Currently, SO2-induced catalyst deactivation from the sulfation of active sites turns to be an intractable issue for selective catalytic reduction (SCR) of NOx with NH3 at low temperatures. Herein, SO2-tolerant NOx reduction has been originally demonstrated via tailoring the electron transfer between surface iron sulfate and subsurface ceria. Engineered from the atomic layer deposition followed by the pre-sulfation method, the structure of surface iron sulfate and subsurface ceria was successfully constructed on CeO2/TiO2 catalysts, which delivered improved SO2 resistance for NOx reduction at 250 °C. It was demonstrated that the surface iron sulfate inhibited the sulfation of subsurface Ce species, while the electron transfer from the surface Fe species to the subsurface Ce species was well retained. Such an innovative structure of surface iron sulfate and subsurface ceria notably improved the reactivity of NHx species, thus endowing the catalysts with a high NOx reaction efficiency in the presence of SO2. This work unraveled the specific structure effect of surface iron sulfate and subsurface ceria on SO2-toleant NOx reduction and supplied a new point to design SO2-tolerant catalysts by modulating the unique electron transfer between surface sulfate species and subsurface oxides.
Keywords: NOx reduction; SO2 tolerance; air pollution control; atomic layer deposition; environmental catalysis; selective catalytic reduction.