Method for producing cycloolefin and production apparatus thereof

A method for producing a cycloolefin, comprising:

• producing the cycloolefin by a partial hydrogenation reaction of a monocyclic aromatic hydrocarbon, wherein the partial hydrogenation reaction is conducted in an aqueous phase which contains a first metal salt-containing acidic aqueous solution and a ruthenium catalyst, and wherein the partial hydrogenation reaction is conducted in a reactor with a liquid-contact portion formed of a nickel-containing material;
• separating an oil phase comprising the cycloolefin and an aqueous phase containing the ruthenium catalyst and an eluted nickel;
• and
• processing the aqueous phase containing the ruthenium catalyst and the eluted nickel through the steps including a first step of desorbing nickel from the ruthenium catalyst by bringing at least a part of the ruthenium catalyst and the eluted nickel contained in the aqueous phase into contact with oxygen and dissolving the nickel into the aqueous phase,
• a second step of separating the aqueous phase containing the ruthenium catalyst and the eluted nickel that has been processed in the first step into a first phase, and a second phase, wherein the concentration of ruthenium catalyst in the first phase is higher than the concentration of ruthenium catalyst in the second phase,
• a third step of feeding the first phase to a reaction system of the partial hydrogenation reaction,
• a fourth step of bringing the second phase containing the ruthenium catalyst and the eluted nickel into contact with a metal catalyst to produce a second metal salt-containing acidic aqueous solution including nickel, wherein the metal catalyst contains at least one metal selected from the group consisting of Cu, Ag, Au, Pd, Pt, Rh, Ir, Ru and Re
• and a fifth step of feeding the second metal salt-containing acidic aqueous solution including nickel to the reaction system of the partial hydrogenation reaction, wherein the concentration of nickel in the second metal salt-containing acidic aqueous solution is lower than the concentration of nickel in the second phase.