Gas-phase polymerization process with wet zone
View Patent ↗The present disclosure is directed to a process for producing olefin-based polymer in a gas phase polymerization reactor. The process includes forming a wet zone in the gas phase polymerization reactor. The wet zone is formed by maintaining a temperature less than or equal to the fluidizing medium dew point temperature+2° C. in a region of the reactor. The region is defined as the region extending from the distributor plate to 2.5 meters above the distributor plate. Injection of a high activity catalyst composition in the wet zone produces olefin-based having a settled bulk density greater than 23.5 lb/ft3.
1. A process for producing olefin-based polymer comprising:
providing a gas phase polymerization reactor comprising a distributor plate and a fluidizing medium having a dew point temperature (DPT), the fluidizing medium comprising one or more olefin monomers and from 5 wt % to 25 wt % of a condensed liquid;
forming, in the reactor, a wet zone by maintaining a temperature less than or equal to the DPT+2° C. in a region in the reactor defined as extending from the distributor plate to 2.5 meters above the distributor plate;
injecting a catalyst composition into the wet zone, the catalyst composition having a catalyst activity greater than 50 ton/kg;
contacting, in the wet zone under gas phase polymerization conditions, the catalyst composition with the one more monomers of the fluidizing medium; and
forming particles of olefin-based polymer having a settled bulk density greater than 23.5 lb/ft 3 .
2. The process of claim 1 comprising injecting the catalyst composition into the wet zone at a height where the reactor temperature is from 60° C. to 77° C.
3. The process of claim 1 comprising injecting the catalyst composition in the wet zone when the DPT is from 60° C. to less than 75° C.
4. The process of claim 1 comprising providing a fluidizing medium comprising propylene monomer and from 5 wt % to 25 wt % condensed liquid phase; and
forming particles of propylene homopolymer having a settled bulk density from 23.5 lb/ft 3 to 27 lb/ft 3 .
5. The process of claim 4 comprising contacting a Ziegler-Natta catalyst composition with the one more monomers of the fluidizing medium, the Ziegler-Natta catalyst composition having an internal electron donor comprising a substituted phenylene aromatic diester; and
forming particles of propylene homopolymer having a settled bulk density greater than 25.0 lb/ft 3 .
6. The process of claim 5 wherein the internal electron donor comprises 5-tert-butyl-3-methyl-1,2-phenylene dibenzoate.
7. The process of claim 6 wherein the catalyst composition comprises a procatalyst composition with an average particle size D(50) from 10 microns to 15 microns.
8. The process of claim 6 wherein the catalyst composition comprises a procatalyst composition with an average particle size D(50) from 25 microns to 30 microns.