List of Issues

Chinese Journal of Catalysis
2008, Vol. 29, No. 5
Online: 25 May 2008

Previous Issue    Next Issue

Cover:

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Articles

Select

Effect of Aluminum on the Mechanical Stress Stability of WOx/ZrO2 Superacid TIAN Ge;XU Yunpeng;XU Zhusheng;TIAN Zhijian*;LIN Liwu 2008, 29 (5):  415-417.  Abstract ( 1939 )   [Full Text(HTML)] () PDF (190KB) ( 804 )   Tetragonal structure of ZrO2 support is very important for WOx/ZrO2 catalysts to be highly active. In this study, it was found that mechanical stress treatments (grinding in a mortar or pressing under 50 MPa) resulted in a partial phase transformation of WOx/ZrO2 from tetragonal ZrO2 to monoclinic ZrO2 and also decreased the n-heptane isomerization activity of the Pt/WOx/ZrO2 catalyst. The addition of aluminum greatly improved the resistance of WOx/ZrO2 to mechanical stress and maintained its n-heptane isomerization activity.

Select

Preparation of Nanoscale CexFe1-xO2 Solid Solution Catalyst by the Template Method and Its Catalytic Properties for Ethanol Steam Reforming LIN Hongyan;MA Zhiqiang;DING Ling;QIU Jieshan;LIANG Changhai* 2008, 29 (5):  418-420.  Abstract ( 1956 )   [Full Text(HTML)] () PDF (221KB) ( 660 )   Nanoscale CexFe1-xO2 solid solutions with high surface area were prepared by a modified template route using an ultrahigh surface area carbon material as the template and nitrate as the oxide precursor. The resultant samples were characterized by XRD, N2 adsorption, Raman spectroscopy, and TEM. The results show that the particle sizes of α-Fe2O3, CexFe1-xO2 solid solutions, and CeO2 are 5-15 nm. Partial Ce4+cations in the nanoscale CeO2 are substituted by Fe3+cations, which results in the formation of CexFe1-xO2 solid solutions. The CexFe1-xO2 solid solutions have superior catalytic activity and selectivity for hydrogen in the ethanol steam reforming compared with the CeO2 and α-Fe2O3 catalysts.

Select

Preparation of Pt/Al2O3 Metallic Honeycomb Catalyst and Its Catalytic Properties for CO Preferential Oxidation ZHANG Jianguo;JIA Jingsheng;ZHANG Chunxi;WANG Shudong\{*\} 2008, 29 (5):  421-425.  Abstract ( 1933 )   [Full Text(HTML)] () PDF (454KB) ( 1015 )   A Pt/Al2O3 metallic honeycomb catalyst was prepared and studied in the CO preferential oxidation. The surface of the Fe-20Cr-5Al metallic substrate (400 cells/in2) appeared needle shape structure when it was oxided at 900 ℃ for 10 h. The optimal Al2O3 coating procedure was slurry-sol-slurry. The metallic honeycomb catalyst showed CO conversion of 54.0% and CO selectivity of 42.5% in CO preferential oxidation at 120 ℃, which were 1.7 and 1.4 times that of the ceramic honeycomb catalyst, respectively.

Select

Photocatalytic Degradation Mechanism of Malachite Green under Visible Light Irradiation over Novel Biomimetic Photocatalyst HMS-FePcs GAO Guandao*;ZHANG Aiyong;ZHANG Meng;CHEN Jinlong;ZHANG Quanxing 2008, 29 (5):  426-430.  Abstract ( 1904 )   [Full Text(HTML)] () PDF (290KB) ( 962 )   Upon visible light irradiation in the presence of H2O2, the novel catalyst HMS-FePcS was found to be highly effective for the degradation of nonbiodegradable malachite green (MG). High-performance liquid chromatography spectra and mass spectrometry spectra during the degradation process were analyzed to show that the MG degradation included its decolorization followed by the mineralization of intermediates. More than ten intermediates were confirmed through GC-MS, and the most probable degradation pathway for MG was proposed. The C-C bond between the central carbon atom and N,N-dimethylaminobenzyl was broken first to give the intermediate 4-(N,N-dimethylamino)methylbenzylone. Subsequently, 4-(N,N-dimethylamino)methylbenzylone reacted with strongly oxidative hydroxyl radicals. Finally, benzene rings were opened, and many small molecules such as fatty acids were produced.

Select

Surface Properties of CuO/ZnO/Al2O3 Catalyst for Methanol Synthesis in Slurry Reactor LI Zhong*;ZHENG Huayan;XIE Kechang 2008, 29 (5):  431-435.  Abstract ( 2179 )   [Full Text(HTML)] () PDF (321KB) ( 803 )   The CuO/ZnO/Al2O3 slurry catalyst was prepared by parallel flow co-precipitation at different Cu/Zn molar ratios and characterized by N2 adsorption-desorption,X-raydiffraction, H2 temperature-programmed reduction, andX-rayphotoelectron spectroscopy. When Cu/Zn≤1, the quantity of highly dispersed copper oxide on the catalyst surface was increased with increasing copper content, which favored the interaction of CuO and ZnO and increased catalyst activity for methanol synthesis. When Cu/Zn>1, the quantity of bulk copper was increased with increasing copper content, the crystallinity of ZnO was increased, and the interaction of CuO and ZnO was weakened, leading to the decrease in the activity of the CuO/ZnO/Al2O3 catalyst.

Select

CuO-CeO2/Al2O3/FeCrAl Monolithic Catalyst Prepared by the Microemulsion Method for Preferential Oxidation of CO ZENG Shanghong;LIU Yuan* 2008, 29 (5):  436-440.  Abstract ( 1891 )   [Full Text(HTML)] () PDF (306KB) ( 810 )   A new technique, the microemulsion method, for depositing CuO-CeO2 on FeCrAl honeycomb supports was described. Adhesion stability of the monolithic catalyst was tested via ultrasonic and thermal shock experiments. The monolithic catalyst was characterized by scanning electron microscopy,X-raydiffraction, andX-rayphotoelectron spectroscopy. The results showed that CuO-CeO2 could be loaded on the FeCrAl honeycomb supports with good adhesion stability by the microemulsion method. CuO-CeO2 was in a nanoparticle form and was homogeneously dispersed on the surface of the supports. The supports had no obvious influence on the chemical states of the catalyst. The CuO-CeO2/Al2O3/FeCrAl monolithic catalyst was used in the preferential oxidation of CO in hydrogen-rich gases and exhibited good activity, high selectivity, and good stability.

Select

Preparation and Modifiable Character of a Novel Amorphous Catalyst Ru-Fe-B/ZrO2 for the Selective Hydrogenation of Benzene to Cyclohexene SUN Haijie;ZHANG Cheng;YUAN Peng;LI Jianxiu;LIU Shouchang* 2008, 29 (5):  441-446.  Abstract ( 2413 )   [Full Text(HTML)] () PDF (422KB) ( 822 )   A novel nano-amorphous Ru-Fe-B/ZrO2 catalyst was prepared by the chemical reduction method and showed high activity and selectivity in the selective hydrogenation of benzene to cyclohexene. The catalyst was characterized by transmission electron microscopy, selected-area electron diffraction,X-raydiffraction, and N2 adsorption. The modifiable character of the activity and selectivity of the catalyst and the effects of NaBH4 concentration and pH of the filtrate on the catalyst performance were investigated. The results showed that over this catalyst the selectivity for cyclohexene reached 80% at 54% of benzene conversion. Moreover, the selectivity decreased slowly with the increase of benzene conversion. The activity and selectivity of the catalyst could be adjusted through adding acid or alkali to the reaction system. The catalyst preparation and properties could be repeated. It was concluded that the nanometer scale and amorphous structure of the catalyst were the main factors for its high activity and selectivity for the selective hydrogenation of benzene to cyclohexene.

Select

Effects of MgO and CaO Promoters on Fe-K-Based Catalysts CHEN Tong*;FAN Qin;LIAO Shijie;NI Junping;MIAO Changxi 2008, 29 (5):  447-452.  Abstract ( 2258 )   [Full Text(HTML)] () PDF (542KB) ( 1085 )   Fe-K-based catalysts with MgO and CaO as promoters were prepared, and their catalytic performance for dehydrogenation of ethylbenzene to styrene was examined in a fixed-bed reactor. The effects of MgO and CaO on the catalysts were characterized by means of SEM, XRD, TPR, and Mssbauer spectroscopy. The catalyst activity was improved by the substitution of Mg2+for Fe3+, and the formation temperature of the active precursor, K2Fe22O34, could be decreased owing to the solid solution of magnesium ferrite on the Fe-K-Mg-based catalyst. The crystallization degree and the selectivity for styrene were improved on the Fe-K-Ca-based catalyst, which was due to the CaO in/on the sill-like crystallites of K2Fe22O34. Furthermore, the reduction of Fe3+was prevented, and the structural stability of the catalyst was enhanced by the CaO promoter.

Select

Gas-Phase Photocatalytic Oxidation of Benzene over TiO2 Supported on Ce0.5-xZr0.5-xBa2xO2 PI Zhan;CAI Li;ZHONG Junbo;GONG Maochu;CHEN Yaoqiang 2008, 29 (5):  453-457.  Abstract ( 2137 )   [Full Text(HTML)] () PDF (296KB) ( 717 )   Photooxidation of gaseous benzene was investigated using anatase TiO2 as the catalyst in a closed steel reactor. The photocatalytic activity can be greatly improved by supporting TiO2 on Ce0.5-xZr0.5-xBa2xO2. The optimal Ba content in the photocatalyst was investigated. The prepared photocatalysts were characterized byX-raydiffraction, UV-Vis diffuse reflectance spectroscopy, andX-rayphotoelectron spectroscopy. The results revealed that the deposited titania is well dispersed as in the Ce0.5-xZr0.5-xBa2xO2 matrix. TiO2/Ce0.5-xZr0.5-x-Ba2xO2 absorbs much more ultraviolet light in the range of 210-400 nm than TiO2. There are Ti and O elements on the surface of TiO2/Ce0.5-xZr0.5-xBa2xO2, and the binding energy of Ti 2p of TiO2/Ce0.5-xZr0.5-xBa2xO2 shifts to a lower value. Based upon the above observations, it is concluded that the role of Ce0.5-xZr0.5-xBa2xO2 is to transfer electrons and enhance the light absorption of the catalyst in the region of 210-400 nm.

Select

Catalytic Activity and Stability of Magadiite-Immobilized Myoglobin in Organic Solvents PENG Shuge*;GAO Qiuming;LIU Hongyu;LU Chang;ZHANG Yuqing 2008, 29 (5):  458-462.  Abstract ( 2284 )   [Full Text(HTML)] () PDF (309KB) ( 990 )   The myoglobin (Mb)-intercalated magadiite nano-composite (Mb-magadiite) was successfully obtained by the exfoliation-reassembly method under mild conditions and was used to catalyze the oxidation of o-phenylenediamine in organic solvents with different hydrophobicities. The results showed that the immobilized myoglobin had higher catalytic activity and stability than free Mb in organic solvents with moderate hydrophobicities. The effects of the organic solvents on the catalytic performance of the immobilized myoglobin were also discussed.

Select

Effect of BaO on the Performance of Pd/Al2O3 Catalyst for H2O2 Production from Anthraquinone Hydrogenation DU Shuwei;WANG Rong*;LIN Bingyu;WEI Kemei 2008, 29 (5):  463-467.  Abstract ( 2379 )   [Full Text(HTML)] () PDF (312KB) ( 807 )   A series of Pd/δ,θ-Al2O3 catalysts containing BaO for anthraquinone hydrogenation to produce H2O2 were prepared by the impregnation method. The effect of barium oxide on the performance of Pd/δ,θ-Al2O3 catalyst was investigated byX-raydiffraction, scanning electron microscopy, nitrogen adsorption, H2-O2 titration, and electron probe microanalysis techniques. The results showed that barium oxide was a good promoter of the Pd/δ,θ-Al2O3 catalyst for the reaction. The addition of a proper amount of barium oxide could inhibit the growth of alumina crystals at high temperature, increase the catalyst surface area, improve the Pd dispersion, increase the Pd concentration on the catalyst surface, and decrease the Pd layer thickness. The addition of 3% BaO increased the catalyst activity by about 25%.

Select

One-Pot Synthesis of Mesoporous Fe-SBA-15 and Its Catalytic Performance for Friedel-Crafts Benzylation LIU Sen;DU Yunchen;XIAO Ni;ZHANG Yonglai;JI Yanyan;XIAO Fengshou* 2008, 29 (5):  468-472.  Abstract ( 2548 )   [Full Text(HTML)] () PDF (299KB) ( 877 )   Mesoporous Fe-SBA-15 samples with different Si/Fe ratios were prepared by one-pot synthesis using urea as a self-adjustor for pH values. The XRD patterns and nitrogen adsorption-desorption isotherms showed that the samples had similar mesoporous structure to SBA-15. The UV-Vis spectra showed that the iron atoms in the samples calcined at 550 ℃ were mainly tetrahedrally coordinated. The activity test results showed that the samples exhibited excellent catalytic performance in Friedel-Crafts benzylation of aromatics with benzyl chloride. For example, the Fe-SBA-15 samples took20-70min for the complete conversion of benzyl chloride with 97.8%-100% selectivity for diphenylmethane under the conditions of 70 ℃ and benzene/benzyl chloride molar ratio of 14.4. The conversion of benzyl chloride increased with increasing reaction temperature and iron content, whereas the time required for complete conversion of benzyl chloride increased with the decrease of the molar ratio of benzene to benzyl chloride.

Select

Preparation of β-MnO2 Nanobelt and Its Electrocatalytic Activity for Oxygen Reduction YUAN Zhongzhi*;WANG Hui;WANG Li;GUAN Juying;XIAO Xin 2008, 29 (5):  473-476.  Abstract ( 2633 )   [Full Text(HTML)] () PDF (295KB) ( 1041 )   Manganese oxide was synthesized by the hydrothermal method through oxidizing MnSO4 withHMnO4at 150 ℃ using cetyltrimethylammonium bromide as template.X-raydiffraction and scanning electron microscopy showed that the product was β-MnO2 nanobelt. The β-MnO2 nanobelt and electrolytic manganese dioxide (EMD) were used as catalyst to make air diffusion electrodes by mixing activated carbon and polytetrafluoroethylene. In6 mol/LKOH aqueous solution, current-potential polarization curves showed that the air electrode potential with β-MnO2 nanobelt catalyst was more positive by 30-60 mV than that of EMD, and the optimal content of β-MnO2 nanobelts in the electrocatalyst was 35%. At the typical current density 40 mA/cm2 of a Zn/air battery, the cell with the β-MnO2 nanobelt catalyst had stable discharge voltage up to 1.12 V.

Select

Partial Oxidation of Methane over Ni/Al2O3 Catalyst Calcined at Ultrahigh Temperatures CHEN Yongdong;CHEN Yaoqiang;MEI Dajiang;ZHANG Lijuan;DONG Wenping;CAO Hongyan;CHEN Hong;GONG Maochu* 2008, 29 (5):  477-481.  Abstract ( 2007 )   [Full Text(HTML)] () PDF (318KB) ( 858 )   The Ni/Al2O3 catalyst calcined at ultrahigh temperatures (1200-1400 ℃) was used in partial oxidation of methane (POM), and the Ni/Al2O3 catalyst retained high activity for POM after reduction. TheX-raydiffraction result indicated that NiAl2O4 was formed when the catalyst was calcined at ultrahigh temperatures, and there was no phase transition in the temperature range. After the catalyst was reduced by H2 at 950 ℃, most of Ni in the catalyst existed as Ni0, and the crystal size of Ni0 was similar, which was confirmed by transmission electron microscopy. The excellent performance of the Ni/Al2O3 catalyst calcined at ultrahigh temperatures for the POM reaction was attributed to both the reducibility of NiAl2O4 and the similar crystal size of Ni0. The higher the calcination temperature, the higher the reduction temperature for NiAl2O4.

Select

Crotonaldehyde Hydrogenation over CuO/SBA-15 Catalyst WANG Yuejuan;WANG Xueli;XIE Guanqun;LU Jiqing;JIN Weiyang;LIU Xijing;LUO Mengfei* 2008, 29 (5):  482-488.  Abstract ( 2012 )   [Full Text(HTML)] () PDF (422KB) ( 950 )   CuO catalysts supported on SBA-15 were prepared by chelating Cu2+with γ-aminopropyltrimethoxysilane (APTS) on the SBA-15 support and were tested for selective hydrogenation of crotonaldehyde. The CuO/SBA-15 catalysts with different CuO loadings were characterized byX-raydiffraction, N2 sorption, and hydrogen temperature-programmed reduction (H2-TPR). N2 sorption results showed that the samples maintained a fine 2D-hexagonal structure after the CuO was loaded, whereas the BET surface area and pore volume decreased with increasing Cu content. H2-TPR results revealed that there were three Cu species: finely dispersed CuO, bulk CuO, and Cu2+ions incorporated into the framework of SBA-15. Catalytic activity of each species was evaluated. The finely dispersed CuO had the highest activity, and the bulk CuO had medium activity, while the Cu2+in the SBA-15 framework was inactive in the reaction. These indicated that the finely dispersed Cu species were the active phase for the reaction. Furthermore, the catalyst calcined under N2 instead of air could increase the content of the finely dispersed CuO, which could consequently enhance the catalytic activity.

Select

Research Advances in Reaction Mechanism for Pd-Catalyzed Oxidative Carbonylation of Phenol to Diphenyl Carbonate LIU Min;WU Yuanxin;DU Zhiping*;YUAN Hua;GE Junwei 2008, 29 (5):  489-496.  Abstract ( 2424 )   [Full Text(HTML)] () PDF (453KB) ( 1145 )   Advances in the reaction mechanism for Pd-catalyzed oxidative carbonylation of phenol to diphenyl carbonate were reviewed. The validation of the reaction mechanism and how to realize the efficient recycle of the Pd-catalyzed system were introduced in detail. The catalytic mechanism for the oxidative carbonylation of phenol to diphenyl carbonate showed that diphenyl carbonate was produced by the insertion of CO into thePd-Obond and subsequent reductive elimination of intermediate Pd(COOPh)(OPh). The aggregation of Pd0 could be reduced and the regeneration rate of active Pd2+from Pd0 could be improved to accelerate the catalytic recycle by the addition of ligands and redox promoters into the Pd catalyst. The problems existing in the reaction system were summarized, and the direction for research and development of the catalyst system was pointed out.

Select

Aging of Noble Metal Catalysts in Low Temperature Fuel Cells CHEN Weimin*;XIN Qin;SUN Gongquan 2008, 29 (5):  497-502.  Abstract ( 1855 )   [Full Text(HTML)] () PDF (232KB) ( 980 )   Catalyst aging is one of the most important factors that results in the performance losses in fuel cells. For low temperature fuel cells, the aging of noble metal catalysts manifests itself in the growth of catalyst particles, the oxidation changing of noble metals, the migration and loss of catalyst components, and the corrosion of carbon supports. In this paper, the latest progresses in the aging of noble metal catalysts in low temperature fuel cells were reviewed, and the four factors responsible for the catalyst aging were discussed.