Univation Technologies, LLC

Exxonmobil Chemical Patents Inc.

Brandon C Locklear

Bruce Jon Savatsky

R Eric Pequeno

James McLeod Farley

Fathi David Hussein

Haiqing Peng

Daudi A Abe

John Francis Szul

Robert Olds Hagerty

Michael E Muhle

Richard B Pannell

Wesley R Mariott

David Michael Glowczwski

William Albert Matthews

Daniel P Zilker

Richard E Pequeno

Abarajith S Hari

Yuet Meng Chu

Rich John Stolz

T R Veariel

Jim Farley

William A Matthews

Tr Veariel

Bruce J Savatsky

TR Veariel

David M Glowczwski

Embodiments of the present disclosure are directed towards catalyst formulations including a metallocene and a stearic compound selected from bis 2-hydroxyethyl stearyl amine, aluminum distearate, and combinations thereof, where the metallocene is represented by the following formula: (Formula (I)) wherein each n-PR is n-propyl, and each X is independently CH, Cl, or F. 

Catalyst formulations

Methods for reducing gels and/or dome sheeting in gas phase polymerization processes and their resulting products are provided. The polymerization processes include polymerizing ethylene and one or more optional comonomers in a fluidized bed reactor in the presence of a metallocene catalyst, hydrogen, and at least one condensing agent.

Methods for making polyethylene polymers

Methods for olefin polymerization are described. The methods include a) forming a first polyolefin under a first set of polymerization conditions in the presence of a first catalyst composition and a first concentration of at least a first continuity additive composition, the first polyolefin composition having a target density, &#x3c1;, and a target Flow Index, FI; and b) forming a second polyolefin composition under a second set of polymerization conditions in the presence of a second catalyst composition and a second concentration of a second continuity additive composition, the second polyolefin composition having a target density, &#x3c1;, and a target Flow Index, FI; wherein the process is essentially free of providing a polymerization neutralizing composition between steps a) and b).

Methods for operating a polymerization reactor

The present disclosure provides a method of maintaining a target value of a melt flow index of a polyethylene polymer product being synthesized with a metallocene catalyst in a fluidized bed gas phase reactor. The method includes producing the polyethylene polymer product at the target value of the melt flow index with a metallocene catalyst in a fluidized bed gas phase reactor at a steady state in which the fluidized bed gas phase reactor is at a first reactor temperature and receives feeds of hydrogen and ethylene at a hydrogen to ethylene feed ratio at a first ratio value. When a change in reactor temperature is detected, the hydrogen to ethylene feed ratio is changed from the first ratio value to a second ratio value so as to maintain the melt flow index value of the polyethylene polymer product at the target value.

Method of maintaining a melt flow index of a polyethylene polymer product

A process for testing a commercial polyolefin condensed mode operation on a pilot plant scale is provided. A feed stream including one or more olefin monomers and one or more inert fluids can be introduced to a fluidized bed contained within a reactor housing having a length to diameter ratio of 1.0 to 20. The one or more olefin monomers can be contacted with one or catalysts within the fluidized bed at conditions sufficient to produce a polyolefin. A cycle gas stream can be withdrawn from the housing, the cycle gas stream having a gas velocity of 1.0 ft/sec to 3.0 ft/sec and including the unreacted monomers and the inert fluids. The cycle gas stream can be compressed to a pressure above the reaction pressure within the housing. The cycle gas stream can be cooled to a temperature that is above the dew point of the cycle gas, and a portion of the compressed cycle gas stream can be removed to create a side stream of the compressed cycle gas stream. The side stream can be cooled to a temperature that is below its dew point to create a gas-liquid mixture, and the cycle gas stream and the cooled side stream including the gas-liquid mixture can be returned to the reactor housing.

Pilot plant scale semi-condensing operation

Methods for extrusion of polyolefins () that control specific energy input to the extruder () for gel reduction. Disclosed herein is an example method for forming plastic products () with reduced gels, comprising: melting a polyolefin resin () in extruder () to form a melt; adjusting specific energy input in the extruder () to reduce gels in the melt; and forming the melt into a polyolefin product (). Disclosed herein is also an example method for forming plastic products () with reduced gels, comprising: melting a polyolefin resin in extruder () to form a melt; selecting a throttle valve () position for gel reduction; setting the throttle valve () at the selected throttle valve () position to restrict flow of the melt out of the extruder (); and forming the melt into a polyolefin product ().

Methods for gel reduction in polyolefins

Methods for extrusion of polyolefins () that utilize melt temperature to control molecular weight and also reduce gels. Disclosed herein is an example method for controlling polymer chain scission in an extrusion system (), comprising: melting a polyolefin resin () in extruder () at a first melt temperature to form a first melt (); passing the first melt () through a screen pack (); forming the first melt) into a first polyolefin product (); melting additional polyolefin resin () of the same grade in the extruder () at a second melt temperature to form a second melt (), wherein the second melt temperature differs from the first melt temperature by 5&#xb0; C. or more to control chain scission in the extruder (); passing the second melt () through the screen pack (); and forming the second melt () into a second polyolefin product ().

Methods for controlling polymer chain scission

Methods for olefin polymerization are described. The methods include a) forming a first polyolefin under a first set of polymerization conditions in the presence of a first catalyst composition and a first concentration of at least a first continuity additive composition, the first polyolefin composition having a target density, 1, and a target Flow Index, FI1; and b) forming a second polyolefin composition under a second set of polymerization conditions in the presence of a second catalyst composition and a second concentration of a second continuity additive composition, the second polyolefin composition having a target density, 2, and a target Flow Index, FI2; wherein the process is essentially free of providing a polymerization neutralizing composition between steps a) and b).

A method for transitioning a gas phase polymerization reactor between metallocene catalysts is provided. The method comprises first reducing the superficial gas velocity and increasing the height of the fluidized bed within the reactor prior to stopping a feed comprising a first metallocene catalyst. The method further comprises introducing a first polymerization neutralizer to the reactor, wherein the first polymerization reactor does not comprise water, and then introducing a second polymerization neutralizer to the reactor, wherein the second polymerization neutralizer is different from the first polymerization neutralizer. After this, the method comprises purging the reactor with an inert gas and then introducing a feed comprising a second metallocene catalyst to the reactor.

Closed reactor transitions between metallocene catalysts

Polyolefin polymerization performed by contacting in a reactor an olefin monomer and optionally a comonomer with a catalyst system in the presence of induced condensing agents (ICA) and optionally hydrogen. The ICA may include two or more ICA components where the composition of the ICA (i.e., the concentration of each ICA component) may affect the polyolefin production rate. Changes to the relative concentration of the two or more ICA components may be according to ICA equivalency factors that allow for increasing the polyolefin production rate while maintain a sticking temperature, increasing polyolefin production rate while increasing the dew point approach temperature of the ICA, or a combination thereof.

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Houston, TX, United States of America

Brandon C Locklear