(181a) Overview of Fischer-Tropsch Products and Their Upgrading to Useful Products

Historically and at present only two catalyst systems are available for large-scale commercials plants: one based on cobalt and one based on iron. Two operating windows are available: low and high temperatures. The iron catalyst produces gaseous and gasoline range products when operated in the high temperature range, usually in fluid catalyst bed reactors. In the low temperature range, the iron catalyst can produce 50-75% wax products. The cobalt catalyst produces high boiling, waxy products when operated in the low temperature range but attempts to operate in a high (above about 220oC) results in the production of too much methane to be a viable option. The gaseous and liquid products are highly olefinic when operating with iron at high temperatures. Reforming to obtain a higher octane gasoline and alkylation of gaseous products to produce gasoline and/or diesel range products are required. Currently the low-temperature iron FT catalysis produces smaller quantities of products that can be used as chemicals than the high temperature operation; however, when large-scale production of low-temperature FT products with either an iron or cobalt catalyst is used, the wax will have to be converted to lower boiling range products. Differences in processing the high molecular weight products from the iron and cobalt FT catalysts will be considered.