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

摘要

Monolith washcoatcd 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 7-Al_2O_3,(2) MnO_x supported on cordierite monolith washcoaled with gamma-Al_2O_3.Both catalysts have been calcined at 500 and 900degC 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/Al_2O_3 and MnO_x+ Pt(Pd)/Al_2O_3 with that of a standard 1 wt%Pt/Al_2O_3 catalyst shows the existence of a synergetic effect.This effect is more pronounced for the samples calcined at 900degC.The developed monolithic catalysts MnO_x+Pt(Pd)/Al_2O_3 demonstrate higher activity and thermal stability (up to 900degC) compared to the commercial monolithic catalyst (TWC's).