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  Subjects -> ENGINEERING (Total: 2312 journals)
    - CHEMICAL ENGINEERING (196 journals)
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    - ELECTRICAL ENGINEERING (104 journals)
    - ENGINEERING (1213 journals)
    - ENGINEERING MECHANICS AND MATERIALS (389 journals)
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ENGINEERING (1213 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: 7)
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: 255)
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: 9)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 18)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 11)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 10)
Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 30)
Advances in Operations Research     Open Access   (Followers: 12)
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: 5)
Advances in Remote Sensing     Open Access   (Followers: 40)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 2)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
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: 17)
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: 8)
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: 18)
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   (Followers: 1)
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: 5)
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: 8)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
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: 9)
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: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 24)
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: 4)
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 10)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
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   (Followers: 1)
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: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 30)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 4)
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: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
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: 24)
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: 4)
Cogent Engineering     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 2)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
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: 27)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 272)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 199)
Composites Part B : Engineering     Hybrid Journal   (Followers: 256)
Composites Science and Technology     Hybrid Journal   (Followers: 193)
Comptes Rendus Mécanique     Full-text available via subscription   (Followers: 2)
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (Followers: 15)
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: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computers & Geosciences     Hybrid Journal   (Followers: 30)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 7)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 6)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 33)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 8)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 9)
Control Engineering Practice     Hybrid Journal   (Followers: 43)
Control Theory and Informatics     Open Access   (Followers: 8)
Corrosion Science     Hybrid Journal   (Followers: 25)
Corrosion Series     Full-text available via subscription   (Followers: 6)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)

        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  [3123 journals]
  • Ammonia synthesis over Cs- or Ba-promoted ruthenium catalyst supported on
           strontium niobate
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Minxuan Chen, Mingwei Yuan, Jinjun Li, Zhixiong You
      Strontium niobates with different crystalline structure and morphology have been prepared via a hydrothermal method and applied as a support for ruthenium catalyst in ammonia synthesis. The sample synthesized with a nominal Sr/Nb = 2.0, having a pure Sr2Nb2O7 crystalline phase and specific surface area of 87 m2 g−1, exhibits the best performance as support for Ru catalyst. The flake-structured Sr2Nb2O7 substrate induced epitaxial growth of truncated pyramid shaped ruthenium nanoparticles with a dispersion as high as 93%, which have abundant steps and B5 sites playing a key role in ammonia synthesis catalysis. Adding Cs- or Ba-promoter enhanced the activity of Ru/Sr2Nb2O7 catalyst drastically. The highest ammonia synthesis rate over 8Cs- or 4Ba-2 wt%Ru/Sr2Nb2O7 was 4986 and 2317 (μmol g−1 cat h−1) at 0.1 MPa and 673 K, respectively. In addition, both catalysts were stable over reaction for 72 h at 673 K and 0.1 MPa. Thus, the synthesized Sr2Nb2O7 is expected to be a practically promising oxide support for ruthenium ammonia synthesis catalsyts.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Identification of carbon species on iron-based catalysts during
           Fischer-Tropsch synthesis
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Diego Peña, Andrea Cognigni, Thomas Neumayer, Wouter van Beek, Debra S. Jones, Melesio Quijada, Magnus Rønning
      This paper focuses on the use of in situ and ex situ characterisation techniques to provide evidences of carbon species on a commercial iron-based Fischer-Tropsch synthesis catalyst as well as other indices of potential deactivation mechanisms. In situ XANES measurements demonstrate that re-oxidation or transformation of the active iron phase, i.e. the Hägg carbide phase, was not a significant deactivation mechanism at the studied conditions. Sintering of Hägg carbide nanoparticles is significant with increasing temperatures and time on stream. The sintering mechanism is proposed to be a hydrothermally-assisted process. In situ DRIFTS indicates the presence of different carbon species on the catalyst surface such as aliphatic hydrocarbons from wax products and oxygenate compounds such as alcohols, aldehydes/ketones and carboxylate species. Carboxylate species are resistant towards hydrogenation at 280 °C. The presence of different carbon species on the surface after wax product extraction is evident from TPH-MS measurements. GC-MS analysis shows that the strongly adsorbed carbon species remaining on the catalyst surface from wax products are mainly α-olefins and branched carboxylic species. The interaction of oxygenate compounds, especially carboxylate species with iron oxide, may form stable complexes limiting further iron catalyst carburization. STEM-EDX analysis shows that carbon is preferentially located on iron particles.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Palladium-silver polyaniline composite as an efficient catalyst for
           ethanol oxidation
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Zahra Nodehi, Amir Abbas Rafati, Ali Ghaffarinejad
      In recent years bi-metallic materials have shown promising effect as potential catalyst layer in the fuel cells. Here, for the first time, bimetallic Ag-Pd were electrodeposited on polyaniline/glassy carbon electrode (PANI/GCE) via the constant current method, which used as efficient electrode for ethanol oxidation reaction (EOR) in alkaline media. Some important parameters including applied current, deposition time and metal ratio were optimized. The obtained bimetallic AgPd/PANI/GCE catalyst showed improved catalytic performance for ethanol conversion compared with the Pd/PANI/GCE, Pd/GCE, Ag/PANI/GCE, and PANI/GCE. The catalytic enhancement is due to the synergic effect between Ag, Pd and PANI. Moreover, the proposed AgPd composite was deposited on the carbon fiber cloth (CC) to evaluate its applicability as an anode in ethanol fuel cell. To summarize, the good electrochemical performance and easy preparation make the obtained Ag-Pd bimetallic composite as a potential candidate for alkaline ethanol fuel cell.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Understanding the photocatalytic degradation by P25 TiO2 of acetic acid
           and propionic acid in the pursuit of alkane production
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Lynn M. Betts, Frederic Dappozze, Chantal Guillard
      Towards the application of harvesting valuable hydrocarbon products from wastewater and associated fermentation processes, the traditional P25 Degussa TiO2-assisted decarboxylation of simple carboxylic acid substrates - in this case acetic and propionic acids – was re-examined for its alkane production capacity. Avoiding doping or the introduction of other elements into the commercially available TiO2 lattice, we modified other parameters of the reaction not yet explored. Under nitrogen, highly concentrated (50%) and pure (100%) solutions of both acetic acid and propionic acid demonstrated good selectivity for the decarboxylation over any other side reaction or complete mineralization, nearing or exacting a 1:1 hydrocarbon/CO2 ratio in each case. This behaviour proves that the direct reaction of h+ with the acid in either case is the key parameter to favour this selectivity. In the case of acetic acid, methane’s yield was increased significantly by the periodic aeration of the catalyst when exhausted under nitrogen. The modification of solution pH to more physiological and fermentation-compatible levels (pH of 6.0) lead to improve the selectivity and the ethane’ yield in 50% propionic acid degradation and also resulted in virtually no unidentified carbon products. The Photo-Kolbe coupling and dehydration products, meanwhile, were favoured in the less concentrated solutions, suggesting that more dilute solutions may be more promising for deriving longer length hydrocarbons from substrates of smaller size. Mechanistically, these results also implicate that OH° radicals are at the origin of product generation by way of Photo-Kolbe coupling and dehydration. Finally, acetic acid and propionic acid were degraded simultaneously, in which the latter was degraded preferentially or at least initially before the former, along with the appearance of propane as a result of cross-coupling.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Highly porous monolith/TiO2 supported Cu, Cu-Ni, Ru, and Pt catalysts in
           methanol steam reforming process for H2 generation
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Pooya Tahay, Yasin Khani, Mohammad Jabari, Farzad Bahadoran, Nasser Safari
      A comprehensive investigation on the steam reforming of methanol (SRM) process using a microstructure monolith in conjunction with a synthesized nanostructure of TiO2 is presented. The surface of the designed monolith/TiO2 structure was coated with copper, copper/nickel, ruthenium, and platinum as the catalyst. The prepared catalysts were then characterized with FE-SEM, AFM, BET surface area measurement, FT-IR, far-infrared, temperature programmed reduction (TPR), and X-ray diffraction (XRD). The obtained results show that in this process, the designed Monolith/TiO2 structure has a remarkable impact on methanol conversion (99%) and carbon monoxide selectivity (5%). These results are interpreted by the high surface area and superb mass transfer in this micro/nano engineered structure. These results also indicated that the catalyst activity and dispersion are influenced by the metal-support interaction, which is more pronounced in the TiO2 supports. The ruthenium catalyst presented the highest conversion and selectivity for this process. However, the economically viable property of the Cu-Ni catalyst supposes it as an alternative for the noble ruthenium catalyst.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • TiO2 Supported gold–palladium catalyst for effective syngas production
           from methane partial oxidation
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Zhu Luo, David A. Kriz, Ran Miao, Chung-Hao Kuo, Wei Zhong, Curtis Guild, Junkai He, Bill Willis, Yanliu Dang, Steven L. Suib, Partha Nandi
      The CO and H2 (syngas) production from methane partial oxidation (MPO) using TiO2 supported Au-Pd bimetallic catalysts are discussed. The supported Au, Pd and Au-Pd bimetallic nanoparticles were prepared by an incipient wetness impregnation or co-impregnation method and were characterized. The supported Au-Pd catalyst was selective for reforming and was more active compared to bare TiO2, TiO2 supported Au only, or Pd only catalysts. The catalyst properties before and after MPO reaction were investigated, including the stability of the TiO2 support, and the stability of Au and Pd nanoparticles. The supported Au-Pd catalyst has the highest TON (TONH2 = 23 at 650 °C), compared to supported Au catalyst (TONH2 < 1) and supported Pd catalyst (TONH2 < 1). Based on the analysis of outlet gases from the MPO reaction in a flow reactor, synergetic effects between Au and Pd, where Pd activates CH bonds while gold modulates the behavior of oxygen at the catalyst surface, are shown to contribute to MPO. Additionally, the Au-Pd/TiO2 material shows long-term activity (>12 h) for the MPO reaction at 600 °C.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Hydrothermal modification of the alumina catalyst for the skeletal
           isomerization of n-butenes
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Ildar N. Mukhambetov, Svetlana R. Egorova, Aliya N. Mukhamed’yarova, Alexander A. Lamberov
      Hydrothermal modification of the alumina catalyst of n-butenes skeletal isomerization was investigated. It is shown that during the hydrothermal treatment of γ-Al2O3 and subsequent calcination its activity in skeletal isomerization of n-butenes first increases, and then it decreases with a rise of the hydrothermal treatment duration. This behavior is due to a similar change in the content of the strong Lewis acid sites of alumina, which are the active centers of reaction and they can be identified by IR-spectroscopy of the adsorbed pyridine and EPR-spectroscopy of the adsorbed anthraquinone. We report the mechanism of new Lewis acid sites formation at the γ-Al2O3 hydrothermal treatment containing X-ray amorphous component.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • New catalysts with dual-functionality for cyclohexane selective oxidation
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Amal A. Alshehri, Abdullah M. Alhanash, Murad Eissa, Mohamed S. Hamdy
      M-Co-TUD-1; a series of the new materials was prepared by applying one-step synthesis procedure based on sol-gel technique. The prepared materials contain 1wt% of cobalt ions and 5wt% of metal oxide (metal = Cr, Cu, Ti, Mn, Bi, V, or Sr) in the TUD-1 mesoporous material. The prepared materials were characterized by using XRD, DRS UV–vis, N2 sorption measurements, ICP elemental analysis, SEM, and HR-TEM. Characterization results showed that all the prepared materials contain isolated Co2+ ions and nanoparticles of Cr2O3, TiO2, MnO, V2O5 or bulky crystals of Bi2O3 and CuO incorporated in the silica matrix. The catalytic performance of the prepared materials was evaluated in liquid phase, free-solvent selective oxidation of cyclohexane to cyclohexanone and cyclohexanol by using TBHP as an oxidant at 70 °C. The prepared materials exhibited higher activity than either Co-TUD-1 or other M-TUD-1. More importantly, a very small concentration of the intermediate; cyclohexyl hydroperoxide (CHHP) was detected. In case of stability, Mn-Co-TUD-1 and Ti-Co-TUD-1 exhibited an excellent stability during the reaction. Moreover, Mn-Co-TUD-1 was successfully recycled up to 4 runs.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Truxillic and truxinic acid-based, bio-derived diesters as potent internal
           donor in Ziegler-Natta catalyst for propylene polymerization
    • Abstract: Publication date: 25 March 2018
      Source:Applied Catalysis A: General, Volume 554
      Author(s): Akanksha Matta, Patchanee Chammingkwan, Brajendra K. Singh, Minoru Terano, Tatsuo Kaneko, Toshiaki Taniike
      In this study, novel α-truxillic and β-truxinic acid-based, bio-derived diesters have been developed as internal donors for preparing Ziegler-Natta (ZN) catalysts. Impacts of these bio-derived diesters were investigated on the chemical composition, the morphology, the mode of adsorption, and the propylene polymerization performance of the catalysts in comparison to the most widely used fourth-generation catalyst containing dibutyl phthalate. The molecular structures of the diesters and the particle morphology of the catalysts were preserved in the catalyst preparation. The bio-derived diesters afforded ZN catalysts with a reasonable activity and stereospecificity in propylene polymerization along with similarly broad molecular weight distribution (MWD) as the phthalate-based catalyst. Another promising feature of the catalysts was an opposite hydrogen response in terms of expansion of MWD upon the addition of H2.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Catalytic oxidation of 1,2-dichloroethane over three-dimensional ordered
           meso-macroporous Co3O4/La0.7Sr0.3Fe0.5Co0.5O3: Destruction route and
           mechanism
    • Abstract: Publication date: 5 March 2018
      Source:Applied Catalysis A: General, Volume 553
      Author(s): Mingjiao Tian, Chi He, Yanke Yu, Hua Pan, Louise Smith, Zeyu Jiang, Ningbo Gao, Yanfei Jian, Zhengping Hao, Qing Zhu
      Three-dimensional ordered meso-macroporous La0.7Sr0.3Fe0.5Co0.5O3 (3DOM LSFCO)-supported Co3O4 catalysts were designed and prepared via a PMMA-templating strategy for the total oxidation of 1,2-dichloroethane (1,2-DCE). The physicochemical properties of all synthesized samples were characterized by XRD, FE-SEM, TEM, HAADF-STEM, low-temperature N2 sorption, XPS, H2-TPR, and in situ FT-IR. The introduction of Co3O4 increases the generation rate of oxygen vacancy, playing a crucial role in adsorption and activation of oxygen species. The special 3DOM structure of perovskite-type oxide promotes 1,2-DCE molecules to effectively and intimately contact with the surface adsorbed oxygen over supported catalysts and further accelerates the redox process. Compared with pure LSFCO, all the Co3O4 supported catalysts show superior catalytic performance with reaction rate increases from 5.53 × 10−12 to 2.29 × 10−11 mol g−1 s−1 and E a decreases from 74.7 to 22.6 KJ mol−1. Amongst, the 10Co3O4/3DOM LSFCO catalyst exhibits the best catalytic activity, highest resistance to chlorine poisoning and lowest by-products concentration because of the largest amount of surface adsorbed oxygen. CO2, CO, HCl, and Cl2 are the main oxidation productions, while some typical reaction intermediates such as vinyl chloride, 1,1,2-trichloroethane and trichloroethylene are also observed, especially over the 3DOM LSFCO sample. Furthermore, the reaction mechanism of 1,2-DCE oxidation over obtained catalysts was proposed based on the results of gas chromatography, in situ FT-IR, and on-line MS. It is believed that the Co3O4/3DOM LSFCO are promising catalysts for the total removal of chlorinated volatile organic compounds.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Hydrodeoxygenation of guaiacol as a model compound of bio-oil in methanol
           over mesoporous noble metal catalysts
    • Abstract: Publication date: 5 March 2018
      Source:Applied Catalysis A: General, Volume 553
      Author(s): E.A. Roldugina, E.R. Naranov, A.L. Maximov, E.A. Karakhanov
      The liquid phase hydrodeoxygenation (HDO) of guaiacol (GUA), a model compound of bio-oil, was studied on bimetallic (PtPd) and monometallic (Ru) catalysts supported on mesoporous aluminosilicate of Al-HMS(X) type with different Si/Al (X) ratios and on mesoporous zirconia modified with silica (m-ZrO2-SiO2) in the presence of methanol as a solvent. The catalysts were characterized by NH3-TPD, TEM, XPS, 27Al and 29Si solid-state NMR and N2 adsorption–desorption methods. The influence of сatalyst loading, temperature, solvent/guaiacol ratio and contact time on the catalytic performance was investigated. It was established that, decreasing the Si/Al ratio and, correspondingly, increasing the acidity of the catalysts based on Al-HMS led to increasing conversion of guaiacol. Phenol, catechol, and their methylated derivatives were the main products of guaiacol HDO reaction in methanol at low catalyst loading (guaiacol/metal ratio, 800). It was found that the fraction of completely hydrodeoxygenated products (cyclohexane and methylcyclohexane) greatly increased as the catalyst loading grew (guaiacol/metal ratio, 160). Conversion of guaiacol on PtPd/m-ZrO2-SiO2 catalyst was higher than that on PtPd/Al-HMS(10), in accordance with the larger number of acid sites on the catalyst surface; however, the undesirable heavy fraction of methylated by-products was also higher. Ru-based catalysts exhibited the highest catalytic activity and showed unusually high selectivity toward fully hydrodeoxygenated products (cyclohexane, methylcyclohexane) in the HDO of guaiacol in the presence of methanol. Guaiacol can be efficiently converted into alkanes, with quantitative conversion and selectivity to cyclohexanes of 78% over Ru/Al-HMS(10) catalyst under relatively mild conditions (200 °C, 5 MPa H2). Methylation under the influence of methanol, deoxygenation on acid sites and aromatic ring hydrogenation on metal sites proceeded in a parallel way according to the suggested reaction pathways.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Study of NO removal and resistance to SO2 and H2O of MnOx/TiO2, MnOx/ZrO2
           and MnOx/ZrO2–TiO2
    • Abstract: Publication date: 5 March 2018
      Source:Applied Catalysis A: General, Volume 553
      Author(s): Bohan Jia, Jiaxiu Guo, Hongdi Luo, Song Shu, Ningjie Fang, Jianjun Li
      MnO x /TiO2, MnO x /ZrO2 and MnO x /ZrO2–TiO2 were prepared by impregnation and NO removal was evaluated in a fixed‒bed reactor under simulated reactive gas. All samples were characterized by various technologies. The results showed that MnO x /ZrO2–TiO2 had good selective catalytic reduction activity between 80–360 °C and excellent resistance to H2O at 200 °C for 30 h and achieved 80% NOx removal efficiency at 140 °C. The NO removal efficiency of MnO x /ZrO2 was only 45–80%, and that of MnOx/TiO2 was 100% at 240–360 °C. However, their tolerance to H2O was not as good as MnO x /ZrO2–TiO2. When SO2 was induced into reactive gas, the NO removal efficiency of MnO x /ZrO2 at 200 °C was maintained 70% for 34 h, but that of MnO x /TiO2 decreased rapidly. MnO x /ZrO2–TiO2 maintained 100% NO removal efficiency for 5 h and decreased gradually. After SO2 was stopped, NO removal ability wasn’t recovered, indicating that deactivation of catalyst was irreversible. TiO2 can improve the texture properties, and the surface area and total pore volume of MnO x /TiO2 reached 313 m2/g and 0.38 m3/g. The existence of zirconium oxide significantly increased the concentration of Mn4+ and Oβ on the surface of catalysts. MnO x /ZrO2–TiO2 had wide surface acidity, which improved NH3 adsorption. After SO2 resistance testing, Mn4+ content on the surface of catalysts decreased whereas Mn3+ obviously increased. SO2 could be oxidized by MnO x to SO3, and SO3 was adsorbed on ZrO2 or TiO2 to form zirconium sulfate or titanyl sulfate. (NH4)2SO4 was formed on singe ZrO2 or TiO2 carrier. These sulfates increased the surface acidity, resulting in a change of NO removal ability.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Dual catalysis over ZnAl mixed oxides in the glycerolysis of urea:
           Homogeneous and heterogeneous reaction routes
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Huy Nguyen-Phu, Chan-yi Park, Eun Woo Shin
      In this work, we prepared ZnO, ZnAl2O4, and ZnAl mixed oxides with different metal molar ratios and applied them for synthesizing glycerol carbonate (GC) from glycerol and urea. The reaction routes related to the Zn species over the ZnAl mixed oxides were investigated. The ZnAl mixed oxides were found to consist of two Zn crystalline phases: ZnO and ZnAl2O4. From the reaction results, the ZnAl mixed oxides showed much higher glycerol conversion and GC yield than the ZnO and ZnAl2O4. During the reaction, the dissolution of the Zn species from the ZnO phase over the ZnAl mixed oxides was observed while the ZnAl2O4 phase remained insoluble. The ZnO phase provided a homogeneous reaction route via the dissolved Zn species, resulting in the formation of a Zn complex containing the isocyanate (NCO) and zinc glycerolate. In contrast, the insoluble ZnAl2O4 phase was responsible for not only a heterogeneous reaction route, but also adsorption of the Zn NCO complex on the catalyst. We proposed that the adsorbed Zn NCO complex could play a role as an active site for an additional heterogeneous reaction route. Therefore, the ZnAl mixed oxides exhibited high GC yields through the dual catalysis routes: the homogeneous reaction route over the ZnO phase and the heterogeneous reaction route over the ZnAl2O4 phase.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Effect of Si/Al2 ratios in Mo/H-MCM-22 on methane dehydroaromatization
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Tae Hwan Lim, Kihun Nam, In Kyu Song, Kwan-Young Lee, Do Heui Kim
      A series of Mo(5)/H-MCM-22 catalysts with various Si/Al2 ratios were applied to methane dehydroaromatization reaction. According to the NH3 TPD, XPS, TPO, UV Raman and STEM-EDS analysis, it is clearly verified that Brønsted acid site, determined by the Si/Al2 ratios, stabilizes monomeric Mo oxide species, by facilitating to migrate Mo oxides into the microchannel of zeolite, so that it can influence the distribution of catalytically active Mo oxide species. Combined TPO and UV Raman analysis of post-reaction catalysts obviously confirmed that HT (high temperature) type coke is primarily composed of polyaromatics such as naphthalene and anthracene, which brings about the deactivation of the catalyst during MDA reaction. The formation of HT type coke is mainly affected by the amount of Mo oxides present on the external surface of zeolite, which indicates that the major role of zeolite microchannel is to provide a shape-selective environment during the conversion of methane to benzene. To sum up, an increment in Brønsted acid site enhances the dispersion of Mo oxides, thus leading to the improved methane conversion rate and benzene formation rate while suppressing the formation of HT type coke concomitantly.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Hydrotalcite-derived Co/Mg(Al)O as a stable and coke-resistant catalyst
           for low-temperature carbon dioxide reforming of methane
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Dalin Li, Shuping Xu, Kai Song, Chongqi Chen, Yingying Zhan, Lilong Jiang
      The Co catalyst using hydrotalcite-derived Mg(Al)O as support shows promising catalytic activity for low-temperature CH4-CO2 reforming. Under a wide range of reaction conditions, that is T = 773–1023 K, CH4/CO2/N2 = 25/25/50–50/25/25, WHSV = 60,000–120,000 mL h−1 g−1, and TOS = 25–200 h, the Co catalyst exhibits stable activity and high coke resistance. The performance is superior to the Ni counterpart which readily deactivates at 773 K due to severe coke deposition. The initial coking rate on the Co catalyst was estimated to be about 1/20 times that on the Ni catalyst. The kinetic study suggests that the dissociative adsorption of CH4 is favored on the Ni catalyst, whereas the Co catalyst has high affinity for CO2 adsorption. The results of CH4-TPSR and direct CH4 decomposition experiments further reveal that the Co catalyst is much less active for carbon formation through CH4 decomposition. It is deduced that a combination of lower activity for CH4 dissociation/decomposition and higher affinity for CO2 adsorption as well as a stronger metal-support interaction is responsible for the higher coke resistance of the Co catalyst.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Formation of NH3 and N2O in a modern natural gas three-way catalyst
           designed for heavy-duty vehicles: the effects of simulated exhaust gas
           composition and ageing
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Pauliina Nevalainen, Niko M. Kinnunen, Anna Kirveslahti, Kauko Kallinen, Teuvo Maunula, Matthew Keenan, Mika Suvanto
      An increasing number of heavy-duty vehicles are using liquefied natural gas (LNG) as a fuel due to the expanding refuelling station network for LNG and lower overall emissions compared to diesel vehicles. The latest EURO VI regulation or natural gas fuelled vehicles set a limit for NH3 of 10 ppm, and N2O exhaust is expected to be restricted in Europe in the near future. Poisonous and corrosive NH3 and the greenhouse gas N2O are formed as by-products in a three-way catalyst used to minimize the emissions of stoichiometric heavy-duty engines. In this work, we studied how high temperature NH3 and N2O formed in modern, fresh and aged bimetallic Pd/Rh three-way catalysts in simulated exhaust gas. More precisely, the exhaust gas composition and temperature were examined. Decreases in NO concentration and increases in temperature lowered the formation of NH3 and N2O, whereas a decrease in CH4 concentration reduced only NH3 formation. According to Raman and powder X-ray diffraction experiments, the structure of the catalyst changed during the ageing, and this reputedly affected the function of cerium-zirconium mixed oxides and thus the formation of NH3 and N2O. Temperature programmed reduction (H2-TPR) measurements showed changes in cerium-zirconium mixed oxide performance after ageing supporting Raman spectroscopy findings. Catalyst ageing in oxidizing conditions increased the formation of N2O. This study showed that exhaust gas composition plays an important role in the formation of undesired NH3 and N2O emissions.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Promoting deoxygenation of triglycerides via Co-Ca loaded SiO2-Al2O3
           catalyst
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): N. Asikin-Mijan, H.V. Lee, J.C. Juan, A.R. Noorsaadah, Hwai Chyuan Ong, S.M. Razali, Y.H. Taufiq-Yap
      Triglycerides and fatty acid derivatives can be converted to hydrocarbon-grade green diesel that are entirely fungible to the fossil fuels. In the present study, deoxygenation (DO) process of triolein was studied by using mesoporous SiO2-Al2O3 supported Co-Ca catalyst. The presence of active metals (Co-Ca) showed high DO activity exclusively via decarboxylation/decarbonylation (deCOx) pathways with maximum hydrocarbon n-(C8-C20) yield of 73%, and high selectivity of n-C15 and n-C17 fractions. This results suggested the acid-base active sites of catalyst provide selective deCOx pathway of triglycerides structure. In additional, the presence of high surface area of Co-Ca/ SiO2-Al2O3 enhance the metal dispersion for better accessment of large molecular reactant with catalyst during DO process. An optimum Co metal content (10 wt.%) for deCOx reaction was observed, while an excess Co content is not preferable due to tendency of cracking effect. The efficiency of Co-Ca/SiO2-Al2O3 was investigated by using non-edible feedstock (e.g. Ceiba oil and Sterculia oil) along with catalyst stability study were carried out. Resulst also indicated that degradation of DO activity was due to the formation of coke.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Ethyl benzene oxidative dehydrogenation to styrene on Al-B and Al-B-Sb
           catalysts
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Abdulrahim A. Al-Zahrani, Nagaraju Pasupulety, Muhammad A. Daous, Hafedh Driss, Arshid M. Ali, Sharif F. Zaman, Lachezar A. Petrov
      Alumina (Al), alumina-boron (Al-15B), alumina-boron-antimony (Al-B-Sb) and alumina-antimony (Al-15Sb) catalysts were synthesized by sol-gel method using ethanol as a solvent and ammonia gas as a gel forming agent. These catalysts were studied for the dehydrogenation of ethylbenzene (EB) to styrene in the presence of oxygen and steam. The reaction was carried out in the temperature range of 450-500 °C with EB contact time 0.54 gcat.s/cm3. The synthesized catalysts were characterized by using N2-physisorption, XRD, XPS, TEM-HRTEM-EDS and NH3-TPD-mass spectral analysis techniques. At 475 °C, only 58% of styrene selectivity with 32% of EB conversion was observed on Al. Addition of 15 mol.% of B to Al significantly enhanced the selectivity of styrene to 94% with 46% EB conversion at 475 °C. Addition of 15 mol.% Sb to Al reduced the EB conversion (38%) and styrene selectivity (75%) compared to Al-15B catalyst. Interestingly, small amount of Sb (5 mol.%) addition to Al-B improved the EB conversion to 52.5% with 92% of styrene selectivity at 475 °C. The acid sites of weak and moderate strength were increased in Al-15B catalyst compared to Al. Boron played a dual role as Al densification suppressing agent and to some extent deposited on the surface of Al which improved the styrene selectivity. However, small amount of Sb addition to Al-15B not only retained weak and moderate strength acid sites of Al-B but also generated acid sites of Sb which led to the formation of N2O and NO during NH3-TPD-mass analysis. Hence, the styrene yield (48.8%) was improved on Al-B-5Sb compared to Al-15B catalyst (43%). It is noteworthy that Al-15B and Al-B-5Sb catalysts were stable for more than 60h of reaction.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Low temperature prepared copper-iron mixed oxides for the selective CO
           oxidation in the presence of hydrogen
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): M.P. Yeste, H. Vidal, A.L. García-Cabeza, J.C. Hernández-Garrido, F.M. Guerra, G.A. Cifredo, J.M. González-Leal, J.M. Gatica
      Copper-iron mixed oxides with Fe/Cu molar ratios ranging from pure CuO to Fe2O3 were synthesised by a low temperature co-precipitation method, and tested in the CO-PROX reaction. The extensive characterization performed by means of different techniques showed the progressive variation of physical and chemical properties including composition, texture, structure and reducibility of the prepared oxides. Rietveld analysis of X-ray diffraction data, XPS and Raman spectra, and especially TEM study revealed the formation of CuFe2O4. All the samples were more active and selective below 200 °C than a commercial Pt/Al2O3 catalyst used as a reference. In particular, the catalyst having a 2 Fe/Cu molar ratio, corresponding to the cuprospinel stoichiometry, exhibited the best performance with a 76% conversion and a 60% selectivity at 125 °C, operating with 50% of H2 in the gas stream, being relatively stable in long-term time-on-stream experiments. On the contrary, pure CuO rapidly deactivated in the course of reaction at 150 °C. Differences in catalytic stability were related to a promoting effect of iron in the mixed oxide which makes copper more resistant to full reduction.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Photocatalytic synthesis of 2,5-diformylfuran from 5-hydroxymethyfurfural
           or fructose over bimetallic Au-Ru nanoparticles supported on reduced
           graphene oxides
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Ben Ma, Yingyong Wang, Xiaoning Guo, Xili Tong, Chang Liu, Yunwei Wang, Xiangyun Guo
      The photocatalytic conversion of biomass to renewable fuels and chemicals is significant for the sustainable development of energy resources. Herein we report that bimetallic Au-Ru nanoparticles supported on reduced graphene oxides (rGO) exhibit excellent photocatalytic performances for the synthesis of 2,5-diformylfuran (DFF) from partial oxidation of 5-hydroxymethyfurfural (HMF) or one-pot conversion of fructose in the absence of any bases, and the yield of DFF can reach as high as 91% and 86%, respectively. Comparing with rGO-supported monometallic Au or Ru catalysts, the Au-Ru/rGO catalyst shows higher photocatalytic activity due to the transfer of photo-excited electrons from Ru to Au nanoparticles through the conductive graphene support. Since the Au-Ru/rGO catalyst can utilize abundant solar energy, avoid the usage of bases and demonstrate high selectivity and good reusability, the present work provides a green, economical and efficient synthetic route for DFF production.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Effect of cobalt loading on structure and catalytic behavior of CoOx/SiO2
           in CO2-assisted dehydrogenation of ethane
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Rajesh Koirala, Olga V. Safonova, Sotiris E. Pratsinis, Alfons Baiker
      Structural and catalytic properties of flame-made CoOx/silica catalysts for the CO2-assisted dehydrogenation of ethane were observed to vary strongly depending on the Co-loading (0.1–4.5 wt%). X-ray diffraction showed that both fresh and spent catalysts were amorphous. UV–vis, XPS and XAS indicated that at Co-loadings lower than about 1 wt% highly dispersed tetrahedral Co2+ strongly bound to the silica matrix in a cobalt silicate like mixed oxide phase, was the prevalent cobalt species. At higher Co-loadings the presence of CoOx clusters became significant. All cobalt species showed strong resistance towards reduction, as shown by TPR. Comparative XAS analyses of catalysts exposed to ambient atmosphere and thermally pretreated catalysts (400 °C, vacuum for 2 h) showed that the presence of water facilitates the transformation of tetrahedrally to octahedrally coordinated Co2+. Best catalytic performance was achieved with a catalyst containing 0.75 wt% Co, affording 46% ethane conversion at 85% selectivity to ethene under the standard reaction conditions applied (700 °C, CO2/C2H6 ratio of 2.5 and gas hourly space velocity of 6000 L kg−1 h−1). Some coke deposition in the form of disordered and graphitic carbon was observed with all Co-loaded catalysts. The catalyst with optimal Co-loading (0.75 wt%) showed nearly stable performance during 10 h time-on-stream.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Mg/Ga mixed-oxide catalysts for phenol methylation: Outstanding
           performance in 2,4,6-trimethylphenol synthesis with co-feeding of water
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Tommaso Tabanelli, Stefano Cocchi, Bianca Gumina, Lorella Izzo, Massimo Mella, Sauro Passeri, Fabrizio Cavani, Carlo Lucarelli, Jan Schütz, Werner Bonrath, Thomas Netscher
      In this paper, we report on a new catalyst type based on Mg/Ga/O for the gas-phase methylation of phenol with the aim of obtaining the synthesis of 2,4,6-trimethylphenol. This catalyst showed an outstanding performance compared to similar catalysts reported in the literature, with high yield to the desired product. Reasons for this excellent performance were related to the high activity in methanol dehydrogenation to formaldehyde, which is the rate-limiting step in the multi-step (but one-pot) process, as well as to the moderate acidic features due to Ga sites, which enhanced the intramolecular rearrangement of O-alkylated compounds. The surprising role for co-fed steam, which greatly enhanced the selectivity to 2,4,6-trimethylphenol, was also investigated, combining reactivity experiments, in-situ FT-IR spectroscopy, and DFT calculations. It was found that the co-adsorption of water significantly affects the chemo-selectivity of the reaction, thus decreasing the formation of O-alkylated compounds in favour of the desired C-alkylated compounds. Reasons for catalyst deactivation were also studied.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Oxidation of aromatic oxygenates for the production of terephthalic acid
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Konstantinos A. Goulas, Mika Shiramizu, James R. Lattner, Basudeb Saha, Dionisios G. Vlachos
      We study the production of terephthalic acid (TA) from biomass-derived aromatic oxygenates. Among several heterogeneous catalysts tested, a carbon-supported Ir catalyst in 4-heptanone solvent gives the best TA yield from 1,4-dihydroxymethylbenzene. A maximum 76% TA yield is achieved at 100 °C and 12 bar O2. Based on kinetic measurements, we show that the reaction progresses in two distinct pathways. First, the alcohol groups of the substrate are converted to the aldehydes via an O-assisted dehydrogenation pathway over Ir, and then the aldehydes are oxidized to the acid in the solution via a free radical mechanism. We demonstrate that it is easier to oxidize aromatic diols than p-xylene over a heterogeneous catalyst, and thus, the biomass route to TA may be an attractive alternative to the commercial crude oil-based process.
      Graphical abstract image

      PubDate: 2018-02-05T12:18:42Z
       
  • Re-promoted Ni-Mn bifunctional catalysts prepared by microwave heating for
           partial methanation coupling with water gas shift under low H2/CO
           conditions
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Xinxin Dong, Baosheng Jin, Yiqing Sun, Kun Shi, Lei Yu
      Re-promoted Ni-Mn bifunctional catalysts were prepared by microwave and conventional heating separately, and tested for partial methanation coupling with water gas shift (WGS) of simulated biomass gas in a fixed bed reactor. A series of characterization techniques including N2 isothermal adsorption, XRD, H2-TPR, H2-TPD, SEM, TEM and XPS were employed to examine the physico-chemical properties of the catalysts. With the reaction condition of 350 °C, H2/CO = 0.8 and H2O/CO = 1, 82.6% CO conversion, 70.0% CH4 selectivity and 82.8% CO2 growth rate were obtained on the Ni-Mn/Re-Al2O3 (MV) catalyst, which indicated its excellent synergetic effect on partial methanation coupling with WGS. According to the characterization results, it was found that microwave heating was beneficial to increase the dispersion of Ni species in comparison with conventional heating and the addition of Re promoter elevated the catalytic performance from both structural and electronic aspects, which was proven by the lowered reduction temperature of β-type NiO and the intensified electron cloud density of active Ni atoms, respectively. In addition, the sequence of Re impregnation also had impact on the catalytic performance. Step impregnation prepared Ni-Mn/Re-Al2O3 (MV) exhibited larger turnover frequency (TOF) than co-impregnation prepared Ni-Mn-Re/Al2O3 (MV) in the H2/CO range of 0.6–1.0, owing to the larger electron cloud density and better anti-coking ability of the former catalyst. The 110-h lifetime test further demonstrated the potential of stable Ni-Mn/Re-Al2O3 (MV) catalyst in industrial application.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Developing reactive catalysts for low temperature oxidative coupling of
           methane: On the factors deciding the reaction performance of Ln2Ce2O7 with
           different rare earth A sites
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Junwei Xu, Liang Peng, Xiuzhong Fang, Ziyang Fu, Wenming Liu, Xianglan Xu, Honggen Peng, Renyang Zheng, Xiang Wang
      To develop more efficient catalysts that can be operated at low temperature region for oxidative of methane (OCM), a series of Ln2Ce2O7 compounds with different A sites (Ln = La, Pr, Sm and Y) have been prepared. It is revealed by XRD and Raman techniques that a defective cubic fluorite phase has been formed in all the catalysts. As a consequence, all the Ln2Ce2O7 catalysts possess much stronger surface basicity and more abundant electrophilic oxygen species in comparison with individual CeO2, which is beneficial to OCM reaction. It is believed that the concerted interaction between surface intermediate basic sites and selective electrophilic oxygen species is the predominant reason controlling the reaction performance of the catalysts. Furthermore, Ln2Ce2O7 catalysts own more abundant mesopores and higher surface areas than pure CeO2, which could also be favorable for the contacting of the reactants with the active sites. Due to the optimal synergistic interaction of these factors, La2Ce2O7 exhibits the best performance among all the catalysts, on which the highest C2 yield of 16.6% is achieved at 750 °C. In comparison with Mn/Na2WO4/SiO2, the most promising catalyst at present, La2Ce2O7 display much improved reaction performance at low temperature region (<750 °C).
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      PubDate: 2018-02-05T12:18:42Z
       
  • A sinter resistant Co Fischer-Tropsch catalyst promoted with Ru and
           supported on titania encapsulated by mesoporous silica
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Tumelo N. Phaahlamohlaka, Mbongiseni W. Dlamini, Mashikoane W. Mogodi, David O. Kumi, Linda L. Jewell, David G. Billing, Neil J. Coville
      One of the pathways responsible for the deactivation of Fischer-Tropsch catalysts is the loss of active metal surface area due to nanoparticle agglomeration. To combat this effect efforts have been made to increase the interaction between the metal nanoparticles and the support using materials like silica. In this study, the supported metal particles were covered with a highly porous layer of silica to stabilize the Co nanoparticles on a titania support both during reduction and under reaction conditions. Co3O4 nanoparticles (size range: 8–12 nm) supported on titania were stabilized by coating them with a thin layer of mesoporous silica ( ∼ 4 nm) to make Fischer-Tropsch catalysts that are less prone to sintering (Co/TiO2@mSiO2). To mitigate the strong metal support interactions brought about by the titania and silica a Ru promoter was loaded together with the cobalt nanoparticles onto the titania (CoRu/TiO2@mSiO2). Temperature programmed XRD studies on the evolution of the Co metal nanoparticles showed that there was no significant particle size growth under reduction conditions in the temperature range from 30 to 600 °C. Chemisorption studies following reduction under hydrogen at 350 °C and 450 °C gave results consistent with the in situ XRD data when compared to the Co/TiO2. Fischer-Tropsch synthesis on the Co/TiO2@mSiO2 and CoRu/TiO2@mSiO2 catalysts encapsulated inside the mesoporous silica shell exhibited good catalytic performance without any display of significant mass transport limitations that might arise due to a silica shell coating of the active sites. For these two catalysts the Fischer-Tropsch activity increased with reduction temperature without any significant negative changes in their selectivity due to sintering, while the activity on Co/TiO2 decreased due to Co nanoparticle sintering.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Alkylation of O-xylene and styrene catalyzed by cross-linked poly acidic
           ionic liquids catalyst with novel mesoporous-macroporous structure
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Huaying Gao, Yuming Zhou, Xiaoli Sheng, Shuo Zhao, Chao Zhang, Jiasheng Fang, Beibei Wang
      Cross-linked poly acidic ionic liquids (MPM-C6V-SO3CF3-IL) with mesoporous and macroporous network structure have been synthesized in different solvents. The novel solid acid catalyst with special network structure has a large surface area (103.83 m2/g), large pore volume (0.72 cm3/g) and abundant mesopores and macropores, which help to improve the contact between active site and reactants. Catalytic performance of catalyst was investigated through alkylation of o-xylene and styrene. Different reaction parameters specifically solvent on obtained catalyst and production of PXE were systematically investigated. Under optimal reaction conditions (reaction time was 3 h, reaction temperature was 120 °C, catalyst amount was 0.17 g (0.5 wt%), and o-xylene/styrene mass ratio was 7.5:1), a high conversion of styrene (100%) and 1,2-diphenylethane (PXE) yield of 99.67% was obtained, which is superior to commercial acid in liquid and even previous acids synthesized by our own group. Moreover, catalyst could keep relatively high thermostability under reaction and are easy to be separated and recycled from the solution, which are critical for heterogeneous solid catalysts. Thus, this novel catalyst can be potentially applied in other acidic reactions.
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      PubDate: 2018-02-05T12:18:42Z
       
  • FT-IR spectroscopy study of HNCO adsorption and hydrolysis over
           oxide-based samples dedicated to deNOx processes
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): M. Barreau, X. Courtois, F. Can
      HNCO adsorption monitored by FT-IR spectroscopy was performed over a wide range of oxides from various acid-base and redox properties: SiO2, Al2O3, TiO2, ZrO2, CeO2, CeO2-ZrO2, WO3/CeO2-ZrO2. HNCO adsorbed dissociatively in the whole studied samples. A correlation with pyridine ν8a wavenumbers revealed that HNCO dissociation mainly involved weak Lewis acid sites (LAS) location. The significant isocyanate adsorption capacity of titania and zirconia was evidenced. HNCO hydrolysis reaction was also investigated. Among the various studied samples, CeO2-ZrO2 and WO3/CeO2-ZrO2 presented the higher HNCO hydrolysis rate, with ammonia formation from room temperature. For all studied samples, NCO groups were evidenced as intermediate species of HNCO hydrolysis.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Catalytic evaluation of mesoporous metal oxides for liquid phase oxidation
           of styrene
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Ngonidzashe Masunga, Ginny Sasha Tito, Reinout Meijboom
      Mesoporous manganese oxide, cobalt oxide, and hybrid Mn-Co oxide were synthesized using an inverse surfactant micelle method. The synthesized materials were monodispersed nanoparticle aggregates with connected and well defined intra-particle voids. An increase in the pore and crystallite size with increase in calcination temperature was observed with TEM, SEM, p-XRD, and N2-sorption. These mesoporous metal oxides were employed in the selective oxidation of styrene using tert-butyl hydrogen peroxide as an oxidant. Higher selectivity towards styrene oxide was achieved using manganese oxide followed by cobalt oxide while the hybrid oxide showed the lowest selectivity towards styrene oxide. The catalytic activities of the compared catalysts were decreasing in the order of Mn-Co_350 (66.6 h−1) > MnO2_350 (47.4 h−1) > Co3O4_350 (35.6 h−1). The catalytic activities and selectivity profiles under various reaction conditions such as solvent type, catalyst amount, styrene to TBHP ratio and temperature are discussed. The catalytic recyclability of metal oxides showed that they are stable, and the structure of the catalyst was retained.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Conversion of syngas toward aromatics over hybrid Fe-based Fischer-Tropsch
           catalysts and HZSM-5 zeolites
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Yuebing Xu, Dapeng Liu, Xiaohao Liu
      Direct conversion of syngas (CO + H2) toward aromatics has been demonstrated over a hybrid catalyst system composed of Fe-based FTS catalyst and HZSM-5 zeolite. Over the catalyst system, the aromatics were highly selective in the liquid hydrocarbon products with a content greater than 95%, and 70–90% of the aromatics were concentered on the toluene, xylene and 3C-branched alkylbenzenes. In this study, we systematically investigated the effects of reaction conditions (temperature, pressure, space velocity and H2/CO ratio) and catalyst combination (Si/Al ratio of zeolite, weight ratio of HZSM-5 to Fe-based catalyst, metal modification of HZSM-5, and kind of Fe-based catalyst) on the CO conversion, selectivity to aromatics, aromatic distribution, and catalyst deactivation, combining with some characterization technologies (XRD, BET, NH3-TPD, H2-TPR, TG and 27Al NMR). The obtained results show that HZSM-5 zeolite was the crucial component for aromatic formation. Excessive loading of the zeolite in bed would greatly suppress the carburization of reduced Fe into Fe carbides as well as CO dissociation on the Fe carbides because of the increasingly unfavorable direct contact between the acidic HZSM-5 and Fe-based catalyst, resulting in a remarkably lower CO conversion. HZSM-5 zeolite having high Brønsted acidity favored the formation of aromatics with a high content in liquid phase. However, as HZSM-5 had originally lower Brønsted acidity or the Brønsted acidity decreased during the aromatic synthesis due to more coke deposition, the selectivity to hydrocarbons in liquid phase gradually shifted to iso-paraffins rather than aromatics. Reactions operated over FeMn-HZSM-5 catalyst system at lower temperature or higher pressure led to an easier deactivation of HZSM-5 mainly from coke deposition. Compared with the FeMn-HZSM-5, FeK-HZSM-5 deactivated seriously at same conditions probably due to heavier and olefinic primary hydrocarbons over the FeK catalyst. In addition, 27Al NMR showed that extraction of framework Al by in situ formed H2O and CO2 could be ignorable for the HZSM-5 deactivation. More detailed results and discussion from abundant experimental work on clarifying their effects on the aromatic synthesis can be found in the article.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Esterification of aqueous lactic acid solutions with ethanol using carbon
           solid acid catalysts: Amberlyst 15, sulfonated pyrolyzed wood and graphene
           oxide
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552
      Author(s): Van Chuc Nguyen, Ngoc Quynh Bui, Pascale Mascunan, Thi Thu Ha Vu, Pascal Fongarland, Nadine Essayem
      Lactic acid esterification over three carbon based solid acid catalysts were compared: sulfonated carbonised wood, graphene oxide (GO) and Amberlyst 15(A15) with the aim to address their water tolerance related to their acidity and hydrophobicity. The acidic properties of the carbon materials were measured by calorimetry of NH3 adsorption and their hydrophobicity was evaluated by water vapor adsorption isotherms. Here, we disclose the exceptional strong acidity of GO with differential heat of NH3 adsorption (QdiffNH3) higher than 200 kJ mol−1 while A15 and sulfonated carbon have significant lower acid strength with QdiffNH3 lower than 150 kJ mol−1. The super-acidity of GO is tentatively ascribed to the presence of “free” protons explained by the delocalization of the negative charges of counter anions within the graphene sheet. In presence of the minimum water content (3 mol L−1), GO is the most active catalyst with a TOF of 52 h−1 and its activity is also less inhibited upon water addition compared to A15. These results are rationalized considering that TOF depends intrinsically on the strength of Br∅nsted active sites and on the active site accessibility more or less controlled by the its micro-environment hydrophobicity seen to be equivalent for A15, sulfonated carbon and GO.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Graphical abstract TOC
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552


      PubDate: 2018-02-05T12:18:42Z
       
  • Graphical abstract TOC
    • Abstract: Publication date: 25 February 2018
      Source:Applied Catalysis A: General, Volume 552


      PubDate: 2018-02-05T12:18:42Z
       
  • Synthesis and stabilization of small Pt nanoparticles on TiO2 partially
           masked by SiO2
    • Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Zhenyu Bo, Sol Ahn, M. Alexander Ardagh, Neil M. Schweitzer, Christian P. Canlas, Omar K. Farha, Justin M. Notestein
      Controlling metal nanoparticle size and preserving metal dispersion at elevated temperature remain key challenges in designing new supported metal catalysts. Many methods have been proposed to stabilize metal nanoparticles for catalysis, but the use of specialized equipment or metal precursors can limit the application of these methods for scalable production. Here, we demonstrate a synthesis strategy to improve the dispersion and thermal stability of Pt nanoparticles on an oxide support. A thin SiO2 coat (<2 nm) was deposited on TiO2 through repeated condensation cycles of tetraethyl orthosilicate (TEOS) with or without an organic template on the surface. H2PtCl6 was deposited using wetness impregnation, and the samples were dried, calcined, and reduced. The as-synthesized Pt nanoparticles are 1–2 nm by TEM and maintain dispersion >45% by CO chemisorption even after prolonged heating at 500 °C, whereas Pt nanoparticles on unmodified TiO2 are less dispersed (∼33%) and their dispersion falls further upon prolonged heating. Ethylene hydrogenation demonstrates that the Pt nanoparticles on modified TiO2 preserve the catalytic activities of Pt on unmodified TiO2. The use of wet chemistry-based oxide modification and wetness impregnation makes this strategy a scalable and generalizable synthesis method to prepare other supported metal nanoparticles for catalysis applications.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Enhanced catalytic ozonation performance of highly stabilized mesoporous
           ZnO doped g-C3N4 composite for efficient water decontamination
    • Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Xiangjuan Yuan, Shule Duan, Guangyu Wu, Lei Sun, Gang Cao, Dongya Li, Haiming Xu, Qiang Li, Dongsheng Xia
      A series of functional organic-metal zinc oxide (ZnO) doped graphitic carbon nitride (g-C3N4) denoted as ZnO-CN composites were fabricated via a facile mixing and calcination approach. The composition, structure, and morphology of the as-prepared ZnO-CN composites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, fourier transform infrared (FT-IR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. When loading amount of ZnO is 0.1 and calcination temperature is 650 °C (denoted as ZnO-CN0.1-650), the kinetic constant of atrazine (ATZ) degradation was 2.73 min−1, which was almost 10.5 times higher than that of ozone alone, exhibiting the highest catalytic ozonation activity. The results of the characterization indicated that ZnO-CN0.1-650 presents the mesoporous structure in laminated g-C3N4 and Zn(II) are strongly coordinated and stabilized within the electron-rich g-C3N4 framework. The feasibility of ZnO-CN0.1-650 for practical application was further evaluated at different catalyst dosages, initial ATZ concentrations, solution pHs, and natural organic matters. Radical scavengers experiments demonstrated that O2 −, OH, and 1O2 are the dominant reactive radical species. In addition, the composite showed excellent stability for pollutants removal over multiple reaction cycles. A possible mechanism of the enhanced catalytic ozonation activity is attributed to the host-guest interaction between ZnO and g-C3N4, as well as the improved meso-porosity, increased surface area, and intensive mass and electron transfer ability ascribed to the electronic and surface properties modification. Overall, the ZnO-CN0.1-650 composite is demonstrated to be a highly efficient, stable, and recoverable catalyst, which provided a promising alternative in catalytic ozonation.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Co-processing of lignocellulosic biocrude with petroleum gas oils
    • Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): L. Sauvanaud, Y. Mathieu, A. Corma, L. Humphreys, W. Rowlands, T. Maschmeyer
      A biocrude was obtained via the catalytic hydrothermal treatment of lignocellulosic biomass. This was further co-hydroprocessed with Straight Run Gas Oil (SRGO) under desulphurization conditions. Amounts of biocrude of up to 20 wt% could be co-processed, while maintaining a diesel stream density within the specifications contained in the road diesel regulation EN 590. The changes in the diesel properties associated with an increasing amount of biocrude were not a simple linear function of biocrude content. Rather, some positive correlations seem to exist between biocrude and SRGO at low biocrude contents, possibly due to intramolecular hydrogen transfer, yielding a diesel stream with a better quality than would be obtained from simply mixing hydrotreated pure streams in a 80% to 20% ratio.
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      PubDate: 2018-02-05T12:18:42Z
       
  • Graphical abstract TOC
    • Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551


      PubDate: 2018-02-05T12:18:42Z
       
  • Impact of desilication of *BEA zeolites on the catalytic performance in
           hydroisomerization of n-C10
    • Authors: H. Sammoury; J. Toufaily; K. Cherry; T. Hamieh; Y. Pouilloux; L. Pinard
      Pages: 1 - 12
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): H. Sammoury, J. Toufaily, K. Cherry, T. Hamieh, Y. Pouilloux, L. Pinard
      Two commercial nanocrystal *BEA zeolites CP811 (P1) and CP814E (P2) with same total Si/Al ratio (Si/Altotal =12) but different textural properties, were desilicated using different alkaline treatment; classical in presence of NaOH alone, or incorporated with a pore directing agent. P1 was desilicated by NaOH alone, and NaOH+TPABr, while P2 was desilicated in presence of NaOH+TBAOH. A synthesized microcrystal *BEA zeolite with Si/Al total ratio of 36, was also desilicated with NaOH alone, NaOH+TPABr, and NaOH+TBAOH. All parent and desilicated zeolites were transformed into bifunctional catalysts by platinum loading and were tested in the hydroisomerization of n-C10. P1 zeolite was impregnated with different Pt contents to insure maximum activity and selectivity towards isomers products. It has been seen that the improvement of the textural properties by desilication using the different pore directing agents, was not always the cause behind an increase or decrease in the activity and selectivity of the catalyst, but rather was more the location of the Pt particles and their predicted distance from the acidic sites. However, the presence of an interplay between the inter- and intracrystalline mesopores, with the additional parameter of Pt-H+ distance, serve better as combined characteristics behind the final activity and selectivity.
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      PubDate: 2017-12-13T01:55:35Z
      DOI: 10.1016/j.apcata.2017.11.024
      Issue No: Vol. 551 (2017)
       
  • Silica deposition as an approach for improving the hydrothermal stability
           of an alumina support during glycerol aqueous phase reforming
    • Authors: Fang Liu; Chukwuemeka Okolie; Ryan M. Ravenelle; John C. Crittenden; Carsten Sievers; Pieter C.A. Bruijnincx; Bert M. Weckhuysen
      Pages: 13 - 22
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Fang Liu, Chukwuemeka Okolie, Ryan M. Ravenelle, John C. Crittenden, Carsten Sievers, Pieter C.A. Bruijnincx, Bert M. Weckhuysen
      Silica deposition on the benchmark aqueous phase reforming (APR) catalyst Pt/γ-Al2O3 is studied to prevent or limit hydrolytic attack of the support under hydrothermal APR conditions, for which boehmite formation by support hydration is a known cause for catalyst deactivation. Tetraethyl orthosilicate (TEOS) is employed as a silicon source in a straightforward liquid-phase, silylation process followed by catalyst calcination and reduction. Characterization by X-ray diffraction, temperature-programmed desorption of NH3, infrared, 27Al nuclear magnetic resonance and X-ray photoelectron spectroscopy of the fresh catalysts suggests that silica addition occurs preferentially on the support surface, resulting in weak Brønsted acid sites as well as in the formation of Si-O-Al linkages at the expense of specific surface Lewis acid sites. Silylation and calcination of Pt/γ-Al2O3 causes partial blockage of the metal surface area (12% loss), whereas γ-Al2O3 surface silica modification prior to Pt deposition makes controlled metal deposition difficult. Catalytic performance tests show the overcoated samples to be active in the APR of 5 wt% glycerol, albeit with lower H2 production rates compared to the benchmark catalyst. Characterization of spent APR catalysts clearly demonstrates that silylation/calcination treatments effectively slows down the transformation of the γ-Al2O3 support due to the formation of a Si-O-Al interface. Overall, the lifetime of the catalyst is increased three-fold as a result of the surface overcoating treatment, with repetitive recycling ultimately leading to loss of the protective silica layer.
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      PubDate: 2017-12-13T01:55:35Z
      DOI: 10.1016/j.apcata.2017.11.025
      Issue No: Vol. 551 (2017)
       
  • Effect of Au nanoparticles on the activity of TiO2 for ethanol upgrading
           reactions
    • Authors: J. Quesada; R. Arreola-Sánchez; L. Faba; E. Díaz; V.M. Rentería-Tapia; S. Ordóñez
      Pages: 23 - 33
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): J. Quesada, R. Arreola-Sánchez, L. Faba, E. Díaz, V.M. Rentería-Tapia, S. Ordóñez
      This article analyses the role of gold nanoparticles supported on TiO2 for the gas-phase ethanol condensation. Previously, the original P25 surface was modified for increasing the Au-Ti interaction, in order to minimize the thermal deactivation. Catalysts were tested both in absence and presence of hydrogen (523–673K, WHSV=7.9h−1; yEtOH =0.32; yH2 =0-0.1; 0.1MPa). Parent TiO2 is mainly selective for dehydration reactions yielding diethyl ether (favoured at low temperatures) and ethylene (favoured at higher temperatures). The presence of Au in the catalyst promotes dehydrogenation pathways, yielding acetaldehyde, as well as condensation products (mainly butanol, with selectivities close to 10%). According to DRIFT spectroscopy results, the strong ethanol adsorption on the TiO2 surface justifies the low yields and the high relevance of side-reactions produced by inter- or intra- molecular dehydration routes (diethyl ether, and ethylene formation). The gold addition minimizes this adsorption and enhances the main route by a double role: an improvement in the dehydrogenation rate (yielding more acetaldehyde) and an enhancement in the hydrogenation steps.
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      PubDate: 2017-12-13T01:55:35Z
      DOI: 10.1016/j.apcata.2017.12.004
      Issue No: Vol. 551 (2017)
       
  • Facile synthesis of a superior MTP catalyst: Hierarchical
           micro-meso-macroporous ZSM-5 zeolites
    • Authors: Hongyao Li; Yaquan Wang; Chunyang Fan; Chao Sun; Xiao Wang; Cui Wang; Xu Zhang; Shuhai Wang
      Pages: 34 - 48
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Hongyao Li, Yaquan Wang, Chunyang Fan, Chao Sun, Xiao Wang, Cui Wang, Xu Zhang, Shuhai Wang
      With the growing demand for propylene and the rapid depletion of petroleum resources, the methanol-to-propylene (MTP) reaction has aroused much interest in the industrial and academic research fields as an alternative route to produce propylene. Developing a highly efficient MTP catalyst by adopting a facile, efficient route is currently an important research goal. It is clear that the synthesis of a hierarchical micro-meso-macroporous ZSM-5 zeolite is regarded as the ideal strategy owing to its ability to minimize coke formation and to produce maximal catalytic efficiency in the MTP reaction. In this study, a superior MTP catalyst with a hierarchical micro-meso-macroporous structure (denoted as M-ZSM-5) has been successfully developed based on the passivation effect and the strong self-condensation of the short-chain organosilane 3-aminopropyltrimethoxy-silane (APTES) on the surfaces of nanocrystals in a quasi-solid-state system. This environmentally friendly synthetic strategy is operationally simple, with a high yield (above 80%) and low cost and thus has considerable potential for industrial applications. In the quasi-solid-state system, APTES not only induced the formation of ultrafine nanocrystals but also ensured that these ultrafine nanocrystals were assembled in situ into hierarchical micro-meso-macroporous ZSM-5 zeolites. When applied to the methanol-to-propylene (MTP) reaction, the synthesized MZ-x (x = 1–5) zeolites exhibited a longer catalytic lifetime (31 h–89 h) (at a high weight hourly space velocity of 8 h-1) than that of a commercial ZSM-5 catalyst (denoted as C1Z-1)(11 h), which are nearly three times and eight times longer than that of the C1Z-1 sample. In addition, the MZ-x (x = 1–5) catalysts also present a slightly higher propylene selectivity (39.92%–41.89%), butylene selectivity (22.29%–23.65%) and light olefins (C2= − C4 = ) selectivity (69.19%–71.43%) than that of the C1Z-1 (39.86%, 21.70%, 68.46%). These results were attributed to the abundant mesopores and macropores of M-ZSM-5 built by the ultrafine nanocrystals, offering a shorter diffusion path and more-accessible active sites for reaction.
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      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.007
      Issue No: Vol. 551 (2017)
       
  • Synergistic effects of Nb2O5 promoter on Ru/Al2O3 for an aqueous-phase
           hydrodeoxygenation of glycerol to hydrocarbons
    • Authors: Seongho Jeon; Yong Min Park; Jaeyeong Park; Kasi Saravanan; Hae-Kwon Jeong; Jong Wook Bae
      Pages: 49 - 62
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Seongho Jeon, Yong Min Park, Jaeyeong Park, Kasi Saravanan, Hae-Kwon Jeong, Jong Wook Bae
      Synergistic effects of niobium oxide (Nb2O5) on the Ru/Al2O3, where the alumina had boehmite phases prepared by sol-gel method with subsequent co-impregnation of bimetallic Ru-Nb, were investigated for an aqueous-phase hydrodeoxygenation (APH) as well as aqueous-phase reforming (APR) reaction of glycerol to form gaseous hydrocarbons and hydrogen with useful liquid-phase glycols such as ethylene and propylene glycols. The promoting effects of the Nb2O5 on the prototype Ru/Al2O3 were mainly attributed to the stabilized boehmite structures with the help of an incorporation of niobium oxides, which largely increased the catalytic activity and stability through less aggregations of smaller Ru nanoparticles. At an optimal Nb/Ru molar ratio of ∼1, the much smaller Ru nanoparticles were highly dispersed on the Nb-incorporated alumina matrices on the hexa-coordinated Al3+ sites selectively even after hydrothermal aqueous-phase reactions. The highly dispersed Ru nanoparticles on the Lewis acid sites of the boehmite phase of Al2O3 surfaces showed a facile reducibility and larger metallic Ru surface area with less formations of inactive hard coke precursors. It was mainly originated from the preferential presence of the reduced metallic Ru nanoparticles on the surfaces of the acidic Nb2O5-modified boehmite, which can strongly anchor the active Ru metals with their smaller sizes.
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      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.006
      Issue No: Vol. 551 (2017)
       
  • Effect of alkali and alkaline earth metal on Co/CeO2 catalyst for the
           water-gas shift reaction of waste derived synthesis gas
    • Authors: Yeol-Lim Lee; Ajay Jha; Won-Jun Jang; Jae-Oh Shim; Chandrashekhar V. Rode; Byong-Hun Jeon; Jong Wook Bae; Hyun-Seog Roh
      Pages: 63 - 70
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Yeol-Lim Lee, Ajay Jha, Won-Jun Jang, Jae-Oh Shim, Chandrashekhar V. Rode, Byong-Hun Jeon, Jong Wook Bae, Hyun-Seog Roh
      We prepared a series of alkali (Na and K) and alkaline earth metal (Ca and Ba) promoted Co/CeO2 catalysts to investigate the effect of the promoter on the catalytic performance of the catalyst in the high-temperature water-gas shift (WGS) reaction of waste derived synthesis gas. Interestingly, alkali metal promoted catalysts deactivated rapidly compared to alkaline earth metal promoted catalysts. Alkaline earth metal promoted catalysts showed relatively higher stability (> 50 h) even at a very high gas hourly space velocity of 143,000 h−1. X − ray diffraction (XRD) and transmission electron microscopy (TEM) results reveal that the higher stability of the alkaline earth metal promoted catalysts was due to the strong resistance to sintering, showing a relatively small crystallite size of metallic cobalt compared to the alkali metal promoted catalysts after WGS reaction.
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      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.009
      Issue No: Vol. 551 (2017)
       
  • Photocatalytic synthesis of vanillin using N-doped carbon nanotubes/ZnO
           catalysts under UV-LED irradiation
    • Authors: Maria J. Sampaio; Anas Benyounes; Philippe Serp; Joaquim L. Faria; Cláudia G. Silva
      Pages: 71 - 78
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Maria J. Sampaio, Anas Benyounes, Philippe Serp, Joaquim L. Faria, Cláudia G. Silva
      ZnO synthesized by solid-state thermal process was combined with different contents of nitrogen-doped carbon nanotubes (N-CNT). The materials were characterized by several techniques including thermogravimetric analysis, N2 adsorption-desorption isotherms, scanning and transmission electron microscopies, and diffuse reflectance UV–vis and photoluminescence spectroscopies. The performance of neat ZnO and N-CNT/ZnO composite materials was evaluated in the selective photocatalytic oxidation of vanillyl alcohol into vanillin under UV-LED irradiation. The presence of the carbon phase in the composite materials (from 5.0 to 10 wt.%) revealed to be crucial for increasing the performance of the photocatalysts. The best performance for vanillyl alcohol oxidation was obtained using the composite containing 5% of carbon phase (5.0%N-CNT/ZnO), with an increase of 22% in vanillin concentration comparing to neat ZnO after 2 h of reaction. This enhancement in the efficiency of ZnO by the introduction of the carbon phase is attributed to the action of N-CNT as effective electron scavengers for ZnO, as revealed by the photoluminescence quenching, inhibiting the recombination of electrons and holes.
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      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.002
      Issue No: Vol. 551 (2017)
       
  • Improving the low-temperature hydrothermal stability of Cu-SAPO-34 by the
           addition of Ag for ammonia selective catalytic reduction of NOx
    • Authors: Xiao Xiang; Yi Cao; Lijing Sun; Pengfei Wu; Lei Cao; Shutao Xu; Peng Tian; Zhongmin Liu
      Pages: 79 - 87
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Xiao Xiang, Yi Cao, Lijing Sun, Pengfei Wu, Lei Cao, Shutao Xu, Peng Tian, Zhongmin Liu
      Ag promoted Cu-SAPO-34 has been developed to improve the low-temperature hydrothermal stability of Cu-SAPO-34 for the NH3-SCR reaction. Kinetic tests show that the addition of Ag into Cu-SAPO-34 doesn’t change the reaction mechanism. The ion-exchanged Ag species, which decrease the Brønsted acid density and provide more Lewis acid sites with moderate acidity, have a protective effect on the SAPO framework against low-temperature steaming treatment (LTST). Higher surface Cu content is observed for CuAg2.25-SAPO-34, although CuAg2.25-SAPO-34 and Cu-SAPO-34 have similar content of isolated Cu ions. In situ DRIFTS studies demonstrate, for the first time, the NH3 molecules adsorbed on the weak/moderate acid sites (independent of the acid types such as Brønsted acid or Lewis acid) are more active than on the strong acid sites for the low-temperature SCR reaction. Compared with the original catalyst Cu-SAPO-34, the enhanced SCR activity of CuAg2.25-SAPO-34 after LTST is ascribed to the better preservation of total acid sites, higher moderate acid density (Lewis acid sites) and larger amount of surface Cu species on the CuAg2.25-SAPO-34 catalyst.
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      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.001
      Issue No: Vol. 551 (2017)
       
  • Base free oxidation of 1,6-hexanediol to adipic acid over supported noble
           metal mono- and bimetallic catalysts
    • Authors: Modibo Mounguengui-Diallo; François Vermersch; Noémie Perret; Catherine Pinel; Michèle Besson
      Pages: 88 - 97
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Modibo Mounguengui-Diallo, François Vermersch, Noémie Perret, Catherine Pinel, Michèle Besson
      1,6-Hexanediol is an emerging building-block chemical, which may be derived from biomass and can produce adipic acid for the synthesis of polymers. A series of supported Pt, Bi-Pt, Au, Pd, Au-Pd, and Au-Pt catalysts were prepared and evaluated in the aerobic oxidation of 1,6-hexanediol to adipic acid in aqueous solution without the addition of a base or an acid. The influences of various molar ratios of the metals in the bimetallic systems and the support (C, ZrO2) were studied. Under the conditions used, bismuth did not promote the catalytic performance of Pt catalysts. On the other hand, formation of an alloy of Au-Pd or Au-Pt made the catalysts very effective. A yield of adipic acid of ca. 96% was achieved at 70 °C under 40 bar of air over the Au-Pt catalyst supported on zirconia with a Au/Pt molar ratio of about 1. Recycling tests revealed the possibility to use the catalyst up to 6 times without significant changes in its catalytic performance.
      Graphical abstract image

      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.005
      Issue No: Vol. 551 (2017)
       
  • Highly efficient porous organic copolymer supported Rh catalysts for
           heterogeneous hydroformylation of butenes
    • Authors: Yuqing Wang; Li Yan; Cunyao Li; Miao Jiang; Wenlong Wang; Yunjie Ding
      Pages: 98 - 105
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Yuqing Wang, Li Yan, Cunyao Li, Miao Jiang, Wenlong Wang, Yunjie Ding
      Porous organic copolymer (denoted as CPOL-BP&P) was afforded through the copolymerization of vinyl biphephos and tris(4-vinylphenyl)phosphine monomers under solvothermal conditions, and followed with impregnation method provided a highly efficient Rh/CPOL-BP&P catalyst with high activity (TOF = 11,200 h−1) and regioselectivity (the ratio of linear to branched aldehydes, l:b = 62.2) for heterogeneous hydroformylation of 1-butene. High regioselectivity was also obtained in the hydroformylation of butene mixture (2-butene: l:b = 55.8, isomeric mixture of butenes: l:b = 56.0). The Rh/CPOL-BP&P catalysts were thoroughly characterized by means of nitrogen sorption isotherms, in situ FT-IR, XPS, solid-state 31P MAS NMR, HAADF-STEM, SEM and TEM. The formation of unique coordination bonds with Rh species in the polymer skeleton was determined. Heterogeneous hydroformylation of butenes was effectively realized due to a synergetic effect between PPh3 moiety and biphephos moiety.
      Graphical abstract image

      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.013
      Issue No: Vol. 551 (2017)
       
  • Influence of H2O and H2S on the composition, activity, and stability of
           sulfided Mo, CoMo, and NiMo supported on MgAl2O4 for hydrodeoxygenation of
           ethylene glycol
    • Authors: Trine Marie Hartmann Dabros; Abhijeet Gaur; Delfina Garcia Pintos; Paul Sprenger; Martin Høj; Thomas Willum Hansen; Felix Studt; Jostein Gabrielsen; Jan-Dierk Grunwaldt; Anker Degn Jensen
      Pages: 106 - 121
      Abstract: Publication date: 5 February 2018
      Source:Applied Catalysis A: General, Volume 551
      Author(s): Trine Marie Hartmann Dabros, Abhijeet Gaur, Delfina Garcia Pintos, Paul Sprenger, Martin Høj, Thomas Willum Hansen, Felix Studt, Jostein Gabrielsen, Jan-Dierk Grunwaldt, Anker Degn Jensen
      In this work, density functional theory (DFT), catalytic activity tests, and in-situ X-ray absorption spectroscopy (XAS) was performed to gain detailed insights into the activity and stability of MoS2, Ni-MoS2, and Co-MoS2 catalysts used for hydrodeoxygenation (HDO) of ethylene glycol upon variation of the partial pressures of H2O and H2S. The results show high water tolerance of the catalysts and highlight the importance of promotion and H2S level during HDO. DFT calculations unraveled that the active edge of MoS2 could be stabilized against SO exchanges by increasing the partial pressure of H2S or by promotion with either Ni or Co. The Mo, NiMo, and CoMo catalysts of the present study were all active and fairly selective for ethylene glycol HDO at 400 °C, 27 bar H2, and 550–2200 ppm H2S, and conversions of ≈50–100%. The unpromoted Mo/MgAl2O4 catalyst had a lower stability and activity per gram catalyst than the promoted analogues. The NiMo and CoMo catalysts produced ethane, ethylene, and C1 cracking products with a C2/C1 ratio of 1.5–2.0 at 550 ppm H2S. This ratio of HDO to cracking could be increased to ≈2 at 2200 ppm H2S which also stabilized the activity. Removing H2S from the feed caused severe catalyst deactivation. Both DFT and catalytic activity tests indicated that increasing the H2S concentration increased the concentration of SH groups on the catalyst, which correspondingly activated and stabilized the catalytic HDO performance. In-situ XAS further supported that the catalysts were tolerant towards water when exposed to increasing water concentration with H2O/H2S ratios up to 300 at 400–450 °C. Raman spectroscopy and XAS showed that MoS2 was present in the prepared catalysts as small and highly dispersed particles, probably owing to a strong interaction with the support. Linear combination fitting (LCF) analysis of the X-ray absorption near edge structure (XANES) spectra obtained during in-situ sulfidation showed that Ni was sulfided faster than Mo and CoMo, and that Mo was sulfided faster when promoted with Ni. Extended X-ray absorption fine structure (EXAFS) results showed the presence of MoS2 in all sulfided catalysts. Sulfided CoMo was present as a mixture of CoMoS and Co9S8, whereas sulfided NiMo was present as NiMoS.
      Graphical abstract image

      PubDate: 2017-12-26T15:15:34Z
      DOI: 10.1016/j.apcata.2017.12.008
      Issue No: Vol. 551 (2017)
       
 
 
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