Preparation, Characterization and CO ₂ Adsorption Performance and Mechanism of Cross-Linked Polystyrene Resin Composites

The porous resin microspheres possess characteristics such as high specific surface area, adjustable pore structure and modifiable surface chemical properties, thus having great potential in CO2 adsorption. In this study, cross-linked polystyrene resins with varying degrees of cross-linking were prepared through suspension polymerization, and then modified to obtain cross-linked resin-based composite materials. Under the conditions of 60 °C and 0.1 MPa pressure, when the content of divinylbenzene (DVB) was 60 wt % and triethylenetetramine (TEPA) was 40 wt %, the CO2 adsorption capacity reached 4.46 mmol/g, which was significantly higher than that of pure polystyrene resin (1.68 mmol/g). A three-dimensional cross-linked system model composed of DVB and polystyrene was constructed by molecular dynamics simulation. The adsorption sites of CO2 and N2 in the material were mapped using the Grand canonical Monte Carlo (GCMC) simulation. Through thermodynamic analysis, adsorption isotherm modeling, and kinetic calculations, the exothermic nature of the adsorption process on amine-modified cross-linked resin was established. These findings indicate a monolayer adsorption mechanism, thereby confirming the predominance of chemisorption and the presence of surface diffusion behavior. Density functional theory (DFT) calculations were performed to quantify the interaction strength between gas molecules and the material surface through adsorption heat analysis. Additionally, the impact of H2O on the adsorption process was investigated by combining transition state search techniques to identify key intermediates in the adsorption reaction and charge density analysis to elucidate charge transfer mechanisms between H2O molecules, the adsorbent, and target gas molecules.