| Summary: | The net oxidising atmosphere of lean burn engines requires a special after-treatment catalyst for NO<sub>x</sub> removal from the exhaust gas. Lean NO<sub>x</sub> traps (LNT) are such kind of catalysts. To increase the efficiency of LNTs at low temperatures platinised perovskite-based infiltration composites La<sub>0.5</sub>Sr<sub>0.5</sub>Fe<sub>1-x</sub>M<sub>x</sub>O<sub>3-δ</sub>/Al<sub>2</sub>O<sub>3</sub> with M = Nb, Ti, Zr have been developed. In general, platinum based LNT catalysts show an undesired, hazardous formation of N<sub>2</sub>O in the lean operation mode due to a competing C<sub>3</sub>H<sub>6</sub>-selective catalytic reduction (SCR) at the platinum sites. To reduce N<sub>2</sub>O emissions an additional Rh-coating, obtained by incipient wetness impregnation, besides the Pt coating and a two-layered oxidation catalyst (2 wt.% Pd/20 wt.% CeO<sub>2</sub>/alumina)-LNT constitution, has been investigated. Though the combined Rh-Pt coating shows a slightly increased NO<sub>x</sub> storage capacity (NSC) at temperatures above 300 °C, it does not decrease N<sub>2</sub>O formation. The layered oxidation catalyst-LNT system shows a decrease in N<sub>2</sub>O formation of up to 60% at 200 °C, increasing the maximum NSC up to 176 µmol/g. Furthermore, the NSC temperature range is broadened compared to that of the pure LNT catalyst, now covering a range of 250–300 °C.
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