Exxonmobil Chemical Patents Inc.

Exxon Chemical Patents, Inc.

Scott Thomas Roger

James Austin Kendrick

Thomas W Towles

Anthony Nicholas Speca

Stanley J Katzen

Zerong Lin

Edward F Smith

Robert G Depierri

Keith W Trapp

David Geoffrey Marrow

Andrew M Cochran

Processes and apparatus for preparing bimodal polymers are provided. In some embodiments, processes include introducing a monomer, a first diluent, a catalyst, hydrogen, at a first hydrogen concentration, and optional comonomer, to a first loop reactor to produce, under polymerization conditions, a first slurry of polymer solids. Processes may also include continuously discharging the first slurry of polymer solids from the loop reactor as a first polymerization effluent to a first flash tank; separating the first polymerization effluent in the first flash tank to provide a first concentrated polymer slurry with significantly lower hydrogen concentration; and transferring the first concentrated polymer slurry from the flash tank to a re-slurry mixer. Processes may further include introducing a re-slurry mixer diluent to the first concentrated polymer slurry to form a second concentrated polymer slurry in the re-slurry mixer that can be pumped to a second slurry loop reactor.

Processes and apparatus for bimodal slurry polymerization

The present invention relates to the removal of hydrocarbon residues from a catalyst and more specifically the air activation of a catalyst containing hydrocarbon residues. It also relates to extruded pipe and utility conduit resins comprising polyethylene, household/industrial chemicals container resins, and to a polyethylene resin particularly suitable for large parts by blow molding and sheet extrusion procedures, wherein the resin is made by a process using an activated chromium and titanium-based catalyst.

Catalyst activation and resins therefrom

Methods of making supported chromium catalyst systems and processes of polymerizing ethylene using the supported chromium catalyst systems are disclosed. A method of forming a catalyst system in a polymerization reactor includes contacting a supported chromium catalyst and a metal alkyl cocatalyst by cofeeding the catalyst and cocatalyst to the reactor or feeding the catalyst and cocatalyst separately to the reactor, to form a catalyst system. The catalyst and cocatalyst are not pre-contacted prior to the feeding or cofeeding step. The catalyst system can be contacted with ethylene and optional alpha-olefin comonomer to form polyethylene.

Catalyst system and process

A process/apparatus is disclosed for continuously separating a liquid medium comprising diluent and unreacted monomers from a polymerization effluent comprising diluent, unreacted monomers and polymer solids, comprising a continuous discharge of the polymerization effluent from a slurry reactor through a discharge valve and transfer conduit into a first intermediate pressure flash tank with a conical bottom defined by substantially straight sides inclined at an angle to that of horizontal equal to or greater than the angle of slide of the slurry/polymer solids and an exit seal chamber of such diameter (d) and length (l) as to maintain a desired volume of concentrated polymer solids/slurry in the exit seal chamber such as to form a pressure seal while continuously discharging a plug flow of concentrated polymer solids/slurry bottom product of the first flash tank from the exit seal chamber through a seal chamber exit reducer with inclined sides defined by substantially straight sides inclined at an angle to that of horizontal equal to or greater than the angle of slide of the polymer solids which remain after removal of about 50 to 100% of the inert diluent therefrom to a second flash tank at a lower pressure.

Continuous slurry polymerization apparatus

A process of converting a loop reactor into multiple loop reactors comprising starting with a loop reactor comprising at least 8 vertical legs, at least two non-vertical conversion runs, each non-vertical run connected in fluid flow communication with two vertical legs; at least two feed inlets; and at least two continuous discharge conduits; disconnecting at least one connection of each conversion run; and reconnecting each conversion run in fluid flow communication with a different vertical leg in such a manner to form multiple loop reactors each having at least one feed inlet and at least one continuous discharge conduit.

Continuous slurry polymerization process and apparatus

Methods are provided for determining and controlling polymer product properties on-line in a slurry reactor system, such as a stirred slurry or slurry loop reactor. The methods include obtaining a regression model for determining a polymer product property, the regression model including principal component loadings and principal component scores, acquiring a Raman spectrum of polymer product in the slurry reactor system, calculating a new principal component score from at least a portion of the Raman spectrum and the principal component loadings, and calculating the polymer product property by applying the new principal component score to the regression model. The property can be controlled by adjusting at least one polymerization parameter based on the calculated polymer product property.

On-line measurement and control of polymer product properties by Raman spectroscopy

A process/apparatus is disclosed for continuously separating a liquid medium comprising diluent and unreacted monomers from a polymerization effluent of a slurry loop reactor containing a flow of slurry therein, comprising a discharge conduit extending a distance into the loop reactor; the conduit having a longitudinal axis and an opening inside the loop reactor; at least a portion of the conduit being curved along its longitudinal axis inside the loop reactor; and the opening substantially facing the flow of the slurry, wherein the discharge conduit is located within a lower leg of the loop reactor such that a continuous discharge of the polymerization effluent from a slurry reactor through a discharge valve and transfer conduit into a first intermediate pressure flash tank wherein volatile inert diluent and unreacted monomers are removed and the polymer solids which remain after removal of about 50 to 100% of the inert diluent therefrom to a second flash tank at a lower pressure.

Continuous slurry polymerization volatile removal

Polymerization processes are disclosed for producing polyethylene having a target density and improved environmental stress resistance. Ethylene and optionally one or more &#x3b1;-olefin comonomers, supported chromium catalyst, and metal alkyl cocatalyst are contacted to produce polyethylene. The density of the polyethylene is determined, and the concentration of cocatalyst is adjusted in response to a deviation between the density of the polyethylene and the target density. The catalyst and cocatalyst can be fed separately into the reactor, or can be co-fed, eliminating the need to pre-contact the catalyst and cocatalyst prior to introducing them into the reactor.

Polymerization process

A process/apparatus is disclosed for continuously separating a liquid medium comprising diluent and unreacted monomers from a polymerization effluent comprising diluent, unreacted monomers and polymer solids, comprising a continuous discharge of the polymerization effluent from a slurry reactor through a discharge valve and transfer conduit into a first intermediate pressure flash tank with a conical bottom defined by substantially straight sides inclined at an angle to that of horizontal equal to or greater than the angle of slide of the slurry/polymer solids and an exit seal chamber of such diameter (d) and length (l) as to maintain a desired volume of concentrated polymer solids/slurry in the exit seal chamber such as to form a pressure seal while continuously discharging a plug flow of concentrated polymer solids/slurry bottom product of said first flash tank from the exit seal chamber through a seal chamber exit reducer with inclined sides defined by substantially straight sides inclined at an angle to that of horizontal equal to or greater than the angle of slide of the polymer solids which remain after removal of about 50 to 100% of the inert diluent therefrom to a second flash tank at a lower pressure.

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Baton Rouge, LA, United States of America

Scott Thomas Roger