Amine-impregnated porous carbon–silica sheets derived from vermiculite with superior adsorption capability and cyclic stability for CO2 capture

Amine-functionalized adsorbents have become one of the most promising capture technologies for greenhouse gas mitigation. However, developing cost-effective adsorbents with high adsorption capacity and superior cyclic stability via temperature swing adsorption remains difficult. Herein, sandwich-like polyethyleneimine (PEI)-impregnated porous carbon–silica sheets derived from vermiculite (AEVCP) adsorbents were successfully synthesized via porous carbon network confined within acid activated expanded vermiculite derived silica (AEV) sheets and interlayer amine-functionalization with PEI impregnation. The effect of adsorption temperature on CO2 adsorption performances, adsorption/desorption kinetics and thermodynamics for AEVCP adsorbents were specifically discussed. The optimal AEVCP50 adsorbent possessed a large CO2 uptake of 1.84 mmol/g at 75 ℃ in 60 vol% CO2/40 vol% N2 and superior cyclic stability with 7.6 % decay after 10 cycles, due to the hierarchical porous structure and high thermal conductivity of porous carbon–silica sheets derived from vermiculite (AEVC) support. The unique sandwich-like features of AEVC support are favorable for the high amine loading, rapid CO2 diffusion and efficient capture. The interlayer carbon implantation and amine-functionalization with strong interlayer spatial confinement effect, can suppress the formation of urea linkages, avoid the persistent over-heating and excess amine agglomeration, and enhance the gas diffusion and thermal transfer during the adsorption isobar process, which ultimately lead to superior adsorption capability and cyclic stability for CO2 capture. This design approach of cost-effective adsorbents derived from natural minerals provides a new avenue for practical CO2 capture and separation processes.