Process for polymerizing monomers in fluidized beds
AssigneeExxon Chemical Patents Inc.
InventorsMarc L. DeChellis, John R. Griffin, Michael E. Muhle
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Abstract
The invention is directed toward polymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins utilizing a bulky ligand transition metal catalyst in a gas phase fluidized bed polymerization reactor operating in condensed mode.
Claims34
A continuous gas phase polymerization process comprising copolymerizing an alpha-olefin monomer with at least one other alpha-olefin comonomer in the presence of a silica-supported metallocene catalyst in a gas phase fluidized bed reactor operating in a condensed mode, said process further comprises a recycle stream passing through a fluidized bed in said reactor wherein the recycle stream comprises a dew point increasing component in an amount greater than 2.0 mole percent.
A continuous process for the polymerization of alpha-olefin monomer and at least one copolymerizable alpha-olefin comonomer in a gas phase fluidized bed reactor, said process comprising the steps of:
- a) passing a recycle stream through said reactor, said recycle stream comprising monomer, comonomer and hydrogen in a ratio of (C.sub.x +H.sub.2)/C.sub.y of less than 0.2, where C.sub.x, H.sub.2 and C.sub.y are the mole percent respectively of comonomer, hydrogen and monomer, said recycle stream further comprising a dew point increasing component in an amount greater than 2.0 mole percent and optionally, a non-condensable inerts making up the balance of said recycle stream;
- b) introducing a polymerization catalyst into said reactor, the polymerization catalyst comprising a metallocene catalyst system supported on a particulate material comprising silica;
- c) withdrawing said recycle stream from the reactor;
- d) cooling said recycle stream to form a liquid and a gas phase;
- e) introducing into said recycle stream additional monomers to replace monomers polymerized to maintain said ratio of said recycle stream;
- f) reintroducing said liquid and gas phase into said reactor;
- and
- g) withdrawing said polymer product from said reactor.
In a gas fluidized bed polymerization process for polymerizing alpha-olefins comprising, passing a recycle stream comprising a monomer and at least one comonomer through a fluidized bed reactor, withdrawing a polymeric product and a recycle stream comprising unreacted monomers, introducing into said recycle stream additional monomers to replace monomers polymerized and withdrawn, compressing and cooling said recycle stream to form a gas and a liquid phase and reintroducing said gas phase and said liquid phase into said reactor, the improvement comprising:
- maintaining the recycle stream at a monomer concentration in the range of from about 10-20 to about 80-90 mole percent, employing a silica-supported catalyst system comprising a metallocene catalyst and as the cocatalyst alumoxane or an ionic activated complex and passing the recycle stream through a fluidized bed in said reactor wherein the recycle stream further comprises a dew point increasing component in an amount greater than 2.0 mole percent.
Dependencies are inferred from the claim text.