NO Adsorption and Reduction over LaMnO Based Lean NO Trap Catalysts.

We have reported a LaMnO-based, Pt free lean NO trap (LNT) catalyst shows promising NO reduction activities, but the mechanism of NO reduction or the role of the perovskite over this catalyst has not been addressed. This paper presented our investigation on the mechanistic aspects of NO adsorption and reduction over several LaMnO-based LNT catalysts. NO can be effectively oxidized to NO on LaMnO at 350 °C, while little NO (NO + NO) can be stored verified by the following temperature programmed desorption experiment; under the same conditions, a significant amount of NO (41 μmol NO/g washcoat) were stored over BaO/AlO/LaMnO indicating NO are adsorbed mainly on the BaO/AlO. The temperature programmed surface reaction with CO demonstrated that although it can store NO during the lean period, failed to reduce NO by CO over the BaO/AlO/LaMnO catalyst. After adding Pd into BaO/AlO/LaMnO, NO can not only be stored during the lean conditions but also reduced. It could be concluded that the Pd catalyst, not perovskite, is responsible for NO reduction during the rich conditions. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]