The negative effects of SO2 on CO2 capture with K2CO3/Al2O3

Post-combustion CO2 capture technology with K-based sorbent is considered to be an innovative capture concept; however, the residual SO2 in the flue gas will still affect the CO2 sorption performance of the K-based sorbent. This paper investigated the CO2 sorption and sulfation characteristics of K2CO3/Al2O3. The effects of several variables such as H2O concentration, SO2 concentration, and sorption temperature were studied. Results showed that it was important to investigate the effects of SO2 on the CO2 capture capacity of this sorbent, even when the SO2 concentration is very low due to the fact that the sulfation competes with the CO2 sorption process. K2SO3, as the sulfation product, cannot be converted back to K2CO3 for reuse. In order to enhance the CO2 sorption competitiveness or to increase the reaction rate ratio (ε) of the sorbent, the fluidized bed reactor (FBR) was selected as the suitable reactor for the sorption process. Also, besides increasing CO2/SO2 volume ratio in the flue gas, properly increasing the sorption temperature and H2O concentration will increase the CO2 sorption competitiveness. Pretreating sorbent with H2O vapor and using them to capture CO2 in FBR will get further better CO2 sorption competitiveness. Based on the competition model built in this paper, the activation energy for K2CO3 and SO2 is 55.01 kJ mol−1. The results from this study supply theoretical evidence for commercial operation of post-combustion CO2 capture technology with K-based sorbent.