SYNTHESIS AND TEXTURAL PROPERTIES OF UNSUPPORTED AND SUPPORTED RUTILE (TIO2) MEMBRANES

Two approaches were postulated for improving the stability of porous texture of titania membranes: (1) retarding the phase transformation and grain growth; (2) avoiding the phase transformation. Based on the second approach, rutile membranes were made directly from a rutile sol, prepared by the precipitation of titania on SnO2 nuclei. The rutile membranes were stable up to 800-degrees-C, with a porosity of ca. 40%, whereas normal titania membranes (starting with anatase) show very little porosity above 600-degrees-C. Alumina substitution retards grain growth and pore growth at 850-degrees-C for unsupported as well as supported membranes.