Method of operating ruthenium catalyst reactor

A method of operating a ruthenium catalyst reactor comprising steps of:

• filling a reaction container of the catalytic reactor with a ruthenium catalyst formed of an inorganic oxide carrier and ruthenium supported thereon, with a filling height level of the catalyst filled in the reaction container being adjusted above a height level at which a material fluid is fed from an introduction part to inside the reaction container;
• supplying a mixed gas mainly containing hydrocarbon, oxygen-containing gas and steam as the material fluid to the reaction container;
• allowing a partial oxidation reaction to proceed in the presence of the ruthenium catalyst;
• and producing synthetic gas containing hydrogen and carbon monoxide,
• the method further comprising steps of:
• monitoring a molar ratio (C/O2) of carbon contained in the hydrocarbon gas and oxygen contained in the oxygen-containing gas which are supplied to the reaction container, and
• stopping the supply of the oxygen-containing gas to the reaction container before the molar ratio (C/O2) is reduced below a critical molar ratio in terms of molar ratio (C/O2) at which scattering of ruthenium in the ruthenium catalyst is generated,
• a different molar ratio (C/O2) being adopted as the critical molar ratio in accordance with a type of the hydrocarbon gas, with the critical molar ratio (C/O2) being set to 1 or less.