Development of monolithic catalysts with low noble metal content for diesel vehicle emission control

Abstract

Monolith washcoated catalysts with potential for diesel emission control have been developed. Two types of catalysts have been prepared for further study: (1) MnO x supported on granulated γ-Al2O3, (2) MnO x supported on cordierite monolith washcoated with γ-Al2O3. Both catalysts have been calcined at 500 and 900 °C and subsequently modified by doping with 0.1–1.0 wt% of Pt or Pd. The influence of the concentration of both manganese oxide (0–10 wt%) and noble metals Pt and Pd in the range 0–1.0 wt% on the catalytic activity in methane oxidation has been studied. Comparison of the catalytic activity of MnO x /Al2O3 and MnO x + Pt(Pd)/Al2O3 with that of a standard 1 wt%Pt/Al2O3 catalyst shows the existence of a synergetic effect. This effect is more pronounced for the samples calcined at 900 °C. The developed monolithic catalysts MnO x + Pt(Pd)/Al2O3 demonstrate higher activity and thermal stability (up to 900 °C) compared to the commercial monolithic catalyst (TWC’s).