Low-temperature H₂-plasma-assisted NO_x storage and reduction over a combined Pt/Ba/Al and LaMnFe catalyst

A model catalyst of the Pt/Ba/Al₂O₃ (PBA) type exhibited poor activity in NO_x storage-reduction (NSR) at low temperatures (≤300°C) even under a plasma-enhanced process. In order to achieve optimal NO_x removal efficiency during plasma-assisted NO_x storage-reduction in the presence of H₂O and CO₂, a PBA+LMF (LaMn_0.9Fe_0.1O₃) catalyst was prepared by mechanical mixing. Compared to the PBA and LMF references, the combined PBA+LMF catalyst showed an obvious synergistic effect with respect to NO_x storage capacity. With the assistance of H₂ plasma in rich phase, higher NO_x conversions could be obtained over the PBA+LMF sample over a wide temperature range (200-350°C). The origin of the synergy was clarified on the basis of structure-activity correlations. The combination of non-thermal plasma and heterogeneous catalysis was proven to be very effective in improving the low temperature activity of lean NO_x trap (LNT) catalysts.