Effects of K addition on the performance of supported Fe catalysts for Fischer - Tropsch synthesis (FTS) were studied in a slurry reactor at 240 to 270ºC, 2.0 to 4.0 MPa and syngas H2/CO = 1.0. The catalysts were characterized by N2 adsorption, H2 temperature programmed reduction, X - ray diffraction, X - ray fluorescence, thermogravimetric analysis, scanning electron microscopy and dispersive X - ray spectroscopy. A strong interaction was observed between Fe and K, which inhibited the reduction of Fe catalyst. Addition of potassium increased the production of heavy hydrocarbons (C20+).

The dependencies of Fischer-Tropsch synthesis liquid hydrocarbon product distribution on operating pressure and temperature have been studied for unpromoted and potassium-promoted iron catalyst. The study followed an experimental planning and the results were analyzed based on surface response methodology. The effects of different operating conditions on the distribution of the liquid product were compared based on number-average carbon number and distribution dispersion. Results showed that high pressures (25 to 30 atm) favor the production of heavy waxes that can be converted into liquid fuels through hydrocracking, while greater selectivity towards liquid fuels are favored by low temperature (240ºC) and low pressure (20 atm). The liquid product distribution produced using potassium promoted iron catalyst presented higher number-average number of carbons, lower dispersion and lower skewness when compared to product distribution obtained with the unpromoted iron catalyst. The use of potassium as a promoter resulted in the production of longer hydrocarbon chains with higher selectivity of a specific narrow carbon number range.

Fischer-Tropsch synthesis is an important chemical process for the production of liquid fuels. In recent years, the abundant availability of natural gas and the increasing demand of gasoline, diesel and waxes have led to a high interest in further developing this process. The dependencies of liquid hydrocarbon product distribution of iron catalyzed Fischer-Tropsch synthesis on operating pressure and temperature have been studied. The study followed an experimental planning and the results were analyzed based on surface response methodology. The effects of different operating conditions on product distribution were compared based on number average carbon number and distribution dispersion. Results showed that high temperature (270°C) and pressure (27 atm) favor the production of heavy waxes that can be converted to liquid fuels through hydrocracking, while greater direct selectivity towards liquid fuels are favored by low temperature (240°C) and high pressure (30 atm).