Organic amine-modified mesoporous carriers are considered potential CO₂ sorbents, in which the CO₂ adsorption performance was limited by the agglomeration and volatility of liquid amines. In this study, four additives of ether compounds were separately coimpregnated with polyethylene polyamine (PEPA) into MCM-41 to prepare the composite chemisorbents for CO₂ adsorption. The textural pore properties, surface functional groups and elemental contents of N for MCM-41 before and after functionalization were characterized; the effects of the type and amount of additives, adsorption temperature and influent velocity on CO₂ adsorption were investigated; the amine efficiency was calculated; and the adsorption kinetics and regeneration for the optimized sorbent were studied. For 40 wt.% PEPA-loaded MCM-41, the CO₂ adsorption capacity and amine efficiency at 60 °C were 1.34 mmol/g and 0.18 mol CO₂/mol N, when the influent velocity of the simulated flue gas was 30 mL/min, which reached 1.81 mmol/g and 0.23 mol CO₂/mol N after coimpregnating 10 wt.% of 2-propoxyethanol (1E). The maximum adsorption capacity of 2.16 mmol/g appeared when the influent velocity of the simulated flue gas was 20 mL/min. In addition, the additive of 1E improved the regeneration and kinetics of PEPA-loaded MCM-41, and the CO₂ adsorption process showed multiple adsorption routes.

Every late autumn, fluttering poplar leaves scatter throughout the campus and city streets. In this work, poplar leaves were used as the raw material, while H₃PO₄ and KOH were used as activators and urea was used as the nitrogen source to prepare biomass based-activated carbons (ACs) to capture CO₂. The pore structures, functional groups and morphology, and desorption performance of the prepared ACs were characterized; the CO₂ adsorption, regeneration, and kinetics were also evaluated. The results showed that H₃PO₄ and urea obviously promoted the development of pore structures and pyrrole nitrogen (N–5), while KOH and urea were more conductive to the formation of hydroxyl (–OH) and ether (C–O) functional groups. At optimal operating conditions, the CO₂ adsorption capacity of H₃PO₄– and KOH–activated poplar leaves after urea treatment reached 4.07 and 3.85 mmol/g, respectively, at room temperature; both showed stable regenerative behaviour after ten adsorption–desorption cycles.

3-Aminopropyltrimethoxysilane (APTS) and tetraethylenepentamine (TEPA)-co-functionalized mesoporous silica gel (MSG) composites were prepared for CO₂ adsorption. The surface functional groups, thermal stability, and pore structures of the composites were tested using FT-IR, TGA, and N₂ adsorption–desorption techniques, respectively. The effects of the amine loading, adsorption temperature, and influent flow rate on CO₂ adsorption were experimentally investigated. The results indicate that the synergistic effects of APTS, TEPA, and Si-OH on MSG enhanced CO₂ adsorption performance. In addition, the amine-co-modified MSG exhibited good cyclic regenerability and rapid adsorption kinetics.