Process for preparing polymerization catalyst carrier by spray c

Details Process for preparing polymerization catalyst carrier by spray c Process for preparing polymerization catalyst carrier by spray c

1993-11-18

1995-12-19

Pal, Asok

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Plural component system comprising a - group i to iv metal...

502156, B01J 3100

Patent

active

054768241

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a method for preparing a particulate carrier for an olefin polymerization procatalyst which comprises a transition metal compound reacted with the carrier, in which method: donor, n is 1 to 6, and m is 0 to 1, lower temperature than the melt, thereby distributing it in the form of atomized melt, and then solidifying to fine carrier particles and
2. Description of the Related Art
For the polymerization of olefins, the Ziegler-Natta catalyst system is commonly 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 IVA-VIII (Hubbard) of the Periodic Table of the elements. The cocatalyst is based on an organometallic compound of a metal belonging to any of the groups IA-IIIA (Hubbard) of the Periodic Table of the elements.
Currently, the procatalysts typically comprise an inert carrier, on which the actual active catalyst component, that is, the transition metal compound or the mixture or complex formed by catalytic compounds, is layered. The morphology, size and size distribution of the particles of the carrier influence significantly the properties of the polymer achieved by the catalyst. In fact, by an active catalyst a polymer can be produced, from which, thanks to its purity, no catalyst residues need to be removed.
The morphology and particle size of the carrier, on the other hand, affects the morphology of the polymer product itself, since it has been observed that the morphology of the catalyst is repeated in the structure of the polymer (the so-called replica phenomenon). If a flowable polymer product is desired, having a useful morphology and a narrow particle size distribution, which is desirable in view of the use of the polymer in subsequent many processes, the properties of the carrier shall, because of the replica phenomenon, be made similar to the desired polymer properties.
Currently, procatalysts of the Ziegler-Natta type typically comprise a magnesium-based carrier, such as a magnesium chloride, treated with a transition metal compound, such as a titanium halide, more particularly titanium tetrachloride, and sometimes also with an electron donor compound. It is also known that the carrier can be used in a preferred and equal-sized crystal form by allowing it to crystallize as a complex of any of its crystal solvents.
The patent family consisting of, among others, EP specification 65700 and U.S. Pat. No. 4,421,674 and which claims priority from the Italian application IT 2,188,181 (810521) relates to a method for preparing a catalyst which is particularly active in the polymerization of gaseous ethylene.
In this process, a titanium halide is reacted with a magnesium chloride catalyst carrier, in the form of microspheres, after which the reaction product particles are recovered by physical means and mixed with an organometallic cocatalyst compound.
These conventional methods generally require: ethanol, in an amount of 100 to 300 g of magnesium dichloride/1 of solution, whereby the water-content of the solution does not exceed 5% by weight; non-aqueous flow of nitrogen gas, the purity of which is at least 99.9% and the inlet temperature of which flow is between 180.degree. and 280.degree. C., whereby the nitrogen and the solution flows are simultaneously controlled so that the outlet temperature of the gaseous mixture is between 130.degree. and 210.degree. C., provided that the outlet temperature is at least 40.degree. C. lower than the inlet temperature and that the ethanol does not evaporate completely, whereby spheroidal magnesium dichloride particles are obtained; which is in vapor or liquid form and optionally diluted with an inert solvent to be evaporated; contain 0.7 to 12% by weight of titanium bound to the solid material; and compound, which is an alkylaluminum or an alkylaluminum halide.
This type of spray-drying method is based on a fairly complete drying of ethanol (C.sub.2 H.sub.5 OH) from the

REFERENCES:
Finnish Patent Application No. 870640, filed Feb. 16, 1987, cited in Official Action dated 24 Nov. 1994 in priority application.
Research Disclosure, Jun. 1982, abst. No. 21828, pp. 203-203, A. R. Blythe et al.: "Electrostatic spraying ".

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