Effects of Ti-doping on the NOx storage and the sulfur resistance of the BaFe1 − xTixO3 − y perovskite-type catalysts for lean-burn exhausts

•The Ti-doping in BaFeO3 − x enlarges the surface area, as well as the NSC.•The Ti-doping in BaFeO3 − x reduces the amount of carbonate.•The Ti-doping in BaFeO3 − x improves the sulfur resistance.•Sulfates are more readily deposited on undissolved titanium than on perovskite.•The Ti-doping degree in perovskite significantly affects the catalytic performances.

Doping with Ti in the BaFeO3 − x perovskite resulted in the significantly improved NOx adsorbability and the sulfur resistance, as compared with the BaFeO3 − x. The Ti loading and residual carbonate could enhance the NOx storage capacity of these catalysts. However, during the sulfation, the sulfates were readily formed over the undissolved titanium oxides and the carbonates on perovskite. The complete Ti-doping in perovskite would reduce the amount of the residual carbonate, as well as the undissolved titanium, consequently leading to the relatively smaller NOx storage capacity (NSC) but the further improved sulfur resistance. Among these Ti incorporated perovskites, the BaFe0.8Ti0.2O3 − y perovskite prepared by the impregnation method had the most complete Ti-doping degree and the highest sulfur resistance: only 5.1% of the NSC dropped (from 1000 to 949 μmol g −1) after the sulfation pretreatment at 400 °C. It is a possible NOx trapping material with the advantages of the high NOx storage capacity and sulfur tolerance for lean-burn exhausts.