催化学报

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前言

第六届国际环境催化大会 (6th ICEC, 2010) 专辑

2011, 32 (5): 0-0.

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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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第32卷第5期目次

2011, 32 (5): 1-2.

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燃油氧化脱硫

蒋宗轩, 吕宏缨, 张永娜, 李灿

2011, 32 (5): 707-715. DOI: 10.1016/S1872-2067(10)60246-X

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综述了燃油的氧化脱硫, 包括一些具有吸引力的氧化脱硫方法, 如 H2O2/有机酸, H2O2/杂多酸, H2O2/含钛分子筛和其它非过氧化氢体系 (如叔丁基过氧化物等). 对本课题组开发的新型乳液催化氧化脱硫体系进行了详细的介绍. 在乳液体系中, 界面间的传质限制被大大降低. 在温和条件下, 双亲性乳液催化剂可以将柴油中的含硫化合物选择氧化成其相应的砜类化合物. 氧化得到的砜可以使用极性萃取剂将其从油品中除去. 经过氧化和萃取之后, 加氢柴油中的硫含量可以从几百 μg/g 降低至 0.1 μg/g, 而直馏柴油中的硫含量则可以从 6000 μg/g 降低至 30 μg/g.

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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

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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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硅烷化 TS-1 对环己烷均相氧化反应的促进作用

王德强, 张一波, 肖德海, 杨向光

2011, 32 (5): 723-726. DOI: 10.1016/S1872-2067(10)60193-3

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考察了钛硅分子筛 (TS-1) 以及硅烷化钛硅分子筛 (TS-1-S) 上环烷酸钴 (Co-nap) 催化环己烷氧化反应性能. 结果表明, TS-1 和 TS-1-S 对该反应均具有显著的促进作用, 环己烷转化率由无 TS-1 时的 3.6% 分别提高至 6.4% 和 7.9%, 产物选择性保持在 80% 左右, 反应时间由 300 min 可缩短为 130 min. 进一步的研究表明, 随着 TS-1 的加入, Co-nap 在其表面发生了吸附, 使得均相反应变成了“类多相催化反应”, 这是反应性能显著提高的主要原因.

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CeO₂ 添加对 Ag/Al₂O₃ 催化剂低温氨氧化性能的影响

张丽, 刘福东, 余运波, 刘永春, 张长斌, 贺泓

2011, 32 (5): 727-735. DOI: 10.1016/S1872-2067(10)60220-3

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采用活性测试和氮气吸附、X 射线衍射、X 射线光电子能谱、紫外-可见漫反射吸收光谱、高倍透射电镜、原位漫反射傅里叶变换红外光谱和 O2 脉冲吸附等研究了铈添加对 Ag/Al2O3 催化剂低温氨氧化性能的影响. 结果表明, 适量铈的添加可以明显促进 Ag/Al2O3 催化剂的低温氨氧化活性, 且对催化剂的选择性影响不大. 添加铈不仅可以促进 Ag/Al2O3 催化剂表面吸附和活化 O2 的能力, 而且可促进催化剂表面对氨的解离吸附和活化. 这是铈促进 Ag/Al2O3 催化剂低温氨氧化活性的主要原因.

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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

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Fully formulated lean NO_x trap (LNT) catalysts of the type Pt/Rh/BaO/Al₂O₃ were prepared with and without incorporation of CeO₂-ZrO₂ in the washcoat, and their NO_x reduction behavior was evaluated in steady-state, continuous flow experiments. In the fresh state, CeO₂-ZrO₂ addition was found to exert little effect on NO_x reduction activity using H₂, CO, and NH₃ as the reductants. However, after simulated road aging, NO_x 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

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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

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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

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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

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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 NiMoO_xC_y 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

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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

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An efficient and environmentally benign procedure for the catalytic esterification of salicylic acid with aliphatic alcohols, C_nH_2n+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

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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

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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 MnO_x and CoO_x oxides promoted complete oxidation, especially at low input energy. CoO_x/SMF showed higher activity than MnO_x/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

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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 Ce_0.75Zr_0.25O₂ phase for CZ and Ce_0.5Zr_0.5O₂and Ce_0.6Zr_0.4O₂ phases for CZA samples, respectively. While the formation of only Ce_0.8Tb_0.2O_2-_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

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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

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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

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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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Cu_xCo_1-x/Al₂O₃/堇青石整体式催化剂的制备及其催化甲苯燃烧性能

赵福真, 张广宏, 曾鹏辉, 杨肖, 季生福

2011, 32 (5): 821-826. DOI: 10.1016/S1872-2067(10)60184-2

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以堇青石蜂窝陶瓷为基底, Al₂O₃ 浆料为过渡胶体, Cu 和 Co 为催化活性组分, 制备了一系列 Cu_xCo_1-x/Al₂O₃//堇青石 (x = 0~1) 整体式催化剂. 采用 X 射线衍射、X 射线光电子能谱、扫描电镜和程序升温还原等手段对催化剂进行了表征. 以甲苯为模型化合物, 在微型固定床反应器上评价了催化剂的催化性能. 结果表明, 当Cu含量较低时, 在整体式催化剂上形成了Cu-Co-O 固溶体; 当 Cu 含量较高时, 可以检测到 CuO. 在催化剂表面, Co 以 Co²⁺ 和 Co³⁺ 形式存在, 而 Cu 主要以 Cu²⁺ 形式存在. 适量 Cu 的加入可以改善催化剂中 Co 的氧化还原性能, 有利于催化剂活性的提高. 在所制备的催化剂中, Cu_0.5Co_0.5/Al₂O₃/堇青石整体式催化剂活性最高, 在315 ^oC 可以完全催化燃烧消除甲苯.

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十六烷基三甲基溴化铵辅助作用下球形、蠕虫状和网状 Pd 纳米粒子的制备与表征

訾学红, 王锐, 刘立成, 戴洪兴, 张桂臻, 何洪

2011, 32 (5): 827-835. DOI: 10.1016/S1872-2067(10)60194-5

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以十六烷基三甲基溴化铵 (CTAB) 为表面活性剂, NaBH4 为还原剂, 通过调节水相体系中 CTAB 和 NaBH4 浓度, 合成了一系列不同形貌的 Pd 纳米粒子, 合成过程简便易行且环境友好. 结果表明, 随着 CTAB 浓度的增加, Pd 粒子形貌由纳米微球逐渐向纳米线网络形态转变. CTAB 浓度和 NaBH4 浓度是决定 Pd 粒子形貌的两个重要因素.

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CeO₂-WO₃ 复合氧化物催化剂的 NH₃-SCR 反应机理

陈亮, 李俊华, 葛茂发, 马磊, 常化振

2011, 32 (5): 836-841. DOI: 10.1016/S1872-2067(10)60195-7

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采用共沉淀法制备了新型 CeO₂-WO₃ 复合氧化物催化剂, 并用于氨选择性催化还原 (NH₃-SCR) NO_x 反应中. 活性测试表明, 在 200~450 ºC NO_x 转化率接近 100%. 采用程序升温脱附和原位漫反射红外光谱研究了该催化剂上的 NH₃-SCR 反应机理. 结果表明, 该催化剂的主要活性位是 CeO₂, 而 WO₃ 的加入大大提高了其表面 Brönsted 酸位的数量与强度及其氧化 NO 的能力. 另外还发现, 除了催化剂表面 Lewis 酸与 Brönsted 酸参与反应外, 表面的桥式与单齿硝酸盐也是活性很高的物种. 整个 SCR 反应可通过以上两种途径进行.

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双模板法制备具有介孔孔壁的三维有序大孔二氧化铈及其改善的低温还原性能

张晗, 张磊, 邓积光, 刘雨溪, 蒋海燕, 石凤娟, 吉科猛, 戴洪兴

2011, 32 (5): 842-852. DOI: 10.1016/S1872-2067(10)60196-9

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以聚甲基丙烯酸甲酯 (PMMA) 为硬模板, 三嵌段共聚物 F127、十六烷基三甲基溴化铵 (CTAB) 或聚乙二醇 (PEG) 为软模板剂 (表面活性剂), 柠檬酸为络合剂, 硝酸铈为金属前驱体, 采用双模板法成功地合成出具有介孔孔壁的三维有序大孔 (3DOM) 结构的立方相 CeO₂样品 CeO₂-F127, CeO₂-CTAB 和 CeO₂-PEG, 并利用多种分析技术表征了它们的物化性质. 结果表明, 三个样品均具有 3DOM 结构和蠕虫状介孔孔壁, 表面活性剂的种类对样品的孔结构和比表面积影响较大. 在制备过程中引入表面活性剂可提高 CeO₂ 样品的比表面积, 所得 CeO₂-F127, CeO₂-CTAB 和 CeO₂-PEG 样品的比表面积分别为 60.5, 60.2 和 51.8 m²/g. 具有 3DOM 结构的 CeO₂ 样品的低温还原性显著好于无孔的体相 CeO₂, 它们的低温还原性按照 CeO₂-PEG < CeO₂-CTAB < CeO₂-F127 的顺序提高, 与其表面氧空位密度大小的顺序相吻合. CeO₂ 因具有蠕虫状介孔孔壁的 3DOM 结构, 改善了其物化性质, 使此类材料在催化方面有着更广泛的应用前景.

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钾对氧化铜催化活性炭还原 NO 反应的助催化作用

冯柄楠, 卢冠忠, 王艳芹, 郭耘, 郭杨龙

2011, 32 (5): 853-861. DOI: 10.1016/S1872-2067(10)60211-2

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研究了活性炭负载的 Cu-K-O 复合氧化物催化剂上碳还原 NO 的反应. 结果表明, K 的加入可有效地提高 CuO 催化剂的活性和稳定性, 当 Cu/K 的质量比为 2 时催化性能最佳. X 射线衍射、X 射线光电子能谱和程序升温脱附-质谱等结果表明, K 与 Cu 间的协同作用可促进表面碳活化中心与表面氧物种生成 CO^₂ 的反应, 保持表面 Cu²⁺活性中心的数量, 从而有利于 Cu²⁺/Cu⁺ 反应循环的进行.

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非水溶剂热法制备 (001) 面暴露的 F/TiO₂纳米晶及其光催化活性

蔡陈灵, 王金果, 曹锋雷, 李和兴, 朱建

2011, 32 (5): 862-871. DOI: 10.1016/S1872-2067(10)60206-9

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采用非水体系溶剂热法制备了 (001) 面暴露的锐钛矿相 F/TiO2 纳米光催化剂. 结果表明, F 的掺杂对 TiO2 纳米单晶的形成影响很大. 一方面, F 离子作为晶面导向剂稳定 (001) 晶面, 形成 (001) 面暴露的锐钛矿相 TiO2; 另一方面, F 离子也起到稳定剂作用, 抑制纳米粒子的快速生长. 以光催化降解甲基橙为模型反应比较了不同 F/TiO2 样品和商业 P25 样品的光催化活性. 同时, 通过选用不同捕获剂, 研究了 F/TiO2 和 P25 样品在甲基橙降解反应中的活性物种.

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Ru-Re/SiO₂催化剂上丙三醇氢解制丙二醇: 催化剂的酸性质与 Re 组分的作用

马兰, 李宇明, 贺德华

2011, 32 (5): 872-876. DOI: 10.1016/S1872-2067(10)60198-2

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考察了 Ru-Re/SiO2 双组分催化剂的酸性质, 并探讨了 Re 组分在丙三醇氢解制丙二醇反应中对提高该催化剂性能所起的作用. 本文采用氨气程序升温脱附法和吸附吡啶原位红外光谱法表征了双组分 Ru-Re/SiO2 和单组分 Ru/SiO2、Re/SiO2 催化剂的酸性质, 并比较了催化剂在丙三醇氢解反应中的催化性能. 结果显示, Ru-Re/SiO2、Ru/SiO2 和 Re/SiO2 催化剂表面均有酸性位, 但 Ru-Re/SiO2 和 Re/SiO2 催化剂的酸量明显高于 Ru/SiO2 催化剂. 本文对不同 Re 含量的 Ru-Re/SiO2 催化剂的催化性能也进行了考察. Ru-Re/SiO2 催化剂的活性随催化剂表面的酸量增加而增大, 且催化剂表面的酸量与催化剂上铼氧化物的含量直接相关. 讨论了铼氧化物在 Ru-Re/SiO2 催化剂催化的丙三醇氢解反应过程中所起的作用.

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