To improve the NOx storage capacity (NSC) of lean NOx, trap (LNT) catalysts of the Pt/BaO/Al2O3 type, the catalyst was doped with redox active transition metals of Mn, Co, or Cu, respectively. Due to differences in the chemical states of the doped metals, the catalysts exhibited different catalytic behaviors. Co and Mn doped catalysts showed improved NO to NO2 oxidation ability, and therefore enhanced NOx storage capacities, which led to the increased cycle averaged NOx, conversions as compared to a Pt/Ba/Al2O3 reference. However, being limited by NO reduction in rich phase, the NOx conversions were still poor at low temperatures (<250 degrees C). By employing an H-2-plasma in rich phase to assist NO reduction, NOx, conversions were greatly enhanced especially for low temperatures (<= 250 degrees C). The best properties were achieved over Pt/Co/Ba/Al2O3 catalyst which exhibited NOx conversions higher than 80% in the whole temperature range (150-350 degrees C) and best SO2 resistance abilities. (C) 2016 Elsevier B.V. All rights reserved.