Spectroscopic tools for probing the isolated titanium centres in MCM41 mesoporous catalysts

Abstract

Catalytically active Ti(IV) centres anchored to the inner walls of MCM-41 mesoporous silicas have been investigated using a combination of FT-IR, diffuse reflectance UV-visible and luminescence spectroscopy supplemented by the use of H2O and NH3 as molecular probes of the Ti coordination. The results re-affirm and extend the conclusions reported earlier for the Ti-MCM41 novel epoxidation catalysts, seeMaschmeyer T.,Rey F.,Sankar G. andThomas J. M.,Nature, 378 (1995) 159, who, usingin situ EXAFS studies, showed that the Ti(IV) centres exist largely as isolated active sites.