Temperature programmed desorption study on the mechanism of SO2 oxidation by activated carbon and activated carbon fibres Original Research Article

The mechanism of SO2 oxidation by O2 on ACs and ACFs has been studied over a wide variety of samples with different porosity and surface oxygen content. Temperature programmed desorption experiments after SO2 adsorption at room temperature and using gas mixtures with different compositions and in-situ FTIR experiments during the adsorption and the subsequent desorption, show that SO2 oxidation is inhibited by the oxygen complexes existing on the carbon surface. The experiments also suggest that the SO2 oxidation occurs through the interaction of adsorbed SO2 with O2 in the gas phase by a mechanism that follows an Eley–Rideal kinetic model. Desorption of SO3 produces carbon gasification and generates selectively CO-type oxygen complexes at the surface; CO2 gas is only formed through secondary reactions between SO3 and CO.