Thermal Stability of Silica-Zirconia Membranes

The thermal stability, phase transformation, surface morphology, pore size distribution and permeation of the defect-free silica-zirconia membrane were investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), gas adsorption analyzer (BET), and gas permeation apparatus, respectively. Using silica as the stabilizing agent, the defect-free membrane was much more stable than pure zirconia. The crystal transformation of zirconia in the sil-ica-stabilized membrane could be prohibited by the interaction between silica and zirconia. ZrO2 crystals were kept tetragonal below 900℃, the size of which did not change with temperature between 700℃ and 900℃. It was further veri-fied by the AFM observation, pore size analysis and permeation study. This thermal stability makes the silica-zirconia membrane a good choice as the intermediate layer for zeolite and Pd-based membranes.