Development of stabilized Ca-based CO2 sorbents supported by fly ash

The rapid decay of CO2 capture capacity during the calcination/carbonation cycles is one major problem of the calcium looping technology. To improve and maintain excellent CO2 capture performance of sorbents is of significance, especially in an environmental friendly and cost effective way. Using fly ash, the solid waste captured by collectors from coal combustion systems to modify calcium based sorbents is a potential application to enhance CO2 capture capacity. Sorbents modified with fly ash presented great reactivity and achieved enhancement in CO2 capture capacity. After 15 cycles, the modified sorbents achieved a CO2 capture capacity of 0.27 g CO2/g sorbent, 5 times as high as that of the original sorbent (calcium carbonate) under severe calcination conditions. The modified sorbent maintained a capacity of 0.180 g CO2/g sorbent over 80 cycles. The increased surface area and pore volume enabled enhanced CO2 capture capacity of the modified sorbents. The carbonation kinetics of the modified sorbents was highly increased compared with the original sorbents. The formation of Ca3Al2O6 and CaAl2O4 in the modified sorbents enhanced the sorbents' sintering resistant and slowed the decay in CO2 capture capacity during the multiple cycles. A promising route to enhance CO2 capture performance with waste reutilization is highlighted.