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Chinese Journal of Catalysis
2012, Vol. 33, No. 7
Online: 21 June 2012


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Gao and coworkers investigated the changes in morphology and crystal phases of cerium oxides with thermal treatment and the performance of V₂O₅/CeO₂ catalysts for propane oxidation dehydrogenation.  The results clearly show the relationship between the structure and thermal stability of the nanomaterials and their catalytic properties. See the article on pages 1069–1074.

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Table of Contents for Vol. 33 No. 7 2012, 33 (7):  0-0.  Abstract ( 1016 )   PDF (1547KB) ( 901 )

Research Briefing

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Structural Effects of Cerium Oxides on Their Thermal Stability and Catalytic Performance in Propane Oxidation Dehydrogenation GAO Xu-Feng, CHEN Chun-Lin, REN Shi-Yuan, ZHANG Jian, SU Dang-Sheng 2012, 33 (7):  1069-1074.  DOI: 10.1016/S1872-2067(11)60404-X Abstract ( 2782 )   [Full Text(HTML)] () PDF (445KB) ( 1146 )   The low-dimensional ceria nanorods and nanoparticles were prepared by wet chemical methods. The structural effect on the thermal stability of CeO2 has been well investigated by in situ X-ray powder diffraction, transmission electron microscopy, and N2 physisorption, revealing a superior stability of CeO2 nanorods. CeO2-supported V2O5 catalysts were prepared by the incipient wetness impregnation method and their catalytic performance in the oxidative dehydrogenation of propane was evaluated. The V2O5/CeO2 nanorods catalysts display an improved selectivity for propene, probably arising from the immediate diffusion of propene product due to the open characteristic of rod-like structure.

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Ammonia Synthesis over Ruthenium Catalysts using Barium-Doped Zirconia as Supports Prepared by Citric Acid Method LIN Jian-Xin, WANG Zi-Qing, ZHANG Liu-Ming, NI Jun, WANG Rong, WEI Ke-Mei 2012, 33 (7):  1075-1079.  DOI: 10.1016/S1872-2067(11)60413-0 Abstract ( 2691 )   [Full Text(HTML)] () PDF (494KB) ( 1097 )   Barium-promoted zirconia (Ba-ZrO2) was synthesized by the citric acid method and used as supports for Ru/Ba-ZrO2 catalysts, which were prepared by incipient wetness impregnation with K2RuO4 as precursor. The obtained Ba-ZrO2 and catalysts were characterized by X-ray diffraction and CO2 temperature-programmed desorption. The effect of Ba content on the structure and catalytic activity of K-Ru/Ba-ZrO2 catalysts is discussed. The formation of BaZrO3 can improve significantly the catalytic activity of Ru/Ba-ZrO2 for ammonia synthesis. The ammonia concentration and rate of ammonia synthesis of the K-Ru/Ba-ZrO2 catalyst (molar ratio of Ba:Zr is 1:1) were 9.24% and 29.77 mmol/(g•h), respectively, at 425 °C, 5.0 MPa, and 10000 h-1. Improvements in electron conductivity and the basic nature of the catalyst may be the main reasons for such high catalytic activity in ammonia synthesis.

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Promotion Effect of Steam Treatment on Activity of Ni2P/SiO2 for Hydrodechlorination of Chlorobenzene GUO Ti, CHEN Ji-Xiang, LI Ke-Lun 2012, 33 (7):  1080-1085.  DOI: 10.1016/S1872-2067(11)60418-X Abstract ( 2750 )   [Full Text(HTML)] () PDF (562KB) ( 926 )   Ni2P/SiO2 was pretreated with a 0.8%H2O-99.2%H2 flow at 303, 514, and 543 K. The Ni2P/SiO2 catalysts before and after treatment were characterized by N2 adsorption-desorption, X-ray diffraction, inductively coupled plasma atomic emission spectrometry, H2 temperature-programmed desorption, and in situ diffuse reflection infrared Fourier transform spectroscopy, and their activities in the hydrodechlorination of chlorobenzene (CB) were tested in a fix-bed reactor. There was no difference in BET specific surface area, pore structure, the Ni2P crystallite size, the Ni content, and the Ni/P ratio for the Ni2P/SiO2 catalysts before and after treatment. The treatment at 303 K did not decrease the density of exposed Ni sites on Ni2P/SiO2, while the treatment at 514 and 543 K led to the decrease of exposed Ni sites and the increase of the P–OH groups on Ni2P/SiO2. Under the conditions of 513 K, the CB space velocity of 3.75 ml/(g·h), and the H2/CB molar ratio of 9.0, the initial CB conversions on the treated Ni2P/SiO2 catalysts exceeded 93.8%, which was much higher than that (5.6%) on the untreated one. The promotion effect of steam treatment on the activity of Ni2P/SiO2 may be related to a synergism between the Ni sites and the P–OH groups.

Research papers

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Selective Oxidation of Diphenylmethane to Benzophenone over CeAlPO-5 Molecular Sieves Subbiah DEVIKA, Muthiahpillai PALANICHAMY, Velayutham MURUGESAN 2012, 33 (7):  1086-1094.  DOI: 10.1016/S1872-2067(11)60401-4 Abstract ( 2156 )   [Full Text(HTML)] () PDF (597KB) ( 2217 )   Selective oxidation of diphenylmethane to benzophenone requires active and selective catalysts. The framework incorporation of cerium in AlPO-5 molecular sieves creates active cerium sites in isolation. These active sites are responsible for selective oxidation. Cerium incorporated AlPO-5 with different Al/Ce ratios were synthesized, and the vapor phase oxidation of diphenylmethane in air over these catalysts was studied at 250, 275, 300, 325, and 350 °C. The diphenylmethane conversion and selectivity for benzophenone were more than 90%. CeAlPO-5(25) was found to be more active than other catalysts. The stability of the catalyst was verified by the time on stream study which indicated steady diphenylmethane conversion and benzophenone selectivity. Hence framework incorporated CeAlPO-5 molecular sieves are stable and active catalysts for the selective oxidation of diphenylmethane.

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Silica-Bonded N-Propyl Diethylenetriamine Sulfamic Acid as a Recyclable Solid Acid Catalyst for the Synthesis of α-Aminonitriles Tahere RAHI, Mojtaba BAGHERNEJAD, Khodabakhsh NIKNAM 2012, 33 (7):  1095-1100.  DOI: 10.1016/S1872-2067(11)60383-5 Abstract ( 2556 )   [Full Text(HTML)] () PDF (341KB) ( 1223 )   Silica-bonded N-propyl diethylenetriamine sulfamic acid (SBPDSA) is employed as a recyclable catalyst to synthesize α-aminonitriles. These syntheses involved one-pot condensation of an aldehyde, an amine, and trimethylsilyl cyanide under mild reaction conditions at room temperature. SBPDSA was recycled seven times in the condensation of benzaldehyde, aniline, and trimethylsilyl cyanide without reduction of its catalytic activity.

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Photocatalytic Activity for Hydrogen Evolution over Well-Dispersed Heterostructured In2O3/Ta2O5 Composites XU Lei-Lei, NI Lei, SHI Wei-Dong, GUAN Jian-Guo 2012, 33 (7):  1101-1108.  DOI: 10.1016/S1872-2067(11)60382-3 Abstract ( 2682 )   [Full Text(HTML)] () PDF (883KB) ( 1359 )   Using well-dispersed Ta2O5 microspheres as supports, which were prepared by controlling the hydrolysis rates of tantalum ethoxide via the formation of glycolate in an acetone-water mixture, dispersible heterostructured In2O3/Ta2O5 composites were fabricated for photocatalytic hydrogen evolution under simulant solar light irradiation. The compositions, structure, morphologies, and optical absorption properties of these composites were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that in the as-prepared heterostructured In2O3/Ta2O5 composites, In2O3 nanoparticles are well distributed on the surface of Ta2O5 microspheres with a clear interface between the two phases. The incorporation of In2O3 extends the light absorption range and restricts photogenerated charge-carrier recombination, resulting in enhanced photocatalytic activity for hydrogen evolution.

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Structural Properties and Catalytic Activity of Sr-Substituted LaFeO3 Perovskite ZHANG Xiao-Jing, LI Hua-Ju, LI Yong, SHEN Wen-Jie 2012, 33 (7):  1109-1114.  DOI: 10.1016/S1872-2067(11)60388-4 Abstract ( 2741 )   [Full Text(HTML)] () PDF (877KB) ( 1196 )   Partial substitution of La3+ by Sr2+ in LaFeO3 resulted in significant changes in its structure and catalytic activity. The perovskite structure was changed from orthorhombic in LaFeO3 to nearly cubic in La0.8Sr0.2FeO3. Replacement of La3+ by Sr2+ induced a positive charge deficiency that was compensated for by the oxidation of some Fe3+ to Fe4+ and the generation of oxygen vacancies, which greatly promoted the reducibility of the perovskite. La0.8Sr0.2FeO3 gave considerably enhanced activity in CO oxidation and methane combustion because the oxygen vacancies accelerated the dissociation of gaseous oxygen on the surface in CO oxidation and facilitated the diffusion of lattice oxygen from the bulk to the surface during CH4 combustion.

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Mixtures of Steel-Making Slag and Carbons as Catalyst for Microwave-Assisted Dry Reforming of CH4 Jose M. BERMUDEZ, Beatriz FIDALGO, Ana ARENILLAS, J. Angel MENENDEZ 2012, 33 (7):  1115-1118.  DOI: 10.1016/S1872-2067(11)60386-0 Abstract ( 2314 )   [Full Text(HTML)] () PDF (285KB) ( 1014 )   The use of steel-making slag as catalysts for microwave-assisted dry reforming of CH4 was studied. Two carbon materials (an activated carbon and a metallurgical coke), mixtures of the carbon materials and Fe-rich slag, and mixtures of the carbon materials and Ni/Al2O3 were tested as catalysts. The mixtures of slag with carbons gave rise to higher and steadier conversions than those achieved over the carbon materials alone. In addition, the use of the metallurgical coke mixed with metal-rich catalysts gave rise to remarkable results. Thus, no CH4 and CO2 conversions were achieved when coke was used alone, whereas high conversions were obtained when it was mixed with the metal-rich catalysts.

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Synergetic Effect of La and Ba Promoters on Nanostructured Iron Catalyst in Fischer-Tropsch Synthesis Yahya ZAMANI, Mehdi BAKAVOLI, Mohamad RAHIMIZADEH, Ali MOHAJERI, Seyed Mohamad SEYEDI 2012, 33 (7):  1119-1124.  DOI: 10.1016/S1872-2067(11)60396-3 Abstract ( 2330 )   [Full Text(HTML)] () PDF (457KB) ( 935 )   Effect of promoters such as Barium and Lanthanum has been investigated on the conventional nanostructured iron catalyst in Fischer-Tropsch synthesis (FTS). The nanosized iron-based catalysts were prepared by a microemulsion method with the general formulation of 100Fe/4Cu, 100Fe/4Cu/2La, 100Fe/4Cu/ 1La/1Ba, and 100Fe/4Cu/2Ba. The phase, structure, and morphology of the catalysts were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature-programmed desorption of CO2, and temperature-programmed reduction. The results indicated that the addition of promoters could improve the activity of Fe catalysts for FTS and WGS (water-gas shift reaction) and lower the gas fraction at the outlet. In addition, both Ba- and La-promoted Fe catalysts exhibit the highest activity due to the synergetic effect.

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Role of CeO2 in Three-Component Au/CeO2/SiO2 Composite Catalyst for Low-Temperature CO Oxidation ZHANG Hui-Li, REN Li-Hui, LU An-Hui, LI Wen-Cui 2012, 33 (7):  1125-1132.  DOI: 10.1016/S1872-2067(11)60399-9 Abstract ( 2932 )   [Full Text(HTML)] () PDF (768KB) ( 891 )   Hierarchical composite nanostructure composed of Au, CeO2, and SiO2 was fabricated by sequentially depositing ceria nanoparticles through impregnation and calcination, and then gold nanoparticles through a deposition-precipitation method on hierarchical monolithic silica (HMS) with multi-length scale pore structure. The Au/CeO2/HMS composite nanostructure was characterized by X-ray diffraction, temperature-programmed reduction, and diffuse reflectance infrared Fourier transform spectroscopy. The results indicate that the presence of ceria had a significant effect on targeted deposition and stabilization of small metallic gold nanoparticles on the support. The temperature for complete conversion of CO to CO2 over Au/CeO2/HMS is ca. 60 oC at a space velocity of 80000 ml/(g·h). The highly dispersed metallic gold nanoparticles can activate CO and the small ceria nanoparticles supply oxygen in the reaction. The catalytic activity remains considerably stable during 48 h stability testing. The interaction between gold and ceria contributed greatly to CO oxidation and the presence of silica improved the stability of the gold catalyst.

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Effect of Additives on L-Proline Catalyzed Direct Asymmetric Aldol Reactions LUO Jian-Qing, TAN Rong, KONG Yu, LI Cheng-Yong, YIN Dong-Hong 2012, 33 (7):  1133-1138.  DOI: 10.1016/S1872-2067(11)60394-X Abstract ( 2761 )   [Full Text(HTML)] () PDF (317KB) ( 774 )   The direct asymmetric aldol reaction of aromatic aldehydes with acetone catalyzed by L-proline was accelerated by the addition of diols or diphenols. The use of additives decrease the amount of L-proline needed and allowed the use of solvent free conditions. Catechol with two adjacent hydroxy groups on aromatic ring was the most efficient additive. Under the optimized conditions, 5 mol% L-proline with 1 mol% catechol gave excellent chiral selectivity (80% ee value) with > 90% yield, which was higher than that obtained using 30 mol% L-proline without an additive. Computations indicated that the additive promoted the reaction by an intermolecular hydrogen bond between the hydrogen of the hydroxyl group and the oxygen of the carbonyl group, which activated the carbonyl group of the aldehyde. Catechol with two adjacent hydroxyl groups on the aromatic ring can form two hydrogen bonds with the oxygen of the carbonyl group on the corresponding aldehyde. Therefore, the combination of L-proline and catechol was very efficient in catalyzing the direct asymmetric aldol reaction and gave a high yield in a short time.

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Effect of Alkaline-Earth Metal Oxides on Cu/SiO2-Al2O3 Catalyst for Vapor-Phase Synthesis of 3-Methylindole from Glycerol and Aniline WANG Zhao-Yu, LI Xiao-Hui, ZHANG Yue, SHI Lei, SUN Qi 2012, 33 (7):  1139-1145.  DOI: 10.1016/S1872-2067(11)60407-5 Abstract ( 2548 )   [Full Text(HTML)] () PDF (1083KB) ( 760 )   The effect of the addition of an alkaline-earth metal oxide (MgO, CaO, SrO or BaO) to a Cu/SiO2-Al2O3 catalyst for the vapor-phase synthesis of 3-methylindole from glycerol and aniline was investigated. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, and thermogravimetric and differential thermal analysis. MgO reinforced the interaction between copper and the support, which promoted the dispersion of Cu particles. In addition, MgO increased the amount of weak acid sites and inhibited the formation of coke. As a result, the addition of MgO to Cu/SiO2-Al2O3 gave a much improved catalyst. Adding CaO, SrO or BaO to Cu/SiO2-Al2O3 deteriorated the catalysts because the dispersion of Cu particles became worse and the amounts of weak acid sites on Cu-SrO/SiO2-Al2O3 and Cu-BaO/SiO2-Al2O3 were fewer. The addition of the alkaline-earth metal oxides did not change the texture of the coke formed.

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Green and Recyclable Medium for Asymmetric Hydrogenation of Benzalacetone Catalyzed by RuCl2(TPPTS)2-(S,S)-DPENDS QIN Rui-Xiang, WANG Jin-Bo, XIONG Wei, FENG Jian, LIU De-Rong, CHEN Hua 2012, 33 (7):  1146-1153.  DOI: 10.1016/S1872-2067(11)60397-5 Abstract ( 2753 )   [Full Text(HTML)] () PDF (504KB) ( 1054 )   PEG400-H2O was a green and recyclable reaction medium for asymmetric hydrogenation of benzalacetone catalyzed by ruthenium achiral monophosphine complex, RuCl2(TPPTS)2 (TPPTS: P(m-C6H4SO3Na)3), which was modified by (S,S)-DPENDS (disodium salt of sulfonated (S,S)-1,2-diphenyl-1,2-ethylene-diamine). Under the optimized conditions, the chemoselectivity for 4-phenyl-3-buten-2-ol was 98.5% with a corresponding ee value of 74.3%. The resulting products could easily be separated from the catalyst by extraction with n-hexane. The catalyst immobilized on PEG400-H2O could be recycled and reused at least five times without significant loss of chemoselectivity and enantioselectivity.

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(1S,2S)-Diphenylethylenediamine Modified Ir/SiO2 Catalyst for Asymmetric Hydrogenation of Acetophenone and Its Derivatives YANG Chao-Fen, YANG Jun, SUN Xiao-Dong, ZHU Yan-Qin, WANG Qi-1, CHEN Hua 2012, 33 (7):  1154-1160.  DOI: 10.1016/S1872-2067(11)60403-8 Abstract ( 2464 )   [Full Text(HTML)] () PDF (487KB) ( 649 )   An efficient and highly dispersed 5%Ir/SiO2 catalyst for the asymmetric hydrogenation of acetophenone and its derivatives were prepared under basic conditions without the use of any stabilizer. The effects of different reaction parameters, namely, catalyst preparation, base used, chiral modifier, and concentration of (1S,2S)-diphenylethylenediamine ((1S,2S)-DPEN), were evaluated. Under optimum conditions with 5%Ir/SiO2 modified by (1S,2S)-DPEN, a high ee value of 70.0% was obtained for the asymmetric hydrogenation of acetophenone. It is noteworthy that this highest ee value was obtained with a supported metal catalyst without any stabilizer. The catalyst preparation is simple and there was no loss of enantioselectivity when the catalyst was reused several times.

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Ionic Liquid Effects on the Activity of β-Glycosidase for the Synthesis of Salidroside in Co-solvent Systems BI Yan-Hong, WANG Chao-Yu, MAO Yan-Yong, ZHENG Shang-Yong, ZHANG Hai-Jiang, SHI Hao 2012, 33 (7):  1161-1165.  DOI: 10.1016/S1872-2067(11)60395-1 Abstract ( 2367 )   [Full Text(HTML)] () PDF (407KB) ( 853 )   The preparation of salidroside was successfully carried out in fourteen ionic liquids (ILs)-containing systems using β-glycosidase from black plum seeds for the first time. The optimum conditions were determined for C6MIm?BF4, pH, phosphate buffer content, and molar ratio of tyrosol to D-glucose to be 1% (v/v), 5.9, 20% (v/v), and 8:1, under which the initial reaction rate and yield were 3.3 mmol/(L·h) and 24.5%, respectively. Moreover, the effects of 1-alkylimidazolium-based ILs possessing different alkyl chain lengths from C2 to C10 and a variety of anions including BF4-, PF6-, Cl-, Br-, and I- on enzyme activity in co-solvent systems were investigated. The results indicate that the optimal chain length of the alkyl substituent on the imidazolium ring of the cation was C6.

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Use of Intraparticle Mass Transfer Parameters as a Design Tool for Catalyst Pellets L. PETROV, M. DAOUS, Y. ALHAMED, A. AL-ZAHRANI, Kh. MAXIMOV 2012, 33 (7):  1166-1175.  DOI: 10.1016/S1872-2067(11)60406-3 Abstract ( 3224 )   [Full Text(HTML)] () PDF (290KB) ( 906 )   A chromatographic method and a dynamic Wicke-Kallenbach method (DMWK) were used to determine the diffusion characteristics of two industrial copper containing catalysts. The first catalyst was used in nitrobenzene hydrogenation to aniline and the second was used in a low temperature water-gas shift reaction. Experimental results show that application of these two methods leads to similar results. Experimental data obtained allow for monitoring changes in the texture of the catalyst grains and intraparticle diffusivity of gaseous reagents at different states of the catalyst activity and use, which can be used as criteria for designing optimal industrial catalyst pellets.

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Pre-reforming of Liquefied Petroleum Gas over Magnesium Aluminum Mixed Oxide Supported Nickel Catalysts WANG Xin-Xing, WANG Xue-Guang, SHANG Xing-Fu, NIE Wang-Xin, ZOU Xiu-Jing, LU Xiong-Gang, DING Wei-Zhong 2012, 33 (7):  1176-1182.  DOI: 10.3724/SP.J.1088.2012.20138 Abstract ( 2476 )   [Full Text(HTML)] () PDF (560KB) ( 770 )   The catalytic performance of Ni catalysts supported on magnesium aluminum mixed oxide (Ni/MgmAl) for the pre-reforming of liquefied petroleum gas (LPG) was studied, and the catalysts were prepared by the co-precipitation-impregnation method and calcined in the lower temperature range of 400–700 oC. The X-ray diffraction and H2 temperature-programmed reduction results showed that Ni species were highly dispersed on the catalyst surface without NiAl2O4 spinel formation. The Ni/MgmAl catalysts could be reduced to metallic Ni nanoparticles at 650 oC, which showed excellent catalytic activity and stability for LPG pre-reforming at 400 oC and a low steam/carbon molar ratio of 2.0. The effects of Mg/Al molar ratios, Ni loading, and calcination temperature of the support and catalyst on the catalytic behavior of the Ni/MgmAl catalysts were investigated in detail. The results revealed that the 15%Ni/Mg1.25Al catalyst with both support and catalyst calcined at 500 oC had the optimal catalytic performance for LPG pre-reforming. Compared with Ni/MgmAl catalysts calcined at high temperature (≥ 800 oC), the present catalysts showed easier coke deposition and a slight decrease in catalytic activity and stability. However, it may be more promising candidate for LPG pre-reforming for the use of hydrogen fuel cells in transportation and small stationary application due to lower reduction temperature.

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Reaction Mechanism for Partial Oxidation of Methane to Synthesis Gas over Rh/SiO2 Catalyst WEN Zai-Gong, LI Hu, WENG Wei-Zheng, XIA Wen-Sheng, HUANG Chuan-Jing, WAN Hui-Lin 2012, 33 (7):  1183-1190.  DOI: 10.3724/SP.J.1088.2012.20208 Abstract ( 2414 )   [Full Text(HTML)] () PDF (568KB) ( 792 )   The partial oxidation of methane (POM) for the production of synthesis gas over Rh/SiO2 catalyst was investigated by in situ Raman spectroscopy characterization, continuous flowing and pulse reaction evaluation focusing on the reaction mechanism of synthesis gas formation in the oxidation zone, i.e., the catalyst zone where O2 is still available in gas phase. It was found that when a flow of CH4:O2:Ar = 2:1:45 at 600 °C was passed through the pre-reduced 4% Rh/SiO2 catalyst, no bands associated with rhodium oxide could be detected on the catalyst by Raman spectroscopy. While Raman bands related to carbon species that originated from methane dissociation could be detected at the catalyst oxidation zone under working conditions. The results of pulse reaction of POM as well as steam reforming and CO2 reforming of methane at 700 °C with a contact time less than 1 ms over the catalyst indicate that the formation of CO and H2 is mainly resulted from the direct partial oxidation of CH4 while the steam reforming and CO2 reforming reactions play only a minor role in the oxidation zone of the catalyst bed. The pulse reaction with an isotopic gas mixture of CH4:16O2:H218O:He = 2:1:2:95 over the Rh/SiO2 catalyst further indicated that the C16O percentage was higher than 92% of the total CO produced in the reaction. Based on these results, the conclusion, that the major reaction responsible for synthesis gas formation in the oxidation zone of Rh/SiO2 catalyst bed is the pyrolysis of methane on reduced rhodium sites to form hydrogen and carbon adspecies followed by the coupling of two surface hydrogen atoms to H2 and partial oxidation of surface carbon species to CO, is suggested.

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Effect of Hydrothermal Treatment of Activated Carbon by Nitric Acid on Activity of Ba-Ru-K/AC Catalyst for Ammonia Synthesis Feng-Guo-Quan, Lan Guo-Jun , LI Ying, HAN Wen-Feng, LIU Hua-Zhang 2012, 33 (7):  1191-1197.  DOI: 10.3724/SP.J.1088.2012.20233 Abstract ( 3044 )   [Full Text(HTML)] () PDF (991KB) ( 927 )   Activated carbon (AC) was functionalized by HNO3 hydrothermal treatment at 180 oC. Ruthenium catalyst samples were prepared through incipient wetness impregnation with aqueous solution of RuCl3·3H2O precursor. The influence of HNO3 concentration on the support structure, surface oxygen functional groups (SOFGs), Ru dispersion, and the catalytic activity of Ru/AC for ammonia synthesis was investigated by N2 physisorption, He temperature-programmed desorption, CO chemisorption, and transmission electron microscopy. The results indicated that the amount of SOFGs, Ru particle size, and activity depend strongly on the HNO3 concentration used in the hydrothermal treatment. The porous texture of carbon support almost keeps unchanged with low HNO3 concentrations (≤ 2.0 mol/L) treatment, while it decreases significantly at high acid concentrations (2.4 mol/L). However, the amount of SOFGs increases with the concentration of nitric acid as well as the Ru particle size. Ammonia synthesis activity of the Ba-Ru-K/AC catalyst samples, whose support was treated with HNO3 (2.0 mol/L), is as high as 17.80% at 400 oC, 10 MPa, and 10000 h−1, which is 16.8% higher than that of the catalyst obtained via washing with HNO3 (4.6 mol/L). The optimal conditions of hydrothermal treatment are HNO3 (2.0 mol/L) at 150 oC for 4 h with filling degree 70%. Therefore, the amount of SOFGs and Ru particle size are tunable by varying the HNO3 concentration during the hydrothermal treatment.

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4-N,N-Dimethylamino Pyridine Promoted Oxidation of Toluene Catalyzed by Cobalt Acetate and Benzyl Bromide ZHANG Zhan, GAO Jin, MA Hong, XU Jie 2012, 33 (7):  1198-1202.  DOI: 10.3724/SP.J.1088.2012.20314 Abstract ( 2538 )   [Full Text(HTML)] () PDF (449KB) ( 778 )   The influence of different nitrous organic compounds, including triethylamine, 2,6-dimethylpyridine, 4-carboxylic pyridine, pyridine, and 4-N,N-dimethylamino pyridine (DMAP), on the oxidation of toluene catalyzed by cobalt acetate and benzyl bromide was investigated. DMAP showed improvement for the activity. The promoting effect was discussed.

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Effect of Oxalic Acid on the Structure and Catalytic Performance of Sb-V-O Catalyst for Propane Ammoxidation WANG Guo-Jun, GUO Yun, LU Guan-Zhong 2012, 33 (7):  1203-1208.  DOI: 10.3724/SP.J.1088.2012.20204 Abstract ( 2225 )   [Full Text(HTML)] () PDF (498KB) ( 730 )   VSb3 mixed oxide catalyst samples for propane ammoxidation were prepared by a coprecipitation method with the vanadium starting materials treated with different amounts of oxalic acid in the preparation process. The VSb3 mixed oxide catalyst prepared with vanadium starting materials treated with nitric acid and the catalyst without treatment were also prepared for comparison. The effects of the oxalic acid amount on the physicochemical properties of the VSb3 mixed oxide catalyst were investigated by low-temperature N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, and H2 temperature-programmed reduction, and its catalytic performance for propane ammoxidation to acrylonitrile was tested. The results showed that the addition of oxalic acid in preparation process can keep V at a low valence, which generates a greater amount of SbVO4 phase that is vital active sites for propane ammoxidation. In the catalyst prepared with the oxalic acid/V molar ratio of 3, more SbVO4 phase can be formed, and Sb and V with suitable valence and appropriate concentration could disperse on the catalyst surface, resulting in better balance between oxidation and reduction capability. Therefore, both the conversion of propane and the selectivity for acrylonitrile can be obviously enhanced over the VSb3 mixed oxide catalyst prepared by treating vanadium starting materials with oxalic acid.

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Synthesis of Ag@AgBr Photocatalyst and Its Performance for Degradation of Methylene Blue under Visible-Light Irridiation NIE Long-Hui, HUANG Zheng-Qing, XU Hong-Tao, ZHANG Wang-Xi, YANG Bai-Rui, FANG Lei, LI Shuai-Hua 2012, 33 (7):  1209-1216.  DOI: 10.3724/SP.J.1088.2012.20320 Abstract ( 3187 )   [Full Text(HTML)] () PDF (414KB) ( 1503 )   Ag@AgBr plasmon photocatalyst was prepared by the deposition-precipitation and photo-reduction method. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse spectroscopy. The photocatalytic activity and stability of the prepared samples were evaluated by the degradation of methylene blue (MB) under the visible light (l > 420 nm) irradiation. Several parameters, such as catalyst concentration, pH value, initial MB concentration, H2O2 content, recycling runs, and scavengers, were examined. The results show that the photocatalytic activity of Ag@AgBr reached 96% in MB aqueous solution (10 mg/L) containing 1 g/L catalyst at pH = 9.8 under visible-light irradiation, and it almost kept unchanged after five-cycle photocatalytic test. The degradation efficiency of MB had little variation in the presence of a small amount of H2O2 but reduced in the presence of excessive H2O2. MB photodegradation was greatly suppressed by ethylenediaminetetraacetic acid while slightly decreased by isopropanol. The photocatalytic mechanism for MB degradation by Ag/AgBr under visible light irradiation was also presented.

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Deep Dealumination of Ultrafine NaY Zeolite WANG Xi-Long, SONG Jin-Na, YE Xiu-Qun, GU Hai-Fang, HUANG Yao, NIU Guo-Xing 2012, 33 (7):  1217-1223.  DOI: 10.3724/SP.J.1088.2012.20249 Abstract ( 2271 )   [Full Text(HTML)] () PDF (449KB) ( 1023 )   The ultrafine NaY zeolite with 200 nm grain size was dealuminated deeply by the optimized treatment of (NH4)2SiF6 solution, steamed at 600 oC, silicon sol + oxalic acid, and steamed at 800 oC, respectively. The first treatment of (NH4)2SiF6 solution is very important, which can fix the framework defects of zeolite and strengthen its stability. The amount of (NH4)2SiF6 and treated number need to be carefully controlled according to the grain size of NaY zeolite. For 200 nm NaY zeolite, the best molar ratio of (NH4)2SiF6 to framework aluminum of zeolite is 0.16 and once treatment is relatively appropriate. The final dealuminated Y zeolite has the high framework Si/Al ratio of 27.3 and surface area of 581.9 m2/g, as well as the crystallinity of 65%. The key factor for the successful deep dealumination of ultrafine Y zeolite is to repair promptly its crystal defects resulting from the dealumination process. The treatments of (NH4)2SiF6 solution, silicon sol, and steamed at 800 oC appear such effect.

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Synthesis of Polyvinyl Pyrrolidone-Heteropolyacid Acidic Hybrid Catalyst and Its Catalytic Activity for Esterification Reactions LENG Yan, CHOU Xue-Qian, JIANG Ping-Ping, WANG Jun 2012, 33 (7):  1224-1228.  DOI: 10.3724/SP.J.1088.2012.20305 Abstract ( 2140 )   [Full Text(HTML)] () PDF (719KB) ( 1098 )   A novel acidic polyvinyl pyrrolidone-heteropolyacid hybrid catalyst PVP-PW was synthesized and characterized. The catalytic activity of the catalyst was measured in the esterification of acetic acid with n-butanol. The hybrid PVP-PW was demonstrated to be a highly efficient solid-liquid heterogeneous catalyst and exhibited high ester yield of 98.4% with perfect selectivity of 100%. After the reaction, the catalyst could be recovered simply by filtration and reused at least six times without a significant loss in the catalytic activity. In addition, this catalyst can be well applied to versatile carboxylic acids or alcohols for esterification.

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Selective Hydrogenation of Maleic Anhydride to Succinic Anhydride in Liquid Phase over Ni-Cu/Al2O3 Catalyst WANG Da, ZHANG Yin, LI Hai-Tao, ZHAO Li-Li, ZHANG Hong-Xi, ZHAO Yong-Xiang 2012, 33 (7):  1229-1235.  DOI: 10.3724/SP.J.1088.2012.20247 Abstract ( 2946 )   [Full Text(HTML)] () PDF (537KB) ( 863 )   A series of Ni-Cu/Al2O3 catalyst samples were prepared by the wetness impregnation method and characterized by N2 physisorption, H2 temperature-programmed reduction, H2 temperature-programmed desorption, X-ray diffraction, and CO temperature-programmed surface reaction. Their catalytic performance in the liquid phase hydrogenation of maleic anhydride was investigated. The results indicated that the particle size of nickel crystallites was reduced, and the nickel species was well dispersed. Then, the C=C hydrogenation activity was significantly improved when the catalyst was promoted by Cu. However, due to the interaction between Ni and Cu, the C=O hydrogenation was retarded. The combination of the above two factors led to high selectivity for succinic anhydride over 15%Ni-7%Cu/Al2O3 catalyst. The conversion of maleic anhydride and selectivity for succinic anhydride reached 100% under the reaction conditions of 5 MPa hydrogen pressure and 210 oC for 40 min.

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Titanium Silicalite Synthesized by Dry Gel Conversion Method and Its Catalytic Performance WANG Wei-Hai, LI Gang, LIU Li-Ping, CHEN Yong-Ying 2012, 33 (7):  1236-1241.  DOI: 10.3724/SP.J.1088.2012.20226 Abstract ( 2374 )   [Full Text(HTML)] () PDF (591KB) ( 767 )   TS-1 zeolite was synthesized by dry gel conversion technique with ethylenediamine (EDA) as alkali source and tetrapropylammonium bromide as template. On this base, the hierarchical TS-1 was prepared with sucrose as meso/macropore template. The obtained samples were characterized by powder X-ray diffraction, UV-Vis spectroscopy, and N2 physical adsorption-desorption. The catalytic performance of the samples was evaluated using the oxidation of small molecular thiophene (Th) and bulky molecular benzothiophene (BT). With the decrease of the EDA/H2O molar ratio at the bottom of autoclave, TS-1 samples presented the trend of increase for the crystallinity, Ti content in framework, and the catalytic activity in Th oxidation. When the ethylamine and n-butylamine were used as the alkali source, it was difficult for TS-1 to crystallize. Hierarchical TS-1 possessed mesopore/macropore and exhibited higher catalytic performance than TS-1 in Th oxidation. For the oxidation of BT, hierarchical TS-1 synthesized with sucrose/SiO2 molar ratio of 0.35 presented the highest activity and the BT removal rate could reach almost 100%. However, the TS-1 had no catalytic activity in oxidation of BT.