Preparation of Al2O3–ZrO2 mixed supports; their characteristics and hydrothermal stability

Al2O3–ZrO2 mixed supports have been synthesised using a colloidal solution of ZrO(OH)2 or a Zr(IV) propoxide solution in organic medium. Zirconia content in these samples was about 10% (∼36% of the theoretic monolayer). The hydrothermal stability (alumina→boehmite transformation at 230 °C, about 10 bar pressure, in the presence of water vapour) of these supports was then investigated by XRD. The presence of the zirconia over the alumina decrease the quantity of boehmite formed after the hydrothermal treatment. The dispersion of zirconia and the stability in hydrothermal conditions of the final support are function of the preparation method.