CO Hydrogenation On a Model Co/SiO2 Catalyst

Supported cobalt catalysts have been extensively studied for Fischer-Tropsch synthesis because of their higher activity compared to commercially used iron catalysts.  In this study, a planar model Co/SiO₂ catalyst was prepared by depositing metallic cobalt onto silica films in ultrahigh vacuum conditions.  CO hydrogenation was carried out on this catalyst at a total pressure of carbon monoxide and hydrogen between 250 and 760 Torr.  The effects of reaction temperature and pressure on kinetics and product distributions were investigated.  The turnover frequency, activation energy, and chain growth probability were found in good agreement with those obtained on cobalt-based technical catalysts.  The catalyst surfaces were studied by X-ray photoelectron spectroscopy after CO hydrogenation.  It was found that the catalyst deactivation was mainly caused by carbonaceous depositions, whereas the formation of cobalt oxide or cobalt carbide was not observed after reaction.