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  Subjects -> ENGINEERING (Total: 2277 journals)
    - CHEMICAL ENGINEERING (191 journals)
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    - ELECTRICAL ENGINEERING (103 journals)
    - ENGINEERING (1203 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)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
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  
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Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
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Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
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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 Catalysis Today
  [SJR: 1.348]   [H-I: 164]   [8 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0920-5861
   Published by Elsevier Homepage  [3049 journals]
  • Computational and experimental study of the second metal effect on the
           structure and properties of bi-metallic MeMoS-sites in transition metal
           sulfide catalysts
    • Abstract: Publication date: Available online 14 November 2017
      Source:Catalysis Today
      Author(s): E.A. Permyakov, V.S. Dorokhov, V.V. Maximov, P.A. Nikulshin, A.A. Pimerzin, V.M. Kogan
      Bimetallic (Me)MoS2 (Me=Nb, Fe, Co, Ni) sulfide systems, both modified and non-modified by potassium, were investigated by the DFT method. Geometric and electronic structures of active sites were compared in terms of CO and hydride hydrogen adsorption. Most of the studied metals are electron density acceptors on the S-edge of the crystallite, which inhibits hydride hydrogen adsorption and deactivates the S-edge. The CO adsorption energy on the Me-edge decreased in the order Fe>Co>Ni. Computational data were verified by experimental tests in syngas conversion. Modification by potassium was shown to hinder σ-bonding of the adsorbed molecule and to stabilize hydride hydrogen.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • Visible-light Photooxygenation of α-Terpinene in a Falling Film
           Microreactor
    • Abstract: Publication date: Available online 11 November 2017
      Source:Catalysis Today
      Author(s): Oksana Shvydkiv, Klaus Jähnisch, Norbert Steinfeldt, Alexander Yavorskyy, Michael Oelgemöller
      The photooxygenation of α-terpinene was investigated in a falling film microreactor. The formation of microfilms and the flow operation allowed for a safe and controllable production of the bioactive endoperoxide ascaridole. Stepwise investigation of the process parameters resulted in the selective formation of ascaridole of up to 89% and a productivity of 2.5–3.2molL−1 h−1, respectively.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • Catalytic combustion of vineyard pruning waste in a conical spouted bed
           combustor
    • Abstract: Publication date: Available online 11 November 2017
      Source:Catalysis Today
      Author(s): María J.San José, Sonia Alvarez, Raquel López
      The feasibility of a conical spouted bed combustor for the thermal catalytic exploitation of vineyard pruning waste, under different operating conditions has been analyzed. Stable-flow regimes of vine shoot beds with a Pd catalyst were determined over a wide range of combustion conditions. With the aim of improving the combustion yield, thermal exploitation of vine shoots was performed in batch mode, in a conical spouted bed combustor at temperatures ranging from 250 to 550°C, with and without the Pd catalyst. The influence of the catalyst and inlet gas temperature on the flue gas concentration was analyzed. The experimental vine shoot combustion yield with the Pd catalyst at different inlet gas temperatures were compared with those obtained without the catalyst. The high experimental combustion efficiency calculated from the flue gases concentrations demonstrates the favorable performance of the conical spouted bed combustor for the catalytic combustion of vine shoots.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • Effects of preparation technique and lanthana doping on Ni/La2O3-ZrO2
           catalysts for hydrogen production by CO2 reforming of coke oven gas
    • Abstract: Publication date: Available online 11 November 2017
      Source:Catalysis Today
      Author(s): Hongwei Cheng, Guangshi Li, Hongbin Zhao, Xionggang Lu, Qian Xu, Wei Tao
      A series of Ni/La2O3-ZrO2 catalysts were prepared by homogeneous precipitation, template or sol-gel technique and used for hydrogen production from coke oven gas by CO2 reforming. The catalysts were characterized by BET, XRD, TPR, TPH, TEM and TG–DSC. A study is also carried out to observe the effect of lanthana loading on the reforming reaction. TPH results indicated the presence of more than two types of carbonaceous species on the used catalysts, which are categorized based on temperature difference. The low-temperature carbon species could be considered as the active sites for the reforming reaction. Experiments and TG-DSC results revealed that all of the catalysts present good catalytic performance and excellent anti-carbon property. The test results showed that the catalysts prepared by sol-gel method exhibited the highest catalytic activity due to their suitable pore size distribution. The Ni/La2O3-ZrO2 catalyst with 8wt% lanthanum oxide loading provides the best catalytic activity, which will be promising application on catalytic CO2 reforming of COG in the future.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • Pd doped CaCoxZr1-xO3-δ perovskites for automotive emissions control
    • Abstract: Publication date: Available online 11 November 2017
      Source:Catalysis Today
      Author(s): Qinghe Zheng, Marty Lail, Kelly Amato, Jonathan Todd Ennis
      CaCo x Zr1-x O3-δ (x =0, 0.3, 0.5, 0.7 and 0.9) perovskites with and without Pd doping were synthesized for the first time and reported here to show outstanding redox property and oxygen storage capacity (OSC) compared to the ceria-based oxygen storage materials (OSMs). The studied perovskites retain their main phase of orthorhombic Lakargiite CaZrO3 structure, and were characterized by x-ray fluorescence (XRF), x-ray diffraction (XRD), temperature programmed reduction (TPR) and dynamic redox cycle measurements. Partial substitution of Co by Zr at B sites enhanced the perovskite structural crystallinity and stability, material reducibility and OSC properties, giving optimized OSM composition when x was around 0.5. Further kinetic studies showed a first order reaction mechanism with an activation energy (E a) of 0.159eV for CaCo0.5Zr0.5O3-δ. For Pd-containing samples, Pd was present in both forms of bulk Pd2+ and surface Pd0, and the amount of surface Pd0 increased with increasing Pd loading. Pd dopant also facilitated the Co reduction and improved the catalyst reducibility. Under simulated exhaust conditions at fuel lean-rich conditions (stoichiometric numbers of 1.16, 1.07 and 0.95), Pd-doped CaCo0.6-y Zr0.4Pd y O3 (y =0.05 and 0.1) samples showed profound catalytic activity towards C3H6 and CO oxidation (T 50 s<280°C at fuel lean-rich), suggesting their potential application for automotive emissions control.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • Two-dimensional MXene/A-TiO2 composite with unprecedented catalytic
           activation for sodium alanate
    • Abstract: Publication date: Available online 11 November 2017
      Source:Catalysis Today
      Author(s): Yanping Fan, Zhenluo Yuan, Guodong Zou, Qingrui Zhang, Baozhong Liu, Qiuming Peng
      Differing from graphene with a carbon element component, analogous metallic-graphene two-dimensional layered titanium carbide (2D MXene) provides more opportunities to achieve better surface functionalization. Herein, a thin layered 2D MXene/A-TiO2 composite was prepared by chemical exfoliation and hydrothermal decomposition. The 2D MXene/A-TiO2 composite exhibits high catalytic activity in the adsorption and desorption of hydrogen kinetics for NaAlH4. The critical dehydrogenation temperature of NaAlH4 is ∼90°C. The first-stage dehydrogenation (∼3.0wt.%) is accomplished in 50min at 110°C. After the first activated cycle, a constant cycling capacity of 4.7wt.% is remained for a minimum of five cycles tests. It is found that the excellent catalytic activation should be ascribed to the synergistic effect between homogenous distributed Ti-H and TiC, which are originated from MXene/A-TiO2. The results represent a new step forward in the applications of MXene catalytic dehydrogenation and provide new strategies in the quest for new functional MXene derivatives by in-situ modification.
      Graphical abstract image

      PubDate: 2017-11-15T15:21:53Z
       
  • IFC - Editors; Editorial Board &amp; scope
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297


      PubDate: 2017-11-02T03:11:31Z
       
  • Contents list
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297


      PubDate: 2017-11-02T03:11:31Z
       
  • Preface: Environment EECAT
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Junhua Li, Keld Johansen, Koichi Eguchi, Zebao Rui, Yongdan Li


      PubDate: 2017-11-02T03:11:31Z
       
  • NO adsorption and influence of the control of temperature over catalytic
           test results for NO oxidation
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): A. Serrano-Lotina, A.C. Bueno, C. Goberna-Selma, P. Ávila, M.A. Bañares
      A preliminary partial oxidation of NO to NO2 is helpful for low-temperature SCR. Oxidation of NO was evaluated over a Pt-based catalyst. Prior to the study, which was focused on the influence of the control of temperature over the catalytic results, PID process parameters of the catalytic reaction system were optimized showing that the unit control refinement is crucial for a good performance of the catalytic tests. This is particularly important when a significant population of adsorbed species build on the surface of the catalyst, which is the present case; adsorption phenomena may lead to deceiving apparent conversion values. Temperature programmed desorption tests showed that O2 is essential for the NO adsorption. Three modes of heating/cooling were checked. When ramp mode was used for controlling the temperature, adsorption/desorption phenomena led to deceptive results of catalytic conversion. However, when stepped mode was evaluated stationary state was reached, and then NO disappearance was only due to NO conversion to NO2.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • A kinetic modeling study of NO oxidation over a commercial Cu-CHA SCR
           catalyst for diesel exhaust aftertreatment
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Amir R. Fahami, Isabella Nova, Enrico Tronconi
      Based on a redox kinetic mechanism, we derive a rate expression for NO oxidation over Cu-zeolite catalysts, and fit it to a set of NO oxidation experiments carried out over a commercial Cu-zeolite SCR catalyst with chabazite structure. The so developed model is able to predict the complex behavior of the NO oxidation reaction in good agreement with data covering the effects of NO, O2, NO2 and H2O feed contents, GHSV and reaction temperature (150–350°C). We show also that the dependency of the negative kinetic order of NO2 on the operating temperature is consistent with the proposed mechanism. Since NO oxidation in an NH3-SCR converter may affect the overall deNOX activity, the herein presented model is also relevant to characterize and describe the behavior of state-of-the-art SCR catalysts.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • NH3-SCR performance improvement over Mo modified Mo(x)-MnOx nanorods at
           low temperatures
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Xiaolei Hu, Qiang Shi, He Zhang, Pengfei Wang, Sihui Zhan, Yi Li
      A series of novel Mo modified Mo(x)-MnOx catalysts were prepared by co-precipitation and used for NH3-SCR removal of NOx at low temperatures, which were characterized by XRD, BET, TEM, H2-TPR, NH3-TPD, XPS and in situ DRIFT. It can be found that the addition of Mo species could induce the granular crystals transformed to the oblong-shaped nanorods, then BET surface area was obviously increased. Among the tested catalysts with different doping ratio, Mo(2)-MnOx exhibited nearly 100% NOx conversion from 150°C to 350°C with a gas hourly space velocity of 50000h−1, meanwhile, better H2O resistance performance could also be found on Mo(2)-MnOx catalyst. These were due to its higher Mn4+ content, abundant surface adsorbed oxygen (Oα) and more acid sites based on H2-TPR, NH3-TPD, XPS and in situ DRIFT. Moreover, these preferable features could be correlated with the addition of Mo species by contrast with pure MnOx.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Oxidizing, trapping and releasing NOx over model manganese oxides in
           alternative lean-burn/fuel-rich atmospheres at low temperatures
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Li-Hong Guo, Li Guo, Dong-Yue Zhao, Zhong-Nan Gao, Ye Tian, Tong Ding, Jing Zhang, Li-Rong Zheng, Xin-Gang Li
      Herein, we report the performance of the catalytic oxidizing, trapping and releasing NO over the MnOx (Mn2O3, Mn3O4 and MnO2) model Lean NOx Traps (LNT) catalysts at low temperatures (≤200°C). Among these typical MnOx samples, Mn2O3 has the high NO oxidizability, and can efficiently trap and release NOx in the alternative lean-burn/fuel-rich atmospheres. Our characterization results show that enrichment of the Mn3+ cations and active surface oxygen species probably plays the important role for NO oxidation. Although MnO2 has the biggest NOx storage capacity in the lean-burn atmosphere, the strong adsorption strength between MnO2 and NOx inhibits the release of the stored NOx species in the fuel-rich atmosphere. The in situ DRIFTS and NO-TPD studies indicate that the trapped NOx on Mn2O3 can transform from nitro compounds to nitrites, and then to nitrates along with the increased adsorption temperature.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Keggin-tungstophosphoric acid decorated Fe2O3 nanoring as a new catalyst
           for selective catalytic reduction of NOx with ammonia
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Zhaoyong Ren, Yunfei Teng, Leyu Zhao, Rui Wang
      With the aim of developing a new sort of highly effective and eco-friendly catalyst for NOx abatement, 40wt.% 12-tungstophosphoric acid (TPA)-decorated Fe2O3 nanorings were synthesized via a microwave-assisted hydrothermal method followed by simple mechanical-chemistry grinding. Analyses of SEM,TEM and XRD demonstrated the successful synthesis of Fe2O3 nanorings. HRTEM image manifested that 3 layers of TPA polyanions were coated on the external surface of Fe2O3 nanorings. FTIR and NH3-TPD were also employed to characterize the loading of TPA on Fe2O3 and the distribution of acid sites of the composite material. The results indicated the existence of interaction between the terminal oxygen of TPA and Fe3+ of Fe2O3 nanorings. H2-TPR and SCR experiment showed that TPA played a significant promotion role in the SCR reaction of NOx, while Fe2O3 served not only as the active ingredient but also as the support of TPA. TPA/Fe2O3 achieved a satisfactory SCR performance, with the NOx conversion higher than 92% maintained in a wide temperature range between 230 and 500°C. Additionally, the catalyst exhibited an excellent SO2-resistance capacity.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Influence of phosphorus on Cu-SSZ-13 for selective catalytic reduction of
           NOx by ammonia
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Kunpeng Xie, Kirsten Leistner, Kurnia Wijayanti, Ashok Kumar, Krishna Kamasamudram, Louise Olsson
      The influence of phosphorus on Cu-SSZ-13 NH3-SCR catalysts was investigated in order to reveal the deactivation behavior of Cu-SSZ-13 in the presence of phosphorus-containing poisons in the exhaust of diesel engines. The phosphorus-poisoning was simulated by treating the Cu-SSZ-13 catalysts with (NH4)2HPO4 aqueous solution using incipient wetness impregnation method. The focus of the study was the effect of phosphorous on the different reactions occurring on the SCR catalyst, including ammonia oxidation, NO oxidation and standard SCR using monolith catalysts. Moreover, characterization such as ICP-SFMS, N2-physisorption, and NH3-TPD were employed for the evaluation of the physical and chemical properties of the P-impregnated catalysts. Physically blocking of pores and poisoning of acidic sites were observed on the P-impregnated catalysts. In addition, we observed that phosphorus severely suppressed ammonia oxidation and NO oxidation, while its impact on standard SCR reaction was nearly negligible below 300°C. Interestingly, a promotive effect was found at higher temperatures, likely due to the severely inhibiting effect on NH3 oxidation caused by the formation of copper phosphates in the large cages (i.e. 8-membered rings) of Cu-SSZ-13.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Effect of sulfur aging and regeneration on low temperature NO adsorption
           over hydrothermally treated Pd/CeO2 and Pd/Ce0.58Zr0.42O2 catalysts
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): YoungSeok Ryou, Jaeha Lee, Hyokyoung Lee, Chang Hwan Kim, Do Heui Kim
      Various treatments such as hydrothermal aging (HTA), sulfur aging (SA), and regeneration (DeSOx) were applied to Pd/CeO2 and Pd/Ce0.58Zr0.42O2 (Pd/Ce58) catalysts to understand the effect of sulfur aging and regeneration on the changes in NO adsorption ability and physicochemical properties of catalysts. The addition of Pd to Ce-based supports results in the larger amount of NO adsorbed at higher desorption temperature (250–500°C) than CeO2. Also, Pd/CeO2 has larger amount of NO adsorbed than Pd/Ce58, indicating that ceria is the active site for NO adsorption at low temperature. However, SA treatment on both catalysts gives rise to the negligible NO adsorption ability since it leads to form thermodynamically more stable Ce(SO4)2. Structural and textural analysis after regeneration shows that Pd/Ce58 maintains the pore size distribution with the similar crystalline size, whereas Pd/CeO2 does not, despite the similar amount of residual sulfur over two samples. In addition, Pd dispersion is recovered completely over the former sample, although the latter does not. However, the fact that both regenerated catalysts do not recover the NO adsorption ability to the level of HTA ones implies that either textural property or Pd dispersion cannot account for the degradation of NO adsorption at low temperature. Instead, H2-TPR analysis indicates that the intimate interaction Pd and ceria is lost for both samples after regeneration, as evidenced by the disappearance of the simultaneous reduction of CeO2 and PdO below 20°C. Hence, it can be concluded that the exposure of SO2 and the subsequent regeneration significantly affects the interaction between PdO and CeO2, resulting in the irreversible decrease in the NO adsorption ability at low temperature.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Fundamental chemistry of V-SCR catalysts at elevated temperatures
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Søren B. Rasmussen, Billie L. Abrams
      Understanding the structural properties of vanadium at high temperatures for vanadia-based SCR at nearly monolayer coverage is an important topic, which has influence on e.g. automotive applications. Nowadays, improved, stabilized Anatase combined with profound technical insights makes high and low temperature behavior of V-SCR significantly better. However, the equilibrium between surface anchored Vv =O and interstitial V4+ species intercalated into the TiO2 matrix is changed during a thermal runaway of the catalytic system in question, and vanadium catalyzes Rutilation of the Anatase. Hydrothermal aging of the V-SCR catalyst is not related to vanadium evaporation, but to changes of the surface chemistry. Our observations were achieved by using in-situ Raman spectroscopy at relevant temperatures and gas conditions, showing that the vanadia-tungsta catalyst is stable under hydrothermal conditions at 550°C and that a VXTi1-XO2 phase is formed during thermal runaway of the catalyst, exemplified by exposure of an excess monolayer vanadia titania model catalyst to 750°C. These observations, combined with new achievements at low temperature for corrugated monolithic catalysts at 200°C reveal that vanadium based catalysts remain a robust, cost efficient and sulfur tolerant solution for automotive exhaust gas cleaning meeting future demands.

      PubDate: 2017-11-02T03:11:31Z
       
  • Effect of cobalt substitution on nanoporous nickel phosphate VSB-5
           catalyst for the catalytic reduction of NO by H2
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Qian Yang, Zhi Chen, Dantong Zhou, Weihua Shen, Shuichi Naito
      To develop and apply new type catalyst is an effective route for reducing the NOx emission. The catalytic reduction of NO by H2 without O2 could be used as a model reaction for the evaluation of a given catalyst. Cobalt doped nanoporous nickel phosphate VSB-5 is a recently developed catalyst and is firstly applied to catalytically reduce NO by H2 in the absence of O2. NO can be catalytic reduced by H2 on the prepared samples. The catalytic performance has close relations with the amount of doped cobalt and enhanced catalytic performance has been observed on cobalt substituted samples. Large amount of NO could be adsorbed on the surface of Co-VSB-5 which works as the active component during the catalytic process. Accordingly, a reaction mechanism is also proposed. The prepared catalyst may have potential application in the de-NOx process.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Catalyzed soot filters (CSF) with H2S control function for lean NOx trap
           (LNT) systems
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yuejin Li, Michael Weinstein, Matthew Caudle, Steven Steeley, Gerd Grubert, Alfred Punke
      A lean NOx trap (LNT) based emission control system typically consists of a LNT catalyst for NOx reduction and CO/HC oxidation and a catalyzed soot filter (CSF) for particulate filtration and CO/HC oxidation. During LNT’s operation, it is required that sulfur compounds bound to the catalyst surface must be periodically removed in a reducing environment to recover the NOx storage sites. However, this desulfation process produces high levels of H2S emission, which must be suppressed. A series of catalyzed soot filters has been investigated for H2S suppression, and CuO based filters were found to be very efficient in converting H2S to SO2. Only 0.05g/in3 bulk CuO can convert 500ppm H2S to SO2 with 100% efficiency at GHSV=34,000h−1 after a high temperature aging treatment (800°C/16h with 10% H2O). However, CuO was found to severely poison the precious metal (PGM) functions in the filter, dramatically reducing its CO/HC oxidation activity. The degree of poisoning is proportional to the CuO loading and also related to the proximity between CuO and the PGM within the filter microstructure. A zoned coating approach, where CuO and PGM occupy two non-overlapping zones in the axial direction, has been systematically investigated with both laboratory reactor and engine tests. The zoned H2S-CSFs, with CuO in the front of the filter and the PGM in the rear, were demonstrated to be effective catalysts that can fulfil both H2S suppression and CO/HC oxidation requirements.
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      PubDate: 2017-11-02T03:11:31Z
       
  • CuO-CeO2 mixed oxide catalyst for the catalytic decomposition of N2O in
           the presence of oxygen
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Zhiming Liu, Chenxi He, Biaohua Chen, Haiyan Liu
      The catalytic decomposition of N2O was investigated over a series of CuO-CeO2 mixed oxide catalysts prepared by the hydrothermal method. It was found that CuO-CeO2 mixed oxide catalyst exhibited higher activity than pure CuO and CeO2. The co-existence of CuO and CeO2 exhibited a synergetic effect, which inhibited the crystallization of the CuO phase, leading to the high surface area. Moreover, the two redox couples (Ce4+/Ce3+ and Cu2+/Cu+) formed over CuO-CeO2 mixed oxide contribute to the desorption of surface adsorbed oxygen species and thus the regeneration the active sites, which is favorable for the catalytic N2O decomposition to proceed.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • The promotion effect of Fe to Cu-SAPO-34 for selective catalytic reduction
           of NOx with NH3
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Huawang Zhao, Huisheng Li, Xianghui Li, Mengke Liu, Yongdan Li
      A number of Fe loaded Cu-SAPO-34 (Fe: Cu-SAPO–34=0.5, 1 and 1.5wt.%) catalysts were prepared with incipient wetness impregnation of iron acetate solution on a one-pot synthesized Cu-SAPO-34 sample. The Fe/Cu-SAPO-34 sample with 1wt.% Fe loading shows the best selective catalytic reduction performance among the samples tested at temperatures above 200°C. The results of ultraviolet-visible diffuse reflectance spectroscopy indicate that isolated Fe3+ ions, FexOy oligomers, and Fe2O3 particles coexist in the Fe incorporated samples. Further examinations tell that the bulk CuO on the surface in the Cu-SAPO-34 sample with appropriate amount of Fe addition transforms to isolated Cu2+ ions, which enhances its catalytic activity in the temperature range of 200–350°C. The Fe: Cu-SAPO–34=1wt.% sample exhibits a lower NH3 oxidation ability at high temperatures than that of Cu-SAPO-34, which is due to the reduced amount of bulk CuO species on the surface. Both the reduced NH3 oxidation ability and the additional isolated Fe3+ sites contribute to the excellent activity of the Fe: Cu-SAPO-34=1wt.% sample above 350°C.
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      PubDate: 2017-11-02T03:11:31Z
       
  • N2O formation during NOx storage and reduction using C3H6 as reductant
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Jinxin Zhu, Meiqing Shen, Jianqiang Wang, Xiuting Wang, Jun Wang
      N2O formation over Pt-BaO/Al2O3 catalysts was found to be involved in a complex reaction network induced by C3H6 evolutions during NOx storage reduction process. C3H6 evolutions in the rich period travelled along cracking to CxHy(ad), partial oxidation to COad and followed by NCOad production. In the lean period, residual NCOad reacting with the introduced NO/O2 led to the formation of N2O. In the rich period, N2O was originated from the chemical adsorption of NO on Pt0 surface caused by C3H6 reduction. In addition, both H2O and CO2 in the feed had significant influences on N2O formation in rich period. In the presence of H2O, high performance of water-gas shift was found at T≥300°C, and steam reforming of C3H6 occurred at T≥350°C. These reactions produced a large number of Had that facilitated NH3 production and thereby decreased N2O formation. When CO2 was introduced to the feed, CO2 reforming of C3H6 appeared at T≥300°C as a result of COad production. These parts of COad were responsible for the increase in N2O formation.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Control of Hg0 and NO from coal-combustion flue gases using
           MnOx-CeOx/mesoporous SiO2 from waste rice husk
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Kuan-Hung Liu, Ming-Yin Chen, Yun-Chih Tsai, Hong-Ping Lin, Hsing-Cheng Hsi
      MnOx- and MnOx-CeOx-impregnated SiO2 particles were developed from waste rice husk via a hydrothermal synthesis for removal of Hg0 and NOx. MnOx of 5 or 20wt% associated with 5 or 10wt% CeOx was impregnated into resource-recovery mesoporous SiO2. The presence of MnOx and CeOx reduced the specific surface area (SBET) and pore volume of the SiO2 particles. Nevertheless, MnOx(5%)-CeOx(5%)/SiO2 possessed the largest SBET (123m2 g−1) among the impregnated samples. Electron microscopy images show that the metal-oxide-impregnated SiO2 was plate-shaped with sizes of 3–10μm. Mn4+/Mn3+ and Ce4+/Ce3+ were the major valence states in the MnOx-CeOx/SiO2 samples; the ratio of Mn4+/Mn3+ increased as CeOx was present. The presence of both amorphous/highly dispersed and crystalline MnOx was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. Removal of Hg0 and NO was achieved by both MnOx/SiO2 and MnOx-CeOx/SiO2 at between 150 and 350°C. MnOx-CeOx/SiO2 showed greater Hg and low-temperature NO removal potentials than MnOx/SiO2, with MnOx(20%)-CeOx(10%)/SiO2 having Hg0 removal efficiency of 96% at 150°C and nearly 100% reduction of NO under a broad operation window of 100–300°C. These results indicate that resource recovery of waste rice husk for producing SiO2 adsorbent/catalyst for Hg0 and NOx removal is successful.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Development of HCl-treated titania nanotube photocatalysts for dye
           photodegradation and low-concentration elemental mercury removal
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Cheng-Yen Tsai, Chen-Wuing Liu, Yi Hao Chan, Ting-Yu Chang, Bing-Ci Chen, Hsing-Cheng Hsi
      TiO2 nanotube (TNT) photocatalysts were synthesized through a facile one-step hydrothermal method using Degussa P-25 as precursor. The resulting TNTs were subsequently washed with deionized water and 0.1–1.0M HCl to possess a variety of physicochemical properties. Anatase was the major crystalline phase for the resulting TNTs. The Brunauer-Emmett-Teller surface area of TNTs was 307–392m2 g−1. Hydroxyl groups and oxygen vacancies were shown to be generated on the surface of all TNTs. Photocatalytic activity of TNTs for Congo red and crystal violet dye decomposition was strongly determined by their pre-adsorption abilities, which are greatly affected by solution pH. Hg0 removal by the TNTs was enhanced with increased HCl concentration and the presence of O2 in the test environment; however, the presence of water vapor reduced the Hg0 capture due to competitive adsorption of H2O. The Cl functionality formed on the surface of TNTs due to HCl treatment appeared to act as one of the adsorption sites and enhance Hg0 removal, as well as helping in against the competition from water molecules. Nevertheless, the unwashed HCl residues also obstructed other active sites on TNT surface, such as oxygenated groups that also play important role in Hg0 oxidation and adsorption.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Influences of sodium and potassium cations on the hydrodesulfurization
           performances of Pd and Pt catalysts supported on siliceous MCM-41
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Chao Dong, Xiang Li, Anjie Wang, Yongying Chen
      Na+ and K+ were introduced to siliceous MCM-41 (Si-MCM-41) by ion-exchange of Si-MCM-41 with sodium oxalate or potassium oxalate, respectively. The supported Pd and Pt catalysts were prepared by an incipient wetness impregnation method. Their hydrodesulfurization (HDS) performances were evaluated using dibenzothiophene as the model molecule. The introduction of Na+ or K+ led to a decrease in the metal dispersions but an increase in the electron densities of metal sites. It also strongly inhibited the adsorption, dissociation, and probably the spillover of H2 on the catalysts. Independent of the type of metal, a push-pull effect of Na+ and K+ on the HDS performances of the Pd and Pt catalysts was observed. They on the one hand enhanced the direct desulfurization pathway (DDS), but on the other hand hindered the hydrogenation route. The DDS activity of Pt increased almost linearly with its electron density. These are discussed by considering both the negative effects of Na+ and K+ on the formation of active hydrogen species and their positive role on the electron densities of the metal sites. The Pt catalysts deactivated faster than the Pd catalysts. The kinetic study indicates that Na+ and K+ did not affect the deactivation of the catalysts.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Study on the coating of nano-particle and 3DOM LaCoO3 perovskite-type
           complex oxide on cordierite monolith and the catalytic performances for
           soot oxidation: The effect of washcoat materials of alumina, silica and
           titania
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Long Tang, Zhen Zhao, Yuechang Wei, Jian Liu, Yang Peng, Kaixiang Li
      The novel catalysts of LaCoO3/ɤ-Al2O3/cordierite monolith, LaCoO3/SiO2/cordierite monolith, LaCoO3/TiO2/cordierite monolith were prepared by using aluminum oxide, silicon dioxide and titanium dioxide nanoparticles as washcoat and monolithic cordierite as the monolithic ceramic substrate. The obtained samples were characterized by means of XRD, SEM, EDS, BET, and ultrasonic vibration test (Medi II Pselecta). The surface area of the cordierite monolith-supported LaCoO3/ɤ-Al2O3 is larger than those of LaCoO3/SiO2 and LaCoO3/TiO2. The coating of alumina, silica oxide and titania nanoparticles could increase the surface area of monolithic cordierite and also endue the coated layer with engineered structure. The results of thermal treatment experiment indicate that the good thermal stability of the ɤ-Al2O3 coating on the cordierite. The ultrasonic vibration test results showed that the washcoat was adhered to the substrate strongly. The weight loss for the samples LaCoO3/ɤ-Al2O3/cordierite (the most desired preparation protocol in this study) eventually reached about 3%, which was considered as a low weight loss. The LaCoO3/ɤ-Al2O3/cordierite monolith catalysts were successfully prepared by coating ready-made 3DOM LaCoO3 (perovskite-type oxides) catalysts onmonolithic cordierite substrate with a dip-coating method by employing aluminasol for the first time. The catalytic activities of a series of monolithic catalystsLaCoO3/ɤ-Al2O3/cordierite, LaCoO3/ɤ-Al2O3/cordierite (3DOM-catalysts), LaCoO3/SiO2/cordierite, LaCoO3/TiO2/cordierite were evaluated for soot combustion. Thenano LaCoO3/ɤ-Al2O3/cordierite catalysts gave the highest catalytic activity for soot combustion among the studied catalysts. The T10, T50, T90 over the LaCoO3/ɤ-Al2O3/cordierite catalyst were 199.4°C, 340.5°C, 405.3°C, respectively, and s c o 2 m was 99.9%.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Combined adsorption and catalytic ozonation for removal of endocrine
           disrupting compounds over MWCNTs/Fe3O4 composites
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yajing Huang, Wenjun Xu, Lingling Hu, Jiawei Zeng, Chun He, Xiuqin Tan, Zhuoyan He, Qiong Zhang, Dong Shu
      MWCNTs/Fe3O4 magnetic composites, combined adsorption and catalytic ozonation behavior, were synthesized by a hydrothermal process. The synthesized MWCNTs/Fe3O4 composites were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), element analysis and Brunauer-Emmett-Teller (BET) surface area. The adsorption performance and catalytic activity of MWCNTs/Fe3O4 for BPA removal in aqueous solution were evaluated. The results showed that the synthesized MWCNTs/Fe3O4 exhibited an excellent adsorption ability and catalytic ozonation activity owning to its large specific surface areas, hollow tube channels and abundant surface oxygen-containing groups, leading to high adsorption for BPA and O3, high retention and utilization of O3 molecules on the composites. In addition, the catalytic ozonation performance of MWCNTs/Fe3O4 could be improved by increasing surface oxygen-containing groups to accelerate O3 decomposition, thus producing more OH radicals. Moreover, BPA removal efficiency could be improved by increasing dose of catalyst, pH value and the concentration of humic acid (HA). The fluorescence spectra and OH radicals measurement displayed that HA could greatly increase OH radicals via inducing more surface oxygen-containing groups on the catalyst, thus, promoting BPA removal. Furthermore, MWCNTs/Fe3O4 showed the great stability and durability during several reaction recycles.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Synergetic effect of oxygen vacancy and Pd site on the interaction between
           Pd/Anatase TiO2(101) and formaldehyde: A density functional theory study
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Xuyu Wang, Zebao Rui, Yingqing Zeng, Hongbing Ji, Zheng Du, Qinglei Rao
      Insights into the functions and the synergetic effects of oxygen vacancy and noble metal sites on the performance of the reducible oxide supported noble metal catalysts are very important in designing formaldehyde catalysts. Herein, the roles of oxygen vacancies and Pd sites, and their synergistic effect on the interaction between HCHO and Pd/Anatase TiO2(101) surface were systematically studied by a density functional theory (DFT) study. It is found that both the presence of oxygen vacancy and Pd site can promote the HCHO adsorption over TiO2(101) surface. The presence of Pd site is beneficial for the oxygen vacancy formation by reducing its formation energy. Furthermore, synergetic effect of oxygen vacancy and Pd site on the interaction between Pd/TiO2(101) and HCHO is demonstrated for the case with the co-presence of oxygen vacancy and Pd site. In this situation, the oxygen atom of HCHO molecular occupies the oxygen vacancy and the carbon atom of HCHO connects with the Pd site, and a larger adsorption energy is obtained in comparison with the cases with only oxygen vacancy or Pd site present. These results indicate that both oxygen vacancy manufacturing and Pd doping can strength the HCHO adsorption over TiO2(101) surface, and their synergistic effects further promote the interaction between HCHO and Pd/TiO2 catalyst, which is beneficial for the HCHO oxidation.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Insight into the enhanced performance of TiO2 nanotube supported Pt
           catalyst for toluene oxidation
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Zebao Rui, Minni Tang, Weikang Ji, Junjie Ding, Hongbing Ji
      Featuring an assembly of identical pores, TiO2 nanotube array (TiNT) makes an ideal monolith-like support of noble metal catalysts for volatile organic compounds combustion. Herein, the deep oxidation of gaseous toluene over Pt/TiNT and anatase TiO2 (ATiO2) particles supported Pt catalysts are studied and compared. Pt/TiNT demonstrates remarkably enhanced performance over Pt/ATiO2 powder catalyst, and ranges among the best performances of the state of the art Pt based catalysts. A toluene conversion of (>)95% at 185°C and a multiple heating-cooling cyclic stable performance with a time of (>)300h are achieved over 0.4wt% Pt/TiNT. In situ DRIFTS study indicates that toluene is sequentially oxidized to benzaldehyde, benzoate, aliphatic carboxylates species, CO and finally to CO2, and the decomposition of benzoate species is the key step. The unique performance of Pt/TiNT is attributed to its ordered monolith-like structure, well-dispersion and surface enrichment of Pt, and enhanced benzoate species decomposition rate.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Highly effective self-propagating synthesis of CeO2-doped MnO2 catalysts
           for toluene catalytic combustion
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Luming Li, Fangli Jing, Jinlong Yan, Jiang Jing, Wei Chu
      Using a facile new synthesis method, the fabrication of cerium oxide doped birnessite MnO2 (δ-MnO2) catalysts has been operated, for the toluene catalytic combustion. These samples were investigated by XRD, Raman, TEM, BET, H2-TPR and XPS techniques and their catalytic activities were investigated and compared. The catalytic combustion of toluene was investigated as the model reaction for VOCs abatement. The several CeO2/MnO2 based nano composites were accomplished via controlling the molar proportion of potassium permanganate and cerium acetate raw materials. The subtle CeO2 doped δ-MnO2 catalyst displayed better reducibility at lower reduction temperature, with the higher Mn4+/Mn3+ ratio, which converts completely the 1000ppm toluene to CO2 and H2O at 318°C and its T90 is 277°C. The excellent catalytic performance of Mn12Ce1Ox catalyst might be resulted from the synergistic effect between the highly dispersed CeO2 nanoparticles and the δ-MnO2 substrate at their interface. These new observations provide a new perspective on the design of the high activity catalyst for decomposing the volatile organic compounds (VOCs abatement).

      PubDate: 2017-11-02T03:11:31Z
       
  • Bridging the reaction route of toluene total oxidation and the structure
           of ordered mesoporous Co3O4: The roles of surface sodium and adsorbed
           oxygen
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Kezhi Li, Jianjun Chen, Bingyang Bai, Shen Zhao, Fangyun Hu, Junhua Li
      Catalysts with ordered mesoporous structure usually behave superior in total oxidation of toluene. However, the link between reaction route and ordered mesoporous structure is still not fully founded currently. In this work, Co3O4 is selected as a model catalyst to illustrate the reaction route. The intermediates in the oxidation of toluene were analyzed via in situ Fourier transform infrared spectroscopy (in situ FTIR), high performance liquid chromatography (HPLC) and temperature programmed oxidation (TPO) experiment. Here we prove benzoquinone route as a special reaction route only observed in ordered mesoporous Co3O4, coexisting with the commonly reported benzoate route. Benzoquinone route is favored especially at lower temperature, accelerating the reaction rate, and acts as a crucial intrinsic reason for the better performance of ordered mesoporous Co3O4. The results also indicate that the activity of Co3O4 for oxidation of toluene depends on the quantity and nucleophilicity of surface oxygen species, which could be increased by the irregular surface morphology and the introduction of sodium.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Catalytic performance for toluene abatement over Al-rich Beta zeolite
           supported manganese oxides
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yuexin Peng, Ling Zhang, Long Chen, Dingzhong Yuan, Guoxiong Wang, Xiangju Meng, Feng-Shou Xiao
      Catalytic combustion of toluene has been widely investigated due to importance of abatement of volatile organic compounds (VOCs), and in this work we have successfully prepared highly efficient heterogeneous catalysts for toluene combustion by impregnation of manganese oxides with Al-rich Beta zeolites (Beta-SDS) with H-form (MnOx/H-Beta-SDS) and K-form (MnOx/K-Beta-SDS) as well as pure siliceous Beta zeolite (MnOx/Si-Beta). Catalytic tests show that these zeolite-supported catalysts have higher activities than alumina-supported manganese oxides (MnOx/Al2O3). By comprehensive consideration of reducibility, adsorbed oxygen species, and lattice oxygen species in the catalysts, it is shown that the adsorbed oxygen species play more important roles than others for the catalytic activity. The good catalytic performance and understanding of active sites over the MnOx/H-Beta-SDS might be helpful for preparation of catalysts in VOCs abatement.
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      PubDate: 2017-11-02T03:11:31Z
       
  • A template-free method for preparation of MnO2 catalysts with high surface
           areas
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yonghui Wei, Lei Ni, Minxia Li, Jili Zhao
      High surface-area manganese oxides catalysts are widely employed in catalytic oxidation of volatile organic compounds (VOCs) because of their high efficiency and good stability. However, template agents are usually introduced to the synthesis process to create the high surface area (>150m2/g). It is quite expensive and complicated, restricting the widespread applications. Herein, a template-free method was reported here to prepare high surface-area MnO2 catalysts by selectively removing La elements from LaMnO3 perovskites using acid treatment. The obtained MnO2 catalysts possessed excellent catalytic activity in toluene oxidation. Besides, the reserved La elements after acid treatment could be recycled to repeat the preparation process. After three cyclic processes, the catalytic performances were improved gradually, which may provide the possibility for the practical application in VOCs elimination.
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      PubDate: 2017-11-02T03:11:31Z
       
  • “Storage-oxidation” cycling process for indoor benzene removal
           at room temperature
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yidi Wang, Bingbing Chen, Bo Wu, Limei Yu, Xiaobing Zhu, Chuan Shi
      Non-thermal air plasma assisted “storage-oxidation” cycling process was applied to indoor benzene removal at room temperature and realized over TS-1 zeolite supported AgCu catalysts. AgCu/TS-1 catalyst showed not only promising C6H6 capacity under humid condition in the storage phase, but also high oxidation efficiency of absorbed benzene with the assistance of non-thermal plasma (NTP) at a moderate discharge power of 6W. Due to the generation of increased amounts of Cu+ and active surface oxygen species resulting from the Ag–Cu interaction, the AgCu/TS-1 catalyst showed higher benzene storage and oxidation capacity than the other catalysts. Compared with the thermal regeneration, the good humidity tolerance, non-benzene release, and low energy cost was achieved in the non-thermal air plasma regeneration, which providing a promising way for indoor benzene purification.
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      PubDate: 2017-11-02T03:11:31Z
       
  • Selective catalytic combustion of hydrogen cyanide over metal modified
           zeolite catalysts: From experiment to theory
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Ning Liu, Xiaoning Yuan, Biaohua Chen, Yingxia Li, Runduo Zhang
      A series of metal modified zeolite including Cu-(Beta, FER, MCM-22, MCM-49, MOR) and M-(M=Cu, Co, Fe, Mn, Ni)-ZSM-5 was prepared by impregnation method and characterized by BET, XRD, and H2-TPR. HCN-SCC (selective catalytic combustion) activity measurement results suggest that Cu-ZSM-5 exhibiting excellent HCN conversion activity (T90 =350°C) and N2 yield (>95% at T>350°C) constitutes one kind of promising candidate for HCN catalytic abatement. The HCN-SCC mechanism was further investigated by density functional theory (DFT) over constructed 20T-Cu-ZSM-5 models, which suggests that: (i) the 20T-Cu-ZSM-5 containing double active [Cu]+ site was much more favorable than that of 20T-Cu-ZSM-5 with single active [Cu]+ site during NCO generation step, being mainly related to the cooperation effect of double active [Cu]+ site; (ii) NCO+NO→N2 +CO2 was confirmed to the one kind of probable reaction pathway for N2 and CO2 generations, wherein the NO could be produced through oxidation of NCO; (iii) the DFT energy calculation results as well as the microkinetic analyses suggested that the NCO formation step possessing the highest energy barrier (10.4kcalmol−1) was proposed to be the rate determining step of the whole catalytic cycle.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Effects of atmosphere pretreatment on the catalytic performance of
           Pd/γ-Al2O3 catalyst in benzene degradation II: Crystal structure
           transformation of Pd active species
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Ji Liu, Yu Chen, Huamei Wang, Mingde Yang, Yulong Wu, Zhen Chen
      The effects of pretreatment under reducing (H2), inert (N2 and He), and oxidative (air) atmospheres on the catalytic performance of Pd/γ-Al2O3 in benzene degradation were investigated in this study. The crystal structure transformation of Pd active species, which is a significant influencing factor on the catalytic activity of Pd/γ-Al2O3, was investigated in depth via X-ray diffraction combined with in situ Raman analysis. Results showed that the temperature-induced destruction of the near-surface PdO crystal lattice occurs at or above 553K in inert pretreatment, and this process is reversible when the temperature decreased immediately. The destruction of the PdO crystal lattice largely relied on the increase in treatment time, resulting in the structural transformation from the well-defined crystalline PdO to the amorphous state. The temperature-induced destruction of the near-surface PdO crystal lattice was also observed in oxidative atmosphere with no connection with the increase in treatment time. The catalytic performance of Pd/γ-Al2O3 on benzene degradation is enhanced significantly as a result of the structural transformation from the well-defined crystalline PdO to the amorphous state via pretreatment with inert atmosphere. A possible mechanism for the structural transformation process and its relationship with the catalytic activity is proposed.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Co3O4/HZSM-5 catalysts for methane combustion: The effect of preparation
           methodologies
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Xinxiang Cao, Rui Zhou, Ning Rui, Zongyuan Wang, Jiajun Wang, Xintong Zhou, Chang-jun Liu
      A series of Co3O4/HZSM-5 catalysts with different Co3O4 loadings were prepared by incipient wetness impregnation followed by thermal calcination or dielectric barrier discharge (DBD) plasma decomposition. Their catalytic performances for the complete combustion of methane were evaluated from 300 to 700°C. The plasma decomposed samples exhibit much higher catalytic activity than the calcined ones. Among all the samples tested, the plasma decomposed catalyst with 20wt.% loading of Co3O4 possesses the highest catalytic activity with T10 (10% CH4 conversion) at 300°C and T100 (complete conversion) at 550°C. The excellent catalytic activity of the DBD plasma decomposed samples would attribute to well-dispersed Co3O4, enhanced low-temperature reducibility, high content of lattice oxygen and adsorbed oxygen species, as well as the low formation tendency of the intermediate of Co-formate.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Effective photodegradation of dyes using in-situ N-Ti3+ co-doped porous
           titanate-TiO2 rod-like heterojunctions
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Minh-Tri Nguyen-Le, Byeong-Kyu Lee
      In this study, a simple sol-gel approach was applied to fabricate novel N-Ti3+ co-doped porous titanate-TiO2 rod-like heterostructures with both enhanced adsorption ability and visible light photocatalytic activity. We also investigated the effect of calcination temperature on the physical properties and visible light photocatalytic activity of the heterostructures. When calcined at high temperature (>400°C), the rod-like heterostructures became thermally less stable due to the structural conversion of the visible-light-active composite (Na2Ti3O7–anatase rod-like heterostructures) into the visible-light-inactive form (Na2Ti3O7 − Na2Ti6O13 heterostructures). High mesoporosity, low recombination rate of electrons and holes, and effective incorporation of nitrogen dopants and Ti3+ defects were the main features of the enhanced photocatalytic activity of the rod-like heterostructures in the degradation of 10mg/L methylene blue (MB) under visible light. O2 − was the dominated radical for MB photodegradation.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Cu2O NPs/Bi2O2CO3 flower-like complex photocatalysts with enhanced visible
           light photocatalytic degradation of organic pollutants
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Shuanglong Lin, Wenquan Cui, Xingang Li, Hong Sui, Zisheng Zhang
      A facile and feasible interfacial self-assembly approach was developed to synthesize flower-like Cu2O/Bi2O2CO3 micro-composites. Degradation of methylene blue (MB) was used to evaluate the photocatalytic activity of composite under visible light. When compared to Bi2O2CO3, the flower-like Cu2O/Bi2O2CO3 micro-composites show higher photocatalytic activity. Additionally, our results indicate that the photocatalytic activity of Cu2O/Bi2O2CO3 composites is dependent on Cu2O loading. The highest photocatalytic performance of Cu2O/Bi2O2CO3 micro-composites is 94% after irradiation for 20min, which is 3–5 times that of pure Cu2O (calculated based on the equivalent Cu2O content in Cu2O/Bi2O2CO3) and pure Bi2O2CO3 respectively. Photocatalytic mechanism for the degradation of MB over Cu2O/Bi2O2CO3 was proposed based on the above. Our results provide an invaluable methodology for designing high visible-responsive photocatalysts based on Cu2O/bismuth and related functional materials, which is promising for semiconductor composites and new energy applications.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Facile synthesis of deep eutectic solvent assisted BiOCl/BiVO4@AgNWs
           plasmonic photocatalysts under visible light enhanced catalytic
           performance
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Dhayanantha Prabu Jaihindh, Yen-Pei Fu
      Noble metals are very well known for their surface plasmon resonance property that facilitate of better light absorption in the visible region particularly for gold and silver. Nevertheless, unlike semiconductors, noble metals are commonly considered lacking the ability to accelerate reactions by way of photogenerated electron-hole pairs due to their continuous energy band structure. Here, we report a one dimensional (1D) AgNWs combined with BiOCl/BiVO4 photocatalysts have been synthesized at room temperature. BiOCl/BiVO4 photocatalysts have been synthesized in the presence of deep eutectic solvents (DESs), also known as deep eutectic ionic liquids (DEILs).The synthesized product was characterized using various techniques. Surface morphology was analyzed using SEM and TEM, which shows a sheet like shaped structure from sol–gel method. The structural, optical properties were investigated by X-ray diffraction (XRD), UV–vis spectrophotometer, and Photoluminescence (PL) spectroscopy measurements. The BiOCl/BiVO4@AgNWs shows a better degradation of methylene blue (MB) and rhodamine B (RhB) than pure BiVO4 illuminated under a Xe arc lamp with 35W and color temperature of 6000K. Also, the significant enhancement of visible-light-driven photocatalytic activity should be ascribed to the formation of the BiOCl/BiVO4 heterojunction, which can result in the high separation and transfer efficiency of photogenerated charge carriers. It was verified by electrochemical impedance spectra (EIS) and linear sweep voltammetry (LSV).
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Facile fabrication of heterostructured bismuth titanate nanocomposites:
           The effects of composition and band gap structure on the photocatalytic
           activity performance
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yue Du, Qiang Hao, Daimei Chen, Tong Chen, Simeng Hao, Jinjin Yang, Hao Ding, Wenqing Yao, Jianhua Song
      Heterostructured Bi2Ti2O7/Bi4Ti3O12 nanocomposites were successfully synthesized through a facile calcination method. The composition and band gap of the Bi2Ti2O7/Bi4Ti3O12 nanocomposites were controlled by tuning the calcination temperature. The morphology of the Bi2Ti2O7/Bi4Ti3O12 composite changed from worm-like nanosheets to spherical particles when the calcination temperature increased from 500 to 800°C. The structural features of the heterojunction were confirmed using characterization techniques such as XRD, SEM, HRTEM, ESR, and SPV. The Bi2Ti2O7/Bi4Ti3O12 nanocomposite calcined at 600°C had the highest visible light photocatalytic activity, which was almost 2.0 times as high as that of the pure Bi2Ti2O7 for Rhodamine B (RhB) photodegradation, and 2.5 times the rate of 2,4–dichlorophenol (2,4–DCP) removal under simulated sunlight irradiation. The enhanced photocatalytic activity is due to the heterojunction interfaces induced by the match of lattice and energy levels between Bi2Ti2O7 and Bi4Ti3O12, which is helpful for the separation and transfer of electron-hole pairs. The photocatalytic mechanism was elucidated via active species trapping experiments and electron spin resonance. The photogenerated holes played a key role in the degradation reaction via the Bi2Ti2O7/Bi4Ti3O12 composites. Finally, a possible charge transfer mechanism for the enhanced photocatalytic activity was proposed.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Three-dimensional titanate–Graphene oxide composite gel with enhanced
           photocatalytic activity synthesized from nanofiber networks
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Ruirui Liu, Xiuyan Li, Shichao Li, Guowei Zhou
      We report the synthesis of a novel three-dimensional titanate–graphene oxide (TiGO) composite gel with controllable morphology through a facile one-pot solvothermal approach. This technique directly utilizes tetra-butyl titanate as a titanium source and acetic acid (HAc) as a stabilizer and cross-linking agent. Gel formation at the macro level and morphological evolution of flower-like networks into nanofibers at the micro level were controlled by regulating the amounts of graphene oxide (GO) and HAc added to the reaction system. TiGO composite is composed of nanofiber bundles and its photocatalytic activity was evaluated by photocatalytic decolorization of methyl orange aqueous solution under UV irradiation. The improved photocatalytic performance was attributed mainly to synergistic effects of titanate and GO.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Wüstite-based catalyst for ammonia synthesis: Structure, property and
           performance
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Huazhang Liu, Wenfeng Han
      Fused iron catalyst is an active and classical catalyst both for ammonia synthesis and Fischer-Tropsch synthesis which are two typical industrial processes. As it is of significance to catalysis science as well as its importance to industry, fused iron catalyst is an ideal model system for heterogeneous catalysis research. However, the precursors of fused iron catalysts were confined to Fe3O4 in the most studies. The discovery of wüstite (Fe1-xO) based catalyst is a key innovation for fused iron catalyst which necessitates the further research to obtain deeper insight into this novel catalyst. This paper summarized three major scientific issues involved in the development of wüstite based catalyst, namely, the physicochemical properties, characteristics of wüstite, as well as the mechanism leading to the high activity. Based on this novel catalyst, new concepts and opinions were proposed, and the insights and principles obtained are as follow. Hump like activity trend of reduced catalyst was first obtained with varying of Fe2+/Fe3+ in the catalyst precursor. Molecular ratio of iron oxides, single phase theory and structure of active sites were suggested to elucidate the high activity of wüstite based catalyst. In addition, new concepts and opinions such as the disproportionation of metastable wüstite and its inhibition, matching of promoters with the structural characteristics of wüstite, synergy between acidic site and basic site on the surface of catalyst, role of Al2O3 in the re-structuring of catalyst surface, mechanism of competitive reduction, strong H2 adsorption, active sites, micro-structure of α-Fe and the essence of high activity were proposed to bring light to the structure-activity relationship forming the theory system with single phase theory as the kernel of wüstite catalyst. These regularities and the theory system significantly promoted and enriched the scientific knowledge of fused iron catalyst. It is unexpected that a knowledge based improvement of a catalyst would have a strong effect on other fields of catalysis research.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Pd/C-catalyzed synthesis of N-aryl and N-alkyl isoquinolones via CH/NH
           activation
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Zhen Shu, Yuntao Guo, Wei Li, Baiquan Wang
      Pd/C-catalyzed direct synthesis of N-aryl and N-alkyl isoquinolones was developed via the annulation reactions of benzamides and alkynes in high yields (up to 99%) through the cleavage of CH/NH bonds. The reaction was ligand-free and air was used as oxidant. High regioselectivities were found when unsymmetrical alkynes or meta-benzamides were used as substrates. The heterocyclic carboxamide substrates, such as furan and thiophene derivatives, also afforded the corresponding products in high yields.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Loading Ni/La2O3 on SiO2 for CO methanation from syngas
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Shuangshuang Li, Honggui Tang, Dandan Gong, Zhi Ma, Yuan Liu
      The critical problem for CO methanation catalysts to produce synthetic natural gas is deactivation due to carbon deposition and/or sintering of the active components. It was reported that Ni/La2O3 has better resistance to sintering and can eliminate the carbon deposited via lanthanum containing compound. However, the lanthanum oxide has low surface area, mechanical strength and stability. To overcome this problem, a new scheme has been proposed in this study by supporting the perovskite-type oxide of LaNiO3 on SiO2. Nickel and lanthanum ions are evenly dispersed at atomic level in the nanocrystallites of LaNiO3, after reduction highly dispersed small Ni nanoparticles were supported on La2O3 which spread on SiO2. Thus, Ni/La2O3 was loaded on SiO2. The catalysts were characterized by means of BET, XRD, HRTEM+EDX, H2 chemisorption, ICP, and TGA techniques, and their catalytic performances were measured for CO methanation from syngas to generate CH4. The prepared catalyst derived from LaNiO3/SiO2 showed very good catalytic performance, especially showed very high resistance towards carbon deposition and nickel sintering. The NiO-La2O3/SiO2 prepared by common incipient-wetness impregnation method was investigated for comparison. This method can be extended for loading other catalysts, for that a lot of metallic ions can be acted as the ions of perovskite-type oxides.

      PubDate: 2017-11-02T03:11:31Z
       
  • Effect of chlorine on performance of Pd catalysts prepared via colloidal
           immobilization
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Yingnan Zhao, Wanwei Liang, Yongdan Li, Leon Lefferts
      This contribution shows the effect of residual chlorine on the catalytic performance of a Pd-based catalyst in the hydrogenation of nitrite for cleaning of drinking water. The catalyst was prepared via immobilization a colloidal Pd nanoparticles using activated carbon as support. Different amount of hydrochloric acid (HCl) was added to immobilize the Pd colloid on the carbon support, facilitating the removal of the residual stabilizer, polyvinyl alcohol (PVA), from the surface of the Pd nanoparticles (NPs). The catalysts were characterized by TEM, CO-chemisorption, XRF, N2 physisorption, UV–vis spectroscopy, and XPS. The activity and selectivity of the catalysts were measured for nitrite hydrogenation in semi-batch operation. The results show that PVA can be removed completely at pH below 2. The residual chlorine on the catalysts can be removed by reduction in H2/N2 at a mild temperature, i.e. 200°C, regardless the amount of HCl used. Nevertheless, high concentration of HCl during immobilization (pH 1) causes partial Pd re-dissolution according to UV–vis spectroscopy, resulting in formation of highly dispersed Pd clusters that could not be detected with TEM. Reduction of this catalyst with high chlorine content in H2 at 200°C is resulting in formation of relatively large Pd particles via sintering. Without pre-reduction at 200°C, residual chlorine can also be removed almost completely during the hydrogenation reaction at room temperature. The activity of the Pd catalyst is insensitive to the chlorine concentration below 30μmolL−1 in the aqueous reaction mixture. Interestingly, the selectivity to N2 is improved by adding chlorine to the reaction mixture, independent of the way chlorine is added, i.e. via the catalyst or added directly to the reaction solution.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Synthesis of titanium containing MCM-41 from industrial hexafluorosilicic
           acid as epoxidation catalyst
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Tieliang Liu, Fang Jin, Xianqiao Wang, Yangchun Fan, Ming Yuan
      The industrial by-product hexafluorosilicic acid was investigated as silicate source for titanium containing MCM-41 (Si/Ti–MCM-41) synthesis. An extended and detailed study, which includes the effects of several factors such as the state and content of Ti, surfactant/Si ratio and template removal technique on the physicochemical properties and catalytic activity of Si/Ti–MCM-41, is presented; The Si/Ti–MCM-41 was also characterized by powder X-ray diffraction, N2 adsorption-desorption, fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometer, thermal gravimetric measurements, X-ray fluorescence and scanning electron microscopy. The results show that the specific surface area and pore volume of the molecular sieve reach 1040m2 g−1 and 0.74cm3 g−1 under the hydrothermal conditions of the Si/Ti mole ratio equal to 60, CTAB/Si mole ratio to 0.81, hydrothermal temperature at 343K and time for 3h. The catalytic performance shows that samples have higher activity and selectivity for cyclohexene epoxidation to produce cyclohexene oxide. With the reaction temperature 333K and mole ratio of cyclohexene/tertiary butyl peroxide hydrogen equal to 1, the highest cyclohexene conversion and epoxide selectivity is 79.23% and 95%, respectively. The catalyst activity has not obvious change with two times recycles.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Catalytic wastewater treatment: Oxidation and reduction processes. Recent
           studies on chlorophenols
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Claude Descorme
      Although the water resource is not exhaustible, the water quality must be preserved. It does represent a major challenge for the coming decades. Since water is used for many different industrial, agricultural and domestic applications, a wide variety of waste effluents is being produced. Since conventional wastewater treatment plants, mainly based on biological processes, are poorly efficient for the treatment of toxic and/or non-biodegradable and/or highly concentrated effluents, new solutions are being looked for. Many different approaches have been investigated and catalytic processes may play a crucial role. Both oxidation and reduction processes for the treatment of chlorophenols have been reviewed. The principle of each of those processes is being described, the key parameters are identified and subsequently the major challenges to be overcome both in terms of material science and/or catalytic efficiency (activity and selectivity) are highlighted to offer a general but homogenized overview of the state-of-the-art in the different fields. Finally, the most recent developments in each field are shortly discussed.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Hollow zeolite-encapsulated Fe-Cu bimetallic catalysts for phenol
           degradation
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Chengyi Dai, Anfeng Zhang, Lei Luo, Xinbao Zhang, Min Liu, Junhu Wang, Xinwen Guo, Chunshan Song
      Highly dispersed Fe-Cu bimetallic oxide nanoparticles were successfully encapsulated in hollow Silicalite-1 single crystals (Fe2O3 CuO@Hol S-1) by tetrapropylammonium hydroxide (TPAOH) hydrothermal treatment with an “impregnation-dissolution-recrystallization” process. Due to the Fe-Cu bimetallic interaction compared with single iron oxide, Fe-Cu bimetallic oxide exhibits a higher dispersion with the particle size decreasing from ∼11.3nm to ∼3.7nm. For aqueous phenol degradation, the Fe2O3 CuO@Hol S-1 catalyst exhibits high activity attributed to the enhanced transport of reactants/products in the short microporous channels (20nm) and the small metal oxide particle size. Interestingly, the particle size of encapsulated Fe2O3 CuO (3.7nm) is larger than that of zeolite micropore (0.53nm), which helps preventing the leaching of metal oxide that is a significant problem for conventional supported Fe catalyst in this reaction.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
  • Simultaneous hydrodenitrogenation and hydrodesulfurization on unsupported
           Ni-Mo-W sulfides
    • Abstract: Publication date: 15 November 2017
      Source:Catalysis Today, Volume 297
      Author(s): Sylvia Albersberger, Jennifer Hein, Moritz W. Schreiber, Santiago Guerra, Jinyi Han, Oliver Y. Gutiérrez, Johannes A. Lercher
      The catalytic properties of unsupported Ni-Mo-W sulfides (composites of Ni-Mo(W)S2 mixed sulfides and Ni3S2) obtained from precursors synthesized via co-precipitation, hydrothermal, and thiosalt decomposition were explored for hydrodenitrogenation (HDN) of o-propylaniline or quinoline in presence and absence of dibenzothiophene undergoing hydrodesulfurization (HDS). The conversion rates varied with the reacting substrate and were related to specific catalyst properties such as morphology, texture, surface and composition. For the HDN of o-propylaniline and the HDS of dibenzothiophene in presence of o-propylaniline, high concentrations of coordinatively unsaturated cationic sites (as characterized by NO adsorption) and the specific surface areas determined the rates of reaction. For the HDN of quinoline and the HDS of dibenzothiophene in the presence of quinoline, the high hydrogenation activity of tungsten sulfide and length of the slabs was found to be more important than in the cases with o-propylaniline. Overall, the activity of unsupported catalysts relates to the size of sulfide slabs provided that Ni is present at the perimeter of the slabs.
      Graphical abstract image

      PubDate: 2017-11-02T03:11:31Z
       
 
 
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