Preparation of Pd-based membranes on Pd/TiO2 modified NaX/PSS substrate for hydrogen separation: Design and optimization

Abstract Porous stainless steel/NaX nanozeolites/Palladium (Pd)/TiO 2 (PSS/NaX/Pd/TiO 2 ) membrane was prepared by sol–gel method and its application was investigated for hydrogen separation. NaX nanozeolites were synthesized using microwave heating method and coated by vacuum-assisted method on the PSS surface. The prepared membranes were characterized using SEM, and XRD analysis. The Box-Behnken design was used to determine the relation between synthetic and process variables including NaX content (0.5–1.5 g), Pd/TiO 2 percentage (2–10%), pressure difference (2–4 bar) and temperature (350–450 °C) on the hydrogen permeation flux and H 2 /N 2 ideal selectivity. By optimization of parameters, the experimental maximum hydrogen permeation flux and ideal selectivity were found to be 0.245 mol/m 2  s and 1025, respectively. Moreover, the performance of fabricated PSS/NaX/Pd/TiO 2 membrane was investigated for different mixtures of H 2 /N 2 in optimum conditions. The results indicated that hydrogen fluxes and H 2 /N 2 separation factor were remarkably decreased by increasing N 2 content. The obtained results suggests that the incorporation of Pd/TiO 2 composite into the Pd-based membranes and optimization of parameters can be effective method for increasing the performance of Pd-based membranes in hydrogen separation.