Membrane-cryogenic hybrid CO2 capture—A review

The membrane-cryogenic hybrid process is a promising CO₂ capture process, which combines the advantages of membrane and cryogenic, such as high efficiency (up to 98 % CO₂ captured) and low energy consumption (specific energy consumption around 1.7 MJ/kg CO₂ avoided). Through pretreatment by membranes, CO₂ concentration can be increased, which makes it possible to separate CO₂ via phase change in the cryogenic unit. This work reviews the current status of the development of membrane-cryogenic hybrid processes. The synergy between membrane and cryogenic separation is summarized to identify the bottleneck of such processes and provide insights for process improvement. It was found that cold temperatures would be beneficial to reduce CO₂ activation energy and then improve CO₂ selectivity of membranes. To further improve the CO₂ separation performance, the potential intensification methods of the membrane-cryogenic hybrid process including cold-membrane synthesis, process optimization via heat integration are discussed and envisioned.