Patent ID: 7947859

Claim:
A method for producing a cycloolefin continuously comprising: partially hydrogenating a monocyclic aromatic hydrocarbon with hydrogen in the presence of a ruthenium catalyst, water, and a metal sulfate, wherein the concentration of chloride ions dissolved in the water in which the catalyst is present is 300 wt ppm or less at any time after starting the partial hydrogenation and up to 500 hours; regenerating the catalyst or a part thereof; and reusing the regenerated catalyst; wherein (1) the ruthenium catalyst is a catalyst comprising a carrier and/or a dispersant, and the concentration of chloride ions contained in the carrier and/or the dispersant is 200 wt ppm or less; (2) the concentration of chloride ions contained in the monocyclic aromatic hydrocarbon is 10 wt ppm or less; (3) the concentration of chloride ions contained in the hydrogen is 1 mg-Cl/Nm 3 -H 2 or less (wherein N (normal) means that the unit is based on the gas in the standard state); (4) the concentration of chloride ions contained in water provided for the partial hydrogenation is 20 wt ppm or less; (5) the concentration of chloride ions in the catalyst is 400 wt ppm or less; (6) the concentration of chloride ions in the metal sulfate is 10 wt ppm or less.