Keywords: carbonation-calcination cycle, CO2 separation, compaction, flue gas cleaning, high reactivity calcium oxide, precipitated calcium carbonate, pressure pelletisation of limestone, CO2 sequestration
Reactive separation of CO2 using pressure pelletised limestone
Calcium oxide powder derived by the calcination of mesoporous calcium carbonate provides a higher conversion towards carbonation compared to calcium oxide derived from naturally occurring limestone and hydrated lime. Compaction of this high reactivity sorbent was investigated for its use in CO2 separation from flue gas. It was observed that compaction preserved the porosity of the powder. The pellets were able to attain 50–80% conversion towards carbonation over three cycles. The rate and extent of carbonation reaction reduces with increasing pellet thickness. The effect of compaction load and CO2 concentration did not show any appreciable difference in the rate of carbonation. Whereas the mesoporous calcium carbonate pellet showed appreciable drop in carbonation conversion, the pellets made from other precursors, such as natural limestone and hydrated lime, maintained a higher degree of reactivity over three cycles.