Supported Bifunctional Cobalt Catalysts for CO and H2 Conversion to Fuel Fractions of Hydrocarbons

Abstract

of Supported bifunctional cobalt catalysts for the direct conversion of synthesis gas to liquid fuelfraction hydrocarbons (HCs) have been studied. The effect of ZSM-5 zeolite in the structure of the support preformed using a boehmite binder on the catalytic and physicochemical properties of the catalysts has been examined. The synthesized catalysts exhibit high mechanical strength; therefore, they can be used in tubular Fischer–Tropsch (FT) synthesis reactors. The efficiency of the supported bifunctional Со/(Аl₂O₃–ZSM-5) catalysts is determined by the number of active metal cobalt sites, the degree of dispersion of the cobalt crystallites, and the total surface acidity. An increase in the catalyst acidity leads to an increase in the fuel fraction selectivity owing to long-chain HCs. At the same time, the activity of the catalysts decreases; therefore, a decrease in their efficiency is observed. It is assumed that this finding is attributed to the diffusion limitations between the HC synthesis and hydrotreating sites.