ACID PROPERTIES STUDIES OF SI AND AL-SI OXIDE PILLARED ZR-TI PHOSPHATES

Acid properties of Ti-Zr phosphates pillared with silica and silica-al umina oligomers have been studied by following the adsorption-desorpti on of several probe molecules with different acid strengths (NH3 pyrid ine and isopropanol). Samples showed similar acid properties, but othe r than the well known acidic materials like amorphous silica-aluminas and zeolites as determined by NH3 adsorption. FT-IR studies of absorbe d pyridine showed the existence of Lewis and Bronsted sites on silica- alumina pillared material whereas no Lewis sites were detected on the silica-pillared counterparts. By isopropanol decomposition it was show n that in the range of temperatures analyzed, acid centres reacted. Th e activity of the material in isopropanol decomposition reaction is hi gh, with values ranging between 30 and 40 mu mol g(-1) s(-1) for the c atalyst derived from samples with higher silica-alumina loading.