259601 Direct Versus Hydrogen Assisted CO Dissociation On Metal Surfaces
We present computational investigations of the formation of precursor hydrocarbon species relevant to production of liquid hydrocarbons on low index surfaces of various important noble and transition metals. The formation could occur via the so-called carbide mechanism. In this mechanism, direct carbon monoxide dissociation takes place, followed by stepwise hydrogenation of C yielding CHx precursor species. Formation of precursor CHx species could also potentially take place through hydrogen assisted route giving rise to hydrogenated carbon monoxide intermediates. First-principles calculations of energetics and barriers of carbon monoxide conversion to hydrocarbons species were performed using plane-wave periodic density functional theory. Our calculations indicate that the hydrogen assisted route is competitive, particularly on transition metals. An in-house microkinetic computer code, with input thermodynamics and kinetic parameters estimated from electronic structure calculations, was developed. The two pathways were examined on representative surfaces using microkinetic approach and it was found that the aforementioned finding holds true at realistic conditions.