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    Chinese Journal of Catalysis
    2013, Vol. 34, No. 6
    Online: 07 June 2013

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    Phenol is resistant to biodegradation and persists in environment for long periods. Wan and co-workers in their Article on pages 1066–1075 report the high efficiency of ordered mesoporous carbon-based anatase in degrading phenol through adsorption and visible light-driven photocatalysis cycles. The carbon-based anatase catalysts possess honeycomb-like ordered mesoporous channels, amorphous carbon frameworks, and intercalated carbon-doped anatase nanocrystals. The combination of physical and chemical treatments solves the problems for regeneration of carbon adsorbent and leaching of anatase nanocatalyst.

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    Table of Contents
    Table of Contents for Vol. 34 No. 6
    2013, 34 (6):  0-0. 
    Abstract ( 314 )   PDF (1626KB) ( 331 )  
    Reviews
    Progress in synthesis of ethylene glycol through C1 chemical industry routes
    SONG Heyuan, JIN Ronghua, KANG Meirong, CHEN Jing
    2013, 34 (6):  1035-1050.  DOI: 10.1016/S1872-2067(12)60529-4
    Abstract ( 873 )   [Full Text(HTML)] () PDF (740KB) ( 1347 )  

    Ethylene glycol (EG) is an important industrial chemicals. It has attracted attention because it can be used to synthesize polyester resins and fibers. C1 chemical industry routes have been explored for EG synthesis from syngas and coal as starting materials. It is suggested that such routes are more promising methods for EG synthesis than the use of petroleum is. The pertinent literature on EG synthesis through C1 chemical industry routes are summarized. The methods include direct synthesis from syngas, carbonylation of formaldehyde, CO coupling reactions, hydroformylation of formaldehyde, and condensation of formaldehyde.

    Progress in non-platinum catalysts with applications in low temperature fuel cells
    ZHANG Jie, TANG Shuihua, LIAO Longyu, YU Weifei
    2013, 34 (6):  1051-1065.  DOI: 10.1016/S1872-2067(12)60588-9
    Abstract ( 799 )   [Full Text(HTML)] () PDF (654KB) ( 1081 )  

    Non-platinum catalysts have recently attracted significant attention with regard to their potential applications in low temperature fuel cells. This review summarizes the progresses in the development of these catalysts to date, including anode and cathode catalysts. Anode catalysts based on metal carbides, Pd alloys, and perovskite oxides are described, focusing on their catalytic activity. The non-platinum cathode catalysts include transition metal macrocyclic compounds, metal nitrides, and metal oxides. Particularly, various aspects are discussed in detail, including active sites, metal-support interactions, and the preparation parameters for transition metal macrocyclic compounds. All the compounds reviewed are considered promising candidates that may find commercial applications as non-platinum anode and cathode catalysts for fuel cells.

    Articles
    Ordered mesoporous carbon-based titania as a reusable adsorbent-catalyst for removing phenol from water
    WEI Wei, YU Chao, ZHAO Qingfei, QIAN Xufang, WAN Ying
    2013, 34 (6):  1066-1075.  DOI: 10.1016/S1872-2067(12)60567-1
    Abstract ( 689 )   [Full Text(HTML)] () PDF (641KB) ( 765 )  

    The high efficiency of ordered mesoporous carbon-based anatase for the visible light-driven photo-degradation of phenol in water is reported. Adsorption-photocatalysis cycles were used to treat polluted water. Contaminated water containing 200 mg/L phenol can be completely mineralized within 10 cycles, in which each cycle consisted of adsorption for 8 h and visible light-driven illumination for 8 h. The roles of non-metal doping in the anatase lattice, aggregation-free confinement of anatase nanoparticles by the carbon pore wall, and adsorption of phenol in the mesopores on the catalytic performance are discussed. The present work provides an effective combination of physical and chemical treatments to remove relatively high concentrations of non-biodegradable organic substances using a mesoporous photocatalyst.

    Preparation and photocatalytic activity of rutile TiO2 and goethitecomposite photocatalysts
    XIE Weimiao, CHEN Hui, ZHANG Xuanhui, HU Xianchao, LI Guohua
    2013, 34 (6):  1076-1086.  DOI: 10.1016/S1872-2067(12)60569-5
    Abstract ( 648 )   [Full Text(HTML)] () PDF (1364KB) ( 1130 )  

    Rutile TiO2 and goethite (α-FeOOH) composite photocatalysts were fabricated by hydrolysis and precipitation using titanium tetrachloride as a precursor and α-FeOOH as a support. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results show that at lower temperature, rutile TiO2 particles coat on the surface of α-FeOOH particles to form rutile TiO2-α-FeOOH composite photocatalyst. At higher temperature, iron ions are doped into the rutile TiO2 lattice to form iron-doped rutile TiO2 tubes; at medium temperature, the sample is a mixture with both composite and iron-doped structures. The photocatalytic activity of the samples is estimated by their ability to degrade methyl orange under irradiation with ultraviolet-visible light (200-800 nm) at ambient temperature. The photocatalytic activities of the samples are improved compared with that of pure rutile TiO2 and α-FeOOH. The sample containing a mixture of composite and iron-doped structures shows the highest photocatalytic activity of that investigated. As a result, the photocatalytic activity of Ti2O could be improved effectively by combining with α-FeOOH or doping iron.

    Effects of cerium on the selective catalytic reduction activity and structural properties of manganese oxides supported on multi-walled carbon nanotubes catalysts
    LI li, WANG Lishan, PAN Siwei, WEI Zhengle, HUANG Bichun
    2013, 34 (6):  1087-1097.  DOI: 10.1016/S1872-2067(11)60520-2
    Abstract ( 578 )   [Full Text(HTML)] () PDF (1149KB) ( 699 )  

    A series of manganese and cerium oxides supported on multi-walled carbon nanotubes (MWCNTs) catalysts for low-temperature NH3 selective catalytic reduction (SCR) of NOx were prepared by the pore volume impregnation method. The SCR activity of Mn-Ce/MWCNTs catalysts was compared with that of Mn/MWCNTs catalyst. The effects of Ce were characterized by transmission electron microscopy, N2 adsorption-desorption, H2 temperature-programmed reduction, X-ray photoelectron spectroscopy and X-ray powder diffraction. The results show that the addition of cerium oxides could improve the SCR activity of Mn/MWCNTs catalysts. Mn-Ce/MWCNTs catalyst with a Ce/Mn ratio of 0.6 was found to have the highest activity. The addition of cerium oxides enhanced the dispersion of metal oxides on the MWCNTs. It could also increase the specific surface area and total pore volume, and decrease the average pore size of the catalysts. Ce would improve the concentration of oxygen and the valence of manganese. Furthermore, from the XRD results, it was obvious that the crystalline MnOx disappeared because of the introduction of Ce to the catalyst. MnOx mainly existed in an amorphous state or microcrystal structure in the Mn-Ce/MWCNTs catalysts. CeO2 was found to be the main phase for CeOx.

    Voltammetric determination of ascorbic acid in the presence of acetaminophen and tryptophan using an improved carbon nanotube paste electrode
    Hadi BEITOLLAHI, Somayeh MOHAMMADI
    2013, 34 (6):  1098-1104.  DOI: 10.1016/S1872-2067(12)60544-0
    Abstract ( 636 )   [Full Text(HTML)] () PDF (447KB) ( 990 )  

    A carbon paste electrode (CPE) modified with carbon nanotubes and 5-amino-3',4'-dimethyl- biphenyl-2-ol (5ADB) is prepared. Under the optimum pH of 7.0, the oxidation of ascorbic acid (AA) on the modified CPE occurs at a potential about 280 mV less positive than that on the unmodified CPE. Some kinetic and thermodynamic parameters for electrocatalytic oxidation of AA, including electron transfer coefficient (α = 0.58) and diffusion coefficient (D=2.2×10-6 cm2/s), are also determined. AA, acetaminophen (AC), and tryptophan (TRP) were detected simultaneously using the modified CPE. The peak potentials recorded using the modified CPE in phosphate-buffered solution at pH 7.0 were 265, 465, and 780 mV for AA, AC, and TRP, respectively. The modified CPE was successfully used to determine the concentrations of AA, AC, and TRP in real samples.

    Effect of methanol concentration on oxygen reduction reaction activity of Pt/C catalysts
    TANG Shuihua, LIN Wenfeng, Paul A. CHRISTENSEN, Geir Martin HAARBERG
    2013, 34 (6):  1105-1111.  DOI: 10.1016/S1872-2067(11)60480-4
    Abstract ( 608 )   [Full Text(HTML)] () PDF (536KB) ( 914 )  

    The oxygen reduction reaction (ORR) activity of Pt/C catalysts was investigated in electrolytes of 0.5 mol/L H2SO4 containing varying concentrations of methanol in a half-cell. It was found that the ORR activity was improved notably in an electrolyte of 0.5 mol/L H2SO4 containing 0.1 mol/L CH3OH as compared with that in 0.5 mol/L H2SO4, 0.5 mol/L H2SO4 containing 0.5 mol/L CH3OH, or 0.5 mol/L H2SO4 containing 1.0 mol/L CH3OH electrolytes. The same tendency for improved ORR activity was also apparent after commercial Nafion® NRE-212 membrane was hot-pressed onto the catalyst layers. The linear sweep voltammetry results indicate that the ORR activities of the Pt/C catalyst were almost identical in the 0.5 mol/L H2SO4+0.1 mol/L CH3OH solution before and after coated with the Nafion® membrane. Electrochemical impedance spectroscopy results demonstrated that the resistance of the Nafion® membrane is smaller in the electrolyte of 0.5 mol/L H2SO4+0.1 mol/L CH3OH than in other electrolytes with oxygen gas feed. This exceptional property of the Nafion® membrane is worth investigating and can be applied in fuel cell stacks to improve the system performance.

    Effect of CuSAPO-34 catalyst preparation method on NOx removal from diesel vehicle exhausts
    ZUO Yongquan, HAN Lina, BAO Weiren, CHANG Liping, WANG Jiancheng
    2013, 34 (6):  1112-1122.  DOI: 10.1016/S1872-2067(11)60517-2
    Abstract ( 640 )   [Full Text(HTML)] () PDF (802KB) ( 901 )  

    CuSAPO-34 samples prepared by hydrothermal synthesis (HS), pore-volume impregnation (PVI), and ion-exchange (IE) methods were characterized using X-ray diffraction, scanning electronic microscopy, atomic absorption spectroscopy, temperature-programmed reduction with hydrogen, X-ray absorption near-edge structure spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption. The selective catalytic reduction (SCR) ability over CuSAPO-34 for NOx from a simulated diesel exhaust was investigated through C3H6-SCR and NH3-SCR, before and after aging of the CuSAPO-34 catalyst. The results indicated that the sample prepared by IE had significantly better activity compared with those prepared using HS and PVI, especially in C3H6-SCR at temperatures below 300℃. The activity of CuSAPO-34 in NO SCR was affected by the preparation method as a result of changes in the specific area (ABET), pore-size distribution, and the valence state of the active component. The active component of the catalyst prepared by HS was mainly Cu2+, whereas those of samples prepared by IE and PVI were mainly Cu+. Aging treatment can destroy the structure of the catalyst, decrease its surface area, and reduce the number of active Cu components on the catalyst surface, leading to a visible decrease in catalytic activity. The CuSAPO-34 prepared using the PVI method had the smallest decrease in NO SCR activity after aging, showing that it had better anti-aging properties.

    Inhibiting Pd nanoparticle aggregation and improving catalytic performance using one-dimensional CeO2 nanotubes as support
    TANG Zirong, YIN Xia, ZHANG Yanhui, ZHANG Nan, XU Yijun
    2013, 34 (6):  1123-1127.  DOI: 10.1016/S1872-2067(12)60536-1
    Abstract ( 828 )   [Full Text(HTML)] () PDF (921KB) ( 982 )  

    One-dimensional (1D) CeO2 nanotubes can be used as a support to inhibit Pd nanoparticle aggregation during the high temperature calcination process in air. This is in opposition to the significant aggregation of Pd particles that is observed for the preparation of supported Pd metal catalysts using non-1D commercial CeO2 as support. The as-prepared Pd/CeO2 nanotube catalyst exhibits much higher catalytic performance than Pd/commercial CeO2 toward the aerobic selective oxidation of benzyl alcohol to benzaldehyde. This work suggests that 1D metal oxide materials can be used as a promising class of supports to inhibit noble metal nanoparticle aggregation, thereby improving catalytic performance toward target reactions.

    Influence of reaction conditions on one-step hydrotreatment of lipids in the production of iso-alkanes over Pt/SAPO-11
    WANG Congxin, LIU Qianhe, LIU Xuebin, YAN Lijun, LUO Chen, WANG Lei, WANG Bingchun, TIAN Zhijian
    2013, 34 (6):  1128-1138.  DOI: 10.1016/S1872-2067(11)60524-X
    Abstract ( 641 )   [Full Text(HTML)] () PDF (632KB) ( 1838 )  

    A one-step hydrotreatment of soybean oil to produce iso-alkanes has been carried out over a Pt/SAPO-11 catalyst in a fixed-bed reactor. The influence of reaction conditions such as temperature, pressure, hydrogen/oil ratio, and space velocity on the catalytic performance has been investigated. From the levels of intermediate products, gas products (CO, CO2) and the target product (alkane), it was found that the hydrogenolysis of esters, fatty acids and fatty aldehydes and the formation of fatty alcohols were prohibited, which led to high selectivity for hydrodecarboxylation and hydrodecarbonylation at high temperature, low pressure or low hydrogen/oil ratio. The selectivity of the isomerization increased when temperature increased or space velocity decreased, while pressure and hydrogen/oil ratio were found to have no influence. A plausible reaction pathway has been proposed based on these results.

    Kerosene cracking over supported monolithic Pt catalysts: Effects of SrO and BaO promoters
    JIAO Yi, WANG Jia, QIN Lixiao, WANG Jianli, ZHU Quan, LI Xiangyuan, GONG Maochu, CHEN Yaoqiang
    2013, 34 (6):  1139-1147.  DOI: 10.1016/S1872-2067(12)60541-5
    Abstract ( 493 )   [Full Text(HTML)] () PDF (772KB) ( 728 )  

    The cracking of RP-3 fuel over supported monolithic Pt catalysts was studied at atmospheric pressure. The influence of BaO and SrO additives on the cracking reaction was examined. The effect of reaction time on the amount of carbon deposited during cracking was investigated. The catalysts were characterized using an automatic adsorption instrument (for Brunauer-Emmett-Teller analysis), temperature-programmed reduction, X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The results show that the total amount of gaseous products produced in catalytic cracking over a monolithic Pt/CA(CeO2-Al2O3)-La-Al2O3 (CA is a support) catalyst increased by 39.7% compared with that produced by thermal cracking. The addition of BaO or SrO improved the total amount of gaseous products by 25.6% and 37%, respectively. If BaO and SrO were simultaneously added to the monolithic Pt/CA-La-Al2O3 catalyst, the catalytic effect improved significantly, and the total amount of gaseous products increased by 96.5%. The addition of BaO or SrO effectively inhibits carbon deposition, and the synergistic effect of BaO and SrO additives improves the cracking reaction.

    Modification of nanocrystalline HZSM-5 zeolite with tetrapropylammonium hydroxide and its catalytic performance in methanol to gasoline reaction
    HE Yingping, LIU Min, DAI Chengyi, XU Shutao, WEI Yingxu, LIU Zhongmin, GUO Xinwen
    2013, 34 (6):  1148-1158.  DOI: 10.1016/S1872-2067(12)60579-8
    Abstract ( 625 )   [Full Text(HTML)] () PDF (895KB) ( 980 )  

    Nanocrystalline ZSM-5 zeolite was modified with tetrapropylammonium hydroxide (TPAOH) solution. The effect of the TPAOH treatment time on the catalytic performance of HZSM-5 was investigated in methanol to gasoline (MTG) reaction. The modified samples were characterized using X-ray diffraction, scanning electron microscopy, 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption, and NH3 temperature-programmed desorption. The HZSM-5 structure was basically unchanged after modification, but the relative crystallinity increased and the crystal morphology was more regular. The Brunauer-Emmett-Teller surface area, the micropore surface area, the surface Si/Al ratio, and the amount of strong acid sites increased; this might be caused by desilication and dealumination, and secondary crystallization of the zeolite during the treatment. The stability of the catalyst was significantly improved after modification, as reflected by the increased lifetime from 70 h to above 170 h in MTG reaction. The catalyst lifetime increased with increasing TPAOH treatment time. Hydrogen transfer reactions became faster and led to more isoparaffins and less olefins in the liquid products.

    Vapor-phase selective dehydration of 1,4-butanediol to 3-buten-1-ol over ZrO2 catalysts modified with alkaline earth metal oxides
    ZHANG Qian, ZHANG Yin, LI Haitao, ZHAO Yongxiang, MA Meng, YU Yu
    2013, 34 (6):  1159-1166.  DOI: 10.1016/S1872-2067(12)60525-7
    Abstract ( 637 )   [Full Text(HTML)] () PDF (639KB) ( 828 )  

    Modified ZrO2 catalysts were prepared by doping with alkaline earth metal oxides (CaO, SrO, or BaO) in a wet impregnation method. The catalysts were characterized by N2 physisorption, X-ray diffraction, and temperature-programmed desorption (TPD) with NH3 and CO2. Their catalytic performance in the vapor-phase selective dehydration of 1,4-butanediol (BDO) to 3-buten-1-ol (BTO) was investigated. The results showed that the alkaline earth metal can change the acid-base properties on the catalyst surface and thus affect BDO conversion and BTO product selectivity. For ZrO2 catalyst modified by CaO, Ca2+ entered the ZrO2 crystal lattice and formed Ca?O?Zr hetero-linkages. These allowed the CaO/ZrO2 catalyst to maintain a high acid density and generate a large number of basic sites when compared with unmodified ZrO2. In contrast, SrO and BaO reacted with ZrO2 to generate the corresponding zirconates, which resulted in decreased acid density on the catalyst surface. Of the catalysts tested, CaO/ZrO2 showed the best catalytic performance. The highest yield of BTO was 60.5% and was achieved at 350℃ over CaO/ZrO2 catalyst. The key point for highly selective dehydration of BDO to BTO resided in the synergistic effect between acid and base sites on the catalyst surface.

    Enhancement of photocatalytic properties of Ga2O3-SiO2 nanoparticles by Pt deposition
    E. S. BAEISSA, R. M. MOHAMED
    2013, 34 (6):  1167-1172.  DOI: 10.1016/S1872-2067(12)60570-1
    Abstract ( 579 )   [Full Text(HTML)] () PDF (552KB) ( 787 )  

    Ga2O3-SiO2 nanoparticles were prepared by a sol-gel method and Pt was then immobilized on their surface via photo-assisted deposition (PAD). The produced samples were characterized using X-ray diffraction (XRD), ultraviolet and visible spectroscopy, photoluminescence emission spectroscopy, and surface area measurements. The catalytic performances of the Ga2O3-SiO2 and Pt/ Ga2O3-SiO2 samples were evaluated for the degradation of cyanide using visible light. XRD and EDX results showed that the Pt was well dispersed within the Ga2O3-SiO2 phase and was detected on the surface of the catalyst, which confirmed the successful loading of Pt ions by the PAD method. BET results revealed that the surface area of Ga2O3-SiO2 was higher than that of Pt/Ga2O3-SiO2. 0.3 wt% Pt/Ga2O3-SiO2 exhibited the highest photocatalytic activity for degradation of cyanide under visible light. The catalyst could be reused with no loss in activity for the first 10 cycles.

    Tetrabutylammonium hexatungstate [TBA]2[W6O19]: Novel and reusable heterogeneous catalyst for rapid solvent-free synthesis of polyhydroquinolines via unsymmetrical Hantzsch reaction
    Abolghasem DAVOODNIA, Maryam KHASHI, Niloofar TAVAKOLI-HOSEINI
    2013, 34 (6):  1173-1178.  DOI: 10.1016/S1872-2067(12)60547-6
    Abstract ( 633 )   [Full Text(HTML)] () PDF (359KB) ( 770 )  

    A novel, efficient, and environmentally friendly method for the synthesis of polyhydroquinoline derivatives by a one-pot, four-component unsymmetrical Hantzsch condensation of dimedone, aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of tetrabutylammonium hexatungstate [TBA]2[W6O19] under solvent-free conditions has been developed. The results showed that this heterogeneous catalyst has high catalytic activity and the desired products were obtained in good to high yields. Moreover, the catalyst was found to be reusable and considerable catalytic activity was still achieved after the fifth run.

    Sequential Ag-catalyzed carboxylative coupling/Ru-catalyzed cross-metathesis reactions for the synthesis of functionalized 2-alkynoates
    ZHANG Linlin, ZHANG Wenzhen, SHI Linglong, REN Xiang, Lü Xiaobing
    2013, 34 (6):  1179-1186.  DOI: 10.1016/S1872-2067(12)60527-0
    Abstract ( 651 )   [Full Text(HTML)] () PDF (451KB) ( 680 )  

    Sequential reactions can provide efficient access to a variety of important organic compounds that would be otherwise difficult to obtain using conventional methods and readily available starting materials. Based on the importance of 2-alkynoates in organic synthesis, the current research aimed to develop a method for the convenient synthesis of functionalized 2-alkynoates from terminal alkynes, CO2, terminal alkene-derived bromides, and methyl acrylate using a combination of the carboxylative coupling and cross-metathesis reactions. The initial ligand-free silver-catalyzed carboxylative coupling reactions of a variety of different aryl-substituted terminal alkynes and CO2 with 5-bromopentene and 6-bromohexene provided a series of 4-pentenyl 2-alkynoates and 5-hexenyl 2-alkynoates, respectively, in good yield. These resulting 2-alkynoates were further transformed into methyl (E)-6-acetylenecarboxy-2-hexenoates and (E)-7-acetylenecarboxy-2-heptenoates in moderate to good yields by their cross-metathesis reactions with methyl acrylate in the presence of the Grubbs-Hoveyda catalyst. All of the new products characterized spectroscopically.

    Hydroxyalkylation of indole with cyclic carbonates catalyzed by ionic liquids
    GAO Guohua, ZHANG Lifeng, WANG Binshen
    2013, 34 (6):  1187-1191.  DOI: 10.1016/S1872-2067(12)60571-3
    Abstract ( 541 )   [Full Text(HTML)] () PDF (397KB) ( 860 )  

    A simple and eco-friendly procedure has been developed for the synthesis of hydroxyalkyl indoles from indole and cyclic carbonates in the presence of a catalytic amount of imidazolium based ionic liquids under solvent-free conditions. The effects of reaction time, the catalyst amount, temperature, and the ratio of the reactants were investigated to develop the optimum conditions for the transformation. Under the optimized reaction conditions, indole reacted with ethylene carbonate or propylene carbonate to give 1-(2-hydroxyethyl)indole or 1-(2-hydroxypropyl)indole, as well as the corresponding sequential derivatives, in high yields. The catalytic activity of the ionic liquids was affected by the anions of the ionic liquids in the order of BF4- < Br- < Cl- < OAc-, which was consistent with the hydrogen bond basicity of the anions of the ionic liquids.

    Pd nanoparticles confined in fluoro-functionalized yolk-shell-structured silica for olefin hydrogenation in water
    LI Xiaofei, ZHANG Wenjuan, ZHANG Limin, YANG Hengquan
    2013, 34 (6):  1192-1200.  DOI: 10.1016/S1872-2067(12)60561-0
    Abstract ( 663 )   [Full Text(HTML)] () PDF (820KB) ( 763 )  

    Pd nanoparticles were confined in yolk-shell mesoporous silica via encapsulation, etching and modification, producing a functionalized yolk-shell-structured catalyst. This catalyst was characterized using X-ray diffraction analysis, transmission electron microscopy, N2 adsorption-desorption, and thermogravimetric analysis. The catalyst had high activity for olefin hydrogenation in water, higher than that of the unmodified counterpart. The catalyst can be recovered through centrifugation, and its activity is not significantly decreased after several reaction cycles.

    Effect of H2S pre-treatment on structure and activity of Ni2P/SiO2 catalyst for hydrodechlorination of chlorobenzene
    YANG Qing, DAI Jicai, LI Kelun, CHEN Jixiang
    2013, 34 (6):  1201-1207.  DOI: 10.1016/S1872-2067(12)60595-6
    Abstract ( 498 )   [Full Text(HTML)] () PDF (670KB) ( 750 )  

    The effect of 10% H2S/H2 treatment on the structure of Ni2P/SiO2 and its activity for the hydrodechlorination of chlorobenzene was investigated using X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, CO chemisorption, H2 temperature-programmed desorption, NH3 temperature-programmed desorption, and activity tests. The H2S/H2 treatment did not change the Ni2P phase or crystallite size even at temperatures as high as 873 K. However, S species were incorporated in the surface of the Ni2P crystallites to form surface phosphosulfide (NiPxSy) species, which blocked the Ni sites and induced their further electron-deficiency. H2S/H2 treatment also led to an increase of spilt-over hydrogen species. The treated Ni2P/SiO2 catalyst had higher turnover frequencies in the hydrodechlorination of chlorobenzene than the untreated catalyst. This was ascribed to the increased electron-deficiency of Ni site and a greater amount of spilt-over hydrogen species.

    Rapid nonenzymatic monitoring of glucose and fructose using a CuO/multiwalled carbon nanotube nanocomposite-modified glassy carbon electrode
    Hajar SHEKARCHIZADEH, Mahdi KADIVAR, Ali A. ENSAFI
    2013, 34 (6):  1208-1215.  DOI: 10.1016/S1872-2067(12)60586-5
    Abstract ( 459 )   [Full Text(HTML)] () PDF (546KB) ( 830 )  

    A nonenzymatic electrochemical sensor for glucose and fructose was fabricated that contained a glassy carbon electrode modified with a copper oxide (CuO)/multiwalled carbon nanotube (MWCNT) nanocomposite. The electrochemical properties of the CuO/MWCNT-modified glassy carbon electrode were investigated. Two distinguishable anodic peaks were observed around 0.30 and 0.44 V corresponding to the oxidation of glucose and fructose, respectively, at the surface of the modified electrode. The detection limits for glucose and fructose were both 0.04 mmol/L. The sensor was used to simultaneously determine the concentrations of glucose and fructose in hydrolyzed sucrose samples, and to measure glucose in blood serum samples, demonstrating its potential as a nonenzymatic carbohydrate sensor.

    A novel approach for the preparation of phase-tunable TiO2 nanocomposite crystals with superior visible-light-driven photocatalytic activity
    YU Fuhai, WANG Junhu, ZHAO Kunfeng, YIN Jie, JIN Changzi, LIU Xin
    2013, 34 (6):  1216-1223.  DOI: 10.1016/S1872-2067(12)60574-9
    Abstract ( 604 )   [Full Text(HTML)] () PDF (765KB) ( 658 )  

    A series of novel TiO2 nanocomposite crystals with superior visible-light-driven photocatalytic activity were successfully prepared using a soft chemical solution process involving direct reaction of aqueous H2O2 with a 2-ethoxyethanol solution of tetraisopropyl titanate before calcination of the resulting peroxo-titanium complexes at 500℃ for 4 h. The synthesized TiO2 samples are composed of anatase and rutile phases, and the ratio of rutile could be continuously tuned from 0 to 96% by altering the 2-ethoxyethanol volume. There are clear red-shifts in the UV-Vis absorption spectra and apparent band gap narrowing for the synthesized TiO2 in comparison with Evonik P-25. The synthesized TiO2 samples are found to be much more efficient for methylene blue degradation under visible-light irradiation. The optimized sample (2-ethoxyethanol: 5 ml; rutile in bulk: 46%) exhibits 5-fold higher adsorption capacity and 3-fold higher photocatalytic activity than those of Evonik P-25 (λ ≥ 400 nm). Characterizations including X-ray diffraction and Raman spectroscopy reveal that the surface of the optimized TiO2 sample only contains a small quantity of rutile. It is concluded that the surface phase composition and distribution of the TiO2 nanocomposite crystals are essential to their greatly enhanced photocatalytic activities and strong adsorption capacities. In addition, the concentration of defects existing in the synthesized TiO2 is also regarded to account for these enhanced properties.

    Comparison of the salt-induced activation of Pseudomonas cepacia lipase in organic media by phosphate buffer and sodium sulfate
    JIN Qianru, JIA Guoqing, WANG Xiuli, LI Can
    2013, 34 (6):  1224-1231.  DOI: 10.1016/S1872-2067(12)60558-0
    Abstract ( 517 )   [Full Text(HTML)] () PDF (877KB) ( 566 )  

    The effects of a kosmotropic phosphate buffer (PB) or sodium sulfate (SS) on the enzymatic activity of crude Pseudomonas cepacia lipase (PCL) in organic media were explored. Previously, it was believed that SS acts as an effective enzyme activator, and PB was only used to adjust the solution pH. The present work showed PB-induced activation of PCL in the transesterification activity, where an increase of nearly 10-fold was achieved by carefully controlling the lyophilization condition. This activation, which gave about one-half of the native catalytic efficiency of PCL in aqueous media, was even more effective than the SS-induced activation. Thermogravimetric analysis of PCL preparations showed that different local environments surrounded PCL due to the presence of PB or SS. The local polarity of PCL preparations suspended in n-hexane was investigated by fluorescence spectroscopy using 2-(4’-amino-2’-hydroxy phenyl)benzoxazole as the probe. SS-incorporated PCL showed a much stronger local polarity than PB-incorporated and salt-free PCL. A correlation was found between the transesterification activity and local polarity of the enzyme preparation as a function of salt content. The data confirmed that the salt-induced activation of PCL in organic media can be attributed in part to the polar environment constituted by the salt-bonded water surrounding the PCL.

    Synthesis and catalytic oxidation performance of Al-TS-1
    SHEN Lu, DENG Xiujuan, LIU Yueming
    2013, 34 (6):  1232-1241.  DOI: 10.1016/S1872-2067(12)60553-1
    Abstract ( 456 )   [Full Text(HTML)] () PDF (913KB) ( 631 )  

    The preparation of titanium silicalite-1 (TS-1) containing Al (Al-TS-1) and its catalytic oxidation properties were investigated systematically. The features of Al-TS-1 were characterized using X-ray diffraction, ultraviolet-visible spectroscopy, inductively coupled plasma atomic emission spectroscopy, 27Al magic-angle spinning and 29Si magic-angle spinning nuclear magnetic resonance spectroscopies, and scanning electron microscopy. The results showed that incorporation of Al into the TS-1 framework influences the amount of framework Ti in Al-TS-1. However, when the Al/Si ratio is lower than 0.005, the amount of framework Ti in Al-TS-1 is hardly affected. Neither the Al centers nor the Ti centers in the Al-TS-1 framework influence the acidic catalytic and catalytic oxidation performance. Al in the Al-TS-1 framework suppressed desilication of silica species adjacent to framework Ti species in Al-TS-1 in a basic catalytic system, so Ti active sites in the Al-TS-1 framework could be protected.

    Synthesis of three-dimensionally ordered macroporous LaFeO3 perovskites and their performance for chemical-looping reforming of methane
    HE Fang, ZHAO Kun, HUANG Zhen, LI Xin’ai, WEI Guoqiang, LI Haibin
    2013, 34 (6):  1242-1249.  DOI: 10.1016/S1872-2067(12)60563-4
    Abstract ( 741 )   [Full Text(HTML)] () PDF (1194KB) ( 1357 )  

    Three-dimensionally ordered macroporous (3DOM) LaFeO3 perovskite-type oxides were synthesized using a polystyrene colloidal crystal templating method. The obtained 3DOM LaFeO3 was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The reactivity of the perovskite-type oxides was evaluated using temperature-programmed reduction and multicyclic redox reactions by exposing them to an alternating methane and air atmosphere. The methane oxidation performance of the oxides was investigated in a fixed-bed reactor. The effect of the self-assembly method on the structure of the polystyrene template was also studied. A vertical deposition method yielded a more uniform and orderly polystyrene template than those obtained by centrifugation and evaporation techniques. The solvent and concentration of the precursor solution were the major factors to affect the prepared 3DOM perovskite. SEM analysis showed that samples synthesized with ethanol precursor solvent exhibited a better 3DOM structure than those produced with ethylene glycol, and that 1.0 mol/L may be an optimal precursor solution concentration. XRD and FTIR results suggested that the obtained 3DOM LaFeO3 was pure crystalline perovskite. Two kinds of oxygen species were found to exist on the 3DOM perovskites: surface adsorbed oxygen and bulk lattice oxygen. The surface oxygen contributed to the complete oxidization of methane to CO2 and H2O because of its higher reactivity, while the bulk lattice oxygen tended towards partial methane oxidation to H2 and CO. The available oxygen in the 3DOM LaFeO3 was higher than that of the same mass of non-3DOM LaFeO3 during the partial oxidation of methane. Methane was partially oxidized into syngas with a H2/CO ratio of around 2:1 in a wide time range of the reactions. The generated H2/CO = 2 syngas was suitable for subsequent gas-to-liquids processes, such as Fischer-Tropsch and/or methanol synthesis.

    Ultrasonic fabrication of N-doped TiO2 nanocrystals with mesoporous structure and enhanced visible light photocatalytic activity
    ZHOU Wanqin, YU Changlin, FAN Qizhe, WEI Longfu, CHEN Jianchai, YU Jimmy C
    2013, 34 (6):  1250-1255.  DOI: 10.1016/S1872-2067(12)60578-6
    Abstract ( 540 )   [Full Text(HTML)] () PDF (677KB) ( 680 )  

    An ultrasonic method was developed to fabricate novel mesoporous TiO2 nanocrystals doped with a high concentration of N (N/TiO2). The nanocrystals were characterized by physicochemical methods including N2 physical adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic degradation of dimethyl phthalate, a hazardous chemical in water, by the prepared N/TiO2 nanocrystals under visible light irradiation (400?660 nm) was investigated. The results show that N-doping efficiency under ultrasonic irradiation is 3.2 times higher than under typical conditions, and the produced TiO2 nanocrystals have mesoporous structure. N/TiO2 fabricated under ultrasound exhibited much higher efficiency for the degradation of dimethyl phthalate than that prepared under typical conditions. The high photocatalytic degradation activity of N/TiO2 fabricated under ultrasound is mainly attributed to its high N content effectively increasing its ability to absorb visible light.

    Visible-light-responsive carbon-embedded photocatalyst coupled with plug-flow reactor for decomposition of vaporous aromatics
    Ho-Hwan CHUN, Wan-Kuen JO
    2013, 34 (6):  1256-1261.  DOI: 10.1016/S1872-2067(12)60549-X
    Abstract ( 539 )   [Full Text(HTML)] () PDF (483KB) ( 548 )  

    A plug-flow reactor coated with carbon-doped TiO2 (C-TiO2) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o-xylene (BTEX)) under a range of experimental conditions. The characteristics of the as-prepared C-TiO2 and a reference Degussa P25 TiO2 powder were examined using X-ray diffraction, scanning electron microscopy, diffuse-reflectance ultraviolet-visible-near infrared spectroscopy, and Fourier transform infrared spectroscopy. The experimental conditions for the photocatalytic performance of the as-prepared C-TiO2 photocatalyst were controlled using three operational parameters, relative humidity, flow rate, and input concentration. Unlike other target compounds, very little benzene was removed by the C-TiO2 photocatalyst under visible-light irradiation. In contrast, the C-TiO2 exhibited higher removal efficiencies for the other three target compounds (toluene, ethylbenzene, and xylene) compared with those achieved using unmodified TiO2 under visible-light irradiation. The highest removal efficiency was obtained at a relative humidity value of 45%. Specifically, the toluene removal efficiency determined at a relative humidity of 45% was 78%, whereas it was close to 0%, 7.2%, and 5.5% for relative humidity values of 20%, 70%, and 95%, respectively. In addition, the removal efficiencies for the three target compounds decreased as the flow rate or input concentration increased. These findings indicate that the as-prepared C-TiO2 photocatalyst could be used for the removal of toxic vaporous aromatics under optimized operating conditions.

    Catalytic conversion of n-butane over Au-Zn-modified nano-sized HZSM-5
    AI SHA種u La Hong, LIU Jiaxu, HE Ning, GUO Hongchen
    2013, 34 (6):  1262-1266.  DOI: 10.1016/S1872-2067(12)60539-7
    Abstract ( 593 )   [Full Text(HTML)] () PDF (562KB) ( 889 )  

    An Au-Zn-modified HZSM-5 catalyst was prepared using deposition-precipitation and wet impregnation methods. To obtain a better understanding of the relationship between catalyst characteristics and catalytic performance, a thorough study of various catalyst samples (HZSM-5, Au/HZSM-5, Zn/HZSM-5, and Au-Zn/HZSM-5) was performed. The interactions between Au and Zn species in Au-Zn/HZSM-5 were determined using ultraviolet-visible and X-ray photoelectron spectroscopies. Compared with Zn/HZSM-5, the introduction of Au to give Au-Zn/HZSM-5 effectively promotes the dehydrogenation and aromatization of n-butane, and also suppresses hydrogenolysis over Zn species. The n-butane conversion (70.8%) and selectivity for olefins and aromatics (61.98%) increased significantly. The dry gas selectivity also decreased significantly to 28.4%. Au-Zn-containing HZSM-5 is a useful catalyst for the conversion of light alkanes.

    Synthesis and characterization of P-doped TiO2 thin-films for photocatalytic degradation of butyl benzyl phthalate under visible-light irradiation
    R. M. Mohamed, E. Aazam
    2013, 34 (6):  1267-1273.  DOI: 10.1016/S1872-2067(12)60572-5
    Abstract ( 571 )   [Full Text(HTML)] () PDF (490KB) ( 1105 )  

    P-doped TiO2 (PTIO) thin-films with different P contents were prepared using a sol-gel method. The thin-film samples were characterized using various techniques. The photocatalytic activity was evaluated by decomposing butyl benzyl phthalate under visible-light irradiation. The results showed that the transformation of anatase to the rutile phase was inhibited and grain growth of TiO2 was prevented by P doping. The results confirm that the doped P atoms existed in two chemical forms, and those incorporated in the TiO2 lattice may play a positive role in photocatalysis. The high photocatalytic activities of the PTIO thin-films may be the result of extrinsic absorption through the creation of oxygen vacancies, rather than excitation of the intrinsic absorption band of bulk TiO2. The PTIO can be recycled with little depression of the photocatalytic activity. After six cycles, the photocatalytic activity of the PTIO film was still higher than 98%.