Molecularly engineering polymeric membranes for <scp>H<sub>2</sub></scp>/<scp>CO<sub>2</sub></scp> separation at 100–300 °C
Leiqing Hu, Sankhajit Pal, Hien Nguyen, Vinh T. Bui, Haiqing Lin
Abstract
Abstract Over the last two decades, polymers with superior H 2 /CO 2 separation properties at 100–300 °C have gathered significant interest for H 2 purification and CO 2 capture. This timely review presents various strategies adopted to molecularly engineer polymers for this application. We first elucidate the Robeson's upper bound at elevated temperatures for H 2 /CO 2 separation and the advantages of high‐temperature operation (such as improved solubility selectivity and absence of CO 2 plasticization), compared with conventional membrane gas separations at ~35 °C. Second, we describe commercially relevant membranes for the separation and highlight materials with free volumes tuned to discriminate H 2 and CO 2 , including functional polymers (such as polybenzimidazole) and engineered polymers by cross‐linking, blending, thermal treatment, thermal rearrangement, and carbonization. Third, we succinctly discuss mixed matrix materials containing size‐sieving or H 2 ‐sorptive nanofillers with attractive H 2 /CO 2 separation properties.