过刊目录

2003, Vol. 12, No. 2　Online: 2003-06-30

上一期    下一期

全全选选:

导出引用 EndNote Ris BibTeX

隐藏/显示图片

Articles

Select

Recent Progress in Direct Partial Oxidation ofMethane to Methanol Qijian Zhang;Dehua He;Qiming Zhu 2003, 12 (2): 81-89.  摘要 ( 7678 )   PDF(257KB) ( 3960 )   The direct conversion of methane to methanol has attracted a great deal of attention for nearly a century since it was rst found possible in 1902, and it is still a challenging task. This review article describes recent advancements in the direct partial oxidation of methane to methanol. The history of direct oxidation of methane and the diculties encountered in the partial oxidation of methane to methanol are brie y summarized. Recently reported developments in gas-phase homogeneous oxidation, heterogeneous catalytic oxidation and liquid phase homogeneous catalytic oxidation of methane are reviewed.

Select

NOx-Catalyzed Gas-Phase Activation of Methane: the Formation of Hydrogen Chaoxian Xiao;Zhen Yan;Yuan Kou 2003, 12 (2): 90-92.  摘要 ( 10240 )   PDF(278KB) ( 1730 )   NOx-catalyzed oxidation of methane without a solid catalyst was investigated, and a hydrogen selectivity of 27% was obtained with an overall methane conversion of 34% and a free O2 concentration of 1.7% at 700oC.

Select

Density Functional Investigations into the Adsorption of Methanol on Isomorphously Substituted ZSM-5 Shuping Yuan;Jianguo Wang;Yongwang;Li;Haijun Jiao 2003, 12 (2): 93-97.  摘要 ( 9451 )   PDF(932KB) ( 1942 )   The adsorption of methanol in the acid sites of zeolites has attracted a great deal of attention because of its relevance to the industrial methanol to gasoline conversion process. In this work, the B3LYP hybrid density functional method was used to investigate the adsorption behavior of methanol on Bronsted acid sites in B, Al, Ga and Fe isomorphously substituted ZSM-5 zeolites. The optimized structures reveal a physisorbed methanol interacting with the zeolite framework through two hydrogen bonds. The order of the computed adsorption energy correlates with the acid strength of the isomorphously substituted ZSM-5: B-ZSM-5≤Fe-ZSM-5

Select

Nickel Complexes Bearing Bidentate SchiBase as Ethylene Oligomerization Catalysts Jianjun Yi;Xugeng Huang;Wei Zhang;Xiaoyu Hong;Zhenhua Jing 2003, 12 (2): 98-104.  摘要 ( 7489 )   PDF(294KB) ( 2176 )   Several nickel complexes [N,N]NiBr2, in which [N,N] indicates bidentate nitrogencontaining ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine (C18H22N2); 2: N-(2,6- diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C19H24N2); 3: N-(2,4,6-trimethylphenyl)pyridine- 2-carboxaldimine(C15H16N2); 4: N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldimine (C16H18- N2) were synthesized. Some of the nickel complexes exhibit high activity for ethylene oligomerization in the presence of an organoaluminum activator. The main factor aecting the activity and the structure of oligomers is the steric eect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalysts showed higher activities and produced oligomers with higher molecular weight than Et2AlClactivated ones. The oligomerization in toluene rather than hexane results in much higher activity, and the oligomers produced in toluene have relatively high molecular weight. With activation of MAO or Et2AlCl, the [N,N]NiBr2 system tended to produce highly branched oligomers with low a-olefin content, but the a-olefin content could be increased by changing the reaction conditions.

Select

Effect of Drying Methods on the Structure and Combustion Activity of Mn-Substituted Hexaaluminate Catalysts Jinguang Xu;Zhijian Tian;Junwei Wang;Yunpeng Xu;Zhusheng Xu;Liwu Lin 2003, 12 (2): 105-112.  摘要 ( 7469 )   PDF(504KB) ( 1857 )   Conventional oven drying (COD) and supercritical drying (SCD) methods were applied to the preparation of Mn-substituted hexaaluminate (BaMnAl11O19-a ) catalysts. The effect of drying methods on phase composition, specific surface area, pore structure, reduction behavior of Mn3+ ions, and combustion activity of the samples was investigated. The homogenous mixing of the components in the sol-gel process could be maintained by SCD, and the hexaaluminate phase was almost the only phase of the resulting materials after calcination. H2-TPR revealed that the Mn3+ ions in the sample obtained by SCD were easier to be reduced than that by COD. Moreover, the samples obtained by SCD have higher surface area, narrower pore size distribution, and higher combustion activity than those obtained by COD.

Select

Structure and Properties of Sol-Gel Derived CuNiMnZrO2 Catalysts for CO Hydrogenation Zhongyi Ma;Cheng Yang;Run Xu;Wei Wei;Wenhuai Li;Yuhan Sun 2003, 12 (2): 113-118.  摘要 ( 9090 )   PDF(673KB) ( 2189 )   Abstract: Two CuNiMnZrO2 catalysts (crystallized or non-crystallized) were prepared by co-hydrolyzing zirconium n-propoxide with Cu(NO3)2, Mn(NO3)2 and Ni(NO3)2 in an ethanol solution in the presence of diglycol. The physical and chemical properties of the catalysts were characterized using BET, XRD, TEM, XPS and CO-DRIFT techniques. It was found that the non-crystallized CuNiMnZrO2 catalyst demonstrated highly dispersed active phases and high activity for CO adsorption, which resulted in good performance for synthesis of higher alcohols in CO hydrogenation compared to crystallized CuNiMnZrO2.

Select

Surface Acidity/Basicity and Catalytic Reactivity of CeO2/-Al2O3 Catalysts for the Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene Xin Ge;Shenghua Hu;Qing Sun;Jianyi Shen 2003, 12 (2): 119-122.  摘要 ( 7977 )   PDF(291KB) ( 2391 )   Dehydrogenation of ethane to ethylene in CO2 was investigated over CeO2/ -Al2O3 catalysts at 700oC in a conventional ow reactor operating at atmospheric pressure. XRD, BET and microcalori- metric adsorption techniques were used to characterize the structure and surface acidity/basicity of the CeO2/r-Al2O3 catalysts. The results show that the surface acidity decreased while the surface basicity increased after the addition of CeO2 to r-Al2O3. Accordingly, the activity of the hydrogenation reaction of CO2 increased, which might be responsible for the enhanced conversion in the dehydrogenation of ethane to ethylene. The highest ethane conversion obtained was about 15% for the 25%CeO2/r-Al2O3. The selectivity to ethylene was high for all the CeO2, r-Al2O3 and CeO2/ r-Al2O3 catalysts.

Select

Characterization and Activity of Cr, Cu and Ga Modified ZSM-5 for Direct Conversion of Methane to Liquid Hydrocarbons Nor Aishah Saidina Amin;Didi Dwi Anggoro 2003, 12 (2): 123-119.  摘要 ( 9336 )   PDF(428KB) ( 2491 )   Direct conversion of methane using a metal-loaded ZSM-5 zeolite prepared via acidic ion exchange was investigated to elucidate the roles of metal and acidity in the formation of liquid hydrocarbons. ZSM-5 (SiO2/Al2O3=30) was loaded with dierent metals (Cr, Cu and Ga) according to the acidic ion-exchange method to produce metal-loaded ZSM-5 zeolite catalysts. XRD, NMR, FT-IR and N2 adsorption analyses indicated that Cr and Ga species managed to occupy the aluminum positions in the ZSM-5 framework. In addition, Cr species were deposited in the pores of the structure. However, Cu oxides were deposited on the surface and in the mesopores of the ZSM-5 zeolite. An acidity study using TPD-NH3, FT-IR, and IR-pyridine analyses revealed that the total number of acid sites and the strengths of the Bronsted and Lewis acid sites were signicantly dierent after the acidic ion exchange treatment. Cu loaded HZSM-5 is a potential catalyst for direct conversion of methane to liquid hydrocarbons. The successful production of gasoline via the direct conversion of methane depends on the amount of aluminum in the zeolite framework and the strength of the Bronsted acid sites.

Select

Study of a Catalyst for Energy-Saving Natural Gas Steam Reforming Chunde Niu;Daowen Chong;Yuchun;Cheng;Shuren Hao 2003, 12 (2): 135-138.  摘要 ( 10751 )   PDF(243KB) ( 1889 )   The DS-1 catalyst for energy-saving natural gas steam reforming was prepared by using potash as a carbon-resistant additive and adding rare earth oxide. The catalyst demonstrated good reducibility, carbon resistance, activity and stability in aging tests and 500 h stability tests at low water/carbon ratios.

Select

Activity Enhancement of Vanadium Catalysts with Ultrasonic Preparation Process for the Oxidation of Sulfur Dioxide Zhenxing Chen;Honggui Li;Lingsen Wang 2003, 12 (2): 139-144.  摘要 ( 8625 )   PDF(299KB) ( 2172 )   The eect of ultrasonic cavitations on the activity of vanadium catalysts at low temperatures for the oxidation of sulfur dioxide, in which rened carbonized mother liquor had been added, was investigated. Twenty minutes were needed to produce obvious cavitations when the catalyst raw material was treated in the 50 W ultrasonic generator. However, only 10 minutes would be needed in a 150 W ultrasonic generator. The higher the temperature of the wet material, the less time was needed to produce cavitations, and the optimal temperature was 60oC . The water content in the wet material mainly aected the quantity of cavitations. Ls-8 catalyst was prepared using ultrasonic. Its activity for conversion of SO2 reached to 52.5% at 410oC and 4.2% at 350oC. The dierential thermal analyses indicate that both endothermic peaks and exothermic peaks noticeably shifted forward compared with Ls catalyst prepared without ultrasonic, and SEM results show a uniform pore size distribution for Ls-8 catalyst.

Select

Influence of Pretreatment Conditions on Methane Aromatization Performance of Mo/HZSM-5 and Mo-Cu/HZSM-5 Catalysts Yiping Zhang;Dongjie Wang;Jinhua Fei;Xiaoming Zheng 2003, 12 (2): 145-149.  摘要 ( 8690 )   PDF(260KB) ( 2168 )   Mo/HZSM-5 is a good catalyst for methane aromatization, and the reaction performance of Mo/HZSM-5 and Cu modified Mo/HZSM-5 catalysts under various pretreatment conditions has been stud- ied. The results indicate that the catalyst presented a distinguished catalytic activity, benzene selectivity and a high stability when the bed temperature was raised in N2 atmosphere.