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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  [3042 journals]
  • IFC - Editors; Editorial Board & scope
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292


      PubDate: 2017-06-21T10:03:43Z
       
  • Contents list
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292


      PubDate: 2017-06-21T10:03:43Z
       
  • Editorial: New Developments in Sulfide Catalysis: Meeting Industrial Needs
           in a Fast Changing World
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Emiel Hensen, Sonja Eijsbouts, Thomas Weber


      PubDate: 2017-06-21T10:03:43Z
       
  • What’s new' On the development of sulphidic HT catalysts before
           the molecular aspects
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): J.A. Rob van Veen
      In 1869 Berthelot had already reported to have produced oil from coal, but only around 1910, in Germany (for cogent reasons), the subject was taken up in earnest. First Bergius, and then Pier (of the BASF, not fortuitously either) developed what was eventually called the Bergius-Pier process, a two-stage process for the liquefaction of coal. It was Matthias Pier who developed the catalysts for the second stage in which the primary products of the first coal-hydrogenation step needed to be upgraded. When he was done, by the late 1940s, many of the hydrotreating (HT), and some of the hydrocracking catalysts we are familiar with had seen the light of day: Co/Ni/Mo/W (mixed) sulphides, supported on alumina, Al2O3:F, or amorphous silica-alumina. The alumina-based catalysts were obviously ready-made for the hydrotreating of petroleum fractions as well, and therefore they were the catalysts of choice when this family of processes took off after WW II, and they also underwent, of course, further development. But it was only in the 1960s that people really started to imagine how these HT catalysts were structured and how they might function, giving rise to a variety of catalyst models under the impact of new spectroscopic techniques, and eventually leading to the Topsøe model and all that. Now, the question before us is: did the greatly increased knowledge of the catalysts affect in any substantial way their further development? Or is it rather the case that fundamental knowledge only started to be acquired when HT catalysis was already almost mature? This paper, then, has two parts: first, the essential features of catalyst development in the pre-Molecular-Aspects era will be reviewed, and then some salient aspects of the modern (so-to-speak) era will be discussed with a view to assess whether or not catalyst development can be seen to be changing, as it was often claimed, from an art to a science in the latter era.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Comprehensive GC×GC chromatography for the characterization of sulfur
           compound in fuels: A review
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Chantal Lorentz, Dorothée Laurenti, José Luiz Zotin, Christophe Geantet
      Since the beginning of the 2000’s, comprehensive GC×GC chromatography brought a totally new way to characterize complex matrices. This disruptive technique is well adapted to fuels and rapidly gained importance in R&D laboratories of oil (and related) companies. Therefore, this analytical tool has been applied to many aspects of refining and especially the challenge of reducing the sulfur content in fuels. The present article reviews the use of comprehensive GC×GC for understanding the nature of sulfur compounds in refinery products (from gasoline to VGO) and their catalytic conversion through various catalytic processes such as HDS, AOTS, ODS. Various types of detectors (universal or specific) as well as HT GC×GC have been applied and can be combined in order to get a better description of the S compounds in oil products.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Nickel sulfide crystals in Ni-Mo and Ni-W catalysts: Eye-catching inactive
           feature or an active phase in its own right'
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Sonja Eijsbouts, Xuanqi Li, Jaap Bergwerff, Jaap Louwen, Leo Woning, Joachim Loos
      Ni sulfide (NiSx) crystals dominate the TEM images and STEM-EDX elemental maps of used Ni-Mo and Ni-W hydrotreating catalysts. Crystal sizes ranging from about 5 to over 100nm in diameter are observed not only in severely deactivated catalysts after use in commercial reactors, but also in highly active catalysts obtained after relatively short testing regimes. Depending on Ni-S stoichiometry and reaction conditions, NiSx crystals have different dimensions, shapes and crystal structures. Many of the NiSx crystals are decorated by multiple layers of MoS2/WS2. Although the activity of bulk Ni sulfide is generally deemed to be negligible, this does raise the question if these crystals play a role in catalysis after all. The number and percentage of accessible Ni sites in different catalysts can be estimated by combining the results of (i) the dispersion measurements on the MoS2/WS2 phase, (ii) the dispersion measurements on the visualized NiSx crystals and (iii) the composition of the catalyst matrix surrounding the NiSx crystals as derived from the phase analysis. The calculations based on the apparent Ni to Mo/W ratio of the catalyst matrix show that the catalyst matrix contains much more Ni than what can be accommodated on the MoS2/WS2 edges. We assume that this excess Ni is present as small non-visualized NiSx crystals mixed in the catalyst matrix. The fraction of Ni atoms on the surface of NiSx crystals can be calculated using the parameters of the millerite structure. The calculations carried out for NiMo/Al2O3 and NiW bulk catalysts show that the NiSx crystals could account for 19% and 48% of the active Ni sites, respectively. Despite this relatively high number of accessible Ni sites on the surface of NiSx crystals, no positive effect of a Ni/W ratio higher than 0.25 on the catalyst HDS and HDN activity was observed for a series of NiW bulk catalysts with variable Ni/W ratio. This suggests that, despite their spectacular presence in the TEM micrographs, the NiSx crystals do not significantly contribute to the HDS and HDN activity.
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      PubDate: 2017-06-21T10:03:43Z
       
  • High pressure flow reactor for in situ X-ray absorption spectroscopy of
           catalysts in gas-liquid mixtures—A case study on gas and liquid phase
           activation of a Co-Mo/Al2O3 hydrodesulfurization catalyst
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): L. van Haandel, E.J.M. Hensen, Th. Weber
      An in situ characterization of heterogeneous catalysts under industrial operating conditions may involve high pressure and reactants in both the gas and the liquid phase. In this paper, we describe an in situ XAS flow reactor, which is suitable to operate under such conditions (pmax 20bar,Tmax 350°C) and report its use in studying hydrodesulfurization (HDS) catalyst activation. The effect of pressure (1 or 20bar) and sulfiding agent on the sulfidation rate of a CoMo/Al2O3 catalyst prepared with phosphate and polyethyleneglycol is determined from in situ XANES at the Co and Mo K-edges. Cobalt is sulfided substantially faster in 20bar compared to 1bar H2/H2S (gas phase activation), whereas the effect of pressure on molybdenum sulfidation is smaller. Liquid phase activation in 20bar H2 and a model diesel feed (n-hexadecane/tert-nonylpolysulfide (TNPS)) starts at 190°C, initiated by the in situ formation of H2S from TNPS, and is rapidly completed. Thus, pressure and sulfiding agent have a substantial effect on the sulfidation rate of HDS catalysts. The in situ XAS approach introduced here enables studying catalysts under industrial operating conditions and is applicable to not only hydrodesulfurization catalysts, but to any other catalytic system that requires high pressure and reactants in a gas/liquid mixture.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Effects of the support Brønsted acidity on the hydrodesulfurization and
           hydrodenitrogention activity of sulfided NiMo/Al2O3 catalysts
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Wei Han, Hong Nie, Xiangyun Long, Mingfeng Li, Qinghe Yang, Dadong Li
      Through switching the deposition of MoS3 nanoparticles onto the support with the impregnation of the support with a NH4F solution, two typical F-doped bimetallic NiMoS2/Al2O3 catalysts exhibiting nearly the same compositions, textural properties, chemical state and micromorphology but only one containing some Brønsted (B) acid sites on the alumina surface were first prepared. And then the effects of the support B acidity on hydrodesulfurization (HDS) and hydrodenitrogeneration (HDN) activity were comprehensively studied using representative quinoline (Q) and dibenzothiophene (DBT) as the model reactants, respectively. After comparing the “structure-function” relations of the two bimetallic catalysts, an electronic effect of the support B acid sites on the edge sites of their neighboring MoS2 nanoslabs was suggested. This electronic effect could not only bring about the easier formation of CUS, but also enhance the acidity of SH species. This dual effect greatly promotes the HDS and HDN activities. Besides, the B acid sites also help the catalysts exhibit a certain isomerization activity, which further enhances the HDS performance.
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      PubDate: 2017-06-21T10:03:43Z
       
  • FT-IR study of NO adsorption on MoS2/Al2O3 hydrodesulfurization catalysts:
           Effect of catalyst preparation
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): L. van Haandel, E.J.M. Hensen, Th. Weber
      The effect of catalyst preparation on structure and performance of MoS2/Al2O3 hydrodesulfurization (HDS) catalysts was studied by NO adsorption, monitored by infrared spectroscopy (NO-IR) and complemented with EXAFS. The main bands at 1785cm−1 and 1690cm−1 were assigned to the ν(NO) stretching vibrations of coupled mono- or dinitrosyl surface complexes. NO adsorption on sulfided catalysts prepared with nitrilotriacetic acid (NTA) or citric acid (CA) gave rise to additional bands in the IR spectra at 1655cm−1, 1630cm−1 and 1615cm−1, assigned to mononitrosyl adsorption modes. Catalysts prepared with NTA and CA were more active in thiophene HDS than calcined or dried catalysts, despite comparable NO uptake (0.10-0.12 NO/Mo). This was attributed to a changed MoS2 edge structure as suggested by the NO-IR data, as well as to an improved degree of sulfidation as observed by EXAFS. Correlating NO uptake with MoS2 dispersion shows that not more than 30–40% of edge and corner sites were probed with NO. This implies that only a small portion of edge sites may act as active sites in HDS catalysis.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Active sites of sulfided NiMo/Al2O3 catalysts for
           4,6-dimethyldibenzothiophene hydrodesulfurization-effects of Ni and Mo
           components, sulfidation, citric acid and phosphate addition
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Kentaro Kobayashi, Masatoshi Nagai
      The active sites of the sulfided 5.2wt%Ni9.8wt%Mo/Al2O3 catalyst for the hydrodesulfurization of 4,6-dimethyldibenzothiophene were studied using a high-pressure flow system. The catalysts were prepared by dry sulfidation or after the calcination of four sets of NiMo precursors with and without citric acid and phosphoric acid. The dry sulfidation using the precursor of nickel carbonate and molybdenum trioxide with citric acid and phosphate produced the HDS MoO3 is considered a precursor for the hydrogenation activity, and ammonium heptamolybdate is a precursor for the direct desulfurization activity. and the highest number of active sites of the Ni2+MoS2 slab (NiMoS phase) based on the NO and XPS. The sulfidation after calcination using nickel nitrate and ammonium hexamolybdate had the highest HDS rate for the desulfurization, and the number of sites of the MoS2 (Mo4+) slab covered with Ni sulfide (Ni2+). This site was stacked with 3.3 layers and 34Å length for the 2% phosphorus catalyst and widely dispersed as multilayers, and increased when stacked by the phosphate addition and contained highly stacked slabs by the citric acid addition.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Unsupported trimetallic Ni(Co)-Mo-W sulphide catalysts prepared from mixed
           oxides: Characterisation and catalytic tests for simultaneous tetralin HDA
           and dibenzothiophene HDS reactions
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Yordy E. Licea, Ricardo Grau-Crespo, Luz A. Palacio, Arnaldo C. Faro
      Unsupported A-Mo-W (A=Ni or Co) sulphide catalysts were obtained from mixed oxides containing different W:Mo ratios. An in situ liquid-phase sulphidation of the mixed oxides in a batch reactor was followed by catalytic tests in a liquid-phase reaction (at 613K and 70bar), using a mixture of dibenzotiophene (DBT) and tetralin (THN) as the feed. After the catalytic tests, the bulk sulphide catalysts were characterised by nitrogen physical adsorption, XANES/EXAFS, SEM and HR-(S)TEM. The HR-TEM images showed randomly oriented, stacked-layer particles typical of Mo (W) sulphides and an elemental HR-STEM mapping evidenced Mo/W homogeneous distribution in the trimetallic sulphides. The EXAFS results for the trimetallic catalysts are consistent with the presence of nickel or cobalt sulphide domains, and Mo1-x W x S2 solid solutions. The intralayer Mo:W solid solutions were confirmed to be thermodynamically stable with respect to phase separation by DFT calculations, which were also used to aid in the interpretation of the EXAFS results. The effect of the W:Mo ratio on the catalytic properties of the Ni- and Co-containing series was found to be different. For the Ni series, increasing the W content caused an activity increase in THN hydrodearomatization (HDA) relative to DBT hydrodesulphurization (HDS), while it had little influence on the relative contribution of the direct desulphurisation (DDS) route with respect to the previous hydrogenation (HYD) route for DBT HDS. In contrast, for the Co series, the activities and selectivities were essentially insensitive to the W content. Both the Ni and Co series of unsupported sulphides were more selective for the HYD route in DBT HDS than a supported NiMo/Al2O3 catalyst.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Influence of active phase structure of CoMo/Al2O3 catalyst on the
           selectivity of hydrodesulfurization and hydrodearomatization
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): W. Chen, X. Long, M. Li, H. Nie, D. Li
      The relationship between the morphology and the selectivity of the sulfide phase in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and hydrodearomatization (HDA) reaction of 1-methylnaphthalene (1-MN) was studied. The morphology of the CoMo catalyst was tuned by increasing the metal content and adding organic compounds. The concentration of CoMoS sites at the corners (C(CoMoSC) and edges C(CoMoSE)) of the sulfide slabs were measured by X-ray photoelectron spectroscopy and high resolution transmission electron microscopy techniques. The corner and edge sites of the sulfide phase account for the direct desulfurization (DDS) and hydrogenation desulfurization (HYDS) routes in the HDS of 4,6-DMDBT, respectively. The hydrogen consumption analysis showed that the HYDS of 4,6-DMDBT and HDA of 1-MN both occur at the edge sites of the MoS2 slabs. The HYDS route in 4,6-DMDBT HDS was more promoted than the 1-MN HDA reaction when the stacking was increased. The turnover frequency of the corner sites for the DDS reaction and edge sites for the HYDS and HDA reactions were correlated with the length and stacking of the sulfide phase. The results revealed how the selectivities of the DDS, HYDS and HDA reactions as well as the hydrogen consumption can be tuned by modifying the morphology of the sulfide phase.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Beneficial role of carbon in Co(Ni)MoS catalysts supported on
           carbon-coated alumina for co-hydrotreating of sunflower oil with
           straight-run gas oil
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): A.N. Varakin, V.A. Salnikov, M.S. Nikulshina, K.I. Maslakov, A.V. Mozhaev, P.A. Nikulshin
      The purpose of the study was to evaluate carbon effect on Co(Ni)-PMo/C/Al2O3 catalysts in co-hydrotreating (co-HDT) of straight-run gas oil (SRGO) and sunflower oil (SO). The catalysts were prepared using 12-molybdophosphoric heteropolyacid, cobalt tartrate, and Al2O3 or C/Al2O3 (2wt% of carbon) as a support. The solids were characterized by N2 physisorption, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic properties were investigated using a bench-scale flow reactor in co-HDT of mixed feed containing SRGO and 5, 10, and 15wt% of SO. It was found that Co-РMo catalysts demonstrated higher hydrodesulfurization (HDS) activity in SRGO HDT than its Ni-РMo/C/Al2O3 counterparts. The use of C/Al2O3 led to more active Co-РMo and Ni-РMo catalysts compared with Al2O3 supported ones. Co-PMo samples more significantly lost activities than Ni-PMo after adding SO in the feed. Addition of SO led to an increase in HDS apparent activation energy by 21kJmol−1 on Co-РMo and has not affected it in co-HDT of blended feedstock over Ni-PMo. All obtained results showed the high effectiveness of the prepared Ni-РMo/C/Al2O3 catalyst. They showed high HDS, hydrogenation and hydrodenitrogenation activities in co-HDT of the mixed SRGO/SO feedstock as well as catalyst stability against to accelerated deactivation. The possible reasons of the catalytic behavior of the studied samples are discussed based on the characteristics of the freshly sulfided and spent samples as well as determined kinetic parameters.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Silica-supported Ni2P: Effect of preparation conditions on structure and
           catalytic performance in thiophene hydrodesulfurization (HDS)
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Xuefang Lan, Emiel J.M. Hensen, Thomas Weber
      Silica-supported Ni2P catalysts were synthesized from precursors, which were either prepared by sequential impregnation of phosphorus (i.e. phosphate, phosphite and hypophosphite) on calcined NiO/SiO2, or by co-impregnation of nickel and phosphorus and subsequent reduction with hydrogen. Ni2P formation mechanisms, as investigated by means of TPR-MS, XRD and XPS, varied as a function of preparation method. Catalytic performance of the resulting Ni2P materials was evaluated in thiophene hydrodesulfurization; particle size was characterized by TEM. Catalysts prepared by sequential impregnation and subsequent calcination were less active than samples prepared by co-impregnation without calcination because of significantly lower Ni2P dispersion due to calcination. For catalysts prepared by co-impregnation the activity increased with increasing reducibility of the P precursor, i.e. in the order NH4H2PO4 <H3PO3 ≈H3PO2.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Ni2P/Al2O3 hydrodesulfurization catalysts prepared by separating the
           nickel compound and hypophosphite
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Dapeng Liu, Anjie Wang, Chenguang Liu, Roel Prins
      Bulk Ni2P and Al2O3-supported Ni2P were prepared at low phosphidation temperature (300 or 330°C) from nickel nitrate, oxide, sulfate, chloride, and acetate as nickel source and ammonium and sodium hypophosphite as well as hypophosphoric acid as phosphorus source. The hypophosphite source was positioned up-flow of the nickel source in an oven and flowing N2 gas transported the phosphine formed in the decomposition of hypophosphite to the nickel compound. X-ray diffraction, N2 adsorption-desorption, thermogravimetry and differential scanning calorimetry, temperature-programmed reduction in H2, and transmission electron microscopy, field emission scanning electron microscopy, CO chemisorption, and solid-state 31P nuclear magnetic resonance were used to study the bulk and supported Ni2P. Whereas unsupported nickel nitrate, sulfate, chloride, and oxide led to impure Ni2P, nickel acetate gave pure Ni2P. Ni2P/Al2O3 catalysts were therefore prepared from nickel acetate and their activity was studied in the hydrodesulfurization of dibenzothiophene. Separating the hypophosphite from the nickel compound has the advantage that the phosphate formed in the disproportionation of hypophosphite does not reach the Al2O3-supported Ni compound and cannot block the pores of the support. Ni2P is formed by sequential reduction and phosphidation reactions and therefore its preparation demands careful adjustment of the synthesis conditions. Insufficient PH3 leads to Ni and Ni12P5 side products and too much PH3 to Ni5P4, which all have a lower HDS activity than Ni2P.
      Graphical abstract image

      PubDate: 2017-06-21T10:03:43Z
       
  • Direct synthesis of methyl mercaptan from H2/CO/H2S using tungsten based
           supported catalysts: Investigation of the active phase
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): A. Cordova, P. Blanchard, H. Salembier, C. Lancelot, G. Frémy, C. Lamonier
      K2WO4 and K2WS4 were used as precursors for the preparation of alumina, silica and hydroxyapatite supported catalysts whose catalytic performance have been evaluated in the direct reaction of syngas with hydrogen sulfide to produce methyl mercaptan. The solids were characterized using specific surface area measurements, Raman, XRD and X-rays Photoelectrons Spectroscopy, before and after activation (sulfidation). Catalytic performances were correlated to the formation of a KxWS2 phase, evidenced by Raman and XPS, where potassium is assumed to be intercalated in the 1T-WS2 layered phase. Alumina supported catalyst containing high surface concentration of this phase was the most efficient with a CH3SH productivity reaching 72gh−1 L−1.
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      PubDate: 2017-06-21T10:03:43Z
       
  • On the photocatalytic and electrocatalytic hydrogen evolution performance
           of molybdenum sulfide supported on TiO2
    • Abstract: Publication date: 1 September 2017
      Source:Catalysis Today, Volume 292
      Author(s): Etienne Girel, Eric Puzenat, Christophe Geantet, Pavel Afanasiev
      This study aimed to define key preparation and treatment parameters determining the hydrogen evolution reaction (HER) performance of molybdenum sulfide-based photocatalysts. Amorphous and nanocrystalline molybdenum sulfide catalysts supported on titania have been studied in photocatalytic and electrochemical HER. The results of HER measurements were compated to the thiophene hydrodesulfurization HDS activity. Titania polymorph plays a crucial role for HER: high-surface area anatase PC500 and anatase-rutile Degussa P25 show high HER performance, whereas rutile nanorods demonstrate poor activity. Two preparation methods applying impregnation and solution deposition techniques have been compared. Solution deposition affords superior activity, with a maximum HER rate for 0.5%wt. Mo loading, even if the dispersion of MoS2 phase and HDS activity are better for impregnated systems. Therefore, for the photocatalytic performance not the dispersion of MoS2 and abundance of edge sites but efficient electron hopping from the semiconductor to the co-catalyst is most important. In order to study the influence of the MoS2 edges state, the solids reduced under H2 or treated in pure H2S were compared. The presence edge S2 2− groups have a positive influence on the photo- and electrocatalytic HER activity.
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      PubDate: 2017-06-21T10:03:43Z
       
  • IFC - Editors; Editorial Board &amp; scope
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291


      PubDate: 2017-06-21T10:03:43Z
       
  • Contents list
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291


      PubDate: 2017-06-21T10:03:43Z
       
  • Preface: Green Catalytic Processes
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291
      Author(s): Ajay K. Dalai, Janusz A. Kozinski, Nicolas Abatzoglou, Md. Azhar Uddin


      PubDate: 2017-06-21T10:03:43Z
       
  • Ex-situ up-conversion of biomass pyrolysis bio-oil vapors using Pt/Al2O3
           nanostructured catalyst synergistically heated with steel balls via
           induction
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291
      Author(s): Mohammad Abu-Laban, Pranjali D. Muley, Daniel J. Hayes, Dorin Boldor
      Radiofrequency-driven hydrodeoxygenation of sawdust pyrolysis vapor and the coking performance of the catalysts were investigated using Pt/Al2O3 commercial pellets mixed with steel balls inside an alumina tube. The radio-frequency induction heating of the catalyst bed was compared with a conventional method of heating using electric tape engulfing the catalyst bed reactor. Partial deoxygenation of the oil was successfully achieved in the catalytic upgrading of pyrolysis oil at 234°C, with the use of the induction heater. The molar O/C ratio of the oil decreased from 1.36 to 0.51. No deoxygenation of the oil was observed using the electric tape control under identical conditions as both carbon and oxygen appeared to be removed at approximately equal rates, with the carbon being deposited in the form of coke onto the catalyst instead of being recovered in the liquid.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Lewis acid catalyzed gasification of humic acid in supercritical water
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291
      Author(s): Miao Gong, Sonil Nanda, Howard N. Hunter, Wei Zhu, Ajay K. Dalai, Janusz A. Kozinski
      Humic acid is a model compound of sewage sludge that occurs as a result of decomposing organic matter. Supercritical water gasification of humic acid was performed at a temperature, feed concentration and reaction time of 600°C, 15wt% and 75min, respectively with variable concentrations (5–15wt%) of Lewis acid metal chloride catalysts. The non-catalytic gasification of humic acid resulted in H2 yield (0.79mol/kg), total gas yield (1.59mol/kg), carbon gasification efficiency (2.2%), H2 gasification efficiency (10%) and lower heating value of 5.1kJ/Nm3. In contrast, 15wt% of Lewis acid catalysts loading significantly improved H2 yields (2.79–11.03mol/kg), total gas yields (4.72–15.44mol/kg), carbon gasification efficiency (5.7–12.4%), H2 gasification efficiency (40.9–141.6%), energy recovery (8.8–33.79%) and lower heating value of gas products (22.4–72.3kJ/Nm3). The activity of Lewis acids was in the order: CaCl2 <ZnCl2 <FeCl3 <CuCl2 <NiCl2 <AlCl3. The addition of Lewis acid catalysts led to an increment in H2 yield due to ring-opening reaction and intermediates gasification. High catalyst loading promoted the degradation of humic acid with greater gas yields and fragmented surface morphology of char residues. The liquid effluents from Lewis acid catalyzed gasification of humic acid contained considerable amounts of aromatic and aliphatic components.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Catalytic methanation of CO2 with NH3
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291
      Author(s): Md. Azhar Uddin, Yamato Honda, Yoshiei Kato, Katsuhiko Takagi
      The catalytic methanation of CO2 with ammonia over Ni, Pt, and Ru catalysts impregnated on γ-alumina was carried out in a fixed-bed reactor under atmospheric pressure at 573–873K. The methanation of CO2 with NH3 is considered to occur in two stages –NH3 decomposition into H2/N2 followed by CO2 methanation with H2. 1wt% Pt/γ-Al2O3 exhibited low activity for NH3 decomposition and CO2 methanation with H2. Both 5wt% Ni/γ-Al2O3 and 1wt% Ru/γ-Al2O3 showed high activity for NH3 decomposition and CO2 methanation with H2, but Ru/γ-Al2O3 was much more active. For CO2 methanation with ammonia, only Ru/γ-Al2O3 was significantly active. The yield of CH4 increased with increased Ru loading and reaction temperature, but was limited by thermodynamic equilibrium at higher temperatures. Ammonia decomposition is more facile than CO2 methanation on the Ru/γ-Al2O3 catalyst and CO2 methanation is the rate limiting step.
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      PubDate: 2017-06-21T10:03:43Z
       
  • Effect of alkali on CH bond scission over Pt/YSZ catalyst during
           water-gas-shift, steam-assisted formic acid decomposition and methanol
           steam reforming
    • Abstract: Publication date: 1 August 2017
      Source:Catalysis Today, Volume 291
      Author(s): Michela Martinelli, Gary Jacobs, Wilson D. Shafer, Burtron H. Davis
      In previous work, Na-doping of Pt/YSZ was found to facilitate the low temperature water gas shift reaction (LT-WGS), and the promoting effect was ascribed to an electronic weakening of the CH bond of the formate species, a proposed intermediate in the catalytic cycle. Formate has also been implicated as an intermediate in steam-assisted formic acid decomposition (SAFAD) and methanol steam reforming (MSR) pathways. In the current contribution, Na-doping was also found to significantly accelerate the SAFAD reaction. The high activity of Pt/YSZ for SAFAD, as well as the promoting effect of Na, are in stark contrast to the view that formates are too stable, precluding them as intermediates for LT-WGS. With MSR, a remarkable promoting effect of Na doping was observed in the selectivity to CO2 (>90% for Na-doped relative to 22% for undoped at 300°C); however, at the doping levels used in the current work, the activity was lower for the Na doped catalyst and further optimization is needed to improve MSR conversion.
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      PubDate: 2017-06-21T10:03:43Z
       
  • IFC - Editors; Editorial Board &amp; scope
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294


      PubDate: 2017-06-16T00:38:20Z
       
  • Contents list
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294


      PubDate: 2017-06-16T00:38:20Z
       
  • CO electro-oxidation reaction on Pt nanoparticles: Understanding peak
           multiplicity through thiol derivative molecule adsorption
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Dong Young Chung, Myeong Jae Lee, Minhyoung Kim, Heejong Shin, Mi-Ju Kim, Ji Mun Yoo, Subin Park, Yung-Eun Sung
      The electro-oxidation of CO adsorbed on Pt nanoparticles is an important reaction in fuel cells. Despite extensive research, the underlying concept for peak multiplicity is not yet clearly understood. We investigated CO electro-oxidation features by scan-rate-dependent Tafel analysis and a model system experiment based on adsorption of 3-mercaptopropionic acid (3-MPA). The results suggest that the first main oxidation peak corresponds to the competition between OH adsorption and the interaction between adsorbed CO and OH. Modifying the Pt surface with 3-MPA can reduce the OH coverage, which in turn reduces the width of the first peak. However, the peak potential is not significantly dependent on OH coverage. Considering that the free surface is large enough for OH adsorption on Pt at high potential, the second peak shows few features that depend on OH coverage; the second peak is mainly influenced by the Pt-CO interaction.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Improvement of the photocatalytic hydrogen production rate of g-C3N4
           following the elimination of defects on the surface
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Jin Su Kim, Jae Woong Oh, Seong Ihl Woo
      The structural defects in g-C3N4 play an important role for photocatalytic activity of g-C3N4 for hydrogen production. We conducted a study on the relationship between the surface defect concentration and the photocatalytic activity having different modification time for the hydrogen production. The ball milling process for the elimination of the defects was adopted. The amino group created by incomplete polymerization of g-C3N4 may be considered as the defects, and the improved photocatalytic activity was measured after the modification. The enhancement can be ascribed to both enlarged surface area and reduced surface defect concentration. In order to identify the major factor for the enhancement of hydrogen production rate, the linear plot for photocatalytic activity versus the surface area and the degree of polymerization was obtained, respectively. Finally, it was identified that the reduced surface defect concentration is a major factor for the enhancement of the photocatalytic activity.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Improving removal of 4-chlorophenol using a TiO2 photocatalytic system
           with microwave and ultraviolet radiation
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Seo Jin Ki, Ki-Joon Jeon, Young-Kwon Park, Sangmin Jeong, Heon Lee, Sang-Chul Jung
      A conventional photocatalytic system is a viable tool to purify wastewaters, whereas poor degradation performance due to diverse pollutants under various conditions still leaves it behind commercial markets. This study aimed to determine the degradation efficiency and mechanism of 4-chlorophenol in a hybrid system integrating a series of unit processes such as a conventional TiO2 photocatalytic reactor as well as microwave and ultraviolet (UV) radiation. The decomposition (rate) of 4-chlorophenol was assessed with respect to the microwave intensity, pH, circulating fluid velocity, hydrogen peroxide level, and oxygen gas injection, along with a mix of individual processes. Results showed that there were favorable conditions for improving the degradation performance within certain limits. However, a significant synergy effect was also observed in the combined processes, which was substantially larger than any single process. Out of them, the best degradation performance was achieved using microwave irradiation and hydrogen peroxide in the photocatalytic reactor. The four intermediates (i.e., benzoquinone, hydroquinone, 4-chlorocatechol, and hydroxyhydroquinone) appeared to be generated through hydroxyl radicals-mediated hydroxylation and dechlorination in the proposed photocatalytic pathway. The present research is expected to provide new insights into designing the high performance photocatalytic system with affordable cost.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Catalytic conversion of 1,2-dichloroethane over Ni-Pd system into
           filamentous carbon material
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Yurii I. Bauman, Yuliya V. Shorstkaya, Ilya V. Mishakov, Pavel E. Plyusnin, Yury V. Shubin, Denis V. Korneev, Vladimir O. Stoyanovskii, Aleksey A. Vedyagin
      The alloyed Ni-Pd system with Pd content of 3wt.% was prepared by coprecipitation method followed by reduction in hydrogen atmosphere at 800°C. The formation of single-phase solid solution with unit cell parameter a=3.532(1) Å (determined by (331) reflex at 2θ ≈ 145°) corresponding to NiPd alloy with weight ratio 97:3 was confirmed by XRD analysis. Kinetic studies on catalytic conversion of 1,2-dichloroethane (DCE) over NiPd alloy into carbon nanomaterial (CNM) were performed in a flow reactor equipped with McBain balances in a temperature range of 580–700°C. It was shown that interaction of DCE with NiPd system results in a fast disintegration of pristine alloy with formation of submicron (0.2-0.9μm) particles, which efficiently catalyze the growth of segmented carbon filaments. According to Raman spectroscopy and transmission electron microscopy data, hydrogen concentration in reaction mixture strongly affects the structural features and density of segmented filaments. The average values of inter-segmental distance calculated from TEM micrographs of carbon filaments were found to be 96, 46, 16nm for hydrogen concentration of 23, 36 and 47 vol.%, respectively. Strongly chemisorbed chlorine species were suggested to be responsible for the cyclic perturbations in carbon transfer and deposition. Obtained carbon nanomaterials were characterized with comparatively high specific surface area (300–400m2/g) and extremely low bulk density (<0.03g/ml).
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      PubDate: 2017-06-16T00:38:20Z
       
  • Role of acid solvent to prepare highly active PtSn/θ-Al2O3 catalysts in
           dehydrogenation of propane to propylene
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Natarajan Prakash, Mi-Hyun Lee, Sungho Yoon, Kwang-Deog Jung
      The PtSn bimetallic catalysts with a high Pt metal dispersion were successfully prepared using acid solvent. The aqueous mixed acid solution of HCl and HNO3 was used as solvent to dissolve the Pt and Sn precursors. The (Pt-Sn)A, (Sn-Pt)A and (PtSn)A catalysts (PtSnA catalysts) were prepared by sequential impregnation of Pt and Sn, sequential impregnation of Sn and Pt and co-impregnation, respectively. The metal dispersions of the (Pt-Sn)A, (Sn-Pt)A and (PtSn)A catalysts were 21.6%, 25.9%, 24.4%, respectively. For comparison, the (Pt-Sn)E, (Sn-Pt)E and (PtSn)E catalysts were prepared using ethanol similarly to the PtSnA catalysts. The metal dispersions of (Pt-Sn)E, (Sn-Pt)E and (PtSn)E catalysts (PtSnE catalysts) were 7.1%, 5.4%, and 7.5%, respectively. The metal dispersions of the PtSnA catalysts were three times higher than those of the PtSnE catalysts. The Pt metal particle sizes of the PtSnA catalysts were measured to be 4.4–6.9nm by chemisorption and 1.9–2.3nm by Technai STEM images. However, it was observed by a Titan STEM that the aggregates of the metal sub-nanoparticles were dispersed on the PtSnA catalysts. All the metal particles on the PtSnA catalysts existed in the sub-nano sizes. The particle size of 1.9–2.3nm by the Technai STEM is the size of the aggregates of the metal sub-nanoparticles. Propane dehydrogenation was conducted with the prepared catalysts at 873K and a GHSV of 22,500mLgcat −1 h−1. The initial catalytic activity decreased in the order of (Sn-Pt)A>(PtSn)A>(Pt-Sn)A>(PtSn)E>>(Pt-Sn)E>(Sn-Pt)E. The PtSnA catalysts showed not only the high activity but also the high selectivity and stability in propane dehydrogenation for 15h.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Catalytic dehydrofluorination of 1,1,1,2,3-pentafluoropropane (HFC-245eb)
           to 2,3,3,3-tetrafluoropropene (HFO-1234yf) using in-situ fluorinated
           chromium oxyfluoride catalyst
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Seoyeon Lim, Min Soo Kim, Jae-Wook Choi, Honggon Kim, Byoung Sung Ahn, Sang Deuk Lee, Hyunjoo Lee, Chang Soo Kim, Dong Jin Suh, Jeong-Myeong Ha, Kwang Ho Song
      As part of an effort to prepare a refrigerant with zero ozone depletion potential (ODP) and with a low global warming potential (GWP), the catalytic dehydrofluorination of 1,1,1,2,3-tetrafluoropropane (HFC-245eb) is performed to produce 2,3,3,3-tetrafluoropropene (HFO-1234yf). Cr2O3 prepared by the sol-gel method (Cr2O3(SG)) exhibits good catalytic activity attributable to the formation of surface chromium oxyfluoride, which exhibits better catalytic activity with high-valent chromium and a larger fluorine content. The formation of chromium oxyfluoride from chromium oxide is achieved by in-situ fluorination in the early stage of dehydrofluorination, avoiding the conventional fluorination method using toxic HF.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Direct synthesis of hydrogen peroxide from hydrogen and oxygen over
           palladium catalyst supported on heteropolyacid-containing ordered
           mesoporous carbon
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Jong Won Lee, Jeong Kwon Kim, Tae Hun Kang, Eo Jin Lee, In Kyu Song
      A series of palladium catalysts supported on ordered mesoporous carbon (Pd/OMC-T) were prepared with a variation of preparation temperature (T=8, 15, 25, 35, and 45°C) of ordered mesoporous carbon (OMC). Conversion of hydrogen and yield for hydrogen peroxide over Pd/OMC-T catalysts showed volcano-shaped trends with respect of preparation temperature in the presence of halide and acid additives. The catalytic performance was found to be closely related to the palladium surface area. With an attempt not to use acid additive, another series of palladium catalysts supported on heteropolyacid (HPA)-containing ordered mesoporous carbon (Pd/OMC-XHPA) were prepared with a variation of HPA content (X=5, 10, 20, 30, and 40wt%) using OMC-25 as a support. Selectivity and yield for hydrogen peroxide showed volcano-shaped trends with respect to HPA content. The superior catalytic performance of the catalyst at a certain HPA content (Pd/OMC-20HPA) was attributed to its high acidity caused by introduction of HPA into the pores of the catalyst.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Catalytic decomposition of N2O over NiO-CeO2 mixed oxide catalyst
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Zhiming Liu, Zizheng Zhou, Fang He, Biaohua Chen, Yuanyuan Zhao, Qi Xu
      A series of NiO-CeO2 mixed oxide catalysts prepared by the hydrothermal method were investigated for the decomposition of N2O. It was found that the addition CeO2 to NiO catalyst leads to a noticeable enhancement of the activity for the decomposition of N2O. The introduction of CeO2 inhibited the crystallization of the NiO phase, leading to the high surface area. In particular, the co-presence of NiO and CeO2 exhibited a synergetic effect, which contributes to forming the stabilized Ni2+ active sites. All of these factors, collectively, accounted for the high activity of NiO-CeO2 mixed oxide catalyst for the decomposition of N2O.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Low temperature NH3-SCR activity enhancement of antimony promoted
           vanadia-ceria catalyst
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Pullur Anil Kumar, Young Eun Jeong, Heon Phil Ha
      In this work, the antimony promoted Vanadia-Ceria catalysts have been prepared by homogeneous precipitation method for the selective catalytic reduction of NOx with NH3. With an introduction of Sb into Vanadia-Ceria, the catalysts showed an improvement in the low temperature NOx conversion below 250°C. These high activities of the Sb promoted catalysts were related to the increase of acid sites and redox properties of the catalysts, which were investigated by the NH3-TPD (temperature programmed desorption), H2-TPR (temperature programmed reduction) and in-situ NH3-DRIFTS (diffused reflectance infrared Fourier transformed spectroscopy) spectra. In addition, structural and morphological properties of these catalysts were examined by X-ray diffraction, BET surface area and FE-SEM (Field emission scanning electron microscopy). After the addition of Sb to Vanadia-Ceria, the increase of surface area with a smaller, uniform sized particles and high dispersion of vanadia were indicated in the optimized 4wt.%V2O5–2wt.% Sb-CeO2 catalyst. Furthermore, the Lewis and Brønsted acid sites were enhanced in the 4wt.%V2O5–2wt.% Sb-CeO2 catalyst to promote NOx conversion at a wide temperature range of 175–400°C. XPS results also indicated an improvement in the active oxygen species of this catalyst due to the enhancement of surface oxidation species of V4+/V5+, Sb3+/Sb5+ and Ce3+/Ce4+.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Effect of metal-metal and metal-support interaction on activity and
           stability of Pd-Rh/alumina in CO oxidation
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Aleksey A. Vedyagin, Alexander M. Volodin, Roman M. Kenzhin, Vladimir O. Stoyanovskii, Yury V. Shubin, Pavel E. Plyusnin, Ilya V. Mishakov
      A series of Pd-Rh/alumina catalysts with total precious metals loading of 0.2wt.% was prepared by means of mechanical mixing of monometallic precursors and incipient wetness impregnation of the support with dual complex salt. Gamma and delta alumina supports were obtained from commercial aluminum hydroxide by calcinations at 720 and 1000°C respectively. Supports were examined by electron paramagnetic resonance spectroscopy, low-temperature nitrogen adsorption, X-ray diffraction analysis and photoluminescence spectroscopy. It was shown that concentration of donor sites of the supports differs according to distinctions between values of their specific surface areas. Finally, the strength of metal-support interaction is getting much weaker in the case of δ-Al2O3. Bimetallic Pd-Rh species with strong metal-metal interaction supported on γ-Al2O3 were found to be characterized by superior high-temperature stability. Pd/Rh ratios of 3:2 and 7:3 were shown to be the most appropriate for this purpose.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Mechanistic study for enhanced CO oxidation activity on (Mn,Fe) co-doped
           CeO2(111)
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Kyeounghak Kim, Jeong Woo Han
      Owing to the unique properties such as facile redoxability and high stability, ceria has been used for a wide range of applications including automotive emission control, catalytic combustion, hydrocarbon reforming, and electrocatalytic reactions. It is well known that enhanced chemical reactivity can be achieved on transition metal (TM)-doped ceria nano-catalysts. In particular, co-doping of TM on CeO2 surface has recently opened a great potential to improve the catalytic activity compared to the single doped one. In this study, we performed DFT calculations to compare the activity of CO oxidation between Mn-, Fe-, and (Mn,Fe)-doped CeO2(111) via Mars-van Krevelen (MvK) mechanism. We firstly verified that a conventional linear relationship between oxygen vacancy formation energy and the catalytic activity of CO oxidation is also effective for the co-doped CeO2(111). It turns out that the energy required to create oxygen vacancy (Evf), that is a key descriptor of the reactivity, will be extremely useful to rapidly screen the catalytic activity on co-doped oxide system. Then, we investigated the entire reaction profile of CO oxidation via the MvK mechanism on Fe-, Mn- and (Mn,Fe)-doped CeO2(111). Based on the results, we confirmed the improved activity of CO oxidation on the co-doped system, which was in good agreement with the prediction from Evf. From this study, we believe that the co-doping of TM on oxide catalysts will be a noble strategy to enhance the catalytic activity.
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      PubDate: 2017-06-16T00:38:20Z
       
  • CO and CO2 methanation over supported Ni catalysts
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Thien An Le, Min Sik Kim, Sae Ha Lee, Tae Wook Kim, Eun Duck Park
      CO and CO2 methanation was investigated over Ni catalysts supported on different supports such as γ-Al2O3, SiO2, TiO2, CeO2, and ZrO2. Among them, Ni/CeO2 was determined to be the most active for CO and CO2 methanation. These catalytic activities increased with increasing surface area of CeO2. To increase the specific catalytic activity for CO and CO2 methanation, various Ni-CeO2 catalysts with different Ni contents were prepared using co-precipitation method. The optimum Ni content was determined for both reactions. The prepared catalysts were characterized with inductively coupled plasma-atomic emission spectroscopy, N2 physisorption, temperature-programmed reduction, temperature-programmed desorption, and X-ray diffraction. The high Ni dispersion and strong CO2 adsorption appeared to be responsible for the high catalytic activity for CO and CO2 methanation. This Ni-CeO2 can be applied to the low-temperature CO and CO2 methanation reactor to achieve high single-pass conversions of CO and CO2.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Enhancement of methanation of carbon dioxide using dielectric barrier
           discharge on a ruthenium catalyst at atmospheric conditions
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Chung Jun Lee, Dae Hoon Lee, Taegyu Kim
      This paper describes the enhancement of CO2 methanation using dielectric barrier discharge (DBD) on Ru catalyst under atmospheric conditions. The DBD plasma leads to increased deoxygenation of CO2, which is decomposed into CO. Subsequently, the Ru catalyst activates the methanation in the DBD plasma at atmospheric conditions. The effect of the discharge frequency of the DBD plasma and the H2/CO2 mixture ratio on the CO2 conversion and CH4 selectivity is investigated. The CO2 conversion and CH4 selectivity rapidly increase at a discharge frequency above 2.5kHz, and reach 23.20% and 95.02%, respectively, when the H2/CO2 molar ratio is 7. CO2 methanation and deoxygenation are simultaneously enhanced by adding Ar. Optical emission spectroscopy is used for the plasma diagnostics in the CO2 methanation process. The optical emission spectra of the γ-Al2O3 and Ru/γ-Al2O3 catalysts are measured to investigate the effect of the presence of Ru during plasma generation. Finally, the excited and ionized hydrogen atoms are confirmed as the primary accelerators in the plasma-assisted CO2 methanation process.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Investigation of intermediates in non-oxidative coupling of methane by
           non-thermal RF plasma
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Jongyoon Bae, Maeum Lee, Sunyoung Park, Myung-Geun Jeong, Do-Young Hong, Young Dok Kim, Yong-Ki Park, Young Kyu Hwang
      Non-oxidative coupling of methane by low pressure RF plasma was investigated with real time monitoring tools such as Langmuir probe, and ion mass and energy spectrometer. Process parameters were systematically changed to generate various plasma conditions and thus to identify key factors affecting the methane activation. From real time analysis, it was found that effects of electron energy and ion energy on methane conversion were minimal when the electron energy of plasma is greater than methane activation energy. On the other hand, electron concentration and the residence time in plasma were strongly correlated with the degree of methane conversion. Moreover, it should be noted that the density of methanium (CH5 +) which is a byproduct of ion-molecule reaction pathway of methyl radical formation (CH3 ), was reversely related to the extent of methane conversion due to active reactions among the methanium and C2 product molecules. Furthermore, for tested experimental conditions in this study, the product distribution of the methane plasma reaction was more closely related with the methane conversion level than with other plasma parameters. This real time analysis results can be used to derive meaningful insights to help designing an effective synergistic plasma-catalyst system.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Enhanced catalytic performance of Pt/TiO2 catalyst in water gas shift
           reaction by incorporation of PRGO
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Soon Jin Kwon, Ji Hye Park, Kee Young Koo, Wang Lai Yoon, Kwang Bok Yi
      TiO2 over partially reduced graphite oxide (PRGO) was prepared using the hydrothermal synthesis method with varying amounts of the TiO2 precursor for WGS catalyst support. Pt catalysts for the low-temperature water gas shift (WGS) reaction were then prepared by the incipient wetness impregnation method with the TiO2/PRGO (TirGO) supports. The WGS reaction was carried out with the Pt/TiO2/PRGO (Pt/TirGO) catalysts to investigate the effect of the incorporation of PRGO on the catalytic activity. Characterization of the supports and catalysts was performed with XRD, SEM, XPS, Raman spectroscopy, BET surface analysis, and temperature-programmed reduction (TPR). It was found that functional groups containing oxygen on the PRGO provide anchoring sites for the TiO2 precursors during the hydrothermal process, resulting in enhanced catalytic activity. In addition, the introduction of PRGO also improved the reducibility of the catalysts. It was also confirmed that there exists an optimal ratio of TiO2 to PRGO that facilitates a uniform dispersion of nanosized TiO2 on the PRGO by balancing the number of functional groups on PRGO with the amount of TiO2 precursor used. Among the Pt/TirGO catalysts synthesized, Pt/TirGO-5 possessed the optimum ratio of TiO2 to PRGO and showed excellent catalytic activity in the WGS reaction, achieving over 80% conversion of CO at the low temperature of 280°C and a very high gas hourly space velocity (GHSV) of 47,700h−1.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Enhanced activity and durability of Ru catalyst dispersed on zirconia for
           dry reforming of methane
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Ho Seok Whang, Min Seok Choi, Jinkyu Lim, Chanyeon Kim, Iljeong Heo, Tae-Sun Chang, Hyunjoo Lee
      Dry reforming of methane (DRM) reaction is an interesting and promising way to convert CO2 into valuable chemicals. Various metals have been investigated as active sites for the DRM reaction, and particularly, precious metals have been known to be active without severe coke formation. In this work, we showed that a very small amount of Ru (0.13wt%) immobilized at ZrO2-SiO2 are very active and stable for the DRM reaction performed at 800°C. When Ru was deposited at the SiO2 support, Ru domain size was relatively large as 6.3nm. But the Ru size significantly decreased to 1.4nm when Ru was deposited at the ZrO2-SiO2 support. The strong metal-support interaction between Ru and ZrO2 was also confirmed by TPR and XANES measurements. The Ru/ZrO2-SiO2 catalyst presented no coke formation whereas filamentous carbon was deposited at the Co-Ru/ZrO2-SiO2 catalyst. The Ru/ZrO2-SiO2 catalyst enabled the DRM reaction stably at 800°C without significant reduction in activity even at high space velocities of >100,000ml/gcat·h.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Ru-coated metal monolith catalyst prepared by novel coating method for
           hydrogen production via natural gas steam reforming
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Kee Young Koo, Hyun Ji Eom, Soon Chul Kwon, Un Ho Jung, Wang Lai Yoon
      Ru-coated FeCrAlloy monolith catalysts were prepared by a deposition-precipitation (DP) method with different solution pHs and evaluated the catalytic activity in natural gas steam reforming (NGSR) reaction for H2 production. The characteristics of prepared monolith catalysts as to the crystallite size, surface area, pore size distribution, metal dispersion, and morphology of Ru particles were analyzed by XRD, BET, BJH, CO-chemisorption, and SEM, respectively. The solution pH had a major effect on the precipitation formation and the particle size and dispersion of Ru catalyst coated on the monolith surface. At pH 7, nano-sized Ru particles with high BET surface area (112m2/g) and metal dispersion (23.5%) were formed uniformly on the monolith surface. Among the prepared monolith catalysts, the monolith catalyst prepared at pH 7 showed the highest CH4 conversion in NGSR. Despite the less amount of Ru metal coated on the metal monolith, the monolith catalyst showed a good catalytic performance equivalent to the 2wt% Ru/Al2O3 pellet catalyst due to the high availability of the Ru active metal in NGSR. It was also confirmed that the Ru catalyst layer coated on the FeCrAlloy monolith had good adhesion via ultrasonic vibration test.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Consecutive carbonylation and decarboxylation of glycerol with urea for
           the synthesis of glycidol via glycerol carbonate
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Yohana Kurnia Endah, Min Soo Kim, Jisik Choi, Jungho Jae, Sang Deuk Lee, Hyunjoo Lee
      Zn(OAc)2-catalyzed carbonylation and decarboxylation of glycerol and urea for the synthesis of glycidol were conducted at 150°C, 2.7kPa for 2h and 170°C, 2.0kPa for 1.5h, respectively. When the reaction conducted in a one-pot consecutive way, the yield of glycidol was 20%. However, when the formed zinc glycerolate (Zn(C3H6O3)) was filtered out after the carbonylation, the yield increased to 50% with respect to the amount of glycerol, whereas the yields of glycidol were very low when other zinc salts such as ZnCl2, ZnSO4 and Zn(NO3)2, were used as catalysts. The high catalytic activity of Zn(OAc)2 for this carbonylation and decarboxylation of glycerol and urea could be ascribed to the formation of Zn(NH3)x(OAc)2, which was determined from IR and TOF-SIMS studies.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Layered MWW zeolite-supported Rh catalysts for the hydrodeoxygenation of
           lignin model compounds
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Ji Sun Yoon, Taehee Lee, Jae-Wook Choi, Dong Jin Suh, Kangtaek Lee, Jeong-Myeong Ha, Jungkyu Choi
      The improved catalytic activity of Rh nanoparticles deposited on the swollen and pillared zeolites was observed in the hydrodeoxygenation (HDO) reactions of 1,3,5-trimethoxybenzene (1,3,5-TMB), a bulky lignin model compound, and guaiacol, one of the most frequently used lignin model compounds. As the high dispersion of metal nanoparticles increases HDO activity, the swelling/calcination and pillaring of crystalline MCM-22 zeolites increased the dispersion of Rh metal nanoparticles on the external surface area, and thus the corresponding HDO activity with respect to 1,3,5-TMB. On the contrary, although the mesopores in the amorphous MCM-41 and silica-alumina aerogel (SAA) supports accommodated higher Rh dispersion, overall, the resulting catalysts suffered from mass transfer limitation, and thus showed poor HDO reaction activity for 1,3,5-TMB. Finally, the Rh nanoparticles supported on the pillared zeolite showed the highest HDO activity for guaiacol, mainly due to the higher Rh dispersion and acid sites on the external surface among the zeolite-supported Rh catalysts.
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      PubDate: 2017-06-16T00:38:20Z
       
  • In-situ catalytic copyrolysis of cellulose and polypropylene over
           desilicated ZSM-5
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Yeojin Hong, Yejin Lee, Pouya Sirous Rezaei, Beom Sik Kim, Jong-Ki Jeon, Jungho Jae, Sang-Chul Jung, Sang Chai Kim, Young-Kwon Park
      The catalytic pyrolysis of biomass using zeolites as catalysts is a promising technique for the production of renewable chemicals and fuels. On the other hand, the low effective hydrogen to carbon ratio of biomass results in a hydrogen-deficient hydrocarbon pool inside the catalyst and in turn the formation of carbonaceous deposits, which causes catalyst deactivation. The catalytic copyrolysis of cellulose and polypropylene was conducted using ZSM-5, desilicated ZSM-5, and Al-SBA-15. The co-feeding of polypropylene with cellulose led to the enhanced formation of aromatic hydrocarbons due to the increased hydrogen content of feedstock and the interaction between the cellulose-derived furans and olefins obtained from polypropylene. Microporous zeolites resulted in the production of more aromatic hydrocarbons compared to mesoporous Al-SBA-15. In addition, desilicated ZSM-5 showed better catalytic performance than the parent ZSM-5 due to the presence of larger channels that facilitate the diffusion of compounds with a wider range of molecular sizes.
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      PubDate: 2017-06-16T00:38:20Z
       
  • Supported Fe2O3 nanoparticles for catalytic upgrading of microalgae
           hydrothermal liquefaction derived bio-oil
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Junjie Bian, Qi Zhang, Peng Zhang, Lijuan Feng, Chunhu Li
      Fe2O3/MCM-41 magnetic catalyst was fabricated in a facile, reproducible route and employed for hydrothermal liquefaction (HTL) of microalgae, deoxygenation upgrading of derived biocrude and its model compounds (palmitic acid and methyl palmitate) under the absence of hydrogen. The Fe2O3/MCM-41 catalyst was prepared by using a modified assembling method. Firstly, Fe2O3 nanoparticles were coated with a layer of SiO2, and then coated by silicoaluminate that was prepared by using natural clinoptilolite as an aluminum source. XRD, TEM, H2-TPR, and UV-VIS-NIR characterizations of the catalyst revealed that 10–30nm γ-Fe2O3 particles were well dispersed on the mesoporous support. Catalytic liquefaction of Chlorella derived the less complicated, higher HHV biocrude on Fe2O3/MCM-41 catalysts. In 320–350°C regime, palmitic acid conversion was improve by 14–29% with Fe2O3/MCM-41 catalyst. Under 342°C, methyl palmitate conversion was 56% and decarboxylation selectivity to pentadecane was improved to 62% on the catalyst in the sub-critical water. in situ DRIFTS reaction test demonstrated that decarboxylation initiation temperature lower was down to 240°C and the produced CO2 desorpted at 310°C. It could be deduced that CO2 desorption is rate limiting step, and the decreasing of pH played a negative role on the RCOO- active intermediate. The possible mechanism was proposed to confirm that tuning the adsorption strength of RCOO- and CO2 on the Fe2O3/MCM-41 catalyst should improve the pentadecane selectivity of palmitic acid decarboxylation.
      Graphical abstract image

      PubDate: 2017-06-16T00:38:20Z
       
  • Heteropolyacid catalysts for Diels-Alder cycloaddition of
           2,5-dimethylfuran and ethylene to renewable p-xylene
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Yanuar Philip Wijaya, Haryo Pandu Winoto, Young-Kwon Park, Dong Jin Suh, Hyunjoo Lee, Jeong-Myeong Ha, Jungho Jae
      The Diels-Alder cycloaddition of biomass-derived furans and subsequent dehydration are promising routes for the sustainable production of commodity chemicals such as p-xylene (PX). In this paper, we have investigated the catalytic performances of a range of phosphotungstic acid (HPW) and silicotungstic acid (HSiW) catalysts supported on various oxides, i.e., SiO2, Al2O3, TiO2 and ZrO2 and their structure-activity correlation in the conversion of 2,5-dimethylfuran (DMF) and ethylene to PX. The characterization studies of the catalysts using XRD, BET, Raman and 31P MAS-NMR spectroscopy reveal that all of the supported heteropolyacid (HPA) catalysts (except HPW/ZrO2) retain their Keggin structure on the surface of oxide supports. Results from ammonia- and n-propylamine-TPD studies show that all of the supported HPA catalysts possess well-defined Brønsted acid sites with the total acidity decreasing in the following order: HPA/SiO2 >HPA/Al2O3 >HPA/ZrO2 >HPA/TiO2. The conversion of DMF and the initial rate of PX production generally increase with an increase in the total acidity, with HPA/SiO2 being the most active catalyst. The turnover frequency of PX production for HPA/SiO2 is also considerably greater than those for the HPAs supported on Al2O3, ZrO2, and TiO2, which suggests that the higher activity of HPA/SiO2 is at least partly due to the enhanced strength of Brønsted acid sites. Both the silica-supported HSiW and HPW catalysts demonstrate remarkably high PX selectivity (82–85%) at high DMF conversion (91–94%) at 250°C after 6h reaction. The effects of reaction conditions such as acid loading, reaction temperature, and reaction time have also been investigated with the most active silica-supported HSiW catalysts to optimize the PX yield.
      Graphical abstract image

      PubDate: 2017-06-16T00:38:20Z
       
  • Structured catalysts for biofuels transformation into syngas with active
           components based on perovskite and spinel oxides supported on Mg-doped
           alumina
    • Abstract: Publication date: 15 September 2017
      Source:Catalysis Today, Volumes 293–294
      Author(s): Vladislav Sadykov, Svetlana Pavlova, Ekaterina Smal, Marina Arapova, Mikhail Simonov, Natalia Mezentseva, Vladimir Rogov, Tatiana Glazneva, Anton Lukashevich, Anne-Cecile Roger, Ksenia Parkhomenko, Andre van Veen, Oleg Smorygo
      For structured catalysts of biofuels transformation into syngas inexpensive and stable to sintering active components based upon Mg-doped γ-alumina with supported LaNi0.9Ru0.1O3 perovskite or MnCr2O4 spinel promoted by Ru+Ni were developed. Characterization of the surface features, reactivity, catalytic activity and routes of ethanol transformation on these catalysts demonstrated that suppression of support acidity, strong interaction of Ru-Ni alloy nanoparticles with manganese chromite layers on support and a high redox ability provide a high yield of syngas and stability to coking. The most promising active component (2wt% Ni+2wt% Ru)/MnCr2O4/10wt% MgO−γ-Al2O3 supported on microchannel heat-conducting CrAlO cermet plates demonstrated a high performance and stability to coking in the autothermal reforming of such reactive fuels as glycerol, anisol and turpentine oil.
      Graphical abstract image

      PubDate: 2017-06-16T00:38:20Z
       
 
 
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