Preparation and characterization of Al2O3-TiO2 composite oxide nanocrystals

Al2O3-TiO2 composite oxide nanocrystals with different Al2O3/TiO2 ratios (1/4, 2/3, 3/2, and 4/1) were prepared by the poly(ethylene glycol) (PEG) sol-gel method, The preparation process was monitored by thermogravimetric analysis and differential scanning calorimetry (TGA-DSC), Nanocrystal particles of these composite oxides obtained at various heat-treating temperatures (400-1100 degrees C) were characterized in terms of morphology, size, specific surface area, composition, and structure by transmission electron microscopy (TEM), BET specific surface area analysis, and X-ray powder diffractometry (XRD), Nanoparticles of Al2O3-TiO2 with grain sizes in the range 1-150 nm and specific surface areas of 4.3-136 m(2)/g could be obtained under different conditions. The morphology of the particles changed from spherical to cubic with increasing heat-treatment temperature, Anatase was stabilized in these composite nanomaterials and the mechanism was discussed, The change of the particles specific surface areas with increase of the Al2O3/TiO2 ratio was researched. The Al2O3-TiO2 composite oxide nanocrystals could catalyze the polymerization of maleic anhydride and may provide a route to obtain a product without rings at the end groups. (C) 1998 Academic Press.