The process was invented by Lewis Cass Karrick in the s. Typically natural gas is used as the feedstock, which is steam reformed to make CO and hydrogen: CH. This Fischer—Tropsch technology is also under development by the Statoil Company Norway for use on a vessel to convert associated gas at offshore oil fields into a hydrocarbon liquid.
One of the positive defining characteristics of synthetic fuels production is the ability to use multiple feedstocks coal, gas, or biomass to produce the same product from the same plant. Alkanes are also likely to undergo pyrolysis reactions at certain high temperatures, and if the fuel is used as a heat-exchange fluid to reduce the heat load, carbon formation can occur — this is mainly a problem for some of the newer military jet aircraft. Cobalt[ edit ] Cobalt-based catalysts are highly active, although iron may be more suitable for certain applications.
Ruthenium[ edit ] Ruthenium is the most active of the FT catalysts. The process is now used mainly for C2 and C7 alkene production. Unfortunately, because of scale and cost constraints, pure BTL processes did not score well until very high carbon prices were assumed, though again this may improve with better feedstocks and more efficient larger scale projects. First, reactant gases entering a Fischer—Tropsch reactor must be desulfurized. Such efforts have had only limited success.
By skillful selection of variables T, P, t, and catalyst , we can, in principle, make anything from methane to high molecular weight waxes. They must also generate a sufficient return on investment to justify the capital investment in the project. In addition to alkane formation, competing reactions give small amounts of alkenes , as well as alcohols and other oxygenated hydrocarbons. It is really a polymerization process, and it follows polymerization statistics. In addition to the active metal the catalysts typically contain a number of "promoters," including potassium and copper.
A high content of a carrier provides mechanical strength and wide pores for easy mass transfer of the reactants in the liquid product filling the pores. Alkali metal oxides and copper are common promotors, but the formulation depends on the primary metal, iron vs cobalt. The second direction of iron catalyst development has aimed at highest catalyst activity to be used at low reaction temperature where most of the hydrocarbon product is in the liquid phase under reaction conditions. Pyrolysis and carbonization processes[ edit ] See also: Karrick process There are a number of different carbonization processes. One reactor with a capacity of , tons per annum is now in operation and even larger ones are being built nearly , tons per annum. However, the produced liquids are mostly a by-product and the main product is semi-coke, a solid and smokeless fuel.
Iron-based catalysts can tolerate lower ratios, due to intrinsic water-gas shift reaction activity of the iron catalyst. The product leaves the reactor where catalyst is recovered, oils are removed by a hydrocarbon scrubber, and the tail gas recovered. Advantages of this process are that dissolution and oil upgrading are taking place in the single reactor, products have high H:C ratio, and a fast reaction time, while the main disadvantages are high gas yield, high hydrogen consumption, and limitation of oil usage only as a boiler oil because of impurities. Recently since low-temperature Fischer—Tropsch slurry processes are under investigation for the use of iron and cobalt catalysts, particularly for the production of a hydrocarbon wax, or to be hydrocracked and isomerised to produce diesel fuel, by Exxon and Sasol. In particular, it is amazing that the much carbided alkalized iron catalyst gives a similar reaction as the just metallic ruthenium catalyst. They must also generate a sufficient return on investment to justify the capital investment in the project.
One direction has aimed at a low-molecular-weight olefinic hydrocarbon mixture to be produced in an entrained phase or fluid bed process Sasol—Synthol process. Schroeder in A sensitivity analysis was performed to determine how carbon control regulations such as an emissions trading scheme for transportation fuels would affect the price of both petroleum-derived diesel and FT diesel from the different plants. One reactor with a capacity of , tons per annum is now in operation and even larger ones are being built nearly , tons per annum. Coal-based Fischer—Tropsch plants produce varying amounts of CO2, depending upon the energy source of the gasification process. Iron-based catalysts can tolerate lower ratios, due to intrinsic water-gas shift reaction activity of the iron catalyst.
Cobalt[ edit ] Cobalt-based catalysts are highly active, although iron may be more suitable for certain applications. One direction has aimed at a low-molecular-weight olefinic hydrocarbon mixture to be produced in an entrained phase or fluid bed process Sasol—Synthol process. Credit: Dr. It is the first bio-based jet fuel that has been certified for use in aircraft and has been tested in blends with major airlines Virgin. Today slurry-phase bubble column low-temperature Fischer—Tropsch synthesis is regarded by many authors as the most efficient process for Fischer—Tropsch clean diesel production. This owes primarily to the near-absence of sulfur and extremely low level of aromatics present in the fuel.
Recall that branched alkanes and aromatic compounds have higher octane numbers. This chapter details an analysis which derives the Required Selling Price RSP of the FT diesel fuels produced in order to determine the economic feasibility and relative competitiveness of the different plant options. The primary location for gasification and FT synthesis is in South Africa — the gasoline being sold in South Africa has an octane number of It acts as a Fischer—Tropsch catalyst as the pure metal, without any promotors, thus providing the simplest catalytic system of Fischer—Tropsch synthesis, where mechanistic conclusions should be the easiest—e.
Using 14C-labelled ethylene and propene over cobalt catalysts results in incorporation of these olefins into the growing chain. The formation of heavy waxes should be avoided, since they condense on the catalyst and form agglomerations. This also provides agitation of the contents of the reactor. Cobalt[ edit ] Cobalt-based catalysts are highly active, although iron may be more suitable for certain applications. Jet fuel made from FT synthesis makes a decent fuel. Addition of isotopically labelled alcohol to the feed stream results in incorporation of alcohols into product.