The catalytic conversion of SO2 to SO3 by fly ash and the capture of SO2 and SO3 by CaO and MgO

Abstract The formation of SO 3 from SO 2 and 0 2 is catalyzed by iron oxide in the fly ash from a coal-fired boiler. The amount of SO 3 produced is dependent on the iron oxide content of the fly ash and on the oxygen concentration of the gas stream. Carbon in the fly ash significantly reduces the formation of SO 3 . The removal of SO 2 from a gas stream by CaO and MgO is enhanced by the catalytic conversion of the SO 2 , to SO 3 , as SO 3 is more easily captured than SO 2 by these oxides. The formation of SO 3 and its removal from the gas stream depend on the reaction temperature, the oxygen concentration of the gas stream, and the flow rate of the gas.