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

摘要

In order to separate a mixture of hydrogen ( $$ ext {H}_,$$ ) and carbon dioxide ( $$ ext {CO}_,$$ ) 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 ( $${{-} ext {C}{ quiv} ext {C}{-} ext {C}{ quiv} ext {C}{-}}$$ ) bonds linkages and replacing with hydrogen atoms in graphdiyne structure. Our DFT calculations exhibit poor selectivity and good permeances for $$ ext {H}_,$$ / $$ ext {CO}_,$$ gases passing through this membrane. To improve the performance of the GDY-H membrane for $$ ext {H}_,$$ / $$ ext {CO}_,$$ 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 $$ ext {H}_,$$ / $$ ext {CO}_,$$ is increased from 5.65 to completely purified $$ ext {H}_,$$ gas at 300?K. Furthermore, GDY-H membrane represents excellent permeance, about $$10^8$$ gas permeation unit (GPU), for $$ ext {H}_,$$ molecule at temperatures above 20 K. The $$ ext {H}_,$$ 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 $$ ext {H}_,$$ purification and $$ ext {CO}_,$$ capture processes in the industry.