Hydrogenation of CO2 over sprayed Ru/TiO2 fine particles and strong metal-support interaction

Abstract

Ru/TiO2 catalysts were prepared by spray reaction (SPR) and conventional impregnation (IMP) methods. The catalytic activities of SPR fine particles were much higher than those of IMP catalysts for CO2 hydrogenation. A high temperature reduction greatly promoted the activity of SPR catalyst. A model of surface structure was proposed which exhibits the enhancement of decoration and the formation of more boundaries over spr-Ru/TiO2. The high activity of SPR catalyst is attributed to the occurrence of new active sites at the metal-support perimeters and not any SMSI phenomenon. EXAFS reveals that the Ru atom was interacting with TiO2 by oxygen atom so strongly on the SPR catalysts that a part of the Ru atoms, located near the internal interface between Ru particles and TiO2 support, existed as Run+ (n<4) cations even if SPR catalyst was subjected to a high temperature reduction. These Run+ cations are responsible for the inhibition of SMSI formation over SPR catalysts. © 1999 Elsevier Science B.V. All rights reserved.