Continuous ethylene polymerization with catalyst regeneration

Claim 1

IN A PROCESS FOR POLYMERIZING ETHYLENE WITH A SOLID CATALYST COMPRISING ESSENTIALLY AT LEAST 1 WEIGHT PER CENT EACH OF MOLYBDEUM OXIDE AND A METAL OXIDE SELECTED FROM THE CLASS CONSISTING OF GAMMA-ALUMINA, TITANIA AND ZIRCONIA, WHICH CATALYST HAS BEEN TREATED WITH HYDROGEN AT A TEMPERATURE OF ABOUT 400 TO 650* C. FOR A TIME SUFFICIENT TO EFFECT SUBSTANTIAL ACTIVATION THEREOF, IN A POLYMERIZATION ZONE AT A TEMPERATURE IN THE RANGE OF 75 TO 325* C. AND AT A PRESSURE IN THE RANGE OF 100 TO 5,000 P.S.I.G WHEREIN CONTACT BETWEEN ETHYLENE AND CATALYST IS EFFECTED IN THE PRESENCE OF A SOLVENT, THE IMPROVED METHOD OF OPERATION WHICH COMPRISES CONTINUOUSLY WITHDRAWING FROM THE POLYMERIZATION ZONE AN EFFULENT STREAM CONTAINING POLYMER AND CATALYST, SEPARATING CATALYST FROM THE WITHDRAWN STREAM, REGENERATING A FIRST PORTION OF THE SEPARATED CATALYST BY BURNING CARBONACEOUS DEPOSITS THEREFROM WITH OXYGEN, TREATING THE REGENERATED CATALYST AND ALSO TREATING A SECOND PORTION OF THE SEPARATED CATALYST WITHOUT REGENERATION BY CONTACTING THE REGENERATED FIRST PORTION AND THE UNREGENERATED SECOND PORTION WITH HYDROGEN AT A TEMPERATURE OF ABOUT 400 TO 650* C. FOR A TIME SUFFICIEN TO EFFECT SUBSTANTIAL REACTIVATION THEREOF AND CONTINUOUSLY RETURNING REACTIVATED CATALYST TO THE POLYMERIZATION ZONE.