Palladium solid solution catayst and methods of making

Abstract

Disclosed are three-way catalysts that are able to simultaneously convert nitrogen oxides, carbon monoxide, and hydrocarbons in exhaust gas emissions into less toxic compounds. Also disclosed are three-way catalyst formulations comprising palladium (Pd)-containing oxygen storage materials. In some embodiments, the three-way catalyst formulations of the invention do not contain rhodium. Further disclosed are improved methods for making Pd-containing oxygen storage materials. The relates to methods of making and using three-way catalyst formulations of the invention.

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         13 . A method of making the oxygen storage material (OSM) comprising a metal oxide doped with at least one transition metal, wherein said transition metal and OSM are present as a solid solution, comprising:
 1) adding an amount of transition metal salt to an aqueous slurry of milled OSM; and   2) adding an amount of base to generate an IWCP-OSM slurry.   
     
     
         14 . A method of making a catalyst composition comprising an oxygen storage material (OSM) prepared as in  claim 13 , comprising:
 1) generating an IWCP-OSM slurry by: a) adding an amount of transition metal salt to an aqueous slurry of milled OSM; and b) adding an amount of base to generate an IWCP-OSM slurry;   2) generating a support oxide mixture by: a) milling an amount of support oxide with acetic acid; b) adding an amount of BaCO 3  or CaCO 3  and stirring to generate a support oxide mixture;   3) adding said support oxide mixture of 2) to said IWCP-OSM slurry of 1) and coating the resulting composition on to a washcoat; and   4) calcining the resulting mixture of 3) to yield a catalyst composition.   
     
     
         15 . A method of increasing oxygen flow through a catalyst system by utilizing an oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal,
 wherein said OSM is present in the washcoat, overcoat, or both, and 
 wherein said transition metal and OSM are present as a solid solution. 
 
     
     
         16 . A method of increasing the oxygen storage capacity of a catalyst system by utilizing an oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal,
 wherein said OSM is present in the washcoat, overcoat, or both, and 
 wherein said transition metal and OSM are present as a solid solution. 
 
     
     
         17 . A method of improving the lifetime of a platinum group metal (PGM) catalyst present in a catalyst system by utilizing an oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal,
 wherein said OSM is present in the washcoat, overcoat, or both, and 
 wherein said transition metal and OSM are present as a solid solution. 
 
     
     
         18 . A method of improving the light-off performance of a catalyst system by utilizing an oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal,
 wherein said OSM is present in the washcoat, overcoat, or both, and 
 wherein said transition metal and OSM are present as a solid solution. 
 
     
     
         19 . A method of reducing the amount of Rh present in a catalyst system while maintaining catalyst efficiency by utilizing an oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal,
 wherein said OSM is present in the washcoat, overcoat, or both, and 
 wherein said transition metal and OSM are present as a solid solution. 
 
     
     
         20 . A method of simultaneously converting a) nitrogen oxides to nitrogen and oxygen; b) carbon monoxide to carbon dioxide; and c) hydrocarbons to carbon dioxide and water present in exhaust gas emissions, comprising contacting said gas emissions with the catalyst system comprising a substrate and a washcoat, wherein said washcoat comprises an oxygen storage material (OSM) prepared as in  claim 13 . 
     
     
         21 . A catalytic convertor system comprising a catalyst system comprising: a substrate and a washcoat, wherein said washcoat comprises an oxygen storage material (OSM), doped with at least one transition metal prepared as in  claim 13 , wherein said transition metal and said OSM are present as a solid solution. 
     
     
         22 . A close coupled catalytic converter comprising the oxygen storage material (OSM) prepared as in  claim 13  comprising a metal oxide doped with at least one transition metal, wherein said transition metal and OSM are present as a solid solution. 
     
     
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