Anodic Pd membrane H2 extraction enhances thermochemical dehydrogenation.

Dehydrogenation reactions underpin fuel processing1, chemical synthesis2 and hydrogen storage and transport3. Many are endothermic and kinetically inhibited by H2, leading to low single-pass yields at moderate temperatures4. These reactions can be promoted by integrating the catalyst with a hydrogen-selective membrane, which relies on an H2 partial pressure differential to drive in situ hydrogen removal5. However, this approach often results in limited hydrogen flux, reduced mechanical stability and low recovered hydrogen partial pressures6. Here we use a hydrogen-selective Pd-based membrane as the anode of a molten-hydroxide electrochemical cell with a hydrogen-evolving cathode. This construct enables electrochemically driven H2 separation at dehydrogenation temperatures without a pressure differential. We demonstrate that low anode potentials of <0.3 V versus the reversible hydrogen electrode are sufficient to drive diffusion-limited H transport across the membrane. Compared with pressure-driven processes, this approach enables a 4-fold enhancement in the hydrogen separation rate at 300 °C, while enriching H2 from 0.05 atm (balance Ar) to a pure 1.0 atm H2 stream. Interfacing the anode with a dehydrogenation catalyst enables the conversion of ammonia and methylcyclohexane at 250 °C up to 91% and 94%, respectively. This work provides a proof-of-concept demonstration for electrochemically assisted hydrogen removal to enhance selected dehydrogenation reactions.