Surface reactivity of VOx/CeO2 (1 1 1) and the impact of transition metal doping of CeO2 support on oxidative dehydrogenation of propane

Abstract

Propane oxidative dehydrogenation (ODH) was studied over VOx/CeO2 nanoparticle catalysts for various vanadia nuclearities using Density Functional Theory simulations. On monomers and dimers, propene formation involved V=O, bridged (V–O–Ce, V–OV) and ceria surface oxygens but with low selectivity, while on trimers and possibly higher oligomers it was kinetically favourable over ceria surface oxygens, with higher selectivity than on monomers and dimers. On trimer, overoxidation via acetone formation was inhibited, but at the expense of overall catalyst reactivity. Doping of ceria support with Ni induced strong Ni–VOx interactions, stabilizing the vanadia monomer. The V–O–Ni bridged oxygen was less accessible for overoxidation, resulting in an increase in activation energy barrier for acetone formation by 0.69 eV on VO2/Ce0.89Ni0.11O2(111), while there was a minimal impact on V3O6/Ce0.89Ni0.11O2 (111). Hence, transition metal doping of ceria support is a potential strategy to improve propene selectivity over VOx/CeO2 catalysts for a wide range of V loadings.