Amine grafting of carbazole-based hypercrosslinked polymer as an adsorbent to enhance CO2 capture

Abstract

Carbon capture and utilization by solid sorbents is considered as a promising way for the elimination of the Carbon dioxide (CO2) emission to the atmosphere. In this study, a polymeric solid sorbent specially, hypercrosslinked polymer based on carbazole monomer was synthesized through Friedel-Crafts reaction. Aim to study the effect of the resulting sample’s amination on the CO2 uptake capability, a chemical modification was applied to the adsorbent by adding groups to the resulting porous polymer skeleton. Additionally, a batch reactor was used to explore the adsorption process at temperatures between 298 K and 328 K and pressures between 1 and 9 bar, as well as the impact of temperature and pressure factors on adsorption capacity. According to findings, amine group addition to porous polymer network increased the adsorbent's adsorption capacity from 182.13 (mg/g) to 236.37 (mg/g) at 298 K and 5 bar. Isotherm, kinetic, and thermodynamic models were utilized to explore the adsorption process. According to the results, among the isotherm models, the Hill model and among the kinetic models, the fractional order model showed an excellent fitting with the experimental values. Finally, using the thermodynamic model, the values of enthalpy, entropy, and Gibbs free energy were obtained for the carbazole-based hyper cross-linked polymeric adsorbent −12.729 (kj.mol−1), −0.018 (kj.mol−1.K−1), −7.276 (kj.mol−1), respectively, and for the amine-functionalized adsorbent −19.655 (kj.mol−1), −0.037 (kj.mol−1.K−1), −8.584 (kj.mol−1), respectively.