LaCoO3 perovskite in Pt/LaCoO3/K/Al2O3 for the improvement of NOx storage and reduction performances

Abstract

A series of x wt% Pt/LaCoO₃/K/Al₂O₃ (x = 0, 0.3 and 1.0) and 1.0 wt% Pt/K/Al₂O₃ catalysts were synthesized. The effects of the addition of LaCoO₃ perovskite in x wt% Pt/LaCoO₃/K/Al₂O₃ on NO_x storage and reduction (NSR) performances were studied. 1.0 wt% Pt/LaCoO₃/K/Al₂O₃ exhibits higher NO_x storage capacity and reduction efficiency in NSR than 1.0 wt% Pt/K/Al₂O₃. Interestingly, when the Pt content is lowered from 1.0 to 0.3 wt%, 0.3 wt% Pt/LaCoO₃/K/Al₂O₃ still shows a higher NO_x storage capacity than 1.0 wt% Pt/K/Al₂O₃ and comparable reduction properties. Moreover, 0.3 wt% Pt/LaCoO₃/K/Al₂O₃ possesses higher resistance to SO₂ poisoning and better regenerability than 1.0 wt% Pt/K/Al₂O₃. In situ DRIFTS analysis shows that NO_x storage in 0.3 wt% Pt/LaCoO₃/K/Al₂O₃ is mainly via the nitrate route with small amount of nitrites to nitrates conversion below 200 °C, while NO_x storage at higher temperature mainly proceeds via the nitrate route.