Electrolytic production of NaOH and H2 from alkaline solution containing CO2 using cation exchange membranes

Abstract

Amid climate change concerns, a revolutionary reinvention of industrial processes is urgently needed to mitigate CO2 emissions. Carbon capture, storage, and utilisation (CCSU) technologies have been proposed to reduce the release of CO2 into the atmosphere. In this study, six cation exchange membranes (CEMs) in a membrane electrolysis (ME) setup are evaluated in the regeneration of NaOH and production of H2 from a CO2-captured alkaline solution. The temperature, current intensity, and catholyte type were varied in the experiments. This study focuses on the commercially available membrane CMF based on its superior performance, but similar trends were observed for all six CEMs. The results indicate that the current intensity strongly influences the membrane electrolysis performance, with a higher current density increasing H2 production and catholyte pH. Furthermore, the investigation of the influence of temperature on performance demonstrates that higher temperatures lead to reduced overpotentials and have no significant effect on H2 production or NaOH regeneration. Thus, efficient NaOH regeneration occurs at reduced currents, especially at 298–303 K. Deionised water is recommended as the ideal catholyte for enhanced performance.