Process for polymerizing monomers in fluidized beds
AssigneeExxon Chemical Patents Inc.
InventorsJohn R. Griffin, Marc L. DeChellis, Michael E. Muhle
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Abstract
The invention is directed toward polymerizing or copolymerizing alpha-olefins either alone or in combination with one or more other alpha-olefins in the presence of a metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium such that the fluidizing medium entering the reactor comprises a gas and a liquid phase.
Claims55
A process for polymerizing alpha-olefin(s) in the presence of a supported metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium wherein the fluidizing medium serves to control the cooling capacity of said reactor, the process comprising employing in the fluidizing medium a level of liquid entering the reactor which is greater than 2 to 50 weight percent based on the total weight of the fluidizing medium wherein the bulk density function (Z) is maintained at a value equal to or greater than the calculated limit of the bulk density function.
A process for polymerizing alpha-olefin(s) in the presence of a supported metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium to produce a polymer product having a density in the range of 0.90 g/cc to about 0.939 g/cc, said process comprising operating said reactor such that the enthalpy change of said fluidizing medium entering and exiting the reactor is greater than about 35 Btu/lb, the fluidizing medium comprises a level of liquid entering the reactor which is greater than 2 to 50 weight percent based on the total weight of the fluidizing medium and wherein the bulk density function (Z) is maintained at a value equal to or greater than the calculated limit of the bulk density function.
A process for polymerizing alpha-olefin(s) in the presence of a supported metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium having a gas phase and a liquid phase entering the reactor, said process comprising:
- a) controlling the cooling capacity of said fluidizing medium by controlling the ratio of said gas phase to said liquid phase wherein the fluidizing medium comprises a level of liquid greater than 2 to 50 weight percent based on the total weight of the fluidizing medium;
- and
- b) maintaining the bulk density function (Z) at a value greater than or equal to the calculated limit of the bulk density function.
A continuous process for increasing reactor productivity of a gas phase polymerization reactor having a fluidizing medium and fluidized bed, said process comprising passing a gaseous stream comprising monomer through a reaction zone in the presence of a supported metallocene catalyst to produce a polymeric product, withdrawing said polymeric product, withdrawing said fluidizing medium comprising unreacted monomer from said reaction zone, mixing said fluidizing medium with hydrocarbon and polymerizable monomer(s) to form a liquid and a gas phase, and recycling said fluidizing medium to said reactor, the process comprising:
- a) introducing said hydrocarbon into said fluidizing medium to permit an increase in the cooling capacity of the fluidizing medium above 42 Btu/lb to 100 Btu/lb and wherein the fluidized medium comprises a level of liquid entering into the reactor which is greater than 2 to 50 weight percent based on the total weight of the fluidized medium;
- b) increasing the rate of withdrawal of polymer product to above at least about 500 lb/hr-ft.sup.2 ;
- c) calculating a bulk density function limit;
- and
- d) maintaining a bulk density function (Z) value greater than or equal to the calculated limit of the bulk density function.
A process for polymerizing alpha-olefin(s) in the presence of a supported metallocene catalyst in a gas phase reactor having a fluidized bed and a fluidizing medium for producing a polymer product having a density in the range from about greater than 0.900 g/cc to 0.970 g/cc, the process comprising operating said reactor such that the enthalpy change of said fluidizing medium entering and exiting the reactor is greater than about 35 Btu/lb, the fluidizing medium comprises a level of liquid entering the reactor which is greater than 2 to 50 weight percent based on the total weight of the fluidizing medium and wherein the bulk density function (Z) is maintained at a value equal to or greater than the calculated limit of the bulk density function.
A process for polymerizing alpha-olefin(s) in the presence of a supported metallocene catalyst in gas phase reactor having a fluidized bed and a fluidizing medium entering the reactor, the fluidizing medium having a gas phase and a liquid phase, said process comprising:
- a) controlling the cooling capacity of said fluidizing medium by controlling the ratio of said gas phase to said liquid phase wherein the fluidizing medium comprises a level of liquid greater than 2 to 50 weight percent based on the total weight of the fluidizing medium;
- b) calculating a bulk density function limit;
- c) monitoring a bulk density function (Z);
- and
- d) adjusting the bulk density function (Z) to maintain the bulk density function (Z) at a value greater than or equal to the calculated bulk density function limit.
Dependencies are inferred from the claim text.