Catalyst – solid sorbent – or support therefor: product or process – Forming or treating a sphere – process only – Forming other than by liquid immersion
Patent
1994-05-11
1995-11-21
Pal, Asok
Catalyst, solid sorbent, or support therefor: product or process
Forming or treating a sphere, process only
Forming other than by liquid immersion
502107, 502111, 502125, 502134, B01J 3508, B01J 3700
Patent
active
054686989
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for preparing a particulate carrier for an olefin polymerization procatalyst comprising a complex of an organic compound/transition metal compound as a carrier, in which method average 3.3 to 5.0 C.sub.2 H.sub.5 OH-molecules per each MgCl.sub.2 -molecule, into a chamber, wherein a particulate carrier is formed of it, and
BACKGROUND OF THE INVENTION
For the polymerization of olefins the Ziegler-Natta-catalyst system is generally used, which consists of a so-called procatalyst and a cocatalyst. The procatalyst is based on a compound of a transition metal belonging to any of the groups IV(A) to VIII(A) (Hubbard) of the periodical system of elements and the cocatalyst is based on an organometallic compound of a metal belonging to any of the groups I (A) to III (A) (Hubbard) of the periodical system of elements.
Nowadays, the procatalysts typically comprise an inert carrier, on which the actual active catalyst component i.e. the transition metal compound or the mixture of the complex formed by the catalytical compounds has been layered. The morphology and size distribution of the particles of such a carrier are most significant for the activity of the catalyst and the properties of the polymer obtained through the catalyst. With an active catalyst you are, namely, able to produce a polymer, from which, due to its purity, no catalyst residues need to be removed. The morphology of the carrier, again, influences the morphology of the polymer product itself for it has been noticed that the morphology of the catalyst is repeated in the structure of the polymer (the so-called replica phenomenon). When a flowing product polymer having the desired morphology and a narrow particular size distribution is wanted, which is desirable in view of the many aims of use of the processing processes, the properties of the carrier shall by the aid of the replica phenomenon be made similar.
Nowadays, the Ziegler-Natta type procatalysts typically comprise a magnesium based carrier, such as magnesium chloride, which has been treated with a transition metal compound of titanium halide, such as titanium tetrachloride, and sometimes also with an electron donor compound. It is also known that the carrier can be brought to an advantageous and equal-size crystal form by letting it crystallize as a complex from any of its crystal solvents.
The treatment of such a carrier with a crystal solvent has been disclosed among others in the U.S. Pat. No. 4,071,674, in which the procatalyst based on a transition metal compound has been prepared by bringing a titanium or vanadium compound to react with a reaction product that has been formed when magnesium dihalide and the addition product of alcohol are reacting with an organometallic compound of a metal of any of the groups I-III. The preparation of the procatalyst begins with the addition of alcohol dropwise to the suspension of magnesium dihalide, after which the organometallic compound is added dropwise to the reaction mixture. After agitation the preactivated carrier is activated by adding titanium tetrachloride to the mixture. The adding stages of this kind of a method are primitive and do not at all allow regulation of the morphology of the procatalyst in the way desired.
Treatment with a crystal solvent has also been described in patent application JP-59-215301. In this publication the carrier complex (10 g of MgCl.sub.2 and 24.2 g of EtOH) have been prepared by an emulsifying technique. The carrier complex melt has been dispersed into n-decane as spheroidal melt particles. Thereafter the carrier particles in the emulsion have been shock coagulated by transferring the emulsion into cold hydrocarbon medium. A drawback of this method is, among others, that such components are needed in the preparation of the carrier that are not useful at later stages of the catalyst preparation and this presupposes the existance of a purifying and recirculation equipment for this purpose.
The patent family comprising, among others, the EP publication
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Garoff Thomas
Koskinen Jukka
Borealis Holding A/S
Meeks Timothy H.
Pal Asok
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