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Chinese Journal of Catalysis
2006, Vol. 27, No. 4
Online: 25 April 2006

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A Highly Photoactive Nanocrystalline TiO2 Aerogel Prepared by a Non-Alkoxide Sol-Gel Method CHEN Lin, ZHU Jian, YANG Jun, LIU Yongmei, CAO Yong, HE Heyong, DAI Weilin, FAN Kangnian 2006, 27 (4):  291-293.  Abstract ( 1741 )   [Full Text(HTML)] () PDF (266KB) ( 675 )   The nanocrystalline TiO2 aerogel was prepared by a novel epoxide-mediated non-alkoxide sol-gel method, and the catalyst was characterized by X-ray diffraction, N2 adsorption and transmission electron microscopy. The influence of the preparation conditions on the textural properties of the TiO2 aerogels was investigated, and the catalyst activity was tested by using phenol degradation as the model reaction. When H2O/TiCl4 molar ratio is 3, the prepared TiO2 aerogel has the smallest crystallite size and the biggest surface area, and the catalyst shows the highest activity for phenol degradation.

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Transesterification of Cottonseed Oil to Biodiesel Catalyzed by Highly Active Ionic Liquids WU Qin1,2, CHEN He1, HAN Minghan1*, WANG Jinfu1, WANG Dezheng1, JIN Yong1 2006, 27 (4):  294-296.  Abstract ( 2226 )   [Full Text(HTML)] () PDF (171KB) ( 1345 )   The transesterification of cottonseed oil to biodiesel catalyzed by ionic liquids was studied. Several water-stable Bronsted-acidic ionic liquids with an alkane sulfonic acid group were synthesized. These ionic liquids show good catalytic activity for the transesterification of cottonseed oil. The catalytic activity of each ionic liquid is dependent on its cation. The ionic liquid 1-(4-sulfonic acid)butylpyridinium hydrogen sulfate shows the best catalytic activity, which is nearly the same as the catalytic activity of concentrated sulfuric acid. The produced biodiesel can be separated via simple decantation, and the ionic liquids can be reused after distillation.

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A Method for Producing Terephthalic Acid by Comamonas testosterone DSM6577 WANG Jing1,2, TIAN Jing1,2, XU Jianhe3 2006, 27 (4):  297-298.  Abstract ( 2097 )   [Full Text(HTML)] () PDF (148KB) ( 785 )   p-Toluic acid was used as a sole source of carbon and energy to screen for a bacterium to produce terephthalic acid. Comamonas testosterone strain DSM6577 can oxidize p-toluic acid to terephthalic acid through sequential reactions catalyzed by a series of enzymes. The growth of the strain, degradation of p-toluic acid, and production of terephthalic acid were studied. p-Toluic acid can be completely transformed within 8 h, but the formation of terephthalic acid takes place during 14 to 31 h, and a maximal yield of 34 mg/L is obtained at 21 h.

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Catalytic Activity of Hβ Zeolite for Cyclohexyl Hydroperoxide Decomposition SUN Zhiqiang, XU Jie*, DU Zhongtian, ZHANG Wei 2006, 27 (4):  299-300.  Abstract ( 1974 )   [Full Text(HTML)] () PDF (123KB) ( 779 )   The transition metal free acidic zeolite Hβ has been found to be very active for the decomposition of cyclohexyl hydroperoxide. A remarkable high TOF of 181.9 h-1 was achieved with Hβ, which is almost equal to the TOF over 5%Ru/Al2O3. The total selectivity for the main products cyclohexanol and cyclohexanone reached 84.6%. The reaction temperature greatly affected the decomposition rate and product selectivity.

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Preparation and Catalytic Activity of Monolayer Dispersed Pt/Ni Bimetallic Catalyst for C=C and C=O Hydrogenation WANG Songrui1, LIN Wei1, ZHU Yuexiang1*, XIE Youchang1, Jingguang G. CHEN2 2006, 27 (4):  301-303.  Abstract ( 2052 )   [Full Text(HTML)] () PDF (192KB) ( 956 )   The monolayer dispersed Pt/Ni bimetallic catalyst was prepared through a simple replacement reaction, and its catalytic activity for the hydrogenation of cyclohexene, styrene, acetone, and butyl aldehyde was tested. The Pt/Ni catalyst prepared by the replacement reaction showed much higher activity than Pt/Ni and Pt/Al2O3 catalysts with the same Pt loading prepared by the conventional impregnation method.

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Preparation of Supported Pd/Al2O3 Catalysts by Ultrasonic Impregnation and Their Catalytic Performance for Anthraquinone Hydrogenation YANG Yonghui, LIN Yanjun, FENG Junting, David G. EVANS, LI Dianqing* 2006, 27 (4):  304-308.  Abstract ( 2223 )   [Full Text(HTML)] () PDF (356KB) ( 1013 )   Palladium catalysts supported on spherical γ-Al2O3 and θ-Al2O3 with palladium loading of 0.3% were prepared with and without ultrasonic treatment during the impregnation step. Structural and physical properties of the catalysts were characterized by X-ray diffraction, N2 adsorption, and transmission electron microscopy. The effects of ultrasonic treatment on the Pd distribution and anthraquinone hydrogenation activity of the catalysts were investigated. The results show that the activity of the supported catalysts prepared with ultrasonic treatment for anthraquinone hydrogenation is higher than those without ultrasonic treatment. Compared with the Pd/γ-Al2O3 catalyst, the supported catalyst Pd/θ-Al2O3 prepared under the same condition of ultrasonic treatment during the impregnation step has higher catalytic activity and stability in anthraquinone hydrogenation.

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Alkylation Performance of Thiophene and Its Derivatives during Olefinic Alkylation of Thiophenic Sulfur in Gasoline ZHANG Zekai1,2, JIANG Hui3, LIU Shenglin1, WANG Qingxia1, XU Longya1* 2006, 27 (4):  309-313.  Abstract ( 1953 )   [Full Text(HTML)] () PDF (319KB) ( 1075 )   The alkylation performance of thiophene and its derivatives (such as 2-methylthiophene, 3-methylthiophene, and 2,5-dimethylthiophene) with 1-hexene was investigated in a fixed-bed reactor. The results showed that thiophene and its derivatives could be mono-alkylated with 1-hexene easily, and their conversion was close to 100% under experimental conditions. However, with the increase of the number of the branched chain on the thiophene ring, the di- and tri-alkylation capability of thiophene derivatives decreased a lot because of the thermodynamics and steric effects, and their primary products are restricted to the mono-alkylated products. The decrease in alkylation capability of thiophene derivatives enhanced the other two parallel competitive reactions, the aromatics alkylation and hexene alkylation (or called hexene oligomerization). The relative content of their further alkylated products was even more than that of the mono-alkylated products during the alkylation of dimethylthiophene.

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Asymmetric Reduction of Ethyl 4-Chloro-3-Oxobutanoate to Ethyl 4-Chloro-3-Hydroxybutanoate Directly Catalyzed by Yeast Fermentation Broth MA Xiaokui1*, WANG Zhezhi1, CHEN Wuling2 2006, 27 (4):  314-318.  Abstract ( 2186 )   [Full Text(HTML)] () PDF (293KB) ( 1066 )   The asymmetric reduction of ethyl 4-chloro-3-oxobutanoate (COBE) to optically active ethyl 4-chloro-3-hydroxybutanoate (CHBE) directly catalyzed by yeast fermentation broth and the influence of chiral additives and reaction conditions on this reaction were studied. The concentrations of COBE and (S)-CHBE, and the optical purity of the product were determined by gas chromatography and high-performance liquid chromatography with a Chiralcel OB column, respectively. In the yeast fermentation broth without any chiral additive, the substrate was decomposed and the pH value of the reaction mixture decreased sharply. When β-cyclodextrin was used as the chiral additive, the yield and enantiomeric excess of (S)-CHBE reached as high as 76% and 92%, respectively. Under specified conditions, high β-cyclodextrin concentration favored (S)-CHBE formation. The optimum reaction conditions are 29～31 ℃, pH 7.2, and yeast cultivation time of 16～18 h.

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H2-TPR Study on Mo/HZSM-5 Catalyst for CH4 Dehydroaromatization LIU Hongmei2, XU Yide1* 2006, 27 (4):  319-323.  Abstract ( 2314 )   [Full Text(HTML)] () PDF (299KB) ( 838 )   Temperatured-programmed reduction (TPR) of hydrogen was used to investigate the reducibility of Mo species on Mo/HZSM-5 catalysts prepared by different methods, and the possible six H2-consumption peaks were assigned precisely with the help of 1H MAS NMR. The TPR peaks corresponding to the reduction of Mo species associated with Bronsted acid sites were first identified. In addition, the catalytic performance of various Mo-based catalysts was studied for methane dehydroaromatization. The Mo species that is located in the channels of HZSM-5 zeolite and associated with Bronsted acid site is more active and stable for the formation of one-ring aromatics in the methane dehydroaromatization.

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In Situ X-Ray Diffraction Study of VOx and MoOx Dispersion on Al2O3 HUANG Xiumin, TANG Xingfu, XU Yide, SHEN Wenjie* 2006, 27 (4):  324-328.  Abstract ( 1998 )   [Full Text(HTML)] () PDF (499KB) ( 811 )   The dispersion of VOx and MoOx on Al2O3 was investigated by means of in situ X-ray diffraction. For the VOx/Al2O3 catalyst prepared by the impregnation method, the precursor of (NH4)2［VO(C2O4)2］ dispersed uniformly on the support. (NH4)2［VO(C2O4)2］ began to decompose at 200 ℃, the decomposition finished at 400 ℃, and the obtained VOx species dispersed through the HxV2O5 phase. For the VOx/Al2O3 catalyst prepared by mechanical grinding, although there was an interaction between V2O5 and Al2O3, no obvious spontaneous dispersion phenomenon was observed; thus the dispersion of VOx was rather poor as compared with the impregnated catalyst. For the MoOx/Al2O3 catalysts prepared by impregnation and mechanical grinding, the MoO3 phase resulted from (NH4)6Mo2O24•4H2O decomposition was not completely the same, and the contents of (040) and (060) crystal planes were different.

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Surface Properties of CeO2-TiO2 Catalyst and Its Catalytic Activity in Wet Air Oxidation YANG Shaoxia*, ZHU Wanpeng, CHEN Zhengxiong, WANG Jianbing, ZHOU Yunrui 2006, 27 (4):  329-334.  Abstract ( 2050 )   [Full Text(HTML)] () PDF (412KB) ( 757 )   CeO2-TiO2 catalysts were prepared by sol-gel and coprecipitation methods. The physical properties including surface area, metal crystal phases, surface components, and pHPZC of the catalysts were characterized by N2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Zeta potentiometric analysis. The catalytic activity for wet air oxidation (WAO) of high concentration acetic acid and phenol was investigated. Moreover, the relationship between the surface structure and the catalytic activity was studied. The results showed that for the CeO2-TiO2 catalysts, the increase in the specific surface area and the decrease in the particle size are due to the interaction of Ce and Ti. A higher content of the chemisorbed oxygen was present on the surface of the CeO2-TiO2 catalysts. The pHPZC of the CeO2-TiO2-2 catalyst (pHPZC=4.6) prepared by coprecipitation was higher than that of the CeO2-TiO2-1 catalyst (pHPZC=3.2) prepared by the sol-gel method. The adsorption of acetic acid and phenol on the surface of CeO2-TiO2-2 is more effective. In WAO of acetic acid and phenol, the CeO2-TiO2 catalysts were very active. The activity of CeO2-TiO2-2 was the highest. By using the CeO2-TiO2-2 catalyst, about 79% COD removal was obtained in WAO of acetic acid at 230 ℃ and 5 MPa after 120 min reaction, while about 96% COD removal was achieved in WAO of phenol at 150 ℃ and 4 MPa after 120 min reaction.

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Application of Ligand-Free Pd/LDH-F Catalyst in Heck and Suzuki Coupling Reactions ZHOU Hao1, ZHUO Guanglan2, JIANG Xuanzhen1*, ZHANG Bo3, GE Zhonghua 3 2006, 27 (4):  335-338.  Abstract ( 2424 )   [Full Text(HTML)] () PDF (232KB) ( 786 )   The palladium catalyst supported on fluoride pillared layered double hydroxide (LDH-F) was prepared by the incipient wetness method, and it was used to catalyze the Heck and Suzuki coupling reactions of aryl bromides. The structure of the Pd/LDH-F catalyst and the leaching of Pd in the solution were characterized by X-ray diffraction and inductively coupled plasma. With a small palladium dosage (Pd/aryl bromide molar ratio of 0.001) and no ligand, Pd/LDH-F exhibits higher catalytic activity and selectivity than the catalysts supported on other carriers for the Heck reaction of aryl bromides with styrene. The Pd/LDH-F catalyst can be easily separated from the reaction mixture and reused four times without loss in activity. Under the conditions of Pd/aryl bromide molar ratio of 0.005, room temperature and 3 h, the Pd/LDH-F catalyst can catalyze the Suzuki reaction of bromobenzene with a product yield of 99%.

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Ullmann Reaction of Iodobenzene over Pd/NH2C3H6-MCM-41 in Aqueous Medium CHEN Jia, WAN Ying, LI Hexing* 2006, 27 (4):  339-343.  Abstract ( 1814 )   [Full Text(HTML)] () PDF (379KB) ( 711 )   NH2C3H6-modified MCM-41 was synthesized by co-condensation of tetraethylorthosilicate (TEOS) and organosilane aminopropyltrimethoxysilane (APTES) at room temperature, and it was then used as the support to prepare the Pd/NH2C3H6-MCM-41 catalyst. The characterization by X-ray diffraction, NMR, FT-IR, transmission electron microscopy, X-ray photoelectron spectroscopy, and N2 adsorption revealed that both NH2C3H6-MCM-41 and Pd/NH2C3H6-MCM-41 remained mesoporous structure similar to that of MCM-41, but their degree of structrural order decreased with the increase in the amounts of the NH2C3H6[KG-47x]-[KG-15x][KG*2] group and Pd. During the Ullmann reaction of PhI performed in an aqueous medium, Pd/NH2C3H6-MCM-41 exhibited higher activity and higher selectivity for biphenyl than Pd/SiO2 and Pd/MCM-41. This may be due to the high and homogeneous dispersion of Pd particles, electron enrichment of metallic Pd, well-ordered mesoporous structure, suitable base strength, and hydrophobicity. The yield of biphenyl could reach 63%, showing good potential of the catalyst in industrial application.

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Preparation of Lanthanide Ions-Doped TiO2 and Its Photocatalytic Activity for Imidazole Degradation CHEN Enwei, YIN Donghong*, SONG Huijuan, GONG Liming, YU Ningya* 2006, 27 (4):  344-348.  Abstract ( 1889 )   [Full Text(HTML)] () PDF (400KB) ( 944 )   The lanthanide ions-doped TiO2 samples with different content were prepared by the sol-gel method using titanium tetrachloride and lanthanide chloride as the raw materials. The samples were characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PLS), surface photovoltage spectroscopy (SPS), and X-ray photoelectron spectroscopy (XPS). The XRD result indicated that the lanthanide ions did not enter the crystal lattices of TiO2. The intensity of PLS and SPS related to the surface oxygen vacancies and defects as well as the separation and recombination of photoinduced charge carriers changed with the kinds of lanthanide ions and the dopant content. The photocatalytic activity of the samples for the degradation of aqueous imidazole was tested under UV light. The result showed that the appropriate content of lanthanide dopants could effectively promote the separation effect of surface photoinduced charge carriers on TiO2, which was responsible for the remarkable increase in photocatalytic activity.

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Polymerization of Styrene Catalyzed by Bis-(β-ketonaphthylamino) Nickel(Ⅱ)/MAO Catalyst System LIU Yongming1, HE Xiaohui1, CHEN Yiwang1*, WU Qing2 2006, 27 (4):  349-354.  Abstract ( 2045 )   [Full Text(HTML)] () PDF (363KB) ( 975 )   Polymerization of styrene was catalyzed by a new late transition metal complex catalyst system based on bis-(β-ketonaphthylamino) nickel(Ⅱ)/MAO (methylaluminoxane). The influence of polymerization conditions such as polymerization temperature, Al/Ni molar ratio, monomer concentration, and polymerization time was investigated. The obtained polymer was characterized by gel permeation chromatography, proton and 13C nuclear magnetic resonance, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and wide-angle X-ray diffraction. The results indicated that the catalyst system exhibited high catalytic activity. The structure analysis result of the polymer demonstrated that the above catalyst system initiated styrene to yield atactic polystyrene with moderate molecular weight and narrow molecular weight distribution (Mw/Mn＜1.6).

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Copolymerization of Cyclohexene Oxide with Carbon Dioxide Catalyzed by Zn-Co Double Metal Cyanide Complex CHEN Shang1,2*, ZHANG Xinghong2, QI Guorong2 2006, 27 (4):  355-360.  Abstract ( 2112 )   [Full Text(HTML)] () PDF (329KB) ( 725 )   Double metal cyanide complexes based on Zn3［Co(CN)6］2 were prepared and used for copolymerization of cyclohexene oxide with carbon dioxide. The catalytic characteristics and the effect of preparation conditions on catalytic performance and product composition were investigated. The results showed that these catalysts could catalyze copolymerization effectively. The catalytic efficiency could reach over 6?000 g/g when the catalyst content was 1.8×10-4, and the products were confirmed to be nearly alternative copolymers by FT-IR and1H NMR. The effects of complexing agents and zinc halides (ZnX2, X=F, Cl, Br, I) on catalytic performance were studied. The catalytic efficiency was influenced by the kind of complexing agents and zinc halides employed in preparation of catalysts. However, the composition of copolymers was only influenced by the kind of zinc halides. Among those complexing agents and zinc halides investigated, tert-butanol and zinc chloride were preferable, respectively. The kinetic study indicated that the initial reaction rate of copolymerization exhibited first order dependence on the catalyst content, and average activation energy of copolymerization was 41.6 kJ/mol.

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Biocatalytic Synthesis of α-Arbutin by Xanthomonas BT-112 LIU Chunqiao, ZHANG Shurong, ZHANG Peng* 2006, 27 (4):  361-364.  Abstract ( 2250 )   [Full Text(HTML)] () PDF (253KB) ( 1006 )   α-Arbutin has been recently found to be a useful cosmetic ingredient since it has a stronger inhibitory effect on tyrosinase than β-arbutin that is widely used in cosmetics. However, α-arbutin is not a natural product and difficult to be chemically synthesized. In this paper, a bacterium of Xanthomonas BT-112 was isolated and used for the anomer-selective synthesis of α-arbutin from hydroquinone and sucrose. The effects of reaction temperature, shaking speed, hydroquinone concentration, and reactant composition were investigated. When the suspension of Xanthomonas BT-112 was incubated at 35 ℃ with 48 mmol/L hydroquinone and 96 mmol/L sucrose, only one form of hydroquinone glucoside, α-arbutin, was obtained as a product. Under these conditions, the conversion based on the amount of hydroquinone supplied reached 94.3%. The product was identified by 13C NMR and1H NMR.

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Reaction Mechanism of Liquid-Phase Oxidation of Cyclohexane Catalyzed by Bi-Modified Vanadium-Phosphorous Oxide Catalyst HE Dugui1, JI Hongbing2*, LUO Sirui2, YUAN Qiulan2 2006, 27 (4):  365-368.  Abstract ( 1953 )   [Full Text(HTML)] () PDF (189KB) ( 835 )   Bi-modified vanadium-phosphorous oxide (Bi-VPO) catalysts were prepared and used in liquid-phase oxidation of cyclohexane. The results showed that Bi modification could greatly enhance the catalytic performance of Bi-VPO for the oxidation of cyclohexane under mild conditions. The experiments without any solvent and with tetrahydrofuran as a solvent indicated the existence of interaction between acetonitrile and hydrogen peroxide. The free radical trap experiment proved that a free radical process is present in the catalytic system. The oxidation experiment of cyclohexanol explained that cyclohexanone is derived directly from cyclohexane oxidation instead of cyclohexanol oxidation.