TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: 40% (mole conversion) or more of the noble metal components exists within 0.15 mm from the support surface and 90% (mole conversion) or more of the noble metal components exists within 0.3 microns from the support surface. The noble metal component is ruthenium, platinum, rhodium, palladium and/or an iridium component, preferably a ruthenium component. The inorganic oxide is alumina. The noble metal is contained as anion complex or halide, preferably a chloride, supported by pore filling impregnation. The catalyst further contains metal component(s) chosen from manganese, lanthanum, and/or yttrium component, cobalt component, and alkali metal component, alkaline earth metal component and/or cerium component. An aqueous solution or solution of noble metal component, manganese component, lanthanum component, yttrium component, and/or cobalt component is dip coated on the alumina support having a water absorption amount of 2 times or more to form the catalyst. The catalyst is spherical, cylindrical, honeycomb form, plate-shaped, ring-shaped, grain-shaped, foam-shaped, fiber type or cloth-shaped catalyst. EXAMPLE - 8 mass% of aluminum sulfate containing an aqueous solution was added to a sodium aluminate aqueous solution (5 kg) until the pH became 9.5. The obtained deposit (alumina gel) was water washed and dried until the moisture content became 15%. The alumina gel was extrusion molded and baked at 500degreesC for 5 hours, and gamma-alumina was obtained. Manganese nitrate hexahydrate (11.00 g) was dissolved in water and impregnated into gamma-alumina, dried at 120degreesC, and baked at 800degreesC for 3 hours and a gamma-alumina support containing 10 mass% of manganese oxide was prepared. Ruthenium chloride (2.55 g) was dissolved in water and impregnated into the gamma-alumina support (33) and left at room temperature for 1 hour. The support was immersed in a 5 N sodium hydroxide aqueous solution and the impregnated compound was decomposed by slow stirring for 1 hour. Catalyst containing 3 mass parts of ruthenium supported w.r.t 100 mass parts of gamma-alumina support was obtained by drying at 80degreesC for 3 hours. The catalyst was filled in a quartz reaction tube and water vapor and desulfurized kerosene oil were introduced into the tube and hydrogen reduction processing was carried out at 600degreesC with hydrogen air flow. Water vapor modification reaction was carried out at normal pressure and 600degreesC. The gas obtained after 1 hour was sampled. The C1 conversion ratio was 64.4%. 33% of ruthenium existed with in 0.15 mm from the catalyst surface and 98% of ruthenium existed between 0.3 mm from the catalyst surface.