a formate decarboxylation pathway was favored when Na content reached 2.5 wt.%. The proposal is rooted in the observed weakening of the C-H bond of formate, as demonstrated in in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and kinetic isotope effect (KIE) experiments for the water-gas shift reaction conducted at low temperature. When adsorbed methoxy, produced when methanol is dissociatively adsorbed, was converted in the presence of H2O in DRIFTS spectroscopy, formate species were prevalent for a 2% Pt–2.5% Na/YSZ catalyst, while only a minor contribution was observed for 2% Pt/YSZ. Moreover, the formate produced on Na-doped Pt/YSZ exhibited ν(CH) stretching bands at low wavenumber, consistent with C–H bond weakening, thus favoring dehydrogenation (and decarboxylation). It is proposed that when Na is present, formate is likely an intermediate, and because its dehydrogenation is favored, selectivity can be fine-tuned between decarbonylation and decarboxylation based on Na dopant level.
      PubDate: 2017-05-10
      DOI: 10.3390/catal7050148
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 149: Factors Controlling the Redox Activity of
           

    • Authors: Chunzhen Yang, Alexis Grimaud
      First page: 149
      Abstract: Triggering the redox reaction of oxygens has become essential for the development of (electro) catalytic properties of transition metal oxides, especially for perovskite materials that have been envisaged for a variety of applications such as the oxygen evolution or reduction reactions (OER and ORR, respectively), CO or hydrocarbons oxidation, NO reduction and others. While the formation of ligand hole for perovskites is well-known for solid state physicists and/or chemists and has been widely studied for the understanding of important electronic properties such as superconductivity, insulator-metal transitions, magnetoresistance, ferroelectrics, redox properties etc., oxygen electrocatalysis in aqueous media at low temperature barely scratches the surface of the concept of oxygen ions oxidation. In this review, we briefly explain the electronic structure of perovskite materials and go through a few important parameters such as the ionization potential, Madelung potential, and charge transfer energy that govern the oxidation of oxygen ions. We then describe the surface reactivity that can be induced by the redox activity of the oxygen network and the formation of highly reactive surface oxygen species before describing their participation in catalytic reactions and providing mechanistic insights and strategies for designing new (electro) catalysts. Finally, we give a brief overview of the different techniques that can be employed to detect the formation of such transient oxygen species.
      PubDate: 2017-05-11
      DOI: 10.3390/catal7050149
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 150: Synthesis of SAPO-34 Molecular Sieves via
           Novel Intermittent Hydrothermal Treatment and Its Effect on the
           Crystallization and Product Properties

    • Authors: Zhihui Guo, Ping Miao, Weiping Zhu, Lei Guo, Fei Li, Yunpeng Xue, Qi Yin, Ruixue Yuan, Lianbin Xu
      First page: 150
      Abstract: Intermittent hydrothermal treatment was introduced into the synthesis of SAPO-34 molecular sieves to control the nucleation and the growth in the crystallization. The effect of the crystallization time, the order of long-time and short-time crystallization in two-stage crystallization, and frequency in multi-stage crystallization on synthesis, physicochemical properties and catalytic performance for conversion of methanol to light olefins (MTO) has been studied. The results show that pure SAPO-34 can be obtained with increasing crystallization time. The interruption of the initial crystallization is more beneficial for improving the Si distribution and the MTO catalytic performance of SAPO-34 molecular sieves. The sample obtained by repeatedly alternating heating and cooling during crystallization shows smaller particle size, higher acidity, longer lifetimes and higher yields of ethylene than that obtained by the conventional continuous crystallization at high temperature.
      PubDate: 2017-05-11
      DOI: 10.3390/catal7050150
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 151: Effect of Citric Acid on MoO3/Al2O3
           Catalysts for Sulfur-Resistant Methanation

    • Authors: Dajun Meng, Baowei Wang, Wenxia Yu, Weihan Wang, Zhenhua Li, Xinbin Ma
      First page: 151
      Abstract: A series of MoO3/Al2O3 catalysts with different amounts (molar ratio of CA/Mo = 0, 1, 1.5, and 2) of citric acid (CA) prepared by simultaneous impregnation were evaluated for sulfur-resistant methanation. Based on the evaluation results, catalytic activity increased accompanied with the rise of citric acid amount. Combine with the analysis of N2-physisorption, XRD, H2-TPR, XPS, and TEM, the catalyst saturated loading capacity improved, resulting in increasing dispersion of Mo species on Al2O3 surface clearly. According to H2-TPR result, the Mo oxide precursors can be more easily sulfureted when citric acid is added. Moreover, based on the Raman analysis, increasingly tetrahedrally coordinated Mo6+ species with high methanation performance are generated after citric acid treatment. These factors probably together accelerate MoO3/Al2O3 catalytic activity growth for methanation.
      PubDate: 2017-05-12
      DOI: 10.3390/catal7050151
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 152: Methanation of CO2 on Ni/Al2O3 in a
           Structured Fixed-Bed Reactor—A Scale-Up Study

    • Authors: Daniel Türks, Hesham Mena, Udo Armbruster, Andreas Martin
      First page: 152
      Abstract: Due to the ongoing change of energy supply, the availability of a reliable high-capacity storage technology becomes increasingly important. While conventional large-scale facilities are either limited in capacity respective supply time or their extension potential is little (e.g., pumped storage power stations), decentralized units could contribute to energy transition. The concepts of PtX (power-to-X) storage technologies and in particular PtG (power-to-gas) aim at fixation of electric power in chemical compounds. CO2 hydrogenation (methanation) is the foundation of the PtG idea as H2 (via electrolysis) and CO2 are easily accessible. Methane produced in this way, often called substitute natural gas (SNG), is a promising solution since it can be stored in the existing gas grid, tanks or underground cavern storages. Methanation is characterized by a strong exothermic heat of reaction which has to be handled safely. This work aims at getting rid of extreme temperature hot-spots in a tube reactor by configuring the catalyst bed structure. Proof of concept studies began with a small tube reactor (V = 12.5 cm3) with a commercial 18 wt % Ni/Al2O3 catalyst. Later, a double-jacket tube reactor was built (V = 452 cm3), reaching a production rate of 50 L/h SNG. The proposed approach not only improves the heat management and process safety, but also increases the specific productivity and stability of the catalyst remarkably.
      PubDate: 2017-05-15
      DOI: 10.3390/catal7050152
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 153: Structure-Dependent Photocatalytic
           Performance of BiOBrxI1−x Nanoplate Solid Solutions

    • Authors: Huan-Yan Xu, Xu Han, Qu Tan, Xiu-Lan He, Shu-Yan Qi
      First page: 153
      Abstract: BiOXxY1−x (X, Y = Cl, Br, and I) solid solutions have been regarded as promising photocatalysts attributed to their unique layered structure, tunable band structure, and chemical and optical stability. In this study, BiOBrxI1−x nanoplate solid solutions with a high exposure of {001} crystal facets were prepared by a facile alcoholysis method at room temperature and atmospheric pressure. X-ray diffraction (XRD) peaks exhibited a slight shift to lower diffraction angle with the increase of I content in BiOBrxI1−x samples, which resulted in a gradual increase in their cell parameters. Field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) images revealed that BiOBrxI1−x samples exhibited 2D plate-like structure with the in-plane wrinkles. The regular changes in optical absorption threshold and Eg value seen in UV-vis diffuse reflectance spectra (UV-vis DRS) indicated that the optical absorption property and band structure could be modulated by the formation of BiOBrxI1−x solid solutions. The photocatalytic degradation of active dye Rhodamine B (RhB) over BiOBrxI1−x solid solutions showed that BiOBr0.75I0.25 had the best photocatalytic activity. The RhB photodegradation processes followed a pseudo-first-order kinetic model. The synergistic effect of structural factors (including amount of exposed {001} facets, interlayer spacing of (001) plane, and energy-level position of the valence band) determined the photocatalytic performance of BiOBrxI1−x solid solutions.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050153
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 154: Perovskite Electrocatalysts for the Oxygen
           Reduction Reaction in Alkaline Media

    • Authors: Marcel Risch
      First page: 154
      Abstract: Oxygen reduction is considered a key reaction for electrochemical energy conversion but slow kinetics hamper application in fuel cells and metal-air batteries. In this review, the prospect of perovskite oxides for the oxygen reduction reaction (ORR) in alkaline media is reviewed with respect to fundamental insight into activity and possible mechanisms. For gaining these insights, special emphasis is placed on highly crystalline perovskite films that have only recently become available for electrochemical interrogation. The prospects for applications are evaluated based on recent progress in the synthesis of perovskite nanoparticles. The review concludes with the current understanding of oxygen reduction on perovskite oxides and a perspective on opportunities for future fundamental and applied research.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050154
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 155: Catalytic Performance of MgO-Supported Co
           Catalyst for the Liquid Phase Oxidation of Cyclohexane with Molecular
           Oxygen

    • Authors: Mingzhou Wu, Yu Fu, Wangcheng Zhan, Yanglong Guo, Yun Guo, Yunsong Wang, Guanzhong Lu
      First page: 155
      Abstract: A highly-efficient and stable MgO-supported Co (Co/MgO) catalyst was developed for the oxidation of cyclohexane with oxygen. The effects of the Co loading and support on the catalytic activity of the supported Co3O4 catalyst were investigated. The results show that the Co supported on MgO presented excellent activity and stability. When the Co/MgO catalyst with the Co content of 0.2 wt% (0.2%Co/MgO) was used, 12.5% cyclohexane conversion and 74.7% selectivity to cyclohexanone and cyclohexanol (KA oil) were achieved under the reaction conditions of 0.5 MPa O2 and 140 °C for 4 h. After being repeatedly used 10 times, its catalytic activity was hardly changed. Further research showed that the high catalytic performance of the 0.2%Co/MgO catalyst is attributed to its high oxygen-absorbing ability and the high ratio between the amount of weak and medium base sites with the help of the synergistic interaction between Co and MgO.
      PubDate: 2017-05-13
      DOI: 10.3390/catal7050155
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 156: Effective Electron Transfer Pathway of the
           Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity
           under Visible Light

    • Authors: Hongwei Tian, Chenxing Wan, Xin Xue, Xiaoying Hu, Xiaoyi Wang
      First page: 156
      Abstract: Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous TiO2/RGO/Ag (MTGA) nanocomposite exhibited superior photocatalytic performance for the degradation of methylene blue (MB) under visible light, and the degradation rate reached 0.017 min−1, which was 3.4-times higher than that of MTG. What is more, the degradation rate of MTGA nanocomposite after three cycle times is 91.2%, and the composition is unchanged. In addition, we found that the OH•, h+ and especially O2•− contribute to the high photocatalytic activity of MTGA for MB degradation. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR) to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the separation efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance.
      PubDate: 2017-05-15
      DOI: 10.3390/catal7050156
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 157: Development of Active and Stable Low Nickel
           Content Catalysts for Dry Reforming of Methane

    • Authors: Quan Ha, Udo Armbruster, Hanan Atia, Matthias Schneider, Henrik Lund, Giovanni Agostini, Jörg Radnik, Huyen Vuong, Andreas Martin
      First page: 157
      Abstract: Methane dry reforming (DRM) was investigated over highly active Ni catalysts with low metal content (2.5 wt %) supported on Mg-Al mixed oxide. The aim was to minimize carbon deposition and metal sites agglomeration on the working catalyst which are known to cause catalyst deactivation. The solids were characterized using N2 adsorption, X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that MgO-Al2O3 solid solution phases are obtained when calcining Mg-Al hydrotalcite precursor in the temperature range of 550–800 °C. Such phases contribute to the high activity of catalysts with low Ni content even at low temperature (500 °C). Modifying the catalyst preparation with citric acid significantly slows the coking rate and reduces the size of large octahedrally coordinated NiO-like domains, which may easily agglomerate on the surface during DRM. The most effective Ni catalyst shows a stable DRM course over 60 h at high weight hourly space velocity with very low coke deposition. This is a promising result for considering such catalyst systems for further development of an industrial DRM technology.
      PubDate: 2017-05-16
      DOI: 10.3390/catal7050157
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 158: Influence of Dissolved Ions on the Water
           Purification Performance of TiO2-Impregnated Porous Silica Tubes

    • Authors: Mio Hayashi, Tsuyoshi Ochiai, Shoko Tago, Hiromasa Tawarayama, Toshifumi Hosoya, Tsukaho Yahagi, Akira Fujishima
      First page: 158
      Abstract: TiO2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K) was determined to be 4.6 × 10−2 L µmol−1, and the Langmuir-Hinshelwood rate constant (kLH) was calculated as 2.6 µM min−1. To determine the influence of ions on the efficiency of methylene blue degradation, we examined both Milli-Q water (soft water) and Contrex water (hard water) as solvents, and confirmed the reduced purification for the Contrex solution. It was, therefore, considered that the presence of inorganic salts decreased the photocatalytic efficiency. Furthermore, variations in the methylene blue decomposition ability were observed between anion-free and cation-free Contrex. Finally, we concluded that the efficiency of photocatalytic decomposition of TiO2 was influenced by multiple parameters, including the presence of anions and cations, as well as the solution pH.
      PubDate: 2017-05-16
      DOI: 10.3390/catal7050158
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 159: Process Simulation for the Design and Scale
           Up of Heterogeneous Catalytic Process: Kinetic Modelling Issues

    • Authors: Antonio Tripodi, Matteo Compagnoni, Rocco Martinazzo, Gianguido Ramis, Ilenia Rossetti
      First page: 159
      Abstract: Process simulation represents an important tool for plant design and optimization, either applied to well established or to newly developed processes. Suitable thermodynamic packages should be selected in order to properly describe the behavior of reactors and unit operations and to precisely define phase equilibria. Moreover, a detailed and representative kinetic scheme should be available to predict correctly the dependence of the process on its main variables. This review points out some models and methods for kinetic analysis specifically applied to the simulation of catalytic processes, as a basis for process design and optimization. Attention is paid also to microkinetic modelling and to the methods based on first principles, to elucidate mechanisms and independently calculate thermodynamic and kinetic parameters. Different case studies support the discussion. At first, we have selected two basic examples from the industrial chemistry practice, e.g., ammonia and methanol synthesis, which may be described through a relatively simple reaction pathway and the relative available kinetic scheme. Then, a more complex reaction network is deeply discussed to define the conversion of bioethanol into syngas/hydrogen or into building blocks, such as ethylene. In this case, lumped kinetic schemes completely fail the description of process behavior. Thus, in this case, more detailed—e.g., microkinetic—schemes should be available to implement into the simulator. However, the correct definition of all the kinetic data when complex microkinetic mechanisms are used, often leads to unreliable, highly correlated parameters. In such cases, greater effort to independently estimate some relevant kinetic/thermodynamic data through Density Functional Theory (DFT)/ab initio methods may be helpful to improve process description.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050159
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 160: Catalytic Behaviour of CuO-CeO2 Systems
           Prepared by Different Synthetic Methodologies in the CO-PROX Reaction
           under CO2-H2O Feed Stream

    • Authors: Juan Cecilia, Ana Arango-Díaz, Jaasiel Marrero-Jerez, Pedro Núñez, Elisa Moretti, Loretta Storaro, Enrique Rodríguez-Castellón
      First page: 160
      Abstract: CuO-CeO2 catalysts, with 6 wt % of Cu, have been synthesised by different preparation methods (calcination of nitrate precursors, thermal urea-nitrate combustion, freeze-drying method, using polymethyl metacrylate PMMA microspheres as template and precipitation using NaOH or the decomposition of urea as precipitating agents). The obtained materials have been characterised by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, N2 adsorption-desorption at −196 °C, H2 thermoprogrammed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The catalysts displayed high dispersion of copper oxide, obtaining CO conversion values of 90–100% at 115 °C in the CO preferential oxidation in excess of hydrogen (CO-PROX) and maintaining this activity even after 48 h of time on stream. The incorporation of CO2 and H2O in the feed stream (simulating a PROX unit) caused a decrease in the CO conversion, except for the catalyst synthesised using PMMA microspheres as a template which maintained a CO conversion of 95% at 115 °C. This catalyst exhibits an excellent catalytic performance, also under real operating conditions, thanks to many and concomitant factors, such as the very small CeO2 particle size (5.6 nm), the surface being rich in copper (atomic ratio Cu/Ce = 0.35) that is easily reducible, and the peculiar morphology and porosity of the material.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050160
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 161: Reactivity of Copper Electrodes towards
           Functional Groups and Small Molecules in the Context of CO2
           Electro-Reductions

    • Authors: Bernhard Schmid, Christian Reller, Sebastian Neubauer, Maximilian Fleischer, Romano Dorta, Guenter Schmid
      First page: 161
      Abstract: The direct electro-reduction of CO2 to functional molecules like ethene is a highly desirable variant of CO2 utilization. The formation of, for example, ethene from CO2 is a multistep electrochemical process going through various intermediates. As these intermediates are organic species, the CO2 reducing electro-catalyst has to be competent for a variety of organic functional group transformations to yield the final product. In this work, the activity of an in situ-grown nano-structured copper catalyst towards a variety of organic functional group conversions was studied. The model reagents were selected from the product spectrum of actual CO2 reduction reaction (CO2RR) experiments and from proposals in the literature. The CO2 bulk electrolysis benchmark was conducted at 170 mAcm−2 current density with up to 43% Faradaic Efficiency (FE) for ethene and 23% FE for ethanol simultaneously. To assure relevance for application-oriented conditions, the reactivity screening was conducted at elevated current densities and, thus, overpotentials. The found reactivity pattern was then also transferred to the CO reduction reaction (CORR) under benchmark conditions yielding additional insights. The results suggest that at high current density/high overpotential conditions, also other ethene formation pathways apart from acetaldehyde reduction such as CH2 dimerization are present. A new suggestion for a high current density mechanism will be presented, which is in agreement with the experimental observations and the found activity pattern of copper cathodes toward organic functional group conversion.
      PubDate: 2017-05-18
      DOI: 10.3390/catal7050161
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 162: Cellulose with a High Fractal Dimension Is
           Easily Hydrolysable under Acid Catalysis

    • Authors: Mariana Díaz, Magali Hernández, Ilich Ibarra, Ariel Guzmán, Victor Lara, Enrique Lima
      First page: 162
      Abstract: The adsorption of three diverse amino acids couples onto the surface of microcrystalline cellulose was studied. Characterisation of modified celluloses included changes in the polarity and in roughness. The amino acids partially break down the hydrogen bonding network of the cellulose structure, leading to more reactive cellulose residues that were easily hydrolysed to glucose in the presence of hydrochloric acid or tungstophosphoric acid catalysts. The conversion of cellulose and selectivity for glucose was highly dependent on the self-assembled amino acids adsorbed onto the cellulose and the catalyst.
      PubDate: 2017-05-19
      DOI: 10.3390/catal7050162
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 163: Catalytic Processes for Utilizing
           Carbohydrates Derived from Algal Biomass

    • Authors: Sho Yamaguchi, Ken Motokura, Kan Tanaka, Sousuke Imamura
      First page: 163
      Abstract: The high productivity of oil biosynthesized by microalgae has attracted increasing attention in recent years. Due to the application of such oils in jet fuels, the algal biosynthetic pathway toward oil components has been extensively researched. However, the utilization of the residue from algal cells after oil extraction has been overlooked. This residue is mainly composed of carbohydrates (starch), and so we herein describe the novel processes available for the production of useful chemicals from algal biomass-derived sugars. In particular, this review highlights our latest research in generating lactic acid and levulinic acid derivatives from polysaccharides and monosaccharides using homogeneous catalysts. Furthermore, based on previous reports, we discuss the potential of heterogeneous catalysts for application in such processes.
      PubDate: 2017-05-19
      DOI: 10.3390/catal7050163
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 164: Solar and Visible Light Illumination on
           Immobilized Nano Zinc Oxide for the Degradation and Mineralization of
           Orange G in Wastewater

    • Authors: Hung-Yee Shu, Ming-Chin Chang, Tien-Hsin Tseng
      First page: 164
      Abstract: An advanced oxidation process (AOP) utilizing immobilized zinc oxide (ZnO) photocatalyst was employed to decolorize and mineralize orange G (OG) azo dye in wastewater under solar and visible light irradiation. This AOP employed visible light and ZnO in a so-called Vis/ZnO process. Operating parameters, including ZnO dosage, initial OG concentration, pH, visible-light intensity, catalyst loaded area, and treatment volume were investigated to illustrate their influences on OG degradation and mineralization. From the results, neither visible light alone, nor the ZnO adsorption process could degrade or remove OG from wastewater. However, for the Vis/ZnO process, the higher ZnO dosage and visible light intensity are two major parameters to improve the OG degradation and total organic carbons (TOC) mineralization. The initial pH of 11 was the most effective pH condition on the OG degradation. The first-order rate constant is exponentially decreased from 0.025 to 0.0042 min−1 with the increase of the initial OG concentration and an empirical equation can be derived to estimate the first-order rate constant with a known initial OG concentration. In contrast, the first-order rate constant is linearly increased from 0.0027 to 0.0083 min−1 by increasing the visible light intensity. The results present that the Vis/ZnO process is an effective AOP for the degradation of OG in wastewater.
      PubDate: 2017-05-20
      DOI: 10.3390/catal7050164
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 165: Use of Metal Catalysts Bearing Schiff Base
           Macrocycles for the Ring Opening Polymerization (ROP) of Cyclic Esters

    • Authors: Carl Redshaw
      First page: 165
      Abstract: Schiff base macrocycles are emerging as useful scaffolds for binding two or more catalytic metals in close proximity. Such coordination chemistry allows for the evaluation of potentially beneficial catalytic cooperative effects. In the field of ring opening polymerization (ROP) of cyclic esters, only a handful of metal systems bound by Schiff base [2 + 2] type macrocycles have been studied. Nevertheless, results to date have, for certain metals, identified some interesting structure activity relationships, whilst for other systems results have revealed particular combinations of metals and macrocycles to be virtually inactive. This perspective review takes a look at two types of recently-reported Schiff base macrocycles that have been employed as pro-ligands in the metal-catalyzed ROP of cyclic esters, specifically ε-caprolactone and rac-lactide.
      PubDate: 2017-05-22
      DOI: 10.3390/catal7050165
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 166: Catalytic Decomposition of N2O over
           Cu–Zn/ZnAl2O4 Catalysts

    • Authors: Xiaoying Zheng, Runhu Zhang, Fang Bai, Chao Hua
      First page: 166
      Abstract: The catalytic decomposition of N2O was investigated over Cu-Zn/ZnAl2O4 catalysts in the temperature range of 400–650 °C Catalytic samples have been prepared by wet impregnation method. Prepared catalysts were characterized using several techniques like BET surface area, X-ray diffraction (XRD), and Scanning electron microscopy (SEM). The Cu-Zn/ZnAl2O4 showed higher catalytic performance along with long term stability during N2O decomposition. The Cu-Zn/ZnAl2O4 catalysts yielded 100% N2O conversion at 650 °C. The Cu-Zn/ZnAl2O4 catalysts are promising for decrease this strong greenhouse gas in the chemical industry.
      PubDate: 2017-05-22
      DOI: 10.3390/catal7050166
      Issue No: Vol. 7, No. 5 (2017)
       
  • Catalysts, Vol. 7, Pages 96: Total Oxidation of Propane Using CeO2 and
           CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

    • Authors: Benjamin Solsona, Rut Sanchis, Ana Dejoz, Tomas García, Lidia Ruiz-Rodríguez, José López Nieto, Juan Cecilia, Enrique Rodríguez-Castellón
      First page: 96
      Abstract: Several CeO2 and CuO-CeO2 catalysts were prepared using different methods, i.e., a homogeneous precipitation with urea, a nanocasting route using CMK-3 carbon as a hard template and a sol–gel process using Poly(methyl methacrylate) (PMMA) polymer as a soft template, and tested in the total oxidation of propane. The catalysts were characterized by a number of physicochemical techniques (XRD, N2 adsorption, TPR, XPS, Raman spectroscopy) showing distinct characteristics. For each series, Cu-Ce-O catalysts with low Cu-loadings (5 wt % CuO) showed the highest activity, higher than those samples either without copper or with high Cu-loading (13 wt % CuO). The incorporation of copper leads to an increase of the concentration of bulk defects but if the Cu-loading is too high the surface area drastically falls. The highest activity in the total oxidation of propane was achieved by Cu-containing ceria catalysts synthesized using a polymer as a template, as this method yields high surface area materials. The surface area and the number of bulk/sub-surface defects of the ceria seem to be the main properties determining the catalytic activity.
      PubDate: 2017-03-23
      DOI: 10.3390/catal7040096
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 97: Three-Dimensional TiO2 Structures
           Incorporated with Tungsten Oxide for Treatment of Toxic Aromatic Volatile
           Compounds

    • Authors: Joon Lee, Wan-Kuen Jo
      First page: 97
      Abstract: This study assessed 3D WO3–TiO2 nanoflowers (WTNF) synthesized by a combined hydrothermal–ultrasonication–impregnation method for their applicability to the treatment of aromatic volatile compounds under visible-light illumination. The scanning electron microscopy exhibited the formation of 3D structures in the prepared WTNF samples. The X-ray diffraction patterns and energy dispersive X-ray results indicated a successful incorporation of WO3 into TNF structures. The UV-visible spectroscopy showed that the prepared WTNF samples can be functioned under visible light irradiation. The output-to-input concentration ratios of toluene and o-xylene with WTNF samples were lower than those of TiO2 nanoflowers. These findings were illustrated on the basis of charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. The input-to-output concentration ratios of the target chemicals were lowest for 10 M NaOH and highest for 5 M NaOH. The photocatalytic degradation efficiencies of WTNF sample photocatalysts increased with increasing WO3 content from 0.1% to 1.0%, and dropped gradually with increasing WO3 content further to 4.0%. Light-emitting-diodes (LEDs) are a more highly energy-efficient light source compared to a conventional lamp for the photocatalytic degradation of toluene and o-xylene, although the photocatalytic activity is higher for the conventional lamp.
      PubDate: 2017-03-23
      DOI: 10.3390/catal7040097
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 98: Eco-Friendly Physical Activation Methods for
           Suzuki–Miyaura Reactions

    • Authors: Katia Martina, Maela Manzoli, Emanuela Calcio Gaudino, Giancarlo Cravotto
      First page: 98
      Abstract: Eco-compatible activation methods in Suzuki–Miyaura cross-coupling reactions offer challenging opportunities for the design of clean and efficient synthetic processes. The main enabling technologies described in the literature are microwaves, ultrasound, grinding (mechanochemistry) and light. These methods can be performed in water or other green solvents with phase-transfer catalysis or even in solventless conditions. In this review, the authors will summarize the progress in this field mainly from 2010 up to the present day.
      PubDate: 2017-03-23
      DOI: 10.3390/catal7040098
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 99: Fivefold Enhanced Photoelectrochemical
           Properties of ZnO Nanowire Arrays Modified with C3N4 Quantum Dots

    • Authors: Hao Yang, Zhiliang Jin, Hongyan Hu, Gongxuan Lu, Yingpu Bi
      First page: 99
      Abstract: A facile and effective growing strategy of graphite-like carbon nitride quantum dots (CNQDs) modified on ZnO nanowire array composite electrodes has been successfully designed and prepared for the first time. The remarkable quantum enhanced properties were carefully studied by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), UV-vis diffuse reflectance, PEC performance, and photocatalytic hydrogen production, and the results were in good agreement. Fivefold enhanced photoelectrochemical performances of this novel hierarchical hetero-array prepared in this paper compared with pure ZnO nanowire arrays were obtained under UV-light. The effect was attributed to the remarkable charge separation between CNQDs and ZnO nanowire arrays. Additional investigations revealed that the particular structure of CNQDs/ZnO composites contributed to the separation of a photon-generation carrier and an enhanced photoelectric current. Moreover, the absorption edge of CNQD-modified ZnO nanowire arrays was slightly broadened, and the diameter was reduced as well. The photoelectrochemistry hydrogen evolution splitting water using simulated solar irradiation exhibited the foreground of a possible application of a mechanism of photoelectrochemistry hydrogen evolution over CNQDs/ZnO composite electrodes.
      PubDate: 2017-03-24
      DOI: 10.3390/catal7040099
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 100: Visible-Light-Active TiO2-Based Hybrid
           Nanocatalysts for Environmental Applications

    • Authors: Alessandra Truppi, Francesca Petronella, Tiziana Placido, Marinella Striccoli, Angela Agostiano, Maria Curri, Roberto Comparelli
      First page: 100
      Abstract: Photocatalytic nanomaterials such as TiO2 are receiving a great deal of attention owing to their potential applications in environmental remediation. Nonetheless, the low efficiency of this class of materials in the visible range has, so far, hampered their large-scale application. The increasing demand for highly efficient, visible-light-active photocatalysts can be addressed by hybrid nanostructured materials in which two or more units, each characterised by peculiar physical properties, surface chemistry and morphology, are combined together into a single nano-object with unprecedented chemical–physical properties. The present review intends to focus on hybrid nanomaterials, based on TiO2 nanoparticles able to perform visible-light-driven photocatalytic processes for environmental applications. We give a brief overview of the synthetic approaches recently proposed in the literature to synthesise hybrid nanocrystals and discuss the potential applications of such nanostructures in water remediation, abatement of atmospheric pollutants (including NOx and volatile organic compounds (VOCs)) and their use in self-cleaning surfaces.
      PubDate: 2017-03-25
      DOI: 10.3390/catal7040100
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 101: High Catalytic Activity of Heterometallic
           (Fe6Na7 and Fe6Na6) Cage Silsesquioxanes in Oxidations with Peroxides

    • Authors: Alexey Yalymov, Alexey Bilyachenko, Mikhail Levitsky, Alexander Korlyukov, Victor Khrustalev, Lidia Shul’pina, Pavel Dorovatovskii, Marina Es’kova, Frédéric Lamaty, Xavier Bantreil, Benoît Villemejeanne, Jean Martinez, Elena Shubina, Yuriy Kozlov, Georgiy Shul’pin
      First page: 101
      Abstract: Two types of heterometallic (Fe(III),Na) silsesquioxanes—[Ph5Si5O10]2[Ph10Si10O21]Fe6(O2‒)2Na7(H3O+)(MeOH)2(MeCN)4.5.1.25(MeCN), I, and [Ph5Si5O10]2[Ph4Si4O8]2Fe6Na6(O2‒)3(MeCN)8.5(H2O)8.44, II—were obtained and characterized. X-ray studies established distinctive structures of both products, with pair of Fe(III)-O-based triangles surrounded by siloxanolate ligands, giving fascinating cage architectures. Complex II proved to be catalytically active in the formation of amides from alcohols and amines, and thus becoming a rare example of metallasilsesquioxanes performing homogeneous catalysis. Benzene, cyclohexane, and other alkanes, as well as alcohols, can be oxidized in acetonitrile solution to phenol—the corresponding alkyl hydroperoxides and ketones, respectively—by hydrogen peroxide in air in the presence of catalytic amounts of complex II and trifluoroacetic acid. Thus, the cyclohexane oxidation at 20 °C gave oxygenates in very high yield of alkanes (48% based on alkane). The kinetic behaviour of the system indicates that the mechanism includes the formation of hydroxyl radicals generated from hydrogen peroxide in its interaction with di-iron species. The latter are formed via monomerization of starting hexairon complex with further dimerization of the monomers.
      PubDate: 2017-03-27
      DOI: 10.3390/catal7040101
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 102: Caprolactam-Based Brønsted Acidic Ionic
           Liquids for Biodiesel Production from Jatropha Oil

    • Authors: Hui Luo, Heng Yin, Rui Wang, Weiyu Fan, Guozhi Nan
      First page: 102
      Abstract: Caprolactam-based ionic liquids show many advantages, such as the lower toxicity, lower cost, and a simple preparation process. In this work, caprolactam-based ionic liquids were prepared and adopted as catalysts for the transesterification of Jatropha oil with methanol. The results demonstrated that the SO3H-functional caprolactam‐based ionic liquids have higher catalytic activity than those of the caprolactam-based ionic liquids without sulfonic group or the SO3Hfunctional pyridine-based ionic liquids, attributed to their stronger Brønsted acidity. By optimizing the reaction parameter, the biodiesel yield catalyzed by 1-(4-sulfonic group) butylcaprolactamium hydrogen sulfate ([HSO3-bCPL][HSO4]) could reach above 95% at 140 °C for 3 h. Furthermore, the ionic liquid had a good reusability.
      PubDate: 2017-03-27
      DOI: 10.3390/catal7040102
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 103: Dicyclopentadiene Hydroformylation to
           Value-Added Fine Chemicals over Magnetically Separable Fe3O4-Supported
           Co-Rh Bimetallic Catalysts: Effects of Cobalt Loading

    • Authors: Yubo Ma, Jie Fu, Zhixian Gao, Libo Zhang, Chengyang Li, Tianfu Wang
      First page: 103
      Abstract: Six Co-Rh/Fe3O4 catalysts with different cobalt loadings were prepared by the co-precipitation of RhCl3, Co(NO3)2, and Fe(NO3)3 using Na2CO3 as the precipitant. These catalysts were tested for dicyclopentadiene (DCPD) hydroformylation to monoformyltricyclodecenes (MFTD) and diformyltricyclodecanes (DFTD). The results showed that the MFTD formation rate increased with increasing cobalt loading, whereas the DFTD formation rate initially increased and then decreased when the cobalt loading was greater than twice that of Rh. The DFTD selectivity was only 21.3% when monometallic Rh/Fe3O4 was used as the catalyst. In contrast, the selectivity was 90.6% at a similar DCPD conversion when the bimetallic 4Co-2Rh/Fe3O4 catalyst was employed. These catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and thermogravimetric and differential thermal analyses (TG-DTA). The results obtained by these complimentary characterization techniques indicated that adding cobalt to the Rh/Fe3O4 catalyst enhanced the Rh reducibility and dispersion; the Rh reducibility was easily altered, and increasing the cobalt loading improved the Rh dispersion. It was concluded that the enhanced catalytic performance with increasing cobalt loading might be due to the formation of a more reactive Rh species with a different Rh–phosphine interaction strength on the catalyst surface.
      PubDate: 2017-03-30
      DOI: 10.3390/catal7040103
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 104: Methanation of Carbon Dioxide over
           Ni–Ce–Zr Oxides Prepared by One-Pot Hydrolysis of Metal Nitrates with
           Ammonium Carbonate

    • Authors: Wangxin Nie, Xiujing Zou, Chenju Chen, Xueguang Wang, Weizhong Ding, Xionggang Lu
      First page: 104
      Abstract: Ni–Ce–Zr mixed oxides were prepared through one-pot hydrolysis of mixed metal nitrates with ammonium carbonate for CO2 methanation. The effects of Ce/Zr molar ratio and Ni content on catalysts’ physical and chemical properties, reduction degree of Ni2+, and catalytic properties were systematically investigated. The results showed that Zr could lower metallic Ni particle sizes and alter interaction between Ni and supports, resulting in enhancements in the catalytic activity for CO2 methanation. The Ni–Ce–Zr catalyst containing 40 wt % Ni and Ce/Zr molar ratio of 9:1 exhibited the optimal catalytic properties, with 96.2% CO2 conversion and almost 100% CH4 selectivity at a low temperature of 275 °C. During the tested period of 500 h, CO2 conversion and CH4 selectivity over Ni–Ce–Zr catalyst kept constant under 300 °C.
      PubDate: 2017-03-31
      DOI: 10.3390/catal7040104
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 105: Environmental Benign Synthesis of Lithium
           Silicates and Mg-Al Layered Double Hydroxide from Vermiculite Mineral for
           CO2 Capture

    • Authors: Yu Zhang, Tuantuan Zhou, Benoit Louis, Feng Yu, Jianming Dan, Qiang Wang
      First page: 105
      Abstract: This research introduces a completely new environmental benign synthesis route for obtaining two kinds of inter-mediate and high temperature CO2 sorbents, Mg-Al layered double hydroxide (LDH) and Li4SiO4, from vermiculite. The mineral vermiculite was leached with acid, from which the obtained SiO2 was used for the synthesis of Li4SiO4 and the leaching waste water was used for the synthesis of Mg-Al LDH. Therefore, no waste was produced during the whole process. Both Li4SiO4 and Mg-Al LDH sorbents were carefully characterized using XRD, SEM, and BET analyses. The CO2 capturing performance of these two sorbents was comprehensively evaluated. The influence of the Li/Si ratio, calcination temperature, calcination time, and sorption temperature on the CO2 sorption capacity of Li4SiO4, and the sorption temperature on the CO2 sorption capacity of LDH, were investigated. The optimal leaching acid concentration for vermiculite and the CO2 sorption/desorption cycling performance of both the Li4SiO4 and Mg-Al LDH sorbents were determined. In sum, this demonstrated a unique and environment-friendly scheme for obtaining two CO2 sorbents from cheap raw materials, and this idea is applicable to the efficient utilization of other minerals.
      PubDate: 2017-04-03
      DOI: 10.3390/catal7040105
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 106: Thermal Activation of CuBTC MOF for CO
           Oxidation: The Effect of Activation Atmosphere

    • Authors: Xiuling Zhang, Zhibin Zhan, Zhuang Li, Lanbo Di
      First page: 106
      Abstract: High performance catalysts for carbon monoxide (CO) oxidation were obtained through thermal activation of a CuBTC (BTC: 1,3,5-benzenetricarboxylic acid) metal–organic framework (MOF) in various atmospheres. X-ray diffraction (XRD), X-ray photonelectron spectroscopy (XPS), N2 adsorption–desorption measurement, and field emission scanning electron microscopy (FESEM) were adopted to characterize the catalysts. The results show that thermal activation by reductive H2 may greatly destroy the structure of CuBTC. Inert Ar gas has a weak influence on the structure of CuBTC. Therefore, these two catalysts exhibit low CO oxidation activity. Activating with O2 is effective for CuBTC catalysts, since active CuO species may be obtained due to the slight collapse of CuBTC structure. The highest activity is obtained when activating with CO reaction gas, since many pores and more effective Cu2O is formed during the thermal activation process. These results show that the structure and chemical state of coordinated metallic ions in MOFs are adjustable by controlling the activation conditions. This work provides an effective method for designing and fabricating high performance catalysts for CO oxidation based on MOFs.
      PubDate: 2017-04-07
      DOI: 10.3390/catal7040106
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 107: Recyclable Polymer-Supported
           Terpyridine–Palladium Complex for the Tandem Aminocarbonylation of Aryl
           Iodides to Primary Amides in Water Using NaN3 as Ammonia Equivalent

    • Authors: Toshimasa Suzuka, Hiromu Sueyoshi, Kazuhito Ogihara
      First page: 107
      Abstract: Primary aromatic amides are valuable compounds, which are generally prepared via Beckmann rearrangement of oximes and the hydration of nitriles in organic solvents. We investigated the environmentally friendly catalytic aminocarbonylation in water. Thus, a novel heterogeneous transition-metal catalyst, a polymer-supported terpyridine–palladium(II) complex, was prepared and found to promote azidocarbonylation of aryl iodides with NaN3 and to reduce the generated benzoyl azides in water under CO gas to yield primary aryl amides with high to excellent yield in a one-pot reaction. The catalyst was recovered and reused several times with no loss of catalytic activity.
      PubDate: 2017-04-07
      DOI: 10.3390/catal7040107
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 108: Efficient Hydrolysis of Lignocellulose by
           Acidic Ionic Liquids under Low-Toxic Condition to Microorganisms

    • Authors: Kosuke Kuroda, Ken Inoue, Kyohei Miyamura, Heri Satria, Kenji Takada, Kazuaki Ninomiya, Kenji Takahashi
      First page: 108
      Abstract: Lignocellulose is known as a renewable resource, and acidic ionic liquids have been highlighted as efficient catalysts for hydrolysis of cellulose. To achieve successive hydrolysis and fermentation, efficient hydrolysis with sufficiently diluted acidic ionic liquids is necessary because acidic ionic liquids are toxic to fermentative microorganisms. Escherichia coli was confirmed to grow in 0.05 M dilute acidic ionic liquid—1-(1-butylsulfonic)-3-methylimidazolium hydrogen sulfate ([Sbmim][HSO4])—although the growth was suppressed in more concentrated solutions. Therefore, we applied the 0.05 M [Sbmim][HSO4] solution to hydrolysis of bagasse, leading to a glucose yield of 48% at 190 °C. This value is greater than that obtained with a concentrated [Sbmim][HSO4] solution, which is not suitable for the growth of Escherichia coli (yield: 40% in a 1.0 M solution). Efficient hydrolysis with acidic ionic liquids under low-toxic condition was achieved.
      PubDate: 2017-04-07
      DOI: 10.3390/catal7040108
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 109: Characterization of MoVTeNbOx Catalysts
           during Oxidation Reactions Using In Situ/Operando Techniques: A Review

    • Authors: Soe Lwin, Weijian Diao, Chinmoy Baroi, Anne Gaffney, Rebecca Fushimi
      First page: 109
      Abstract: Light alkanes are abundant in shale gas resources. The bulk mixed metal oxide MoVTe(Sb)NbOx catalysts play a very important role in dehydrogenation and selective oxidation reactions of these short hydrocarbons to produce high-value chemicals. This catalyst system mainly consists of M1 and less-active M2 crystalline phases. Due to their ability to directly monitor the catalysts under the relevant industrial conditions, in situ/operando techniques can provide information about the nature of active sites, surface intermediates, and kinetics/mechanisms, and may help with the synthesis of new and better catalysts. Sophisticated catalyst design and understanding is necessary to achieve the desired performance (activity, selectivity, lifetime, etc.) at reasonable reaction conditions (temperature, pressure, etc.). This article critically reviews the progress made in research of these MoVTe(Sb)NbOx catalysts in oxidation reactions mainly through in situ/operando techniques and suggests the future direction needed to realize the industrialization of these catalysts.
      PubDate: 2017-04-08
      DOI: 10.3390/catal7040109
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 110: Study of the V2O5-WO3/TiO2 Catalyst
           Synthesized from Waste Catalyst on Selective Catalytic Reduction of NOx by
           NH3 †

    • Authors: Chunping Qi, Weijun Bao, Liguo Wang, Huiquan Li, Wenfen Wu
      First page: 110
      Abstract: V2O5-WO3/TiO2 catalysts were synthesized from waste selective catalytic reduction (SCR) catalyst through oxalic acid leaching and impregnating with various V2O5 mass loadings. The denitration (deNOx) activity and physiochemical properties of the catalysts were investigated. All the catalysts were characterized by N2 adsorption/desorption, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction. The evaluation result revealed that the deNOx activity of newly synthesized catalyst with 1.0% V2O5 was almost recovered to the level of fresh catalyst, with NO conversion being recovered to 91% at 300 °C, and it also showed a good resistance to SO2 and H2O. The characterization results showed that the decrease of impurities, partial recovery of the V4+/V5+ ratio, and increased reducibility were mainly responsible for the recovery of catalytic activity.
      PubDate: 2017-04-08
      DOI: 10.3390/catal7040110
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 111: Unprecedented Multifunctionality of Grubbs
           and Hoveyda–Grubbs Catalysts: Competitive Isomerization, Hydrogenation,
           Silylation and Metathesis Occurring in Solution and on Solid Phase

    • Authors: Maitena Martinez-Amezaga, Carina Delpiccolo, Luciana Méndez, Ileana Dragutan, Valerian Dragutan, Ernesto Mata
      First page: 111
      Abstract: This contribution showcases the interplay of several non-metathetic reactions (isomerization, silylation and “hydrogen-free” reduction) with metathesis in systems comprising a functionalized olefin and a soluble or resin-immobilized silane. These competing, one-pot reactions occur under activation by second-generation Ru-alkylidene catalysts. Different olefinic substrates were used to study the influence of the substitution pattern on the reaction outcome. Emphasis is placed upon the rarely reported yet important transformations implying a solid phase-supported silane reagent. Catalytic species involved in and reaction pathways accounting for these concurrent processes are evidenced. An unexpected result of this research was the clearly proved partial binding of the olefin to the resin, thereby removing it from the reacting ensemble.
      PubDate: 2017-04-09
      DOI: 10.3390/catal7040111
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 112: Improving the Stability of Cold-Adapted
           Enzymes by Immobilization

    • Authors: ChangWoo Lee, Sei-Heon Jang, Hye-Shin Chung
      First page: 112
      Abstract: Cold-adapted enzymes have gained considerable attention as biocatalysts that show high catalytic activity at low temperatures. However, the use of cold-adapted enzymes at ambient temperatures has been hindered by their low thermal stabilities caused by their inherent structural flexibilities. Accordingly, protein engineering and immobilization have been employed to improve the thermal stability of cold-adapted enzymes. Immobilization has been shown to increase the thermal stability of cold-adapted enzymes at the critical temperatures at which denaturation begins. This review summarizes progress in immobilization of cold-adapted enzymes as a strategy to improve their thermal and organic solvent stabilities.
      PubDate: 2017-04-12
      DOI: 10.3390/catal7040112
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 113: Abatement of VOCs Using Packed Bed
           Non-Thermal Plasma Reactors: A Review

    • Authors: Savita Veerapandian, Christophe Leys, Nathalie De Geyter, Rino Morent
      First page: 113
      Abstract: Non thermal plasma (NTP) reactors packed with non-catalytic or catalytic packing material have been widely used for the abatement of volatile organic compounds such as toluene, benzene, etc. Packed bed reactors are single stage reactors where the packing material is placed directly in the plasma discharge region. The presence of packing material can alter the physical (such as discharge characteristics, power consumption, etc.) and chemical characteristics (oxidation and destruction pathway, formation of by-products, etc.) of the reactor. Thus, packed bed reactors can overcome the disadvantages of NTP reactors for abatement of volatile organic compounds (VOCs) such as lower energy efficiency and formation of unwanted toxic by-products. This paper aims at reviewing the effect of different packing materials on the abatement of different aliphatic, aromatic and chlorinated volatile organic compounds.
      PubDate: 2017-04-12
      DOI: 10.3390/catal7040113
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 114: Steam Reforming of Bio-Compounds with
           Auto-Reduced Nickel Catalyst

    • Authors: Feng Cheng, Valerie Dupont
      First page: 114
      Abstract: As an extension of chemical looping combustion, chemical looping steam reforming (CLSR) has been developed for H2 production. During CLSR, a steam reforming (SR) process occurs following the reduction of catalysts by the reforming feedstock itself (termed “auto-reduction”), as opposed to a separate, dedicated reducing agent like H2. This paper studied SR performances of four common bio-compounds (ethanol, acetone, furfural, and glucose) with a nickel catalyst that had undergone auto-reduction. A packed bed reactor was used to carry out the experiment of auto-reduction and subsequent SR. The effects of temperature and steam to carbon ratio (S/C) on the carbon conversions of the bio-compounds to gases and yields of gaseous products were investigated. The carbon deposition on spent catalysts was characterized by CHN elemental analysis and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX). The SR performance with the auto-reduced catalyst was close to that with the H2-reduced catalyst. In general, an increase in temperature or S/C would lead to an increase in H2 yields. The dependence of SR performance on temperature or S/C was specific to the type of bio-compounds. Accordingly, the main bottlenecks for SR of each bio-compound were summarized. A large amount of CH4 existed in the reforming product of ethanol. Severe carbon deposition was observed for SR of acetone at temperatures below 650 °C. A high thermal stability of furfural molecules or its derivatives restricted the SR of furfural. For SR of glucose, the main problem was the severe agglomeration of catalyst particles due to glucose coking.
      PubDate: 2017-04-13
      DOI: 10.3390/catal7040114
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 115: Lipase-Mediated Amidation of Anilines with
           1,3-Diketones via C–C Bond Cleavage

    • Authors: Liu Zhang, Fengxi Li, Chunyu Wang, Lu Zheng, Zhi Wang, Rui Zhao, Lei Wang
      First page: 115
      Abstract: In this work, an efficient and green lipase-mediated technique has been mined for the amidation of anilines with 1,3-diketones via C–C bond cleavage. Under the optimal conditions, high yields (64.3%–96.2%) could be obtained when Novozym 435 was used as the catalyst. Furthermore, Novozym 435 exhibited a satisfying reusability and more than 80% of yield can be obtained after seven cycles. This work provides a more rapid and mild strategy for amide synthesis with high yield and expands the application of enzyme in organic synthesis.
      PubDate: 2017-04-14
      DOI: 10.3390/catal7040115
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 116: Hydrothermal Fabrication of High Specific
           Surface Area Mesoporous MgO with Excellent CO2 Adsorption Potential at
           Intermediate Temperatures

    • Authors: Wanlin Gao, Tuantuan Zhou, Benoit Louis, Qiang Wang
      First page: 116
      Abstract: In this work, we report on a novel sodium dodecyl sulfate (SDS)-assisted magnesium oxide (MgO)-based porous adsorbent synthesized by hydrothermal method for intermediate CO2 capture. For industrial MgO, its CO2 adsorption capacity is normally less than 0.06 mmol g−1, with a specific surface area as low as 25.1 m2 g−1. Herein, leaf-like MgO nanosheets which exhibited a disordered layer structure were fabricated by the introduction of SDS surfactants and the control of other synthesis parameters. This leaf-like MgO adsorbent showed an excellent CO2 capacity of 0.96 mmol g−1 at moderate temperatures (~300 °C), which is more than ten times higher than that of the commercial light MgO. This novel mesoporous MgO adsorbent also exhibited high stability during multiple CO2 adsorption/desorption cycles. The excellent CO2 capturing performance was believed to be related to its high specific surface area of 321.3 m2 g−1 and abundant surface active adsorption sites. This work suggested a new synthesis scheme for MgO based CO2 adsorbents at intermediate temperatures, providing a competitive candidate for capturing CO2 from certain sorption enhanced hydrogen production processes.
      PubDate: 2017-04-15
      DOI: 10.3390/catal7040116
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 117: Novel Synthesis of Plasmonic Ag/AgCl@TiO2
           Continues Fibers with Enhanced Broadband Photocatalytic Performance

    • Authors: Nan Bao, Xinhan Miao, Xinde Hu, Qingzhe Zhang, Xiuyan Jie, Xiyue Zheng
      First page: 117
      Abstract: The plasmonic Ag/AgCl@TiO2 fiber (S-CTF) photocatalyst was synthesized by a two-step approach, including the sol-gel and force spinning method for the preparation of TiO2 fibers (TF), and the impregnation-precipitation-photoreduction strategy for the deposition of Ag/AgCl onto the fibers. NaOH aqueous solution was utilized to hydrolyze TiCl4, to synthesize TF and remove the byproduct HCl, and the produced NaCl was recycled for the formation and deposition of Ag/AgCl. The surface morphology, specific surface area, textural properties, crystal structure, elemental compositions and optical absorption of S-CTF were characterized by a series of instruments. These results revealed that the AgCl and Ag0 species were deposited onto TF successfully, and the obtained S-CTF showed improved visible light absorption due to the surface plasmon resonance of Ag0. In the photocatalytic degradation of X-3B, S-CTF exhibited significantly enhanced activities under separate visible or UV light irradiation, in comparison to TF.
      PubDate: 2017-04-17
      DOI: 10.3390/catal7040117
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 118: SO42−/Sn-MMT Solid Acid Catalyst for
           Xylose and Xylan Conversion into Furfural in the Biphasic System

    • Authors: Qixuan Lin, Huiling Li, Xiaohui Wang, Longfei Jian, Junli Ren, Chuanfu Liu, Runcang Sun
      First page: 118
      Abstract: A sulphated tin ion-exchanged montmorillonite (SO42−/Sn-MMT) was successfully prepared by the ion exchange method of montmorillonite (MMT) with SnCl4, followed by the sulphation. This catalysis was applied as a solid acid catalyst for the heterogeneous catalytic transformations of xylose and xylan into furfural in the bio-based 2-methyltetrahydrofuran/H2O biphasic system. These prepared catalysts were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), temperature programmed desorption of ammonia (NH3-TPD), pyridine adsorbed Fourier transform infrared spectroscopy (Py-FTIR), element analysis (EA) and Brunauer-Emmett-Teller (BET) method. Their catalytic performance for xylose and xylan into furfural was also investigated. The reaction parameters such as the initial xylose and xylan concentration, the amounts of catalyst, the organic-to-aqueous phase volume ratio, the reaction temperature and time were studied to optimize the reaction conditions. Results displayed that SO42−/Sn-MMT contained both Brønsted acid and Lewis acid sites, and SO42− ions were contributive to the formation of stronger Brønsted acid sites, which could improve the reaction efficiency. Reaction parameters had significant influence on the furfural production. The substitution of water by the saturated NaCl solution in the aqueous phase also had an important effect on the xylose and xylan conversion. The highest furfural yields were achieved up to 79.64% from xylose and 77.35% from xylan under the optimized reaction conditions (160 °C, 120 min; 160 °C, 90 min). Moreover, the prepared catalyst was stable and was reused five times with a slight decrease (10.0%) of the furfural yield.
      PubDate: 2017-04-17
      DOI: 10.3390/catal7040118
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 119: Microwave-Assisted Synthesis of Co3(PO4)2
           Nanospheres for Electrocatalytic Oxidation of Methanol in Alkaline Media

    • Authors: Prabhakarn Arunachalam, Maged Shaddad, Abdullah Alamoudi, Mohamed Ghanem, Abdullah Al-Mayouf
      First page: 119
      Abstract: Low-cost and high-performance advanced electrocatalysts for direct methanol fuel cells are of key significance for the improvement of environmentally-pleasant energy technologies. Herein, we report the facile synthesis of cobalt phosphate (Co3(PO4)2) nanospheres by a microwave-assisted process and utilized as an electrocatalyst for methanol oxidation. The phase formation, morphological surface structure, elemental composition, and textural properties of the synthesized (Co3(PO4)2) nanospheres have been examined by powder X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), field emission-scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption isotherm investigations. The performance of an electrocatalytic oxidation of methanol over a Co3(PO4)2 nanosphere-modified electrode was evaluated in an alkaline solution using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. Detailed studies were made for the methanol oxidation by varying the experimental parameters, such as catalyst loading, methanol concentration, and long-term stability for the electro-oxidation of methanol. The good electrocatalytic performances of Co3(PO4)2 should be related to its good surface morphological structure and high number of active surface sites. The present investigation illustrates the promising application of Co3(PO4)2 nanospheres as a low-cost and more abundant electrocatalyst for direct methanol fuel cells.
      PubDate: 2017-04-17
      DOI: 10.3390/catal7040119
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 120: Quantitative Structure-Thermostability
           Relationship of Late Transition Metal Catalysts in Ethylene
           Oligo/Polymerization

    • Authors: Wenhong Yang, Zhifeng Ma, Jun Yi, Wen-Hua Sun
      First page: 120
      Abstract: Quantitative structure–thermostability relationship was carried out for four series of bis(imino)pyridine iron (cobalt) complexes and α-diimine nickel complexes systems in ethylene oligo/polymerization. Three structural parameters were correlated with thermal stability, including bond order of metal-nitrogen (B), minimum distance (D) between central metal and ortho-carbon atoms on the aryl moiety and dihedral angle (α) of a central five-membered ring. The variation degree of catalytic activities between optimum and room temperatures (AT) was calculated to describe the thermal stability of the complex. By multiple linear regression analysis (MLRA), the thermal stability presents good correlation with three structural parameters with the correlation coefficients (R2) over 0.95. Furthermore, the contributions of each parameter were evaluated. Through this work, it is expected to help the design of a late transition metal complex with thermal stability at the molecular level.
      PubDate: 2017-04-18
      DOI: 10.3390/catal7040120
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 121: Merging Metallic Catalysts and Sonication: A
           Periodic Table Overview

    • Authors: Claudia Domini, Mónica Álvarez, Gustavo Silbestri, Giancarlo Cravotto, Pedro Cintas
      First page: 121
      Abstract: This account summarizes and discusses recent examples in which the combination of ultrasonic waves and metal-based reagents, including metal nanoparticles, has proven to be a useful choice in synthetic planning. Not only does sonication often enhance the activity of the metal catalyst/reagent, but it also greatly enhances the synthetic transformation that can be conducted under milder conditions relative to conventional protocols. For the sake of clarity, we have adopted a structure according to the periodic-table elements or families, distinguishing between bulk metal reagents and nanoparticles, as well as the supported variations, thus illustrating the characteristics of the method under consideration in target synthesis. The coverage focuses essentially on the last decade, although the discussion also strikes a comparative balance between the more recent advancements and past literature.
      PubDate: 2017-04-19
      DOI: 10.3390/catal7040121
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 122: Promotive Effect of Sn2+ on Cu0/Cu+ Ratio
           and Stability Evolution of Cu/SiO2 Catalyst in the Hydrogenation of
           Dimethyl Oxalate

    • Authors: Chuancai Zhang, Denghao Wang, Bin Dai
      First page: 122
      Abstract: The influence of Sn2+doping on the structure and performance of silica supported copper catalyst was systematically investigated and characterised. Catalytic evaluation showed that the suitable content of Sn2+ introduced into a Cu/SiO2 catalyst evidently improved the catalytic activity and stability of ethylene glycol synthesis from dimethyl oxalate. X-ray diffraction and X-ray auger electron spectroscopy indicated that the Cu0/Cu+ ratio gradually increased with increasing Sn2+ content, and an appropriate proportion of Cu0/Cu+ ratio played a very significant role in this reaction. Transmission electron microscopy revealed that the active copper particles in the Cu-xSn/SiO2 catalyst were smaller than those of the Cu/SiO2 catalyst. This result may be due to the introduction of Sn2+ species transformed into SnO2. Furthermore, SnO2 effectively segregated the active copper. These effects are beneficial in inhibiting the aggregation of copper in the catalysts, thereby improving the stability of the catalyst and prolonging the life span.
      PubDate: 2017-04-19
      DOI: 10.3390/catal7040122
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 123: A Simple and Efficient Process for Large
           Scale Glycerol Oligomerization by Microwave Irradiation

    • Authors: Rémi Nguyen, Nicolas Galy, Abhishek Singh, Florian Paulus, Daniel Stöbener, Cathleen Schlesener, Sunil Sharma, Rainer Haag, Christophe Len
      First page: 123
      Abstract: Herein, an optimized method for 100 g scale synthesis of glycerol oligomers using a microwave multimode source and the low priced K2CO3 as catalyst is reported. This method allows the complete conversion of glycerol to its oligomers in only 30 min, yielding molecular weights up to 1000 g mol−1. Furthermore, a simple iterative purification process, involving the precipitation of the crude product in acetone and methanol, affords a final product composed of larger oligomers with a narrow dispersity (D < 1.5).
      PubDate: 2017-04-19
      DOI: 10.3390/catal7040123
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 124: In Search of Governing Gas Flow Mechanism
           through Metal Solid Foams

    • Authors: Anna Gancarczyk, Marcin Piątek, Marzena Iwaniszyn, Przemysław Jodłowski, Joanna Łojewska, Jolanta Kowalska, Andrzej Kołodziej
      First page: 124
      Abstract: Solid foams have been intensely studied as promising structured catalytic internals. However, mechanisms governing flow and transport phenomena within the foam structures have not been properly addressed in the literature. The aim of this study was to consider such flow mechanisms based on our experimental results on flow resistance. Two mechanisms were considered: developing laminar flow in a short capillary channel (flow-through model), and flow around an immersed solid body, either a cylinder or sphere (flow-around model). Flow resistance experiments were performed on three aluminum foams of 10, 20, and 40 PPI (pores per inch), using a 57 mm ID test column filled with the foams studied. The foam morphology was examined using microtomography and optical microscopy to derive the geometric parameters applied in the model equations. The flow-through model provided an accuracy of 25% for the experiments. The model channel diameter was the foam cell diameter, and the channel length was the strut thickness. The accuracy of the flow-around model was only slightly worse (35%). It was difficult to establish the geometry of the immersed solid body (sphere or cylinder) because experiment characteristics tended to change from sphere to cylinder with increasing PPI value.
      PubDate: 2017-04-21
      DOI: 10.3390/catal7040124
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 125: Preparation of Rh/Ni Bimetallic
           Nanoparticles and Their Catalytic Activities for Hydrogen Generation from
           Hydrolysis of KBH4

    • Authors: Liqiong Wang, Liang Huang, Chengpeng Jiao, Zili Huang, Feng Liang, Simin Liu, Yuhua Wang, Haijun Zhang
      First page: 125
      Abstract: ISOBAM-104 protected Rh/Ni bimetallic nanoparticles (BNPs) of 3.1 nm in diameter were synthesized by a co-reduction method with a rapid injection of KBH4 solution. The catalytic activities of as-prepared BNPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated. Ultraviolet-visible spectrophotometry (UV-Vis), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the structure, particle size, and chemical composition of the resultant BNPs. Catalytic activities for hydrolysis of KBH4 and catalytic kinetics of prepared BNPs were also investigated. It was shown that Rh/Ni BNPs displayed much higher catalytic activities than that of Rh or Ni monometallic nanoparticles (MNPs), and the prepared Rh10Ni90 BNPs possessed the highest catalytic activities with a value of 11580 mol-H2·h−1·mol-Rh−1. The high catalytic activities of Rh/Ni BNPs could be attributed to the electron transfer effect between Rh and Ni atoms, which was confirmed by a density functional theory (DFT) calculation. The apparent activation energy for hydrogen generation of the prepared Rh10Ni90 BNPs was about 47.2 ± 2.1 kJ/mol according to a kinetic study.
      PubDate: 2017-04-23
      DOI: 10.3390/catal7040125
      Issue No: Vol. 7, No. 4 (2017)
       
  • Catalysts, Vol. 7, Pages 72: Comparison of Efficiencies and Mechanisms of
           Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce,
           Mg, and Ce-Mg Oxides Loaded Al2O3

    • Authors: Chunmao Chen, Yu Chen, Brandon Yoza, Yuhao Du, Yuxian Wang, Qing Li, Lanping Yi, Shaohui Guo, Qinghong Wang
      First page: 72
      Abstract: The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al2O3) were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP) reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs) are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+) increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions.
      PubDate: 2017-02-24
      DOI: 10.3390/catal7030072
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 73: Catalytic Dehydration of Glycerol to Acrolein
           over a Catalyst of Pd/LaY Zeolite and Comparison with the Chemical
           Equilibrium

    • Authors: Israel Pala Rosas, José Contreras, José Salmones, Carlos Tapia, Beatriz Zeifert, Juan Navarrete, Tamara Vázquez, Diana García
      First page: 73
      Abstract: Glycerol dehydration to acrolein was studied with three catalysts using zeolite-Y. This zeolite in its protonic form (HY), with La (LaY) and Pd with La (Pd/LaY), was characterized by X-ray diffraction (XRD), Fourier-transform-infrared spectroscopy (FTIR) with pyridine, BET, Scanning Electron Microscope (SEM)–Energy-Dispersive Spectroscopy X-ray (EDS) and the catalytic activity tests were carried out under H2 atmosphere. It was found that La ions exchanged in the zeolite-Y resulted in the improvement of both glycerol conversion and yield to acrolein, also a relatively constant glycerol conversion was achieved up to three hours, due to the presence of Pd on the catalyst and H2 in the feed. The comparison of the calculated and experimental yields obtained from the catalytic tests of the Pd/LaY catalyst indicates a greater activity for the reaction to acrolein than for the reaction to acetol. The calculated equilibrium yields of the dehydration reaction from glycerol to acrolein, acetol, ethanal, methanol, and water and the experimental yields of a Pd/LaY catalyst were compared. Thermodynamically, a complete conversion of glycerol can be achieved since the general system remains exothermic and promotes the path to acetol below 480 K. Above this temperature the system consumes energy and favors the production of acrolein, reaching its maximum concentration at 600 K.
      PubDate: 2017-02-25
      DOI: 10.3390/catal7030073
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 74: The Suzuki–Miyaura Cross-Coupling as a
           Versatile Tool for Peptide Diversification and Cyclization

    • Authors: Tom Willemse, Wim Schepens, Herman Vlijmen, Bert Maes, Steven Ballet
      First page: 74
      Abstract: The (site-selective) derivatization of amino acids and peptides represents an attractive field with potential applications in the establishment of structure–activity relationships and labeling of bioactive compounds. In this respect, bioorthogonal cross-coupling reactions provide valuable means for ready access to peptide analogues with diversified structure and function. Due to the complex and chiral nature of peptides, mild reaction conditions are preferred; hence, a suitable cross-coupling reaction is required for the chemical modification of these challenging substrates. The Suzuki reaction, involving organoboron species, is appropriate given the stability and environmentally benign nature of these reactants and their amenability to be applied in (partial) aqueous reaction conditions, an expected requirement upon the derivatization of peptides. Concerning the halogenated reaction partner, residues bearing halogen moieties can either be introduced directly as halogenated amino acids during solid-phase peptide synthesis (SPPS) or genetically encoded into larger proteins. A reversed approach building in boron in the peptidic backbone is also possible. Furthermore, based on this complementarity, cyclic peptides can be prepared by halogenation, and borylation of two amino acid side chains present within the same peptidic substrate. Here, the Suzuki–Miyaura reaction is a tool to induce the desired cyclization. In this review, we discuss diverse amino acid and peptide-based applications explored by means of this extremely versatile cross-coupling reaction. With the advent of peptide-based drugs, versatile bioorthogonal conversions on these substrates have become highly valuable.
      PubDate: 2017-02-25
      DOI: 10.3390/catal7030074
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 75: Effect of Different Nano-Sized Silica Sols as
           Supports on the Structure and Properties of Cu/SiO2 for Hydrogenation of
           Dimethyl Oxalate

    • Authors: Chuancai Zhang, Denghao Wang, Mingyuan Zhu, Feng Yu, Bin Dai
      First page: 75
      Abstract: Cu/x-SiO2 catalysts with 4, 10, and 20 nm silica sols as supports was produced by ammonia evaporation method and characterized. Different nano-sized silica sols as supports significantly affected the structure and catalytic properties of the copper catalysts for ethylene glycol synthesis from dimethyl oxalate. Compared with Cu/20-SiO2 and Cu/4-SiO2 catalysts, the catalytic performance and stability of Cu/10-SiO2 catalyst were greatly enhanced. The Cu/10-SiO2 catalyst showed 99.9% conversion with 94% EG selectivity and a lifetime of over 3080 h if it is calculated by industrial weight liquid hourly space velocity (WLHSV) of 0.5 h−1. The Cu/10-SiO2 catalyst has one of the longest lifetimes among the catalysts and is a good alternative catalyst for this reaction. Improvement in the catalytic performance and stability of Cu/10-SiO2 is attributed to the proper SBET, Dp and larger dispersion of copper. In addition, the supports of Cu/10-SiO2 catalyst have smaller particles than that of Cu/20-SiO2; thus, the migration and growth of copper species in catalysts are restrained during the reaction.
      PubDate: 2017-02-25
      DOI: 10.3390/catal7030075
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 76: Suzuki-Miyaura C-C Coupling Reactions
           Catalyzed by Supported Pd Nanoparticles for the Preparation of Fluorinated
           Biphenyl Derivatives

    • Authors: Roghayeh Erami, Diana Díaz-García, Sanjiv Prashar, Antonio Rodríguez-Diéguez, Mariano Fajardo, Mehdi Amirnasr, Santiago Gómez-Ruiz
      First page: 76
      Abstract: Heterogeneous recyclable catalysts in Suzuki-Miyaura C-C coupling reactions are of great interest in green chemistry as reusable alternatives to homogeneous Pd complexes. Considering the interesting properties of fluorinated compounds for the pharmaceutical industry, as precursors of novel materials, and also as components of liquid crystalline media, this present study describes the preparation of different fluorinated biphenyl derivatives by Suzuki-Miyaura coupling reactions catalyzed by a heterogeneous system (G-COOH-Pd-10) based on Pd nanoparticles supported onto COOH-modified graphene. The catalytic activity of the hybrid material G-COOH-Pd-10 has been tested in Suzuki-Miyaura C–C coupling reactions observing excellent versatility and good conversion rates in the reactions of phenylboronic acid, 4-vinylphenylboronic acid, 4-carboxyphenylboronic acid, and 4-fluorophenylboronic acid with 1-bromo-4-fluorobenzene. In addition, the influence of the arylbromide has been studied by carrying out reactions of 4-fluorophenylboronic acid with 1-bromo-2-fluorobenzene, 1-bromo-3-fluorobenzene, 1-bromo-4-fluorobenzene, 2-bromo-5-fluorotoluene, and 2-bromo-4-fluorotoluene. Finally, catalyst recyclability tests show a good degree of reusability of the system based on G-COOH-Pd-10 as the decrease in catalytic activity after five consecutive catalytic cycles in the reaction of 1-bromo-4-fluorobenzene with 4-florophenylboronic acid at 48 hours of reaction is lower than 8% while in the case of reactions at three hours the recyclability of the systems is much lower.
      PubDate: 2017-02-28
      DOI: 10.3390/catal7030076
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 77: Polymerization of Alkylsilanes on ZIF-8 to
           Hierarchical Siloxane Microspheres and Microflowers

    • Authors: Lin Yang, Congjia Xie, Yizhou Li, Lei Guo, Minfang Nie, Jinping Zhang, Zhiying Yan, Jiaqiang Wang, Wei Wang
      First page: 77
      Abstract: The use of metal-organic frameworks (MOFs) in the polymerization field remains comparatively rare up to now, let alone studies on the fabrication of polymer microstructures through a MOFs-catalyzed assembly process. Zeolitic imidazolate framework-8 (ZIF-8), a well-known MOF for its chemical and thermal stabilities, was used to induce a polymerization reaction of saturated alkylsilanes for the first time. The reaction temperature was found to be critical for morphology control of the polymerized ZIF-siloxane composites. The polymerization of alkylsilanes by ZIF-8 at room temperature resulted in siloxane microspheres while rose petal-like microstructures were obtained at higher temperature. The effects of the reaction time on the structures of the polymerization products were also investigated and the polymerization reaction process was proposed. This work expands the field of MOFs’ applications and develops a reasonable method for the multidimensional assembly of MOFs building blocks into required structures or platforms for designing new kinds of hierarchical morphologies, which to our knowledge has not been previously investigated.
      PubDate: 2017-03-03
      DOI: 10.3390/catal7030077
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 78: Upgrading Lignocellulosic Biomasses:
           Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous
           Pd-Fe Catalysts

    • Authors: Claudia Espro, Bianca Gumina, Emilia Paone, Francesco Mauriello
      First page: 78
      Abstract: This review provides an overview of heterogeneous bimetallic Pd-Fe catalysts in the C–C and C–O cleavage of platform molecules such as C2–C6 polyols, furfural, phenol derivatives and aromatic ethers that are all easily obtainable from renewable cellulose, hemicellulose and lignin (the major components of lignocellulosic biomasses). The interaction between palladium and iron affords bimetallic Pd-Fe sites (ensemble or alloy) that were found to be very active in several sustainable reactions including hydrogenolysis, catalytic transfer hydrogenolysis (CTH) and aqueous phase reforming (APR) that will be highlighted. This contribution concentrates also on the different synthetic strategies (incipient wetness impregnation, deposition-precipitaion, co-precipitaion) adopted for the preparation of heterogeneous Pd-Fe systems as well as on the main characterization techniques used (XRD, TEM, H2-TPR, XPS and EXAFS) in order to elucidate the key factors that influence the unique catalytic performances observed.
      PubDate: 2017-03-07
      DOI: 10.3390/catal7030078
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 79: Two-Dimensional Layered Double Hydroxide
           Derived from Vermiculite Waste Water Supported Highly Dispersed Ni
           Nanoparticles for CO Methanation

    • Authors: Panpan Li, Mingyuan Zhu, Zhiqun Tian, Yang Han, Yu Zhang, Tuantuan Zhou, Lihua Kang, Jianming Dan, Xuhong Guo, Feng Yu, Qiang Wang, Bin Dai
      First page: 79
      Abstract: Expanded multilayered vermiculite (VMT) was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS) exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO2 nanomesh (2D VMT-SiO2) by mixed-acid etching of VMT. Compared with three-dimensional (3D) MCM-41, 2D VMT-SiO2 as a catalyst support provided a superior position for implantation of NiO species and the as-obtained catalyst exhibited excellent performance. In this paper, we successfully synthesized a layered double hydroxide (LDH) using the spent liquor after mixed-acid etching of VMT, which mainly contained Mg2+ and Al3+. The as-calcined layered double oxide (LDO) was used as a catalyst support for CO methanation. Compared with Ni/MgAl-LDO, Ni/VMT-LDO had smaller active component particles; therefore, in this study, it exhibited excellent catalytic performance over the whole temperature range of 250–500 °C. Ni/VMT-LDO achieved the best activity with 87.88% CO conversion, 89.97% CH4 selectivity, and 12.47 × 10−2·s−1 turn over frequency (TOF) at 400 °C under a gas hourly space velocity of 20,000 mL/g/h. This study demonstrated that VMT-LDO as a catalyst support provided an efficient way to develop high-performance catalysts for synthetic natural gas (SNG) from syngas.
      PubDate: 2017-03-07
      DOI: 10.3390/catal7030079
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 80: Electrocatalysts Prepared by Galvanic
           Replacement

    • Authors: Athanasios Papaderakis, Ioanna Mintsouli, Jenia Georgieva, Sotiris Sotiropoulos
      First page: 80
      Abstract: Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases) hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a Mnoble-rich shell and M-rich core (denoted as Mnoble(M)) leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition) as well as the various options for the support are also reviewed.
      PubDate: 2017-03-08
      DOI: 10.3390/catal7030080
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 81: Synthesis of Renewable Diesel Range Alkanes
           by Hydrodeoxygenation of Palmitic Acid over 5% Ni/CNTs under Mild
           Conditions

    • Authors: Yanan Duan, Ranran Ding, Yanchun Shi, Xiao Fang, Husheng Hu, Mingde Yang, Yulong Wu
      First page: 81
      Abstract: Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound of bio-oil under a mild condition of 240 °C reaction temperature and 2 MPa H2 pressure. The experimental results revealed that the main reaction product was pentadecane (yield of 89.64%) at an optimum palmitic acid conversion of 97.25% via the hydrodecarbonylation (HDC) process. The deoxygenation mechanism for palmitic acid conversion was also investigated. This study provides technical parameters and a theoretical basis for further industrialization in the bio-oil upgrading process.
      PubDate: 2017-03-09
      DOI: 10.3390/catal7030081
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 82: Biotemplated Mesoporous TiO2/SiO2 Composite
           Derived from Aquatic Plant Leaves for Efficient Dye Degradation

    • Authors: Zhiying Yan, Jiao He, Lei Guo, Yueting Li, Deliang Duan, Yongjuan Chen, Junjie Li, Fagui Yuan, Jiaqiang Wang 
      First page: 82
      Abstract: The biotemplating technique is an environmental-protective high-efficiency new technology by which the resulting TiO2 may simultaneously attain the duplication of structure and self-doping elements from biotemplate materials, which is highly desirable for photocatalytic applications. In this paper, aquatic plant leaves—including reed, water hyacinth, and duckweed—were used as both templates and silicon precursors to successfully synthesize biomorphic TiO2/SiO2 composite with mesoporous structures. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, and UV–visible diffuse reflectance spectra were applied to characterize the microstructures of the samples. The results show that all TiO2/SiO2 composites are mainly composed of an anatase phase with mesoporous structure and possess high specific surface area. Compared with commercial Degussa P25 TiO2, all TiO2/SiO2 samples display intensive light-harvesting efficiency, particularly in the visible light range. The activities were evaluated by using gentian violet as a target for photocatalytic degradation experiments under simulated solar irradiation. The TiO2/SiO2 samples templated by reed and water hyacinth leaves exhibit high activity, while the TiO2/SiO2 samples obtained from duckweed are inferior to P25 in the degradation of gentian violet. A synergistic effect of SiO2 incorporation and structural construction through biotemplating is proposed to be beneficial to photocatalytic activity.
      PubDate: 2017-03-09
      DOI: 10.3390/catal7030082
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 83: Review of Heterogeneous Catalysts for
           Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels

    • Authors: Xianhui Zhao, Lin Wei, Shouyun Cheng, James Julson
      First page: 83
      Abstract: To address the issues of greenhouse gas emissions associated with fossil fuels, vegetable oilseeds, especially non-food oilseeds, are used as an alternative fuel resource. Vegetable oil derived from these oilseeds can be upgraded into hydrocarbon biofuel. Catalytic cracking and hydroprocessing are two of the most promising pathways for converting vegetable oil to hydrocarbon biofuel. Heterogeneous catalysts play a critical role in those processes. The present review summarizes current progresses and remaining challenges of vegetable oil upgrading to biofuel. The catalyst properties, applications, deactivation, and regeneration are reviewed. A comparison of catalysts used in vegetable oil and bio-oil upgrading is also carried out. Some suggestions for heterogeneous catalysts applied in vegetable oil upgrading to improve the yield and quality of hydrocarbon biofuel are provided for further research in the future.
      PubDate: 2017-03-11
      DOI: 10.3390/catal7030083
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 84: Solvent-Free Biginelli Reactions Catalyzed by
           Hierarchical Zeolite Utilizing a Ball Mill Technique: A Green Sustainable
           Process

    • Authors: Ameen Shahid, Nesreen Ahmed, Tamer Saleh, Shaeel Al-Thabaiti, Sulaiman Basahel, Wilhelm Schwieger, Mohamed Mokhtar
      First page: 84
      Abstract: A sustainable, green one-pot process for the synthesis of dihydropyrimidinones (DHPMs) derivatives by a three-component reaction of β-ketoester derivatives, aldehyde and urea or thiourea over the alkali-treated H-ZSM-5 zeolite under ball-milling was developed. Isolation of the product with ethyl acetate shadowed by vanishing of solvent was applied. The hierachical zeolite catalyst (MFI27_6) showed high yield (86%–96%) of DHPMs in a very short time (10–30 min). The recyclability of the catalyst for the subsequent reactions was examined in four subsequent runs. The catalyst was shown to be robust without a detectable reduction in catalytic activity, and high yields of products showed the efficient protocol of the Biginelli reactions.
      PubDate: 2017-03-13
      DOI: 10.3390/catal7030084
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 85: Olefin Metathesis with Ru-Based Catalysts
           Exchanging the Typical N-Heterocyclic Carbenes by a
           Phosphine–Phosphonium Ylide

    • Authors: Laia Arnedo, Remi Chauvin, Albert Poater
      First page: 85
      Abstract: Density functional theory (DFT) calculations have been used to describe the first turnover of an olefin metathesis reaction calling for a new in silico family of homogenous Ru-based catalysts bearing a phosphine–phosphonium ylide ligand, with ethylene as a substrate. Equal to conventional Ru-based catalysts bearing an N-heterocyclic carbene (NHC) ligand, the activation of these congeners occurs through a dissociative mechanism, with a more exothermic first phosphine dissociation step. In spite of a stronger electron-donating ability of a phosphonium ylide C-ligand with respect to a diaminocarbene analogue, upper energy barriers were calculated to be on average ca. 5 kcal/mol higher than those of Ru–NHC standards. Overall, the study also highlights advantages of bidentate ligands over classical monodentate NHC and phosphine ligands, with a particular preference for the cis attack of the olefin. The new generation of catalysts is constituted by cationic complexes potentially soluble in water, to be compared with the typical neutral Ru–NHC ones.
      PubDate: 2017-03-14
      DOI: 10.3390/catal7030085
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 86: Dendrimer-Stabilized Ru Nanoparticles
           Immobilized in Organo-Silica Materials for Hydrogenation of Phenols

    • Authors: Eduard Karakhanov, Anton Maximov, Anna Zolotukhina, Adila Mamadli, Anna Vutolkina, Andrey Ivanov
      First page: 86
      Abstract: New hybrid catalysts based on Ru nanoparticles, encapsulated into poly(propylene imine dendrimers), immobilized into silica pores, were synthesized and examined for the hydrogenation of alkyl-substituted phenols. The corresponding alkyl-substituted cyclohexanols were presented as the major reaction products, while incomplete hydrogenation products appeared to be minor. A competition between the sterical factors of dendrimer-containing carriers and the electronic factors of substrate substituents influenced the hydrogenation rate of the alkyl-substituted phenols. The carrier structure was found to have a significant influence on both the physical and chemical properties of the catalysts and their hydrogenation activity. The synthesized hybrid catalysts appeared to be stable after recycling and could be re-used several times without significant loss of activity.
      PubDate: 2017-03-14
      DOI: 10.3390/catal7030086
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 87: Recent Advancements in Stereoselective Olefin
           Metathesis Using Ruthenium Catalysts

    • Authors: T. Patrick Montgomery, Adam M. Johns, Robert H. Grubbs
      First page: 87
      Abstract: Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three categories of Z-selective olefin metathesis catalysts has made Z-olefins easily accessible to both laboratory and industrial chemists. Further design enhancements to asymmetric olefin metathesis catalysts have streamlined the construction of complex molecules. The understanding gained in these areas has extended to the employment of ruthenium catalysts to stereoretentive olefin metathesis, the first example of a kinetically E-selective process. These advancements, as well as synthetic applications of the newly developed catalysts, are discussed.
      PubDate: 2017-03-14
      DOI: 10.3390/catal7030087
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 88: The Role of Ruthenium in CO2 Capture and
           Catalytic Conversion to Fuel by Dual Function Materials (DFM)

    • Authors: Shuoxun Wang, Erik T. Schrunk, Harshit Mahajan, and Robert J. Farrauto
      First page: 88
      Abstract: Development of sustainable energy technologies and reduction of carbon dioxide in the atmosphere are the two effective strategies in dealing with current environmental issues. Herein we report a Dual Function Material (DFM) consisting of supported sodium carbonate in intimate contact with dispersed Ru as a promising catalytic solution for combining both approaches. The Ru-Na2CO3 DFM deposited on Al2O3 captures CO2 from a flue gas and catalytically converts it to synthetic natural gas (i.e., methane) using H2 generated from renewable sources. The Ru in the DFM, in combination with H2, catalytically hydrogenates both adsorbed CO2 and the bulk Na2CO3, forming methane. The depleted sites adsorb CO2 through a carbonate reformation process and in addition adsorb CO2 on its surface. This material functions well in O2- and H2O-containing flue gas where the favorable Ru redox property allows RuOx, formed during flue gas exposure, to be reduced during the hydrogenation cycle. As a combined CO2 capture and utilization scheme, this technology overcomes many of the limitations of the conventional liquid amine-based CO2 sorbent technology.
      PubDate: 2017-03-17
      DOI: 10.3390/catal7030088
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 89: Pd/C Catalysis under Microwave Dielectric
           Heating

    • Authors: Elena Cini, Elena Petricci, Maurizio Taddei
      First page: 89
      Abstract: Microwave-assisted organic synthesis (MAOS) provides a novel and efficient means of achieving heat organic reactions. Nevertheless, the potential arcing phenomena via microwave (MW) interaction with solid metal catalysts has limited its use by organic chemists. As arcing phenomena are now better understood, new applications of Pd/C-catalyzed reactions under MW dielectric heating are now possible. In this review, the state of the art, benefits, and challenges of coupling MW heating with heterogeneous Pd/C catalysis are discussed to inform organic chemists about their use with one of the most popular heterogeneous catalysts.
      PubDate: 2017-03-20
      DOI: 10.3390/catal7030089
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 90: Organocatalytic Enantioselective Epoxidation
           of Some Aryl-Substituted Vinylidenebisphosphonate Esters: On the Way to
           Chiral Anti-Osteoporosis Drugs

    • Authors: Andrea Chiminazzo, Laura Sperni, Alessandro Scarso, Giorgio Strukul
      First page: 90
      Abstract: The synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic activators having a basic character, with the best results being observed using quinine and sparteine. These activators not only provide from good to excellent epoxide yields with a large variety of VBPs, but also interesting enantioselectivities in the 67%–96% ee range, at least in the case of the Ph and m-MeO–Ph VBP derivatives, opening the way to a number of chiral anti-osteoporosis potentially active pharmaceutical ingredients.
      PubDate: 2017-03-20
      DOI: 10.3390/catal7030090
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 91: Stabilization of a Lipolytic Enzyme for
           Commercial Application

    • Authors: Simone Antonio De Rose, Halina Novak, Andrew Dowd, Sukriti Singh, Dietmar Andreas Lang, Jennifer Littlechild
      First page: 91
      Abstract: Thermomyces lanouginosa lipase has been used to develop improved methods for carrier-free immobilization, the Cross-Linked Enzyme Aggregates (CLEAs), for its application in detergent products. An activator step has been introduced to the CLEAs preparation process with the addition of Tween 80 as activator molecule, in order to obtain a higher number of the individual lipase molecules in the ”open lid” conformation prior to the cross-linking step. A terminator step has been introduced to quench the cross-linking reaction at an optimal time by treatment with an amine buffer in order to obtain smaller and more homogenous cross-linked particles. This improved immobilization method has been compared to a commercially available enzyme and has been shown to be made up of smaller and more homogenous particles with an average diameter of 1.85 ± 0.28 µm which are 129.7% more active than the free enzyme. The CLEAs produced show improved features for commercial applications such as an improved wash performance comparable with the free enzyme, improved stability to proteolysis and a higher activity after long-term storage.
      PubDate: 2017-03-21
      DOI: 10.3390/catal7030091
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 92: Catalytic Transfer Hydrogenation of Biobased
           HMF to 2,5-Bis-(Hydroxymethyl)Furan over Ru/Co3O4

    • Authors: Ting Wang, Junhua Zhang, Wenxing Xie, Yanjun Tang, Daliang Guo, Yonghao Ni
      First page: 92
      Abstract: 2,5-Bis-(hydroxymethyl)furan (BHMF) is an important biomass-based platform chemical that can be derived from the hydrogenation of biomass-based 5-hydroxymethylfurfural (HMF). In this paper, the formation of BHMF from HMF via the catalytic transfer hydrogenation (CTH) process, using isopropanol as the hydrogen source and Ru/Co3O4 as the catalyst, was studied. The results revealed that the Ru/Co3O4 catalyst displayed a high catalytic efficiency, and that a BHMF yield of up to 82% was obtained at 190 °C in 6 h. Moreover, it was found that the recovered Ru/Co3O4 exhibited a similar catalytic activity to the pristine Ru/Co3O4 catalyst. These results supported the conclusion that the present CTH process is an attractive green route for the synthesis of BHMF from biomass-based HMF.
      PubDate: 2017-03-21
      DOI: 10.3390/catal7030092
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 93: Photocatalytic Water Oxidation on ZnO: A
           Review

    • Authors: Sharifah Bee Abdul Hamid, Swe Jyan Teh, Chin Wei Lai
      First page: 93
      Abstract: The investigation of the water oxidation mechanism on photocatalytic semiconductor surfaces has gained much attention for its potential to unlock the technological limitations of producing H2 from carbon-free sources, i.e., H2O. This review seeks to highlight the available scientific and fundamental understanding towards the water oxidation mechanism on ZnO surfaces, as well as present a summary on the modification strategies carried out to increase the photocatalytic response of ZnO.
      PubDate: 2017-03-21
      DOI: 10.3390/catal7030093
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 94: Graphene Oxide-Supported Oxime Palladacycles
           as Efficient Catalysts for the Suzuki–Miyaura Cross-Coupling Reaction of
           Aryl Bromides at Room Temperature under Aqueous Conditions

    • Authors: Melania Gómez-Martínez, Alejandro Baeza, Diego A. Alonso
      First page: 94
      Abstract: Palladacycles are highly efficient precatalysts in cross-coupling reactions whose immobilization on carbonaceous materials has been hardly studied. Herein, we report a detailed study on the synthesis and characterization of new oxime palladacycle-graphene oxide non-covalent materials along with their catalytic activity in the Suzuki–Miyaura reaction. Catalyst 1-GO, which has been fully characterized by ICP, XPS, TGA, and UV-Vis analyses has been demonstrated to be an efficient catalyst for the Suzuki–Miyaura coupling between aryl bromides and arylboronic acids using very low catalyst loadings (0.002 mol % of Pd) at room temperature under aqueous conditions.
      PubDate: 2017-03-22
      DOI: 10.3390/catal7030094
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 95: Highly Selective Solid Acid Catalyst
           H1−xTi2(PO4)3−x(SO4)x for Non-Oxidative Dehydrogenation of Methanol
           and Ethanol

    • Authors: Gheorghiţa Mitran, Daniel Mieritz, Dong-Kyun Seo
      First page: 95
      Abstract: The conversion of alcohols towards aldehydes in the presence of catalysts by non-oxidative dehydrogenation requires special importance from the perspective of green chemistry. Sodium (Na) super ionic conductor (NASICON)-type hydrogen titanium phosphate sulfate (HTPS; H1−xTi2(PO4)3−x(SO4)x, x = 0.5–1) catalysts were synthesized by the sol-gel method, characterized by N2 gas sorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), NH3 temperature-programmed desorption (NH3-TPD), ultraviolet–visible (UV-VIS) spectroscopy, and their catalytic properties were studied for the non-oxidative dehydrogenation of methanol and ethanol. The ethanol is more reactive than methanol, with the conversion for ethanol exceeding 95% as compared to methanol, where the conversion has a maximum value at 55%. The selectivity to formaldehyde is almost 100% in methanol conversion, while the selectivity to acetaldehyde decreases from 56% to 43% in ethanol conversion, when the reaction temperature is increased from 250 to 400 °C.
      PubDate: 2017-03-22
      DOI: 10.3390/catal7030095
      Issue No: Vol. 7, No. 3 (2017)
       
  • Catalysts, Vol. 7, Pages 67: Improved CO Oxidation Activity of 3DOM
           Pr-Doped Ceria Catalysts: Something Other Than an Ordered Macroporous
           Structure

    • Authors: Arantxa Davó-Quiñonero, Jorge González-Mira, Ion Such-Basañez, Jerónimo Juan-Juan, Dolores Lozano-Castelló, Agustín Bueno-López
      First page: 67
      Abstract: It is demonstrated that the synthesis procedure for preparing three-dimensionally ordered macroporous (3DOM) Pr-doped ceria catalysts using a polymethylmethacrylate (PMMA) template not only affects the porous structure, but also the chemistry of the ceria surface. The PMMA template does not affect the crystalline features (type of phases, crystallite size, and cell parameter) of Pr-doped ceria, Ce and Pr location into the particles, and the bulk reduction of the Ce-Pr mixed oxide catalysts. On the contrary, the utilization of the PMMA template improves both the porosity and surface redox properties. 3DOM Ce-Pr mixed oxide catalysts combine micro, meso, and macropores, the most area being in the macropore range, while a reference unshaped catalyst presents poor porosity in all ranges. However, the catalyzed CO oxidation rates do not correlate with the surface area of the catalysts (neither micro nor meso/macro). The Ce-Pr-3DOM catalyst also presents improved surface reducibility with regards to the counterpart reference material prepared without the template, and improved redox behavior under reaction conditions; that is, it has a higher area and this area is reduced and reoxidized more easily. X-ray photoelectron spectroscopy analysis evidences that this is mainly attributed to praseodymium cations, which accomplish redox cycles more easily than cerium cations.
      PubDate: 2017-02-17
      DOI: 10.3390/catal7020067
      Issue No: Vol. 7, No. 2 (2017)
       
  • Catalysts, Vol. 7, Pages 68: On Metal Segregation of Bimetallic
           Nanocatalysts Prepared by a One-Pot Method in Microemulsions

    • Authors: Concha Tojo, David Buceta, Manuel López-Quintela
      First page: 68
      Abstract: A comparative study on different bimetallic nanocatalysts prepared from microemulsions using a one-pot method has been carried out. The analysis of experimental observations, complemented by simulation studies, provides detailed insight into the factors affecting nanoparticle architecture: (1) The metal segregation in a bimetallic nanocatalysts is the result of the combination of three main kinetic parameters: the reduction rate of metal precursors (related to reduction standard potentials), the material intermicellar exchange rate (determined by microemulsion composition), and the metal precursors concentration; (2) A minimum difference between the reduction standard potentials of the two metals of 0.20 V is needed to obtain a core-shell structure. For values ∆ε0 smaller than 0.20 V the obtaining of alloys cannot be avoided, neither by changing the microemulsion nor by increasing metal concentration; (3) As a rule, the higher the film flexibility around the micelles, the higher the degree of mixture in the nanocatalyst; (4) A minimum concentration of metal precursors is required to get a core-shell structure. This minimum concentration depends on the microemulsion flexibility and on the difference in reduction rates.
      PubDate: 2017-02-17
      DOI: 10.3390/catal7020068
      Issue No: Vol. 7, No. 2 (2017)
       
  • Catalysts, Vol. 7, Pages 69: Effect of CO Concentration on the α-Value of
           Plasma-Synthesized Co/C Catalyst in Fischer-Tropsch Synthesis

    • Authors: James Aluha, Yongfeng Hu, Nicolas Abatzoglou
      First page: 69
      Abstract: A plasma-synthesized cobalt catalyst supported on carbon (Co/C) was tested for Fischer-Tropsch synthesis (FTS) in a 3-phase continuously-stirred tank slurry reactor (3-φ-CSTSR) operated isothermally at 220 °C (493 K), and 2 MPa pressure. Initial syngas feed stream of H2:CO ratio = 2 with molar composition of 0.6 L/L (60 vol %) H2 and 0.3 L/L (30 vol %) CO, balanced in 0.1 L/L (10 vol %) Ar was used, flowing at hourly space velocity (GHSV) of 3600 cm3·h−1·g−1 of catalyst. Similarly, other syngas feed compositions of H2:CO ratio = 1.5 and 1.0 were used. Results showed ~40% CO conversion with early catalyst selectivity inclined towards formation of gasoline (C4–C12) and diesel (C13–C20) fractions. With prolonged time-on-stream (TOS), catalyst selectivity escalated towards the heavier molecular-weight fractions such as waxes (C21+). The catalyst’s α-value, which signifies the probability of the hydrocarbon chain growth was empirically determined to be in the range of 0.85–0.87 (at H2:CO ratio = 2), demonstrating prevalence of the hydrocarbon-chain propagation, with particular predisposition for wax production. The inhibiting CO effect towards FTS was noted at molar H2:CO ratio of 1.0 and 1.5, giving only ~10% and ~20% CO conversion respectively, although with a high α-value of 0.93 in both cases, which showed predominant production of the heavier molecular weight fractions.
      PubDate: 2017-02-21
      DOI: 10.3390/catal7020069
      Issue No: Vol. 7, No. 2 (2017)
       
  • Catalysts, Vol. 7, Pages 70: Development of Ni-Based Catalysts Derived
           from Hydrotalcite-Like Compounds Precursors for Synthesis Gas Production
           via Methane or Ethanol Reforming

    • Authors: Ya-Li Du, Xu Wu, Qiang Cheng, Yan-Li Huang, Wei Huang
      First page: 70
      Abstract: As a favorably clean fuel, syngas (synthesis gas) production has been the focus of concern in past decades. Substantial literatures reported the syngas production by various catalytic reforming reactions particularly in methane or ethanol reforming. Among the developed catalysts in these reforming processes, Ni-based catalysts from hydrotalcite-like compounds (HTLcs) precursors have drawn considerable attention for their preferable structural traits. This review covers the recent literature reporting syngas production with Ni-based catalysts from HTLc precursors via methane or ethanol reforming. The discussion was initiated with catalyst preparation (including conventional and novel means), followed by subsequent thermal treatment processes, then composition design and the addition of promoters in these catalysts. As Ni-based catalysts have thermodynamic potential to deactivate because of carbon deposition or metal sintering, measures for dealing with these problems were finally summarized. To obtain optimal catalytic performances and resultantly better syngas production, based on analyzing the achievements of the references, some perspectives were finally proposed.
      PubDate: 2017-02-20
      DOI: 10.3390/catal7020070
      Issue No: Vol. 7, No. 2 (2017)
       
  • Catalysts, Vol. 7, Pages 71:
           Novel Fe‐W‐Ce Mixed Oxide for the Selective 
           Catalytic Reduction of NOx with NH3 at Low  Temperatures

    • Authors: Anna Stahl, Zhong Wang, Tobias Schwämmle, Jun Ke, Xuebing Li
      First page: 71
      Abstract: A set of novel iron doped cerium‐tungsten catalysts were prepared by sol‐gel method with a view to their application for low temperature selective catalytic reduction (SCR) of NOx with NH3 in power plants. With a molar ratio Fe/W/Ce of 0.5:1:1, a NOx reduction of >90% at 200 °C was achieved. In Fe-W-Ce catalysts with low iron oxide content, it was found that the iron compounds were highly dispersed and formed a solid solution within the cerium oxide lattice, which promoted the SCR activity. Large amounts of iron in the catalysts might form a layer of Fe2O3 on the catalyst surface, which induced the synergistic inhibition effect among Fe, Ce and W species. Moreover, the Fe‐W‐Ce catalysts possessed a high resistance to changed operation parameters as well as to deactivation by SO2 and/or H2O. The novel catalyst showed to be competitive among recently developed low‐temperature SCR catalysts.
      PubDate: 2017-02-20
      DOI: 10.3390/catal7020071
      Issue No: Vol. 7, No. 2 (2017)
       
 
 
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