Effect of sulfation on CO2 capture of CaO-based sorbents during calcium looping cycle

Calcium looping cycle is considered as one of the most promising post combustion CO capture technologies that can curb CO emissions from power plants fired with fossil fuel. However the presence of SO and steam in the flue gas leads to the sulfation of CaO-based sorbents, and thus reduces the sorbents' capacity for CO capture. In this study, the effect of sorbent sulfation during both carbonation and calcination stage on the cyclic CO capture performance was investigated. The results showed that the reaction time, SO concentrations and steam greatly influenced the capacity of CaO-based sorbent. The sulfation degree of the sorbent decreased with the reduction of carbonation and calcination time per cycle. High SO concentration present with steam led to a rapid loss in capacity of the sorbent within a few cycles. Furthermore, the synthetic sorbent derived from a sol-gel process had much higher cyclic CO capture capacities than natural limestone sorbent whether in conditions without SO or with SO and steam. Microscopic images showed that after multiple cycles in the presence of SO and steam, the porous structure of the synthetic sorbent could be retained while limestone experienced serious pore blockage and agglomeration of grains