Development of enhanced CO2 adsorbents on functionalized MCM-41 with hybrid amines

In this study, three preparation methods were used to modify MCM-41 to enhance the CO₂ adsorption capability. That is, grafting, impregnation and a two-step method combining the grafting and impregnation. It was demonstrated that amine grafting and subsequent impregnation of MCM-41 significantly enhanced the CO₂ adsorption capacity than single amine alone. The maximum adsorption capacity of 5.49 mmol g⁻¹ was obtained on MCM-41 with 1% 3-aminopropyltriethoxysilane (APTES) grafting and subsequent 60% triethylenetetramine (TETA) impregnation (named as M-1AP-60TETA), which also showed good adsorption cycling stability for ten cycles. This was attributed to the synergistic effect of APTES and TETA, where the formation of an intertwined network enhanced CO₂ diffusion and carbamate formation.