Patent ID: 6875409

Claim:
A bi-functional catalyst useful for oxidation and removal of nitrogen oxides (NOx) contained in fuel combustion gases, the catalyst comprising: an adsorption function metal oxide component comprising at least one metal oxide selected from the group consisting of oxides of barium, cesium, lanthanum, strontium, and zirconium, wherein said adsorption metal oxide component includes lanthanum, said adsorption function metal oxide component providing adsorption function and adsorption sites for nitrogen oxides in fuel combustion gases; and an oxidation function metal oxide component comprising at least one metal oxide selected from the group consisting of chromium, cobalt, copper, iron, manganese, and platinum, wherein said oxidation metal oxide component includes at least one of copper or manganese promoted with platinum, said oxidation function metal oxide component providing an oxidation function and oxidation sites for nitrogen oxides in fuel combustion gases, said adsorption metal oxide component and said oxidation metal oxide component being combined together in close intimate contact so that said adsorption metal oxide component and said oxidation metal oxide component are chemically bonded closely together so as to form a metal oxide complex having a crystalline structure, said adsorption sites and oxidation sites for nitrogen oxides within the bi-functional catalyst being adjacent to each other and arranged so as to promote adsorption and oxidation of nitrogen oxides when exposed to fuel combustion gases containing nitrogen oxides, the molar ratio of metal within the adsorption function metal oxide component to metal within the oxidation function metal oxide component being in a ratio range of 0.1:1 to 5:1 in the bi-functional catalyst.