Fischer-Tropsch method

Most of the production of hydrocarbons by Fischer Tropsch method uses synthesis gas produced from sources that yield a relatively low... 

The coverage on liquid fuels must include an account of the processes for synthesis of gasoline. The synthesis process is carried out by any one of the following (i) polymerization, (ii) Fischer-Tropsch method and (iii) Bergius process. The following description relates only to the first of these methods. 

Whatever the source of synthesis gas, it is the starting point for many industrial chemicals. Some examples to be discussed are the hydroformylation process for converting alkenes to aldehydes and alcohols, the Monsanto process for the production of acetic acid from methanol, the synthesis of methanol from methane, and the preparation of gasoline by the Mobil and Fischer-Tropsch methods. 

Reaction (3) was discovered by Fischer-Tropsch in 1923. The first plants which produced 200,000 tons of hydrocarbons were developed in Germany in 1936. The maximum production of hydrocarbons utilizing the Fischer-Tropsch method was achieved in Germany at the beginning of 1944 (ca 6,000,000 tons per year). After WWII, hydrocarbons were produced by this method in the United States (1948-1953) and in South Africa (from 1955). Owing to the rise in the price of oil after 1973, interest in the Fischer-Tropsch synthesis increased. 

Indirect Liquefaction Process for converting coal into oil or synfuel by first gasifying it also know as the Fischer-Tropsch method. 

The chemical processes being used in the twenty-first century favor the indirect Fischer-Tropsch method of coal liquefaction. In this process, coal is initially subjected to very high heat to create a charred substance that can be combined with carbon dioxide and steam to produce a synthesis gas composed of hydrogen and carbon monoxide. The gas is then chemically subjected to a metallic catalyst, which transforms it into a synthetic crude oil. The resultant synthetic oil can then be refined into the desired fuel. 

Neither the idea nor the practice of producing oil from coal is new. As early as 1819, Charles Macintosh distilled naphtha from coal for the purpose of waterproofing textiles. However, the major breakthroughs in coal liquefaction did not occur until the period between the early 1900 s, when the two processes long used as the starting points for producing oil from coal—the Bergius and Fischer-Tropsch methods— were developed. 

Because the Earth s coal reserves are substantially greater than its oil reserves, a general consensus exists within the energy industry that a liquefied coal industry will eventually emerge around the globe. That day, however, has yet to come. Hence, any discussion of the products that can emerge from such an industry must necessarily be divided into two parts the likely applications of a future liquefied coal industry and what has occurred within the framework of the Fischer-Tropsch method in the Republic of South Africa, the one country where a sig nificant oil-from-coal industry exists. 

Audi has competed in the Le Mans races with R15 TDI cars powered by synthetic diesel fuel produced using the Fischer-Tropsch method. 

On the occasion of Otto Roelen s death in 1993 the question was raised whether the fiiel synthesis based on the Fischer-Tropsch method, which was one of the most important research areas of Roelen, is still of immediate interest. The following shows a simplified version of the reactions occurring in the Fischer-Tropsch synthesis ... 

Other synthetic methods have been investigated but have not become commercial. These include, for example, the hydration of ethylene in the presence of dilute acids (weak sulfuric acid process) the conversion of acetylene to acetaldehyde, followed by hydrogenation of the aldehyde to ethyl alcohol and the Fischer-Tropsch hydrocarbon synthesis. Synthetic fuels research has resulted in a whole new look at processes to make lower molecular weight alcohols from synthesis gas. 

Various methods may be used for the determination of gas holdup—for example, displacement measurements and tracer experiments. Farley and Ray (F2) have described the use of gamma-radiation absorption measurement for the determination of gas holdup in a slurry reactor for the Fischer-Tropsch synthesis. 

Unfortunately, it is difficult to ascertain the identity of the actual catalytic species, and it is not clear whether catalysis by a true intercalation compound has been established. For instance, a frequent method for ammonia and Fischer-Tropsch catalyst generation is the following ... 

Tsubaki N., Sakota H., and Takahashi S. 2004. Production method of Fischer-Tropsch synthesis catalyst and hydrocarbon. Japanese Patent Application JP2004237254. 

Soled S.L., Iglesia E., and Fiato R.A. 1992. Copper-promoted cobalt manganese spinel catalyst and method for making the catalyst for Fischer-Tropsch synthesis. U.S. Patent 5162284. 

Van Steen, E., andPrinsloo, F. F. 2002. Comparison of preparation methods for carbon nanotubes supported iron Fischer-Tropsch catalysts. Catalysis Today 71 327-34. 

Mochizuki, T., Hara, T., Koizumi, N., and Yamada, M. 2007. Novel preparation method of highly active Co/Si02 catalyst for Fischer-Tropsch synthesis with chelating agents. Catal. Lett. 113 165-69. 

Temperature-programmed reduction combined with x-ray absorption fine-structure (XAFS) spectroscopy provided clear evidence that the doping of Fischer-Tropsch synthesis catalysts with Cu and alkali (e.g., K) promotes the carburization rate relative to the undoped catalyst. Since XAFS provides information about the local atomic environment, it can be a powerful tool to aid in catalyst characterization. While XAFS should probably not be used exclusively to characterize the types of iron carbide present in catalysts, it may be, as this example shows, a useful complement to verify results from Mossbauer spectroscopy and other temperature-programmed methods. The EXAFS results suggest that either the Hagg or s-carbides were formed during the reduction process over the cementite form. There appears to be a correlation between the a-value of the product distribution and the carburization rate. 

Espinoza, R.L., Shingles, T., Duvenhage, D.J., and Langenhoven, P.L., Method of modifying and controlling catalyst selectivity in a Fischer-Tropsch process. U.S. patent 6,653,357, Sasol Technology, Nov. 25, 2003. 

Taking these effects into account, internal pore diffusion was modeled on the basis of a wax-filled cylindrical single catalyst pore by using experimental data. The modeling was accomplished by a three-dimensional finite element method as well as by a respective differential-algebraic system. Since the Fischer-Tropsch synthesis is a rather complex reaction, an evaluation of pore diffusion limitations... 

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