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ENGINEERING (1208 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
3D Research     Hybrid Journal   (Followers: 19)
AAPG Bulletin     Hybrid Journal   (Followers: 6)
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Adsorption     Hybrid Journal   (Followers: 4)
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Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 1)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 4)
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Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access  
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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)
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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: 9)
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at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
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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: 4)
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Bautechnik     Hybrid Journal   (Followers: 1)
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Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
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Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Biofuels Engineering     Open Access  
Biointerphases     Open Access   (Followers: 1)
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Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
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Biomedizinische Technik - Biomedical Engineering     Hybrid Journal  
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Biotechnology Progress     Hybrid Journal   (Followers: 39)
Boletin Cientifico Tecnico INIMET     Open Access  
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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)
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Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers, Droit, Sciences et Technologies     Open Access  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 14)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 41)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 8)
Case Studies in Thermal Engineering     Open Access   (Followers: 3)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 6)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 5)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 6)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 14)
City, Culture and Society     Hybrid Journal   (Followers: 21)
Clay Minerals     Full-text available via subscription   (Followers: 9)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
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Coastal Engineering Journal     Hybrid Journal   (Followers: 5)
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Color Research & Application     Hybrid Journal   (Followers: 1)
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Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 13)
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        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  [3042 journals]
  • Influence of acid-base properties of the support on the catalytic
           performances of Pt-based catalysts in a gas-phase hydrogenation of
    • Authors: F. Saad; J.D. Comparot; R. Brahmi; M. Bensitel; L. Pirault-Roy
      Pages: 1 - 9
      Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): F. Saad, J.D. Comparot, R. Brahmi, M. Bensitel, L. Pirault-Roy
      Catalytic performances of Pt-based catalysts supported on various oxides (Al2O3, MgO, SiO2, and CeO2) prepared by a sol-gel method were evaluated by gas-phase hydrogenation of acetonitrile, in order to investigate the influence of acid-base properties of support oxides on products distribution. Acid-base properties were studied by pyridine adsorption followed by FTIR (Lewis and Brønsted acidity), 3,3-dimethyl-1-butene isomerization (Brønsted acidity), and temperature-programmed desorption (TPD) of CO2 (basicity). The results obtained concerning acid-base characterization of the oxides in this paper show a reasonable scale of surface acidity and basicity, as MgO and CeO2 are known to be basic oxides, silica is expected to be a neutral support according the preparation procedure, whereas alumina is an amphoteric one. The performances of the four tested catalysts in terms of the selectivity towards the primary amine are correlated with the amount of basic sites. The more basic the support is, the more it favors the production of primary amines.
      Graphical abstract image

      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.038
      Issue No: Vol. 544 (2017)
  • New insights in evaluation of acid sites in micro-mesoporous zeolite-like
           materials using potentiometric titration method
    • Authors: Nataliya D. Shcherban; Svitlana M. Filonenko; Roman Yu. Barakov; Sergii A. Sergiienko; Kai Yu; Ivo Heinmaa; Ari Ivaska; Dmitry Yu. Murzin
      Pages: 34 - 42
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Nataliya D. Shcherban, Svitlana M. Filonenko, Roman Yu. Barakov, Sergii A. Sergiienko, Kai Yu, Ivo Heinmaa, Ari Ivaska, Dmitry Yu. Murzin
      Potentiometric titration was used to characterize the acid-base properties of micro-mesoporous zeolite-like materials obtained via dual template synthesis using sol-precursors of Beta zeolite and micellar templates. The obtained results were compared with other methods of acidity determination (ammonia TPD, pyridine ad(de)sorption). The acid sites with the strength comparable to Beta zeolite (lg K values 4.3–4.7) were found in low-crystalline and X-ray amorphous micro-mesoporous materials. The strongest acid sites were observed in conventional Beta zeolite and a low-crystalline (degree of crystallinity ca. 0.1) micro-mesoporous material prepared on its basis (lg K 4.3) in concentration of 450 and 100μmol/g, respectively. A change from acidic to alkaline reaction media in the second stage of micro-mesoporous materials preparation led to an increase of the acid sites concentration from 190 to 600μmol/g concomitant with formation of a high fraction of comparatively strong acid sites (lg K 4.7, 200μmol/g). A high content of acid sites in low-crystalline and X-ray amorphous samples was assigned to acidity of zeolite precursors rather than zeolite crystals.
      Graphical abstract image

      PubDate: 2017-06-21T17:06:01Z
      DOI: 10.1016/j.apcata.2017.05.039
      Issue No: Vol. 543 (2017)
  • Enhancement of palladium-catalyzed direct desulfurization by yttrium
    • Authors: Ali Mansouri; Natalia Semagina
      Pages: 43 - 50
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Ali Mansouri, Natalia Semagina
      Bimetallic Pd-Y nanoparticles were synthesized by yttrium precursor reduction on the surface of colloidal Pd seeds catalyzed by palladium hydride. The addition of yttrium improved the thermal stability of the Pd nanoparticles to agglomeration. The nanoparticles before and/or after deposition on alumina were characterized by TEM, XPS, STEM with elemental mapping, temperature-programmed reduction, CO chemisorption and CO-DRIFT spectroscopy. The supported catalysts were evaluated in hydrodesulfurization (HDS) of 4,6-dimethydibenzothiophene at 350°C and 1MPa. Yttrium addition did not alter the overall HDS rate but increased the direct desulfurization selectivity from 71% to 84% and suppressed cracking twice as much as monometallic Pd catalyst did. The study demonstrates that PdY structures could be a promising candidate for low-pressure HDS of refractory sulfur compounds.
      Graphical abstract image

      PubDate: 2017-06-21T17:06:01Z
      DOI: 10.1016/j.apcata.2017.06.016
      Issue No: Vol. 543 (2017)
  • Promotion on light olefins production through modulating the reaction
           pathways for n-pentane catalytic cracking over ZSM-5 based catalysts
    • Authors: Xu Hou; Yuan Qiu; Enxian Yuan; Fuqiang Li; Zaizheng Li; Shuang Ji; Zhenning Yang; Guozhu Liu; Xiangwen Zhang
      Pages: 51 - 60
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Xu Hou, Yuan Qiu, Enxian Yuan, Fuqiang Li, Zaizheng Li, Shuang Ji, Zhenning Yang, Guozhu Liu, Xiangwen Zhang
      Insights into reaction mechanism were vital to direct naphtha catalytic cracking process to produce light olefins. In order to reveal influences of reaction pathways modulation on light olefins production, Zr-ZSM-5, Ag-ZSM-5, and the regenerated HZSM-5 (ZSM-5(R2)) were prepared and employed in n-pentane catalytic cracking. It was found that light olefins yield obtained over Zr-ZSM-5, Ag-ZSM-5, and ZSM-5(R2) at 500°C was 58%, 81%, and 113% higher than that over the parent HZSM-5 (12.0%), respectively. Promotion on light olefins production caused by Zr-incorporation can be attributed to the enhancement of hydride transfer reactions increasing the utilization of Brønsted acid sites and the catalytic activity accompanied with the proximate stability compared to the parent HZSM-5. Different from Zr-ZSM-5, Ag-ZSM-5 and ZSM-5(R2) respectively introduced dehydrogenation cracking and redox cracking to n-pentane catalytic cracking, which selectively promoted the formation of light olefins and significantly enhanced n-pentane protolytic cracking. However, both Ag-ZSM-5 and ZSM-5(R2) went through a rapid deactivation at 550°C, which was probably due the selective enhancement of alkenes accelerating the side reactions to coke formation.
      Graphical abstract image

      PubDate: 2017-06-21T17:06:01Z
      DOI: 10.1016/j.apcata.2017.06.013
      Issue No: Vol. 543 (2017)
  • Highly efficient single atom cobalt catalyst for selective oxidation of
    • Authors: Min Li; Shujie Wu; Xiaoyuan Yang; Jing Hu; Ling Peng; Lu Bai; Qisheng Huo; Jingqi Guan
      Pages: 61 - 66
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Min Li, Shujie Wu, Xiaoyuan Yang, Jing Hu, Ling Peng, Lu Bai, Qisheng Huo, Jingqi Guan
      Catalysts with atomically dispersed active sites are highly desirable to maximize atom efficiency. Herein, we reported atomically cobalt dispersed onto nitrogen-doped graphene (denoted as Co-NG) by heat-treating cobalt salts and graphene oxide in ammonia atmosphere. The Co-NG catalyst was characterized by various analysis techniques, such as XPS, XRD, Raman, TEM, SEM, HAADF-STEM and nitrogen adsorption. Characterization results showed that the surface O content decreased as the doping temperature increased, while the surface N content kept increasing up to 7.94 at% at the doping temperature of 750°C. The coordination of N with Co should improve the catalytic behavior of Co-NG. The Co-NG catalyst has extremely high atom efficiency and shows high activity and excellent stability for the selective oxidation of various alcohols (e.g. benzyl alcohol, 4-chloro-benzyl alcohol, 4-methyl-benzyl alcohol, 4-methoxy-benzyl alcohol, 4-hydroxy-benzyl alcohol, phenethyl alcohol, 2-methyl heptanol, etc) by oxygen molecule. For example, 94.8% benzyl alcohol conversion and 97.5% benzaldehyde selectivity can be achieved over Co-NG after reaction for 5h, and the catalyst yields an average TOF of over 500h−1.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.018
      Issue No: Vol. 543 (2017)
  • Improving 1,3-butadiene yield by Cs promotion in ethanol conversion
    • Authors: Pratap T. Patil; Dapeng Liu; Yan Liu; Jie Chang; Armando Borgna
      Pages: 67 - 74
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Pratap T. Patil, Dapeng Liu, Yan Liu, Jie Chang, Armando Borgna
      Gas phase conversion of ethanol into butadiene was studied over silica-supported ZnO, ZrO2 and ZnO-ZrO2 catalysts in a fixed-bed reactor. Surface active sites were characterised using a variety of techniques including temperature-programmed desorption (TPD) of NH3 and CO2 as well as Fourier transform infrared (FTIR) spectroscopy of adsorbed pyridine. An increased concentration of acid and base sites was found in the following order: ZnO<ZrO2 <ZnO-ZrO2. In addition, new acid and base sites were generated when alkaline metal promoters were introduced. Typical reaction products for all catalysts include acetaldehyde, butadiene, ethylene, propylene, butenes, diethyl ether and C4 oxygenates. Compared to single oxide supported catalysts, a remarkable acid-base synergetic effect was observed on the binary oxides supported catalysts with or without alkali metal modification. The improved catalytic activity and selectivity can be attributed to the right balance between acid and base sites, minimising dehydration to ethylene while promoting dehydrogenation to acetaldehyde. Furthermore, the existence of acid-base pairs with the appropriate configuration and strength promotes the aldol condensation and Meerwein-Ponndorf-Verley (MPV) reduction efficiently.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.05.025
      Issue No: Vol. 543 (2017)
  • Effects of Mn addition on dehydrogenation of methylcyclohexane over
           Pt/Al2O3 catalyst
    • Authors: Atsushi Nakano; Shota Manabe; Takuma Higo; Hirofumi Seki; Satoshi Nagatake; Tomohiro Yabe; Shuhei Ogo; Tomomi Nagatsuka; Yukihiro Sugiura; Hideshi Iki; Yasushi Sekine
      Pages: 75 - 81
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Atsushi Nakano, Shota Manabe, Takuma Higo, Hirofumi Seki, Satoshi Nagatake, Tomohiro Yabe, Shuhei Ogo, Tomomi Nagatsuka, Yukihiro Sugiura, Hideshi Iki, Yasushi Sekine
      Methylcyclohexane (MCH) is a prospective hydrogen carrier candidate. Although Pt/Al2O3 catalyst shows high conversion for dehydrogenation of MCH at 623K, methane formation and deactivation caused by coke deposition are issues over the catalyst. Results of this study demonstrate that Mn addition to Pt/Al2O3 brought higher selectivity and stability for dehydrogenation of MCH than with Pt/Al2O3 alone. Although Pt and Mn do not form an alloy structure, Pt and Mn form an adjacent structure, and the unsaturated coordination of Pt which promotes methane formation and deactivation decreased. Pt-Mn/Al2O3 shows high catalytic performance by virtue of the coverage of such sites by MnOx.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.017
      Issue No: Vol. 543 (2017)
  • Applications of light olefin oligomerization to the production of fuels
           and chemicals
    • Authors: Christopher P. Nicholas
      Pages: 82 - 97
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Christopher P. Nicholas
      The oligomerization of the light olefins ethene, propene, and butenes into fuels and chemicals has been investigated and commercially practiced for many years. While the area appears on the surface to be mature, many advances have been made in recent years. In this feature article, I discuss the mechanisms of reaction and showcase catalysts and processes useful for oligomerization from both the open and patent literature. Commercially practiced processes are spotlighted. Among the catalysts utilized in the art are acidic catalysts such as solid phosphoric acid and zeolites, as well as metal based catalysts including aluminum alkyls, and nickel and zirconium based complexes and solids. A short section on catalysts and processes which utilize a metallacycle mechanism in order to achieve high selectivity to 1-hexene or 1-octene is followed by a discussion of multi-functional materials possessing both acid and metal active sites. Finally, processes where oligomerization is a key step in a multi-step or multi-reaction process are discussed.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.011
      Issue No: Vol. 543 (2017)
  • RWGS reaction employing Ni/Mg(Al,Ni)O − The role of the O vacancies
    • Authors: Michelly T. Rodrigues; Priscila C. Zonetti; Odivaldo C. Alves; Eduardo F. Soua-Aguiar; Luizs P. Borges; Lucia E.G. Appel
      Pages: 98 - 103
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Michelly T. Rodrigues, Priscila C. Zonetti, Odivaldo C. Alves, Eduardo F. Soua-Aguiar, Luizs P. Borges, Lucia E.G. Appel
      The performance of Ni supported on Mg(Al)O catalysts was evaluated in the RWGS reaction. The catalysts were characterized by TPR, EPR, TPSR, XRD, XPS, cyclohexane dehydrogenation reaction, atomic absorption and N2 physisorption. Two different catalytic systems were prepared by impregnation using water or ethanol as solvents of the Ni precursor. When ethanol was employed, Ni diffuses into the Mg(Al)O particles generating a homogeneous distribution of this metal through the catalyst particle leading to a Mg(Al,Ni)O solid solution, a very small amount of Nio and NiAl2O4. On the other hand, hydrotalcite is generated on the external layers of Mg(Al)O when water is the solvent. Nickel is trapped in the hydrotalcite structure. After calcination and reduction its concentration on the catalyst surface is higher than the one in the bulk. Both Mg(Al,Ni)O and Nio are observed on the catalyst surface. Oxygen vacancies were also observed for the two catalysts via EPR analyses due to the replacement of Mg by Al in the MgO lattice. The Mg(Al,Ni)O vacancies are active species for the reduction of CO2 to CO. These species and Nio are the catalytic sites of the RWGS reaction. Increasing the Nio concentration on the catalysts surface the activity of the catalysts increases as well. As far as we are concerned, this is the first time that Mg(Al)O or Mg(Al,Ni)O vacancies are associated with the performance of a catalytic system. This work exhibits that Ni/Mg(Al,Ni)O is a promising catalytic system for the RWGS reaction.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.026
      Issue No: Vol. 543 (2017)
  • Dicationic ionic liquids/heteropoly acid composites as heterogeneous
           catalysts for cyclohexene oxidation with molecular oxygen under
           solvent-free condition: Insights from theory and experiments
    • Authors: Fahime Nezampour; Mehran Ghiaci; Hossein Farrokhpour
      Pages: 104 - 114
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Fahime Nezampour, Mehran Ghiaci, Hossein Farrokhpour
      This study describes solvent-free oxidation of cyclohexene using dicationic ionic liquids (DIL)/heteropoly acid (HPA) composites with molecular oxygen. Structural characterization of the DIL/HPA composites was carried out by different techniques such as ICP, FT-IR, 1H NMR, BET, TGA, XRD, FESEM, EDX and TEM. Characterization results confirmed that heteropoly acids i.e., tungstophosphoric (H3PW12O40, TPA) and molybdophosphoric acid (H3PMo12O40, MPA) were incorporated with DILs without distortion of the Keggin structure of the heteropoly acids. Two different dicationic ionic liquids with linear and aromatic linkage, DIL-L and DIL-A, were prepared and applied for synthesis of the composites. Effective parameters including the effect of temperature, time, oxygen pressure, amount of the selected catalyst, i.e., DIL-L/tungstophosphoric acid was thoroughly investigated. The catalyst was found to be stable and recyclable. The main product of the reaction was cyclohexene-2-one (Cy-one) at 70°C and 15bar oxygen pressure after 6h. Additionally, theoretical calculations at the PM6 semi-empirical method was performed on DILs/HPA complexes with different number of DIL molecules to explore the capacity of HPA in interaction with DILs and obtained the orientations of DILs around the Keggin oxoanion of the HPA. The calculations showed that the maximum number of DIL molecules around the [H2PW12O40]− oxoanion was five and the interaction of DIL-L withthe oxoanion was stronger than that of DIL-A which was in agreement with the experimental data.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.025
      Issue No: Vol. 543 (2017)
  • Effect of La, Mg and Mo additives on dispersion and thermostability of Ni
           species on KIT-6 for CO methanation
    • Authors: Yuhao Lv; Zhong Xin; Xin Meng; Miao Tao; Zhicheng Bian; Jia Gu; Wenli Gao
      Pages: 125 - 132
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Yuhao Lv, Zhong Xin, Xin Meng, Miao Tao, Zhicheng Bian, Jia Gu, Wenli Gao
      Ni catalysts supported on mesoporous silica KIT-6 with and without promoters (La, Mg and Mo) were prepared by co-impregnation and their catalytic performances on CO methanation were conducted in fixed-bed reactor. As a result, promoters had a negligible benefit to the dispersion of Ni particles since Ni species were highly dispersed on KIT-6. While the metal Ni surface area was reduced due to partial coverage of metal Ni by promoters. Besides the improvement of the promoters (La and Mo) on CO methanation activity, a suitable Ni- support interaction can hindrance the aggregation of Ni particles on 0.5MoNi/KIT-6 during thermal treatment. While the aggregation of Ni particles was severe on Ni/KIT-6 and 0.3LaNi/KIT-6 due to the weak interaction between Ni and support. Furthermore, Mg enhanced the interaction between Ni and KIT-6 by forming NiO-MgO solid solution, but simultaneously some “unsupported” free and “surface rich” Ni species was formed, which would aggregate into larger particles (ca. 25×40nm) during thermal treatment. It was worth mentioning that high pressure (3MPa) improved the catalytic activities and thermostability of catalysts for CO methanation but the aggregation of metal particles were more severe after thermal treatment in reactants under high temperature.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.05.038
      Issue No: Vol. 543 (2017)
  • Bimetallic Pd-Fe supported on γ-Al2O3 catalyst used in the ring opening
           of 2-methylfuran to selective formation of alcohols
    • Authors: Gloria Lourdes Dimas-Rivera; Javier Rivera De la Rosa; Carlos J. Lucio-Ortiz; Daniela Xulú Martínez-Vargas; Ladislao Sandoval-Rangel; Domingo Ixtcoatl García Gutiérrez; Carolina Solis Maldonado
      Pages: 133 - 140
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Gloria Lourdes Dimas-Rivera, Javier Rivera De la Rosa, Carlos J. Lucio-Ortiz, Daniela Xulú Martínez-Vargas, Ladislao Sandoval-Rangel, Domingo Ixtcoatl García Gutiérrez, Carolina Solis Maldonado
      This work presents the hydrogenation of 2-methylfuran (2-MF) in gaseous fluid phase into a catalytic reactor in order to obtain products with good properties to be used as biofuel. Bimetallic nanoparticles were obtained by impregnation on Al2O3 from the classic catalytic metals used in hydrogenation reactions such as platinum and palladium, combined with iron, to observe the catalytic activity and the selectivity to form interest biofuel compounds. Pt, Pd, Pt-Fe and Pd-Fe catalysts (with 0.5% wt. metal content) supported on alumina were reduced at 450°C and tested. At 200°C, Pt/Al2O3 and Pt-Fe/Al2O3 catalysts presented less than 19% conversion and the main formed product was pentene (90% selectivity). The Pd/Al2O3 catalyst conversion of 2-MF was of 5% at 200°C, obtaining 1-pentanol and 1-butanol as products, together with a 28% of selectivity. The Pd-Fe/Al2O3 catalyst presented the highest conversion of 2-MF at 200°C of 31%, the production of alcohols such as 1-pentanol, 2-pentanol and 1-butanol summed a selectivity of 39%. Since the Pd-Fe/Al2O3 catalyst presented the best performance, it was analyzed under high-resolution transmission electron microscopy technique. The HRTEM image revealed the presence of 5nm size nanoparticles over the alumina, and Pd and Fe oxide nanoparticles were identified measuring the interplanar distances of exposed planes. A FePd3 nanoparticle alloy was also identified, which was the difference in having a greater hydrogenation efficiency for the 2-MF molecule.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.019
      Issue No: Vol. 543 (2017)
  • Influence of a carbon nanotube support and supercritical fluid reaction
           medium on Fe-catalyzed Fischer-Tropsch synthesis
    • Authors: David P. Roe; Rui Xu; Christopher B. Roberts
      Pages: 141 - 149
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): David P. Roe, Rui Xu, Christopher B. Roberts
      To investigate the influence of a supercritical fluid reaction medium on nanoparticle-catalyzed Fischer-Tropsch synthesis (FTS), Fe-based nanoparticle catalysts supported on carbon nanotubes were prepared and tested under both gas phase and supercritical FTS operating conditions. The nanoparticle catalysts displayed high activity, low CH4 selectivity, and elevated oxygenate selectivity. Conversion and selectivity towards heavy, unhydrogenated products were elevated under supercritical operation. With K promotion, aldehydes were produced under both gas phase and supercritical conditions. This study demonstrated the necessity of K promotion for aldehyde production and demonstrated that appreciable amounts of aldehydes can be produced in gas phase, Fe-catalyzed FTS.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.020
      Issue No: Vol. 543 (2017)
  • Piperidine-appended imidazolium ionic liquid as task-specific basic-IL for
           Suzuki and Heck reactions and for tandem Wittig-Suzuki, Wittig-Heck,
           Horner-Emmons-Suzuki, and Horner-Emmons-Heck protocols
    • Authors: Hemantkumar M. Savanur; Rajesh G. Kalkhambkar; Kenneth K. Laali
      Pages: 150 - 161
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Hemantkumar M. Savanur, Rajesh G. Kalkhambkar, Kenneth K. Laali
      Facile, high yielding, one-pot methods for the synthesis of a library of diversely substituted bi-aryls, diarylethenes, and aryl-enoates, via Suzuki and Heck reactions, and by sequential Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck reactions are reported. The reactions employ piperidine-appended imidazolium ionic liquid [PAIM][NTf2] as a task-specific basic-IL, butyl-methyl-imidazolium ionic liquid [BMIM][X] (X=PF6, BF4) as solvent, and catalytic amounts of Pd(OAc)2, with no other additives. Wittig and Horner-Emmons reactions are effected by reacting substituted benzaldehydes with 4-bromobenzyl-PPh3 (or bromomethyl-PPh3) phosphonium salts, or diethylphosphonate with bromobenzaldehydes respectively, to form the corresponding ethenes. Subsequent cross-coupling reactions are accomplished by addition of aryl-boronic acid or phenyl-ethenes along with Pd(OAc)2 to bring about the aforementioned hyphenated transformations. The feasibility to perform double-olefination via Wittig and Horner-Emmons reactions with dialdehydes to form highly conjugated bis-styryl and bis-enoate compounds is also shown. The [BMIM][X] solvent is recycled and reused.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.015
      Issue No: Vol. 543 (2017)
  • Effect of Cu deposition method on silico aluminophosphate catalysts in
           NH3-SCR and NH3-SCO reactions
    • Authors: Marco Schiavoni; Sebastiano Campisi; Antonella Gervasini
      Pages: 162 - 172
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Marco Schiavoni, Sebastiano Campisi, Antonella Gervasini
      In this study, a commercial silicoaluminophosphate of chabazite (CHA) structure with low addition of copper phase (ca. 2–3wt.%) deposited from Cu-acetate, Cu-nitrate, and Cu-chloride precursors (Cu/CHA) with ionic-exchange and impregnation procedures was taken into consideration thanks to its known good de-NOx activity. The Cu/CHA samples were tested in the NH3-SCR (catalytic reduction of NOx by NH3) and NH3-SCO (catalytic oxidation of NH3) reactions, in the 200–500°C interval. Important differences of Cu aggregation on CHA surface were evidenced between the samples prepared by ionic-exchange and impregnation, as observed from Uv-DRS, EPR, and H2-TPR analyses. Well-dispersed Cu-phase on the CHA surface and more aggregated CuOx clusters were formed by depositing the Cu-phase with ionic-exchange and impregnation method, respectively. All the Cu/CHA samples were active and selective in the NH3-SCR reaction in the explored temperature interval, with enhanced performances of the sample prepared by impregnation. NH3-SCO selectivity to N2 was higher (80–95%) on the samples with lower Cu aggregation while sample with surface CuOx species was less selective (65%) but more active at lower temperatures. Temperature to obtain 50% of ammonia conversion (T50 °C) was around 250°C, for the sample prepared by impregnation, and in the range 355–390°C for the samples prepared by ionic-exchange. The study permitted to disclose the possibility to use Cu/CHA samples in a cascade NH3-SCR and NH3-SCO reactions in a future process for zero emissions of both NOx and NH3.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.034
      Issue No: Vol. 543 (2017)
  • Palladium-catalyzed hydroamination of farnesene—Long chain amines as
           building blocks for surfactants based on a renewable feedstock
    • Authors: Thiemo A. Faßbach; Nadine Gösser; Fridolin O. Sommer; Arno Behr; Xiaoqiang Guo; Steffen Romanski; Dirk Leinweber; Andreas J. Vorholt
      Pages: 173 - 179
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Thiemo A. Faßbach, Nadine Gösser, Fridolin O. Sommer, Arno Behr, Xiaoqiang Guo, Steffen Romanski, Dirk Leinweber, Andreas J. Vorholt
      Long chain amines are of great importance for industrial chemistry as they are precursors for surfactants like amine oxides or quaternary ammonia compounds. The atom efficient, homogeneously catalyzed hydroamination using 1,3-dienes offers linear linkage of the amine group to renewables like β‐farnesene, offering a C15 skeletal structure, which is a desired size for surfactants, the so called laurics. The presented paper describes the development of a catalytic system for the hydroamination of the industrially available terpene β‐farnesene in good to excellent yields. The reaction works with a broad range of amines, aliphatic and aromatic ones. Furthermore, functionalities, like alcohol or ether groups, are tolerated, yielding functionalized farnesylamines. With two model nucleophiles, a scale-up to a 5000mL reactor was accomplished; the obtained products were functionalized to surfactants and afterwards characterized by their surface activity.
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      PubDate: 2017-07-02T12:53:59Z
      DOI: 10.1016/j.apcata.2017.06.014
      Issue No: Vol. 543 (2017)
  • Highly efficient transformation of γ-valerolactone to valerate esters
           over structure-controlled copper/zirconia catalysts prepared via a
           reduction-oxidation route
    • Authors: Shanshan Liu; Guoli Fan; Lan Yang; Feng Li
      Pages: 180 - 188
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Shanshan Liu, Guoli Fan, Lan Yang, Feng Li
      Design and development of novel and efficient catalysts are crucial but challenging for the catalytic conversion of biomass and derivatives to fuels and chemicals. In this paper, a novel separate nucleation and aging steps assistant reduction-oxidation strategy was developed to synthesis CuO/ZrO2 complex precursor with homogeneously distributed Cu and Zr components, which can be used as an ideal precursor for the synthesis of highly dispersed Cu/ZrO2 catalyst. Characterization results revealed that homogeneous dispersion of CuO, high surface area of ZrO2 support with controlled porous structure, and strong interaction between CuO and ZrO2 in CuO/ZrO2 precursor could lead to the enhanced Cu dispersion and the formation of Cu+ active centers. The synthesized Cu/ZrO2 catalysts exhibited excellent catalytic performance (85.4% conversion of GVL and 98.0% selectivity of pentyl valerate) in the catalytic transformation of GVL to valerate esters, more efficient than that of Cu/ZrO2-CP and Cu/ZrO2-CH catalysts prepared via co-precipitation and chemisorption hydrolysis methods, respectively. The superior catalytic performance was mainly attributed to both the cooperation of Cu0 and Cu+ species and the highly dispersed surface Cu0, thereby improving the adsorption and polarization of CO bond in GVL and the following dissociation of H2 to produce active hydrogen for the hydrogenation step during the catalytic transformation of GVL. Moreover, such copper-based catalysts exhibited potential applications in the exploitation and utilization of biomass resources with significantly enhanced efficiency.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.032
      Issue No: Vol. 543 (2017)
  • The study of morphology effect of Pt/Co3O4 catalysts for higher alcohol
           synthesis from CO2 hydrogenation
    • Authors: Bi Ouyang; Shuhao Xiong; Yuhua Zhang; Bing Liu; Jinlin Li
      Pages: 189 - 195
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Bi Ouyang, Shuhao Xiong, Yuhua Zhang, Bing Liu, Jinlin Li
      Two kinds of Co3O4 with different morphologies (nanorods and naoplates) were used to support Pt nanoparticles to prepared Pt/Co3O4 catalysts. The properties of the nano-structured Co3O4 and Pt/Co3O4 were characterized by XRD, SEM, TEM, H2-TPR and XPS techniques. The catalyst activity was studied in higher alcohol synthesis from CO2 hydrogenation in fixed-bed reactor operated at 2MPa and 190–230°C. The catalyst gave a stable and relative higher CO2 conversion and alcohol selectivity during 50h under mild reaction condition. The morphology of Co3O4 affected the catalyst’s CO2 conversion and production selectivity. The active surface of Pt/Co3O4-p catalyst was high dispersed Pt and Co nanoparticles anchored on Co3O4 support with some oxygen vacancies, evidenced by XRD results. The highest space time yield of higher alcohol (0.56mmolgcat −1 h−1) was achieved at 200°C and 2MPa for Pt/Co3O4-p catalyst.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.031
      Issue No: Vol. 543 (2017)
  • The shape effect of La2O2CO3 in Pd/La2O2CO3 catalyst for selective
           hydrogenation of cinnamaldehyde
    • Authors: Fei Wang; Zhongnan Zhang; Xuejiao Wei; Qihua Fang; Xingmao Jiang
      Pages: 196 - 200
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Fei Wang, Zhongnan Zhang, Xuejiao Wei, Qihua Fang, Xingmao Jiang
      Controllably adjusting the morphology of nanocatalysts is known as an effective way to improve catalytic performance. Pd/La2O2CO3 catalysts with different morphologies (nanorods and nanoparticles) were successfully synthesized via simple hydrothermal method and evaluated for selective hydrogenation of cinnamaldehyde. The highly catalytic activity (86% HCAL selectivity at 100% CAL conversion at 3h) occurred over Pd/La2O2CO3-NRs with La2O2CO3 nanorods as support. Remarkably, Pd/La2O2CO3-NRs catalyst not only showed better catalytic performance, nearly 10 times higher than Pd/La2O2CO3-NPs catalyst, but also exhibited excellent cycling stability. CO2-TPD showed that the intense desorption peaks at about 560K represented the medium-strength basic sites (La3+–O2− pairs) with a total amount of 0.13mmolg−1 on the La2O2CO3-NPs and 0.21mmolg−1 on the La2O2CO3-NRs. These results indicated that support morphology has a significant effect on catalytic activity and can modify surface basicity, which resulting in enhanced hydrogenation activity.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.039
      Issue No: Vol. 543 (2017)
  • Ethene hydrogenation on zeolite-supported rhodium clusters. A mechanistic
           study by density functional and microkinetic modeling
    • Authors: Velina K. Markova; Georgi N. Vayssilov; Alexander Genest; Notker Rösch
      Pages: 201 - 208
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Velina K. Markova, Georgi N. Vayssilov, Alexander Genest, Notker Rösch
      Experiments showed small Rh clusters, supported in zeolites, to be catalytically active in the hydrogenation of ethene. We report a computational study on the transformations of ethene over Rh4 clusters supported in a faujasite zeolite framework, in particular on the influence of the hydrogen loading of the clusters. Our density functional calculations revealed a general trend of decreasing activation energies of the hydrogenation for increasing H coverage of the metal particles. Furthermore, the coordination of the attacking H ligand crucially affects the hydrogenation barriers. At low H coverage, strongly adsorbed, bridge-bonded H ligands are responsible for the calculated higher barriers while lower barriers were calculated for top-coordinated H ligands near the organic reactants. Microkinetic modeling, based on these electronic structure results, suggests that zeolite-supported Rh4 clusters are active for hydrogenation of ethene regardless the H loading. Ethene, adsorbed in π-coordinated fashion, was determined to be a crucial resting state in this reaction.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.036
      Issue No: Vol. 543 (2017)
  • Catalytic reduction of 4-nitrophenol by palladium-resin composites
    • Authors: Nastaran Jadbabaei; Ryan James Slobodjian; Danmeng Shuai; Huichun Zhang
      Pages: 209 - 217
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Nastaran Jadbabaei, Ryan James Slobodjian, Danmeng Shuai, Huichun Zhang
      Catalytic reduction of 4-nitrophenol (4-NP) by palladium-resin catalysts is promising for 4-NP detoxification, in situ regeneration of the catalysts, and recycling of the products. In this study, we examined the catalytic reduction of 4-NP by Pd0-based catalysts supported on three neutral resins and two anion exchange resins, using hydrogen gas as the electron donor. The reduction kinetics followed the same trend as the adsorption kinetics, i.e., faster adsorption and reduction were observed at acidic pHs for the neutral resins and at basic pHs for the anionic resins (4-NP pKa =7.15). The Langmuir-Hinshelwood model based on surface reaction as the rate determining step fitted the kinetic data well. These findings point to the significant role of adsorption in the overall catalytic reaction. Cl− inhibited the reactivity of the neutral resins less than that of the anion exchangers due to the hydrophobic nature of the former. The longevity of the catalysts was examined in two tests: (1) 1mM 4-NP was repeatedly spiked into the same catalysts for eight times, where the accumulation of 4-NP and the sole reduction product (4-aminophenol) on the resin surfaces resulted in the gradual loss in the catalytic activity, which was largely restored after regeneration, and (2) the catalysts were subjected to fresh influent in each adsorption and catalytic reduction cycle for seven times, where the catalysts sustained their reactivity through the seven cycles, significantly eliminating the need for frequent regeneration.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.023
      Issue No: Vol. 543 (2017)
  • Graphene oxide mediated cellulose-derived carbon as a highly selective
           catalyst for the hydrolysis of cellulose to glucose
    • Authors: Meng Zhang; Minghui Wu; Qing Liu; Xin Wang; Tao Lv; Lishan Jia
      Pages: 218 - 224
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Meng Zhang, Minghui Wu, Qing Liu, Xin Wang, Tao Lv, Lishan Jia
      A novel graphene oxide mediated flake carbon-based solid acid bearing SO3H, COOH, and OH groups was synthesized via hydrothermal carbonization of cellulose with a small amount of graphene oxide (GO) as a structure-directing agent and subsequent sulfonation. A series of characterization results show that with a certain addition of GO, the carbonized samples can transform from micron carbon spheres into crumpling layers, and the hydrophilcity of the GO induced catalysts also get increased. The prepared solid acid with 10wt% addition of GO (10-SGOC) exhibits excellent glucose selectivity (94.22%) at a moderate temperature (160°C). The catalytic performance of 10-SGOC is attributed to its lamellar structure with good hydrophilcity and the existence of functional OH, COOH and SO3H groups. The unique structure and hydrophilcity could improve the dispersion of the catalyst and provide effective interaction between reactants and functional groups on the solid acid, then OH groups adsorb cellulose on surface of the catalyst and acidic sites hydrolyze cellulose to glucose. Moreover, the catalyst displays good stability in catalytic activity; the selectivity of glucose could remain above 92.48% after four cycling experiments.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.033
      Issue No: Vol. 543 (2017)
  • A critical perspective on the design and development of metal oxide
           catalysts for selective propylene ammoxidation and oxidation
    • Authors: James F. Brazdil
      Pages: 225 - 233
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): James F. Brazdil
      The objective of this article is to use the example of the development of metal oxide catalysts for the selective ammoxidation and oxidation of propylene to illustrate successful catalyst design strategies for achieving enhanced yields of acrylonitrile and acrolein, respectively. The processes of catalytic selective ammoxidation and oxidation of propylene are not the only, albeit they are among the most industrially significant, examples of the commercial application of metal oxide selective oxidation catalysts. Other important commercial catalytic processes that use highly developed metal oxide catalysts systems include butane oxidation to maleic anhydride and alkyl aromatic ammoxidation of toluene, xylenes, and picolines (alkyl pyridines) to produce valuable aromatic nitriles including nicotinonitrile which is the precursor for nicotinic acid (niacin) an important B-complex vitamin. Using the example of industrial propylene selective (amm)oxidation, this article surveys the available patents, scientific and technical journals to chronical and analyze the development and advancement of the complex metal oxides from discovery to current state-of-the-art. Recognizing that commercial practices are proprietary, this analysis uses no known company sensitive or confidential information is included in these descriptions. From this analysis a comprehensive catalyst design strategy unfolds that is based on the enabling science of solid state chemistry and the results of the characterization tools it provides. This provides a viable platform to unlock the next level of metal oxide catalyst development with ultra-high selectivity for hydrocarbon oxidation.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.022
      Issue No: Vol. 543 (2017)
  • Production of lactic acid from glycerol via chemical conversion using
           solid catalyst: A review
    • Authors: Noraini Razali; Ahmad Zuhairi Abdullah
      Pages: 234 - 246
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Noraini Razali, Ahmad Zuhairi Abdullah
      The production of lactic acid from glycerol has been receiving a lot of attention due to the efficient roles of glycerol as raw material in producing various useful chemicals. Selective oxidation and hydrothermal reactions using solid catalyst have been found as potential techniques in producing high selectivity of lactic acid. Typically, glycerol reaction mechanisms are proposed based on oxidative dehydrogenation, dehydration and benzylic acid rearrangement step in alkaline aqueous medium. Bifunctionals catalyst are useful to carry out multi-step reaction requiring different active sites in one pot reaction. One of the selective oxidation processes is using bifunctional catalyst with acidic site in combination with Al3+ or Cr3+, with Lewis acid sites and a redox centre i.e. polyoxometalates (POM) exhibited high activity (93.7%) and selectivity (90.5%) to lactic acid. Meanwhile, hydrothermal reaction by using 30%CuO/ZrO2 gave 100% glycerol conversion and 94.6% selectivity to lactic acid. Currently, the development of efficient catalysts through suitable combinations of nonprecious metals is highly proposed. This paper critically reviews the recent progress in this area of research by classifiying catalysts based on active sites and roles of catalyst characteristics. The detail discussion on the influencing parameters to enhance the selectivity of lactic acid and glycerol conversion is also provided in detail.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.07.002
      Issue No: Vol. 543 (2017)
  • NH3-SCR of NO over one-pot Cu-SAPO-34 catalyst: Performance enhancement by
           doping Fe and MnCe and insight into N2O formation
    • Authors: Dong Zhang; Ralph T. Yang
      Pages: 247 - 256
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Dong Zhang, Ralph T. Yang
      One-pot synthesized Cu-SAPO-34 was prepared. Fe and MnCe (at Mn/Ce=3/7) species were doped on the Cu-SPAO-34 samples by incipient wetness impregnation. The introduction of Fe and MnCe using incipient wetness impregnation enhanced the ammonia selective catalytic reduction (SCR) activity and resulted in the best SCR performance for meeting diesel engine emission control requirement. The 1%Fe/1%MnCe/3.86%Cu-SAPO-34 catalyst showed higher hydrothermal stability than 1%Fe/1%MnCe/Cu-SSZ-13. It also exhibited higher SO2 resistance and wider temperature window, and yielded less N2O product. N2O formation was systematically investigated to study the mechanism. The catalysts were characterized by XRD, XPS, H2-TPR and NH3-TPD. The addition of Fe and MnCe increased Lewis acidity, which was beneficial to SCR activity. The lower oxidation state Fe species (Fe2+) was also responsible for the enhanced SCR activities.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.021
      Issue No: Vol. 543 (2017)
  • Cobalt doped CuO nanoparticles as a highly efficient heterogeneous
           catalyst for reduction of 4-nitrophenol to 4-aminophenol
    • Authors: A. Sharma; R.K. Dutta; A. Roychowdhury; D. Das; A. Goyal; A. Kapoor
      Pages: 257 - 265
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): A. Sharma, R.K. Dutta, A. Roychowdhury, D. Das, A. Goyal, A. Kapoor
      We present here a simple thermal route for synthesizing 5.1wt% cobalt doped CuO nanoparticles (NPs) as the optimized composition of the best heterogeneous CuO catalyst for catalytic reduction of toxic 4-nitrophenol to industrially beneficial 4-aminophenol. The reduction is completed in merely 3min in the presence of 8mM NaBH4 as reducing agent. The optimized catalyst dose was 2mg/L for converting 0.12mM 4-nitrophenol and the corresponding rate constant (k) for reduction reaction was 43.8×10−3 s−1 per mg of catalyst. The catalytic reduction reaction was monitored by UV–vis spectroscopy method and by HPLC analysis. The mechanism is discussed in the light of hydride transfer phenomenon facilitated by large surface area and positive surface charge of the cobalt doped CuO nanoparticles. The cobalt doping resulted in: (a) increasing surface area due to decrease in particle size of the CuO NPs to 10nm, measured by HRTEM; (b) improve stability of the cobalt doped CuO NPs. The cobalt dopant occupied the grain boundaries of CuO to reduce the particle size as derived from positron annihilation lifetime spectroscopy. The X-ray photoelectron spectroscopy analysis of unused catalyst and the spent catalyst revealed occurrence of Co2+ and Co3+ states at the surface. While the X-ray diffraction studies of spent catalyst confirmed the inhibition of reduction of the surface CuO to metallic copper in the presence of NaBH4, attributable to cobalt doping. It was concluded that cobalt doping led to stable and efficient CuO NPs as catalyst for reduction reaction.
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      PubDate: 2017-07-12T03:54:58Z
      DOI: 10.1016/j.apcata.2017.06.037
      Issue No: Vol. 543 (2017)
  • Efficient transformation in characteristics of cations supported-reduced
           graphene oxide nanocomposites for the destruction of trichloroethane
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Usman Farooq, Muhammad Danish, Shuguang Lu, Mark L. Brusseau, Muhammmad Naqvi, Xiaro Fu, Xiang Zhang, Qian Sui, Zhaofu Qiu
      Experiments were conducted to investigate the use of graphene-oxide supported metallic nanocomposites for improving the degradation of trichloroethane (TCA) by sodium percarbonate (SPC). Two methods of production, chemical reduction (CR) and solvo-thermal (ST), were tested for preparation of single (Fe) and binary (Fe-Cu) nanocomposites supported by reduced graphene oxide (rGO). A variety of analytical techniques including N2 adsorption Brunauer-Emmett-Teller (BET), x-ray diffraction (XRD), fourier-transfrom infrared spectroscopy (FTIR), and transmisison electron microscopy (TEM) were applied to characterize the physicochemical and microstructural properties of the synthesized nanocomposites. The characterization indicated that the CR method produced nanocomposites that comprised only mesoporous structure. Conversely, both micro and mesoporous structures were present for samples produced with the ST method. The synthesized single and bimetallic composites produced from the ST method showed higher surface areas, i.e. 93.6m2/g and 119.2m2/g as compared to the ones synthesized via the CR method, i.e. 13.8m2/g and 38.0m2/g respectively. The results of FTIR and XRD analyses confirmed that the ST method produced highly crystalline nanocomposites. SEM and TEM analysis validated that metallic particles with definite morphology well distributed on the surface of rGO. X-ray photoelectron spectroscopy (XPS) analysis confirmed the homogeneity nanocomposites and occurrence of variation in copper oxidation states during degradation process. EDS mapping validate the homogeneous distribution of Cu and Fe at reduced graphene oxide surface. The Fe-Cu/rGO (ST) activated SPC system effectively degraded TCA (92%) in 2.5h at low nanocomposite dose compared to the Fe-Cu/rGO (CR) and only Fe, for which the maximum degradation efficiencies achieved were 81% and 34%. In conclusion, excellent catalytic characteristics were observed for the ST-synthesized single and bimetallic (Fe/rGO, Fe-Cu/rGO) catalysts. These catalysts were successful in improving the degradation of TCA via activated SPC.
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      PubDate: 2017-07-23T11:24:54Z
  • The influence of different promoter oxides on the functionality of hybrid
           CuZn-ferrierite systems for the production of DME from CO2-H2 mixtures
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): G. Bonura, C. Cannilla, L. Frusteri, F. Frusteri
      In this work the one pot production of dimethylether (DME) by catalytic hydrogenation of carbon dioxide has been studied. The catalytic behaviour of the CuZn-ferrierite hybrid system has been assessed, considering the influence of five different oxides promoters (i.e., ZrO2, CeO2, La2O3, Al2O3, Ga2O3) both on the physico-chemical properties (i.e., surface area, pore volume, copper surface area and dispersion, metal-oxide distribution, acid-base capacity) and on the activity-selectivity pattern. The reaction was carried out in a fixed bed reactor, by feeding CO2 and H2 in the molar ratio 1: 3. The CuZn-FER catalysts doped with Zr, Al or Ga showed a similar behaviour in the DME production, while Ce and La exhibited an inadequate functionality as oxide promoters, mainly evidencing a higher activation energy on the CO2 activation path. The final DME productivity resulted to be driven not so much by specific metallic properties, rather by the presence of an adequate surface balance of acid-base sites that, in a different way, shift the reactions of the global process towards the equilibrium value.
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      PubDate: 2017-07-23T11:24:54Z
  • Three-way catalytic reactions on Rh-based catalyst: Effect of Rh/ceria
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Chengxiong Wang, Tingting Zheng, Jun Lu, Xiaodong Wu, Harold Hochstadt, Yunkun Zhao
      Rh-based catalysts were prepared by various methods and it was found that preparation methods play an important role in metal-support interaction (MSI) control which affects the catalytic performance of catalyst. The results suggest that the catalytic reduction of NO is mainly achieved by C3H6 in exhaust and H2 generated from the water-gas shift reaction as well as the steam reforming of C3H8 and CH4. Concentration of water in reaction stream has a significant influence on the water-gas shift and steam reforming reactions. The removal of C3H6 is accomplished by oxygen-induced oxidation instead of steam reforming reaction. In addition, Rh/ceria interactions promote the formation of active oxygen species and surface oxygen vacancy that respectively favors CO oxidation and NO reduction with a high N2 selectivity. Rh@CeO2 system shows high thermal stability due to Rh/ceria interaction.
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      PubDate: 2017-07-23T11:24:54Z
  • Pd3Sn nanoparticles on TiO2 and ZnO supports as catalysts for
           semi-hydrogenation: Synthesis and catalytic performance
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Shaun K. Johnston, Nikolay Cherkasov, Elena Pérez-Barrado, Atte Aho, Dmitry Y. Murzin, Alex O. Ibhadon, M. Grazia Francesconi
      The two catalysts Pd3Sn/TiO2 and Pd3Sn/ZnO were prepared via a one-pot procedure based on the “polyol method” with the addition of a capping agent (polyvinylpyrrolidone) to control the particle size distribution. The same procedure was used to prepare Pd/TiO2 and Pd/ZnO for comparison. All four catalysts showed high activity and selectivity for the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) in the liquid phase under identical conditions. However, Pd3Sn/TiO2 and Pd3Sn/ZnO show selectivities to alkene significantly higher than that of the Pd catalysts. Specifically, the selectivity increases from 96.4% to 97.4% on TiO2 support, and 96.2% to 97.6% on ZnO support, at 90% conversion. Transition electron microscopy shows nanoparticles evenly dispersed on the support, with mean particle sizes as low as 4.1 (±0.8) nm when Sn is incorporated into the catalyst. Unsupported Pd3Sn was prepared using the same method and characterised by powder X-Ray diffraction followed by the Rietveld refinement. Pd3Sn was found to be single-phase and isostructural to Pd metal with a face centred cubic unit cell.
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      PubDate: 2017-07-23T11:24:54Z
  • CO2 conversion to propylene carbonate catalyzed by ionic liquid containing
           organosilane groups supported on titanate nanotubes/nanowires
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Wesley F. Monteiro, Michele O. Vieira, Aline S. Aquino, Michèle O. de Souza, Jeane de Lima, Sandra Einloft, Rosane Ligabue
      The direct conversion of CO2 into propylene carbonate was investigated using pristine sodium titanate nanotubes (TNT) and nanowires (TNW) on which the ionic liquid (IL) 1-methyl-3-(3-trimethoxysilylpropyl)imidazolium chloride was supported, resulting in IL-TNTs and IL-TNWs, respectively. Anchorage of the IL through its organosilane groups (around 28wt%) on the surface of TNT and TNW was confirmed by FTIR, DRX, EDS and TGA analyses. All the nanostructured materials showed good catalytic activity after CO2 cycloaddition to propylene oxide. IL-TNTs and IL-TNWs exhibited high catalytic performance (TOF=46 and 49h−1, respectively) and 100% selectivity in propylene carbonate (propylene/catalyst molar ratio=580, cat/cocat molar ratio=2.4, 4.0MPa of CO2, 383.15K, 6h).
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      PubDate: 2017-07-23T11:24:54Z
  • Enhancing catalytic activity of lanthanide oxysulfate (La2O2SO4/Pr2O2SO4)
           via facile manipulation of nanoscale catalyst synthesis process and
           reactor configuration
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Shuai Tan, Dongmei Li
      We recently reported that a facile colloidal synthesis approach can be used to synthesize nanoscale Eu2O2S to significantly enhance activity of rare-earth based catalysts. While extending this method to synthesize other coordinated lanthanide complexes (La and Pr), we discovered that mixed phases of lanthanide monosulfide (LnS) and lanthanide oxysulfate (Ln2O2SO4) (Ln=La, Pr) co-existed in the product, instead of the desired single-phase complex. Utilizing the high oxophilicity of sulfur and Ln elements, we successfully converted LnS impurity to Ln2O2SO4 nanoparticles with unique morphologies by simply heating them in air. By impregnating the resultant nanocatalysts onto a commercial tubular oxide support (referred to as CCR), CO conversion of nanoscale La2O2SO4 for high temperature water-gas-shift (HTS) reaction increased from nearly zero in fixed-bed reactor (FBR) to 35% in CCR module at 500°C. Reactivity comparison among different catalyst size, morphology and type suggests that the enhanced catalytic activity of La2O2SO4/Pr2O2SO4 nanocatalysts in CCR derives from the increased surface area and minimized aggregation.
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      PubDate: 2017-07-23T11:24:54Z
  • Understanding the role of oxygen surface groups: The key for a smart
           ruthenium-based carbon-supported heterogeneous catalyst design and
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Francisco R. García-García, Esteban Gallegos-Suarez, Marcos Fernández-García, Antonio Guerrero-Ruiz, Inmaculada Rodríguez-Ramos
      The aim of this work is to understand the role of oxygen surface groups during the preparation, activation and reaction of heterogeneous ruthenium catalysts supported on activated carbon materials. Hence, non-promoted and sodium promoted ruthenium catalysts supported on two different activated carbon materials, with and without oxygen surface groups, were prepared by successive incipient wetness impregnation and tested in the ammonia decomposition reaction. The catalysts were characterised with a multi-technique approach that involves; nitrogen adsorption isotherms at −196°C (BET and BJH methods), temperature programed oxidation (TPO), scanning electron microscope (SEM), temperature programed desorption (TPD), transmission electron microscopy (TEM), in-situ X-ray absorption near edge structure (XANES), temperature programed reduction (TPR) and microcalorimetry of hydrogen chemisorption. The performance of the different ruthenium supported catalysts during the ammonia decomposition reaction was determined in a constant flow fixed-bed reactor at 1atm, in the temperature range from 350°C to 450°C. This work shows how the oxygen surface groups of the activated carbon can be used to control/influence (i) the final oxidation state of ruthenium particles, (ii) ruthenium particles size, (iii) selective deposition of the sodium promotor. We believe that such use of the presence of surface groups on the activated carbon surface could potentially be employed to improve the catalytic performance of next generation heterogeneous catalysts.
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      PubDate: 2017-07-23T11:24:54Z
  • TiO2-doped Mn2O3-Na2WO4/SiO2 catalyst for oxidative coupling of methane:
           Solution combustion synthesis and MnTiO3-dependent low-temperature
           activity improvement
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Pengwei Wang, Guofeng Zhao, Ye Liu, Yong Lu
      The Mn2O3-Na2WO4/SiO2 catalyst is the most promising one among the enormous catalysts for the oxidative coupling of methane (OCM) but only at above 800°C. No doubt that lowering temperature of the OCM process is at the forefront of this catalysis field. A promising low-temperature active and selective TiO2-doped Mn2O3 Na2WO4/SiO2 catalyst, consisting of 6wt% TiO2, 6wt% Mn2O3, 10wt% Na2WO4 and SiO2 in balance, is developed by solution combustion synthesis (SCS) method. This catalyst is capable of converting 20% CH4 with 70% selectivity to C2-C3 hydrocarbons even at 700°C (catalyst bed temperature) and is stable for at least 250h without deactivation sign, for a feed gas of 50% CH4 in air using a gas hourly space velocity of 8000mLgcat. −1 h−1. In contrast, the non-TiO2-doped SCS catalyst is almost inactive at 700°C whereas it can achieve reactivity (∼24% CH4 conversion and ∼74% C2-C3 selectivity) comparable to the TiO2-doped one at 800°C. XRD and Raman results evidently reveal that the formation of MnTiO3 during the OCM process appears to be important for the low-temperature OCM activity improvement by TiO2-doping.
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      PubDate: 2017-07-23T11:24:54Z
  • Enhancement of CO bond cleavage to afford aromatics in the
           hydrodeoxygenation of anisole over ruthenium-supporting mesoporous metal
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Tuan Ngoc Phan, Young-Kwon Park, In-Gu Lee, Chang Hyun Ko
      Mesoporous TiO2, Al2O3, silica (SBA-15), and nonporous conventional TiO2 (P25) were used as supports for Ru catalysts in the hydrodeoxygenation (HDO) of anisole. The catalytic reaction was performed in a batch reactor at 200°C and 5–30bar H2 pressure. It was shown that the selectivity of this catalytic system towards benzene strongly depended on the H2 pressure, being higher at low pressure. Moreover, significant differences in the product distribution were observed for these catalysts suggesting the strong influence of the nature of supports on controlling the reaction pathway. The SBA-15-supported Ru catalyst (Ru/SBA-15) catalyzed the reaction primarily by the hydrogenation (HYD) pathway. The mesoporous-Al2O3-supported Ru (Ru/meso-Al2O3) promoted the reaction via the HYD and demethylation pathways simultaneously. Mesoporous-TiO2-supported Ru (Ru/meso-TiO2) and P25-supported Ru (Ru/P25) promoted higher yield of benzene, indicating its high selectivity for the direct deoxygenation (DDO) route. The use of meso-TiO2 facilitated the spillover effect, leading to the formation of numerous Ti3+ defect sites and oxygen vacancies. As a result, Ru/meso-TiO2 with anatase phase exhibited higher selectivity for the DDO pathway compared to nonporous P25 with a mixed rutile and anatase phase. The results indicated that the phase and mesoporous structure of TiO2 plays an important role in promoting its interaction with Ru particles and in selecting the HDO reaction pathway.
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      PubDate: 2017-07-23T11:24:54Z
  • On A-doping strategy for tuning the TWC catalytic performance of
           perovskite based catalysts
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): A. Garbujo, M. Pacella, M.M. Natile, M. Guiotto, J. Fabro, P. Canu, A. Glisenti
      Several perovskites of the type La1-xAxCo0.5Cu0.5O3 (A=K, Sr, Ba; x=0, 0.25, 0.5) and a Sr-doped understoichiometric one, have been prepared by citrate method aiming at application as noble metals free catalysts for automotive application. The catalysts have been characterized by BET, X-ray diffraction (XRD), Temperature Programmed Reduction (TPR), X-Ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM) and the effect of A-doping has been investigated. The catalytic activity was studied in model reactions (CO oxidation, CO assisted NO reduction), and in a complex three way catalysts (TWC) mixture approaching automotive exhaust composition at both stoichiometric and O2-limiting conditions and the obtained results are discussed in relation with characterization results. A-doping induces the formation of highly dispersed cubic CuO particles, as observed in the understoichiometric samples. Doping also influences the surface segregation. La segregation is observed in the undoped LaCo0.5Cu0.5O3 sample whereas K is surface segregated in La0.75K0.25Co0.5Cu0.5O3; Co segregates in the Ba-doped perovskite and Sr in the understoichiometric La0.35Sr0.35Co0.5Cu0.5O3. The reducibility (TPR) is altered by A-doping. The reactivity results suggest that in simple CO+O2 and CO+NO mixtures the activation temperature is increased by any doping, but at 400°C the conversion in the CO assisted NO reduction is not significantly different with respect to the one obtained in the undoped catalyst. Activity with a more complex mixture, simulating actual engine exhaust, reveals the interesting activity of the Sr-doped catalysts, that outperform LaCo0.5Cu0.5O3 at both stoichiometric and O2-lean conditions. NO reduction can be achieved at lean O2 conditions, where it is quantitative from 400°C. The possibility to reach similar or better activity by replacing the use of La, which is a Rare Earth Element, by using Sr is particularly interesting. Stability at high temperatures and at fast fluctuations of O2 in inlet stream for 50% Sr-doped catalyst confirms these results.
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      PubDate: 2017-07-23T11:24:54Z
  • Cu9-Alx-Mgy catalysts for hydrogenation of ethyl acetate to ethanol
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Jingxia Tian, Jun Hu, Wenjuan Shan, Peng Wu, Xiaohong Li
      Cu9-Al x or Cu9-Al x -M y (M=Mg, Ca, Ba or Sr) catalysts were prepared by a deposition-precipitation method, characterized by means of H2-TPR, XRD and N2 sorption, and applied for hydrogenation of ethyl acetate to ethanol in a fixed-bed reactor. The molar ratio of Cu/Al or Cu/Al/M and the reaction parameters were investigated thoroughly. As a result, the Cu9-Al0.5-Mg1.5 catalyst with higher specific surface area, lower initial reduction temperature and better metal dispersion furnished 97.8% ethyl acetate conversion with 98% selectivity to ethanol under optimal reaction conditions. Moreover, the Cu9-Al0.5-Mg1.5 catalyst also showed good lifetime and neither the activity nor selectivity decreased during 210h test. Based on the characterization of the Cu9-Al0.5-Mg1.5 catalyst, the optimal Cu+/Cu0 proportion played a key role in determining the superior performance.
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      PubDate: 2017-07-23T11:24:54Z
  • Do happy catalyst supports work better' Surface coating of silica and
           titania supports with (poly)dopamine and their application in
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Rajesh Munirathinam, Dorothée Laurenti, Denis Uzio, Gerhard D. Pirngruber
      In order to meet the demand for cleaner fuels, it is necessary to develop high performing hydrotreating catalysts. Although organic additives are often used to improve the performances of hydrotreating catalysts, bio-polymer additives have not yet been thoroughly investigated. We recently showed that dopamine, a neurotransmitter molecule, which is also frequently found in adhesive bio-polymers, efficiently coats the surface of an alumina carrier material and modifies the interaction with active components of hydrotreating catalysts, i.e. cobalt and molybdenum. The catalytic performance of the CoMoS/Al2O3 catalysts could, thus, be improved. In the present paper we extend the strategy to other carrier materials (silica and titania). The catalysts prepared on (poly)dopamine (Pdop) coated silica showed enhanced activity for the hydrogenation of toluene reaction and the selective HDS of FCC gasoline model feed. Pdop coating lowers the MoS2 nanocrystallites' stacking on silica, thereby improving the accessibility of active edge sites. The origin of this increase in catalytic activity may be found in the higher capacity of Pdop's functional groups to interact with metallic precursors leading to a better dispersion of the active phase. On the contrary, when the interaction between the dopamine and the support is too strong (as observed for TiO2), the functional groups of Pdop are not available for interaction with Co and Mo species, resulting in decreased catalytic activity.
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      PubDate: 2017-07-23T11:24:54Z
  • Aqueous microwave-assisted synthesis of non-interpenetrated metal-organic
           framework for room temperature cycloaddition of CO2 and epoxides
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Robin Babu, Seol-Hee Kim, Amal Cherian Kathalikkattil, Roshith Roshan Kuruppathparambil, Dong Woo Kim, Sung June Cho, Dae-Won Park
      A multilinker non-interpenetrated metal-organic framework, UMCM-15, was synthesized by using microwave power as an alternative energy-efficient tool for the first time. The synergistic catalytic activity, when combined with a co-catalyst containing a strongly nucleophilic anion, was studied in the solventless room temperature cycloaddition between epoxides and CO2. Unlike previous reports on UMCM-15 synthesized in the high-boiling solvent dimethylformamide, low boiling water/ethanol mixture was used as the solvent herein. This approach holds potential as a sustainable green methodology. Crystal formation during the microwave-assisted (MW) synthesis was monitored at certain time intervals. The favorable role of non-interpenetrated pillared structures in promoting room temperature CO2-epoxide cycloaddition reactions was explained by comparing the catalytic efficiency of the three-linker extended pillar-layered non-interpenetrated UMCM-15 with its analogous pillared structures built from two- and three-fold interpenetrated ([Zn2(BDC)2(4,4′-bipy)] and [Zn2(NDC)2(4,4′-bipy)]) catalytic systems with a single dicarboxylate linker. The efficacy of the microwave-assisted UMCM-15(M) catalyst in cycloaddition reactions was proved by comparing the catalytic activity of UMCM-15(M) with that of the congener made by solvothermal synthesis, UMCM-15(S). In addition, a plausible mechanism for the synergistic operation of the Lewis acid sites and nucleophiles was suggested.
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      PubDate: 2017-07-23T11:24:54Z
  • Toward non-precious nanocomposite photocatalyst: An efficient ternary
           photoanode TiO2 nanotube/Co9S8/polyoxometalate for photoelectrochemical
           water splitting
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Ran Liu, Zhixia Sun, Xixi Song, Yuzhuo Zhang, Lin Xu, Lu Xi
      At present the photoelectrochemical (PEC) water splitting achieves a very high efficiency, but the development of the efficient and inexpensive photoanode materials is still desired for practical application. Herein, we fabricate a composite photoanode consisting of TiO2 nanotube arrays modified with polyoxometalate (POM) and Co9S8, in which POM aims to facilitate charge separation and Co9S8 acts as good electron transport mediator. It is the first introduction of Co9S8 into PEC water oxidation system. Although these three components are all non-precious inorganic materials, the photocurrent density of the TiO2/Co9S8/POM composite photoanode reaches up to 1.12mA/cm2 at 1.23V vs RHE under simulated solar light illumination, which is among the highest PEC water oxidation photoanodes. Particularly, the TiO2/Co9S8/POM composite photoanode shows an 8.5-fold improvement in photocurrent density compared to the pristine TiO2 nanotube array photoanode. The measurements of EIS and Mott-Schottky plots revealed that the TiO2/Co9S8/POM composite photoanode held the best efficiency of charge separation and transport at the interface as well as the highest carrier density. The aforementioned results demonstrate a feasible approach to improving the PEC water splitting efficiency by dual modification of TiO2 nanotube arrays with low-cost materials.
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      PubDate: 2017-07-23T11:24:54Z
  • Cu3(BTC)2 catalyzed oxidation of silane to silanol using TBHP or water as
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Nagaraj Anbu, Amarajothi Dhakshinamoorthy
      In the present work, a series of metal organic frameworks are examined for the conversion of Si-H to Si-OH using either t-butylhydroperoxide (TBHP) or water as oxidants. The reaction is optimized using dimethylphenylsilane (1) as a model substrate. It is observed that Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) exhibits a comparable activity with Zr(BDC) (BDC: 1,4-benzenedicarboxylate) while the activity of Fe(BTC) is lower than Cu3(BTC)2 using TBHP as oxidant. On the other hand, the reaction of 1 with water in the presence of Cu3(BTC)2 as a catalyst showed complete conversion of 1 with 99% selectivity to the corresponding silanol, but other MOFs like Fe(BTC) and Zr(BDC) are inactive under identical reaction conditions. A series of control experiments indicate that Cu2+ is essential to convert 1 to 2 under the present experimental conditions. Further, Cu2+ in Cu3(BTC)2 acts as redox centre with TBHP whereas it behaves as a Lewis acid using water as oxidant. High conversion and selectivity is observed for all the silanes studied under the present experimental conditions. The catalyst stability is assessed by powder XRD, FT-IR and SEM images and observing no structural deterioration of Cu3(BTC)2 either in TBHP or water as oxidants. Furthermore, hot filtration test indicated the absence of copper under the present reaction conditions, thus confirming the stability of Cu3(BTC)2.
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      PubDate: 2017-07-23T11:24:54Z
  • Ethylene oligomerization in zeolite-grafted Cr(III)-diphosphinoamine
           catalysts using triisobutylaluminium as cocatalyst: Change from
           dimerization to trimerization due to confinement effect
    • Abstract: Publication date: 25 August 2017
      Source:Applied Catalysis A: General, Volume 544
      Author(s): Huaiqi Shao, Jingjing Wang, Ruofei Wang, Liwu Song, Xiaoyan Guo, Tao Jiang
      Zeolite-supported Cr(III)-diphosphinoamine (Cr(III)-PNP) catalysts were prepared through grafting PNP on HY and NaY zeolites followed by complexing with CrCl3(THF)3 for ethylene oligomerization. The structure of supported Cr(III)-PNP catalysts was characterized by scanning electron microscopy, X-ray diffraction, nitrogen adsorption and desorption, thermogravimetric analyses and Fourier transform infrared, and the influence of the supported pattern on reactivity for ethylene oligomerization were investigated. The results revealed that the complex of Cr(III)-PNP was grafted on silicon hydroxyls in the pore channel of HY zeolite to decrease pore size but to maintain pore structure. Comparing with homogeneous Cr(III)-PNP producing 1-butene as main product, HY-supported catalyst had higher activity and selectivity toward 1-hexene increased from 4.07% to 73.24% using triisobutylaluminium as cocatalyst. The increase is attributed to confinement effect of the pore channel, which increases the stability of the chromacycloheptane intermediate to 1-hexene. The confinement effect for ethylene oligomerization was revealed in experiment.
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      PubDate: 2017-07-23T11:24:54Z
  • Selective dealumination of HZSM-5 zeolite boosts propylene by modifying
           1-butene cracking pathway
    • Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): María Ibáñez, Eva Epelde, Andrés T. Aguayo, Ana G. Gayubo, Javier Bilbao, Pedro Castaño
      An HZSM-5 zeolite was dealuminated by steaming with its self-adsorbed water at mild temperatures (300, 400 or 500°C), characterized and tested in the transformation of 1-butene into propylene. The structural, porous-surface and acidic properties of the catalysts (unmodified and steamed) were characterized using N2 adsorption-desorption isotherms, tert-butylamine adsorption-TPD, XRD, 29Si and 27Al MAS-NMR, and FTIR spectroscopies, and the results pointed to the following evidences: (i) dealumination took place transforming specific strong acid, framework tetrahedral Al sitings (located within the micropores) into distorted and extra-framework species; and (ii) the porous-surface properties were less sensible to the treatment. The acid site density was shifted towards the intersections of the zeolite micropores (of weaker acidity), resulting in the selective inhibition of hydrogen transfer pathway, thus lowering the selectivity of paraffins, aromatics and ultimately, coke deposition. Overall, the performance of the 500°C-steamed catalyst compared with the parent one was enhanced: propylene selectivity was boosted 69%, coke deposition dropped by 34%, whereas the initial conversion only fell 6%.
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      PubDate: 2017-07-23T11:24:54Z
  • Hydrodeoxygenation of guaiacol on tungstated zirconia supported Ru
    • Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Adid Adep Dwiatmoko, Inho Kim, Lipeng Zhou, Jae-Wook Choi, Dong Jin Suh, Jungho Jae, Jeong-Myeong Ha
      Ru nanoparticles supported on tungstated zirconia (WZr) were prepared and used for the catalytic hydrodeoxygenation of guaiacol to deoxygenated hydrocarbon fuels. The tuning of tungsten, from 5 to 20wt%, adjusted the number of acid sites on the tungstated zirconia and the size of the Ru nanoparticles. The optimum fraction of tungsten was determined for the optimum hydrodeoxygenation activity. The conversion of guaiacol reached a maximum of 96.8% for 10wt% of tungsten. Increasing the tungsten fraction increased the number of acid sites and the dispersion of Ru, but the formation of tungsten oxide (WOx) particles with too large fraction of tungsten inhibited the formation of smaller Ru nanoparticles, thus reducing the catalytic activity.
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      PubDate: 2017-07-23T11:24:54Z
  • Effect of Cp*Iridium(III) Complex and acid co-catalyst on conversion of
           furfural compounds to cyclopentanones or straight chain ketones
    • Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Yong-Jian Xu, Jing Shi, Wei-Peng Wu, Rui Zhu, Xing-Long Li, Jin Deng, Yao Fu
      In this paper, Cp*Ir (III) Complex and acid co-catalyst system was developed. By using Cp*Ir and γ-Al2O3 (Lewis acid), 5-hydroxymethylfurfural (5-HMF) can be converted efficiently to 3-hydroxymethyl cyclopentanone (HCPN). Meanwhile, Cp*Ir and Brønsted acid can promote conversion of 5-HMF to 1-Hydroxy-2,5-hexanedione (HHD). The effect of Lewis acid and Brønsted acid on the hydrogenation of furan derivatives was studied. Mechanism of conversion of 5-HMF to HCPN was discussed in detail and mechanism proposed by our predecessors was revised. Instead of being an intermediate for the formation of HCPN, it is believed that, HHD is a product of another reaction pathway. HHD condensed via Aldol reaction to produce 3-methylcyclopenten-2-ol-1-one (MCP) instead of HCPN. Under the promotion of Lewis acid, 5-HMF firstly convert to the precursor of HHD. After that, the reaction is through 4 π-electrocyclic ring closure process and HCPN was formed ultimately. Furthermore, we found that our Cp*Ir and acid co-catalyst system is suitable for a variety of furfural compounds. By using Cp*Ir, Brønsted acid can promote conversion of furfural compounds to straight chain ketones and Lewis acid can promote the rearrangement of furfural compounds to cyclopentanone derivatives.
      Graphical abstract image

      PubDate: 2017-07-23T11:24:54Z
  • Transition-metal incorporated heteropolyacid-ionic liquid composite
           catalysts with tunable Brønsted/Lewis acidity for acetalization of
           benzaldehyde with ethylene glycol
    • Authors: Xiaoxiang Han; Kai Ouyang Chunhua Xiong Xiujuan Tang Qing Chen
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Xiaoxiang Han, Kai Ouyang, Chunhua Xiong, Xiujuan Tang, Qing Chen, Kuiwu Wang, Li-Li Liu, Chin-Te Hung, Shang-Bin Liu
      A series of transition-metal (M=Mn, Fe, Co, Ni, Cu) ion-exchanged tungstophosphoric acid (H3PW12O40; TPA)-based ionic liquid (IL) catalysts, synthesized by incorporating metal and methylimidazolium propyl sulfobetaine (MIMPS) zwitterionic IL precursors onto TPA, were exploited for acetalization of benzaldehyde (BzH) with ethylene glycol (EG). These organic-inorganic, water-soluble M-MIMPS-TPA composite salts possess not only strong Brønsted and Lewis acidities but also exhibited unique self-separation property desirable for catalyst separation and recycling. The superior acetalization activities observed for these novel M-MIMPS-TPA catalysts are attributed to their strong acidity, Brønsted/Lewis acid synergy, and low mass transport resistance. Among them, the Ni[MIMPSH]PW12O40 catalyst showed extraordinary catalytic performance and durability with a benzaldehyde glycol acetal selectivity and yield of 99.0 and 94.6%, respectively, in excellent agreement with results from response surface methodology. Further kinetic study gave rise to an activation energy of 34.11kJ/mol for the acetalization reaction, surpassing most reported catalysts.
      Graphical abstract image

      PubDate: 2017-07-02T12:53:59Z
  • A safer and greener chlorohydrination of allyl chloride with H2O2 and HCl
           over hollow titanium silicate zeolite
    • Authors: Xinxin Peng; Changjiu Xia Min Lin Xingtian Shu Bin Zhu
      Abstract: Publication date: 5 August 2017
      Source:Applied Catalysis A: General, Volume 543
      Author(s): Xinxin Peng, Changjiu Xia, Min Lin, Xingtian Shu, Bin Zhu, Baorong Wang, Yao Zhang, Yibin Luo, Xuhong Mu
      Industrial production of dichloropropanols through chlorohydrination of allyl chloride suffers from a series of disadvantages such as use of hazardous Cl2, low atom economy, low dichloropropanol concentration and serious pollution. In this work, a safer and greener route for chlorohydrination of allyl chloride with H2O2 and HCl over hollow titanium silicate (HTS) at mild condition is developed. Unlike the traditional Cl2-based chlorohydrination, this novel method is initiated via synergistic effect of Lewis acidity (HTS) and Brønsted acidity (HCl) to promote occurrence of oxidation, protonation and nucleophilic reaction of allyl chloride simultaneously and hence dichloropropanols are generated. Owing to a completely different reaction route, the formation of 1,2,3-trichloropropane by-product is depressed and the content of dichloropropanol exceeded 22wt%, which increase by about 4 times compared with traditional Cl2-based chlorohydrination (the content of dichloropropanol is below 4wt%). At the optimized conditions, both of the allyl chloride conversion and dichloropropanol selectivity could approach 99% simultaneously and the waste is minimized. What’s more, the HTS was reusable. Concentrated HCl solution treatment was adopted to test HTS’s stability. The characterization and catalytic evaluation results reveal that, although parts of the framework Ti species have transformed into non-framework Ti and then leached into the solution, HTS remains structural stable, and the allyl chloride conversion and dichloropropanol selectivity didn’t decrease obviously during the treatment.
      Graphical abstract image

      PubDate: 2017-06-21T17:06:01Z
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