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Abstract

PURPOSE: To easily reactivate a ruthenium catalyst by keeping the deactivated catalyst lower than the hydrogen partial pressure used in the hydrogenation reaction of an unsaturated organic compound and more than 50^oC lower than the reaction temperature.

CONSTITUTION: A ruthenium catalyst deactivated in the hydrogenation reaction of an unsaturated organic compound is kept lower than the hydrogen partial pressure in the hydrogenation reaction and more than 50^oC lower than the reaction temperature to reactivate the catalyst. Ruthenium black, metallic ruthenium fine particles having extremely small average crystallite diameter, etc., are exemplified as the ruthenium catalyst. The reactivation temperature is appropriately controlled more than about 40^oC lower than the reaction temperature, and the time of reactivation ranges usually from several minutes to several days.