CHARACTERIZATION OF ALUMINA-TITANIA MIXED-OXIDE SUPPORTS .1. TIO2-BASED SUPPORTS

The bulk and surface properties of a series of titanium-rich Al2O3-TiO 2 mixed oxides catalytic supports have been determined by different te chniques (S-BET, pore size distribution, XRD, DTA, FTIR, FT-Raman, UV- vis diffuse reflectance and FTIR of adsorbed pivalonitrile and pyridin e). The analysis of the results indicates that the prepared solids wer e fairly homogeneous, with titania showing the anatase structure and n o segregation of alumina particles. Also, the addition of small amount s of alumina to titania enhances significantly its thermal stability. The UV, FTIR, Raman and XRD results suggest that part of the alumina f orms a solid solution with TiO2 and that two types of aluminum are pre sent, one due to surface monolayer-type species and other due to octah edrally coordinated bulk species. The FT-Raman and the FTIR spectra of adsorbed probe molecules support the idea that the anatase particles are largely covered by surface alumina partial monolayers. (C) 1997 El sevier Science B.V.