Amine-Modified Mesoporous Silica for CO2 Adsorption: The Role of Structural Parameters

The present study investigated the role of structural parameters such as pore size, pore volume, and specific surface area of mesoporous silica on the CO 2 sorption performance of various amine-functionalized adsorbents. A series of mesoporous silica with different structural properties KIT-6, MCM-41, SBA-15, and HV MCM-41 were synthesized and functionalized with pentaethylenehexamine (PEHA) by wet impregnation. The CO 2 sorption performances of the sorbents were evaluated using high pressure gas adsorption analyzer. The sorption capacity of adsorbents follows the order: MCM-41 < HV MCM-41 < SBA-15 ≈ KIT-6 at 105 °C and 1 bar. Larger pore size reduces the mass transfer resistance, and large pore volume improves the PEHA distribution inside the pores. The high specific surface area has little impact during adsorption. Due to the 3D structure with interconnected pores, KIT-6 shows the lowest heat of regeneration (57.8 kJ/mol CO 2 ) during adsorption. The PEHA-impregnated KIT-6 (K-60 PEHA) shows the highest sorption capacity 4.48 mol CO 2 /g at 105 °C and 1 bar. It also exhibit fairly stable sorption performance up to 10 adsorption/desorption cycles between in the temperature range of 90–105 °C.