METHOD AND APPARATUS FOR TREATING REFORMED GAS AND FUEL CELL ELECTRIC POWER GENERATION SYSTEM

To provide a method for treating a reformate in which carbon monoxide in the reformate can be removed in a stable and reliable manner for a long period of time. A method for treating a reformate according comprises a temperature elevating step of heating a selective oxidation catalyst 19 to elevate temperature thereof, the selective oxidation catalyst 19 being for selectively oxidizing carbon monoxide in the reformate 44 with air 34 for selective oxidation; a selective oxidation catalyst 19 activating step of, after the temperature of the selective oxidation catalyst 19 has been elevated in the above temperature elevating step, supplying the reformate 44, formed in a reforming step of forming the reformate 44 from a hydrocarbon fuel 42 by steam reforming reaction, to the selective oxidation catalyst 19 for a predetermined time, without supplying the air 34 for selective oxidation, to activate the selective oxidation catalyst 19; and a carbon monoxide removing step of removing carbon monoxide in the reformate 44, formed in the reforming step, by the selective oxidation thereof with the air 34 for selective oxidation using the activated selective oxidation catalyst 19.