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.