Rational design, synthesis and evaluation of ZnO nanorod array supported Pt:La0.8Sr0.2MnO3 lean NOx traps

Abstract In this study, a new type of lean NO x traps (LNT) based on Pt:La 0.8 Sr 0.2 MnO 3 (LSMO) nanoparticles decorated on ZnO nanorod array integrated monoliths have been successfully designed and demonstrated. Compared to the commercial catalyst, the nanorod array based catalyst demonstrates competitive NO oxidation activity, and exceptional hydrothermal stability and recoverability after sulfur poisoning. With uniform distribution of perovskite and Pt nanoparticles, the ZnO nanorod array retains its structure after long-time exposure to the reducing gaseous atmosphere. The H 2 treatment induces the surface Mn 4+ reduction to Mn 3+ and subsequently to Mn 2+ , affecting oxygen mobility, and decreasing the amount of surface lattice oxygen on the LSMO perovskite, thus leading to the catalyst performance decay according to a Mars-Van Krevelen reaction mechanism. Such surface state change was found to be reversible, with the catalytic performance fully recovered after O 2 re-treatment, making it suitable for NO x storage and reduction (NSR). The complete lean NO x traps are formulated with rationally-designed sequential BaCO 3 and Pt loading, improving NOx storage capacity. The ZnO nanorod array supported LNT shows good water compatibility under simulated exhaust. The nanorod array catalysts may be potentially suitable for vehicular NO x emission control.