PGM-FREE WASH COAT FOR DIESEL PARTICULATE FILTER WITH CATALYST

摘要

PROBLEM TO BE SOLVED: To provide a PGM (platinum group metal)-free wash coat which can realize a combination of cost effectiveness with efficiency in a diesel particulate filter (DPF) with a catalyst.

SOLUTION: In this PGM-free wash coat, a catalyst composition containing silver- and/or cobalt-stabilized ceria promotes the oxidation of soot during regeneration of DPF. The catalyst composition is useful as a wash coat composition for removing and/or minimizing exhausted matter, particularly for DPF as a part of an automobile post-treatment system particularly for a direct fuel ejection engine vehicle. The silver-stabilized ceria component and the cobalt-stabilized ceria component oxidize soot at 250 to 300°C in the presence of NO2and oxygen. An Ag-La-Mn perovskite component was very active at a temperature of above 300°C. The regeneration capability was substantially equal to or better than a Pt component supported at a Pt level of 28.32 g Pt/m3. The equilibrium point is provided at 250 to 275°C. The soot was fully oxidized at 325°C. The exhaustion levels of CO, NOx and HC during regeneration were also substantially the same as those in the case of the Pt component.

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