Improving CO2 /N2 and CO2/H2 Selectivity of Hypercrosslinked Carbazole-Based Polymeric Adsorbent for Environmental Protection

In this study, carbazole-based hypercrosslinked polymer (HCP) adsorbent was synthesized using the knitting method by Friedel-Crafts reaction. The effects of crosslinker to carbazole ratio and synthesis time on the adsorbent structure were investigated to improve CO2/N2 and CO2/H2 selectivity. Crosslinker to carbazole ratio and the synthesis time was considered in the range of 1-4 (mol/mol) and 8-18 (h), respectively. HCP adsorbents were analyzed by energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-teller analysis (BET). The adsorption capacity of CO2, N2, and H2 were measured by carbazole-based HCP and it was correlated with the nonlinear form of the Langmuir isotherm model. The achieved BET surface area of adsorbent with the highest amount of synthesis parameters was 922 (m2/g). The ideal adsorbed solution theory (IAST) was utilized to anticipate CO2/N2 and CO2/H2 selectivity at 298 k and 1 bar. CO2/N2 and CO2/H2 selectivity for adsorbent with the maximum amount of synthesis parameters were 8.4 and 4.4, respectively. The high selectivity values of carbazole-based HCPs are due to the presence of nitrogen atoms in the adsorbent structure and a more robust interaction between CO2 molecules and the adsorbent surface.