Effect of operating conditions on Fischer-Tropsch liquid products produced by unpromoted and potassium-promoted iron catalyst

摘要

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.