Process for preparing polyolefin products
View Patent ↗A novel liquid phase polymerization process for preparing a polyolefin product having preselected properties is disclosed. The process includes the steps of providing a liquid feedstock which contains an olefinic component and a catalyst composition consisting of a stable complex of BF 3 and a complexing agent therefor. The feedstock may comprise any one or more of a number of olefins including branched olefins such as isobutylene, C 3 to C 15 linear alpha olefins and C 4 to C 15 reactive non-alpha olefins. The feedstock and the catalyst composition are introduced into a residual reaction mixture recirculating in a loop reactor reaction zone provided in the tube side of a shell and tube heat exchanger at a recirculation rate sufficient to cause intimate intermixing of the residual reaction mixture, the added feedstock and the added catalyst composition. The heat of the polymerization reaction is removed from the recirculating intimately intermixed reaction admixture at a rate calculated to provide a substantially constant reaction temperature therein while the same is recirculating in said reaction zone. The conditions in the reactor are appropriate for causing olefinic components introduced in said feedstock to undergo polymerization to form the desired polyolefin product in the presence of the catalyst composition. A product stream containing the desired polyolefin product is withdrawn from the reaction zone. The introduction of the feedstock into the reaction zone and the withdrawal of the product stream from the reaction zone are controlled such that the residence time of the olefinic components undergoing polymerization in the reaction zone is appropriate for production of the desired polyolefin product.
1. A single-stage liquid phase polymerization process for preparing a polyolefin product having preselected properties, said process comprising:
providing a liquid feedstock comprising at least one olefinic component;
providing a catalyst composition comprising a complex of BF 3 and a complexing agent therefor which comprises an aliphatic alcohol having a primary hydroxyl group and no hydrogen on a beta carbon, said complex thereby being stable at temperatures greater than 0° C.;
introducing said feedstock and said catalyst composition into a residual reaction mixture in a loop reactor reaction zone;
recirculating the residual reaction mixture with the feedstock and the catalyst composition therein in said zone at a recirculation rate sufficient to cause intimate intermixing of the residual reaction mixture, the feedstock and the catalyst composition to thereby present a recirculating, intimately intermixed reaction admixture of the residual reaction mixture, the feedstock and the catalyst composition in said reaction zone;
maintaining the recirculating intimately intermixed reaction admixture in its intimately intermixed condition and removing heat of reaction from the reaction admixture at a rate calculated to provide a substantially constant reaction temperature greater than 0° C. in the reaction admixture while the reaction admixture is recirculating in said reaction zone;
withdrawing a product stream comprising polyolefin product and catalyst composition from said reaction zone; and
controlling the introduction of said feedstock into said reaction zone and the withdrawal of said product stream from the reaction zone such that the residence time of the olefinic components undergoing polymerization in the reaction zone is appropriate for production of said polyolefin product.
2. A process as set forth in claim 1 , wherein said reaction zone comprises a tube side of a shell-and-tube heat exchanger.
3. A process as set forth in claim 1 , further comprising adding a quenching material capable of killing the catalyst to the withdrawn product stream.
4. A process as set forth in claim 1 , wherein said residence time is no greater than 4 minutes.
5. A process as set forth in claim 1 , wherein said complexing agent comprises a C 1 -C 8 aliphatic alcohol.
6. A process as set forth in claim 5 , where said alcohol comprises methanol.
7. A process as set forth in claim 1 , wherein the molar ratio of BF 3 to complexing agent in said complex ranges from approximately 0.5:1 to approximately 1:1.
8. A process as set forth in claim 1 , wherein said feedstock and said catalyst composition are premixed and introduced into the reaction zone together as a single stream.
9. A process as set forth in claim 1 , wherein said feedstock and said catalyst composition are introduced into the reaction zone separately as two streams.
10. A process as set forth in claim 1 , wherein said residual reaction mixture is recirculated at a rate such that a Reynolds number of at least 2000 is maintained in said reaction zone.
11. A process as set forth in claim 1 , wherein a heat transfer coefficient U of at least 50 Btu/min ft 2 ° F. is maintained in said reaction zone.
12. A process as set forth in claim 1 , wherein said feed stock comprises at least 30% by weight of said olefinic component.
13. A process as set forth in claim 12 , wherein said olefinic component comprises isobutylene.
14. A process as set forth in claim 1 , wherein the olefinic component comprises isobutylene and the polyolefin product comprises polyisobutylene.
15. A process as set forth in claim 14 , wherein said polyisobutylene has a vinylidene content of at least 50%.
16. A process as set forth in claim 1 , wherein the olefinic component comprises a C 3 to C 15 linear alpha olefin.
17. A process as set forth in claim 1 , wherein the olefinic component comprises a C 4 to C 15 non-alpha olefin.
18. A process as set forth in claim 2 , further comprising adding a quenching material capable of killing the catalyst to the withdrawn product stream.
19. A process as set forth in claim 2 , wherein said residual reaction mixture is recirculated at a rate such that a Reynolds number of at least 2000 is maintained in said reaction zone.
20. A process as set forth in claim 3 , wherein said residual reaction mixture is recirculated at a rate such that a Reynolds number of at least 2000 is maintained in said reaction zone.
21. A single-stage liquid phase polymerization process for preparing a polyolefin product having preselected properties, said process comprising:
providing a liquid feedstock comprising at least one olefinic component;
providing a catalyst composition comprising a complex of BF 3 and a complexing agent therefor, said complexing agent comprising a glycol, said complex being stable at temperatures needed to produce said polyolefin product;
introducing said feedstock and said catalyst composition into a residual reaction mixture in a loop reactor reaction zone;
recirculating the residual reaction mixture with the feedstock and the catalyst composition therein in said zone at a recirculation rate sufficient to cause intimate intermixing of the residual reaction mixture, the feedstock and the catalyst composition to thereby present a recirculating, intimately intermixed reaction admixture of the residual reaction mixture, the feedstock and the catalyst composition in said reaction zone;
maintaining the recirculating intimately intermixed reaction admixture in its intimately intermixed condition and removing heat of reaction from the reaction admixture at a rate calculated to provide a substantially constant reaction temperature in the reaction admixture while the reaction admixture is recirculating in said reaction zone, said constant reaction temperature being at a level appropriate for causing olefinic components introduced in said feedstock to undergo polymerization to form said polyolefin product in the presence of said catalyst composition;
withdrawing a product stream comprising polyolefin product and catalyst composition from said reaction zone; and
controlling the introduction of said feedstock into said reaction zone and the withdrawal of said product stream from the reaction zone such that the residence time of the olefinic components undergoing polymerization in the reaction zone is appropriate for production of said polyolefin product.
22. A process as set forth in claim 21 , where said complexing agent comprises ethylene glycol.