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Chinese Journal of Catalysis
2007, Vol. 28, No. 6
Online: 25 June 2007

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Ionic Liquids as Solvents/Catalysts for Selective Alkylation of Amines with Alkyl Halides Yetkin GOK;Ismail OZDEMR;Engin CETINKAYA 2007, 28 (6):  489-491.  Abstract ( 2379 )   [Full Text(HTML)] () PDF (168KB) ( 1167 )   The selective alkylation of amino groups within amine derivatives with a variety of alkyl halides was carried out using ionic liquids ([bmim]I and [bmim]PF6) in the presence of triethylamine. The reaction was found to proceed under relatively mild conditions with excellent conversions and selectivities. The ionic liquid was recycled and reused.

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Asymmetric Hydroformylation of Styrene Catalyzed by Pyranoside Diphosphite-Rh(Ⅰ) Complexes JIA Xiaojing;WANG Lailai;*;Albert S. C. CHAN;LI Yueming 2007, 28 (6):  492-494.  Abstract ( 2357 )   [Full Text(HTML)] () PDF (192KB) ( 1024 )   Several chiral aryl diphosphite ligands derived from pyranoside backbones of glucose and galactose were applied in Rh-catalyzed asymmetric hydroformylation of styrene. A synergic effect between the chiralities of glucose and the binaphthyl moieties was observed. The sense of enantioselectivity is mainly controlled by the binaphthyl moieties, and the chirality of the sugar moiety can also affect the enantioselectivity of the reactions. In the case of the matching combination of phenyl-3,6-anhydro-β-D-glucopyranoside and binaphthyl moiety, 4-bis｛[(S)-1,1′-binaphthyl-2,2′-diyl]-phosphite｝-phenyl-3,6-anhydro-β-D-gluco-pyranoside (L4), 41% ee and 74∶26 of branch-to-normal ratio were obtained.

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Carbonylation of Amines with CO Catalyzed by Imidazole-2-selone LI Peng;WANG Xiaofang;YUAN Xiaohua;WANG Shudong;LU Shiwei* 2007, 28 (6):  495-497.  Abstract ( 2140 )   [Full Text(HTML)] () PDF (187KB) ( 866 )   The1,3-dialkylimidazole-2-selones-catalyzedoxidative carbonylation of organic amines and ethanolamine with carbon monoxide to ureas and2-oxazolidinonewas investigated. Moderate to good product yields were obtained. Odour existing in elemental selenium-catalyzed carbonylation reactions can be avoided in this catalytic system.Key words:1,3-dialkylimidazoleselone;selenium; carbon monoxide; amine; carbonylation; urea; 2-oxazolidinone

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Influence of Reduction Conditions on the Catalytic Activity of Ni2P/SiO2 for Gas-Phase Hydrodechlorination of Chlorobenzene ZHOU Shaojun;CHEN Jixiang*;LIU Xuguang;ZHANG Jiyan 2007, 28 (6):  498-500.  Abstract ( 2124 )   [Full Text(HTML)] () PDF (222KB) ( 924 )   The silica-supported nickel phosphide, Ni2P/SiO2, was prepared by the temperature-programmed reduction method, and the influence of reduction conditions (H2 flow rate, reduction temperature, and time) on the textural properties of the catalyst was investigated. There was no remarkable difference in BET specific surface area, pore structure, and the Ni2P crystallite size for the catalysts prepared under different reduction conditions, whereas the P contents on the catalyst surface differed obviously. The catalysts showed an induction period for the hydrodechlorination, which might be due to the excess P covering the active sites. The induction period could be shortened by increasing the H2 flow rate, reduction temperature, and reduction time during the catalyst preparation, indicating that reduction conditions influenced the surface properties of the catalyst. Ni2P/SiO2 showed excellent activity and stability for the hydrodechlorination of chlorobenzene. Under the conditions of 573 K, H2 flow rate of 75 ml/min, and chlorobenzene flow rate of 3 ml/h, the chlorobenzene conversion maintained above 99% during 130 h reaction over the Ni2P/SiO2 catalyst.

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Effects of H2O2 and H3PO4 on the Synthesis of SAPO41 and AlPO41 Molecular Sieves Using H3PO3 as the Phosphorus Source CHEN Huihui;CHAO Ran;NA Bo;LI Niu*;XIANG Shouhe;GUAN Naijia 2007, 28 (6):  501-503.  Abstract ( 1905 )   [Full Text(HTML)] () PDF (245KB) ( 912 )   Using H3PO3 as the phosphorus source is a new route to prepare SAPO-41 and AlPO-41 molecular sieves. However, it needs a long crystallization period for the formation of these AFO structure materials. In the present communication, effects of the addition of H2O2 and H3PO4 on the synthesis of SAPO-41 and AlPO-41 have been investigated. The addition of either H2O2 or H3PO4 can promote the crystallization of AlPO-41 and SAPO-41. Besides, SAPO-41 has been obtained with the crystal size smaller than 10 μm at lower di-n-propylamine concentration when the mixture of H3PO3 and H3PO4 is used as the phosphorus source.

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Electrochemical Behavior and Electrocatalytic Activity of Glassy Carbon Electrode Modified by Anthraquinone/Polypyrrole Composite Film ZHANG Guoquan;YANG Fenglin* 2007, 28 (6):  504-508.  Abstract ( 2327 )   [Full Text(HTML)] () PDF (386KB) ( 1123 )   Conductive and functional polypyrrole (PPy) film was prepared by incorporation of anthraquinonesulphonate (AQS) as dopant during the electropolymerization of pyrrole on a glassy carbon electrode in aqueous solution. The electrochemical behavior of AQS in PPy matrix in various pH buffer solutions and electrocatalytic reduction of oxygen on the resulting polymer film at the optimized pH of 5.5 were studied by using cyclic voltammetry (CV) and rotating disk electrode (RDE) technique. The results showed that PPy not only lowed the AQS reaction potential and the peak potential separation but also increased the redox peak currents. The value of ionization constant for H2AQ/HAQ- is 9.5. The CV and RDE studies showed the involvement of two electrons in oxygen reduction and H2AQ is responsible for the enhanced catalytic activity. The catalytic reaction is in agreement with an electrochemical-chemical mechanism. The AQS/PPy composite film-modified electrode was found to exhibit reproducible results.

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Catalytic Activity of Palladium Supported on Magnetic Nanoparticles for Heck Reaction SHEN Bin*;LI You;WANG Zhifei;HE Nongyue 2007, 28 (6):  509-513.  Abstract ( 2194 )   [Full Text(HTML)] () PDF (348KB) ( 1213 )   Carbon-enclosed magnetic nanoparticles synthesized by the hydrothermal method were used as a support for the palladium nanoparticle catalyst. The catalyst samples were characterized by transmission electron microscopy,X-rayphotoelectron spectroscopy, and a vibration sample magnetometer. Its catalytic activity for the Heck coupling reaction was measured. The results showed that the mean catalyst particle size was 300 nm, the surface was covered with a layer of palladium particles (12 nm), and the catalyst was of superparamagnetic property. In the Heck reaction of iodobenzene and acrylic acid catalyzed by the catalyst, high iodobenzene conversion (more than 95%) could be obtained under the base conditions of both CH3COONa and NEt3 after 4 h. The iodobenzene conversion over the catalyst was about 88% after 10 recycles, and the catalyst could be steadily dispersed in the reaction mixture and be separated by the magnetic field added.

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Mechanism of Carbon Burn-Off on V2O5/AC for Simultaneous SO2 and NO Removal During Regeneration in NH3 Atmosphere GUO Yanxia;LIU Zhenyu;LIU Qingya;SUN Dekui; 2007, 28 (6):  514-520.  Abstract ( 2293 )   [Full Text(HTML)] () PDF (496KB) ( 1003 )   The activated carbon (AC)-supported V2O5 catalyst-sorbent, V2O5/AC, was found to be very effective for the simultaneous removal of SO2 and NO from flue gas at 200 ℃. The catalyst-sorbent, however, may suffer from high carbon loss during periodical regeneration required by the SO2 removal process. The SO2-adsorbed V2O5/AC catalyst-sorbent could be regenerated in the presence of NH3 at low temperature (300 ℃), and the carbon burn-off is much less than that in an inert atmosphere. In this study, the behaviors and mechanism of carbon burn-off during the regeneration of V2O5/AC in 5%NH3-95%Ar were studied using temperature-programmed desorption, elemental analysis,X-rayphotoelectron spectroscopy, and Fourier transform infrared spectroscopy. The carbon consumption amount for the regeneration carried out in 5%NH3-95%Ar is much lower than that in Ar atmosphere. The presence of NH3 inhibits the carbon burn-off by reacting with the surface oxygen-containing groups in V2O5/AC,-COOH,-OH,and V2O5 etc, to produce H2O and nitrogen-containing groups such as-CONH2,C-N,andC≡N.

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Activity and Stability of Pelletized Ruthenium Catalysts in Wet Air Oxidation WANG Jianbing;ZHU Wanpeng*;WANG Wei;YANG Shaoxia;ZHOU Yunrui 2007, 28 (6):  521-527.  Abstract ( 2088 )   [Full Text(HTML)] () PDF (565KB) ( 897 )   A series of pelletized supports mainly consisting of CeO2 were developed by the traditional molding method and new molding method. Ruthenium catalysts loaded on these supports were prepared by impregnation. The analysis of BET surface area and mechanical strength of the catalysts were carried out. Their activity in wet air oxidation of acetic acid and the stability of Ru/ZrO2-CeO2 in wet air oxidation of phenol were investigated. Ruthenium catalysts prepared by the new method possess larger surface area than that prepared by the traditional method. Introduction of Zr into Ru/CeO2 can increase surface area of the catalyst. In a batch experiment of wet air oxidation of acetic acid with pelletized Ru/ZrO2-CeO2, chemical oxygen demand (COD) removal was 98%. In the dynamic experiment of wet air oxidation of phenol with pelletized Ru/ZrO2-CeO2, phenol and COD reduction was maintained at 96% during 110 h of reaction. The concentration of the main intermediates was small. In the experiment of catalytic wet air oxidation of phenol, the leaching concentration of active species was small. There were small amounts of carbonaceous deposits on the surface of the used catalysts, and the carbonaceous deposits can be completely oxidized at 300 ℃. Pelletized Ru/ZrO2-CeO2 possesses good stability and possibility of use in practical processes.

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Parameter Effects and Reaction Pathways of Photoreduction of CO2 over TiO2/SO2-4 Photocatalyst LO Cho-Ching;HUNG Chung-Hsuang;YUAN Chung-Shin;*;HUNG Yu-Li 2007, 28 (6):  528-534.  Abstract ( 3130 )   [Full Text(HTML)] () PDF (392KB) ( 1211 )   The feasibility of applying a modified acidic photocatalyst (TiO2/SO2-4) to reduce carbon dioxide was investigated. The photocatalytic reduction of CO2 was conducted in a bench-scale batch photocatalytic reactor. Three near-UV black lamps with a maximal spectrum wavelength of 365 nm were assembled on the top of the reactor to provide an average irradiated light intensity of 2.0 mW/cm2. The TiO2/SO2-4 photocatalyst was prepared by a modified sol-gel process and coated on stainless steel substrates for the reduction of CO2. Experimental parameters such as the reductants, the initial CO2 concentration, and the reaction temperature were investigated. The results indicated that the highest photoreduction rate of CO2 was observed using H2 as a reductant over TiO2/SO2-4. The major gaseous products from CO2 photoreduction were carbon monoxide and methane, while other minor products of ethene and ethane were also detected in the experiments. The photoreduction rate of CO2 was found to be increased with initial CO2 concentration and reaction temperature, which promoted the formation of reaction products. Furthermore, the FT-IR spectra showed that formic acid, methanol, carbonate ions, formaldehyde, and methyl formate formed on the surface of TiO2/SO2-4 photocatalyst. Two reaction pathways of CO2 photoreduction over TiO2/SO2-4 photocatalyst were proposed. One reaction pathway described the formation of gaseous products CO, CH4, C2H4, and C2H6. The other reaction pathway formed CO2-3ads, CH3OHads, HCOO-ads, HCOOHads, HCOHads, and HCOOCH3adson the surface of TiO2/SO2-4 photocatalyst.

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Preparation of Supported Au-Pd Bimetallic Catalyst and Its Catalytic Activity for CO Oxidation MA Chunyan;LI Xinhua;JIN Mingshan;LIAO Weiping;GUAN Rengui;SUO Zhanghuai* 2007, 28 (6):  535-540.  Abstract ( 2398 )   [Full Text(HTML)] () PDF (390KB) ( 924 )   The Au-Pd/SiO2 catalyst was prepared by impregnation of SiO2 with an alkaline HAuCl4 solution by an incipient wetness method. The effect of calcination temperature on the catalytic activity for CO oxidation was evaluated. The Au-Pd/SiO2 catalyst calcined in air at 673 K shows higher catalytic activity compared with the catalysts calcined at 623, 723, or 773 K. The catalyst was characterized by N2 adsorption-desorption isotherms,X-raydiffraction, temperature-programmed reduction, CO temperature-programmed desorption, andX-rayphotoelectron spectroscopy. The results indicate that the catalyst calcined at 673 K has the largest surface area and the smallest pore volume, and there exist Pd0, PdO, and Au0 phases on it. The formation of AuxPdy alloy does not favor the catalyst activity.

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Comparison of Core/Shell Binary Structure Zeolite ZSM-5/SAPO-5 Synthesized by Vapor-Phase Transport and Hydrothermal Synthesis ZHANG Qiang*;LI Chunyi;SHAN Honghong;YANG Chaohe 2007, 28 (6):  541-546.  Abstract ( 2421 )   [Full Text(HTML)] () PDF (393KB) ( 948 )   A series of ZSM-5(core)/SAPO-5 (shell) binary structure zeolite samples were synthesized by hydrothermal synthesis and vapor-phase transport at different crystallization temperatures for different time. Phosphoric acid, pseudoboehmite, and silica sol were used as phosphorus, aluminum, and silicon sources, respectively. Triethylamine was used as template. The zeolite samples were characterized by means ofX-raydiffraction, scanning electron microscopy,X-rayenergy dispersive spectroscopy, Fourier transform infrared spectroscopy, and N2 adsorption. The zeolite samples had binary structure with a ZSM-5 core and a SAPO-5 shell. The crystallinity of the zeolite samples increased as the crystallization temperature was increased and the crystallization time was protracted. Using the vapor-phase transport technique for synthesis of binary structure zeolite could reduce the SAPO-5 particle size and the amount of self-existent SAPO-5 zeolite and improve the distribution of SAPO-5 on the ZSM-5 surface. The experiments of heavy oil cracking showed that the core/shell binary structure zeolite samples were more favorable for the formation of light olefins than the mechanical mixture.

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Synthesis of Star Poly(ε-caprolactone) Catalyzed by Lanthanum Tris(2,6-di-tert-butyl-4-methylphenolate) ZHU Weipu;CHEN Wei;SHEN Zhiquan* 2007, 28 (6):  547-550.  Abstract ( 2352 )   [Full Text(HTML)] () PDF (221KB) ( 802 )   Tri- and tetra-arm star poly(ε-caprolactone)s have been successfully synthesized by ring-opening polymerization of ε-caprolactone using triethanolamine or N,N,N′,N′-tetrakis-(2-hydroxyethyl) ethylenediamine (HEA) as the multifunctional initiator and lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) (La(DBMP)3) as the catalyst. In1HNMR analysis, compared with triethanolamine and HEA molecules, the chemical shifts of the hydrogen (N(CH2CH2O)n, n=3, 4) in star poly(ε-caprolactone)s moved from 3.65 to 4.10, suggesting the direct linkage between the poly(ε-caprolactone) arm and the initiator. When the molar ratio of triethanolamine to La(DBMP)3 ranged from 1.7 to 6.4, pure tri-arm star poly(ε-caprolactone) could be prepared, which indicates that one catalyst molecule could co-work with several initiator molecules. The molecular weights of star poly(ε-caprolactone) were determined by1HNMR end group analysis, which are very close to the values calculated from the molar ratio of ε-caprolactone to the initiator.

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Influence of Silylation on Catalytic Performance of Ti/HMS Molecular Sieve LI Xuefeng;GAO Huanxin;JIN Guojie;DING Lin;CHEN Lu;YANG Hongyun;HE Xin;CHEN Qingling;* 2007, 28 (6):  551-556.  Abstract ( 2202 )   [Full Text(HTML)] () PDF (459KB) ( 940 )   Ti/HMS samples were prepared by hydrothermal synthesis (HTS) and chemical vapor deposition (CVD) methods and then silylated by trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDSZ) in a vapor phase. The samples were characterized by XRD, N2 adsorption, FT-IR,29SiNMR, and DRUV-Vis, and their catalytic performance for the epoxidation of propylene using cumene hydroperoxide as oxidant was measured. The silylation could promote remarkably the catalytic performance. The Ti/HMS silylated by HMDSZ had much higher catalytic activity than that silylated by TMCS. This is because TMCS could not only react with silanol but also breakSi-O-TiandSi-O-Sibonds to form new silanol, which led to higher hydrophilicity for the silylated samples than those silylated by HMDSZ. The silylation with TMCS partially destroyed the tetracoordinated framework titanium species in Ti/HMS, but this did not occur in the silylation with HMDSZ.

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Hydroformylation of Tripropene in Thermoregulated PEG Biphasic Catalytic System YANG Yuchuan;JIANG Jingyang*;WANG Yanhua;LIU Chun;JIN Zilin 2007, 28 (6):  557-560.  Abstract ( 2130 )   [Full Text(HTML)] () PDF (214KB) ( 927 )   The thermoregulated PEG (polyethylene glycol) biphasic catalytic system, which has a characteristic of “being homogeneous at high temperature and biphasic at room temperature★, was applied for the hydroformylation of tripropene catalyzed by Rh(acac)(CO)2/TMPGP (TMPGP: P[O(CH2CH2O)nCH3]3, n=8). The effects of reaction conditions on the reaction and the catalyst recycling efficiency were studied systematically. Under the optimized reaction conditions (V(CO)/V(H2)=1, 6 MPa, and 130 ℃), tripropene conversion and aldehyde yield reached 77% and 75%, respectively. The PEG phase containing the catalyst was separated at room temperature and recycled 11 times without significant loss of catalytic activity. The Rh leaching into the product phase in the first run was 1.5% (mass fraction), and the average Rh loss for each run of the 11 cycles was 0.69%. Further studies showed that the catalyst phase could be recycled 15 times without loss of catalytic activity when the whole catalytic system was cooled to-20℃, and the Rh leaching into the product phase was only 0.16% in the first run.

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Fe3+-Modified Nano-ZnO Photocatalyst and Its Catalytic Activity for Degradation of Nonylphenol Ethoxylate-10 ZHANG Jingfeng;DU Zhiping*;ZHAO Yonghong;TAI Xiumei 2007, 28 (6):  561-566.  Abstract ( 2372 )   [Full Text(HTML)] () PDF (448KB) ( 843 )   Fe3+-modified ZnO samples with different amounts of Fe were prepared by the ammonia immersion method. The crystal structure, specific surface area, atomic states on surface, and spectral characteristics were analyzed byX-raydiffraction, N2 adsorption,X-rayphotoelectron spectroscopy, and diffuse reflectance ultraviolet-visible spectroscopy, respectively. The photocatalytic activity of Fe3+/ZnO samples for degradation of nonylphenol ethoxylate-10 (NPE-10) was studied under the irradiation with ultraviolet and visible light. The results showed that Fe could be successfully doped on the nano-ZnO crystal. The particle size of Fe3+/ZnO decreased and its specific surface area increased with the increase in doping Fe3+. Compared with the nano-ZnO, the binding energy of Fe 2p in Fe3+/ZnO dropped, but the binding energy of Zn 2p and O 1s increased. The content of adsorbed O and hydroxy O on the surface of Fe3+/ZnO increased remarkably in contrast to that of the pure ZnO sample. The 0.5%Fe3+/ZnO exhibited a red shift in the absorption spectrum. The photocatalytic activity of the 0.5%Fe3+/ZnO sample was highest, and the extra 18% and 69% degradation rate of NPE-10 could be found under3 hirradiation of ultraviolet and visible light, respectively.

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Catalytic Cracking of Butene over Nano-Sized H-ZSM-5 Catalyst LI Fufen;JIA Wenhao;CHEN Lixing;GUO Hongchen* 2007, 28 (6):  567-571.  Abstract ( 2632 )   [Full Text(HTML)] () PDF (377KB) ( 911 )   In a small continuous flowing fixed-bed reactor, the nano-sized H-ZSM-5 catalyst with crystal size of20-50nm was applied to the catalytic cracking of butene from liquefied petroleum gas for propene synthesis. The catalytic performance of the nano-sized H-ZSM-5 catalyst was compared with that of two micro-sized H-ZSM-5 samples with crystal size of1-2and1-6μm, respectively. Under the same reaction conditions, the nano-sized H-ZSM-5 and the micro-sized H-ZSM-5 samples had approximately the same initial butene conversion and propene yield. However, the nano-sized H-ZSM-5 sample exhibited better resistance to coking and deactivation. Under the reaction conditions of WHSV=7 h-1, p=0.1 MPa, and θ=560 ℃, the butene conversion and propene yield over the micro-sized H-ZSM-5 samples decreased by about 50% after reaction for only28 h, whereas over the nano-sized H-ZSM-5 sample the reaction time could be prolonged to 120 h. According to the coke analysis results, the coking rate on the nano-sized H-ZSM-5 sample was lower than that on the micro-sized samples.

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High Selective Synthesis of2,6-Dimethylnaphthanlene Catalyzed by Acidic Ionic Liquids WU Wei;WEI Xiaoli;WU Guang;LI Lingfei;ZHANG Milin 2007, 28 (6):  572-578.  Abstract ( 2272 )   [Full Text(HTML)] () PDF (331KB) ( 1328 )   The transalkylation of1,2,4,5-tetramethylbenzene (TeMB) with 2-methylnaphthalene (2-MN) to synthesize2,6-dimethylnaphthalene (2,6-DMN) by ionic liquid Et3NHCl-AlCl3 was investigated, and the effects of the acidic strength of the ionic liquid and the reaction conditions on the transalkylation were studied. The results showed that a high selectivity for2,6-DMN can be obtained by controlling the acid strength of the ionic liquid and optimizing the reaction conditions. Using cyclohexane as the solvent and Et3NHCl-AlCl3(x(AlCl3)=0.71) as the catalyst, 48.8% 2-MN conversion, 81.2% selectivity for DMN, 52.4% molar ratio of2,6-DMN/total dimethylnaphthalenes, and 20.8% yield of2,6-DMN were obtained under the reaction conditions of 20 ℃,6 h, and 2-MN∶TeMB molar ratio of 1∶1. In addition, the catalyst exhibited 100% molar ratio of2,6-DMN/total dimethylnaphthalenes with 3.7% 2-MN conversion during2 hreaction under the optimized reaction conditions. A high selectivity for2,6-DMN was also obtained when a feed of mixed methylnaphthalene or naphthalene was used. The reuse of the ionic liquid was investigated and the main reason for the catalyst deactivation was discussed.