Density Functional Theory Study of H and CO Adsorption on Alkali-Promoted Mo2C Surfaces

Abstract

Using alkali metals as promoters is known to strongly influence the selectivity of catalytic reactions on Mo2C catalysts. To provide fundamental information about this observation, density functional theory calculations have been performed to study K and Rb adsorption of seven low-index alpha-Mo2C surfaces and the equilibrium crystal shape of Mo2C has been predicted using the Wulff construction. K and Rb are found to bind most strongly on Mo2C (001). This surface is also shown to favor a reconstruction in the absence of adsorbates. This reconstruction strengthens the adsorption of K and H while it weakens the adsorption of CO on the surface. A small number of calculations of H/K and CO/K coadsorption were performed to probe the effect of alkali promoters on these adsorbed species.