Patent ID: 8343888

Claim:
A method of forming crystalline particles of a perovskite catalyst material on cell wall surfaces of an extruded ceramic monolithic catalyst support substrate, wherein the perovskite crystalline particles comprise (i) cations of one or more elements, A-group cations, having a first range of ionic radii; (ii) cations of one or more elements, B-group cations, having a range of radii smaller than the first ionic radii range; and oxygen anions, and to be composed in elemental proportions as ABO 3 , the method comprising: forming an aqueous solution comprising A-group cations with a substantially equivalent number of B-group cations; adding a polybasic, carboxyl group-containing organic acid to the aqueous solution in an amount to provide an excess of carboxyl groups with respect to the total of A-group cations and B-group cations, and reacting the carboxyl groups and cations to form an aqueous ionic complex of cations and acid; adjusting the water content of the aqueous ionic complex, if necessary, for coating of the aqueous ionic complex on cell wall surfaces of an extruded ceramic monolithic catalyst support; applying the aqueous ionic complex to cell wall surfaces of the extruded ceramic monolithic catalyst support to form an adherent coating layer of the ionic complex; evaporating superficial water from the coating layer; and calcining the coating layer in air at elevated temperature to form particles of crystalline perovskite on the cell wall surfaces of the extruded ceramic monolithic catalyst support for catalytic treatment of a as flowing through the cells of the extruded ceramic monolithic catalyst support.