The effect of self-reactivation on the CO

2

capture capacity of the spent calcium based sorbent was investigated in a dual-fixed bed reactor. The sampled sorbents from the dual-fixed bed reactor were sent for XRD

SEM and N

2

adsorption analysis to explain the self-reactivation mechanism. The results show that the CaO in the spent sorbent discharged from the calciner absorbs the vapor in the air to form Ca(OH)

2

and further Ca(OH)

2

·2H

2

O under environmental conditions

during which process the CO

2

capture capacity of the spent sorbent can be self-reactivated. The microstructure of the spent sorbent is improved by the self-reactivation process

resulting in more porous microstructure

higher BET surface area and pore volume. Compared with the calcined spent sorbent that has experienced 20 cycles

the pore volume and BET surface area are increased by 6.69 times and 56.3% after self-reactivation when

φ

=170%. The improved microstructure makes it easier for the CO

2

diffusion and carbonation reaction in the sorbent. Therefore

the CO

2

capture capacity of the spent sorbent

is enhanced by self-reactivation process. A self-reactivation process coupled with calcium looping process was proposed to reuse the discharged spent calcium based sorbent from the calciner. Higher average carbonation conversion and CO

2

capture efficiency can be achieved when self-reactivated spent sorbent is used as supplementary sorbent in the calciner rather than fresh CaCO

3

under the same conditions.