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Journal Cover Catalysis Today
  [SJR: 1.348]   [H-I: 164]   [5 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0920-5861
   Published by Elsevier Homepage  [3039 journals]
  • Partial oxidation of methanol over copper supported on nanoshaped ceria
           for hydrogen production
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Daniel G. Araiza, Antonio Gómez-Cortés, Gabriela Díaz
      Copper (5wt.%) supported on ceria nanopolyhedra, nanorods and nanocubes was studied as catalyst for hydrogen production from partial oxidation of methanol (POM). Supports were prepared by hydrothermal approach and addition of copper was achieved by wet impregnation. Catalysts were characterized by EDS, XRD, TEM, HRTEM, N2 adsorption, H2-TPR, N2O Chemisorption, CH3OH-TPD, Raman and DRIFT spectroscopies. POM reaction was studied at O2/CH3OH molar ratio of 0.3 as a function of temperature in the range 160–280°C and as a function of time on stream for 24h at 265°C. As a result of the support morphology the following features were observed: (i) variety of copper species on the surface of the nanoshaped ceria; (ii) different capability and stability of carbonate formation; (iii) desorption of products from CH3OH-TPD at different temperatures; (iv) activity, selectivity and stability variations in the POM reaction related to oxidation state of the copper phase. At constant temperature, polyhedra and rod-like catalysts show similar performance, but the former one produces lower amounts of CO.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Effect of the calcination temperatures of the Fe-based catalysts supported
           on polystyrene mesoporous carbon for FTS Synthesis
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Marcia G.A. Cruz, Fabiano A.N. Fernandes, Alcemira C. Oliveira, Josue M. Filho, Alcineia C. Oliveira, Adriana F. Campos, E. Padron-Hernandez, Enrique Rodríguez-Castellón
      The porous Fe-based catalysts supported on polystyrene mesoporous carbon were studied in the Fischer-Tropsch Synthesis. The solids were pretreated at different calcination temperatures and their characterizations were examined by X-ray diffraction (XRD), Raman spectroscopy, Scanning and Transmission electron microcopies (SEM and TEM), textural properties, elemental composition by X-ray dispersive spectroscopy (EDS), temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). It was shown that the preexistent carbides phases, obtained upon using elevated temperatures of calcinations procedure, were not completely reoxidized during the reaction, while the formation of carbides through the polymeric carbon reaction with magnetite and/or metallic iron resulted in highly active catalyst for FTS.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Catalytic activity of palladium nanocubes/multiwalled carbon nanotubes
           structures for methyl orange dye removal
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): O. Arciniega Cano, C.A. Rodríguez González, J.F. Hernández Paz, P. Amezaga Madrid, P.E. García Casillas, A.L. Martínez Hernández, C.A. Martínez Pérez
      In this work, the synthesis and catalytic activity measurements of a nanostructured material formed by palladium (Pd) nanocubes supported on multiwalled carbon nanotubes (MWCNTs) for removing methyl orange as a model of organic contaminant from aqueous solution are presented. The nanocubes were synthesized by a reduction process of H2PdCl4 and a non-covalent method that involves a surfactant functionalization of the carbon nanotubes was used to produce the nanostructured material. Characterization was performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis. Results showed well dispersed Pd nanocubes, in the range of 15–25nm, bonded onto the carbon nanotubes. The catalytic experiments exhibited 81.9% methyl orange removal after 8min and 99% after 60min using 1mg of the nanostructured material per every 20mg/L of the dye.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Modified gelcasting of microwave assisted synthesized sulfur-doped anatase
           for photocatalytic degradation of organic compounds
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): A. Cortéz-Lorenzo, L. Escamilla-Perea, K. Esquivel-Escalante, R. Velázquez-Castillo
      Sulfur-doped anatase nanoparticles were synthesized using titanium isopropoxide and thiourea, reactions were done through a microwave assisted hydrothermal method to control the morphology, crystallinity and the dimensions. Pure anatase was also obtained as a reference material for photocatalytic characterization. All synthesis reactions were carried out at 215°C, using a potency of 600W during 60min. Crystalline phases were identified by XRD and by HRTEM the crystal structure was studied, and the dimensions of nanocrystal were determined. The images recorded were analyzed with a Digital Micrograph software. Subsequently, the synthesized anatase was used in order to obtain ceramics with controlled porosity through the modified gelcasting process. This process was performed in order to reduce the photocatalyst loss when organic compound degradation reactions were carried out. The anatase was mixed with polymers, dispersants and solvents to produce a reticulated gel which made the anatase easy to be molded and consequently, ceramic plates were formed. The ceramic porosity was observed with a SEM and their photocatalytic activities were evaluated by photodegradation reactions of methyl red dye in water solution. All these reactions lasted 3h and samples were collected at different times during the reaction. Color removal was evaluated with UV–vis measurements following the color disappearing at 434nm wavelength. Significant differences in photocatalytic properties were observed between doped and pure anatase despite the low concentration of sulfur (0.1% weight.)
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      PubDate: 2016-12-07T04:57:13Z
       
  • Pretreatment impact on the morphology and the catalytic performance of
           hybrid heterodimers nanoparticles applied to CO oxidation
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Luelc Souza da Costa, Daniela Zanchet
      In this work, we applied seeded growth colloidal method to produce Au-FexOy dumbbells nanoparticles (DBNPs). The colloidal DBNPs were characterized and deposited on SiO2 to evaluate the effect of Au-FexOy interface on the catalytic activity in CO oxidation (CO+1/2O2 →CO2). In particular, we addressed the impact of redox pretreatments in the catalytic activity. Catalytic data showed that the catalyst was not very active after the first oxygen activation but after a reduction step there was a substantial increase in the catalyst activity. A detail characterization showed that DBNPs suffered great morphological and structural changes with the formation of core/shell Au-FexOy structures, in which the FexOy shells were irregular and presented lower crystallinity. The results suggest that the increase in catalytic activity was related to the formation of a more extended Au-FexOy interface after the pretreatments, thereby increasing the amount of active sites.
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      PubDate: 2016-12-07T04:57:13Z
       
  • Titania nanotubes decorated with anatase nanocrystals as support for
           active and stable gold catalysts for CO oxidation
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Alberto Sandoval, Rodolfo Zanella, Tatiana E. Klimova
      Gold nanoparticles supported on titania nanostructured materials were prepared, characterized and tested in CO oxidation. Two nanostructured supports were used: titania nanotubes (TNT) synthesized by the Kasuga method and titania nanotubes decorated with TiO2 anatase nanocrystals prepared by post-synthetic treatment of TNT with 0.05M HNO3 solution at 70°C for 48h (TNT-T). Gold catalysts with 4wt.% of Au nominal loading were prepared by deposition-precipitation with urea. A reference Au catalyst supported on TiO2 Degussa P-25 was also prepared. Supports and catalysts were characterized by N2 physisorption, XRD, UV–vis and Raman spectroscopy, TPR, SEM-EDX and HRTEM. HRTEM characterization showed that gold nanoparticles with an average size between 2 and 7nm were obtained in all catalysts making them suitable for CO oxidation. Catalytic tests showed differences in activity and stability among the prepared catalysts. The Au/TNT catalyst presented poor activity for CO oxidation, meanwhile the Au/TNT-T catalyst showed higher activity than the Au/TiO2 Degussa P-25, especially at a low temperature interval (−10 to 100°C). Stability tests performed for Au/TNT-T and Au/TiO2 Degussa P-25 catalysts at 25°C revealed higher stability of the Au/TNT-T catalyst, attributed to low sintering of gold nanoparticles.
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      PubDate: 2016-12-07T04:57:13Z
       
  • MoOx-VOx based catalysts for the oxidative desulfurization of refractory
           
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Marco A. Alvarez-Amparán, Luis Cedeño-Caero
      The oxidative desulfurization (ODS) process has emerged as a new technology to achieve ultra-low sulfur levels in diesel fuels. This work presents the performance of MoOx-VOx based catalysts in the ODS process and an evaluation of the interaction between MoOx and VOx in these bimetallic catalysts, using Al2O3 as catalytic support, and hydrogen peroxide and tertbutil-hidroperoxide as oxidant agents. The catalysts were characterized by scanning electron microscopy (SEM-EDX), nitrogen physisorption, X-ray diffraction (XRD) and temperature programed reduction (TPR). The catalytic activity of MoOx-VOx/Al2O3 was higher than the monometallic catalysts: MoOx/Al2O3 and VOx/Al2O3. The characterization results suggested that in MoOx-VOx catalysts the molybdenum species interact strongly with the support and that the vanadium species were distributed mainly as isolated-vanadium species, due to the interaction between VOx and MoOx.
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      PubDate: 2016-12-07T04:57:13Z
       
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2


      PubDate: 2016-12-07T04:57:13Z
       
  • Contents list
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2


      PubDate: 2016-12-07T04:57:13Z
       
  • Special issue on selected contributions of the 8th International Symposium
           on “Advanced Catalytic Materials”, Cancun, Mexico, August 17–20,
           2015
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): José Manuel Domínguez, Manuel Ramos Murillo, Jorge Ramírez Solís


      PubDate: 2016-12-07T04:57:13Z
       
  • Vanadium and titanium oxide supported on mesoporous CMK-3 as new catalysts
           for oxidative desulfurization
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Lorena Rivoira, Juliana Juárez, Horacio Falcón, Marcos Gómez Costa, Oscar Anunziata, Andrea Beltramone
      Vanadium supported-CMK-3 catalysts with vanadium loading of 1–7wt.% were studied in the oxidative desulfurization (ODS) of dibenzothiophene as a model sulfur compound. The activity was compared with titanium supported-CMK-3. Structural and textural characterization of the catalysts was performed by means of N2 adsorption, XRD, UV–vis–DRS, Raman spectroscopy, XPS, TEM and TPR. The dispersion and the nature of the vanadium species depend on the V loading, so does the catalyst activity. Vanadium supported-CMK-3 with 7wt.% of vanadium loading was the most active catalyst for ODS of DBT using hydrogen peroxide (H2O2) as oxidant and acetonitrile as solvent. 100% of DBT elimination was attained at short time in mild conditions. Carbon ordered mesoporous CMK-3 with high surface area and high pore volume promotes a very good anchorage of metallic oxides in the carbons framework reaching high active sites distribution and more stable nanoclusters. The reusability of the catalyst indicates that V-CMK-3 is a potential catalyst for the ODS of dibenzothiophene.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Hydrogenation of tetralin in presence of nitrogen using a noble-bimetallic
           couple over a Ti-modified SBA-15
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Verónica A. Vallés, Brenda C. Ledesma, Gina A. Pecchi, Oscar A. Anunziata, Andrea R. Beltramone
      Monometallic Pt- and bimetallic Pt-Ir-modified Ti-SBA-15 were used in the hydrogenation of tetralin to decalin in the presence of 150ppm of N as quinoline and indole at 250°C and 15atm of pressure of hydrogen, using a Parr reactor. The catalyst was synthesized using sol-gel method and Ti was added during the synthesis using Tetraethyl Orthotitanate. Pt/Ir was added by wetness impregnation. The catalysts prepared were extensively characterized by X-ray diffraction (XRD), N2 adsorption isotherms, UV–vis-DRS, Raman spectroscopy, XPS, TEM-EDS and TPR. UV–vis-DRS and Raman spectroscopy confirmed that Ti was incorporated in tetrahedral coordination in the framework of the SBA-15. The analysis showed that the mesoporous structure was maintained after metal incorporation and Ti incorporation helps to reduce significantly the size of the metals clusters and improves its dispersion considerably. Pt-Ir/Ti-SBA-15 was the most active catalyst. The experimental data were quantitatively represented by a modified Langmuir-Hinshelwood type rate equation. The preliminary results show these materials as a promising catalyst for HDT reactions.
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      PubDate: 2016-12-07T04:57:13Z
       
  • XAFS study on promoting effect of Au via NiO reduction in Au-Ni bimetallic
           clusters
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3
      Author(s): Shogo Shirakawa, Mayuko Osaki, Yasutaka Nagai, Yusaku F. Nishimura, Kazuhiko Dohmae, Shin’ichi Matsumoto, Hirohito Hirata
      Au-Ni bimetallic clusters were identified as possible automobile catalysts that do not contain a platinum-group metal (PGM). The Au-Ni bimetallic clusters were prepared as nanoparticles of Au and Ni using a polyol method. The oxidation states of the Au and Ni species and catalytic activities were studied simultaneously under a NO-CO stream using time-resolved operando X-ray absorption fine structure (XAFS) analysis. Under the investigated reaction conditions, the clusters pretreated by O2 initially composed of mixtures of Au and NiO were easily reduced to bimetallic Au-Ni nano-particles. The Au atoms promote the release of oxygen from nearby NiO within the cluster. The resulting Au-Ni alloy species exhibit NO purification activity matching that of Rh.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Ordered mesoporous CoO-NiO-Al2O3 bimetallic catalysts with dual
           confinement effects for CO2 reforming of CH4
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 2
      Author(s): Xin Huang, Changchun Ji, Changzhen Wang, Fukui Xiao, Ning Zhao, Nannan Sun, Wei Wei, Yuhan Sun
      Ordered mesoporous CoO-NiO-Al2O3 bimetallic catalysts with different Co/Ni molar ratios were prepared by an evaporation-induced self-assembly method. The samples were characterized by means of XRD, N2 physisorption, H2-TPR, TEM, XPS, Raman and TGA, and tested for CO2 reforming of CH4. Characterization results indicated that the formation of Ni-Co nano-alloy anchored in the ordered mesoporous skeleton led to the enhancement of stability of active sites and thus suppressed carbon deposition during reforming reaction, particularly for the C5N5 catalyst. Compared with the ordered mesoporous monometallic NiO-Al2O3 catalyst, the C5N5 catalyst exhibited superior stability without obvious deactivation for 150h reforming reaction and holds a promising candidate for cost-effective reforming process.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Catalytic transfer hydrogenation of biomass-derived levulinic acid and its
           esters to γ-valerolactone over ZrO2 catalyst supported on SBA-15 silica
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3
      Author(s): Yasutaka Kuwahara, Wako Kaburagi, Yohsuke Osada, Tadahiro Fujitani, Hiromi Yamashita
      A series of ZrO2 catalysts supported on mesoporous SBA-15 silica were synthesized and examined as catalysts in the production of γ-valerolactone (GVL) from biomass-derived levulinic acid and its esters via a catalytic transfer hydrogenation (CTH) using several alcohols as hydrogen donors. Among the catalysts examined, ZrO2 supported on high-surface-area SBA-15 silica bearing highly-dispersed zirconium species exhibited the highest catalytic activity, of which reaction rate was 1.7 times higher than that of the conventional bulk ZrO2 catalyst. Zr K-edge XAFS analysis revealed that Zr4+-oxide species with a low-coordination state anchored on silica surface is the dominant active species. Such a Zr species efficiently converted levulinic acid and its esters to GVL (∼95% yields) under mild reaction conditions (150°C, 1.0MPa Ar), and was reusable over multiple catalytic cycles without significant loss of catalytic performances. Comparative experiments, combined with detailed characterizations using NH3/CO2-TPD and in-situ FTIR, proposed a plausible reaction mechanism where basic ZrOH site triggers the CTH reaction involving a six-member ring transition state.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Dry reforming of CH4 on Co/Al2O3 catalysts reduced at different
           temperatures
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 2
      Author(s): É. Horváth, K. Baán, E. Varga, A. Oszkó, Á. Vágó, M. Törő, A. Erdőhelyi
      The reforming of methane with carbon dioxide has been investigated at 773K on 10% Co/Al2O3 reduced at different temperatures up to 1173K. The catalysts were characterized by BET, TPR, XRD and XPS methods. TPR and XPS results revealed that during the pre-treatment of the catalysts the Co only partially reduced. The reduction degree and the amount of the structured metallic cobalt increased with the reduction temperature. The conversion of the reactants was the highest on the sample reduced at 973K, but the turnover frequencies of CO and H2 formation increased as the reduction temperature increased. The amount of surface carbon significantly depended on the pre-treatment temperature of the catalysts. The IR spectra registered at the beginning of the reaction indicate that tilted CO was formed, but the position of the absorption bands depends on the reduction temperature of the catalysts. Similarly, the pre-treatment temperature influenced the type of the surface carbon determined by XPS. We assume that the different structures of the metallic Co formed in pretreatment resulted in the different catalytic behaviors.
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      PubDate: 2016-12-07T04:57:13Z
       
  • Contents list
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 2


      PubDate: 2016-12-07T04:57:13Z
       
  • The 7th China–Japan Workshop on Environmental Catalysis and
           Eco-Materials was held in Guangzhou, China, November 6th–9th, 2015
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3
      Author(s): D. Ye, M. Ogura


      PubDate: 2016-12-07T04:57:13Z
       
  • Significant enhancement in activity of Pd/TiO2 catalyst for formaldehyde
           oxidation by Na addition
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3
      Author(s): Yaobin Li, Changbin Zhang, Hong He
      Developing an effective material for indoor HCHO elimination at ambient temperature is of great significance. In this work, a series of Pd/TiO2 catalysts with different Na loadings were prepared and tested for their activity in HCHO oxidation. The results indicated that Na addition had a remarkable promotion effect on Pd/TiO2 catalysts for HCHO oxidation, and the optimal Na loading was 2wt.%. Features of the catalysts including the reducibility, Pd dispersion and valence state of Pd and O were elucidated using a variety of characterization techniques. The results showed that 2.0Na-Pd/TiO2 exhibited more exposure of active Pd sites and contained abundant surface OH groups, giving it the best HCHO catalytic oxidation performance of the studied catalysts. The 2.0Na-Pd/TiO2 catalyst also had high resistance to effects of space velocity and relative humidity (RH), maintaining high HCHO conversion over a wide gas hourly space velocity range of 80,000–190,000h−1 and RH of 25%–65%.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3


      PubDate: 2016-12-07T04:57:13Z
       
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 2


      PubDate: 2016-12-07T04:57:13Z
       
  • Contents list
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 3


      PubDate: 2016-12-07T04:57:13Z
       
  • Electronic binding of sulfur sites into Al2O3-ZrO2 supports for NiMoS
           configuration and their application for Hydrodesulfurization
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Leonardo Díaz-García, Víctor Santes, Tomás Viveros-García, Arturo Sánchez-Trujillo, Joel Ramírez-Salgado, Carlos Ornelas, Enrique Rodríguez-Castellón
      We present an effective chemical synthesis of bimetallic Nickel-Molybdenum catalysts. The catalysts were made using a sol-gel method with alumina modified by zirconia (Al2O3-xZrO2) support with x=0, 10 and 15 wt-% respectively. In order to measure their catalytic activity, they were evaluated through hydrodesulfurization (HDS) reaction using industrial gas oil 2 wt-% sulfur content. Results, indicate an important increase of their catalytic activity in presence of zirconia, probably as caused by electron donation from atoms as presented in zirconia tetragonal structure (XRD). Furthermore, using high resolution characterization techniques such as X-ray Photoelectron Spectroscopy (XPS) and Temperature Programmed Reduction of Sulfides (TPR-S) has revealed a special interaction between zirconia and active sites, confirming the electron donation, mainly at Mo octahedral sites, as occurred due to formation of so-called NiMoS phase. In order to complete our analysis, images of High-Resolution Transmission Electron Microscopy (HRTEM) shown dispersed laminar molybdenum sulfide structures with some bending, high stacking over c-axis when the sol-gel alumina was modified by zirconium domains.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Effect of NiMo phases on the hydrodesulfurization activities of
           dibenzothiophene
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Huan Liu, Changlong Yin, Xuehui Li, Yongming Chai, Yanpeng Li, Chenguang Liu
      Preparation of highly-active hydrodesulfurization (HDS) catalysts draws increasing attention due to environmental concerns. Now the effects of various NiMo phases on the HDS activities are investigated. Calcinations of a series of PVP-assisted synthesized NiMo oxides led to NiMo precursors with various phases. The NiMo precursors and sulfided catalysts were characterized by XRD, N2 isotherm, FT-IR, SEM, and TPR, and the activities of the NiMo catalysts were obtained in the HDS reactions of dibenzothiophene (DBT). Results revealed that the phases of α-, β-NiMoO4, and ammonium nickel molybdate were detected on the NiMo precursors. A NiMo-0.5 precursor with a H2-type hysteresis loop had very high BET surface area (144m2 g−1), which was higher than traditional metal oxides. Phases of MoS2 and Ni3S2 nanoparticles were detected on the sulfided NiMo catalysts. Catalytic results reveal that the sulfided NiMo catalysts deriving from β-NiMoO4 phase were more active than those from the α-NiMoO4 phase. A NiMo-0.1 catalyst had higher HDS activities towards DBT than the other NiMo catalysts, due to the phase of β-NiMoO4 and easy reductions of nickel oxide and molybdate, which might be beneficial for the formation of ‘NiMoS’ active phase. These findings show that for the preparations of highly-active unsupported and supported NiMo catalysts, the β-NiMoO4 phase is preferred, which provides more useful information in the development of HDS catalysts.
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      PubDate: 2016-12-07T04:57:13Z
       
  • Effect of hydrogen spillover in selective hydrodesulfurization of FCC
           gasoline over the CoMo catalyst
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Bin Liu, Lei Liu, Zhong Wang, Yongming Chai, Huan Liu, Changlong Yin, Chenguang Liu
      The synergism of promoter Co on the performance of MoS2 phase in selective hydrodesulfurization (HDS) of FCC gasoline was studied by regulating the step impregnation-sulfurization sequence of Co and Mo species to adjust the proportion of Co-Mo-S phase, separated Co9S8 and MoS2 phases. The evaluation results demonstrated that the CoMo/γ-Al2O3 catalyst with Co species first impregnation-sulfurization showed higher HDS activity and selectivity. The characterization by XRD, HRTEM, XPS, TPR and FT-IR showed that, on this catalyst, the interaction between the sulfurized Co and MoS2 phases was weak, and lead to the lower Co decoration on the MoS2 phase, thus forming more Co9S8 phase. The more formed Co9S8 phase could produce more hydrogen spillover (Hso) to create more CUS and SH groups, thus greatly improving the HDS activity and selectivity. Through the layered loading test of Co9S8/γ-Al2O3 and MoS2/γ-Al2O3 catalysts, it was found that the Hso synergetic effect between the Co9S8 and MoS2 phases could significantly improve the HDS activity, but showed very little effect on the saturation of olefins.
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      PubDate: 2016-12-07T04:57:13Z
       
  • Effect of the support and promoters in Fischer-Tropsch synthesis using
           supported Fe catalysts
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): L.A. Cano, A.A. Garcia Blanco, G. Lener, S.G. Marchetti, K. Sapag
      The effect of support and promoters on the catalytic properties of Fe supported in the FTS was studied. Precursors of supported Fe on SiO2 and SBA −15 were synthesized and doped with Cu and K. The precursors were activated in pure H2 and catalytically tested with a mixture of H2:CO=2:1, T=543K and P=10bar. The samples were characterized by atomic absorption, N2 adsorption, X-ray diffraction, TEM and TPR. Also, we used the DFT to study the changes of the electronic structure when the Fe, K and Cu are adsorbed on the SBA-15 surface. The incorporation of different ions do not alter the structural and textural properties of the support. In the FTS, all the catalysts supported on SBA-15 presented a low selectivity towards methane and a promising hydrocarbon production in the range of gasoline, showing positive effect of the support for iron catalysts for the FTS reaction. The activity order obtained was: Fe/K-SBA-15>Fe/Cu-SBA–15≈Fe-SBA–15>Fe-SiO2, which is the same order for the selectivity towards olefins. The presence of K on the SBA-15 surface increases the activity and selectivity towards olefins; an effect that can be attributed to the electrostatic effect generated by the alkaline ions.
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      PubDate: 2016-12-07T04:57:13Z
       
  • Heterogeneous acid conversion of a tricaprylin-palmitic acid mixture over
           Al-SBA-15 catalysts: Reaction study for biodiesel synthesis
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Denis A. Cabrera-Munguia, Horacio González, Aída Gutiérrez-Alejandre, J.L. Rico, R. Huirache-Acuña, Rafael Maya-Yescas, Rosa E. del Río
      In this work mesoporous Al-SBA-15 was synthesized by the sol-gel method and used as a solid acid catalyst for the conversion of a model mixture of tricaprylin with 20wt% of palmitic acid at T=175–215°C. The incorporation of aluminum to the SBA-15 through the sol-gel method, gives rise to mesoporous materials with the typical hexagonal arrangement of SBA-15 (XRD). In addition, these materials possess Lewis and Brönsted acid sites (pyridine adsorption), large surface area and wide pore diameter (N2 physisorption) being capable of catalyzing simultaneously transesterification of triglycerides (tricaprylin) and esterification of palmitic acid (up to 20wt%) resulting in FAME yields of 40–87%. A detailed analysis of the reaction products indicates that the conversion of triglyceride to diglyceride is the limiting step during the acid transesterification over Al-SBA-15 catalysts, which results from the difficulty to protonate triglycerides followed by methanol addition. A simplified lumped first order reaction model reproduces well the experimental data for the acid transesterification of tricaprylin in the presence of a high content of free fatty acids (palmitic acid). The calculated activation energy was 64.7kJmol−1 which is in the range of 45–120kJmol−1 previously reported for acid catalysts.
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      PubDate: 2016-12-07T04:57:13Z
       
  • AuCu alloy nanoparticles supported on SiO2: Impact of redox pretreatments
           in the catalyst performance in CO oxidation
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Priscila Destro, Sergio Marras, Liberato Manna, Massimo Colombo, Daniela Zanchet
      The use of colloidal metallic nanoparticles (NPs) in catalysis is an interesting strategy to address complex and fundamental aspects in this field. This synthesis methodology allows an accurate adjustment of size and shape of the metal phase, which can reveal the complex interplay of several factors that usually determine the overall catalytic activity. In the case of bimetallic NPs, another parameter can be finely tuned, namely the composition. The full potential of colloidal NPs in catalysis is indeed extremely exciting; however, crucial aspects related to the removal of the organic protective agents, in order to expose the catalytic sites, as well as the potential drawbacks of remaining synthesis residues on the surface of the NPs have still to be deeply understood. In this work, we evaluated the effect of pretreatments on the activation of AuCu alloy NPs supported on SiO2 applied to catalytic oxidation of CO, showing their significant impact in the final performance and stability of the catalyst.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Predicting the structural and electronic properties of transition metal
           monoxides from bulk to surface morphology
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 2
      Author(s): Jin-Jia Liu, Yu Meng, Pengju Ren, Bao Zhaorigetu, Wenping Guo, Dong-Bo Cao, Yong-Wang Li, Haijun Jiao, Zizhong Liu, Meilin Jia, Yong Yang, Aiju Xu, Xiao-Dong Wen
      We systematically investigate the structural, electronic and magnetic properties, bonding analysis, as well as surface morphology of transition metal monoxides (FeO, CoO and NiO) utilizing density functional theory (DFT) with various functionals across from GGA to GGA+U and hybrid functional. Our results reveal that the screened hybrid functional (HSE) could give a reasonable description on structural and electronic properties of these strongly correlated systems when compared to experiments. Local approximation GGA functional fails to yield the accuracy band gaps. GGA+U approximation are rational when given a reasonable U, but the U which reproduce a reasonable band gap often yield a significant error in describing other properties such as lattice constant or magnetic moment. The computed Crystal Orbital Overlap Population (COOP) indicates that cubic FeO and CoO are metastable phase, while the distortion occurs to enhance stability. Based on the reliable functional, the surface morphology of FeO, CoO and NiO are predicted using Wulff construction approach.
      Graphical abstract image

      PubDate: 2016-12-07T04:57:13Z
       
  • Contents list
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1


      PubDate: 2016-11-30T04:47:36Z
       
  • Catalysis for water purification
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Kwang-Ho Choo, Hyunwoong Park, Wonyong Choi


      PubDate: 2016-11-30T04:47:36Z
       
  • Well-organized, mesoporous nanocrystalline TiO2 on alumina membranes with
           hierarchical architecture: Antifouling and photocatalytic activities
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Rizwan Ahmad, Jin Kyu Kim, Jong Hak Kim, Jeonghwan Kim
      We report the development of improved antifouling and photocatalytic membranes based on an organized mesoporous TiO2 (om-TiO2) layer on a porous alumina (Al2O3) support. The om-TiO2 layer was templated by an amphiphilic graft copolymer, i.e., poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM), and was 50–70nm in pore size with high porosity and good pore interconnectivity. The precoating of poly(vinyl pyrrolidone) (PVP) on a porous alumina support was the key to providing a flat platform and improving the adhesion properties of alumina with TiO2, which allowed for the formation of om-TiO2 membranes. Fouling of photocatalytic om-TiO2 on the alumina membrane was also investigated using a laboratory-scale photocatalytic dead-end filtration reactor using a model dye compound. The fouling rate was observed to be much slower for the om-TiO2 membrane compared to the bare alumina support under UV illumination during 6h of membrane operation. The PVP precoating on the alumina support improved the permeation quality of the om-TiO2 membrane. The improved removal of the organic dye compound was thought to result from the enhanced adsorption capability of organic compounds and subsequent photocatalytic reactions on the om-TiO2 layer. However, UV illumination performed for longer than 6h gradually increased the fouling rate due to the deposition of the organic dye compound on the membrane surface, and prohibited the accessibility of the UV light to the TiO2 layer.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Elimination of trace organic contaminants during enhanced wastewater
           treatment with horseradish peroxidase/hydrogen peroxide (HRP/H2O2)
           catalytic process
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): So-Young Na, Yunho Lee
      The potential of horseradish peroxidase combined with hydrogen peroxidase (HRP/H2O2) catalytic process was assessed as an enhanced wastewater treatment technology to eliminate trace organic contaminants (micropollutants). Kinetic experiments with 17α-ethinylestradiol (EE2) as a phenolic micropollutant in synthetic buffered solutions showed that the apparent first-order rate constant of EE2 transformation (k EE2) increased linearly with increasing HRP concentration but was independent of the concentrations of H2O2 and EE2. The observed kinetic behaviors of EE2 could be well explained by the known chemistry of the HRP/H2O2 system considering the reaction of Compound II with EE2 as the rate-limiting step in the catalytic cycle of HRP under the condition of excess H2O2 over HRP. Using this HRP/H2O2 kinetic model, the second-order rate constants of the reaction of Compound II (k3) with a few selected phenolic micropollutants including EE2 and phenol and aniline could be determined and compared with those from the literature. Good correlations were found between the k3 of various phenolic or anilinic compounds (from this study and the literature) versus Hammett sigma constants, which can be used for predicting the elimination efficiency of phenolic or anilinic micropollutants. Experiments conducted using lake water and wastewater effluent matrices showed that significant elimination of phenolic micropollutants (i.e., % elimination levels of 20%–100%) could be achieved under the following treatment condition: 1.4–5.6nM (12–48U/L) of HRP, 20μM of H2O2, and 1h of reaction time. Elimination of the other tested micropollutants without phenolic moieties was less than 5%. The elimination levels of phenolic micropollutants (e.g., EE2) in real water matrices spiked at 2μM could be well predicted by the HRP/H2O2 kinetic model with the corresponding k3 value. However, relatively lower elimination levels were observed when the phenolic micropollutants were spiked at 1μg/L, indicating some reduction in the performance of the HRP/H2O2 process for eliminating phenolic micropollutants present at environmentally relevant concentrations (e.g., sub μg/L).
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Evaluation of the O3/graphene-based materials catalytic process: pH effect
           and iopromide removal
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Y. Yoon, H. Oh, Y.-T. Ahn, M. Kwon, Y. Jung, W.K. Park, T.-M. Hwang, W.S. Yang, J.-W. Kang
      Graphene-based materials, including graphene oxide (GO), reduced-graphene oxide (rGO), and non-oxidative graphene (nOG) were evaluated for catalytic ozonation in water solutions. Among the graphene-based materials evaluated for catalytic ozonation, it was confirmed that rGO was unsuitable to apply to the ozone (O3)/graphene-based materials catalytic process because the high electron mobility of rGO prevented the transformation of O3 into hydroxyl radicals (OH). On the other hand, GO, which had sufficient oxygenated functional groups on the surface, decomposed and generated the most amount of O3 and OH, respectively. Although O3/nOG process produced a lower amount of OH than O3/GO process, nOG was more effective than GO for the transformation yields of O3 into OH. Furthermore, nOG could generate OH not only in the bulk phase, but also on the surface of nOG during catalytic ozonation. However, iopromide (IPM) was effectively removed during O3/GO process due to the more OH generated in the bulk phase than O3/nOG process.

      PubDate: 2016-11-30T04:47:36Z
       
  • Manganese oxide nanorods as a robust Fenton-like catalyst at neutral pH:
           Crystal phase-dependent behavior
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Eun-Ju Kim, Dasom Oh, Chung-Seop Lee, Jianyu Gong, Jungwon Kim, Yoon-Seok Chang
      Manganese oxide nanorods with different crystal phases (α-, β-, γ-, and δ-MnO2) were prepared via a mild hydrothermal method, and examined as heterogeneous catalysts for the decomposition of H2O2 into active radicals and concomitant degradation of methylene blue (MB) dye at neutral pH. The catalytic activity of MnO2 nanorods was highly dependent upon their crystal structures, following the order of γ-MnO2 > β-MnO2 > α-MnO2 > δ-MnO2. Complete degradation of MB was achieved with γ-MnO2 in a short duration of 20min. Furthermore, γ-MnO2 exhibited much higher activity compared to iron-containing nanoparticles (Fe° and Fe3O4) and several reported catalysts in the literature. The observed trend in catalyst performance was discussed in terms of surface area, degree of crystallinity, and exposed facets. It was found that γ-MnO2 showed considerable activity over a broad range of pH and temperature as well as desired reusability for four consecutive cycles. Quenching studies indicated that hydroxyl radicals (OH) played a major role in the degradation of MB. These results provide important insight into the design of more efficient manganese oxide catalysts for wastewater treatment.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Electron shuttling catalytic effect of mellitic acid in zero-valent iron
           induced oxidative degradation
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Seung-Hee Kang, Alok D. Bokare, Yiseul Park, Chi Hun Choi, Wonyong Choi
      The enhanced oxidation capacity of zero-valent iron (ZVI) using mellitic acid (MA) as an electron shuttle catalyst was investigated using 4-chlorophenol (4-CP) as a model pollutant. In the presence of MA, enhanced electron transfer from ZVI surface to molecular oxygen resulted in higher production of hydrogen peroxide (H2O2), which subsequently increased the effective concentration of hydroxyl radical (HO) generated through the Fenton-type reaction. The possible role of MA as an efficient electron shuttle was supported by cyclic voltammetric estimation of MA reduction potential (E0 =−0.184VNHE) and corroborated with photocurrent measurements in the ZVI suspension. Control experiments using Fe(II) ions instead of ZVI demonstrated that the presence of MA in the Fe(II)/H2O2 homogeneous system had no significant effect on the 4-CP oxidation efficiency. This indicates that the formation of a Fe(II)-MA complex does not contribute to the 4-CP oxidation pathway. The primary role of MA in the ZVI/O2 system seems to mediate the electron transfer from the ZVI surface to dioxygen. It implies that organic species containing multiple carboxylic ligands (species like MA or its structural analogues) may function as an electron shuttle in the ZVI/O2 catalytic system.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Electrocatalytic activities of Sb-SnO2 and Bi-TiO2 anodes for water
           treatment: Effects of electrocatalyst composition and electrolyte
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Yong Yoon Ahn, So Young Yang, Chimyung Choi, Wonyong Choi, Soonhyun Kim, Hyunwoong Park
      This study compares the electrocatalytic behavior and performance of metal-doped oxide anodes in widely employed electrolytes (i.e., Na2SO4, NaClO4, and NaCl). Sb-doped SnO2 (Sb-SnO2), Bi-doped SnO2 (Bi-SnO2), or Bi-doped TiO2 (Bi-TiO2) are coated onto a Ta-doped IrO2 (Ta-IrO2) electrode using identical fabrication procedures involving coating and annealing cycles. The resultant electrodes display porous morphologies with interparticle connections. Crystalline phases of Sb-associated oxides are not evident in Sb-SnO2, whereas distinct Bi2O3 phases are observed in Bi-SnO2 and Bi-TiO2 because the radius of Bi3+ is larger than those of the base metals. Sb-SnO2 exhibits the highest electrocatalytic activity for the decomposition of phenol irrespective of the type of electrolyte, whereas the activity of Bi-SnO2 is always poor. The activity of Bi-TiO2 is poor in sulfate and perchlorate electrolytes; in contrast, it is remarkably enhanced and comparable to that of Sb-SnO2 in chloride electrolyte. Such chloride-specific activity of Bi-TiO2 is attributed to the effective generation of reactive chlorine species, whereas the generation of OH radicals is limited. On the other hand, Sb-SnO2 effectively catalyzes the generation of OH radicals, leading to mediated generation of reactive chlorine species. The decomposition of phenol is further examined in terms of reaction intermediates and CO2 production using Sb-SnO2 and Bi-TiO2 anodes in sulfate and chloride electrolytes. The electrocatalyst and electrolyte-dependent mechanism is discussed.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Decomposition of acetaminophen (Ace) using TiO2/UVA/LED system
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Pei Xiong, Jiangyong Hu
      For photocatalytic degradation of organic pharmaceutical pollutants in wastewater, an important limitation is low photonic efficiency. To solve this problem, using periodic illumination is a good option. However, due to the nature of widely applied traditional mercury lamp, which cannot be turned on and off efficiently, the study of periodic illumination was limited. In this research, ultraviolet-A/light emitting diode (UVA/LED) lamp was introduced and a TiO2/UVA/LED photocatalytic system was setup for acetaminophen (Ace) degradation study. The background study was conducted, which included the effects of H2O2, humic acid and bicarbonate ion concentrations. Different periodic pulse frequencies were applied, results in this study shows that smallest duty cycle (0.2) and shortest cycle time (20ms) gave the highest photonic efficiency for photocatalytic degradation of Ace in the studied range. The effect of additional H2O2 was also studied. H2O2 added into the heterogeneous reaction system enhanced both decomposition rate and photonic efficiency under both continuous illumination mode and periodic illumination mode. The enhancement effect of H2O2, however, was found more obvious for controlled periodic illumination, especially for small duty cycles and short cycle times. In addition, by the addition of H2O2, the mineralization of Ace was accelerated probably due to the increase of hydroxyl radical concentration.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Stabilization of Pickering emulsion with surface-modified titanium dioxide
           for enhanced photocatalytic degradation of Direct Red 80
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Mohsin Nawaz, Waheed Miran, Jiseon Jang, Dae Sung Lee
      Surface modification of titanium dioxide (TiO2) was carried out with salicylic acid (SA) to generate an efficient Pickering emulsion (PE)-based photocatalytic system. The PE was stabilized with 0.5 and 1.0mgmL−1 of TiO2 and SA-TiO2 by using cyclohexane and a synthetic aqueous Direct Red 80 (DR 80) solution (0.4:1) as the oil and water phases, respectively. The photocatalytic activity of solution-dispersed TiO2 was compared with that of the PE-based photocatalytic system for DR 80 degradation. In almost all PE-based photocatalytic systems, 100% color removal of DR 80 was observed within 15–60min, compared to 76% and 100% color removal, achieved after 120min, using 0.5 and 1.0mgmL−1 solution-dispersed TiO2, respectively. The estimated reaction rates of the PE-based photocatalytic system, as calculated using the Langmuir–Hinshelwood kinetics model, were almost double to those obtained for solution-dispersed TiO2. However, the addition of a free oil phase adversely affected the photocatalytic activity, and the lowest DR 80 degradation percentage was observed using 0.5 or 1.0mgmL−1 TiO2. The results demonstrated that a functional PE was successfully stabilized with SA-TiO2, and enhanced photocatalytic degradation of the azo dye was achieved in an effective and novel way.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Anodization of bismuth doped TiO2 nanotubes composite for photocatalytic
           degradation of phenol in visible light
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Imran Ali, Seu-Run Kim, Sung-Pil Kim, Jong-Oh Kim
      Bismuth doped TiO2 photocatalyst was synthesized in a one-step electrochemical anodization method. Bismuth nitrate Bi(NO3)3 was used as a bismuth source. The obtained samples were characterized by FE-SEM, XRD, EDX and XPS. The optimum synthesis conditions for bismuth doping were 1.0M bismuth nitrate in an ethylene glycol electrolyte with anodization at 40V for 2h. Compared with undoped TiO2 nanotubes, bismuth doped TiO2 photocatalyst showed a higher photocatalytic activity by a factor of 4.0 for phenol degradation under visible light irradiation. The optimum phenol degradation using a photoelectrocatalytic method was observed at a 0.5V external bias, and this degradation rate was 5.2 times faster than that observed for undoped TiO2 nanotubes. The doped bismuth TiO2 nanotubes are favorable for the separation of photo-induced electrons and holes, reducing the recombination of charges, and promoting the formation of hydroxyl radicals and superoxides that degrade phenol.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Is surface fluorination of TiO2 effective for water purification? The
           degradation vs. mineralization of phenolic pollutants
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Jungho Ryu, Wooyul Kim, Jaesung Kim, Jinjung Ju, Jungwon Kim
      The photocatalytic activity of surface fluorinated TiO2 (F-TiO2) for both the degradation and mineralization of bisphenol A (BPA) was compared with that of pure TiO2. The degradation rate of BPA (i.e., the conversion rate of BPA to intermediates) was enhanced, but the mineralization rate (i.e., the conversion rate of BPA to CO2) was reduced by surface fluorination. These behaviors are different from the general trend in photocatalysis, in which the photocatalyst with a higher activity for the degradation also shows a higher activity for the mineralization. The surface fluorination of TiO2 enhanced the production of the hydroxyl radical (OH), which is primarily responsible for the degradation of BPA, by altering the OH generation pathway. However, the lower mineralization on F-TiO2, which produced more OH, implies that the role of OH in the photocatalytic mineralization process is minor. The production of superoxide/hydroperoxyl radical (O2 −/HO2 ), which is suggested as an essential oxidant for the mineralization of phenolic pollutants, by F-TiO2 was lower than that exhibited by pure TiO2. The reduced photocurrent (I ph) generation and the enhanced H2O2 production on F-TiO2 indicate that fluorides on the TiO2 surface reduce the interfacial electron transfer rate (i.e., the production of O2 −/HO2 ) and enhance the reduction of O2 −/HO2 to H2O2. The degradation rate increased, but the mineralization efficiency decreased with increasing the surface coverage of fluorides, which depends on the pH and fluoride concentration in the solution. The reduced mineralization efficiency of other phenolic pollutants (4-chlorophenol, phenol, methylene blue, rhodamine B, and acid orange 7) was also observed on F-TiO2. This result indicates that the negative effect of surface fluorination on the mineralization of phenolic pollutants is pervasive and is not restricted to BPA.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • Synthesis of multiwall carbon nanotubes/TiO2 nanotube composites with
           enhanced photocatalytic decomposition efficiency
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1
      Author(s): Thillai Sivakumar Natarajan, Joon Yeob Lee, Hari C. Bajaj, Wan-Kuen Jo, Rajesh J. Tayade
      Multiwall carbon nanotubes (MWCNT)-loaded TiO2 nanotube (TNT) composites were synthesized by hydrothermal method. Scanning electron microscopy and transmission electron microscopy revealed the tubular morphology of the prepared TNT and MWCNT/TNT composites, which was further confirmed by the increase in their surface area. The MWCNT/TNT photocatalysts show high photocatalytic decomposition efficiency (PDE) for the degradation of rhodamine 6G (RhB-6G) dye, with excellent stability and reusability. Among the MWCNT/TNT composites, 10% loading of MWCNT results in a significantly higher PDE (89%) as compared with that of bare TNT (78%), Degussa P-25 TiO2 (P25, 60%), and TiO2 nanoparticles (56%). The enhanced PDE of MWCNT/TNT composites is due to the ability of the MWCNTs to promote the electron transfer process and reduce the electron-hole pair recombination rate, as also confirmed by photoluminescence measurements. Moreover, chemical oxygen demand (COD) and total organic carbon (TOC) analyses were performed to verify the RhB-6G dye degradation. Tubular morphology, enriched adsorption, synergic effect, and efficient separation of photogenerated electron-hole pairs account for the enhanced PDE of MWCNT/TNT composites in the decomposition of RhB-6G dye under the current experimental conditions.
      Graphical abstract image

      PubDate: 2016-11-30T04:47:36Z
       
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 15 March 2017
      Source:Catalysis Today, Volume 282, Part 1


      PubDate: 2016-11-30T04:47:36Z
       
  • The fabrication of TiO2 supported on slag-made calcium silicate as
           low-cost photocatalyst with high adsorption ability for the degradation of
           dye pollutants in water
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1
      Author(s): Jiayuan Shi, Yasutaka Kuwahara, Taicheng An, Hiromi Yamashita
      In this work, a composite photocatalyst of TiO2 supported on the slag-made calcium silicate (TiO2/SCS) was synthesized by employing a facile mixing process and using blast furnace slag as a low-cost and abundant precursor of SCS. The characterization results revealed that the open framework structure of SCS was covered by well-dispersed TiO2 nanoparticle aggregates, indicating the close combination of titania and calcium silicate in the TiO2/SCS photocatalyst. Higher specific surface areas could be obtained for TiO2/PCS (PCS: pure calcium silicate) and TiO2/SCS composites, indicating their better adsorption capabilities than that of bare TiO2. The degradation of methylene blue (MB) by TiO2, TiO2/PCS and TiO2/SCS composites with different weight percentages of titania was carried out under UV-light irradiation to systematically investigate their photocatalytic activities, and the TiO2 content of 60wt% (TiO2-60/SCS) was found to be the best one to achieve the maximum rate of MB degradation, which may be due to the high specific surface area and good adsorption capacity of the composite photocatalysts. The degradation of methyl violet (MV) and methyl orange (MO) dyes indicated that the obtained photocatalysts can effectively adsorb cationic molecules (MB and MV) but have little absorption toward negatively charged molecules (MO), which play a key role in the subsequent photocatalytic degradation of dye pollutants.
      Graphical abstract image

      PubDate: 2016-11-24T15:16:04Z
       
  • Kinetics of reduction of a resazurin-based photocatalytic activity ink
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1
      Author(s): Andrew Mills, Nathan Wells, John MacKenzie, Grant MacDonald
      The kinetics of reduction of a Resazurin, Rz, -based photocatalyst activity indicator ink, paii, on a commercial sample of self-cleaning glass, Activ™ is examined; the latter has ca. a 15nm compact coating of anatase TiO2 which serves as the active photocatalyst layer. The rate of dye reduction is reduced significantly by the presence of ambient O2. In the absence of O2, the measured change in film absorbance due to Rz, dΔAbs/dt, was found to be independent of both [Rz] and film thickness, b. It is shown that this translates to the rate of dye reduction, d[Rz]/dt, being independent of the concentration of the Rz in the ink film, [Rz], and inversely proportional to film thickness, b. The observed kinetics are rationalised in terms of a kinetic model in which the rate determining step is the reduction of photocatalyst surface-adsorbed Rz by photo-generated surface electrons, with all photocatalyst surface sites occupied by Rz. Further work suggests that, if the kinetics of the photocatalysed reduction of the Rz paii were diffusion-controlled, then the decay in [Rz] would be first order and dependent upon b −2.
      Graphical abstract image

      PubDate: 2016-11-24T15:16:04Z
       
  • Combination of coagulation-flocculation and heterogeneous photocatalysis
           for improving the removal of humic substances in real treated water from
           Agbô River (Ivory-Coast)
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1
      Author(s): Chia Yvette Prisca Ayekoe, Didier Robert, Droh Gone Lanciné
      The presence of natural organic matter (NOM) is the cause of problems in drinking water treatment processes, among which: negative effect on water color quality, poor taste and odor, enhanced biological growth in distribution systems, complexation site for heavy metals and increase in coagulant and disinfectant dose requirements, which increases potential harmful disinfection byproducts (DBPs) formation. To optimize the removal of the NOM present in drinking waters, the conventional coagulation-flocculation process was optimized and completed with heterogeneous photocatalysis. Heterogeneous photocatalytic tests were performed with TiO2-P25 suspended catalyst and TiO2-P25/β-SiC supported material. Coagulation-flocculation and heterogeneous photocatalysis have been applied individually and coupled to evaluate the best process to degrade maximum organic compounds. After each treatment, UV absorbance at 254nm (UV254nm), Specific UV Absorbance (SUVA254) and Total Organic Carbon (TOC) were measured to determine humic substances removed. The optimization of the coagulation-flocculation process conditions was obtained at pH=5 for 110mgL−1 of the coagulant dose, and 70% of humic substances were removed in these conditions. The coupling between coagulation-flocculation and supported photocatalytic process (with TiO2-P25/β-SiC supported catalyst) shows about 80% of mineralization of humic substances remaining in clarified water by coagulation-flocculation, after 220min of irradiation. Therefore about 90% of humic substances are removed with these coupled processes.
      Graphical abstract image

      PubDate: 2016-11-24T15:16:04Z
       
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1


      PubDate: 2016-11-24T15:16:04Z
       
  • Contents list
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1


      PubDate: 2016-11-24T15:16:04Z
       
  • Heterogeneous photocatalysis from fundamentals to possible applications
    • Abstract: Publication date: 1 March 2017
      Source:Catalysis Today, Volume 281, Part 1
      Author(s): Leonardo Palmisano, Vittorio Loddo, Sedat Yurdakal


      PubDate: 2016-11-24T15:16:04Z
       
 
 
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