ABSTRACT The excessive consumption of fossil fuels has triggered a dramatic surge in CO 2 emissions, prompting the development of diverse mitigation strategies. Among these, the functionalization of metal–organic frameworks (MOFs) with polar amine moieties has emerged as a promising approach to substantially enhance their CO 2 capture capacity. In this study, HKUST‐1 was synthesized via a solvothermal method and then modified with three different amines (DEA, TEPA, and PEI) by impregnation to prepare a series of solid amine adsorbents. The effects of the amine type, amine loading, and environmental parameters, including temperature, gas flow rate, CO 2 concentration, and humidity, on the CO 2 adsorption performance were systematically studied. Thermal stability, cycling performance, and adsorption kinetics were also evaluated. The results show that the PEI‐modified adsorbent exhibits the best performance, with an optimal amine loading of 20%. Excessive amine loading leads to pore blockage and reduces adsorption capacity. Compared to unmodified HKUST‐1, PEI20@HKUST‐1 shows a 92% enhancement in CO 2 adsorption, attributed to PEI's bidentate adsorption mechanism and flexible polymeric chains, which contribute to a high amine utilization efficiency. Among the environmental factors studied, higher temperatures lower the CO 2 uptake due to thermodynamic constraints, whereas increasing flow rate and humidity first promotes and then suppresses adsorption. The optimal adsorption conditions are identified as 30°C, 20 mL min −1 flow rate, and 45% relative humidity. Moreover, PEI20@HKUST‐1 displays good thermal stability and excellent cycling performance, retaining 88% of its initial adsorption capacity after 15 consecutive adsorption–desorption cycles. Kinetic analysis confirms that the adsorption process follows the Avrami model, which indicates a combined physisorption and chemisorption mechanism.
Zhang et al. (2026) studied this question.