Thermodynamics and regeneration of CO2 adsorption on mesoporous spherical-silica particles

Mesoporous spherical-silica particles (MSPs) were modified by N-[3-(trimethoxysilyl) propyl]ethylenediamine (EDA) solution and were employed as sorbents to study thermodynamics and regeneration of CO2 adsorption from gas streams. The thermodynamic analysis gave low isosteric heats of adsorption, which are typical for physical adsorption. The cyclic CO2 adsorption on MSP(EDA) showed that the adsorbed CO2 could be effectively desorbed via thermal treatment at 120 °C for 25 min while the adsorbed CO2 due to physical interaction could be effectively desorbed via vacuum suction at 0.145 bar for 30 min. If a combination of thermal treatment and vacuum suction was conducted at 120 °C and 0.145 bar, the time for effectively desorbing CO2 could be shortened to 7.5 min and thus reduces a significant amount of energy penalty. The adsorption capacities and the physicochemical properties of MSP(EDA) were preserved after 15 cycles of adsorption and regeneration. These results suggest that the MSP(EDA) can be stably employed in the prolonged cyclic adsorption and that they are thus possibly cost-effective sorbents for CO2 capture from flue gases.