for Journals by Title or ISSN
for Articles by Keywords
help

Publisher: Elsevier   (Total: 2571 journals)

 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

  First | 19 20 21 22 23 24 25 26     

The end of the list has been reached. Please navigate to previous pages.

  First | 19 20 21 22 23 24 25 26     

Journal Cover Catalysis Today
   [8 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0920-5861
     Published by Elsevier Homepage  [2571 journals]   [SJR: 1.283]   [H-I: 129]
  • Influence of the sol–gel preparation method on the photocatalytic NO
           oxidation performance of TiO2/Al2O3 binary oxides
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Meryem Polat , Asli M. Soylu , Deniz A. Erdogan , Huseyin Erguven , Evgeny I. Vovk , Emrah Ozensoy
      In the current work, TiO2/Al2O3 binary oxide photocatalysts were synthesized via two different sol–gel protocols (P1 and P2), where various TiO2 to Al2O3 mole ratios (0.5 and 1.0) and calcination temperatures (150–1000°C) were utilized in the synthesis. Structural characterization of the synthesized binary oxide photocatalysts was also performed via BET surface area analysis, X-ray diffraction (XRD) and Raman spectroscopy. The photocatalytic NO(g) oxidation performances of these binary oxides were measured under UVA irradiation in a comparative fashion to that of a Degussa P25 industrial benchmark. TiO2/Al2O3 binary oxide photocatalysts demonstrate a novel approach which is essentially a fusion of NSR (NO x storage reduction) and PCO (photocatalytic oxidation) technologies. In this approach, rather than attempting to perform complete NO x reduction, NO(g) is oxidized on a photocatalyst surface and stored in the solid state. Current results suggest that alumina domains can be utilized as active NO x capturing sites that can significantly eliminate the release of toxic NO2(g) into the atmosphere. Using either (P1) or (P2) protocols, structurally different binary oxide systems can be synthesized enabling much superior photocatalytic total NO x removal (i.e. up to 176% higher) than Degussa P25. Furthermore, such binary oxides can also simultaneously decrease the toxic NO2(g) emission to the atmosphere by 75% with respect to that of Degussa P25. There is a complex interplay between calcination temperature, crystal structure, composition and specific surface area, which dictate the ultimate photocatalytic activity in a coordinative manner. Two structurally different photocatalysts prepared via different preparation protocols reveal comparably high photocatalytic activities implying that the active sites responsible for the photocatalytic NO(g) oxidation and storage have a non-trivial nature.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Mesoporous metal oxide/silica composites with photocatalytic activity and
           magnetic response
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Xavier Collard , Adrien Comès , Carmela Aprile
      In this work, a novel class of mesoporous metal oxide/silica composites was prepared. Both ZnO and magnetite (Fe3O4) nanoparticles were embedded within the mesoporous silica architecture. The solids display a high surface area, narrow pore size distribution and a regular array of mesoporous hexagonal channels with long range ordering. All the materials were tested for the photodegradation of Rhodamine B and the catalytic performance compared with analogous mesoporous solids exclusively bearing ZnO nanoparticles in the silica framework. All the materials present good photocatalytic performance and magnetic response. The best catalyst containing 15wt% ZnO and 5wt% Fe3O4 particle loading, displays a higher turnover number than unstructured ZnO nanoparticles and commercial ZnO nanopowder and can be easily separated from the reaction mixture by simply applying a magnetic field as weak as the one generated by a common magnetic stirring bar.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Mixed iron–erbium vanadate NH3-SCR catalysts
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Marzia Casanova , Jordi Llorca , Amod Sagar , Karl Schermanz , Alessandro Trovarelli
      A series of SCR catalysts of mixed iron–erbium vanadates supported on TiO2–WO3–SiO2 were prepared and their reduction, textural, structural and morphological properties characterized by temperature programmed reduction, X-ray powder diffraction, B.E.T. methods and transmission electron microscopy. The influence of Fe/Er ratio in the vanadate as well as the effect of aging conditions on their activity in ammonia SCR reaction was investigated. SCR activity at medium/low temperature was found to correlate directly with the Fe loading of the catalyst, with supported FeVO4 resulting the most active material. This behavior might be correlated with the characteristics of Fe3+ OV5+ bond and the acidity of the VO moiety. Supported FeVO4 suffers a strong deactivation following thermal aging due to rutile formation in TiO2-based support and consequent collapse of surface area. The effect of Er is that of blocking transformation to rutile, thus enhancing activity after thermal treatment. Mixed composition Fe x Er1−x VO4 with x =0.5 represents the best compromise between activity and stability and are potential candidates for deNO x process when a higher stability is requested.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Cu on amorphous AlPO4: Preparation, characterization and catalytic
           activity in NO reduction by CO in presence of oxygen
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Mohamed Kacimi , Mahfoud Ziyad , Leonarda F. Liotta
      Cu/AlPO4 catalysts with Cu loading of 1, 2.5 and 5wt% were prepared by by Cu (II) ion complexes exchange. The catalysts were characterized, at different steps of treatment, by means of several techniques, such as UV–vis–NIR and ESR spectroscopy, TPR/TPO analysis, TEM investigations, butan-2-ol conversion. The NO reduction by CO in presence of oxygen under stoichiometric conditions was investigated. The NO reduction was 100% selective to N2. The most active catalyst was 5Cu/AlPO4 containing the highest amount of dispersed surface copper (II) species, reducible at low temperature.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Electrochemically-assisted NOx storage–reduction catalysts
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Willinton Yesid Hernandez , Abdelkader Hadjar , Anne Giroir-Fendler , Patricia Andy , Agnès Princivalle , Michaela Klotz , Ahmed Marouf , Christian Guizard , Caroline Tardivat , Céline Viazzi , Philippe Vernoux
      Supported noble-metal catalysts are extensively used in industry, particularly for car exhaust treatments. The challenge is to maximize the catalytic efficiency while minimizing the noble metal loading. Recent advances from the literature propose the use of electropromoted nanodispersed catalysts in order to assist catalytic reactions with electrochemical mechanisms: this type of catalyst design, inspired from fuel cells, combines electrochemical promotion of catalysis and high metallic active site availability. This paper explores whether electrochemical effects can improve the catalytic performances of nanodispersed NO x storage and reduction (NSR) catalysts deposited in the porosity of SiC mini-DPFs. NSR catalysts were elaborated employing Pt and Rh nanoparticles as electrodes, supported on yttria stabilized zirconia (YSZ) or gadolinium doped cerium oxide (GDC) nanoparticles (electrolyte), and used for NO x abatement in diesel exhaust gas conditions. Improved NO x removal efficiency was obtained. Comparison of YSZ (ionic conductor) and GDC (mixed ionic and electronic conductor) electrolytes showed that GDC-based catalytic nano-cells present the highest catalytic activities. A detailed analysis of the reaction products showed that electrochemical reactions can take place on nano-electrodes, in addition to catalytic reactions.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Influence of ceria loading on the NOx storage and reduction performance of
           model Pt–Ba/Al2O3 NSR catalyst
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Beñat Pereda-Ayo , Unai De La Torre , M. Pilar González-Marcos , Juan R. González-Velasco
      The influence of the addition of ceria on the NO x storage and reduction behaviour of model Ba–Pt/Al2O3 catalyst has been studied. Several 15%Ba–1.5%Pt–Ce/Al2O3 catalysts were prepared with increasing ceria loading, from 0 to 20.3wt.%. The prepared catalysts were characterized in terms of specific surface area (N2 adsorption–desorption at −196°C), platinum dispersion (H2-chemisorption), reducibility (H2-TPR) and acidity (NH3 adsorption–desorption experiments). The storage of NO x was followed by FTIR showing that low Ce loaded catalyst, i.e. Ba–Pt–4.5%Ce/Al2O3, was able to promote nitrate formation readily at low temperature (200°C), while nitrites were predominant for model Ba–Pt/Al2O3 and high loaded Ce catalyst, i.e. Ba–Pt–15.4%Ce/Al2O3. Ammonia oxidation experiments confirmed that Ce was able to oxidize NH3 into N2, the reaction extent increasing with temperature and Ce loading. The 4.5% Ce loaded catalyst achieved the highest NO x storage and reduction efficiency. The NO x storage capacity was increased with respect to the model Ba–Pt/Al2O3 catalyst due to the enhancement of NO oxidation conversion and due to the ability of Ce to take part as NO x storage material. On the other hand, NH3 emissions were reduced due to the participation of Ce in the oxidation of NH3 to N2. In contrast, high Ce loaded catalyst penalized NO x storage capacity and increased NH3 selectivity. The limited NO x storage capacity was in concordance with the low NO to NO2 conversion, which was attributed to a possible migration of CeO2 to form an atomic layer over Pt which ultimately covers and blocks its catalytic activity. The increased NH3 emission was attributed to a lower acidity of the doped catalyst which reduced the NH3 adsorption capacity.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • From the powder to the honeycomb. A comparative study of the NSR
           efficiency and selectivity over Pt–CeZr based active phase
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): L. Masdrag , X. Courtois , F. Can , B. Cartoixa , S. Raux , A. Frobert , D. Duprez
      The efficiency and the selectivity of a model platinum based catalyst supported on a modified ceria–zirconia oxide was evaluated in the NO x storage-reduction (NSR) process at four catalytic scales: powder, (0.5″×1.5″) flow-through monolith (FTM) system, small size (1″×2″) and full size (5.66″×10″) catalysed Diesel Particulate Filter (DPF). The washcoating of the active phase over FTM affects both the NO x storage properties and the NO x reduction step. The reduction step efficiency is especially decreased at low temperatures. It is associated with an incomplete regeneration of the storage sites and with a strong NO x desorption peak during the rich pulses of the NSR process for the FTM supported system. The NO x reduction selectivity is also strongly affected by the upscale, with an important N2O selectivity detected over FTM. The recorded NO x profiles during NSR cycles indicate a probable diffusion limitation. However, same trends were observed for both powder and FTM systems concerning the effect of the reductant mixture, for both NSR efficiency and N-compounds selectivity. After incorporation of the active phase in the porosity of the DPF, a sharp drop in NO x storage properties and subsequently in NSR efficiency are observed. Supplementary tests suggest that the diffusion from the platinum oxidizing sites to the storage sites is again very affected by the upscale. Finally, the engine bench tests confirm the low DeNO x activity of the DPF system.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Pt based catalytic coatings on poly(benzimidazole) micromonoliths for
           indoor quality control
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): A. Eguizábal , M.A. Urbiztondo , M.P. Pina
      Flexible polybenzimidazole (PBI) micromonoliths prepared by microtransfer moulding are herein proposed for the first time as G-S contactors for catalytic applications. Macroporous polymeric supports with 20μm as characteristic length and 70,000m−1 as S/V ratio have been coated by covalent linkage with Pt supported on amino functionalized ETS-10 crystals. As a proof of concept, the catalytic performance of the Pt modified PBI micromonoliths has been successfully demonstrated for indoor quality control, i.e. n-hexane removal at ppm level.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Effect of ionically conductive supports on the catalytic activity of
           platinum and ruthenium nanoparticles for ethylene complete oxidation
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Rima J. Isaifan , Elena A. Baranova
      The effect of the support nature on the catalytic activity of platinum and ruthenium nanoparticles is investigated for ethylene complete oxidation in the temperature range of 25–220°C. The nanoparticles (NPs) were deposited on ionically conductive supports: yttria-stabilized zirconia (YSZ) and samarium-doped ceria (SDC), and on non-ionically conductive supports: carbon black (C) and gamma-alumina (γ-Al2O3) to give ≤0.7wt% loading and an average particle sizes of 1.9–2.9nm depending on the support. The presence of O2− ionic conductivity greatly enhanced Pt and Ru catalytic activity compared with the same metals deposited on non-ionically conductive supports for C2H4 complete oxidation. The light off temperatures of Pt/SDC and Ru/SDC were 60°C and 70°C, respectively, whereas for the same NPs deposited on the high surface area carbon, the higher temperatures of 90°C for Pt/C and 130°C for Ru/C were obtained. The same trend was observed with activation energies, which were 22 and 35.1kJ/mol for Pt/SDC and Ru/SDC compared with 31 and 52.4kJ/mol for Pt/C and Ru/C, respectively. It is proposed that metal–support interaction (MSI), in particular, the electronic effect between NPs and ionic conductors is responsible for the high catalytic activity. The electronic effect is manifested by the oxygen ion exchange in the vicinity of the three-phase boundary similar to the electrochemical promotion mechanism, which is thermally self-induced in the case of Pt and Ru NPs deposited on SDC and YSZ.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Propene oxidation over palladium catalysts supported on zirconium rich
           ceria–zirconia
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Naoto Kamiuchi , Masaaki Haneda , Masakuni Ozawa
      Ceria–zirconia solid solution with the Ce/Zr ratio of 1/3 was prepared and used as support material for palladium catalysts. The palladium catalysts supported on the zirconium rich ceria–zirconia (Pd/CZ) were studied for propene oxidation reaction. In the activity tests, the influences of palladium loadings, pretreatment conditions, and reaction conditions were investigated. The catalytic activities of Pd/CZ with small amount of palladium component were strongly affected by the pretreatment conditions such as oxidative or reductive atmosphere. From IR measurements, it was suggested that the palladium species with high reducibility should be active for the complete oxidation of propene. The initial activities of Pd/CZ catalysts under the insufficient oxygen condition were equivalent to the activities under the stoichiometric condition due to the property of high oxygen storage capacity (OSC). It was revealed that CZ support helped the high dispersion of palladium oxide particles and its OSC property assisted the propene oxidation reaction.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Catalytic oxidation of chlorinated benzenes over V2O5/TiO2 catalysts: The
           effects of chlorine substituents
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Jian Wang , Xue Wang , Xiaolong Liu , Tingyu Zhu , Yangyang Guo , Hao Qi
      Chlorobenzene and 1,3,5-trichlorobenzene were chosen as model pollutants of chlorinated benzenes. Catalytic (kinetic) studies and in-situ FTIR experiments were conducted over V2O5/TiO2 catalysts to investigate the oxidation behavior of these two chlorinated benzenes. Different oxidation rates were observed in the catalytic study, which was ascribed to their molecular structural properties. Oxidation products and by-products were analyzed both on-line by GC and off-line by GC-MS, and slight difference was observed for these two chlorinated benzenes. Similar surface species on the catalysts could be easily identified in the in-situ FTIR curves. Supported by these results, a possible reaction pathway for catalytic oxidation of 1,3,5-trichlorobenzene was accordingly proposed. Noteworthy, the effect of the chlorinated degree on the catalytic oxidation was discussed, and it is well demonstrated that the structural and electronic factors of the chlorinated benzenes, and the influence of chlorine to the active vanadium sites, play important roles in the oxidation process.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Deactivation of a Pd/AC catalyst in the hydrodechlorination of chlorinated
           herbicides
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): E. Diaz , A.F. Mohedano , J.A. Casas , L. Calvo , M.A. Gilarranz , J.J. Rodriguez
      This work analyses the stability of a palladium on activated carbon (Pd/AC) catalyst in the ambient-like conditions hydrodechlorination (HDC) of the organochlorinated herbicides 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) as well as 2,4-dichlorophenol (2,4-DCP), a precursor in the synthesis of the second. Continuous long term experiments (100h time on stream) were performed at mild operating conditions (30°C, 1atm). The composition of the reaction effluents was analyzed and their ecotoxicity (Microtox) measured. In all cases, a significant decrease of ecotoxicity was observed due to the high dechlorination achieved. The Pd/AC catalyst maintained a constant activity along the HDC of 2,4-DCP, while it suffered an important deactivation in the HDC of 2,4-D and MCPA. From characterization of the fresh and used catalyst the adsorption/deposition of reaction byproducts on the active sites can be recognized as the main cause of deactivation. The use of activated carbon as support reduces the negative effect that the released chloride ions usually provoke on other HDC catalysts.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Catalytic wet air oxidation of ammonia over supported noble metals
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Cédric Lousteau , Michèle Besson , Claude Descorme
      Highly active and selective supported noble metal catalysts were studied in the catalytic wet air oxidation of ammonia. Under the applied reaction conditions (200°C, 50bar total pressure) only nitrites and molecular nitrogen were detected as primary products. Nitrates formed upon oxidation of nitrites. Platinum-based catalysts were shown to be the most active and among the most selective toward molecular nitrogen. The control of the oxygen coverage at the catalyst surface (metal–oxygen bond energy) was evidenced to have a key impact on both the activity and the selectivity. The retro-disproportionation and nitrous acid decomposition reactions appeared to impact the selectivity upon the conversion of nitrites to nitrates.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Nitrogen-doped carbon xerogels as catalysts for advanced oxidation
           processes
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): R.P. Rocha , J. Restivo , J.P.S. Sousa , J.J.M. Órfão , M.F.R. Pereira , J.L. Figueiredo
      Nitrogen-doped carbon xerogels were tested as metal-free catalysts for the mineralization of oxalic acid by ozonation and by wet air oxidation. Oxalic acid was completely mineralized in less than 45min in wet air oxidation, but complete conversion was never achieved with ozone. Some general trends were observed, and correlations between the catalytic activity and the surface chemistry of the carbon materials were established. In particular, the apparent reaction rate constants for both processes correlate with the concentration of surface nitrogen. The effect of N-doping is particularly effective in CWAO, the rate constants increasing by two orders of magnitude in comparison with the nitrogen-free material. With ozone, oxidation of oxalic acid may occur both in the liquid phase (homogeneous reaction) and on the catalyst surface, while wet air oxidation appears to proceed mainly on the carbon surface.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Fixed-bed catalytic wet peroxide oxidation of phenol with titania and
           Au/titania catalysts in dark
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Michael Ferentz , Miron V. Landau , Roxana Vidruk , Moti Herskowitz
      It was established that nanostructured TiO2 with crystal size in range of 4.5–30nm display stable operation in phenol CWPO in dark [PhOH=200ppmw] yielding 52–76% TOC conversion in a fixed-bed reactor at pH=2.5, T =80°C and LHSV=3.8h−1. Deposition of ∼3wt.% of Au nanoparticles increases the catalytic activity of TiO2 in CWPO of phenol defined as pseudo-first-order rate constant of substrate mineralization by a factor of 2.0–2.8 depending on Au crystal size. Small 3–4nm Au nanoparticles aggregate at reaction conditions with complete deactivation of Au component. Larger 7–8nm Au nanoparticles are stable against aggregation and deactivation. No leaching of Ti and Au was detected in runs with duration up to 300h. The CWPO with both Au and TiO2 catalysts proceeds according to radical mechanism mostly in the part of catalysts layer where H2O2 is completely decomposed. At proper operation conditions TiO2 and Au/TiO2 catalysts allow reaching >95% mineralization of phenol and stable operation.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Sonocatalytic degradation of oxalic acid in the presence of oxygen and
           Pt/TiO2
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Tony Chave , Nathalie. M. Navarro , Patrick Pochon , Nina Perkas , Aharon Gedanken , Sergey I. Nikitenko
      In order to treat aqueous effluents containing organic pollutants, several techniques can be considered depending on the organic compound concentration. Sonochemistry appears to be a promising solution to answer water remediation issue. In fact, when submitted into a liquid, ultrasound can induce the nucleation, growth, and violent collapse of vapor/gas filled bubbles. However, despite the extreme local conditions observed during acoustic cavitation, using ultrasound alone is efficient only at low concentration in organic pollutants. In the present study, 0.05M oxalic acid degradation kinetics were followed at 40°C under various conditions, in presence or not of Pt/TiO2 catalyst under silent conditions or ultrasound at 20 and 360kHz. Experiments were achieved under controlled atmosphere and comparison between argon, Ar/O2 (20vol% O2) and pure O2 conditions was performed. Oxidation rate increase of oxalic acid was measured under Ar/O2 atmosphere in presence of Pt/TiO2 catalyst due to strong dispersion effect of both low and high ultrasonic frequency and formation of chemically active species by sonolysis. High frequency ultrasonic irradiation under Ar/O2 atmosphere gives the highest kinetic increase compared to silent conditions with oxalic acid degradation rate around 13μmolmin−1 at 40°C with 2gL−1 of 3wt% Pt on P25 TiO2 catalyst.


      PubDate: 2014-11-23T08:12:13Z
       
  • The influence of the textural properties of ZnO nanoparticles on
           adsorption and photocatalytic remediation of water from pharmaceuticals
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): J. Choina , A. Bagabas , Ch. Fischer , G.-U. Flechsig , H. Kosslick , A. Alshammari , A. Schulz
      The pollution of surface, ground and drinking water by pharmaceuticals in low concentration is a new emerging problem. Zinc oxide nanoparticles of different sizes have been characterized by XRD, TEM, UV–Vis/DRS and N2 adsorption–desorption measurements. The photocatalytic degradation of low concentrated pharmaceuticals tetracycline and ibuprofen at low photocatalyst amount and at low photocatalyst to substrate mass ratio (cat-to-sub ratio) have been investigated in details. The influence of pH value, ZnO and drug concentrations as well as the contribution of adsorption has been deeply studied. The formation of intermediates has been investigated by electrospray ionization-time of flight-mass spectroscopy. Zinc oxide is known to promote the formation of reactive OH radicals and therefore is of special interest for the photocatalytic remediation of water from pharmaceuticals. Smaller particles are more active than larger ones due to increased specific surface area and adsorption. Interestingly, adsorption of the drug on ZnO is markedly improved at low concentration (<5ppm), leading to the different degradation behaviors, compared to ppm concentrated solution.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Photodegradation of benzene, toluene and xylenes under visible light
           applying N-doped mixed TiO2 and ZnO catalysts
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): A.M. Ferrari-Lima , R.P. de Souza , S.S. Mendes , R.G. Marques , M.L. Gimenes , N.R.C. Fernandes-Machado
      N-doped TiO2/ZnO catalysts were prepared by sol–gel technique and calcined at 380 and 500°C. Its photocatalytic activity was evaluated in the photodegradation of benzene, toluene and xylenes (BTX) under visible-LED light and compared with the undoped TiO2/ZnO activity. The amount of doped nitrogen was found to be 0.64at%. Concentrations of BTX were analysed by gas chromatography applying the headspace technique. The NTiO2/ZnO catalyst calcined at 500°C led to reductions of benzene, toluene and xylenes concentrations greater than 80wt% after 120min of irradiation. The photocatalytic reactions followed the first order kinetics.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Effects of heat and peroxide treatment on photocatalytic activity of
           titanate nanotubes
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Boštjan Erjavec , Renata Kaplan , Albin Pintar
      The influence of structural, morphological and surface properties on photocatalytic activity of pristine and modified titanate nanotubes was carefully described and discussed in the following study. Titanate nanotubes (TNTs) were prepared via alkaline hydrothermal synthesis route followed by acid washing at ambient conditions. The resulting high specific surface area nanotubular solids were further modified by two distinguished post-treatments: (i) heat-treatment in the temperature range from 300 to 700°C, and (ii) peroxide-treatment at room temperature. Bisphenol A (BPA), a well-known endocrine disrupting compound (EDC), was selected as a testing molecule to evaluate the photodegradation potency of the modified TNTs. The resulting BPA and TOC removals confirmed that crystallinity and BET surface area of examined heat-treated solids play a crucial role in governing the photooxidation reaction. Regarding the peroxide-treated TNTs, a nearly three-fold improvement in BPA removal was attained in comparison to the pristine TNTs, which can be attributed to the redox reaction of surface titanium(IV) peroxo groups. However, the exposure of anatase-based samples to the H2O2 medium resulted in deteriorated photocatalytic oxidation of the model compound, due to recovery of surface Ti3+ defect sites, leading to increased e−–h+ recombination and decreased oxygen adsorption. In addition, a carbon-based elemental analysis of the heat-treated TNTs (TNT_500) and standard TiO2 P25 stressed the potential of tailor-made crystalline TNTs to be applied as photocatalysts for long-term removal of aqueous organics, due to low accumulation of carbonaceous deposits during the photodegradation runs.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A




      PubDate: 2014-11-23T08:12:13Z
       
  • Surface fluorination on TiO2 catalyst induced by photodegradation of
           perfluorooctanoic acid
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Sara Gatto , Maurizio Sansotera , Federico Persico , Massimo Gola , Carlo Pirola , Walter Panzeri , Walter Navarrini , Claudia L. Bianchi
      The photoabatement of perfluorooctanoic acid in aqueous solution has been performed with a commercial nano-sized TiO2-based photocatalyst content of 0.66g/L under an UV irradiation of 95W/m2. PFOA degradation intermediates were investigated by HPLC–MS and 19F-NMR analysis. Evidences of a degradation mechanism based on two competitive pathways are discussed: photo-redox and β-scission pathways. Shorter perfluorinated carboxylic acids, C n F2n+1COOH (n =1–6), as expected degradation intermediates, were identified and their concentration trends over time were determined. The apparent pseudo-first order kinetic constant expressed as rate of PFOA disappearance was also measured: k app 0.1296h−1. The influence of fluoride ions on TiO2 surface was analyzed by XPS technique, revealing a surface modification that affects the performances of the catalyst.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Contents list
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A




      PubDate: 2014-11-23T08:12:13Z
       
  • Preface
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): M. Besson , A. Pintar , P. Vernoux



      PubDate: 2014-11-23T08:12:13Z
       
  • Fabrication of high-sensitivity palladium loaded tungsten trioxide
           photocatalyst by photodeposite method
    • Abstract: Publication date: 1 March 2015
      Source:Catalysis Today, Volume 241, Part A
      Author(s): Yuka Sakai , Asami Shimanaka , Masahiko Shioi , Shigeru Kato , Shigeo Satokawa , Toshinori Kojima , Akihiro Yamasaki
      Pd-supported tungsten oxide (Pd/WO3) was prepared by photodeposition by using black light. X-ray diffraction and X-ray photoelectron spectroscopy analyses of Pd/WO3 confirmed the presence of Pd(0). Pd(0) was uniformly dispersed on the surface of WO3. The optimum Pd amount for the degradation of aqueous methylene blue (MB) was 0.5wt%, and the photocatalytic activity in this case was 27 times higher than that of pure WO3. The optimum Pd amount for the decomposition of gaseous acetaldehyde was 0.1wt%, and the photocatalytic activity using this amount of Pd was 5.9 times greater than that for pure WO3. Pd as a support improved the charge separation efficiency. Further, hydrogen peroxide was produced on the Pd(0) side of the photocatalyst because of the movement of photoexcited electrons, and it contributed significantly to MB degradation. Moreover, electrons produced with MB moved to the Pd side, and contributed to hydrogen peroxide production. Only photocatalytic degradation contributed to acetaldehyde decomposition, while both photocatalytic and self-sensitized degradation contributed to MB degradation. The Pd/WO3 sample containing the optimal amount of Pd acted as an effective photocatalyst, despite the difference between the optimal Pd amount required for acetaldehyde decomposition and that for MB degradation.
      Graphical abstract image

      PubDate: 2014-11-23T08:12:13Z
       
  • Synergism and photocatalytic water splitting to hydrogen over M/TiO2
           catalysts: Effect of initial particle size of TiO2
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): S. Bashir , A.K. Wahab , H. Idriss
      In order to study the effect of anatase/rutile phases of TiO2 on the photo-catalytic production of hydrogen (often invoked as synergism) two series of Pt/TiO2 materials were prepared. The initial phase of TiO2 in both series is anatase but their particle size is different. In one case the mean particle size of TiO2 is ca. 15–20nm (nano) and in the other it is ca. 100nm (micro). Before the deposition of Pt, the two semiconductors (nano and micro) were heated to elevated temperatures to obtain partial (and total) transformation of the anatase phase to the rutile phase (UV–vis, XRD, XPS-valence band). On this differently prepared mixed phases Pt was deposited (ca. 1at.%; corrected XPS Pt4f/Ti2p=ca. 0.05) and each series was tested for the photocatalytic production of hydrogen from water in presence of ethanol (5vol.%) as a sacrificial agent (under identical conditions). Based on rates per unit mass no synergism for hydrogen production was seen in both cases; this is in part due to the decrease in the BET surface area during the phase transformation. However, strong synergism was observed for hydrogen production rates per unit area when the initial starting semiconductor was anatase nano (while no synergism seen in the case of the micro crystals). Maximum rate observed was in the 10–30% rutile range. Possible reasons for these differences are discussed.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Active gold-ceria and gold-ceria/titania catalysts for CO oxidation: From
           single-crystal model catalysts to powder catalysts
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): José A. Rodriguez , Rui Si , Jaime Evans , Wenqian Xu , Jonathan C. Hanson , Jing Tao , Yimei Zhu
      CO oxidation was studied on model and powder catalysts of Au-CeO2 and Au-CeO x /TiO2. Phenomena observed in Au-CeO2(111) and Au-CeO2/TiO2(110) provided useful concepts for designing and preparing highly active and stable Au-CeO x /TiO2 powder catalysts for CO oxidation. Small particles of Au dispersed on CeO2(111) displayed high catalytic activity, making Au-CeO2(111) a better CO oxidation catalyst than Au-TiO2(110) or Au-MgO(100). An excellent support for gold was found after depositing nanoparticles of ceria on TiO2(110). The CeO x nanoparticles act as nucleation centers for gold, improving dispersion of the supported metal and helping in the creation of reaction sites efficient for the adsorption of CO and the dissociation of the O2 molecule. High-surface area catalysts were prepared by depositing gold on ceria nanorods and CeO x /TiO2 powders. The samples were tested for the low-temperature (10–70°C) oxygen-rich (1%CO/4%O2/He) CO oxidation reaction after pre-oxidation (20%O2/He, 300°C) and pre-reduction (5%H2/He, 300°C) treatments. Synchrotron-based operando X-ray diffraction (XRD) and X-ray absorption (XAS) spectroscopy were used to study the Au-CeO2 and Au-CeO x /TiO2 catalysts under reaction conditions. Our operando findings indicate that the most active phase of these catalysts for low-temperature CO oxidation consist of small particles of metallic Au dispersed on CeO2 or CeO x /TiO2.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Renewable energy and fuel production over transition metal oxides: The
           role of oxygen defects and acidity
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Zhong He , Xianqin Wang
      Reduction of carbon dioxide emissions and humanity's reliance on fossil fuels by generation of renewable energy and fuel is a potentially effective solution. In this context, the role of oxygen defects and acidity of transition metal oxides during steam reforming of ethanol and hydrodeoxygenation of carboxylic acids are discussed. It is found that steam reforming of ethanol requires more oxygen defects with high mobility but less acidity while biofuel production by hydrodeoxygenation requires relatively strong acidity and/or moderate metal–oxygen bond strength in the transition metal oxides. The finding provides new opportunities for revealing the relationship of structures and catalytic performance, and insights in the rational design of transition metal oxides as catalysts or supports for renewable energy and fuel production.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Designing a new generation of catalysts: Water gas shift reaction example
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Jesus Graciani , Javier Fdez. Sanz
      In the present work, we briefly review the main conclusions harvested until now in our previous works regarding the WGS reaction together with new results, examples and key ideas for designing WGS catalysts. Most of the ideas and general statements included in the present work may be also very useful for designing catalysts for other reactions that require the presence and combination of metals and oxides. Particularly relevant is the description of the nature, properties and future implications of the nano-mixed-oxide phase “naturally” generated at the interface of some systems which modifies and activates the whole catalytic process. Co-supporting metal and reducible-oxide nanoparticles on another oxide-support in systems with a strong oxide–oxide interaction opens the door to a new family of highly active catalysts suitable for reactions such as water gas shift, CO oxidation or methanol synthesis, among others.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • The role of exposed silver in CO oxidation over MgO(001)/Ag(001) thin
           films
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Franziska Ringleb , Yuichi Fujimori , Matthew A. Brown , William E. Kaden , Florencia Calaza , Helmut Kuhlenbeck , Martin Sterrer , Hans-Joachim Freund
      The reactivity of MgO(001) films deposited on Ag(001) and Mo(001) in CO oxidation as a function of oxide film thickness was investigated experimentally at ambient pressure reaction conditions. MgO films grown on Mo(001) were found to be inactive in CO oxidation, whereas activity enhancement with decreasing oxide film thickness was observed for MgO(001)/Ag(001). In situ infrared and post-reaction X-ray photoemission data showed that ultra-thin MgO films interact much more strongly with the reactants and residual water than bulk-like MgO. Poisoning of the MgO surfaces by the resultant accumulation of carbonate and hydroxyl species is suggested to inhibit the reactivity in CO oxidation. Detailed investigations of the surface structure of MgO(001)/Ag(001) films indicate that silver ad-islands on Ag(001), which are formed during MgO growth, are responsible for the enhancement of CO oxidation activity over ultrathin MgO(001)/Ag(001) films.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Effect of nature of ceria supports on the growth and sintering behavior of
           Au nanoparticles
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Yinghui Zhou , Erik Wayne Peterson , Jing Zhou
      The growth and sintering behavior of gold have been investigated on reducible CeO x (111) (1.5< x <2) thin films with controlled oxidation states under ultrahigh vacuum conditions. Scanning tunneling microscopy studies reveal that Au experiences the transition of the three-dimensional particle growth on the fully oxidized ceria surface to the two-dimensional growth on the reduced ceria at room temperature. X-ray photoelectron spectroscopy data show a positive shift of up to 0.7eV for the Au 4f core level with the increase of the degree of Ce reduction in the film, which is attributed to the Au particle size effect. Upon heating to higher temperatures, Au agglomerates to form large particles with a well-defined hexagonal shape. The temperature of transformation depends on the cerium oxidation states. These Au particles exhibit the 4f binding energies that are characteristics for the bulk gold. Instead of nanoparticles, layered films can be formed on the reduced ceria surface when Au is deposited at 500K. Our study demonstrates that the structure of Au and correspondingly the interfaces between Au and ceria can be controlled by varying the nature of ceria surfaces as well as annealing/deposition temperatures. Such study can play a role in the understanding of the structure–reactivity relationship of ceria-supported gold catalysts.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Pt–CeOx thin film catalysts for PEMFC
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): R. Fiala , M. Vaclavu , A. Rednyk , I. Khalakhan , M. Vorokhta , J. Lavkova , V. Potin , I. Matolinova , V. Matolin
      Platinum is the mostly used element in catalysts for fuel cell technology, but its high price limits large-scale applications. Platinum doped cerium oxide represents an alternative solution due to very low loading, typically few micrograms per 1cm2, at the proton exchange membrane fuel cell (PEMFC) anode. High efficiency is achieved by using magnetron sputtering deposition of cerium oxide and Pt of 30nm thick nanoporous films on large surface carbon nanoparticle substrates. Thin film techniques permits to grow the catalyst film characterized by highly dispersed platinum, mostly in ionic Pt2+ state. Such dispersed Pt species show high activity and stability. These new materials may help to substantially reduce the demand for expensive noble-metals in catalytic applications. We measured Pt–CeO x thin film anode catalyst activity in a hydrogen PEMFC and compared it with performance of a standard reference cell. Photoelectron spectroscopy was used to investigate chemical composition of Pt–CeO x induced by the catalyst interaction with hydrogen. Nanostructured character of the catalyst was confirmed by electron microscopy.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Isolation and characterization of formates on CeOx–CuyO/Cu(111)
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Kumudu Mudiyanselage , Ashleigh E. Baber , Zongyuan Liu , Sanjaya D. Senanayake , Darío J. Stacchiola
      Formate species have been proposed to be either critical intermediates or spectators in the water–gas shift (WGS) and methanol synthesis processes. CeO x –Cu y O/Cu(111) has been shown to be a very active inverse catalyst for the WGS reaction. We present here the study of formate species obtained from the deprotonation of formic acid (HCOOH) on the inverse catalysts. Exposure of CeO x –Cu y O/Cu(111) to HCOOH at 300K leads to the formation of formates on both ceria and Cu sites. The formates isolated on CeO x –Cu y O/Cu(111) systems cannot be hydrogenated even at a pressure of 200Torr H2 at 300–350K. The formate species localized on ceria sites are thermally more stable than those on Cu sites, and the thermal decomposition of all of the formates occurs by dehydrogenation releasing CO2 and H2. Evidence of reverse spillover of formates from the oxide to the metal was observed on CeO2−x /Cu(111) inverse catalysts.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • Contents list
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B




      PubDate: 2014-11-15T07:59:53Z
       
  • Oxides in Catalysis
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Dario Stacchiola , Martin Sterrer , Sanjaya D. Senanayake , Ping Liu



      PubDate: 2014-11-15T07:59:53Z
       
  • Determination of the surface electronic structure of Fe3O4(111) by soft
           X-ray spectroscopy
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B
      Author(s): Sarp Kaya , Hirohito Ogasawara , Anders Nilsson
      The determination of surface terminations in transition metal oxides is not trivial because many structural configurations could be possible. They exhibit various terminations depending on the oxidation states of metal cations exposed to the surface. Fe3O4 is one example in which octahedrally and tetrahedrally coordinated Fe2+ and Fe3+ cations coexists with oxygen anions. For the identification of the surface termination of Fe3O4(111) grown on Pt(111) we have employed surface sensitive synchrotron based X-ray photoelectron and absorption spectroscopy. It has been shown that the topmost surface is octahedrally coordinated Fe3+ rich.
      Graphical abstract image

      PubDate: 2014-11-15T07:59:53Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part B




      PubDate: 2014-11-15T07:59:53Z
       
  • Bio-based substances from urban waste as auxiliaries for solar
           photo-Fenton treatment under mild conditions: Optimization of operational
           variables
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): J. Gomis , L. Carlos , A. Bianco Prevot , A.C.S.C. Teixeira , M. Mora , A.M. Amat , R. Vicente , A. Arques
      The use of soluble bio-based organic substances (SBO) obtained from urban wastes to expand the pH region where the photo-Fenton process can be applied has been investigated in this study. For this purpose, a mixture of six pollutants, namely acetaminophen, carbamazepine, amoxicillin, acetamiprid, clofibric acid and caffeine, at an initial concentration of 5mgL−1 each, has been employed. Surface response methodology, based on the Doehlert matrix, has shown to be a useful tool to determine the effect of pH (in the range 3–7), concentration of SBO (15–25mgL−1) and iron (2–6mgL−1) on the performance of the photodegradation of the studied pollutants, measured by their half-life. Results indicate that, at high SBO concentration, the optimum pH shifts in most cases to a higher value (between 3 and 4) and that a significant loss of efficiency of the process was only observed at pH values above 5. An iron concentration of 4–5mgL−1 and an amount of SBO of 19–22mgL−1 have been determined to be the optimal conditions for the degradation of most of the studied pollutants at pH=5.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Disinfection of urban effluents using solar TiO2 photocatalysis: A study
           of significance of dissolved oxygen, temperature, type of microorganism
           and water matrix
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Irene García-Fernández , Isabel Fernández-Calderero , María Inmaculada Polo-López , Pilar Fernández-Ibáñez
      The enhancement of current technologies used to treat polluted water is one of the most important challenges in water research. The application of physico-chemical treatments could reduce the load of chemical and biological pollutants present in WW reducing the pressure over water requirements, allowing the reclaim of the treated water. Advanced Oxidation Processes (AOPs) and, in particular, photocatalysis using titanium dioxide (TiO2) have shown a great potential for chemicals removal as well as for pathogens reduction in water. Moreover, the use of solar Compound Parabolic Collectors (CPC) reactors has been also shown to be very effective for water treatment purpose by solar photocatalysis. Nevertheless, the effects of some key parameters in photocatalytic disinfection have not been already investigated at pilot scale in solar reactors; like dissolved oxygen concentration, water temperature, water matrix composition and the type of microorganism. The roles of these parameters in photocatalytic processes are individually known for chemicals degradation, but their relative significance in water photocatalytic disinfection has been never studied at pilot scale. The aim of this work was to investigate the influence of these parameters on the disinfection efficiency using a solar 60L-CPC reactor with suspended TiO2 (100mg/L). The following variables were experimentally evaluated: injection of air in the reactor (160L/h); different controlled temperatures (15, 25, 35 and 45°C); two very different models of water pathogen, Escherichia coli (model of fecal water contamination) and Fusarium solani spores (a highly phytopathogenic fungus); and the chemical composition of the water comparing urban WW effluents (UWWE) and simulated urban WW effluent (SUWWE). The increase of water temperature (from 15 to 45°C) had a benefit on the disinfection rate for both pathogens in all the experimental conditions evaluated. The air injection led to an important enhancement on the inactivation efficiency, which was stronger for F. solani spores, the most resistant microorganisms to TiO2 photocatalysis. The composition of the water matrix significantly affected the efficiency of the photocatalytic treatment, showing a better inactivation rate in SUWWE than for UWWE.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • TiO2 photocatalysis of 2-isopropyl-3-methoxy pyrazine taste and odor
           compound in aqueous phase: Kinetics, degradation pathways and toxicity
           evaluation
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): M. Antonopoulou , I. Konstantinou
      In recognition of the growing demand regarding the control of undesired taste and odor (T&O) problems in natural water resources, the photocatalytic degradation of 2-isopropyl-3 methoxy pyrazine (IPMP), a common metabolite of soil actinomycetes which contributes a rotten vegetable odor to water, was investigated under simulated solar irradiation. Under the studied conditions (C =10mgL−1, C TiO 2 = 1 00  mg L − 1 and I =600Wm−2), 95% of IPMP was removed within 20min of irradiation. The reaction intermediates were completely mineralized to CO2 and the nitrogen was predominantly released as NH4 + ions after 240min irradiation. The major transformation products of TiO2 photocatalysis of IPMP have been determined by the use of high resolution accurate liquid chromatography–orbitrap mass spectrometry as well as gas chromatography–mass spectrometry (GC–MS) techniques. Hydroxylation of the isopropyl and methoxy groups has been identified as the main reaction pathway. Scavenging experiments indicated the important role of HO•, h+ and O2 •− in the photocatalytic process. Toxicity assessment revealed the efficiency of the photocatalytic treatment to achieve almost complete detoxification of the irradiated solution.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Ionic liquids breakdown by Fenton oxidation
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Macarena Munoz , Carmen M. Domínguez , Zahara M. de Pedro , Asunción Quintanilla , Jose A. Casas , Juan J. Rodriguez
      Fenton oxidation has proved to be an efficient treatment for the degradation of ionic liquids (ILs) of different families viz. imidazolium, pyridinium, ammonium and phosphonium, in water. The intensification of the process, defined as the improvement on the efficiency of H2O2 consumption, by increasing the temperature is necessary to avoid high reaction times and the need of large excess of H2O2. In this work, temperatures within the range of 70–90°C have been used, which allowed an effective breakdown of the ILs tested (1gL−1 initial concentration) with the stoichiometric amount of H2O2 and a relatively low Fe3+ dose (50mgL−1). Under these conditions conversion of the ILs was achieved in less than 10min, with TOC reductions higher than 60% upon 4h reaction time, except for the phosphonium IL. The remaining TOC corresponded mainly to short-chain organic acids. The treatment reduced substantially the ecotoxicity up to final values below 0.01TU in most cases and a significant improvement of the biodegradability was achieved. Upon Fenton oxidation of the four ILs tested hydroxylated compounds of higher molecular weight than the starting ILs, fragments of ILs partially oxidized and short-chain organic acids were identified as reaction by-products. Reaction pathways are proposed.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Contents list
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A




      PubDate: 2014-10-30T09:52:42Z
       
  • Effect of photocatalysis on the transfer of antibiotic resistance genes in
           urban wastewater
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): P.S.M. Dunlop , M. Ciavola , L. Rizzo , D.A. McDowell , J.A. Byrne
      The widespread use and abuse of antibiotics in human and animal medicine has produced a reservoir of antibiotic resistant bacteria (ARB) which persist and spread within many environments including natural and wastewater systems. This paper reports the first investigation into the effect of advanced oxidation technologies, photocatalysis, on the potential to induce antibiotic resistant gene transfer within sub-lethally injured ARB. The impact of photocatalytic disinfection (PCD) treatments on three strains of Escherichia coli, an antibiotic sensitive strain (K12) and two antibiotic resistant strains (J-53R (rifampicin resistant) and HT-99 (chloramphenicol resistant), within an immobilised titanium dioxide stirred tank reactor. When suspended in distilled water, viable cell numbers (CFUmL−1) of both ARB declined from 3log10 to 0.5log10 with 180min PCD treatment. However, subsequent recovery to 3log10 of both ARB was observed during post treatment incubation at 37°C for 24h. No E. coli K12 were recovered immediately after 150min treatment, or after post treatment incubation. These observations suggest that the ARB are less sensitive to the oxidative stresses involved in PCD treatment than the antibiotic sensitive strain. Gene pair conjugant numbers in PCD treated mixtures of J-53R and HT-99 cells (a 9:1 ratio) were calculated to be four-fold greater than in the (no treatment) control experiments. Both surviving bacterial cell numbers and conjugant pair numbers were lower when ARB were PCD treated in final effluent from an urban wastewater treatment plant. In conclusion, the results of this study confirm the efficacy of PCD, but also highlight the importance of applying PCD treatment “long enough” to avoid post treatment recovery from sub-lethal injury and the highly undesirable transfer of antibiotic resistant genes amongst bacteria during wastewater treatment.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Kinetic modelling of Escherichia coli inactivation in a photocatalytic
           wall reactor
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Javier Marugán , Rafael van Grieken , Cristina Pablos , M. Lucila Satuf , Alberto E. Cassano , Orlando M. Alfano
      A kinetic model of the photocatalytic inactivation of Escherichia coli in an annular wall reactor is presented. The model is based on a reaction scheme that involves a series of events in which bacteria are progressively damaged and eventually led to cell lysis. The model explicitly takes into account radiation absorption effects. Photocatalytic inactivation experiments were carried out in a photoreactor operated in a closed recirculating circuit with a reservoir tank and irradiated with a 6W black light lamp situated in the axis of the reactor. Immobilization of TiO2 Aeroxide P25 has been carried out by the dip-coating procedure onto the inner-tube wall of the annular reactor. Experimental results for different TiO2 layer thicknesses were used to estimate the kinetic parameters of the model. Good agreement between model predictions and inactivation experiments was achieved in the whole range of TiO2 thicknesses studied.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • FeOOH and derived phases: Efficient heterogeneous catalysts for clofibric
           acid degradation by advanced oxidation processes (AOPs)
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Shailesh S. Sable , Pallavi P. Ghute , Pedro Álvarez , Fernando J. Beltrán , Francesc Medina , Sandra Contreras
      In this study the degradation of an aqueous solution of clofibric acid was investigated during catalytic ozonation and Fenton-like process with FeOOH – derived catalysts. From the different calcination temperatures tested, it has been observed that the most active catalyst is the commercial FeOOH calcined at 200°C, when maghemite and hematite are the predominant phases obtained. The best result, at room temperature, for CFA mineralization was observed over 0.5wt% Pd on FeOOH (calcined at 200°C) among all tested catalysts, achieving 68% and 81% mineralization degree, in 2h and 6h, respectively, in catalytic ozonation and 66% and 71% of mineralization degree within 2h and 6h, respectively for Fenton process. The efficiency of the Fenton-like process is enhanced at higher temperature (40–60°C), reaching a mineralization degree up to 82% in 6h. Furthermore, Pd impregnation on FeOOH increased the catalyst stability.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Introduction
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Dionissios Mantzavinos , Ioannis Poulios , Pilar Fernández-Ibañez , Sixto Malato



      PubDate: 2014-10-30T09:52:42Z
       
  • Catalytic ozonation of ibuprofen with ultrasound and Fe-based catalysts
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Asu Ziylan , Nilsun H. Ince
      The study is about a novel method of decomposing and mineralizing the emerging contaminant ibuprofen (IBP) by catalytic ozonation using catalysts such as high-frequency ultrasound (US) and soluble/insoluble Fe-bearing species. Preliminary experiments with single processes were run to select the optimum values of IBP concentration, O3 flow rate and specific US power as 50μM, 12mgmin−1, and 0.23WmL−1, respectively. It was found that the most critical operation parameter was pH, as it controlled the mass transfer and decomposition of O3, as well as the diffusion of solutes from the bulk solution to the gas–liquid and solid–liquid interfaces. As such, ozonation and sonication alone were most effective at pH 9.0 and 3.0, respectively owing to the higher rate of OH production and gas–liquid interfacial reactions at these conditions. Catalytic ozonation with Fe-bearing species but no ultrasound was most effective at pH 6.5, with a maximum degree of IBP decay in the presence of FeSO4. Catalytic ozonation with ultrasound and solid particles was effective at pH 6.5, but maximum degree of oxidation/mineralization was obtained with nanoparticles of zero-valent iron (ZVI) at pH 3.0 (100%, 58%). The synergy of US+ZVI at acidic pH was attributed to: (i) the massive surface areas enriched with extensive reaction and nucleation sites, (ii) the role of reactive Fe (furnishing out from the metal core onto the catalyst surface) and reactive oxygen species as promoters of Fenton-like reactions, and (iii) the contribution of hydrodynamic shear forces to continuous enhancement and cleaning of the catalytic surfaces.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • IFC - Editorial Board
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A




      PubDate: 2014-10-30T09:52:42Z
       
  • Effect of activated carbon surface chemistry on the activity of ZVI/AC
           catalysts for Fenton-like oxidation of phenol
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): S.A. Messele , O.S.G.P. Soares , J.J.M. Órfão , C. Bengoa , F. Stüber , A. Fortuny , A. Fabregat , J. Font
      Activated carbons with different amounts of surface oxygenated groups were used as adsorbents or supports for zero-valent iron (ZVI) catalyst and tested in phenol adsorption and catalytic wet peroxide oxidation, respectively. The results revealed that the surface chemistry of the support plays an important role in phenol adsorption and in the catalytic performance of the respective iron-supported catalysts. ZVI is active when the support has only a limited amount of oxygenated groups on the surface. The presence of acidic oxygenated surface groups is not favorable for the catalytic activity of ZVI in phenol oxidation as well as for phenol adsorption. ZVI supported on activated carbon heat-treated at 900°C yields the best phenol removal, reaching over 85% after 3h, under the conditions tested: 150mgL−1 of initial phenol concentration, initial pH set at 3, 30°C, and the stoichiometric amount of hydrogen peroxide for achieving complete mineralization.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Efficient removal of Orange G using Prussian Blue nanoparticles supported
           over alumina
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): L. Doumic , G. Salierno , M. Cassanello , P. Haure , M. Ayude
      Prussian Blue nanoparticles (PBNP) synthetized and adsorbed onto γ-Al2O3 spheres were prepared and characterized by transition and scanning electron microscopy (TEM, SEM), energy dispersive X-ray spectroscopy (EDS) and sorptometry. Adsorption and reaction runs were performed using aqueous solutions of a model azo dye Orange G. The adsorption capacity of the PBNP/γ-Al2O3 at 323 and 343K at initial pH 3 and 6 was studied. The presence of PBNP increased the adsorption capacity of the support and this effect was more pronounced at initial pH 6. However, since the adsorbent life time was narrow and its regeneration quite difficult, PBNP/γ-Al2O3 was tested as a heterogeneous Fenton-like catalyst. The catalytic activity and stability for oxidation of Orange G were investigated in terms of discolouration, TOC and oxidant conversion. At the best operating condition studied (343K and pH0 =3), complete dye discolouration and 60% of mineralization were attained while reaction largely overcomes adsorption. At this temperature the catalyst activity and its characteristics remained almost invariable during 9 cycles of 5h each and iron leaching occurred in low extent.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
  • Development of glycerol-based metal-free carbon materials for
           environmental catalytic applications
    • Abstract: Publication date: 1 February 2015
      Source:Catalysis Today, Volume 240, Part A
      Author(s): Rui S. Ribeiro , Adrián M.T. Silva , Maria T. Pinho , José L. Figueiredo , Joaquim L. Faria , Helder T. Gomes
      A thermally stable and non-porous carbon material (S BET =10m2 g−1 and no micropores), with low ash content and basic character, was produced by partial carbonization of glycerol with sulphuric acid followed by calcination under inert atmosphere. Further thermal activation in air atmosphere at different temperatures (from 150 to 350°C) leads to materials with less basic character and to a tremendous evolution of the porosity, mostly microporosity (S BET =598m2 g−1 and V Mic =0.24cm3 g−1). Experiments show that metal-free carbon materials synthesized by this approach can be highly active catalysts for the catalytic wet peroxide oxidation (CWPO) process when the surface chemistry and textural properties are adequately tuned. Effective catalytic degradation of 2-nitrophenol (80% conversion) was achieved with the material treated under air atmosphere at 300°C, even when operating under a high pollutant/catalyst mass ratio, opening a window of opportunity for added-value crude glycerol-derived products. Furthermore, catalyst activity was effectively recovered by a simple oxidative thermal regeneration procedure.
      Graphical abstract image

      PubDate: 2014-10-30T09:52:42Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2014