(570s) Production of Middle Distillate Range Transportation Fuels From Synthesis Gas Using Fischer Tropsch Synthesis Technology Under Supercritical Phase

Fischer-Tropsch synthesis (FTS) is integrated in the Coal/Biomass-to-Liquid technology for converting synthesis gas, a CO/H2 mixture, into a wide distribution of hydrocarbon products. A triple-bed reactor system, which allows FTS, oligomerization and cracking/isomerization stages to occur sequentially, is build to prune the wide FTS products range to middle distillates. Supercritical media is utilized to improve mass transport and heat transfer in the reaction system.

Upgrading FTS products from the first bed takes place in the second bed of the triple-bed reactor system, with catalytic oligomerization reaction by polymerization of light olefins into gasoline or diesel range with varying degrees of branching. Hydrocracking/isomerization is utilized for cracking the long chain FTS products and wax into middle distillates, using palladium over amorphous silica alumina catalysts (1 wt%).

Based on previous experience on supercritical phase FTS, proper supercritical media result in reduced CH4 and CO2 production, enhanced middle distillate yield, and improved catalyst activity maintenance during FTS. In light of the highly exothermic nature of FTS reactions and oligomerization reaction, supercritical media facilitate heat removal to prevent catalysts sintering and charring.