Supported palladium membrane reactor architecture for electrocatalytic hydrogenation
Electrolytic palladium membrane reactors offer a means of hydrogenation that utilizes hydrogen derived from water electrolysis instead of hydrogen gas. Previous embodiments of these reactors employ expensive palladium foil membranes (≥25 µm thickness). We report here that the amount of palladium used in these membrane reactors can be reduced by depositing a thin (1–2 µm) layer of palladium onto a porous polytetrafluoroethylene (PTFE) support. This supported palladium membrane was designed to ensure fast solvent and/or electrolyte diffusion to the palladium layer. The hydrogenation of 1-hexyne, for example, shows that the Pd/PTFE membrane demonstrates consumption rates of 0.71 mmol h-1, which is comparable to 0.92 mmol h-1 measured for high-surface area palladium (with Pd catalyst). The high porosity of the PTFE enables a 12-fold increase in electrocatalytic surface area at the Pd–PTFE interface compared to planar palladium foil membranes. We show here a pathway for creating supported membranes that can lead to a cost-effective and potentially scalable electrolytic palladium membrane reactor.