Infra-red study of the surface properties of rutile. Deuterium exchange, carbon dioxide and but-1-ene adsorption

Abstract

Deuterium exchange with surface hydroxyl groups on rutile was studied using D₂ and D₂O; the former completely exchanges at 300°C (2 h) with evidence for surface reduction, while the latter does not achieve complete exchange with the saturated vapour at room temperature. The shift in infra-red frequencies on deuteration verified previous assignments of surface species as being hydrogenic and also indicated the physical inaccessibility of certain species. Adsorption of CO₂ produced a labile bicarbonate species and indicates the separate chemical identity of the two surface hydroxyl species represented by peaks at 3700 and 3670 cm^–1. But-1-ene interacts with the rutile surface at 150°C with formation of surface alkoxide, and indicates the presence of inaccessible surface groups, but gives no evidence for preferential reaction by one of the hydroxyl groups.