SURFACE-CHEMISTRY OF TITANIA (ANATASE) AND TITANIA-SUPPORTED CATALYSTS

The anatase surface is highly heterogeneous due to the different surro undings of the Ti4+ ions situated on the various crystal faces. The su rface acidity of TiO2 is of a Lewis type, but many admixtures and addi tives generate Bronsted acidity. The crystal structure of anatase (i) determines the lack of centres for dissociation of adsorbed molecules, which affects anatase adsorption and (photo)catalytic properties, and (ii) favours the formation of active VOx species on V2O5/TiO2 catalys ts. Crucial for the catalytic performance of titania-supported metals is their partial coverage by TiOx(x<2) moieties after high-termperatur e reduction.