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Chinese Journal of Catalysis
2007, Vol. 28, No. 7
Online: 25 July 2007

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Selective Hydrogenation of p-Chloronitrobenzene over Ru-Ir/γ-Al2O3 Catalyst Modified by Organic Amines XU Qiong;Wang Lei;CHEN Junru;LI Xianjun;LI Ruixiang* 2007, 28 (7):  579-581.  Abstract ( 2235 )   [Full Text(HTML)] () PDF (228KB) ( 778 )   A Ru-Ir/γ-Al2O3 bimetallic catalyst was prepared by impregnating γ-Al2O3 with a isopropylalcohol solution of RuCl3 and H2IrCl6. The effect of organic amine modifiers on the selective hydrogenation of p-chloronitrobenzene (p-CNB) over Ru-Ir/γ-Al2O3 was investigated. The addition of ethylenediamine and L-lysine remarkably improved the catalytic activity of Ru-Ir/γ-Al2O3 and the selectivity for p-chloroaniline (p-CAN) at high conversion of p-CNB. In the presence of ethylenediamine, the conversion of p-CNB increased from 37.2% to 95.6% and the selectivity for p-CAN was maintained at 100%. Similarly, the addition of L-lysine greatly enhanced the catalyst activity and completely suppressed the formation of by-products. The promotion effect was attributed to the coordination of ethylenediamine or L-lysine with the metal center, with improved the cooperation between ruthenium and iridium.

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A Novel Reduction Method for Ni/γ-Al2O3 Catalyst by a High Frequency Cold Plasma Jet at Atmospheric Pressure LIU Gaihuan;CHU Wei;LONG Huali;DAI Xiaoyan;YIN Yongxiang* 2007, 28 (7):  582-584.  Abstract ( 2179 )   [Full Text(HTML)] () PDF (213KB) ( 835 )   The Ni/γ-Al2O3 catalyst was reduced by high frequency cold plasma jet at atmospheric pressure. The performance of the catalyst for carbon dioxide reforming of methane was investigated. The process of catalyst reduction with plasma was quick and simple and was completed in only 10 min, giving activity and selectivity higher than those of the catalyst prepared by the conventional method. At the CH4/CO2 molar ratio of 4/6 and the reaction temperature of 850 ℃, the methane conversion and CO2 conversion reached up to 95.77% and 75.65%, respectively, and a hydrogen selectivity of 100% and a CO selectivity of 94.79% were obtained over the novel catalyst reduced by plasma. The novel catalyst exhibited good stability during a reaction test for 36 h. XRD characterization showed that only a metallic nickel phase and γ-alumina existed in the catalyst reduced by plasma, and the NiAl2O4 phase and other nickel oxides were not detected. The nickel particle size of the catalyst was smaller than that of the conventional catalyst. An enhanced dispersion was achieved with the plasma reduction.

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Synthesis of Adamantane Catalyzed by an Active Immobilized Aluminium Chloride Catalyst WU Limei;JI Min*;HE Min;CAI Tianxi 2007, 28 (7):  585-587.  Abstract ( 1962 )   [Full Text(HTML)] () PDF (155KB) ( 1024 )   An immobilized AlCl3 catalyst was first used to catalyze the isomerization of endo-tricyclodecane to produce adamantane. The AlCl3 catalyst immobilized on γ-Al2O3 exhibited high activity and selectivity at a low reaction temperature of 140 ℃, with endo-tricyclodecane conversion of 100% and adamantane selectivity of 17.7%, whereas the AlCl3 catalyst immobilized on SiO2 showed very low adamantane selectivity of almost zero.

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Ring-Opening Polymerization of2,2-Dimethyltrimethylene Carbonate and Its Copolymerization with ε-Caprolactone by Ionic Liquid-Supported Rare Earth Metal Complex Catalysts XIONG Yubing;NI Xufeng;FAN Ling;SHEN Zhiquan* 2007, 28 (7):  588-590.  Abstract ( 2155 )   [Full Text(HTML)] () PDF (178KB) ( 998 )   Homopolymerization of2,2-dimethyltrimethylene carbonate and its copolymerization with ε-caprolactone (ε-CL) catalyzed by ionic liquid-supported rare earth catalysts were investigated for the first time. The results indicated that this novel catalyst is effective for the homopolymerization and copolymerization. Of all the rare earth catalysts prepared, LaCl3 showed the highest catalytic activity and can be used to prepare poly(2,2-dimethyltrimethylene carbonate) with a viscosity average molecular weight of 3.61×104 and a yield over 88% under mild conditions of ε-CL/La molar ratio=200 and 60 ℃ in toluene. Moreover, both random and block copolymers can be prepared by changing the feed sequence with this catalyst only when ε-CL was polymerized first. When2,2-dimethyltrimethylene carbonate was polymerized first, only homopolymer can be prepared. The copolymers were characterized by1HNMR.

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Efficient Synthesis of3,4-Dihydropyrimidin-2(1H)-one Using Metal Hydrogen Sulfates M(HSO4)n as Catalyst under Solvent-Free Conditions Khodabakhsh NIKNAM;Mohammad Ali ZOLFIGOL;Zahra HOSSIENINEJAD;Nader DANESHVAR 2007, 28 (7):  591-595.  Abstract ( 2133 )   [Full Text(HTML)] () PDF (277KB) ( 924 )   Metal hydrogen sulfates M(HSO4)n(Ca(HSO4)2, Zn(HSO4)2, and oxone) were used to catalyze one-pot three-component condensation reactions of aldehydes,1,3-dicarbonyl compounds, and urea at 90 ℃ under solvent-free conditions to give3,4-dihydropyrimidin-2(1H)-one in high yields.

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Effects of Reduction Atmosphere on Structure and Catalytic Activity of Co-ZrO2 Catalyst for Fischer-Tropsch Synthesis JIA Litao;FANG Kegong;CHEN Jiangang;SUN Yuhan* 2007, 28 (7):  596-600.  Abstract ( 2066 )   [Full Text(HTML)] () PDF (301KB) ( 1170 )   The effects of reduction atmosphere on the structure of the Co-ZrO2 coprecipitation catalyst and its catalytic activity for Fischer-Tropsch synthesis were investigated by means ofX-raydiffraction, transmission electron microscopy, scanning electron microscopy, and temperature-programmed reduction. The reduction of the Co-ZrO2 catalyst in CO atmosphere led to an increase in BET surface area but obvious decrease in syngas atmosphere. The cubic metallic cobalt species (2θ=44.4°) was observed for the catalyst reduced in H2. After the reduction of the catalyst in either syngas or CO, both the cubic metallic cobalt and hexagonal metallic cobalt (2θ=41.7° and 47.5°) appeared with the presence of the carbon deposition. No catalytic activity was detected for the catalyst sample reduced in CO owing to the severe carbon deposition. The catalyst samples reduced in either syngas or H2 showed the similar CO conversion though the carbon deposition was observed for the former, and its high CH4 selectivity could be attributed to the presence of carbon deposition.

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Preparation of Sugar-Based Chiral Salen-Mn(Ⅲ) Complex and Its Application in Asymmetric Epoxidation ZHAO Shanshan;ZHAO Jiquan*;HE Leqin;LI Na;ZHAO Dongmin 2007, 28 (7):  601-606.  Abstract ( 2195 )   [Full Text(HTML)] () PDF (319KB) ( 712 )   A novel chiral salen ligand was synthesized through the reaction of1,2:5,6-di-O-isopropylidene-3-O-methylene-[5-(3-tert-butyl-2-hydroxybenzaldehyde)]-α-D-glucofuranose with (1S,2S)-(-)-1,2-diphenylethylenediamine. The sugar-based chiral salen-Mn(Ⅲ) complex was prepared from this ligand. The ligand and complex were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and elemental analysis. The complex was then used as a catalyst for the asymmetric epoxidation of alkenes using NaClO and m-chloroperoxybenzoic acid as the oxidants. The results showed that the chiral sugar moiety that was incorporated into C5(5′) of the ligand had certain effect on enantioselectivity. Furthermore, the recycle ability of the catalyst was studied in the epoxidation of styrene with m-chloroperoxybenzoic acid as terminal oxidant in the presence of the ionic liquid [bmim]PF6. The enantiomeric excess of the epoxides was still 51% even after the catalyst was used three times.

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PdCl2/PS-Phenol Co-catalyzed Acetalization of Methyl Acrylate with Methanol in Supercritical Carbon Dioxide WANG Zhaoyang;JIANG Huanfeng;*;QI Chaorong;SHEN Yanxia;YANG Shaorong;ZENG Yucai 2007, 28 (7):  607-610.  Abstract ( 2404 )   [Full Text(HTML)] () PDF (192KB) ( 961 )   PdCl2/polystyrene-supported phenol (PS-Phenol) was presented as a co-catalyst for the acetalization of methyl acrylate with methanol in supercritical carbon dioxide under oxygen atmosphere. After methyl acrylate was completely converted, the highest yield and selectivity for methyl3,3-dimethoxypropanoate were 97.7% and 100%, respectively. Compared with small molecular acidic co-catalysts, the separation of PS-Phenol from the reaction system by simple filtration made the recycling of precious palladium practical and convenient.

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Catalytic Promotion of Activated Carbon by Treatment with Some Transition Metal Cations Sahar A. EL-MOLLA;Gamil A. EL-SHOBAKY;Sohair A. SAYED AHMED 2007, 28 (7):  611-616.  Abstract ( 2026 )   [Full Text(HTML)] () PDF (286KB) ( 1054 )   A commercial activated carbon sample was treated with dilute nitric acid (1%) followed by impregnation with 5% and 10% cobalt, nickel, or copper nitrates, which were dissolved in the minimum amounts of distilled water sufficient to cover the surfaces of activated carbon granules followed by drying at 100 ℃ till weights became constant. The transition metal ions-treated samples were heated at 400 ℃ in a flow of argon for 3 h. The analytical tools for characterization of different solids wereX-raydiffraction, nitrogen adsorption at-196℃, infrared spectroscopy, catalytic conversion of iso-propanol, and catalytic decomposition of H2O2 at 25-45 ℃. The results revealed that the activated carbon treated with 5% and 10% transition metal oxides heated at 400 ℃ in a argon flow consisted of a mixture of very poor crystalline CoO, Co3O4, NiO, Cu2O, and CuO phases of nano-crystalline nature. The treatment of activated carbon with cobalt, copper, or nickel oxide led to a small increase in its BET surface area. All solids investigated acted mainly as dehydrogenation catalysts with selectivities above 90%. The percentage increase in the catalytic activity, measured at 225 ℃, due to the treatment with 5% transition metal oxide attained 6%, 24.6%, and 40.6% for cobalt, nickel, and copper oxides, respectively. The observed measurable increase in the catalytic activity of the commercial activated carbon system treated with small amounts of CoO in the catalysis of H2O2 decomposition can be considered as a consequence of the significant increase in the concentration of catalytically active sites taking part in the catalysis of H2O2 decomposition, but it did not modify the mechanism of the catalytic decomposition.

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Characterization and Catalytic Activity of Silylated Nanoscale ZSM-5 WANG Kunyuan;WANG Xiangsheng*;LI Gang;LONG Huayun 2007, 28 (7):  617-621.  Abstract ( 1932 )   [Full Text(HTML)] () PDF (246KB) ( 1028 )   Multiple impregnations and chemical reaction deposition were used to modify the external surface of nanoscale ZSM-5 with tetraethoxysilane. Toluene disproportionation over this silylated ZSM-5 was investigated. The acid sites of the catalysts were measured by modified Hammett indicators and FT-IR spectroscopy of adsorbed pyridine. The catalyst structure was characterized by X-ray diffraction and29SiMAS NMR. The results showed that silanization of the zeolite decreased the concentration of acid sites, which led to the decrease in catalytic activity. The silanization also decreased the amount of Q4 species of Si and the relative crystallinity of the zeolite. Dealumination was observed on the surface of nanoscale ZSM-5. The decrease in the number of framework aluminum resulted in a decline in the number of acid sites and catalytic activity.

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Increase in Concentration and Strength of Acidic Catalytic Sites on Sulfated Zirconia by Doping with Silica S. Tajammul HUSSAIN;Muhammad MAZHAR;Sheraz GUL 2007, 28 (7):  622-626.  Abstract ( 2228 )   [Full Text(HTML)] () PDF (230KB) ( 949 )   Doping sulfated zirconia with silica increases the acidity of the sulfated zirconia. This modified catalyst was used for liquid-phase dehydration of methanol at 413-453 K as a model reaction. Methanol is sequentially dehydrated to dimethyl ether and ethylene over both sulfated zirconia and silica-doped sulfated zirconia in a single step. Also, significant amounts of propylene are formed by the silica-doped catalyst but not by the undoped catalyst. The data were discussed in relation to increased acid active sites after doping with silica, which electronically modified the catalyst surface.

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FT-IR and Density Functional Theory Studies on Surface Acidity of SO2-4/SiO2 GUO Daishi;MA Zifeng*;JIANG Qizhong;YE Weidong;LI Chunbo 2007, 28 (7):  627-634.  Abstract ( 2874 )   [Full Text(HTML)] () PDF (537KB) ( 1179 )   Silica MCM-41 without and with sulfuration treatment was measured by in situ pyridine adsorption infrared spectroscopy. Cluster models of pure SiO2 and SO2-4/SiO2 were built up, and density functional theory calculations on pyridine adsorption were carried out to analyze the surface acidity of SO2-4/SiO2. The combined results of experimental and theoretical studies showed that there were no Lewis acid sites on the surface of SO2-4/SiO2. The IR frequencies assignable to Lewis acidity corresponded to the enhanced hydrogen-bonded adsorption of pyridine by sulfuration treatment. The chelating structure of HSO-4 acts as Brnsted sites on the surface of SO2-4/SiO2, with an acid strength higher than that of sulfonic group-functionalized silica SO3H-MSU but weaker than that of HZSM-5. The acid catalytic activity of SO2-4/SiO2 results from the Bronsted acidity.

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Preparation and Catalytic Performance of Pd Monolithic Catalysts Supported by Y2O3 Washcoat JIN Lingyun;HE Mai;LU Jiqing;JIA Aiping;SU Xiaowen;LUO Mengfei* 2007, 28 (7):  635-640.  Abstract ( 2338 )   [Full Text(HTML)] () PDF (413KB) ( 893 )   A novel Y2O3 washcoat adhered to the cordierite honeycomb was prepared using Y(NO3)3 as the precursor. The Y2O3 washcoat is suitable for supported Pd catalysts. Catalytic combustion of toluene and ethyl acetate was conducted as model reactions to evaluate the performance of Pd/Y2O3 catalysts. The catalysts exhibit fairly good catalytic activity and thermal stability. For the catalysts calcined at 500 ℃, the T99of toluene is 210 ℃. The Y2O3 washcoat and the Pd/Y2O3 catalysts were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy,X-raydiffraction, Raman spectroscopy, and H2-temperature-programmed reduction. The results show that the washcoat has sufficient adhesion and high adsorption efficiency for active species. For the catalysts calcined at higher temperatures (700 ℃ and 900 ℃), the crystallite size of the active species (PdO) increases, which possibly results in a decline in the catalytic activity.

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Theoretical Calculation for Interaction of CO2 with •H and •CH3 in Synthesis of Acetic Acid from CH4 and CO2 ZHANG Riguang;HUANG Wei*;WANG Baojun 2007, 28 (7):  641-645.  Abstract ( 2209 )   [Full Text(HTML)] () PDF (245KB) ( 851 )   The reactions of CO2 with H and CH3 radicals were systematically investigated using the quantum chemistry density functional theory. The reaction mechanism of CO2 with H and CH3 radicals was obtained. The pathway that H or CH3 radical attacked the C atom of CO2 was the preferential pathway in all the four designed reaction pathways. The main product was acetic acid, while methyl formate was inhibited by dynamics. The calculated result was in accordance with the experimental result, which provided a new illustration and guidance for the direct synthesis of oxygenated compounds from CH4 and CO2 by a two-step reaction method.

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Comparison of Electrocatalytic Performance of Different Anodes with Cyclic Voltammetry and Tafel Curves DING Haiyang;FENG Yujie*;LIU Junfeng 2007, 28 (7):  646-650.  Abstract ( 2795 )   [Full Text(HTML)] () PDF (308KB) ( 1446 )   The eletrocatalytic capability of Pt, Ti base RuO2 (Ti/RuO2), and Ti base SnO2 (Ti/SnO2) electrodes was evaluated with cyclic voltammetry (CV) and Tafel curves. CV curves of the three electrodes were measured in 500 mg/L phenol solution, and their phenol oxidation peak potentials were around 0.93, 0.95, and 1.40 V (vs Ag/AgCl), respectively. The capability of direct electrocatalytic oxidation of phenol lied in the sequence of Pt＜Ti/SnO2＜Ti/RuO2. The Tafel curves were measured in 0.1 mol/L H2SO4 and the results showed that the oxygen evolution overpotentials of the three electrodes increased in the order Ti/RuO2

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Influence of Nickel Salt Precursors on the Hydrogenation Activity of Ni/γ-Al2O3Catalyst REN Shibiao;QIU Jinheng;WANG Chunyan;XU Bolian;FAN Yining*;CHEN Yi 2007, 28 (7):  651-656.  Abstract ( 2291 )   [Full Text(HTML)] () PDF (381KB) ( 796 )   The structure and catalytic property of the supported Ni/γ-Al2O3catalysts prepared with different nickel salt precursors for hydrogenation of α-pinene have been studied usingX-raydiffraction, UV-VIS diffuse reflectance spectroscopy, temperature-programmed reduction, CO chemisorption, and microreactor tests. It has been shown that the catalytic hydrogenation activity of the Ni/γ-Al2O3catalyst increases with increasing Ni loading, and the catalytic activity of the nickel acetate-derived Ni/γ-Al2O3catalyst is much higher than that of the nickel nitrate-derived catalyst. The catalyst characterization results indicate that the catalytic hydrogenation activity of Ni/γ-Al2O3catalysts prepared with different nickel salt precursors is correlated to the different ratios of Ni2+ions in the tetrahedral and octahedral vacancies ofγ-Al2O3and the different reduction degrees of the NiO/γ-Al2O3precursors. When the nickel ion loading is far below the dispersion capacity, the supported nickel ions preferentially incorporate into the tetrahedral vacancies ofγ-Al2O3. With increasing nickel loading, the ratio of Ni2+ions that incorporate into the octahedral vacancies ofγ-Al2O3increases. The dispersion capacity of nickel ions onγ-Al2O3derived from nickel acetate is lower than that of the sample derived from nickel nitrate due to the greater shielding effect of acetate anions than nitrate anions. Moreover, the ratio of octahedral Ni2+to tetrahedral Ni2+on the nickel acetate-derived sample is higher than that on the nickel nitrate-derived sample because of the lower density of octahedral vacancies onγ-Al2O3. As octahedral Ni2+ions are easier to be reduced to the metallic state than tetrahedral Ni2+ions, the catalytic activity of the Ni/γ-Al2O3catalyst prepared with the nickel acetate precursor is much higher than that of the catalyst of the same nickel loading prepared with the nickel nitrate precursor.

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Resistance of Nano-Sized Gold Catalysts to Water and Sulfur Poisoning WANG Donghui;DONG Tongxin;SHI Xicheng*;ZHANG Zhongliang 2007, 28 (7):  657-661.  Abstract ( 2243 )   [Full Text(HTML)] () PDF (307KB) ( 1206 )   Au/FeOx/Al2O3 showed more active and stable than Au/Al2O3 in CO oxidation at low temperature. Moisture enhanced the activity of the nano-sized gold catalyst, and higher CO conversion appeared at water partial pressure of 550-1600 Pa in the feed gas. The catalyst was deactivated fast and irreversibly in dry feed gas but slow and reversibly in saturated vapor. The gold particle size increased in the catalyst that was deactivated by saturated vapor. The promoters had no effect on water resistance but had a visible effect on the resistance to H2S or SO2. The main reason of deactivation was the appearance of sulfide or sulfate on the catalyst surface.

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Methanol-Driven Continuous Biosynthesis of Epoxypropane by Methanotrophic Bacteria XIN Jiaying;LIU Mei;ZHANG Yingxin;XIA Chungu;LI Shuben 2007, 28 (7):  662-666.  Abstract ( 2104 )   [Full Text(HTML)] () PDF (306KB) ( 960 )   Methylosinus trichosporium IMV 3011 was cultivated on methanol vapor as carbon source. The methanol vapor-grown culture was adapted to grow on liquid methanol with its gradually increasing concentrations from 0.01% to 1%(volume fraction). After adaptation to high methanol levels, M. trichosporium IMV 3011 was cultured on methanol-methane to obtain a large quantity of cells with methane monooxygenase (MMO) activity. The effect of methanol on the growth of M. trichosporium IMV 3011 and MMO activity was studied. The growth of methanotrophic bacteria was significantly enhanced in comparison to the absence of methanol. In the batchwise epoxidation, the epoxidation capacity of M. trichosporium IMV 3011 was enhanced when methanol was provided, indicating that the methanol could act as an electron donator to drive the synthesis of epoxypropane. Also, the possibility of methanol-driven continuous synthesis of epoxypropane by M. trichosporium IMV 3011 was explored in a membrane reactor. At the most suitable liquid flow velocity of6 ml/h, the epoxypropane concentration in eluate was 2.19 mmol/L and the residual methanol concentration was 1.08 mmol/L. The product inhibition was overcome owing to the continuous removal of epoxypropane. In this process, the reactor was operated continuously for 192 h, and the epoxypropane concentration in eluate was kept to about 1.35 mmol/L. Direct counts and plate counts for M. trichosporium IMV 3011 showed that the bacteria could survive in the process of methanol-driven epoxypropane synthesis.