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  Subjects -> CHEMISTRY (Total: 871 journals)
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CHEMISTRY (610 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 13)
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: 42)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 20)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 20)
ACS Macro Letters     Full-text available via subscription   (Followers: 25)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 40)
ACS Nano     Full-text available via subscription   (Followers: 264)
ACS Photonics     Full-text available via subscription   (Followers: 13)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chimica Slovenica     Open Access  
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 54)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 64)
Advances in Chemical Science     Open Access   (Followers: 15)
Advances in Chemistry     Open Access   (Followers: 20)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 21)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 25)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 61)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Chemistry     Open Access   (Followers: 29)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 165)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 236)
Annales UMCS, Chemia     Open Access  
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
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: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 8)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 31)
Arabian Journal of Chemistry     Open Access   (Followers: 5)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 333)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 20)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 120)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 84)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 71)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 9)
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: 17)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 73)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 22)
Chemical Reviews     Full-text available via subscription   (Followers: 182)
Chemical Science     Open Access   (Followers: 23)
Chemical Technology     Open Access   (Followers: 21)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Hybrid Journal   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 151)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 243)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 19)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 11)
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: 11)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 5)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
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: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 70)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  

        1 2 3 4 | Last

Journal Cover Catalysts
  [SJR: 1.123]   [H-I: 14]   [9 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2073-4344
   Published by MDPI Homepage  [198 journals]
  • Catalysts, Vol. 8, Pages 124: Conversion of South African Coal Fly Ash
           into High-Purity ZSM-5 Zeolite without Additional Source of Silica or
           Alumina and Its Application as a Methanol-to-Olefins Catalyst

    • Authors: Roland Missengue, Pit Losch, Nicholas Musyoka, Benoit Louis, Patrick Pale, Leslie Petrik
      First page: 124
      Abstract: Characteristics of ZSM-5 synthesized from H2SO4-treated coal fly ash and fused coal fly ash extracts are compared in this study. In the synthesis process, fused coal fly ash extract (without an additional silica source) was used in the synthesis of ZSM-5. The effect of the structure-directing agent (tetrapropylammonium bromide, 1,6-hexanediamine or 1-propylamine) on the properties and methanol-to-olefins (MTO) effectiveness of the fly ash-based ZSM-5 was also investigated. A pure ZSM-5 synthesized from the fused coal fly ash extract led to a methanol conversion higher than 90% after 5 h on stream. The template 1,6-hexanediamine led to the synthesis of the most stable fly ash-based catalyst keeping a 44% methanol conversion after 24 h on stream.
      Citation: Catalysts
      PubDate: 2018-03-21
      DOI: 10.3390/catal8040124
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 125: Active Component Migration and Catalytic
           Properties of Nitrogen Modified Composite Catalytic Materials

    • Authors: Miaomiao Li, Peng Gui, Luning Zheng, Jiaang Li, Gang Xue, Jinsheng Liang
      First page: 125
      Abstract: During the catalytic combustion reaction of methane, the migration of the active species on surface facilitates the catalytic reaction, and the element doping can improve the redox performance of the catalyst. Nitrogen-modified perovskite type composite catalysts were prepared by hydrothermal method and then characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), temperature-programmed reductions (TPR), and X-ray photoelectron spectra (XPS). The results revealed that nitrogen sources (urea, biuret, melamine, carbohydrazide, and semicarbazide hydrochloride) and nitrogen source addition changed the catalytic performance in physical and chemical properties, the migration of reactive species and the catalytic performance. When the addition amount of semicarbazide hydrochloride was three times that of LaCoO3, the composite catalysts had high Co3+/Co2+ (1.39) and Oads/Olat (15.18) and showed the best catalytic performance: the temperatures that are required for achieving methane conversion of 50% and 90% were 277 and 360 °C, which are more effective than noble metal oxides. Moreover, the in situ diffuse reflectance infrared fourier transform spectroscopy (DRIFTS) were applied to elucidate the efficient for CH4 removal and also can further explain the surface reaction mechanism of the composite catalyst during the methane catalytic combustion.
      Citation: Catalysts
      PubDate: 2018-03-21
      DOI: 10.3390/catal8040125
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 126: Vanadium Supported on Alumina and/or
           Zirconia Catalysts for the Selective Transformation of Ethane and Methanol
           

    • Authors: Souhila Benomar, Amada Massó, Benjamín Solsona, Rachid Issaadi, Jose López Nieto
      First page: 126
      Abstract: Vanadium supported on pure (Al2O3, ZrO2) or mixed zirconia-alumina (with Al/(Al + Zr) ratio of 0.75 or 0.25) catalysts have been prepared by wet impregnation, using homemade prepared supports. The catalysts have been characterized and tested in the oxidative dehydrogenation (ODH) of ethane and in the methanol aerobic transformation. The catalytic performance strongly depends on the nature of the metal oxide support. Thus, activity decreases in the order: VOx/ZrO2 > VOx/(Al,Zr-oxides) > VOx/Al2O3. On the other hand, at low and medium ethane conversions, the selectivity to ethylene presents an opposite trend: VOx/Al2O3 > VOx/(Al,Zr-oxides) > VOx/ZrO2. The different selectivity to ethylene at high conversion is due to the lower/higher initial ethylene formation and to the extent of the ethylene decomposition. Interestingly, VOx/(Al,Zr-oxides) with low Zr-loading present the lowest ethylene decomposition. The catalytic results obtained mainly depend on the nature of the supports whereas the role of the dispersion of vanadium species is unclear. In methanol oxidation, the catalysts tested present similar catalytic activity regardless of the support (Al2O3, ZrO2 or mixed Al2O3-ZrO2) but strong differences in the selectivity to the reaction products. Thus, dimethyl ether was mainly observed on alumina-supported vanadium oxide catalysts (which is associated to the presence of acidic sites on the surface of the catalyst, as determined by TPD-NH3). Formaldehyde was the main reaction product on catalysts supported on Zr-containing oxides (which can be related to a low presence of acid sites). In this article, the importance of the presence of acid sites in ethane ODH, which can be estimated using the methanol transformation reaction, is also discussed.
      Citation: Catalysts
      PubDate: 2018-03-22
      DOI: 10.3390/catal8040126
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 127: Liquid-Phase Hydrodeoxygenation of Guaiacol
           over Mo2C Supported on Commercial CNF. Effects of Operating Conditions on
           Conversion and Product Selectivity

    • Authors: Rui Moreira, Elba Ochoa, José Pinilla, António Portugal, Isabel Suelves
      First page: 127
      Abstract: In this work, a Mo2C catalyst that was supported on commercial carbon nanofibers (CNF) was synthetized and tested in the hydrodeoxygenation (HDO) of guaiacol. The effects of operating conditions (temperature and pressure) and reaction time (2 and 4 h) on the conversion of guaiacol and products selectivity were studied. The major reaction products were cresol and phenol, followed by xylenols and toluene. The use of more severe operating conditions during the HDO of guaiacol caused a diversification in the reaction pathways, and consequently in the selectivity to products. The formation of phenol may have occurred by demethylation of guaiacol, followed by dehydroxylation of catechol, together with other reaction pathways, including direct guaiacol demethoxylation, and demethylation of cresols. X-ray diffraction (XRD) analysis of spent catalysts did not reveal any significant changes as compared to the fresh catalyst.
      Citation: Catalysts
      PubDate: 2018-03-22
      DOI: 10.3390/catal8040127
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 128: Investigation of Catalytic Ozonation of
           Recalcitrant Organic Chemicals in Aqueous Solution over Various ZSM-5
           Zeolites

    • Authors: Yandan Wang, Wenfeng Ma, Brandon Yoza, Yingying Xu, Qing Li, Chunmao Chen, Qinghong Wang, Yu Gao, Shaohui Guo, Yali Zhan
      First page: 128
      Abstract: Catalytic ozonation processes (COPs) are an emerging technology for wastewater treatments. NaZSM-5 zeolites in three different SiO2/Al2O3 ratios (31, 45, and 120) and their metallic oxides loaded samples were compared for COP of nitrobenzene solution. NaZSM-5(120) showed high total organic carbon (TOC) removals (70.2–74.0%) by adsorption relative to NaZSM-5(45) (0.4–0.6%) at various initial pH conditions. NaZSM-5(31) was obtained by NaOH treatment of NaZSM-5(45) and displayed 20.9–23.8% of TOC removals by adsorption. In COPs, the different ZSM-5 zeolites exhibited various TOC removals and different reaction pathways. COP-NaZSM-5(120) showed high TOC removals compared to COP-NaZSM-5(45) and COP-NaZSM-5(31). The repeated uses of zeolites in COPs were performed to understand the reaction pathways and contribution of adsorption versus ozonation (i.e., catalytic oxidation and/or direct ozonation). Both adsorption and direct ozonation in COP-NaZSM-5(120) contributed TOC removal for the first use, whereas direct ozonation and •OH mediated oxidation dominated the process for eight repeated uses. Direct ozonation and •OH-mediated oxidation controlled the COP-NaZSM-5(45) process for the first and eight repeated uses. Adsorption and direct ozonation governed the COP-NaZSM-5(31) process for the first use, whereas the direct ozonation dominated it for eight repeated uses. In COPs, NaZSM-5(120) and NaZSM-5(45) showed the catalytic activity, whereas NaZSM-5(31) displayed negligible catalytic activity. The high catalytic activity of NaZSM-5(120) may be due to more Si-O bonds on zeolite surfaces. The results revealed that loading of Mg oxide on ZSM-5 zeolites can increase catalytic activity in COPs. These results show the application potential of ZSM-5 zeolites in ozonation of recalcitrant chemical wastewaters.
      Citation: Catalysts
      PubDate: 2018-03-22
      DOI: 10.3390/catal8040128
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 129: A New Mn–Salen Micellar Nanoreactor for
           Enantioselective Epoxidation of Alkenes in Water

    • Authors: Francesco Ballistreri, Rosa Toscano, Maria Amato, Andrea Pappalardo, Chiara Gangemi, Sofia Spidalieri, Roberta Puglisi, Giuseppe Trusso Sfrazzetto
      First page: 129
      Abstract: A new chiral Mn–salen catalyst, functionalized with a long aliphatic chain and a choline group, able to act as surfactant catalyst for green epoxidation in water, is here described. This catalyst was employed with a commercial surfactant (CTABr) leading to a nanoreactor for the enantioselective epoxidation of some selected alkenes in water, using NaClO as oxidant. This is the first example of a nanoreactor for enantioselective epoxidation of non-functionalized alkenes in water.
      Citation: Catalysts
      PubDate: 2018-03-25
      DOI: 10.3390/catal8040129
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 130: Investigation of Iron Vanadates for
           Simultaneous Carbon Soot Abatement and NH3-SCR

    • Authors: Marzia Casanova, Sara Colussi, Alessandro Trovarelli
      First page: 130
      Abstract: FeVO4 and Fe0.5Er0.5VO4 were prepared and loaded over standard Selective Catalytic Reduction (SCR) supports based on TiO2-WO3-SiO2 (TWS) and redox active supports like CeO2 and CeZrO2 with the aim of finding a suitable formulation for simultaneous soot abatement and NH3-SCR and to understand the level of interaction between the two reactions. A suitable bi-functional material was identified in the composition FeVO4/CeZrO2 where an SCR active component is added over a redox active support, to increase carbon oxidation properties. The influence of the presence of ammonia in soot oxidation and the effect of the presence of soot on SCR reaction have been addressed. It is found that the addition of NO and NO/NH3 mixtures decreases at different levels the oxidation temperature of carbon soot, while the presence of carbon adversely affects the NH3-SCR reaction by increasing the oxidation of NH3 to NO, thus lowering the NO removal efficiency.
      Citation: Catalysts
      PubDate: 2018-03-26
      DOI: 10.3390/catal8040130
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 131: Catalytic Hydroisomerization Upgrading of
           Vegetable Oil-Based Insulating Oil

    • Authors: Dieu-Phuong Phan, Eun Lee
      First page: 131
      Abstract: Due to its high biodegradability, high dielectric strength, and good thermal stability, vegetable oil is under consideration as an alternative transformer fluid for power system equipment, replacing traditional petroleum-based insulating oils. Its main drawbacks are its poor low-temperature properties arising from the crystallization of its long-chain normal paraffins, and its lower oxidative stability arising from its higher concentration of unsaturated fatty acids. Hydroisomerization/isomerization over bifunctional catalysts is considered to be an efficient pathway to upgrade vegetable oil-based insulating oil; this converts saturated/unsaturated long-chain fatty acids to branched isomers. The efficiency of this process depends crucially on the behavior of the catalyst system. This paper extensively reviews recent results on the influence that the metal phase and acidity, the effects of pore channels, and the balance between metal and acid sites have upon the activity and selectivity of catalytic hydroisomerization.
      Citation: Catalysts
      PubDate: 2018-03-28
      DOI: 10.3390/catal8040131
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 132: Heavy Oil Upgrading and Enhanced Recovery in
           a Steam Injection Process Assisted by NiO- and PdO-Functionalized SiO2
           Nanoparticulated Catalysts

    • Authors: Luisana Cardona, Daniela Arias-Madrid, Farid B. Cortés, Sergio H. Lopera, Camilo A. Franco
      First page: 132
      Abstract: This work aims to investigate the effect of active catalytic nanoparticles on the improvement of the efficiency in recovery of a continuous steam injection process. Catalytic nanoparticles were selected through batch-adsorption experiments and the subsequent evaluation of the temperature for catalytic steam gasification in a thermogravimetric analyzer. A nanoparticulated SiO2 support was functionalized with 1.0 wt % of NiO and PdO nanocrystals, respectively, to improve the catalytic activity of the nanoparticles. Oil recovery was evaluated using a sand pack in steam injection scenarios in the absence and presence of a 500 mg/L SiNi1Pd1 nanoparticles-based nanofluid. The displacement test was carried out by constructing the base curves with water injection followed by steam injection in the absence and presence of the prepared treatment. The oil recovery increased 56% after steam injection with nanoparticles in comparison with the steam injection in the absence of the catalysts. The API gravity increases from 7.2° to 12.1°. Changes in the asphaltenes fraction corroborated the catalytic effect of the nanoparticles by reducing the asphaltenes content and the 620 °C+ residue 40% and 47%, respectively. Also, rheological measurements showed that the viscosity decreased by up to 85% (one order of magnitude) after the nanofluid treatment during the steam injection process.
      Citation: Catalysts
      PubDate: 2018-03-29
      DOI: 10.3390/catal8040132
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 133: MgAl-Layered Double Hydroxide Solid Base
           Catalysts for Henry Reaction: A Green Protocol

    • Authors: Magda Abdellattif, Mohamed Mokhtar
      First page: 133
      Abstract: A series of MgAl-layered double hydroxide (MgAl-HT), the calcined form at 500 °C (MgAlOx), and the rehydrated one at 25 °C (MgAl-HT-RH) were synthesized. Physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Surface area of the as-synthesized, calcined, and rehydrated catalysts was determined by N2 physisorption at −196 °C. CO2 temperature-programmed desorption (CO2-TPD) was applied to determine the basic sites of catalysts. The catalytic test reaction was carried out using benzaldehyde and their derivatives with nitromethane and their derivatives. The Henry products (1–15) were obtained in a very good yield using MgAl-HT-RH catalyst either by conventional method at 90 °C in liquid phase or under microwave irradiation method. The mesoporous structure and basic nature of the rehydrated solid catalyst were responsible for its superior catalytic efficiency. The robust nature was determined by using the same catalyst five times, where the product % yield was almost unchanged significantly.
      Citation: Catalysts
      PubDate: 2018-03-29
      DOI: 10.3390/catal8040133
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 134: The Role of Fe2O3 Species in Depressing the
           Formation of N2O in the Selective Reduction of NO by NH3 over
           V2O5/TiO2-Based Catalysts

    • Authors: Moon Kim, Ki Yang
      First page: 134
      Abstract: Promotion of 2.73% Fe2O3 in an in-house-made V2O5-WO3/TiO2 (VWT) and a commercial V2O5-WO3/TiO2 (c-VWT) has been investigated as a cost effective approach to the suppression of N2O formation in the selective catalytic reduction of NO by NH3 (NH3-SCR). The promoted VWT and c-VWT catalysts all gave a significantly decreased N2O production at temperatures >400 °C compared to the unpromoted samples. However, such a promotion led to the loss in high temperature NO conversion, mainly due to the oxidation of NH3 to N-containing gases, particularly NO. Characterization of the unpromoted and promoted catalysts using X-ray diffraction (XRD), NH3 adsorption-desorption, and Raman spectroscopy techniques could explain the reason why the promotion showed much lower N2O formation levels at high temperatures. The addition of Fe2O3 to c-VWT resulted in redispersion of the V2O5 species, although this was not visible for 2.73% Fe2O3/VWT. The iron oxides exist as a highly-dispersed noncrystalline α-Fe2O3 in the promoted catalysts. These Raman spectra had a new Raman signal that could be tentatively assigned to Fe2O3-induced tetrahedrally coordinated polymeric vanadates and/or surface V-O-Fe species with significant electronic interactions between the both metal oxides. Calculations of the monolayer coverage of each metal oxide and the surface total coverage are reasonably consistent with Raman measurements. The proposed vanadia-based surface polymeric entities may play a key role for the substantial reduction of N2O formed at high temperatures by NH3 species adsorbed strongly on the promoted catalysts. This reaction is a main pathway to greatly suppress the extent of N2O formation in NH3-SCR reaction over the promoted catalysts.
      Citation: Catalysts
      PubDate: 2018-03-30
      DOI: 10.3390/catal8040134
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 135: Strategies of Coping with Deactivation of
           NH3-SCR Catalysts Due to Biomass Firing

    • Authors: Leonhard Schill, Rasmus Fehrmann
      First page: 135
      Abstract: Firing of biomass can lead to rapid deactivation of the vanadia-based NH3-SCR catalyst, which reduces NOx to harmless N2. The deactivation is mostly due to the high potassium content in biomasses, which results in submicron aerosols containing mostly KCl and K2SO4. The main mode of deactivation is neutralization of the catalyst’s acid sites. Four ways of dealing with high potassium contents were identified: (1) potassium removal by adsorption, (2) tail-end placement of the SCR unit, (3) coating SCR monoliths with a protective layer, and (4) intrinsically potassium tolerant catalysts. Addition of alumino silicates, often in the form of coal fly ash, is an industrially proven method of removing K aerosols from flue gases. Tail-end placement of the SCR unit was also reported to result in acceptable catalyst stability; however, flue-gas reheating after the flue gas desulfurization is, at present, unavoidable due to the lack of sulfur and water tolerant low temperature catalysts. Coating the shaped catalysts with thin layers of, e.g., MgO or sepiolite reduces the K uptake by hindering the diffusion of K+ into the catalyst pore system. Intrinsically potassium tolerant catalysts typically contain a high number of acid sites. This can be achieved by, e.g., using zeolites as support, replacing WO3 with heteropoly acids, and by preparing highly loaded, high surface area, very active V2O5/TiO2 catalyst using a special sol-gel method.
      Citation: Catalysts
      PubDate: 2018-03-30
      DOI: 10.3390/catal8040135
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 136: [(PhCH2O)2P(CH3)2CHNCH(CH3)2]2PdCl2/CuI as
           Cocatalyst for Coupling-Cyclization of 2-Iodophenol with Terminal Alkynes
           in Water

    • Authors: Panli Jiang, Mengping Guo, Leiqing Fu, Yongju Wen, Xiuli Shen, Lanjiang Zhou
      First page: 136
      Abstract: A new and efficient [(PhCH2O)2P(CH3)2CHNCH(CH3)2]2PdCl2/CuI-co-catalyzed coupling-cyclization reactions of 2-iodophenol with terminal alkynes is described. Different 2-substitued benzo[b]furan derivatives are obtained in good to excellent yields. This protocol employs a relatively low palladium(II) catalyst loading in water under air conditions.
      Citation: Catalysts
      PubDate: 2018-03-30
      DOI: 10.3390/catal8040136
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 137: The First Catalytic Direct C–H Arylation
           on C2 and C3 of Thiophene Ring Applied to Thieno-Pyridines, -Pyrimidines
           and -Pyrazines

    • Authors: Joana Campos, Maria-João Queiroz, Sabine Berteina-Raboin
      First page: 137
      Abstract: A practical one-pot procedure for the preparation of diverse thieno[3,2-d]pyrimidines is reported here for the first time. This two-step process via C–H activation in position C-2 of thiophene led to the development of an improved methodology for the synthesis of numerous compounds. This new methodology is an efficient alternative to the conventional methods currently applied. The C–H activation of the thiophene C-3 position was also achieved and can be selective. The optimized conditions can also be applied to thienopyridines and thienopyrazines.
      Citation: Catalysts
      PubDate: 2018-03-30
      DOI: 10.3390/catal8040137
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 138: Efficiently Enhancing Electrocatalytic
           Activity of α-MnO2 Nanorods/N-Doped Ketjenblack Carbon for Oxygen
           Reduction Reaction and Oxygen Evolution Reaction Using Facile Regulated
           Hydrothermal Treatment

    • Authors: Mei Wang, Kui Chen, Jun Liu, Quanguo He, Guangli Li, Fuzhi Li
      First page: 138
      Abstract: Scalable, low-cost and highly efficient catalysis of oxygen electrocatalytic reactions (ORR/OER) are required for the rapid development of clean and renewable energy conversion/storage technologies. Herein, two types of α-MnO2 nanorods were prepared under hydrothermal treatment at 150 °C for 0.5 h (MnO2-150-0.5) or 120 °C for 12 h (MnO2-120-12), then supported on N-doped ketjenblack carbon (N-KB) as bi-functional ORR/OER catalysts. Their electrocatalytic activities toward ORR and OER were investigated systematically. As a result, MnO2-150-0.5/N-KB displays superior ORR catalytic activity, with much more positive half-wave potential and much larger limiting current density (0.76 V and 6.0 mA cm−2), comparable to those of 20 wt. % Pt/C (0.82 V and 5.10 mA cm−2). MnO2-150-0.5/N-KB also shows high electron transfer number (3.86~3.97) and low yield of peroxides (1–7%) during ORR process in the whole potential range of 0–1.0 V (vs. RHE). Meanwhile, the MnO2-150-0.5/N-KB also exhibits better OER activity with low overpotential, comparable to IrO2/N-KB. The excellent electrocatalytic activity of MnO2-150-0.5/N-KB can be attributed to the synergistic effect, relatively smaller size, higher amount of Mn3+, and low charge transfer resistance. This work offers a new strategy for scalable preparation of more efficient and cost-effective α-MnO2 bi-functional oxygen catalysts.
      Citation: Catalysts
      PubDate: 2018-03-30
      DOI: 10.3390/catal8040138
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 139: Palladium-Catalyzed Regioselective
           Alkoxylation via C-H Bond Activation in the Dihydrobenzo[c]acridine Series
           

    • Authors: Benjamin Large, Flavien Bourdreux, Aurélie Damond, Anne Gaucher, Damien Prim
      First page: 139
      Abstract: 5,6-Dihydrobenzo[c]acridine belongs to the large aza-polycyclic compound family. Such molecules are not fully planar due to the presence of a partially hydrogenated ring. This paper describes the first Pd-catalyzed alkoxylation via C-H bond activation of variously substituted 5,6-dihydrobenzo[c]acridines. We determined suitable conditions to promote the selective formation of C-O bonds using 10% Pd(OAc)2, PhI(OAc)2 (2 eq.) and MeOH as the best combination of oxidant and solvent, respectively. Under these conditions, 5,6-dihydrobenzo[c]acridines bearing substituents at both rings A and D were successfully functionalized, giving access to polysubstitutited acridine motifs.
      Citation: Catalysts
      PubDate: 2018-03-31
      DOI: 10.3390/catal8040139
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 140: Recent Progress in Atomic-Level
           Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

    • Authors: Feng Gao, Charles Peden
      First page: 140
      Abstract: Cu/SSZ-13 Selective Catalytic Reduction (SCR) catalysts have been extensively studied for the past five-plus years. New and exciting fundamental and applied science has appeared in the literature quite frequently over this time. In this short review, a few topics specifically focused on a molecular-level understanding of this catalyst are summarized: (1) The nature of the active sites and, in particular, their transformations under varying reaction conditions that include dehydration, the presence of the various SCR reactants and hydrothermal aging; (2) Discussions of standard and fast SCR reaction mechanisms. Considerable progress has been made, especially in the last couple of years, on standard SCR mechanisms. In contrast, mechanisms for fast SCR are much less understood. Possible reaction paths are hypothesized for this latter case to stimulate further investigations; (3) Discussions of rational catalyst design based on new knowledge obtained regarding catalyst stability, overall catalytic performance and mechanistic catalytic chemistry.
      Citation: Catalysts
      PubDate: 2018-03-31
      DOI: 10.3390/catal8040140
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 141: Polystyrene-Supported Acyclic Diaminocarbene
           Palladium Complexes in Sonogashira Cross-Coupling: Stability vs. Catalytic
           Activity

    • Authors: Vladimir Mikhaylov, Viktor Sorokoumov, Denis Liakhov, Alexander Tskhovrebov, Irina Balova
      First page: 141
      Abstract: Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-PdII) are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-PdII, systems are found to have different catalytic activity and stability regarding Pd-leaching. PdII-diaminocarbenes possessing protons at both nitrogen atoms smoothly decompose into Pd0-containing species providing a catalytic “cocktail system” with high activity and ability to reuse within nine runs. Polymer-supported palladium (II) complex bearing NBn–Ccarbene–NH-moiety exhibits greater stability while noticeably lower activity under Sonogashira cross-coupling. Four molecular ADC-PdII complexes are also synthesized and investigated with the aim of confirming proposed base-promoted pathway of ADC-PdII conversion through carbodiimide into an active Pd0 forms.
      Citation: Catalysts
      PubDate: 2018-04-02
      DOI: 10.3390/catal8040141
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 142: Continuous Dimethyl Carbonate Synthesis from
           CO2 and Methanol Using Cu-Ni@VSiO as Catalyst Synthesized by a Novel
           Sulfuration Method

    • Authors: Meng Zhang, Kirill Alferov, Min Xiao, Dongmei Han, Shuanjin Wang, Yuezhong Meng
      First page: 142
      Abstract: Conversion of carbon dioxide into useful chemicals is a valuable task. One way to perform it is to transform CO2 into dimethyl carbonate (DMC) by a reaction with methanol. Catalyst exerts significant impact on this process. During this work, Cu-Ni@VSiO bimetallic catalysts were successfully synthesized by traditional solution and novel sulfuration methods. The catalytic materials were characterized by several analytical techniques and were tested in a continuous fixed-bed reactor under different reaction conditions to promote DMC synthesis from CO2 and methanol in the absence of dehydrating agents. The effects of reaction temperature, pressure, space velocity, metal loading, and bulk density on the catalytic performance were investigated in detail. It was found that the activity of Cu-Ni@VSiO catalyst with the support obtained by the novel sulfuration method is about three times higher when compared to that of the catalyst with the support that is synthesized by the traditional solution method. This result may stem from the difference in microstructure of the studied catalytic materials.
      Citation: Catalysts
      PubDate: 2018-04-03
      DOI: 10.3390/catal8040142
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 143: DRIFT Study on Promotion Effect of the
           Keggin Structure over V2O5-MoO3/TiO2 Catalysts for Low Temperature NH3-SCR
           Reaction

    • Authors: Rui Wu, Ningqiang Zhang, Lingcong Li, Hong He, Liyun Song, Wenge Qiu
      First page: 143
      Abstract: Heteropoly acids (HPAs) with the Keggin structure have been widely used in NOx removal. Two kinds of catalysts (those with and without the Keggin structure) are prepared for studying the effect of the Keggin structure on the NH3-SCR reaction. A series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analyses are conducted to investigate the surface-adsorbed species on the catalysts during the SCR reaction. The mechanism for enhancing low-temperature activity of the catalysts is proposed. Furthermore, the effect of NH4+ in the Keggin structure is also investigated. Results indicate that both the Langmuir–Hinshelwood (L-H) and Eley–Rideal (E-R) mechanisms occurred in the NH3-SCR reaction over the catalyst with the Keggin structure (Cat-A); in addition, when more acid sites are provided, NOx species activity is improved and more NH4+ ions participate in reaction over Cat-A, thus promoting SCR activity.
      Citation: Catalysts
      PubDate: 2018-04-03
      DOI: 10.3390/catal8040143
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 144: Controlled Synthesis of Heterostructured
           SnO2-CuO Composite Hollow Microspheres as Efficient Cu-Based Catalysts for
           the Rochow Reaction

    • Authors: Hezhi Liu, Yongjun Ji, Xiujing Zou, Jing Li, Yu Zhang, Xueguang Wang, Ziyi Zhong, Fabing Su
      First page: 144
      Abstract: In this work, we report the design and synthesis of a series of heterostructured SnO2-CuO hollow microspherical catalysts (H-SnO2(x)-CuO, x is the weight ratio of Sn/Cu) for the Rochow reaction. The microspherical catalysts with nanosheets and nanoparticles as building blocks were prepared by a facile one-pot hydrothermal method coupled with calcination. When tested for the Rochow reaction, the prepared H-SnO2(0.2)-CuO composite exhibited higher dimethyldichlorosilane selectivity (88.2%) and Si conversion (36.7%) than the solid CuO, hollow CuO and other H-SnO2(x)-CuO microspherical samples, because in the former there is a stronger synergistic interaction between CuO and SnO2.
      Citation: Catalysts
      PubDate: 2018-04-03
      DOI: 10.3390/catal8040144
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 145: Gaseous Nitric Acid Activated Graphite Felts
           as Hierarchical Metal-Free Catalyst for Selective Oxidation of H2S

    • Authors: Zhenxin Xu, Cuong Duong-Viet, Housseinou Ba, Bing Li, Tri Truong-Huu, Lam Nguyen-Dinh, Cuong Pham-Huu
      First page: 145
      Abstract: In this study, we reported on the influence of gaseous HNO3 treatment on the formation of defects decorated with oxygenated functional groups on commercial graphite felts (GFs). The gaseous acid treatment also leads to a remarkable increase of the specific as well as effective surface area through the formation of a highly porous graphite structure from dense graphite filamentous. The as-synthesized catalyst was further used as a metal-free catalyst in the selective oxidation of H2S in industrial waste effluents. According to the results, the defects decorated with oxygenated groups were highly active for performing selective oxidation of H2S into elemental sulfur. The desulfurization activity was relatively high and extremely stable as a function of time on stream which indicated the high efficiency of these oxidized un-doped GFs as metal-free catalysts for the selective oxidation process. The high catalytic performance was attributed to both the presence of structural defects on the filamentous carbon wall, which acting as a dissociative adsorption center for the oxygen, and the oxygenated functional groups, which could play the role of active sites for the selective oxidation process.
      Citation: Catalysts
      PubDate: 2018-04-04
      DOI: 10.3390/catal8040145
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 146: Porous Organic Polymers-Supported
           Metallocene Catalysts for Ethylene/1-Hexene Copolymerization

    • Authors: Xiong Wang, Xiaoyu Han, Feng Ren, Renwei Xu, Yongxiao Bai
      First page: 146
      Abstract: Porous organic polymers (POPs) have received much attention in adsorption, separation, and catalysis. In this paper, porous organic polymers with different pore structure were used as metallocene catalyst supports, and ethylene/1-hexene copolymerizations were conducted using the POPs-supported metallocene catalyst. The pore structure of the prepared POPs and the supported metallocene catalyst were characterized by nitrogen sorption porosimetry and non-local density functional theory simulation, and the molecular chain structure of the produced ethylene/1-hexene copolymers were investigated through gel permeation chromatography (GPC), IR analysis, differential scanning calorimetry (DSC), and temperature rising elution fractionation (TREF). The results show that the loading amount of active sites varied with different pore structures of the POP supports, and the active species scattered in different pore sizes had a moderate impact on the molecular chain growth and the molecular weight distribution. The IR, DSC, and TREF analysis revealedthat different branching degree, double bond content, and chemical composition distributions were detected from the molecular chain structure of the ethylene/α-olefin copolymers from different POPs and silica-supported metallocene catalysts, despite their similar IR, DSC, and TREF curves due to the same active species. Scanning electron microscopy (SEM) showed that porous ethylene/α-olefin copolymers with varied surface morphology were obtained from the POPs-supported metallocene catalysts with different pore structure.
      Citation: Catalysts
      PubDate: 2018-04-04
      DOI: 10.3390/catal8040146
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 147: Enhancing Light-Driven Production of
           Hydrogen Peroxide by Anchoring Au onto C3N4 Catalysts

    • Authors: Xiaoyu Chang, Junjiao Yang, Dandan Han, Bing Zhang, Xu Xiang, Jing He
      First page: 147
      Abstract: Light-driven production of hydrogen peroxide (H2O2) is a green and sustainable way to achieve solar-to-chemical energy conversion. During such a conversion, both the high activity and the stability of catalysts were critical. We prepared an Au-supported C3N4 catalyst—i.e., Au/C3N4-500(N2)—by strongly anchoring Au nanoparticles (~5 nm) onto a C3N4 matrix—which simultaneously enhanced the activity towards the photosynthesis of H2O2 and the stability when it was reused. The yield of H2O2 reached 1320 μmol L−1 on Au/C3N4-500(N2) after 4 h of light irradiation in an acidic solution (pH 3), which was higher than that (1067 μmol L−1) of the control sample Au/C3N4-500(Air) and 2.3 times higher than that of the pristine C3N4. Particularly, the catalyst Au/C3N4-500(N2) retained a much higher stability. The yield of H2O2 had a marginal decrease on the spent catalyst—i.e., 98% yield was kept. In comparison, only 70% yield was obtained from the spent control catalyst. The robust anchoring of Au onto C3N4 improved their interaction, which remarkably decreased the Au leaching when it was used and avoided the aggregation and aging of Au particles. Minimal Au leaching was detected on the spent catalyst. The kinetic analyses indicated that the highest formation rate of H2O2 was achieved on the Au/C3N4-500(N2) catalyst. The decomposition tests and kinetic behaviors of H2O2 were also carried out. These findings suggested that the formation rate of H2O2 could be a determining factor for efficient production of H2O2.
      Citation: Catalysts
      PubDate: 2018-04-04
      DOI: 10.3390/catal8040147
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 148: Insights in the Rhodium-Catalyzed Tandem
           Isomerization-Hydroformylation of 10-Undecenitrile: Evidence for a Fast
           Isomerization Regime

    • Authors: Lucas Le Goanvic, Jean-Luc Couturier, Jean-Luc Dubois, Jean-François Carpentier
      First page: 148
      Abstract: The tandem isomerization-hydroformylation of 10-undecenitrile (1) into the corresponding linear aldehyde (2) with a Rh-biphephos system was studied and the formation of internal olefin isomers (1-int-x) was monitored over time. The existence of an “isomerization phenomenon” was evidenced, where fast isomerization of 1 into up to 70% of 1-int-x followed by fast back-isomerization of 1-int-x into 1 and, in turn, into 2 occurs. This fast dynamic isomerization regime is favored at high syngas pressure (40 bar) and low biphephos-to-Rh ratio (5–10), and it is best observed at relatively high catalyst loadings ([1]0/[Rh] ≤ 3000). The latter regime is indeed evanescent, and gives place to a second stage in which isomerization of internal olefins (and eventual conversion into 2) proceeds much more slowly. The results are tentatively rationalized by the formation of an unstable species that promotes dynamic isomerization and which slowly vanishes or collapses into a Rh-biphephos species which is the one responsible for hydroformylation.
      Citation: Catalysts
      PubDate: 2018-04-05
      DOI: 10.3390/catal8040148
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 149: Immobilization/Stabilization of Ficin
           Extract on Glutaraldehyde-Activated Agarose Beads. Variables That Control
           the Final Stability and Activity in Protein Hydrolyses

    • Authors: El-Hocine Siar, Sara Arana-Peña, Oveimar Barbosa, Mohammed Zidoune, Roberto Fernandez-Lafuente
      First page: 149
      Abstract: Ficin extract has been immobilized on different 4% aminated-agarose beads. Using just ion exchange, immobilization yield was poor and expressed activity did not surpass 10% of the offered enzyme, with no significant effects on enzyme stability. The treatment with glutaraldehyde of this ionically exchanged enzyme produced an almost full enzyme inactivation. Using aminated supports activated with glutaraldehyde, immobilization was optimal at pH 7 (at pH 5 immobilization yield was 80%, while at pH 9, the immobilized enzyme became inactivated). At pH 7, full immobilization was accomplished maintaining 40% activity versus a small synthetic substrate and 30% versus casein. Ficin stabilization upon immobilization could be observed but it depended on the inactivation pH and the substrate employed, suggesting the complexity of the mechanism of inactivation of the immobilized enzyme. The maximum enzyme loading on the support was determined to be around 70 mg/g. The loading has no significant effect on the enzyme stability or enzyme activity using the synthetic substrate but it had a significant effect on the activity using casein; the biocatalysts activity greatly decreased using more than 30 mg/g, suggesting that the near presence of other immobilized enzyme molecules may generate some steric hindrances for the casein hydrolysis.
      Citation: Catalysts
      PubDate: 2018-04-06
      DOI: 10.3390/catal8040149
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 150: Stereoselective Enzymatic Reduction of
           1,4-Diaryl-1,4-Diones to the Corresponding Diols Employing Alcohol
           Dehydrogenases

    • Authors: Ángela Mourelle-Insua, Gonzalo de Gonzalo, Iván Lavandera, Vicente Gotor-Fernández
      First page: 150
      Abstract: Due to the steric hindrance of the starting prochiral ketones, the preparation of chiral 1,4-diaryl-1,4-diols through the asymmetric hydrogen transfer reaction has been mainly restricted to the use of metal-based catalysts, oxazaborolidines, or organocatalysts. Herein, we demonstrated the versatility of oxidoreductases, finding overexpressed alcohol dehydrogenase from Ralstonia sp. (E. coli/RasADH) as the most active and stereoselective biocatalyst. Thus, the preparation of a set of 1,4-diaryl-1,4-diols bearing different pattern substitutions in the aromatic ring was achieved with complete diastereo- and enantioselectivity under mild reaction conditions.
      Citation: Catalysts
      PubDate: 2018-04-06
      DOI: 10.3390/catal8040150
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 151: Synthesis and Characterization of
           CNT/TiO2/ZnO Composites with High Photocatalytic Performance

    • Authors: Yanzhen Huang, Rongkai Li, Dongping Chen, Xinling Hu, Pengxin Chen, Zhibin Chen, Dongxu Li
      First page: 151
      Abstract: Novel carbon nanotubes (CNTs)/titanium dioxide (TiO2)/zinc oxide (ZnO) composites have been successfully synthesized via a two-step solution method using titanyl sulfate as the titanium precursor. Its structural performances were researched by various characterization methods, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composites was tested by degrading rhodamine B (RhB) under UV-vis illumination and found to strongly rely on the content of ZnO. The experimental results showed that the CNT/TiO2/ZnO-90 wt % expressed more outstanding photocatalytic performance compared to the corresponding binary composites and the CNT/TiO2/ZnO-85 wt %, CNT/TiO2/ZnO-95 wt % materials. The improved photocatalytic activity was attributed to synergistic effect of CNT, TiO2 and ZnO, in which ZnO can absorb photons to produce electrons and holes, whereas TiO2 and CNT can reduce the electron-hole recombination.
      Citation: Catalysts
      PubDate: 2018-04-09
      DOI: 10.3390/catal8040151
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 152: Catalytic Efficiency of Basidiomycete
           Laccases: Redox Potential versus Substrate-Binding Pocket Structure

    • Authors: Olga Glazunova, Nikita Trushkin, Konstantin Moiseenko, Ivan Filimonov, Tatyana Fedorova
      First page: 152
      Abstract: Laccases are copper-containing oxidases that catalyze a one-electron abstraction from various phenolic and non-phenolic compounds with concomitant reduction of molecular oxygen to water. It is well-known that laccases from various sources have different substrate specificities, but it is not completely clear what exactly provides these differences. The purpose of this work was to study the features of the substrate specificity of four laccases from basidiomycete fungi Trametes hirsuta, Coriolopsis caperata, Antrodiella faginea, and Steccherinum murashkinskyi, which have different redox potentials of the T1 copper center and a different structure of substrate-binding pockets. Enzyme activity toward 20 monophenolic substances and 4 phenolic dyes was measured spectrophotometrically. The kinetic parameters of oxidation of four lignans and lignan-like substrates were determined by monitoring of the oxygen consumption. For the oxidation of the high redox potential (>700 mV) monophenolic substrates and almost all large substrates, such as phenolic dyes and lignans, the redox potential difference between the enzyme and the substrate (ΔE) played the defining role. For the low redox potential monophenolic substrates, ΔE did not directly influence the laccase activity. Also, in the special cases, the structure of the large substrates, such as dyes and lignans, as well as some structural features of the laccases (flexibility of the substrate-binding pocket loops and some amino acid residues in the key positions) affected the resulting catalytic efficiency.
      Citation: Catalysts
      PubDate: 2018-04-09
      DOI: 10.3390/catal8040152
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 153: The Deoxygenation Pathways of Palmitic Acid
           into Hydrocarbons on Silica-Supported Ni12P5 and Ni2P Catalysts

    • Authors: Wenjun Zhou, Hui Xin, Huiru Yang, Xiangze Du, Rui Yang, Dan Li, Changwei Hu
      First page: 153
      Abstract: Pure Ni12P5/SiO2 and pure Ni2P/SiO2 catalysts were obtained by adjusting the Ni and P molar ratios, while Ni/SiO2 catalyst was prepared as a reference against which the deoxygenation pathways of palmitic acid were investigated. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission election microscopy (TEM), infrared spectroscopy of pyridine adsorption (Py-IR), H2-adsorption and temperature-programmed desorption of hydrogen (H2-TPD). The crystallographic planes of Ni(111), Ni12P5(400), Ni2P(111) were found mainly exposed on the above three catalysts, respectively. It was found that the deoxygenation pathway of palmitic acid mainly proceeded via direct decarboxylation (DCO2) to form C15 on Ni/SiO2. In contrast, on the Ni12P5/SiO2 catalyst, there were two main competitive pathways producing C15 and C16, one of which mainly proceeded via the decarbonylation (DCO) to form C15 accompanying water formation, and the other pathway produced C16 via the dehydration of hexadecanol intermediate, and the yield of C15 was approximately twofold that of C16. Over the Ni2P/SiO2 catalyst, two main deoxygenation pathways formed C15, one of which was mainly the DCO pathway and the other was dehydration accompanying the hexadecanal intermediate and then direct decarbonylation without water formation. The turn over frequency (TOF) followed the order: Ni12P5/SiO2 > Ni/SiO2 > Ni2P/SiO2.
      Citation: Catalysts
      PubDate: 2018-04-11
      DOI: 10.3390/catal8040153
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 154: Preparation of Stable Cross-Linked Enzyme
           Aggregates (CLEAs) of a Ureibacillus thermosphaericus Esterase for
           Application in Malathion Removal from Wastewater

    • Authors: Yuliya Samoylova, Ksenia Sorokina, Alexander Piligaev, Valentin Parmon
      First page: 154
      Abstract: In this study, the active and stable cross-linked enzyme aggregates (CLEAs) of the thermostable esterase estUT1 of the bacterium Ureibacillus thermosphaericus were prepared for application in malathion removal from municipal wastewater. Co-expression of esterase with an E. coli chaperone team (KJE, ClpB, and ELS) increased the activity of the soluble enzyme fraction up to 200.7 ± 15.5 U mg−1. Response surface methodology (RSM) was used to optimize the preparation of the CLEA-estUT1 biocatalyst to maximize its activity and minimize enzyme loss. CLEA-estUT1 with the highest activity of 29.4 ± 0.5 U mg−1 (90.6 ± 2.7% of the recovered activity) was prepared with 65.1% (w/v) ammonium sulfate, 120.6 mM glutaraldehyde, and 0.2 mM bovine serum albumin at 5.1 h of cross-linking. The biocatalyst has maximal activity at 80 °С and pH 8.0. Analysis of the properties of CLEA-estUT1 and free enzyme at 50–80 °C and pH 5.0–10.0 showed higher stability of the biocatalyst. CLEA-estUT1 showed marked tolerance against a number of chemicals and high operational stability and activity in the reaction of malathion hydrolysis in wastewater (up to 99.5 ± 1.4%). After 25 cycles of malathion hydrolysis at 37 °С, it retained 55.2 ± 1.1% of the initial activity. The high stability and reusability of CLEA-estUT1 make it applicable for the degradation of insecticides.
      Citation: Catalysts
      PubDate: 2018-04-11
      DOI: 10.3390/catal8040154
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 155: Gas-Phase Phosphorous Poisoning of a
           Pt/Ba/Al2O3 NOx Storage Catalyst

    • Authors: Rasmus Jonsson, Oana Mihai, Jungwon Woo, Magnus Skoglundh, Eva Olsson, Malin Berggrund, Louise Olsson
      First page: 155
      Abstract: The effect of phosphorous exposure on the NOx storage capacity of a Pt/Ba/Al2O3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H2O and O2. The NOx storage capacity was measured before and after the phosphorus exposure and a significant loss of the NOx storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N2-physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P4O10. However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO3−). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sample.
      Citation: Catalysts
      PubDate: 2018-04-11
      DOI: 10.3390/catal8040155
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 156: The Effects of Coordinated Molecules of Two
           Gly-Schiff Base Copper Complexes on Their Oxygen Reduction Reaction
           Performance

    • Authors: Zhe Ma, Ya Chu, Chonggang Fu, Hongmei Du, Xianqiang Huang, Jinsheng Zhao
      First page: 156
      Abstract: In this study, two simple Schiff base copper complexes [Cu(H2O)2(HL)]·2H2O (Complex 1) (H3L = 2-OH-4-(OH)-C6H2CH=NCH2CO2H) and [Cu(py)2(HL)] (Complex 2) (Py = pyridine) were initially achieved and authenticated by single-crystal X-ray structure analyses (SXRD), powder X-ray diffraction analyses (PXRD), FT-IR spectroscopy, and elemental analyses. The SXRD reveals that the Cu2+ center in Complex 1 exhibited a distorted square pyramidal geometry, which is constructed based on phenolate oxygen, water molecules, carboxylate oxygen, and imine nitrogen from a deprotonated H3L ligand in an NO4 fashion. The Cu2+ atom in Complex 2 had distorted square pyramidal geometry, and was coordinated with two pyridine molecules and one Gly-Schiff base ligand, exhibiting an N3O2 binding set. Additionally, the free water molecules in Complex 1 linked independent copper complexes by intermolecular hydrogen bond to form a 2D framework. However, the one-dimensional chain supramolecular structure of Complex 2 was formed by the intermolecular O–H…O hydrogen bonds. The oxygen reduction performance of the two complexes was analyzed by cyclic voltammetry (CV) and the rotating disk electrode (RDE) method. Both complexes could catalyze the conversion of oxygen to water through a predominant four-electron pathway, and the Cu–NxOy moieties might be the functional moieties for the catalytic activity. The catalytic pathways and underlying mechanisms are also discussed in detail, from which the structure–activity relationship of the complexes was obtained.
      Citation: Catalysts
      PubDate: 2018-04-12
      DOI: 10.3390/catal8040156
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 157: Catalytic Role of H2O Molecules in Oxidation
           of CH3OH in Water

    • Authors: Satoshi Inaba
      First page: 157
      Abstract: We have examined the catalytic role of H2O molecules in the oxidation of CH3OH in water by quantum chemical simulations. A CH3OH is decomposed into molecules, a formaldehyde and an H2, in water, while it is converted into radicals in a gas phase reaction at a high temperature. H2O molecules located near a CH3OH form a first hydration shell and act as catalyst for the oxidation of CH3OH in water. The oxidation process of a CH3OH in water begins when a proton is delivered to a neighbor H2O molecule from a hydroxyl of a CH3OH. The H2O molecule transfers an extra proton to a second H2O molecule, a proton of which is combined with a proton detached from the methyl of the CH3OH, forming an H2. The energy barrier to decompose a CH3OH is significantly reduced by the catalyst of H2O molecules in water. A cluster of H2O molecules arise in water as an enclosed chain of hydrogen bonds between H2O molecules. A proton is transferred with less energy between H2O molecules within a cluster of H2O molecules. A cluster of five H2O molecules further reduces the energy barrier. The calculated oxidation rate of CH3OH with the transition state theory agrees well with that determined by experiments.
      Citation: Catalysts
      PubDate: 2018-04-12
      DOI: 10.3390/catal8040157
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 158: Binary Nitrogen Precursor-Derived Porous
           Fe-N-S/C Catalyst for Efficient Oxygen Reduction Reaction in a Zn-Air
           Battery

    • Authors: Xiao Liu, Chi Chen, Qingqing Cheng, Liangliang Zou, Zhiqing Zou, Hui Yang
      First page: 158
      Abstract: It is still a challenge to synthesize non-precious-metal catalysts with high activity and stability for the oxygen reduction reaction (ORR) to replace the state-of-the art Pt/C catalyst. Herein, a Fe, N, S co-doped porous carbon (Fe-NS/PC) is developed by using g-C3N4 and 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ) as binary nitrogen precursors. The interaction of binary nitrogen precursors not only leads to the formation of more micropores, but also increases the doping amount of both iron and nitrogen dispersed in the carbon matrix. After a second heat-treatment, the best Fe/NS/C-g-C3N4/TPTZ-1000 catalyst exhibits excellent ORR performance with an onset potential of 1.0 V vs. reversible hydrogen electrode (RHE) and a half-wave potential of 0.868 V (RHE) in alkaline medium. The long-term durability is even superior to the commercial Pt/C catalyst. In the meantime, an assembled Zn-air battery with Fe/NS/C-g-C3N4/TPTZ-1000 as the cathode shows a maximal power density of 225 mW·cm−2 and excellent durability, demonstrating the great potential of practical applications in energy conversion devices.
      Citation: Catalysts
      PubDate: 2018-04-13
      DOI: 10.3390/catal8040158
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 159: Immobilization of Enterobacter aerogenes by
           a Trimetric Autotransporter Adhesin, AtaA, and Its Application to
           Biohydrogen Production

    • Authors: Hajime Nakatani, Nan Ding, Yuki Ohara, Katsutoshi Hori
      First page: 159
      Abstract: Biological hydrogen production by microbial cells has been extensively researched as an energy-efficient and environmentally-friendly process. In this study, we propose a fast, easy method for immobilizing Enterobacter aerogenes by expressing ataA, which encodes the adhesive protein of Acinetobacter sp. Tol 5. AtaA protein on the E. aerogenes cells carrying the ataA gene was demonstrated by immunoblotting and flow cytometry. The AtaA-producing cells exhibited stronger adherence and auto-agglutination characteristics than wild-type cells, and were successfully immobilized (at approximately 2.5 mg/cm3) on polyurethane foam. Hydrogen production from the cell-immobilized polyurethane foams was monitored in repetitive batch reactions and flow reactor studies. The total hydrogen production in triple-repetitive batch reactions reached 0.6 mol/mol glucose, and the hydrogen production rate in the flow reactor was 42 mL·h−1·L−1. The AtaA production achieved simple and immediate immobilization of E. aerogenes on the foam, enabling repetitive and continuous hydrogen production. This report newly demonstrates the production of AtaA on the cell surfaces of bacterial genera other than Acinetobacter, and can simplify and accelerate the immobilization of whole-cell catalysts.
      Citation: Catalysts
      PubDate: 2018-04-16
      DOI: 10.3390/catal8040159
      Issue No: Vol. 8, No. 4 (2018)
       
  • Catalysts, Vol. 8, Pages 94: The Role of Yeast-Surface-Display Techniques
           in Creating Biocatalysts for Consolidated BioProcessing

    • Authors: Ian Dominic Flormata Tabañag, I-Ming Chu, Yu-Hong Wei, Shen-Long Tsai
      First page: 94
      Abstract: Climate change is directly linked to the rapid depletion of our non-renewable fossil resources and has posed concerns on sustainability. Thus, imploring the need for us to shift from our fossil based economy to a sustainable bioeconomy centered on biomass utilization. The efficient bioconversion of lignocellulosic biomass (an ideal feedstock) to a platform chemical, such as bioethanol, can be achieved via the consolidated bioprocessing technology, termed yeast surface engineering, to produce yeasts that are capable of this feat. This approach has various strategies that involve the display of enzymes on the surface of yeast to degrade the lignocellulosic biomass, then metabolically convert the degraded sugars directly into ethanol, thus elevating the status of yeast from an immobilization material to a whole-cell biocatalyst. The performance of the engineered strains developed from these strategies are presented, visualized, and compared in this article to highlight the role of this technology in moving forward to our quest against climate change. Furthermore, the qualitative assessment synthesized in this work can serve as a reference material on addressing the areas of improvement of the field and on assessing the capability and potential of the different yeast surface display strategies on the efficient degradation, utilization, and ethanol production from lignocellulosic biomass.
      Citation: Catalysts
      PubDate: 2018-02-25
      DOI: 10.3390/catal8030094
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 95: Tungsten-Based Mesoporous Silicates W-MMM-E
           as Heterogeneous Catalysts for Liquid-Phase Oxidations with Aqueous H2O2

    • Authors: Nataliya Maksimchuk, Irina Ivanchikova, Olga Zalomaeva, Yurii Chesalov, Alexandr Shmakov, Vladimir Zaikovskii, Oxana Kholdeeva
      First page: 95
      Abstract: Mesoporous tungsten-silicates, W-MMM-E, have been prepared following evaporation-induced self-assembly methodology and characterized by elemental analysis, XRD, N2 adsorption, STEM-HAADF (high angle annular dark field in scanning-TEM mode), DRS UV-vis, and Raman techniques. DRS UV-vis showed the presence of two types of tungsten oxo-species in W-MMM-E samples: isolated tetrahedrally and oligomeric octahedrally coordinated ones, with the ratio depending on the content of tungsten in the catalyst. Materials with lower W loading have a higher contribution from isolated species, regardless of the preparation method. W-MMM-E catalyzes selectively oxidize of a range of alkenes and organic sulfides, including bulky terpene or thianthrene molecules, using green aqueous H2O2. The selectivity of corresponding epoxides reached 85–99% in up to 80% alkene conversions, while sulfoxides formed with 84–90% selectivity in almost complete sulfide conversions and a 90–100% H2O2 utilization efficiency. The true heterogeneity of catalysis over W-MMM-E was proved by hot filtration tests. Leaching of inactive W species depended on the reaction conditions and initial W loading in the catalyst. After optimization of the catalyst system, it did not exceed 20 ppm and 3 ppm for epoxidation and sulfoxidation reactions, respectively. Elaborated catalysts could be easily retrieved by filtration and reused several times with maintenance of the catalytic behavior.
      Citation: Catalysts
      PubDate: 2018-02-27
      DOI: 10.3390/catal8030095
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 96: X-Shaped ZIF-8 for Immobilization Rhizomucor
           miehei Lipase via Encapsulation and Its Application toward Biodiesel
           Production

    • Authors: Miaad Adnan, Kai Li, Li Xu, Yunjun Yan
      First page: 96
      Abstract: This study presents a one-step encapsulation method for synthesizing X-shaped zeolitic imidazolate frameworks (ZIF-8) and immobilizing Rhizomucor miehei lipase (RML). We proved that the morphological structure of ZIF-8 had changed after immobilization with enhanced characterization using a field-emission scanning electron microscope, an energy-dispersive spectrometer, a transmission electron microscope, a Fourier transform infrared spectrometer, and powder X-ray diffraction. The surface area and pore size of the carrier were investigated before and after immobilization using Brunauer–Emmett–Teller and Barrett–Joyner–Halenda methods, respectively. RML@ZIF-8 exhibited high recovery activity of up to 2632%, representing a 26-fold increase in its free lipase. Encapsulated RML was used for biodiesel production from soybean oil in an isooctane system with a conversion yield of 95.6% under optimum conditions. The resulting reusability of the immobilized enzyme indicated no substantial decline in the conversion yield, which remained at 84.7% of the initial activity after 10 cycles. The stability and high performance of the immobilized enzyme are attributed to the harmony between RML and ZIF-8 based on the easy synthesis of ZIF-8 and the short time required to immobilize RML.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030096
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 97: A SET Approach to the Interplay of Catalysts
           and Reactants

    • Authors: Ragnar Larsson
      First page: 97
      Abstract: Research within the area of selective energy transfer (SET) on how resonance develops between a specific vibration within a catalyst system and a corresponding vibration within a reacting system that resonates with it is discussed here. The catalyst system is assumed to donate one or more vibrational quanta to the reacting system. The term ‘specific vibration’ refers to vibration of a type involving bending or stretching that, when transferred resonantly to the reacting system, serves to drive the reactant molecules involved to assume the basic structure of the molecules of the catalyst system. Regardless of whether the catalyst is a pure metal surface or a complex polymolecular system (an enzyme), its role is seen to be that of transferring energy to corresponding vibrations of the reactant system. Examples are here presented of vibrators of various types that can act as catalysts.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030097
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 98: Kinetics of CO Oxidation over Unloaded and
           Pd-Loaded α-Fe2O3 Spherical Submicron Powder Catalysts: Photoacoustic
           Investigations at Low Pressure

    • Authors: Joong-Seok Roh, Ji-Yeong Kim, Joong-Gill Choi, Sung-Han Lee
      First page: 98
      Abstract: In this study, α-Fe2O3 spherical particles with an average diameter of approximately 200 nm were synthesized by a solvothermal method for use as both a catalyst and medium for a Pd catalyst. The kinetics of CO oxidation over powders of α-Fe2O3 spherical particles and 14 wt % Pd/α-Fe2O3 spherical particles were measured in a static reactor by using a CO2 laser-based photoacoustic technique. The total pressure was fixed at 40 Torr for the CO/O2/N2 mixture for temperatures in the range of 225–350 °C. The variation in the CO2 photoacoustic signal with the CO2 concentration during CO oxidation was recorded as a function of time, and the CO2 photoacoustic data at the early reaction stage was used to estimate the rates of CO2 formation. Based on plots of ln(rate) vs. 1/T, apparent activation energies were calculated as 13.4 kcal/mol for the α-Fe2O3 submicron powder and 13.2 kcal/mol for the 14 wt % Pd/α-Fe2O3 submicron powder. Reaction orders with respect to CO and O2 were determined from the rates measured at various partial pressures of CO and O2 at 350 °C. The zero-order of the reaction with respect to Po2 was observed for CO oxidation over α-Fe2O3 submicron powder, while 0.48 order to Po2 was observed for CO oxidation over Pd/α-Fe2O3 submicron powder. The partial orders with respect to PCO were determined as 0.58 and 0.54 for the α-Fe2O3, and the Pd/α-Fe2O3 submicron powders, respectively. The kinetic results obtained from both catalysts were compared with those for the α-Fe2O3 fine powder catalysts and were used to understand the reaction mechanism.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030098
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 99: Methyl Chloride Synthesis over Metal
           Chlorides-Modified Mesoporous Alumina Catalyst

    • Authors: Yuwen Ji, Feilong Zhang, Feng Yu, Jianshu Zhang, Jinli Zhang
      First page: 99
      Abstract: Mesoporous alumina has been successfully prepared using sucrose as templates. Mesoporous alumina-based catalysts, neat and impregnated with metal chlorides, were tested for gas phase methyl chloride synthesis from methanol and HCl. The catalysts were characterized with Transmission electron microscope (TEM), N2-physisorption, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) to identify the relationship between the catalyst characteristics and their activity and selectivity. Experimental studies revealed that the alumina acidity decreases with increasing calcination temperature, and the catalytic activity is strongly related to the acidity. The catalytic activity of mesoporous alumina (named as Al2O3-500 °C) is higher than that of the commercial alumina under the same experimental conditions. The metal chlorides-modified alumina has more Lewis acid sites than the neat alumina. Impregnation by alcohol is more effective for increasing the amount of Lewis acid sites than impregnation by water. The total Lewis acid concentration of the modified alumina decreases in the following order: ZnCl2/Al2O3-E > ZnCl2/Al2O3-W > FeCl3/Al2O3-E > FeCl3/Al2O3-W, Where E and W respectively indicate that the catalyst impregnation solution is ethanol and water, which agrees well with the catalytic performance order. The effect of ethanol as a solvent in the impregnation could be due to the inhibition of the hydrolysis of metal chloride. The catalyst delivered a stable performance during a 100 h test that was significantly higher than that of commercial alumina.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030099
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 100: Enhanced Low Temperature NO Reduction
           Performance via MnOx-Fe2O3/Vermiculite Monolithic Honeycomb Catalysts

    • Authors: Ke Zhang, Feng Yu, Mingyuan Zhu, Jianming Dan, Xugen Wang, Jinli Zhang, Bin Dai
      First page: 100
      Abstract: Selective catalytic reduction of NOx by ammonia (NH3-SCR) was the most efficient and economic technology for De-NOx applications. Therefore, a series of MnOx/vermiculite (VMT) and MnOx-Fe2O3/VMT catalysts were prepared by an impregnation method for the selective catalytic reduction (SCR) of nitrogen oxides (NOx). The MnOx-Fe2O3/VMT catalysts provided an excellent NO conversion of 96.5% at 200 °C with a gas hourly space velocity (GHSV) of 30,000 h−1 and an NO concentration of 500 ppm. X-ray photoelectron spectroscopy results indicated that the Mn and Fe oxides of the MnOx-Fe2O3/VMT catalyst were mainly composed of MnO2 and Fe2O3. However, the MnO2 and Fe2O3 components were well dispersed because no discernible MnO2 and Fe2O3 phases were observed in X-ray powder diffraction spectra. Corresponding MnOx-Fe2O3/VMT monolithic honeycomb catalysts (MHCs) were prepared by an extrusion method, and the MHCs achieved excellent SCR activity at low temperature, with an NO conversion greater than 98.6% at 150 °C and a GHSV of 4000 h−1. In particular, the MnOx-Fe2O3/VMT MHCs provided a good SCR activity at room temperature (20 °C), with an NO conversion of 62.2% (GHSV = 1000 h−1). In addition, the NO reduction performance of the MnOx-Fe2O3/VMT MHCs also demonstrated an excellent SO2 resistance.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030100
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 101: Cost-Effective and Facile Preparation of
           Fe2O3 Nanoparticles Decorated N-Doped Mesoporous Carbon Materials:
           Transforming Mulberry Leaf into a Highly Active Electrocatalyst for Oxygen
           Reduction Reactions

    • Authors: Tingting Zhang, Lihao Guan, Changqing Li, Junfeng Zhao, Manchao Wang, Lin Peng, Jiahui Wang, Yuqing Lin
      First page: 101
      Abstract: Herein, a promising method to prepare efficient N-doped porous carbon-supported Fe2O3 nanoparticles (Fe2O3/N-PCs) ORR electrocatalysts is presented. The porous carbon was derived from a biomass i.e., mulberry leaf through a cost-effective approach. The existence of diverse compounds containing carbon, oxygen, nitrogen and sulfur in mulberry leaf benefit the formation and uniform dispersion of Fe2O3 nanoparticles (NPs) in the porous carbon. In evaluating the effects of the carbon support on the Fe2O3 NPs towards the ORR, we found that the sample of Fe2O3/N-PCs-850 (Fe2O3/N-PCs obtained at 850 °C) with high surface area of 313.8 m2·g−1 exhibits remarkably superior ORR activity than that of materials acquired under other temperatures. To be specific, the onset potential and reduction peak potential of Fe2O3/N-PCs-850 towards ORR are 0.936 V and 0.776 V (vs. RHE), respectively. The calculated number of electron transfer n for the ORR is 3.9, demonstrating a near four-electron-transfer process. Furthermore, it demonstrates excellent longtime stability and resistance to methanol deactivation compared with Pt/C catalyst. This study provides a novel design of highly active ORR electrocatalysts from low-cost abundant plant products.
      Citation: Catalysts
      PubDate: 2018-02-28
      DOI: 10.3390/catal8030101
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 102: A New Approach to Deep Desulfurization of
           Light Cycle Oil over Ni2P Catalysts: Combined Selective Oxidation and
           Hydrotreating

    • Authors: Gwang-Nam Yun, Kye-Syng Cho, Yong-Su Kim, Yong-Kul Lee
      First page: 102
      Abstract: Amphiphilic phosphotungstic acid (A-PTA) and Ni2P/SBA-15 catalysts were prepared to apply for selective oxidation of refractory sulfur compounds in light cycle oils and hydrotreating of the oxidized S compounds, respectively. Physical properties of the catalyst samples were analyzed by BET, CO uptake chemisorption, and TEM. Structural properties for the supported Ni2P catalysts were analyzed by X-ray diffraction (XRD) and extended X-ray absorption fine structure (XAFS) spectroscopy. The selective oxidation of S compounds in the LCO feed was conducted in a batch reactor at H2O2/S ratio of 10, atmospheric pressure and 353 K and then the products were fed to a continuous flow fixed-bed reactor for hydrotreating at 623 K, 3.0 MPa, and LHSV’s of 0.5–2.0 h−1. A-PTA catalyst showed a high oxidation conversion of 95% for a real LCO feed. The following hydrotreating led to a hydrodesulfurization (HDS) conversion of 99.6% and a hydrodenitrogenation (HDN) conversion of 94.7% over Ni2P/SBA-15, which were much higher than those of direct hydrotreating results which gave an HDS conversion of 63.5% and an HDN conversion of 17.5% based on the same LHSV of 2.0 h−1. It was revealed that the reduction in refractory nitrogen compounds after oxidative treatment contributed to the increase of the following HDS activity.
      Citation: Catalysts
      PubDate: 2018-03-01
      DOI: 10.3390/catal8030102
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 103: Designing Multifunctionality into Single
           Phase and Multiphase Metal-Oxide-Selective Propylene Ammoxidation
           Catalysts

    • Authors: James Brazdil
      First page: 103
      Abstract: Multifunctionality is the hallmark of most modern commercial heterogeneous catalyst systems in use today, including those used for the selective ammoxidation of propylene to acrylonitrile. It is the quintessential principle underlying commercial catalyst design efforts since petrochemical process development is invariably driven by the need to reduce manufacturing costs. This is in large part achieved through new and improved catalysts that increase selectivity and productivity. In addition, the future feedstocks for chemical processes will be invariably more refractory than those currently in use (e.g., replacing alkenes with alkanes or using CO2), thus requiring a disparate combination of chemical functions in order to effect multiple chemical transformations with the fewest separate process steps. This review summarizes the key chemical phenomena behind achieving the successful integration of multiple functions into a mixed-metal-oxide-selective ammoxidation catalyst. An experiential and functional catalyst design model is presented that consists of one or both of the following components: (1) a mixed-metal-oxide–solid solution where the individual metal components serve separate and necessary functions in the reaction mechanism through their atomic level interaction in the context of a single crystallographic structure; (2) the required elemental components and their catalytic function existing in separate phases, where these phases are able to interact for the purposes of electron and lattice oxygen transfer through the formation of a structurally coherent interface (i.e., epitaxy) between the separate crystal structures. Examples are provided from the literature and explained in the context of this catalyst design model. The extension of the model concepts to the design of heterogeneous catalysts in general is also discussed.
      Citation: Catalysts
      PubDate: 2018-03-02
      DOI: 10.3390/catal8030103
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 104: Selective Hydrogenation of Benzene to
           Cyclohexene over Ru-Zn Catalysts: Mechanism Investigation on NaOH as a
           Reaction Additive

    • Authors: Haijie Sun, Zhihao Chen, Chenggang Li, Lingxia Chen, Zhikun Peng, Zhongyi Liu, Shouchang Liu
      First page: 104
      Abstract: Ru-Zn catalysts were synthesized via a precipitation method, and the mechanism of NaOH modifying Ru-Zn catalysts on the selective hydrogenation of benzene to cyclohexene was thoroughly investigated. Fresh as well as used catalysts were characterized via X-ray diffraction (XRD), X-ray Fluorescence (XRF), transmission electron microscope (TEM), scanning electron microscope (SEM), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT), respectively. Before catalytic experiments, metallic Ru and rodlike ZnO were detected from fresh Ru-Zn catalysts. Notably, with the increasing concentration of NaOH added into the reaction medium (e.g., from 0 to 0.6 mol·L−1), the dispersion of ZnO on the Ru surface significantly improved, resulting in the enhancement Ruδ+ species of electron deficiency. The catalytic activity towards benzene conversion was therefore retarded and the selectivity towards cyclohexene was improved. When the added NaOH concentration reached 0.6 mol·L−1, the atomic ratio of Zn/Ru decreased from 0.27 (when no NaOH was added) to 0.16, benzene conversion of 45.3%, and cyclohexene selectivity of 89.3% was achieved using a batch reactor after 25 min of reaction time. However, with continually increasing the NaOH concentration, i.e., to 1.2 mol·L−1, parts of ZnO could react with the over-added NaOH, leading to the unfavorable consumption of uniformly dispersed ZnO. This causes the increasing of catalytic activity towards benzene conversion, as well as the decreasing of the selectivity towards cyclohexene. Moreover, no loss of catalytic activity and selectivity towards cyclohexene formation from selective hydrogenation of benzene was observed after 10 times of catalytic experiments without any regeneration.
      Citation: Catalysts
      PubDate: 2018-03-02
      DOI: 10.3390/catal8030104
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 105: Synthesis of Tetrahydropyran from
           Tetrahydrofurfuryl Alcohol over Cu–Zno/Al2O3 under a Gaseous-Phase
           Condition

    • Authors: Fengyuan Zhang, Bin Zhang, Xincheng Wang, Long Huang, Dekun Ji, Songsong Du, Lei Ma, Shijing Lin
      First page: 105
      Abstract: Tetrahydropyran (THP) represents an O-containing hetero-cyclic compound that can be used as a promising solvent or monomer for polymer synthesis. In this work, Cu–ZnO/Al2O3 catalysts have been prepared by a facile precipitation–extrusion method and used for the synthesis of THP through gaseous-phase hydrogenolysis of tetrahydrofurfuryl alcohol (THFA). The effect of the molar ratio of Cu/Zn/Al, reaction temperature, and hydrogen pressure was investigated. An 89.4% selectivity of THP was achieved at 270 °C and 1.0 MPa H2. Meanwhile, the optimum molar ratio of Cu/Zn/Al was determined to be 4:1:10. The Cu–ZnO/Al2O3 catalyst exhibited high catalytic activity and stability for 205 h on-stream. A possible reaction mechanism involving several consecutive reactions was proposed: THFA was firstly rearranged to 2-hydroxytetrahydropyran (2-HTHP), followed by the dehydration of 2-HTHP to 3,4-2H-dihydropyran (DHP) over acid sites; finally, the DHP was hydrogenated to THP. The synergy of acid sites and metal sites of Cu–ZnO/Al2O3 played an important role during the production of THP.
      Citation: Catalysts
      PubDate: 2018-03-06
      DOI: 10.3390/catal8030105
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 106: Effects of Mesopore Internal Surfaces on the
           Structure of Immobilized Pd-Bisphosphine Complexes Analyzed by
           Variable-Temperature XAFS and Their Catalytic Performances

    • Authors: Ken Motokura, Takuma Fukuda, Yohei Uemura, Daiju Matsumura, Marika Ikeda, Masayuki Nambo, Wang-Jae Chun
      First page: 106
      Abstract: In this study, mesoporous and nonporous silica-supported Pd complexes were synthesized and characterized. Variable-temperature XAFS measurements and a curve-fitting analysis showed a slightly larger contribution of σ2static when the Pd complexes were on a nonporous support in comparison to a mesoporous support. In contrast, the catalytic performance of the attached Pd complex in the Suzuki-Miyaura cross-coupling reaction was not affected by such small differences in the static disorder of the Pd complex.
      Citation: Catalysts
      PubDate: 2018-03-09
      DOI: 10.3390/catal8030106
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 107: Synthesis of Rectorite/Fe3O4/ZnO Composites
           and Their Application for the Removal of Methylene Blue Dye

    • Authors: Huanhuan Wang, Peijiang Zhou, Rui Guo, Yifei Wang, Hongju Zhan, Yunfei Yuan
      First page: 107
      Abstract: A novel series of rectorite-based magnetic zinc oxide (ZnO) photocatalysts (REC/Fe3O4/ZnO) was synthesized and characterized in the present work. The fabricated REC/Fe3O4/ZnO composite possessed a high specific surface area and high capacity of adsorption and photocatalysis toward methylene blue (MB) dye. The adsorption isotherm of the dye on the composite fitted well to the Langmuir model, with a maximum adsorption of 35.1 mg/g. The high adsorption capacity increased the interactions between the dye and the REC/Fe3O4/ZnO, which enabled efficient decomposition of the dye under simulated solar radiation using REC/Fe3O4/ZnO as the photocatalyst. The degradation kinetics of MB dye followed the Langmuir–Hinshelwood model. More importantly, the degradation of MB dye and the mass loss of REC/Fe3O4/ZnO after three repetitive experiments were quite small. This suggests that the magnetic composite has great potential as an effective, stable, and easily recovered catalyst. Four major intermediates were detected during the degradation of MB dye and the degradation pathway was proposed.
      Citation: Catalysts
      PubDate: 2018-03-09
      DOI: 10.3390/catal8030107
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 108: High Performance of Manganese Porphyrin
           Sensitized p-Type CuFe2O4 Photocathode for Solar Water Splitting to
           Produce Hydrogen in a Tandem Photoelectrochemical Cell

    • Authors: Xia Li, Aijuan Liu, Dongmei Chu, Chunyong Zhang, Yukou Du, Jie Huang, Ping Yang
      First page: 108
      Abstract: A novel composite composed of (5, 10, 15, 20-tetraphenyl) porphinato manganese sensitized p-type CuFe2O4 was developed for constructing the photocathode of a tandem photoelectrochemical (PEC) cell. The prepared material was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). Light-driven water splitting to produce hydrogen can be achieved through the PEC cell, and the results show that H2 and O2 can be collected separately at low applied bias. This work demonstrates that manganese porphyrin sensitized CuFe2O4 is an effective hybrid material for building the photocathode of a PEC cell for solar water splitting to produce H2.
      Citation: Catalysts
      PubDate: 2018-03-09
      DOI: 10.3390/catal8030108
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 109: Use of Lactobacillus rhamnosus (ATCC 53103)
           as Whole-Cell Biocatalyst for the Regio- and Stereoselective Hydration of
           Oleic, Linoleic, and Linolenic Acid

    • Authors: Stefano Serra, Davide De Simeis
      First page: 109
      Abstract: Natural hydroxy fatty acids are relevant starting materials for the production of a number of industrial fine chemicals, such as different high-value flavour ingredients. Only a few of the latter hydroxy acid derivatives are available on a large scale. Therefore, their preparation by microbial hydration of unsaturated fatty acids, affordable from vegetable oils, is a new biotechnological challenge. In this study, we describe the use of the probiotic bacterium Lactobacillus rhamnosus (ATCC 53103) as whole-cell biocatalyst for the hydration of the most common unsaturated octadecanoic acids, namely oleic acid, linoleic acid, and linolenic acid. We discovered that the addition of the latter fatty acids to an anaerobic colture of the latter strain, during the early stage of its exponential growth, allows the production of the corresponding mono-hydroxy derivatives. In these experimental conditions, the hydration reaction proceeds with high regio- and stereoselectivity. Only 10-hydroxy derivatives were formed and the resulting (R)-10-hydroxystearic acid, (S)-(12Z)-10-hydroxy-octadecenoic acid, and (S)-(12Z,15Z)-10-hydroxy-octadecadienoic acid were obtained in very high enantiomeric purity (ee > 95%). Although overall conversions usually do not exceed 50% yield, our biotransformation protocol is stereoselective, scalable, and holds preparative significance.
      Citation: Catalysts
      PubDate: 2018-03-09
      DOI: 10.3390/catal8030109
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 110: Recent Scientific Progress on Developing
           Supported Ni Catalysts for Dry (CO2) Reforming of Methane

    • Authors: Hyun Seo
      First page: 110
      Abstract: Two major green house gases (CO2 and CH4) can be converted into useful synthetic gas (H2 and CO) during dry reforming of methane (DRM) reaction, and a lot of scientific efforts has been made to develop efficient catalysts for dry reforming of methane (DRM). Noble metal-based catalysts can effectively assist DRM reaction, however they are not economically viable. Alternatively, non-noble based catalysts have been studied so far, and supported Ni catalysts have been considered as a promising candidate for DRM catalyst. Main drawback of Ni catalysts is its catalytic instability under operating conditions of DRM (>700 °C). Recently, it has been demonstrated that the appropriate choice of metal-oxide supports can address this issue since the chemical and physical of metal-oxide supports can prevent coke formation and stabilize the small Ni nanoparticles under harsh conditions of DRM operation. This mini-review covers the recent scientific findings on the development of supported Ni catalysts for DRM reaction, including the synthetic methods of supported Ni nanoparticles with high sintering resistance.
      Citation: Catalysts
      PubDate: 2018-03-11
      DOI: 10.3390/catal8030110
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 111: A Comparative Study of Mn/Co Binary Metal
           Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of
           Benzene

    • Authors: Marco Tomatis, Honghui Xu, Chaohui Wei, Matthew Bishop, Jun He, Chengjun Wang, Ming Zhao, Hang Xiao, Huan Yu, Sailesh Behera, Bencan Tang
      First page: 111
      Abstract: Two commercial diatomaceous earths were used as supports for the preparation of Mn/Co binary metal catalysts at different metal loads (5 to 10 wt % Mn and 5 to 15 wt % Co) by incipient wetness deposition. The activity of the prepared catalysts towards the complete oxidation of benzene to CO2 and water was investigated between 100 and 400 °C. Raw supports and synthesized catalysts were characterized by XRD, N2 physisorption, SEM-EDS, H2-TPR, and TPD. The purification treatment of food-grade diatomite significantly affected the crystallinity of this support while reducing its specific surface area (SSA). A loss of SSA, associated with the increase in the metal load, was observed on samples prepared on natural diatomite, while the opposite trend occurred with food-grade diatomite-supported catalysts. Metal nanoparticles of around 50 nm diameter were observed on the catalysts’ surface by SEM analysis. EDS analysis confirmed the uniform deposition of the active phases on the support’s surface. A larger H2 consumption was found by TPR analysis of natural diatomite-based samples in comparison to those prepared at the same metal load on food-grade diatomite. During the catalytic oxidation experiment, over 90% conversion of benzene were achieved at a reaction temperature of 225 °C by all of the prepared samples. In addition, the formation of coke during the oxidation tests was demonstrated by TGA analysis and the soluble fraction of the produced coke was characterized by GC-MS.
      Citation: Catalysts
      PubDate: 2018-03-12
      DOI: 10.3390/catal8030111
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 112: Fabrication of a Z-Scheme g-C3N4/Fe-TiO2
           Photocatalytic Composite with Enhanced Photocatalytic Activity under
           Visible Light Irradiation

    • Authors: Zedong Zhu, Muthu Murugananthan, Jie Gu, Yanrong Zhang
      First page: 112
      Abstract: In the present study, a nanocomposite material g-C3N4/Fe-TiO2 has been prepared successfully by a simple one-step hydrothermal process and its structural properties were thoroughly studied by various characterization techniques, such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) spectrum, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectrometry (UV-vis DRS). The performance of the fabricated composite material towards the removal of phenol from aqueous phase was systematically evaluated by a photocatalytic approach and found to be highly dependent on the content of Fe3+. The optimum concentration of Fe3+ doping that showed a dramatic enhancement in the photocatalytic activity of the composite under visible light irradiation was observed to be 0.05% by weight. The separation mechanism of photogenerated electrons and holes of the g-C3N4/Fe-TiO2 photocatalysts was established by a photoluminescence technique in which the reactive species generated during the photocatalytic treatment process was quantified. The enhanced photocatalytic performance observed for g-C3N4-Fe/TiO2 was ascribed to a cumulative impact of both g-C3N4 and Fe that extended its spectrum-absorptive nature into the visible region. The heterojunction formation in the fabricated photocatalysts not only facilitated the separation of the photogenerated charge carriers but also retained its strong oxidation and reduction ability.
      Citation: Catalysts
      PubDate: 2018-03-13
      DOI: 10.3390/catal8030112
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 113: Waste into Fuel—Catalyst and Process
           Development for MSW Valorisation

    • Authors: Izabela Pieta, William Epling, Alicja Kazmierczuk, Pawel Lisowski, Robert Nowakowski, Ewa Serwicka
      First page: 113
      Abstract: The present review paper highlights recent progress in the processing of potential municipal solid waste (MSW) derived fuels. These wastes come from the sieved fraction (∅ < 40 mm), which, after sorting, can differ in biodegradable fraction content ranging from 5–60%. The fuels obtained from these wastes possess volumetric energy densities in the range of 15.6–26.8 MJL−1 and are composed mainly of methanol, ethanol, butanol, and carboxylic acids. Although these waste streams are a cheap and abundant source (and decrease the fraction going to landfills), syngas produced from MSW contains various impurities such as organic compounds, nitrogen oxides, sulfur, and chlorine components. These limit its use for advanced electricity generation especially for heat and power generation units based on high temperature fuel cells such as solid oxide fuel cells (SOFC) or molten carbonate fuel cells (MCFC). In this paper, we review recent research developments in the continuous MSW processing for syngas production specifically concentrating on dry reforming and the catalytic sorbent effects on effluent and process efficiency. A particular emphasis is placed on waste derived biofuels, which are currently a primary candidate for a sustainable biofuel of tomorrow, catalysts/catalytic sorbents with decreased amounts of noble metals, their long term activity, and poison resistance, and novel nano-sorbent materials. In this review, future prospects for waste to fuels or chemicals and the needed research to further process technologies are discussed.
      Citation: Catalysts
      PubDate: 2018-03-14
      DOI: 10.3390/catal8030113
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 114: Highly Active and Selective Supported
           Rhenium Catalysts for Aerobic Oxidation of n-Hexane and n-Heptane

    • Authors: Gopal Mishra, Elisabete Alegria, Armando Pombeiro, Luísa Martins
      First page: 114
      Abstract: A series of derivative C-scorpionate rhenium complexes, i.e., [ReCl2{NNC(O)C6H5}(Hpz)(PPh3)2] (A) (where Hpz is pyrazole), [ReCl2{NNC(O)C6H5}(Hpz)2(PPh3)] (B), [ReClF{NNC(O)C6H5}(Hpz)2(PPh3)] (C), and their precursor [ReOCl3(PPh3)2] (D), immobilized on 3-aminopropyl-functionalized silica have been prepared and used for neat O2 oxidation of n-hexane and n-heptane mainly to the corresponding alcohols and, in lower amounts, ketones. The supported catalyst C, with fluoro- and diazenido-ligands, exhibits the highest activity for both alkanes (overall turnover numbers (TONs) up to 3.8 × 103 and 2.5 × 103, for n-hexane and n-heptane, respectively) and can be reused in consecutive catalytic cycles. Improved conversion was observed after addition of hetero-carboxylate co-catalysts. A free-radical-based mechanism is proposed to explain the product formation.
      Citation: Catalysts
      PubDate: 2018-03-15
      DOI: 10.3390/catal8030114
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 115: Solvent-Free Mizoroki-Heck Reaction Applied
           to the Synthesis of Abscisic Acid and Some Derivatives

    • Authors: Geoffrey Dumonteil, Marie-Aude Hiebel, Sabine Berteina-Raboin
      First page: 115
      Abstract: Abscisic acid (ABA) is a natural product, which is a well-known phytohormone. However, this molecule has recently exhibited interesting biological activities, emphasizing the need for a simple and direct access to new analogues based on the ABA framework. Our strategy relies on a pallado-catalyzed Mizoroki-Heck cross-coupling as key reaction performed in solvent and ligand free conditions. After a careful optimization, we succeeded in accessing various (E/Z)-dienes and (E/E/Z)-trienes in moderate to good yields without isomerization and applied the same approach to the synthesis of ABA in an environmentally sound manner.
      Citation: Catalysts
      PubDate: 2018-03-15
      DOI: 10.3390/catal8030115
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 116: Catalytic Oxidation of Chlorobenzene over
           Ruthenium-Ceria Bimetallic Catalysts

    • Authors: Meng Ye, Li Chen, Xiaolong Liu, Wenqing Xu, Tingyu Zhu, Guanyi Chen
      First page: 116
      Abstract: A series of Ru-based mono and bimetallic materials were prepared and evaluated in the catalytic oxidation of chlorobenzene. Among the different Ru-based catalysts, 1Ru/TiO2(P25) was the most active catalyst and contributed the lowest complete oxidation temperature, suggesting that commercial P25 TiO2 was the best support for Ru catalysts. After ceria oxides were introduced into the Ru catalytic system, the catalytic activity of 1Ru-5Ce/TiO2(Rutile) dramatically improved and that of P25 supported catalysts was decreased. Comparing the chlorobenzene consumption rates for 1Ru/TiO2 and 1Ru-5Ce/TiO2 at 280 °C, it could be concluded that monometallic Ru catalytic system was appropriate for P25 support, and the Ru-Ce bimetallic catalytic system was suitable for the rutile TiO2 support. At 280 °C, for 1Ru-5Ce/TiO2(Rutile) and 1Ru-5Ce/TiO2(P25), the chlorobenzene conversion was stabilized at approximately 91% and 86%, respectively. According to the physicochemical properties of the catalysts as characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and Hydrogen temperature programmed reduction (H2-TPR), it can be concluded that (a) electrophilic Oads species play an important role in VOCs oxidation; (b) abundant RuO2 nanoparticles on the surface of 1Ru-5Ce/TiO2(Rutile) result in higher catalytic activity and stability; and (c) dispersion is not the major factor for the catalytic activity, rather the unique structure greatly facilitated the catalytic activity and stability.
      Citation: Catalysts
      PubDate: 2018-03-16
      DOI: 10.3390/catal8030116
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 117: Functional Analysis of Methylomonas sp. DH-1
           Genome as a Promising Biocatalyst for Bioconversion of Methane to Valuable
           Chemicals

    • Authors: Anh Nguyen, In Hwang, Ok Lee, Dong Hur, Young Jeon, Susila Hadiyati, Min-Sik Kim, Sung Yoon, Haeyoung Jeong, Eun Lee
      First page: 117
      Abstract: Methylomonas sp. DH-1, newly isolated from the activated sludge of a brewery plant, has been used as a promising biocatalytic platform for the conversion of methane to value-added chemicals. Methylomonas sp. DH-1 can efficiently convert methane and propane into methanol and acetone with a specific productivity of 4.31 and 0.14 mmol/g cell/h, the highest values ever reported, respectively. Here, we present the complete genome sequence of Methylomonas sp. DH-1 which consists of a 4.86 Mb chromosome and a 278 kb plasmid. The existence of a set of genes related to one-carbon metabolism and various secondary metabolite biosynthetic pathways including carotenoid pathways were identified. Interestingly, Methylomonas sp. DH-1 possesses not only the genes of the ribulose monophosphate cycle for type I methanotrophs but also the genes of the serine cycle for type II. Methylomonas sp. DH-1 accumulated 80 mM succinate from methane under aerobic conditions, because DH-1 has 2-oxoglutarate dehydrogenase activity and the ability to operate the full TCA cycle. Availability of the complete genome sequence of Methylomonas sp. DH-1 enables further investigations on the metabolic engineering of this strain for the production of value-added chemicals from methane.
      Citation: Catalysts
      PubDate: 2018-03-16
      DOI: 10.3390/catal8030117
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 118: Photocatalytic Performance and Degradation
           Mechanism of Aspirin by TiO2 through Response Surface Methodology

    • Authors: Lezhuo Li, Qiuling Ma, Sanfan Wang, Sanxiang Song, Bo Li, Ruonan Guo, Xiuwen Cheng, Qingfeng Cheng
      First page: 118
      Abstract: In the present work, the photocatalytic performance of P25TiO2 was investigated by means of the degradation of aspirin, while the reaction system was systematically optimized by central composite design (CCD) based on the response surface methodology (RSM). In addition, three variables of initial pH value, initial aspirin concentration and P25 concentration were selected to assess the dependence of degradation efficiencies of aspirin. Meanwhile, a predicted model of degradation efficiency was estimated and checked using analysis of variance (ANOVA). The results indicated that the PC removal of aspirin by P25 was significantly influenced by all these variables in descending order as follows: P25 concentration > initial aspirin concentration > initial pH value. Moreover, the parameters were optimized by the CCD method. Under the conditions of an initial pH value of 5, initial aspirin concentration of 10 mg/L and P25 concentration of 50 mg/L, the degradation efficiency of aspirin was 98.9%with 60 min of Xenon lamp irradiation. Besides, based on the liquid chromatography-mass spectrometry measurements, two main PC degradation pathways of aspirin by TiO2 were deduced and the tentative degradation mechanism was also proposed.
      Citation: Catalysts
      PubDate: 2018-03-16
      DOI: 10.3390/catal8030118
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 119: Catalytic Conversion of Model Tars over
           Carbon-Supported Ni and Fe

    • Authors: Luis Arteaga-Pérez, Aaron Delgado, Mauricio Flores, Patricia Olivera, Kimberley Matschuk, Christian Hamel, Tim Schulzke, Romel Jiménez
      First page: 119
      Abstract: Tar removal from gasification gases is a determinant step to guarantee the operational feasibility of gasification-to-chemicals/energy systems. This study aimed to develop novel carbon-supported catalysts for the elimination of tarry aromatics (toluene, naphthalene and benzene) from gasification gases. Effects of reaction temperature (700 < T < 900 °C) and catalyst nature (Fe0 and Ni0) on the activity were assessed by considering thermo-catalytic conversion and steam reforming, under a simulated gasification gas. The catalysts (Ni and Fe) and support (AC) were characterized by X-ray diffraction (XRD), N2 physisorption, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and compositional analyses. Both catalysts and support, presented a mesoporous-like texture with a considerable high surface area (690 < SBET < 743 m2/g). Furthermore, dispersion of the metal nanoparticles (active phase) was uniform as confirmed by TEM images. Results from activity tests suggest that Ni/AC has higher effectivity for converting tars than Fe/AC, as confirmed by the low apparent activation energies (34 < Eapp < 98 kJ/mol) for naphthalene and benzene conversion between 700 and 900 °C. The conversion was 100% above 850 °C; nevertheless; below 750 °C, a sharp reduction in benzene conversion was observed, which was attributed to reversible carbon deposition.
      Citation: Catalysts
      PubDate: 2018-03-17
      DOI: 10.3390/catal8030119
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 120: Recent Progress in Asymmetric Catalysis and
           Chromatographic Separation by Chiral Metal–Organic Frameworks

    • Authors: Suchandra Bhattacharjee, Muhammad Khan, Xiaofang Li, Qi-Long Zhu, Xin-Tao Wu
      First page: 120
      Abstract: Metal–organic frameworks (MOFs), as a new class of porous solid materials, have emerged and their study has established itself very quickly into a productive research field. This short review recaps the recent advancement of chiral MOFs. Here, we present simple, well-ordered instances to classify the mode of synthesis of chiral MOFs, and later demonstrate the potential applications of chiral MOFs in heterogeneous asymmetric catalysis and enantioselective separation. The asymmetric catalysis sections are subdivided based on the types of reactions that have been successfully carried out recently by chiral MOFs. In the part on enantioselective separation, we present the potentiality of chiral MOFs as a stationary phase for high-performance liquid chromatography (HPLC) and high-resolution gas chromatography (GC) by considering fruitful examples from current research work. We anticipate that this review will provide interest to researchers to design new homochiral MOFs with even greater complexity and effort to execute their potential functions in several fields, such as asymmetric catalysis, enantiomer separation, and chiral recognition.
      Citation: Catalysts
      PubDate: 2018-03-19
      DOI: 10.3390/catal8030120
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 121: Single-Atom Mn Active Site in a
           Triol-Stabilized β-Anderson Manganohexamolybdate for Enhanced Catalytic
           Activity towards Adipic Acid Production

    • Authors: Jianhui Luo, Yichao Huang, Bin Ding, Pingmei Wang, Xiangfei Geng, Jiangwei Zhang, Yongge Wei
      First page: 121
      Abstract: Adipic acid is an important raw chemical for the commercial production of polyamides and polyesters. The traditional industrial adipic acid production utilizes nitric acid to oxidize KA oil (mixtures of cyclohexanone and cyclohexanol), leading to the emission of N2O and thus causing ozone depletion, global warming, and acid rain. Herein, we reported an organically functionalized β-isomer of Anderson polyoxometalates (POMs) nanocluster with single-atom Mn, β-{[H3NC(CH2O)3]2MnMo6O18}− (1), as a highly active catalyst to selectively catalyze the oxidation of cyclohexanone, cyclohexanol, or KA oil with atom economy use of 30% H2O2 for the eco-friendly synthesis of adipic acid. The catalyst has been characterized by single crystal and powder XRD, XPS, ESI-MS, FT-IR, and NMR. A cyclohexanone (cyclohexanol) conversion of >99.9% with an adipic acid selectivity of ~97.1% (~85.3%) could be achieved over catalyst 1 with high turnover frequency of 2427.5 h−1 (2132.5 h−1). It has been demonstrated that the existence of Mn3+ atom active site in catalyst 1 and the special butterfly-shaped topology of POMs both play vital roles in the enhancement of catalytic activity.
      Citation: Catalysts
      PubDate: 2018-03-19
      DOI: 10.3390/catal8030121
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 122: Platinum Group Metal Phosphides as Efficient
           Catalysts in Hydroprocessing and Syngas-Related Catalysis

    • Authors: Luis Alvarado Rupflin, Chiara Boscagli, Stephan Schunk
      First page: 122
      Abstract: Platinum group metal phosphides are reviewed as catalytic materials for hydroprocessing and syngas-related catalysis. Starting from synthetic procedures leading to highly disperse nano-particular compounds, their properties in the applications are discussed and compared with relevant benchmarks, if available. Regarding their mode of action, two confronting mechanistic scenarios are presented: (i) a cooperative scenario in which catalytic sites of different functionalities are active in hydroprocessing and (ii) single site catalysis, which appears to be the relevant mode of action in syngas-related catalysis and which occurs over “frustrated” active sites.
      Citation: Catalysts
      PubDate: 2018-03-20
      DOI: 10.3390/catal8030122
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 123: The PT/S-Box of Modular Cellulase AcCel12B
           Plays a Key Role in the Hydrolysis of Insoluble Cellulose

    • Authors: Yuwei Li, Junling Wang, Limei Wang, Hao Tong, Mingwei Bu, Gui Gao, Weiwei Han, Zuoming Zhang
      First page: 123
      Abstract: Cellulases play key roles in the degradation of lignocellulosic materials. The function and mechanism of the catalytic domain (CD) and carbohydrate-binding module (CBM) of cellulases were earlier revealed by analysis and characterization of protein structure. However, understanding of the catalytic mechanism of the entire enzyme, and the analysis of the catalytic model, were inadequate. Therefore, the linker chain between CD and CBM has been extensively studied to bridge this gap. Cellulase AcCel12B and three mutants with different linker lengths (with no or 1–3 PT/S-box units) were successfully constructed and purified. Results showed that the activity of cellulases on Avicel and regenerated amorphous cellulose (RAC) increased with the number of PT/S-box units. Furthermore, the desorption of AcCel12B and its mutants from RAC and Avicel were significantly different. The energy of desorption of wild-type and mutant AcCel12B from cellulose decreased with the number of PT/S-box units. Thus, AcCel12B containing more PT/S-box units was more easily desorbed and had more opportunity to hydrolyze cellulose than other samples. The number of PT/S-box units in endocellulase affected the desorption of the enzyme, which is possibly responsible for the differences in the activity of wild-type and mutant AcCel12B on Avicel and RAC.
      Citation: Catalysts
      PubDate: 2018-03-20
      DOI: 10.3390/catal8030123
      Issue No: Vol. 8, No. 3 (2018)
       
  • Catalysts, Vol. 8, Pages 60: Selective Hydrogenation of Cinnamaldehyde
           Catalyzed by ZnO-Fe2O3 Mixed Oxide Supported Gold Nanocatalysts

    • Authors: Wei Wang, Yan Xie, Shaohua Zhang, Xing Liu, Masatake Haruta, Jiahui Huang
      First page: 60
      Abstract: ZnO-Fe2O3 mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition–precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe2O3 mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of 1.0 MPa. The molar ratio of Fe to Zn was found to greatly affect the selective hydrogenation catalytic activity of ZnO-Fe2O3 mixed oxide supported gold nanocatalysts. Among these supported gold nanocatalysts in this work, Au/Zn0.7Fe0.3Ox (Au loading of 1.74 wt %) exhibited the highest conversion of cinnamaldehyde and high selectivity to cinnamal alcohol. The excellent catalytic activity of Au/Zn0.7Fe0.3Ox was tightly associated with a large surface area, small gold nanoparticles, and good H2 dissociation ability at low temperature.
      Citation: Catalysts
      PubDate: 2018-02-03
      DOI: 10.3390/catal8020060
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 61: 1,3-Diene Polymerization Mediated by
           Homoleptic Tetramethylaluminates of the Rare-Earth Metals

    • Authors: Christoph Hollfelder, Lars Jende, Dominic Diether, Theresa Zelger, Rita Stauder, Cäcilia Maichle-Mössmer, Reiner Anwander
      First page: 61
      Abstract: During the past two decades homoleptic tetramethylaluminates of the trivalent rare-earth metals, Ln(AlMe4)3, have emerged as useful components for efficient catalyst design in the field of 1,3-diene polymerization. Previous work had focused on isoprene polymerization applying Ln(AlMe4)3 precatalysts with Ln = La, Ce, Pr, Nd, Gd and Y, in the presence of Et2AlCl as an activator. Polymerizations employing Ln(AlMe4)3 with Ln = La, Y and Nd along with borate/borane co-catalysts [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] and [B(C6F5)3] were mainly investigated for reasons of comparison with ancillary ligand-supported systems (cf. half-sandwich complexes). The present study investigates into a total of eleven rare-earth elements, namely Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Er and Lu. A full overview on the polymerization behavior of Ln(AlMe4)3 in the presence of perfluorinated borate/borane cocatalysts and R2AlCl-type activators (R = Me, Et) is provided, probing the monomers isoprene and 1,3-butadiene (and preliminary ethylene). Virtually complete cis-1,4-selectivities are obtained for several catalyst/cocatalyst combinations (e.g., Gd(AlMe4)3/Me2AlCl, >99.9%). Insights into the ‘black box’ of active species are obtained by indirect observations via screening of pre-reaction time and cocatalyst concentration. The microstructure of the polydienes is investigated by combined 1H/13C NMR and ATR-IR spectroscopies. Furthermore, the reaction of [LuMe6(Li(thf)x)3] with AlMe3 has been applied as a new strategy for the efficient synthesis of Lu(AlMe4)3. The solid-state structures of Gd(AlMe4)3 and Tb(AlMe4)3 are reported.
      Citation: Catalysts
      PubDate: 2018-02-03
      DOI: 10.3390/catal8020061
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 62: In-Situ Liquid Hydrogenation of
           m-Chloronitrobenzene over Fe-Modified Pt/Carbon Nanotubes Catalysts

    • Authors: Feng Li, Jinrong Liang, Wenxi Zhu, Hua Song, Keliang Wang, Cuiqin Li
      First page: 62
      Abstract: In-situ liquid-phase hydrogenation of m-chloronitrobenzene (m-CNB) based on aqueous-phase reforming (APR) of ethanol and catalytic hydrogenation was carried out over Fe-modified Pt/carbon nanotubes (CNTs) catalysts. The effects of Pt loading over CNTs and Fe modification on the catalytic performance of Pt/CNTs catalysts were studied. In-tube loading of Pt particles, compared with out-tube loading, considerably improved the catalytic activity. With in-tube loading, Fe-modified Pt/CNTs catalysts further improved the m-CNB in-situ hydrogenation performance. After Fe modification, Pt–Fe/CNTs catalysts formed, inside CNTs, a Pt–Fe alloy and iron oxides, which both improved catalytic hydrogenation performance and significantly enhanced ethanol APR hydrogen producing performance, thereby increasing the m-CNB in-situ hydrogenation reactivity.
      Citation: Catalysts
      PubDate: 2018-02-04
      DOI: 10.3390/catal8020062
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 63: In Situ UV-Visible Assessment of Iron-Based
           High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An
           Extent of Reduction Study

    • Authors: Basseem Hallac, Jared Brown, Eli Stavitski, Roger Harrison, Morris Argyle
      First page: 63
      Abstract: The extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt %) lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe3O4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible light using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe2O3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe+2.57 for the catalyst with no lanthana and Fe+2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe+2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe+2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. The paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.
      Citation: Catalysts
      PubDate: 2018-02-04
      DOI: 10.3390/catal8020063
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 64: The CoAlCeO Mixed Oxide: An Alternative to
           Palladium-Based Catalysts for Total Oxidation of Industrial VOCs

    • Authors: Julien Brunet, Eric Genty, Cédric Barroo, Fabrice Cazier, Christophe Poupin, Stéphane Siffert, Diane Thomas, Guy De Weireld, Thierry Visart de Bocarmé, Renaud Cousin
      First page: 64
      Abstract: Catalytic total oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents, and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The catalytic total oxidation of VOCs on noble metal materials is effective. However, the cost of catalysts is a main obstacle for the industrial application of these VOC removal processes. Therefore, the aim of this work is to propose an alternative material to palladium-based catalysts (which are suitable for VOCs’ total oxidation): a mixed oxide synthesized in the hydrotalcite way, namely CoAlCeO. This material was compared to four catalytic materials containing palladium, selected according to the literature: Pd/α-Al2O3, Pd/HY, Pd/CeO2 and Pd/γ­Al2O3. These materials have been studied for the total oxidation of toluene, butanone, and VOCs mixtures. Catalysts’ performances were compared, taking into account the oxidation byproducts emitted from the process. This work highlight that the CoAlCeO catalyst presents better efficiency than Pd-based materials for the total oxidation of a VOCs mixture.
      Citation: Catalysts
      PubDate: 2018-02-06
      DOI: 10.3390/catal8020064
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 65: Oxygen Reduction Reaction Catalyzed by Noble
           Metal Clusters

    • Authors: Zhenghua Tang, Wen Wu, Kai Wang
      First page: 65
      Abstract: Highly-efficient catalysts for the oxygen reduction reaction (ORR) have been extensively investigated for the development of proton exchange membrane fuel cells (PEMFCs). The state-of-the-art Pt/C catalysts suffer from high price, limited accessibility of Pt, sluggish reaction kinetics, as well as undesirable long-term durability. Engineering ultra-small noble metal clusters with high surface-to-volume ratios and robust stabilities for ORR represents a new avenue. After a simple introduction regarding the significance of ORR and the recent development of noble metal clusters, the general ORR mechanism in both acidic and basic media is firstly discussed. Subsequently, we will summarize the recent efforts employing Pt, Au, Ag, Pd and Ru clusters, as well as the alloyed bi-metallic clusters for acquiring highly efficient catalysts to enhance both the activity and stability of ORR. Molecular noble metal clusters with definitive composition to reveal the relevant ORR mechanism will be particularly highlighted. Finally, the current challenges, the future outlook, as well as the perspectives in this booming field will be proposed, featuring the great opportunities and potentials to engineering noble metal clusters as highly-efficient and durable cathodic catalysts for fuel cell applications.
      Citation: Catalysts
      PubDate: 2018-02-07
      DOI: 10.3390/catal8020065
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 66: Active and Stable Methane Oxidation
           Nano-Catalyst with Highly-Ionized Palladium Species Prepared by Solution
           Combustion Synthesis

    • Authors: Mahmoud Khader, Mohammed Al-Marri, Sardar Ali, Ahmed Abdelmoneim
      First page: 66
      Abstract: We report on the synthesis and testing of active and stable nano-catalysts for methane oxidation. The nano-catalyst was palladium/ceria supported on alumina prepared via a one-step solution-combustion synthesis (SCS) method. As confirmed by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HTEM), SCS preparative methodology resulted in segregating both Pd and Ce on the surface of the Al2O3 support. Furthermore, HTEM showed that bigger Pd particles (5 nm and more) were surrounded by CeO2, resembling a core shell structure, while smaller Pd particles (1 nm and less) were not associated with CeO2. The intimate Pd-CeO2 attachment resulted in insertion of Pd ions into the ceria lattice, and associated with the reduction of Ce4+ into Ce3+ ions; consequently, the formation of oxygen vacancies. XPS showed also that Pd had three oxidation states corresponding to Pd0, Pd2+ due to PdO, and highly ionized Pd ions (Pd(2+x)+) which might originate from the insertion of Pd ions into the ceria lattice. The formation of intrinsic Ce3+ ions, highly ionized (Pd2+ species inserted into the lattice of CeO2) Pd ions (Pd(2+x)+) and oxygen vacancies is suggested to play a major role in the unique catalytic activity. The results indicated that the Pd-SCS nano-catalysts were exceptionally more active and stable than conventional catalysts. Under similar reaction conditions, the methane combustion rate over the SCS catalyst was ~18 times greater than that of conventional catalysts. Full methane conversions over the SCS catalysts occurred at around 400 °C but were not shown at all with conventional catalysts. In addition, contrary to the conventional catalysts, the SCS catalysts exhibited superior activity with no sign of deactivation in the temperature range between ~400 and 800 °C.
      Citation: Catalysts
      PubDate: 2018-02-07
      DOI: 10.3390/catal8020066
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 67: Catalytic Wet Oxidation of Pharmaceutical
           Sludge by Molecular Sieve Loaded with Cu/Ce

    • Authors: Xu Zeng, Jun Liu, Jianfu Zhao
      First page: 67
      Abstract: In the present study, the catalytic wet oxidation of pharmaceutical sludge by molecular sieve loaded with Cu/Ce as catalyst was investigated. Experiments were performed in an experimental batch reactor. Reaction parameters including catalyst dose, temperature, time, and oxygen pressure were discussed. The results showed that the catalysts prepared by co-precipitating method have good catalytic performance. Under optimum conditions, the highest volatile suspended solids (VSS) removal rate approximately 92% and chemical oxygen demand (COD) removal rate of 75% were obtained at 260 °C for 60 min with initial oxygen pressure 1.0 MPa and the catalyst 10 g/L. These results implied that the catalytic wet oxidation of pharmaceutical sludge by molecular sieve loaded with Cu/Ce is a promising method for the highly efficient degradation of the sludge.
      Citation: Catalysts
      PubDate: 2018-02-08
      DOI: 10.3390/catal8020067
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 68: Nano-Immobilized Biocatalysts for Biodiesel
           Production from Renewable and Sustainable Resources

    • Authors: Keon Kim, Ok Lee, Eun Lee
      First page: 68
      Abstract: The cost of biodiesel production relies on feedstock cost. Edible oil is unfavorable as a biodiesel feedstock because of its expensive price. Thus, non-edible crop oil, waste oil, and microalgae oil have been considered as alternative resources. Non-edible crop oil and waste cooking oil are more suitable for enzymatic transesterification because they include a large amount of free fatty acids. Recently, enzymes have been integrated with nanomaterials as immobilization carriers. Nanomaterials can increase biocatalytic efficiency. The development of a nano-immobilized enzyme is one of the key factors for cost-effective biodiesel production. This paper presents the technology development of nanomaterials, including nanoparticles (magnetic and non-magnetic), carbon nanotubes, and nanofibers, and their application to the nano-immobilization of biocatalysts. The current status of biodiesel production using a variety of nano-immobilized lipase is also discussed.
      Citation: Catalysts
      PubDate: 2018-02-08
      DOI: 10.3390/catal8020068
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 69: New Trendy Magnetic C-Scorpionate Iron
           Catalyst and Its Performance towards Cyclohexane Oxidation

    • Authors: Ana Ribeiro, Inês Matias, Elisabete Alegria, Ana Ferraria, Ana Botelho do Rego, Armando Pombeiro, Luísa Martins
      First page: 69
      Abstract: For the first time, a magnetic C-scorpionate catalyst was prepared from the iron(II) complex [FeCl2{κ3-HC(pz)3}] (pz = pyrazol-1-yl) and ferrite, using the sustainable mechanochemical synthetic procedure. Its catalytic activity for the cyclohexane oxidation with tert-butyl hydroperoxide (TBHP) was evaluated in different conditions, namely under microwave irradiation and under the effect of an external magnetic field. The use of such magnetic conditions significantly shifted the catalyst alcohol/ketone selectivity, thus revealing a promising, easy new protocol for tuning selectivity in important catalytic processes.
      Citation: Catalysts
      PubDate: 2018-02-08
      DOI: 10.3390/catal8020069
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 70: Low Temperature Synthesis of Nest-Like
           Microsphere with Exposed (001) Facets and Its Enhanced Photocatalytic
           Performance by NaOH Alkalization

    • Authors: Chentao Hou, Jiaming Zhu, Qiaoqiao Song
      First page: 70
      Abstract: In this study, we completed a simple low-temperature synthesis of nest-like titanium oxide (TiO2) microspheres with exposed (001) facets. For the first time, the photocatalytic performance was enhanced by sodium hydroxide (NaOH) alkalization. The characterization of as-synthesized F-TiO2 and OH-TiO2 were analyzed by field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, fourier transform infrared spectroscopic analysis, ultraviolet-vis diffuse reflection spectra and Raman spectroscopy. The photocatalytic activity of the as-prepared catalyst was evaluated through the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RhB) under simulated solar light. The results showed that modification using NaOH can lead to an increase in the percentage of (001) facets from 27.8% for F-TiO2 to 39.2% for OH-TiO2. OH-TiO2 showed superior catalytic photoactivity toward MB. The mechanism of NaOH on TiO2 is also discussed.
      Citation: Catalysts
      PubDate: 2018-02-08
      DOI: 10.3390/catal8020070
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 71: Effect of Dopant Loading on the Structural
           and Catalytic Properties of Mn-Doped SrTiO3 Catalysts for Catalytic Soot
           Combustion

    • Authors: Santiago Suárez-Vázquez, Arquímedes Cruz-López, Carlos Molina-Guerrero, Astrid Sánchez-Vázquez, Carlos Macías-Sotelo
      First page: 71
      Abstract: Soot particles have been associated with respiratory diseases and cancer. To decrease these emissions, perovskite-mixed oxides have been proposed due to their thermal stability and redox surface properties. In this work, SrTiO3 doped with different amounts of Mn were synthesized by the hydrothermal method and tested for soot combustion. Results show that at low Mn content, structural distortion, and higher Oads/Olat ratio were observed which was attributed to the high content of Mn3+ in Ti sites. On the other hand, increasing the Mn content led to surface segregation of manganese oxide. All synthesized catalysts showed mesopores in the range of 32–47 nm. In the catalytic combustion of soot, the samples synthesized in this work lowered the combustion temperature by more than 100 °C compared with the uncatalyzed reaction. The sample doped with 1 wt % of Mn showed the best catalytic activity. The activation energy of these samples was also calculated, and the order of decreasing activation energy is as follows: uncatalyzed > Mn0 > Mn8 > Mn4 > Mn1. The best catalytic activity for Mn1 was attributed to its physicochemical properties and the mobility of the oxygen from the bulk to the surface at temperatures higher than 500 °C.
      Citation: Catalysts
      PubDate: 2018-02-09
      DOI: 10.3390/catal8020071
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 72: Modeling of a Pilot-Scale Fixed-Bed Reactor
           for Dehydration of 2,3-Butanediol to 1,3-Butadiene and Methyl Ethyl Ketone
           

    • Authors: Daesung Song
      First page: 72
      Abstract: A 1D heterogeneous reactor model accounting for interfacial and intra-particle gradients was developed to simulate the dehydration of 2,3-Butanediol (2,3-BDO) to 1,3-Butadiene (1,3-BD) and Methyl Ethyl Ketone (MEK) over an amorphous calcium phosphate (a-CP) catalyst in a pilot-scale fixed-bed reactor. The developed model was validated with experimental data in terms of a fluid temperature profile along with the length of the catalyst bed, 2,3-BDO conversion, and selectivity for the major products, 1,3-BD and MEK, at the outlet of the reactor. The fluid temperature profile obtained from the model along the length of the catalyst bed coincides satisfactorily with the experimental observations. The difference between the experimental data and the 1D heterogeneous reactor model prediction for 2,3-BDO conversion and selectivity of 1,3-BD and MEK were 0.1%, 9 wt %, and 2 wt %, respectively. In addition, valuable insights related to the feeding system of a commercial-scale plant were made through troubleshooting of the pilot tests. Notably, if the feed including only 2,3-BDO and furnaces that increase the temperature of the feed to the reaction temperature were used in a commercial plant, the feeding system could not be operational because of the presence of heavy chemicals considered oligomers of 2,3-BDO.
      Citation: Catalysts
      PubDate: 2018-02-09
      DOI: 10.3390/catal8020072
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 73: Wood-Biochar-Supported Magnetite
           Nanoparticles for Remediation of PAH-Contaminated Estuary Sediment

    • Authors: Cheng-Di Dong, Chiu-Wen Chen, Chih-Ming Kao, Chuan-Chi Chien, Chang-Mao Hung
      First page: 73
      Abstract: In this study, we investigated the ability of a magnetic wood biochar (WB)-based composite catalyst (Fe3O4–WB) to catalyze sodium persulfate (PS) for the remediation of estuary sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). The effects of various critical parameters, including the catalyst dose and initial pH, were investigated. The degradation of the PAHs was found to be related to the number of rings in their structure. The results showed that Fe3O4–WB is an efficient catalyst for the removal of high-ring PAHs (HPAHs), with the highest degradation rates for the 6-, 5-, and 4-ringed PAHs being 90%, 84%, and 87%, respectively, for a PS concentration of 2 × 10−5 M, catalyst concentration of 3.33 g/L, and pH of 3.0. That the reduction rate of the HPAHs was greater than that of the low-ring PAHs can be attributed to the strong affinity of the HPAHs for biochar derived from wood biomass. Overall, this study revealed that the WB-mediated electron transfer catalysis of the surface functional groups in a wide range of pH in the Fe3O4–WB/PS system and potentially application in the remediation of sediments contaminated with PAHs.
      Citation: Catalysts
      PubDate: 2018-02-09
      DOI: 10.3390/catal8020073
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 74: g-C3N4-Based Nanomaterials for Visible
           Light-Driven Photocatalysis

    • Authors: Santosh Kumar, Sekar Karthikeyan, Adam F. Lee
      First page: 74
      Abstract: Graphitic carbon nitride (g-C3N4) is a promising material for photocatalytic applications such as solar fuels production through CO2 reduction and water splitting, and environmental remediation through the degradation of organic pollutants. This promise reflects the advantageous photophysical properties of g-C3N4 nanostructures, notably high surface area, quantum efficiency, interfacial charge separation and transport, and ease of modification through either composite formation or the incorporation of desirable surface functionalities. Here, we review recent progress in the synthesis and photocatalytic applications of diverse g-C3N4 nanostructured materials, and highlight the physical basis underpinning their performance for each application. Potential new architectures, such as hierarchical or composite g-C3N4 nanostructures, that may offer further performance enhancements in solar energy harvesting and conversion are also outlined.
      Citation: Catalysts
      PubDate: 2018-02-09
      DOI: 10.3390/catal8020074
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 75: One-Pot Combination of Metal- and
           Bio-Catalysis in Water for the Synthesis of Chiral Molecules

    • Authors: Nicolás Ríos-Lombardía, Joaquín García-Álvarez, Javier González-Sabín
      First page: 75
      Abstract: During the last decade, the combination of different metal- and bio-catalyzed organic reactions in aqueous media has permitted the flourishing of a variety of one-pot asymmetric multi-catalytic reactions devoted to the construction of enantiopure and high added-value chemicals under mild reaction conditions (usually room temperature) and in the presence of air. Herein, a comprehensive account of the state-of-the-art in the development of catalytic networks by combining metallic and biological catalysts in aqueous media (the natural environment of enzymes) is presented. Among others, the combination of metal-catalyzed isomerizations, cycloadditions, hydrations, olefin metathesis, oxidations, C-C cross-coupling and hydrogenation reactions, with several biocatalyzed transformations of organic groups (enzymatic reduction, epoxidation, halogenation or ester hydrolysis), are discussed.
      Citation: Catalysts
      PubDate: 2018-02-10
      DOI: 10.3390/catal8020075
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 76: Mn-Ce-V-WOx/TiO2 SCR Catalysts: Catalytic
           Activity, Stability and Interaction among Catalytic Oxides

    • Authors: Xuteng Zhao, Lei Mao, Guojun Dong
      First page: 76
      Abstract: A series of Mn-Ce-V-WOx/TiO2 composite oxide catalysts with different molar ratios (active components/TiO2 = 0.1, 0.2, 0.3, 0.6) have been prepared by wet impregnation method and tested in selective catalytic reduction (SCR) of NO by NH3 in a wide temperature range. These catalysts were also characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), in situ Fourier Transform infrared spectroscopy (in situ FTIR), H2-Temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The results show the catalyst with a molar ratio of active components/TiO2 = 0.2 exhibits highest NO conversion value between 150 °C to 400 °C and good resistance to H2O and SO2 at 250 °C with a gas hourly space velocity (GHSV) value of 40,000 h−1. Different oxides are well dispersed and interact with each other. NH3 and NO are strongly adsorbed on the catalyst surface and the adsorption of the reactant gas leads to a redox cycle with the valence state change among the surface oxides. The adsorption of SO2 on Mn4+ and Ce4+ results in good H2O and SO2 resistance of the catalyst, but the effect of Mn and Ce are more than superior water and sulfur resistance. The diversity of valence states of the four active components and their high oxidation-reduction performance are the main reasons for the high NO conversion in this system.
      Citation: Catalysts
      PubDate: 2018-02-12
      DOI: 10.3390/catal8020076
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 77: Effect of Support Pretreatment Temperature on
           the Performance of an Iron Fischer–Tropsch Catalyst Supported on
           Silica-Stabilized Alumina

    • Authors: Kamyar Keyvanloo, Baiyu Huang, Trent Okeson, Hussein Hamdeh, William Hecker
      First page: 77
      Abstract: The effect of support material pretreatment temperature, prior to adding the active phase and promoters, on Fischer–Tropsch activity and selectivity was explored. Four iron catalysts were prepared on silica-stabilized alumina (AlSi) supports pretreated at 700 °C, 900 °C, 1100 °C or 1200 °C. Addition of 5% silica to alumina made the AlSi material hydrothermally stable, which enabled the unusually high support pretreatment temperatures (>900 °C) to be studied. High-temperature dehydroxylation of the AlSi before impregnation greatly reduces FeO·Al2O3 surface spinel formation by removing most of the support-surface hydroxyl groups leading to more effectively carbided catalyst. The activity increases more than four-fold for the support calcined at elevated temperatures (1100–1200 °C) compared with traditional support calcination temperatures of <900 °C. This unique pretreatment also facilitates the formation of ε′-Fe2.2C rather than χ-Fe2.5C on the AlSi support, which shows an excellent correlation with catalyst productivity.
      Citation: Catalysts
      PubDate: 2018-02-12
      DOI: 10.3390/catal8020077
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 78: Photocatalytic Reduction of CO2 from
           Simulated Flue Gas with Colored Anatase

    • Authors: Yebin Guan, Ming Xia, Alessandro Marchetti, Xiaohong Wang, Weicheng Cao, Hanxi Guan, Xueqian Kong
      First page: 78
      Abstract: Photocatalytic reduction with sunlight is an economical and promising advanced approach for reducing the excessive emissions of CO2 from the combustion of fossil fuels. Aimed at practical applications, a type of inexpensive colored anatase material was used to evaluate CO2 photoreduction performance on a platform with a continuous flow of gas mixtures (10 vol % CO2, 90% N2), which resembles realistic flue gas conditions. The results showed an enhanced photocatalytic activity compared with standard P25 and significant improvement over pristine anatase. Based on a series of characterization techniques, we propose that the oxygen vacancies and surface hydroxyl groups on colored anatase can reduce the bandgap and assist the binding of CO2 molecules. Our results showed that photoreduction of CO2 is feasible under practical conditions, and the efficiency could be improved through modification of catalysts.
      Citation: Catalysts
      PubDate: 2018-02-13
      DOI: 10.3390/catal8020078
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 79: Heterogeneous Catalysis by Tetraethylammonium
           Tetrachloroferrate of the Photooxidation of Toluene by Visible and Near-UV
           Light

    • Authors: Kelsie Barnard, Valerie Bright, Robert Enright, Kira Fahy, Adam Liu, Patrick Hoggard
      First page: 79
      Abstract: Titanium dioxide is the most extensively used heterogeneous catalyst for the photooxidation of toluene and other hydrocarbons, but it has low utility for the synthesis of benzyl alcohol, of which little is produced, or benzaldehyde, due to further oxidation to benzoic acid and cresol, among other oxidation products, and eventually complete mineralization to CO2. Et4N[FeCl4] functions as a photocatalyst through the dissociation of chlorine atoms, which abstract hydrogen from toluene, and the photooxidation of toluene proceeds only as far as benzyl alcohol and benzaldehyde. Unlike TiO2, which requires ultraviolet (UV) irradiation, Et4N[FeCl4] catalyzes the photooxidation of toluene with visible light alone. Even under predominantly UV irradiation, the yield of benzyl alcohol plus benzaldehyde is greater with Et4N[FeCl4] than with TiO2. Et4N[FeCl4] photocatalysis yields benzyl chloride as a side product, but it can be minimized by restricting irradiation to wavelengths above 360 nm and by the use of long irradiation times. The photonic efficiency of oxidation in one experiment was found to be 0.042 mol/einstein at 365 nm. The use of sunlight as the irradiation source was explored.
      Citation: Catalysts
      PubDate: 2018-02-13
      DOI: 10.3390/catal8020079
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 80: Oriented Decoration in Metal-Functionalized
           Ordered Mesoporous Silicas and Their Catalytic Applications in the
           Oxidation of Aromatic Compounds

    • Authors: Shijian Zhou, Fu Yang, Bangbang Wang, Hang Su, Kangchao Lu, Yun Ding, Kai Lei, Man Xu, Bo Shao, Yun Wang, Yan Kong
      First page: 80
      Abstract: Ordered mesoporous silicas (OMSs) attract considerable attention due to their advanced structural properties. However, for the pristine silica materials, the inert property greatly inhibits their catalytic applications. Thus, to contribute to the versatile surface of OMSs, different metal active sites, including acidic/basic sites and redox sites, have been introduced into specific locations (mesoporous channels and framework) of OMSs and the metal-functionalized ordered mesoporous silicas (MOMSs) show great potential in the catalytic applications. In this review, we first present the categories of metal active sites. Then, the synthesized processes of MOMSs are thoroughly discussed, in which the metal active sites would be introduced with the assistance of organic groups into the specific locations of OMSs. In addition, the structural morphologies of OMSs are elaborated and the catalytic applications of MOMSs in the oxidation of aromatic compounds are illustrated in detail. Finally, the prospects for the future development in this field are proposed.
      Citation: Catalysts
      PubDate: 2018-02-13
      DOI: 10.3390/catal8020080
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 81: Optimization of Biodiesel Production from
           Waste Cooking Oil Using Waste Eggshell as a Base Catalyst under a
           Microwave Heating System

    • Authors: Yen-Ping Peng, Kassian Amesho, Chin-En Chen, Syu-Ruei Jhang, Feng-Chih Chou, Yuan-Chung Lin
      First page: 81
      Abstract: This paper intends to explore the most affordable and environmentally friendly method for the synthesis of biodiesel. Substitute fuel is presently a significant topic all over the world, attributable to the efforts of reducing global warming, which is the result arising from the combustion of petroleum or petrol diesel fuel. Due to its advantages of being renewable and environmentally friendly, biodiesel production has the potential to become the major substitute of petrol diesel fuel. Biodiesel is non-toxic, biodegradable, is produced from renewable sources, and contributes a small amount of greenhouse gas (e.g., CO2 and SO2) emissions to the atmosphere. Research has established that one of the key obstacles to the commercialization of biodiesel is the high price of biodiesel production due to the shortage of suitable raw materials. However, waste-cooking-oil (WCO) is one of the most cost-effective sources of biodiesel synthesis, and can practically minimize the raw material cost. The research was carried out to produce biodiesel from waste cooking oil in order to reduce the cost, waste, and pollution associated with biodiesel production. The application of a microwave heating system towards enhancing the production of biodiesel from waste cooking oil has been given little consideration in the preceding research, particularly with the application of eggshell as a heterogeneous catalyst. However, the tentative results in this study show significant performance in terms of biodiesel production, as follows: (1) the increasing of the reaction time from 120 to 165 min considerably increased the biodiesel production, which declined with a further rise to 210 min; (2) the results of this study reveal that a methanol-to-oil molar ratio of nine is appropriate and can be used for the best production of biodiesel; (3) the production of biodiesel in this study demonstrated a significant increase in response to the further increasing of power; (4) a 120 min response time, a ratio of 9:1 methanol-to-oil molar fraction, 65 °C temperature; (5) and 5 wt % catalyst were found to be the most ideal reaction conditions during this study. In summary, recycled eggshell was re-used as a suitable catalyst to produce new biodiesel from waste cooking oil, applicable to diesel engines.
      Citation: Catalysts
      PubDate: 2018-02-14
      DOI: 10.3390/catal8020081
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 82: Catalytic Fast Pyrolysis of Kraft Lignin over
           Hierarchical HZSM-5 and Hβ Zeolites

    • Authors: Yadong Bi, Xiaojuan Lei, Guihua Xu, Hui Chen, Jianli Hu
      First page: 82
      Abstract: The hierarchical HZSM-5 and Hβ zeolites were prepared by alkaline post-treatment methods adopting Na2CO3, TMAOH/NaOH mixture, and NaOH as desilication sources, respectively. More mesopores are produced over two kinds of zeolites, while the micropores portion is well preserved. The mesopores formed in hierarchical Hβ zeolites were directly related to the basicity of the alkaline solution, indicating that Hβ zeolite is more sensitive to the alkaline post-treatment. The hierarchical HZSM-5 and Hβ zeolites are more active than the parent one for catalytic fast pyrolysis (CFP) of Kraft lignin. Hierarchical zeolites retained the function of acid catalysis, while additionally creating larger mesopores to ensure the entry of bulkier reactant molecules. The increase of the condensable volatiles yield can be attributed to the improvement of the mass transfer performance, which correlates well with the change of mesoporous surface area. In particular, the condensable volatiles yield for the optimized hierarchical Hβ reached approximately two times that of the parent Hβ zeolites. In contrast to the parent HZSM-5, the optimized hierarchical HZSM-5 zeolite significantly reduced the selectivity of oxygenates from 27.2% to 3.3%.
      Citation: Catalysts
      PubDate: 2018-02-14
      DOI: 10.3390/catal8020082
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 83: Aerobic Oxidation of Benzyl Alcohol on a
           Strontium-Based Gold Material: Remarkable Intrinsic Basicity and Reusable
           Catalyst

    • Authors: Karla Patrícia R. Castro, Marco Aurélio S. Garcia, Wiury C. de Abreu, Samuel Anderson A. de Sousa, Carla Verônica R. de Moura, Jean Cláudio S. Costa, Edmilson M. de Moura
      First page: 83
      Abstract: The development of stable and active gold catalysts has arisen as a significant strategy for oxidation of alcohols. Nano-size PVA-stabilized gold nanoparticles immobilized on Sr(OH)2 by colloidal deposition presented high catalytic activity for benzyl alcohol oxidation. In 2.5 h, 2 bar of O2 and without extra-base addition, the calcined support reached 54.6% (100 °C) and 67.4% (140 °C) of conversion, presenting the remarkable and unexplored intrinsic basicity that strontium-based materials retain. With sub-stoichiometric K2CO3 adding, under the same catalytic conditions, the catalyst conducted the reaction with similar activity, but with excellent reusability in the process, without any gold leaching. We investigated the influence that the support synthesis method and the solvent used for the NPs stabilization have on the oxidation activity. The produced materials were fully characterized by XPS, Rietveld refinement, and TEM.
      Citation: Catalysts
      PubDate: 2018-02-15
      DOI: 10.3390/catal8020083
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 84: Immobilization Effects on the Catalytic
           Properties of Two Fusarium Verticillioides Lipases: Stability, Hydrolysis,
           Transesterification and Enantioselectivity Improvement

    • Authors: Fernanda Dell Antonio Facchini, Marita Gimenez Pereira, Ana Claudia Vici, Marco Filice, Benevides Costa Pessela, Jose Manuel Guisan, Glória Fernandez-Lorente, Maria de Lourdes Teixeira de Moraes Polizeli
      First page: 84
      Abstract: Fusarium verticillioides lipases were purified in a “cascade” method using octadecyl Sepabeads and octyl Sepharose resins, which led to the isolation of two proteins with lipolytic activities. Lip 1 was purified after octyl Sepharose adsorption presenting 30.3 kDa and, Lip 2 presented 68.0 kDa after octadecyl adsorption. These immobilization processes resulted in an increase of 3-fold in activity of each immobilized enzyme. These enzymes presented optima of pH of 5.0 and 6.0, respectively and temperature at 40 °C. They were thermostable at 40 °C and both remained more than 50% of its activity at the pH range of 5.0 to 7.0, with 180 min of incubation. The sardine oil hydrolysis showed higher EPA/DHA ratio. Concerning the ethanolysis reaction, Lip 2 showed higher conversion (5.5%) and both lipases showed activity in the release of the S enantiomers from 2-O-butyryl-2-phenylacetic acid (mandelic butyrate acid) and HPBE hydrolysis. Lip 2 also demonstrated capacity of transesterification. These applications made these enzymes attractive for industrial application.
      Citation: Catalysts
      PubDate: 2018-02-16
      DOI: 10.3390/catal8020084
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 85: Influence of an Electronic Structure of
           N-TiO2 on Its Photocatalytic Activity towards Decomposition of
           Acetaldehyde under UV and Fluorescent Lamps Irradiation

    • Authors: Beata Tryba, Magdalena Wozniak, Grzegorz Zolnierkiewicz, Nikos Guskos, Antoni Morawski, Christophe Colbeau-Justin, Rafał Wrobel, Akio Nitta, Bunsho Ohtani
      First page: 85
      Abstract: The electronic structure of N-TiO2 samples prepared by a sol-gel method was investigated by EPR (Electronic Paramagnetic Resonance) measurements and the energy-resolved distribution of electron traps. In EPR spectra, some of the resonance lines assigned to paramagnetic species of nitrogen and Ti3+ were detected. Sample prepared at 300 °C revealed the highest intensity line of the nitrogen paramagnetic centers, whereas that prepared at 400 °C showed a paramagnetic line for Ti3+. Measurements of the electron trap distribution showed higher density of electron traps for sample prepared at 400 °C than that at 300 °C. Sample prepared at 300 °C, which revealed the highest amount of nitrogen built in the titania in the interstitial position was the most active under visible light. It was evidenced that photocatalytic decomposition of acetaldehyde was dependent strongly on the BET surface area and electrokinetic potential of the photocatalyst surface. The UV content in the fluorescent lamp affected the yield of acetaldehyde decomposition.
      Citation: Catalysts
      PubDate: 2018-02-20
      DOI: 10.3390/catal8020085
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 86: Improved Kinetic Data Acquisition Using An
           Optically Accessible Catalytic Plate Reactor with Spatially-Resolved
           Measurement Techniques. Case of Study: CO2 Methanation

    • Authors: Jose A. Hernandez Lalinde, Kevin Kofler, Xuejie Huang, Jan Kopyscinski
      First page: 86
      Abstract: Modelling and optimization of chemical reactors require a good understanding of the reactions mechanism with the corresponding kinetic description. Therefore, high quality kinetic data are needed, which can be challenging to obtain, especially for fast and highly exothermic reactions such as the CO2 methanation. Traditionally, kinetic studies rely on measuring the exit gas composition (1 data point per species and experiment) using differential reactors with diluted catalyst beds and reactants to avoid temperature change. Therefore, an optically accessible catalytic channel reactor was designed, which allowed for the chance to gather spatially-resolved information on axial gas composition and catalyst surface temperature, specifically by means of a movable sampling capillary and shortwave infrared-thermography (SWIR), respectively. A catalyst coated plate was placed at the bottom of the channel, while a set of two quartz glass plates covers the top. In the current study 35 data points per gas species were collect for 1 experiment conducted under laminar flow conditions at 425 °C. Catalyst surface temperature determined via a SWIR camera was not influenced by polyatomic molecules partaking in the reaction and thus did not falsify the kinetic data. The catalyst mass distribution along the reactor axis was determined, enabling the development of a correct reactor model for kinetic parameter estimation and model discrimination.
      Citation: Catalysts
      PubDate: 2018-02-21
      DOI: 10.3390/catal8020086
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 87: The H2-Treated TiO2 Supported Pt Catalysts
           Prepared by Strong Electrostatic Adsorption for Liquid-Phase Selective
           Hydrogenation

    • Authors: Sasithorn Kuhaudomlap, Okorn Mekasuwandumrong, Piyasan Praserthdam, Shin-Ichiro Fujita, Masahiko Arai, Joongjai Panpranot
      First page: 87
      Abstract: The H2-treated TiO2 supported Pt catalysts were prepared by strong electrostatic adsorption method and tested in the liquid-phase selective hydrogenation of various organic compounds such as 3-nitrostyrene to vinylaniline (VA) and furfural to furfuryl alcohol (FA). A combination of high Pt dispersion, strong interaction of Pt-TiOx, and the presence of low coordination Pt sites was necessary for high hydrogenation activity. However, while the selectivity of VA in 3-nitrostyrene hydrogenation did not depend much on the catalyst preparation method used, the selectivity of FA in furfural hydrogenation was much higher when the catalysts were prepared by SEA, comparing to those obtained by impregnation in which the solvent product was formed, due probably to the non-acidic conditions used during Pt loading by SEA method.
      Citation: Catalysts
      PubDate: 2018-02-22
      DOI: 10.3390/catal8020087
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 88: Ruthenium(II)-Arene Complexes of the
           Water-Soluble Ligand CAP as Catalysts for Homogeneous Transfer
           Hydrogenations in Aqueous Phase

    • Authors: Antonella Guerriero, Maurizio Peruzzini, Luca Gonsalvi
      First page: 88
      Abstract: The neutral Ru(II) complex κP-[RuCl2(η6-p-cymene)(CAP)] (1), and the two ionic complexes κP-[RuCl(η6-p-cymene)(MeCN)(CAP)]PF6 (2) and κP-[RuCl(η6-p-cymene)(CAP)2]PF6 (3), containing the water-soluble phosphine 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP), were tested as catalysts for homogeneous hydrogenation of benzylidene acetone, selectively producing the saturated ketone as product. The catalytic tests were carried out in aqueous phase under transfer hydrogenation conditions, at mild temperatures using sodium formate as hydrogen source. Complex 3, which showed the highest stability under the reaction conditions applied, was also tested for C=N bond reduction from selected cyclic imines. Preliminary NMR studies run under pseudo-catalytic conditions starting from 3 showed the formation of κP-[RuH(η6-p-cymene)(CAP)2]PF6 (4) as the pivotal species in catalysis.
      Citation: Catalysts
      PubDate: 2018-02-22
      DOI: 10.3390/catal8020088
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 89: Catalysis and Downsizing in Mg-Based Hydrogen
           Storage Materials

    • Authors: Jianding Li, Bo Li, Huaiyu Shao, Wei Li, Huaijun Lin
      First page: 89
      Abstract: Magnesium (Mg)-based materials are promising candidates for hydrogen storage due to the low cost, high hydrogen storage capacity and abundant resources of magnesium for the realization of a hydrogen society. However, the sluggish kinetics and strong stability of the metal-hydrogen bonding of Mg-based materials hinder their application, especially for onboard storage. Many researchers are devoted to overcoming these challenges by numerous methods. Here, this review summarizes some advances in the development of Mg-based hydrogen storage materials related to downsizing and catalysis. In particular, the focus is on how downsizing and catalysts affect the hydrogen storage capacity, kinetics and thermodynamics of Mg-based hydrogen storage materials. Finally, the future development and applications of Mg-based hydrogen storage materials is discussed.
      Citation: Catalysts
      PubDate: 2018-02-23
      DOI: 10.3390/catal8020089
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 90: Advances in Enantioselective C–H
           Activation/Mizoroki-Heck Reaction and Suzuki Reaction

    • Authors: Shuai Shi, Khan Shah Nawaz, Muhammad Kashif Zaman, Zhankui Sun
      First page: 90
      Abstract: Traditional cross-coupling reactions, like Mizoroki-Heck Reaction and Suzuki Reaction, have revolutionized organic chemistry and are widely applied in modern organic synthesis. With the rapid development of C–H activation and asymmetric catalysis in recent years, enantioselective C–H activation/cross-coupling reactions have drawn much attention from researchers. This review summarizes recent advances in enantioselective C–H activation/Mizoroki-Heck Reaction and Suzuki Reaction, with emphasis on the structures and functions of chiral ligands utilized in different reactions.
      Citation: Catalysts
      PubDate: 2018-02-23
      DOI: 10.3390/catal8020090
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 91: The Design of MnOx Based Catalyst in
           Post-Plasma Catalysis Configuration for Toluene Abatement

    • Authors: Zhiping Ye, Jean-Marc Giraudon, Nathalie De Geyter, Rino Morent, Jean-François Lamonier
      First page: 91
      Abstract: This review provides an overview of our present state of knowledge using manganese oxide (MnOx)-based catalysts for toluene abatement in PPC (Post plasma-catalysis) configuration. The context of this study is concisely sum-up. After briefly screening the main depollution methods, the principles of PPC are exposed based on the coupling of two mature technologies such as NTP (Non thermal plasma) and catalysis. In that respect, the presentation of the abundant manganese oxides will be firstly given. Then in a second step the main features of MnOx allowing better performances in the reactions expected to occur in the abatement of toluene in PPC process are reviewed including ozone decomposition, toluene ozonation, CO oxidation and toluene total oxidation. Finally, in a last part the current status of the applications of PPC using MnOx on toluene abatement are discussed. In a first step, the selected variables of the hybrid process related to the experimental conditions of toluene abatement in air are identified. The selected variables are those expected to play a role in the performances of PPC system towards toluene abatement. Then the descriptors linked to the performances of the hybrid process in terms of efficiency are given and the effects of the variables on the experimental outcomes (descriptors) are discussed. The review would serve as a reference guide for the optimization of the PPC process using MnOx-based oxides for toluene abatement.
      Citation: Catalysts
      PubDate: 2018-02-23
      DOI: 10.3390/catal8020091
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 92: A General Overview of Support Materials for
           Enzyme Immobilization: Characteristics, Properties, Practical Utility

    • Authors: Jakub Zdarta, Anne Meyer, Teofil Jesionowski, Manuel Pinelo
      First page: 92
      Abstract: In recent years, enzyme immobilization has been presented as a powerful tool for the improvement of enzyme properties such as stability and reusability. However, the type of support material used plays a crucial role in the immobilization process due to the strong effect of these materials on the properties of the produced catalytic system. A large variety of inorganic and organic as well as hybrid and composite materials may be used as stable and efficient supports for biocatalysts. This review provides a general overview of the characteristics and properties of the materials applied for enzyme immobilization. For the purposes of this literature study, support materials are divided into two main groups, called Classic and New materials. The review will be useful in selection of appropriate support materials with tailored properties for the production of highly effective biocatalytic systems for use in various processes.
      Citation: Catalysts
      PubDate: 2018-02-24
      DOI: 10.3390/catal8020092
      Issue No: Vol. 8, No. 2 (2018)
       
  • Catalysts, Vol. 8, Pages 93: Composites of Laminar Nanostructured ZnO and
           VOx-Nanotubes Hybrid as Visible Light Active Photocatalysts

    • Authors: Eglantina Benavente, Daniel Navas, Sindy Devis, Marjorie Segovia, Clivia Sotomayor-Torres, Guillermo González
      First page: 93
      Abstract: A series of hybrid heterostructured nanocomposites of ZnO with V2O5 nanotubes (VOx-NTs) in different mixing ratios were synthesized, with the aim of reducing the recombination of photoinduced charge carriers and to optimize the absorption of visible light. The study was focused on the use of heterostructured semiconductors that can extend light absorption to the visible range and enhance the photocatalytic performance of ZnO in the degradation of methylene blue as a model pollutant. The addition of VOx-NTs in the synthesis mixture led to a remarkable performance in the degradation of the model dye, with hybrid ZnO (stearic acid)/VOx-NTs at a ratio of 1:0.06 possessing the highest photocatalytic activity, about seven times faster than pristine zinc oxide. Diffuse reflectance spectroscopic measurements and experiments in the presence of different trapping elements allowed us to draw conclusions regarding the band positions and photocatalytic degradation mechanism. The photocatalytic activity measured in three subsequent cycles showed good reusability as no significant loss in efficiency of dye degradation was observed.
      Citation: Catalysts
      PubDate: 2018-02-24
      DOI: 10.3390/catal8020093
      Issue No: Vol. 8, No. 2 (2018)
       
 
 
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