Switching off propene hydrogenation in the direct epoxidation of propene over gold–titania catalysts

Low gold-loaded gold–titanium catalysts with very small gold nanoparticles for the direct epoxidation of propene have a remarkably high epoxidation activity. A disadvantage, however, is that these catalysts in certain cases also have a very high activity for the unwanted hydrogenation of propene to propane. The addition of a small amount of carbon monoxide to the feed gas can completely switch off this propene hydrogenation, while at the same time also reducing the rate of direct water formation. The co-ordination environment of titanium plays an important role in propene hydrogenation.