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Chinese Journal of Catalysis
2008, Vol. 29, No. 7
Online: 25 July 2008

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Synthesis of Propylene Carbonate on a Bifunctional Titanosilicate Modified with Quaternary Ammonium Halides ZHANG Jing;LIU Yueming*;LI Ningning;WU Haihong;LI Xiaohong;XIE Wei;ZHAO Zhonglin;WU Peng*;HE Mingyuan 2008, 29 (7):  589-591.  Abstract ( 2136 )   [Full Text(HTML)] () PDF (164KB) ( 1156 )   A novel bifunctional catalyst that exhibits catalytic activity for both the epoxidation of olefins and the carbonation of organic epoxides has been prepared through grafting quaternary ammonium halide on a titanosilicate. The one-pot synthesis of propylene carbonate from propylene, hydrogen peroxide, and carbon dioxide has been investigated. Delaminated titanosilicate with an open external surface is an excellent support for the immobilization of quaternary ammonium salts, and propyl tributyl ammonium halides are active functional species for the cycloaddition. The combination of delamination and functionalization leads to an active catalyst giving a yield of propylene carbonate as high as 48% and good stability and reusability.

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Microwave Synthesis of a&b-Oriented Zeolite T Membranes and Their Application in Pervaporation-Assisted Esterification ZHOU Han;LI Yanshuo;ZHU Guangqi;LIU Jie;LIN Liwu;YANG Weishen* 2008, 29 (7):  592-594.  Abstract ( 2276 )   [Full Text(HTML)] () PDF (364KB) ( 1037 )   High-performance a&b-oriented zeolite T membranes were prepared by the microwave-assisted hydrothermal method. The membranes were applied to the pervaporation-assisted esterification of acetic acid and n-butyl alcohol at 383 K. Zeolite T membranes could effectively remove water product from the reactant mixtures and improve the conversion of acetic acid to 100% without the loss of reactants or products.

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Mutual Influence of Hydrodesulfurization of Dibenzothiophene and Hydrodenitrogenation of Quinoline over NiMoS/γ-Al2O3Catalyst XIANG Chun’e;CHAI Yongming;LIU Yunqi;LIU Chenguang;* 2008, 29 (7):  595-601.  Abstract ( 2294 )   [Full Text(HTML)] () PDF (382KB) ( 1255 )   Both the influence of quinoline on hydrodesulfurization (HDS) of dibenzothiophene (DBT) and the effect of DBT on hydrodenitrogenation (HDN) of quinoline were studied over a presulfided NiMoS/γ-Al2O3catalyst in a fixed-bed high pressure microreactor. The results suggested that quinoline could strongly inhibit the HDS reaction of DBT, where the inhibitory effect on the hydrogenation route (HYD) was stronger than that on the direct desulfurization route (DDS), which resulted from the competitive adsorption of quinoline and intermediate products of HDN reaction on active sites. The different inhibitory extent of quinoline on the DDS route at 300 and 340 ℃ was closely related to the relative amount of HDN intermediate products. DBT had a positive influence on hydrodenitrogenation ability, which was due to H2S released in the HDS reaction. H2S promoted the conversion of coordinatively unsaturated sites to Brnsted acid sites on the catalyst surface, which in turn facilitatedC(sp3)-Nbond cleavage of the HDN intermediate molecules. Although the formation of active sites for HDN must be in the presence of S, the maintenance of active sites does not need too much S.

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CarbonBased Solid Acid as an Efficient and Reusable Catalyst for CrossAldo l Condensation of Ketones with Aromatic Aldehydes under SolventFree Conditio ns Abbas ZALI*;Kamal GHANI;Arash SHOKROLAHI;Mohammad Hossein KESHAVARZ 2008, 29 (7):  602-606.  Abstract ( 2138 )   [Full Text(HTML)] () Aromatic aldehydes undergo crossaldol condensation with ketones in the presenc e of carbon-based solid acid under solvent free conditions to afford the correspondingα,β-unsaturated aldol products in excellent yields. The catalyst is reusable several times without any decrease in the yield of the reactions.

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Synthesis of Tungsten Carbide Nanocrystals and Its Electrochemical Properties ZENG Jianghua;YUAN Dingsheng*;LIU Yingliang;CHEN Jingxing;TAN Sanxiang 2008, 29 (7):  607-611.  Abstract ( 2425 )   [Full Text(HTML)] () PDF (342KB) ( 1315 )   Tungsten carbide (WC) nanocrystals were prepared by a solvothermal method using Mg as the reductant and WO3 and anhydrous ethanol as the precursors. The effect of time and temperature on the synthesis of WC was investigated and a probable formation mechanism was discussed. The obtained WC crystals were characterized byX-raydiffraction, transmission electron microscopy, energy dispersive spectroscopy, and electrochemical methods. Hexagonal WC was successfully prepared when the temperature was as low as 500 ℃. The content of carbon was more than that of W and the composition of the treated sample was C and WC only. The diameter of WC nanocrystals was ranged from 40 to 70 nm and the crystal was dispersed on C films. The WC nanocrystals promoted the Pt/C electrocatalyst ability obviously for the oxygen reduction reaction with the onset potential over 173 mV, which was more positive compared with that of the traditional Pt/C electrocatalyst.

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In Situ Liquid-Phase Catalytic Hydrogenation for the Synthesis of N-Ethylaniline and N,N-Diethylaniline SHEN Yingni;LUO Zhiwei;YAN Xinhuan* 2008, 29 (7):  612-616.  Abstract ( 2372 )   [Full Text(HTML)] () PDF (297KB) ( 1120 )   In situ liquid-phase hydrogenation of nitrobenzene for the synthesis of N-ethylaniline and N,N-diethylaniline in ethanol-water solution over the Pt/γ-Al2O3catalyst was studied. The Pt/γ-Al2O3catalyst was characterized by N2 adsorption-desorption, inductively coupled plasma atomic emission spectrometry,X-raydiffraction, temperature-programmed desorption, and transmission electron microscopy. The results of the reaction showed that under the conditions of 503 K, 5.0 MPa, 3.2 h-1, and 8% nitrobenzene concentration with 70% ethanol and 30% H2O solution, the nitrobenzene conversion reached 100%, and the total yield of N-ethylaniline and N,N-diethylaniline reached as high as 99.5%. The reaction mechanism was discussed.

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Synthesis of Single-Walled Carbon Nanotubes with Narrow Diameter Distribution by Calcination of a Mo-Modified Fe/MgO Catalyst WEN Qian;QIAN Weizhong*;WEI Fei 2008, 29 (7):  617-623.  Abstract ( 2527 )   [Full Text(HTML)] () PDF (557KB) ( 1092 )   The Fe-Mo/MgO catalyst for the synthesis of single-walled carbon nanotubes (SWNTs) from methane decomposition by chemical vapor deposition was pretreated by calcination at 900 ℃ for 10 h. A comparison of SWNT growth on the catalysts with and without Mo confirmed that Mo addition in the calcined catalyst was crucial in stabilizing and dispersing Fe nanoparticles to a small size, and thus, to synthesize SWNTs with uniform diameters. The products were characterized by energy dispersive spectroscopy, high-resolution transmission electron microscopy,X-raydiffraction, Ar adsorption, Raman spectroscopy, and thermogravimetric analysis. The results showed that Fe-rich nanoparticles were the active sites for SWNT growth and the diameter of the SWNTs depended on the size of the Fe nanoparticles. The calcination led to the formation of the FeMoO4 phase when Mo was added, which is a more stable phase than the MgFe2O4 phase. The Mo/Fe ratio was also important in preparing SWNTs of high density, high purity, and with a narrow diameter distribution. These results are useful for the precise control of the synthesis of SWNTs.

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Preparation of BiVO4-MCM-41 Composite Catalyst and Its Photocatalytic Activity for Degradation of Methylene Blue ZHANG Yan;YU Jianqiang*;Akihiko KUDO;ZHAO Xiusong 2008, 29 (7):  624-628.  Abstract ( 2746 )   [Full Text(HTML)] () PDF (331KB) ( 1061 )   The BiVO4-MCM-41 composite catalyst was prepared by supporting BiVO4 with monoclinic scheelite structure on the surface of MCM-41 molecular sieve. The BiVO4-MCM-41 samples were characterized and their photocatalytic activity for degradation of methylene blue was measured. It was found that the zircon structure or tetragonal structure of BiVO4 was first crystallized on the surface of MCM-41 molecular sieve, and under the hydrothermal treatment, the monoclinic scheelite structure of BiVO4 was formed from the zircon structure or tetragonal structure. The catalyst possessed a larger specific surface area and therefore improved its photocatalytic activity for degradation of methylene blue owing to the increase of adsorption performance.

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Preparation of 1-Butyl-3-methylimidazolium Dodecatungstophosphate and Its Catalytic Performance for Esterification of Ethanol and Acetic Acid SHI Jiehua;*;PAN Gao 2008, 29 (7):  629-632.  Abstract ( 2821 )   [Full Text(HTML)] () PDF (228KB) ( 1197 )   A 1-butyl-3-methylimidazolium dodecatungstophosphate ([bmim]3PW12O40) catalyst with high resistance to water was prepared from 1-butyl-3-methylimidazolium bromide ([bmim]Br) and dodecatungsto-phosphoricacid (H3PW12O40). The catalyst was characterized by means of Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, n-BuNH2 potentiometric titration, and elemental analysis. Its catalytic activity for esterification of ethanol and acetic acid to ethyl acetate was measured. The results showed that there were three crystal-water molecules in the [bmim]3PW12O40catalyst, and it preserved the primary Keggin structure and acid strength of H3PW12O40. The acid amount of the [bmim]3PW12O40catalyst was less than that of H3PW12O40. The [bmim]3PW12O40catalyst exhibited higher catalytic activity and reusability in the esterification of ethanol and acetic acid to ethyl acetate.

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Aerobic Oxidation Removal of 1-Pentanethiol from Gasoline Ⅰ. Catalytic Activity of CuZnAl Composite Oxide GAO Lida;XUE Qingsong;LU Yong*;HE Mingyuan 2008, 29 (7):  633-637.  Abstract ( 2178 )   [Full Text(HTML)] () PDF (300KB) ( 1065 )   The aerobic oxidation of 1-pentanethiol in gasoline was carried out by mixing a small amount of air in gasoline and passing through a fixed-bed reactor packed with the CuZnAl composite oxide catalyst. The effects of reaction parameters, such as weight hourly space velocity, O2/S molar ratio, and reaction temperature, on the reaction performance were investigated. This process could proceed at high WHSV (50-70 h-1) with high 1-pentanethiol conversion (>95%) at 150 and 300 ℃ using an O2/S molar ratio of 20. The dimerization of 1-pentanethiol occurred dominantly to form its dimer at 150 ℃. The deep oxidation of 1-pentanethiol to SO2 was the dominant process at 300 ℃ in first tens of hours, but it decreased with prolonged time on stream and meanwhile the dimerization increased.

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A Pd(OAc)2/[mmim]I Catalyst System for Oxidative Carbonylation of Amines to Carbamates, Ureas, and 2-Oxazolidinones PENG Xingao;LI Fuwei;HU Xiaoxue;XIA Chungu*;Christian A. SANDOVAL 2008, 29 (7):  638-642.  Abstract ( 2221 )   [Full Text(HTML)] () PDF (264KB) ( 962 )   A Pd(OAc)2/[mmim]I ([mmim]I=1-methyl-3-methylimidazolium iodide) catalyst system was applied to the oxidative carbonylation of aliphatic amines, aromatic amines, and amino alcohols to carbamates, ureas, and 2-oxazolidinones under different conditions. The catalytic turnover frequencies (TOF, moles of amines converted per mole of catalyst per hour) were12417,17368, and4114h-1for the production of methyl N-phenyl carbamate, N,N′-diphenyl urea, and 2-benzoxazolinone, respectively.

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Surface Structure and Catalytic Performance of CuCl/SiO2-Al2O3 Catalysts for Methanol Oxidative Carbonylation LI Zhong*;MENG Fanhui;REN Jun;ZHENG Huayan;XIE Kechang 2008, 29 (7):  643-648.  Abstract ( 2342 )   [Full Text(HTML)] () PDF (400KB) ( 1076 )   Aluminum was doped into amorphous silica gel to modify its surface structure. The obtained SiO2-Al2O3 support was used to prepare the CuCl/SiO2-Al2O3 catalyst by solid-state ion exchange, and the catalyst activity for liquid-phase oxidative carbonylation of methanol to dimethyl carbonate was investigated. The results showed that the prepared SiO2-Al2O3 support kept the amorphous structure of the silica gel. The BET specific surface area of the silica gel was decreased to 200 m2/g, and the surface acid sites (including Brnsted acid sites) were increased. In the CuCl/SiO2-Al2O3 catalyst, CuCl was not only dispersed on surface but also was ion exchanged with surface Brnsted acid sites of the SiO2-Al2O3 support to form Cu+ species, which resulted in a decrease in BET specific surface area to 148 m2/g. These two kinds of Cu+ species on the catalyst surface were both active centers for the oxidative carbonylation of methanol to dimethyl carbonate. When the catalyst was prepared with Si/Al molar ratio of 5 and was calcined at 500 ℃, the selectivity and space-time yield of dimethyl carbonate reached 74% and 1.27 g/(g·h), respectively.

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Simultaneous Removal of Soot Particles and NO from Diesel Engines over LaBO3 Perovskite-Type Oxides WANG Hong;ZHAO Zhen*;XU Chunming;DUAN Aijun;LIU Jian;CHI Yaoling 2008, 29 (7):  649-654.  Abstract ( 2220 )   [Full Text(HTML)] () PDF (429KB) ( 1084 )   The nanometric LaBO3(B=V, Cr, Mn, Fe, Co, Ni, Cu) oxides were prepared by the organic acid ligation method. The samples were characterized by the techniques of XRD, UV-Vis, FT-IR, H2-TPR, and SEM. The catalytic performance of the prepared samples for the simultaneous removal of soot and NO emitted from diesel engines was investigated. The results showed that the synthesized LaBO3 (B=Cr, Mn, Fe, Co, Ni) oxides possess perovskite-type structures except for La-Cu-O and La-V-O. The oxidizing ability of these five perovskite oxides follows the order of LaNiO3≈LaCoO3＞LaMnO3＞LaFeO3＞LaCrO3, which is consistent with their activity sequence for the desired reactions. Thus their catalytic performance is closely related to the oxidizing ability of these perovskite oxides. Among them, LaCoO3 and LaNiO3 have higher activities for the simultaneous removal of soot and NO. The combustion temperatures (Tm) of soot particles over them are 421 and 431 ℃, respectively, when the contact between catalysts and soot are loose. The selectivities of CO2 are 99.1% and 99.7%, and NO conversions are 17.2% and 20.1%, respectively.

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Hydrogen Storage Capacity of Nickel Supported on a Metal-Organic Framework Compound under Mild Conditions LIU Yingya;ZHANG Jian;ZENG Julan;CHU Hailiang;XU Fen*;SUN Lixian* 2008, 29 (7):  655-659.  Abstract ( 2543 )   [Full Text(HTML)] () PDF (362KB) ( 1312 )   The traditional impregnation method was used to support nickel ions on the metal-organic framework compound MIL-101 (Cr3F(H2O)2O[(O2C)-C6H4-(CO2)]3·nH2O, n≈25) for the preparation of a Ni/MIL-101 composite material. With two ways of impregnation (excessive impregnation and incipient wetness impregnation) followed by two ways of reduction (liquid chemical reduction and solid hydrogenation reduction), four Ni/MIL-101 samples were obtained. The hydrogen storage capacity of the Ni/MIL-101 samples was measured under mild conditions(25-100℃,0.01-4MPa). Compared with the original MIL-101, Ni/MIL-101 had high hydrogen storage capacity because of the Ni particles supported on MIL-101. Among these samples, the sample prepared by excessive impregnation followed by liquid chemical reduction exhibited the highest hydrogen storage capacity of 1.02% at 100 ℃ and 4.0 MPa.

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Influences of Reaction Conditions on Ethene Conversion to Propene over SAPO-34 LI Jinzhe;QI Yue;LIU Zhongmin*;LIU Guangyu;CHANG Fuxiang 2008, 29 (7):  660-664.  Abstract ( 2233 )   [Full Text(HTML)] () PDF (324KB) ( 1005 )   Ethene conversion to propene was carried out over SAPO-34. The influences of reaction conditions on the catalytic performance were investigated in detail. It was found that the propene selectivity increased with space velocity. Ethene conversion decreased with reaction temperature, whereas the selectivity for methane and ethane increased. At the same level of ethene conversion the propene selectivity decreased with reaction temperature. An obvious induction period was observed in the ethene conversion over SAPO-34, and it was strongly influenced by the reaction conditions.

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Aromatization of C5-C8 Alkane Mixture over Modified Nano-Sized HZSM-5 Zeolite Catalysts ZHOU Jianhong;ZHAO Yun;SONG Jinfu;AISHA·Nulahong;HU Jia;CHEN Lixing;GUO Hongchen* 2008, 29 (7):  665-670.  Abstract ( 2295 )   [Full Text(HTML)] () PDF (373KB) ( 1183 )   The effects of steaming and impregnation with transition metal (Ni, Co, Cu, Zn) salt solution on the catalytic performance of nano-sized HZSM-5 zeolite catalysts for the aromatization ofC5-C8alkane mixture were studied in a small fixed-bed reactor. The surface acidity of the modified zeolite catalysts was characterized by NH3-TPD and Py-FT-IR, and the surface acidity was correlated to the aromatization performance. The results showed that steaming treatment at 450 ℃ could notably increase the selectivity for aromatization over the zeolite catalysts, and less methane and ethane were produced. The impregnation of the steamed nano-sized HZSM-5 zeolite with copper or zinc nitrate solution significantly strengthened its resistance to coking deactivation. It was because that steaming treatment decreased both the amount and strength of acid sites on the zeolite surface, while the impregnation with copper or zinc nitrate solution further decreased Brnsted acid sites, increased Lewis acid sites, and generated active dehydrogenation sites by cooperating with Brnsted acid sites, thereby made an impact on both the activation way and the aromatization path of the alkane mixture.

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Vapour-Phase o-Methylation of Catechol with Methanol on SiO2 -Supported Ammonium Metatungstate Catalysts ZOU Xiujing;ZHU Xiaomei;LI Xuemei;WANG Zhenlü;LIU Gang;JIA Mingjun*;ZHANG Wenxiang* 2008, 29 (7):  671-676.  Abstract ( 2298 )   [Full Text(HTML)] () PDF (471KB) ( 1047 )   Catalytic properties of SiO2-supported ammonium metatungstate (AMT) catalysts calcined at different temperatures were investigated for the vapour-phase o-methylation of catechol with methanol. The catalysts calcined at 533 and 573 K showed relatively high catechol conversion (97%) and guaiacol selectivity (91%). The results of temperature-programmed desorption and infrared spectroscopy of adsorbed pyridine revealed that all the tested catalysts possessed weak acid-base sites, which might be the main active sites of the reaction. The stability of AMT/SiO2 calcined at 533 K was studied, and no obvious activity loss occurred within 46 h. With further increase of reaction time, the catalyst activity decreased gradually, but the selectivity for the main product remained almost steady. According to the results of scanning electron microscopy and TGA-DTA thermal analysis, it can be deduced that the coke deposited on the surface of AMT/SiO2 was the main reason for the catalyst deactivation. The catalytic properties of the catalyst could be partially recovered by calcining the used catalyst at a suitable temperature in air.