Quantifying resistances in composite palladium membranes for hydrogen production and purification

Porous supports enable significant reductions in palladium (Pd) thickness and cost but can impart significant resistance that limits overall membrane performance. In this study, composite membranes with varying Pd thickness were fabricated on yttria-stabilized zirconia (YSZ) and alumina (Al 2 O 3 ) supports. A combination of modeling and experiment were used to identify and quantify the factors that contribute to overall performance: bulk resistance, interfacial resistance and Pd quality. The bulk resistance of both supports obeyed Darcy's law under relevant conditions. Despite possessing greater bulk resistance, alumina supports produced superior membranes with up to 2X greater hydrogen permeance than YSZ due to reduced interfacial resistance and no deterioration of Pd quality. The framework introduced here provides an efficient means to assess the rate-limiting factor(s) in composite Pd membrane performance and identify pathways for further improvement. This work demonstrates that material compatibility is as important as structural properties when selecting membrane supports. • Hydrogen permeance of composite palladium membranes supported on porous symmetric and asymmetric ceramics compared. • Pd deposition introduces an interfacial resistance that can significantly reduce permeance. • A model was developed to extract and quantify resistances from experimental data. • Al 2 O 3 supports exhibit lower interfacial resistance and higher Pd quality than those supported on YSZ.