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Chinese Journal of Catalysis
2011, Vol. 32, No. 5
Online: 31 May 2011


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Environmental catalysis has been emerging as one of the rapidly growing areas in catalysis and has made significant progress in recent years. This special issue is a selection of the papers presented at the 6th International Conference on Environmental Catalysis (6th ICEC), which was held in Beijing on September 12–15, 2010. The 24 papers in this issue cover the most recent advances in fundamental and applied aspects of environmental catalysis research, including automotive exhaust catalysis, catalysis for pollutant removal, catalysis for reforming, catalysis for oxidative desulfurization of fuel oils, and so on. These manuscripts were accepted after a peer-review procedure as those accepted usually for publications in this Journal.

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Preface Selected Papers of the 6th International Conference on Environmental Catalysis 2011, 32 (5):  0-0.  Abstract ( 1748 )   PDF (68KB) ( 679 )   The 6th International Conference on Environmental Catalysis (6th ICEC) was held in Beijing from September 12 to September 15, 2010. The ICEC is a series of conferences that was initiated in Pisa (1995) and followed up in Miami Beach (1998), Tokyo (2001), Heidelberg (2005) and Belfast (2008). Totally 398 participants from 26 countries and regions attended the 6th ICEC 2010. Six plenary lectures were presented by Prof. Robbie Burch (The University of Belfast, UK), Dr. Hirofumi Shinjoh (Toyota Central R&D Labs, Japan), Prof. Chunshan Song (The Pennsylvania State University, USA), Prof. Michikazu Hara (Tokyo Institute of Technology, Japan), Prof. Gabriele Centi (University Messina Italy) and Prof. Jincai Zhao (Institute of Chemistry, China), and 133 oral presentations (including 16 keynote lectures) were presented during the conference. In the two poster-discussion sessions, 219 posters were displayed and well discussed. The scope of these presentations included the recent trends and challenges in automotive exhaust catalysis, catalysis for clean water and indoor air, catalysis for sustainable and clean energy, catalysis for reducing greenhouse gases, catalytic processes in green chemistry, and so on. Environmental catalysis, as an important approach to environmental protection and green chemistry, has been emerging as one of the rapidly growing areas in catalysis, and has made significant progress in recent years. The main objective of the 6th ICEC was to promote the global and interdisciplinary approach towards both fundamental science and industrial applications in environmental catalysis. This conference followed the tradition of the conference series and reflected tremendous advances in the field of environmental catalysis during the last few years. The conference provided a forum for scientists and engineers from both academia and industry to discuss the most recent developments and technological opportunities in this vibrant area of research. This special issue of Chinese Journal of Catalysis compiled 24 papers which were selected from the presentations in the 6th ICEC. These manuscripts were accepted after a peer-review procedure as those accepted usually for publications in Chinese Journal of Catalysis. These papers reflected the most recent advances and progresses in fundamental and applied aspects of environmental catalysis research. Finally, the Guest Editors, C. Li and H. He, would like to sincerely thank the colleagues, all authors and referees who have contributed a lot to this special issue. The acknowledgements are also extended to the editors of Chinese Journal of Catalysis for their valuable advice and assistance in preparing this issue.

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Table of Contents for Vol.32 No. 5 2011, 32 (5):  1-2.  Abstract ( 1480 )   [Full Text(HTML)] () PDF (1446KB) ( 943 )

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Oxidative Desulfurization of Fuel Oils JIANG Zong-Xuan, Lü Hong-Ying, ZHANG Yong-Na, LI Can 2011, 32 (5):  707-715.  DOI: 10.1016/S1872-2067(10)60246-X Abstract ( 3678 )   [Full Text(HTML)] () PDF (728KB) ( 1141 )   Several attractive approaches toward oxidative desulfurization of fuel oils, such as using H2O2/organic acids,?H2O2/heteropolyacid, H2O2/Ti-containing zeolites, and other non-hydrogen peroxide systems (e.g., t-butyl hydroperoxide etc.) are reviewed. A new alternative oxidative desulfurization process using emulsion catalysts was developed mainly by our group, is introduced in detail. Limitations because of interphase mass transfer are greatly reduced in the emulsion reaction medium. The amphiphilic emulsion catalysts can selectively oxidize the sulfur-containing molecules present in diesel to their corresponding sulfones when using H2O2 as the oxidant under mild conditions. The sulfones in the oxidized fuel oils can be removed by a polar extractant. The sulfur level of a prehydrotreated diesel can be lowered from a few hundred μg/g to 0.1 μg/g after oxidation and subsequent extraction whereas the sulfur level of a straight-run diesel can be decreased from 6000 to 30 μg/g after oxidation and extraction.

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Recent Developments in the Catalytic Conversion of Cellulose into Valuable Chemicals Pengfei YANG, Hirokazu KOBAYASHI, Atsushi FUKUOKA 2011, 32 (5):  716-722.  DOI: 10.1016/S1872-2067(10)60232-X Abstract ( 3765 )   [Full Text(HTML)] () PDF (457KB) ( 2071 )   Currently, under huge pressure from energy demands and environmental problems, much attention is being paid to biomass conversion, which will play an important role in meeting the requirements for a sustainable society. As the most abundant biomass on earth, cellulose is usually used as the first research target for biomass conversion. In this review, the recalcitrant structure of cellulose is discussed and non-catalytic hydrolysis by hot-compressed water and catalytic hydrolysis using solid acids are then considered. We also review the catalytic conversion of cellulose into valuable chemicals including hexitols (sorbitol and mannitol), ethylene glycol, and related compounds using various heterogeneous catalysts.

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Silanized Titanium Silicate (TS-1) Molecular Sieve for Promoting the Homogeneously Catalyzed Oxidation of Cyclohexane WANG De-Qiang, ZHANG Yi-Bo, XIAO De-Hai, YANG Xiang-Guang 2011, 32 (5):  723-726.  DOI: 10.1016/S1872-2067(10)60193-3 Abstract ( 3347 )   [Full Text(HTML)] () PDF (455KB) ( 1058 )   The promoting effect of titanium silicate (TS-1) molecular sieve and silylanized TS-1 (TS-1-S) on the homogeneous liquid oxidation of cyclohexane catalyzed by cobalt naphthenate (Co-nap) with oxygen as oxidant was investigated. Both TS-1 zeolites were efficient promoters. The conversion of cyclohexane was 7.9% with a selectivity of 83.7% when it was catalyzed by Co-nap/TS-1-S, and the reaction time was reduced to 130 min as compared to 300 min with Co-nap as the catalyst. The adsorption of Co-nap on TS-1-S, which transformed a homogeneous reaction into a “quasi-heterogeneous” reaction, was the reason for the better catalytic performance.

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Effects of Adding CeO2 to Ag/Al2O3 Catalyst for Ammonia Oxidation at Low Temperatures ZHANG Li, LIU Fu-Dong, YU Yun-Bo, LIU Yong-Chun, ZHANG Chang-Bin, HE Hong 2011, 32 (5):  727-735.  DOI: 10.1016/S1872-2067(10)60220-3 Abstract ( 3936 )   [Full Text(HTML)] () PDF (835KB) ( 1064 )   The effects of adding CeO2 to Ag/Al2O3 on the selective catalytic oxidation of ammonia to nitrogen were investigated by activity test and N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse-reflectance spectroscopy, high resolution transmission electron microscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy of NH3 adsorption, and O2-pulse adsorption. Adding a suitable amount of CeO2 improved the catalytic activity of Ag/Al2O3 for NH3 oxidation at temperatures below 160 oC, and slightly influenced N2 selectivity by improving the catalyst’s ability to adsorb and activate O2 and the adsorption and activation of NH3.

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NOx Reduction on Fully Formulated Lean NOx Trap Catalysts Subjected to Simulated Road Aging: Insights from Steady-State Experiments Jin WANG, Yaying JI, Uschi GRAHAM, Caio CESAR SPINDOLA DE OLIVEIRA, Mark CROCKER 2011, 32 (5):  736-745.  DOI: 10.1016/S1872-2067(10)60230-6 Abstract ( 3388 )   [Full Text(HTML)] () PDF (740KB) ( 1122 )   Fully formulated lean NOx trap (LNT) catalysts of the type Pt/Rh/BaO/Al2O3 were prepared with and without incorporation of CeO2-ZrO2 in the washcoat, and their NOx reduction behavior was evaluated in steady-state, continuous flow experiments. In the fresh state, CeO2-ZrO2 addition was found to exert little effect on NOx reduction activity using H2, CO, and NH3 as the reductants. However, after simulated road aging, NOx reduction activity was significantly impaired for the CeO2-ZrO2-free catalyst, whereas the performance of the CeO2-ZrO2-containing analog was affected to only a minor degree. These differences are explained on the basis of high-resolution transmission electron microscopy measurements showing that Pt supported on CeO2-ZrO2 remained highly dispersed after aging, whereas Pt supported on BaO/Al2O3 underwent significant sintering. In addition, the Pt/CeO2-ZrO2 component did not accumulate sulfur during aging, unlike Pt/BaO/Al2O3 for which significant sulfation of the Ba phase occurred. For both catalysts, selectivity to NH3 in NO and NO2 reduction by H2 increased after catalyst aging, indicative of a change in the relative surface coverages of N and H ad-atoms on the precious metal sites.

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Application of Hydrodechlorination in Environmental Pollution Control: Comparison of the Performance of Supported and Unsupported Pd and Ni Catalysts Claudia AMORIMa, Xiaodong WANG, Mark A. KEANE 2011, 32 (5):  746-755.  DOI: 10.1016/S1872-2067(10)60228-8 Abstract ( 3986 )   [Full Text(HTML)] () PDF (918KB) ( 1372 )   Catalytic hydrodechlorination (HDC) is an innovative means of transforming chlorinated waste streams into a recyclable product. In this study, the gas phase HDC of chlorobenzene (CB) has been studied over bulk Pd and Ni and ((8 ± 1) wt%) Pd and Ni supported on activated carbon (AC), graphite, graphitic nanofibers (GNF), Al2O3, and SiO2. Catalyst activation was examined by temperature-programmed reduction (TPR) analysis and the activated catalysts characterized in terms of BET area, transmission electron microscopy, scanning electron microscopy, H2 chemisorption/temperature-programmed desorption, and X-ray diffraction measurements. Metal surface area (1–19 m2/g), TPR, and H2 uptake/release exhibited a dependence on both metal and support. The Pd system delivered specific HDC rates that were up to three orders of magnitude greater than that recorded for the Ni catalysts, a result that we link to the higher H2 diffusivity in Pd. HDC was 100% selective over Ni while Pd also produced cyclohexane (selectivity < 4%) as a result of a combined HDC/hydrogenation. Bulk Pd outperformed carbon supported Pd but was less active than Pd on the oxide supports. In contrast, unsupported Ni presented no measurable activity when compared with supported Ni. The specific HDC rate was found to increase with decreasing metal surface area where spillover hydrogen served to enhance HDC performance.

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Alternative Use of Light Emitting Diodes in an Activated Charcoal-Supported Photocatalyst Reactor for the Control of Volatile Organic Compounds YANG S, YU M. S, KIM J. S, JO W. K 2011, 32 (5):  756-761.  DOI: 10.1016/S1872-2067(10)60202-1 Abstract ( 3359 )   [Full Text(HTML)] () PDF (378KB) ( 1081 )   The applicability of ultraviolet-light emitting diodes (LEDs) as a light source for photocatalysis using granular activated charcoal (GAC) impregnated with transition metal-enhanced photocatalysts for the control of volatile organic compounds (VOCs) was investigated. Two target compounds (toluene and methyl mercaptan) were selected to evaluate the removal activities of the TiO2/GAC composites. The photocatalysts were prepared by a sol-gel method. Methyl trimethoxy silane was added as a precursor sol solution to bind the photocatalyst with the GAC. Metal (Zn2+, Fe3+, Ag+, and Cu2+) enhanced TiO2/GAC composites were prepared and tested for their photocatalytic activities under 400 nm LED irradiation. The specific surface area (SSA) and the surface chemical composition of the prepared composites were investigated. The SSAs of all the impregnated composites were similar to those of pure GAC. Both field emission-scanning electron microscopy and energy dispersive spectroscopic analysis confirmed that titanium and the impregnated metals were deposited on the surface of the adsorbent. The breakthrough time for GAC toward toluene or methyl mercaptan gas increased upon photocatalytic impregnation and LED illumination. Using different binders affected the breakthrough time of the TiO2/GAC composite and the addition of zinc oxide to TiO2 increased the VOC removal capacity of the GAC composite.

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Parametric Study on the Deactivation of Supported Co3O4 Catalysts for Low Temperature CO Oxidation Moon Hyeon KIM, Dong Woo KIM 2011, 32 (5):  762-770.  DOI: 10.1016/S1872-2067(10)60233-1 Abstract ( 3072 )   [Full Text(HTML)] () PDF (419KB) ( 999 )   This study focused on the influences of a variety of reaction parameters and guest molecules such as H2O and C3H8 on the deactivation of supported Co3O4 catalysts for CO oxidation. Additionally, the physical features of and carbon deposition on some samples after the reaction under the chosen conditions were determined by BET and X-ray diffraction as well as by carbon analyses to deduce the precursors associated with catalyst deactivation. Activity maintenance profiles of the catalysts for CO oxidation at 100 °C significantly depended on the support for Co3O4 nanoparticle dispersion, the loading, the preparation technique and the calcination temperature. The best on-stream performance was achieved using a 5% Co3O4/TiO2 catalyst prepared by the incipient wetness method followed by calcination at 350 °C. All the reaction parameters chosen here such as the reaction temperature, the feed gas composition of CO, O2, H2O, and C3H8, and the gas space velocity strongly influenced the extent of catalyst deactivation during CO oxidation and also the rate of catalyst deactivation. However, the deactivation behavior is very complicated. No appreciable changes in the surface area, the porosity, and the phase of the Co3O4 nanoparticles and their size occurred even for the samples that were severely deactivated. Significant deposition of carbon on the catalysts after the reaction was visible and it depended on the reaction parameters chosen here. Consequently, this extensive parametric study on the deactivation of catalysts during oxidation and with the chosen reaction parameters and guest gases can lead to an understanding of the deactivation precursors that are associated with carbonaceous species including carbonates and surface free carbon.

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Preparation of a Nickel Molybdenum Carbide Catalyst and Its Activity in the Dry Reforming of Methane Taro HIROSE, Yasushi OZAWA, Masatoshi NAGAI 2011, 32 (5):  771-776.  DOI: 10.1016/S1872-2067(10)60185-4 Abstract ( 3348 )   [Full Text(HTML)] () PDF (247KB) ( 1355 )   Nickel molybdenum carbide catalysts were prepared and their activities in the CO2 reforming of methane at a low CO2/CH4 reactant ratio were investigated using a microreactor at atmospheric pressure and at 973 K. The effect of the catalyst preparation method and the Ni/Mo ratio on the increase in catalyst life and the promotion of catalytic activity were investigated using N2 adsorption, X-ray diffraction, temperature-programmed carburization, temperature-programmed reaction, and a reforming reaction. The 25Ni75Mo catalyst that was carburized at 813 K exhibited the highest hydrogen formation ability and gave the least carbon deposition. The incomplete carburization of the Mo oxide species in the catalyst that was carburized at a lower temperature gradually gave a more active carburized species. The NiMoOxCy in the catalyst was more active in hydrogen formation during the dry reforming of methane while β-Mo2C and η-Mo3C2 were less active.

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Platinum-Based Catalyst for Diesel Hydrocarbon Oxidation Masaaki HANEDA, Motoi SASAKI, Hideaki HAMADA, Masakuni OZAWA 2011, 32 (5):  777-781.  DOI: 10.1016/S1872-2067(10)60192-1 Abstract ( 2661 )   [Full Text(HTML)] () PDF (315KB) ( 1694 )   The catalytic performance of Pt-based catalysts for the total oxidation of hydrocarbons was investigated. The activity of supported Pt catalysts (Pt/Al2O3, Pt/ZrO2, Pt/TiO2, and Pt/H-ZSM-5) depends on the metal oxide support. Pt/Al2O3 showed the highest catalytic activity when the catalysts were aged at 750 °C for 50 h in air. The activity of Pt/Al2O3 was dependent on the valence state of the Pt surface. Pt/Al2O3 with the Pt surface in the metallic state was more active than with the surface in the cationic state. The surface density of acid and basic sites on the Al2O3 support controlled the valence state of the Pt surface and stability of the Pt particles in the highly dispersed state, respectively.

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Catalytic Performance of Nano-SiO2-Supported Preyssler Heteropolyacid in Esterification of Salicylic Acid with Aliphatic and Benzylic Alcohols Fatemeh F. BAMOHARRAM, Majid M. HERAVI, Javad EBRAHIMI, Ali AHMADPOUR, Mojtaba ZEBARJAD 2011, 32 (5):  782-788.  DOI: 10.1016/S1872-2067(10)60219-7 Abstract ( 3543 )   [Full Text(HTML)] () PDF (463KB) ( 1433 )   An efficient and environmentally benign procedure for the catalytic esterification of salicylic acid with aliphatic alcohols, CnH2n+1OH (n = 1–5) and benzylic alcohols, RC6H4CH2OH (R = H, NO2, OCH3, Br, Cl, Me) was developed using nano-SiO2-supported Preyssler heteropolyacid both under thermal conditions and microwave irradiation. Silica nanostructures were obtained through a sol-gel method and were characterized by transmission electron microscopy and powder X-ray diffraction. The effects of various parameters such as solvent type, molar ratio of substrates, Preyssler heteropolyacid loading on silica, catalyst amount, temperature, and reaction time were studied and the optimum conditions were obtained. It has been found that the catalyst with 30 wt% loading is highly active and shows high yields in esterification reactions. The use of nano-SiO2-supported Preyssler heteropolyacid coupled with microwave irradiation allows a solvent-free, rapid (3 min), and high-yielding reaction. This catalyst can be easily recovered and reused for many times without a significant loss in its activity.

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Preparation and Characterization of High Activity Zirconium-Doped Anatase Titania for Solar Photocatalytic Degradation of Ethidium Bromide S. SWETHA, R. GEETHA BALAKRISHNA 2011, 32 (5):  789-794.  DOI: 10.1016/S1872-2067(10)60200-8 Abstract ( 3209 )   [Full Text(HTML)] () PDF (450KB) ( 1179 )   Ethidium bromide is a fluorescent tag and is used in biomedical applications. It is a potent mutagen because of its DNA intercalating nature. A catalyst composition for the feasible elimination of ethidium bromide using a broad spectrum of solar radiation was investigated. Nanostructured anatase TiO2 was synthesized by gel to crystalline conversion and its bandgap was engineered by doping with zirconium to effectively harness sunlight. The doped nanocrystals were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, and UV-Vis spectroscopy. The formed crystals retained the anatase phase with a marginal increase in size. The pulverization process used to dope Zr into titania resulted in a nano and doped lattice with an increased and extended light absorption range, which gave a nearly five-fold increase in photoactivity over pure titania. The catalytic effect of the modified titania, the dopant concentration, and the dynamics of the dopant concentration on the charge carriers (trapping-recombination) for the degradation of the mutagen was investigated. The modified titania is capable of total ethidium bromide elimination in sunlight. The loss of its mutagenic property was confirmed by an Ames test. The induced revertant colonies observed were nil in the treated sample indicating a complete loss of the intercalating property of the mutagen.

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Catalytic Plasma Reactor for Abatement of Dilute Nitrobenzene J. KARUPPIAH, L. SIVACHRANDIRAN, R. KARVEMBU, Ch. SUBRAHMANYAM 2011, 32 (5):  795-799.  DOI: 10.1016/S1872-2067(10)60190-8 Abstract ( 2425 )   [Full Text(HTML)] () PDF (187KB) ( 1557 )   Oxidative decomposition of dilute nitrobenzene in air was carried out in a catalytic plasma reactor with an inner electrode made of sintered metal fibres (SMF) that also acted as catalyst. The parameters of the concentration, specific input energy, and gas residence time were optimized. The modification of the SMF inner electrode with transition metal oxides like MnOx and CoOx oxides promoted complete oxidation, especially at low input energy. CoOx/SMF showed higher activity than MnOx/SMF and SMF, and could oxidise completely 100 ppm of nitrobenzene at 300 J/L.

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Nanosized Unsupported and Alumina-Supported Ceria-Zirconia and Ceria-Terbia Solid Solutions for CO Oxidation M. Reddy BENJARAM, Thrimurthulu GODE, Lakshmi KATTA 2011, 32 (5):  800-806.  DOI: 10.1016/S1872-2067(10)60227-6 Abstract ( 2999 )   [Full Text(HTML)] () PDF (517KB) ( 1252 )   Ceria-zirconia (CZ) and ceria-terbia (CT) and alumina-supported ceria-zirconia (CZA) and ceria-terbia (CTA) solid solutions were synthesized by coprecipitation and deposition precipitation methods, respectively. Structural characteristics and catalytic activity of the synthesized samples have been investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS), and Brunauer-Emmett-Teller (BET) surface area measurements. To evaluate the catalytic properties, total oxygen storage capacity and CO oxidation activity measurements were carried out. The XRD analyses revealed the formation of Ce0.75Zr0.25O2 phase for CZ and Ce0.5Zr0.5O2 and Ce0.6Zr0.4O2 phases for CZA samples, respectively. While the formation of only Ce0.8Tb0.2O2-d phase was noted for both CT and CTA samples. All the supported and unsupported samples adopted a fluorite-type structure and exhibited cell parameters with respect to Vegard’s rule. The HRTEM results indicated well-dispersed particles of the size around 5 nm. The RS measurements suggested the presence of oxygen vacancies due to defective structure formation. The XPS studies revealed the presence of cerium in both Ce4+ and Ce3+ oxidation states in different proportions. It was found that CO oxidation for CTA occurs at very much lower temperature than CT, CZ, and CZA samples. Details of these findings by correlating with the structural characterization studies are consolidated.

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Heterogeneization of [Cu(2,2'-bpy)Cl2] and [Cu(1,10-phen)Cl2] on Polyoxometalates: New Catalysts for the Selective Oxidation of Tetralin M. BOLTZ, A. BLANC, G. LAUGEL, P. PALE, B. LOUIS 2011, 32 (5):  807-811.  DOI: 10.1016/S1872-2067(10)60239-2 Abstract ( 3558 )   [Full Text(HTML)] () PDF (423KB) ( 2182 )   Mononuclear Cu(II) bipyridine (1) and phenantroline complexes (2) were synthesized and immobilized by different procedures on H3PW12O40 polyoxometalate (POM). Characterization by XRD and SEM-EDX were performed to assess the preservation of the Keggin structure and stoichiometry of the complex. The immobilized complexes were tested as heterogeneous catalysts for the partial oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) using hydrogen peroxide as oxidant in acetonitrile/water as solvent. [Cu(2,2'-bpy)Cl][H2PW12O40] and [Cu(1,10-phen)Cl][H2PW12O40] oxidized tetralin at room temperature, with 16% conversion with (2), to 1-tetralone and 2-tetralone with 83% selectivity. However, the selectivity for 1-tetralone was only 56%. Different preparation methods for the heterogenization of these complexes on the POM Keggin unit were compared and used to enhance the selectivity to 1-tetralone to 75%.

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Wavelength Effect on Photocatalytic Reduction of CO2 by Ag/TiO2 Catalyst K. KOCI, K. ZATLOUKALOVA, L. OBALOVA, S. KREJCIKOVA, Z. LACNY, L. CAPEK, A. HOSPODKOVA, O. SOLCOVA 2011, 32 (5):  812-815.  DOI: 10.1016/S1872-2067(10)60199-4 Abstract ( 3973 )   [Full Text(HTML)] () PDF (223KB) ( 3116 )    Photocatalytic reduction of CO2 by water was performed in the presence of a Ag/TiO2 catalyst under illumination by lamps with different wavelengths (254, 365, and 400 nm). The yields of the main products (methane and methanol) were higher with the 254 nm lamp than with the 365 lamp while no products were observed with the 400 nm lamp. This was because the electron-hole generation rate increased with increasing energy of irradiation (decreasing wavelength) and there were higher densities of electron states at higher energies in TiO2. The increased efficiency of electron-hole generation with a shorter wavelength irradiation increased the efficiency of the catalyst. The energy of the electrons excited by visible light (400 nm) was too low for CO2 photocatalytic reduction.

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Simulation of N2O Abatement in Waste Gases by Its Decomposition over a K-Promoted Co-Mn-Al Mixed Oxide Catalyst Lucie OBALOVá, Květu?e JIRáTOVá, Kateina KARáSKOVá, Franti?ek KOVANDA 2011, 32 (5):  816-820.  DOI: 10.1016/S1872-2067(10)60201-X Abstract ( 2950 )   [Full Text(HTML)] () PDF (225KB) ( 936 )   Intrinsic data of N2O catalytic decomposition over a K-promoted Co-Mn-Al mixed oxide prepared by the thermal treatment of a layered double hydroxide was used for the design of a pilot reactor for the abatement of N2O emissions from the off-gases in HNO3 production. A pseudo-homogeneous one-dimensional model of an ideal plug flow reactor under an isothermal regime (450 °C) was used for reactor design. A catalyst particle diameter of 3 mm is a compromise size because increasing the size of the catalyst particle leads to a decrease in the reaction rate because of an internal diffusion limitation, and particles with a smaller diameter cause a large pressure drop. A catalyst bed of 11.5 m3 was estimated for the target N2O conversion of 90% upon the treatment of 30000 m3/h of exhaust gas (0.1 mol% N2O, 0.005 mol% NO, 0.9 mol% H2O, 5 mol% O2) at 450 °C and 130 kPa.

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Preparation of CuxCo1-x/Al2O3/Cordierite Monolithic Catalysts and the Catalytic Combustion of Toluene ZHAO Fu-Zhen, ZHANG Guang-Hong, ZENG Peng-Hui, YANG Xiao, JI Sheng-Fu 2011, 32 (5):  821-826.  DOI: 10.1016/S1872-2067(10)60184-2 Abstract ( 3279 )   [Full Text(HTML)] () PDF (839KB) ( 997 )   A series of CuxCo1-x/Al2O3/cordierite (x = 0~1) catalysts were prepared using cordierite as a support, a boehmite primer sol as the first washcoat layer and copper as well as cobalt oxides as the activity washcoat layer. The structure of the catalysts was characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and temperature-programmed reduction. Toluene was chosen as a model compound to evaluate the catalytic activity in a conventional fixed-bed quartz reactor. The results indicate that Cu-Co-O was present when the Cu content was low. CuO diffraction peaks were observed when the Cu content was high. Both Co2+ and Co3+ exist on the surface of the obtained monolithic catalysts while Cu2+ is the main Cu species. The addition of a certain amount of copper oxide improved the reducibility of the cobalt oxide, which enhanced the catalytic activity of the catalysts. All the obtained catalysts showed good activity for the catalytic combustion of toluene. The Cu0.5Co0.5/Al2O3/cordierite catalyst showed the best catalytic activity. Toluene was completely oxidized at 315 °C.

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Cetyltrimethyl Ammonium Bromide Assisted Preparation and Characterization of Pd Nanoparticles with Spherical, Worm-Like, and Network-Like Morphologies ZI Xue-Hong, WANG Rui, LIU Li-Cheng, DAI Hong-Xing, ZHANG Gui-Zhen, HE Hong- 2011, 32 (5):  827-835.  DOI: 10.1016/S1872-2067(10)60194-5 Abstract ( 3739 )   [Full Text(HTML)] () PDF (1412KB) ( 1393 )   With cetyltrimethylammonium bromide (CTAB) as a surfactant, a series of palladium nanoparticles with various morphologies were successfully synthesized by controlling the concentrations of CTAB and NaBH4 in an aqueous solution. The morphology of the Pd NPs evolved from nanospheres as interconnected networks with a rise in the CTAB concentration. The CTAB and NaBH4 concentrations were important factors for the control of the final shape of the Pd nanoparticles.

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Mechanism of Selective Catalytic Reduction of NOx with NH3 over CeO2-WO3 Catalysts CHEN Liang, LI Jun-Hua, GE Mao-Fa, MA Lei, CHANG Hua-Zhen- 2011, 32 (5):  836-841.  DOI: 10.1016/S1872-2067(10)60195-7 Abstract ( 3006 )   [Full Text(HTML)] () PDF (577KB) ( 1362 )   The mechanism of NH3-selective catalytic reduction (SCR) over a CeO2-WO3 catalyst was investigated by temperature-programmed desorption (TPD) analysis and in situ diffuse reflectance infrared Fourier transform spectroscopy. The active sites were on CeO2, while WO3 greatly enhanced the amount and strength of the surface Brönsted acid sites and the NO oxidation ability. Both NH4+ and coordinated NH3 contributed to the SCR reaction. Bridging nitrate and monodentate nitrate were confirmed as the reactive nitrate species. Under SCR reaction conditions, surface NH4NO3 was formed, which played the role of an important intermediate species. Two different pathways for the SCR reaction were suggested for the CeO2-WO3 catalyst.

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Dual-templating Preparation and Enhanced Low-Temperature Reducibility of Three-Dimensionally Ordered Macroporous Ceria with Mesoporous Walls ZHANG Han, ZHANG Lei, DENG Ji-Guang, LIU Yu-Xi, JIANG Hai-Yan, SHI Feng-Juan, JI Ke-Meng, DAI Hong-Xing 2011, 32 (5):  842-852.  DOI: 10.1016/S1872-2067(10)60196-9 Abstract ( 3479 )   [Full Text(HTML)] () PDF (1717KB) ( 1562 )   Three-dimensionally ordered macroporous (3DOM) ceria with mesoporous walls and cubic crystal structures were prepared with polymethyl methacrylate (PMMA) as a hard template and triblock copolymer Pluronic F127 (EO106PO70EO106), cetyltrimethylammonium bromide (CTAB), or poly(ethylene glycol) (PEG) as a soft template. Citric acid was used as a complexing agent and cerium nitrate was used as a metal precursor. The 3DOM CeO2 samples were characterized by numerous analytical techniques. The as-fabricated CeO2 samples had a 3DOM architecture with polycrystalline wormhole-like mesoporous walls. The nature of the soft template had an important effect on the pore structure and the surface area of the final product. The surface areas of the F127-, CTAB-, and PEG-derived 3DOM CeO2 samples (denoted CeO2-F127, CeO2-CTAB, and CeO2-PEG, respectively) were ca. 60.5, 60.2, and 51.8 m2/g, respectively. The low-temperature reducibility of the 3DOM-structured CeO2 samples was much better than that of the bulk counterpart and the low-temperature reducibility of the three 3DOM ceria samples increased according to: CeO2-PEG < CeO2-CTAB < CeO2-F127, which coincided with the surface oxygen vacancy density sequence. The improved physicochemical properties associated with the formation of the 3DOM skeleton with wormhole-like mesoporous walls may be useful for applications such as CeO2 materials in heterogeneous catalysis.

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Promoting Role of Potassium on the Catalytic Performance of Copper Oxide for the Reduction of NO by Activated Carbon FENG Bing-Nan, LU Guan-Zhong, WANG Yan-Qin, GUO Yun, GUO Yang-Long 2011, 32 (5):  853-861.  DOI: 10.1016/S1872-2067(10)60211-2 Abstract ( 3417 )   [Full Text(HTML)] () PDF (635KB) ( 1077 )   The reduction of NO by activated carbon over a Cu-K-O mixed oxide catalyst was investigated. We found that the addition of K to CuO obviously improved its catalytic performance and stability, and the optimum Cu/K weight ratio is 2. Characterization by X-ray photoelectron spectroscopy, X-ray diffraction, and temperature-programmed desorption shows that the presence of K can promote the reaction between the surface carbon active sites and the surface oxygen species to form CO2 by a synergetic effect between Cu and K. Additionally, a higher surface concentration of Cu2+ is retained, which favors the Cu2+/Cu+ reduction cycle on the active sites.

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Synthesis and Photocatalytic Activity of F/TiO2 Nanocrystals with Exposed (001) Facets via a Nonhydrolytic Solvothermal Route CAI Chen-Ling, WANG Jin-Guo, CAO Feng-Lei, LI He-Xing, ZHU Jian 2011, 32 (5):  862-871.  DOI: 10.1016/S1872-2067(10)60206-9 Abstract ( 4136 )   [Full Text(HTML)] () PDF (1958KB) ( 2462 )   F/TiO2 nanocrystals with exposed (001) facets were synthesized by a nonhydrolytic solvothermal route. The influence of F ions on the formation process was investigated in detail. The F ions function as a crystal-face directing agent and a stabilizing agent. The photocatalytic activities of the F/TiO2 and commercial P25 samples were determined by the degradation of methyl orange. The influencing factors and active species in the degradation process are discussed after particular characterization and experiments with different scavengers.

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Glycerol Hydrogenolysis to Propanediols over Ru-Re/SiO2: Acidity of Catalyst and Role of Re MA Lan, LI Yu-Ming, HE De-Hua 2011, 32 (5):  872-876.  DOI: 10.1016/S1872-2067(10)60198-2 Abstract ( 3410 )   [Full Text(HTML)] () PDF (435KB) ( 947 )   The acidic property of Ru-Re/SiO2 catalysts and the role of Re were investigated. The acidic properties of Ru-Re/SiO2, Ru/SiO2, and Re/SiO2 were characterized by temperature programmed desorption of ammonia and in situ IR spectra of pyridine adsorption. Their catalytic performances in glycerol hydrogenolysis were compared. Ru-Re/SiO2, Ru/SiO2, and Re/SiO2 possessed acid sites, but the site amounts of Ru-Re/SiO2 and Re/SiO2 were much higher than that of Ru/SiO2. The activities of Ru-Re/SiO2 with different Re contents were evaluated. The activity of Ru-Re/SiO2 increased with the acid amount, which correlated with the amount of Re oxide on the catalyst. The role of Re oxide in Ru-Re/SiO2 catalyzed glycerol hydrogenolysis was discussed.