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  Subjects -> ENGINEERING (Total: 2277 journals)
    - CHEMICAL ENGINEERING (191 journals)
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ENGINEERING (1203 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: 18)
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: 246)
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: 17)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Engineering Software     Hybrid Journal   (Followers: 26)
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: 10)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 22)
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Advances in Natural Sciences: Nanoscience and Nanotechnology     Open Access   (Followers: 29)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in OptoElectronics     Open Access   (Followers: 5)
Advances in Physics Theories and Applications     Open Access   (Followers: 12)
Advances in Polymer Science     Hybrid Journal   (Followers: 41)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 39)
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: 5)
AIChE Journal     Hybrid Journal   (Followers: 32)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 28)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 11)
American Journal of Engineering Education     Open Access   (Followers: 9)
American Journal of Environmental Engineering     Open Access   (Followers: 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: 16)
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: 4)
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Archives of Foundry Engineering     Open Access  
Archives of Thermodynamics     Open Access   (Followers: 7)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
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: 8)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 23)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Motor Trade Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 2)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 2)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 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: 16)
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: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 33)
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: 13)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 27)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 45)
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: 7)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 8)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
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: 23)
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: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 27)
Composite Interfaces     Hybrid Journal   (Followers: 6)
Composite Structures     Hybrid Journal   (Followers: 265)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 190)
Composites Part B : Engineering     Hybrid Journal   (Followers: 260)
Composites Science and Technology     Hybrid Journal   (Followers: 185)
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)
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Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computers & Geosciences     Hybrid Journal   (Followers: 28)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 6)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 4)
Computers and Geotechnics     Hybrid Journal   (Followers: 10)
Computing and Visualization in Science     Hybrid Journal   (Followers: 5)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 31)
Conciencia Tecnologica     Open Access  
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 7)
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)
CT&F Ciencia, Tecnologia y Futuro     Open Access   (Followers: 1)
CTheory     Open Access  

        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  [3049 journals]
  • Selective hydrogenation of furfural over Pt based and Pd based bimetallic
           catalysts supported on modified multiwalled carbon nanotubes (MWNT)
    • Authors: Lujie Liu; Hui Lou; Min Chen
      Pages: 1 - 10
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Lujie Liu, Hui Lou, Min Chen
      Nano-Pt and Nano-Pd particles were introduced to modified multiwalled carbon nanotubes via co-impregnation method for hydrogenation of furfural in liquid phase using ethanol as a solvent. Different transition metal (Cr, Mn, Fe, Co, Ni) was used as promoters using Pt/MWNT and Pd/MWNT catalysts and various supports were also compared to further investigate the hydrogenation process of furfural. Among the catalysts investigated, Pt–Fe/MWNT (Pt: 0.5wt%) showed highest conversion and selectivity to furfuryl alcohol (yield of 87.4%), while Pd–Ni/MWNT (Pd: 0.5wt%) catalysts exhibited the best catalytic performance (83.3% yield of tetrahydrofurfuryl alcohol) under the optimized conditions of 30bar hydrogen and 5h, at 100 and 130°C, respectively. Synergistic effect of bimetallic catalysts has been utilized to improve catalytic activity and stability. The extremely active for the selective hydrogenation of furfural over Pt–Fe/MWNT and Pd–Ni/MWNT catalyst might be attributed to active crystal planes exposed over Pt and Pd promoted by Fe and Ni. Catalysts have shown stable activity and selectivity after 5 cycles using Pt–Fe/MWNT and Pd–Ni/MWNT catalysts. Moreover, we suggest that acid sites of conventional supports might have an impact on furfural conversion.
      Graphical abstract image

      PubDate: 2017-11-02T02:03:54Z
      DOI: 10.1016/j.apcata.2017.10.003
      Issue No: Vol. 550 (2017)
       
  • Pore size-tunable titanosilicates post-synthesized from germanosilicate by
           structural reorganization and H2TiF6-assisted isomorphous substitution
    • Authors: Xue Liu; Lin Zhang; Hao Xu; Jingang Jiang; Mingming Peng; Peng Wu
      Pages: 11 - 19
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Xue Liu, Lin Zhang, Hao Xu, Jingang Jiang, Mingming Peng, Peng Wu
      Titanosilicates with large porosities are highly desirable for the selective liquid-phase epoxidation of alkenes in particular requiring open reaction spaces. Structural collapse and healing took place readily in one-pot when calcined and as-synthesized UTL-type germanosilicates both were subject to severe acid treatment, benefiting from the structural instability and modifiability of Ge-rich double four ring (D4R) units. Several structural derivatives with continuously tunable pore sizes were obtained by precisely controlling the acid treatment process. Isomorphous incorporation of Ti active centers and structural reorganization were then simultaneously realized via solid-liquid phase treatment using aqueous hexafluorotitanic acid (H2TiF6) solution, giving rise to three titanosilicates of Ti-ECNU-14 (OKO), Ti-ECNU-15 and Ti-UTL with different pore sizes varying form medium pores (10-ring) to extra-large pores (14-ring). The obtained titanosilicates with high content of tertrahedrally coordinated Ti ions in framework performed unique catalytic performance in the epoxidation of cyclic alkenes using hydrogen peroxide or anhydrous tert-butyl hydroperoxide as an oxidant.
      Graphical abstract image

      PubDate: 2017-11-02T02:03:54Z
      DOI: 10.1016/j.apcata.2017.10.017
      Issue No: Vol. 550 (2017)
       
  • Bimodal mesoporous TiO2 supported Pt, Pd and Ru catalysts and their
           catalytic performance and deactivation mechanism for catalytic combustion
           of Dichloromethane (CH2Cl2)
    • Authors: Shuang Cao; Xiaoqi Fei; Yexuan Wen; Zhuxing Sun; Haiqiang Wang; Zhongbiao Wu
      Pages: 20 - 27
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Shuang Cao, Xiaoqi Fei, Yexuan Wen, Zhuxing Sun, Haiqiang Wang, Zhongbiao Wu
      Pt-, Pd-, and Ru-doped bimodal mesoporous TiO2 catalysts were prepared by wet impregnation and applied to the catalytic combustion of dichloromethane (DCM). The Pd/TiO2 and Ru/TiO2 catalysts exhibited excellent catalytic activity. Total oxidation of DCM was obtained at 335°C with less undesired CO and byproducts (CxHyClz). A certain decrease in the selectivity of the Pd/TiO2 catalyst was observed in a long-term stability test, whereas Ru/TiO2 displayed appreciable stability. Pt/TiO2 was easily deactivated and showed the poorest performance for DCM decomposition. Deactivation of the catalysts was related to the deposition of carbon species and chlorine poisoning, whereby the active sites for DCM decomposition were occluded. Furthermore, the adsorption of chlorine species could change the chemical states of the Pd or Pt species and generate inactive species. Deactivation of the Ru/TiO2 catalyst was inhibited to some extent as carbon and chlorine species could be removed by RuO2. Moreover, the larger pore-size distribution of Ru/TiO2 was favorable for the desorption of by-products during DCM oxidation.
      Graphical abstract image

      PubDate: 2017-11-02T02:03:54Z
      DOI: 10.1016/j.apcata.2017.10.006
      Issue No: Vol. 550 (2017)
       
  • Deactivation of alumina supported cobalt FT catalysts during testing in a
           Continuous-stirred tank reactor (CSTR)
    • Authors: J. Clarkson; P.R. Ellis; R. Humble; G.J. Kelly; M. McKenna; J. West
      Pages: 28 - 37
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): J. Clarkson, P.R. Ellis, R. Humble, G.J. Kelly, M. McKenna, J. West
      A set of alumina supported cobalt catalysts was prepared, varying the synthesis method and formulation to produce a range of cobalt particle sizes. A combination of degree of reduction (DOR) measurements and H2 chemisorption was used to calculate the cobalt particle sizes on the fresh catalyst samples (5–19nm). The catalysts were pre-reduced and encapsulated in wax prior to testing for Fischer-Tropsch (FT) activity in a continuous-stirred tank reactor (CSTR) system for between 500 and 6000h on-line. The catalysts all demonstrated rapid deactivation over the first 200h of FT testing, with the catalysts with the highest initial activity deactivating most rapidly. Characterisation of the discharged catalysts samples using XRD, TEM and H2 chemisorption indicated that the cobalt particles had undergone a sintering process consistent with an Ostwald ripening mechanism. Catalyst stability in CSTR testing can be enhanced by the presence of large cobalt particles (>20nm).
      Graphical abstract image

      PubDate: 2017-11-02T02:03:54Z
      DOI: 10.1016/j.apcata.2017.10.014
      Issue No: Vol. 550 (2017)
       
  • Measuring and interpreting quantum efficiency of acid blue 9
           photodegradation using TiO2-based catalysts
    • Authors: Uriel Caudillo-Flores; Mario J. Muñoz-Batista; Anna Kubacka; Juan Zárate-Medina; José A. Cortés; Marcos Fernández-García
      Pages: 38 - 47
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Uriel Caudillo-Flores, Mario J. Muñoz-Batista, Anna Kubacka, Juan Zárate-Medina, José A. Cortés, Marcos Fernández-García
      A series of highly-active catalysts were obtained from the same precursor and calcined at different temperatures to generate single-phase anatase and anatase-rutile composite powders. Performance of the catalysts was compared with the P25 reference and assessed through the measurement of the optical properties of the materials and calculation of the efficiency of the photodegradation of a multifunctional dye, acid blue 9. X-ray diffraction, porosimetry, UV–vis and photoluminescence spectroscopies were used to analyze the physico-chemical properties of the catalysts and to test their stability under reaction conditions. Through the calculation of the reaction rate and total organic carbon (TOC) observables as well as the apparent and true quantum efficiency parameters we analyzed quantitatively the performance of the materials. We observe that a high surface area anatase sample showed optimum activity and adequate selectivity towards full mineralization. The catalysts were subjected to sedimentation and recycling experiments and the catalytic performance compared on the basis of the true quantum efficiency. The use of this last parameter leads to different conclusions than those supported by an analysis based in the kinetic constant, reaction rate or apparent quantum efficiency. The high quantum efficiency and easy recovery after repeated experiments shown by the catalysts were interpreted on the basis of the characterization results.
      Graphical abstract image

      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.10.016
      Issue No: Vol. 550 (2017)
       
  • A structure sensitivity approach to temperature programmed desorption
    • Authors: Cesar A. de Araujo Filho; Dmitry Yu. Murzin
      Pages: 48 - 56
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Cesar A. de Araujo Filho, Dmitry Yu. Murzin
      A novel approach for explaining the effect of the metal cluster size on Temperature Programmed Desorption (TPD) from supported catalysts is described. Based on the assumption that metal clusters have regular cuboctahedral geometry, it was possible to develop a model that describes how three dimensional aspects of the metal clusters may affect the TPD profiles. Depending on the way that the metal clusters are assumed to be arranged in the surface, two different approaches are described to account for desorption. The first one, named Monocluster Model, considers a surface with a narrow cluster size distribution in which an average cluster diameter reasonably well describes the cluster population. A more complete approach, named Multicluster Model, explains desorption based on the cluster size distribution of the metal sites. TPD curves of ammonia from different platinum supported carbon materials were numerically treated and compared with the geometrical information obtained from Transition Electron Microscopy. The results displayed a reasonable agreement, indicating that TPD curves should be interpreted taking into account the metal cluster size.
      Graphical abstract image

      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.11.001
      Issue No: Vol. 550 (2017)
       
  • Hydrodeoxygenation of guaiacol over Ni2P/SiO2–reaction mechanism and
           catalyst deactivation
    • Authors: Xuefang Lan; Emiel J.M. Hensen; Thomas Weber
      Pages: 57 - 66
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Xuefang Lan, Emiel J.M. Hensen, Thomas Weber
      The catalytic hydrodeoxygenation of guaiacol, a phenolic model compound of biomass lignin pyrolysis products, has been investigated under atmospheric pressure in H2 utilizing a Ni2P/SiO2 catalyst. Reaction networks are proposed based on the product distribution as a function of contact time and the temperature programmed surface reaction of adsorbed guaiacol and anisole. Guaiacol is mainly converted to benzene through demethoxylation and dehydroxylation via phenol and anisole as intermediates. Demethylation of guaiacol is a side-reaction, which produces small amounts of catechol. Spent catalyst samples were characterized by means of XRD, XPS, TEM, and temperature programmed oxidation to gain understanding the observed slight deactivation. Coke deposition, sintering, and the altering properties of Ni and P species on catalyst surface all contribute to deactivation, while there is no indication of surface oxidation after reaction. The increase of Niδ+ or Ni0 on the Ni2P surface and the decrease of Brønsted acid sites (i.e. POH) are considered to be the major reasons of product distribution changes.
      Graphical abstract image

      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.10.018
      Issue No: Vol. 550 (2017)
       
  • Fabrication of mesoporous Co3O4 oxides by acid treatment and their
           catalytic performances for toluene oxidation
    • Authors: Genqin Li; Chuanhui Zhang; Zhong Wang; He Huang; Hui Peng; Xuebing Li
      Pages: 67 - 76
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Genqin Li, Chuanhui Zhang, Zhong Wang, He Huang, Hui Peng, Xuebing Li
      Considering the harmful effects of volatile organic compounds (VOCs) on the atmosphere and public health, the search for proper catalytic materials for the effective catalytic elimination of VOCs remains one of the most pressing issues in the environmental field. In this study, a series of mesoporous Co3O4-n (n=0.00, 0.0001, 0.01, 0.05, 0.10, 1.00, representing the concentration of HNO3 aqueous solution) catalysts were fabricated by the acid treatment of Co3O4 that was previously prepared via a hydroxycarbonate precipitation method (Co3O4-P). The catalytic performances of the prepared catalysts were evaluated for the model reaction of toluene oxidation. An obvious enhancement of catalytic activity in the reaction was achieved over the acid-treated Co3O4 catalysts using lower HNO3 concentrations, with Co3O4-0.01 exhibiting the optimum catalytic activity (T90 =225°C, 15°C lower than that of Co3O4-P), excellent catalytic durability under dry conditions and a high regeneration capability under humid conditions. Benefitting from the dilute acid treatment, the Co3O4-n (n=0.01, 0.05, 0.10) catalysts presented higher specific surface areas, more weak acidic sites and higher abundances of surface Co2+ and Oads species, which were regarded as the key factors responsible for their enhanced catalytic activities.
      Graphical abstract image

      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.11.003
      Issue No: Vol. 550 (2017)
       
  • Hydrogenation of biomass-derived levulinic acid to γ-valerolactone
           catalyzed by mesoporous supported dendrimer-derived Ru and Pt catalysts:
           An alternative method for the production of renewable biofuels
    • Authors: Mulisa Nemanashi; Ji-Hyang Noh; Reinout Meijboom
      Pages: 77 - 89
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Mulisa Nemanashi, Ji-Hyang Noh, Reinout Meijboom
      Generation 4 PAMAM-OH dendrimers were employed as templating agent for the synthesis of dendrimer-encapsulated Ru and Pt nanoparticles (Ru- or Pt-DENs). These DEN catalysts were then immobilized onto preformed mesoporous support materials (TiO2 and SiO2) using wet-impregnation method to produce heterogeneous catalysts. Ru- and Pt-DENs were characterized prior to immobilization using UV–vis (UV-vis) spectroscopy and high-resolution transmission microscopy (HRTEM). The average particle sizes for Ru- and Pt-DENs were determined to be 1.4±0.2 and 1.7±0.3nm, respectively. Supported solid catalysts were characterized using various techniques such N2 adsorption-desorption physisorption, powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and HRTEM. Inductive coupled plasma-optical emission spectroscopy (ICP-OES) was used for the determination of metal loading on the support. The catalytic performance of these catalysts was investigated in the selective hydrogenation of levulinic acid (LA) to produce γ-valerolactone (GVL). The highest conversion was observed when unsupported catalysts (Ru-DENs and Pt-DENs) were used for all systems studied. The Ru catalyst displayed excellent activity as compared to Pt catalysts. All catalysts showed selectivity to γ-valerolactone up to 100%.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.10.015
      Issue No: Vol. 550 (2017)
       
  • Reduction mechanism of selective NO reduction on Pd-NiO/(Y0.99Ba0.01)2O3
           catalyst
    • Authors: Lin Liu; Tatsumi Ishihara
      Pages: 90 - 97
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Lin Liu, Tatsumi Ishihara
      Y(Ba)2O3 catalyst loaded with 1wt% Pd and 3.2wt% NiO, Pd-NiO/(Y0.99Ba0.01)2O3, was found to be highly active to the selective reduction of NO with C3H6. The adsorption of NO on both (Y0.99Ba0.01)2O3 and Pd-NiO loaded one was studied using temperature-programmed desorption, pulsed reaction analysis and in-situ Fourier transform infrared (FTIR) spectroscopy. It was determined that NO is readily adsorbed on (Y0.99Ba0.01)2O3, primarily via the formation of nitrite and nitrate species. The addition of Pd-NiO assists in activating NO decomposition at lower temperatures as well as increasing the extent of NO adsorption. The reaction of NO with C3H6 and O2 on the Pd-NiO/(Y0.99Ba0.01)2O3 was also studied using pulsed reaction analysis and in-situ FTIR under NO selective reduction condition. The results demonstrated that the mechanism involves the reaction of −C2Hx or −CH3 adsorption species generated via the disproportionation of C3H6 with nitrate species to form CNO or C2HxNOy (x, y=2,3) intermediates. These intermediates readily react with NO and O2 to form the products CO2, N2 and H2O.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.10.022
      Issue No: Vol. 550 (2017)
       
  • Comparative study of n-butane isomerization over SO42−/Al2O3-ZrO2 and
           HZSM-5 zeolites at low reaction temperatures
    • Authors: Pengzhao Wang; Wenfang Zhang; Qiang Zhang; Zhusong Xu; Chaohe Yang; Chunyi Li
      Pages: 98 - 104
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Pengzhao Wang, Wenfang Zhang, Qiang Zhang, Zhusong Xu, Chaohe Yang, Chunyi Li
      The effects of acidity and pore structures of alumina-promoted sulfated zirconia (SZA) and two HZSM-5 zeolites with different SiO2/Al2O3 ratios on reaction properties of n-butane conversion were comparatively investigated. The results demonstrated that monomolecular isomerization reaction predominated at 433–533K for SZA catalysts and bimolecular pathway predominated at 573–673K for HZSM-5 zeolites. For both samples, the amount of coke deposits was considerably low. The differences in catalytic behavior were caused by different acid properties and pore structures. The strength and stability of catalytic Brønsted acid sites determine the conversion rate of n-butane and the deactivation rate of catalysts, respectively. While the contributions of monomolecular and bimolecular pathway, as well as the products distributions are depended on the pore structures and influenced by the density of catalytic Brønsted acid sites.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.11.006
      Issue No: Vol. 550 (2017)
       
  • Chemical Looping Tar reforming with Fe,Sr-doped La2Zr2O7 pyrochlore
           supported on ZrO2
    • Authors: Martin Keller; David Philip Anderson; Henrik Leion; Tobias Mattisson
      Pages: 105 - 112
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Martin Keller, David Philip Anderson, Henrik Leion, Tobias Mattisson
      Chemical Looping Reforming (CLR) has been proposed as a new technology for tar removal from hot raw gas derived from biomass gasification. In this two-reactor fluidized bed process at atmospheric pressure, the bed material is circulating between a reformer, in which the bed material is in contact with the raw synthesis gas, and a regenerator, in which the bed material is regenerated by oxidizing coke deposits and sulfides with air. In this study Fe,Sr-doped La2Zr2O7 pyrochlores supported on ZrO2 with different Fe and Sr loadings were investigated for their use as a catalyst in CLR. By decreasing the Fe loading to Fe/La=0.25 the benzene-to-syngas conversion could be improved by about 50% at T=800°C in comparison with the reference material with Fe/La=1.25. With this material, benzene and ethylene conversion could be further improved by co-feeding O2 with the gasification gas, achieving a benzene conversion of up to 80% and an ethylene conversion of about 95% at a temperature of 850°C and a Gas Hourly Space Velocity of 6800h−1. The performance of the bed material was found stable over at least 3 redox cycles. Considering the expected lower costs and non-toxicity of this material compared to precious metal- and Nickel-containing catalysts, normally used in fixed-bed systems, it is a promising material for a fluidized CLR system for tar removal.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.10.020
      Issue No: Vol. 550 (2017)
       
  • Oxidative coupling of methane on cordierite monoliths coated with Sr/La2O3
           catalysts. Influence of honeycomb structure and catalyst-cordierite
           chemical interactions on the catalytic behavior
    • Authors: Brenda M. Sollier; Leticia E. Gómez; Alicia V. Boix; Eduardo E. Miró
      Pages: 113 - 121
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Brenda M. Sollier, Leticia E. Gómez, Alicia V. Boix, Eduardo E. Miró
      When powder Sr/La2O3 catalysts are deposited on the walls of cordierite monoliths, an important increase in both, methane conversion and C2 yield, takes place. In this work, it is shown that this improved catalytic behavior is due to a combination of physical and chemical factors. This conclusion was drawn after performing a systematic study in which several structured formulations were catalytically evaluated and characterized using different techniques (EDX, XRD, BET, XPS, LRS), which helped us to rationalize the experimental observations. It is suggested that the honeycomb structure provides a more homogeneous gaseous flow as compared with the powder catalyst. This fact results in a better contact between reactant and catalyst surface, which in turn results in an increase of the overall reaction rate. Furthermore, it is demonstrated that the catalytic layer enrichment with Mg and Si, coming from the cordierite structure, greatly contributes to the improved catalytic behavior.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.10.023
      Issue No: Vol. 550 (2017)
       
  • Recent developments in the design of photoreactors for solar energy
           conversion from water splitting and CO2 reduction
    • Authors: Van-Huy Nguyen; Jeffrey C.S. Wu
      Pages: 122 - 141
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Van-Huy Nguyen, Jeffrey C.S. Wu
      In recent decades, increasing interest has been devoted to improving the methods for solar energy conversion using water splitting and CO2 reduction for solar fuel development. Herein, we discuss the historical background, present the current status, and expose development prospects to summarize and highlight the design of photoreactors. First, we discuss how converting CO2 greenhouse gas to renewable fuels by using sustainable sunlight energy can simultaneously solve the problems of global warming and sustainable energy shortage. Several types of photoreactors for photocatalytic CO2 reduction and CO2 hydrogenation for realizing solar fuels have been developed extensively. Among them, an optical-fiber photoreactor, a monolith photoreactor, and an internally illuminated monolith photoreactor have received considerable attention recently. Second, we show how the design of novel twin photoreactor systems has great potential for solar energy conversion from water splitting. Combining water splitting and CO2 hydrogenation to mimic photosynthesis is expected to play an important role in the future. Third, we demonstrate how a twin photoreactor also offers a new approach to producing solar fuels and simultaneously degrading organic wastewater. We believe that effectively combining H2 production to hydrogenate CO2 and organic wastewater treatment is a promising green technology. Finally, we propose critical challenges and prospects for the design of photoreactors. This review highlights the need to give more attention to the design of photoreactors for solar energy conversion from water splitting and CO2 reduction.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.11.002
      Issue No: Vol. 550 (2017)
       
  • Hydrodeoxygenation activity of W modified Ni/H-ZSM-5 catalyst for single
           step conversion of levulinic acid to pentanoic acid: An insight on the
           reaction mechanism and structure activity relationship
    • Authors: Vijay Kumar Velisoju; Naresh Gutta; James Tardio; Suresh K. Bhargava; Krishna Vankudoth; Anjaneyulu Chatla; Sudhakar Medak; Venugopal Akula
      Pages: 142 - 150
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Vijay Kumar Velisoju, Naresh Gutta, James Tardio, Suresh K. Bhargava, Krishna Vankudoth, Anjaneyulu Chatla, Sudhakar Medak, Venugopal Akula
      Direct conversion of levulinic acid (LA) to pentanoic acid (PA) was achieved over the W modified Ni supported on SiO2, Al2O3 and H-ZSM-5 catalysts at 270°C and ambient H2 pressure in a continuous flow fixed-bed reactor. The interaction between Ni and W was the key which is rationalized by XRD, XPS, TGA-TPD of NH3, DRIFTS, TEM, CO-pulse chemisorption and H2-TPR analyses. PA rate of ∼1.24μmols−1 gcat −1 (with highest LA conversion ∼40% and selectivity ∼65% after 6h of continuous operation) achieved over W modified Ni/H-ZSM-5 catalyst compared to others. The better PA rate on Ni-W/H-ZSM-5 catalyst was manifested by the presence of not only strong acid sites and also due to a higher number surface ionic Ni species which were responsible for the ring opening of γ-valerolactone (GVL) and the β-proton abstraction that occurred on basic sites. On the contrary, Ni-W/SiO2, Ni-W/Al2O3 and Ni/H-ZSM-5 were found to be less selective towards PA and more selective towards GVL, exemplifying the role of support and W for the PA selectivity. The surface active sites for the PA formation are illustrated by using probes such as pyridine (strong base) and/or acetone (mild base) and formic acid adsorbed DRIFT spectroscopy. Based on the product distribution, a plausible surface mechanism was also elucidated and discussed.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.11.008
      Issue No: Vol. 550 (2017)
       
  • Oxidative dehydrogenation of ethane to ethylene: A promising
           CeO2-ZrO2-modified NiO-Al2O3/Ni-foam catalyst
    • Authors: Zhiqiang Zhang; Jia Ding; Ruijuan Chai; Guofeng Zhao; Ye Liu; Yong Lu
      Pages: 151 - 159
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Zhiqiang Zhang, Jia Ding, Ruijuan Chai, Guofeng Zhao, Ye Liu, Yong Lu
      From macro- to nano-engineering of a promising CeO2-ZrO2-doped NiO-Al2O3/Ni-foam catalyst has been demonstrated for the oxidative dehydrogenation of ethane to ethylene (ODE), through facial wet chemical etching of a Ni-foam followed post modification with CeO2 and ZrO2. The NiO-Al2O3/Ni-foam (denoted as NANF) achieved a high ethane conversion of 25.2% but with a very low ethylene selectivity of 43.1% at 450°C. ZrO2-doping of the NANF led to a remarkable improvement in the ethylene selectivity but serious deterioration of activity while the CeO2-doping showed an opposite effect. Co-doping of the NANF using optimal amount of CeO2 and ZrO2 markedly promoted not only the activity but also the selectivity to ethylene. For example, over the 1CeO2-5ZrO2-NANF (CeO2:1wt%, ZrO2:5wt%) catalyst, a high ethane conversion of 40.3% was obtained with a 60.6% ethylene selectivity for a feed gas of C2H6/O2/N2 =1/1/8 at 500°C and a gas hourly space velocity of 18,000cm3 g−1 h−1, corresponding to a high ethylene productivity of 510gEthylene kgcat −1 h−1. In nature, co-doping with CeO2 and ZrO2 synergistically tamed the NiO for selective H-abstraction of the ethane molecules other than over oxidation of them.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.11.005
      Issue No: Vol. 550 (2017)
       
  • From medium chain fatty alcohol to jet fuel: Rational integration of
           selective dehydration and hydro-processing
    • Authors: Mingli He; Meng Wang; Guanglu Tang; Yunming Fang; Tianwei Tan
      Pages: 160 - 167
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): Mingli He, Meng Wang, Guanglu Tang, Yunming Fang, Tianwei Tan
      Middle chain fatty alcohols, which can be easily obtained from bio-synthesis and fatty acid hydro-treatment, were used as a renewable resource to produce alternative jet fuels by rational integration of selective dehydration and hydro-processing. Various catalysts such as ZSM-22, Al-MCF and ZSM-5 with different textural and acidic properties were tested in the dehydration step. It was found that the structural and acidic properties have significant influences on the dehydration performance and product distribution. After Pt introduction, the fatty alcohols can be converted into paraffins with different isomerization degrees. The different integrations of dehydration and hydro-processing steps resulted in different medium chain fatty alcohol to jet fuel production processes. Three different production processes, one-step hydro-isomerization over Pt/ZSM-22, dehydration (Al-MCF)/hydro-isomerization (Pt/ZSM-22) and dehydration (ZSM-22)/hydro-processing (Pt/MCF) were developed and tested. The dehydration (Al-MCF)/hydro-isomerization (Pt/ZSM-22) process, which provides the highest iso-paraffin yield, was used for conversion of a commercially available alcohol mixture in a pilot scale reactor. The product obtained from such pilot scale experiment had a freezing point of <−60°C and met the requirements of ASTM 7566 specification except for density.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.11.009
      Issue No: Vol. 550 (2017)
       
  • Electrostatic adsorption-microwave synthesis of palladium nanoparticles on
           graphene for improved cross-coupling activity
    • Authors: S.E. Gilliland; J. Meynard M. Tengco; Y. Yang; J.R. Regalbuto; C.E. Castano; B.F. Gupton
      Pages: 168 - 175
      Abstract: Publication date: 25 January 2018
      Source:Applied Catalysis A: General, Volume 550
      Author(s): S.E. Gilliland, J. Meynard M. Tengco, Y. Yang, J.R. Regalbuto, C.E. Castano, B.F. Gupton
      Graphene materials as catalyst supports have shown tremendous promise for improving catalytic activity. Pd nanoparticles supported by graphene defects have been shown to improve catalytic activity in Suzuki reactions, but understanding their formation and factors that affect their formation is still elusive. In order to gain a better understanding of this phenomenon, a new synthetic method was developed combining strong electrostatic adsorption method for directed ionic Pd precursor uptake with a new solventless microwave irradiation method to simultaneously form Pd nanoparticles and graphene defect sites. Catalytic activities an order of magnitude higher than commercial Pd-carbon catalysts were obtained using this new method with low microwave powers, short reaction times, under atmospheric conditions, and without the use of reducing agents or solvents. The systematic comparison of catalysts synthesized from four different graphene materials and two different Pd precursors revealed Pd-graphene defects form through three routes that are affected by the initial oxygen content of graphene support and choice of ionic Pd precursor.
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      PubDate: 2017-11-16T02:37:52Z
      DOI: 10.1016/j.apcata.2017.11.007
      Issue No: Vol. 550 (2017)
       
  • Characterization of potassium-modified FAU zeolites and their performance
           in aldol condensation of furfural and acetone
    • Authors: Oleg Kikhtyanin; Yadolah Ganjkhanlou; David Kubička; Roman Bulánek; Jiří Čejka
      Pages: 8 - 18
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Oleg Kikhtyanin, Yadolah Ganjkhanlou, David Kubička, Roman Bulánek, Jiří Čejka
      The effects of both Si/Al ratio and preparation method (ion exchange vs. impregnation) on the physico-chemical properties of potassium modified Y zeolites were studied in detail. The samples were used as basic catalysts for aldol condensation of furfural and acetone. A relationship between physico-chemical properties and catalytic performance of potassium-containing Y zeolites was established using XRD, N2 physisorption, IR spectroscopy of adsorbed CO2‎ and CO2-TPD. Neither ion-exchange nor impregnation with KNO3 removed completely all acid sites in Y (Si/Al=2.5). Moreover, K2O clusters were not formed under thermal activation of the samples prepared from the parent H-Y(2.5). As a consequence, both ion-exchanged and impregnated K-Y(2.5) possessed low activity in aldol condensation, but they had high ability to dehydrate reaction products. In contrast, thermal activation of USY zeolites (Si/Al=15 and 40) impregnated with potassium resulted in the formation of K2O species which, according to CO2-IR spectroscopy and CO2-TPD, were strong basic sites. It was concluded that the lower amount of proton sites available for an ion-exchange together with the ‎larger mesopore volume and more defective crystalline framework promoted the accumulation of KNO3 in the USY zeolites during the impregnation step. Subsequently, K2O species were formed by thermal treatment. Impregnated and calcined USY zeolites possessed a superior catalytic activity in comparison with HY (Si/Al=2.5). The presence of K2O species as strong basic sites in K-impregnated USY zeolites was favorable for both the high activity of the catalysts in aldol condensation and the occurrence of the second condensation step.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.09.017
      Issue No: Vol. 549 (2017)
       
  • A re-examination of the catalyst activation and temperature hysteresis in
           methane combustion on Pt/Al2O3
    • Authors: Linxiao Chen; Joseph P. McCann; Steven L. Tait
      Pages: 19 - 30
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Linxiao Chen, Joseph P. McCann, Steven L. Tait
      Methane combustion is an industrially important reaction that has been extensively studied. Supported Pt catalysts on Al2O3 exhibit excellent activity in this reaction owing to their CH bond activation capability. Pt/Al2O3 catalyst remains almost inactive until the conversion increases abruptly at the ignition temperature (Tign ). The temperature hysteresis behavior has been reported, where after ignition, as the temperature is lowered below Tign , the catalyst continues to exhibit high activity. The activation has been previously attributed to the removal of adsorbed oxygen on Pt sites at Tign , while the hysteresis has been explained by the local temperature elevation caused by the reaction heat. In this work, this behavior was re-examined at a small scale in a fixed-bed flow reactor over a range of pre-treatment and reaction mixture conditions. Low-temperature activation was achieved by pre-treating the catalyst with CH4. Carefully designed control experiments yielded observations that cannot be rationalized by the existing theory, suggesting that it is incomplete. Based on these new results, we propose a more comprehensive theory describing the active sites in the oxidation reaction as methane-derived adsorbed carbon active sites, and their formation as the controlling factor in the catalyst activation. The hysteresis can be better explained by the enhanced stability of active sites under reaction conditions. In situ infrared spectroscopy and mass spectrometry studies were conducted in a flow cell, providing strong evidence supporting the theory. The dissociative adsorption of CH4 was studied under a variety of pre-treatment conditions, and proved to be responsible for the active site formation. The fundamental understanding obtained in this work contributes significant insights to the understanding of reaction mechanism.
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      PubDate: 2017-09-26T08:11:30Z
      DOI: 10.1016/j.apcata.2017.09.008
      Issue No: Vol. 549 (2017)
       
  • Direct catalytic hydroxylation of benzene to phenol catalyzed by vanadia
           supported on exfoliated graphitic carbon nitride
    • Authors: Jie Xu; Ye Chen; Ying Hong; Huan Zheng; Dan Ma; Bing Xue; Yong-Xin Li
      Pages: 31 - 39
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Jie Xu, Ye Chen, Ying Hong, Huan Zheng, Dan Ma, Bing Xue, Yong-Xin Li
      Direct hydroxylation of benzene is a sustainable and promising strategy to synthesize phenol. The key topic for the catalytic process is the development of an efficient heterogeneous catalyst. In this work, graphitic carbon nitride (g-C3N4) material was exfoliated and protonated, and then utilized as a support to load vanadia by using VO(acac)2 as a precursor. The synthesized materials were characterized by several techniques including N2 adsorption–desorption, XRD, TG, TEM, SEM, FT-IR, UV–vis, and XPS. The results exhibited that the exfoliation as a simple method could improve the surface area and pore volume of g-C3N4, while protonation was able to facilitate to increase the loading amount of vanadia. In hydroxylation of benzene to phenol in the presence of H2O2, the vanadia catalysts supported on peg-C3N4 demonstrated superior catalytic activity to the catalysts supported on the pristine g-C3N4. Moreover, the effects of protonation conditions including acid concentration and temperature on the final catalytic activity have also been investigated. Under optimized conditions, a maximum yield of phenol reached 15% at 60°C.
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      PubDate: 2017-09-26T08:11:30Z
      DOI: 10.1016/j.apcata.2017.09.015
      Issue No: Vol. 549 (2017)
       
  • Structurally uniform 1-hexene, 1-octene, and 1-decene oligomers:
           Zirconocene/MAO-catalyzed preparation, characterization, and prospects of
           their use as low-viscosity low-temperature oil base stocks
    • Authors: Ilya E. Nifant’ev; Alexander A. Vinogradov; Alexey A. Vinogradov; Igor V. Sedov; Viktor G. Dorokhov; Anton S. Lyadov; Pavel V. Ivchenko
      Pages: 40 - 50
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Ilya E. Nifant’ev, Alexander A. Vinogradov, Alexey A. Vinogradov, Igor V. Sedov, Viktor G. Dorokhov, Anton S. Lyadov, Pavel V. Ivchenko
      An original approach to α-olefin oligomerization as well as novel thermally stable zirconocene catalysts for use in such reactions has been elaborated. The method reported allows the achievement of fractions of lightweight α-olefin oligomers up to 90% yields without considerable formation of byproducts like internal alkenes, alkanes, and higher oligomers. Trimers, tetramers, and pentamers of 1-hexene, 1-octene, and 1-decene were isolated as individual compounds and were hydrogenated. Viscosity characteristics of the isolated saturated and unsaturated hydrocarbons have been studied at various temperatures. The isolated saturated oligomers of 1-octene and 1-decene outperform the traditional electrophilic oligomerization products in terms of viscosity indexes, pour points, and low-temperature viscosity.
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      PubDate: 2017-09-26T08:11:30Z
      DOI: 10.1016/j.apcata.2017.09.016
      Issue No: Vol. 549 (2017)
       
  • Comparing a cobalt-based catalyst with iron-based catalysts for the
           Fischer-Tropsch XTL-process operating at high conversion
    • Authors: E. van Steen; M. Claeys; K.P. Möller; D. Nabaho
      Pages: 51 - 59
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): E. van Steen, M. Claeys, K.P. Möller, D. Nabaho
      The XTL-process is a capital-intensive process. Novel process configurations need to be explored to increase the economic viability of this process. This is typically performed using the known dependencies of the catalyst as a function of the targeted process conditions. However, new process conditions may require catalysts with different characteristics compared to those currently utilised. Here, a set of cobalt- and iron-based Fischer-Tropsch catalysts are evaluated for their suitability in the application of a single-pass XTL-process operating at high conversion of synthesis gas. It is shown that cobalt-based catalysts of a suitable activity may be preferred over iron-based catalysts. The higher selectivity for methane for cobalt-based catalysts is offset by a lower selectivity for C2-C4 resulting in a favourable C5+-selectivity.
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      PubDate: 2017-09-26T08:11:30Z
      DOI: 10.1016/j.apcata.2017.09.019
      Issue No: Vol. 549 (2017)
       
  • Design of Pd@Graphene oxide framework nanocatalyst with improved activity
           and recyclability in Suzuki-Miyaura cross-coupling reaction
    • Authors: Thuy Phuong Nhat Tran; Ashutosh Thakur; Dai Xuan Trinh; Anh Thi Ngoc Dao; Toshiaki Taniike
      Pages: 60 - 67
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Thuy Phuong Nhat Tran, Ashutosh Thakur, Dai Xuan Trinh, Anh Thi Ngoc Dao, Toshiaki Taniike
      We describe a new method to synthesize a catalyst comprising of Pd nanoparticles encapsulated in a graphene oxide framework (Pd@GOF). GO was first intercalated with benzene-1,4-diboronic acid to afford a three-dimensional (3D) framework with uniform interlayer spaces, in which Pd nanoparticles were generated through salt reduction. Thus formed Pd nanoparticles were highly dispersed and stabilized inside a graphitic gallery space with a narrow particle size distribution. Thus obtained Pd@GOF catalyst exhibited an outperforming activity toward the Suzuki-Miyaura cross-coupling reaction in both polar and apolar solvents. Moreover, it can be reused for at least five cycles without any significant loss of the activity, while commercial Pd/C and Pd/GO exhibited a clear drop in the activity. These findings would establish the GOF as a promising scaffold to host noble metal nanoparticles and to construct desired metal@GOF nanocatalysts with improved activity and durability, which must be attractive for a broad range of practical applications.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.09.026
      Issue No: Vol. 549 (2017)
       
  • A novel S, N dual doped carbon catalyst for acetylene hydrochlorination
    • Authors: Jian Wang; Fei Zhao; Chunli Zhang; Lihua Kang; Mingyuan Zhu
      Pages: 68 - 75
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Jian Wang, Fei Zhao, Chunli Zhang, Lihua Kang, Mingyuan Zhu
      In this study, a sulphur and nitrogen dual-doped carbon catalyst was prepared via an easy route with p-phenyldiamine and (NH4)2S2O8 as the nitrogen and sulphur source, respectively. The obtained catalyst displayed efficient acetylene conversion for acetylene hydrochlorination, and the presence of sulphur enhanced the catalytic activity of the nitrogen-doped carbon catalyst. These catalysts show that sulphur and nitrogen have a synergistic effect for acetylene hydrochlorination. Furthermore, because of the addition of different sulphur contents, the pyrrolic N content causes certain changes in the catalysts, resulting in differences in the catalytic activity. Theoretical investigations reveal that the adsorption ability of C2H2 was enhanced by the doping of the S and N-doped carbon catalyst. This is an environmentally friendly catalyst with a broad development prospect and is cheap and easy to obtain.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.09.025
      Issue No: Vol. 549 (2017)
       
  • Preferential dealumination of Zn/H-ZSM-5 and its high and stable activity
           for ethane dehydroaromatization
    • Authors: Hikaru Saito; Satoshi Inagaki; Kiria Kojima; Qiao Han; Tomohiro Yabe; Shuhei Ogo; Yoshihiro Kubota; Yasushi Sekine
      Pages: 76 - 81
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Hikaru Saito, Satoshi Inagaki, Kiria Kojima, Qiao Han, Tomohiro Yabe, Shuhei Ogo, Yoshihiro Kubota, Yasushi Sekine
      The effect of steam treatment on Zn/H-ZSM-5 catalysts prepared by an ion-exchange method for non-oxidative ethane dehydroaromatization was investigated. Steam treatment of Zn/H-ZSM-5 after Zn loading improved its catalytic stability on aromatic hydrocarbon formation including benzene, toluene and xylene. Temperature programmed oxidation measurements demonstrated that the steam treatment brought suppression of coke formation and it contributed to the improvement in the catalytic stability. Characterization of the local structure of the zeolites by 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy revealed that dealumination of the framework Al in the MFI structure proceeded by steam treatment. Results of temperature programmed desorption of ammonia indicate the decrease in the amount of acid sites by the steam treatment. The slight changes in Zn content and its electronic state indicated that bared Al related with H+, not with Zn2+, in the MFI structure was preferentially dealuminated by steam treatment. The preferential dealumination led to suppression of coke formation by the selective removal of undesirable Brønsted acid sites.
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      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.024
      Issue No: Vol. 549 (2017)
       
  • Synthesis of iron-based metal-organic framework MIL-53 as an efficient
           catalyst to activate persulfate for the degradation of Orange G in aqueous
           solution
    • Authors: Mengjie Pu; Zeyu Guan; Yongwen Ma; Jinquan Wan; Yan Wang; Mark L. Brusseau; Haiyuan Chi
      Pages: 82 - 92
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Mengjie Pu, Zeyu Guan, Yongwen Ma, Jinquan Wan, Yan Wang, Mark L. Brusseau, Haiyuan Chi
      A series of MIL-53(Fe) materials was synthesized using a solvothermal method under different temperature and time conditions and were used as catalysts to activate persulfate and degrade Orange G (OG). Influences of the above conditions on the crystal structure and catalytic behavior were investigated. Degradation of OG under different conditions was evaluated, and the possible activation mechanism was speculated. The results indicate that high synthesis temperature (larger than 170°C) leads to poor crystallinity and low catalytic activity, while MIL-53(Fe) cannot fully develop at low temperature (100 or 120°C). The extension of synthesis time from 5h to 3d can increase the crystallinity of the samples, but weakened the catalytic activity, which was caused by the reduction of BET surface area and the amount of Fe (II)-coordinative unsaturated sites. Among all the samples, MIL-53(Fe)-A possesses the best crystal structure and catalytic activity. In optimal conditions, OG solution can be totally decolorized after degradation for 90min, and a removal rate of 74% for COD was attained after 120min. The initial solution pH had great influence on OG degradation, with the greatest removal in acidic pH environment. ESR spectra showed that sulfate radical (SO4 − ), hydroxyl radical (OH), persulfate radical (S2O8 − ), and superoxide radical (O2 ) exist in this system under acidic conditions. Furthermore, with the increase of pH, the relative amount of O2 increases while that of OH and SO4 − decreases, resulting in a reduced oxidizing capacity of the system.
      Graphical abstract image

      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.021
      Issue No: Vol. 549 (2017)
       
  • Characterization of nickel catalysts with transient methods
    • Authors: Stefan Ewald; Sebastian Standl; Olaf Hinrichsen
      Pages: 93 - 101
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Stefan Ewald, Sebastian Standl, Olaf Hinrichsen
      The Ni surface area is a key factor in catalytic performance of supported Ni catalysts employed in heterogeneously catalyzed reactions. For its characterization, transient measurement techniques are powerful but need a proper experimental design and a high level of accuracy. In this study, several transient methods, namely temperature programmed desorption of H2 (H2-TPD), pulsed H2 chemisorption and N2O chemisorption, were applied and evaluated for the characterization of Ni catalysts. Results were compared with those from static H2 chemisorption. Ni powder, as well as NiAlOx and Ni/γ-Al2O3 with varying Ni loadings, synthesized via precipitation and incipient wetness impregnation, respectively, were used as model catalysts. H2-TPD within the temperature range from 84 to 753K is able to completely describe the interaction of H2 with supported Ni. However, a quantitative analysis of the specific Ni surface area based on H2-TPD is difficult whereas pulsed H2 chemisorption leads to comparable results as obtained from static measurements. Adsorption and pre-treatment conditions have a strong impact on the desorption spectra. Reversible morphologic changes of the Ni surface were revealed by H2-TPD when changing the gas atmosphere during pre‐treatment. N2O chemisorption occurs in three steps including fast oxygen uptake, growth of the oxide layer and subsequent layer thickening due to subsurface and bulk oxidation. A separation of surface and subsurface/bulk oxidation of NiAlOx and Ni/γ-Al2O3, both of which are readily oxidized even under mild conditions, is only achievable at temperatures between 190 and 195K. In this temperature range, the ratio of adsorbed oxygen atoms, O, and the number of Ni surface atoms, NiS, (O/NiS) is 0.38±0.07, which can be applied for specific Ni surface area determination. The experimental mode of N2O chemisorption (flow or titration mode) does not influence the extent of subsurface oxidation. The separation of surface and subsurface/bulk oxidation is more feasible in the case of Ni powder. Here, a suitable temperature for Ni surface area determination lies within 265 and 285K with an O/NiS ratio of 0.96±0.05.
      Graphical abstract image

      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.023
      Issue No: Vol. 549 (2017)
       
  • In-situ construction of novel silver nanoparticle decorated polymeric
           spheres as highly active and stable catalysts for reduction of methylene
           blue dye
    • Authors: Guangfu Liao; Qing Li; Wenzhe Zhao; Qiuhu Pang; Haiyang Gao; Zushun Xu
      Pages: 102 - 111
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Guangfu Liao, Qing Li, Wenzhe Zhao, Qiuhu Pang, Haiyang Gao, Zushun Xu
      A facile strategy has been developed for the preparation of novel silver/poly(styrene-N-isopropylacrylamide-methacrylic acid) (Ag/PSNM) nanocomposite spheres with high catalytic activity and good storage stability. Silver (Ag) nanoparticles are successfully deposited on poly(styrene-N-isopropylacrylamide-methacrylic acid) (PSNM) spheres surfaces via in situ reduction and simultaneously protected by polyvinylpyrrolidone (PVP). The prepared Ag/PSNM nanocomposite spheres show good temperature/pH responsive property and improved thermal property. Moreover, they also exhibit high catalytic activity and good recyclability for the catalytic reduction of methylene blue (MB) to leuco methylene blue (LMB). The result of clock reaction indicate that the redox reaction generates a colorless (LMB) solution which easily reverts back to blue (MB) in air. The catalytic activity increase with the increasing of temperature and the reaction rate constant (k) follows the typical Arrhenius-type dependence on temperature. In addition, the prepared Ag/PSNM nanocomposite spheres show good storage stability and the catalytic activity remains almost unchanged after storage for 90days at room temperature. Therefore, the prepared Ag/PSNM nanocomposite spheres can have a highly potential use in the catalytic degradation of organic dyes in wastewater treatment applications.
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      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.034
      Issue No: Vol. 549 (2017)
       
  • Co-N-doped carbon nanotubes supported on diatomite for highly efficient
           catalysis oxidative carbonylation of amines with CO and air
    • Authors: Jiangwei Li; Dong-huai Tu; Yani Li; Weiqiang Wang; Qinwei Yu; Jianming Yang; Jian Lu
      Pages: 112 - 116
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Jiangwei Li, Dong-huai Tu, Yani Li, Weiqiang Wang, Qinwei Yu, Jianming Yang, Jian Lu
      Cobalt-nitrogen-doped carbon nanotubes stably supported on diatomite were obtained by employing Co(OAc)2/phenanthroline. The resulting material was found to be excellent catalysts for the carbonylation of a variety of amines with CO other than phosgene. Both high activity and selectivity were achieved in this carbonylation process, and it allows air as a cheap oxidizing agent. Moreover the catalyst could be recycled for several times with relatively higher activity compared to homogeneous catalyst palladium acetate.
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      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.030
      Issue No: Vol. 549 (2017)
       
  • Adjusted interactions of nickel nanoparticles with cobalt-modified
           MgAl2O4-SiC for an enhanced catalytic stability during steam reforming of
           propane
    • Authors: Kyung Soo Park; Minji Son; Myung-June Park; Dae Hyun Kim; Jeong Hwa Kim; So Hyun Park; Joon-Hwan Choi; Jong Wook Bae
      Pages: 117 - 133
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Kyung Soo Park, Minji Son, Myung-June Park, Dae Hyun Kim, Jeong Hwa Kim, So Hyun Park, Joon-Hwan Choi, Jong Wook Bae
      Steam reforming of propane (SRP) for the stable production of hydrogen-rich reformates was investigated using the Ni-supported on the cobalt-modified SiC-embedded MgAl2O4 support (denoted as NCMAS). The adjusted interactions of the Ni nanoparticles with the cobalt-modified SiC-embedded MgAl2O4 (MgAl2O4-SiC) and its crystallite size distributions largely altered the catalytic activity and stability of NCMAS. The introductions of SiC on the NCMAS, where SiC has a higher thermal conductivity, also increased the dispersion of smaller MgAl2O4 grains with the less formations of inactive NiAl2O4 species, which resulted in the higher catalytic activity with smaller formations of unreformed light hydrocarbons. The positive roles of cobalt promoter on the MgAl2O4-SiC matrices were mainly attributed to the suppressed aggregation of nickel nanoparticles by their strong and intimate interactions with the cobalt-modified MgAl2O4. The effects of cobalt promoter at an optimal 5wt%Co in the MgAl2O4-SiC (NCMAS(5)) enhanced the oxidation-resistance of the nickel nanoparticles with less formations of inactive metal aluminates by being reversibly re-reduced under the SRP reaction conditions. These phenomena further lessen coke depositions by intimately interacting with highly dispersed oxophilic cobalt or cobalt aluminate species. The optimal NCMAS(5) was applied to derive kinetic parameters using Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanisms, and the reasonable activation energy of 73 kJ/mol and optimal operating parameters to maximize hydrogen production by SRP reaction was estimated in terms of the reaction conditions such as space velocity, feed ratio and reaction temperature.
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      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.031
      Issue No: Vol. 549 (2017)
       
  • Rapid one-pot catalytic synthesis of double-capped oligoesters from
           lactones
    • Authors: Parichat Piromjitpong; Jiraya Kiriratnikom; Thasanaporn Ungpittagul; Sirilata Yotphan; Khamphee Phomphrai
      Pages: 134 - 140
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Parichat Piromjitpong, Jiraya Kiriratnikom, Thasanaporn Ungpittagul, Sirilata Yotphan, Khamphee Phomphrai
      The rapid one-pot catalytic synthesis of double-capped oligoesters was carried out by the ring-opening polymerization of various cyclic ester monomers (i.e. ε-caprolactone (ε-CL), δ-valerolactone (DVL), γ-butyrolactone (GBL), and L-lactide (L-LA)) followed by the transesterification reaction with a variety of alkyl esters as an end-capping agent. Simple metal amides were found to be an effective catalyst under mild condition. Among them, LiN(SiMe3)2 was shown to be the most active catalyst giving 94% conversion of double-capped oligo(ε-caprolactone) within 5min at room temperature. The average chain length of the oligoesters can be controlled by the adjustment of the ratio of an alkyl ester to monomer, the reaction time and reaction temperature.
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      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.033
      Issue No: Vol. 549 (2017)
       
  • Relating coke formation and characteristics to deactivation of ZSM-5
           zeolite in methanol to gasoline conversion
    • Authors: Zhijian Wan; Gang Kevin Li; Chuanfu Wang; Hong Yang; Dongke Zhang
      Pages: 141 - 151
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Zhijian Wan, Gang Kevin Li, Chuanfu Wang, Hong Yang, Dongke Zhang
      Two ZSM-5 catalysts, differing only in their crystal size, viz, nanocrystal at∼100nm and microcrystal at 13μm, respectively, were synthesised and tested in methanol to gasoline (MTG) conversion, with a focus on the formation and characteristics of coke deposits. Over time periods when methanol conversion decreased to 50%, herein termed as the service lifespan of the catalyst, the nanocrystal catalyst incurred 31.1wt% coke deposition, while the microcrystal counterpart had 14.1wt% coke. The nanocrystal catalyst showed a service lifespan almost seven times longer than the microcrystal catalyst. The difference in the catalytic service lifespans was examined in terms of the rate of formation of internal coke and structural properties of external coke, as determined using nitrogen physisorption, TGA and TEM. It was found that the internal coke was quickly formed in the microcrystal catalyst leading to rapid coverage of the active sites and blockage of the pores, resulting in fast deactivation. In contrast, coke formed preferentially on the external surface in the case of the nanocrystal catalyst. This external coke was of porous graphitic structures, and thus was not detrimental to the catalytic performance. The coke fouled nanocrystal catalyst was regenerated and the activity of the regenerated catalyst was evaluated under the same reaction conditions. An increase in catalytic service lifespan compared to the pristine nanocrystal catalyst was observed, due to the effect of decreased Al concentration on the catalytic performance.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.09.035
      Issue No: Vol. 549 (2017)
       
  • Controlled silylation of MoVTeNb mixed oxide catalyst for the selective
           oxidation of propane to acrylic acid
    • Authors: Xinlin Tu; Masao Niwa; Akio Arano; Yoshinori Kimata; Eiichi Okazaki; Souichi Nomura
      Pages: 152 - 160
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Xinlin Tu, Masao Niwa, Akio Arano, Yoshinori Kimata, Eiichi Okazaki, Souichi Nomura
      Acrylic acid is an important industrial chemical, and efficient catalysts for its direct preparation by propane oxidation are highly desirable. For this purpose, neutral silica networks were introduced on the surface of MoVTeNb mixed oxide catalysts by controlled silylation using a methyl silicate oligomer (MS-51). The modified catalysts gave ∼56.5% yield of acrylic acid with a selectivity of 77.1% in the oxidation of propane at 380°C. The catalysts were characterized by X-ray fluorescence, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller specific surface area, X-ray diffraction (Rietveld analysis), pyridine desorption, and scanning electron microscopy. MoVTeNb mixed oxide was found to be composed of 90.9% M1 phase and 2.3% M2 phase, and upon silylation, the surface was uniformly covered by a thin SiO2 layer with 0.14 molar ratio with respect to Mo and an estimated thickness of 2.4nm. The amount of acid sites decreased after the first three silylation cycles, but was not affected by repeated cycles. The results of the kinetic study based on the comparison of the simulated contribution of each side reaction were consistent with those of the model reactions using acrylic acid and other reactants: the controlled silylation effectively suppressed acrylic acid oxidation, especially after repeated silylation cycles, which is responsible for the superior performance of the silylated catalysts. Considering the relatively large size of acrylic acid compared to propane and the efficient propane activation by silica-covered catalysts, the controlled silylation was proposed to have two roles, by which further consecutive oxidation is prevented effectively to exhibit excellent performance in oxidation of propane: i) to block the unfavorable acidic sides, ii) to generate a silica layer with pore mouth openings on the surface of MoVTeNb mixed oxide, which allow the entrance of propane but inhibit re-entrance of the produced acrylic acid.
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      PubDate: 2017-10-11T22:48:35Z
      DOI: 10.1016/j.apcata.2017.09.013
      Issue No: Vol. 549 (2017)
       
  • Ru/CeO2 catalysts for combustion of mixture of light hydrocarbons: Effect
           of preparation method and metal salt precursors
    • Authors: Janina Okal; Mirosław Zawadzki; Piotr Kraszkiewicz; Katarzyna Adamska
      Pages: 161 - 169
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Janina Okal, Mirosław Zawadzki, Piotr Kraszkiewicz, Katarzyna Adamska
      Two preparation methods and two metal salt precursors (chlorine containing and chlorine-free) were used to synthesize Ru/CeO2 catalysts and their catalytic behaviour has been evaluated in combustion of propane, n-butane and isobutane mixture. In the first method, Ru nanoparticles (Ru NPs) deposited on CeO2 were synthesized by a microwave-assisted polyol method using RuCl3 as a metal precursor and ethylene glycol as a reducing agent. In the second, Ru/CeO2 catalysts were prepared by traditional incipient wetness impregnation method using RuCl3 or Ru(NO)(NO3)3. ICP-AES, N2 adsorption-desorption, H2-TPR, XRD, HRTEM and SEM-EDS techniques were used to characterize the catalysts. In all the Ru/CeO2 catalysts only highly dispersed Ru nanoparticles (1–2nm) were present. The catalytic data show that the preparation method and the nature of the metal precursor have a significant influence on catalytic performance of the Ru/CeO2 catalysts. The VOC reactivity order (iso-butane > n-butane > propane) show that propane is the most difficult to oxidize. The Ru(NPs)/CeO2 and impregnated Ru(N)/CeO2 catalyst exhibited much higher activity and stability than that of impregnated Ru(Cl)/CeO2. It was found that the Ru(NPs)/CeO2 nano-catalyst was free of chlorine species although it had been prepared from RuCl3. The differences in the activity have been ascribed to the presence of Cl− ions on the Ru(Cl)/CeO2 catalyst and to much better reducibility of the chlorine-free Ru(NPs) and Ru(N) catalysts. The Cl species have a negative impact on the redox properties of CeO2, they have some influence on Ru agglomeration during long-term activity tests (50h), and consequently, the chlorinated catalyst exhibited a poorer activity and stability compared with those of the Cl-free catalysts.
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      PubDate: 2017-11-09T02:10:38Z
      DOI: 10.1016/j.apcata.2017.09.036
      Issue No: Vol. 549 (2017)
       
  • Hydrogenation of levulinic acid to γ-valerolactone over anatase-supported
           Ru catalysts: Effect of catalyst synthesis protocols on activity
    • Authors: A.S. Piskun; J. Ftouni; Z. Tang; B.M. Weckhuysen; P.C.A. Bruijnincx; H.J. Heeres
      Pages: 197 - 206
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): A.S. Piskun, J. Ftouni, Z. Tang, B.M. Weckhuysen, P.C.A. Bruijnincx, H.J. Heeres
      γ-Valerolactone (GVL) is a value-added renewable chemical with great potential and can be obtained from biomass by the hydrogenation of levulinic acid (LA) using metal-based catalysts, such as Ru/TiO2. We here report an in depth study of the effect of catalyst synthesis parameters on the performance of Ru/TiO2 (anatase), varying the nature of the Ru-precursor and the conditions of the calcination and/or reduction step. Catalyst performance was evaluated under batch conditions at a hydrogen pressure of 45bar and using either water (90°C) or dioxane (150°C) as solvent. The experiments showed that catalyst activity depends greatly on the Ru precursor used (RuCl3, RuNO(NO3)3, Ru(NH3)6Cl3). Best results when considering the turn-over frequencies (TOF) of the catalysts were obtained using the RuNO(NO3)3 precursor, whereas RuCl3 performed better when considering the initial rate based on Ru intake. An intermediate calcination step and the use of a hydrogen-rich sweep gas during the final reduction step were shown to have a negative impact on catalyst activity. Characterization of the fresh catalysts by BET and TEM provided valuable insight in the relation between the catalyst structure and its activity.
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      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.09.032
      Issue No: Vol. 549 (2017)
       
  • Glycerol acetalization with formaldehyde using heteropolyacid salts
           supported on mesostructured silica
    • Authors: Lin Chen; Bendaoud Nohair; Dongyuan Zhao; Serge Kaliaguine
      Pages: 207 - 215
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Lin Chen, Bendaoud Nohair, Dongyuan Zhao, Serge Kaliaguine
      In the present work, mesoporous silica supported heteropolyacid salts were studied systematically for glycerol acetalization with formaldehyde. Attention was focused on finding an appropriate loading of Cs2.5H0.5PW12O40 (Cs2.5) on mesoporous silica supports and studying the influence of the architecture of mesoporous silica on activity. Supported Cs2.5H0.5PW12O40 on 2D (SBA-15) and 3D (KIT-6 and SBA-16) pore lattice mesoporous silicas have been compared. The activity of all supported Cs2.5 catalysts was found superior to that of bulk Cs2.5 owing to the high surface area of the mesoporous supports. While the activity difference between 2D and 3D supports did not meet expectations, mesopore volume had a significant impact on activity, which is attributed to a good access to Cs2.5H0.5PW12O40 acid sites. The catalysts could be reused for three times (24h each time), loosing only 10% glycerol conversion.
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      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.09.027
      Issue No: Vol. 549 (2017)
       
  • Catalytic way of transforming 2,3-dimethylphenol to para-quinone with the
           use of vanadium-containing heteropoly acids
    • Authors: Yulia A. Rodikova; Elena G. Zhizhina; Zinaida P. Pai
      Pages: 216 - 224
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Yulia A. Rodikova, Elena G. Zhizhina, Zinaida P. Pai
      2,3-Dimethyl-p-benzoquinone (2,3-Me2BQ) is a valuable chemical that is applied as a soft oxidizing and dehydrogenating agent and also as a synthon in preparing different complex products including pharmaceutical and biochemical substances. Keggin- and modified-type aqueous solutions of Mo-V-phosphoric heteropoly acids (Mo-V-P HPAs) with the gross compositions H3+xPMo12-xVxO40 (HPA-x) and HaPzMoyVx’Ob (HPA-x’), respectively, possessing high oxidation potential and simplicity of regeneration can serve as effective soft oxidants for obtaining such para-quinone from 2,3-dimethylphenol (2,3-Me2P). The synthesized HPA catalysts with different vanadium content were characterized by a number of analysis techniques, such as 31P and 51V NMR spectroscopy, potentiometry, titrimetry, and pH measurement. It was found that the predominant formation of 2,3-Me2BQ instead of corresponding diphenoquinone (DPQ) at one-electron oxidation is achieved by a consecutive optimization of reaction conditions, the most important among them being organic solvent and molar ratio of vanadium(V) to substrate. As was shown, the substitution of HPA-x by HPA-x’ allows one to increase the quinone selectivity and to decrease the optimal molar ratio of vanadium(V) to substrate. The highest yield of the desired quinone (97%) at total substrate conversion was obtained by using the biphasic water-benzene system at molar vanadium(V) to substrate ratio of 12. The temperature of 50°C and an inert atmosphere were established to be the optimal reaction conditions. The aqueous HPA-10′ solution including the highest content of VO2 + ions proved to be the most efficient catalyst among investigated HPAs. Carrying out catalyst regeneration at a separate stage provides the preservation of its activity and selectivity at the initial level for at least ten cycles.
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      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.09.022
      Issue No: Vol. 549 (2017)
       
  • A study of the hydrodeoxygenation of anisole over Re-MoOx/TiO2 catalyst
    • Authors: I.Tyrone Ghampson; Roberto Canales; Néstor Escalona
      Pages: 225 - 236
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): I.Tyrone Ghampson, Roberto Canales, Néstor Escalona
      A well-characterized Re-MoOx/TiO2 catalyst was used to investigate the reaction sequence involved during the hydrodeoxygenation of anisole in a batch reactor by varying the initial anisole concentration in the reactant mixture (0.182–0.382molL−1 corresponding to 2.6–5.4wt.%), the reaction temperature (250–325°C) and hydrogen pressure (30–60bar). The effects of these process variables on product selectivity, calculated at 10% anisole conversion, and reaction rate, estimated from the initial slope of anisole conversion vs. time, were discussed. The initial reaction rate was observed to increase to a maximum at anisole concentration of 0.282molL−1 and then decrease at higher concentrations. Mathematical modeling of the proposed reaction network revealed that the decreased activity at higher anisole concentration is related to diminished ability to cleave CO bonds on phenol and cresols, probably due to increased surface coverage by the reactant on the oxophilic sites on the catalyst which limits access to surface reactive hydrogen for transformation. In regards to the influence of reaction temperature, high temperature favors the formation of cresols at the expense of benzene which was confirmed by the estimated apparent activation energy of the different pathways. On the other hand, the observed strong dependence of benzene/phenol ratio on H2 pressure is attributed to increased availability of surface reactive hydrogen surface to aid in oxygen removal. Results from this study and the literature indicates that CO bond breaking is preceded by either protonation of oxygen on anisole or by partial hydrogenation of the aromatic ring to lower the CO scission barrier. Analysis of the conversion of intermediate compounds confirmed the reaction sequence and preferences during anisole HDO on Re-MoOx/TiO2 catalyst.
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      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.10.009
      Issue No: Vol. 549 (2017)
       
  • Preparation of a novel bimetallic AuCu-P25-rGO ternary nanocomposite with
           enhanced photocatalytic degradation performance
    • Authors: He Wen; Yu Long; Wei Han; Wei Wu; Yuanyuan Yang; Jiantai Ma
      Pages: 237 - 244
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): He Wen, Yu Long, Wei Han, Wei Wu, Yuanyuan Yang, Jiantai Ma
      In this work, a novel bimetallic ternary composite (AuCu-P25-rGO) had been designed and prepared, and been used as a high-performance photocatalyst. The morphology, chemical composition, physical structure and photoelectric property were confirmed by XRD, TEM, BET analysis, FT-IR, Raman, XPS, UV-vis DRS, Photoluminscence spectra and transient photocurrent responses techniques. The photocatalysts possessed higher catalytic activity than P25, P25-rGO, AuCu-P25, Cu-P25-rGO, Au-P25-rGO for photodegradation of organic pollutant (2-nitrophenol) under UV–vis light. Importantly, the molar ratio of Au:Cu exhibited significant influence on the photocatalytic property, and AuCu-P25-rGO with Au/Cu molar ratio=1:1 showed higher activity than these with Au/Cu molar ratio=1:3 and 3:1. In addition, Au1Cu1-P25-rGO could excellently photodegradation of organic dyes (Rhodamine B and methylene blue). The enhanced photocatalytic performance of AuCu-P25-rGO composites can be attributed to three reasons as follows: (1) surface plasmon resonance (SPR) effect of AuCu bimetallic nanoparticles; (2) outstanding conductivity and adsorptivity of rGO; (3) the polymorphs junction formed by mixture of anatase and rutile of P25.
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      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.09.028
      Issue No: Vol. 549 (2017)
       
  • Semihydrogenation of 2-methyl-3-butyn-2-ol on Pd-Zn nanoalloys: Effect of
           composition and heterogenization
    • Authors: Lyudmila B. Okhlopkova; Svetlana V. Cherepanova; Igor P. Prosvirin; Mikhail A. Kerzhentsev; Zinfer R. Ismagilov
      Pages: 245 - 253
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Lyudmila B. Okhlopkova, Svetlana V. Cherepanova, Igor P. Prosvirin, Mikhail A. Kerzhentsev, Zinfer R. Ismagilov
      Influence of composition and heterogenization to titania matrix of Pd-Zn nanoparticles has been studied in selective hydrogenation of the triple bond of 2-methyl-3-butyn-2-ol (MBY). Pd-Zn bimetallic nanoparticles with the various molar ratios Pd/Zn have been obtained by chemical reduction method. Composition- controlled sol-gel technique was employed to synthesize Pd-Zn/TiO2 catalysts. The structure properties of the bimetallic catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Computer modeling for XRD patterns was first used to identify the composition of Pd-Zn alloy and to determine the particle size. For the colloidal and embedded nanoparticles dependences of physicochemical and catalytic properties on composition are different being determined respectively by geometric and electronic effects. The addition of zinc with Pd/Zn ratio of 1 increased selectivity to alkene at 99% conversion from 92.9% for the Pd catalyst to 96.9% for bimetallic catalysts, which is mainly caused by alloy formation.
      Graphical abstract image

      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.10.005
      Issue No: Vol. 549 (2017)
       
  • Catalytic properties of carbon nanotubes-supported heteropolyacids in
           isopropanol conversion
    • Authors: A. Kirpsza; E. Lalik; G. Mordarski; A. Micek-Ilnicka
      Pages: 254 - 262
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): A. Kirpsza, E. Lalik, G. Mordarski, A. Micek-Ilnicka
      The technique of catalytic flow microreactor has been combined with the gas flow-through microcalorimetry to correlate the catalytic activity of supported heteropolyacids with both the acid strength of protons as well as the protons’ accessibility. Multiwall carbon nanotubes (CNT) were used as a support for Keggin (H3PW12O40) and Wells-Dawson (H6P2W18O62) structured heteropolyacids, in order to produce catalysts combining high acidity from the parent acids with the inherent microporosity of the support. Prior to the catalytic tests, the obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and Raman spectroscopies as well as by the nitrogen adsorption-desorption analysis (BET). The latter technique confirmed overall improved porosity of the obtained materials. Upon testing for activity in the isopropyl alcohol dehydration, the supported Wells-Dawson catalysts turned out to be superior to both the Keggin-based materials, as well as to the unsupported H6P2W18O62. It has been found that the improvement of catalytic performance in the isopropanol conversion is mostly related to the increase of the accessibility of protons, rather than to the changes in the acid strengths.
      Graphical abstract image

      PubDate: 2017-10-18T21:27:38Z
      DOI: 10.1016/j.apcata.2017.10.008
      Issue No: Vol. 549 (2017)
       
  • The effect of synthesis parameters on ordered mesoporous nickel alumina
           catalyst for CO2 methanation
    • Authors: Ali Aljishi; Gabriel Veilleux; Jose Augusto Hernandez Lalinde; Jan Kopyscinski
      Pages: 263 - 272
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Ali Aljishi, Gabriel Veilleux, Jose Augusto Hernandez Lalinde, Jan Kopyscinski
      A series of ordered mesoporous nickel alumina catalysts were synthesized via the evaporation induced self-assembly technique (EISA). Varying synthesis parameters such as the type of acid, nickel loading, calcination temperature as well as synthesis method influenced the catalyst morphology and its activity towards CO2 methanation. Catalyst prepared without acid formed macroporous structures with a very low surface area (47m2 g−1), whereas using a mixture of hydrochloric and citric acid resulted in incomplete formation of mesoporous micelles with surface area of 173m2 g−1. On the other hand, using nitric acid lead to complete formation of long cylindrical micelles with a combined surface areas up to 260m2 g−1 and highly dispersed nickel clusters with a size of 3–5nm. An optimum calcination temperature of 700°C was determined yielding the highest CO2 conversion and CH4 selectivity. This catalyst displayed a stable performance and did not exhibit any sign of deactivation during a 150h test. Catalysts calcined at lower and higher temperatures had smaller surface areas as well as lower catalytic activity.
      Graphical abstract image

      PubDate: 2017-10-25T12:57:48Z
      DOI: 10.1016/j.apcata.2017.10.012
      Issue No: Vol. 549 (2017)
       
  • Pd-SnO2/Al2O3 heteroaggregate nanocatalysts for selective hydrogenations
           of p-nitroacetophenone and p-nitrobenzaldehyde
    • Authors: Miaomiao Liu; Weiqiang Tang; Yisheng Xu; Hongbo Yu; Hongfeng Yin; Shuangliang Zhao; Shenghu Zhou
      Pages: 273 - 279
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): Miaomiao Liu, Weiqiang Tang, Yisheng Xu, Hongbo Yu, Hongfeng Yin, Shuangliang Zhao, Shenghu Zhou
      Pd-SnO2 heteroaggregate nanocatalysts were synthesized by in-situ transformation of PdSn bimetallic nanoparticles on alumina. The PdSn bimetallic nanoparticles were prepared by co-reduction of Pd and Sn precursors. The obtained PdSn nanoparticles possibly have a core-shell like structure with Pd cores and Sn-rich shells due to the fast reduction of Pd precursors. The Pd-SnO2/Al2O3 heteroaggreagte nanocatalysts were synthesized by calcination of PdSn/Al2O3 in air followed by H2 reduction. Various characterization techniques, such as HRTEM, XRD and XPS, were used to characterize the PdSn and Pd-SnO2. The Pd3-(SnO2)1/Al2O3 heteroaggreagte nanocatalysts with a ratio of Pd/Sn of 3/1 illustrated enhanced catalytic performances for p-nitroacetophenone and p-nitrobenzaldehyde hydrogenations relative to monometallic Pd nanocatalysts. Theoretical calculations using density functional theory suggested that Pd-SnO2 facilitates the adsorption of reactants in a higher degree than that of products, thus enhancing the catalytic activity even with partial coverage of Pd surfaces with SnO2. The blockage effect of SnO2 on Pd surfaces is speculated to enhance the catalytic selectivity for p-nitroacetophenone and p-nitrobenzaldehyde hydrogenations over Pd-SnO2 heteroaggregate nanocatalysts.
      Graphical abstract image

      PubDate: 2017-10-25T12:57:48Z
      DOI: 10.1016/j.apcata.2017.10.004
      Issue No: Vol. 549 (2017)
       
  • An attempt to improve Ag-based catalysts for allyl alcohol oxidative
           dehydrogenation to acrolein
    • Authors: T.T.N. Nguyen; Huchede Blanco Morfin J.L. Rousset Massin Aouine J.M.M.
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): T.T.N. Nguyen, M. Huchede, E. Blanco, F. Morfin, J.L. Rousset, L. Massin, M. Aouine, V. Bellière-Baca, J.M.M. Millet
      The oxidative dehydrogenation of allyl alcohol to acrolein over bulk alloyed and supported silver catalysts has been studied, with the aim of designing optimal Ag-based catalysts for this specific reaction. All of the tested catalysts were highly active and selective to acrolein at temperatures ranging between 340 and 380°C. The results show that the alloying of Ag with Au or Cu leads to alloys with upper surface compositions comprising approximately between 35 and 65% silver. Although these elements improve the activity of Ag catalysts, they decrease their selectivity, leading to lower acrolein yields. Various different Ag catalyst supports were prepared (LaPO4, Carbon nanotubes CNT, TiO2, Al2O3 and SiO2) using the impregnation method, and subsequently tested. This study reveals that the catalyst with the best performance is Ag/SiO2 with a yield in acrolein of 87.2% at 360°C. The results obtained with the tested catalysts are discussed, and the reasons of performance improvement or degradation caused by the presence of Au or Cu on the active silver sites, or by the presence of the supports, are raised.
      Graphical abstract image

      PubDate: 2017-10-11T22:48:35Z
       
  • Effect of γ-alumina nanorods on CO hydrogenation to higher alcohols over
           lithium-promoted CuZn-based catalysts
    • Authors: SuMin Choi; YoungJong Kang SangWoo Kim
      Abstract: Publication date: 5 January 2018
      Source:Applied Catalysis A: General, Volume 549
      Author(s): SuMin Choi, YoungJong Kang, SangWoo Kim
      To achieve high catalytic activities and long-term stability to produce higher alcohols via CO hydrogenation, the catalytic activities were tuned by controlling the loading amounts of γ-alumina nanorods and Al3+ ions added to modify Cu-Zn catalysts promoted with Li. The selectivity of higher alcohols and the CO conversion to higher alcohols over a Li-modified Cu0.45Zn0.45Al0.1 catalyst supported on 10% nanorods were 1.8 and 2.7 times higher than those with a Cu-Zn catalyst without nanorods and Al3+ ions, respectively. The introduction of the thermally and chemically stable γ-Al2O3 nanorod support and of Al3+ to the modified catalysts improves the catalytic activities by decreasing the crystalline size of CuO and increasing the total basicity. Along with the nanorods, a refractory CuAl2O4 formed by the thermal reaction of CuO and Al3+ enhances the long-term stability by increasing the resistance to sintering of the catalyst.
      Graphical abstract image

      PubDate: 2017-10-11T22:48:35Z
       
  • Direct synthesis of long-chain alcohols from syngas over CoMn catalysts
    • Authors: Yanzhang Yang; Tiejun Lin; Xingzhen Qi; Fei Yu; Yunlei An; Zhengjia Li; Yuanyuan Dai; Liangshu Zhong; Hui Wang; Yuhan Sun
      Abstract: Publication date: Available online 2 October 2017
      Source:Applied Catalysis A: General
      Author(s): Yanzhang Yang, Tiejun Lin, Xingzhen Qi, Fei Yu, Yunlei An, Zhengjia Li, Yuanyuan Dai, Liangshu Zhong, Hui Wang, Yuhan Sun
      CoMn model catalysts were prepared by co-precipitation and evaluated for higher alcohol synthesis (HAS) via syngas. The selectivity to oxygenates (mainly alcohols and aldehydes) was found to be higher than 20C% for the Na-promoted CoMn catalyst. Among the oxygenates, C2+ and C6+ fractions accounted for >90wt% and ∼50wt%, respectively. Metallic Co0 particles and MnCO3 were found in both Na-promoted and unpromoted CoMn catalysts after the reaction, whereas Co2C nanoparticles could only be observed in the spent Na-promoted catalyst. The addition of Na benefited the carbonization of cobalt and increased the selectivity to oxygenates and CO2. Our studies thus suggested that Co/Co2C were the bifunctional dual-sites for the oxygenates formation over the Na-promoted CoMn catalyst, where Co catalyzed CO dissociation and chain propagation, while Co2C was responsible for CO non-dissociative activation and subsequent insertion. In addition, the sole Co2C nanoparticles with certain exposed facets may also act as another kind of active dual-sites for oxygenates formation.
      Graphical abstract image

      PubDate: 2017-10-04T07:28:43Z
      DOI: 10.1016/j.apcata.2017.09.037
       
  • Variability of particle configurations achievable by 2-nozzle flame
           syntheses of the Au-Pd-TiO2 system and their catalytic behaviors in the
           selective hydrogenation of acetylene
    • Authors: Boontida Pongthawornsakun; Okorn Mekasuwandumrong; Francisco J.Cadete Santos Aires; Robert Büchel; Alfons Baiker; Sotiris E. Pratsinis; Joongjai Panpranot
      Abstract: Publication date: Available online 12 September 2017
      Source:Applied Catalysis A: General
      Author(s): Boontida Pongthawornsakun, Okorn Mekasuwandumrong, Francisco J.Cadete Santos Aires, Robert Büchel, Alfons Baiker, Sotiris E. Pratsinis, Joongjai Panpranot
      Catalysts with Au and Pd supported on TiO2 (Au:Pd 1:1wt/wt%) were prepared by 1- and 2-nozzle flame spray pyrolysis (FSP). The 2-nozzle configuration allowed to synthesize various particle configurations by separate or co-feeding of the metal precursor solutions to the two nozzles. For the Au-Pd/TiO2 system, four different catalyst particle configurations were investigated: “TiO2 +AuPd”, “Pd/TiO2 +Au”, “Au/TiO2 +Pd”, and “Pd/TiO2 +Au/TiO2”, where+separates the corresponding precursor solutions fed to the two nozzles. There were no significant differences in the specific surface areas and the average TiO2 crystallite sizes of the catalysts (100m2/g and 16–17nm, respectively) with the exception of “Pd/TiO2 +Au/TiO2”, which exhibited larger surface area and smaller crystallite size (152m2/g, 12nm) due to halving of the Ti precursor concentration in each nozzle. As revealed by CO chemisorption, XPS, and STEM-EDX results, the catalyst properties varied largely in terms of bimetallic AuPd particle compositions, the interaction between metal–metal and metal-support, and the location of Pd (or AuPd) on the TiO2. Among the catalysts studied, “TiO2 +AuPd” prepared with the 2-nozzle system exhibited the highest conversion of acetylene (∼50%) at 40°C with high selectivity to ethylene (>95%). Co-feeding the noble metal precursors together with the Ti precursor afforded less active catalysts due to the formation of Ti-O species partially covering the most active bimetallic AuPd particles. Compared to the commercially available acetylene hydrogenation catalyst and the AuPd/TiO2 prepared by conventional co-impregnation and deposition-precipitation, all the FSP-AuPd/TiO2 catalysts showed superior performances under the reaction conditions used.
      Graphical abstract image

      PubDate: 2017-09-14T09:21:19Z
      DOI: 10.1016/j.apcata.2017.09.014
       
 
 
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