Univation Technologies, LLC

Rich John Stolz

Richard B Pannell

Fathi David Hussein

John Roberts Parrish

R Eric Pequeno

William Albert Matthews

Ivan Jeremy Hartley

Brandon C Locklear

William A Matthews

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

In some embodiments, a method for determining initial conditions for a transition from an initial reaction to a target reaction to minimize (or substantially minimize) the amount of off-grade material produced during the transition, and optionally also process control variables for implementing the transition. Some embodiments also include the steps of setting the reaction conditions to determined initial conditions and then implementing the transition. In some embodiments, a product property that can cause production of more off-grade product during the transition than can any other of the properties is identified as a primary property, and process control variables for implementing the transition are determined so that the product produced during the transition goes off-grade due to the primary property, and due to each of at least one other product property, at the same or substantially the same time, and preferably also so that each non-primary property reaches a value compliant with the target specification set as late as possible but not later than the time the primary property reaches a value compliant with the target specification set.

Method for reducing off-grade product production during reaction transitions

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Baytown, TX, United States of America

Rich John Stolz