Amine-functionalized mesoporous silica derived from natural phyllosilicate for efficient CO2 adsorption

Amine-functionalized mesoporous silica is considered as one of the most promising solid amine adsorbents for post-combustion carbon dioxide (CO 2 ) capture due to their high specific surface area, large pore volume and adjustable pore structure . However, the high costs associated with silica precursors and synthesis techniques of amine-functionalized mesoporous silica have extremely limited their practical applications. In this work, a facile and feasible approach was proposed to construct polyethyleneimine (PEI)-impregnated of Al-MCM-41 derived from natural flake-like kaolinite (FK) clay. The effect of PEI loadings and adsorption temperature on CO 2 uptakes, adsorption/desorption kinetics and stability for Al-MCM-41/PEI x adsorbents were specifically discussed. The optimal Al-MCM-41/PEI (AP30) adsorbent exhibited a high CO 2 uptake of 1.27 mmol/g at 75 °C and stable cyclic stability with a mere 1.1% decline per cycle over 10 adsorption-regeneration cycles, resulting from the unique ordered porous structure and spatial confinement effect of as-prepared Al-MCM-41 support to suppress excess PEI agglomeration and avoid blocking CO 2 adsorption in the resultant adsorbents. The good PEI dispersions provided abundant CO 2 affinity sites, which is beneficial to efficient CO 2 diffusion and adsorption, and thus greatly improving the CO 2 capture performances. This approach has enormous potential for cost-effective large-scale practical applications for CO 2 capture and separation processes.