Methods for determining transition metal compound concentrations in multicomponent liquid systems
AssigneeChevron Philips Chemical Company LP
InventorsQing Yang, Richard M. Buck
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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.
Claims21
A process for operating a polymerization reactor system, the process comprising:
- (I) contacting a catalyst system comprising a first transition metal compound, a second transition metal compound, an activator, and an optional co-catalyst, with an olefin monomer and an optional olefin comonomer in a reactor within the polymerization reactor system under polymerization reaction conditions to produce an olefin polymer;
- wherein the polymerization reactor system comprises a solution reactor, a gas-phase reactor, a slurry reactor, or a combination thereof;
- (II) determining a concentration of the first transition metal compound in a solution comprising the first transition metal compound and the second transition metal compound, the concentration 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 flow rate of the first transition metal compound into the reactor when the concentration of the first transition metal compound in the solution has reached a predetermined level.
A method for determining a concentration of a first transition metal compound in a solution comprising the first transition metal compound and a second transition metal compound, the method comprising:
- submitting a sample of the solution to a sample chamber comprising a flow cell;
- (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;
- wherein the solution comprises the first transition metal compound, the second transition metal compound, and a hydrocarbon solvent.
A polymerization reactor system comprising:
- (A) a reactor configured to contact a catalyst system with ethylene and an optional olefin comonomer under polymerization reaction conditions to produce an ethylene polymer;
- (B) a catalyst preparation vessel configured to contact a first transition metal compound, a second transition metal compound, an activator, and an optional co-catalyst to form the catalyst system;
- (C) 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 present within the polymerization reactor system;
- and
- (D) a controller configured to control a flow rate of the first transition metal compound into the reactor based on the concentration determined by the analytical system.
Dependencies are inferred from the claim text.