A new approach to separate hydrogen from carbon dioxide using graphdiyne-like membrane

Abstract

In order to separate a mixture of hydrogen (text {H}_{2}) and carbon dioxide (text {CO}_{2}) gases, we have proposed a new approach employing the graphdiyne-like membrane (GDY-H) using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. GDY-H is constructed by removing one-third diacetylenic ({{-}text {C}{equiv}text {C}{-}text {C}{equiv}text {C}{-}}) bonds linkages and replacing with hydrogen atoms in graphdiyne structure. Our DFT calculations exhibit poor selectivity and good permeances for text {H}_{2}/text {CO}_{2} gases passing through this membrane. To improve the performance of the GDY-H membrane for text {H}_{2}/text {CO}_{2} separation, we have placed two layers of GDY-H adjacent to each other which the distance between them is 2 nm. Then, we have inserted 1,3,5-triaminobenzene between two layers. In this approach, the selectivity of text {H}_{2}/text {CO}_{2} is increased from 5.65 to completely purified text {H}_{2} gas at 300 K. Furthermore, GDY-H membrane represents excellent permeance, about 10^8 gas permeation unit (GPU), for text {H}_{2} molecule at temperatures above 20 K. The text {H}_{2} permeance is much higher than the value of the usual industrial limits. Moreover, our proposed approach shows a good balance between the selectivity and permeance parameters for the gas separation which is an essential factor for text {H}_{2} purification and text {CO}_{2} capture processes in the industry.