Modifications of CeO2–ZrO2 solid solutions by nickel and sulfate as catalysts for NO reduction with ammonia in excess O2

Nickel and sulfate were impregnated on CeO2–ZrO2 to improve the activity and selectivity of catalyst for NO abatement with ammonia. The performance of catalyst is related to the types of surface acid sites. Lewis acid sites, of which the strength is increased by modification of nickel, are considered as the essential active sites for low-temperature NH3–SCR reaction. The introduction of Brønsted acid sites by sulfate modification weakens the strong oxidation of ammonia but enhances the ammonia adsorption capacity of catalyst. Therefore, the high-temperature activity of catalysts is also improved.