CO2, N2, and H2 Adsorption by Hyper-Cross-Linked Polymers and Their Selectivity Evaluation by Gas-Solid Equilibrium

In this study, the effect of hyper-cross-linked adsorbent structural parameters on gas adsorption and selectivity was investigated. Hyper-cross-linked polymere (HCP) adsorbents were synthesized based on three widely used monomers, such as benzene, polystyrene, and carbazole. Cross-linker value and synthesis time were considered as structural parameters. The selectivities of CO2/N-2 and CO2/H-2 at 1 bar and 298 K were evaluated by the ideal adsorption solution theory (IAST) method. The results showed that carbazole-based HCP adsorbents had higher selectivity of CO2/N-2 and CO2/H-2 than benzene- and polystyrene-based HCPs, and also benzene-based HCPs had higher adsorption capacity. In all three adsorbents, selectivity increases with increasing synthesis time at a constant cross-linker value. In benzene- and carbazole-based adsorbents, selectivity increases with increasing crosslinker value in constant synthesis time, while in polystyrene-based adsorbents, it decreases. Finally, the real adsorption solution theory (RAST) and activity coefficient in the gas-solid equilibrium was applied due to the difference between real and computational mole fractions in the adsorbed phase. The activity coefficient constants were calculated by genetic algorithm and minimization of difference between experimental and calculated data. The results show that the calculated data with the RAST method have a good agreement with experimental data.