First approaches for hydrogen production by the depolarized electrolysis of SO2 using phosphoric acid doped polybenzimidazole membranes

• Published in: International journal of hydrogen energy Vol. 46; no. 58; pp. 29763 - 29773
• Main Authors: Díaz-Abad, Sergio, Rodrigo, Manuel A., Lobato, Justo
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 23.08.2021
• Subjects: Hydrogen; Ohmic resistance; Polybenzimidazole (PBI); SO2 electrolysis; Ohmic resistance; Polybenzimidazole (PBI); Hydrogen; SO2 electrolysis
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.06.117

Renewable energy storage and conversion is nowadays a major target for the scientific community. Their conversion into hydrogen is a clear and clean alternative for their storage. This work shows, for the first time, the results of the SO2 depolarized electrolysis for hydrogen production at high temperature (120–170 °C) using phosphoric acid doped polybenzimidazole (PBI) membranes. A standard and a thermally cure PBI membrane doped with phosphoric acid were used for manufacturing the MEA of two electrolyzers. The benefit of the temperature was demonstrated but an unexpected behavior occurs at voltages higher than 0.8 V when temperature increases. Moreover, the thermally cured membrane shows a superior performance as compared with the standard one. Production of sulfur by reduction of SO2 becomes an important drawback and advices not operating above 130 °C. Results show that PBI membranes doped with phosphoric acid are suitable for high temperature operation for the sulfur dioxide depolarized electrolysis. Increasing temperature is beneficial up to a certain value of potential, showing a considerable influence in the charge transfer resistance of the system. •Westinghouse electrolyzer operated successfully with PBI membranes.•Higher conductivities when membranes are doped with phosphoric acid.•First results above 120 °C with H3PO4 doped PBI membranes for SO2 electrolysis.•Operation under 140 °C allows minimizing the formation of sulfur.•Advanced PBI membranes outperform the standard PBI for SO2 electrolysis.