Optimum design and characteristics of potassium-based sorbents using SiO2 for post-combustion CO2 capture

SiO2 is a common material and is used in various industrial fields. However, the potassium-based sorbents using SiO2 as a support have the low CO2 capture capacities. In this study, the CO2 sorption and regeneration properties of potassium-based sorbents using SiO2 as a support were investigated to determine the cause of the low CO2 capture capacities. In addition, an optimum design method of the potassium-based sorbents using SiO2 as a support having excellent performance was proposed. The CO2 capture capacities of the sorbents decreased as the calcination temperature increased from 500 °C to 700 °C owing to the disappearance of the active material (K2CO3) through the formation of inactive components, such as K2Si2O5 and K2Si4O9. On the other hand, the potassium-based sorbent using SiO2 calcined at 500 °C had a high CO2 capture capacity of 152.3 mg CO2/g sorbent and excellent regeneration properties under the process simulation conditions. Control of the calcination temperature and the mole ratio of K2CO3 to SiO2 was important for obtaining the sorbents with a high CO2 capture capacity. Consequently, SiO2 can be used as a support or additive material in the design of potassium-based sorbents with a high CO2 capture capacity and excellent regeneration properties for post-combustion CO2 capture by controlling the amount of inactive component formed in the calcination process.