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

Two approaches were postulated for improving the stability of porous t exture of titania membranes: (1) retarding the phase transformation an d grain growth; (2) avoiding the phase transformation. Based on the se cond approach, rutile membranes were made directly from a rutile sol, prepared by the precipitation of titania on SnO2 nuclei. The rutile me mbranes were stable up to 800-degrees-C, with a porosity of ca. 40%, w hereas normal titania membranes (starting with anatase) show very litt le porosity above 600-degrees-C. Alumina substitution retards grain gr owth and pore growth at 850-degrees-C for unsupported as well as suppo rted membranes.