Study of SO2 effect on selective catalytic reduction of NOx with NH3 over Fe/CNTs: The change of reaction route

•The adsorption and activation of NOx specie benefit for SCR performance on Fe/CNTs.•The effect of SO2 on Fe/CNTs for SCR reaction is irrecoverable.•Ferric sulfate is the main sulfate specie and inhibits the adsorption of NOx species.•Ferric sulfate promotes the activation of NH3 to directly react with gas NO over 275°C.•Addition of SO2 causes the transform of dominating reaction pathway at different temperatures.