Multifunctional strain-controlled graphdiyne membrane for gas separation: a theoretical study

X Zheng and B Liu and GJ Chen, MOLECULAR SIMULATION, 48, 866-871 (2022).

DOI: 10.1080/08927022.2021.1926456

Graphdiyne (GDY) membrane with intrinsic pore has potential for gas separation. Here we report a multistage gas separation of H-2/CO2/N-2/CH4 gas mixture through graphdiyne by applying tensile strain using molecular dynamics simulation. The results indicate that gas permeability is remarkably enhanced through tensile strain. H-2 molecules have always been able to penetrate GDY membrane, while all CH4 molecules are blocked during the progress of tensile strain up to ultimate strain. An ultrahigh H-2 permeance of similar to 10(6) GPU (gas permeation unit) and H-2 selectivity towards CO2/N-2/CH4 was obtained, which is larger than the acceptable value in industrial applications. As the tensile strain is between 7.5% and 10% (epsilon(x))-15%(epsilon(y)), the membrane adopted in this work can be utilised for separating CO2 from CO2/N-2/CH4 mixture. When the strain level is beyond 10% (epsilon(x))-15% (epsilon(y)), the strained GDY can be served as a CH4 upgrading membrane. The ultrahigh gas permeance is ascribed to the ultrathin membrane and high-density pore, and the size sieving effect of GDY membrane with small pores is responsible for the excellent gas selectivity. The results suggest that these two-dimensional membranes with intrinsic pores could serve as the ideal multifunctional size- selective membrane for gas separation towards different separation requirements.

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