Mechanically robust silane-engineered aerogels for high-affinity CO2 chemisorption under low-pressure, high-temperature conditions

Abstract Developing solid sorbents that combine mechanical robustness with strong CO 2 affinity under low-pressure and elevated-temperature conditions remains a major challenge for practical carbon capture. Here, we report a silane-engineered silica–polymer hybrid aerogel platform in which organosilanes are deposited onto a reinforced SiA framework to simultaneously strengthen the skeleton and regulate the interfacial organization of a PEI/Zn/ionic-liquid active phase. Among the silanes examined, vinyltriethoxysilane affords the largest mechanical enhancement, increasing the compressive strength of the aerogel from 2.14 to 5.32 MPa (+ 148.6%) while preserving a porous network. After loading polyethyleneimine, zinc acetate, and [EMIm]Br, the APTES-derived sorbent, SiA–A(24)–PZI, exhibits the best CO 2 capture performance, reaching 2.95 mmol g − 1 (+ 31.7%) at 298 K and 1 bar, 2.05 mmol g − 1 at 50 mbar, and 1.61 mmol g − 1 at 343 K and 30 mbar. Under simulated flue-gas conditions, it delivers a dynamic CO 2 capacity of 2.19 mmol g − 1 under dry breakthrough and 2.27 mmol g − 1 under humid breakthrough, while maintaining high CO 2 /N 2 selectivity and stable cycling behavior. Toth-model fitting, Qst–uptake analysis, in situ DRIFTS, DFT calculations, and conversion-dependent diffusivity modeling collectively reveal two distinct adsorption regimes: APTES-derived sorbents are dominated by amine-rich chemisorption with cooperative stabilization of carbamate/bicarbonate-type intermediates, whereas VTES-derived sorbents show a stronger contribution from micropore-assisted adsorption. These results establish silane engineering as an effective strategy for coupling framework reinforcement, active-phase organization, and adsorption energetics in hybrid aerogel sorbents.