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  Subjects -> ENGINEERING (Total: 2270 journals)
    - CHEMICAL ENGINEERING (191 journals)
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    - ENGINEERING (1199 journals)
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ENGINEERING (1199 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Full-text available via subscription   (Followers: 5)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 2)
ACS Nano     Full-text available via subscription   (Followers: 217)
Acta Geotechnica     Hybrid Journal   (Followers: 6)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 2)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 10)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 4)
Advanced Science     Open Access   (Followers: 4)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Artificial Neural Systems     Open Access   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 19)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 40)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 35)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
AIChE Journal     Hybrid Journal   (Followers: 28)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 27)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 23)
Analele Universitatii Ovidius Constanta - Seria Chimie     Open Access  
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 8)
Applied Clay Science     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Network Science     Open Access  
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 3)
Applied Sciences     Open Access   (Followers: 2)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 2)
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 7)
Asian Journal of Control     Hybrid Journal  
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 7)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
Batteries     Open Access   (Followers: 3)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 3)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 9)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 3)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 14)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 40)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 7)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 4)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 252)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 177)
Composites Part B : Engineering     Hybrid Journal   (Followers: 223)
Composites Science and Technology     Hybrid Journal   (Followers: 164)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 12)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 25)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 8)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 25)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 6)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 8)
Control Engineering Practice     Hybrid Journal   (Followers: 41)
Control Theory and Informatics     Open Access   (Followers: 7)
Corrosion Science     Hybrid Journal   (Followers: 24)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  

        1 2 3 4 5 6 | Last

Journal Cover Chinese Journal of Catalysis
  [SJR: 0.6]   [H-I: 29]   [2 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 1872-2067
   Published by Elsevier Homepage  [3031 journals]
  • LSDA+U study on the electronic and anti-ferromagnetic properties of
           Ni-doped CuO and Cu-doped NiO
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Yujie Li, Fan Yang, Ying Yu
      Doping is an effective way to improve the activity of photocatalysts. The effect of doping on the magnetic properties of some photocatalysts that are easily recycled was studied using the local spin density approximation (LSDA)+U method on typical divalent metal oxide semiconductors CuO, NiO, Ni-doped CuO, and Cu-doped NiO. It is found that the influence of Ni doping on the spatial structure of CuO and that of Cu doping on the spatial structure of NiO are negligible because of the similar radii of Ni2+ and Cu2+. The valence band and conduction band for Ni-doped CuO are clearly spin-split, corresponding to a net effective magnetic moment of µ eff = 1.66 µB. This may improve the photocatalytic efficiency and raise the recycle rate of photocatalysts. In the Cu-doped NiO system, the presence of Cu 3d states near to the Fermi level increases the width of the valence band and narrows the band gap with respect to that in pure NiO. Beyond the Cu 3d states, within the band gap, appear two energy levels around the Fermi level, which may effectively separate the electron-hole pair and also lead to enhanced absorption of visible light and infrared light. It can be concluded that the observed changes in the band structure may be helpful for improving the activity of photocatalysts and the doped systems have net magnetic moments, meaning that they are easily recycled and can be reused.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Gold-catalyzed addition reaction between creatinine and isatin: A
           sustainable and green chemistry approach for the diastereoselective
           synthesis of 3-substituted-3-hydroxyisatins
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): K. Parthasarathy, T. Ponpandian, C. Praveen
      The aldolization of various isatins with creatinine under gold catalysis in water has been developed. The reaction is operationally simple as the products can be isolated by simple filtration without requiring tedious solvent extraction and column chromatographic techniques. The generality of this methodology is showcased through the reactions of a wide range of isatin derivatives with creatinine to afford the respective aldol products in excellent yields with complete syn-selectivity. The scope of this chemistry is further extended to a tandem reaction involving isatins, creatinine and malononitrile to afford multicomponent products in excellent yields with complete anti-selectivity. The antioxidant potency of the synthesized compound was assessed by a spectrophotometric method, which revealed that three compounds containing halogen atoms (2c, 2d and 2e) were the most active compared with the standard.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Enantioselective synthesis of quaternary α-aminophosphonates by
           organocatalytic Friedel–Crafts reactions of indoles with cyclic
           α-ketiminophosphonates
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Zhong Yan, Xiang Gao, Yong-Gui Zhou
      An efficient asymmetric Friedel–Crafts reaction has been developed for the synthesis of optically active quaternary α-aminophosphonates with up to 98% ee. The synthesis involves the reaction of cyclic α-ketiminophosphonates with indoles using an H8-BINOL-derived chiral phosphoric acid (CPA) catalyst that bears electron-withdrawing 3,5-ditrifluoromethylphenyl substituents on its 3- and 3′-positions. This Friedel–Crafts reaction of cyclic α-ketiminophosphonates was also successful with pyrrole.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • In-plasma catalytic degradation of toluene over different MnO2 polymorphs
           and study of reaction mechanism
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Ting Wang, Si Chen, Haiqiang Wang, Zhen Liu, Zhongbiao Wu
      α-, β-, γ- and δ-MnO2 catalysts were synthesized by a one-step hydrothermal method, and were utilized for the catalytic oxidation of toluene in a combined plasma-catalytic process. The relationship between catalytic performance and MnO2 crystal structures was investigated. It was noted that the toluene removal efficiency was 32.5% at the specific input energy of 160 J/L when non-thermal plasma was used alone. The α-MnO2 catalyst showed the best activity among the investigated catalysts, yielding a toluene conversion of 78.1% at the specific input energy of 160 J/L. For β-MnO2, γ-MnO2 and δ-MnO2, removal efficiencies of 47.4%, 66.1% and 50.0%, respectively, were achieved. By powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, Brunauer-Emmett-Teller, H2 temperature-programmed reduction and X-ray photoelectron spectroscopy analyses, it was concluded that the tunnel structure, the stability of the crystal in plasma, the Mn–O bond strength of MnO2 and the surface-chemisorbed oxygen species played important roles in the plasma-catalytic degradation of toluene. Additionally, the degradation routes of toluene in non-thermal plasma and in the plasma-catalytic process were also studied. It was concluded that the introduction of MnO2 catalysts enabled O3, O2, electrons and radical species in the gas to be adsorbed on the MnO2 surface via a facile interconversion among the Mn4+, Mn3+ and Mn2+ states. These four species could then be transported to the toluene or intermediate organic by-products, which greatly improved the toluene removal efficiency and decreased the final output of by-products.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Cobalt carbonyl ionic liquids based on the 1,1,3,3-tetra-alkylguanidine
           cation: Novel, highly efficient, and reusable catalysts for the
           carbonylation of epoxides
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Wei Zhang, Feng Han, Jin Tong, Chungu Xia, Jianhua Liu
      A series of novel cobalt carbonyl ionic liquids based on 1,1,3,3-tetra-alkyl-guanidine, such as [1,1-dimethyl-3,3-diethylguanidinium][Co(CO)4] (3a), [1,1-dimethyl-3,3-dibutylguanidinium][Co(CO)4] (3b), [1,1-dimethyl-3,3-tetramethyleneguanidinium][Co(CO)4] (3c), and [1,1-dimethyl-3,3-pentamethyleneguanidinium] [Co(CO)4] (3d), were synthesized in good yields and were also characterized using infrared spectroscopy, ultraviolet-visible spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy, high–resolution mass spectrometry, differential scanning calorimetry, and thermogravimetric analysis. The four compounds exhibited high thermal and chemical stability. In addition, the catalytic performance of these compounds was investigated in the carbonylation of epoxides, with 3a exhibiting the best catalytic activity without the aid of a base as the additive. The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate. Moreover, the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, and chloromethyl functional groups.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Effect of Pd doping on CH4 reactivity over Co3O4 catalysts from
           density-functional theory calculations
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Chengcheng Zhao, Yonghui Zhao, Shenggang Li, Yuhan Sun
      Palladium oxide (PdO x ) and cobalt oxide (Co3O4) are efficient catalysts for methane (CH4) combustion, and Pd-doped Co3O4 catalysts have been found to exhibit better catalytic activities, which suggest synergism between the two components. We carried out first-principles calculations at the PBE+U level to investigate the Pd-doping effect on CH4 reactivity over the Co3O4 catalyst. Because of the structural complexity of the Pd-doped Co3O4 catalyst, we built Pd-doped catalyst models using Co3O4(001) slabs with two different terminations and examined CH4 reactivity over the possible Pd–O active sites. A low energy barrier of 0.68 eV was predicted for CH4 dissociation over the more reactive Pd-doped Co3O4(001) surface, which was much lower than the 0.98 and 0.89 eV that was predicted previously over the more reactive pure Co3O4(001) and (011) surfaces, respectively. Using a simple model, we predicted CH4 reaction rates over the pure Co3O4(001) and (011) surfaces, and Co3O4(001) surfaces with different amounts of Pd dopant. Our theoretical results agree well with the available experimental data, which suggests a strong synergy between the Pd dopant and the Co3O4 catalyst, and leads to a significant increase in CH4 reaction rate.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Facile synthesis of S-doped reduced TiO2-x with enhanced visible-light
           photocatalytic performance
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Zhenyu Huang, Zhenggang Gao, Shanmin Gao, Qingyao Wang, Zeyan Wang, Baibiao Huang, Ying Dai
      A different approach to synthesize visible-light-active sulfur (S)-doped reduced titania (S-TiO2-x ) using thiourea dioxide as both the S source and reductant was developed. The structure, morphology, and optical and electronic properties of the as-prepared S-TiO2-x samples were examined by multiple techniques, such as X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, Brunauer-Emmett-Teller and photocurrent measurements, and electrochemical impedance spectroscopy. The photocatalytic activity of S-TiO2-x was evaluated by photodegradation of organic Rhodamine B under visible-light irradiation. The degradation rate of Rhodamine B by S-TiO2-x obtained by calcination was about 31, 2.5, and 3.6 times higher than those of pure TiO2, pristine TiO2-x , and S-doped TiO2, respectively. In addition, the as-prepared S-TiO2-x exhibited long-term stable photocatalytic performance in the degradation of Rhodamine B under visible-light illumination. This report reveals a new approach to prepare stable and highly efficient solar light-driven photocatalysts for water purification.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Synergetic photo-epoxidation of propylene with molecular oxygen over
           bimetallic Au–Ag/TS-1 photocatalysts
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Naixu Li, Bin Yang, Ming Liu, Yong Chen, Jiancheng Zhou
      Au–Ag bimetallic nanoparticle-supported microporous titanium silicalite-1 catalysts were prepared via a hydrothermal-immersion method, and their structures were examined. These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene. The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide. The optimal formation rate (68.3 μmol/g·h) and selectivity (52.3%) toward propylene oxide were achieved with an Au:Ag mass ratio of 4:1. Notably, the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems. A probable reaction mechanism was proposed based on the theoretical and experimental results.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Performance enhancement mechanism of Mn-based catalysts prepared under N2
           for NOx removal: Evidence of the poor crystallization and oxidation of
           MnOx
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Kai Qi, Junlin Xie, De Fang, Fengxiang Li, Feng He
      Among multitudinous metal-oxide catalysts for the selective catalytic reduction of NO x with NH3 (NH3-SCR), Mn-based catalysts have become very popular and developed rapidly in recent years because of its superior low-temperature denitrification activity, mainly originating from multi-valence of Mn. Most studies suggest that the catalytic activity of multi-component oxides is superior to that of single-component catalysts owing to the synergistic effect among the metallic elements in such materials, of which more attentions have been given to Ce as an additive owing to its powerful oxygen storage capacity, redox ability and its ready availability. As the core of SCR technology, the research points in catalyst development at the present stage of all researchers in countries mainly centralize on the optimization of active components, carriers, calcination temperature, calcination time and temperature-raising procedure, giving little thought to the effects of the calcination atmosphere. In the present work, Ce-modified Mn-based catalysts were prepared by a simple impregnation method. The effects of the calcination atmosphere (N2, air or O2) on the performance of the resulting materials during NH3-SCR and its causes of the differences were subsequently investigated and characterized using various analytical methods. Data obtained from X-ray diffraction, thermogravimetry and temperature-programmed reduction with hydrogen show that calcination under N2 reduces both the degree of oxidation and crystallization of the MnO x . Scanning electron microscopy also demonstrates that the use of N2 inhibits the growth of grains and increases the dispersion of the catalysts. In addition, the results of temperature-programmed desorption with ammonia indicate that catalysts calcined under N2 exhibit a greater quantity of acid sites. Finally, X-ray photoelectron spectrometry and activity results demonstrate that MnO x in the lower valence states is more favorable for NH3-SCR reactions. In conclusion, catalysts calcined under N2 show superior performance during NH3-SCR for NO x removal, allowing NO conversions up to 94% at 473 K.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Brønsted-acidic ionic liquids as efficient catalysts for the synthesis of
           polyoxymethylene dialkyl ethers
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Heyuan Song, Meirong Kang, Fuxiang Jin, Guoqin Wang, Zhen Li, Jing Chen
      Acetalation of formaldehyde (HCHO) with dialkyl formal or aliphatic alcohol to prepare polyoxymethylene dialkyl ethers (RO(CH2O) n R, n ≥ 1) catalyzed by Brønsted-acidic ionic liquids has been developed. The correlation between the structure and acidity activity of various ionic liquids was studied. Among the ionic liquids investigated, 1-(4-sulfonic acid)butyl-3-methylimidazolium hydrogen sulfate ([MIMBs]HSO4) exhibited the best catalytic performance in the reaction of diethoxymethane (DEM1) with trioxane. The influences of ionic liquid loading, molar ratio of DEM1 to HCHO, reaction temperature, pressure, time, and reactant source on the catalytic reaction were explored using [MIMBs]HSO4 as the catalyst. Under the optimal conditions of n([MIMBs]HSO4):n(DEM1):n(HCHO) = 1:80:80, 140 °C, and 4 h, the conversion of HCHO and selectivity for DEM2–8 were 92.6% and 95.1%, respectively. The [MIMBs]HSO4 catalyst could be easily separated and reused. A feasible mechanism for the catalytic performance of [MIMBs]HSO4 was proposed.
      Graphical abstract image

      PubDate: 2017-05-22T08:35:24Z
       
  • Quaternary-ammonium-immobilized polystyrenes as efficient and reusable
           heterogeneous catalysts for synthesis of cyclic carbonate: Effects of
           linking chains and pendent hydroxyl group
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Xiaoming Yan, Xuan Ding, Yu Pan, Xiaowei Xu, Ce Hao, Wenji Zheng, Gaohong He
      Spherical polystyrene-supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions of CO2 and epoxides. The effects of the length of the linking chains and a hydroxyl group pendent on the linking chain on the catalytic performance of ionic liquid immobilized catalysts and their mechanisms were studied through experiments and density functional theory calculations. It was found that, compared with a short linking chain, a long chain can make the halogen anion more negative and provide a larger contact area of the catalysts with the reactants, thus enhancing the reaction kinetics. The hydroxyl group can stretch the C–O bonds of the epoxides, promoting the reaction thermodynamics. As a result, for the cycloaddition of propylene oxide, the yield of propylene carbonate is much higher for the catalyst with a long linking chain (yield: 91.4%) compared with the yield for that with a short chain (yield: 70.9%), and is further increased in the presence of pendent hydroxyl groups (yield: 98.5%). The catalyst also shows a high catalytic activity even at mild temperature and good reusability (yield: ≥ 96% for 10 cycles), and the selectivity is always above 99%.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Synthesis of ZSM-5 monoliths with hierarchical porosity through a
           steam-assisted crystallization method using sponges as scaffolds
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Tiejing Hu, Jian Liu, Changyan Cao, Weiguo Song
      Self-supporting ZSM-5 crystals with hierarchical porosity were prepared through a steam-assisted crystallization method using sponges as rigid scaffolds. The synthesized materials were characterized by X-ray diffraction, nitrogen sorption, scanning electron microscopy, transmission electron microscopy, solid-state nuclear magnetic resonance spectroscopy and ammonia temperature-programmed desorption. The ZSM-5 monoliths exhibited high crystallinities, hierarchical porous structures and strong acidities. They showed superior catalytic performance in the liquid-phase esterification reaction between benzyl alcohol and hexanoic acid.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Synthesis of propylene glycol ethers from propylene oxide catalyzed by
           environmentally friendly ionic liquids
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Cong Zhao, Shengxin Chen, Ruirui Zhang, Zihang Li, Ruixia Liu, Baozeng Ren, Suojiang Zhang
      A series of acetate ionic liquids were synthesized using a typical two-step method. The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions. The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions, obtained using ultraviolet-visible spectroscopy, and the relationship between their catalytic activities and basicities was established. The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH. This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used. A possible electrophilic-nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time-of-flight mass spectrometry. In addition, the effects of significant reaction parameters such as concentration of catalyst, molar ratio of alcohol to propylene oxide, reaction temperature, and steric hindrance of the alcohol were investigated in detail.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Chiral BINAP-based hierarchical porous polymers as platforms for efficient
           heterogeneous asymmetric catalysis
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Tao Wang, Yuan Lyu, Kai Xiong, Wenlong Wang, Hao Zhang, Zhuangping Zhan, Zheng Jiang, Yunjie Ding
      Two vinyl-functionalized chiral 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) ligands, (S)-4,4′-divinyl-BINAP and (S)-5,5′-divinyl-BINAP, were successfully synthesized. Chiral BINAP-based porous organic polymers (POPs), denoted as 4-BINAP@POPs and 5-BINAP@POPs, were efficiently prepared via the copolymerization of vinyl-functionalized BINAP with divinyl benzene under solvothermal conditions. Thorough characterization using nuclear magnetic resonance spectroscopy, thermogravimetric analysis, extended X-ray absorption fine structure analysis, and high-angle annular dark-field scanning transmission electron microscopy, we confirmed that chiral BINAP groups were successfully incorporated into the structure of the materials considered to contain hierarchical pores. Ru was introduced as a catalytic species into the POPs using different synthetic routes. Systematic investigation of the resultant chiral Ru/POP catalysts for heterogeneous asymmetric hydrogenation of β-keto esters revealed their excellent chiral inducibility as well as high activity and stability. Our work thereby paves a path towards the use of advanced hierarchical porous polymers as solid chiral platforms for heterogeneous asymmetric catalysis.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Sr-doping effects on La2O3 catalyst for oxidative coupling of methane
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Linna Cong, Yonghui Zhao, Shenggang Li, Yuhan Sun
      Density-functional theory calculations were carried out to study the strontium (Sr)-doping effect on methane activation over a lanthanum-oxide (La2O3) catalyst for the oxidative coupling of methane (OCM) using the cluster model. Eight Sr-doped La2O3 cluster models were built from pure La2O3 clusters that were used previously to model the La2O3 catalyst. These form two distinct categories, namely, those without a radical character (LaSrO2(OH), La2SrO4, La3SrO5(OH), and La5SrO8(OH)) and those with a radical character (LaSrO3, La2SrO4(OH), La3SrO6, and La5SrO9). The potential-energy surface for CH4 activation to form a CH3 radical at different Sr–O and La–O pair sites on these Sr-doped La2O3 clusters was calculated to study the Sr-doping effect on the OCM catalytic activity. CH4 physisorption and chemisorption energies, and activation barriers, and CH3 desorption energies were predicted. Compared with the pure La2O3 clusters, in general, the Sr-doped La2O3 clusters are thermodynamically and kinetically more reactive with CH4. For the Sr-doped La2O3 clusters without the radical character, the Sr–O pair site is more reactive with CH4 than the La–O pair site, although a direct release of the CH3 radical is also highly endothermic as in the case of the pure La2O3 clusters. In contrast, for the Sr-doped La2O3 clusters with a radical character, the activation of CH4 at the oxygen radical site and the release of the CH3 radical are much easier. Thus, our calculations suggest that the Sr dopant prompts the OCM catalytic activity of the La2O3 catalyst by providing a highly active oxygen-radical site and by strengthening the basicity of the M–O pair site, which leads to lower CH4 activation energies and lower CH3 desorption energies.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Synthesis of isosorbide-based polycarbonates via melt polycondensation
           catalyzed by quaternary ammonium ionic liquids
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Wei Sun, Fei Xu, Weiguo Cheng, Jian Sun, Guoqing Ning, Suojiang Zhang
      A series of quaternary ammonium ionic liquids (ILs) were synthesized and employed as catalysts for the production of poly(isosorbide carbonate) (PIC) from diphenyl carbonate and isosorbide via a melt polycondensation process. The relationship between the anions of the ILs and the catalytic activities was investigated, and the readily-prepared IL tetraethylammonium imidazolate (TEAI) was found to exhibit the highest catalytic activity. After optimizing the reaction conditions, a PIC with a weight-average molecular weight (M w) of 25600 g/mol was obtained, in conjunction with an isosorbide conversion of 92%. As a means of modifying the molecular flexibility and thermal properties of the PIC, poly(aliphatic diol-co-isosorbide carbonate)s (PAIC)s were successfully synthesized, again using TEAI, and polymers with M w values ranging from 29000 to 112000 g/mol were obtained. 13C NMR analyses determined that the PAIC specimens had random microstructures, while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from 50 to 115 °C. Thermogravimetric analyses found T d-5% values ranging from 316 to 332 °C for these polymers. Based on these data, it is evident that the incorporation of linear or cyclohexane-based diol repeating units changed the thermal properties of the PIC.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Investigation of low-temperature hydrothermal stability of Cu-SAPO-34 for
           selective catalytic reduction of NOx with NH3
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Xiao Xiang, Pengfei Wu, Yi Cao, Lei Cao, Quanyi Wang, Shutao Xu, Peng Tian, Zhongmin Liu
      The low-temperature hydrothermal stabilities of Cu-SAPO-34 samples with various Si contents and Cu loadings were systematically investigated. The NH3 oxidation activities and NH3-selective catalytic reduction (SCR) activities (mainly the low-temperature activities) of all the Cu-SAPO-34 catalysts declined after low-temperature steam treatment (LTST). These results show that the texture and acid density of Cu-SAPO-34 can be better preserved by increasing the Cu loading, although the hydrolysis of Si–O–Al bonds is inevitable. The stability of Cu ions and the stability of the SAPO framework were positively correlated at relatively low Cu loadings. However, a high Cu loading (e.g., 3.67 wt%) resulted in a significant decrease in the number of isolated Cu ions. Aggregation of CuO particles also occurred during the LTST, which accounts for the decreasing NH3 oxidation activities of the catalysts. Among the catalysts, Cu-SAPO-34 with a high Si content and medium Cu content (1.37 wt%) showed the lowest decrease in NH3-SCR because its Cu2+ content was well retained and its acid density was well preserved.
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      PubDate: 2017-05-22T08:35:24Z
       
  • One-step synthesis of pyruvic acid from glycerol oxidation over Pb
           promoted Pt/activated carbon catalysts
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Chen Zhang, Tao Wang, Yunjie Ding
      One-step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon (Pb-Pt/AC) catalysts under mild conditions. The results of N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy revealed that the alloy phases of PtPb and Pt x Pb were favorable for pyruvic acid production from glycerol oxidation, whereas the Pb3(CO3)2(OH)2 and surface Pb0 species inhibited the glycerol conversion. The loading of Pb and the catalyst preparation method (including impregnation and deposition precipitation) affected the formation of different metal species. Pyruvic acid was obtained at a yield of 18.4% on a 5.0 wt% Pb-5.0 wt% Pt/AC catalyst prepared by co-deposition precipitation method and 500 °C argon treatment.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Enhancement of the formic acid electrooxidation activity of palladium
           using graphene/carbon black binary carbon supports
    • Abstract: Publication date: May 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 5
      Author(s): Meiying Lv, Wenpeng Li, Huiling Liu, Wenjuan Wen, Guang Dong, Jinghua Liu, Kaichen Peng
      Combinations of graphene (Gr) and carbon black (C) were employed as binary carbon supports to fabricate Pd-based electrocatalysts via one-pot co-reduction with Pd2+. The electrocatalytic performance of the resulting Pd/Gr-C catalysts during the electrooxidation of formic acid was assessed. A Pd/Gr0.3C0.7 (Gr oxide:C = 3:7, based on the precursor mass ratio) electrocatalyst exhibited better catalytic performance than both Pd/C and Pd/Gr catalysts. The current density generated by the Pd/Gr0.3C0.7 catalyst was as high as 102.14 mA mgPd −1, a value that is approximately 3 times that obtained from the Pd/C (34.40 mA mgPd −1) and 2.6 times that of the Pd/Gr material (38.50 mA mgPd −1). The anodic peak potential of the Pd/Gr0.3C0.7 was 120 mV more negative than that of the Pd/C and 70 mV more negative than that of the Pd/Gr. Scanning electron microscopy images indicated that the spherical C particles accumulated on the wrinkled graphene surfaces to form C cluster/Gr hybrids having three-dimensional nanostructures. X-ray photoelectron spectroscopy data confirmed the interaction between the Pd metal and the binary Gr-C support. The Pd/Gr0.3C0.7 also exhibited high stability, and so is a promising candidate for the fabrication of anodes for direct formic acid fuel cells. This work demonstrates a simple and cost-effective method for improving the performance of Pd-based electrocatalysts, which should have potential industrial applications.
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      PubDate: 2017-05-22T08:35:24Z
       
  • Engineering vacancies for solar photocatalytic applications
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Mingce Long, Longhui Zheng
      In contrast to the exploration of novel photocatalytic materials, vacancy engineering of traditional photocatalysts comprising earth-abundant elements represents an effective method for enhancing photocatalytic performance without introducing alien elements. This minireview analyzes the latest progress in engineering vacancies in photocatalysts, remarks on state-of-the-art characterization techniques for vacancies, and reviews the formation chemistry and fundamental benefits of anion and cation vacancies in typical photocatalysts. Although knowledge of these vacancies is increasing, challenges remain in this field, and possible further research is therefore also discussed.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Selective aerobic oxidation promoted by highly efficient multi-nitroxy
           organocatalysts
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Kexian Chen, Haiying Xie
      Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucial importance for the long-term sustainable exploitation of available feedstocks and the formation of required intermediates for organic synthesis and industrial processes. Among the developed oxidation protocols, innovative strategies using hydroxyimide organocatalysts in combination with metallic or metal-free cocatalysts have attracted much attention because of the good activities and selectivities of such catalysts in the oxo functionalization of hydrocarbons. This method is based on the reaction using N-hydroxyphthalimide, which was first reported by Ishii's group in the 1990s. Although the important and wide-ranging applications of such catalysts have been summarized recently, there are no reviews that focus solely on oxidation strategies using multi-nitroxy organocatalysts, which have interesting properties and high reactivities. This review covers the concise synthetic methods and mechanistic profiles of known multi-nitroxy organocatalysts and summarizes significant advances in their use in efficient aerobic oxidation. Based on a combination of experimental and theoretical results, guidelines for the future rational design of multi-nitroxy organocatalysts are proposed, and the properties of various model multi-nitroxy organocatalysts are predicted. The present overview of the advantages, limitations, and potential applications of multi-nitroxy organocatalysts can provide useful tools for researchers in the field of selective oxidation.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Supercritical synthesis of platinum-modified titanium dioxide for solar
           fuel production from carbon dioxide
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Susana Tostón, Rafael Camarillo, Fabiola Martínez, Carlos Jiménez, Jesusa Rincón
      This paper investigates the properties of TiO2-based photocatalysts synthesised under supercritical conditions. Specifically, the characteristics of Pt dispersed on TiO2 catalysts obtained in supercritical CO2 are discussed and compared with those of commercial TiO2. The photocatalytic activity of the synthesised catalysts in the CO2 photoreduction reaction to produce solar fuel is tested. The main conclusion of the study is that photocatalysts with better or similar features, including high surface area, crystallisation degree, hydroxyl surface concentration, pore volume, absorbance in the visible range and methane production rate, to those of commercial TiO2 may be produced for the reduction of CO2 to fuel by synthesis in supercritical media.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Simple synthesis of sub-nanometer Pd clusters: High catalytic activity of
           Pd/PEG-PNIPAM in Suzuki reaction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Zhe Chen, Yu Liang, Da-Shuang Jia, Zhi-Min Cui, Wei-Guo Song
      Ultra-small metal nanoclusters have high surface energy and abundant active sites, and therefore their catalytic activities are usually significantly higher than those of larger nanoparticles. A temperature-responsive copolymer, namely poly(ethylene glycol)-co-poly(N-isopropylacrylamide) (PEG-PNIPAM) was synthesized as the first step, and then ultra-small Pd clusters stabilized within PEG-PNIPAM copolymer micelles were formed by direct reduction. Pd nanoclusters of size less than 2 nm showed outstanding catalytic activity in the Suzuki coupling reaction. The reaction between iodobenzene and phenylboronic acid was completed in as little as 10 s (turnover frequency = 4.3 × 104 h−1). A yield of 64% was achieved in 5 min in the reaction between chlorobenzene and phenylboronic acid. The catalyst showed significant deactivation during three consecutive runs. However, this composite catalyst consisting of Pd/PEG-PNIPAM can be easily recycled based on the reversible phase transition of temperature-responsive PEG-PNIPAM. This catalyst therefore has good potential for practical applications.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Cu2O/SiC as efficient catalyst for Ullmann coupling of phenols with aryl
           halides
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Yibing Wang, Xiaoning Guo, Manqian Lü, Zhaoyang Zhai, Yingyong Wang, Xiangyun Guo
      A Cu2O/SiC heterogeneous catalyst was prepared via a two-step liquid-phase method using diethylene glycol as both the solvent and the reducing agent. The catalyst was characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and H2 temperature-programmed reduction. All the results indicate that Cu is present on the SiC support primarily as Cu2O. The SEM and TEM results show that cubic Cu2O nanoparticles are uniformly dispersed on the β-SiC surface. The reaction conditions, namely the temperature, reaction time, and amounts of base and catalyst used, for the Ullmann-type C–O cross-coupling reaction were optimized. A model reaction was performed using iodobenzene (14.0 mmol) and phenol (14.0 mmol) with Cu2O/SiC (5 wt% Cu) as the catalyst, Cs2CO3 (1.0 equiv.) as the base, and tetrahydrofuran as the solvent at 150 °C for 3 h; a yield of 97% was obtained and the turnover frequency (TOF) was 1136 h−1. The Cu2O/SiC catalyst has a broad substrate scope and can be used in Ullmann-type C–O cross-coupling reactions of aryl halides and phenols bearing a variety of different substituents. The catalyst also showed high activity in the Ullmann-type C–S cross-coupling of thiophenol with iodobenzene and substituted iodobenzenes; a TOF of 1186 h−1 was achieved. The recyclability of the Cu2O/SiC catalyst in the O-arylation of phenol with iodobenzene was investigated under the optimum conditions. The yield decreased from 97% to 64% after five cycles. The main reason for the decrease in the catalyst activity is loss of the active component, i.e., Cu2O.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Purification and characterization of alkaline chitinase from Paenibacillus
           pasadenensis CS0611
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Xiaoxiao Guo, Pei Xu, Minhua Zong, Wenyong Lou
      An extracellular chitinase produced by Paenibacillus pasadenensis CS0611 was purified by ammonium sulfate precipitation, HiTrap DEAE FF and HiLoad 26/600 Superdex 200pg column chromatography. The apparent molecular mass determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 69 kDa. The optimum pH and optimum temperature of the chitinase were 5.0 and 50 °C, respectively. The enzyme showed high stability at alkaline pH values and temperatures below 40 °C. Additionally, the metal ions Mn2+, Mg2+, and Co2+ inhibited activity of the chitinase. The chitinase was active on colloidal chitin with an apparent K m of 4.41 mg/mL and V max of 1.08 mg/min. Substrate spectrum analysis indicated that the chitinase reacted preferentially with the glucosidic bond between GlcNAc-GlcNAc. The enzymatic hydrolysate was analyzed by high-performance liquid chromatography and thin layer chromatography, and clearly showed that a subunit of (GlcNAc)2 was the main hydrolysis product.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Fe, N, S-doped porous carbon as oxygen reduction reaction catalyst in
           acidic medium with high activity and durability synthesized using CaCl2 as
           template
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Chi Chen, Zhiyou Zhou, Yucheng Wang, Xue Zhang, Xiaodong Yang, Xinsheng Zhang, Shigang Sun
      Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of Pt catalysts. In the present work, a high-performance ORR catalyst based on Fe, N, S-doped porous carbon (FeNS-PC) was synthesized using melamine formaldehyde resin as C and N precursors, Fe(SCN)3 as Fe and S precursors, and CaCl2 as a template via a two-step heat treatment without a harsh template removal step. The results show that the catalyst treated at 900 °C (FeNS-PC-900) had a high surface area of 775 m2/g, a high mass activity of 10.2 A/g in an acidic medium, and excellent durability; the half-wave potential decreased by only 20 mV after 10000 potential cycles. The FeNS-PC-900 catalyst was used as the cathode in a proton exchange membrane fuel cell and delivered a peak power density of 0.49 W/cm2. FeNS-PC-900 therefore has good potential for use in practical applications.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Correlation between H-ZSM-5 crystal size and catalytic performance in the
           methanol-to-aromatics reaction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Lingzhi Yang, Zhiyuan Liu, Zhi Liu, Wenyong Peng, Yunqi Liu, Chenguang Liu
      The porosity of H-ZSM-5 zeolite is known to facilitate the diffusion of molecules in the methanol-to-aromatics (MTA) reaction. The activity and selectivity of the H-ZSM-5 catalyst in the MTA reaction has been studied as a function of crystal size. ZSM-5 zeolites with different crystal sizes were successfully synthesized by conventional hydrothermal methods. Tailoring ZSM-5 particle size was easily controlled by changes to the sol-gel composition, and in particular, the deionized water to tetrapropylammonium hydroxide ratio, and crystallization time. The structure of the H-ZSM-5 zeolites were characterized by X-ray diffraction and the morphology of the zeolite particles was determined by scanning electron microscopy. N2 adsorption-desorption measurements established changes to the textural properties, and compositional properties were characterized by X-ray fluorescence spectroscopy. Acidity measurements of the catalysts were measured by pyridine-adsorbed Fourier transform infrared spectroscopy and the temperature-programmed desorption of ammonia. After subjecting the catalysts to the MTA reaction, the total amount of coke formed on the spent deactivated catalysts was determined by thermal gravimetric analysis. The results show that the SiO2/Al2O3 molar ratios and acidic properties of the H-ZSM-5 samples are similar, however, the nano-sized hierarchical ZSM-5 zeolite with an additional level of auxiliary pores possesses a higher surface area, larger mesopore volume and larger macropore volume, resulting in more effective mass transportation properties. The H-ZSM-5 zeolite catalysts were evaluated for their activity towards the MTA reaction as a function of crystal size. The nano-sized H-ZSM-5 catalyst having shorter diffusion path lengths, substantial mesoporosity and a high external surface area showed excellent selectivity toward aromatics (average > 42%) and benzene, toluene and xylenes (37% at 180 min). Furthermore, lower coking levels were observed on the nano-sized H-ZSM-5 catalyst when compared with the H-ZSM-5 catalysts possessing larger particle sizes and is attributed to a reduction in polyaromatic hydrocarbons being deposited within the internal surface area.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Porous Rh/BINAP polymers as efficient heterogeneous catalysts for
           asymmetric hydroformylation of styrene: Enhanced enantioselectivity
           realized by flexible chiral nanopockets
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Tao Wang, Wenlong Wang, Yuan Lyu, Kai Xiong, Cunyao Li, Hao Zhang, Zhuangping Zhan, Zheng Jiang, Yunjie Ding
      A new chiral monomer, (S)-5,5′-divinyl-BINAP, was successfully synthesized and embedded into two different porous organic polymers (Poly-1 and Poly-2). After loading a Rh species, the catalysts were applied for the heterogeneous asymmetric hydroformylation of styrene. Compared with the homogeneous BINAP analogue, the enantioselectivity of Rh/Poly-1 catalyst was drastically increased by approximately 70%. The improved enantioselectivity of the porous Rh/BINAP polymers was attributed to the presence of flexible chiral nanopockets resulting from the increased bulk of the R groups near the catalytic center.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Influence of supports for selective production of 2,5-dimethylfuran via
           
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Sanjay Srivastava, G.C. Jadeja, Jigisha Parikh
      The hydrogenolysis of carbon–oxygen bonds is an important model reaction in upgrading biomass-derived furanic compounds to transportation fuels. One of these model reactions, namely conversion of 5-hydroxymethylfurfural (HMF) to the gasoline additive 2,5-dimethylfuran (DMF), is especially attractive. In this study, bimetallic Cu-Co catalysts supported on CeO2, ZrO2, and Al2O3 were used for the selective hydrogenolysis of HMF to DMF. The structures of the fresh and used catalysts were studied using X-ray diffraction, the Brunauer-Emmett-Teller method, transmission electron microscopy, temperature-programmed reduction by H2, temperature-programmed desorption of NH3, and CHNS analysis. The structures were correlated with the catalytic activities. The Cu-Co/CeO2 catalyst produced mainly 2,5-bis(hydroxymethyl)furan via reduction of C=O bonds on large Cu particles. The Cu-Co/Al2O3 catalyst gave the best selectivity for DMF, as a result of a combination of highly dispersed Cu, mixed copper–cobalt oxides, and suitable weak acidic sites. Cu-Co/ZrO2 had low selectivity for DMF and produced a combination of various over-hydrogenolysis products, including 2,5-dimethyltetrahydrofuran and 5,5-oxybis(methylene)-bis(2-methylfuran), because of the presence of strong acidic sites. The reaction pathways and effects of various operating parameters, namely temperature, H2 pressure, and time, were studied to enable optimization of the selective conversion of HMF to DMF over the Cu-Co/Al2O3 catalyst.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Synthesis, characterization and application of BiVO4 photoanode for
           photoelectrochemical oxidation of chlorate
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Seyed Ghorban Hosseini, Saeid Safshekan
      A high-quality polycrystalline bismuth vanadate (BiVO4) film was prepared on a fluorine-doped tin oxide substrate via a facile two-step strategy involving electrodeposition and annealing processes. The morphology and structural characterization of the resulting film were investigated by different methods including scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared, ultraviolet-visible (UV-vis) absorption, and Raman spectroscopies. XRD patterns as well as optical measurements revealed that BiVO4 film crystallized with a pure monoclinic scheelite structure. The prepared BiVO4 film was used for heterogeneous oxidation of chlorate ions in aqueous solution via electrochemical (EC), photochemical (PC), and photoelectrochemical (PEC) processes. The decrease in concentration of chlorate was monitored using UV-vis absorption spectroscopy. The results revealed that BiVO4 could effectively perform chlorate oxidation under light irradiation through a PEC method. The kinetics of chlorate oxidation was consistent with a first-order reaction, and the rate constant for the PEC process was found to be much higher than those of EC and PC. Furthermore, a possible photocatalytic oxidation mechanism for chlorate mainly based on the formation of perchlorate ions is proposed.
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      PubDate: 2017-04-24T03:30:11Z
       
  • CO2 hydrogenation to methanol over Cu/Zn/Al/Zr catalysts prepared by
           liquid reduction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Xiaosu Dong, Feng Li, Ning Zhao, Yisheng Tan, Junwei Wang, Fukui Xiao
      Cu/Zn/Al/Zr catalysts containing Cu in three valence states (Cu2+, Cu+ and Cu0) were prepared using a liquid reduction method and subsequently calcined at different temperatures. The effects of the calcination temperature on the catalyst structure, interactions among components, reducibility and dispersion of Cu species, surface properties and exposed Cu surface area were systematically investigated. These materials were also applied to the synthesis of methanol via the hydrogenation of CO2. The results show that a large exposed Cu surface area promotes catalytic CO2 conversion and that there is a close correlation between the Cu+/Cu0 ratio and the selectivity for methanol. A calcination temperature of 573 K was found to produce a Cu/Zn/Al/Zr catalyst exhibiting the maximum activity during the synthesis of methanol.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Ordered mesoporous Sn-SBA-15 as support for Pt catalyst with enhanced
           performance in propane dehydrogenation
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Bing Li, Zhenxin Xu, Wei Chu, Shizhong Luo, Fangli Jing
      A series of Sn-incorporated SBA-15 materials with high specific surface areas and highly ordered mesoporous structures were synthesized by a facile one-pot method and used as catalyst supports. A reference sample was also prepared using a conventional impregnation method. The catalysts were characterized using various methods, and their activities in propane dehydrogenation were investigated. The incorporation of Sn into the SBA-15 matrix led to strong interactions between Sn species and the support, and these helped to maintain the oxidation states of Sn species during the reaction. Substitution with Sn changed the interfacial properties of the Pt species and improved the function and effect of the Sn promoter. The catalytic activities and stabilities of the Pt catalysts supported on Sn-incorporated SBA-15 were better than those of the impregnated sample. However, the catalytic performance deteriorated when an excessive amount of Sn was introduced and the interactions among Pt, Sn species, and the support became weaker. The Pt/0.5Sn-SBA-15 catalyst gave the best propene selectivity, i.e., 98.5%, with a corresponding propane conversion of about 43.8%.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Transformation of carbon dioxide into valuable chemicals over bifunctional
           metallosalen catalysts bearing quaternary phosphonium salts
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Wuying Zhang, Rongchang Luo, Qihang Xu, Yaju Chen, Xiaowei Lin, Xiantai Zhou, Hongbing Ji
      The chemical transformation of CO2 under mild conditions remains a great challenge because of its exceptional kinetic and thermodynamic stability. Two important reactions in the transformation of CO2 are the N-formylation reaction of amines using hydrosilanes and CO2, and the cycloaddition of CO2 to epoxides. Here, we report the high efficiency of bifunctional metallosalen complexes bearing quaternary phosphonium salts in catalyzing both of these reactions under solvent-free, mild conditions without the need for co-catalysts. The catalysts' bifunctionality is attributed to an intramolecular cooperative process between the metal center and the halogen anion. Depending on the reaction, this activates CO2 by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond (M–H) or the dual activation of epoxide via metal–oxygen coordinative bond (M–O). The one-component catalysts are also shown to be easily recovered and reused five times without significant loss of activity or selectivity. The current results are combined with previous work in the area to propose the relevant reaction mechanisms.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Nanoscale graphene oxide sheets as highly efficient carbocatalysts in
           green oxidation of benzylic alcohols and aromatic aldehydes
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Alireza Sedrpoushan, Masoud Heidari, Omid Akhavan
      Nanoscale graphene oxide (NGO) sheets were synthesized and used as carbocatalysts for effective oxidation of benzylic alcohols and aromatic aldehydes. For oxidation of alcohols in the presence of H2O2 at 80 °C, the NGOs (20% mass fraction) as carbocatalysts showed selectivity toward aldehyde. The rate and yield of this reaction strongly depended on the nature of substituents on the alcohol. For 4-nitrobenzyl alcohol, <10% of it was converted into the corresponding carboxylic acid after 24 h. By contrast, 4-methoxybenzyl alcohol and diphenylmethanol were completely converted into the corresponding carboxylic acid and ketone after only 9 and 3 h, respectively. The conversion rates for oxidation of aromatic aldehydes by NGO carbocatalysts were higher than those for alcohol oxidation. For all the aldehydes, complete conversion to the corresponding carboxylic acids was achieved using 7% (mass fraction) of NGO at 70 °C within 2–3 h. Possible mechanisms for NGO carbocatalyst structure-dependent oxidation of benzyl alcohols and structure-independent oxidation of aromatic aldehydes are discussed.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Zirconium triflate grafted on SBA-15 as a highly efficient solid acid
           catalyst for ring opening of epoxides by amines and alcohols
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Kamlesh N. Tayade, Lianyue Wang, Sensen Shang, Wen Dai, Manish Mishra, Shuang Gao
      Metal (Al, Ti, Zr) triflate grafted mesoporous SBA-15 (AlTf/S, TiTf/S, ZrTf/S) samples were synthesized as inexpensive solid acid materials by a simple one-pot-two-step synthesis methodology. These materials were characterized by X-ray diffraction, N2-sorption, thermogravimetric analysis, Fourier transform infrared spectroscopy (FT-IR), in-situ pyridine FT-IR spectroscopy, and elemental analysis. ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening of epoxides with amines and alcohols and produced β-amino alcohols and β-alkoxy alcohols respectively under ambient reaction conditions. The ZrTf/S catalyst showed the highest activity, which was attributed to its high acidity compared with that of the Ti and Al containing samples.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Preface to Special Column on Novel Catalysts for Energy and Environmental
           Issues
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Atsushi Fukuoka


      PubDate: 2017-04-10T02:08:53Z
       
  • Conversion of glycerol to acrolein by mesoporous sulfated zirconia-silica
           catalyst
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Hirokazu Kobayashi, Shogo Ito, Kenji Hara, Atsushi Fukuoka
      A mesoporous sulfated zirconia-silica catalyst bearing only Brønsted acid sites converted glycerol to acrolein in 81% yield with 82% selectivity. Space time yield as high as 9.0 mmol h−1 gcat −1 was achieved even at a low reaction temperature of 523 K. The catalytic activity and selectivity were higher than those of typical sulfated zirconia. It is proposed that the milder acidity due to dilution of zirconium species by silica and large pore size for faster diffusion contributed towards the better catalytic performance.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Preparation of Sn-β-zeolite via immobilization of Sn/choline chloride
           complex for glucose-fructose isomerization reaction
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Asep Bayu, Surachai Karnjanakom, Katsuki Kusakabe, Abuliti Abudula, Guoqing Guan
      Well dispersion of tin species in an isolated form is a quite challenge since tin salts are easily hydrolyzed into (hydr)oxides during aqueous stannation of β-zeolite. In this study, immobilization of tin species on high silica commercial β-zeolite by using SnCl2/Choline chloride (ChCl) complex followed with calcination provided a convenient way to get well dispersed Sn in β-zeolite in the aqueous condition, which was observed based on electron microscopy images, UV visible spectra and X-ray diffraction pattern. The existence of ChCl facilitated tin species to incorporate into zeolite. (1−2) wt% of Sn loaded β-zeolites exhibited good catalytic activity and high selectivity for glucose-fructose isomerization reaction.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Reductive transformation of CO2: Fluoride-catalyzed reactions with waste
           silicon-based reducing agents
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Ken Motokura, Masaki Naijo, Sho Yamaguchi, Akimitsu Miyaji, Toshihide Baba
      CO2 is one of the most important “renewable” carbon sources. To transform CO2 to useful organic compounds, we examined the reactivity of two model silicon-based “waste” materials, disilanes and metallic Si powder, as reducing agents. In these reactions, fluoride salts were found to be active catalysts: CO2 was converted to formic acid at atmospheric pressure in the presence of H2O as a proton source and the silicon-based reducing reagents. Based on in-situ NMR and kinetics analyses, a hydrosilane and penta-coordinate Si species are proposed as the reaction intermediate and active species, respectively.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Photocatalytic aerobic oxidation of toluene and its derivatives to
           aldehydes on Pd/Bi2WO6
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Bo Yuan, Bao Zhang, Zhiliang Wang, Shengmei Lu, Jun Li, Yan Liu, Can Li
      The selective oxidation of toluene and its derivatives is extremely important in the chemical industry. The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its “green” environmental characteristics. In this study, nanoscale Bi2WO6 with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O2 as the oxidant. The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi2WO6 was found to produce a significant enhancement in the catalytic activity. Mechanistic investigation showed that the superior performance of Pd/Bi2WO6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi2WO6 by the loading of the cocatalyst.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Preparation and characterization of ternary magnetic g-C3N4 composite
           photocatalysts for removal of tetracycline under visible light
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Xu Tang, Liang Ni, Juan Han, Yun Wang
      A stable PNIPAM/Fe3O4/g-C3N4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology. The structure and properties of the materials were characterized and the composite photocatalyst was found to show good stability for tetracycline degradation. The sample not only retained the magnetic properties of Fe3O4, allowing it to be recycled, but its photocatalytic properties could also be changed by controlling the temperature of the reaction system. The degradation intermediate products of tetracycline were further investigated by MS. This work provides a new facile strategy for the development of intelligent and recyclable photocatalytic materials.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Synthesis and characterization of PMoV/Fe3O4/g-C3N4 from melamine: An
           industrial green nanocatalyst for deep oxidative desulfurization
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Ezzat Rafiee, Maryam Khodayari
      A facile approach to the preparation of a novel magnetically separable H5PMo10V2O40/Fe3O4/g-C3N4 (PMoV/Fe3O4/g-C3N4) nanocomposite by chemical impregnation is demonstrated. The prepared nanocomposite was characterized and its acidity was measured by potentiometric titration. PMoV/Fe3O4/g-C3N4 showed high catalytic activity in the selective oxidative desulfurization of sulfides to their corresponding sulfoxides or sulfones. The catalytic oxidation of a dibenzothiophene (DBT)-containing model oil and that of real oil were also studied under optimized conditions. In addition, the effects of various nitrogen compounds, as well as the use of one- and two-ring aromatic hydrocarbons as co-solvents, on the catalytic removal of sulfur from DBT were investigated. The catalyst was easily separated and could be recovered from the reaction mixture by using an external magnetic field. Additionally, the remaining reactants could be separated from the products by simple decantation if an appropriate solvent was chosen for the extraction. The advantages of this nanocatalyst are its high catalytic activity and reusability; it can be used at least four times without considerable loss of activity.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Synthesis of biaryls using palladium nanoparticles immobilized on peptide
           nanofibers as catalyst and hydroxybenzotriazole as novel phenylating
           reagent
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Arash Ghorbani-Choghamarani, Zahra Taherinia
      Peptide nanofibers decorated with palladium nanoparticles catalyzed direct coupling of aryl halides with hydroxybenzotriazole to afford the corresponding biaryls in good to excellent yields. The coupling reactions proceeded under simple, green, and mild conditions. The peptide nanofibers were used as recyclable supports in the coupling reactions. This approach is the first to use hydroxybenzotriazole as a phenylating agent.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Pt-CeO2/SiO2 catalyst for CO oxidation in humid air at ambient temperature
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Shirish S. Punde, Bruce J. Tatarchuk
      CO self-poisoning and slow surface kinetics pose major challenges to a CO oxidation catalyst that should work at ambient temperature. Furthermore, the presence of moisture would cause passivation of the catalyst. A highly active ceria promoted Pt catalyst (4%Pt-12%CeO2/SiO2; conversion ≥ 99% at low (< 500 ppm) and high (> 2500 ppm) CO concentrations was developed for CO oxidation at ambient temperature in humid air. Catalyst preparation variables such as Pt and CeO2 loading, ceria deposition method, drying and calcination conditions for the ceria and Pt precursors were optimized experimentally. The activity was correlated with surface properties using CO/H2 chemisorption, O2-H2 titration, X-ray diffraction and BET surface area analysis. The method of CeO2 deposition had a significant impact on the catalytic activity. CeO2 deposition by impregnation resulted in a catalyst that was three times more active than that prepared by deposition precipitation or CeO2 grafting. O2-H2 titration results revealed that the close association of ceria and Pt in the case of CeO2 deposition by impregnation resulted in higher activity. The catalyst support used was also crucial as a silica supported catalyst was five times more active than an alumina supported catalyst. The particle size and pore structure of the catalyst support were also crucial as the reaction was diffusion controlled. The drying and calcination conditions of the ceria and Pt precursors also played a crucial role in determining the catalytic activity. The Pt-CeO2/SiO2 catalysts with Pt > 2.5 wt% and CeO2 > 15 wt% were highly active (TOF > 0.02 s−1) and stable (conversion ≥ 99% after 15 h) at ambient conditions.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Surface treatment effect on the photocatalytic hydrogen generation of
           CdS/ZnS core-shell microstructures
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Jinzhan Su, Tao Zhang, Lu Wang, Jinwen Shi, Yubin Chen
      CdS/ZnS core-shell microparticles were prepared by a simple two-step method combining ultrasonic spray pyrolysis and chemical bath deposition. The core-shell structures showed enhanced photocatalytic properties compared with those of CdS or ZnS spherical particles. CdS/ZnS photocatalysts with different amount of ZnS loaded as shells were prepared by adjusting the concentrations of Zn and S precursors during synthesis. The optical properties and photocatalytic activity for hydrogen production were investigated and the amount of ZnS loaded as shell was optimized. Thermal annealing and hydrothermal sulfurization treatments were applied to the core-shell structure and both treatments enhanced the material's photocatalytic activity and stability by eliminating crystalline defects and surface states. The result showed that thermal annealing treatment improved the bulk crystallinity and hydrothermal sulfurization improved the surface properties. The sample subjected to both treatments showed the highest photocatalytic activity. These results indicate that CdS/ZnS core-shell microspheres are a simple structure that can be used as efficient photocatalysts. The hydrothermal sulfurization treatment may also be a useful surface treatment for metal sulfide photocatalysts. The simple two-step method provides a promising approach to the large-scale synthesis of core-shell microsphere catalysts.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Fabrication of porous g-C3N4 and supported porous g-C3N4 by a simple
           precursor pretreatment strategy and their efficient visible-light
           photocatalytic activity
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Zhenxing Zeng, Kexin Li, Kai Wei, Yuhua Dai, Liushui Yan, Huiqin Guo, Xubiao Luo
      Porous g-C3N4 and supported porous g-C3N4 were fabricated for the first time by a simple strategy using pretreated melamine as a raw material and pretreated quartz rod as a substrate. The formation of a richly porous microstructure can be attributed to the co-existence of different pore-fabricating units in the preparation system for porous g-C3N4. The richly porous microstructure endowed the as-prepared porous g-C3N4 with an excellent photocatalytic activity. The as-prepared supported porous g-C3N4 exhibited considerable stability because of the existence of chemical interaction between porous g-C3N4 and the quartz rod substrate. The photocatalytic activity of the supported porous g-C3N4 was competitive with that of porous g-C3N4 in powder form because neither the surface migration of photogenerated electrons nor the diffusion of the target organic pollutant were affected by the construction of the quartz rod reactor. The photocatalytic activity of the as-prepared porous g-C3N4 and supported porous g-C3N4 was preliminarily evaluated by the treatment of single-component organic wastewater under visible-light irradiation. Subsequently, the as-prepared porous g-C3N4 was further applied in conventional hydrogen evolution and a new system for simultaneous hydrogen evolution with organic-pollutant degradation. The hydrogen yield and degradation efficiency both increased with increasing photocatalytic activity of the as-prepared materials in the system for simultaneous hydrogen evolution with organic-pollutant degradation.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Zinc-modified Pt/SAPO-11 for improving the isomerization selectivity to
           dibranched alkanes
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Zhichao Yang, Yunqi Liu, Jinchong Zhao, Jianxia Gou, Kaian Sun, Chenguang Liu
      Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n-octane. Their physicochemical properties were investigated using powder X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption, pyridine-adsorbed infrared spectroscopy, temperature-programmed desorption of NH3, temperature-programmed reduction of hydrogen, temperature-programmed desorption of hydrogen, transmission electron microscopy, and X-ray photoelectron spectroscopy. The addition of zinc resulted in high dispersion of platinum. Zinc acted as a competitive adsorbent, changed the location of platinum. The catalyst with a zinc loading of 0.5% gave the highest selectivity to dimethylhexanes, but the conversion was lower than those achieved with the other catalysts. Dimethylhexanes have large molecular diameters, and therefore their diffusion may be difficult. This weakens the catalytic activity of the zinc-modified catalysts and lowers the n-octane conversion.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • One-pot synthesis of ordered mesoporous Cu-KIT-6 and its improved
           catalytic behavior for the epoxidation of styrene: Effects of the pH value
           of the initial gel
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Baitao Li, Xin Luo, Jing Huang, Xiujun Wang, Zhenxing Liang
      The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6 (Cu-KIT-6 x ) prepared via pH adjustment (where x is the pH: 1.43, 2.27, 3.78, 3.97, 4.24 or 6.62). Variations in the catalyst structure and morphology with pH values were characterized by X-ray power diffraction, nitrogen adsorption-desorption analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. As the pH value applied during the initial synthesis, the resulting Cu-KIT-6 x exhibited different structural, textural and surface characteristics, especially in terms of specific copper species and copper content. At a pH value of 3.78, approximately 4.6 wt% copper(II) was successfully incorporated into the framework of the initial KIT-6, in the form of –Cu–O–Si– groups. The catalytic performance of each catalyst was evaluated by following the epoxidation of styrene, employing tert-butyl hydroperoxide as the oxidant and CH3CN as the solvent. A significant styrene conversion of 43.5% with 86.6% selectivity for the desired styrene epoxide was obtained over the Cu-KIT-63.78. A higher Cu content, an ordered cubic Ia3d mesoporous architecture and various specific textural characteristics all combined to endow the Cu-KIT-63.78 with high catalytic activity and good stability.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • PtSnNa/SUZ-4: An efficient catalyst for propane dehydrogenation
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Hualan Zhou, Jingjing Gong, Bolian Xu, Shengcai Deng, Yuanhua Ding, Lei Yu, Yining Fan
      The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD, nitrogen adsorption, NH3-TPD, TG, H2-TPR and TPO techniques combined with propane dehydrogenation tests. It has been shown that SUZ-4-supported PtSnNa (PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5, owing to its higher catalytic activity and stability. Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts. The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity. In contrast to ZSM-5-supported catalysts, Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition. This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H2PtCl6 into the zeolite. In contrast, the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels, followed by transformation to highly dispersed Pt clusters during calcination. In the case of the PtSnNa/ZSM-5, the interactions between Sn oxides and the support were lessened, owing to the weaker acidity of the ZSM-5 zeolite. The dispersed Sn oxides were therefore easier to reduce to the metallic state, thus decreasing the catalytic activity for hydrocarbon dehydrogenation.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Selective glycerol oxidation using platinum nanoparticles supported on
           multi-walled carbon nanotubes and nitrogen-doped graphene hybrid
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Mengyuan Zhang, Yanyan Sun, Juanjuan Shi, Wensheng Ning, Zhaoyin Hou
      Selective oxidation of glycerol is a hot topic. Increased biodiesel production has led to glycerol oxidation over Au- and Pt-based catalysts being widely studied. However, Pt catalysts suffer from deactivation because of weak metal-support interactions. In this study, multi-walled carbon nanotube (MWCNTs)-pillared nitrogen-doped graphene (NG) was prepared by direct pyrolysis of melamine on MWCNTs, and the synthesized NG-MWCNT composite was used as the support for Pt. Characterization results showed that the surface area (173 m2/g) and pore volume of the NG-MWCNT composite were greater than those of bare MWCNTs and the separated melamine pyrolysis product (CN x ). Pt (1.4 ± 0.4 nm) dispersion on the NG-MWCNTs was favorable and the Pt/NG-MWCNT catalyst was highly active and selective in the oxidation of glycerol to glyceric acid (GLYA) in base-free aqueous solution. For example, the conversion of glycerol reached 64.4% with a GLYA selectivity of 81.0%, whereas the conversions of glycerol over Pt/MWCNTs and Pt/CN x were 29.0% and 31.6%, respectively. The unique catalytic activity of the Pt/NG-MWCNTs is attributed to well-dispersed Pt clusters on the NG-MWCNTs and the electron-donating effect of the nitrogen dopant in the NG-MWCNTs.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
 
 
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