Synthesis of supported TiO2 membranes using supercritical alcohol

New techniques to modify inorganic membranes have been developed using hydrolytic decomposition of titanium tetraisopropoxide (TTIP) in supercritical propan-2-ol. Solid anatase particles of about 30 nm size are deposited as a thin film on the surface and in the pores of alumina supports in a Batch reactor. The deposition location was found at the support face in contact with the titanium alkoxide solution. With TTIP concentration equal to 0.1 mol l−1, TiO2 anatase film thickness increases from 1 to 3 μm when supercritical treatment cycles are raised from 1 to 3. The penetration depth around 20–30 μm is found to be independent of either the reactant concentration or the treatment number. Finally, the separation selectivity determined from permeation measurement of H2 and N2 is close to the value predicted by the Knudsen diffusion model.