SULFATED ZIRCONIA AS A COCATALYST IN FISCHER-TROPSCH SYNTHESIS

This work deals with the direct synthesis of branched hydrocarbons fro m synthesis gas using a two-component catalyst: a Fischer-Tropsch synt hesis catalyst (RuKY) and a sulfated zirconia (SO42-/ZrO2) strong acid catalyst. The composition of C-7 hydrocarbons was used to gauge the e ffect of the acid catalyst on hydrocarbon product selectivity. Over Ru KY alone, C-7 olefins prevail in C-7 hydrocarbons while the content of branched C-7 paraffins is very low. The use of SO42-/ZrO2 as a cocata lyst for Fischer-Tropsch synthesis causes significant changes in the c omposition of hydrocarbon products, particularly in the early stages o f the reaction. It increases the content of branched paraffins and dec reases that of olefins. However, this catalyst suffers serious deactiv ation. Addition of small amounts of Pt to SO42-/ZrO2 is an effective w ay for stabilizing its activity under FTS reaction conditions. CO in t he synthesis gas has a suppressing effect on the catalytic activity of SO42-/ZrO2 catalysts. This effect becomes weaker as the reaction temp erature increases due to a less competitive CO adsorption. Our data re veal that CO adsorption occurs not only on Lewis acid sites of SO42-/Z rO2 but also on Pt particles.