Acidic and basic properties of zirconia—alumina and zirconia—titania mixed oxides

Abstract Two series of mixed oxides ZrO 2 Al 2 O 3 and ZrO 2 TiO 2 were prepared from propylate hydrolysis, followed by drying and calcination. The acidic and basic properties of the various samples were characterized by adsorption of specific probe molecules (carbon dioxide, pyridine, 2,6-di-methylpyridine) studied by FT-IR spectroscopy and activity towards two test reactions (2-propanol dehydration and carbon oxysulfide hydrolysis). Both methods showed that a synergy occurred on ZrO 2 TiO 2 samples leading to a maximum of Bronsted acidity and a minimum of basicity for ZrO 2 (23%)TiO 2 (77%). On the other hand, the Lewis acidity of ZrO 2 Al 2 O 3 samples increased with the alumina content whereas the basicity decreased sharply as soon as alumina was introduced.