Preparation and characterization of ultrathin palladium membranes

An ultrathin palladium membrane (1 μm) has been prepared by an improved photocatalytic deposition (PCD) pretreatment and the electroless modification method. SEM results demonstrated good adhesion of the plated palladium membrane on the porous composite TiO₂ support and dense coalescence of the palladium membrane. The flux and H₂/N₂ selectivity of the palladium membrane were determined in the temperature range of 623-823 K and the pressure difference range of 0.02-0.15 MPa. At 673 K and 0.1 MPa pressure difference, the hydrogen permeation flux of the composite membrane was as high as 0.27 mol m^-2 s^-1, and the H₂ZN₂ selectivity coefficient was 361. In this study, the activation energy of hydrogen permeation through the composite palladium membrane was 17 kJ/mol. The corrected pressure exponent for the palladium composite membrane was nearly 0.8 deviated from Sievert's law.