TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: The inventive method may also include preparing a hydrogen and carbon monoxide removal catalyst for accelerating conversion of hydrogen and carbon monoxide into water and carbon dioxide.The hydrogen and carbon monoxide removal catalyst is disposed downstream of the methane removal catalyst with regard to flow of the exhaust gas of a fuel cell stack.An oxygen excessive rate of exhaust gas introduced to a region where the hydrogen and carbon monoxide removal catalyst is disposed is at least 100 %.Preferred Condition: The exhaust gas introduced to the methane removal catalyst is controlled at 200-600degrees C.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The hydrogen and carbon monoxide removal catalyst comprises a second catalytic ingredient including rhodium, platinum (preferred) or palladium.The methane removal catalyst contains alumina, silica, magnesia, zirconia, titania, or ceria as a porous carrier. It also contains zeolite.Preferred Composition: The first catalytic ingredient contained in the methane removal catalyst is 1-10 wt.%. A sum of contents of alkaline metal and alkaline earth metal in the methane removal catalyst is at most 3 wt.%.The second catalytic ingredient (0.1-3 wt.%) is formed by being loaded on a porous carrier. The refractory inorganic compound is contained at 50-100 g/L.Preferred Property: The methane removal catalyst and the hydrogen and carbon monoxide removal catalyst are monolithic honeycomb catalysts.A shape of openings of the monolithic honeycomb catalyst is formed to be circular or elliptical by a refractory inorganic compound, and the first catalytic ingredient and the second catalytic ingredient are supported on surfaces formed to be circular or elliptical. EXAMPLE - Active alumina (gamma-alumina) having a specific surface area of 240 m2/g was impregnated with a palladium nitrate aqueous solution in which a concentration of palladium is 2.5 wt.% and was dried at 120 degreesC for 15 hours, and then was baked at 500 degreesC for 2 hours. Thus, palladium/alumina catalyst powder was obtained, in which the amount ratio of the loaded palladium to alumina in a state where the adsorbed water is removed from it, is approximately 7.5 wt.%.    The obtained palladium/alumina catalyst powder was boehmite were mixed in a mass ratio of 10:1 and added with 1 wt.% of nitric acidic alumina sol, and then mixed with water. This was subjected to a milling treatment for 60 minutes in a magnetic ball mill pot containing alumina balls having a diameter of 7 mm, and thus slurry containing the catalyst powder was obtained.    The slurry was coated on a cordieritic monolithic honeycomb support (phi 35 mm; 40 ml) for laboratory scale testing, which had 400 cells of air vents per square inch, was dried at 110 degreesC and baked at 400 degreesC and thus a monolithic honeycomb catalyst 1 was manufactured. The coating amount of the catalyst powder to the monolithic honeycomb support was set at 45 g/L.