CD₃CN and NH₃ interaction with Ti(IV) catalytic centres grafted on mesoporous MCM-41

CD₃CN and NH₃ were used as molecular probes to monitor the nature of both Brønsted and Lewis acid sites as well as the coordination sphere of Ti(IV) centres in Ti(IV) grafted MCM-41 by means of FT-IR and Diffuse Reflectance UV-Vis spectroscopies. CD₃CN molecule was very effective to reveal the presence and the coordination changes of Ti(IV) Lewis acid centres, but was not helpful to evidence different type of OH acid centres in pure MCM-41 and Ti-MCM-41. On the contrary, ammonia adsorption on Ti-MCM-41 revealed the presence of Bransted sites sufficiently acidic to protonate NH₃ molecules with the formation of NET species.