Fischer-Tropsch (FT) products are produced using four main steps--syngas generation, syngas purification, FT synthesis, and product upgrading. The product mix depends on reactor temperature and pressure, the syngas composition, and the types of catalysts used (typically iron or cobalt). Catalysts can be deactivated by the deposition of carbon on their surface and by impurities (most notably sulfur) in the syngas. Commercial processes are available to clean syngas to meet impurity tolerances.
FTS reactions generate a large amount of heat and reactor design and process development have focused on heat removal and temperature control. A number of different reactor designs are used to commercially produce FTS products.
South Africa produces more than 200 fuel and chemical products using coal. Shell produces 1.1 billion pounds of FT products/yr using natural gas at its facility in Malaysia. Syntroleum operates a 10,000 barrel per day facility in Australia using natural gas to produce liquid fuels and specialty products.
Most of the capital cost for FTS plants is for the generation of the syngas.
The feedstock cost is a major component of the operating costs. Production of syngas from natural gas is 30% lower than from coal. The estimated cost of producing FT liquid fuels from fossil fuel feedstocks (in a 50,000 BPD plant) ranges from $0.76 to $1.70/gallon depending on feedstock price and from $1.10/gallon to $4.10/gallon for biomass feedstocks.
Life cycle assessments (LCA) indicate that FTS liquid fuels produced from fossil fuel feedstocks offer little energy and greenhouse gas emission benefits compared to traditional transportation fuels. Use of biomass feedstocks has the potential to alter this situation.