COMPARATIVE STUDY OF IRON-BASED FISCHER-TROPSCHSYNTHESIS CATALYST PROMOTED WITH POTASSIUM OR SODIUM

摘要

Fischer-Tropsch synthesis (FTS) on iron catalysts is one of the most important routes for the production of liquid fuel from coal-derived syngas with low H_2/CO ratio [1]. Modification of Fischer-Tropsch catalysts by inclusion of potassium ions has been studied for many years, which have been shown to either decrease or increase the FTS activity of an iron catalyst. However, limited reports of the effect of the other alkalis are available. Potassium has been used to promote selective formation of C_2-C_5 olefins on alumina-supported iron catalysts, while both sodium and potassium can reduce methane selectivity observed on iron catalysts [2]. Promotional effects of alkali metals have been explained in terms of modification of the local electron density of the active transition metal, and through blockage of sites [3].