Motor fuels and chemicals from coal via the Sasol Synthol route

Abstract

The production of motor fuels and chemicals from coal is based on the Fischer-Tropsch reaction by passing hydrogen and carbon monoxide in a specific ratio over iron catalysts at elevated temperatures and pressures. The fixed-bed system employs a precipitated iron catalyst. Predominantly heavy hydrocarbons of an aliphatic nature are produced with carbon chains up to 100. These straight-chain hydrocarbons yield excellent waxes and high quality diesel oil, which is also used as raw material for the production of very high quality biodegradable detergents. The fluid-bed system, based on catalytic cracker technology, has the great advantage of high production capacity and scale-up potential. Scaled-up reactors are the only ones used at Sasol Two and Sasol Three. The quantity of ethylene obtained is augmented by ethane cracking. The light olefins can be used as petrochemical feedstock or refined, e.g. by polymerization, and the product added to the motor fuel pool. The product cut in the gasoline range yields a good quality gasoline by using conventional refinery techniques. The oxygenated chemicals, when sold as such, fetch higher prices than when sold as motor fuels.