Influence of the Calcination and Carbonation Conditions on the CO2 Uptake of Synthetic Ca-Based CO2 Sorbents

In this work we report the development of a Ca-based, Al2O3-stabilized sorbent using a sol-gel technique. The CO2 uptake of the synthetic materials as a function of carbonation and calcination temperature and CO2 partial pressure was critically assessed. In addition, performing the carbonation and calcination reactions in a gas-fluidized bed allowed the attrition characteristics of the new material to be investigated. After 30 cycles of calcination and carbonation conducted in a fluidized bed, the CO2 uptake of the best sorbent was 0.31 g CO2/g sorbent, which is 60% higher than that measured for Rheinkalk limestone. A detailed characterization of the morphology of the sol-gel derived material confirmed that the nanostructure of the synthetic material is responsible for its high, cyclic CO, uptake. The sol gel method ensured that Ca2+ and Al3+ were homogenously mixed (mostly in the form of the mixed oxide mayenite). The formation of a finely and homogeneously dispersed, high Tammann temperature support stabilized the nanostructured morphology over multiple reaction cycles, whereas limestone lost its initial nanostructured morphology rapidly due to its intrinsic lack of a support component.