Simultaneous Removal of SOx and NOx Using Slaked Lime at Low Temperature

The activity of slaked lime for the simultaneous absorption of SO x and NO x from flue gases of coal combustion has been studied using a fixed bed reactor at 90 °C. The slaked lime samples were prepared by swelling the natural lime using water vapor. It was found that NO and SO 2 enhanced the adsorption of each other. The results of IR showed that SO 2 was absorbed as SO 4 2- salt by Ca(OH) 2 in the presence of NO; however, it was mainly absorbed as SO 3 2- salt in the absence of NO. It is interesting that NO could not be absorbed by the slaked lime without SO 2 at the low temperature, while it was converted to NO 3 - salts with the presence of SO 2 . This implied that some species formed from SO 2 played a role as catalysts for the adsorption of NO by the slaked lime, which indicated a possible way to remove SO x and NO x simultaneously from the flue gases of coal combustion.