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Chinese Journal of Catalysis
2011, Vol. 32, No. 8
Online: 05 August 2011


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Dr. Stolle et al. in their article on pages 1312–1322 reported on the use of phase-separated mesoporous glasses as catalyst support for metal catalysts used in the liquid-phase selective hydrogenation of chalcone. Glass particles with sizes of 50–100 µm and pore diameter of 50 nm were the most suitable support material and gave high reaction rates and turnovers with Pd as the active metal. The choice of metal precursor significantly affects the hydrogenation rate and selectivity. Reactions carried out on the surfaces of Rh-, Pd-, or Pt-loaded particles were the fastest. In addition to the investigation of the reaction parameters, the authors showed that the energy distribution can be produced by either thermal or microwave heating.

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Table of Contents for Vol.32 No. 8 2011, 32 (8):  0-0.  Abstract ( 1211 )   PDF (1659KB) ( 802 )

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Research Progress in Supported Proline and Proline Derivatives as Recyclable Organocatalysts for the Asymmetric C–C Bond Formation Reactions LIU Yu-Xia, YANG Liu, MA Zhi-Wei, WANG Chuan-Chuan, TAO Jing-Chao 2011, 32 (8):  1295-1311.  DOI: 10.3724/SP.J.1088.2011.10344 Abstract ( 3807 )   [Full Text(HTML)] () PDF (635KB) ( 946 )   In recent years, L-proline and L-proline derivatives were successfully used as organocatalysts in asymmetric reactions. There are three different general approaches for organocatalyst immobilization: covalently supported catalysts, non-covalently supported catalysts, and biphasic catalysts in ionic liquids. This review summarizes some immobilized organocatalysts, highlighting their application, recoverability, and reusability in Aldol and Michael addition reactions.

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Liquid Phase Hydrogenation of Benzalacetophenone: Effect of Solvent, Catalyst Support, Catalytic Metal and Reaction Conditions Achim STOLLE, Christine SCHMOGER, Bernd ONDRUSCHKA, Werner BONRATH 2011, 32 (8):  1312-1322.  DOI: 10.1016/S1872-2067(10)60249-5 Abstract ( 3023 )   [Full Text(HTML)] () PDF (520KB) ( 1732 )   Innovative catalysts based on a “porous glass” support material were developed and investigated for the reduction of benzalacetophenone. The easy preparation conditions and possibility to use different metals (e.g. Pd, Pt, Rh) for impregnation gave a broad variety of these catalysts. Hydrogenation experiments with these supported catalysts were carried out under different hydrogen pressures and temperatures. Porous glass catalysts with Pd as the active component gave chemoselective hydrogenation of benzalacetophenone, while Pt- and Rh-catalysts tended to further reduce the carbonyl group, especially at elevated hydrogen pressures and temperatures. Kinetic analysis of the reactions revealed these had zero order kinetics, which was independent of the type of porous glass support and solvent used.

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Cerium Oxide Promoted Ni/MgO Catalyst for the Synthesis of Multi-walled Carbon Nanotubes YANG Wen, CHU Wei, JIANG Cheng-Fa, WEN Jie, SUN Wen-Jing 2011, 32 (8):  1323-1328.  DOI: 10.1016/S1872-2067(10)60247-1 Abstract ( 3255 )   [Full Text(HTML)] () PDF (468KB) ( 1093 )   Ni/MgO, Ni/CeO2-MgO, and Ni/CeO2 catalysts were prepared by the citric acid combustion method. Their catalytic properties for the synthesis of multi-walled carbon nanotubes (MWCNTs) by chemical vapor deposition using CH4 as carbon source were evaluated. The catalysts were characterized with N2 adsorption, X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The quality and structure of the CNTs were characterized by thermogravimetry (TG) and transmission electron microscopy (TEM). H2-TPR showed that CeO2 helped decrease the reduction temperature and increase the content of an easily reducible Ni species. XPS showed an energy shift of the Ni catalyst that was modified by CeO2. XRD showed that the reduced nickel maintained their small particle sizes in the Ni/CeO2-MgO catalysts. These findings suggested that the addition of CeO2 changed the chemical environment of the nickel species, which resulted in a weaker interaction between the nickel and the support and increased the reducibility of the Ni species. Moreover, the reduced nickel was highly dispersed on the CeO2-MgO support. The change enhanced the catalytic activity for the growth of carbon nanotubes (CNTs). Characterization by TG and TEM showed that the quality of the CNTs grown on Ni/CeO2-MgO was better than those grown on Ni/MgO catalyst.

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Effect of the Morphology of Pt Nanoparticles of Supported Pt Model Catalysts on CO Oxidation WANG Jia-Ning, DAI Hong-Xing, HE Hong 2011, 32 (8):  1329-1335.  DOI: 10.1016/S1872-2067(10)60242-2 Abstract ( 3552 )   [Full Text(HTML)] () PDF (1043KB) ( 1151 )   In order to investigate the influence of particle morphology on the catalytic activity of supported Pt model catalyst, platinum nanoparticles (NPs) with different morphologies were synthesized by a chemical method and loaded onto SiO2 to give well-defined supported catalysts. CO oxidation was used as the probe to investigate the catalytic activities of these Pt/SiO2 model catalysts. X-ray fluorescence, X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, and transmission electron microscopy characterization demonstrated that the different activities of these Pt/SiO2 catalysts were due to different crystal surfaces, which strongly influenced the adsorption and oxidation of CO on the Pt NPs.

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Synthesis of Zero, One, and Three Dimensional CeO2 Particles and CO Oxidation over CuO/CeO2 DAN Wen-Juan, LIU Chang, GUO Hong-Juan, YANG Li-Hua, WANG Xiao-Nan, FENG Zhao-Chi 2011, 32 (8):  1336-1341.  DOI: 10.1016/S1872-2067(10)60251-3 Abstract ( 2902 )   [Full Text(HTML)] () PDF (873KB) ( 1035 )   A method to synthesize zero, one, and three dimensional (0D, 1D, 3D) CeO2 from single crystal cerium formate by a surfactant-free route using H2O, ethanol and ethylene glycol as solvents is shown. 0D CeO2 was composed of aggregated particles of 0.2–0.5 μm. 1D CeO2 was hexagonal rods that were 25–30 μm in width and more than 500 μm in length. The pine needle shaped 3D CeO2 was assembled from smooth rods of 1 to 5 µm diameter and up to 50 µm length that had CeO2 nanoparticles as building units to give 3D micro/nanocomposite structures with a high BET surface area of 234 m2/g. Both 5 wt% CuO/1D CeO2 and 5 wt% CuO/3D CeO2 exhibited high catalytic activities for CO conversion due to the high BET surface area and the facile reducibility of surface CeO2.

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Aerobic Oxidation of Ethylbenzene Co-catalyzed by N-Hydroxyphthalimide and Oxobis(8-Quinolinolato) Vanadium (IV) Complexes QIN Jin-Wei, FU Zai-Hui, LIU Ya-Chun, HE Xiang-Ling, ZHANG De-Xi, WU Wen-Feng, WANG Yan-Long, GONG Xing-Lang, DENG Xiao-Lin, WU Hai-Tao, ZOU Yan-Hong, YU Ning-Ya, YIN Du-Lin 2011, 32 (8):  1342-1348.  DOI: 10.1016/S1872-2067(10)60255-0 Abstract ( 3748 )   [Full Text(HTML)] () PDF (876KB) ( 922 )   The mediation effect of vanadium compounds on the N-hydroxyphthalimide (NHPI)-catalyzed aerobic oxidation of ethylbenzene (EB) was investigated at 90 °C in benzonitrile. Among the vanadium mediators examined, a series of oxobis(8-quinolinolato) vanadium (IV) complexes (VIVOQ2), which were prepared by the coordination of 8-hydroxyquinoline or its derivatives with oxobis(2,4-pentanedionate) vanadium (IV) (VIV O(acac)2) showed a better mediation effect than VIVO(acac)2, NH4VO3, and V2O5 and they gave about 60%–69% EB conversion and 97% of acetophenone (AcPO) selectivity under optimum reaction conditions. This is due to the dual catalysis effects of these V mediators on the transformation of NHPI to the phthalimide-N-oxyl (PINO) radical and the decomposition of 1-phenylethyl hydroperoxide to AcPO, as supported by UV-Vis spectral characterization.

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Structural Characterization and Photocatalytic Activity of Hydrothermally Synthesized Mesoporous TiO2 for 2,4,6-Tribromophenol Degradation in Water LUO Hai-Ying, NIE Xin, LI Gui-Ying, LIU Ji-Kai, AN Tai-Cheng- 2011, 32 (8):  1349-1356.  DOI: 10.1016/S1872-2067(10)60241-0 Abstract ( 3553 )   [Full Text(HTML)] () PDF (793KB) ( 1119 )   Well defined mesoporous TiO2 (M-TiO2) nanocrystallites were prepared by the hydrothermal method using polypropylene glycol (PPG) as template. The method differs from traditional methods in the use of an acetic acid aqueous solution instead of the conventional hydrolysis inhibitors and acid catalysts. The morphology and microstructures of M-TiO2 were characterized by X-ray diffraction, thermogravimetric and differential thermogravimetric, scanning electron microscopy, and nitrogen adsorption-desorption. The effects of the synthesis process, template reagent content, and calcination temperature on the microstructure and photocatalytic activity were investigated. The relationship between the microstructure of M-TiO2 and its photocatalytic activity was studied by the photocatalytic degradation of 2,4,6-tribromophenol in water under UV irradiation. M-TiO2 with a regular channel structure, large pore size, and high specific surface area was successfully synthesized. The M-TiO2 synthesized by the hydrothermal method and calcined at 400 °C that used a PPG content of 20% gave the highest photocatalytic activity, and completely degraded 100 umol/L 2,4,6-tribromophenol within 1 h.

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Characterization and Mechanism of the Photoelectrocatalytic Oxidation of Organic Pollutants in a Thin-Layer Reactor ZHENG Qing, LI Jin-Hua, CHEN Hong-Chong, CHEN Quan-Peng, ZHOU Bao-Xue, SHANG Shu-Chuan, CAI Wei-Min 2011, 32 (8):  1357-1363.  DOI: 10.1016/S1872-2067(10)60250-1 Abstract ( 3453 )   [Full Text(HTML)] () PDF (383KB) ( 884 )   The characterization and mechanism of the photoelectrocatalytic oxidation of a typical endocrine disrupting chemical, bisphenol-A (BPA), on TiO2 nanotube arrays (TNAs) were investigated using a thin-layer reactor where BPA was rapidly and exhaustively oxidized. Physical parameters such as the photocurrent, the initial peak photocurrent, the exhaustive charge quantity, and the blank photocurrent were found to be related to the degradation rate and the reaction mechanism. The Langmuir equation was used to fit the relationship between the initial peak photocurrent response and the BPA concentration indicating the proportionality between the photocurrent responses and the adsorbed organic concentration. A first-order exponential decay fitting of transient photocurrent profiles indicated the validity of first-order organic degradation kinetics for the photoelectrocatalysis. These relationships were found to be valid for many other organics including urea, glycol, glumatic acid, tartaric acid, methanol, and diethanolamine. The quantitative relationship found in this study provides a theoretical foundation for the real-time determination of the degradability of toxic organics by photoelectrocatalytic sensors.

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Effect of Oxide Phase of Promoters on Coke Resistance over Pt/γ-Al2O3 Catalyst YU Jia-Feng, FANG Wen, GE Qing-Jie, XU Heng-Yong 2011, 32 (8):  1364-1369.  DOI: 10.3724/SP.J.1088.2011.10324 Abstract ( 3191 )   [Full Text(HTML)] () PDF (569KB) ( 1061 )   The effects of different promoters on coke deposition over Pt/Al2O3 catalyst for hydrogen-free cyclohexane dehydrogenation were investigated by catalytic tests and a series of analytical techniques such as X-ray diffraction, CO and H2 chemisorption, temperature-programmed desorption of NH3, and temperature-programmed reduction. The stability of different promoters modified catalysts is in the order of Zr-Pt/Al2O3 > Ca-Pt/Al2O3 > Ce-Pt/Al2O3 > Zn-Pt/Al2O3 > Ba-Pt/Al2O3. The results clearly show that the addition of promoters to the Pt/Al2O3 catalyst could inhibit coke deposition by increasing Pt dispersion and promoting hydrogen spillover. That is attributed to the high thermodynamic and chemical stability of the metal oxide promoters. They must be highly dispersed and stable without reacting with Al2O3 in calcination or forming alloy with Pt in reduction. The catalytic property of CaLa-Pt/Al2O3 is worse than either Ca-Pt/Al2O3 or La-Pt/Al2O3 because the acidity of catalyst is enhanced and the spillover hydrogen is reduced due to Ca-La strong interaction.

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Effect of Modification of SBA-15 by Carbon Films on Textural and Catalytic Properties of Supported Cobalt Catalysts ZHU Hai-Yan, ZHOU Chao-Hua, MA Lan, CHENG Zhen-Xing, SHEN Jian-Yi 2011, 32 (8):  1370-1375.  DOI: 10.3724/SP.J.1088.2011.10319 Abstract ( 3013 )   [Full Text(HTML)] () PDF (443KB) ( 819 )   Carbon coated mesoporous SBA-15, named SBA-15C, was obtained from as-synthesized SBA-15 after graphitization in inert gas. With SBA-15 and SBA-15C as supports and cobalt nitrate aqueous solution as precursor, the supported cobalt-based catalyst samples were prepared by a wet impregnation method. The catalyst samples were characterized by X-ray diffraction, N2 physisorption, temperature-programmed reduction, and NH3 microcalorimetric adsorption. The results suggested that upon doping the inner walls of SBA-15 with carbon, the hexagonal ordered mesoporous framework was retained while the surface area decreased a little and the thickness of pore wall increased. The supported cobalt-based catalyst retained the mesoporous characteristics with decreased surface area and pore volume. The average particle size of Co3O4 on SBA-15C was smaller than that on SBA-15, which suggested that the existence of carbon improved the dispersion of Co3O4 particles. However, the modification of SBA-15 with carbon films did not seem to increase the reducibility of Co3O4. Both Co/SBA-15 and Co/SBA-15C exhibited high selectivity for C5+ hydrocarbons (~80%), but Co/SBA-15C showed higher stability in the F-T synthesis reactions.

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CuI/P(OCH2CH3)3 Catalyzed Cross-Coupling Reaction of Aryl Iodides with Alkynes HE Ting, GE Yi-Cen, WU Lei-Lei, FU Hai-Yan, CHEN Hua, LI Xian-Jun 2011, 32 (8):  1376-1379.  DOI: 10.3724/SP.J.1088.2011.10311 Abstract ( 3681 )   [Full Text(HTML)] () PDF (824KB) ( 1518 )   The commercially available ligand P(OCH2CH3)3 was first used in the copper catalyzed cross-coupling reaction of aryl iodides with alkynes. The influences of different copper salts, metal purity, bases, and catalyst dosages were investigated. The results indicate that the coupling of a broad range of aryl iodides with alkynes can be catalyzed by the system of 5 mol% CuI/ P(OCH2CH3)3 efficiently. In addition, this catalyst also exhibits good activity in the synthesis of 2-phenyl-benzofuran in one pot, which provides an economical way for the synthesis of similar compounds.

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Effect of Promoter on the Performance of Cu-Mn Complex Oxide Monolithic Catalysts for Lean Methane Catalytic Combustion ZHANG Jia-Jin, LI Jian-Wei, ZHU Ji-Qin, WANG Yue, CHEN Biao-Hua 2011, 32 (8):  1380-1386.  DOI: 10.3724/SP.J.1088.2011.10323 Abstract ( 3254 )   [Full Text(HTML)] () PDF (867KB) ( 1016 )   Five Cu-Mn complex-oxide catalysts supported on cordierite (COR) monolithic, Cu-Mn-O/Al2O3/COR, Cu-Mn-Ce-O/Al2O3/ COR, Cu-Mn-Zr-O/Al2O3/COR, Cu-Mn-La-O/Al2O3/COR, and Cu-Mn-Ce-Zr-O/Al2O3/COR, for the catalytic combustion of lean methane were prepared by wetness impregnation using cordierite as the support. The effect of promoters such as CeO2, ZrO2, La2O3, and CeO2-ZrO2, on the structure and properties of Cu-Mn-O/Al2O3 was characterized by X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, and N2 adsorption-desorption. The catalytic performance of lean methane catalytic combustion over these catalysts was evaluated in a fixed-bed reactor. The results showed that with the introduction of CeO2, ZrO2, La2O3, and CeO2-ZrO2 as the promoter to Cu-Mn-O/ Al2O3/COR, the specific surface area of the catalysts increases obviously, resulting in an enhancement of active component dispersion and oxygen species concentration on the catalyst surface. Therefore, the surface oxidation reactivity of the catalysts is improved. Besides, the pore structure of the catalysts is also adjusted well, which is beneficial for matching the diffusion-reaction coupling behavior on the catalyst. The activity of Cu-Mn-O/Al2O3/COR, especially the low-temperature activity remarkably increases with the promoter addition. Among the tested promoters, ZrO2 shows the best promoting effect. The methane conversion over Cu-Mn-Zr-O/Al2O3/COR monolithic catalyst is up to 90% under the conditions of 570 °C and GHSV = 20000 h–1.

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Efficient Oxidative Degradation of 2,4-Dichlorophenol over Supported CuO-Based Catalysts LI Jing-Jing, LIU Xing-Hai, SHI Lei, SUN Qi, ZHOU Yong-Gang, XU Jian-Feng, DAN Zuo-Gang, WANG Fu-Dong 2011, 32 (8):  1387-1392.  DOI: 10.3724/SP.J.1088.2011.10334 Abstract ( 2805 )   [Full Text(HTML)] () PDF (863KB) ( 819 )   The catalytic oxidative degradation of 2,4-dichlorophenol (2,4-DCP) was studied. The results indicated that CuO/γ-Al2O3 exhibited high activity for the reaction. Adding alkaline-earth metal oxides into CuO/γ-Al2O3 improved the liberation rate of chloride ion from 2,4-DCP remarkably and SrO was the most efficient. The 2,4-DCP conversion and the liberation rate of chloride ion reached 100% when the CuO/γ-Al2O3-SrO catalyst was used 3 times. The results of X-ray diffraction and the temperature-programmed-desorption of ammonia indicated that the catalyst with good dispersion of CuO particles and a less amount of acid sites was favorable for the efficient oxidative degradation of 2,4-DCP. A probable pathway of the oxidative degradation for 2,4-DCP over the copper-based catalyst was suggested.

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Catalytic Activity of Ni/MgO-Al2O3 Catalytically Activated Absorber for CO2 Reforming with CH4 Driven by Direct Light Irradiation LONG Hua-Li, HU Shi-Jing, XU Yan, QIN Pan, SHANG Shu-Yong, YIN Yong-Xiang, DAI Xiao-Yan 2011, 32 (8):  1393-1399.  DOI: 10.3724/SP.J.1088.2011.10406 Abstract ( 3617 )   [Full Text(HTML)] () PDF (627KB) ( 894 )   Nickel-based catalyst samples prepared by the plasma reduction method and thermal method were used to make catalytically activated absorbers, and their activity for solar CO2 reforming with CH4 was tested using a laboratory-scale receiver-reactor with a sun-simulator. The results showed that the catalytically activated absorber of Ni/MgO-Al2O3 reduced by plasma had the highest activity at low temperature. Under the conditions of average ?ux density of 61 kW/m2 and gas hourly space velocity of 36 dm3/(g·h), the CO2 and CH4 conversion was 54.5% and 72.7%, respectively, and the chemical storage efficiency reached 42.8%. The X-ray diffraction and transmission electron microscopy results indicated that the catalyst reduced by plasma exhibited higher dispersion of nickel and smaller crystal size than the catalyst reduced by the thermal method. The addition of MgO enhanced the basicity of the support and reduced the probability of carbon deposition on Ni/MgO-Al2O3.

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Effect of Supports on Catalytic Performance of Nickel-Based Catalyst for Methanation LI Xia, YANG Xia-Zhen, TANG Hao-Dong, LIU Hua-Zhang 2011, 32 (8):  1400-1404.  DOI: 10.3724/SP.J.1088.2011.10405 Abstract ( 3214 )   [Full Text(HTML)] () PDF (505KB) ( 1104 )   Catalytic behavior for syngas methanation over nickel-based catalysts with different supports (Al2O3-1, Al2O3-2, and SiO2) was investigated. The results showed that the catalyst prepared by Al2O3-2 or SiO2 support possessed higher activity and stability, while the stability of Ni/Al2O3-1 catalyst was extremely poor. The catalysts were characterized by X-ray powder diffraction, transmission electron microscopy, temperature-programmed reduction, N2 adsorption-desorption, and thermogravimetry. Characterization results showed that carbon deposition is not a key factor in determining the catalyst stability, while the destruction of support structure and the migration and agglomeration of Ni particles during the reaction may be the main reasons for the rapid deactivation of the Ni/Al2O3-1 catalyst.

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Enzymatic Synthesis of L-Tryptophan Catalyzed by Tryptophan Synthase in a Water/Organic Solvent Biphase System XU Li-Sheng, LIU Jun-Zhong, WANG Zhi-Yuan, ZHANG Hong-Juan, LIU Wei, LIU Qian, JIAO Qing-Cai 2011, 32 (8):  1405-1410.  DOI: 10.3724/SP.J.1088.2011.10349 Abstract ( 2950 )   [Full Text(HTML)] () PDF (795KB) ( 923 )   Enzymatic synthesis of L-tryptophan from L-serine and indole catalyzed by tryptophan synthase from recombinant Escherichia coli DM206 [pET28a-trpBA/BL21(DE3)] in an aqueous/organic biphasic system was carried out. The effects of organic solvents, volume fraction of ethyl acetate, reaction temperature, pH value of the aqueous phase, molar ratio of L-serine to indole, L-serine concentration, surfactants, and enzyme amount were investigated. Ethyl acetate was found to be the best organic solvent for the reaction. The optimal volume fraction of ethyl acetate was 2.5%. The optimal temperature and pH value were 35 ºC and 8, respectively. The optimal molar ratio of L-serine to indole was 1:1.2. The optimal L-serine concentration was 100 mmol/L. The optimal mass fraction of Tween 80 was 0.4%. The optimal enzyme amount was 20 g/L. Under the optimal conditions, bioconversion rate of L-serine reached 95% after 2.5 h in the aqueous/organic biphasic system.

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Nano-Perovskite-Based (LaMO3) Oxygen Carrier for Syngas Generation by Chemical-Looping Reforming of Methane DAI Xiao-Ping, YU Chang-Chun 2011, 32 (8):  1411-1417.  DOI: 10.3724/SP.J.1088.2011.10416 Abstract ( 2998 )   [Full Text(HTML)] () PDF (633KB) ( 834 )   Catalytic reforming of natural gas is a commercial process to produce syngas, which is the main source for the production of ammonia, methanol, hydrogen, and many other important products. This method produces also large amounts of CO2 as by-product. Chemical-looping reforming (CLR) is a novel technology that can be used for syngas production by partial oxidation and steam reforming of hydrocarbon fuels. One key issue with the CLR concept that is being widely studied is the oxidation and reduction behavior of potential oxygen-carrier materials. Four perovskite-based nano-composite oxides were prepared by the sol-gel method and characterized by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy (SEM), and CH4 temperature-programmed surface reaction. The catalytic performance of the prepared samples for CLR of CH4 to syngas was investigated. The results showed that the LaMO3 (B = Cr, Mn, Fe, and Co) oxides possess perovskite-type nano-composite structure. The oxidizing ability of these four perovskite oxides follows the order of LaCoO3 > LaMnO3 > LaFeO3 > LaCrO3. Among them, LaFeO3 oxide has higher activity for CLR of CH4 to syngas. The CH4 conversion and CO selectivity are 89.6% and 98.9%, respectively. Especially, the sequential redox reaction revealed that the LaFeO3 oxide exhibits high stability with CH4 conversion of 60%~70% and CO selectivity of ~98% after 10 redox cycles. The SEM analysis revealed that the structure of the LaFeO3 oxide was not dramatically changed before and after 10 cyclic reactions.

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Enhanced Ammonia Synthesis Activity of Ru Supported on Nitrogen-Doped Carbon Nanotubes GAO Wei-Jie, GUO Shu-Jing, ZHANG Hong-Bo, PAN Xiu-Lian, BAO Xin-He 2011, 32 (8):  1418-1423.  DOI: 10.3724/SP.J.1088.2011.01020 Abstract ( 3336 )   [Full Text(HTML)] () PDF (710KB) ( 1255 )   Nitrogen-doped carbon nanotubes (NCNTs) were synthesized via chemical vapor deposition using acetonitrile as the carbon and nitrogen sources. Transmission electron microscopic characterization showed clearly tubular morphology of NCNTs with inner diameter of 10–15 nm and wall thickness of 10–20 nm. X-ray photoelectron spectroscopy (XPS) indicated that nitrogen species were incorporated into CNTs and the predominating type of nitrogen species were pyridinic and quaternary nitrogen. XPS, X-ray diffraction, and Raman spectroscopy showed that with increasing temperature the total amount of nitrogen species decreased but the nanotubes were better graphitized. Ru supported on NCNTs exhibited an obviously enhanced activity in ammonia synthesis as compared with the CNT-supported Ru catalyst. In particular, in the temperature range of 550~750 oC, the NCNTs obtained at 650 °C after deposition of Ru yielded a better activity, which was most likely attributed to the promoting effect of nitrogen doping and the graphitization of nanotubes.

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Different Supports-Supported Cr-Based Catalysts for Oxidative Dehydrogenation of Isobutane with CO2 SUN Guo-Song, HUANG Qing-Ze, LI Hui-Quan, LIU Hai-Tao, ZHANG Zhao, WANG Xing-Rui, WANG Qiu-Ping, WANG Jin-Shu 2011, 32 (8):  1424-1429.  DOI: 10.3724/SP.J.1088.2011.10236 Abstract ( 3123 )   [Full Text(HTML)] () PDF (492KB) ( 904 )   The effect of supports (MSU-1, γ-Al2O3, AC (activated carbon), and MgO) on the catalytic activity of Cr-based catalysts was investigated for the dehydrogenation of isobutane with CO2. The catalytic activity was in the order of CrOx/MSU-1 > CrOx/Al2O3 > CrOx/AC > CrOx/MgO. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD). The XRD results indicate that the active species of Cr are dispersed well on the supports. N2 adsorption-desorption shows that the support MSU-1 has the largest surface area (804.2 m2/g), which results in excellent dispersion of Cr and highest activity. The XPS results reveal that Cr6+ is one of the active centers. The results of NH3-TPD indicate that catalyst activity is proportional to the amount of weak acid adsorption sites. As a result, the best support is the MSU-1 zeolite owing to its high specific area and a large amount of weak acid sites. The 59.2% conversion of isobutane and the 39.5% yield of isobutene are achieved on the CrOx/MSU-1 catalyst.

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Preparation of Novel N-TiO2 by a Solid-State Method and Its Photocatalytic Activity MA Peng-Ju, YAN Guo-Tian, QIAN Jun-Jie, ZHANG Min, YANG Jian-Jun 2011, 32 (8):  1430-1435.  DOI: 10.3724/SP.J.1088.2011.10431 Abstract ( 2953 )   [Full Text(HTML)] () PDF (591KB) ( 1171 )   N-doped TiO2 photocatalyst samples were prepared by manual grinding the mixture of nanotube titanic acid and ammonium bicarbonate followed by annealing the mixture at different temperatures in Ar atmosphere for 4 h. The samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometry, transmission electron microscope, and N2 adsorption-desorption. The XPS results indicated that the N was in the form of interstitial atom, i.e., Ti–O–N bond. The intermediate (NH4)2Ti2O4(OH)2 was formed when the mixture was calcined at different temperatures. Subsequently, the N was released due to the decomposition of (NH4)2Ti2O4(OH)2, resulting in the formation of interstitial-N and oxygen vacancies. N-TiO2 samples showed enhanced visible light absorption and visible light photocatalytic activity because of the existence of interstitial N-dopants and oxygen vacancies. The doped N atoms restrained the phase transition from anatase to rutile at higher temperature. Photocatalytic activity was evaluated by degradation of methyl orange in aqueous solution under xenon lamp irradiation, and the N-TiO2 sample with n(N)/n(Ti) = 4 annealed at 500 °C exhibited the highest photocatalytic activity. After 130 min irradiation, the photocatalytic degradation rate of methyl orange was up to 100%, almost 30% higher than that of un-doped TiO2.