A potential substitution of noble metal Pt by perovskite LaCoO3 in ZrTiO4 supported lean-burn NOx trap catalysts

The support ZrTiO4 and the lean-burn NOx trap (LNT) catalyst K/LaCoO3/ZrTiO4 were prepared by co-precipitation and successive impregnation, respectively. This catalyst exhibits much better NOx storage performance than the conventional Pt-containing catalyst K/Pt/ZrTiO4. Compared with Pt, the perovskite LaCoO3 possesses higher capability for NO to NO2 oxidation, giving a higher NOx storage capacity. NOx is mainly stored as nitrate at 350 °C over K/LaCoO3/ZrTiO4. Mild sulfation shows little effect on the structure and performance of this catalyst. Total substitution of Pt by perovskite LaCoO3 to lower the cost of LNT catalysts is feasible.

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► K/LaCoO3/ZrTiO4 is more capable for the oxidation of NO to NO2 than K/Pt/ZrTiO4.
► K/LaCoO3/ZrTiO4 shows much larger NOx storage capacity (NSC) than K/Pt/ZrTiO4.
► Mild sulfation shows small effect on the structure and property of K/LaCoO3/ZrTiO4.
► It is potential for K/LaCoO3/ZrTiO4 to replace the Pt-based K/Pt/ZrTiO4 NSR catalyst.