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Chinese Journal of Catalysis
2006, Vol. 27, No. 7
Online: 25 July 2006

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Electrocatalytic Activity of Polyaniline-Poly(Propylene Oxide) Prepared in Ionic Liquid [bmim]HSO4 LI Meichao, SHEN Zhenlu, MA Chun'an, GAO Yunfang 2006, 27 (7):  541-543.  Abstract ( 1703 )   [Full Text(HTML)] () PDF (241KB) ( 668 )   Copolymerization of aniline and propylene oxide was carried out galvanostatically in an ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim]HSO4). Scanning electron microscopy shows that the copolymer of polyaniline-poly(propylene oxide) (PAN-PPO) is composed of nanofibers with diameters less than 80 nm. The electrocatalytic activity of PAN-PPO for electrooxidation of oxalic acid is perfect. In situ FT-IR spectroscopy was used to investigate the electrooxidation preliminarily.

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Preparation of LTA Zeolite Membranes with Few Non-Zeolite Pores Using Microwave Heating LI Yanshuo, LIU Jie, CHEN Hongliang, YANG Weishen*, LIN Liwu 2006, 27 (7):  544-546.  Abstract ( 1991 )   [Full Text(HTML)] () PDF (328KB) ( 667 )   High-performance LTA zeolite membranes were synthesized on tubular supports by a modified in situ synthesis strategy. The preparation by conventional heating (CH) and microwave heating (MH) was studied. Both CH- and MH-synthesized membranes showed high dehydration performance toward 95.0% isopropanol/water mixtures. However, when the water content in the feed was lower than 2.0%, the CH-synthesized membrane had no separation ability any more. This is due to the existence of nano-sized non-zeolite pores in the zeolite membranes. These defects could be eliminated mostly using fast and homogenous MH.

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Catalytic Oxidation of Benzothiophene and Dibenzothiophene in Model Light Oil Over Ti-MWW CHENG Shifu, LIU Yueming, GAO Jinbao, WANG Lingling, LIU Xiuli, GAO Guohua*, WU Peng, HE Mingyuan 2006, 27 (7):  547-549.  Abstract ( 2079 )   [Full Text(HTML)] () PDF (188KB) ( 1044 )   An oxidative desulfurization process for model light oil over Ti-MWW was investigated. Benothiophene and dibenothiophene are oxidized to their corresponding sulfoxides and sulfones, which can be removed by extraction using acetontrile. The conversion of benothiophene and dibenothiophene is 100% and 95%, respectively, at 343 K. The effect of solvent was also studied. Under the same conditions, the conversion of benzothiophene in three solvents is in the order acetonitrile>methanol>water.

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Synthesis of β-Hydroxyl Selenides from Ring-Opening Reaction of Epoxides with ArSeH Catalyzed by ZnCl2 YANG Minghua1,2*, YANG Hongwei2, ZHENG Yunfa1, ZHU Chengjian2,3 2006, 27 (7):  550-552.  Abstract ( 2151 )   [Full Text(HTML)] () PDF (187KB) ( 942 )   ZnCl2-catalyzed selenolysis of epoxides with ArSeH was investigated in ethanol at room temperature. A variety of β-hydroxyl selenides were obtained in excellent yield and good regioselectivity by the simple, efficient and atomic economic procedure. Starting from epoxide o-cresyl glycidyl ether, a one-pot three-step procedure was used for the chemoselective synthesis of N-tosyl-1,3-oxazolidin-2-ones.

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In Situ XRD Study on Sodium Salt-Modified Mn/SiO2 Catalysts for the Oxidative Coupling of Methane HOU Sicong, CAO Yuan, XIONG Wei, LIU Lingtao, KOU Yuan* 2006, 27 (7):  553-555.  Abstract ( 2106 )   [Full Text(HTML)] () PDF (297KB) ( 782 )   Sodium salt-modified Mn/SiO2 catalysts have been characterized by in situ X-ray diffraction. The results indicate that the low melting point sodium salts exhibit amorphous features under reaction conditions and they are good promoters for the Mn/SiO2 catalyst for the oxidative coupling of methane.

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Photocatalytic Water Splitting to Hydrogen over a Visible Light-Driven LaTaON2 Catalyst LIU Meiying1, YOU Wansheng1, LEI Zhibin1, Tuyoshi TAKATA2, Kazunari DOMEN2*, LI Can1* 2006, 27 (7):  556-558.  Abstract ( 2236 )   [Full Text(HTML)] () PDF (194KB) ( 1087 )   LaTaON2 with a perovskite structure has been successfully prepared by a high-temperature ammonolysis technique using NH4Cl as the mineralizer. The optical absorption edge of LaTaON2 is significantly red-shifted compared to that of LaTaO4. Under visible light irradiation, LaTaON2 with Pt or Ru as a co-catalyst shows high activity for reduction of water to H2 in the presence of ethanol as a sacrificial electron reagent. A remarkable improvement in production efficiency was observed when both Pt and Ru are present.

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Liquid-Phase Hydrogenation of Nitrobenzene to Aniline Using Solvent Hydrogen from Ethanol Reforming YANG Jianfeng, SUN Junqing, LI Xiaonian, YAN Xinhuan* 2006, 27 (7):  559-561.  Abstract ( 2139 )   [Full Text(HTML)] () PDF (156KB) ( 1274 )   Hydrogen was produced by the liquid-phase reforming of ethanol and used directly for the hydrogenation of nitrobenzene to aniline. The reaction was remarkably affected by the catalysts and experimental parameters, such as reaction time and reaction temperature. The most favorable activity and selectivity were obtained when Pt/Al2O3 was used as the catalyst at 220 ℃ for 3 h. The highest conversion of nitrobenzene reached 99.3% and the selectivity for aniline was as high as 99.8%. The results demonstrated that it is capable for the hydrogention of nitrobenzene to produce aniline using solvent hydrogen from the liquid-phase reforming of ethanol without the use of additional molecular hydrogen.

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Effects of Feeding Mode and Substrate Concentration on the Cyclohexanone Ammoximation over Ti-MWW Catalysts SONG Fen, LIU Yueming, WANG Lingling, ZHANG Haijiao, WU Haihong, WU Peng*, HE Mingyuan 2006, 27 (7):  562-566.  Abstract ( 2094 )   [Full Text(HTML)] () PDF (275KB) ( 883 )   The liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide was conducted over the Ti-MWW catalyst. The operating conditions of the reaction, especially the feeding mode of H2O2 greatly affected the catalytic performance of Ti-MWW. In addition, the concentration of H2O2 also affected the ammoximation reaction. Under the optimum reaction conditions, the cyclohexanone conversion and oxime selectivity were both over 99%.

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Steam Reforming of Ethanol over Ni-Cu/CeO2 Catalyst ZHANG Baocai, LI Yong, CAI Weijie, TANG Xiaolan, XU Yide, SHEN Wenjie* 2006, 27 (7):  567-572.  Abstract ( 2080 )   [Full Text(HTML)] () PDF (419KB) ( 1044 )   The catalytic performance of Ni-Cu/CeO2 catalyst for hydrogen production from ethanol steam reforming was investigated with respect to the roles of nickel and copper. The structure and surface characteristics of the catalyst were measured by temperature-programmed reduction, X-ray diffraction, and transmission electron microscopy. It was revealed that the interactions among Cu, Ni, and CeO2 greatly improved the dispersion of Ni particles and consequently enhanced the catalytic activity, but too much copper decreased the activity of the catalyst. Ni was more effective in the cleavage of C[KG-45x]-[KG-20x]C and C[KG-45x]-[KG-20x]H bonds than Cu, and thus ethanol was entirely converted even at much lower temperatures. Additionally, Ni also exhibited excellent methane reforming capability at higher temperatures. Cu favored the dehydrogenation of ethanol to acetaldehyde and water-gas shift reaction at low temperatures, and only showed limited ability for ethanol decomposition at high temperatures.

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Mechanism of Synthesis of 1,5-Naphthalene Dicarbamate from1,5-Naphthalene Diamine and Dimethyl Carbonate XIAO Fukui1,2,3, ZHANG Desheng3, DONG Qingnian1, WEN Dongmei3, PAN Ling3, JIAO Liping3, WEI Wei1*, SUN Yuhan1 2006, 27 (7):  573-578.  Abstract ( 1892 )   [Full Text(HTML)] () PDF (478KB) ( 962 )   The methoxycarbonylation mechanism of 1,5-naphthalene diamine with dimethyl carbonate catalyzed by zinc acetate was investigated by Fourier transform infrared spectroscopy. Zinc acetate dihydrate was not active for the reaction until it changed into anhydrous zinc acetate by losing the crystal water. Anhydrous zinc acetate activated 1,5-naphthalene diamine by the formation of a new zinc complex. The new complex was a suitable nucleophilic reagent that could react with dimethyl carbonate to produce a methoxycarbonylation compound. When the complex of anhydrous zinc acetate with 1,5-naphthalene diamine was formed, the anhydrous zinc acetate changed from a bidentate ligand to a unidentate ligand.

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Influence of Ni Loading on Properties of Ni/TiO2 Catalyst for Hydrogenation of o-Chloronitrobenzene to o-Chloroaniline XIONG Jun, CHEN Jixiang*, ZHANG Jiyan 2006, 27 (7):  579-584.  Abstract ( 1970 )   [Full Text(HTML)] () PDF (425KB) ( 899 )   A series of titania-supported nickel catalysts with different Ni loadings (10%～40%) were prepared by the incipient impregnation method and applied in the hydrogenation of o-chloronitrobenzene to o-chloroaniline. The effects of nickel loading on the physico-chemical properties of the Ni/TiO2 catalysts were studied by nitrogen adsorption-desorption, X-ray diffraction, temperature-programmed reduction, transmission electron microscopy, and H2 chemisorption. The catalyst performance for the hydrogenation was evaluated in an autoclave reactor. The results showed that the o-chloronitrobenzene conversion increased with increasing Ni loading of the Ni/TiO2 catalysts. When the Ni loading was higher than 30%, no remarkable difference in catalyst performance was observed. For the catalysts with Ni loadings higher than 20% under the reaction conditions of temperature 343 K, hydrogen pressure 1.0 MPa, and catalyst to o-chloronitrobenzene mass ratio of 1/10, both the o-chloronitrobenzene conversion and the selectivity for o-chloroaniline exceeded 99% within 210 min. Hence, Ni/TiO2 is a promising catalyst for the synthesis of o-chloroaniline. The characterization results suggested that Ni surface area and the strong metal-support interaction were important factors affecting the catalyst performance, whereas there was no distinct relation between the specific surface area and catalytic performance of the catalyst.

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Effect of Aging Method on the Synthesis of MCM-22 Zeolite in Fluoride System WU Jianmei, WANG Baoyu, LI Niu, XIANG Shouhe* 2006, 27 (7):  585-590.  Abstract ( 1953 )   [Full Text(HTML)] () PDF (343KB) ( 865 )   Zeolite MCM-22 was synthesized hydrothermally under static conditions using NaF and hexamethyleneimine as the mineralizing agent and template, respectively. The effects of aging processes (static aging, stirred aging, and ultrasonic aging) on the synthesis of zeolite MCM-22 were investigated. All the above aging treatment methods accelerated the formation of MCM-22, and the ultrasonic aging showed the best effect. The aging treatment with ultrasound noticeably broadened the range of SiO2/Al2O3 molar ratio (the SiO2/Al2O3 molar ratio of the final gel was 20[KG-45x]-[KG-20x]100), shortened the crystallization time to 48～62 h, and changed the morphology of MCM-22 in the fluoride system.

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Preparation of Ni/CNTs Catalyst and Its Catalytic Performance for Vapor-Phase Carbonylation of Methanol ZHANG Ning*, ZHOU Donglan, ZHU Yu 2006, 27 (7):  591-595.  Abstract ( 2007 )   [Full Text(HTML)] () PDF (299KB) ( 991 )   The nickel catalyst supported on carbon nanotubes (CNTs), prepared by the incipient impregnation method, was employed for the vapor-phase carbonylation of methanol. The effects of the preparation and pretreatment conditions on catalytic activity of the Ni/CNTs catalyst were studied. The catalyst was characterized by means of transmission electron microscopy, X-ray diffraction, and infrared reflectance spectroscopy. The catalytic activity of Ni/CNTs was strongly influenced by the pretreatment conditions. The catalyst showed a high dispersion when the CNTs was pretreated with HNO3 and subsequently activated with Na2CO3. When the Ni/CNTs was calcined under N2 atmosphere at 300 ℃ for 2 h and then reduced under H2 atmosphere at 500 ℃ for 3 h, the prepared Ni/CNTs catalyst showed the highest catalytic activity for the vapor-phase carbonylation of methanol.

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Effect of Carbon Nanotubes on Activity of Rh-Ce-Mn/SiO2 Catalyst for CO Hydrogenation to Oxygenates HUANG Lihong1,2, CHU Wei1*, HONG Jingping1, LUO Shizhong1 2006, 27 (7):  596-600.  Abstract ( 1771 )   [Full Text(HTML)] () PDF (369KB) ( 936 )   The carbon nanotubes (CNTs)-promoted Rh-Ce-Mn/SiO2 catalysts were prepared by the impregnation method and characterized by X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction, N2 adsorption, X-ray diffraction (XRD), and temperature-programmed desorption of H2 or CO. The catalytic performance of Rh-Ce-Mn-CNTs/SiO2 for CO hydrogenation to oxygenates was investigated. The results of XPS and XRD showed that the introduction of CNTs improved the dispersion of Rh and caused an enrichment of active components on the catalyst surface. Meanwhile, the addition of CNTs modified the interaction between rhodium and other components, and the amount of strongly adsorbed H2 or CO on the surface of the catalyst was increased remarkably. The results of CO hydrogenation showed that the existence of CNTs enhanced the activity of the Rh-Ce-Mn/SiO2 catalyst. Under the specific reaction conditions, the CO conversion was 11.86% and the yield of oxygenates was 336.2 g/(kg•h) when the CNTs content was 10%.

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Synthesis and Characterization of ERB-1 Zeolite NIU Xionglei1,2, XIE Sujuan1, XU Longya1* 2006, 27 (7):  601-605.  Abstract ( 2078 )   [Full Text(HTML)] () PDF (369KB) ( 799 )   The ERB-1 zeolite was synthesized using silica aerogel as the silica source, boric acid as the boron source, and sodium hydroxide as the alkali source, respectively. The obtained ERB-1 zeolite was characterized by X-ray diffraction (XRD), N2 adsorption, NH3 temperature-programmed desorption (NH3-TPD), thermogravimetry analysis (TG), differential thermal analysis (DTA) and Fourier-transform infrared reflectance spectroscopy (FT-IR). It was found that the suitable synthesis gel compositions were n(SiO2)/n(B2O3)=0.6～2, n(H2O)/n(SiO2)=40, n(NaOH)/n(SiO2)=0.1～0.2, and n(HMI)/n(SiO2)=0.8～1. The FT-IR result indicated that a part of boron atoms had incorporated into the framework of ERB-1 zeolite. The TG, DTA, and XRD results showed that the ERB-1 zeolite maintained its framework below 800 ℃ when it was calcined in air flow. The NH3-TPD result exhibited that the ERB-1 zeolite had poor acidity and the weak acid was in the majority of its acid sites.

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In Situ Deposition of Pt Nanoparticles on Carbon Nanotube Electrode SHAO Yuyan, YIN Geping*, ZHANG Jian, GAO Yunzhi, SHI Pengfei 2006, 27 (7):  606-610.  Abstract ( 2153 )   [Full Text(HTML)] () PDF (362KB) ( 1083 )   Carbon nanotubes (CNTs) supported Pt (Pt/CNTs) electrode was prepared with in situ ion-exchange method. X-ray photoelectron spectroscopy analysis and scanning electron microscope images showed that Pt nanoparticles were highly dispersed on the surface of electrochemically functionalized CNTs electrode, with Pt particle size of 4.0 nm as determined from X-ray diffraction analysis. The electrochemical surface area and the Pt utilization were enhanced in the ion-exchanged Pt/CNTs electrode, and the electrocatalytic activity for oxygen reduction was higher than the conventional electrode. This was attributed to the specific structure of the ion-exchanged Pt/CNTs electrode, in which almost all the Pt nanoparticles were deposited on the electrochemically active sites.

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Biosynthesis of Oleyl Oleate by Whole-Cell Lipase from Rhizopus chinensis JIN Liang, XU Yan*, CAO Guangqun 2006, 27 (7):  611-614.  Abstract ( 2324 )   [Full Text(HTML)] () PDF (305KB) ( 925 )   The catalytic activity of ten lipases from different sources was compared for the esterification of oleic acid and oleic alcohol to produce oleyl oleate, a new kind of additives used in cosmetic. The whole-cell lipase of Rhizopus chinensis CCTCC M201021 showed the highest conversion (above 90%). Various reaction parameters were optimized to obtain high yield of oleyl oleate. The optimum concentration of oleic acid was 0.3 mol/L, the best organic solvent was n-hexane, and the suitable water content of the dried cells was 3.0%～7.5%. When the molar ratio of oleic acid/oleic alcohol was 1.5, the reaction reached the highest conversion at 30 ℃. The pH range of the whole-cell lipase was wide and the optimal pH value was 9.0.

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Isotopic Tracer Study on Mechanism of Direct Synthesis of Dimethyl Carbonate Promoted by K2CO3/CH3I CAI Zhenqin1,2*, XU Chunming1, ZHAO Suoqi1, XU Zhiming1, SUN Xuewen1, ZHANG Min1 2006, 27 (7):  615-618.  Abstract ( 1976 )   [Full Text(HTML)] () PDF (268KB) ( 750 )   Direct synthesis of dimethyl carbonate (DMC) by CO insertion into methanol promoted by K2CO3/CH3I was studied by the isotopic tracer technique. It is confirmed that the base catalyst K2CO3 participates in the synthesis process. The carbonyl group of DMC is formed by CO2 insertion, and the two methyl groups of DMC are from methanol and iodomethane, respectively. the DMC formation and the dimethyl ether formation follows the mechanisms proposed in the literature, and the combination of the former mechanisms can well explain the experimental results.

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Electrocatalytic Oxidation and Amperometric Determination of Epinephrine over a Gold Electrode Modified by Osmium Bipyridine-Containing Redox Polymer Film FEI Junjie*, TAN Hongyan, CHEN Xiaoming, LI Junan 2006, 27 (7):  619-623.  Abstract ( 2071 )   [Full Text(HTML)] () PDF (262KB) ( 992 )   An osmium bipyridine-containing redox polymer (POs-EA) film-modified gold electrode based on an electrochemical reduction method was developed. The POs-EA film-modified gold electrode exhibited classical features of a kinetically fast redox couple bound to the electrode surface and excellent electrocatalytic activity towards the oxidation of epinephrine. In contrast to a bare gold electrode, the oxidation current of epinephrine increased greatly and the oxidation peak potential shifted negatively to about 0.29 V (vs SCE) over the redox polymer film-modified electrode. Furthermore, the possible catalytical mechanism of epinephrine oxidation was proposed. Amperometric measurements were performed at an applied potential of 0.29 V and a linear response of epinephrine was obtained in the range of 5×10-8～1×10-5 mol/L with a detection limit of 1.5×10-8 mol/L. The proposed procedure was successfully applied to the determination of epinephrine in epinephrine hydrochloride injections.

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Hydrodesulfurization of Dibenzothiophene over ex Situ Presulfided MoNiP/γ-Al2O3 Catalyst LI Yanpeng*, LIU Dapeng, LIU Xiao, CHAI Yongming, LIU Chenguang 2006, 27 (7):  624-630.  Abstract ( 2087 )   [Full Text(HTML)] () PDF (614KB) ( 766 )   Two ex situ presulfided MoNiP/γ-Al2O3 catalysts have been prepared, and their hydrodesulfurization performance has been evaluated using dibenzothiophene as the model compound. A conventional in situ presulfided MoNiP/γ-Al2O3 catalyst was selected as the competitor. The differences in the hydrogenation active phases of the two types of presulfided catalysts have been studied by X-ray diffraction (XRD), high-resolution transmission electron icroscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The ex situ presulfided catalysts had a similar sulfur removal rate (99%) to the in situ presulfided one, but showed a lower hydrogenation activity. Morphology studies using XRD and HRTEM showed that the ex situ presulfided catalysts had a lower stacking number of MoS2 slabs. The XPS results showed that both the sulphidity of Mo and the content of MoS2 active phase of the ex situ presulfided catalyst were lower than those of the in situ presulfided one. The difference in active phase of the two types of presulfided catalysts led to their different hydrogenation activity.

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Asymmetric Reduction of Acetophenone to α-Phenylethanol by Candida valida under Compressed CO2 YING Xiaojiao, YAO Shanjing*, GUAN Yixin 2006, 27 (7):  631-635.  Abstract ( 2087 )   [Full Text(HTML)] () PDF (344KB) ( 745 )   The asymmetric reduction of acetophenone to optically active α-phenylethanol catalyzed by cells of Candida valida CICC1444 under compressed CO2 without agitation was investigated. The reaction by the unimmobilized whole cells under compressed CO2 was feasible, and the R-enantiomer of α-phenylethanol was excessive. The yield of α-phenylethanol was greatly influenced by operating parameters such as concentration of acetophenone, cell mass, temperature, and pressure. Compared with the reaction at ambient pressure without agitation, the conversion of acetophenone and yield of α-phenylethanol under compressed CO2 were increased by 20% and 40%, respectively, and the enantiomeric excess of (R)-α-phenylethanol was increased by 5%[CD*2/3]10%.

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Adsorption and Activation of NH3 during Selective Catalytic Reduction of NO by NH3 LIU Qingya1, LIU Zhenyu2*, LI Chengyue1 2006, 27 (7):  636-646.  Abstract ( 3019 )   [Full Text(HTML)] () PDF (478KB) ( 1098 )   Selective catalytic reduction (SCR) of NO by NH3 is a well studied and demonstrated technology for effective NOx removal from flue gas. However, mechanisms involved in this reaction system including the SCR reaction and NH3 oxidation (side reactions of the SCR) are still not clear. For further advancement in SCR catalysis and catalyst design, systematic literature analyses on the SCR reaction and NH3 oxidation was carried out in this study. In the case of V2O5/TiO2 catalysts, most researchers believed that NH+4 on Bronsted acid sites is responsible for the SCR reaction and that NH+3 (ads) was the intermediate. A few researchers, however, suggested that the SCR reaction was related to NH3 on Lewis acid sites and that NH2(ads) was the intermediate. In the case of other SCR catalysts, it was thought that NH2(ads) from H-abstraction of coordinated NH3 on Lewis acid sites was the intermediate in both SCR reaction and NH3 oxidation to N2, and NH(ads) from H-abstraction of NH2(ads) was the intermediate in the oxidation of NH3 to N2O and NO. Despite the apparent differences, these two types of mechanisms share a common ground from the viewpoint of sequential H-abstraction (or oxidation) of NH3. The adsorbed NH3, either in the protonated form (NH+4) or in the coordinated form (NH3), is partially oxidized by the adsorption sites first before taking part in these reactions. Because the Lewis acid sites and Bronsted acid sites are exchangeable under the SCR conditions due to the presence of H2O, the differences in various SCR mechanisms due to the difference in acid sites are not fundamental. Based on this viewpoint, it was concluded that the SCR activity was determined by the amount of NH3 adsorbed on the surface and the H-abstraction extent of NH3(ads), which relate to the surface acidity and the redox properties. Temperature also affects the NH3 adsorption and H-abstraction ability of SCR catalyst. Regulations of the surface acidity and redox properties of a catalyst with respect to reaction temperature is of importance for the high SCR activity.