FT合成反应器概述

介绍ＦＴ合成反应器的研究进展，详细论述了工业化的高气速固定床、循环流化床和固定流化床反应器的基本原理和开发过程，分析了操作多数对高气速固定床Ｆｒ合成反应结果的影响。并对固定床、流化床和浆态床反应器的结构、生产能力、原料及产物组成和操作条件等进行了比较。     

Co基费托合成催化剂研究进展

概述了co基费托合成催化剂的制备方法,介绍了Co盐种类、浸渍方法、浸渍溶液的pH值、Co盐溶剂、金属Co负载量和干燥温度等制备条件对Co基催化剂活性的影响,介绍了Co基催化剂的改性方法。并在此基础上对Co基催化剂今后的研究发展方向进行了展望。     

A comprehensive mathematical model for the Fischer-Tropsch synthesis in well-mixed slurry reactors

A new product distribution quasi-steady-state model was proposed for the Fischer-Tropsch (FT) synthesis in slurry reactors, being applicable to their transient simulation. It may consider two chain propagation mechanisms or sites and the possibility of 1-olefin readsorption with secondary reactions, recovering the Anderson-Schulz-Flory (ASF) model, the two superimposed ASF model and the 1-olefin readsorption model as particular cases. The hydrocarbon compounds were lumped according to the number of carbon atoms in their molecules for the paraffin and 1-olefin families. The phases were assumed to be well mixed in the reactor and transient mass balances were performed for each component, allowing simulation of operation in constant liquid level and no liquid withdrawal conditions. A rigorous calculation of the vapor-liquid equilibrium (VLE) through cubic equations of state was used to describe the phase behavior. Rate expressions for the FT and the water gas shift reactions are taken from the literature and expressed in terms of fugacities. Simulation results showed that the inclusion of both the olefin readsorption and the two chain propagation mechanisms may explain the anomalies present in experimental hydrocarbon product distribution. Moreover, the effect of phase-equilibrium modeling on product distribution simulation was shown to be slightly important in the conditions analyzed. Compositional lumping schemes for the hydrocarbons were investigated to speed up the simulations. Results showed that lumping can speed up computations up to 250 times with negligible loss of accuracy.     

Fischer-Tropsch synthesis on Fe-Mn ultrafine catalysts

The Fischer-Tropsch (FT) synthesis on Fe-Mn ultrafine catalysts prepared by a special degradation method of Fe-Mn complexes is presented. The effects of preparation method and Mn content on the FT performance are examined and the active phases and the role of Mn are elucidated.     

费托合成技术及其研究进展

综述了费托合成煤间接液化技术的发展历程及其最新进展,重点介绍了费托合成过程中的核心问题,主要包括费托合成工艺、反应器和费托合成催化剂;讨论了高低温费托合成产物的特性与加工方案,展望了费托合成煤间接液化技术的工业应用前景和产业化方向。     

Fischer-Tropsch合成钴基催化剂研究进展

综述了近年来钴基催化剂在费托合成反应中的研究进展.重点评述了钴源、负载量、载体、助剂、制备方法、焙烧和还原条件等因素在负载型钴基催化剂制备过程中对催化剂活性、选择性控制等方面的影响,概述了钴基催化剂在费托合成反应中的催化机理,并对今后催化剂的研究提出了一点建议.     

Specific inhibition as the kinetic principle of the Fischer-Tropsch synthesis

FT CO-hydrogenation on cobalt catalysts has been performed in a well stirred continuously operated slurry reactor with and without addition ofn-octene-1 at different CO partial pressures. Kinetic data have been determined with the help of a mechanistic model. Increasing CO partial pressure inhibits individual reaction steps selectively, in particular associative methane desorption, the steps of chain termination (as paraffins and olefins likewise), whereas in secondary olefin conversion hydrogenation is inhibited drastically, however double bond shift is even promoted. Secondary hydrogenation is concluded to proceed on different sites than chain growth.     

Catalyst and process scale-up for Fischer-Tropsch synthesis

Liquid-phase Fischer-Tropsch technology was demonstrated in a bubble column at DOE's Alternative Fuels Development Unit. The 19-day run demonstrated the technology at a pilot scale and addressed scale-up issues such as catalyst activation, catalyst performance and hydrodynamics. The catalyst performance and reactor hydrodynamics were in line with expectations throughout the run.     

Fischer-Tropsch synthesis over freshly reduced iron-ruthenium alloys

Surface analysis of unsupported FeRu alloys was accomplished using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) after the catalysts were reduced in flowing H₂ at 673 K for 4 h in a pretreatment chamber and introduced directly into the UHV instrument without exposure to the air. XPS lines show Fe and Ru to be metallic after reduction. Quantitative analysis of the first several layers using XPS shows enrichment of the surface region in Fe as expected. Analysis of the secondary ion emission as a function of composition shows a marked decrease in the Ru⁺ emission from 97Ru3Fe compared to the pure Ru catalyst, suggesting alteration of the electronic properties of the surface upon addition of a small amount of Fe. Semiquantitative analysis of the uppermost layer using SIMS suggests greater Fe enrichment in the first layer than the average enrichment calculated from XPS for the first several layers. The initial activity and selectivity of the catalysts for Fischer-Tropsch synthesis were measured at 1 atm and 573 K in 3.3H₂ + CO at conversions below 3%. Selectivity to methane decreases through a minimum with increasing Fe content in the first layer. High propylene and ethylene yields were found for the alloy catalysts. A marked increase in the selectivity of the catalysts to propylene and, particularly, ethylene for 3Fe97Ru compared to pure Ru correlates with the sharp changes in SIMS yields.     

The carburization kinetics of iron-based Fischer-Tropsch synthesis catalysts

The carburization kinetics of iron supported by silica gel was studied in Fischer-Tropsch synthesis. The effect of several variables (content of K and Cu promoters and partial pressure of CO and H₂) on the rate of carburization was examined. It was found that the maximum of carburization rate coincides with a minimum of the hydrocarbons production rate. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enhancing gas phase Fischer-Tropsch synthesis catalyst design

This paper presents the results on the research in the development of a Fe-based catalyst with Co as a co-catalyst, and Ru and ZnO as promoters. The catalytic performance of these materials for FT synthesis was investigated in the gas phase employing a fixed bed reactor system. The Fe-Zn-K/γ-Al₂O₃ catalyst performance was used as the benchmark. The data show that by varying the process conditions (T, P, flow rate), it is possible to achieve a narrow distribution of the liquid products. The effect of co-catalysts and promoters such as K and Zn are also presented. The results from a series of Fe₄Co₁Zn_0.04 based catalysts for Fischer-Tropsch (FT) synthesis, in which the different amounts of Ru are incorporated showed that the addition of Ru suppressed the CH₄ formation at the cost of increasing the CO₂ selectivity. The newly designed catalysts showed significantly high activity towards CO conversion (>70%), along with low selectivity towards CO₂ (5-15%) and methane (ND - 3%). It is also shown that the support material plays a role in the selectivities obtained.     

Metal effects in the Fischer-Tropsch synthesis: Bond-order-conservation-morse-potential approach

We have applied the BOC-MP method to theoretically analyze the metal effects in the Fischer-Tropsch (FT) synthesis by calculating the energetics of conceivable elementary steps (the relevant heats of chemisorption and the reaction activation barriers) during CO hydrogenation over the periodic series Fe(110), Ni(111), Pt(111), Cu(111). The basic steps such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH₂ versus CO into the metal-alkyl bonds, and chain termination leading to hydrocarbons (alkanes versus -olefins) or oxygenates are discussed in detail. It is shown that the periodic trends in the ability of metal surfaces to dissociate chemical bonds and those to recombine the bonds are always opposite. In particular, we argue that metallic Fe is necessary to produce the abundance of carbidic carbon from CO but the synthesis of hydrocarbons and oxygenates can effectively proceed only on carbided Fe surfaces which resemble the less active metals such as Pt. More specifically, we project that the C-C chain growth should occur predominantly via CH₂ insertion into the metal-alkyl bond and the primary FT products should be -olefins. These and other model projections are in agreement with experiment.     

The mechanism of chain growth in the Fischer-Tropsch hydrocarbon synthesis

It is proposed that the slow step in chain growth during the Fischer-Tropsch hydrocarbon synthesis is the formation of an adsorbed ethylidene species from two adsorbed methylenes. Addition of a further methylene species gives a diadsorbed C₃H₆ entity, which leads to a singly attached carbonium ion. A 1,2 hydrogen shift then forms a methyl substituted ethylidene species, which is available for further polymerisation. Further hydrogen shift may occur, yielding an olefin and terminating the chain growth. The extent of chain branching is dictated by the relative stability of secondary and primary carbonium ions, as previously proposed by McCandlish, (J. Catalysis 83 (1983) 362).     

费托合成反应体系的热力学计算与分析

利用Benson基团贡献法和ABWY法估算了费托合成产物的标准生成焓、标准熵和摩尔定压热容,对费托合成反应体系的热力学性质进行了详尽的计算,得到不同反应温度下的反应焓、吉布斯自由能以及反应平衡常数等热力学性质。分析了不同反应步骤的热力平衡与限度,对反应生成烷烃、烯烃、含氧有机化合物的热力学可能性与生成顺序进行了判断,考察了温度和H2与CO摩尔比对合成气平衡转化率的影响。结果表明:费托合成反应是放热反应,低温时大部分反应在热力学上都能够自发地进行,并运行到很高的程度;高温时(大于635 K)生成烷烃、烯烃、醇及酸的大部分反应在热力学上不能自发进行;随着温度的升高,平衡转化率降低,随着H2与CO摩尔比的增大,平衡转化率升高;且所获的热力学数据对费托合成工艺研究及相关催化剂研发等具有重要的参考价值。     

费托合成反应器应用研究进展及展望

费托合成反应是强放热的气液固三相反应,为有效移热及提高目标产物产率,应加强费托合成反应器的研发,系统介绍了工业上几种费托合成反应器的特点、应用规模等,论述了近几年已经或有望进行工业化应用的几种费托合成反应器,如固定床反应器、流化床反应器、浆态床反应器等,并比较了各类反应器的优劣,最后对费托合成反应器的选型和发展提出了建议和展望。固定床反应器技术成熟,产品容易分离,催化剂损失少,但是移热效果较差;浆态床反应器,反应物混合均匀,移热效果好,但产品固液分离较为困难;流化床反应器可以在高温下运行,生产高价值的轻烃产物,但催化剂消耗较大。研究认为,如果目标产品是以分子质量较大的柴油和石蜡为主,建议选择浆态床反应器;如果目标产品是生产烯烃等化学品,建议选择固定流化床反应器。     

Liquid-vapor thermodynamic equilibrium in Fischer-Tropsch synthesis products

A modified Peng-Robinson equation of state is used to develop the methods for calculating the liquid-vapor thermodynamic equilibrium in Fischer-Tropsch synthesis products. The critical thermodynamic parameters of paraffin and olefin hydrocarbons with a number of carbon atoms higher than 20 are determined using the correlations proposed in the present paper. The calculated results are compared with literature data and the data obtained in the Integrated Research and Development Center.     

Methods for the Electrophoretic Shaping of Ceramic Products from Aqueous Slips of Inorganic Materials (A Review)

An overview of the state-of-the-art in the use of technologies for electrophoretic shaping of ceramic materials from aqueous slips of inorganic materials is presented and a critical analysis of both strengths and limitations is given. The need for more efforts in the improved production of large-sized preforms with irregular profile using advanced electrophoretic deposition techniques is emphasized.     

Cobalt Fischer-Tropsch synthesis: Deactivation by oxidation?

Cobalt catalysts as used in the Fischer-Tropsch synthesis (FTS) are relatively expensive (as compared to iron) and need to have a high metal dispersion and long life to be able to offer a good balance between cost and performance. The oxidation of nano-sized metallic cobalt to cobalt oxide during Fischer-Tropsch synthesis has long been postulated as a major deactivation mechanism. However, to date there is no consistent picture. This paper presents an extensive overview of the literature on this topic of deactivation by means of oxidation for unsupported as well as silica-, alumina- and titania-supported cobalt catalysts. Furthermore, it presents results on the deactivation of an industrial Co/Al₂O₃ catalyst as obtained by pseudo in situ X-ray diffraction, magnetic measurements and X-ray absorption near-edge spectroscopy. These analyses were performed to study the oxidation state of spent industrial Co/Al₂O₃ catalyst samples withdrawn from a slurry reactor operating under realistic FTS conditions, and it was concluded that oxidation can be ruled out as a major deactivation mechanism. Finally, these data together with all relevant literature were used to create a common view on the oxidation behaviour of metallic cobalt during FTS. The apparent discrepancies in literature on the oxidation behaviour of cobalt are most likely due to the lack of direct characterisation of the cobalt oxidation state and due to the comparison of catalysts with varying cobalt crystallites sizes, compared at different reactor partial pressures of hydrogen and water (P_H2O/P_H2). It was shown that the oxidation of cobalt can be prevented by selecting the correct combination of the reactor partial pressures of hydrogen and water (P_H2O/P_H2) and the cobalt crystallite size.     

Fischer-Tropsch synthesis using cobalt catalyst containing modified shungite

The technique of Сo-catalyst preparation through the step of shungite modifying of Zazhoginsky deposit (Russia). The morphology surface, elemental composition and structural and functional characteristics of the catalyst were studied. As a result of the Fischer-Tropsch synthesis at atmospheric pressure and a temperature range of 260–380°C in the presence of Co-catalyst the optimum content of cobalt in the catalyst system to produce liquid hydrocarbons was determined.