Thin supported inorganic membranes for energy-related gas and water purification

摘要

Inorganic membranes consist of a stand-alone or supported material with special transport properties, able to operate at elevated temperatures and pressures. Inorganic membranes are classified according to the presence and size of connected porosity. Dense membranes have 100% selectivity for H_2 and O_2, and acceptable flux at high temperature. Micro-porous membranes have ＜ 2nm Ø pores and combine high but ＜ 100% H_2 selectivity with higher fluxes at lower temperatures. Meso-porous membranes have 2-50 nm Ø pores, a good thermo-chemical stability, very high fluxes over a wide temperature range, and moderate Knudsen selectivity for separation of light molecules (H_2) from heavier ones (CO_2). Meso-porous membranes are also considered for pressure-driven water purification. Large scale introduction of inorganic membranes has been hindered by lack of structural definition, reproducibility, and accurate design parameters. The present paper shows how these problems can be addressed by synthesis and characterization of smooth, strong and surface-defect free supporting structures.