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2002, Vol. 11, No. 1　Online: 2002-03-30

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Reviews

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2002--Emergence of the Gas-to-Liquids Industry: a Review of Global GTL Developments T. H. Fleisch;R. A. Sills;M. D. Briscoe 2002, 11 (1): 1-14.  摘要 ( 7684 )   PDF(917KB) ( 3528 )   This paper reviews the status of the gas-to-liquids (GTL) industry | including current commercial plants, announced projects and the technologies that are likely to be implemented in these future projects. Today, only 35,000 B/D of GTL products (0.1% of market) are manufactured from commercial gas-based plants. Advances in technology have lowered the cost of plants to the point where GTL plants can be profitable at crude oil prices of $16/B . The advanced stage of development of several proposed GTL projects and attractive integrated economics, for both the gas eld and plant, show that GTL can be a signicant alternative for monetizing natural gas in the 21st century. GTL technologies includes more than Fischer{Tropsch technology and extends to other liquid fuels, especially in the oxygenate family (methanol, dimethyl ether, etc.).

Articles

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Partial Oxidation of Methane to Formaldehyde over Superfine Mo/ZrO2 Catalysts Xin Zhang;Dehua He;Qijian Zhang;Qing Ye;Qiming Zhu 2002, 11 (1): 15-17.  摘要 ( 8901 )   PDF(238KB) ( 1717 )   Superfine Mo/ZrO2 catalysts were prepared for partial oxidation of methane to HCHO and characterized by BET, XRD, LRS, H2-TPR and XPS. Mo existed mainly in the form of Zr(MoO4)2, and the catalytic performance and physicochemical properties of the Mo/ZrO2 catalysts were closely related to this species.

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Study on Bifunctionality of Mo/HZSM-5 Catalysts for Methane Dehydro-Aromatization Lingling Su;Yide Xu;Xinhe Bao 2002, 11 (1): 18-27.  摘要 ( 9238 )   PDF(456KB) ( 1907 )   Abstract: The optimum Mo/[H+] ratio per unit cell of the active precursors in Mo/HZSM-5 catalysts for methane dehydro-aromatization, measured by 1H MAS NMR, was found to be about 1 when adjusting the acid sites by altering either the SiO2/Al2O3 ratios or the Mo loading. This implies that a concerted interaction between the Mo species and the Bronsted acid sites probably features the bifunctionality of the Mo/HZSM-5 catalyst. On the other hand, it was found that the driving force for Mo species to move into the HSZM-5 zeolite channels and the interaction between the Mo species and the Bronsted acid sites are closely and proportionably related with the amount of Bronsted acid sites per unit cell.

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Reactions in a Mixture of CH4 and CO2 under the Action of Microwave Discharge at Yunpeng Xu;Zhijian Tian;Zhusheng Xu;Liwu Lin 2002, 11 (1): 28-32.  摘要 ( 7636 )   PDF(274KB) ( 2074 )   Abstract: Reactions between CH4 and CO2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor. The main products were CO and H2, while acetylene and ethylene were also found in the products. Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst. Eects of CO2/CH4 molar ratio and total ow rate of the feed gas on the reaction were also investigated.

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Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst L. Late;E. A. Blekkan 2002, 11 (1): 33-42.  摘要 ( 8310 )   PDF(472KB) ( 3048 )   The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550oC over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts for the dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at 10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, the only by-products were CO and CO2. The reaction rate of propane was found to be first order in propane and close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate determining step. The activation energy of the conversion of propane was found to be 122±6 kJ/mol.

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Propane Aromatization over Mo/HZSM-5 Catalysts Junwei Wang;Maoqing Kang;Zhixin Zhang;Xinkui Wang 2002, 11 (1): 43-50.  摘要 ( 9110 )   PDF(328KB) ( 2063 )   Impregnation, mechanical mixing and hydrothermal treatment methods were used to introduce molybdenum species into the HZSM-5 zeolite. The structure and surface acidity of the catalysts were studied by means of XRD, FT-IR, NH3-TPD, TPR and XPS. The eects of Mo content and reaction time on stream on the aromatization of propane were investigated. It was found that the performance of the Mo/HZSM-5 catalyst prepared by the hydrothermal treatment method was much better than that of the other two catalysts. For example, under the reaction conditions of 823 K and 600 h-1 propane conversion and aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17% and 78.56%, respectively. XRD and XPS results showed that the Mo species in the catalysts prepared by hydrothermal treatment were highly dispersed on the surface of the HZSM-5, and larger amounts of them could penetrate into the HZSM-5 channel, as compared with the other two kinds of catalysts. These factors may be responsible for their high activities for propane aromatization. IR and NH3-TPD studies indicated that the number of Bronsted acid centers decreased and the Lewis acid centers increased after Mo was introduced into the HZSM-5 zeolite.

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Synthesis of Acetic Acid on Pd-H4SiW12O40-Based Catalysts by Direct Oxidation of Xinping Wang;Kegong Fang;Jianlu Zhang;Tianxi Cai 2002, 11 (1): 51-56.  摘要 ( 9143 )   PDF(236KB) ( 1923 )   Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse dierential reactor. From the performance of the catalysts with different compositions and configurations, it is proposed that acetic acid is predominantly produced via an intermediate of acetaldehyde. This can be easily confirmed by comparing the product distributions in the integral and the dierential reactors. The active sites for acetic acid formation are considered to exist mainly at the boundaries between the H4SiW12O40 and the Pd particles. The Pd-based catalysts reduced by H2/N2 have higher activities than those reduced by hydrazine, as explained by the degree of Pd dispersion obtained from the characteristics of hydrogen chemical adsorption. It was found that the Pd-Se-SiW12/SiO2 catalyst with selenium tetrachloride as a precursor was more active than that with potassium selenite, and that the acetic acid yield can be greatly increased by adding a suitable amount of dichloroethane (C2H4Cl2/C2H4 mole ratio=0.03) to the reactants.

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Synthesis of Diethyl Oxalate by a Coupling-Regeneration Reaction of Carbon Monoxide Fandong Meng;Genhui Xu;Baowei Wang;Xinbin Ma 2002, 11 (1): 57-62.  摘要 ( 8404 )   PDF(354KB) ( 1805 )   This article describes a process for the synthesis of diethyl oxalate by a coupling reaction of carbon monoxide, catalyzed by palladium in the presence of ethyl nitrite. The kinetics and mechanism of the coupling and regeneration reaction are also discussed. This paper presents the results of a scale-up test of the catalyst and the process based on an a priori computer simulation.

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Adaptation of Cu/ZnO/Al2O3 to Temperature Change in Methanol Synthesis from CO2 Jialin Tao;Ki-Won Jun;Kyu-Wan Lee 2002, 11 (1): 63-69.  摘要 ( 7706 )   PDF(360KB) ( 1880 )   The induction behavior in CO2 hydrogenation was studied by varying the reaction temperature to investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change. The results indicated that a used catalyst had a tendency to keep the last running state in new reaction conditions for MeOH formation, and that this tendency was related to the dierence in Cu/Cun+ ratio caused by CO2 and CO produced at dierent reaction temperatures. However, the reverse water-gas shift reaction (RWGS) induced at four temperatures was completely dierent from that of methanol synthesis. It implied that the two so-called competitive reactions in CO2+H2, RWGS and methanol synthesis, have dierent active centers.

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Kinetics of the Oxidative Dehydrogenation of Isobutane over Cr2O3/La2(CO3)3 Yanping Sun;Tracey A. Robson;Trevor C. Brown 2002, 11 (1): 70-78.  摘要 ( 7894 )   PDF(367KB) ( 1990 )   The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investi- gated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300oC, temper- ature uctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.

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Dealuminated ZSM-5 Zeolite Catalyst for Ethylene Oligomerization to Liquid Fuels Nor Aishah Saidina Amin;Didi Dwi Anggoro 2002, 11 (1): 79-86.  摘要 ( 9363 )   PDF(390KB) ( 2682 )   Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio re ects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for dierent periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio aected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.