Combined generation and separation of hydrogen in an electrochemical water gas shift reactor (EWGSR)

Hydrogen rich gas, originating from fossil fuel reforming processes or biomass gasification, contains a significant amount of CO. Typically, the yield of H2 is increased with subsequent water gas shift units, converting CO to CO2 and additional H2. This study describes a new reactor concept enabling the water gas shift reaction and the separation of the generated hydrogen in one process step by using electrical energy. This electrochemical water gas shift reactor applies a H3PO4-doped Poly(2,5-benzimidazole) membrane as electrolyte and carbon supported Pt or PtRu as anode catalyst. The reactor operation was investigated at 130 °C and 150 °C with a H2 free anode feed stream of humidified CO and N2. The experimental results show the feasibility of the reactor concept, as H2 was generated at the cathode according to Faradays Law. Anodic PtRu led to lower power demands than Pt. The operation at the two temperatures showed that 130 °C results in a lower electrical power demand while generating an equal amount of H2. The feasibility of the reactor was assessed using exergy efficiency analysis.

► Electrochemical water gas shift reaction for combined generation and separation of H2. ► H2 generation rate and CO oxidation rate follow Faradays law. ► Low temperature operation results in a lower electrical power demand. ► Exergy analysis of the proposed electrochemical water gas shift reactor concept.