Patent ID: 8093178

Claim:
A catalyst used in a method for reducing the carbon monoxide concentration of a raw material gas containing hydrogen and carbon monoxide by bringing the raw material gas into contact with an oxygen-containing gas in the presence of the catalyst to selectively oxidize carbon monoxide in the raw material gas, comprising a support of an inorganic oxide and ruthenium loaded thereon, the relative loading depth of ruthenium X(Ru) in the radial direction of the catalyst in a radial cross-section of the catalyst satisfying the requirement represented by the following formula (1): X(Ru)≧15 (1) wherein the relative depth of ruthenium X(Ru) indicates the ratio (%) of the loading depth of ruthenium to the radius of the catalyst particle, wherein in addition to ruthenium, the catalyst further comprises at least one metal selected from the group consisting of platinum, palladium, rhodium and iridium.