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2003, Vol. 12, No. 1　Online: 2003-03-30

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Reaction Chemistry of W-Mn/SiO2 Catalyst for the Oxidative Coupling of Methane Shuben Li 2003, 12 (1): 1-9.  摘要 ( 9531 )   PDF(349KB) ( 3759 )   Abstract: Reaction chemistry of the OCM reaction on W-Mn/SiO2 catalyst has been reviewed in this account. Initial activity and selectivity, stability in a long-term reaction, reaction at elevated pressures and a modelling test in a stainless-steel uidized-bed reactor show that W-Mn/SiO2 has promising performance for the development of an OCM process that directly produces ethylene from natural gas. A study on surface catalytic reaction kinetics and used catalyst structure characterization revealed a possible reason why C2 and COx selectivity changed during the long-term reaction. Further improvement of the catalyst composition and preparation method should be a future direction of study on OCM reaction over W- Mn/SiO2 catalyst.

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Review of Directly Producing Light Olens via CO Hydrogenation Chong Wang;Longya Xu;Qingxia Wang 2003, 12 (1): 10-16.  摘要 ( 9530 )   PDF(285KB) ( 2981 )   Directly making light olens via CO hydrogenation is a promising process to obtain a nonpetroleum based supply of alkenes. Limited by the ASF distribution function of Fischer-Tropsch synthesis, the yield of light olefins (C2-C4) can not reach the desired levels, which is a great challenge to overcome. Beginning with a brief introduction of F-T synthesis, this paper provides a review of current research, including thermodynamic analysis, the ASF distribution function, the reaction performance of CO hydrogenation and slurry reactor studies. The problems currently faced by this research area are presented at the end of the article.

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CO2 Reforming of CH4 over Nickel and Cobalt Catalysts Prepared from La-Based Perovskite Precursors Jianjun Guo;Hui Lou;Yinghong Zhu;Xiaoming Zheng 2003, 12 (1): 17-22.  摘要 ( 9210 )   PDF(356KB) ( 2441 )   Four perovskite-type complex oxides (LaNiO3, La2NiO4, LaCoO3 and La2CoO4) were successfully prepared using two sol-gel methods, the Pechini method (PC) and the citric acid complexing method (CC). The catalysts were characterized by XRD and TPR. After reduction, the activity of the catalysts in the CO2 reforming of methane was tested. Ni-based catalysts from La2NiO4 precursors were the most active and stable catalyst after calcination above 850oC, which gave a methane conversion of 0.025 mmol/(g.s) for those prepared by the PC method and 0.020 mmol/(g.s) by the CC method. It was proposed that the well-defined structure and lower reducibility is responsible for the unusual catalytic behavior observed over the pre-reduced La2NiO4 catalyst.

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Investigation on the Performance of Supported Molybdenum Carbide for the Partial Oxidation of Methane Quanli Zhu;Jian Yang;Jiaxin Wang;Shengfu Ji;Hanqing Wang 2003, 12 (1): 23-30.  摘要 ( 8917 )   PDF(680KB) ( 2175 )   The performance of supported and unsupported molybdenum carbide for the partial oxidation of methane (POM) to syngas was investigated. An evaluation of the catalysts indicates that bulk molybdenum carbide has a higher methane conversion during the initial stage but a lower selectivity to CO and H2/CO ratio in the products. The rapid deactivation of the catalyst is also a significant problem. However, the supported molybdenum carbide catalyst shows a much higher methane conversion, increased selectivity and significantly improved catalytic stability. The characterization by XRD and BET specific area measurements depict an improved dispersion of molybdenum carbide when using alumina as a carrier. The bulk or the supported molybdenum carbide exists in the β-Mo2C phase, while it is transformed into molybdenum dioxide postcatalysis which is an important cause of molybdenum carbide deactivation.

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A Novel Sulded Mo/C Catalyst for Direct Vapor Phase　Carbonylation of Methanol at Atmospheric Pressure Feng Peng 2003, 12 (1): 31-36.  摘要 ( 8460 )   PDF(616KB) ( 2000 )   The direct carbonylation of methanol, without any halide in the feed as a promoter, is presented. A series of Mo catalysts supported on activated carbon, r-Al2O3 and SiO2 were prepared. The results show that the support greatly aects the Mo catalyst in the direct vapor-phase carbonylation of methanol, and activated carbon is the best supports of the investigated supports. In addition, the relationships between adsorptions of NH3 and CO and carbonylation of methanol were investigated. A novel sulfided Mo/C catalyst had high activity and selectivity for the vapor phase carbonylation of methanol to methyl acetate without the addition of a CH3I promoter to the feed. The reaction conditions were optimized at a reaction temperature of 573 K, a methanol concentration of 23 mol% and a carbon monoxide space velocity of 3,000 L/(kg h). Under these optimal conditions a methanol conversion of 50%, carbonylation selectivity of 80 mol%, and space-time yield of 8.0 mol/(kg h) were obtained. The active phase of this novel sulded Mo/C catalyst is the non-crystalline phase, and the active component is present as MoS2.5 on the surface of the activated carbon.

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Simultaneous Removal of COS and H2S at Low Temperatures over Nanoparticle α-FeOOH Based Catalysts Zhihua Gao;Chunhu Li;Kechang Xie 2003, 12 (1): 37-42.  摘要 ( 9303 )   PDF(294KB) ( 2003 )   Catalysts using α-FeOOH nanoparticles as the active ingredient were tested by a microreactor- chromatography assessing apparatus at atmospheric pressure between 25 and 60oC with a gas hourly space velocity of 10,000 h-1 , while the removal performance of H2S with catalysts was investigated using the thermal gravimetric method. The results show that the catalysts are highly active for COS hydrolysis at low temperatures (<60oC) and high gas hourly space velocity, and the highest activity can reach 100%. The catalyst is particularly stable for 12 h, and no deactivation is observed. Nanoparticle α-FeOOH prepared using hydrated iron sulfate shows higher COS hydrolysis activity, and the optimum calcination temperature for the catalyst is 260oC . In addition, the catalysts can remove COS and H2S simultaneously, and 60oC is favorable for the removal of H2S. The compensation eect exists in nanoparticle-based catalysts.

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Microkinetics of H2S Removal by Zinc Oxide in the Presence of Moist Gas Atmosphere Huiling Fan;Chunhu Li;Hanxian Guo;Kechang Xie 2003, 12 (1): 43-48.  摘要 ( 11244 )   PDF(369KB) ( 2194 )   The microkinetics of H2S removal by ZnO desulfurization in H2O-CO2-N2, H2O-CO-N2 and H2O-O2-N2 gas mixtures was studied by thermogravimetric analysis. Experiments were carried out with 100-120 mesh ZnO powder at temperatures from 473 K to 563 K. The results show that the kinetic behaviors of desulfurization could all be described by an improved shrinking-core model. The activation energies of the reaction and the diusion in dierent gas atmospheres were estimated.

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Properties and Characterization of Modified HZSM-5 Zeolites Renqing Lü;Hejin Tangbo;Qiuying Wang;Shouhe Xiang 2003, 12 (1): 56-62.  摘要 ( 10026 )   PDF(1759KB) ( 5378 )   Physicochemical and catalytic properties of phosphorus and boron modified HZSM-5 zeolites treated with 100% steam at 673 K were investigated. The acidity and distribution of acidic sites were stud- ied by infrared spectroscopy using pyridine as probe molecule and temperature programmed desorption (TPD) of ammonia. The structure of the samples was characterized by XRD, and the textural properties of the catalysts were determined by nitrogen isothermal adsorption-desorption measurements and scanning electron microscopy (SEM). The XRD results show that the modified samples have no novel crystalline phase, indicating a high dispersion of phosphorus and boron species. After treatment, the microporous volume and surface area of the samples markedly decrease, implying the blockage of the channel. The nitro- gen adsorption-desorption measurements suggest that the isothermal type of all samples is a combination of isothermal type I and IV, and all hysteresis loops resemble the H4-type in the IUPAC classification. The total acidity of the modified samples, determined by pyridine adsorption IR and TPD of ammonia, decreases in contrast to that of the parent HZSM-5. The conversion of n-heptane over P and B steam- modified HZSM-5 is higher than that of P and B-modified HZSM-5 zeolites but lower than that of the parent HZSM-5.

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In Situ Synthesis of NaY Zeolite with Coal-Based Kaolin Xinmei Liu;Zifeng Yan;Huaiping Wang;Yantuo Luo 2003, 12 (1): 63-73.  摘要 ( 8529 )   PDF(416KB) ( 2241 )   NaY zeolites were in-situ synthesized from coal-based kaolin via the hydrothermal method. The eects of various factors on the structure of the samples were extensively investigated. The samples were characterized by N2 adsorption, XRD, IR and DTG-DTA methods, and the results show that the crystallization temperature and amount of added water play an important role in the formation of the zeo- lite structure. The 4A and P zeolites are the competitive phase present in the resulting product. However, NaY zeolites with a higher relative crystallinity, excluding impure crystals and the well hydrothermal sta- bility, can be synthesized from coal-based kaolin. These zeolites possess a larger surface area and a narrow pore size distribution, and this means that optimization of this process might result in a commercial route to synthesize NaY zeolites from coal-based kaolin.

Research Notes

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Methanol Steam Reforming Catalysts for Fuel Cell Driven Electric Vehicles Yongfeng Li;Xinfa Dong;Weiming Lin 2003, 12 (1): 71-73.  摘要 ( 6917 )   PDF(197KB) ( 1847 )   Cu/ZnAlO catalysts derived from hydroxycarbonate precursors containing hydrotalcite-like layered double hydroxides (LDHs) were studied. The in uence on the performance of the catalysts was also studied when the Al in the Cu/ZnAlO catalyst was partly or completely replaced by Zr or Ce.