Molecular orbital calculations of the hydrodesulfurization of thiophene over a MoCo catalyst

Abstract

We report molecular orbital calculations (CNDO) of the desulfurization reaction of thiophene over a molybdena catalyst. In particular, we have studied the relative stabilities of several molybdenum oxide structures ranging from MoO to a linear chain Mo 3O 10. The processes of hydrogenation and sulfidation of Mo 3O 10 leading to vacancy formation were investigated. It was found that the formation of a partially sulfided active catalyst structure with a vacancy over the Mo atom was energetically allowed. Concerning the adsorption of thiophene on this catalyst model, our calculations show, however, that the CS bond cleavage need not occur prior to ring hydrogenation and that a concurrent hydrogenation of the β carbons may also occur quite readily. Finally, the role of cobalt as a vacancy stabilizer is also discussed.