EPR study of electron trapping on partially hydroxylated alkali-earth oxides occurring during SO2 disproportionation

► SO2 interaction on oxide surface is affected by hydroxyl groups. ► EPR is the most suitable spectroscopic technique to evaluate radical species. ► Adsorption of SO2 on oxide surfaces generates radicals. ► Different basicity of MgO, CaO and SrO plays a crucial role in reactivity.