Polymerization process using a ziegler type catalyst

Claim 1

AN OLEFIN POLYMERIZATION PROCESS COMPRISING CONTACTING AN ALPHA OLEFIN IN A POLYMERIZATION ZONE, IN VAPOR PHASE, WITH A FLUIDIZED BED OF POLYMER PRODUCT AND A CATALYST CONSISTING ESSENTIALLY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRIHALIDES OF TITANIUM AND VANADIUM, AND A STOICHIOMETRIC EXCESS, BASED ON SAID TRIHALIDE, OF AN ALUMINUM ALKYL COMPOUND, WHEREIN (1) SAID TRIHALIDE IS PREPARED IN A SEPARATE CATALYST PREPARATION ZONE BY CONTACTING (A) A CORRESPONDING TETRAHALIDE WITH (B) AN ALUMINUM ALKYL REDUCING AGENT, IN (C) A MEDIUM CONSISTING OF AN ALKANE OF 1 TO 4 CARBON ATOMS PER MOLECULE, (D) AT REDUCING CONDITIONS, INCLUDING A TEMPERATURE IN THE RANGE FROM 50* TO 250*C. AND A PRESSURE AT LEAST EQUAL TO THE CRITICAL PRESSURE OF SAID ALKANE, (2) THE RESULTING TRIHALIDE IS INTRODUCED INTO SAID POLYMERIZATION ZONE IN SUSPENSION IN SAID HYDROCARBON MEDIUM, (3) SAID ALUMINUM ALKYL CATALYST COMPOUND IS COMBINED WITH SAID TRIHALIDE AT A TEMPERATURE NOT SUBSTANTIALLY EXCEEDING THE POLYMERIZATION TEMPERATURE, AND (4) POLYMER IS RECOVERED FROM SAID POLYMERIZATION ZONE.