Polymerization of propylene

Claim 1

METHOD OF CONDUCTING A POLYMERIZATION OPERATION WITH A PLURALITY OF POLYMERIZATION ZONES TO PRODUCE PROPYLENE TETRAMER AND LOWER BOILING PROPYLENE POLYMERS FROM A PROPYLENE CHARGE WHICH METHOD COMPRISES THE FOLLOWING SEQUENTIAL OPERATIONAL PHASES: (1) INTRODUCING 50-95 PARTS OF THE PROPYLENE CHARGE INTO A POLYMERIZATION ZONE A ANS THEREIN REACTING THE PROPYLENE AT A TEMPERATURE MAINTAINED SUBSTANTIALLY THROUGHOUT THE ZONE WITHIN THE RANGE OF 360-390*F. IN THE PRESENCE OF A PHOSPHORIC ACID CATALYST OF RELATIVELY LOW AVERAGE ACTIVITY AND WITHOUT SEPARATE ADDITION OF WATER TO THE REACTANT, INTRODUCING THE EFFUENT FROM ZONE A, TOGETHER WITH 5-50 ADDITIONAL PARTS OF PROPYLENE CHARGE AND WITH WATER ADDED IN AMOUNT OF AT LEAST ABOUT ONE LIQUID VOLUME PER 10,000 LIQUID VOLUMES OF TOTAL HYDROCARBON INTRODUCED, INTO A POLYMERIZATION ZONE B AND THEREIN REACTING THE MIXTURE AT A TEMPERATURE MAINTAINED SUBSTANTIALLY THROUGHOUT THE ZONE WITHIN THE RANGE OF 420-475* F. IN THE PRESENCE OF A PHOSPHORIC ACID CATALYST OF RELATIVELY HIGH AVERAGE ACTIVITY TO YIELD MAINLY PROPYLENE TETRAMER; (2) STOPPING THE OPERATION OF ZONE A AND REPLACING THE CATALYST THEREIN WITH CATALYST OF RELATIVELY HIGH AVERAGE ACTIVITY WHILE CONTINUING THE OPERATION OF ZONE B BY REACTING THEREIN PROPYLENE CHARGE, CONTAINING WATER ADDED IN AMOUNT OF AT LEAST ABOUT ONE LIQUID VOLUME PER 10,000 LIQUID VOLUMES OF TOTAL HYDROCARBON INTRODUCED, AT A TEMPERATURE MAINTAINED SUBSTANTIALLY THROUGHOUT THE ZONE WITHIN THE RANGE OF 390-475*F. TO YIELD MAINLY DIMER AND TRIMER PRODUCTS, THEN OPERATING ZONERS A AND B IN PARALLEL BY REACTING IN EACH PROPYLENE CHARGE UNDER THE CONDITIONS JUST SPECIFIED FOR ZONE B TO YIELD MAINLY DIMER AND TRIMER PRODUCTS; (3) THEN, WHEN THE CATALYST ACTIVITY IN ZONE B HAS BECOME RELATIVELY LOW, CONDUCTING THE OPERATION OF ZONES A AND B SO THAT EACH OPERATES IN THE MANNER OF, AND UNDER THE CONDITIONS SPECIFIED FOR, THE OTHER ZONE IN PHASE (1); AND (4) THEREAFTER CONDUCTING THE OPERATION SUCH THAT EACH OF ZONES A AND B OPERATES IN THE MANNER OF, AND UNDER THE CONDITIONS SPECIFIED FOR, THE OTHER ZONE IN PHASE (2).