Amine functionalized mesocellular silica foam as highly efficient sorbents for CO2 capture

A series of amine-functionalized CO2 sorbents were synthesized by grafting mono-and tri-amine substituted trialkoxysilanes on mesocellular siliceous foam (MCF) via a facile wet grafting method. The effect of amine type, amine loading level, and porous structure of silica on the CO2 adsorption performance was investigated. MCF silica with a three-dimensional (3D) interconnected porous structure was found to be suitable for preparing amine-grafted sorbents. Tested at 25 C and 0.15 bar of CO2, the mono-and tri-amine grafted MCFs exhibited a fast adsorption rate and excellent CO2 adsorption capacity of 1.71 mmol/g for mono-amine and 2.07 mmol/g for tri-amine, which was much higher than amine grafted PQ and SBA-15 with a 2D porous structure, and the amine grafted silica sorbents prepared in previous studies. The large pore volume and pore size coupled with superior interconnectivity of MCF enable more surface silanol groups available and accessible for amino silanes, leading to a high amine loading level and excellent amine dispersion on the silica surface, which enhances both the CO2 adsorption capacity and adsorption rate of the developed sorbents. Cyclic adsorption-desorption tests confirmed the excellent stability of the amine grafted MCF.