The identity of titanium centres in microporous aluminophosphates compared with Ti-MCM-41 mesoporous catalyst and titanosilsesquioxane dimer molecular complex: a spectroscopy study

• Published in: Journal of molecular catalysis. A, Chemical Vol. 204; pp. 483 - 489
• Main Authors: Gianotti, E., Frache, A., Coluccia, S., Thomas, J.M., Maschmeyer, T., Marchese, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2003
• Subjects: DR UV-Vis; Photoluminescence; Raman; Ti-aluminophosphates; Titanosilsesquioxane; Titanosilsesquioxane; Ti-aluminophosphates; Raman; DR UV-Vis; Photoluminescence
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(03)00330-3

TAPO-34 and TAPSO-34 with chabasite-like structures were synthesised using morpholine as structure-directing agent. The synthesis and the spectroscopic characterisation (DR UV-Vis, photoluminescence and Raman spectroscopies) of these materials, combined with the study of mesoporous Ti-MCM-41 and a Titanosilsesquioxane dimer molecular complexes with a well defined co-ordination of the Ti(IV) centers, are reported. Titanium-aluminophosphate and silico-aluminophosphate with chabasite-like structures (TAPO-34 and TAPSO-34) have been hydrothermally synthesised using morpholine as structure-directing agent. The local environment of Ti(IV) sites in these materials was studied using diffuse-reflectance UV-Vis, photoluminescence and Raman spectroscopies. This study, combined with the study of Ti-grafted MCM-41 mesoporous catalyst and a titanosilsesquioxane dimer molecular complex with a well-defined co-ordination of the Ti(IV) centers, revealed that a fraction of Ti(IV) ions are present in tetrahedral co-ordination, consistent with some Ti(IV) ions being incorporated into the aluminophosphate frameworks. However, Raman spectroscopy showed that around 20% of the total amount of the titanium used in the gel synthesis is present in a TiO 2-like extra-phase.