Supported Hybrid Amines Within Porous Aluminosilicate Clays with Natural Different Morphologies for Efficient CO2 Capture

The urgent need for efficient CO2 capture technologies has driven research into amine-functionalized adsorbents, though existing methods face trade-offs between adsorption capacity and cycling stability. This study addresses these limitations by developing a novel hybrid modification strategy combining chemical grafting and physical impregnation on polymorphic kaolinite minerals. Through systematic acid leaching and hybrid grafting–impregnation amine functionalization, the adsorbents with hierarchically porous structures and optimized performances are synthesized. The tubular adsorbent (ATK-APTES-PEI) demonstrated exceptional performance, achieving a CO2 uptake of 1.68 mmol/g at 75 °C under a 60% CO2/40% N2 mixed gas flow, with only 5.3% capacity loss after 10 adsorption–desorption cycles, significantly outperforming both rod-like (ARK-APTES-PEI, 1.55 mmol/g) and flake-like (AFK-APTES-PEI, 1.23 mmol/g) variants. The unique pore structure of ATK-APTES-PEI enables simultaneous high amine loading and maintained gas diffusion pathways, while the hybrid modification strategy synergistically enhances both adsorption capacity and stability by increasing active surface sites. These findings establish critical structure–property relationships for mineral-based adsorbents and demonstrate a scalable approach for industrial CO2 capture applications. The work provides a blueprint for designing cost-effective, stable adsorbents using abundant clay minerals, bridging materials science with environmental engineering for sustainable carbon management solutions.