Hyper-cross-linked polymers (HCPs), as one of the variety of microporous polymers with nanosized pores, have attracted a lot of interest in carbon dioxide adsorption and storage. A HCP adsorbent based on benzene and Friedel–Crafts reaction was synthesized for CO2 adsorption. The response surface methodology is suggested for optimizing the process parameters in order to determine the highest possible CO2 adsorption capacity of the HCP adsorbent. Pressure, temperature, ratio (cross-linker/benzene), and synthesis time are considered as activation parameters, and adsorption capacity (mg/g) is proposed as the response of this method. Additionally, experimental adsorption data were fitted by the adsorption isotherm and kinetic models to obtain the adsorbent behavior. Finally, thermodynamic modeling was accomplished and enthalpy, entropy, and Gibbs free energy differences of adsorption at 293 K were obtained at −20.612 kJ/mol, −0.043 kJ/mol K, and −7.950 kJ/mol, respectively. The optimum values of pressure, temperature, ratio (cross-linker/benzene), and synthesis time within the experimental range that maximize CO2 adsorption capacity were obtained at 7.8 bar, 294 K, 2.75, and 13.6 h, respectively. The optimized value of CO2 adsorption capacity by benzene-based HCP was obtained as 262 mg/g.

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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/N2 and CO2/H2 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/N2 and CO2/H2 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 cross-linker 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.

In this work, benzene based hypercrosslinked polymer (HCP) as an adsorbent was modified using amine group to enhance CO2 uptake capability and selectivity. Based on BET analysis result, the HCP and the modified HCP provide surface area of 806 (m2 g−1) and micropore volume of 453 (m2 g−1) and 0.19 (cm3 g−1) and 0.14 (cm3 g−1), respectively. The CO2 and N2 gases adsorption were performed in a laboratory scale reactor at a temperature between 298 and 328 K and pressure up to 9 bar. The experimental data were evaluated using isotherm, kinetic and thermodynamic models to identify the absorbent behavior. The maximum CO2 adsorption capacity at 298 K and 9 bar was obtained 301.67 (mg g−1) for HCP and 414.41 (mg g−1) for amine modified HCP. The CO2 adsorption thermodynamic parameters assessment including enthalpy changes, entropy changes, and Gibbs free energy changes at 298 K were resulted − 14.852 (kJ mol−1), − 0.024 (kJ mol−1 K−1), − 7.597 (kJ mol−1) for HCP and − 17.498 (kJ mol−1), − 0.029(kJ mol−1 K−1), − 8.9 (kJ mol−1) for amine functionalized HCP, respectively. Finally, the selectivity of the samples were calculated at a CO2/N2 composition of 15:85 (v/v) and 43% enhancement in adsorption selectivity at 298 K was obtained for amine modified HCP.

In this study, experimental tie-line data for the ternary system containing water, citric acid, and 1-decanol were measured at various temperatures (298.2, 308.2, 318.2, and 328.2 K) and atmospheric pressure (101.3 ± 0.4 kPa). The reliability and consistency of the liquid−liquid equilibrium experimental data were evaluated by the Othmer−Tobias and Hand equations. The distribution coefficients and separation factor of this system for solvent capability were calculated. The maximum of separation factor for 1-decanol as solvent was obtained as 4.25 at 298.2 K and decreases with increasing temperature and citric acid concentration. Finally, by using the genetic algorithm method, interaction parameters of the NRTL thermodynamic model were measured for these experimental data. The values of the parameters of this model were evaluated with the root-mean-square deviation (rmsd) method. The average rmsd value between the experimental and calculated mass fraction was 0.1984% for the NRTL model. The rmsd values demonstrate that the NRTL model is suitable for description of phase behavior and can be applied to this system.