Synthesis of thermally stable, high surface area anatase-alumina mixed oxides

Mixed oxides containing anatase and 5-20 mol% alumina have been synthesized from a precursor sol containing acetic acid modified titanium isopropoxide and boehmite (AlOOH). The resultant oxides retain considerable anatase phase at 1000 degrees C and have specific surface area many times higher than that of pure titania. A composite precursor containing titania-20 mol% alumina after calcination at 450 degrees C, has a specific surface area as high as 318 m(2)/g compared to a value of 100 m(2)/g for pure titania prepared under identical conditions. The uniform dispersion of the nanoparticles of alumina in the titania gel matrix causes reduction in the anatase/anatase contact points and thus results in a decrease of nucleation sites leading to increase in thermal stability of anatase phase. The high surface area and porosity could arise from the highly branched acetate polymeric gel. The sintered density of compacts derived from mixed oxides is also brought down considerably compared to pure titania counter parts. (C) 2000 Published by Elsevier Science B.V. Ail rights reserved.