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Chinese Journal of Catalysis
2009, Vol. 30, No. 12
Online: 25 December 2009

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Solvent Effect on Selective Dehydroxylation of Glycerol to 1,3-Propanediol over a Pt/WO3/ZrO2 Catalyst GONG Lei-Feng, Lü Yuan , DING Yun-Jie, LIN Rong-He, LI Jing-Wei, DONG Wen-Da, WANG Tao, CHEN Wei-Miao 2009, 30 (12):  1189-1191.  Abstract ( 2415 )   [Full Text(HTML)] () PDF (322KB) ( 1301 )   Different solvents were studied for dehydroxylation of glycerol to1,3-propanediol over a Pt/WO3/ZrO2 catalyst. Protic solvents such as ethanol and water favored the formation of 1,3-propanediol from glycerol. Binary solvents containing a protic component showed a synergetic solvent effect on the selective dehydroxylation of glycerol to 1,3-propanediol. The protic component in the binary solvent influenced the performance of the Pt/WO3/ZrO2 catalyst.

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Synergistic Effect of TPPTS and TPPDS on the Regioselectivity for 1-Decene Hydroaminomethylation in a Two-Phase Catalytic System MAO Hui;FU Haiyan*;CHEN Hua*;LI Ruixiang;LI Xianjun 2009, 30 (12):  1192-1196.  Abstract ( 2510 )   [Full Text(HTML)] () PDF (466KB) ( 943 )   The hydroaminomethylation of 1-decene in the RhCl(CO)(TPPTS)2-TPPTS[P(m-C6H4SO3Na)3]/TPPDS[C6H5P(m-C6H4SO3Na)2]- CTAB aqueous/organic biphasic system was studied under different conditions of molar ratios of TPPTS to TPPDS, reaction pressures, and concentrations and structures of cationic surfactants. The synergistic effect of TPPTS and TPPDS on the regioselectivity was observed. The results showed that the ratio of linear/branched amine rose from 8.2 (without TPPDS) to 21.0 ([TPPTS]/[TPPDS] = 4:1). The structure of cationic surfactants exhibited an important influence on the regioselectivity. The ratio of linear/branched amine decreased when using dou-ble-chain cationic surfactants instead of single-chain cationic surfactants. The cationic surfactant that could form compact aggregate favored the formation of linear amine.

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Preparation of Mesoporous Mordenite and Its Catalytic Performance for Transformation of Heavy Aromatics QI Xiaolan;CHEN Xuemei;KONG Dejin*;ZHENG Junlin;YUAN Xiaohong;YANG Deqin 2009, 30 (12):  1197-1202.  Abstract ( 2344 )   [Full Text(HTML)] () PDF (9682KB) ( 1181 )   Mesoporous mordenite samples were prepared by treatment in NaOH solution with different concentrations. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption-desorption methods. The NaOH concentration had a great impact on physicochemical properties of the mesoporous mordenite. With the increase in NaOH concentration, the particle size of the mesoporous mordenite became smaller, the amount of derived mesopores increased, the pore size distribution became broader, and the volume of mesopores increased in a linear manner. When the NaOH concentration was 0.50 mol/L, the mesoporous mordenite became zeolite microbox-like architecture and its fragments. The mordenite after alkaline treatment had much better catalytic performance for transformation of C9 and C10 aromatics to benzene, toluene, and xylene.

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Preparation of a Biomass Carbon-Based Solid Acid Catalyst WU Rina;WANG Tonghua;*;XIU Zhilong;GUO Feng;PAN Yanqiu;YIN Jianzhong 2009, 30 (12):  1203-1208.  Abstract ( 2737 )   [Full Text(HTML)] () PDF (1786KB) ( 1702 )   A carbon-based solid acid catalyst was prepared by a carbonization-sulphonation method from natural biomass wooden powder. The esterification of oleic acid and methanol was taken as the model reaction to investigate the impact of  preparation parameters on the catalyst activity. X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, high-resolution transmission electron microscopy, and elemental analysis were used to characterize the catalyst. The results showed that the carbon-based solid acid catalyst prepared under the optimal conditions of carbonization at 400 oC for 0.5 h and then sulphonation at 135 oC for 1 h exhibited higher catalytic activity. The conversion of oleic acid reached 96% after reaction for 2 h in an equipment of continuous esterification with a rectifying column for removing water from the system. The biomass carbon-based solid acid catalyst had turbostratic carbon structure, and the sulfuric acid group (–SO3H) content reached 13.25%. The catalyst showed considerable heat stability below 220 oC.

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Density Functional Study of O2 and CO Adsorption on Co2B2/TiO2 and Co2B2Pt/TiO2 Surfaces ZENG Qingsong;CHEN Wenkai;*;DAI Wenxin;LI Yi;DING Kaining 2009, 30 (12):  1209-1214.  Abstract ( 2199 )   [Full Text(HTML)] () PDF (19218KB) ( 700 )   The possible models of Co2B2 and Co2B2Pt alloy clusters supported on TiO2 surface were studied by the density functional theory. The geometrical optimized results indicated that Co2B2 and Co2B2Pt alloy clusters preferred to be bound on the top of the two O atoms of TiO2 with two Co atoms. By analyzing the partial density of states for Co2B2 and Co2B2Pt alloy clusters, it was shown that the bonding interaction between partial Co and B is enhanced in the Co2B2 system. For the Co2B2Pt system, the bonding interaction between Pt and B is also enhanced. In these systems, new molecular orbitals have formed after Co2B2Pt alloy clusters were supported on TiO2 surface. Comparing the results of CO and O2 adsorption on PtCo2B2 /TiO2 and Co2B2/TiO2 surfaces, it was concluded that the promotion of CO and O2 adsorption on the Co2B2 is due to the Pt atoms onto the cluster.

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Functionalized Poly(ethylene glycol)-Stabilized Palladium Nanoparticles for Se-lective Oxidation of Alcohols in Supercritical Carbon Dioxide WANG Xiangrui;FENG Bo;YANG Hanmin;HOU Zhenshan;*;ZHAO Xiuge;HU Yu;QIAO Yunxiang;LI Huan;PAN Zhenyan 2009, 30 (12):  1215-1221.  Abstract ( 2154 )   [Full Text(HTML)] () PDF (5615KB) ( 1097 )   The aerobic oxidation of various alcohols to the corresponding aldehydes or ketones was carried out using stabilized palladium nanoparticles in a supercritical carbon dioxide (scCO2)/poly(ethylene glycol) (PEG-2000) biphasic system. The effects of reaction conditions on catalytic activity were investigated in detail. Among the Pd nano-catalysts reduced with different reductants, Pd nanoparticles obtained by H2 reduction showed the best catalytic performance in the oxidation of benzyl alcohol. The products can be easily extracted with scCO2 in situ from the Pd nano-catalyst immobilized in functionalized poly(ethylene glycol), and therefore the loss of palladium could be eliminated. The conversion reached 98% after the catalyst was reused 5 times.

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Oxidative Desulfurization Catalyzed by Molybdophosphate-Based Ionic Liquid AN Ying;LU Liang;LI Caimeng;CHENG Shifu;GAO Guohua* 2009, 30 (12):  1222-1226.  Abstract ( 2742 )   [Full Text(HTML)] () PDF (421KB) ( 1523 )   Oxidative desulfurization of dibenzothiophene and other sulfides in ionic liquid for model oil was investigated over molybdophosphate-based ionic liquid [hmim]3PMo12O40. Under the mild conditions, high desulfurization was obtained for dibenzothiophene (90%) and dialkyl sulfides (100%). The effects of catalyst, reaction temperature, and amount of H2O2 were investigated. The ionic liquid can be recycled 4 times without a significant decrease in activity.

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Control of Thickness and Composition of Pd/Ag Membrane during Layer-by-Layer Electroless Plating ZENG Gaofeng;SHI Lei;XU Hengyong;* 2009, 30 (12):  1227-1232.  Abstract ( 2010 )   [Full Text(HTML)] () PDF (1373KB) ( 1136 )   The deposition rules of Pd were investigated during electroless plating in baths with different amounts of Pd2+. It was demonstrated that the Pd deposition rate was controlled by the auto-catalytic activity of the metal layer surface when the deposited Pd layer became thicker than 5 μm even if Pd2+ in the plating baths was far from being consumed. When the Pd2+ amount in the bath was kept lower than that necessary for reaching the Pd layer thickness (e.g. corresponding to 1–4 μm Pd), the Pd2+ conversion in the bath was higher than 90% after reaction for 180 min. Furthermore, the same was found during Ag deposition from silver plating baths with a low amount of Ag+, i.e. Ag+ conversion was higher than 95% after plating for 120 min in baths containing Ag+ sufficient for thick Ag layer of 0.5–2 μm. It was proved by scanning electron microscopy measurements that the higher conversions of Ag+ were related to the special growth properties of Ag particles. According to the deposition rules of Pd and Ag, the thickness and metal composition of ultra-thin Pd/Ag membranes prepared by layer-by-layer electroless plating could be pre-designed as well as accurately controlled by preparing relevant plating bath with low amounts of metal.

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Effect of Mayenite Washcoat on Activity and Thermal Stability of Honeycomb Monolithic La0.8Sr0.2MnO3 Catalyst CHEN Yinfei;WANG Zhanlong;ZHANG Zekai* 2009, 30 (12):  1233-1237.  Abstract ( 2539 )   [Full Text(HTML)] () PDF (2260KB) ( 814 )   12SrO·7Al2O3 was synthesized by solid reaction and was used as the washcoat to a La0.8Sr0.2MnO3-cordierite monolith catalyst. The monolith catalyst was treated at different temperatures (850–1050 oC) and was characterized by N2 adsorption-desorption, X-ray diffraction, and scanning electron microscopy. The catalytic activity of the monolith catalyst was evaluated using methyl methacrylate combustion. The results showed that the 12SrO·7Al2O3 washcoat improved the thermal stability of the monolith catalyst obviously. After calcination at 850 oC for 6 h, the monolith catalyst with the 12SrO·7Al2O3 washcoat could fully convert methyl methacrylate at about 260 oC. The 12SrO·7Al2O3 prevented the interaction between La0.8Sr0.2MnO3 and cordierite and alleviated the sintering of La0.8Sr0.2MnO3, and thus kept the structure and the dispersion of La0.8Sr0.2MnO3 and enhanced the activity and thermal stability of the monolith catalyst.

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Deactivation and Regeneration of Ti/HMS Catalyst Used in Propylene Epoxida-tion JIN Guojie*;GAO Huanxin;YANG Hongyun;CHEN Lu;DING Lin;KANG Chenjun;XIE Zaiku 2009, 30 (12):  1238-1242.  Abstract ( 2163 )   [Full Text(HTML)] () PDF (421KB) ( 1060 )   Using cumene hydroperoxide as an oxidant, the deactivation and regeneration of the Ti/HMS (titanium-containing hexagonal mesoporous silica) catalyst were studied for epoxidation of propylene to propylene oxide. The structure and surface species of the fresh and used catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and thermogravimetry analysis. The results indicated that the main reason for catalyst deactivation was that the active sites on the catalyst surface were covered by polymer molecules produced during the reaction. The catalyst deactivation was not due to the transformation of tetra-coordinated Ti species to hexa-coordinated, octa-coordinated, or even anatase species. Hot cumene washing could partly restore the catalyst activity, but the low-temperature carbon-burning could restore the catalyst activity nearly to the level of fresh one. Therefore, the deactivated Ti/HMS catalyst was renewable and its activity could be restored by a proper regeneration method.

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Effects of Di-nitrogen Schiff Base Ligands on Olefin Epoxidation Catalyzed by Methyltrioxorhenium GAO Yu;ZHANG Yuecheng;ZHAO Jiquan* 2009, 30 (12):  1243-1247.  Abstract ( 2363 )   [Full Text(HTML)] () PDF (367KB) ( 1176 )   The di-nitrogen Schiff base ligands were synthesized by the condensation of 4-methylaniline with 2-pyridinecarboxaldehyde, 6-methyl-2-pyridinecarboxaldehyde, or 6-isopropyl-2-pyridinecarboxaldehyde, respectively. The Schiff base ligands were used as the additives for the epoxidation of three olefins, cyclohexene, styrene, and 1-octene, catalyzed by methyltrioxorhenium (MTO) with 30% H2O2 as oxidant. The effects of the solvent, reaction temperature, and structure of the Schiff base ligands on the epoxidation were investigated. Methanol was the best solvent for the catalytic system made up of above Schiff base ligands and MTO. The addition of the Schiff base ligands increased the epoxide selectivity remarkably. Both the conversion of cyclohexene and the selectivity of epoxide could reach up to 100% when the reaction was run at –10 oC for 12 h in methanol. The strong coordination capacity of the Schiff base is in favor of the augmentation of the selectivity for epoxide in the reaction. For these Schiff base ligands, the coordination capacity was determined by the electronic and steric properties of the substitute at 6-position in the pyridine ring. The alkyl group with small steric effect and strong electron donation could increase the coordination capacity, which increased the selectivity for the epoxidation reaction.

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The Effect of Fluorine Modification on Catalytic Performance of Nanosized HZSM-5 Zeolite for Conversion of Methanol to Propene GUO Qiangsheng;MAO Dongsen*;LAO Yanping;LU Guanzhong 2009, 30 (12):  1248-1254.  Abstract ( 2109 )   [Full Text(HTML)] () PDF (791KB) ( 990 )   Based on the comparison of catalytic performance of nanosized and microsized HZSM-5 zeolites for the conversion of methanol to propene, the fluorine-modified nanosized HZSM-5 zeolites were prepared by impregnation with NH4F aqueous solution. The parent and modified samples were characterized by transmission electron microscopy, N2 adsorption, X-ray diffraction, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. Their performance for conversion of methanol to propene was tested in a continuous flow fixed-bed micro-reactor at atmospheric pressure, 500 oC, and methanol space velocity (WHSV) of 1.0 h–1. The results showed that when the content of fluorine was lower than 10%, the amount and intensity of acidic sites on the fluorinated nanosized HZSM-5 zeolites decreased continuously with fluorine content increasing, which resulted in the enhanced selectivity for propene and catalyst stability. However, the modification with too higher content (15%) of fluorine decreased the catalyst stability due to the distinctly reduced amount of acid sites, surface area, and pore volume. It was concluded that after modification with appropriate amount (10%) of fluorine, the selectivity for propene and the reaction time that can maintain total conversion of methanol was increased significantly to 46.7% and 145 h from 30.1% and 75 h over the parent nanosized HZSM-5 zeolite, respectively.

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Cinchona-Derived Quaternary Ammonium Salts-Improved Asymmetric Cycloaddition of CO2 to Epoxides ZHANG Suling;SONG Yingying;JING Huanwang;*;YAN Peng;CAI Qiang;* 2009, 30 (12):  1255-1260.  Abstract ( 2733 )   [Full Text(HTML)] () PDF (385KB) ( 1103 )   A new catalyst system, SalenCoX/cinchona-derived quaternary ammonium salts, was developed to catalyze the cycloaddition of CO2 to epoxides under extremely mild reaction conditions. Chiral propylene carbonate was obtained with good enantioselectivity in the presence of the catalyst. The anions of the catalysts and the cocatalysts evidently affect the activity and enantioselectivity of the reaction. The activity of (S,S)-catalysts in terms of anion is in the order 2-nitrophenoxy > 2,4,6-trinitrophenoxy > NO3- > OAc- > CF3CO2- ≈ Br- > Cl- > OTs-. The cocatalyst with the Cl- anion gives the highest ee value for propylene carbonate. In contrast, the cocatalyst with the Br- anion has higher activity. When the catalyst (S,S)-(+)-1,2-cyclohexanediamino(N,N-bis(3,5-di-tert-butyl- salicylidene) cobalt(III) acetate ((S,S)-A) was combined with the cocatalyst N,O-dibenzylquininium chloride (1a) , it gives the highest 73% ee for propylene carbonate.

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Biodegradation of Trinitrotoluene by a Bacterial Consortium Containing Kleb-siella sp. and Burkholderia sp. GUO Xiaojie;XIN Baoping;*;MA Xingtai;XIA Yunting;CHEN Shi;YANG Yepeng 2009, 30 (12):  1261-1268.  Abstract ( 2555 )   [Full Text(HTML)] () PDF (486KB) ( 1033 )   The biodegradation characteristic and mechanism of trinitrotoluene (TNT) by a bacterial consortium S consisted of Klebsiella sp. S1 and Burkholderia sp. S2 were investigated by shaking-flask culture. The results show that the consortium S can completely biodegrade 0.1 g/L TNT in solution in the presence of both external carbon and nitrogen sources, whereas the biodegradation efficiency of TNT reaches 80% and 12%, respectively, with external carbon source only and nitrogen source only. Highly active nitroreductase was detected in the S1 catalyst system. This enzyme transformed TNT into a condensation product, diazodinitrotoluene, which was further degraded through ring cleavage catalyzed by the combined action of highly active toluene dioxygenase and catechol dioxygenase produced in the case of coexistence of S1 and S2. Nitro groups in TNT were released during the ring cleavage of diazodinitrotoluene, resulting in the formation of NO2–, which was further oxidized into NO3–. This bacterial consortium has greater potentials in biodegradation of TNT than the single bacterium.

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Density Functional Theoretical Study of Decomposition of Methane on Clean Pd(111) and Oxygen-Modified Pd(111) Surfaces Lü Cun-Qin, LING Kai-Cheng, WANG Gui-Chang 2009, 30 (12):  1269-1275.  Abstract ( 2497 )   [Full Text(HTML)] () PDF (22434KB) ( 726 )   The reaction pathway of C–H bond breaking of methane on the clean Pd(111) and O-modified Pd(111) surfaces was investigated by the first-principles density functional theory generalized gradient approximation calculations with the slab model. Geometries of reactants, transition states, and products were calculated. Adsorption energy of possible species and activation energy barriers of the reaction were also obtained. The calculated results show that methane favors such a configuration that one hydrogen points towards the surface in the top site. Methyl is adsorbed in the top site, and hydroxyl, oxygen, and hydrogen are all adsorbed in the fcc site. On the clean Pd(111) surface, the activation energy of 0.97 eV is smaller than that of 1.42 eV in the case of oxygen-modified (oxygen atom acts as a “spectator”) Pd(111) surface, which indicates that the presence of oxygen atom inhibited the C–H bond cleavage. Compared with the case that only the surface oxygen atom exists (oxygen atom participates in the reaction), the activation energy decreased from 1.43 to 0.72 eV when the subsurface oxygen atom exists. This suggests that the subsurface oxygen atom promotes the activation of methane molecule. On the oxygen-modified Pd(111), the activation energy of the reactions forming methyl and hydrogen, and methyl and hydroxyl is 1.42 and 1.43 eV, respectively, which indicates that the reaction possibility is equivalent.

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Asymmetric Reduction of Acetyltrimethylsilane Catalyzed by Candida parapsi-losis CCTCC M203011 Cells LOU Wenyong;GUO Qiang;YU Huilei;ZONG Minhua;* 2009, 30 (12):  1276-1280.  Abstract ( 2250 )   [Full Text(HTML)] () PDF (415KB) ( 722 )   The asymmetric reduction of acetyltrimethylsilane (ATMS) to (R)-1-trimethylsilylethanol (TMSE) catalyzed by Candida parapsilosis CCTCC M203011 cells was studied. It was found that the Candida parapsilosis CCTCC M203011 cells were capable of mediating the reduction of ATMS to (R)-1-TMSE with excellent enantioselectivity. The yield of (R)-1-TMSE with the cells immobilized on calcium alginate was higher than that with free cells. In addition, different co-substrates manifested a distinct effect on the bioreduction, and the initial reaction rate was clearly faster and the product yield was much higher using glucose as a co-substrate in the bioreduction. Moreover, the optimal glucose concentration, shaking rate, buffer pH, reaction temperature, and substrate concentration for the bioreduction were found to be 110 mmol/L, 180 r/min, 6.0, 30 oC,?and 20 mmol/L, respectively. Under these conditions, the initial reaction rate, maximum product yield, and product ee value were 11.4 μmol/h, 96.5%, and 99.9%, respectively.

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Influence of Noble Metals on the Direct Oxidation of Ethylene to Acetic Acid over NM/WO3-ZrO2 (NM = Ru, Rh, and Pd) Catalysts WANG Lixia;XU Shuliang;CHU Wenling;#;YANG Weishen;* 2009, 30 (12):  1281-1286.  Abstract ( 2215 )   [Full Text(HTML)] () PDF (390KB) ( 1216 )   Ru-, Rh-, and Pd/WO3-ZrO2 catalysts were studied for the direct oxidation of ethylene to acetic acid. The catalytic activity and selectivity depended strongly on the noble metals used. Rh/WO3-ZrO2 gave the highest conversion of ethylene, whereas Ru/WO3-ZrO2 was almost inactive. The higher catalytic activity was attributed to a better metal dispersion. Pd/WO3-ZrO2 gave the highest selectivity for acetic acid (75%), with the selectivity of the other two catalysts being rather low (~10%). Temperature-programmed oxidation and H2 reduction experiments were used to show that the strength of the noble metal–oxygen bond played an important role in product distribution. A weak metal–oxygen bond favored the formation of acetic acid, while a strong metal–oxygen bond favored the combustion of ethylene to COx.

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Vapor-Phase Synthesis of 3-Methylindole over Fe-, Co-, or Ni-Promoted Ag/SiO2 Catalysts Lü Wen-Hui, LIU Xing-Hai, LIU Dong-Yan, SHI Lei, SUN Qi 2009, 30 (12):  1287-1290.  Abstract ( 2295 )   [Full Text(HTML)] () PDF (445KB) ( 979 )   Fe, Co, or Ni as a promoter was added into the Ag/SiO2 catalyst for the vapor-phase synthesis of 3-methylindole from aniline and 1,2-propanediol. The promoted Ag/SiO2 catalysts were characterized by X-ray diffraction, H2 temperature-programmed reduction, and thermogravimetry. The results indicated that the addition of Fe or Ni to Ag/SiO2 was favorable for the increase of the catalyst selectivity. Among them, Fe could reinforce the interaction between the silver active component and the support and greatly promote the dispersion of silver particles on the support, which resulted in the remarkable increase in the initial activity of the catalyst. Adding Co or Ni to Ag/SiO2 promoted the sintering of silver during the reaction although it reduced the coking a little. As a result, the stability of the catalysts decreased.