A DFT study of olefin metathesis over heterogeneous Mo/HBeta catalyst: The influence of Mo oxidation state

Density functional theory (DFT) calculations were performed to investigate the influence of Mo oxidation state on the olefin metathesis over heterogeneous Mo/HBeta catalyst. Three cluster models of Mo-methylidene active sites with different Mo oxidation states were developed. The olefin such as ethene metathesis on Mo-methylidene occurs via two elementary steps, i.e. the formation of the molybdacyclobutane intermediate and the opening of the four-membered ring. On the basis of the energy profiles, the energy barriers of the second step are largely dependent on the Mo oxidation states, and the reaction rate of Mo-methylidene active sites are found to decrease in the order of MoV > MoVI > MoIV.