CA2033964A1 - Process for the preparation of spherical particles of magnesium alkoxide - Google Patents
Process for the preparation of spherical particles of magnesium alkoxideInfo
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- CA2033964A1 CA2033964A1 CA002033964A CA2033964A CA2033964A1 CA 2033964 A1 CA2033964 A1 CA 2033964A1 CA 002033964 A CA002033964 A CA 002033964A CA 2033964 A CA2033964 A CA 2033964A CA 2033964 A1 CA2033964 A1 CA 2033964A1
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- Prior art keywords
- magnesium alkoxide
- process according
- preparation
- finely divided
- catalyst
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F3/00—Compounds containing elements of Groups 2 or 12 of the Periodic System
- C07F3/02—Magnesium compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/68—Preparation of metal alcoholates
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT
A process for the preparation of finely divided, spherical magnesium alkoxide is disclosed. The product is prepared by spray drying of an alcoholic solution of the corresponding carboxylated magnesium alkoxide and subsequent drying and decarboxylation of the resulting finely divided carboxylated magnesium alkoxide. The solution is sprayed via a two-material nozzle with inner atomization, which is operated in the part-load range at 10 to 30% of its capacity into an inert accompanying gas which is under a pressure of 1.0 to 1.2 bar, has been preheated to 100-140°C and if fed concurrently. The magnesium alkoxide so prepared is used for the preparation of a catalyst for the polymerization of .alpha.-olefins. Polypropylene prepared using such a catalyst has a high stereospecificity and a high bulk density.
A process for the preparation of finely divided, spherical magnesium alkoxide is disclosed. The product is prepared by spray drying of an alcoholic solution of the corresponding carboxylated magnesium alkoxide and subsequent drying and decarboxylation of the resulting finely divided carboxylated magnesium alkoxide. The solution is sprayed via a two-material nozzle with inner atomization, which is operated in the part-load range at 10 to 30% of its capacity into an inert accompanying gas which is under a pressure of 1.0 to 1.2 bar, has been preheated to 100-140°C and if fed concurrently. The magnesium alkoxide so prepared is used for the preparation of a catalyst for the polymerization of .alpha.-olefins. Polypropylene prepared using such a catalyst has a high stereospecificity and a high bulk density.
Description
~033964 Process for the preparation of spherical particles of magnesium alkoxide The present invention relates to finely divided, spher-ical magnesium alkoxide, a process for its preparation and its use for the preparation of highly active catalysts for the polymeriza-tion of ~-olefins.
Catalysts for olefin polymerization can be prepared by many processes, by reacting a solid component, which, as a rule, contains magnesium, titanium and a halogen, preferably chlorine, with an organoaluminium compound. The activity and the stereospecificity of such supported catalysts are usually improved by incorporating an electron donor (Lewis base) in the carrier component and by complexing the organoaluminium compound with a further electron donor. It is known that magnesium alkoxides can be used as starting materials for the preparation of such supported catalysts. In this case, the magnesium alkoxide particles are preferably halogenated with the aid of a suitable halogenating agent, such as benzoyl chloride, thionyl chloride or titanium tetrachloride, in the presence of an electron donor, such as, for example, ethyl benzoate. If halogenating agents other than titanium tetrachloride are initially used, the latter must be incorporated in the solid component in the required amount by subsequent reaction with titanium tetrachloride, a content of 2 to 4.5% by weight of titanium usually being required. Regarding the details of the catalyst preparation, reference may be made to ~uropean Published Patent Applications 0,216,402 and 0,236,082 and ~033~4 to the literature cited there.
Since, in the polymerization of ~-olefins, the mor-phology of the resulting polymer particles is a faithful reproduc-tion of the morphology of the catalyst and this in turn is an exact image of that of the magnesium alkoxide used (see for example J. Rudolph and J. Gross, Die Angewandte Makromolekulare Chemie _ (1974), 195-197), it is also necessary to use a magnes-ium alkoxide of defined morphology to achieve defined properties of the desired polymer.
European Published Patent Application 0,236,082 des-cribes the preparation of spherical to raisin-shaped particles of magnesium alkoxides by conventional spray-drying. A preEerably alcoholic solution of a carboxylated magnesium alkoxide is sprayed through a nozzle, which is not defined in detail, or via a rota-ting disk into a hot accompanying gas; this accompanying gas can be fed concurrent or countercurrent. Although temperatures of 40 to 120C may be used, the range from 50 to 90C is preferred for ethanolic solutions since it is only in this range that the desired spherical to raisin-shaped particles can be produced. As is evident from the Examples, on the other hand, hollow spheres are obtained at 100-120UC, many of which disintegrate into nutshell-like fragments.
Virtually all of the particles obtained by the process of European Published Patent Application 0,236,082 have a diameter in the range of from 2 to 250 ~m; preferably, 90% b~ weight of the particles are in the range from 10 to 40~lm, with a weight average at about 20 ~m~
2~3396~
Catalysts for olefin polymerization can be prepared by many processes, by reacting a solid component, which, as a rule, contains magnesium, titanium and a halogen, preferably chlorine, with an organoaluminium compound. The activity and the stereospecificity of such supported catalysts are usually improved by incorporating an electron donor (Lewis base) in the carrier component and by complexing the organoaluminium compound with a further electron donor. It is known that magnesium alkoxides can be used as starting materials for the preparation of such supported catalysts. In this case, the magnesium alkoxide particles are preferably halogenated with the aid of a suitable halogenating agent, such as benzoyl chloride, thionyl chloride or titanium tetrachloride, in the presence of an electron donor, such as, for example, ethyl benzoate. If halogenating agents other than titanium tetrachloride are initially used, the latter must be incorporated in the solid component in the required amount by subsequent reaction with titanium tetrachloride, a content of 2 to 4.5% by weight of titanium usually being required. Regarding the details of the catalyst preparation, reference may be made to ~uropean Published Patent Applications 0,216,402 and 0,236,082 and ~033~4 to the literature cited there.
Since, in the polymerization of ~-olefins, the mor-phology of the resulting polymer particles is a faithful reproduc-tion of the morphology of the catalyst and this in turn is an exact image of that of the magnesium alkoxide used (see for example J. Rudolph and J. Gross, Die Angewandte Makromolekulare Chemie _ (1974), 195-197), it is also necessary to use a magnes-ium alkoxide of defined morphology to achieve defined properties of the desired polymer.
European Published Patent Application 0,236,082 des-cribes the preparation of spherical to raisin-shaped particles of magnesium alkoxides by conventional spray-drying. A preEerably alcoholic solution of a carboxylated magnesium alkoxide is sprayed through a nozzle, which is not defined in detail, or via a rota-ting disk into a hot accompanying gas; this accompanying gas can be fed concurrent or countercurrent. Although temperatures of 40 to 120C may be used, the range from 50 to 90C is preferred for ethanolic solutions since it is only in this range that the desired spherical to raisin-shaped particles can be produced. As is evident from the Examples, on the other hand, hollow spheres are obtained at 100-120UC, many of which disintegrate into nutshell-like fragments.
Virtually all of the particles obtained by the process of European Published Patent Application 0,236,082 have a diameter in the range of from 2 to 250 ~m; preferably, 90% b~ weight of the particles are in the range from 10 to 40~lm, with a weight average at about 20 ~m~
2~3396~
After spray drying, the bound CO2 is expelled again by heating for several days in a stream of nitrogen at temperatures of, initially, 70C to, finally, 150C. As an alternative to this expensive process, the carboxylated magnesium alkoxide obtained is said to be capable of being directly reacted further. The cata-lyst obtained is said to be capable of being used both for gas-phase polymerization and for liquid-phase polymerization.
The process described in European Published Patent Application 0,236,082 for the preparation of spherical particles 10 of magnesium alkoxide is unsatisfactory for several reasons:
- The preparation of more finely divided magnesium alkoxide having a mean diameter of less than 10 ~m, as is desirable especially for the preparation of catalysts for the liquid-phase polymerization, is not possible by this method.
- The relatively low drying temperature during spray dry-ing leads to products which have a considerable residual moisture content, with the danger of agglomeration and caking on the walls.
- An inconvenient aftertreatment is required to remove the bound CO2. Alternatively, it is possible to dispense with this aftertreatment, but this gives a catalyst hav-ing substantially lower activity.
European Published Patent Application 0,216,402 des-cribe~ a multistage process for the preparation of spherical, mixed maqnesium alkoxide of the formula Mq(OR)2-a(OR')a (a = 9 to 0.5~ In the preferred case (R = C2Hs; R' = CH3), ~03396~
The process described in European Published Patent Application 0,236,082 for the preparation of spherical particles 10 of magnesium alkoxide is unsatisfactory for several reasons:
- The preparation of more finely divided magnesium alkoxide having a mean diameter of less than 10 ~m, as is desirable especially for the preparation of catalysts for the liquid-phase polymerization, is not possible by this method.
- The relatively low drying temperature during spray dry-ing leads to products which have a considerable residual moisture content, with the danger of agglomeration and caking on the walls.
- An inconvenient aftertreatment is required to remove the bound CO2. Alternatively, it is possible to dispense with this aftertreatment, but this gives a catalyst hav-ing substantially lower activity.
European Published Patent Application 0,216,402 des-cribe~ a multistage process for the preparation of spherical, mixed maqnesium alkoxide of the formula Mq(OR)2-a(OR')a (a = 9 to 0.5~ In the preferred case (R = C2Hs; R' = CH3), ~03396~
- 4 - 23443-44h the foll~winq procedure is ~dopted:
1) An ethanolic suspension of magnesium ethoxide is pre-pared from magnesium and ethanol; the product is iso-lated and dried.
2) The dried magnesium ethoxide is dissolved in methanol, the solution is spray-dried at 15 to 200C, preferably at 30 to 70C, spherical particles having a diameter of from 5 t~ 30 ~m, preferably lO to 18~m, being formed.
At this point, a mixed alkoxide predominantly containing methoxide groups is present; it is unsuitable in this form for the preparation of olefin polymerization catalysts~
3) The product from 2) is suspended in ethanol, and the methanol formed at the equilibrium is distilled off.
4) The product having a low content of methoxide groups is isolated and dried.
Apart from the many process stages, such as, for example, changing the solvent twice and drying three times, the low solubility of the magnesium ethoxide in methanol (see European Published Patent Application 0,216,402, Example 1) and the resulting necessity to evaporate large amounts of solvent with corresponding consumption of energy, are found to be a serious disadvantage. Furthermore, the product still has a residual content of undesirable methoxide groups.
The primary aim of the present invention is to provide finely divided, spherical magnesium alkoxide for the preparation of a catalyst for the ~olymeri~ation of ~-olefins, which permits 2033~64 the production of polyolefins, in particular polypropylene, with high stereospecificity, high bulk density and good fluidizability during pneumatic conveying. The polymer should have as low an ash content as possible even without extraction and must not contain any fish eyes during processing.
Owing to the known dependence of the polyolefin mor-phology on that of the polymerization catalyst and hence on the morphology of the magnesium alkoxide used, it was necessary to provide a process which permits the preparation of spherical, com-pact particles of magnesium alkoxide having a relatively narrowparticle size distribution and a weight average of the particle diameter of less than 10 ~m. In particular, in order to ensure freedom from fish eyes and good fluidizability, no significant amounts having diameters greater than about 100~ m must be pre-sent. This necessitates measures to ensure effective atomization on the one hand and to prevent agglomeration of still moist particles in the gas space or on the wall on the other hand.
Previously unobtainable finely divided magnesium alkox-ide free of methoxide groups and prepared in this manner can be particularly advantageously used for the preparation of catalysts for liquid-phase polymerization.
In addition to the liquid-phase polymerization of ole-fins, gas-phase polymerization processes in which the polymeriza-tion takes place in, for example, a fluidized bed have become es-tablished worldwide. A catalyst having coarser particles is required for this purpose; mean particle diameters of, for example, 20 ~m are typical~ A further object of the present 20339~
1) An ethanolic suspension of magnesium ethoxide is pre-pared from magnesium and ethanol; the product is iso-lated and dried.
2) The dried magnesium ethoxide is dissolved in methanol, the solution is spray-dried at 15 to 200C, preferably at 30 to 70C, spherical particles having a diameter of from 5 t~ 30 ~m, preferably lO to 18~m, being formed.
At this point, a mixed alkoxide predominantly containing methoxide groups is present; it is unsuitable in this form for the preparation of olefin polymerization catalysts~
3) The product from 2) is suspended in ethanol, and the methanol formed at the equilibrium is distilled off.
4) The product having a low content of methoxide groups is isolated and dried.
Apart from the many process stages, such as, for example, changing the solvent twice and drying three times, the low solubility of the magnesium ethoxide in methanol (see European Published Patent Application 0,216,402, Example 1) and the resulting necessity to evaporate large amounts of solvent with corresponding consumption of energy, are found to be a serious disadvantage. Furthermore, the product still has a residual content of undesirable methoxide groups.
The primary aim of the present invention is to provide finely divided, spherical magnesium alkoxide for the preparation of a catalyst for the ~olymeri~ation of ~-olefins, which permits 2033~64 the production of polyolefins, in particular polypropylene, with high stereospecificity, high bulk density and good fluidizability during pneumatic conveying. The polymer should have as low an ash content as possible even without extraction and must not contain any fish eyes during processing.
Owing to the known dependence of the polyolefin mor-phology on that of the polymerization catalyst and hence on the morphology of the magnesium alkoxide used, it was necessary to provide a process which permits the preparation of spherical, com-pact particles of magnesium alkoxide having a relatively narrowparticle size distribution and a weight average of the particle diameter of less than 10 ~m. In particular, in order to ensure freedom from fish eyes and good fluidizability, no significant amounts having diameters greater than about 100~ m must be pre-sent. This necessitates measures to ensure effective atomization on the one hand and to prevent agglomeration of still moist particles in the gas space or on the wall on the other hand.
Previously unobtainable finely divided magnesium alkox-ide free of methoxide groups and prepared in this manner can be particularly advantageously used for the preparation of catalysts for liquid-phase polymerization.
In addition to the liquid-phase polymerization of ole-fins, gas-phase polymerization processes in which the polymeriza-tion takes place in, for example, a fluidized bed have become es-tablished worldwide. A catalyst having coarser particles is required for this purpose; mean particle diameters of, for example, 20 ~m are typical~ A further object of the present 20339~
invention is therefore to provide a flexible process in which alternatively the finely divided magnesium alkoxide according to the invention, having a weight average particle diameter of less than 10 ~m, or a magnesium alkoxide having coarser particles and a weight average of 20 ~m or more can be prepared in the same plant without conversion, merely by suitable variation of parameters, such as, for example, load range of the nozzle. Such flexibility of the plant could contribute substantially to its cost-efficiency.
Furthermore, it was intended to find a simple and rapid process for final drying and decarboxylation of the initially formed finely divided carboxylated magnesium alkoxide.
These objects are achieved in the present invention by the process described below.
The process according to the invention is characterized in that a solution of carboxylated magnesium alkoxide in the same alcohol on which the alkoxide is also based a) is sprayed via a two-material nozzle with inner atomiza-tion of the type described in, for example, German Patent 2,627,880, and which is operated in the part-load range at 5 to 30~, preferably 10 to 25%, of capacity, b) into an inert accompanying gas which is under a pressure of 1.0 to 1.2 bar, preferably 1.01 to 1.05 bar, is fed concurrent and has been preheated to a relatively high temperature of 100 to 140C, preferably 105 to 120C, it being advantageous if the spray drier is in the form of ~03~
Furthermore, it was intended to find a simple and rapid process for final drying and decarboxylation of the initially formed finely divided carboxylated magnesium alkoxide.
These objects are achieved in the present invention by the process described below.
The process according to the invention is characterized in that a solution of carboxylated magnesium alkoxide in the same alcohol on which the alkoxide is also based a) is sprayed via a two-material nozzle with inner atomiza-tion of the type described in, for example, German Patent 2,627,880, and which is operated in the part-load range at 5 to 30~, preferably 10 to 25%, of capacity, b) into an inert accompanying gas which is under a pressure of 1.0 to 1.2 bar, preferably 1.01 to 1.05 bar, is fed concurrent and has been preheated to a relatively high temperature of 100 to 140C, preferably 105 to 120C, it being advantageous if the spray drier is in the form of ~03~
a long tube tapering conically downwards, c) after which the resulting finely divided carboxylated magnesium alkoxide is dried and is decarboxylated.
The carboxylated magnesium alkoxide used has the formula Mg(OR)2 x C2 where R = C2 to C4, such as, for example, n-propyl, n-butyl, isobutyl or preferably ethyl and x = 0.2 to 2Ø It is prepared in a known manner by dissolving magnesium turnings in the corre-sponding alcohol and redissolving the initially formed particles of magnesium alkoxide by passing in dry CO2. Here, the C02 is merely an auxiliary for increasing the solubility of the alkoxide;
its reaction with the alkoxide is reversible, and it can therefore be removed again by heating. The larger x, the easier CO2 is released again on heating; it is advisable here to choose x to be only as large as is absolutely necessary, in order to avoid exces-sive C02 contamination of the accompanying gas, which is circu-lated after the alcohol has been condensed out. Where R = ethyl, a value for x of 1.0 to 1.25 is therefore particularly preferred.
The solution may have a solids content of 2 to 40% by weight. Concentrations between 20 and 40% by weight, particularly preferably 25 to 30% by weight, based on dry substance, are usually used.
The nozzle used is a two-material nozzle with inner atomization. Liquid pressure and gas pressure must be the same.
Spraying is carried out at pressures between 10 and ~0 bar, preferably between 35 and 45 bar.
20339~
The carboxylated magnesium alkoxide used has the formula Mg(OR)2 x C2 where R = C2 to C4, such as, for example, n-propyl, n-butyl, isobutyl or preferably ethyl and x = 0.2 to 2Ø It is prepared in a known manner by dissolving magnesium turnings in the corre-sponding alcohol and redissolving the initially formed particles of magnesium alkoxide by passing in dry CO2. Here, the C02 is merely an auxiliary for increasing the solubility of the alkoxide;
its reaction with the alkoxide is reversible, and it can therefore be removed again by heating. The larger x, the easier CO2 is released again on heating; it is advisable here to choose x to be only as large as is absolutely necessary, in order to avoid exces-sive C02 contamination of the accompanying gas, which is circu-lated after the alcohol has been condensed out. Where R = ethyl, a value for x of 1.0 to 1.25 is therefore particularly preferred.
The solution may have a solids content of 2 to 40% by weight. Concentrations between 20 and 40% by weight, particularly preferably 25 to 30% by weight, based on dry substance, are usually used.
The nozzle used is a two-material nozzle with inner atomization. Liquid pressure and gas pressure must be the same.
Spraying is carried out at pressures between 10 and ~0 bar, preferably between 35 and 45 bar.
20339~
Any inert gas may be used as the propellant and as the accompanying gas. For practical reasons, dry and oxygen-free nitrogen is used. When carboxylated magnesium ethoxide in ethanol is used, the temperature of the accompanying gas is particularly preferably between 105 and 115C.
Under these conditions, single-material nozzles give particles which are too coarse. Rotating-disk atomizers, which in principle are more suitable, also give a material which is too coarse. However, very good results are obtained using the two-material nozzles described.
The spray drier is generally in the form of a slim tower which consists of an upper cylindrical part having a diameter-to-length ratio of 0.3 to 0.9, preferably 0.6 to 0.8, and a subsequent concial part. It is preferable if this concial part is longer than the cylindrical part. The accompanying gas is fed in and removed by the concurrent method, the particles formed being deposited in a suitable apparatus, such as a cyclone or a filter.
By means of this procedure, it is possible to obtain, alternatively, a very finely divided magnesium alkoxide or, if desired, also magnesium alkoxide having coarser particles.
Because of the nozzle used, which has a small spray angle, and the geometry of the tower, caking on the walls is greatly suppressed.
Relatively stringent conditions are possible for the final drying and decarboxylation, since, owing to the good pre-liminary drying compared with the process disclosed in EuroPean Published Patent Application 0,236,082, the danger of caking is substantially lower. Any suitable drying apparatus which is 2033~6~
Under these conditions, single-material nozzles give particles which are too coarse. Rotating-disk atomizers, which in principle are more suitable, also give a material which is too coarse. However, very good results are obtained using the two-material nozzles described.
The spray drier is generally in the form of a slim tower which consists of an upper cylindrical part having a diameter-to-length ratio of 0.3 to 0.9, preferably 0.6 to 0.8, and a subsequent concial part. It is preferable if this concial part is longer than the cylindrical part. The accompanying gas is fed in and removed by the concurrent method, the particles formed being deposited in a suitable apparatus, such as a cyclone or a filter.
By means of this procedure, it is possible to obtain, alternatively, a very finely divided magnesium alkoxide or, if desired, also magnesium alkoxide having coarser particles.
Because of the nozzle used, which has a small spray angle, and the geometry of the tower, caking on the walls is greatly suppressed.
Relatively stringent conditions are possible for the final drying and decarboxylation, since, owing to the good pre-liminary drying compared with the process disclosed in EuroPean Published Patent Application 0,236,082, the danger of caking is substantially lower. Any suitable drying apparatus which is 2033~6~
preEerably suitable for vacuum operation, such as, for example, paddle driers, tumble driers, rotary kilns, etc., may be used. In general, drying is carried out at temperatures of about 110 to 150C, preferably 125 to 145C, for a period of 3 to 10 hours, preferably 4 to 8 hours, with application of sliqhtlv reduced pressure, preferably 950 to 980 hPa. Under these conditions, the bound CO2 is effectively removed. A paddle drier having paddles which pass close to the edge or an apparatus which intro~
duces the heat directly into the product is particularly suitable.
The magnesium alkoxide powder obtained in this manner can be converted by all conventional methods of the prior art, as described in, for example, European Published Patent Application 0,236,082, into a catalyst for the polymerization of ~-olefins.
The polymerization catalyzed therewith can be carried out in any conventional manner.
The resulting finelv divided catalyst powder is particu-larly suitable for liquid-phase polymerization of ~-olefins, such as, for example, ethylene, propylene, but-1-ene, hex-1-ene or mix-tures thereof, either the liquefied monomer or an inert hydro-carbon being used as a liquid medium. The polymerization can becarried out continuously or batch-wise.
It should be noted that both the pulverulent magnesium alkoxide described here and the polymerization catalyst prepared therefrom have different sensitivities to oxvgen, moisture, carbon dioxide, acetylenes and sulfur compounds; such catalyst poisons must therefore be carefully excluded during the process.
Polypropylene prepared using such catalysts has a high 20339~4 - 10 - 23~43-4~6 stereospecificity and a high bulk density and is easily fluidiz-able during pneumatic conveying, with fluidization beginning at less than 7 cm/sec, typically less than 3 cm/sec and under suit-able conditions less than 1 cm/sec. ~ecause of the small particle size, according to the invention, of the catalyst and the absence of coarse particles, the polyolefin has a very low ash content and can be processed without fish eyes.
The invention will be further described by way of non-limiting examples and with references to the accompanying drawings in which:
Figure 1 represents a scanning electron micrograph of the product of Example 3.
Example 1: Ethanolic solution of carboxvlated magnesium ethoxide .
In a 3 m3 stirred container, 300 kg of magnesium ethoxide are added to 1,000 kg of ethanol while stirring, and then 145 kg of CO2 are metered in via a dip tube extending below the liquid surface, in such a way that no gas bubbles appear at the liquid surface. The magnesium ethoxide particles, which are virtually insoluble in ethanol, gradually dissolve with reaction with the CO2. A slightly cloudy opalescent solution of 30.8~ by weight of carboxylated magnesium ethoxide Mg(OC2H5)2 1.25 C02 is formed.
Example 2 Spraying the solution In a spray tower in which the cylindrical part has a diameter-to-len~th ratio of 0.7, 12.3 kg/h of the solution from Example 1 are sprayed by means of a two-material nozzle with inner atomization in accordance with German Patent 2,627,880 (load: 7%
of capacity) into an accompanying gas stream (dry N2) heated to 203396~
~ 23443-446 110C. The drier outlet temperature is about 90C. The particles are deposited in a double cyclone, the yield is 89.4%, the process being carried out without fine dust filters downstream of the cyclone.
The resulting particles of carboxylated magnesium ethox-ide have a weight average particle diameter of 8.4 ~m (determined by laser diffraction using a "Microtrac"* apparatus from Leeds &
Northrup). They have the following particle size distribution:
d1o = 3-0 ~m; d50 = 6.9 ~m; dgo = 15.0~ m;
i.e. 10~ by weight of the particles have a diameter of up to 3 m, etc. The largest diameter measured is 38 ~m.
The residual ethano] content is 4.9% by weight and the C2 is still bound.
Example 3: Drying and decarboxylation 300 g of the product from Example 2 are subsequently dried for 5 hours at a pressure of 980 mbar and an internal temperature of 131C in a stream of nitrogen (about 10 1/h) in a 2 1 laboratory paddle drier having PTFE paddles which pass close to the edge, a constant weight being achieved.
The primary particle sizes do not change during this procedure; however, small agglomerates form, these being broken up again by stirring during further catalyst preparation. By means of scanning electron micrographs, it is possible to show that the individual spherical particles are not destroyed by the treatment in the paddle drier (see Fig. 1).
The magnesium ethoxide thus obtained is used for the preparation of a catalyst for the polymerization of ~-olefins *Trade-mark 20~39~
according to European Published Patent Application 0,236,082. The activity and stereospecificity of the catalyst obtained are good;
in liquid-phase polymerization of propylene, a polypropvlene having high bulk density and good fluidizability is obtained.
duces the heat directly into the product is particularly suitable.
The magnesium alkoxide powder obtained in this manner can be converted by all conventional methods of the prior art, as described in, for example, European Published Patent Application 0,236,082, into a catalyst for the polymerization of ~-olefins.
The polymerization catalyzed therewith can be carried out in any conventional manner.
The resulting finelv divided catalyst powder is particu-larly suitable for liquid-phase polymerization of ~-olefins, such as, for example, ethylene, propylene, but-1-ene, hex-1-ene or mix-tures thereof, either the liquefied monomer or an inert hydro-carbon being used as a liquid medium. The polymerization can becarried out continuously or batch-wise.
It should be noted that both the pulverulent magnesium alkoxide described here and the polymerization catalyst prepared therefrom have different sensitivities to oxvgen, moisture, carbon dioxide, acetylenes and sulfur compounds; such catalyst poisons must therefore be carefully excluded during the process.
Polypropylene prepared using such catalysts has a high 20339~4 - 10 - 23~43-4~6 stereospecificity and a high bulk density and is easily fluidiz-able during pneumatic conveying, with fluidization beginning at less than 7 cm/sec, typically less than 3 cm/sec and under suit-able conditions less than 1 cm/sec. ~ecause of the small particle size, according to the invention, of the catalyst and the absence of coarse particles, the polyolefin has a very low ash content and can be processed without fish eyes.
The invention will be further described by way of non-limiting examples and with references to the accompanying drawings in which:
Figure 1 represents a scanning electron micrograph of the product of Example 3.
Example 1: Ethanolic solution of carboxvlated magnesium ethoxide .
In a 3 m3 stirred container, 300 kg of magnesium ethoxide are added to 1,000 kg of ethanol while stirring, and then 145 kg of CO2 are metered in via a dip tube extending below the liquid surface, in such a way that no gas bubbles appear at the liquid surface. The magnesium ethoxide particles, which are virtually insoluble in ethanol, gradually dissolve with reaction with the CO2. A slightly cloudy opalescent solution of 30.8~ by weight of carboxylated magnesium ethoxide Mg(OC2H5)2 1.25 C02 is formed.
Example 2 Spraying the solution In a spray tower in which the cylindrical part has a diameter-to-len~th ratio of 0.7, 12.3 kg/h of the solution from Example 1 are sprayed by means of a two-material nozzle with inner atomization in accordance with German Patent 2,627,880 (load: 7%
of capacity) into an accompanying gas stream (dry N2) heated to 203396~
~ 23443-446 110C. The drier outlet temperature is about 90C. The particles are deposited in a double cyclone, the yield is 89.4%, the process being carried out without fine dust filters downstream of the cyclone.
The resulting particles of carboxylated magnesium ethox-ide have a weight average particle diameter of 8.4 ~m (determined by laser diffraction using a "Microtrac"* apparatus from Leeds &
Northrup). They have the following particle size distribution:
d1o = 3-0 ~m; d50 = 6.9 ~m; dgo = 15.0~ m;
i.e. 10~ by weight of the particles have a diameter of up to 3 m, etc. The largest diameter measured is 38 ~m.
The residual ethano] content is 4.9% by weight and the C2 is still bound.
Example 3: Drying and decarboxylation 300 g of the product from Example 2 are subsequently dried for 5 hours at a pressure of 980 mbar and an internal temperature of 131C in a stream of nitrogen (about 10 1/h) in a 2 1 laboratory paddle drier having PTFE paddles which pass close to the edge, a constant weight being achieved.
The primary particle sizes do not change during this procedure; however, small agglomerates form, these being broken up again by stirring during further catalyst preparation. By means of scanning electron micrographs, it is possible to show that the individual spherical particles are not destroyed by the treatment in the paddle drier (see Fig. 1).
The magnesium ethoxide thus obtained is used for the preparation of a catalyst for the polymerization of ~-olefins *Trade-mark 20~39~
according to European Published Patent Application 0,236,082. The activity and stereospecificity of the catalyst obtained are good;
in liquid-phase polymerization of propylene, a polypropvlene having high bulk density and good fluidizability is obtained.
Claims (11)
1. Process for the preparation of finely divided, spherical magnesium alkoxide Mg(OR)2 wherein R ;is C2-C4-alkyl, which process comprises spray drying a solution of the corresponding carboxylated magnesium alkoxide Mg(OR)2 ? x CO2 wherein x is from about 0.2 to about 2.0 in an alcohol ROH and subsequent drying and decarboxylation of the resulting finely divided carboxylated magnesium alkoxide wherein the solution is sprayed via a two-material nozzle with inner atomization, which nozzle is operated in the part-load range at 5 to 30% of its capacity, into an inert accompanying gas which is under a pressure of from about 1.0 to about 1.2 bar, has been preheated to a temperature of from about 100 to about 140°C and is fed concurrently.
2. Process according to Claim 1, wherein the nozzle is operated from about 10 to about 25% of its capacity.
3. Process according to Claim 1, wherein the accompanying gas is dry nitrogen.
4. Process according to Claim 1, 2 or 3, wherein the spray drier consists of an upper cylindrical part having a diameter-to-length ratio of from about 0.3 to about 0.9 and a subsequent conical part.
5. Process according to Claim 4, wherein the diameter-to-length ratio is from about 0.6 to about 0.8.
6. Process according to Claim 4, wherein the conical part of the spray drier is longer than the cylindrical one.
7. Process according to Claim 1, 2 or 3 wherein R is ethyl.
8. Process according to Claim 7, wherein x is from about 1.0 to about 1.25.
9. Process according to Claim 1, 2 or 3 wherein the accompanying gas is preheated to a temperature of from about 105°
to about 120°C.
to about 120°C.
10. Finely divided, spherical magnesium alkoxide prepared according to Claim 1, 2 or 3, wherein the weight average particle diameter is less than 10 µm.
11. Use of the magnesium alkoxide according to Claim 10 for the preparation of a catalyst for the polymerization of .alpha.-olefins.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4000697.2 | 1990-01-12 | ||
| DE4000697A DE4000697A1 (en) | 1990-01-12 | 1990-01-12 | METHOD FOR PRODUCING SPHERICAL PARTICLES OF MAGNESIUM ALKOXIDE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2033964A1 true CA2033964A1 (en) | 1991-07-13 |
Family
ID=6397927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002033964A Abandoned CA2033964A1 (en) | 1990-01-12 | 1991-01-10 | Process for the preparation of spherical particles of magnesium alkoxide |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0436801B1 (en) |
| JP (1) | JPH0687773A (en) |
| KR (1) | KR910014383A (en) |
| AT (1) | ATE94862T1 (en) |
| CA (1) | CA2033964A1 (en) |
| DE (2) | DE4000697A1 (en) |
| ES (1) | ES2044376T3 (en) |
| FI (1) | FI910125A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4040252A1 (en) * | 1990-12-17 | 1992-06-25 | Huels Chemische Werke Ag | METHOD FOR THE PRODUCTION OF EARTH ALKALYL ALCOHOLATES WITH SPHERICAL PARTICLE HABITUS |
| DE4300186A1 (en) * | 1993-01-07 | 1994-07-14 | Huels Chemische Werke Ag | Storage-stable solutions of carbonized magnesium methylate in methanol as well as their production and use |
| DE4300185A1 (en) * | 1993-01-07 | 1994-07-14 | Huels Chemische Werke Ag | Storage-stable solutions of a mixture of carbonized magnesium methylate, carbonized magnesium ethylate and their carbonized mixed alkoxide in a mixture of methanol and ethanol and their preparation and use |
| KR100954056B1 (en) | 2007-12-12 | 2010-04-20 | 삼성토탈 주식회사 | Method of preparation of spherical support for olefin polymerization catalyst |
| KR20100007076A (en) | 2008-07-11 | 2010-01-22 | 삼성토탈 주식회사 | Method for controlling size of spherical support for olefin polymerization catalyst |
| KR101140112B1 (en) | 2009-05-22 | 2012-04-30 | 삼성토탈 주식회사 | A preparation method of dialkoxymagnesium support for catalyst for olefin polymerization, a preparation method of catalyst for olefin polymerization using the same and a polymerization method of olefin using the same |
| CN101906017A (en) * | 2009-06-04 | 2010-12-08 | 中国石油化工股份有限公司 | Method for preparing alkoxyl magnesium solid particles |
| KR101169861B1 (en) | 2010-05-27 | 2012-07-31 | 삼성토탈 주식회사 | Method of preparation of spherical support and solid catalyst for olefin polymerization using the support |
| ES2804259T3 (en) | 2010-09-16 | 2021-02-05 | China Petroleum & Chem Corp | Catalyst support for olefin polymerization, solid catalyst component and catalyst |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1806549B2 (en) * | 1968-11-02 | 1974-06-12 | Dynamit Nobel Ag, 5210 Troisdorf | Process for the production of magnesium-alcohol compounds |
| GB8521431D0 (en) * | 1985-08-28 | 1985-10-02 | Shell Int Research | Spherical magnesium alkoxide particles |
| IN168393B (en) * | 1986-02-28 | 1991-03-23 | Shell Oil Co |
-
1990
- 1990-01-12 DE DE4000697A patent/DE4000697A1/en not_active Withdrawn
- 1990-11-14 ES ES90121757T patent/ES2044376T3/en not_active Expired - Lifetime
- 1990-11-14 AT AT90121757T patent/ATE94862T1/en not_active IP Right Cessation
- 1990-11-14 EP EP90121757A patent/EP0436801B1/en not_active Expired - Lifetime
- 1990-11-14 DE DE90121757T patent/DE59002845D1/en not_active Expired - Fee Related
-
1991
- 1991-01-09 FI FI910125A patent/FI910125A/en not_active Application Discontinuation
- 1991-01-10 KR KR1019910000238A patent/KR910014383A/en not_active Application Discontinuation
- 1991-01-10 CA CA002033964A patent/CA2033964A1/en not_active Abandoned
- 1991-01-11 JP JP3012684A patent/JPH0687773A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0436801A1 (en) | 1991-07-17 |
| DE4000697A1 (en) | 1991-07-18 |
| ES2044376T3 (en) | 1994-01-01 |
| FI910125A (en) | 1991-07-13 |
| FI910125A0 (en) | 1991-01-09 |
| ATE94862T1 (en) | 1993-10-15 |
| JPH0687773A (en) | 1994-03-29 |
| EP0436801B1 (en) | 1993-09-22 |
| KR910014383A (en) | 1991-08-31 |
| DE59002845D1 (en) | 1993-10-28 |
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