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
2001-02-01
2004-03-16
Choi, Ling-Siu (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S103000, C502S115000, C526S348000, C526S124300, C526S123100, C526S142000
Reexamination Certificate
active
06706655
ABSTRACT:
The invention relates to a process for the preparation of an olefin polymerization catalyst component comprising a magnesium dihalide, a titanium tetrahalide, and a dicarboxylic acid di-, oligo- and/or polyester as internal electron donor. The invention also relates to such a catalyst component and its use for the polymerization of &agr;-olefins such as propene.
BACKGROUND OF THE INVENTION
Generally, so called Ziegler-Natta catalyst components of the above kind have been prepared by reacting a magnesium halide-alcohol complex support with a titanium tetrahalide and an electron donor which usually is a phthalic acid di-, oligo- or polyester. The preparation involves the use of large amounts of reagents and washing liquids, which are difficult to handle. Additionally, byproducts are formed, which cannot easily be regenerated or destroyed, but form an environmental problem.
For example, the preparation of a conventional polypropene catalyst component involves the reaction of a magnesium dichloride-alcohol complex support with titanium tetrachloride to give a reactive &bgr;-magnesium dichloride surface as intermediate and hydrogen chloride and titanium alkoxy trichloride as byproducts. Then, the reactive &bgr;-magnesium dichloride surface is activated with further titanium tetrachloride to give said catalyst component (the treatment with a titanium halide such as titanium tetrachloride is henceforth called titanation). This gives an inert magnesium chloride-based support covered with active sites based on titanium, chlorine and, optionally, an internal electron donor.
The titanium alkoxy trichloride byproduct formed in said titanation is a catalyst poison and must be carefully removed by extensive washing using large amounts of titanium tetrachloride. Further, the titanium alkoxy trichloride must be carefully separated from the titanium tetrachloride washing liquid, if the latter is to be reused e.g. for activating the reactive &bgr;-magnesium dichloride. Finally, the titanium alkoxy trichloride is a hazardous waste material, which is difficult to dispose of.
Thus, in a typical propene polymerization catalyst component preparation involving two titanations and three heptane washes, one mol of produced catalyst component (mol Mg) requires about 40 mol of titanium tetrachloride e.g. as washing liquid to be circulated, and produces as waste material an amount of about three mol of titanium alkoxy trichloride as well as about three mol of hydrogen chloride.
Sumitomo, EP 0 748 820 A1 (hereinafter referred to as “Sumitomo”), has prepared dialkoxy magnesium, reacted it with titanium tetrachloride to form an intermediate and then reacted the intermediate with phthalic acid dichloride to form a catalytically active propene polymerization catalyst component. The activity was raised by repeated titanations, as well as repeated washes with toluene and hexane. See page 10, lines 14 to 37, of said publication.
Said process of Sumitomo has avoided the reaction between the solid magnesium dichloride-alcohol complex and liquid titanium tetrachloride, and thereby eliminated the formation of large quantities of catalytically poisonous titanium alkoxy trichloride byproduct. However, as much as four titanations and hydrocarbon treatments are still needed to give satisfactory catalytic activity.
Further, conventional processes based on titanium trichloride and on titanium tetrachloride covered magnesium dichloride give catalyst component particles of either the wrong size or too broad a particle size distribution. As the relative size and size distribution of the catalyst component particles are reproduced in the olefin polymer (the so called “replication”-phenomena), this is reflected as morphology problems in the polymer product. Such problems are, e.g., fouling of the polymerization reactor and clogging of its piping due to the presence of too much fines.
DESCRIPTION OF THE INVENTION
The purpose of the present invention is to provide a process which results in a catalyst component having satisfactory activity without producing harmful byproducts such as said titanium alkoxy trichloride or requiring the use of large amounts of titanation reagent and/or washing liquid. A further purpose of the invention is to obtain a catalyst component which has the right particle size and size distribution, so that a suitable polymer will be obtained without disturbances in the polymerization process.
The problem described above has now been solved with a novel process for the preparation of a catalyst component of the above type, which is mainly characterized by the steps of:
(i) reacting in solution at least one magnesium compound (a), selected from the group consisting of a dialkyl magnesium R
2
Mg, an alkyl magnesium alkoxide RMgOR, wherein each R is a similar or different C
1
-C
20
alkyl, and a magnesium dihalide MgX
2
, wherein X is a halogen, with at least one alcohol (b), selected from the group consisting of a mixture of at least one monohydric alcohol R′OH and at least one polyhydric alcohol R′(OH)
m
, and at least one polyhydric alcohol R′(OH)
m
, wherein R′ is an 1-valent or, respectively, an m-valent C
1
-C
20
hydrocarbyl group and m is an integer selected from 2, 3, 4, 5 and 6, to give a first intermediate (ab), and
(ii) reacting in solution said first intermediate (ab) with at least one dicarboxylic acid dihalide (c) which forms essentially all of said carboxylic acid di-, oligo- and/or polyester and has the formula (1):
wherein each R″ is a similar or different C
1
-C
20
hydrocarbyl group or both R″:s form together with the two unsaturated carbons of the formula a C
5
-C
20
aliphatic or aromatic ring, and X′ is a halogen, to give a second intermediate (abc), and
(iii) reacting said second intermediate (abc) with at least one titanium tetrahalide TiX″
4
(d) wherein X″ is a halogen,
(iv) recovering by precipitation said catalyst component in crude form, or a precursor of said catalyst component, and
(v) optionally washing said crude catalyst component or said precursor, to give said catalyst component.
It has thus been found that a high activity olefin polymerization catalyst comprising a magnesium halide, a titanium tetrahalide and a dicarboxylic acid di-, oligo- and/or polyester as internal donor can be prepared without the above mentioned disadvantages by reacting the reaction product of a dialkyl magnesium or a magnesium halide and a polyhydric alcohol with a dicarboxylic acid dihalide and a titanium tetrahalide. Further, by means of the polyhydric alcohol, the morphology of the catalyst component and thus the morphology of the polymer can be controlled and improved.
Of the above mentioned steps (i) to (iii), preferably all are performed in solution. If necessary, one or several hydrocarbon solvents, optionally with the application of stirring and/or heating, can be used to dissolve the reactants. Performing the process in a solution means that all reagent molecules have access to, and can react with, each other, thus forming a homogenous reaction product. Earlier processes which have been performed by reacting a solid support with a titanium compound and an electron donor, do not form this kind of homogenous reaction products. See the above description of earlier technique.
The catalyst component is in step (iv) preferably recovered in solid form by precipitation. Precipitation in the present invention means that the reaction product formed in solution is recovered as a powder, the particles of which comprise similar individual molecules of that reaction product. It is thus distinguished from earlier processes which include first the precipitation of a support and then the reaction of the support surface with catalytically active component(s). The particles formed according to the present invention are thus homogenous, while the particles of earlier processes are more or less heterogenous (inert core+active surface).
It is preferable if said first and second intermediates as well as the final product of the claimed process are
Ala-Huikku Sirpa
Garoff Thomas
Leinonen Timo
Birch & Stewart Kolasch & Birch, LLP
Borealis Technology Oy
Choi Ling-Siu
LandOfFree
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