UNDERSTANDING THE TRENDS IN THE HYDRODESULFURIZATION ACTIVITY OF THE TRANSITIN METAL SULFIDES

It is shown that the trends in the hydrodesulfurization activity of th e transition metal sulfides can be understood from the variation in th e binding energy of sulfur to the transition metals. A model based on the ab initio calculations of Gelatt, Moruzzi, and Williams is used to describe the binding energy trends and to single out the important pa rameters determining them. One important aspect of the model is, that it predicts that the trends in the catalytic activity are given to a l arge extend by the coupling between the sulfur chemisorption energy an d the sulfur-induced distortions of the metal lattice. The simple mode l also appears to describe promotional effects.