Efficiency increase in hypercrosslinked polymer based on polystyrene in CO2 adsorption process

In this investigation, a hypercrosslinked polymer based on polystyrene as an adsorbent was used for CO2 adsorption. Design of experiment with response surface methodology is considered to optimize the synthesis parameters for obtaining the maximum carbon dioxide adsorption capacity. The independent parameters including the crosslinker amount (mmol), synthesis time (h) and catalyst type (FeCl3 and AlCl3) and adsorption capacity (mg/g) are considered as the dependent parameter in design of experiment method. The optimum values of crosslinker amount, synthesis time, and catalyst type to maximize adsorption capacity achieved 17.7 mmol, 14.6 h, and FeCl3, respectively. Additionally, isotherm and kinetic modeling were carried out to determine the adsorbent behavior. The results showed that Hill and Elovich models have a better precision between other isotherm and kinetic models. Finally, thermodynamic modeling was accomplished using the optimized adsorbent and the results show that physisorption is the main of CO2 adsorption by polystyrene-based adsorbent. The values of - 13.498 kJ/mol, - 0.018 kJ/mol.K, and - 8.224 kJ/mol were obtained for enthalpy differences, entropy differences, and Gibbs free energy change at 293 K and 5 bar, respectively.