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Chinese Journal of Catalysis
2013, Vol. 34, No. 8
Online: 16 August 2013


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Li and coworkers in their Article on pages 1489–1495 reported a series of mononuclear Ru complexes based on the bipyridine-dicarboxylate ligand with different substituents on the para-position of the pyridine ligand as water oxidation catalysts and their catalytic activity towards both chemical and photochemical water oxidation. The more electron-withdrawing substituents on the axial ligands of the catalysts lead to higher activity towards water oxidation.

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Table of Contents for Vol. 34 No. 8 2013, 34 (8):  0-0.  Abstract ( 192 )   PDF (18750KB) ( 373 )

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Pt nanowire electrocatalysts for proton exchange membrane fuel cells Zeyu Yan, Bing Li, Daijun Yang, Jianxin Ma 2013, 34 (8):  1471-1481.  DOI: 10.1016/S1872-2067(12)60629-9 Abstract ( 673 )   [Full Text(HTML)] () PDF (987KB) ( 865 )   The proton exchange membrane fuel cell (PEMFC) directly converts chemical energy into electricity with a high energy conversion rate, environmental friendliness, and the ability to start working quickly. The key material that determines the performance, lifetime, and cost of the PEMFC is the electrocatalyst, but the Pt catalyst used is very expensive, which is the major factor limiting the commercial use of the PEMFC. The Pt nanowire catalyst has demonstrated good performance in improving the utilization ratio of Pt, electrochemical activity, CO tolerance, and durability. This article reviewed the preparation and characterization of the Pt nanowire catalyst and its electrochemical activity.

Communications

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Selective hydrogenation of benzene to cyclohexene in continuous reaction device with two reaction reactors in serie over Ru-Co-B/ZrO2 catalysts Haijie Sun, Shuaihui Li, Yuanxin Zhang, Houbing Jiang, Lianglong Qu, Shouchang Liu, Zhongyi Liu 2013, 34 (8):  1482-1488.  DOI: 10.1016/S1872-2067(12)60637-8 Abstract ( 488 )   [Full Text(HTML)] () PDF (519KB) ( 768 )   A Ru-B/ZrO2 catalyst for selective hydrogenation of benzene to cyclohexene was prepared using a chemical reduction method. The effects of transition metals such as Cr, Mn, Fe, Co, Ni, Cu, and Zn on the performance of the Ru-B/ZrO2 catalyst were investigated. It was found that the addition of these transition metals all increased the B content of the Ru-B/ZrO2 catalyst. The modification of B, the ensemble effect, and the ligand effect of the second metal or metal oxide resulted in a decrease in the activity and an increase in the selectivity for cyclohexene of the Ru-B/ZrO2 catalyst. When the atomic ratio of Co/Ru was 0.06, the Ru-Co-B/ZrO2 catalyst gave a selectivity for cyclohexene of 82.8% and a cyclohexene yield of 62.8% at a benzene conversion of 75.8% at 25 min. Moreover, the benzene conversion was stable at around 40%, and the selectivity for cyclohexene and the cyclohexene yields stabilized at around 73% and 30%, respectively, in 419 h under the optimum reaction conditions in a continuous device with two reactors in series.

Articles

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Chemical and photocatalytic water oxidation by mononuclear Ru catalysts Yi Jiang, Fei Li, Fang Huang, Biaobiao Zhang, Licheng Sun 2013, 34 (8):  1489-1495.  DOI: 10.1016/S1872-2067(12)60600-7 Abstract ( 652 )   [Full Text(HTML)] () PDF (1083KB) ( 995 )   Four mononuclear Ru complexes with different substituents on the para position of the pyridine ligand of Ru(bda)(pic)2 (H2bda=2,2'-bipyridine-6,6'-dicarboxylic acid; pic=picoline) were synthesized and characterized by 1H nuclear magnetic resonance or X-ray crystallography. The electrochemical properties of this series of compounds in acidic and neutral conditions were studied by cyclic voltammetry. Their catalytic activity towards water oxidation was investigated using a chemical oxidant ([Ce(NH4)2(NO3)6] (CeIV) in acidic solution, or driven by visible light in a three-component system containing a photosensitizer ([Ru(bpy)3]2+) and an electron acceptor (S2O82-). For the chemical water oxidation, complex 1 was found to be the most effective, exhibiting a turnover number (TON) of up to 4000. The pyridine substituent at the 4-position in 1 may be protonated giving an intensive electron-withdrawing effect. Complex 2 bears the most electron-withdrawing trifluoromethyl group under neutral conditions and showed the highest photocatalytic activity with a TON of 270 over 2 h. It was concluded that the more electron-withdrawing substituents led to higher activity towards oxygen evolution for this type of Ru catalysts in the oxidation of water.

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Coking on micrometer- and nanometer-sized mordenite during dimethyl ether carbonylation to methyl acetate Huifu Xue, Xiumin Huang, Evert Ditzel, Ensheng Zhan, Meng Ma, Wenjie Shen 2013, 34 (8):  1496-1503.  DOI: 10.1016/S1872-2067(12)60607-X Abstract ( 669 )   [Full Text(HTML)] () PDF (731KB) ( 896 )   As compared to conventional micrometer-sized mordenite particles, nanometer-sized mordenite gave a much higher activity and better stability in dimethyl ether carbonylation to methyl acetate by suppressing the deposition of hard coke. A structural analysis revealed that intra-crystalline diffusion limitation of the reactants and products to and from the active sites inside the channels was greatly decreased by reducing the zeolite size to the nanometer size.

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Synthesis and catalytic cracking performance of Fe/Ti-ZSM-5 zeolite from attapulgite mineral Xiaozhao Zhou, Yan Liu, Xiangju Meng, Baojian Shen, Feng-Shou Xiao 2013, 34 (8):  1504-1512.  DOI: 10.1016/S1872-2067(12)60638-X Abstract ( 430 )   [Full Text(HTML)] () PDF (975KB) ( 929 )   Fe/Ti-ZSM-5 zeolite was synthesized successfully from treated attapulgite (ATP). This mineral consists of amorphous silica containing Fe and Ti species. X-ray diffraction patterns, scanning electron microscopy images, and nitrogen sorption isotherms indicate that the sample has a typical MFI structure, high crystallinity, and large specific surface area. Temperature-programmed desorption of ammonia and H2 temperature-programmed reduction indicates that the Fe/Ti-ZSM-5 zeolite is strongly acidic and has superior redox properties. More importantly, compared with conventional ZSM-5 zeolite, Fe/Ti-ZSM-5 performs well, resulting in an increase in yield of 0.21% propylene and 0.33% total light olefins in the catalytic cracking of Canadian LGO (light gas oil). These results suggest that the presence of Fe and Ti species in ZSM-5 zeolite is favorable for enhancing light olefin yields, which is potentially important for oil refining in the future.

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Magnetically recoverable, nanoscale-supported heteropoly acid catalyst for green synthesis of biologically active compounds in water Ezzat Rafiee, Sara Eavani, Maryam Khodayari 2013, 34 (8):  1513-1518.  DOI: 10.1016/S1872-2067(12)60645-7 Abstract ( 412 )   [Full Text(HTML)] () PDF (464KB) ( 920 )   12-Tungstophosphoric acid supported on aerosil silica and silica-coated γ-Fe2O3 nanoparticles was prepared and characterized using transmission electron microscopy, scanning electron microscopy, and inductively coupled plasma atomic emission spectroscopy. The catalytic activity of the two prepared catalysts was compared in the synthesis of 1,8-dioxo-9,10- diaryldecahydroacridines in water. 12-Tungstophosphoric acid was highly dispersed on the silica-coated γ-Fe2O3 nanoparticles and showed higher activity and a higher reuse number compared with the acid supported on aerosil silica. The catalyst could be recovered simply by using an external magnetic field and could be reused several times without appreciable loss of its catalytic activity.

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Immobilization of highly active Pd nano-catalysts on functionalized mesoporous silica supports using mercapto groups as anchoring sites and their catalytic performance for phenol hydrogenation Jiaxi Zhang, Gaowei Huang, Cheng Zhang, Qunhua He, Chao Huang, Xu Yang, Huiyu Song, Zhenxing Liang, Li Du, Shijun Liao 2013, 34 (8):  1519-1526.  DOI: 10.1016/S1872-2067(12)60603-2 Abstract ( 612 )   [Full Text(HTML)] () PDF (1036KB) ( 868 )   Highly active and highly dispersed Pd-loaded nano-catalysts using mercapto group (-SH) functionalized mesoporous silica supports, namely, Pd-SH-MCM-41 and Pd-SH-SBA-15, were prepared using an impregnation-reduction approach. The surface -SH groups are believed to facilitate the high distribution and immobilization of the Pd nanoparticles within the silica supports through an anchoring interaction. The catalysts featured long-range ordered structures, uniform pore size, high surface area, and highly dispersed Pd nanoparticles as characterized by X-ray diffraction, N2 adsorption-desorption, and transmission electron microscopy. The catalysts showed activity five times higher than that of commercial Pd/C catalyst and three times higher than those of Pd/MCM-41 and Pd/SBA-15 catalysts. Within 1 h of reaction at 80℃ and 1.0 MPa, the conversion of phenol attained was greater than 99%, and the selectivity for cyclohexanone was 98%.

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Enhanced visible light photocatalytic activity of Ag2S-graphene/TiO2 nanocomposites made by sonochemical synthesis Ze-Da Meng, Lei Zhu, Kefayat Ullah, Shu Ye, Qian Sun, Won-Chun Oh 2013, 34 (8):  1527-1533.  DOI: 10.1016/S1872-2067(12)60611-1 Abstract ( 508 )   [Full Text(HTML)] () PDF (1750KB) ( 770 )   Ag2S-graphene/TiO2 composites were synthesized by a facile sonochemical method. The products were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and UV-Vis diffuse reflectance spectrophotometry. During the synthesis reaction, the reduction of graphene oxide and loading of Ag2S and TiO2 particles were achieved. The Ag2S-graphene/TiO2 composites possessed a large adsorption capacity for dyes, an extended light absorption range, and efficient charge separation properties. Hence, in the photodegradation of rhodamine B, a significant enhancement in the reaction rate was observed with the Ag2S-graphene/TiO2 composites as compared to pure TiO2. The generation of reactive oxygen species was detected by the oxidation of 1,5-diphenyl carbazide to 1,5-diphenyl carbazone. The high activity was attributed to the synergetic effects of high charge mobility and the red shift in the absorption edge of the Ag2S-graphene/TiO2 composites.

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Effect of alumina support on catalytic performance of Pt-Sn/Al2O3 catalysts in one-step synthesis of N-phenylbenzylamine from aniline and benzyl alcohol Mengyao Yin, Songbo He, Zhengkun Yu, Kaikai Wu, Liandi Wang, Chenglin Sun 2013, 34 (8):  1534-1542.  DOI: 10.1016/S1872-2067(12)60608-1 Abstract ( 691 )   [Full Text(HTML)] () PDF (838KB) ( 811 )   The effect of alumina on the catalytic performance of Pt-Sn/Al2O3 catalysts in the green synthesis of secondary amines by N-alkylation of amines with alcohols based on the borrowing hydrogen strategy was investigated. N-alkylation of aniline with benzyl alcohol to produce N-phenylbenzylamine was used as a model reaction. Three different alumina supports were selected, and the corresponding catalysts were prepared by complex impregnation under vacuum. The supports and catalysts were characterized using N2 adsorption-desorption, mercury intrusion porosimetry, X-ray diffraction, transmission electron and scanning electron microscopies, CO chemisorption, H2 temperature-programmed reduction, and NH3 temperature-programmed desorption. The results show that the catalysts with small Pt particles that were highly dispersed on the alumina supports and interacted weakly with the supports had high catalytic activities. The large pore volumes and pore size distributions of the alumina supports helped diffusion and adsorption of the reactants on the catalyst surface and increased the catalytic activity; they also promoted removal of the products from the catalyst surface and enhanced the catalytic stability. However, strong acidity and acid distribution of the alumina supports decreased the selectivity for secondary amines and reduced the catalyst stability.

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Ru/Al2O3-ZrO2-NiO/cordierite monolithic catalysts for selective hydrogenation of benzene Minghao Wang, Hongjiu Su, Jin Zhou, Shudong Wang 2013, 34 (8):  1543-1550.  DOI: 10.1016/S1872-2067(12)60609-3 Abstract ( 497 )   [Full Text(HTML)] () PDF (1147KB) ( 805 )   Ru/Al2O3-ZrO2-NiO/cordierite catalysts with an egg-shell-like Ru distribution were prepared by conventional incipient wetness impregnation and ammonia gas absorption deposition. The performance of the catalysts in a modified monolithic fixed-bed reactor was evaluated. The catalysts exhibited good selectivity and stability. Importantly, a maximum yield of 24.7% was achieved at a low concentration of ZnSO4 (0.5 wt%). The catalysts were characterized by N2 adsorption, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, optical microscopy, and scanning electron microscopy/energy-dispersive X-ray analysis. The introduction of NiO resulted in the formation of NiAl2O4 phase during calcination at 1373 K, reducing the proportion of small pores. Meanwhile, the presence of ZrO2 enhanced the sintering resistance of the coating, and moderate surface area was retained after calcination. The egg-shell distribution of Ru, thin layer thickness indicating short diffusion length, small proportion of nanosized pores (e.g., 1-4 nm), moderate specific surface area, and narrow pore size distribution to facilitate Ru dispersion are thought to be important factors controlling the behavior of the present monolithic catalysts.

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Photocatalytic decomposition of perfluorooctanoic acid in pure water and wastewater by needle-like nanostructured gallium oxide Tian Shao, Pengyi Zhang, Zhenmin Li, Ling Jin 2013, 34 (8):  1551-1559.  DOI: 10.1016/S1872-2067(12)60612-3 Abstract ( 546 )   [Full Text(HTML)] () PDF (717KB) ( 732 )   Nanostructured β-Ga2O3 with a needle-like structure was synthesized by a polyvinyl alcohol (PVA)- assisted hydrothermal method and subsequent heat treatment. It has a high specific surface area (25.95 m2/g) and large number of nanopores (4-25 nm), and it exhibited good photocatalytic activity for perfluorooctanoic acid (PFOA) decomposition in pure water unde UV irradiation (λ=254 nm). PFOA had a half-life of 18.2 min, and the first order rate constant (2.28 h-1) for PFOA decomposition with the needle-like β-Ga2O3 was 7.5 and 16.8 times higher, respectively, than with commercial Ga2O3 and TiO2 (P25). In addition, in combination with vacuum UV (VUV) irradiation (λ=185 nm), the needle-like β-Ga2O3 showed high activity for the removal of trace PFOA in both pure water and wastewater, with first order rate constants of 4.03 and 3.51 h -1, respectively. The adverse effect that coexisting natural organic matters in wastewater have on the decomposition of PFOA was mostly eliminated with VUV irradiation, and the energy consumption in this method was much less than the values reported for other methods in the literature.

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Highly active and cis-1,4 selective polymerization of 1,3-butadiene catalyzed by cobalt(II) complexes bearing α-diimine ligands Xiangyu Jia, Heng Liu, Yanming Hu, Quanquan Dai, Jifu Bi, Chenxi Bai, Xuequan Zhang 2013, 34 (8):  1560-1569.  DOI: 10.1016/S1872-2067(12)60625-1 Abstract ( 629 )   [Full Text(HTML)] () PDF (701KB) ( 963 )   A series of cobalt(II) complexes bearing α-diimine ligands were synthesized and characterized by elemental and spectroscopic analysis. These complexes had the general formulas [ArN=C(Me)-(Me)C=NAr]CoCl2 (Ar=C6H5, 3a; 4-MeC6H4, 3b; 4-MeOC6H4, 3c; 4-FC6H4, 3d; 4-ClC6H4, 3e; 2-MeC6H4, 3f; 2-EtC6H4, 3g; 2-iPrC6H4, 3h; 2,4,6-Me3C6H2, 3i; 2,6-Et2C6H3, 3j; 2,6-iPrC6H3, 3k). 2,6-Bis[(2,6-diisopropylphenylimino)ethyl]pyridine CoCl2 (4a) was also synthesized for comparison. The structures of complexes 3i, 3k, and 4a were further analyzed by X-ray crystallography. When the Co(II) complexes were activated with ethylaluminum sesquichloride, they exhibited high catalytic activity for 1,3-butadiene polymerization. The polymers produced have high cis-1,4 stereoregularity (up to 98.0%) and high molecular weights (Mn=1×104-1×105). The substituent ligand affected both catalytic activity and stereoselectivity through an electronic effect while steric hindrance by the substituent was not important. The effects of the polymerization conditions, such as polymerization time, temperature, different alkylaluminum compounds used as cocatalyst, and [Al]/[Co] molar ratio, on polymerization behavior were investigated.

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Temperature-programmed desorption and surface reaction studies of CO on Co2C Yanpeng Pei, Yunjie Ding, Juan Zang, Xiangen Song, Wenda Dong, Hejun Zhu, Tao Wang, Weimiao Chen 2013, 34 (8):  1570-1575.  DOI: 10.1016/S1872-2067(12)60615-9 Abstract ( 515 )   [Full Text(HTML)] () PDF (570KB) ( 910 )   Cobalt carbide (Co2C) samples were prepared by carburizing Co with CO at 473 K for in excess of 400 h and were characterized by X-ray diffraction, transmission electron microscopy, CO temperature-programmed reduction, CO temperature-programmed desorption (CO-TPD), and CO temperature-programmed surface reaction. The prepared Co2C samples were composed of bulk Co2C with a surface CoO passivation layer. The passivation layer could be removed by reaction with CO at 477 K. CO desorbing at low temperature in CO-TPD experiments likely originated from chemisorbed CO. CO desorbing at high temperature was likely due to residual CO within the Co2C crystal lattice. CO adsorbed on Co2C reacted with H2 to form alcohol.

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Hierarchical mesoporous ZSM-5 for the dehydration of methanol to dimethyl ether Qi Yang, Haitao Zhang, Meng Kong, Xiuxiu Bao, Jinhua Fei, Xiaoming Zheng 2013, 34 (8):  1576-1582.  DOI: 10.1016/S1872-2067(12)60621-4 Abstract ( 548 )   [Full Text(HTML)] () PDF (801KB) ( 814 )   Hierarchical mesoporous ZSM-5 zeolites were synthesized using small organic cations of tetrapropylammonium and meso-sized cationic polymers of dimethyldiallyl ammonium chloride acrylamide copolymer as templates. The zeolites were used for the dehydration of methanol to dimethyl ether (DME). Characterization results showed that the basic MFI-type structure was still obtained after adding the cationic polymers, while their nitrogen isotherms exhibited a broad hysteresis loop at relative pressures higher than 0.4, which proved the presence of mesopores. The mesoporosity of the hierarchical mesoporous ZSM-5 can be adjusted simply by adding different amounts of the cationic polymer. Catalytic tests showed that the hierarchical mesoporous HZSM-5 zeolites exhibited better stability than conventional HZSM-5 and excellent DME selectivity. The activity for methanol dehydration strongly depended on the textural property and acidity of the catalyst.

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Preparation, characterization and catalytic activity of amphiphilic cyclopalladated aryl imines and their Langmuir-Blodgett films Na Zhao, Fei Wang, Meiling Zhou, Tiesheng Li, Hui Liu, Wenjian Xu, Yangjie Wu 2013, 34 (8):  1583-1588.  DOI: 10.1016/S1872-2067(12)60613-5 Abstract ( 468 )   [Full Text(HTML)] () PDF (496KB) ( 462 )   A series of novel amphiphilic cyclopalladated aryl imines were synthesized and characterized. These catalysts showed high activity for Heck and Suzuki reactions in homogeneous systems. Heterogeneous Langmuir-Blodgett films of the catalysts also demonstrated high catalytic activity for these coupling reactions.

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Molecularly imprinted polymer containing Fe(III) catalysts for specific substrate recognition Wenqing Sun, Rong Tan, Weiguo Zheng, Donghong Yin 2013, 34 (8):  1589-1598.  DOI: 10.1016/S1872-2067(12)60624-X Abstract ( 552 )   [Full Text(HTML)] () PDF (578KB) ( 555 )   A series of molecularly imprinted polymers (MIPs) containing equal amounts of iron(III) were prepared by the polymerization of acrylamide and ethylene dimethacrylate in the presence of the template of o-, m-, or p-nitrobenzyl alcohol (NBA) and a FeCl3 complex. The samples were characterized by scanning electron microscopy, N2 adsorption, and Fourier transform infrared spectroscopy. The catalysts exhibited high catalytic activity and unique substrate recognition in the oxidation of benzyl alcohol derivatives in water using 30% H2O2 as the oxidant. The conversion of p-NBA was 80% over the p-Fe(III)-MIP catalyst when the template molecule was p-NBA, which had a good fit with the substrate. However, the conversion of p-NBA was less than 58% over o-Fe(III)-MIP or m-Fe(III)-MIP due to the mismatch of the substrate with the cavities of the Fe(III)-MIP. The results indicated that the Fe(III)-MIP samples contained molecular recognizable shapes and sites in their cavities that match the corresponding substrate. The special recognizing cavities of the Fe(III)-MIP catalyst exhibited unique substrate recognition, and therefore the selectivity for the substrate was improved.

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Cation location and migration in lanthanum-exchanged NaY zeolite Xiaohui Du, Haitao Zhang, Xueli Li, Zhengguo Tan, Honghai Liu, Xionghou Gao 2013, 34 (8):  1599-1607.  DOI: 10.1016/S1872-2067(11)60622-6 Abstract ( 559 )   [Full Text(HTML)] () PDF (535KB) ( 959 )   LaNH4Y and LaY zeolites were prepared using a double-exchange double-calcination method by La exchange of NaY zeolite. The distribution of the La cations was determined by powder X-ray diffraction with Rietveld refinement. The results indicate that the La cations are initially located in supercages, and then their hydration shells are stripped off and they migrate to small sodalite structures located at SI′ during heating and dehydration. The changes in the T-O-T angles show significant distortion of the flexible framework and instability in LaNH4Y obtained using a one-exchange one-calcination process. For La cations located at SI′ and coordinated with O3, the T-O3 bond distance increased, which indicates that the rare-earth cations not only restrain framework dealumination, suppressing condensation of the unit cell, but also have an effect on the T-O3 bond distance, increasing the unit cell volume. The role of the rare-earth species is to ensure the hydrothermal stability of the zeolite in order to control the acid site density and catalytic activity. The effects of La cations and NH4+ cations on the zeolite acidity were studied using infrared spectroscopy and NH3 temperature-programmed desorption, and the mechanism of rare-earth stabilization of the Y zeolite is described.

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Synthesis of vitamin E succinate by interfacial activated Candida rugosa lipase encapsulated in sol-gel materials Yi Hu, Xiangjun Jiang, Suwen Wu, Ling Jiang, He Huang 2013, 34 (8):  1608-1616.  DOI: 10.1016/S1872-2067(12)60628-7 Abstract ( 478 )   [Full Text(HTML)] () PDF (510KB) ( 580 )   Vitamin E succinate was synthesized by interfacial activated Candida rugosa lipase (CRL) encapsulated in sol-gel materials. The effects of various immobilization parameters were investigated. The optimum conditions were found to consist of n-propyltrimethoxysilane/tetraethoxysilane molar ratio=1/1, water/silane molar ratio (R value)=20, lipase loading=0.5 mg/ml sol, and PEG400 loading=12 μl/ml sol. Compared with free enzymes, sol-gel encapsulated enzymes kept its activity of 70.58% and achieved 2.6-fold increased stability after 18 h incubation in phosphate buffer (0.025 mol/L, pH=7.0) at 50℃. Based on the interfacial characteristics of CRL, five kinds of surfactants were used for activation. The results demonstrate that olive oil was the most effective in activating CRL. The esterification activity of vitamin E succinate synthesis by interfacial activated CRL encapsulated in sol-gel materials reached up to 6.7-fold and 1.43-fold that of free enzyme and non-interfacial activated enzyme, respectively.

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Effect of sulfur doping on the photocatalytic performance of BiVO4 under visible light illumination Zhenxuan Zhao, Hongxing Dai, Jiguang Deng, Yuxi Liu, Chak Tong Au 2013, 34 (8):  1617-1626.  DOI: 10.1016/S1872-2067(12)60632-9 Abstract ( 476 )   [Full Text(HTML)] () PDF (1326KB) ( 996 )   Porous monoclinic bismuth vanadate (BiVO4-δ) and sulfur-doped bismuth vanadates (BiVO4-δS0.05, BiVO4-δS0.08, and BiVO4-δS0.12) were synthesized by a dodecylamine-assisted alcohol-hydrothermal route in the absence and presence of thiourea or Na2S. The physicochemical properties of the materials were characterized and their photocatalytic performance for the degradation of methylene blue and formaldehyde under visible light was evaluated. The samples have a single phase monoclinic scheetlite crystal structure with a porous olive-like morphology, surface areas of 8.4-12.5 m2/g, and bandgap energies of 2.40-2.48 eV. Surface Bi5+, Bi3+, V5+, and V4+ species were present on the S-doped BiVO4-δ samples. Sulfur doping influenced the surface Bi5+/Bi3+, V5+/V4+, and Oads/Olatt molar ratios, and the amount of sulfur doped had an important effect on the photocatalytic performance. Under visible light, BiVO4-δS0.08 performed the best in the photodegradation of methylene blue and formaldehyde. A higher surface oxygen species concentration and a lower bandgap energy were responsible for the excellent visible light photocatalytic performance of BiVO4-δS0.08.

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Biomimetic preparation of organic-inorganic composite microcapsules for glucose oxidase immobilization Qian Xin, Yanjun Jiang, Jing Gao, Liya Zhou, Li Ma, Ying He, Fei Jia 2013, 34 (8):  1627-1633.  DOI: 10.1016/S1872-2067(12)60635-4 Abstract ( 430 )   [Full Text(HTML)] () PDF (777KB) ( 717 )   Organic-inorganic composite microcapsules made of sodium poly(styrenesulfonate) (PSS), poly(dimethyl diallyl ammonium chloride) (PDADMAC), and biomimetic silica were successfully fabricated via a combination of layer-by-layer self-assembly and biomimetic mineralization. The morphologies and chemical compositions of the microcapsules (denoted by (PSS/PDADMAC)2-SiO2) were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The composite microcapsules were used as carrier for the immobilization of glucose oxidase (GOD). GOD encapsulated in (PSS/PDADMAC)2-SiO2 (denoted by GOD@(PSS/PDADMAC)2-SiO2) displayed improved thermal, pH, and operational stabilities. The activity recovery of the immobilized GOD reached 72.85% under the optimized conditions. GOD@(PSS/PDADMAC)2-SiO2 showed a 2.21-fold increase in the Michaelis constant (Km) compared with free GOD. The composite microcapsules have the potential for a range of applications in chemical/biological catalysis and drug/gene delivery systems, and as biosensors.