Process for forming polyolefins

Patent metadata

Field	Value
Publication number	US-9850330-B2
Application number	US-201615289597-A
Country	US
Kind code	B2
Filing date	Oct 10, 2016
Priority date	Apr 29, 2014
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

Processes of forming polyolefins are described herein. One or more specific embodiments of the processes generally include introducing olefin monomer selected from C 2 -C 3 olefins into a first reaction zone under first polymerization conditions to form a first polyolefin; withdrawing a transfer effluent from the first reaction zone, the transfer effluent including first polyolefin and unreacted olefin monomer; introducing the transfer effluent, a comonomer selected from C 4 -C 8 olefins, and additional olefin monomer to a second reaction zone under second polymerization conditions to form a second reactor product; maintaining an essentially constant comonomer:olefin monomer ratio in the second reaction zone; and withdrawing at least a portion of the second reactor product, wherein the second reactor product includes a bimodal polyolefin.

First claim

What is claimed is:

1. A process of forming polyolefins comprising:
introducing olefin monomer selected from C 2 -C 3 olefins into a first reaction zone under first polymerization conditions to form a first polyolefin;
withdrawing a transfer effluent from the first reaction zone, the transfer effluent comprising the first polyolefin and unreacted olefin monomer;
introducing the transfer effluent, a comonomer selected from C 4 -C 8 olefins, and additional olefin monomer to a second reaction zone under second polymerization conditions to form a second reactor product;
maintaining an essentially constant comonomer:olefin monomer weight ratio of from about 0.005:1 to 100:1 in the second reaction zone; and
withdrawing at least a portion of the second reactor product, wherein the second reactor product comprises a bimodal polyolefin.

2. The process of claim 1 , wherein the olefin monomer comprises ethylene.

3. The process of claim 2 , wherein the comonomer comprises hexene.

4. The process of claim 1 , wherein the first reaction zone, the second reaction zone or a combination thereof comprise a loop slurry reaction vessel.

5. The process of claim 1 , wherein the second reaction zone comprises a loop slurry reaction vessel and the loop slurry reaction vessel comprises a plurality of olefin feed locations, comonomer feed locations, hydrogen feed locations, or a combinations thereof.

6. The process of claim 1 , wherein maintaining a comonomer:olefin monomer ratio essentially constant comprises determining a concentration of carry over olefin monomer in the transfer effluent; and
adjusting a rate of introduction of the additional olefin monomer into the second reaction zone, adjusting a rate of introduction of the comonomer into the second reaction zone or a combination thereof in response to the carry over olefin monomer concentration.

7. The process of claim 6 , wherein the carry over olefin monomer concentration is determined by a process comprising:
irradiating in-situ the transfer effluent;
measuring scattered energy from the transfer effluent; and
determining from the measured scattered energy the carry over olefin monomer concentration.

8. The process of claim 6 , wherein the carry over olefin monomer concentration is determined by calculating the production rate of first polyolefin in the first reaction zone.

9. The process of claim 8 , wherein the production rate of the first polyolefin in the first reaction zone is determined from the calculated reaction quotient (Q r×n ) and the heat of polymerization per unit of polyolefin produced.

10. The process of claim 6 , wherein the carry over olefin monomer concentration is determined by performing an energy balance calculation for the first reaction zone.

11. The process of claim 1 , further comprising maintaining an essentially constant comonomer:olefin monomer ratio of from about 0.5:1 to 100:1 in the second reaction zone.

12. The process of claim 1 , further comprising maintaining an essentially constant comonomer:olefin monomer ratio of from about 1:1 to 10:1 in the second reaction zone.

13. A process of forming polyolefins comprising:
introducing olefin monomer selected from C 2 -C 3 olefins into a reaction zone under polymerization conditions to form a polyolefin via an input stream;
introducing a comonomer selected from C 4 -C 8 olefins into the reaction zone; and
maintaining an essentially constant comonomer:olefin monomer ratio of from about 0.005:1 to 100:1 in the reaction zone by determining a concentration of olefin monomer introduced into the reaction zone; and
adjusting a rate of introduction of olefin monomer into the reaction zone, adjusting a rate of introduction of the comonomer into the reaction zone or a combination thereof in response to the concentration of olefin monomer concentration introduced into the reaction zone.

14. The process of claim 13 , wherein the olefin monomer concentration is determined by a process comprising:
irradiating in-situ the input stream;
measuring scattered energy from the input stream; and
determining from the measured scattered energy the olefin monomer concentration.

15. The process of claim 13 , further comprising maintaining an essentially constant comonomer:olefin monomer ratio of from about 0.5:1 to 100:1 in the second reaction zone.

16. The process of claim 13 , further comprising maintaining an essentially constant comonomer:olefin monomer ratio of from about 1:1 to 10:1 in the second reaction zone.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Kufeld Scott E
• Mutchler Joel A

Classifications

• C08F2500/01

  High molecular weight, e.g. >800,000 Da. · CPC title

• C08F210/02 Primary

  Ethene · CPC title

• C08F210/16 Primary

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08L23/10

  Homopolymers or copolymers of propene · CPC title

• C08L23/00

  Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers · CPC title