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Journal Cover Catalysis Today
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0920-5861
     Published by Elsevier Homepage  [2566 journals]   [SJR: 1.283]   [H-I: 129]
  • Hydrocarbon oxidation over Fe- and Cr-containing metal-organic frameworks
           MIL-100 and MIL-101–a comparative study
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Oxana A. Kholdeeva , Igor Y. Skobelev , Irina D. Ivanchikova , Konstantin A. Kovalenko , Vladimir P. Fedin , Alexander B. Sorokin
      Catalytic properties of Fe- and Cr-based metal-organic frameworks (MOFs) MIL-100 and MIL-101 have been assessed in two liquid-phase reactions: solvent-free allylic oxidation of alkenes (cyclohexene, α- and β-pinenes) with molecular oxygen and oxidation of anthracene (AN) with tert-butyl hydroperoxide (TBHP). In the oxidation of alkenes, the product selectivity strongly depends on the nature of metal (Fe or Cr) but, for the same metal, only slightly differs for the MIL-100 and MIL-101 structures. The Fe-containing MOFs afford the formation of unsaturated alcohols while Cr-based MOFs give mainly unsaturated ketones. Both Cr-MIL-100 and Cr-MIL-101 favor decomposition of cyclohexenyl hydroperoxide to produce 2-cyclohexen-1-one with 67–69% selectivity. Stability toward destruction reduced in the order Cr-MIL-101, Cr-MIL-100>Fe-MIL-100>Fe-MIL-101. In the oxidation of anthracene over both Cr-MOFs and Fe-MIL-101, the selectivity toward 9,10-anthraquinone (AQ) attained 100% at 92–100% AN conversion. The turnover frequency (TOF) decreased in the order Cr-MIL-101>Fe-MIL-101>Cr-MIL-100>Fe-MIL-100. Cr-MIL-101 revealed superior catalytic performance in terms of AN conversion, AQ selectivity and TOF. Nearly quantitative yield of AQ was obtained after 1.5h at 100°C in chlorobenzene as solvent. No leaching of active metal occurred under optimal reaction conditions and the MOFs could be recycled several times without deterioration of the catalytic properties.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Understanding effects of activation-treatments in K-free and K-MoVSbO
           bronze catalysts for propane partial oxidation
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): F. Ivars-Barceló , J.M.M. Millet , T. Blasco , P. Concepción , J.S. Valente , J.M. López Nieto
      The effect of activation treatments of K-free and K-MoVSbO bronzes on either their physico-chemical characteristics or catalytic properties for propane partial oxidation have been studied. The as-synthesized materials, hydrothermally prepared and presenting (SbO)2M20O56 type structure (the so called M1-phase), were activated by different heat-treatments, characterized (XRD, SEM-EDS, HRTEM, V K-edge, Sb L1- and K-edges XANES, EPR, XPS, NH3-TPD) and tested in propane partial oxidation. In general, the selectivity to acrylic acid (the most valuable product) was higher in K-containing MoVSbO catalysts. In addition, different trend in the catalytic behavior was found between K-free and K-containing MoVSbO series, mostly related to different changes in crystalline phases distribution and catalysts surface characteristics (composition and acid properties) induced by the several activation treatments which also modified the average Sb oxidation state.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Heterogeneous selective oxidation of fatty alcohols: Oxidation of
           1-tetradecanol as a model substrate
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Vicente Cortés Corberán , Almudena Gómez-Avilés , Susana Martínez-González , Svetlana Ivanova , María I. Domínguez , María Elena González-Pérez
      Selective oxidation of fatty alcohols, i.e., linear long-chain alkanols, has been scarcely investigated to date, despite its potential application in high value chemical's production. We report for the first time the liquid phase heterogeneous oxidation of 1-tetradecanol, used as a model molecule for fatty alcohols, according to green chemistry principles by using a Au/CeO2–Al2O3 catalyst and O2 as oxidant at normal pressure. High selectivity to tetradecanal (ca. 80%) or to tetradecanoic acid (60–70%) are reached at medium conversion (up to 38%), depending on the reaction conditions used. Comparison with similar tests of 1-octanol oxidation shows that the increase of the carbon chain length decreases the alcohol conversion and the formation of ester, probably due to a greater steric effect.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Catalysis field in orthorhombic Mo3VOx oxide catalyst for the selective
           oxidation of ethane, propane and acrolein
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Satoshi Ishikawa , Xiaodong Yi , Toru Murayama , Wataru Ueda
      Orthorhombic Mo3VO x oxide catalysts in various crystal sizes with different external surface areas and the same micropore volumes were synthesized hydrothermally by adding sodium dodecyl sulphonate (SDS, C12H25SO3Na) to preparation solution and by changing synthesis temperature. The synthesized catalysts were then tested for the selective oxidations of ethane, propane, and acrolein, in order to clarity catalysis field for the reactions. It was found that ethane converted to ethene in the heptagonal channel in the structure of the catalyst and propane was also oxidized to CO x in the heptagonal channel. Acrolein, on the other hand, was converted to acrylic acid at the mouth of the heptagonal channel. It is concluded that the heptagonal channel is all responsible for the catalysis for ethane, propane, and acrolein. However, the catalysis field is different in a reflection of the molecular size of the reactants.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Oxygen activation on oxide surfaces: A perspective at the atomic level
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Hans-Joachim Freund
      Thin oxide films have been used as model supports to unravel the influence of the oxide–metal and oxide–gas interface. We discuss the influence of defects in the oxide lattice and the oxide surface on properties of adsorbed species, in particular the formation of oxide particles from a deposited transition metal onto ceria and of adsorbed oxygen from the gas phase. Here we correlate the structure of the particles, as revealed by a combination of STM and spectroscopic as well as theoretical calculations, with their reactive properties. The nature of the involved defects is characterized by adsorption of Au as a way to correlate the influence of various defects of different structure on the Au charge state. In a second case study, we demonstrate the influence of dopants within the supporting oxide on the adsorption of oxygen on a defect free surface. This is shown to be potentially relevant for the activation of methane in oxidative methane coupling reactions, as recently demonstrated.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Site isolation and phase cooperation: Two important concepts in selective
           oxidation catalysis: A retrospective
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Robert K. Grasselli
      Site isolation and phase cooperation are two important concepts in selective oxidation catalysis and are useful in the design and discovery of new catalysts. Site isolation deals with the limitation of active oxygens at the catalytic site with the aim to maximize the formation of desired selective oxygenated products and to minimize overoxidation to waste products (CO x ) [1]. Phase cooperation deals with the concept that two properly chosen phases of complimentary catalytic properties, when brought into intimate (nanoscale) contact with each other, can be made to cooperate synergistically with each other to give higher yields of desired selective oxidation products than what can be obtained by either of the two phases operating separately and independently from each other [2]. This cooperation of phases is of particular importance when all of the key catalytic functionalities cannot be incorporated into a single phase. These two principles, were first proposed and articulated by SOHIO researchers in the late 1950s and served as useful guidelines for the invention and development of selective oxidation and ammoxidation catalysts, many of which were ultimately successfully commercialized. After all these years, these concepts are still very much applicable to explain the behavior of many catalysts and remain a useful tool for the design of new catalysts in the area of selective oxidation and ammoxidation catalysis of light hydrocarbons and related fields. A retrospective and update of the site isolation and phase cooperation concepts is presented here, and includes their application to new and challenging catalytic problems facing the scientific and technological world.


      PubDate: 2014-09-14T14:11:49Z
       
  • Propane ammoxidation over Mo–V–Te–Nb–O M1 phase:
           Density functional theory study of propane oxidative dehydrogenation steps
           
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Junjun Yu , Ye Xu , Vadim V. Guliants
      Propane ammoxidation to acrylonitrile catalyzed by the bulk Mo–V–Te–Nb oxides has received considerable attention because it is more environmentally benign than the current process of propylene ammoxidation and relies on a more abundant feedstock. This process is proposed to consist of a series of elementary steps including propane oxidative dehydrogenation (ODH), ammonia and O2 activation, NH x insertion into C3 surface intermediates, etc. Density functional theory calculations were performed here to investigate the three sequential H abstraction steps that successively convert propane into isopropyl, propene, and π-allyl on cation sites in the proposed selective and active center present in the ab plane of the Mo–V–Te–Nb–O M1 phase. The initial H abstraction from propane was found to be the rate-limiting step of this process, consistent with both the proposed reaction mechanism for propane ammoxidation on the Mo–V–Te–Nb oxides and current understanding of V5+ as the active site for alkane activation on V-based oxides. Te=O was found to be significantly more active than V5+=O for the H abstraction from propane, which suggests that the surface and bulk Te species may be different. The role of Mo=O is most likely limited to being an H acceptor from isopropyl to form propene under ammoxidation conditions.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Thermal transformations of 2-chlorophenol on a surface of ZnO powder
           catalyst
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Jia Gao , Andrew V. Teplyakov
      Catalytic transformation of multifunctional molecules requires understanding of the competing reactions on a surface of a heterogeneous catalyst. Here the reaction of 2-chlorophenol is investigated with ZnO powder that has a potential to be used in environmental remediation. Since it is important to follow every step of surface-catalyzed processes, adsorption and thermally induced transformations of 2-chlorophenol on ZnO powder catalyst were followed by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and supplemented by density functional theory (DFT) investigations. The room temperature adsorption FTIR results show that O–H dissociation is the primary reaction pathway. Room temperature adsorption studies followed by in situ thermal annealing to desired temperature and then quenching back to room temperature followed by XPS prove that C–Cl dissociation in 2-chlorophenol is competing with the O–H dissociation process on ZnO; however, the majority of chlorine is still bound to carbon and can only be removed by thermal annealing together with the phenyl group. DFT description helps to construct the reaction mechanism diagram and O–H dissociation is found to have a reaction barrier of only 62.4kJ/mol, while C–Cl bond dissociation has a substantially higher barrier of 111.2kJ/mol. Thus, this set of studies suggests that the reaction of 2-chlorophenol on ZnO powder proceeds selectively towards the O–H dissociation; however, the products released from its surface following thermal annealing contain chlorinated hydrocarbon fragments. This observation implies that it would be difficult to use unmodified ZnO as a catalyst for a direct utilization and mineralization of chlorophenols.
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      PubDate: 2014-09-14T14:11:49Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238




      PubDate: 2014-09-14T14:11:49Z
       
  • Contents list
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238




      PubDate: 2014-09-14T14:11:49Z
       
  • Preface
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238




      PubDate: 2014-09-14T14:11:49Z
       
  • Conversion of ethanol to hydrocarbons on hierarchical HZSM-5 zeolites
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Karthikeyan K. Ramasamy , He Zhang , Junming Sun , Yong Wang
      This study reports synthesis, characterization, and catalytic activity of the nano-size hierarchical HZSM-5 zeolite with high mesoporosity produced via a solvent evaporation procedure. Further, this study compares hierarchical zeolites with conventional HZSM-5 zeolite with similar Si/Al ratios for the ethanol-to-hydrocarbon conversion process. The catalytic performance of the hierarchical and conventional zeolites was evaluated using a fixed-bed reactor at 360°C, 300psig, and a weight hourly space velocity of 7.9h−1. For the low Si/Al ratio zeolite (∼40), the catalytic life-time for the hierarchical HZSM-5 was approximately 2 times greater than the conventional HZSM-5 despite its coking amount deposited 1.6 times higher than conventional HZSM-5. For the high Si/Al ratio zeolite (∼140), the catalytic life-time for the hierarchical zeolite was approximately 5 times greater than the conventional zeolite and the amount of coking deposited was 2.1 times higher. Correlation was observed between catalyst life time, porosity, and the crystal size of the zeolite. The nano-size hierarchical HZSM-5 zeolites containing mesoporosity demonstrated improved catalyst life-time compared to the conventional catalyst due to faster removal of products, shorter diffusion path length, and the migration of the coke deposits to the external surface from the pore structure.
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      PubDate: 2014-09-14T14:11:49Z
       
  • New molecular basket sorbents for CO2 capture based on mesoporous
           sponge-like TUD-1
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Xiaoxing Wang , Chunshan Song , Anne M. Gaffney , Ruozhi Song
      In this work, a new class of mesoporous and sponge-like TUD-1 materials have been explored as the support matrix for immobilizing a functional polymer, polyethylenimine (PEI), to prepare molecular basket sorbents (MBS) for CO2 capture. The performance of TUD-1 based MBS has been evaluated in a fixed-bed flow system using a simulated flue gas. Effects of the pore properties, PEI loading amount and moisture on the sorption capacity were examined. Compared to the well-known SBA-15, the TUD-1 based nano-porous MBS showed not only a comparable gravimetric capacity (∼115mg-CO2/g-sorb), but also a significantly higher volumetric capacity (as high as 68mg-CO2/mL-sorb). Both the pore volume and pore size play a crucial role in determining the CO2 sorption capacity of the TUD-1 based MBS. Furthermore, the TUD-1 supported PEI samples exhibited faster CO2 sorption kinetics than SBA-15 based MBS, due likely to the improved CO2 diffusion constant which was estimated by Parabolic diffusion equation. The highest CO2 sorption capacity of 116mg-CO2/g-sorb was obtained with PEI loading of 50wt% at 75°C under dry conditions, which was further enhanced to 130mg-CO2/g-sorb in the presence of moisture (3vol%). The PEI/TUD-1 sorbent was tested for 45 sorption–desorption cycles, showing a good regenerability and cyclic stability. Because of its high CO2 sorption performance and commercial availability of the support, the TUD-1 based MBS could be promising for cost-effective capture of CO2 from flue gas.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Perspectives of spray pyrolysis for facile synthesis of catalysts and thin
           films: An introduction and summary of recent directions
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Curtis Guild , Sourav Biswas , Yongtao Meng , Tahereh Jafari , Anne M. Gaffney , Steven L. Suib
      In the modern technological world, applications are rapidly demanding homogeneous, reproducible, scalable processes for films and catalytic surfaces. The uses of spray pyrolytic methods for fabricating these films have received attention since the late 1980s, and today spray pyrolysis finds use in a variety of applications, ranging from biomedical to industrial, microelectronics to ceramics. In this review, basic parameters of spray pyrolysis for catalytic and thin film formation are summarized, while recent developments in spray deposition for environmental remediation, photovoltaics, fuel cell and battery materials, biomedical applications, and microelectronics are also discussed.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Stabilization of active sites in alloyed Pd–Rh catalysts on
           γ-Al2O3 support
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Aleksey A. Vedyagin , Alexander M. Volodin , Vladimir O. Stoyanovskii , Roman M. Kenzhin , Elena M. Slavinskaya , Ilya V. Mishakov , Pavel E. Plyusnin , Yury V. Shubin
      Active components for three-way catalysts containing alloyed Pd–Rh particles with the concentration of the components 0.12 and 0.08wt.%, respectively, were synthesized and studied. The properties of these materials were compared with those of supported catalysts containing one or two precious metals (PM) prepared by mechanical mixing of the components with the same concentrations of PM. The stability of the samples was estimated by in situ prompt thermal aging (PTA) procedure. Photoluminescence (PL) and electron paramagnetic resonance (EPR) were used to show the importance of intrinsic sites of the support in stabilization of single-metal and alloyed Pd-containing clusters with high catalytic activity in CO oxidation. Substantial mutual effect of Pd and Rh in the alloyed particles was revealed. It prevents Pd-containing particles from sintering and hinders diffusion of Rh3+ ions into the bulk of the support at high temperatures. The spin probe technique was used to demonstrate that the alloy formation permits one to improve significantly the catalyst stability to reduction.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Selective oxidation of hydrocarbons on supported Au catalysts
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Neema A. Mashayekhi , Mayfair C. Kung , Harold H. Kung
      The importance of proximity of isolated TiO x cluster to Au surface for the formation of acetone in the selective oxidation of propane was investigated using a model system of Au particles decorated with mononuclear TiO x units dispersed in silica clusters. The results showed that no acetone was formed without TiO x , and its formation was more prominent on a sample containing a higher density of TiO x . Covering a Au/TiO2 catalyst with a layer of TiO x -containing silica changed the product selectivity from predominently propene to acetone. The data strongly supported the importance of isolated TiO x clusters near the Au surface in acetone formation, and suggested the relevance of Au-TiO x interface sites. Such interface sites might also be important in selective propene epoxidation that was coupled to CO oxidation in a H2O-methanol mixture. Using oxygen isotope labeling technique, it was found that the proximal source of oxygen in propene oxide was not from H2O but from O2. The observation was consistent with a methyl hydroperoxide intermediate, which could be formed by oxidation of a Ti methoxy at the Au-support interface.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Selective oxidation using supported gold bimetallic and trimetallic
           nanoparticles
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): Graham J. Hutchings
      Supported gold nanoparticles are highly effective for a range of redox reactions. In these reactions the activity is often enhanced by the addition of a second or indeed a third metallic component. A model reaction that is often investigated is the selective oxidation of benzyl alcohol using molecular oxygen as terminal oxidant. In the presence of a solvent the complexity of this reaction can often be missed. However, in the solvent-free oxidation of benzyl alcohol to benzaldehyde using supported gold palladium nanoparticles as catalysts, there are two pathways to the principal product, benzaldehyde. One is the direct catalytic oxidation of benzyl alcohol to benzaldehyde by O2, while the second is the disproportionation of two molecules of benzyl alcohol to give equal amounts of benzaldehyde and toluene. The formation of toluene is an unwanted side reaction. In this paper the research on this reaction will be reviewed and two strategies described that can be used to switch off the formation of the non desired toluene. The first involves the use of basic supports for the gold palladium nanoparticles, which is highly effective in suppressing the formation of toluene and this may be related to the morphology of the gold palladium nanoparticles and their interaction with the support. The second involves the introduction of platinum to the gold palladium nanoparticles which also switches off toluene formation on supports that permit toluene formation in the absence of platinum. This effect may be related to the relative stability of platinum hydride.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen
           sulfide
    • Abstract: Publication date: December 2014
      Source:Catalysis Today, Volume 238
      Author(s): M.D. Soriano , E. Rodríguez-Castellón , E. García-González , J.M. López Nieto
      Na-containing V2O5 materials have been prepared hydrothermally from gels with Na/V ratios of 0.02–0.26, and calcined at 500°C. The calcined samples have been characterized and tested as catalysts in the partial oxidation of H2S to elemental sulfur. At low Na-contents, V2O5 and NaV6O15 bronze are formed, with the NaV6O15/V2O5 ratio increasing with the Na-content. Pure NaV6O15 bronze is mainly formed from gels containing a Na/V ratio of 0.18. However, NaV6O15 and Na1.164V3O8 are formed from gels with Na/V ratio higher than 0.35. NaV6O15 based catalyst shows high conversion for the oxidation of H2S with a high selectivity into elemental sulfur. These catalysts are more active and stable than pure or Na-doped V2O5 catalysts. V4O9 is observed after reaction in both pure Na-doped V2O5 catalysts but also in NaV6O15/V2O5 mixed catalysts. However, no changes in the NaV6O15 crystalline structure are observed in the Na-promoted catalysts. Accordingly, NaV6O15 crystalline phase is stable for several hours of catalysis at a difference with V2O5. The active sites in V-containing vanadium catalysts are probably V5+ OV4+ pairs as previously proposed for V4O9 crystalline phase. The best catalytic performances were achieved on V2O5 NaV6O15 mixtures which are transformed into V4O9 NaV6O15 mixtures during the catalytic tests. These catalytic results could be due to the intrinsic physical properties of both phases but also because of the optimal dispersion obtained in the synthesis procedure.
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      PubDate: 2014-09-14T14:11:49Z
       
  • Glycerol conversion in the presence of carbon dioxide on alumina supported
           nickel catalyst
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Pedro P. Florez-Rodriguez , Aracelis J. Pamphile-Adrián , Fabio B. Passos
      The glycerol conversion in the presence of carbon dioxide was investigated on a Ni/γ-Al2O3 catalyst. The catalyst was characterized by XRD, TPR, BET, XPS, H2-TPD, DRIFTS and Raman. A catalyst preparation method using ethylene glycol and a reduction passivation procedure provided an active catalyst. For the different catalytic runs in a batch reactor, a higher formation of hydrocarbons, alcohols, ketones, and furans was observed when the mass of catalyst was increased. For temperatures below 200°C, both glycerol and CO2 were converted, suggesting a potential route for glycerol valorization and CO2 sequestration, with the consequent production of oxirane, alcohols, ketones and carboxylic acids. For higher temperatures, there was the formation of a wide range of low yield products, with higher yields to ketones, alcohols and esters.
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      PubDate: 2014-09-10T13:57:30Z
       
  • Biodiesel synthesis from acid oil over large pore sulfonic acid-modified
           mesostructured SBA-15: Process optimization and reaction kinetics
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Krunal A. Shah , Jigisha K. Parikh , Kalpana C. Maheria
      Biodiesel synthesis from acid oil (AO) containing high free fatty acids (FFA) over pore expanded sulfonic acid functionalized mesostructured SBA-15 was studied. Reaction parameters affecting the FAME yield were optimized using Taguchi design. 99% FFA conversion was obtained under optimum conditions viz. at 100°C with 4wt.% catalyst amount and 1:15 oil to methanol ratio after 8h. Kinetic study revealed that the reaction followed pseudo first order kinetic law.
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      PubDate: 2014-09-10T13:57:30Z
       
  • Esterification of levulinic acid with ethanol over sulfated mesoporous
           zirconosilicates: Influences of the preparation conditions on the
           structural properties and catalytic performances
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Yasutaka Kuwahara , Tadahiro Fujitani , Hiromi Yamashita
      Levulinic acid is considered one of the most important biomass-derived chemicals owing to its potential as a versatile building block to synthesize valuable fuels and chemicals. Levulinate esters, such as methyl levulinate and ethyl levulinate obtained via esterification of levulinic acid with alcohols, can in particular be used as fuel additives and plasticizers, and thus have a potential to replace a significant amount of petroleum-derived chemical feedstocks. In this article, sulfated zirconosilicates having P6mm hexagonal mesoporous structure were applied as solid acid catalysts to the esterification of levulinic acid with ethanol to produce ethyl levulinate, and the influences of preparation conditions on the structural properties and catalytic performances were investigated. A distinct correlation was observed between the catalytic activity and the density of acid sites, showing that dispersibility of the acid sites and the associated accessibility of the organic reactants play an important role in determining the overall activity. Among the catalysts tested, sulfated Zr–SBA-15 with optimum Zr content (Si/Zr ratio of 10.7) was found to be the best catalyst, the activity of which was far superior to that of conventional sulfated ZrO2. In addition, direct conversion of cellulosic sugars (glucose and fructose) into levulinate esters was also examined.
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      PubDate: 2014-09-10T13:57:30Z
       
  • Biofuel synthesis in a capillary fluidized bed
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): D.C. Boffito , C. Neagoe , M. Edake , B. Pastor-Ramirez , G.S. Patience
      Hydrotalcite, MgO, CaO and zeolites transesterify canola oil in the gas phase at temperatures above 300°C and atmospheric pressure. Syringe pumps metered oil and alcohol through a 1/8″ tube to the bottom of a 7mm “capillary”-fluidized bed. Argon gas entered the annular region of the bed through a sintered glass frit as supplemental fluidizing gas. Oil conversion was complete with excess methanol in the feed. Contact times were less than 0.3s and the weight-hourly space velocity was on the order of 15h−1 (0.15mlmin−1 oil feed rate with 0.5g of catalyst). As the catalyst deactivates, the oil condenses and the fluidized bed collapses. The zeolite deactivated within 2min; the hydrotalcite could operate for several minutes; the CaO and MgO operated without interruption for well over 20min. Periodic oxidation of the catalyst maintained catalyst activity.
      Graphical abstract image Highlights

      PubDate: 2014-09-10T13:57:30Z
       
  • Production of biodiesel from unrefined canola oil using mesoporous
           sulfated Ti-SBA-15 catalyst
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Rajesh V. Sharma , Chinmoy Baroi , Ajay K. Dalai
      The present study deals with the synthesis of mesoporous sulfated Ti-SBA-15 (with Si/Ti ratio varying from 10 to 80) and these catalysts were used for preparation of biodiesel from unrefined canola oil. The physico-chemical properties of the catalyst were analyzed by FT-IR, pyridine FT-IR, N2 adsorption–desorption isotherm, X-ray diffraction analysis (XRD), X-ray absorption near edge spectroscopy (XANES), NH3-temperature programmed desorption (TPD), Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy. It was observed that the sulfation of Ti-SBA-15 increases the extent of transesterification by fourfold. Taguchi methodology (L9 orthogonal array) was used to optimize the reaction parameters such as temperature, methanol to oil molar ratio, catalyst loading and reaction time towards methyl ester (biodiesel) formation through simultaneous esterification and transesterification reaction. Reaction time and temperature were found to be the most significant reaction parameters. In this study, 1wt% catalyst yielded 91wt% ester in 4h when 15:1 methanol to oil molar ratio was used at 200°C. The catalyst was found to be reusable when studied upto 3 cycles.
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      PubDate: 2014-09-10T13:57:30Z
       
  • Contents list
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237




      PubDate: 2014-09-10T13:57:30Z
       
  • Preface for the special Issue: Sustainable Fuels and Chemicals
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Ajay K. Dalai , Yong Wang



      PubDate: 2014-09-10T13:57:30Z
       
  • In situ XANES study of methanol decomposition and partial oxidation to
           syn-gas over supported Pt catalyst on SrTiO3 nanocubes
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Hui Wang , Junling Lu , Christopher L. Marshall , Jeffrey W. Elam , Jeffrey T. Miller , HongBo Liu , James A. Enterkin , Robert M. Kennedy , Peter C. Stair , Kenneth R. Poeppelmeier , Laurence D. Marks
      A catalyst of Pt nanoparticles was prepared by atomic layer deposition on SrTiO3 nanocuboids and tested for methanol decomposition and partial oxidation. The catalyst had uniform nanoparticle size of 1.58±0.37nm and a Pt (111) surface. In situ X-ray absorption near-edge spectroscopy (XANES) measured in a temperature-programmed reduction showed that the Pt particles were easily reduced. However, the as-received catalyst, a reduced catalyst, and an oxidized catalyst all had catalytic activity, differing slightly in methanol conversion and product selectivity. In situ XANES also revealed that CO adsorbed on the Pt sites was the only observed surface species during both methanol decomposition and partial oxidation. It seemed that the breakage of CH and OH bonds overwhelmingly occurred once methanol was adsorbed, forming H2 and adsorbed CO. The latter was then released from the catalyst surface or was oxidized to CO2 when O2 was present.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Generation of syngas through autothermal partial oxidation of glycerol
           over LaMnO3- and LaNiO3-coated monoliths
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Shih-Kang Liu , Yu-Chuan Lin
      This study presents a side-by-side comparison of LaMnO3 and LaNiO3 perovskites in the autothermal partial oxidation of glycerol to syngas. Pure glycerol and glycerol/water solutions were converted to syngas under adiabatic conditions. The addition of water suppressed glycerol conversion and reaction temperature, but increased H2 selectivity with the appropriate steam-to-glycerol feed ratio. Catalytic results show that LaMnO3 is more active than LaNiO3 in autothermal partial oxidation because of its combustion-prone nature. In contrast, LaNiO3 produced higher H2 selectivity than LaMnO3 did. A comparative study of LaMnO3 and LaNiO3 in glycerol steam reforming and water-gas shift was performed as well to reveal how these H2-production reactions proceed in the oxygen-deficient regime of a catalyst bed. The outcomes indicate that LaNiO3 is more active than LaMnO3 in these two reactions, thereby enhancing H2 selectivity in a partial oxidation system. Moreover, a 24-h lifetime test of these two perovskites was conducted, showing that LaMnO3 has greater durability.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Selective mono-isopropylation of 1,3-propanediol with isopropyl alcohol
           using heteropoly acid supported on K-10 clay catalyst
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Ganapati D. Yadav , Devendra P. Tekale
      Catalytic hydrogenolysis/hydrogenation of bioglycerol leads to 1,2 and 1,3-propanediols, which can be further valorized to industrially important products through a variety of reactions such as etherification, esterification and cyclization through acetalization. In the current work, selective mono-etherification of 1,3-propanediol (PDO) with isopropanol to 3-isopropyl-1-propanaol was systematically studied, using 20% w/w Cs2.5H0.5PW12O40/K-10 catalyst in an autoclave at 170°C. In a typical reaction, using 1:6mol ratio of 1,3-PDO to isopropanol at 0.03g/cm3 catalyst loading and 1000rpm, 60% conversion was achieved with 100% selectivity to the product. The catalyst was prepared by incipient wetness technique and characterized by various techniques such as X-ray diffraction, surface area measurement by N2 adsorption–desorption, FTIR, and SEM. Effect of various reaction parameters on conversion and selectivity was studied to establish kinetics and mechanism. The catalyst is robust and reusable. The overall process is green and clean.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Reaction of glyceraldehyde and glucose on Zn-modified Pt(111) surfaces
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Jesse R. McManus , Eddie Martono , John M. Vohs
      The high oxygen content and multiple functional groups in biomass-derived platform molecules like glucose provide a major challenge in biomass conversion to value-added fuels and chemicals. Understanding the role of multiple functionalities in the reaction on catalytically relevant surfaces, particularly with regard to deoxygenation chemistry, is paramount. In this study, temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) were utilized to identify the role of the multiple functionalities of glucose and model aldose glyceraldehyde in their reactions on Pt(111) and Zn-modified Pt(111) surfaces. Comparisons were drawn to similar data for model molecules acetaldehyde and glycolaldehyde. For all four molecules, dehydrogenation to form an acyl intermediate, followed by decarbonylation to form CO and H2 occurred on Pt(111). Also, with all molecules studied, addition of Zn to the Pt(111) surface caused an increase in the barrier for C–H and C–C bond scission resulting in stabilization of surface intermediates to much higher temperatures than on Pt(111). The Zn/Pt(111) surface was additionally found to be active for alcohol dissociation to form Zn-bound alkoxides, and in the case of polyols glyceraldehyde and glucose, these multiple alkoxide bonds geometrically prevented the η2(C,O) aldehyde bonding configuration and subsequent carbonyl deoxygenation that was observed with smaller C2 molecules acetaldehyde and glycolaldehyde. These results help elucidate the role of multiple alcohol functionalities in biomass-derived oxygenates in the reaction over catalytically relevant surfaces, and highlight the potential of using alloy effects (such as Zn-modification of Pt shown herein) to modify catalytic chemistry.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Nano-iron carbide synthesized by plasma as catalyst for
           Fischer–Tropsch synthesis in slurry reactors: The role of iron
           loading and K, Cu promoters
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Jasmin Blanchard , Nicolas Abatzoglou
      Nano-iron carbides (NFeC), generated by a plasma spray technique, were used as-produced and promoted with potassium (K) and copper (Cu) in Fischer–Tropsch synthesis (FTS) in a 3-φ continuously stirred tank slurry reactor. NFeC particles were initially encapsulated in a carbon matrix to protect them from air-borne oxidation. This matrix was partially removed under reductive conditions as a pre-treatment of subsequent FTS reactions. Cu and K promoters were added to the catalyst by mixing Cu metallic powder and/or K2CO3 powder with iron–oil suspension fed to the plasma. The reactants simulated the composition of synthesis gas produced by urban biomass gasification. At-line gas chromatography of the more volatile products and global liquid product analyses by micro-distillation provided the necessary data for mass balance, conversion and selectivity estimations. Also, an appropriate algorithm successfully estimated the ratio of FTS over water–gas shift (WGS) reactions extents. The results disclosed that this nano-powder, characterized by very low internal porosity, generated a liquid fuel that was lighter than other commercial catalysts under similar reaction severities but at a significantly lower catalyst load (9% of the mass of liquid). Increased catalyst loading in the slurry above a critical limit led to higher product water hold-up and, consequently, higher rates of catalyst deactivation. Conversion, selectivity and the Anderson–Schulz–Flory distribution probability of chain growth “α” were compiled and reported. Tests with Cu- and K-promoted catalysts showed a highly significant decrease of the catalyst deactivation rate, with CO and H2 conversion increasing respectively to 82% and 44% from 35% and 30% obtained with no-doped catalyst. Moreover, CH4 yield was reduced to 4.7% from 12%, and the WGS rate tripled. Finally, the absence of internal porosity in the catalyst facilitated the definition of process-operating conditions in which surface reaction kinetics was the controlling step.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Enzymatic glycerolysis for conversion of sunflower oil to food based
           emulsifiers
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Malaya K. Naik , S.N. Naik , Sanat Mohanty
      High temperature glycerolysis widely used in industrial scale for production of food-based emulsifiers has many disadvantages. On the other hand, high cost, unavailability, low activity and high reaction time of enzymes limit the use in industrial scale glycerolysis reactions for the production of food-based emulsifiers (i.e. monoglycerides). The goal of this project is to develop an efficient and optimal glycerolysis process for production of monoglycerides. This study found that optimal production through enzymatic glycerolysis was achieved with 15wt% loading of Fermase CALB 10000 and oil to glycerol molar ratio was optimized at 1:5. A tert-butyl alcohol system was developed carefully with evaluation of more than 10 organic solvents. The suitable co-solvent addition was 1:50 molar ratio with respect to oil. In the above-optimized condition, the conversion of monoglyceride was 50–60% at 2–3h and 70–80% at 5 to 6h of reaction time. The reaction time was optimized at 5h. Subsequent to the following reaction was found that, there is no drastic reduction of enzyme activity and could be reused for next reaction. Due to this behaviour, we recommend Fermase 10000 as an effective and low cost enzyme for future glycerolysis reaction in industrial scale.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Catalytic deoxygenation of triglycerides and fatty acids to hydrocarbons
           over Ni–Al layered double hydroxide
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Eduardo Santillan-Jimenez , Tonya Morgan , Jaime Shoup , Anne E. Harman-Ware , Mark Crocker
      The conversion of fatty acids and triglycerides to fuel-like hydrocarbons was investigated over a Ni–Al layered double hydroxide catalyst and over 20% Ni/Al2O3 for comparison purposes. Both catalytic performance and the extent of catalyst fouling were found to show a marked dependence on the hydrogen partial pressure used during reaction and on the Ni-specific surface area of the catalyst employed. The amenability of a representative spent catalyst to regeneration via calcination in air was also demonstrated. The regenerated catalyst was observed to outperform the fresh formulation when tested for activity in the conversion of lipids to fuel-like hydrocarbons. This is attributed to the formation of strong basic sites – which are capable of catalyzing the deoxygenation of lipids – during the regeneration process. The fact that inexpensive Ni-based catalysts capable of affording good yields of fuel-like hydrocarbons can be regenerated by treatment in hot air makes these formulations interesting from an industrial standpoint. Results suggest that the conversion of triglycerides to fuel-like hydrocarbons is intermediated by fatty acids and that the conversion of fatty acids – either as the reaction feed or as reaction intermediates – to hydrocarbons proceeds via aldehyde and/or fatty acid ester intermediates.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Selective acetalization of ethylene glycol with methyl 2-napthyl ketone
           over solid acids: Efficacy of acidic clay supported Cs2.5H0.5PW12O40
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Ganapati D. Yadav , Suraj O. Katole
      Catalytic conversion of biomass to value added products is relevant with regard to several industries. Biomass derived ethylene glycol has many applications. Acetalization is used to synthesize valuable chemicals and also occasionally to protect carbonyl groups of aromatic molecules in organic transformations. Acetalization of ethylene glycol to cyclic dioxolane has many applications in fragrance, cosmetics, food and beverage additives, pharmaceuticals, detergents, and lacquer industries. The current work reports synthesis of 2-methyl-2-napthyl-1,3-dioxolane by acetalization of ethylene glycol with methyl 2-napthyl ketone using several heterogeneous solid acid catalysts including 20% (w/w) Cs2.5H0.5PW12O40/K-10 (Cs-DTP/K-10), UDCaT-4, UDCaT-5 and K-10 clay. Among them, 20% (w/w) Cs-DTP/K-10 catalyst was found to be the most efficient catalyst giving 87% conversion of methyl 2-napthyl ketone with 100% selectivity toward 2-methyl-2-napthyl-1,3-dioxolane. Effects of several reaction parameters were studied and optimized. The optimum reaction conditions were: 110°C, molar ratio of methyl 2-naphthyl ketone to ethylene glycol 1:2, catalyst loading 0.02g/cm3, speed of agitation 800rpm, and time 3h. Reaction mechanism and kinetic model were developed. The methodology was extended to different substrates, and catalyst reusability was also studied. The catalyst was well characterized by various techniques such as XRD, BET, FTIR, TPD and SEM. It is robust and recyclable.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • A green process for glycerol valorization to glycerol carbonate over
           heterogeneous hydrotalcite catalyst
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Ganapati D. Yadav , Payal A. Chandan
      Biodiesel production is accompanied by 10% w/w glycerol which needs to be valorized to into bulk and specialty chemicals in order to make the biodiesel economics favorable. Glycerol carbonate is one such product from glycerol which has many potential applications. A green process using calcined hydrotalcite supported on hexagonal silica (CHT-HMS) catalyst was developed for the conversion of glycerol to glycerol carbonate using dimethyl carbonate. Effects of various Al:Mg composition and loading on hexagonal mesoporous silica (HMS) were studied. Al:Mg composition of 1:2 with 15% w/w loading on HMS was the best catalyst. . CHT-HMS catalyst was fully characterized by various techniques such as FT-IR, EDAX, SEM, TPD, XRD, etc. The effects of various parameters such as speed of agitation, catalyst concentration, mole ratio, and temperature were studied. The catalyst is robust and recyclable. The reaction follows Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism with weak adsoption of all species. Thus, a second order rate equation for the reaction was developed and the activation energy estimated.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Role of tungsten in the aqueous phase hydrodeoxygenation of ethylene
           glycol on tungstated zirconia supported palladium
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Oscar G. Marin-Flores , Ayman M. Karim , Yong Wang
      The focus of the present work was specifically on the elucidation of the role played by tungsten on the catalytic activity and selectivity of tungstated zirconia supported palladium (Pd-mWZ) for the aqueous phase hydrodeoxygenation (APHDO) of ethylene glycol (EG). Zirconia supported palladium (Pd-mZ) was used as reference. The catalysts were prepared via incipient wet impregnation and characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR), CO pulse chemisorption, CO-DRIFTS, ammonia temperature-programmed desorption (NH3-TPD) and pyridine adsorption. The presence of W results in larger Pd particles on supported Pd catalysts, i.e., 0.9 and 6.1nm Pd particles are for Pd-mZ and Pd-mWZ, respectively. The catalytic activity measurements show that the overall intrinsic activity of Pd particles on mWZ is 1.9 times higher than on mZ. APHDO process appears to be highly favored on Pd-mWZ whereas Pd-mZ exhibits a higher selectivity for reforming. This difference in terms of selectivity seems to be related to the high concentration of Brønsted acid sites and electron-deficient Pd species present on Pd-mWZ.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • A novel development of mixed catalyst–sorbent pellets for steam
           gasification of coal chars with in situ CO2 capture
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Ehsan Mostafavi , Nader Mahinpey , Vasilije Manovic
      The main purpose of this research was the development of a mixed catalyst–sorbent for gasification and in situ CO2 capture; therefore, novel mixed catalyst–sorbent (composite) pellets were prepared with different contents of potassium carbonate and calcium oxide as the catalyst and sorbent, respectively. The pellets were used in steam gasification experiments of two different types of coal. The maximum hydrogen yield of 80% was obtained with 50% of the catalyst in the composite pellets and lignite Boundary Dam (BD) coal at 700°C. Use of the catalyst enhanced the gasification and water–gas shift (WGS) reaction rates, while the capture of carbon dioxide (CO2) shifted the WGS equilibrium forward, favoring hydrogen production. Trace amounts of CO2 and carbon monoxide were detected. In terms of maximum achievable hydrogen yield, the pellets containing 50% catalyst demonstrated the best performance. As expected, BD coal (a low-rank coal) showed a higher reactivity than the Genesee sub-bituminous (a medium-rank coal) samples. Ultimate analyses and burn-off tests were performed on the residues to determine the amounts of unconverted carbon, and the results of these tests also confirmed the best performance of the pellets with a catalyst content of 50%. Despite the decreasing trend of pore surface area with increasing catalyst percentage, increasing the catalyst content of composite pellets to a certain level had a positive effect on hydrogen production. This indicates that the performance of pellets is almost independent of the pore surface area. Indeed, the optimal ratio is the result of the trade-off among pore surface area, dispersion, formation of a bimetallic solid phase, and the concentration of active catalyst sites on the pellets.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Ni catalysts for steam gasification of biomass: Effect of La2O3 loading
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Jahirul Mazumder , Hugo I. de Lasa
      La2O3 promoted Ni/γ-Al2O3 fluidizable catalysts are studied for the steam gasification of a cellulose surrogate (glucose) and a lignin surrogate (2-methoxy-4-methylphenol) in a CREC Riser Simulator. Two γ-Al2O3 are considered as the support for an active and stable Ni catalyst. La2O3 modified supports and catalysts are characterized using BET specific surface area, XRD, TPR, TPO, and H2-pulse chemisorption. Pyridine FTIR, NH3-TPD and CO2-TPD are employed to establish the effect of La2O3 on the aciditiy-basicity of the alumina used. It is shown that increasing the La2O3 up to 5wt% improves the BET surface area and the CO2 adsorption capacity, as well as reduces support acidity. XRD results revealed the formation of undesirable LaAlO3 on the Ni catalyst containing 10wt% La2O3.The 10wt% La2O3 also favors the formation of larger Ni crystallites which are susceptible to coking. In agreement with this, the catalyst containing 10wt% La2O3 gives lower dry gas yields and carbon conversions, as well as yields higher coking than the catalyst supported on alumina with 5wt% La2O3. On the other hand, catalysts supported on Sasol γ-Al2O3 display higher surface area, Ni reducibility and dispersion, and CO2 adsorption capacity than the Alcan γ-Al2O3 supported catalysts. The addition of 5wt% La2O3 further enhances both the structural properties and the reactivity of Ni/Sasol γ-Al2O3 catalyst. In particular, catalytic gasification using 20% Ni on a 5% La2O3-Sasol γ-Al2O3 catalyst shows promising glucose and 2-methoxy-4-methylphenol conversions to a high-quality synthesis gas at only 650°C. This catalyst yields a 95% carbon conversion of glucose to permanent gases with no tar formation and negligible coke deposition; whereas a 81% carbon conversion with only 10.5wt% tars is achieved from 2-methoxy-4-methylphenol gasification.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Ethanol conversion to hydrocarbons on HZSM-5: Effect of reaction
           conditions and Si/Al ratio on the product distributions
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Karthikeyan K. Ramasamy , Yong Wang
      The Conversion of ethanol to hydrocarbon over HZSM-5 zeolite with different Si/Al ratios was investigated under various reaction conditions. The catalyst with a higher Si/Al ratio (low acid density) deactivated faster and generated more unsaturated compounds at a similar time-on-stream. Temperature affects the catalytic activity with respect to liquid hydrocarbon generation and the hydrocarbon product composition. At lower temperatures (∼300°C), the catalyst deactivated faster with respect to the liquid hydrocarbon formation. Higher temperatures (∼400°C) reduced the formation of liquid range hydrocarbons and formed more gaseous fractions. Weight hourly space velocity was also found to affect product selectivity with higher weight hourly space velocity leading to a higher extent of ethylene formation. The experimental results were analyzed in terms of the product composition and the coke content with respect to catalyst time-on-stream and compared with the catalyst lifetime with respect to the variables tested on the conversion of ethanol to hydrocarbon.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • Production of hydrogen by steam reforming of ethanol over alumina
           supported nano-NiO/SiO2 catalyst
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237
      Author(s): Barnali Bej , Narayan C. Pradhan , Swati Neogi
      The production of hydrogen by catalytic steam reforming of ethanol was carried out over alumina supported nano NiO catalyst in silica synthesized using sol–gel method. The catalyst was characterized using SEM, TEM and BET surface area analyzer. The performance of the catalyst in ethanol reforming was investigated using three important operating parameters such as reaction temperature, feed steam to ethanol ratio and space-time. The activity tests were performed in the steam to ethanol molar ratio range of 2:1 to 9:1 and space-time from 2.78 to 9.25kgcatalysthkmol−1 of ethanol fed and in the temperature range of 550 to 700°C. A maximum yield of 4.2mol of hydrogen per mole of ethanol reacted were produced at 650°C. A favorable operating condition was established at 650°C using 8:1 steam to ethanol molar ratio and a space-time of 9.25kgcatalysthkmol−1 of ethanol fed. Under these operating conditions, ethanol conversion, product composition and H2 yield were studied to see the contributions of water–gas shift reaction, ethanol cracking, methane steam reforming and also reverse water–gas shift reaction towards the yield of hydrogen. The kinetic study was performed over a wide range of space-time at different temperatures under negligible diffusional resistance. A power-law model rate equation was derived with acquired experimental data. The kinetic parameter and order of reaction were estimated by non-linear regression method. The activation energy was calculated to be 27kJmol−1. A good agreement was obtained between experimental and model predicted results.
      Graphical abstract image

      PubDate: 2014-09-10T13:57:30Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 15 November 2014
      Source:Catalysis Today, Volume 237




      PubDate: 2014-09-10T13:57:30Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part B




      PubDate: 2014-08-18T16:03:27Z
       
  • Zeolites and mesoporous materials in fuel cell applications
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part B
      Author(s): King Lun Yeung , Wei Han
      This review article surveys the use of zeolites and mesoporous materials in fuel cell device and, operations. Zeolites are increasingly used to modify and improve the fuel cell membrane to address the, problems of fuel crossover and membrane stability. Mesoporous carbons and carbon aerogels with, their large surface area, high porosity and good interconnectivity are considered ideal material for electrodes and electrocatalysts. Zeolites and mesoporous materials are also employed as template to create nano-, micro- and macro-scale structures for new electrocatalysts. Furthermore, zeolites are used as catalyst, adsorbent and membrane in fuel processing from hydrogen production to purification.
      Graphical abstract image

      PubDate: 2014-08-18T16:03:27Z
       
  • Solid acids: Green alternatives for acid catalysis
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part B
      Author(s): Princy Gupta , Satya Paul
      This review deals with the general discussion on green chemistry and catalysis; and solid acid catalysts. Various Lewis and Brønsted solid acid catalysts reported in the last few years for various synthetic protocols have been discussed in this review.
      Graphical abstract image

      PubDate: 2014-08-18T16:03:27Z
       
  • Key questions, approaches, and challenges to energy today
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part B
      Author(s): John N. Armor
      This perspectives article is intended to highlight global energy needs and solutions with a focus on catalysis. Market dynamics are discussed along with today's major energy resource options and emerging energy resources versus petroleum with a particular focus on those topics where catalysis can offer real impact: shale gas, biomass, and solar. Petroleum, NG, and coal continue to dominate the energy resources for most nations with the percentage of renewables growing but accounting, in total, for a much smaller share of the energy pie. Other natural resources, such as land, geology, and water do impact energy options. Over the last few years, shale gas has had a big impact on the available energy resources. Renewables will take increasing amounts of the energy pie, but this is going to depend on the region and in nations, such as the USA and China, which have a long term supply of any one of the big three energy resources: NG, petroleum, and/or coal. There have in the past and will continue to be roles for catalysis and new materials in the big three and in renewables with many new opportunities arising because of the recent development of vast fields of shale gas wells producing at regionally competitive prices.
      Graphical abstract image

      PubDate: 2014-08-18T16:03:27Z
       
  • Comment on “The Critical evaluation of in situ probe techniques for
           catalytic honeycomb monoliths” by Hettel et al.
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part B
      Author(s): Alexandre Goguet , William P. Partridge , Farid Aiouche , Christopher Hardacre , Kevin Morgan , Cristina Stere , Jacinto Sá



      PubDate: 2014-08-18T16:03:27Z
       
  • Sol–gel method for synthesis of Mn–Na2WO4/SiO2 catalyst for
           methane oxidative coupling
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part A
      Author(s): H.R. Godini , A. Gili , O. Görke , S. Arndt , U. Simon , A. Thomas , R. Schomäcker , G. Wozny
      In this experimental study, a novel sol–gel method was developed to synthesize a 1.9%Mn–5%Na2WO4/SiO2 catalyst for oxidative coupling of methane (OCM) reactions. The performance of the synthesized catalyst was investigated in fixed-bed and porous packed-bed membrane reactors. Particularly, the effects of operating temperature, methane-to-oxygen ratio and nitrogen dilution on the performance of this catalyst were investigated. It was observed that for high values of methane conversion, the sol–gel Mn–Na2WO4/SiO2 catalyst provides 5–15% higher selectivity toward the desired products (C2: C2H4 +C2H6) than the Mn–Na2WO4/SiO2 catalyst prepared by the incipient wetness impregnation method. It was also observed that for a similar set of experiments, the C2-selectivity of the sol–gel catalyst is affected relatively less by the variation of methane-to-oxygen ratio. As a result, this catalyst can be exploited under the low methane-to-oxygen feed ratio which provides an efficient performance in both the OCM reactor and the OCM process scale. The best observed performance of the sol–gel catalyst in the packed-bed membrane reactor is 78% C2-selectivity, 64% ethylene-selectivity and 24.2% C2-yield under 20% nitrogen dilution.
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      PubDate: 2014-08-14T16:01:43Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part A




      PubDate: 2014-08-14T16:01:43Z
       
  • Contents list
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part A




      PubDate: 2014-08-14T16:01:43Z
       
  • Special Issue on the 11th International Conference on Catalysis in
           Membrane Reactors
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part A
      Author(s): José M. Sousa , Angelo Basile , João Crespo



      PubDate: 2014-08-14T16:01:43Z
       
  • Noble metal catalysts supported on nanofibrous polymeric membranes for
           environmental applications
    • Abstract: Publication date: 1 November 2014
      Source:Catalysis Today, Volume 236, Part A
      Author(s): K. Soukup , P. Topka , V. Hejtmánek , D. Petráš , V. Valeš , O. Šolcová
      The effect of preparation method on the particle size of palladium and platinum nanoparticles supported on poly(2,6-dimethyl-1,4-phenylene) oxide electrospun membranes by the wet impregnation technique was investigated. Catalysts with similar metal loading (0.63–0.78wt.%) possessing various mean metal particle size (2.5–8.7nm) were prepared employing different impregnation times and nominal metal loadings. The catalysts were tested in the total oxidation of methanol (1000ppm in air). The catalytic activity of platinum catalysts increased with increasing size of Pt nanoparticles while the effect of the platinum loading was not observed. On the other hand, the catalytic activity of palladium catalysts increased with the increasing palladium loading and did not correlate with the nanoparticle size.
      Graphical abstract image

      PubDate: 2014-08-14T16:01:43Z
       
 
 
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