Abstract: The present invention is a process for transitioning from a first polymerization catalyst system to a second polymerization catalyst system incompatible with the first polymerization catalyst system in a gas-phase reactor. The novel process comprises conducting a first polymerization reaction using a first polymerization catalyst system; stopping the first polymerization reaction; removing the contents of the first polymerization reaction from the reactor while maintaining a substantially closed system; then, in the substantially closed system, introducing a substantially contaminant free seedbed into the reactor; introducing a second feed system and a second catalyst system into the reactor; and conducting a second polymerization reaction.
Type:
Grant
Filed:
October 10, 2003
Date of Patent:
January 4, 2005
Assignee:
ExxonMobil Chemical Patents Inc.
Inventors:
Thomas Redden Veariel, George Varcelia Yenetchi, Sandy Clay Hinds, Diwalker Singh, Thierry Polchlopek
Abstract: The invention describes a method for decreasing the viscosity of crude oils and residuum utilizing a combination of thermal and acidic treatment. Further, the invention describes a method for making a water-in-oil emulsion, or a solids-stabilized water-in-oil emulsion with a reduced viscosity. The emulsion can be used in enhanced oil recovery methods, including using the emulsion as a drive fluid to displace hydrocarbons in a subterranean formation, and using the emulsion as a barrier fluid for diverting flow of fluids in the formation.
Abstract: The invention is directed to olefin polymerization processes using bridged hafnocene catalyst complexes comprising highly substituted noncoordinating anions that are surprisingly stable under high temperature olefin polymerization processes such that olefin copolymers having significant amount of incorporated comonomer can be prepared with high molecular weights. More specifically, the invention is a polymerization process for ethylene copolymers having a melt index of about 0.87 to about 0.930 comprising contacting, under homogeneous polymerization conditions at a reaction temperature at or above 140° C. to 225° C.
Type:
Grant
Filed:
July 10, 2001
Date of Patent:
May 6, 2003
Assignee:
ExxonMobil Chemical Patents Inc.
Inventors:
Donna J. Crowther, Bernard J. Folie, John F. Walzer, Jr., Rinaldo S. Schiffino