Process to Decrease or Eliminate Corrosion from the Decomposition of Halide Containing Olefin Cataysts (Chevron Phillips Chemical Company)

PATENT
Process to Decrease or Eliminate Corrosion from the Decomposition of Halide Containing Olefin Cataysts (Chevron Phillips Chemical Company)
Inventors:
Knudsen, Ronald D. (Bartlesville, OK, US)
Ewert, Warren M. (Bartlesville, OK, US)
Kreischer, Bruce E. (Kingwood, TX, US)
Application Number:
13/709523
Publication Date:
04/25/2013
Assignee:
Chevron Phillips Chemical Company LP (The Woodlands, TX, US)
Abstract:
A process is provided to inhibit or limit the decomposition of a halide-containing olefin oligomerization catalyst system during recovery of an oligomerization product. The process includes deactivation of an olefin oligomerization catalyst system present in an olefin oligomerization reactor effluent stream by contact with an alcohol under conditions that minimize potential for deactivated catalyst system decomposition. Such conditions include minimization of the water content of the deactivation agent and concentration of the deactivation agent.
FIELD OF THE INVENTION
This invention relates to a system of catalytic olefin preparation and recovery, deactivated catalyst recovery and diluent recycle. More specifically, the invention relates to methods of deactivating the catalyst in the effluent of the oligomerization reactor under conditions which prevent or decrease the formation of hydrogen halide acids during downstream processing and thereby prevent or decrease process equipment corrosion caused by such acids.
BACKGROUND OF THE INVENTION
Olefins, for example alpha-olefins, referred to as 1-olefins, have many uses. In addition to uses as specific chemicals, alpha-olefins are used in polymerization processes either as a monomer or a comonomer to prepare polyolefins, or polymers. Higher alpha-olefins and other olefins can be produced by contacting lower olefins, for example ethylene, with a catalyst, producing trimers of mono-olefins, dimers of diolefins, or other reaction products in an addition reaction. This reaction or addition of two or more olefins is generally referred to as oligomerization. Trimerization, which is the addition of three olefins, is a subset of the general class of oligomerization reactions. Often, the catalyst system is dispersed in a process solvent, and the reactants, a lower 1-olefin and optionally hydrogen, are fed in as gases. The reaction product or higher olefins dissolve in the process solvent as they are formed. Product olefins and catalyst are removed from the reactor in the process solvent containing them, i.e., in the oligomerization reactor effluent.
Unfortunately, during the production of olefins, a significant reaction co-product can be a polymeric material. Polymer production during the course of olefin preparation is detrimental to the process and reactor because polymer can build up on the interior walls or other portions of the reactor and inhibit heat transfer. Furthermore, any polymer produced needs to be separated from the olefin products stream, and/or a low molecular weight polymer can be formed causing a sticky, glue-like substance throughout the process and reactor.
To prevent polymer formation and potential buildup in that part of the process downstream of the oligomerization reactor resulting from active catalyst in the reactor effluent, systems to deactivate catalyst activity have been developed. In addition to prevention of polymer formation, deactivation of the catalyst system is important to prevent isomerization of the 1-olefin product to undesirable internal, i.e., 2- and higher, olefins, which lowers the product purity. Deactivation of the catalyst system also can remove hazards associated with the air- and water-sensitivity of aluminum alkyls.
There exists a need, therefore, for a deactivation process for use with halide-containing oligomerization catalyst systems, for example, metal halides such as alkylaluminum halide, which reduces or eliminates downstream corrosion.
SUMMARY OF THE INVENTION
In accordance with some embodiments of this invention, a process to inhibit or limit the decomposition of a halide-containing olefin oligomerization catalyst system during recovery of an oligomerization product is provided wherein the process includes the steps of forming an intermediate stream by contacting an olefin oligomerization reactor effluent stream which comprises olefin product(s), catalyst system, polymer(s) and/or oligomer(s) with an alcohol that is soluble in any portion of the reactor effluent stream, wherein the catalyst system comprises a chromium source, a pyrrole-containing compound and metal compound and wherein the alcohol is added in an amount to effect a mole alcohol to mole metal compound ratio between about 2.5 and about 1.5. In some embodiments of the invention, the amount of alcohol added to deactivate the catalyst system is greater than about 1.5 and less than about 2.5 moles per mole metal compound. In some embodiments of the invention, the alcohol is added in an amount to deactivate the catalyst system. In some embodiments of the invention, the amount of alcohol added to deactivate the catalyst system is greater than about 0.1 and less than about 2.5 moles per mole metal compound. In some embodiments of the invention, the amount of alcohol added to deactivate the catalyst system is greater than about 0.1 and less than about 2.0 moles per mole metal compound. In some embodiments of the invention, the amount of alcohol added to deactivate the catalyst system is greater than about 1.8 and less than about 2.2 moles per mole metal compound. In some embodiments of the invention, the amount of alcohol added to deactivate the catalyst system is greater than about 0.1 and less than about 2.2 moles per mole metal compound. In some embodiments, the metal compound is an alkylaluminum compound. In some embodiments, the number of moles of alcohol added to deactivate the catalyst system is based upon the number of moles of active metal alkyl units.
In other embodiments, the amount of alcohol added to deactivate the catalyst system is determined by the number of equivalents required to deactivate the catalyst. This equivalent ratio would be referred to as one equivalent of alcohol per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.1 and less than about 1.8 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.1 and less than about 1.2 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.1 and less than about 1.0 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.1 and less than about 0.8 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.1 and less than about 0.5 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.6 and less than about 1.8 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be greater than about 0.8 and less than about 1.2 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be less than about 1.8 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be less than about 1.2 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be less than about 1.0 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be less than about 0.8 equivalents per equivalent of active metal alkyl unit. In yet other embodiments, the amount of alcohol added to deactivate the catalyst system may be less than about 0.5 equivalents per equivalent of active metal alkyl unit. In some embodiments, the active metal alkyl unit is an alkylaluminum unit.
In some embodiments of the invention, the process to inhibit or limit the decomposition of a halide-containing olefin oligomerization catalyst system during recovery of an oligomerization product optionally includes the step of separating an intermediate stream into at least one product stream comprising olefin oligomerization product and at least one heavies stream.
In some embodiments of the invention, the olefin oligomerization catalyst system comprises a halogenated alkylaluminum or a mixture of a halogenated alkylaluminum and an alkylaluminum. In another embodiment of the invention, the olefin oligomerization catalyst system comprises a halide compound and a metal alkyl compound, such as an alkylaluminum compound.
In some embodiments of the invention, the alcohol has a boiling point different from the olefin product in the reactor effluent stream, e.g. does not form an azeotrope with the olefin product. In some embodiments of the invention, the alcohol is selected from the group of 1-hexanol, 3-hexanol, 2-ethyl-1-hexanol, 3-octanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 2-methyl-3-heptanol, 1-octanol, 2-octanol, 4-octanol, 7-methyl-2-decanol, 1-decanol, 2-decanol, 3-decanol, 4-decanol, 5-decanol, 2-ethyl-1-decanol, and mixtures thereof.
In some embodiments of the invention, the alcohol is treated to minimize water content. In yet other embodiments of the invention, the water content of the alcohol is minimized before the formation of an intermediate stream.
In some embodiments of the invention, the separation of at least one olefin oligomerization product stream and at least one heavies stream is accomplished by distillation at a temperature less than or equal to about 200° C.
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