Novel low-temperature lean NOx storage materials based on La0.5Sr0.5Fe1-xMxO3-δ/Al2O3 infiltration composites (M = Ti, Zr, Nb)

Abstract Low-temperature NOx storage materials for lean NOx traps based on nanocomposites containing perovskite-type oxides of La0.5Sr0.5Fe1-xMxO3-δ (M = Ti, Nb or Zr; x = 0.25 or 0.5) are prepared in a highly porous alumina with different loadings of 15-25 wt. %. The resulting storage materials are characterised by X-ray diffraction, BET and transmission electron microscopy with coupled ASTAR system for crystallite phase mapping. For all nanocomposites high surface areas around 100 m²/g are found. With perovskite loadings of 20 wt. % the platinised composites reveal NOx storage capacities between 120 to 164 µmol/g below 300 °C with a performance ranking of Zr > Ti > Nb. After hydrothermal ageing at 750 °C only for the Nb and Zr containing composites a decrease of the NSC up to 20 % can be observed. The NSC of the LSFT system can be improved by decreasing the perovskite loading to 15 wt. %.