The synthesis of hydrocarbons and oxygenates during CO hydrogenation on CoCuZnO catalysts: Analysis at the site level using multiproduct SSITKA

Abstract

This paper addresses the effect of component interaction in CoCuZnO catalysts on oxygenate synthesis during CO hydrogenation. Formation of the various products was investigated for the first time using in-situ multiproduct SSITKA. CO hydrogenation was carried out in a fixed-bed differential reactor at 250°C and 1.8atm. Reaction results indicate that the activities for all products decrease with the combination of Co with Cu, possibly, based on SSITKA results, due to partial blockage of the Co surface by Cu. ZnO alone, on the other hand, seems to serve primarily as a support for Co but may increase slightly the intrinsic activities for higher oxygenates. The effects of Cu and ZnO on Co, however, were not additive. The Co–Cu–ZnO combination resulted in a synergy that greatly increased selectivities for higher oxygenates by significantly decreasing the ability for hydrocarbon formation. Interestingly, the rate of synthesis for C2 oxygenates on Co/CuZnO was identical to that on Co/Al2O3 (considered by most to be only a hydrocarbon synthesis catalyst)—but without the high production rate of hydrocarbons.