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    Chinese Journal of Catalysis
    2007, Vol. 28, No. 1
    Online: 25 January 2007

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    Articles
    Catalytic Decomposition of Hydroxyl Ammonium Nitrate at Room Temperature
    REN Xiaoguang1,2, LI Minghui2, WANG Aiqin1, LI Lin1, WANG Xiaodong1, ZHANG Tao1*
    2007, 28 (1):  1-2. 
    Abstract ( 2056 )   [Full Text(HTML)] () PDF (117KB) ( 968 )  
    A series of alumina- or silica-supported precious metal catalysts have been screened for catalytic decomposition of hydroxyl ammonium nitrate by the thermal analysis method. Ir/SiO2 exhibits the highest catalytic activity, on which 80% hydroxyl ammonium nitrate can be completely decomposed even at 20.7 ℃, manifesting its great potentials as an environmentally benign monopropellant. H2 chemisorption on Ir/SiO2 and Ir/Al2O3 suggests that a large particle size seems to be favorable for this reaction.
    A Propylene Polymerization Catalyst Using Poly (propylene glycol) dibenzoate as Electron Donor
    ZHANG Qiaofeng~1; YUAN Yuping~ 2; 3; ZHANG Chunyu~2; CHEN Bin~ 2; ZHANG Xuequan~ 1; 2
    2007, 28 (1):  3-4. 
    Abstract ( 2110 )   [Full Text(HTML)] () PDF (153KB) ( 2214 )  
    A novel MgCl_2-supported Ziegler-Natta catalyst using poly(propylene glycol)dibenzoate (PPGDB) as the internal electron donor for propylene polymerization was prepared. The catalyst exhibited comparable activity and stereoselectivity with that using normal phthalate as electron donor but rather broader molecular weight distribution of resulting polypropylene. Examination of the interaction between PPGDB and MgCl_2 by using infrared spectroscopy showed that both C=O and C-O-C of PPGDB could coordinate to MgCl2.
    Catalytic Performance of Supported PbO Catalysts for Synthesis of Methyl N-phenyl Carbamate from Aniline and Dimethyl Carbonate
    KANG Wukui~ 1; 2; KANG Tao~1; MA Fei~1; ZHAO Yongfeng~3; CUI Lili~3; YAO Jie~1; WANG Gongying~ 1
    2007, 28 (1):  5-9. 
    Abstract ( 2105 )   [Full Text(HTML)] () PDF (325KB) ( 1056 )  
    The catalytic performance of a series of supported PbO catalysts for synthesis of methyl N-phenyl carbamate (MPC) from aniline (An) and dimethyl carbonate (DMC) was studied. It was found that PbO/SiO_2 showed the best catalytic performance. The yield of MPC was 99.5% under the conditions of n(PbO) / n(An) =1%, n(DMC) / n(An) =5, θ=160 ℃, and t=4 h. The PbO/SiO_2 catalyst was easily separated from the product solution, and the catalyst remained higher activity after reuse 5 times, which showed that the lifespan of PbO/SiO2 was long.
    Preparation,Characterization,and Photocatalytic Performance of NdPW_(12)O_(40)/TiO_2 Composite Catalyst
    CAI Tiejun~ 1; YUE Ming~1; WANG Xianwen~2; DENG Qian~1; PENG Zhenshan~1; ZHOU Wenhui~1
    2007, 28 (1):  10-16. 
    Abstract ( 2017 )   [Full Text(HTML)] () PDF (508KB) ( 731 )  
    The NdPW12O40/TiO2 composite catalyst was prepared by the sol-gel method and characterized by thermogravimetric-differential thermal analysis, infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, fluorescence emission spectroscopy, scanning electron microscopy, and X-ray diffraction. The photocatalytic eliminations of acetone and methanol were used as model reactions to evaluate the photocatalytic activity of the composite catalyst under ultraviolet light irradiation. The results show that TiO2 modified by NdPW12O40 has small crystal size (11 to 14 nm) and large surface area, and the aggregation of TiO2 particles is effectively inhibited. When the initial concentration of acetone is 6.58 g/m3 and the space time is 2~4 s, the mineralization rate is 96.74% using 0.1 g of 1%NdPW12O40/TiO2 as the catalyst, which conforms to the requirements of emission standards for air pollutants. Methanol can be mineralized completely when its initial concentration is 882 g/m3 and the space time is 20 s. Compared with pure TiO2, the light absorption ability of NdPW12O40/TiO2 gets enhanced, and the absorption region extends to long wavelengths by 20 nm.
    Preparation of Pt/CMK-3 Anode Catalyst for Methanol Fuel Cells Using Paraformaldehyde as Reducing Agent
    WU Wei1, CAO Jieming1*, CHEN Yu2, LU Tianhong2
    2007, 28 (1):  17-21. 
    Abstract ( 1969 )   [Full Text(HTML)] () PDF (359KB) ( 946 )  
    The Pt/CMK-3 anode catalyst for direct methanol fuel cells (DMFC) was prepared by the liquid reduction method using paraformaldehyde as the reducing agent. The catalyst was characterized by X-ray diffraction and transmission electron microscopy. The results showed that CMK-3 was a highly intriguing support material for DMFC because of its high surface area, uniform mesopores, and high thermal and chemical stability. The average particle size of Pt nanoparticles in Pt/CMK-3 was 2~8 nm, which was smaller than that of the commercial Pt/XC-72 catalyst from the E-TEK Corporation and that of the Pt/C-M catalyst prepared using methanol as the reducing agent. The particle size distribution of Pt/CMK-3 was narrow, and the relative crystallinity was low. The electroactivity of Pt/CMK-3 for ethanol oxidation was studied. The Pt/CMK-3 catalyst possessed higher electrocatalytic activity than Pt/XC-72 and Pt/C-M catalysts.
    DRIFTS Study on Adsorption and Activation of CH4 and CO2 on Ni/SiO2 Catalyst with Various Ni Particle Sizes
    GUO Jianzhong1,2, HOU Zhaoyin1, GAO Jing1, ZHENG Xiaoming1*
    2007, 28 (1):  22-26. 
    Abstract ( 2505 )   [Full Text(HTML)] () PDF (419KB) ( 872 )  
    The adsorption and activation of CH4 and CO2 on Ni/SiO2 catalyst with different Ni particle sizes were investigated by diffuse reflectance infrared Fourier transform spectroscopy. CHx species (x=1-3) were observed on the catalyst with different Ni particle sizes when CH4 was adsorbed on its surface. The CH3-O species was also detected as the result of an interaction of CHx species with surface hydroxyl groups. The dissociation of CH4 depended intensively on the Ni particle size. CH4 dissociated more easily on the Ni/SiO2 catalyst with a Ni particle size of approximate 8 nm. CO2 was very difficult to dissociate on the Ni/SiO2 catalyst, while the adsorbed H from CH4 dissociation promoted the dissociation of CO2. Small Ni particles might be helpful to hydrogen overflow to the support for CO2 activation. In co-adsorption of CH4 and CO2, the monodentate carbonate species was observed on the Ni/SiO2 catalyst with smaller Ni particle size, which indicated that smaller Ni particles could promote the reaction of CO2 with surface oxygen species.
    Characterization of Na-Rh/γ-Al2O3 Catalyst and Its Catalytic Properties for Selective Oxidation of CO
    WANG Fang1,2, LU Gongxuan1*
    2007, 28 (1):  27-33. 
    Abstract ( 1757 )   [Full Text(HTML)] () PDF (540KB) ( 940 )  
    A novel active catalyst of Na-Rh/γ-Al2O3 was prepared by impregnation and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and N2 adsorption-desorption. The catalytic performance of Rh/γ-Al2O3 and Na-Rh/γ-Al2O3 catalysts for the selective oxidation of CO in the presence of excess hydrogen was compared, and the effect of pretreatment on the catalytic activity was investigated. The 5%Na-0~5%Rh/γ-Al2O3 catalyst maintains its activity for CO oxidation for more than 100 h in the presence of hydrogen and moisture. The conversion of CO and CO2 selectivity up to 100% and 70%, respectively, were obtained at 100 ℃, GHSV=2~25×104 h-1, 1~4%O2, 2%CO, and 70%H2. XPS results indicated that the electronic interaction between Na and Rh causes a transfer of electron density from Na to Rh, which increases the back-donation of electrons from the filled d orbitals of Rh to the CO 2π* antibonding molecular orbitals and results in a weakening of the C[KG-45x]=[KG-20x]O bond. Highly dispersed Rh was found on the surface of the promoted catalysts. N2 adsorption-desorption results revealed that the specific surface area decreases after the addition of Na, but the average pore size becomes larger, which provides more spaces for CO oxidation.
    Comparative Study on Hydrocracking over MCM-22 and ITQ-2 Zeolite-Supported Catalysts
    LIU Baijun1*, FENG Legang2, HOU Huijuan1, GAO Shansong1, ZHA Xianjun1
    2007, 28 (1):  34-38. 
    Abstract ( 2118 )   [Full Text(HTML)] () PDF (273KB) ( 845 )  
    A series of supported WNi catalysts for hydrocracking of vacuum gas oil (VGO) were prepared using ITQ-2 and MCM-22 zeolites as supports. The catalysts were characterized by temperature-programmed desorption of ammonia, infrared spectroscopy of pyridine adsorption, and nitrogen adsorption. The acidities of WNi/MCM-22 and WNi/ITQ-2 catalysts were similar; but the surface area and pore volume of WNi/ITQ-2 were larger than those of WNi/MCM-22. The results of VGO hydrocracking indicated that WNi/ITQ-2 catalysts had higher catalytic activity and selectivity for middle distillates. The higher activity was due to the large secondary pore structure of the ITQ-2 zeolite and its rich accessible acidic centers. The reason for the higher selectivity was that products left acid centers rapidly and secondary cracking was avoided because of the large secondary structure.
    Application of Beam Irradiation in Preparation of Visible-Light Responsive TiO2 Films
    HOU Xinggang, GU Xuenan, LIU Andong*
    2007, 28 (1):  39-44. 
    Abstract ( 1900 )   [Full Text(HTML)] () PDF (414KB) ( 840 )  
    In order to improve the utilization of visible light, implantation of transition metals (V+, Cr+) and deposition of noble metals (Ag, Pt) through electron beam irradiation were used to modify TiO2 films prepared by the sol-gel method. A red shift was found in the ultraviolet-visible spectra of the modified TiO2 films. Photocatalytic degradation of methyl orange showed that the photocatalytic activity of TiO2 films under visible light irradiation was increased dramatically by the two methods.
    Harmonious Effects of Multiple Energy Fields in Micro-arc Discharge Catalysis System during Wastewater Disposal
    YAN Zhijun~1; YAN Zhiyu~ 2; XIAO Jingkun~2
    2007, 28 (1):  45-50. 
    Abstract ( 2004 )   [Full Text(HTML)] () PDF (359KB) ( 997 )  
    The effect of micro-arc discharge of the Ti anode on the decolorization of methyl orange was studied. It was found that the decolorization of methyl orange was prominent. Under the conditions of peak-value voltage 550 V, pulse frequency 300 Hz, duty circle of positive pulse 1/180, anode area 25 mm~50 mm, and react ion time 60 min in H3PO4 electrolyte (0.3 mol/L), the decolorization of methyl orange (600 ml, 20 mg/L) was 94%. During the discharge, the ceramic layer formed on the Ti anode was anatase and the wavelength of micro-arc was between 300 and 350 nm, which were proved by XRD and spectrum analysis. It was hinted that there might be photocatalysis, electrocatalysis, wave-like sono-catalysis during micro-arc discharge. The contrastable experiments showed that the individual effect of such catalysis was inapparent. The react ion mechanism was thought that the dominating process was plasma catalysis with the harmonious effects of multiple energy fields on the Ti anode during micro-arc discharge in the degradation of organic compounds.
    Deactivation Mechanism of Cu-Based Catalyst for Methanol Synthesis in Slurry Phase
    ZHAI Xufang1,2, Jun SHAMOTO3, XIE Hongjuan1, TAN Yisheng1, HAN Yizhuo1*, Noritatsu TSUBAKI3
    2007, 28 (1):  51-56. 
    Abstract ( 2444 )   [Full Text(HTML)] () PDF (429KB) ( 968 )  
    Compared with the traditional gas phase synthesis, slurry-phase synthesis of methanol has many advantages. The bottle neck for the commercialization of slurry-phase methanol synthesis is the catalyst deactivation. In this paper, the stability and deactivation of a commercial Cu-based C301 catalyst for methanol synthesis from syngas with paraffin in a slurry phase were studied using a stirred autoclave reactor system. Synthesis reactions were conducted under the conditions of 5 MPa, 260 ℃, and 1?100 ml/(g•h), and the reactions were lasted for different times to obtain catalyst samples with different deactivation degrees. The composition and morphology of the catalyst samples before and after reaction were characterized by means of temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, scanning electron microscopy-energy dispersive spectroscopy, elemental analysis, and N2 physical adsorption. The results showed that the deactivated catalyst was not poisoned by impurities in the reaction system. The main causes for the deactivation of the Cu-based catalyst were the sintering and carbon deposition. The Cu composition in the catalyst did not change significantly during the reaction.
    Preparation of MgO-Supported Cu2O Catalyst and Its Catalytic Properties for Cyclohexanol Dehydrogenation
    SHI Qiujie*, LIU Ning, LIANG Yi
    2007, 28 (1):  57-61. 
    Abstract ( 2233 )   [Full Text(HTML)] () PDF (326KB) ( 826 )  
    In order to obtain a more effective catalyst for the dehydrogenation of cyclohexanol to cyclohexanone, the MgO-supported Cu2O catalyst was prepared by chemical reduction combined with impregnation using MgO as the support and hydrazine hydrate as the reducing agent. The effects of preparation conditions on the catalytic properties of the catalyst were studied, and the catalyst was characterized by N2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and temperature-programmed reduction. Cu2O is reduced to Cu0 when the amount of N2H4•H2O used is high. With increasing amount of NaOH used, the catalyst particles congregate and the specific surface area of catalyst decreases. The catalyst activity for dehydrogenation of cyclohexanol reaches the maximum at a Cu2+∶N2H4•H2O∶NaOH molar ratio of 1∶1∶2. The catalyst reduced by N2H4•H2O is composed of Cu+ only, whereas the traditional Cu/MgO catalyst contains Cu0 and little Cu+. Because Cu+ is more active than Cu0, the activity of the Cu2O/MgO catalyst is much higher than that of the traditional Cu/MgO catalyst.
    Preparation of γ-Fe2O3 Support and Evaluation of Catalytic Activty of Ru-K/Fe2O3 Catalyst for Ammonia Synthesis
    NI Jun1, WANG Rong1, ZHENG Ying2, LIN Jianxin1, WEI Kemei1*
    2007, 28 (1):  62-66. 
    Abstract ( 2026 )   [Full Text(HTML)] () PDF (346KB) ( 867 )  
    A novel nanometer iron oxide support was successfully synthesized by the sol-gel method. The results of X-ray diffraction, differential thermal analysis, thermogravimetric analysis, scanning electron microscopy, and N2 physical adsorption show that the prepared Fe2O3 particles have a typical mesoporous structure with pore diameters of 18~8[KG-45x]-[KG-20x]25~0 nm. The effect of the crystal phase composition of Fe2O3 on catalytic activity of the Ru-K/γ-Fe2O3 catalyst was further investigated under the conditions of 475 ℃, 10 MPa, 10?000 h-1, and V(H2)/V(N2)=3. The higher the content of γ-Fe2O3 in the support, the better the catalytic activity of the catalyst.
    Different Reaction Characteristics of Hydride Transfer and Hydrogen Transfer in Catalytic Cracking
    GONG Jianhong*, LONG Jun, XU Youhao
    2007, 28 (1):  67-72. 
    Abstract ( 2052 )   [Full Text(HTML)] () PDF (319KB) ( 1287 )  
    Based on the Daqing vacuum gas oil’s reaction on an acid Y zeolite catalyst, hydride transfer and hydrogen transfer were distinguished as two different reaction stages during the catalytic cracking. Hydride transfer takes place at conversion intervals between 5%~10% and 60%~70%, while hydrogen transfer occurs at conversions above 60%~70%. Coke, independent of hydride transfer, is mainly produced by hydrogen transfer. The hydrogen transfer reaction on the Y zeolite catalyst mainly takes place between gasoline olefins and naphthenes.
    Complex Reactions of Hydration and Etherification of Isobutene over La-Modified β Molecular Sieve
    YANG Bolun*, LU Shiqing, WU Jiang, WANG Huajun
    2007, 28 (1):  73-79. 
    Abstract ( 2125 )   [Full Text(HTML)] () PDF (440KB) ( 829 )  
    The La/β molecular sieve catalyst was prepared by the ion-exchange method using microwave heating and conventional heating. The catalyst was characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy. Hydration and etherification reactions of isobutylene with an ethanol-water mixture to produce a fuel mixture were carried out over these catalysts. The effects of the preparation method and La loading on the catalytic performance of La/β catalysts were studied, and the reaction mechanism was proposed. The results indicated that the ion-exchange degree and La loading of the La/β catalyst prepared by the microwave heating method were higher than the one prepared by the conventional heating method, and the ion-exchange time was shorter. The conversion of water and ethanol over the modified La/β molecular sieve catalyst was increased by 10%~20% compared with the unmodified Hβ molecular sieve, and the catalyst activity increased with the La loading. The hydration and the etherification mainly occurred on the external surface of the β molecular sieve catalyst. Bridging Al[KG-45x]-[KG-20x]OH[KG-45x]-[KG-20x]Si acid sites, i.e., Bronsted acid sites, were the main active sites, and the carbonium ion was formed during the reaction.
    Ethanol Oxidation over Carbonized TiO2 Nanotube-Supported Pd Electrocatalyst
    HU Fengping, SHEN Peikang*
    2007, 28 (1):  80-84. 
    Abstract ( 2084 )   [Full Text(HTML)] () PDF (290KB) ( 1072 )  
    TiO2 nanotubes were carbonized by decomposition of poly(ethylene glycol) to achieve good electrical conductivity and subsequently used as the support for the preparation of the Pd/TiO2C electrocatalyst. The oxidation of alcohols in alkaline media over the Pd/TiO2C catalyst was investigated. The results show that the dispersion of the metal electrocatalyst and the structure of the electrode can be improved using carbonized TiO2 nanotubes as the support, and hence the catalyst activity is increased. The Pd/TiO2C electrocatalyst with a Pd/TiO2C mass ratio of 1/1 gives the best catalytic performance for alcohol oxidation. The catalytic activity of the Pd/TiO2C electrocatalyst with a Pd loading of 0~3 mg/cm2 is 2~8 times higher than that of the Pd/C electrocatalyst with the same loading in alkaline media.
    Preparation of Chiral Salen-Mn(Ⅲ) Complex Supported on MCM-41 and Its Catalytic Properties for Enantioselective Epoxidation
    ZHAO Jiquan*, ZHANG Yaran, ZHANG Yuecheng
    2007, 28 (1):  85-90. 
    Abstract ( 1928 )   [Full Text(HTML)] () PDF (398KB) ( 895 )  
    MCM-41 was functionalized with 3-aminopropyl groups by the reaction of hydroxyl groups on the MCM-41 surface with 3-aminopropyltriethoxysilane being refluxed in toluene. By employing the reaction of amino groups with active ester groups on the chiral Salen-Mn(Ⅲ) complex, the homogeneous chiral Salen-Mn(Ⅲ) complex was heterogenized. The supported catalyst was characterized by FT-IR, DR UV-Vis, XRD, ICP, and N2 adsorption. The results indicated that the complex was supported on MCM-41 and the native structure of MCM-41 was maintained. The supported catalyst was applied to the enantioselective epoxidation of 1,2-dihydronaphthalene using NaClO and m-chloroperbenzoic acid as oxidants. The results confirmed that the activity of the supported catalyst was lower than that of the homogeneous chiral Salen-Mn(Ⅲ). However, its enantioselectivity was higher than that of the homogeneous one. A yield of 45~9% and ee of 84~3% of epoxide were obtained when 1,2-dihydronaphthalene was oxidized by NaClO for 12 h at 20 ℃ in the presence of the pyridine nitrogen oxide. About 34% of manganese leaching was observed after the supported catalyst was run 5 times.
    Structure and Catalytic Performance of H3PW12O40/SiO2 Prepared by Several Methods
    ZHAO Xinqiang*, HAN Yantao, SUN Xiaolei, WANG Yanji
    2007, 28 (1):  91-96. 
    Abstract ( 1869 )   [Full Text(HTML)] () PDF (335KB) ( 794 )  
    Silica-supported H3PW12O40 catalysts were prepared by the impregnation method, sol-gel technique, and sol-gel technique using ionic liquids as the template, respectively, to solve the problems of H3PW12O40 such as low surface area, difficult separation, and reuse. The catalysts were characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption, and NH3 temperature-programmed desorption. Their catalytic performance for the nitration of benzene was evaluated. The results revealed that H3PW12O40 in all the catalyst samples kept its Keggin structure. The specific surface area of the H3PW12O40/SiO2 catalyst prepared by the impregnation method was 475~2 m2/g, and the nitration of benzene over it decreased from 82~4% to 70~7% after 4 runs. The specific surface area of the H3PW12O40/SiO2 catalyst prepared by the sol-gel technique was 498~6 m2/g, and the nitration of benzene over it decreased from 85~1% to 79~6% after 4 runs. The H3PW12O40/SiO2 catalyst prepared by the sol-gel technique using [emim]BF4 as the template possessed mesoporous structure and a specific surface area of 558~5 m2/g, and the nitration of benzene over this catalyst decreased from 84~7% to 79~9% after 4 runs. The three H3PW12O40/SiO2 catalyst samples showed higher stability and activity in the nitration of benzene.