The enhanced resistance to Na+-poisoning of MnCoCrOx SCR catalyst by acidity regulation: The mechanism of sulfuric acid pretreatment

•The resistance of MnCoCrOx catalyst to Na+ species could be greatly enhanced via sulfuric acid pretreatment.•0.1 M sulfuric acid-treated 1 wt.% Na+ poisoned MnCoCrOx catalyst exhibits a broad T90 window between 199 and 400 °C.•Sulfuric acid could introduce excessive Brønsted acid sites and cut the loss of Lewis acid sites at the surface of MnCoCrOx catalyst.•HSO4− species would serve as acid sites for NH3 adsorption and activation.