Abstract: The invention provides a catalyst for catalytically removing three components, which are carbon monoxide, hydrocarbons and nitrogen oxides, from combustion exhaust gas generated by combusting fuel at around the stoichiometric air to fuel ratio. The catalyst includes: (A) a first catalyst component including at least rhodium, platinum, or palladium in a content of 0.01 to 0.5% by weight; and (B) a second catalyst component, which is the remainder, including a composite oxide or a mixed oxide including (a) at least zirconium oxide or titanium oxide, and (b) an oxide of at least praseodymium, yttrium, neodymium, tungsten, niobium, silicon, or aluminum, wherein the content of the oxide (a) in the composite oxide or the mixed oxide is in a range of 70 to 95% by weight. The invention further provides a two-layer catalyst that includes a surface catalyst layer containing the above-mentioned catalyst.

Abstract: The invention provides a catalyst for catalytically removing three components which are carbon monoxide, hydrocarbons and nitrogen oxides from combustion exhaust gas generated by combusting fuel in the neighborhood of the stoichiometric air to fuel ratio by bringing the combustion exhaust gas into contact therewith, the catalyst comprising: (A) a first catalyst component comprising at least one member selected from rhodium, platinum, and palladium in a content of 0.01 to 0.5% by weight; and (B) a second catalyst component, which is the remainder, comprising a composite oxide or a mixed oxide comprising (a) at least one oxide selected from zirconium oxide and titanium oxide, and (b) an oxide of at least one element selected from praseodymium, yttrium, neodymium, tungsten, niobium, silicon, and aluminum, wherein the content of the oxide (a) in the composite oxide or the mixed oxide is in a range of 70 to 95% by weight.