The capacity of particles of CaO, produced by calcining limestone, to reactively absorb CO2, degrades with the number of cycles of carbonation and calcination. A novel method of reactivating the stone in humid, ambient air is described. Typically, a calcined limestone has a carrying capacity for CO2 which falls fromy similar to 79% (on the basis of moles of CO2 permole of CaO) to only about 20-30% after 30 cycles of regeneration and reuse. This new technique enables the carrying capacity to be restored to similar to 55%, thereby improving the economics of sequestrating CO2 using a calcium-based sorbent.
