Sulphur tolerant diesel oxidation catalysts by noble metal alloying

A series of Mn-alloyed Pt supported catalysts were investigated for the NO oxidation reaction applied in diesel oxidation catalysts under sulphur-containing conditions. The observed NO oxidation conversion correlated to the Pt amount in the catalyst under sulphur-free conditions. In the presence of SO2 in the feed, the Pt/Al2O3 catalyst heavily deactivated resulting in the lowest performance compared to Mn-alloyed Pt catalysts. Already small amounts of Mn improved the SO2-resistance significantly. Whilst pure Pt/Al2O3 catalyst deactivates fully within the first 30 min under NO oxidation conditions including 300 ppm SO2, an alloy with a Mn to Pt ratio of 1:1 performed with a remarkable high catalytic stability for the NO oxidation over at least 70 h under continuous testing conditions