Sulfuric acid-modified zirconia membrane for use in hydrogen separation

摘要

Microporous zirconia membranes, in which the pore size distribution was controlled by optimizing the calcination temperature, were prepared by a sol-gel technique. The membrane with an average pore size < 2 nm was then modified by exposure to sulfuric acid (H_2SO_4) solutions, followed by heat-treatment. The gas permeation properties of the membranes were evaluated for single-component and binary-component systems of H_2, N_2, CO_2, iso-C_4H_(10) and NH_3. The zirconia membrane, which was modified by treatment with a 0.50 mol l~(-1) H_2SO_4 solution, showed a high hydrogen permeance of (2.8-3.0) x 10~(-6) mol Pa~(-1) m~(-2) s~(-1), and the H_2 selectivities over CO_2 and iso-C_4H_(10) were 6 and 9, respectively, for equimolar binary systems. The experimental data showed that the H_2 selectivity over the other gases increased, and the permeance devreased, when increasing concentration of the H_2SO_4 solution were used. The permeance of NH_3 for the H_2SO_4-modified membranes suggests that acidic sites were introduced as a result of the modification.