Fischer—Tropsch synthesis development

Schaub, G., Rohde, R., and Subiranas, A.M. (2006) Fischer-Tropsch synthesis - development and perspectives. Presented at DGMK/ SCI-Conference Synthesis Gas Chemistry, Dresden, Germany, 4-6 October 2006. 

A number of chemical products are derived from Sasol s synthetic fuel operations based on the Fischer-Tropsch synthesis including paraffin waxes from the Arge process and several polar and nonpolar hydrocarbon mixtures from the Synthol process. Products suitable for use as hot melt adhesives, PVC lubricants, cormgated cardboard coating emulsions, and poHshes have been developed from Arge waxes. Wax blends containing medium and hard wax fractions are useful for making candles, and over 20,000 t/yr of wax are sold for this appHcation. 

The second reaction is called the Fischer-Tropsch synthesis of hydrocarbons. Depending on the conditions and catalysts, a wide range of hydrocarbons from very light materials up to heavy waxes can be produced. Catalysts for the Fischer-Tropsch reaction iaclude iron, cobalt, nickel, and mthenium. Reaction temperatures range from about 150 to 350°C reaction pressures range from 0.1 to tens of MPa (1 to several hundred atm) (77). The Fischer-Tropsch process was developed iadustriaHy under the designation of the Synthol process by the M. W. Kellogg Co. from 1940 to 1960 (83). 

The first demonstration of catalytic conversion of synthesis gas to hydrocarbons was accompHshed ia 1902 usiag a nickel catalyst (42). The fundamental research and process development on the catalytic reduction of carbon monoxide was carried out by Fischer, Tropsch, and Pichler (43). Whereas the chemistry of the Fischer-Tropsch synthesis is complex, generalized stoichiometric relationships are often used to represent the fundamental aspects ... 

In 1950 the Fischer-Tropsch synthesis was banned in Germany by the allied forces. Sinarol, a high paraffinic kerosene fraction sold by Shell, was used as a substitute. This ban coincided with the rapid development of the European petrochemical industry, and in due time Fischer-Tropsch synthesis applied to the production of paraffins became uneconomic anyway. After the war there was a steady worldwide increase in the demand for surfactants. In order to continually meet the demand for synthetic detergents, the industry was compelled to find a substitute for /z-paraffin. This was achieved by the oligomerization of the propene part of raffinate gases with phosphoric acid catalyst at 200°C and about 20 bars pressure to produce tetrapropene. Tetrapropene was inexpensive, comprising a defined C cut and an olefinic double bond. Instead of the Lewis acid, aluminum chloride, hydrofluoric acid could now be used as a considerably milder, more economical, and easier-to-handle alkylation catalyst [4],... 

The catalytic partial oxidation of methane for the production of synthesis gas is an interesting alternative to steam reforming which is currently practiced in industry [1]. Significant research efforts have been exerted worldwide in recent years to develop a viable process based on the partial oxidation route [2-9]. This process would offer many advantages over steam reforming, namely (a) the formation of a suitable H2/CO ratio for use in the Fischer-Tropsch synthesis network, (b) the requirement of less energy input due to its exothermic nature, (c) high activity and selectivity for synthesis gas formation. 

Recently, the Fischer-Tropsch synthesis regained much attention mainly due to the (political) desire for cleaner fuels and the potential shortage of crude oil. Therefore, research activity is focusing on the development of improved reactor concepts as well as on novel and promising catalysts for an economic production of clean fuels via FTS. 

Zhang, Y., Shinoda, M., and Tsubaki, N. 2004. Development of bimodal cobalt catalysts for Fischer-Tropsch synthesis. Catal. Today 93 55-63. 

In this work, a detailed kinetic model for the Fischer-Tropsch synthesis (FTS) has been developed. Based on the analysis of the literature data concerning the FT reaction mechanism and on the results we obtained from chemical enrichment experiments, we have first defined a detailed FT mechanism for a cobalt-based catalyst, explaining the synthesis of each product through the evolution of adsorbed reaction intermediates. Moreover, appropriate rate laws have been attributed to each reaction step and the resulting kinetic scheme fitted to a comprehensive set of FT data describing the effect of process conditions on catalyst activity and selectivity in the range of process conditions typical of industrial operations. 

Visconti, C.G., Tronconi, E., Lietti, L., Zennaro, R., and Forzatti, P. 2007. Development of a complete kinetic model for the Fischer-Tropsch synthesis over Co/A1203 catalysts. Chem. Eng. Sci. 62 5338 -3. 

There has been considerable recent research interest in the activation of carbon monoxide en route to more complex organic molecules. Among the various reactions that have been investigated and/or newly discovered, the transition metal catalyzed reduction of CO to hydrocarbons (Fischer-Tropsch synthesis) has enjoyed particular attention (l- ). Whereas most of the successful efforts in this area have been directed toward the development of heterogeneous catalysts, there are relatively few homogeneous systems. Among these, two are based on clusters (10,11) and others are stoichiometric in metal (12-17). In this report we detail the synthesis and catalytic chemistry of polystyrene ( ) supported... 

Iso-Synthesis A version of the Fischer-Tropsch process developed in Germany during World War II. 

Another option to extend the ligno-cellulosic feedstock base is the development of BTL through biomass gasification and subsequent Fischer-Tropsch synthesis. Although BTL is fully compatible with diesel fuel, ligno-cellulosic BTL has not yet been commercialised. 

The director of this Institute, Dr. Herbert Kolbel, Professor of Technical Chemistry, has been involved during the second World War II in the development of upgrading coal to other hydrocarbons according to the Fischer-Tropsch synthesis in bubble column reactors with suspended catalysts. He was interested in gaining more knowledge s on of transport processes and chemical reactions in these reactors. 

In 1976 he was appointed to Associate Professor for Technical Chemistry at the University Hannover. His research group experimentally investigated the interrelation of adsorption, transfer processes and chemical reaction in bubble columns by means of various model reactions a) the formation of tertiary-butanol from isobutene in the presence of sulphuric acid as a catalyst b) the absorption and interphase mass transfer of CO2 in the presence and absence of the enzyme carboanhydrase c) chlorination of toluene d) Fischer-Tropsch synthesis. Based on these data, the processes were mathematically modelled Fluid dynamic properties in Fischer-Tropsch Slurry Reactors were evaluated and mass transfer limitation of the process was proved. In addition, the solubiHties of oxygen and CO2 in various aqueous solutions and those of chlorine in benzene and toluene were determined. Within the framework of development of a process for reconditioning of nuclear fuel wastes the kinetics of the denitration of efQuents with formic acid was investigated. 

Summarizing, there are still many scientific challenges and major opportunities for the catalysis community in the field of cobalt-based Fischer-Tropsch synthesis to design improved or totally new catalyst systems. However, such improvements require a profound knowledge of the promoted catalyst material. In this respect, detailed physicochemical insights in the cobalt-support, cobalt-promoter and support-support interfacial chemistry are of paramount importance. Advanced synthesis methods and characterization tools giving structural and electronic information of both the cobalt and the support element under reaction conditions should be developed to achieve this goal. 

One shortcoming of the Fischer-Tropsch synthesis is its lack of selectivity in giving complex product mixtures. In an attempt to improve the selectivity of syngas-based hydrocarbon synthesis, Mobil researchers developed a process consisting of converting methyl alcohol (itself, however, produced from syngas) to gasoline (or other hydrocarbons) over a shape-selective intermediate-pore-size zeolite catalyst (H-ZSM-5) 22 78... 

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