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2014, Vol. 23, No. 2　Online: 2014-02-20


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Hou and coworkers in their Article on pages 136–144 reported H+/nanosheets and H⁺/nanoscrolls derived from K₄Nb₆O₁₇ with increased surface areas have a high adsorption capacity and a rapid visible-light response for the photodegradation of RhB. The materials can be easily prepared with low-cost and so, they could have a promising potential in the visible-light driven degradation of dyes to substitute for TiO₂.

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Nitrogen doped carbon catalyzing acetylene conversion to vinyl chloride Xingyun Li, Xiulian Pan, Xinhe Bao 2014, 23(2): 131-135.  DOI: 10.1016/S2095-4956(14)60126-1 摘要 ( 7804 )   Commercial production of vinyl chloride from acetylene relies on the use of HgCl2 as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL·min-1·g-1 and 200℃. It delivers a stable performance within a test period of 100 h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.

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A comparison of H+-restacked nanosheets and nanoscrolls derived from K4Nb6O17 for visible-light degradation of dyes Chenhui Hu, Lihong Zhang, Liyuan Cheng, Jing Chen, Wenhua Hou, Weiping Ding 2014, 23(2): 136-144.  DOI: 10.1016/S2095-4956(14)60128-5 摘要 ( 7549 )   H+-restacked nanosheets and nanoscrolls peeled from K4Nb6O17 display different structures and surface characters. The two restacked samples with increased surface areas have an amazing visible-light response for the photodegradation of dyes, which is superior to commercial TiO2 (P25) and Nb2O5. By comparison, H+/nanosheets have a relatively faster photodegradation rate originated from large and smooth basal plane. The work reveals that dye adsorbed on the unfolded nanosheets can effectively harvest sunlight. Due to facile preparation, low-cost and high photocatalytic efficiency, H+/nanosheets and H+/nanoscrolls might be used for the visible light-driven degradation of organic dyes as a substitute for TiO2 in industry.

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Nanocomposites of graphene-CdS as photoactive and reusable catalysts for visible-light-induced selective reduction process Siqi Liu, Min-Quan Yang, Nan Zhang, Yi-Jun Xu 2014, 23(2): 145-155.  DOI: 10.1016/S2095-4956(14)60129-7 摘要 ( 7271 )   Graphene (GR)-CdS nanocomposites with different weight addition ratios of GR have been assembled by a facile solvothermal treatment. The GR-CdS nanocomposite photocatalyst with an appropriate ratio of GR exhibits enhanced photoactivity for selective reduction of aromatic nitro compounds to the corresponding aromatic amines in water under visible light irradiation as compared with blank-CdS. The characterization of GR-CdS nanocomposite photocatalysts by a collection of techniques discloses that: i) GR can tune the microscopic morphology of CdS nanoparticles and improve light absorption intensity in the visible light region; ii) GR scaffolds act as an electron reservoir to trap and shuttle the electrons photogenerated from CdS semiconductor under the visible light illumination; iii) the introduction of GR enhances the adsorption capacity of GR-CdS nanocomposites toward the substrates, aromatic nitro compounds. The synergistic effect of these factors should account for the photoactivity advancement of GR-CdS nanocomposites toward the probe reactions. Furthermore, because the photogenerated holes in the system are trapped by the quenching agent ammonium oxalate, the as-obtained GR-CdS photocatalyst is stable during the photocatalytic reduction reactions. A reasonable model has also been proposed to illustrate the reaction mechanism.

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Sulfonated carbon materials with hydrophilic and lipophilic properties Yupei Zhao, Hui Chen, Yu'an Huang, Yu Zhao, Yuchuan Fu, Jianyi Shen 2014, 23(2): 156-163.  DOI: 10.1016/S2095-4956(14)60130-3 摘要 ( 7684 )   Two acidic carbon materials (H-PRC and HS-C) were used as catalysts for the condensation reaction of methanol with formaldehyde to produce dimethoxymethane (DMM) in aqueous solution (hydrophilic system) and for the etherification of isopentene with methanol to produce tert amyl methyl ether (TAME) in toluene solution (lipophilic system). Microcalorimetric adsorptions of water and benzene showed that the HS-C was highly hydrophilic without the lipophilicity, while the H-PRC exhibited both the hydrophilicity and lipophilicity. Thus, the HS-C was well dispersed in aqueous solution and difficult to separate from it. On the other hand, the H-PRC was highly active, more active than the acidic resin (D008) and sulfuric acid, for the synthesis of DMM in aqueous solution. The H-PRC was also highly active, more active than the HS-C, for the etherification of isopentene with methanol to produce TAME in toluene solution, probably owing to its amphiphilic surface property as well as its strong surface acidity as measured by the microcalorimetric adsorption of NH3.

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Oxygen permeation and phase structure properties of partially A-site substituted BaCo0.7Fe0.225Ta0.075O3-δ perovskites Bo Jiang, Hongwei Cheng, Longfei Luo, Xionggang Lu, Naijun Zhang, Jizhong Liu 2014, 23(2): 164-170.  DOI: 10.1016/S2095-4956(14)60131-5 摘要 ( 7968 )   Ba0.9R0.1Co0.7Fe0.225Ta0.075O3-δ (BRCFT, R=Ca, La or Sr) membranes were synthesized by a solid-state reaction. Metal cation Ca2+, La3+ or Sr2+ doping on A-site partially substituted Ba2+ in BaCo0.7Fe0.225Ta0.075O3-δ oxides, and its subsequent effects on phase structure stability, oxygen permeability and oxygen desorption were systematically investigated by XRD, TG-DSC, H2-TPR, O2-TPD techniques and oxygen permeation experiments. The partial substitution with Ca2+, La3+ or Sr2+, whose ionic radii are smaller than that of Ba2+, succeeded in stabilizing the cubic perovskite structure without formation of impurity phases, as revealed by XRD analysis. Oxygen-involving experiments showed that BRCFT with A-site fully occupied by Ba2+ exhibited good oxygen permeation flux under He flow, reaching about 2.3 mL·min-1·cm-2 at 900℃ with 1 mm thickness. Of all the membranes, BLCFT membrane showed better chemical stability in CO2, owing to the reduction in alkalinity of the mixed conductor oxide by La doping. In addition, we also found the stability of the perovskite structure under reducing atmospheres was strengthened by increasing the size of A-site cation (Ba2+>La3+>Sr2+>Ca2+).

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Synthesis of a new ordered mesoporous NiMoO4 complex oxide and its efficient catalytic performance for oxidative dehydrogenation of propane Xiaoqiang Fan, Jianmei Li, Zhen Zhao, Yuechang Wei, Jian Liu, Aijun Duan, Guiyuan Jiang 2014, 23(2): 171-178.  DOI: 10.1016/S2095-4956(14)60132-7 摘要 ( 7669 )   Highly ordered mesoporous NiMoO4 material was successfully synthesized using mesoporous silica KIT-6 as hard template via vacuum nanocasting method. The structure was characterized by means of XRD, TEM, N2 adsorption-desorption, Raman and FT-IR. The mesoporous NiMoO4 with the coexistence of α-NiMoO4 and β-NiMoO4 showed well-ordered mesoporous structure, a bimodal pore size distribution and crystalline framework. The catalytic performance of NiMoO4 was investigated for oxidative dehydrogenation of propane. It is demonstrated that the mesoporous NiMoO4 catalyst with more surface active oxygen species showed better catalytic performance in oxidative dehydrogenation of propane in comparison with bulk NiMoO4.

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Facile deposition of cobalt oxide based electrocatalyst on low-cost and tin-free electrode for water splitting Ali Han, Pingwu Du 2014, 23(2): 179-184.  DOI: 10.1016/S2095-4956(14)60133-9 摘要 ( 7836 )   Facile deposition of a water-splitting catalyst on low-cost electrode materials could be attractive for hydrogen production from water and solar energy conversion. Herein we describe fast electrodeposition of cobalt-based water oxidation catalyst (Co-WOC) on simple graphite electrode for water splitting. The deposition process is quite fast, which reaches a plateau in less than 75 min and the final current density is ～1.8 mA/cm2 under the applied potential of 1.31 V at pH=7.0. The scanning electron microscopy (SEM) study shows the formation of nanometer-sized particles (10-100 nm) on the surface of the electrode after only 2 min and micrometer-sized particles (2-5 μm) after 90 min of electrolysis. X-ray photoelectron spectroscopy (XPS) data demonstrate the as-synthesized ex-situ catalyst mainly contains Co2+ and Co3+ species incorporating a substantial amount of phosphate anions. These experiments suggest that cost-efficient cobalt oxide materials on graphite exhibit alluring ability for water splitting, which might provide a novel method to fabricate low-cost devices for electrochemical energy storage.

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Hydrogenolysis of glycerol over HY zeolite supported Ru catalysts Shaohua Jin, Zihui Xiao, Chuang Li, Christopher T. Williams, Changhai Liang 2014, 23(2): 185-192.  DOI: 10.1016/S2095-4956(14)60134-0 摘要 ( 7771 )   An enhanced active and selective catalyst consisting of ruthenium supported on dealuminated HY zeolite has been prepared by a wet impregnation method. It was found that BET surface area of Ru/HY catalysts significantly increases after HCl treatment. This treatment also increases the concentration of strong acid sites in the catalyst. The hydrogenolysis of glycerol over 5 wt% Ru/HY catalyst was investigated at 190-220℃, an initial H2 pressure of 3-6 MPa, and in 20 wt% glycerol aqueous solution. The results indicate that HCl treated Ru/HY catalyst shows higher activity compared with the untreated Ru/HY catalyst, and that the glycerol hydrogenolysis efficiency is influenced by the porosity and acidity of the support. A selectivity to 1,2-PDO of 81.3% at a glycerol conversion of 60.1% under 3 MPa H2 pressure and 220℃ for 10 h was achieved over the modified Ru/HY catalyst with a 1.0 mol/L HCl treatment. It has also been shown that a longer reaction time, a higher temperature and a higher H2 pressure have the positive effects on the glycerol hydrogenolysis efficiency of the enhanced Ru/HY.

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Preparation of phosphorus-modified PITQ-13 catalysts and their performance in 1-butene catalytic cracking Penghui Zeng, Yun Liang, Shengfu Ji, Baojian Shen, Honghai Liu, Baojie Wang, Hongjuan Zhao, Mingfu Li 2014, 23(2): 193-200.  DOI: 10.1016/S2095-4956(14)60135-2 摘要 ( 7087 )   A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their catalytic performance in 1-butene catalytic cracking was evaluated in a fixed fluidized bed reactor. The results showed that the crystallinity, surface area and pore volume of P-modified PITQ-13 catalysts decreased with the increasing amounts of P. The number of weak acid sites increased, whereas that of strong acidity decreased. The selectivity to propylene in 1-butene cracking reactions increased because of the decrease in strong acidity. The yield of propylene achieved 41.6% over PITQ-13-2 catalyst with a P content of 1.0 wt%, which was 5.1% greater than that achieved over HITQ-13 catalyst.

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Methane formation route in the conversion of methanol to hydrocarbons Wenping Zhao, Baozhu Zhang, Guiru Wang, Hongchen Guo 2014, 23(2): 201-206.  DOI: 10.1016/S2095-4956(14)60136-4 摘要 ( 7871 )   The influence factors and paths of methane formation during methanol to hydrocarbons (MTH) reaction were studied experimentally and thermodynamically. The fixed-bed reaction results show that the formation of methane was favored by not only high temperature, but also high feed velocity, low pressure, as well as weak acid sites dominated on deactivated catalyst. The thermodynamic analysis results indicate that methane would be formed via the decomposition reactions of methanol and DME, and the hydrogenolysis reactions of methanol and DME. The decomposition reactions are thermal chemistry processes and easily occurred at high temperature. However, they are influenced by catalyst and reaction conditions through DME intermediate. By contrast, the hydrogenolysis reactions belong to catalytic processes. Parallel experiments suggest that, in real MTH reactions, the hydrogenolysis reactions should be mainly enabled by surface active H atom which might come from hydrogen transfer reactions such as aromatization. But H2 will be involved if the catalyst has active components like NiO.

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Hydrothermal exfoliated molybdenum disulfide nanosheets as anode material for lithium ion batteries Yundan Liu, Long Ren, Xiang Qi, Liwen Yang, Jun Li, Yao Wang, Jianxin Zhong 2014, 23(2): 207-212.  DOI: 10.1016/S2095-4956(14)60137-6 摘要 ( 7646 )   Ultrathin MoS2 nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2 nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm-2 μm. As anode material for Li-ion batteries, the as-prepared MoS2 nanosheets electrodes exhibited a good initial capacity of 1190 mAh·g-1 and excellent cyclic stability at constant current density of 50 mA·g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh·g-1.

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Adsorption separation performance of H2/CH4 on ETS-4 by concentration pulse chromatography Yanna Liu, Song Xiao, Pu Bai, Haoquan Hu, Lijun Jin 2014, 23(2): 213-220.  DOI: 10.1016/S2095-4956(14)60138-8 摘要 ( 6205 )   To exploit an effective adsorbent to separate hydrogen and methane, microporous titanium silicate molecular sieve NaETS-4 was synthesized and modified by strontium. The adsorption characteristics and diffusion behaviors of the prepared titanosilicate molecular sieve were studied by concentration pulse chromatography. And the effects of ion-exchange and dehydration temperature on adsorbent structure and gas diffusion were also discussed. The results showed that the thermal stability and Henry's Law constants were enhanced and micropore diffusivity decreased after exchanging Na+ with Sr2+. With the increase of dehydration temperature, Henry's Law constant and micropore diffusivity of CH4 decreased in both NaETS-4 and SrETS-4. While for H2 in SrETS-4, the increase of Henry's Law constant and the decrease of diffusion rate can be attributed to the shrinks of pore diameter resulting from the relocation of Sr2+. Correspondingly, the kinetic selectivity of H2/CH4 reached 8.91 indicating its potentiality in separating H2 and CH4.

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Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over Al2O3-K/CAC catalyst at low temperature Xin Sun, Ping Ning, Xiaolong Tang, Honghong Yi, Kai Li, Dan He, Xianmang Xu, Bin Huang, Ruiyun Lai 2014, 23(2): 221-226.  DOI: 10.1016/S2095-4956(14)60139-X 摘要 ( 6587 )   In this work, a series of coal-based active carbon (CAC) catalysts loaded by Al2O3 were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 30-70℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2 concentration, gas hourly space velocity (GHSV) and relative humidity (RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3 calcined at 300℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2 was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2 decrease. A small amount of O2 introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.

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Poly(amide-6-b-ethylene oxide)/SAPO-34 mixed matrixmembrane for CO2 separation Dan Zhao, Jizhong Ren, Hui Li, Kaisheng Hua, Maicun Deng 2014, 23(2): 227-234.  DOI: 10.1016/S2095-4956(14)60140-6 摘要 ( 7092 )   In this paper, poly(amide-6-b-ethylene oxide) (Pebax1657)/SAPO-34 mixed matrix membranes (MMMs) were prepared by solvent-evaporation method with acetic acid as a novel solvent. CO2, N2, CH4 and H2 permeation properties were investigated, and the physical properties of Pebax/SAPO-34 MMMs were characterized by XRD and SEM. At low SAPO-34 content, it was homogeneously distributed in the Pebax matrix, and then precipitated and agglomerated at high SAPO-34 content. The crystallinity of Pebax phase in Pebax/SAPO-34 MMMs decreased initially and then rebounded as a result of phase separation. With the increase of transmembrane pressure difference, CO2 permeability was enhanced due to the effect of pressure-induced plasticization. Owing to the happening of stratification, the CO2 permeability of Pebax/SAPO-34 MMMs (50 wt% SAPO-34) increased to 338 Barrer from 111 Barrer of pristine Pebax, while the selectivities of CO2/CH4 and CO2/N2 were almost unchanged. Compared with the pristine Pebax, the gas separation performances of Pebax/SAPO-34 MMMs were remarkably enhanced.

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Novel Ni/CeO2-Al2O3 composite catalysts synthesized by one-step citric acid complex and their performance in catalytic partial oxidation of methane Changlin Yu, Jiubiao Hu, Wanqin Zhou, Qizhe Fan 2014, 23(2): 235-243.  DOI: 10.1016/S2095-4956(14)60141-8 摘要 ( 10679 )   A series of novel Ni/CeO2-Al2O3 composite catalysts were synthesized by one-step citric acid complex method. The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, hydrogen temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry analysis (TGA). The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity (GHSV) and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane (CPOM) were investigated. Catalytic activity test results show that the highest methane conversion (>85%), the best selectivities to carbon monoxide (>87%) and to hydrogen (>95%), the excellent stability and perfect H2/CO ratio (2.0) can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700℃ under the reaction condition of 750℃, CH4/O2 ratio of 2:1 and gas hourly space velocity of 12000 mL·h-1·g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area (～108 m2·g-1), small crystallite size, easy reducibility and low coking rate.

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Production of hydrogen-rich gas and multi-walled carbon nanotubes from ethanol decomposition over molybdenum modified Ni/MgO catalysts Ruihao Chen, Yinzhi Xie, Yaqian Zhou, Jianhua Wang, Hui Wang 2014, 23(2): 244-250.  DOI: 10.1016/S2095-4956(14)60142-X 摘要 ( 7461 )   A series of molybdenum modified Ni/MgO catalysts (Ni-Mo/MgO) with different loading ratios of Ni:Mo were prepared by impregnation method. Ethanol decomposition to co-produce multi-walled carbon nanotubes and hydrogen-rich gas at temperatures of 600-800℃ was investigated over the synthesized Ni-Mo/MgO catalysts. The results showed that the catalytic activity depended strongly on the reaction temperature and loading ratio of Ni:Mo. According to the gaseous and solid products obtained, the reaction pathways for ethanol decomposition were suggested.

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Modelling of a tubular solid oxide fuel cell with different designs of indirect internal reformer P. Kim-Lohsoontorn, F. Priyakorn, U. Wetwatana, N. Laosiripojana 2014, 23(2): 251-263.  DOI: 10.1016/S2095-4956(14)60143-1 摘要 ( 6351 )   The cell performance and temperature gradient of a tubular solid oxide fuel cell with indirect internal reformer (IIR-SOFC) fuelled by natural gas, containing a typical catalytic packed-bed reformer, a catalytic coated wall reformer, a catalytic annular reformer, and a novel catalytic annular-coated wall reformer were investigated with an aim to determine the most efficient internal reformer system. Among the four reformer designs, IIR-SOFC containing an annular-coated wall reformer exhibited the highest performance in terms of cell power density (0.67 W·cm-2) and electrical efficiency (68%) with an acceptable temperature gradient and a moderate pressure drop across the reformer (3.53×10-5 kPa). IIR-SOFC with an annular-coated wall reformer was then studied over a range of operating conditions: inlet fuel temperature, operating pressure, steam to carbon (S:C) ratio, gas flow pattern (co-flow and counter-flow pattern), and natural gas compositions. The simulation results showed that the temperature gradient across the reformer could not be decreased using a lower fuel inlet temperature (1223 K-1173 K) and both the power density and electrical efficiency of the cell also decreased by lowering fuel inlet temperature. Operating in higher pressure mode (1-10 bar) improved the temperature gradient and cell performance. Increasing the S:C ratio from 2:1 to 4:1 could decrease the temperature drop across the reformer but also decrease the cell performance. The average temperature gradient was higher and smoother in IIR-SOFC under a co-flow pattern than that under a counter-flow pattern, leading to lower overpotential and higher cell performance. Natural gas compositions significantly affected the cell performance and temperature gradient. Natural gas containing lower methane content provided smoother temperature gradient in the system but showed lower power density and electrical efficiency.