The present invention provides for novel poisoning-resistant catalysts
used for automobile exhaust gas treatment systems. To alleviate the
detrimental affects of engine oil and/or fuel additive poisoning the
present invention provides for an overcoat layer comprising a porous
refractory oxide and one or more base metal oxides, which is coated over
one or more precious metal containing washcoat layers. The overcoat of
the present invention prevents phosphorous as well as other poisoning
deposits, from fouling and/or negatively interacting with the underlying
precious metal containing washcoats. In an alternative embodiment, the
present invention provides for the coating of the upstream end of a
catalytic member by the overcoat layer, thereby creating an upstream
poison capture zone.