Pt-free, LaMnO3 based lean NOx trap catalysts

Conventional lean NOx trap (LNT) catalysts require high loadings of Pt in order to oxidize NO to NO2, a critical step in LNT applications. This paper presents a concept study of using LaMnO3 perovskite as a substitute to Pt in LNT catalyst. The structure, morphology and redox property of LaMnO3 perovskite were probed by TPR, XRD and its performance on NO oxidation to NO2 was also evaluated. A LaMnO3 based, PGM free LNT showed good NO oxidation activity and NOx storage capability under lean conditions, but it did not have sufficient NOx reduction activities during LNT regeneration. With the addition of Pd/Rh to provide NOx reduction activities, a LaMnO3-based, Pt-free LNT showed high NOx storage/reduction activities under lean and rich cycling conditions. (C) 2011 Elsevier B.V. All rights reserved.