METHOD FOR STOPPING OLEFIN POLYMERIZATION REACTION IN EMERGENCY

PROBLEM TO BE SOLVED: To stop an olefin polymerization reaction in an emergency within a short time by introducing a compound selected from among water, alcohols, molecular oxygen, CO2 and CO in polymerizing an olefin in a vapor phase in the presence of a specified catalyst. SOLUTION: A catalyst is prepared by bringing a compound containing a metal of group IV in the periodic table, a compound containing a metal of group I, II or III in the periodic table, an organic compound having a plurality of conjugated double bonds, a modified organoaluminum compound having an Al-O-Al bond and/or a boron compound and an inorganic compound support and/or a particulate polymer support into contact with each other. An olefin (e.g. ethylene) is (co)polymerized steadily in a vapor phase. When the emergency stop of the polymerization reaction is necessary, a compound selected from among water, alcohols, molecular oxygen, carbon dioxide and carbon monoxide is introduced into the reactor, whereupon the olefin polymerization reaction can be stopped within a short time.