Polymerisation process

Patent metadata

Field	Value
Publication number	US-9605092-B2
Application number	US-201414903372-A
Country	US
Kind code	B2
Filing date	Jul 22, 2014
Priority date	Aug 5, 2013
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

Polymerization process, in particular for the polymerization of monomer selected from ethylene and propylene in a reaction system containing at least three reactors operated in series. The process includes (a) polymerizing monomer in a first reactor having a volume of at least 50 m 3 to produce a first polymer, (b) passing the first polymer to a second reactor and polymerizing monomer in the second reactor to produce a second polymer containing the first polymer and polymer produced in the second reactor, and (c) passing the second polymer to a third reactor and polymerizing monomer in the third reactor to produce a third polymer containing the second polymer and polymer produced in the third reactor. The polymerizations are performed such that between 0.01 and 5 w % of the total mass of the third polymer is polymer produced in the second reactor.

First claim

The invention claimed is:

1. A process for the polymerisation of monomer selected from ethylene and propylene in a reaction system comprising at least three reactors operated in series, which process comprises
(a) polymerising monomer in a first reactor, said first reactor having a volume of at least 50 m 3 , to produce a first polymer,
(b) passing the first polymer to a second reactor and polymerising monomer in the second reactor to produce a second polymer comprising the first polymer and polymer produced in the second reactor,
(c) passing the second polymer to a third reactor and polymerising monomer in the third reactor to produce a third polymer comprising the second polymer and polymer produced in the third reactor,
wherein the polymerisations are performed such that between 0.01 and 5 wt % of the total mass of the third polymer is polymer produced in the second reactor.

2. A process according to claim 1 wherein the third reactor has a volume of at least 50 m 3 .

3. A process according to claim 1 wherein both the first and third reactors are slurry loop reactors.

4. A process according to claim 3 wherein the second reactor also comprises a slurry phase.

5. A process according to claim 1 wherein the second reactor comprises a stirred tank, and wherein both a liquid and a vapour phase are present.

6. A process according to claim 1 wherein the production rate (amount of polymer produced per unit time) in the second reactor is reduced compared to the first and third reactors and/or wherein the space time yield (STY) in the second reactor, which is a measure of the amount of polymer produced per unit time per unit volume of the reactor, is reduced in the second reactor compared to the first and third reactors.

7. A process according to claim 1 wherein the pressure in the second reactor is above 0.5 MPa (5 bar), and is 10-90% lower than the lowest of the first reactor pressure and the third reactor pressure.

8. A process according to claim 1 wherein the temperature in the second reactor is in the range 40 to 100° C.

9. A process according to claim 1 wherein the second reactor comprises liquid and vapour phases and the distribution of diluent present between the liquid and vapour phases in the second reactor is such that at least 30% of the diluent is in the liquid phase.

10. A process according to claim 1 wherein the residence time in the second reactor is in the range of 10 to 90 minutes.

11. A process according to claim 1 wherein between 0.1and 5 wt % of polymer, based on total mass of the third polymer is polymer produced in the second reactor.

12. A process according to claim 1 which process comprises
(a) polymerising monomer in a first reactor to produce a slurry of a first polymer,
(b) passing a slurry of the first polymer to a second reactor and polymerising monomer in the second reactor to produce a slurry of a second polymer, said second polymer comprising the first polymer and polymer produced in the second reactor,
(c) passing a slurry of the second polymer to a third reactor and polymerising monomer in the third reactor to produce a slurry of a third polymer, said third polymer comprising the second polymer and polymer produced in the third reactor.

13. A process according to claim 1 wherein a separate feed comprising monomer is added to the second reactor.

14. A process according to claim 1 wherein the second reactor comprises a liquid phase and the liquid phase in the second reactor comprises 0.1 to 1 mol % monomer.

15. A process according to claim 1 wherein the second reactor comprises a liquid phase and the molar ratio of comonomer to monomer in the liquid phase in the second reactor is between 24:1 and 4:1 by moles of comonomer to monomer.

16. A process according to claim 1 wherein there is fed to the second reactor the first polymer and a first stream comprising monomer which is derived from the effluent withdrawn from the third or a subsequent reactor.

17. A process according to claim 1 which process comprises
(a) polymerising monomer in the first reactor to produce a slurry of a first polymer,
(b) passing a slurry of the first polymer to a second reactor and polymerising monomer in the second reactor to produce a slurry of a second polymer, said second polymer comprising the first polymer and polymer produced in the second reactor,
(c) passing a slurry of the second polymer to a third reactor, said third reactor having a volume of at least 50 m 3 , and polymerising monomer in the third reactor to produce a slurry of a third polymer, said third polymer comprising the second polymer and polymer produced in the third reactor,
wherein there is also fed to the second reactor a first stream comprising monomer which is derived from the effluent withdrawn from the third or a subsequent reactor.

18. A process according to claim 16 wherein the third or subsequent reactor is a slurry reactor and produces an effluent in the form of a slurry of polymer solids in a liquid medium comprising diluent, and this stream is treated to vaporise the components of the liquid medium, which are then separated from the polymer solids, wherein the first stream is at least 80% by weight of this separated stream.

19. A process according to claim 16 wherein at least 80% by weight of the first stream is in vapour form when passed to the second reactor and/or wherein at least part of the first stream is passed to the second reactor without compression and/or at least part of the first stream is passed to the second reactor without indirect cooling.

20. A process according to claim 16 wherein the first stream is separated from the polymer withdrawn from the third or subsequent reactor at a pressure of 0.5 MPa (5 bar) and above.

21. A process according to claim 16 wherein the process comprises only three reactors i.e. the first, second and third reactors.

22. A process according to claim 16 wherein the second reactor comprises a stirred tank which is configured in association with a fractionator, and wherein lighter components, such as hydrogen and monomer, and also diluent, are recovered from the fractionator as a vapour for further treatment and recycle.

23. A process according to claim 10 wherein the residence time in the second reactor is in the range of 15 to 60 minutes.

24. A process according to claim 11 wherein between 0.5 and 1.5 wt % of polymer based on total mass of the third polymer is polymer produced in the second reactor.

25. A process according to claim 15 wherein the second reactor comprises a liquid phase and the molar ratio of comonomer to monomer in the liquid phase is higher in the second reactor than in either of the first and third reactors.

26. A process according to claim 18 wherein the first stream is essentially all of the separated stream.

27. A process according to claim 26 wherein essentially all of the first stream is in vapour form when passed to the second reactor.

Assignees

• Ineos Europe Ag

Inventors

• Parisel Marc Jean-Marie Ghislain
• Van Breuseghem Philip
• Walworth Brent R

Classifications

• C08F6/003 Primary

  from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom · CPC title

• C08F2500/07

  High density, i.e. > 0.95 g/cm3 · CPC title

• C08F2500/08

  Low density, i.e. < 0.91 g/cm3 · CPC title

• C08F2/001

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title

• C08F6/005

  from solid polymers · CPC title