Titania-silica as catalysts: molecular structural characteristics and physico-chemical properties

Recent results on characterization and applications of titania-silica mater ials as photocatalysts, acid catalysts and oxidation catalysts are reviewed . The similarities and differences in structural characteristics and physic o-chemical properties between titania-silica mixed and supported oxides are emphasized. The generation of new catalytic active sites either on the sil ica surface or in the silica matrix is discussed with respect to the format ion of Ti-O-Si bonds and the local structure. The insights obtained from th ese studies allow a fundamental understanding of the relationships between the structural characteristics and the physico-chemical/reactivity properti es of titania-silica catalysts. (C) 1999 Elsevier Science B.V. All rights r eserved.