(39e) Amine-Modified Mesoporous SiO2 Spheres As a Promising CO2 Capture Sorbent

Designing effective CO₂ adsorbents requires optimizing both adsorption capacity and selectivity. In this study, we developed a hybrid organic-inorganic sorbent by functionalizing mesoporous silica spheres (MSS) with aminopropyltriethoxysilane (APTMS) to overcome common limitations such as low selectivity and limited adsorption capacity. A series of MSS-(x%)APTMS samples were synthesized, where x (0%, 1.5%, 7.5%, and 15%) represents the weight percentage of APTMS relative to the total weight of the MSS framework.. Thermogravimetric analysis (TGA) showed that MSS-(15 wt.%) APTMS exhibited the highest CO₂ adsorption capacity at 2.5 wt.% (0.56 mmol/g). Cyclic adsorption tests confirmed its stability and reproducibility over multiple cycles. CO₂ adsorption was further evaluated at pressures ranging from 0 to 120 kPa at 0°C, with MSS-(15 wt.%) APTMS achieving a maximum uptake of 2.33 mmol/g at 120 kPa. Comprehensive FTIR and TEM analyses confirmed the successful incorporation of amine functional groups while maintaining the MSS framework’s morphology. The adsorption kinetics were studied at various temperatures using pseudo-first-order and pseudo-second-order models, offering insights into the interaction mechanisms between CO₂ and the functionalized sorbents. Comparative studies with SBA-15 and fumed silica functionalized with the same APTMS concentration demonstrated the superior performance of MSS-(15 wt.%) APTMS in CO₂ capture. These results highlight MSS-APTMS as an effective sorbent, particularly suitable for CO₂ capture under near-room-temperature conditions.