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  Subjects -> ENGINEERING (Total: 2282 journals)
    - CHEMICAL ENGINEERING (192 journals)
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    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1204 journals)
    - ENGINEERING MECHANICS AND MATERIALS (385 journals)
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ENGINEERING (1204 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 6)
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: 233)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
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: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 6)
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 3)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
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: 15)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
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: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
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: 30)
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: 28)
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: 15)
Applied Clay Science     Hybrid Journal   (Followers: 5)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
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: 3)
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: 8)
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: 8)
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: 5)
Batteries     Open Access   (Followers: 4)
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: 4)
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: 10)
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: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 31)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 9)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Hybrid Journal   (Followers: 2)
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     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
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: 8)
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: 10)
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: 5)
Coatings     Open Access   (Followers: 3)
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: 26)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 258)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 181)
Composites Part B : Engineering     Hybrid Journal   (Followers: 237)
Composites Science and Technology     Hybrid Journal   (Followers: 216)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 14)
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: 28)
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: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 30)
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: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 42)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Current Science     Open Access   (Followers: 58)

        1 2 3 4 5 6 7 | Last

Journal Cover Applied Catalysis A: General
  [SJR: 1.234]   [H-I: 159]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0926-860X
   Published by Elsevier Homepage  [3044 journals]
  • Insight into the role of hydroxyl groups on the ZnCr catalyst for
           isobutanol synthesis from syngas
    • Authors: Xiaofeng Gao; Yingquan Wu; Guohui Yang; Tao Zhang; Xiaoli Li; Hongjuan Xie; Junxuan Pan; Yisheng Tan
      Pages: 1 - 11
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Xiaofeng Gao, Yingquan Wu, Guohui Yang, Tao Zhang, Xiaoli Li, Hongjuan Xie, Junxuan Pan, Yisheng Tan
      A series of ZnO, ZnCr catalysts were prepared by a sol-gel method and ammonia solution was used to adjust the pH of the sol solution. The catalysts were characterized by XRD, in-situ FR-IR, NH3-TPD, in-situ XPS, HRTEM. The results show that lower calcination temperature is helpful to reduce the crystal size and crystallinity of ZnCr nanocrystal, as well as forming a certain amount of structure defects and hydroxyl groups. The hydroxyl groups could be consumed by CO under the interaction between ZnO and ZnCr spinel, resulting in more exposed oxygen vacancies. We find the proper calcination temperature and Zn/Cr molar ratio for the ZnCr catalysts preparation are 400°C and 1.0, respectively. The Zn1Cr1–400∼2.0 catalyst prepared with the pH value of 2 shows more hydroxyl groups and small particle size, exhibiting the best catalytic performance both on the CO conversion (20.9%) and isobutanol selectivity (24.2wt%).
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.022
      Issue No: Vol. 547 (2017)
       
  • Design of selective hydrocracking catalysts for BTX production from
           diesel-boiling-range polycyclic aromatic hydrocarbons
    • Authors: Jaeuk Shin; Youngseok Oh; Yeseul Choi; Jihye Lee; Jung Kyoo Lee
      Pages: 12 - 21
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Jaeuk Shin, Youngseok Oh, Yeseul Choi, Jihye Lee, Jung Kyoo Lee
      Various metallic components (Ni, NiSn, NiW-S, CoMo-S and NiMo-S) with different hydrogenation (HYD) activities were supported on H-Beta or hybrid zeolites (BZ(x), where x denotes the weight percentage of H-ZSM-5 in the physical mixture of H-Beta and H-ZSM-5). These bifunctional catalysts were applied to the hydrocracking (HYC) of tetralin in a fixed-bed down-flow reactor at 4MPa as a model reaction for polycyclic aromatic hydrocarbon (PAH) conversion to high-value benzene, toluene, and xylenes (BTX). From the HYC of tetralin over the series of metals/H-Beta catalysts, it was found that CoMo-S/H-Beta and NiMo-S/H-Beta, whose metallic components show moderate activities in the HYD of tetralin, exhibit higher BTX yields than the other catalysts whose metals have excessively high or low HYD activities. However, these catalysts show limited BTX yield (∼47.3wt% at 425°C) owing to the large coproduction of alkylbenzenes other than BTX. When metals with moderate HYD activities are supported on the hybrid zeolites, the BTX yield is significantly enhanced by the effect of H-ZSM-5 in the dealkylation of alkylbenzenes into BTX. NiMo-S/BZ(10) provides a BTX yield of 54.3wt% and a total 1-ring aromatic yield as high as 63.8wt% (corresponding to 94.4% of the theoretical maximum of 67.6wt%) at 425°C. Therefore, the NiMo-S/BZ(10) catalyst, where the metallic and acidic functions and structural properties of the zeolite are well balanced, show promise as an HYC catalyst for the hydroconversion of PAHs into high-value BTX mixtures.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.019
      Issue No: Vol. 547 (2017)
       
  • Oxidative coupling of methane over Mn-Na2WO4 catalyst supported by
           monolithic SiO2
    • Authors: Cagla Uzunoglu; Aybuke Leba; Ramazan Yildirim
      Pages: 22 - 29
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Cagla Uzunoglu, Aybuke Leba, Ramazan Yildirim
      In this work, oxidative coupling of methane was studied over monolithic Mn/Na2WO4/SiO2 catalysts. The monolithic catalysts were prepared by three different ways as (1) preparation of monolithic silica (monosil) followed by impregnation of Mn and Na2WO4, (2) preparation of monolithic silica with Mn addition during gelation (Mn-monosil) followed by impregnation of Na2WO4 and (3) preparation of monolithic silica as MCM-41 structure (MCM-monosil) followed by impregnation of Mn and Na2WO4. The catalysts were tested in a microflow reactor and the results were compared with those obtained over particulate catalysts. It was found that Mn-monosil performed best and produced C2 yield of 16.2%, which is close to the values obtained over particulate catalyst (19.3%). Mn-monosil was also passed the 10h stability and hysteresis tests successfully. SEM characterization revealed that monolithic catalysts prepared by three different methods had different pore structure; it was also seen from SEM images that Mn-monosil preserved its original form better, and this was also verified by XRD analysis.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.020
      Issue No: Vol. 547 (2017)
       
  • Direct deoxygenation of lignin model compounds into aromatic hydrocarbons
           through hydrogen transfer reaction
    • Authors: Tianye Guo; Qineng Xia; Yi Shao; Xiaohui Liu; Yanqin Wang
      Pages: 30 - 36
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Tianye Guo, Qineng Xia, Yi Shao, Xiaohui Liu, Yanqin Wang
      A new route is reported for the direct deoxygenation of lignin model compounds to aromatic hydrocarbons via the catalytic hydrogen transfer reactions over Ru/Nb2O5-SiO2 catalyst with 2-PrOH as a hydrogen donor. It is found that Ru/Nb2O5-SiO2 catalyst is active for the hydrodeoxygenation of p-cresol with 98.5% conversion and 84.0% yield of toluene at 230°C, owing to the significant promotion effect of NbOx species on CO bond cleavage and the proper transfer hydrogenation activity of Ru. Furthermore, Ru/Nb2O5-SiO2 catalyst also shows excellent performances in the transfer hydrodeoxygenation of various lignin model compounds such as 2-methoxy-4-methyl phenol, benzyl phenyl ether (α-O-4 model compound), 2-(2-methoxyphenyl)oxy-1-phenethanol (β-O-4 model compound) and even the real lignin extracted from birch, into aromatic hydrocarbons with 2-PrOH as the hydrogen donor. The reaction pathway studies of these model compounds demonstrate that the direct deoxygenation (DDO) is the main reaction route over Ru/Nb2O5-SiO2 catalyst in the presence of 2-PrOH. Here, using 2-PrOH as a hydrogen source is found to be more selective to aromatic hydrocarbons than using molecular hydrogen. This work provides a new way for the high selective production of aromatic hydrocarbons from renewable lignin via the catalytic hydrogen transfer reactions.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.07.050
      Issue No: Vol. 547 (2017)
       
  • Characterization of the location of coke deposited on spent HZSM-5 zeolite
           by special temperature-programmed oxidation and isothermal oxidation
           methods
    • Authors: Xiaochao Xian; Chao Ran; Chenglong Nai; Peng Yang; Shuo Zhao; Lichun Dong
      Pages: 37 - 51
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Xiaochao Xian, Chao Ran, Chenglong Nai, Peng Yang, Shuo Zhao, Lichun Dong
      The location of coke deposited on HZSM-5 zeolite catalyst during the supercritical catalytic cracking (400°C, 4.0MPa) of n-dodecane was systematically characterized by special temperature-programmed oxidation (TPO) and isothermal oxidation methods, and a steric hindrance model describing the interactions of the coke deposited on different locations was proposed to support the methods theoretically. Accord to the results, the sharp shoulder peak that appears on the TPO profile at high temperature range (>700°C) with low concentration of oxygen in the oxygen/nitrogen mixed carrier gas (≤2.0 Vol.%) can be ascribed to the characteristic peak representing the oxidation of the coke blocked in micropores, while the appearance of the CO peak during the isothermal oxidation at high temperature (≥550°C) using air as carrier gas provides another method to detect the coke blocked in micropores. Through checking whether the characteristic sharp shoulder peak of the TPO profile appears or not as expected according to the steric hindrance model during the re-oxidation of several samples with different coke content and spatial distribution, which were prepared by partial oxidation of the spent catalyst using TPO and isothermal oxidation methods, the special TPO and isothermal oxidation methods combined with their theoretical support of the steric hindrance model were proved to be self-consistent in the characterization of the location of coke. The location information of coke was further verified by the typical method of nitrogen adsorption-desorption analyses of a series of partially oxidized samples prepared by TPO method.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.023
      Issue No: Vol. 547 (2017)
       
  • Isotopic H/D exchange on graphenes. A combined experimental and
           theoretical study
    • Authors: German Sastre; Amparo Forneli; Valer Almasan; Vasile I. Parvulescu; Hermenegildo Garcia
      Pages: 52 - 59
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): German Sastre, Amparo Forneli, Valer Almasan, Vasile I. Parvulescu, Hermenegildo Garcia
      Adsorption of H2/D2 on graphene (G), graphene oxide (GO), single walled carbon nanotube (SWCNT), N-doped graphene [(N)G], and a sample of active carbon (C) has led to the detection of HD, indicating dissociative chemisorption of hydrogen on the surface of the material. The amount of HD detected follows the order G>SWCNT>GO∼(N)G∼C, G giving about five-fold higher H2/D2 adsorption and HD exchange level than SWCNT and about ten-fold larger values than that of the other samples. Quantum-chemistry calculations modeling a carbon atom vacancy on a G cluster estimates an activation barrier for H2 dissociation of ca. 84kJ/mol for a mechanism involving under coordinated carbon atoms at the defect site.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.018
      Issue No: Vol. 547 (2017)
       
  • Mechanistic evaluation of ferrite AFe2O4 (A=Co, Ni, Cu, and Zn) catalytic
           performance in oxalic acid ozonation
    • Authors: Fengzhen Zhang; Chaohai Wei; Kaiyi Wu; Hongtao Zhou; Yun Hu; Sergei Preis
      Pages: 60 - 68
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Fengzhen Zhang, Chaohai Wei, Kaiyi Wu, Hongtao Zhou, Yun Hu, Sergei Preis
      Spinel ferrites AFe2O4 (A=Co, Ni, Cu, and Zn) synthesized by citrate sol-gel method were tested for their catalytic performance in ozonation of aqueous oxalic acid. The objectives of this work include the evaluation of catalytic activity and ferrites stability in mineralization of oxalic acid together with exploring the activation mechanisms of ferrite catalysts in catalytic ozonation process. The results indicated that CoFe2O4 was the most active in catalyzing oxalic acid mineralization, removing 68.3% of TOC within 120min in the reaction conditions of initial pH 2.3, oxalic acid concentration 5mM, inlet ozone concentration 14±1mgL−1, catalyst dose 1.0gL−1. All catalysts exhibited satisfactory composition stability in a batch experiment, although losing up to 4.67% of the catalyst mass in Fe3+ leaching from ZnFe2O4. H2-Temperature programmed reduction and cyclic voltammetry scan analysis revealed that these spinel ferrites had the potential reducibility and the electron donating ability to ozone molecule, respectively. Additionally, X-ray photoelectron spectroscopy showed that the surface metal ions’ valence state and the surface oxygen species played important roles in catalytic ozonation process. The reaction rate constant of oxalic acid mineralization were well fitted to non-linearly depend on variable metal valence and linearly depend on surface hydroxyl group density. The radical-based mechanistic reaction pathways involving A2+-A3+-A2+ cycle and positively charged surface hydroxyl groups were proposed.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.025
      Issue No: Vol. 547 (2017)
       
  • DFT study reveals geometric and electronic synergisms of palladium-mercury
           alloy catalyst used for hydrogen peroxide formation
    • Authors: Mawan Nugraha; Meng-Che Tsai; John Rick; Wei-Nien Su; Hung-Lung Chou; Bing Joe Hwang
      Pages: 69 - 74
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Mawan Nugraha, Meng-Che Tsai, John Rick, Wei-Nien Su, Hung-Lung Chou, Bing Joe Hwang
      One of the main obstacles confronting the direct synthesis of hydrogen peroxide (H2O2) is how to maintain the unbroken OO bonding of the intermediate species on the catalytic surface. To address this challenge Pd-Hg alloys have been used with initial reports suggesting their performance offers advantages when compared to monometallic Pd and Pd-Au alloys; however, the interactions of O2 with Pd-Hg alloys are not well characterised. In this study, density functional theory (DFT) calculations, employed to investigate O2 adsorption on the Pd and Pd-Hg alloy surfaces, suggested O2 adsorption can occur via either a superoxo or a peroxo pathway and that when Hg is alloyed to Pd there are more surface adsorbed superoxo groups compared to adsorption on a monometallic Pd surface. The Hg in Pd6Hg3/Pd(111) results in an electronic surface structure different to that of Pd(111) and a reduced O2 adsorption energy. The stronger O2 surface interactions, when combined with weaker OO bonding (of the adsorbed O2), which result from the presence of Hg on the Pd-Hg surface leads to synergistic geometric and electronic effects that result in an increased selectivity during of the synthesis of H2O2.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.021
      Issue No: Vol. 547 (2017)
       
  • Hydrogen from pyroligneous acid via modified bimetal Al-SBA-15 catalysts
    • Authors: Xiwei Xu; Yan Sun; Zhiyu Li; Xiaodong Chen; Enchen Jiang
      Pages: 75 - 85
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Xiwei Xu, Yan Sun, Zhiyu Li, Xiaodong Chen, Enchen Jiang
      Hydrogen gas was produced from the catalytic reformation of pyroligneous acid (PA)with modified bimetallic Al-SBA-15 catalysts. Al-SBA-15 catalysts with different aluminum loading contents were prepared through one-step hydrothermal synthesis. Monometallic M-Al-SBA-15 (M=Ni, Fe, Co, and Sn) and bimetallic M/N-Al-SBA-15 (M-N=Ni-Fe, Ni-Sn, and Ni-Co) catalysts were synthesized through impregnation. The catalysts were characterized via N2 adsorption-desorption, scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XRD), and X-ray photoelectron spectroscopy(XPS) analysis and so on. Bimetallic M-N-Al-SBA-15 catalysts exhibited higher catalytic activity and carbon deposition resistance than monometallic M-Al-SBA-15 catalysts. Sn facilitated the combination of Ni with Al into a NiAl2O4 spinel in the carrier. Ni/Sn-Al-SBA-15 bimetallic catalyst showed excellent catalytic activity and carbon deposition resistance. The H2 yield was 30.1mg/g and H2 content remained 40% after 16h under the optimal reaction conditions via the Ni/Sn-Al-SBA-15 catalyst.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.030
      Issue No: Vol. 547 (2017)
       
  • Incorporation of molybdenum into Pd and Pt catalysts supported on
           commercial silica for hydrodeoxygenation reaction of dibenzofuran
    • Authors: D. Ballesteros-Plata; A. Infantes-Molina; M. Rodríguez-Cuadrado; E. Rodríguez-Aguado; P. Braos-García; E. Rodríguez-Castellón
      Pages: 86 - 95
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): D. Ballesteros-Plata, A. Infantes-Molina, M. Rodríguez-Cuadrado, E. Rodríguez-Aguado, P. Braos-García, E. Rodríguez-Castellón
      Molybdenum was incorporated into catalysts based on noble metals (Pt or Pd) and supported on silica in order to evaluate how its presence can modify the catalytic response of monometallic catalysts for hydrodeoxygenation (HDO). To this end, the catalysts were evaluated in the hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) and characterized by different experimental techniques to understand its structure, texture and acidic properties. Catalytic results showed that the active phase had much influence on the activity and selectivity to different reaction products, although, in all cases, bicyclohexane (BCH) was the main reaction product observed. Molybdenum played a very important role in the case of bimetallic catalysts, mainly in the case of palladium. Molybdenum species improved the selectivity to O-free products related to its capacity to break the CO bond. However, molybdenum activity was nil in the absence of noble metal. Moreover, regardless of the noble metal employed, the reducibility, acidity and dispersion of the molybdenum species changed and this is possibly associated to a synergism effect between noble metal and Mo.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.034
      Issue No: Vol. 547 (2017)
       
  • The effect of calcination atmosphere upon the photocatalytic performance
           of Au-La2O3/TiO2 for hydrogen production from formic acid
    • Authors: Minghui Wu; Meng Zhang; Tao Lv; Minxue Guo; Jianjun Li; Chika A. Okonkwo; Qing Liu; Lishan Jia
      Pages: 96 - 104
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Minghui Wu, Meng Zhang, Tao Lv, Minxue Guo, Jianjun Li, Chika A. Okonkwo, Qing Liu, Lishan Jia
      A simple modified sol-gel method by calcinating titanium dioxide precursor with gold and lanthanum in heat treatment under H2/CO2 atmosphere has been proposed to prepare highly photocatalytic Au-La2O3/TiO2 (ALT) hybrid. Characterization results show that gold nanoparticles with small particle size are embedded in a nearly homogeneous component, which may induce a strong interaction of La and Au co-doping to obtain an appropriately modified bandgap structure and extend the absorption edge to visible light region. The formation of La2O2CO3 on the surface could facilitate to the basicity optimization of the photocatalyst and contribute to the CH bond cleavage in HCOO- to release H2 and CO2 from formic acid (FA). The large surface area and small-sized mesopores structure could provide more active sites for the adsorption of reactant molecules and improve the photocatalytic activity. Benefiting from these positive effects, the ALT photocatalyst calcinating in H2/CO2 demonstrated a great potential in FA photocatalytic decomposition under simulated sunlight irradiation and produced an optimal H2 generation rate of 178.4μmol g c a t − 1 h−1 (14.9mmol g A u − 1 h−1), which was approximately 1.3, 1.9 and 2.6 times higher than the same catalysts calcinating in H2, CO2, and N2, respectively.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.027
      Issue No: Vol. 547 (2017)
       
  • Nanoscale Ziegler catalysts based on bis(acetylacetonate)nickel in the
           arene hydrogenation reactions
    • Authors: Yuliya Yu. Titova; Fedor K. Schmidt
      Pages: 105 - 114
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Yuliya Yu. Titova, Fedor K. Schmidt
      The turnover frequencies of catalytic systems based on Ni(acac)2–AlEt3 or AlEt2(OEt) in the hydrogenation of benzene and its methyl-substituted homologs (toluene, three isomers of xylene, and 1,3,5-trimethylbenzene) have been determined at temperatures of 80–120°C, initial PH2 =15bar, and different ratios of Al/Ni. The size and nature of the nanoparticles forming in the systems based on Ni(acac)2–AlEt3 or AlEt2(OEt) under the benzene hydrogenation condition shave been resolved by high-resolution electron microscopy and X-ray microanalysis. This study included the performance of competitive hydrogenation reactions of benzene with toluene or three xylene isomers. The relative adsorption constants of toluene and three xylene isomers have been determined and the stereochemistry of the hydrogen addition to the arene ring has also been elucidated.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.029
      Issue No: Vol. 547 (2017)
       
  • Gold nanoparticles deposited on surface modified carbon materials as
           reusable catalysts for hydrocarboxylation of cyclohexane
    • Authors: A.P.C. Ribeiro; L.M.D.R.S. Martins; S.A.C. Carabineiro; J.L. Figueiredo; A.J.L. Pombeiro
      Pages: 124 - 131
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): A.P.C. Ribeiro, L.M.D.R.S. Martins, S.A.C. Carabineiro, J.L. Figueiredo, A.J.L. Pombeiro
      Gold nanoparticles were deposited on different carbon materials and used as catalysts for the alkane hydrocarboxylation reaction. Cyclohexane hydrocarboxylation to cyclohexanecarboxylic acid was carried out in the presence of CO and water, peroxodisulfate, in water/acetonitrile medium, at ca. 50°C, with gold nanoparticles deposited by a colloidal method on carbon nanotubes and activated carbon with three different surface chemistries: in their original forms (CNT or AC, respectively), oxidized with HNO3 (-ox) or oxidized with HNO3 and subsequently treated with NaOH (-ox-Na). Au/CNT-ox-Na was the best catalyst, yielding cyclohexanecarboxylic acid up to 88.2% yield, with excellent recyclability (97.5% of the initial activity was maintained after five consecutive catalytic cycles).
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.028
      Issue No: Vol. 547 (2017)
       
  • Performances of promoted cobalt catalysts supported on mesoporous alumina
           for Fischer-Tropsch synthesis
    • Authors: Vahid Vosoughi; Ajay K. Dalai; Nicolas Abatzoglou; Yongfeng Hu
      Pages: 155 - 163
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Vahid Vosoughi, Ajay K. Dalai, Nicolas Abatzoglou, Yongfeng Hu
      Noble metals (Ru, Re, Pt, Ir) and transition metals (Mn, Y) with their atomic ratio of 0.01 to cobalt were used as promoters on the cobalt catalysts supported on mesoporous alumina. The cobalt loading was 15wt% and all catalysts were tested for Fischer-Tropsch synthesis in a fixed-bed reactor. The process conditions for activity test were: 230 °C and 400 psi, GHSV=900h−1, and H 2 C O = 2.0 . The selectivity test for the promoted and unpromoted catalysts was performed at CO conversion ≈50% by adjusting the syngas flowrate. Addition of promoters increased the cobalt dispersion on mesoporous alumina support. The highest increase in dispersion from 4.7% to 7.6% resulted from addition of Ru. Promoters positively impacted the cobalt dispersion in the decreasing order of: Ru < Re < Pt < Ir < Mn < Y. The reduction temperature for all promoted catalysts were shifted to lower temperature. The maximum decrease in temperature happened with platinum by ΔT ∼−150°C for the 1st reduction temperature and ΔT ∼−270°C for the 2nd reduction temperature. The reducibility of the CoOx species on mesoporous alumina was extensively improved by noble metals addition and modestly enhanced by Mn and Y. Significant increase in CO conversion and C5+ of the promoted catalysts were observed. CO conversion was increased from ∼60% to ∼86, 84, 82, 80% as a result of Ru, Re, Ir, Pt addition. Addition of Ru and Re promoters favored the heavy molecular weight hydrocarbons’ (C5+) selectivity and improved it from 81.7% to 84.2 and 83.1%, respectively.
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      PubDate: 2017-09-08T03:35:11Z
      DOI: 10.1016/j.apcata.2017.08.032
      Issue No: Vol. 547 (2017)
       
  • SAPO-18 and SAPO-34 catalysts for propylene production from the
           oligomerization-cracking of ethylene or 1-butene
    • Authors: Eva Epelde; María Ibáñez; José Valecillos; Andrés T. Aguayo; Ana G. Gayubo; Javier Bilbao; Pedro Castaño
      Pages: 176 - 182
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Eva Epelde, María Ibáñez, José Valecillos, Andrés T. Aguayo, Ana G. Gayubo, Javier Bilbao, Pedro Castaño
      The performance of SAPO-18 and SAPO-34 catalysts has been compared during the conversion of ethylene or 1-butene to propylene. This comparison has been made in terms of activity (conversion), selectivity and stability against coke deposition. The SAPOs were synthesized, agglomerated, calcined, characterized and tested in a fixed-bed reactor at 500°C. The spent catalysts (after 5h on stream) were characterized to assign the location and nature of coke. The results point to the higher activity and stability of SAPO-18 catalyst in the conversions of each reactant (ethylene or 1-butene), which has been explained on the basis of its acidity, pore topology and above all, the faster diffusion of aromatics causing deactivation. Thus, the SAPO-18 catalyst suffers slower coke deposition, while this coke is of lighter nature (more aliphatic and less aromatic). The advantages of SAPO-18 over SAPO-34 catalyst are more relevant for the transformation of 1-butene, where the propylene selectivity and yield increase over time, as secondary reactions are selectively neglected and coke condensation is slowed down.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.036
      Issue No: Vol. 547 (2017)
       
  • Hydrogenation of 2-benzylpyridine over alumina-supported Ru catalysts: Use
           of Ru3(CO)12 as a Ru precursor
    • Authors: Tae Wan Kim; Jinho Oh; Young-Woong Suh
      Pages: 183 - 190
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Tae Wan Kim, Jinho Oh, Young-Woong Suh
      Although Ru3(CO)12 becomes a popular precursor for supported Ru catalysts nowadays, the activities of the catalysts prepared by thermolysis of the supported Ru3(CO)12 under different atmospheres have been rarely compared. We herein report the preparation of alumina-supported Ru samples by thermal activation of Ru3(CO)12 in air, H2 or N2, followed by activity test in the hydrogenation of 2-benzylpyridine (BPy). When the supported Ru3(CO)12 was activated in air, RuO2 particles of 12–15nm diameters were produced by complete oxidation of carbonyl groups. In contrast, thermal activation in H2 and N2 induced the formation of highly dispersed Ru0 particles of 1.4–2.3nm diameters. In such activations methane was produced, suggesting that direct hydrogenation of CO coordinated to the Ru surface complex occurred in H2 while the coordinated CO reacted with ruthenium hydride species in N2. In the activity test for BPy hydrogenation, the samples prepared in H2 and N2 showed superior H2 storage efficiencies and higher rate constants compared to those prepared in air (reduced before the reaction). Additionally, the former samples were examined to be relatively stable even though exposed to ambient air for 7 days. Therefore, H2 and N2 gases are recommended for thermal activation of alumina-supported Ru3(CO)12.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.038
      Issue No: Vol. 547 (2017)
       
  • Easily recoverable micron-sized silica-walled TS-1 colloidosomes:
           Preparation and application as liquid-phase alkene epoxidation catalysts
    • Authors: Guojun Lv; Fumin Wang; Xubin Zhang
      Pages: 191 - 198
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Guojun Lv, Fumin Wang, Xubin Zhang
      Ultrafine hierarchical TS-1 zeolite (<300nm) generally expresses eminent catalytic activity for liquid-phase alkene epoxidation, but encounters serious separation difficulties. Micron-sized silica-walled TS-1 colloidosomes, which were synthesized via an interfacial sol-gel method, can effectively resolve fine TS-1 zeolite separation problems. The interfacial sol-gel process involves construction of a stable W/O Pickering emulsion stabilized by fine TS-1 particles and alkali-catalyzed hydrolysis of silica precursor methyl-trimethoxysilane at the oil-water interface. The successful preparation of TS-1 colloidosome was verified by Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The prepared TS-1 colloidosome dimension is tailorable according to water-to-oil volume ratio (Rw/o) and ratio of TS-1 wt to oil volume (Rs/o). On the same time, X-ray diffraction patterns and UV–vis spectra disclosed that the interfacial sol-gel process had no effect on the MFI structure of hierarchical TS-1 particles. The catalytic results showed that the prepared TS-1 colloidosome was a very active and stable catalyst for liquid-phase alkene epoxidation reactions.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.001
      Issue No: Vol. 547 (2017)
       
  • Characterization and catalytic activity of CuO/TiO2-ZrO2 for low
           temperature CO oxidation
    • Authors: Masashi Kikugawa; Kiyoshi Yamazaki; Hirofumi Shinjoh
      Pages: 199 - 204
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Masashi Kikugawa, Kiyoshi Yamazaki, Hirofumi Shinjoh
      In this study, catalysts with different loadings of CuO supported on TZ20 (TiO2:ZrO2 =80:20) composite oxides were prepared by the co-precipitation method and characterized by XRD, TEM, and H2-TPR measurements, and N2O decomposition experiments were conducted to determine the number of Cu sites. In addition, the relationship between the CuO states and CO oxidation activities of CuO/TZ20 was revealed. In our previous study, the CO oxidation activities of the CuO catalysts were as high as those observed for precious metal catalysts after simulated diesel exhaust aging tests. The TZ20 surface is covered with three types of Cu species. These species change with increasing CuO loading, going from isolated Cu2+, CuO layer, and finally to CuO particles at high CuO loadings. The CuO layer was the most readily reduced, as well as the most active site for CO oxidation. The amount of Cu forming CuO layers increased with increasing CuO loading; however, at CuO loadings larger than 5wt%, the amount of Cu forming CuO layers and the CO oxidation activity both remained constant. Additionally we indicated that adjusting the calcination condition caused the redispersion of CuO particles to the CuO layer and had the potential to improve the CO oxidation activities of CuO/TZ20.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.005
      Issue No: Vol. 547 (2017)
       
  • Surfactant-assisted formation of silver titanates as active catalysts for
           methanol electro-oxidation
    • Authors: Mohamed Mokhtar Mohamed; M. Khairy; Salah Eid
      Pages: 205 - 213
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Mohamed Mokhtar Mohamed, M. Khairy, Salah Eid
      Silver nanoparticles successfully incorporated in titanate nanosheets and synthesized hydrothermally via employing cetyltrimethylammonium bromide (CTAB) and triblock copolymer (pluronic F127) assisted templates were thoroughly characterized using transmission electron microscopy-selected area electron diffraction (TEM-SAED), X-ray diffraction, diffuse reflectance UV/visible absorption spectroscopy, N2 sorptiometry, FTIR and Raman spectroscopy. The dispersed Ag nanoparticles of uniform size (2–3nm) were found to contact intimately with titanateF127 nanosheets to show superior crystallinity, wider layer distances and higher surface area and pore volume (SBET =51.1m2 g−1,Vp =0.081cm3g−1) than Ag/titanateCTAB (7.2m2 g−1, 0.02cm3 g−1). This constructed Ag/titanateF127 exhibits markedly improved electrocatalytic (1.4-fold) and photoelectrocatalytic (4.0-fold) activities and stabilities towards methanol oxidation than that of Ag/titanateCTAB; as determined using cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The enhanced activity of Ag/titanateF127 was also attributed to electron transfer across the interface potential of the composite Ag-titanateF127 as well as the delay of charge recombination that has been substantiated not only via exposed Ag but also through the non-decomposed carbon template. This enhanced electron transfer and electronic conductivity was established by impedance spectroscopy, and exhibits the maximum obtained photocurrent density (2.0mAcm−2) under visible light illumination (λ>420nm, 88W). The results revealed that the template F127 had a significant effect not only on enhancing the titanate crystallinity and exhibiting a surface plasmon resonance band; unlike Ag/titanateCTAB, but also in acquiring a high pore volume value and widened layers, which all work towards improving the Ag-titanateF127 durability for methanol oxidation.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.031
      Issue No: Vol. 547 (2017)
       
  • Elecreoreduction of CO2 to formic acid on Cu: Role of water bilayer in
           modeling electrochemical interface
    • Authors: Shan Ping Liu; Ming Zhao; Yong Fu Zhu; Wang Gao; Qing Jiang
      Pages: 214 - 218
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Shan Ping Liu, Ming Zhao, Yong Fu Zhu, Wang Gao, Qing Jiang
      Solid–liquid interface, which is the location that electrochemical reaction occurs, is essential for CO2 reduction. However, different theoretical calculations often use different models of solid–liquid interface and predict conflicting mechanisms, e.g. for the formation of HCOOH. To address this issue, we adopt different structures of solid–liquid interface to mimic the reaction circumstance using density functional theory calculations. We find that the reaction barriers and energies are sensitive to the reaction circumstance, such as the state of water molecules, the number of water molecules, and the available surface sites, whereas the selectivity of CO2 reduction can be hardly changed once a water bilayer network on Cu surface is used. In particular, a solid–liquid interface built from 4-6-4 water rings (5H2O/1H) can present an appropriate description of the solvent, predicting the formation pathways of HCOOH in reasonable agreement with the experiments. These results confirm the role of water bilayer networks in describing solid–liquid interface in the electrocatalysis, which serves as an important basis for the future studies.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.002
      Issue No: Vol. 547 (2017)
       
  • Structure–activity relationships of Fe-Co/K-Al2O3 catalysts calcined at
           different temperatures for CO2 hydrogenation to light olefins
    • Authors: Thanapa Numpilai; Thongthai Witoon; Narong Chanlek; Wanwisa Limphirat; Giuseppe Bonura; Metta Chareonpanich; Jumras Limtrakul
      Pages: 219 - 229
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Thanapa Numpilai, Thongthai Witoon, Narong Chanlek, Wanwisa Limphirat, Giuseppe Bonura, Metta Chareonpanich, Jumras Limtrakul
      Fe-Co/K-Al2O3 catalyst has been reported to be active and selective for olefin production from CO2 hydrogenation. However, the effect of calcination temperature on the physicochemical properties of Fe-Co/K-Al2O3 catalysts as well as their catalytic activity in CO2 hydrogenation to olefins has not yet been addressed. Here, we show that the calcination temperature (400–800°C) has significant impacts on metal oxides crystallite size, on the interaction between Fe2O3 and other metal oxides and on the transformation of potassium phases, which affect CO2 conversion, product selectivity as well as yield of olefins. The Fe-Co/K-Al2O3 catalyst calcined at 400°C achieves the highest CO2 conversion, hydrocarbons selectivity and olefins yield of 49.0%, 90.6% and 18.1%, respectively. The CO2 conversion and hydrocarbons selectivity decrease with ascending calcination temperature which is ascribed to the increase of metal oxides crystallite size, inducing stronger interactions between Fe2O3 and other metal oxides. Unlike the CO2 conversion and hydrocarbons selectivity, the olefins to paraffins (O/P) ratio followed a volcano-shaped trend as the function of calcination temperature with a maximum at 7.6 over the Fe-Co/K-Al2O3 catalyst calcined at 700°C. This volcanic trend is attributed to the interplay among the positive effect of high calcination temperature on the complete decomposition of KNO3 to K2O, a stronger interaction between Fe2O3 and K2O and the formation of KAlO2 phase, favorably suppressing the hydrogenation of olefins, and the negative effect of high calcination temperature on the increase of the particle size of the active phase and lower dispersion of mixed metal oxides due to a drastic decrease in BET surface area.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.006
      Issue No: Vol. 547 (2017)
       
  • Basic anion-exchange resin (AER)-supported Au-Pd alloy nanoparticles for
           the oxidation of 5-hydroxymethyl-2-furfural (HMF) into 2,5-furan
           dicarboxylic acid (FDCA)
    • Authors: Churchil A. Antonyraj; Nhan Thanh Thien Huynh; Seok-Kyu Park; Seunghan Shin; Yong Jin Kim; Sangyong Kim; Kwan-Young Lee; Jin Ku Cho
      Pages: 230 - 236
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Churchil A. Antonyraj, Nhan Thanh Thien Huynh, Seok-Kyu Park, Seunghan Shin, Yong Jin Kim, Sangyong Kim, Kwan-Young Lee, Jin Ku Cho
      Au-Pd alloy nanoparticles supported on basic anion-exchange resin (AER) have exceptional catalytic activity for the oxidation of 5-hydroxymethyl-2-furfural (HMF) into 2,5-furan dicarboxylic acid (FDCA) with an equimolar amount of base. SEM-EDX and TEM analyses show that 5–20nm Au-Pd alloy nanoparticles are well dispersed both on the resin surface and inside resin spheres by a simple procedure without any assistance of additives. XPS analysis reveals that Au- and Pd metals exist in an alloy form on the AER support, which is confirmed by a comparison study with a mixture of AER-supported monometallic nanoparticles (AER-supported Au and AER-supported Pd). In the presence of a 1:1 ratio of Au-Pd alloy nanoparticles over Amberlite IRA-743 resin with O2 (10bar) at 373K in an equimolar Na2CO3 aqueous solution, HMF is oxidized to FDCA with a 93.2% yield. On the other hand, mixture of AER-supported Au and AER-supported Pd affords only a 52% FDCA yield under identical conditions. This catalyst can be used 6 times without any significant loss of activity. FDCA is also obtained from HMF with an 82.9% yield in air (40bar).
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.012
      Issue No: Vol. 547 (2017)
       
  • High efficient conversion of furfural to 2-methylfuran over Ni-Cu/Al2O3
           catalyst with formic acid as a hydrogen donor
    • Authors: Zhaolin Fu; Ze Wang; Weigang Lin; Wenli Song; Songgeng Li
      Pages: 248 - 255
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Zhaolin Fu, Ze Wang, Weigang Lin, Wenli Song, Songgeng Li
      Conversion of furfural to 2-methylfuran over Cu/Al2O3, Ni/Al2O3 and Ni-Cu/Al2O3 catalysts were investigated with formic acid as a hydrogen donor. Ni/Al2O3 showed a high catalytic activity but a moderate selectivity to 2-methylfuran. Contrarily, Cu/Al2O3 showed a low catalytic activity but a high selectivity for carbonyl reduction. Over the bimetallic catalysts Ni-10%Cu/Al2O3, by increasing Ni content, more furfural was converted with the reduction of carbonyl primarily. The effect of reaction solvent and the fraction of formic acid were also studied. The result showed that isopropanol solvent could contribute to the formation of furfuryl alcohol with 96% selectivity through the transfer hydrogenation process. Formic acid could decompose to H2 and CO2, remarkably promoting the hydrogenolysis of furfuryl alcohol to 2-methylfuran. Finally, 100% conversion and 92mol% yield of 2-methylfuran could be obtained over 10%Ni-10%Cu/Al2O3. It was attributed to the synergic effect of Ni-Cu metals, with increased affinity for carbonyl reduction.
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      PubDate: 2017-09-20T08:07:00Z
      DOI: 10.1016/j.apcata.2017.09.011
      Issue No: Vol. 547 (2017)
       
  • Conversion of guaiacol over different Re active phases supported on
           CeO2-Al2O3
    • Authors: C. Alvarez; K. Cruces; R. Garcia; C. Sepulveda; J.L.G. Fierro; I.T. Ghampson; N. Escalona
      Pages: 256 - 264
      Abstract: Publication date: Available online 8 September 2017
      Source:Applied Catalysis A: General
      Author(s): C. Alvarez, K. Cruces, R. Garcia, C. Sepulveda, J.L.G. Fierro, I.T. Ghampson, N. Escalona
      The effect of Al2O3 modification by CeO2 addition (14wt.% to obtain a maximum monolayer coverage) on the catalytic activity of three supported Re active phases (Re, ReOx and ReSx) for guaiacol conversion was studied. A 10wt.% loading of Re was impregnated into CeO2-Al2O3 support and used to prepare the three rhenium active phases by calcination, reduction or sulfidation steps. The catalysts were characterized by different techniques in order to explain the catalytic behavior of the solids studied. The catalysts were then evaluated in a batch reactor at 300°C and 5MPa of H2. The characterization results showed that the addition of CeO2 modified the acidity of the support as well as the metal-support interaction, and consequently the catalytic activity. In fact, CeO2 addition doubled the activity of Re and ReSx catalysts in comparison to the corresponding γ-Al2O3-supported catalysts. These results were attributed to a higher dispersion of active sites in the case of metallic Re catalyst and higher concentration of non-stoichiometric sulfur species (ReS2-x) in the case of ReSx catalyst. On the other hand, a similar catalytic activity was observed over the two supported ReOx catalysts, indicating that the role of ReOx active phase on guaiacol conversion outweighs structural and surface modification induced by CeO2 addition. In relation to products distribution, it was observed that CeO2 addition enhanced phenol formation and generally led to higher degree of deoxygenation which is most likely related to decrease in acidity.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.010
      Issue No: Vol. 547 (2017)
       
  • Dialkylpyrazolium ionic liquids as novel catalyst for efficient fixation
           of CO2 with metal- and solvent-free
    • Authors: Yuan Ma; Ci Chen; Tengfei Wang; Jingshun Zhang; JiaJia Wu; Xiangdong Liu; Tiegang Ren; Li Wang; Jinglai Zhang
      Pages: 265 - 273
      Abstract: Publication date: Available online 8 September 2017
      Source:Applied Catalysis A: General
      Author(s): Yuan Ma, Ci Chen, Tengfei Wang, Jingshun Zhang, JiaJia Wu, Xiangdong Liu, Tiegang Ren, Li Wang, Jinglai Zhang
      The efficient fixation of CO2 without co-catalyst and solvent under metal-free condition is still an urgent topic in sustainable chemistry. In this work, a series of dialkylpyrazolium ionic liquids are employed to promote the cycloaddition of CO2 and PO to produce PC. They would be easily synthesized by a simple one-pot reaction. The effect of alkyl chain length in cation and different anion is explored. Diethylpyrazolium iodide presents the excellent catalytic activity with the product yield of 96% and selectivity of 99% in a benign condition. Moreover, the catalyst could be reused for at least five times without significant loss of catalytic activity. An intensive structure-activity research testifies that the cycloaddition of CO2 with PO is activated by a synergistic effect from both cation and anion of ILs. To confirm it, the detailed mechanism is investigated by density functional theory associated with the non-covalent interactions and atoms in molecule analysis. Besides the electrostatic interaction between cation of ionic liquid and PO, the noncovalent interaction, especially for hydrogen bond, plays a vital role in promoting the reaction.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.009
      Issue No: Vol. 547 (2017)
       
  • Catalytic fast pyrolysis of cellulose in a microreactor system using
           hierarchical zsm-5 zeolites treated with various alkalis
    • Authors: Kai Qiao; Xu Shi; Feng Zhou; Hao Chen; Jie Fu; Huixia Ma; He Huang
      Pages: 274 - 282
      Abstract: Publication date: 25 October 2017
      Source:Applied Catalysis A: General, Volume 547
      Author(s): Kai Qiao, Xu Shi, Feng Zhou, Hao Chen, Jie Fu, Huixia Ma, He Huang
      Hierarchical ZSM-5 catalysts were prepared by desilication using NaOH, Na2CO3 and TPAOH with different concentrations under the same treatment conditions. Their structures and acidities were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption and desorption (N2-BET) and ammonia temperature-programmed desorption (NH3-TPD). The catalytic fast pyrolysis (CFP) of cellulose to produce aromatics over the hierarchical ZSM-5 catalysts prepared using different alkali treatments was investigated. The alkali treatment by Na2CO3 (0.4∼0.8M) was much milder than treatment by NaOH, which allowed the desilication process to be highly controllable, resulting in an increase of both the amount and strength of the strong acid sites, and the formation of hierarchical structures combining micro- and mesoporosity. The organic hydroxide TPAOH did not change the pore structure of ZSM-5, but it greatly increased the relative crystallinity. The CFP of cellulose with HZSM-5 produced 35.5% liquid aromatic hydrocarbons and 32.7% coke. The yield of aromatics increased after Na2CO3 treatment but decreased after NaOH treatment. In addition, the yield of coke showed the opposite trend. The highest aromatic yield (38.2%) and lowest coke yield were obtained in the CFP of cellulose with the desilicated zeolite treated with 0.6M Na2CO3. The increased acidity in hierarchical ZSM-5 treated with Na2CO3 increased the selectivity of highly valuable aromatics, such as benzene, toluene, and xylene, and decreased the selectivity of large aromatics. TPAOH-treated HZSM-5 showed a slightly increased yield of aromatics due to the repair effect of TPAOH, but this treatment did not form a mesoporous structure.
      Graphical abstract image

      PubDate: 2017-09-20T08:07:00Z
      DOI: 10.1016/j.apcata.2017.07.034
      Issue No: Vol. 547 (2017)
       
  • Aerobic oxidation of α-pinene catalyzed by homogeneous and MOF-based
           Mn catalysts
    • Authors: Yasmin S. Raupp; Ceylan Yildiz; Wolfgang Kleist; Michael A.R. Meier
      Pages: 1 - 6
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Yasmin S. Raupp, Ceylan Yildiz, Wolfgang Kleist, Michael A.R. Meier
      Manganese catalysts were investigated for the liquid-phase aerobic oxidation of α‐pinene. First, the influence of reaction parameters such as time, solvent, temperature, oxidant flow rate and catalyst concentration on conversion, yield and selectivity were evaluated using Mn(III) acetate as homogeneous catalyst. Mn(III) acetate afforded pinene oxide as the main product along with small amounts of verbenol and verbenone. The optimized reaction conditions were likewise applied to a novel mixed-linker metal-organic framework (MOF) based on MIL-53-NH2(Al), which was successfully synthesized and modified in a two-step post-synthetic reaction using maleic anhydride and Mn(III) acetate. The performance of the Mn-containing MOF catalyst was directly compared to its homogeneous counterpart Mn(III) acetate, showing very similar activity in a mixture of diethyl carbonate/dimethylformamide (DEC/DMF) as solvent. In both cases, a conversion of 31% and the formation of 17% pinene oxide (55% selectivity) were observed after 6 h. The heterogeneous MOF catalyst was easily removed from the reaction mixture by filtration and reused for at least five catalytic cycles without significant loss of activity. A hot filtration test showed that the catalysis mainly proceeded heterogeneously, although minor contributions of homogeneous species could not be completely excluded.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.07.047
      Issue No: Vol. 546 (2017)
       
  • Chemoenzymatic synthesis of (S)-Pindolol using lipases
    • Authors: Gledson Vieira Lima; Marcos Reinaldo da Silva; Thiago de Sousa Fonseca; Leandro Bezerra de Lima; Maria da Conceição Ferreira de Oliveira; Telma Leda Gomes de Lemos; Davila Zampieri; Jose Cleiton Sousa dos Santos; Nathalia Saraiva Rios; Luciana Rocha Barros Gonçalves; Francesco Molinari; Marcos Carlos de Mattos
      Pages: 7 - 14
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Gledson Vieira Lima, Marcos Reinaldo da Silva, Thiago de Sousa Fonseca, Leandro Bezerra de Lima, Maria da Conceição Ferreira de Oliveira, Telma Leda Gomes de Lemos, Davila Zampieri, Jose Cleiton Sousa dos Santos, Nathalia Saraiva Rios, Luciana Rocha Barros Gonçalves, Francesco Molinari, Marcos Carlos de Mattos
      A straightforward chemoenzymatic synthesis of (S)-Pindolol has been developed. The key step involved the enzymatic kinetic resolution of rac-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane with lipase from Pseudomonas fluorescens via hydrolytic process to obtain enantiomerically enriched halohydrin (2S)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (96% ee) and (2R)-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane (97% ee). The latter was subjected to a hydrolysis reaction catalyzed by Candida rugosa leading to (2R)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (97% ee), followed by a reaction with isopropylamine, producing (S)-Pindolol (97% ee) in quantitative yield.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.003
      Issue No: Vol. 546 (2017)
       
  • Influence of lactic acid on the catalytic performance of MDABCO for
           ring-opening polymerization of l-lactide
    • Authors: Zhixiong Luo; Somboon Chaemchuen; Kui Zhou; Andres Alvarado Gonzalez; Francis Verpoort
      Pages: 15 - 21
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Zhixiong Luo, Somboon Chaemchuen, Kui Zhou, Andres Alvarado Gonzalez, Francis Verpoort
      A series of metal organic frameworks (MOFs) MDABCO (M=Co, Ni, Cu, Zn; DABCO=1,4-diazabicyclo[2.2.2]octane) are utilized as catalysts for the bulk ring-opening polymerization of l-lactide. The catalytic activity varies in the order CuDABCO, NiDABCO<ZnDABCO, CoDABCO. By adding lactic acid, we unexpectedly observed enhanced catalytic activity. The combined use of lactic acid and ZnDABCO during polymerization results in a highly active polymerization system, along with the gradual change of MOFs structure caused by an increased acid concentration. Compared to related homogeneous fragments, such as zinc nitrate and 1,4-diazabicyclo[2.2.2]octane, ZnDABCO is found to afford highly isotactic polylactide, which would be ascribed to the unique structural properties of MOFs.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.007
      Issue No: Vol. 546 (2017)
       
  • Synthesis of maghemite nanoparticles, biodiesel and hydrogen: One pot
           sequential reactions
    • Authors: Mookan Rengasamy; Mohanraj Sundaresan; Anbalagan Krishnasamy; Pugalenthi Velan
      Pages: 22 - 29
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Mookan Rengasamy, Mohanraj Sundaresan, Anbalagan Krishnasamy, Pugalenthi Velan
      A sequential synthesis of hydrogen, iron nanoparticles and biodiesel was developed through a single step reaction. Hydrogen was generated as 2600±25mL during the methanolysis of sodium borohydride. Iron nanoparticles in the form of maghemite (γ-Fe2O3, maghemite nanoparticles, MNPs) were formed by the chemical reduction of ferric chloride with sodium borohydride. The obtained maghemite nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis. The size of the maghemite nanoparticles ranged from 15 to 27nm. Biodiesel was produced by transesterification reaction of Pongamia pinnata oil using in situ formed maghemite nanocatalyst with the highest yield of 90±1%. The formed biodiesel was analyzed by FTIR and gas chromatography-mass spectrometry (GC–MS). The saturated, monounsaturated and polyunsaturated fatty acid methyl esters distributions of biodiesel were measured using GC–MS and the values were reported as 27.37, 56.41 and 16.22%, respectively. The fuel properties of the resultant biodiesel agreed well with the ASTM D6751 specifications. These findings show that the produced biodiesel and hydrogen were commercially attractive and potentially alternative for petrodiesel.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.07.019
      Issue No: Vol. 546 (2017)
       
  • Graphitic carbon/carbon nitride hybrid as metal-free photocatalyst for
           enhancing hydrogen evolution
    • Authors: Xiaohan An; Yiqun Cao; Qi Liu; Lu Chen; Zheguan Lin; Yangen Zhou; Zizhong Zhang; Jinlin Long; Xuxu Wang
      Pages: 30 - 35
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Xiaohan An, Yiqun Cao, Qi Liu, Lu Chen, Zheguan Lin, Yangen Zhou, Zizhong Zhang, Jinlin Long, Xuxu Wang
      Graphitic carbon/carbon nitride hybrid was fabricated by a two-step procedure from the initially hydrothermal self-assembly of melamine and sucrose and then typical thermal condensation. The structure, composition, photoelectric and photocatalytic properties of the resulting sample was characterized in detail by X-ray diffraction, Fourier transform infrared spectra, Raman spectra, X-ray photoelectron spectroscopy, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, photoelectric current, electrochemical impedance spectroscopy and photocatalytic hydrogen production. The results revealed that the graphitic carbon/carbon nitride hybrid has conjugation effect between carbon nitride and graphitic carbon and thus leads to a better efficiency for water splitting than the pristine carbon nitride.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.07.046
      Issue No: Vol. 546 (2017)
       
  • Fabrication of propylsulfonic acid functionalized SiO2 core/PMO shell
           structured PrSO3H-SiO2@Si(R)Si nanospheres for the effective conversion of
           d-fructose into ethyl levulinate
    • Authors: Daiyu Song; Yingnan Sun; Qingqing Zhang; Panpan Zhang; Yihang Guo; Jiyan Leng
      Pages: 36 - 46
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Daiyu Song, Yingnan Sun, Qingqing Zhang, Panpan Zhang, Yihang Guo, Jiyan Leng
      Propylsulfonic acid functionalized SiO2 core/alkyl- or phenyl-bridged organosilica shell structured PrSO3H-SiO2@Si(R)Si (R= C2H4 , C6H4 or C6H4 C6H4 ) nanospheres are facilely prepared by a CTAB-directed one-pot two-step condensation strategy. The morphological characteristics, textural properties, Brønsted acid nature and structure of the PrSO3H-SiO2@Si(R)Si nanospheres are well characterized. The materials are successfully applied in the catalytic transformation of D-fructose into the important organic chemical, ethyl levulinate, in the presence of ethanol as both reactant and solvent. The catalytic activity of the PrSO3H-SiO2@Si(R)Si nanospheres outperform commercially available Amberlyst-15, HY zeolite and HCl, mainly attributing to their strong Brønsted acid nature; additionally, unique core-shell structure with excellent porosity properties and well-adjusted hydrophilicity/hydrophobicity also give the positive influence on the ethanolysis activity, which can improve the accessibility of the reactants to the PrSO3H sites and facilitate the multi-step ethanolysis reaction proceeding to the formation of the final product. The PrSO3H-SiO2@Si(R)Si nanospheres can be reused three times without obvious activity loss, contributed from covalent bonding of the PrSO3H groups with the silica and organosilica framework as well as hydrophobic PrSO3H-functionalized organosilica shell.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.004
      Issue No: Vol. 546 (2017)
       
  • Flame spray pyrolysis-designed silica/ceria-zirconia supports for the
           carbon dioxide reforming of methane
    • Authors: Emma C. Lovell; Jonathan Horlyck; Jason Scott; Rose Amal
      Pages: 47 - 57
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Emma C. Lovell, Jonathan Horlyck, Jason Scott, Rose Amal
      Flame spray pyrolysis (FSP) was used to design silica/ceria-zirconia particles with assorted structures as Ni catalyst supports for the carbon dioxide reforming of methane. The FSP precursor feed was varied to produce either mixed-oxide or core-shell arrays. The structures exhibited diversity in their properties including surface area and oxygen storage capacity. NiO deposit size decreased with increasing ceria-zirconia content, from 14nm for the neat SiO2 to 5nm for the neat Ce0.7Zr0.3O2. Compared to the neat supports, the co-operative benefits of coupling the silica with the ceria-zirconia were clear. Introducing ceria-zirconia to the silica enabled the mixed supports to outperform the neat silica by supressing methane decomposition and promoting the dry reforming reaction. Introducing silica to the ceria-zirconia enabled the mixed supports to outperform the neat ceria-zirconia by decreasing susceptibility toward the reverse water gas shift reaction and preventing deactivation at 700°C, attributed to better support thermal stability.
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      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.08.002
      Issue No: Vol. 546 (2017)
       
  • Deactivation studies of bimetallic AuPd nanoparticles supported on MgO
           during selective aerobic oxidation of alcohols
    • Authors: Susana Guadix-Montero; Hamed Alshammari; Remco Dalebout; Ewa Nowicka; David J. Morgan; Greg Shaw; Qian He; Meenakshisundaram Sankar
      Pages: 58 - 66
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Susana Guadix-Montero, Hamed Alshammari, Remco Dalebout, Ewa Nowicka, David J. Morgan, Greg Shaw, Qian He, Meenakshisundaram Sankar
      Here we report the synthesis and characterisation of high surface area MgO prepared via the thermal decomposition of various magnesium precursors (MgCO3, Mg(OH)2 and MgC2O4). Bimetallic gold-palladium nanoalloy particles were supported on these MgO materials and were tested as catalysts for the solvent-free selective aerobic oxidation of benzyl alcohol to benzaldehyde. All these catalysts were found to be active and very selective (>97%) to the desired product (benzaldehyde). However, MgO prepared via the thermal decomposition of magnesium oxalate displayed the highest activity among all the magnesium oxide supports tested. Attempts were made to unravel the reasons for the deactivation of these catalysts using different characterisation techniques namely in situ XRD, XPS, ICP-MS, TEM, and TGA-MS. From the data obtained, it is clear that MgO undergoes phase changes from MgO to Mg(OH)2 and MgCO3 during catalyst preparation as well as during the catalytic reaction. Besides phase changes, strong adsorption of reactants and products on the catalyst surface, during the reaction, were also observed and washing the catalyst with organic solvents did not completely remove them. The phase change and catalyst poisoning were reversed through high temperature heat treatments. However, these processes led to the sintering of the metal nanoparticles. Moreover, substantial leaching of the support material (MgO) was also observed during the reaction. These latter two processes led to the irreversible deactivation of AuPd nanoparticles supported on MgO catalyst during the solvent-free selective aerobic oxidation of alcohols. Among the three different MgO supports studied in this article, an inverse correlation between the catalytic activity and Mg leaching has been observed. This article reports a deeper understanding of the mode of deactivation observed in metal nanoparticles supported on MgO during liquid phase reactions.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.07.045
      Issue No: Vol. 546 (2017)
       
  • Deconstruction of lignocellulosic biomass with hydrated cerium (III)
           chloride in water and ethanol
    • Authors: Mehmet K. Akalin; Parthapratim Das; Koray Alper; Kubilay Tekin; Arthur J. Ragauskas; Selhan Karagöz
      Pages: 67 - 78
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Mehmet K. Akalin, Parthapratim Das, Koray Alper, Kubilay Tekin, Arthur J. Ragauskas, Selhan Karagöz
      Lignocellulosic biomass was decomposed to produce crude bio-oil in water and ethanol using hydrated cerium (III) chloride as a catalyst. Use of the catalyst affected not only the yield of crude bio-oil but also the composition of bio-crude for both water and ethanol. The catalyst had a detrimental effect on the crude bio-oil yields obtained from water processing for all runs. However, in ethanol, use of the catalyst improved the crude bio-oil yields in all tested runs. The solid residue yields decreased with the catalyst use in the runs with water but increased in all studies with ethanol, except those with the shortest tested residence time of 10min. The highest crude bio-oil yield of 48.2wt% was obtained at 300°C using 5mmol of hydrated cerium (III) chloride at a residence time of 90min in ethanol. The heating values of the crude bio-oils increased with the catalyst use for both water and ethanol processing. The highest heating value of 33.3MJkg−1 was obtained with hydrated cerium (III) chloride at 300°C and a residence time of 120min.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.010
      Issue No: Vol. 546 (2017)
       
  • Facile synthesis of Fe-modified manganese oxide with high content of
           oxygen vacancies for efficient airborne ozone destruction
    • Authors: Jingbo Jia; Wenjuan Yang; Pengyi Zhang; Junying Zhang
      Pages: 79 - 86
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Jingbo Jia, Wenjuan Yang, Pengyi Zhang, Junying Zhang
      Oxygen vacancy engineering is an efficient strategy to improve the catalytic performance of nanomaterials. In this work, a highly active Fe-modified manganese oxide (Fe-MnOx) was synthesized and used for airborne ozone decomposition. The addition of Fe3+ during MnO2 synthesis led to higher specific surface area, greatly increased content of oxygen vacancies, evidenced by XPS, H2-TPR analysis and lower oxygen vacancy formation energy (decreased by ∼1.2eV) based on the density functional theory calculations. The ozone conversion over Fe-MnOx kept 97% after 24h reaction, while it over MnO2 slowed down to 85% under dry condition. Remarkably, under humid condition (RH=60%), the ozone conversion over Fe-MnOx kept 73% after 6h reaction, while ozone conversion over pure MnO2 decreased to 50% within 1h under the conditions of 100ppm inlet ozone concentration and weight space velocity of 660Lg−1 h−1. The intermediate peroxide species (O2 2−) formed on the surface oxygen vacancies of Fe-MnOx and MnO2 during ozone decomposition reaction were observed using in situ Raman spectroscopy. The concentration and depletion rate of O2 2− on the surface of Fe-MnOx was higher than that on MnO2, illustrating that O2 2− acted as the key species to boost the catalytic process. The content and dispersity of oxygen vacancies were identified to be mainly responsible for the performance difference. This provides a promising idea for designing novel nanomaterial catalyst for gaseous ozone decomposition.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.013
      Issue No: Vol. 546 (2017)
       
  • Mechanisms for CC bond cleavage and formation during acrolein production
           on a mixed metal oxide catalyst
    • Authors: Linh Bui; Aditya Bhan
      Pages: 87 - 95
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Linh Bui, Aditya Bhan
      We report a reaction network detailing the mechanistic origins of 20 C2–C6 byproducts observed during the oxidation of propylene to acrolein at 623K on a molybdenum-based catalyst promoted with cobalt and nickel used in the industrial production of acrolein. The carbon backbone of propylene is preserved in the sequential oxidation of propylene to allyl alcohol, acrolein, and acrylic acid, as well as propylene oxidation to acetone and propanal via water-mediated pathways. Transient kinetic measurements in conjunction with co-feed experiments of C2 and C3 aldehydes and carboxylic acids show that decarbonylation and decarboxylation reactions, reactions of organic compounds with surface-adsorbed oxygen species, and total combustion reactions are the three mechanisms for CC bond cleavage. CC bond formation reactions that result in C4–C6 byproducts occur via: (i) the addition reaction of a propylene-derived surface allyl species with formaldehyde to form C4 products and with propylene and allyl alcohol to form C6 products, or (ii) the addition reaction of an acrolein (acrylic acid)-derived surface ethenyl intermediate with propylene to form pentadiene and with acrolein to form C5 cyclic oxygenates.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.011
      Issue No: Vol. 546 (2017)
       
  • Adsorptive interaction between 1,5-pentanediol and MgO-modified ZrO2
           catalyst in the vapor-phase dehydration to produce 4-penten-1-ol
    • Authors: Hailing Duan; Masaki Unno; Yasuhiro Yamada; Satoshi Sato
      Pages: 96 - 102
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Hailing Duan, Masaki Unno, Yasuhiro Yamada, Satoshi Sato
      Vapor-phase catalytic dehydration of 1,5-pentanediol (1,5-PDO) was investigated over monoclinic ZrO2 catalysts modified with basic oxides. An unsaturated alcohol, 4-penten-1-ol (4P1OL), was produced together with the formation of tetrahydropyran, δ-valerolactone, 1,4-pentadiene, pentanal, 1-pentanol, and 5-hydroxypentanal, etc. Among the modified ZrO2 catalysts, only ZrO2 modified with MgO enhanced the selectivity to 4P1OL efficiently. The most active modified catalyst was found to have 20 mol% MgO and a calcination at 800°C (MgO/ZrO2), and the selectivity of 4P1OL exceeded 83% at 400°C. A pulse adsorption measurement of several chemicals clarified adsorptive interaction between a reactant and a catalyst at 220°C: the interaction between 1,5-PDO and MgO/ZrO2 was stronger than the other adsorbates and catalysts. Another strong adsorptive interaction between 1,4-butanediol and CaO/ZrO2, which was effective in the dehydration of 1,4-butanediol to produce 3-buten-1-ol, was also observed.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.07.048
      Issue No: Vol. 546 (2017)
       
  • In situ X-ray diffraction of Fischer-Tropsch catalysts—Effect of water
           on the reduction of cobalt oxides
    • Authors: James Paterson; Mark Peacock; Ewen Ferguson; Manuel Ojeda; Jay Clarkson
      Pages: 103 - 110
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): James Paterson, Mark Peacock, Ewen Ferguson, Manuel Ojeda, Jay Clarkson
      By using in situ X-ray diffraction, we were able to demonstrate the effect of H2O on the reduction of cobalt oxide particles for Fischer-Tropsch Synthesis. Reduction of Co3O4 to Co via CoO in H2 produces large quantities of water, which was thought to have an impact upon the reduction of the catalyst down a reactor bed. Bed profiles are produced from saturation of the bottom of the catalyst bed from the H2O produced from the top of the bed. This contribution clearly shows the impact of H2O on the cobalt crystallites to hinder reduction and facilitate sintering of the cobalt particles. In situ X-ray diffraction was used to follow the reduction of the cobalt phase throughout the evolution of the reduction process, while controlled water production and cofeed was used to study the effect across different water levels (from 0 up to 1% H2O). Each study in turn produced clear transitions to CoO and Co metal, while H2O shifted the peaks to higher transition temperatures and slowed the reduction process to cobalt metal.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.017
      Issue No: Vol. 546 (2017)
       
  • Effect of the size of Cu clusters on selectivity and activity of acetylene
           selective hydrogenation
    • Authors: Bo Zhao; Riguang Zhang; Zaixing Huang; Baojun Wang
      Pages: 111 - 121
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Bo Zhao, Riguang Zhang, Zaixing Huang, Baojun Wang
      In order to probe into the size effect of Cu catalyst on the selectivity and activity of ethylene formation in acetylene selective hydrogenation, different sizes of Cu catalysts including Cu13, Cu38, Cu55 clusters and the periodic Cu(111) surface have been employed to systematically investigate the selective hydrogenation of C2H2 using density functional theory calculations. The results show that the adsorption ability of C2H2 is stronger than that of C2H4 on different sizes of Cu catalysts, which is in favor of C2H2 activation and hydrogenation. On Cu13 and Cu38 clusters, C2H2 easily undergoes over-hydrogenation to form ethane via CHCH2 and CHCH3 intermediates, namely, both clusters exhibit a poor selectivity towards C2H4 formation. However, on Cu55 cluster, C2H2 is easily hydrogenated to form C2H4 via CHCH2 intermediate, and C2H4 prefers desorption over its hydrogenation, suggesting that Cu55 cluster exhibits a good selectivity towards C2H4 formation. Further, the periodic Cu(111) surface regarded as the large Cu particle sizes has the same results with Cu55 cluster. Therefore, among different sizes of Cu cluster, the size of Cu cluster affects the preferred pathway of C2H2 selective hydrogenation, and alters the selectivity towards C2H4 formation; moreover, beginning with Cu55 cluster, Cu cluster is beneficial to C2H2 hydrogenation to C2H4. The activity of C2H4 formation follows the order of Cu(111) > Cu38> Cu55 >> Cu13, which corresponds to the d-band center of these catalysts. The identifications about the relationship of the intrinsic selectivity and activity with cluster size effect would provide a clue for designing highly-efficient Cu-based catalysts in C2H2 hydrogenation to C2H4.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.001
      Issue No: Vol. 546 (2017)
       
  • Manganese incorporated on glucose as an efficient catalyst for the
           synthesis of adipic acid using molecular O2 in aqueous medium
    • Authors: Sagar D. Nale; Pramod V. Rathod; Vrushali H. Jadhav
      Pages: 122 - 125
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Sagar D. Nale, Pramod V. Rathod, Vrushali H. Jadhav
      A new manganese incorporated on glucose catalyst Mn@CC-SO3H-NH2 was synthesized and well characterized using FT-IR, PXRD, EDAX, SEM, TEM, [13] C cross-polarization NMR and BET analysis. The catalyst thus synthesized was studied for its utility in the synthesis of industrially important chemical adipic acid starting from readily available cyclohexanone using molecular O2 as a source. Adipic acid was obtained in maximum yield of 82% using Mn@CC-SO3H-NH2 catalyst in water as a solvent. The catalyst was easily recovered and reused for minimum five runs without any significant loss in the yield of products. Using molecular O2 as an oxidant and water as a solvent, the reaction is very important from green chemistry perspectives and can also be industrially feasible.
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      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.008
      Issue No: Vol. 546 (2017)
       
  • Nickel nanoparticles supported on silica for the partial oxidation of
           isooctane
    • Authors: Qusay Bkour; Oscar G. Marin-Flores; Trent R. Graham; Parissa Ziaei; Steven R. Saunders; M. Grant Norton; Su Ha
      Pages: 126 - 135
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Qusay Bkour, Oscar G. Marin-Flores, Trent R. Graham, Parissa Ziaei, Steven R. Saunders, M. Grant Norton, Su Ha
      A Ni-based nanoparticle catalyst was synthesized over a silica support via wet impregnation using either ethylene glycol or water. X-ray diffraction and transmission electron microscopy analysis showed that the particle size of the Ni catalyst prepared using ethylene glycol as the solvent tended to be smaller than that obtained when water was used. The resulting catalysts were tested for performance toward partial oxidation (POX) of isooctane at high weight hourly space velocities (WHSV). The results were compared with those from a Rh-based catalyst, which is commonly used for the same reaction. At a WHSV of 13.8h−1, a Ni/SiO2 catalyst with an average Ni particle size of 6.8nm exhibits higher catalytic activity and stability with an improved resistance to carbon formation than a Ni/SiO2 catalyst with an average Ni particle size of 16.6nm. The catalyst with the smaller Ni particles outperformed the supported Rh catalyst for the POX of isooctane. To further improve the Ni dispersion and enhance its ability to run at even higher WHSVs with milliseconds of residence time, ceria was used as a promoter. The ceria-promoted Ni catalyst was also prepared by the wet impregnation method using ethylene glycol as the solvent. The addition of ceria corresponded with a further reduction in the size of the Ni nanoparticles and improved Ni dispersion. Using the Ni-Ce/SiO2 catalyst the WHSV could be increased up to 20.0h−1 while still maintaining its good catalytic activity. At this high WHSV of 20.0 h-1, the Ni/SiO2 catalyst without the ceria promoter and the Rh catalyst showed severe deactivation due to the formation of surface carbon deposits.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.015
      Issue No: Vol. 546 (2017)
       
  • Alloying of AuNPs with palladium: A promising tool for tuning of
           selectivity for epoxide in oxidation of styrene using molecular oxygen
    • Authors: Anuj S. Sharma; Harjinder Kaur
      Pages: 136 - 148
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Anuj S. Sharma, Harjinder Kaur
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.014
      Issue No: Vol. 546 (2017)
       
  • Conversion of n-hexane and n-dodecane over H-ZSM-5, H-Y and Al-MCM-41 at
           supercritical conditions
    • Authors: Benjamin Huang; Peng Bai; Matthew Neurock; Robert J. Davis
      Pages: 149 - 158
      Abstract: Publication date: 25 September 2017
      Source:Applied Catalysis A: General, Volume 546
      Author(s): Benjamin Huang, Peng Bai, Matthew Neurock, Robert J. Davis
      Catalytic reactions of supercritical n-hexane and n-dodecane were studied over H-ZSM-5, H-Y and Al-MCM-41 at pressures between 4 and 6MPa and temperatures between 558 and 748K, using a combination of experimental and theoretical approaches. The primary reaction for n-hexane conversion over H-ZSM-5 was cracking, whereas the primary reaction over H-Y and Al-MCM-41 was isomerization. In contrast, cracking was the primary reaction of n-dodecane over all of the aluminosilicates. Turnover frequencies (TOFs) for n-hexane and n-dodecane conversion over H-ZSM-5 were much greater than for H-Y and Al-MCM-41 under all tested reaction conditions. The invariance of TOFs for n-hexane conversion over H-ZSM-5 and H-Y over the pressure range studied indicated that the reaction was nearly zero-order in hydrocarbon at the supercritical conditions used here. Configurational-bias Monte Carlo simulations indicate that the loadings of reactant molecules reached only about half of their saturation values at the experimental conditions, but plateaus in the adsorption isotherms of n-hexane in H-ZSM-5 and of n-dodecane in both H-ZSM-5 and H-Y zeolites account for the nearly zero-order kinetics. At supercritical conditions, the apparent activation energy of n-dodecane cracking over H-ZSM-5, H-Y and Al-MCM-41 as well as that for n-hexane cracking over H-ZSM-5 was associated with the rate constant for CC bond cleavage (156–200kJmol−1). Density-functional theory calculations show that for n-hexane conversion over H-ZSM-5, β-scission from the bound alkoxide possesses the highest barriers, ranging from 167–177kJmol−1 depending on the mode of cracking. The intrinsic activation barriers for isomerization and hydride transfer reactions were calculated to be significantly lower, at 94 and 96–124kJmol−1, respectively, although still higher than the experimentally observed value of 74±6kJmol−1 for n-hexane conversion over H-Y. Rate expressions derived for monomolecular cracking, bimolecular cracking, and isomerization reactions suggest that the differences between the apparent barriers determined experimentally and the intrinsic barriers calculated theoretically are likely due to the competing hydrocarbon adsorption or quasi-equilibrated exothermic reaction steps. The increased selectivity to cracking over isomerization for n-hexane in H-ZSM-5 was attributed to the difficulty of product removal from the zeolite and, for n-dodecane, to the greatly reduced β-scission barriers and the much stronger product adsorption.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.07.027
      Issue No: Vol. 546 (2017)
       
  • Variability of particle configurations achievable by 2-nozzle flame
           syntheses of the Au-Pd-TiO2 system and their catalytic behaviors in the
           selective hydrogenation of acetylene
    • Authors: Boontida Pongthawornsakun; Okorn Mekasuwandumrong; Francisco J.Cadete Santos Aires; Robert Büchel; Alfons Baiker; Sotiris E. Pratsinis; Joongjai Panpranot
      Abstract: Publication date: Available online 12 September 2017
      Source:Applied Catalysis A: General
      Author(s): Boontida Pongthawornsakun, Okorn Mekasuwandumrong, Francisco J.Cadete Santos Aires, Robert Büchel, Alfons Baiker, Sotiris E. Pratsinis, Joongjai Panpranot
      Catalysts with Au and Pd supported on TiO2 (Au:Pd 1:1wt/wt%) were prepared by 1- and 2-nozzle flame spray pyrolysis (FSP). The 2-nozzle configuration allowed to synthesize various particle configurations by separate or co-feeding of the metal precursor solutions to the two nozzles. For the Au-Pd/TiO2 system, four different catalyst particle configurations were investigated: “TiO2 +AuPd”, “Pd/TiO2 +Au”, “Au/TiO2 +Pd”, and “Pd/TiO2 +Au/TiO2”, where+separates the corresponding precursor solutions fed to the two nozzles. There were no significant differences in the specific surface areas and the average TiO2 crystallite sizes of the catalysts (100m2/g and 16–17nm, respectively) with the exception of “Pd/TiO2 +Au/TiO2”, which exhibited larger surface area and smaller crystallite size (152m2/g, 12nm) due to halving of the Ti precursor concentration in each nozzle. As revealed by CO chemisorption, XPS, and STEM-EDX results, the catalyst properties varied largely in terms of bimetallic AuPd particle compositions, the interaction between metal–metal and metal-support, and the location of Pd (or AuPd) on the TiO2. Among the catalysts studied, “TiO2 +AuPd” prepared with the 2-nozzle system exhibited the highest conversion of acetylene (∼50%) at 40°C with high selectivity to ethylene (>95%). Co-feeding the noble metal precursors together with the Ti precursor afforded less active catalysts due to the formation of Ti-O species partially covering the most active bimetallic AuPd particles. Compared to the commercially available acetylene hydrogenation catalyst and the AuPd/TiO2 prepared by conventional co-impregnation and deposition-precipitation, all the FSP-AuPd/TiO2 catalysts showed superior performances under the reaction conditions used.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.014
       
  • Heteropoly acid supported on silicalite−1 possesing intracrystalline
           nanovoids prepared using biomass − an efficient and recyclable catalyst
           for esterification of levulinic acid
    • Authors: K. Manikandan; K.K. Cheralathan
      Abstract: Publication date: Available online 6 September 2017
      Source:Applied Catalysis A: General
      Author(s): K. Manikandan, K.K. Cheralathan
      Graphical abstract image

      PubDate: 2017-09-08T03:35:11Z
      DOI: 10.1016/j.apcata.2017.09.007
       
  • 5-Hydroxymethylfurfural Catalytic Oxidation Under Mild Conditions by Co
           (II), Fe (III) And Cu (II) Salen Complexes Supported on SBA-15: Synthesis,
           Characterization and Activity
    • Authors: Daniela Xulú Martínez-Vargas; Javier Rivera De La Rosa; Ladislao Sandoval-Rangel; Jorge Luis Guzmán-Mar; Marco A. Garza-Navarro; Carlos J. Lucio-Ortiz; David A. De Haro-Del Río
      Abstract: Publication date: Available online 1 September 2017
      Source:Applied Catalysis A: General
      Author(s): Daniela Xulú Martínez-Vargas, Javier Rivera De La Rosa, Ladislao Sandoval-Rangel, Jorge Luis Guzmán-Mar, Marco A. Garza-Navarro, Carlos J. Lucio-Ortiz, David A. De Haro-Del Río
      In the present work, an alternative system of 5-hydroxymethylfurfural (HMF) oxidation was studied, in an effort to avoid the use of expensive precious metal catalysts, high pressures and systems not environmentally friendly. The catalysts tested were Co (II), Fe (II) and Cu (II) Salen complexes supported on SBA-15 (Co Salen/SBA-15, Fe Salen/SBA-15 and Cu Salen/SBA-15 respectively). The reaction was carried out in aqueous medium at room temperature (25°C ±1) and atmospheric pressure, using hydrogen peroxide (H2O2) as the only oxidant agent. The effect of various reaction conditions such as H2O2 content, oxidant agent amount, different transition metals present in the catalyst and temperature were evaluated. The HMF and the reaction products such as; 2,5-diformylfuran (DFF), 2,5-furandicarboxylic acid (FDCA), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) and 5-formyl-2-furancarboxylic acid (FFCA) were followed by high performance liquid chromatography (HPLC) measurements. The selectivity and reaction kinetics under different reaction conditions was studied. The different synthesized catalysts were extensively characterized by UV-vis spectroscopy, subsequently by FTIR, DR-UV-vis, AA and XPS spectroscopy and through nitrogen physorption, which was related to its catalytic activity. The successful synthesis of SBA-15 support was confirmed by its textural properties and STEM. From the experimental data obtained a reaction mechanism with parallel reactions was proposed founding that the oxidation route of the alcohol group in HMF is favored over of the oxidation of the aldehyde group on the other side of the molecule.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.035
       
  • Application of Magnetic Resonance Imaging and Raman Imaging to study the
           impact of phosphorus in impregnation of hydrotreatment catalysts
    • Authors: L. Catita; A.-A. Quoineaud; D. Espinat; C. Pichon; O. Delpoux
      Abstract: Publication date: Available online 30 August 2017
      Source:Applied Catalysis A: General
      Author(s): L. Catita, A.-A. Quoineaud, D. Espinat, C. Pichon, O. Delpoux
      Magnetic Resonance Imaging is applied, for the first time, to monitor in-situ the impregnation step of hydrotreatment catalysts with an aqueous solution composed simultaneously of molybdenum, cobalt and phosphorus. This technique provides information about spatial distribution of all metal precursors inside the catalyst pellet with a significantly improved spatial resolution of 39μm×39μm compared to the literature. Streamline Raman Imaging yields complementary information about molybdenum speciation at equilibrium. For a molybdenum based catalyst, a slow transport of molybdenum complexes through γ-alumina is observed by Magnetic Resonance Imaging, which suggests a strong interaction between metal precursor and the support. Presence of polymeric molybdenum ions is found near the edges as well as the formation of an Anderson-type heteropolyanion. In the presence of phosphorus, interaction between molybdenum and γ-alumina is weaken since a preferential adsorption to phopshorus is observed. This phenomenon results in an increase in the transport rate of molybdenum complexes. When phosphorus is added to a molybdenum based catalysts promoted by cobalt, preferential interactions between metal promotor and the support are observed rather than with molybdenum species. This innovative Magnetic Resonance Imaging −Streamline Raman Imaging methodology allows a better control of the deposition process during impregnation and to identify the descriptors that most influence this preparation step. Finally, this methodology can be applied to other type of supported catalysts.
      Graphical abstract image

      PubDate: 2017-09-02T10:48:31Z
      DOI: 10.1016/j.apcata.2017.08.039
       
 
 
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