Preparation and characterization of inorganic membranes for hydrogen separation

• Silica and Pt membranes were prepared using dip-coating technique.
• H2, He and N2 gas permeation tests were carried out for membrane characterization.
• H2/He selectivity of 1.96 was obtained for the Pt membrane.
• The selectivity was found to be higher than that of the theoretical Knudsen selectivity.
• The experimental results reveal both viscous, Knudsen and activated surface diffusion transport mechanisms.

A tubular commercially available alumina support was coated using the dip coating technique. The objective is to prepare silica and Pt impregnated membranes. Scanning electron microscopy (SEM), energy diffraction X-ray analysis (EDXA), nitrogen adsorption–desorption at 77 K and gas permeation measurements were employed for membrane characterization. The permeation of H2, He and N2 revealed that the membranes are crack-free. H2/N2 selectivity for the silica membrane obtained the highest value of 2.93 at 0.9 barg and 25 °C. On the other hand, H2/He selectivity of 1.96 at 1.6 barg and 300 °C for the Pt membrane was obtained and found to be higher than the theoretical Knudsen selectivity. While the silica membrane realised on the thin film coating to enhance the selectivity to hydrogen, the Pt impregnated membrane on the other hand enhance hydrogen transport through an activated surface diffusion in addition to Knudsen flow.