Résumé
As global energy demand continues to rise, hydrogen purification plays a pivotal role in advancing the “hydrogen economy”, ensuring the required purity levels for its direct use or storage. This work presents the synthesis and functional characterization of palladium-based hydrogen-selective composite membranes applicable for gas separation below 300 °C. These membranes were prepared via Atomic Layer Deposition (ALD) of palladium (Pd) onto asymmetric ceramic tubular supports, using palladium hexafluoroacetylacetonate Pd(hfac)2 and formalin at 220 °C. Prior to Pd deposition, the γ-Al₂O₃ top-layer of the support was modified with an ultra-thin (∼1 nm) amorphous alumina layer also deposited by ALD. This strategy enhances the number of nucleation sites for Pd, resulting in the formation of thin, uniform and compact membranes. It also substantially reduces Pd precursor consumption compared to conventional methods. The gas separation factors at 286 °C were 86 for H2/N2, 79 for H2/CH4 and 67 for H2/CO2. Additionally, the composite membranes demonstrated resilience to repeated temperature cycling and were able to restore their performance after exposure to trace amounts of CO.