(552b) 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.