Highly selective 3D porous graphene membrane for organic gas separation derived from polyphenylene.

In this paper, a 3D nanoporous carbon molecular sieve (CMS) membrane is proposed to investigate the diffusion and separation properties of ethylene/methane and ethylene/acetylene binary mixtures permeating through the structural deformated carbon nanotube (CNT) channels. Combining the results obtained from density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we find that the organic gas permeability and selectivity can be effectively ameliorated by fine-tuning the geometric structure of CNTs gas separation channels. By virtue of the intrinsic structural characteristics, this hybrid CMS configuration established elliptical cylinder channels to separate the organic gas molecules with similar molecular size. Compared with channels with a circular cross section, the gas selectivity for channels with an elliptical cross section is larger, and it increases with an increasing pressure. The selectivity of ethylene over acetylene (methane) increased to ~13.8 (5.5) in deformed CNTs channels, which is more than doubled over the original CNT channels. This distinguished hybridization configuration may pave a promising avenue to utilize gas separation materials. The lateral view of ethylene over acetylene binary mixture (1:1, v/v) separation at 80 bar. Image 1 • A CMS with elliptical cylinder channels separates gas with similar molecular size. • The gas selectivity is effectively ameliorated by fine-tuning the CNT structure. • The selectivity of ethylene over acetylene (methane) is about 13.8 (5.5). [ABSTRACT FROM AUTHOR]