(29) Hyeonho Joo, Sung June Cho and Kyungsu Na*, “Control of CO2 absorption capacity and kinetics by

Abstract

MgO-based dry sorbents promoted by various metal carbonate and nitrate salts were prepared via co-precipitation of three precursors (MgO/carbonate/nitrate), wherein effects of metal types in carbonate and nitrate salt, and mole ratios in MgO/carbonate/nitrate on the absorption capacity and kinetics were investigated comprehensively during CO2 absorption/regeneration cycles under temperature swing absorption process (absorption at 300 °C with 15% CO2 and regeneration at 500 °C with 100% CO2 under dry condition). The CO2 absorption capacity was analyzed with thermal gravimetric analyzer, and the absorption kinetics were compared with rate constant derived by using linear driving force model. According to the change of metal types among Li, Na, K and Ca while variation of the composition in MgO/carbonate/nitrate, CO2 absorption capacity and kinetics were changed dramatically. MgO promoted with CaCO3 and NaNO3 (MC0.19N0.20) was the best sorbent showing 30.3 wt%, but significant decrease in absorption capacity was observed during three cycles. MgO promoted with Na2CO3 and NaNO3 (MN0.19N0.15) exhibited the largest rate constant of 0.811 min−1, whereas other sorbents are distributed down to 0.046 min−1. In view of sorbent stability, MgO with K2CO3 and KNO3 (MK0.40K0.03) might be good sorbents since they showed very stable absorption/regeneration performances without significant decrease in working capacity during 10 cycles. The present result on the MgO-based sorbent preparation and CO2 absorption performances would provide important selection criteria for MgO-based dry sorbents based on high working capacity, rapid absorption rate, and stability showing stable absorption/regeneration reversibility.