SIZE-AND SUPPORT-DEPENDENT ELECTRONIC AND CATALYTIC PROPERTIES OF SIZE SELECTED CLUSTER CATALYSTS ON METHANATION OF CO: A COMBINED GIXAS, GISAXS AND TPRX STUDY

摘要

To develop more active FT(Fischer Tropsch) catalysts, a significant amount of effort has been made to understand the effect of particle size and support in this reaction. However, the full extent and the origin of the particle size effects are not yet clearly understood. The oxide formation and lower reducibility of small nanometer size cobalt oxide clusters (< 10 nm), which results from their higher tendency to oxidize than their larger counterparts, are known to be responsible for the lower activity. A recent study showed that oxidation of nano-sized cobalt crystallites is not necessarily the cause of deactivation at realistic Fischer–Tropsch synthesis conditions. The deactivation of small nanoparticles is ascribed to a combination of the surface energy of nanosized cobalt crystallites and structure sensitivity surface reconstruction to the overall FT process.