Layered catalyst composite

A method of forming a layered catalyst composite comprising the steps of:

• forming a first layer comprising:
• a first support;
• a first palladium component;
• optionally at least one first platinum group metal component other than palladium;
• an oxygen storage component in intimate contact with the first platinum group metal component;
• optionally a first zirconium component;
• optionally at least one first alkaline earth metal components;
• and
• optionally at least one first rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components, wherein the first layer requires at least one first alkaline earth metal component and at least one first rare earth metal component;
• coating the first layer with a second layer comprising:
• a second support;
• a second palladium component free from intimate contact with the oxygen storage component;
• optionally at least one second platinum group metal component other than palladium;
• optionally a second zirconium component;
• optionally at least one second alkaline earth metal components;
• and
• optionally at least one second rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components, wherein the second layer requires at least one of the second alkaline earth metal component and at least one second rare earth metal component.

A layered catalyst composite comprising a first layer and a second layer:

• the first layer comprising:
• a first support;
• at least one palladium component, wherein the first palladium component is substantially the only platinum group metal component in the first layer;
• a first oxygen storage component in intimate contact with the first palladium component;
• optionally a first zirconium component;
• optionally at least one first alkaline earth metal component;
• and
• optionally at least one first rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components, wherein the first layer requires at least one first alkaline earth metal component and at least one first rare earth metal component;
• and
• the second layer comprising:
• a second support;
• at least one second palladium component free from intimate contact with the oxygen storage component, wherein the second palladium component is substantially the only platinum group metal component in the second layer;
• optionally a second zirconium component;
• optionally at least one second alkaline earth metal component;
• and
• optionally at least one second rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components, wherein the second layer requires at least one of the second alkaline earth metal component and at least one second rare earth metal component.

A method comprising the steps of:

• combining at least one water soluble or dispersible first palladium component and finely divided, high surface area refractory oxide with an aqueous liquid to form a first solution or dispersion which is sufficiently dry to absorb essentially all of the liquid;
• mixing the first solution or dispersion with other first layer components comprising a soluble first oxygen storage component to intimately contact the first palladium component;
• optionally, mixing the first solution or dispersion with a first water soluble or dispersible platinum group metal component other than a palladium component, a first zirconium component, at least one first alkaline earth metal component, and at least one first rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components;
• forming a first layer of the first solution or dispersion on a substrate;
• converting the first palladium components in the resulting first layer to a water insoluble form;
• combining at least one water soluble or dispersible second palladium component and finely divided, high surface area refractory oxide with an aqueous liquid to form a second solution or dispersion which is sufficiently dry to absorb essentially all of the liquid;
• optionally, mixing the second solution or dispersion with a second water soluble or dispersible platinum group metal component other than a palladium component, a second zirconium component, at least one second alkaline earth metal component, and at least one second rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components;
• forming a second layer of the second solution or dispersion on the first layer;
• and
• converting the second palladium components in the resulting second layer to a water insoluble form, the second palladium components being free from intimate contact with the oxygen storage component.

A catalytic article comprising a upstream section and a downstream section:

• the downstream section comprising:
• a downstream substrate;
• a first layer on the downstream substrate, the layer comprising:
• at least one first palladium component;
• a first oxygen storage component in intimate contact with the first palladium component;
• optionally, a first zirconium component;
• optionally, at least one first alkaline earth metal component;
• and
• optionally, at least one first rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components;
• and
• the upstream section comprising:
• an upstream substrate;
• a second layer on the upstream substrate, the upstream layer comprising:
• at least one second palladium component free from intimate contact with the oxygen storage component;
• optionally, a second zirconium component;
• optionally, at least one second alkaline earth metal component;
• and
• optionally, at least one second rare earth metal component selected from the group consisting of lanthanum metal components and neodymium metal components.