The Fischer-Tropsch synthesis (FTS) produces a wide range of hydrocarbons from synthesis gas. The ability of the reaction to produce transportation fuels from coal or biomass could be vitally important in the near future due to the dwindling supply of high quality crude oil. For this reason, the current study endeavors to increase the selectivity of FTS in the C8 – C12 range.

Two series FTS reactors, both containing silica supported iron catalyst, were employed to perform this study. Synthesis gas was fed into the first reactor; additional synthesis gas was fed into the second reactor along with the products from the first. Several trials were performed in which the relative amounts of carbon monoxide and hydrogen in the secondary synthesis gas stream were varied while the CO:H2 ratio of the primary synthesis gas stream was held constant.

This presentation will discuss the results of these experiments with regards to selectivity of carbon dioxide, methane, C2 – C3 compounds, C4 – C6 compounds, C7 – C10 compounds, and C11 – C15 compounds. The affect of conversion on selectivity will also be discussed with regards to previously performed work.