Methods for determining transition metal compound concentrations in multicomponent liquid systems

Patent metadata

Field	Value
Publication number	US-10697889-B2
Application number	US-201816006976-A
Country	US
Kind code	B2
Filing date	Jun 13, 2018
Priority date	Jul 21, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Methods for determining the concentration of transition metal compounds in a solution containing more than one transition metal compound are described. Polymerization reactor systems providing real-time monitoring and control of the concentrations of the transition metal components of a multicomponent catalyst system are disclosed, as well as methods for operating such polymerization reactor systems and for improving methods of preparing the multicomponent catalyst system.

First claim

We claim:

1. A process for preparing a catalyst composition, the process comprising:
(I) contacting a first transition metal compound, a second transition metal compound, a solid activator, and an optional co-catalyst to form the catalyst composition;
(II) determining a concentration of the first transition metal compound in a solution containing the first transition metal compound and the second transition metal compound, wherein the solution is separated from the catalyst composition, and the concentration is determined via the steps of:
(i) submitting a sample of the solution to a sample chamber;
(ii) irradiating the sample in the chamber with a light beam at a wavelength in the UV-visible spectrum; and
(iii) generating a sample absorbance profile of the sample, subtracting a reference absorbance profile of the second transition metal compound in a reference solution from the sample absorbance profile to result in a first transition metal compound absorbance profile, and correlating the first transition metal compound absorbance profile to a standard to determine the concentration of the first transition metal compound in the solution; and

(III) adjusting a relative amount of at least one component of the catalyst composition based on the concentration of the first transition metal compound in the solution.

2. The process of claim 1 , wherein a solution feed stream containing both the first transition metal compound and the second transition metal compound is contacted with a slurry of the solid activator in step (I).

3. The process of claim 1 , wherein the first transition metal compound, the second transition metal compound, the solid activator, and the co-catalyst are contacted in step (I).

4. The process of claim 1 , wherein the solution is separated from the catalyst composition using sieving, filtering, centrifuging, settling, or any combination thereof.

5. The process of claim 1 , wherein the relative amount of the first transition metal compound, the second transition metal compound, the solid activator, or any combination thereof, is adjusted in step (III).

6. The process of claim 1 , wherein:
the wavelength in step (ii) comprises wavelengths in the 300 nm to 600 nm range;
the sample absorbance profile in step (iii) comprises an absorbance curve over a range of wavelengths; and
the step of correlating is performed at a single wavelength.

7. The process of claim 1 , wherein the first transition metal compound and the second transition metal compound independently comprise chromium, vanadium, titanium, zirconium, hafnium, or a combination thereof.

8. The process of claim 1 , wherein:
the first transition metal compound is an unbridged metallocene compound; and
the second transition metal compound is a bridged metallocene compound.

9. The process of claim 1 , wherein the second transition metal compound comprises two or more different second transition metal compounds.

10. The process of claim 1 , wherein the reference solution comprises the second transition metal compound and a hydrocarbon solvent.

11. The process of claim 10 , wherein:
the hydrocarbon solvent comprises 1-hexene, isobutane, toluene, cyclohexene, or any combination thereof;
a weight ratio of the first transition metal compound to the second transition metal compound in the solution is in a range from about 1:50 to about 1:5;
the sample absorbance profile, the reference absorbance profile, and the first transition metal compound absorbance profile independently comprise an absorbance curve over a range of wavelengths; and
the standard comprises a calibration curve.

12. A catalyst preparation system comprising:
(a) a catalyst preparation vessel configured to contact a first transition metal compound, a second transition metal compound, and a solid activator to form a catalyst composition;
(b) an activator feed stream configured to introduce the solid activator into the catalyst preparation vessel;
(c) a first transition metal compound feed stream configured to introduce the first transition metal compound into the catalyst preparation vessel;
(d) a second transition metal compound feed stream configured to introduce the second transition metal compound into the catalyst preparation vessel;
(e) a catalyst system feed stream configured to withdraw the catalyst composition from the catalyst preparation vessel; and
(f) an analytical system configured to determine a concentration of the first transition metal compound in a solution comprising the first transition metal compound and the second transition metal compound, wherein the solution is separated from the catalyst composition.

13. The catalyst preparation system of claim 12 , wherein the analytical system comprises an ultraviolet-visible spectrometer.

14. The catalyst preparation system of claim 12 , wherein the analytical system comprises an ultraviolet-visible spectrometer with an integrated computer system for measuring a sample absorbance profile of the first transition metal compound in the solution, for subtracting a reference absorbance profile of the second transition metal compound in a reference solution from the sample absorbance profile to result in a first transition metal compound absorbance profile, and for correlating the first transition metal compound absorbance profile to a standard to determine the concentration of the first transition metal compound in the solution.

15. The catalyst preparation system of claim 12 , wherein the catalyst preparation system further comprises (g) a controller configured to control a flow rate of the activator feed stream, a flow rate of the first transition metal compound feed stream, and/or a flow rate of the second transition metal compound feed stream into the catalyst preparation vessel based on the concentration determined by the analytical system.

16. The catalyst preparation system of claim 12 , wherein:
the catalyst preparation vessel is further configured to contact the first transition metal compound, the second transition metal compound, the solid activator, and a co-catalyst to form the catalyst composition; and
the catalyst preparation system further comprises a co-catalyst feed stream configured to introduce the co-catalyst into the catalyst preparation vessel.

17. The catalyst preparation system of claim 12 , wherein the analytical system further comprises a liquid-solid separating device configured to separate the solution from the catalyst composition.

18. The catalyst preparation system of claim 12 , wherein the first transition metal compound feed stream and the second transition metal compound feed stream are introduced directly into the catalyst preparation vessel.

19. The catalyst preparation system of claim 12 , wherein the first transition metal compound feed stream and the second transition metal compound feed stream are combined prior to the catalyst preparation vessel.

20. The catalyst preparation system of claim 12 , wherein:
the solution comprises the first transition metal compound, the second transition metal compound, and a hydrocarbon solvent;
the first transition metal compound and the second transition metal compound independently comprise a bridged or unbridged metallocene compound; and
the activator feed stream comprises a slurry of the solid activator.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Yang Qing
• Buck Richard M

Classifications

• C08F2420/07

  Heteroatom-substituted Cp, i.e. Cp or analog where at least one of the substituent of the Cp or analog ring is or contains a heteroatom · CPC title

• C08F2420/09

  Cyclic bridge, i.e. Cp or analog where the bridging unit linking the two Cps or analogs is part of a cyclic group · CPC title

• C08F210/00

  Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond · CPC title

• B01J19/0033 Primary

  Optimalisation processes, i.e. processes with adaptive control systems (adaptive control systems per se G05B13/00) · CPC title

• C08F4/65904

  in combination with another component of C08F4/64 · CPC title