Preparation of Palladium Membrane for Hydrogen Separation by Self-Tuning Photocatalytic Deposition

Abstract

Sol-gel derived nanoporous TiO₂ membranes were prepared by coating a porous support with TiO₂ colloidal solution, followed by drying and calcination at 450°C. Self-tuning photocatalytic deposition was applied for the preparation of palladium membrane for hydrogen separation. The result of EPMA for cross section of Pd–TiO₂ membrane suggested the thickness of Pd–TiO₂ layer was around 1.5 mm. The permeance of hydrogen and nitrogen for Pd–TiO₂ membrane at 200°C decreased to about 1/4 of initial values in the first 3.5 h of irradiation and approached steady-state values, indicating the possibility of self-tuning of the palladium layer. It was found that annealing improved hydrogen selectivity. For example, hydrogen to nitrogen permselectivity for Pd–TiO₂ membranes annealed at 450°C in air for 8 h increased from 7 to 29 with hydrogen permeance of 6.3×10⁻⁶m³·m⁻²·s⁻¹·kPa⁻¹ at 200°C. This is because palladium particles could plug into the inter-particle pores after annealing the Pd–TiO₂ membrane.