Specific Li+ sites in a nanoporous carbon for enhanced light hydrocarbons storage and separation: GCMC and DFT simulations

Abstract

The storage and separation of light hydrocarbons (C1/C2/C3) is an important process in the petrochemical industry, but it brings considerable technical challenges. Here, we have examined the performance of Li-doped nanoporous carbon (NPC) in separation of C2 and C3 over C1 using Grand Canonical Monte Carlo calculations (GCMC), and explored the mechanism for adsorptive separation by density functional theory (DFT). In the meantime, the established model and selected force field parameters were verified through experimental data to be feasible for the storage and separation of light hydrocarbons on nanoporous carbons (NPCs). The calculation results show that the C3/C1 selectivity of NPC and NPC-OH is higher than C2/C1 selectivity. However, it is found that C2H2/CH4, C2H4/CH4 and C3H6/CH4 selectivity of NPC-Li is around 174, 71 and 336, which is higher selectivity than that of NPC (4, 7 and 79) and NPC-OH (6, 8 and 77). The enhancement of C2H2, C2H4 and C3H6 separation over CH4 is mainly due to the influences of the high adsorption energy and strong electrostatic interaction. It has been proved that the doping of Li+ into NPC is a promising adsorbent for the adsorption and separation of light hydrocarbons, and provides a novel insight for the design and development of light hydrocarbons separation materials.