REVERSAL OF THE SMSI STATE ON PT/TIO2 BY CO HYDROGENATION

We have examined the role of the SMSI state in the CO hydrogenation activity of Pt/TiO2 and, in particular, whether CO hydrogenation leads to reversal of the SMSI state. Hydrogenolysis of n-butane, which is suppressed in the SMSI state, was used to monitor the onset and reversal of the SMSI state. When CO hydrogenation was performed on a Pt/TiO2 catalyst subjected to high temperature reduction, there was almost a complete restoration of hydrogenolysis activity. This implies that the working catalyst surface during CO hydrogenation is free of the site-blocking oxide species responsible for the SMSI state. The ratio of hydrogenolysis/isomerization activity of n-butane was also unaffected by onset of the SMSI state. Therefore, the migration of TiQx over the metal surface during SMSI does not cause selective suppression of hydrogenolysis with respect to isomerization. The site-blocking oxide species responsible for SMSI on the metal surface do not appear to be necessary to obtain enhanced CO hydrogenation activity on Pt/TiO2. © 1991.