Comparison of Pt and Pd catalysts for hydrogen pump separation from reformate

► H2 was purified with a PEM hydrogen pump with Pd/C catalysts. ► Pd/C catalysts were less efficient than Pt/C catalysts for H2 purification. ► CO2 adsorbs on Pd catalysts reducing the electroactive surface area. ► The effective MEA resistance increases with decreases in H2 partial pressure. ► Gas phase diffusion contributes to the effective MEA resistance.