Molecular elucidation of sub‐3 Å gas transport in ultramicroporous carbon molecular sieve membranes
Mengjie Hou, Xinyu Dong, Li‐Qiang He, Lin Li, Tonghua Wang, Peng‐Cheng Ma, Hui LiAbstract
Carbon molecular sieve membranes (CMSMs) are highly desirable for industrial gas separation. However, a molecular‐level understanding of their gas transport characteristics and separation mechanisms, governed by ultramicropores, remains challenging, especially for gas molecules with sub‐3 Å dimensions. Herein, we investigate the transport behavior of sub‐3 Å gas molecules (H 2 , He, and Ne) in the ultramicroporous CMSM using experimental‐based atomic modeling and simulations. Results demonstrate that the H 2 /He selectivity exceeding that of Knudsen diffusion arises from kinetic configurational confinement imposed by ultramicropores, specifically due to the slender geometry of H 2 and its smaller critical diameter (2.38 Å versus 2.79 Å for He). Unlike H 2 and He, Ne exhibits preferential adsorption within CMSM, which induces significant ultramicropore shrinkage during transport, especially at low operating temperatures, leading to remarkably enhanced He/Ne sieving capability. These results provide an in‐depth and molecular perspective on efficient sub‐3 Å gas separation using CMSMs.