Shraavya RaoXuepeng DengChanglong ZouBabul PrasadYang HanLI-CHIANG LINW.S. Winston Ho2024-10-292024-10-29202420507488https://www.scopus.com/record/display.uri?eid=2-s2.0-85205927456&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/722615Facilitated transport membranes (FTMs) show great promise for H2S/CO2 separation, an industrially important yet challenging process. Herein, we report FTMs with excellent H2S/CO2 separation performance and investigate how contradictory thermodynamic and kinetic reaction preferences affect FTM selectivity. For membranes based on an extremely sterically hindered di-tert-butylamine carrier, CO2 transport occurs exclusively via a slow bicarbonate pathway. Reducing the membrane thickness shifts the reaction preference from the thermodynamically favored bicarbonate pathway to the kinetically favored amine-H2S reaction, leading to a 10-fold improvement in H2S/CO2 selectivity. This unusual trend of increasing selectivity with decreasing thickness, the opposite of typical FTMs, enables simultaneous improvements in membrane permeance and selectivity. This translates to an exceptional H2S/CO2 permselectivity of 20, and an overall separation performance surpassing the H2S/CO2 upper bounds.true[SDGs]SDG13journal article10.1039/d4ta04997g2-s2.0-85205927456