Synthetic Fischer-Tropsch synthesis

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. 

Fischer-Tropsch Waxes. Polymethylene wax [8002-74-2] production is based on the Fischer-Tropsch synthesis, which is basicaHy the polymerisation of carbon monoxide under high pressure and over special catalysts to produce hydrocarbons (see Fuels, synthetic-liquid fuels). 

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 primary product from Fischer-Tropsch synthesis is a complex multiphase mixture of hydrocarbons, oxygenates, and water. The composition of this mixture is dependent on the Fischer-Tropsch technology and considerable variation in carbon number distribution, as well as the relative abundance of different compound classes is possible. The primary Fischer-Tropsch product has to be refined to produce final products, and in this respect, it is comparable to crude oil. The primary product from Fischer-Tropsch synthesis can therefore be seen as a synthetic crude oil (syncrude). There are nevertheless significant differences between crude oil and Fischer-Tropsch syncrude, thus requiring a different refining approach.1... 

The synthetic fuels that can be produced by low-temperature Fischer-Tropsch synthesis inherently have a high quality (being sulfur- and aromatics-free) and can therefore be used as quality improvers with conventional components. 

Catalysts and reactors have been extensively investigated for liquid phase Fischer-Tropsch synthesis (Davis, 2002). The synthetic Fischer-Tropsch diesel fuel can provide benefits in terms of both PM and NO emissions (May, 2003). Properties of FT and No. 2 diesel fuels are given in Table 3.9. 

Syngas to Synthetic Fuels The Fischer-Tropsch Synthesis... 

The LFTB concluded, on the basis of these studies, that the Mobil process provided a more economic and efficient method of producing synthetic fuel than did Fischer-Tropsch synthesis. The Board also concluded that it was not possible for New Zealand to reach 50 percent self-sufficiency in transport fuels by the middle 1980 s without synthetic fuel. With only condensate, CNG and LPG a realistic comparable goal would be about 25 percent self-sufficiency. 

Although nearly any combustible fuel can be used as a source of Fischer-Tropsch synthesis gas, coal is by far the most common. A long-term agreement made prior to construction made available a supply of natural gas at 0.05 per thousand cubic feet for the Carthage Hydrocol Company plant. With greatly increasing demand for natural gas, however, it is unlikely that plants producing purely synthetic liquid fuete will be based tai natural gas in the United States. New supplies of natural gas at the well are currently about 15-20 cents per thousand cubic feet, and the price will inevitably continue to increase. 

General Synthesis Scheme. A schematic diagram of a plant producing synthetic liquid fuels and chemicals from coal via the Fischer-Tropsch synthesis is shown in Fig. 11-3. Gasification of coal with steam and oxygen is followed by a purification step to eliminate solids, sulfur compounds, and most of the carbon dioxide. Two stages of synthesis are employed to attain a high conversion of the synthesis gas. Recovery and treatment of primary... 

Drs. Raje and Davis present interesting work on the use of isotopes to study Fischer-Tropsch synthesis. This route to synthetic chemicals, despite having been studied for some time, must be more cost-competitive before it will be widely used. The work presented in this chapter will help us understand the mechanism of the reactions and how to maximize yields. 

The company Sasol operates a synthetic fuel production facility consisting of 48 coal gasification (Lurgi) units. The product gas is generated at a rate of 2.1 million Nm /h with a 38 % hydrogen share and is used for gasoline and diesel production by means of Fischer-Tropsch synthesis [78]. 

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