Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
2002-07-15
2004-08-24
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
Reexamination Certificate
active
06780808
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable.
FEDERALLY SPONSORED RESEARCH
Not Applicable.
REFERENCE TO MICROFICHE APPENDIX
Not Applicable.
FIELD OF THE INVENTION
This invention relates to magnesium halide compositions, catalysts made therefrom, methods of increasing the solubility of magnesium halides, methods of making magnesium halide compositions and catalysts, as well as methods of polymerization.
BACKGROUND OF THE INVENTION
Solutions of MgCl
2
in various electron donor solvents have found use in industry for the preparation of olefin polymerization catalysts. Often these solutions employ ethers, ketones and esters to form Mg—Ti catalyst precursors that have found wide acceptance in the catalysis of olefin polymerizations. Known precursors have resulted from the dissolution of magnesium chloride and titanium chloride in the solvent, followed by evaporation or distillation of the excess solvent. Tetrahydrofuran (TMF) has proven an especially useful solvent due to its coordinating properties with both MgCl
2
and TiCl
x
and its relatively low boiling point, which facilitates evaporation and solvent recovery. The resulting dried catalyst precursor is treated with a cocatalyst, typically an aluminum alkyl compound, to generate the composition which is active in olefin polymerization.
The use of such catalyst precursors in industrial polymerization processes exploit the solubility of MgCl
2
in the solvent. Alkaline-earth halides are typically insoluble in hydrocarbon solvents However the solubility in certain coordinating electron donor solvents can be suitably high for industrial applications For instance, the solubility of MgCl
2
in tetrahydrofuran (THF) increases from ca 0.2 M at −25° C. to about 0.7 M at 30° C. The amount of precursor that is obtainable per batch preparation of precursor is limited by the solubility of MgCl
2
.
Interestingly, however, at higher temperatures, the solubility of MgCl
2
in such donor solvents decreases. For example, at the boiling point of THF (65° C.) the solubility of MgCl
2
is only about 0.4 M at atmospheric pressure. Such a reduction in solubility complicates the precursor drying process because removal of the solvent by heating is typically performed most effectively near the boiling point of the solvent. To avoid reducing the concentration of MgCl
2
in the precursor solution to undesirable levels, the drying process is performed at reduced temperatures and pressures. Unfortunately, removal of the solvent under these conditions requires more time and is less effective, thereby reducing batch throughput.
The reduced solubility of MgCl
2
at higher temperatures also causes the formation of a thick crust of precipitated MgCl
2
on reactor walls and piping when solubility limits are exceeded at such temperatures.
For these reasons, catalyst precursor systems with improved solubility would find use in polymerization processes. Also, methods of increasing the solubility and changing the solubility profile of MgCl
2
as a function of temperature would be useful. Therefore, magnesium halide catalyst components having higher solubility or a solubility that does not decrease with temperature and processes employing such catalyst components and catalysts made therefrom would be useful.
SUMMARY OF THE INVENTION
In some embodiments, there is provided a method for increasing the solubility of a magnesium halide, comprising 1) providing an electron donor solvent; contacting a magnesium halide with the electron donor solvent, and 2) providing an electron donor compound to form a magnesium-halide composition, wherein the composition is characterized by a solubility of the magnesium halide in the solvent that does not decrease as a function of the temperature up to the boiling point of the solvent
In other embodiments, a polymerization catalyst component comprising a magnesium halide, an electron donor solvent, and an electron donor compound, wherein the composition is characterized by a solubility in the electron donor solvent that does not decrease as a function of the temperature up to the boiling point of the electron donor solvent is provided.
In still other embodiments, a method of making a catalyst is disclosed In such embodiments, the method comprises forming a magnesium-containing composition, contacting the magnesium-containing composition with a transition metal compound to form a catalyst precursor, and contacting the catalyst precursor with a cocatalyst. The magnesium-containing composition includes a magnesium halide, an electron donor solvent, and an electron donor compound and is characterized by a solubility in the electron donor solvent that does not decrease as a function of the temperature up to the boiling point of the electron donor solvent.
Still other embodiments provide methods of making a polymer, comprising reacting at least one olefin monomer in the presence of a catalyst comprising the reaction product of: a magnesium-containing composition that includes a magnesium halide, an electron donor solvent, and an electron donor compound. The magnesium-containing composition is characterized by a solubility in the electron donor solvent that does not decrease as a function of the temperature up to the boiling point of the electron donor solvent. The catalyst composition also includes a transition metal compound, wherein the transition metal is selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, and combinations thereof, and a cocatalyst composition.
In some embodiments described above, compositions are substantially free of other electron donor compounds, and the molar ratio of the electron donor compound to magnesium halide is less than or equal to 1.9. In some embodiments, the ratio of the electron donor compound to magnesium halide is less than about 1.75, while in others the ratio of the electron donor compound to magnesium halide ranges from about 0.1 to less than about 0.5.
In some methods, catalyst precursors, catalyst components, and catalysts described herein, the magnesium halide is magnesium chloride, magnesium bromide, magnesium iodide, or combinations thereof. The electron donor compound may be a linear, branched, substituted, or unsubstituted aliphatic or aromatic alcohol having between one and about 25 carbon atoms. Exemplary alcohols include methanol, ethanol, propanol, isopropanol, butanol, 2-ethyl hexanol, 1-dodecanol, cyclohexanol, and di-tert-butyl phenol.
The solvent may be selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers, and aliphatic ketones. In some embodiments, the solvent is selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, ethers, and aliphatic ketones. Exemplary alkyl esters suitable as solvents include methyl acetate, ethyl acetate, ethyl propionate, methyl propionate, ethyl benzoate, and combinations thereof. Ethers that are suitable for use as the solvent include, but are not limited to, diethyl ether, diusopropyl ether, di-n-butyl ether, ethylisopropyl ether, methylbutyl ether, methylallyl ether, ethylvinyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran and combinations thereof Suitable ketones include acetone, methylethyl ketone, cyclohexanone, cyclopentylmethyl ketone, 3-bromo-4-heptanone, 2-chlorocyclo-pentanone, allylmethyl ketone, and combinations thereof Of course, mixed solvents containing a second electron donor solvent that is an alkyl ester of an aliphatic or aromatic carboxylic acid, an aliphatic or cyclic ether, or an aliphatic ketone may be used in some embodiments. In some embodiments described herein, the solubility of a magnesium halide composition in solvent is greater than about 0.7 mol/liter.
In particular embodiments, the magnesium halide is magnesium chloride, the alcohol is ethanol or isopropanol, the molar ratio of the alcohol to magnesium is about 0.1 to about 1.1, the solubility of the magnesium halide or magnesium halide composition in the solvent is between about 0.8 and 2.5 mol MgCl
2
Hepburn Cynthia Anne
Jorgensen Robert James
Wagner Burkhard Eric
Bell Mark L.
Brown Jennine M.
McKinney Osborne K.
Univation Technologies LLC
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