GB1586071A

GB1586071A - Olefin polymerization process and catalyst

Info

Publication number: GB1586071A
Application number: GB1303877A
Authority: GB
Original assignee: Gulf Oil Corp
Current assignee: Gulf Oil Corp
Priority date: 1976-06-03
Filing date: 1977-03-29
Publication date: 1981-03-18
Also published as: IT1077114B; JPS52147591A; CA1099251A; FR2353568B1; DE2716256A1; NL7706167A; BE855241A; FR2353568A1

Description

(54) OLEFIN POLYMERIZATION PROCESS AND CATALYST (71) We, GULF OIL CORPORATION, a corporation organized and existing under the laws of the State of Delaware, United States of America, of P.O. Box 1166, Pittsburgh, Pennsylvania 15230, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to Ziegler-type catalysts.

It is known that Ziegler-type catalysts formed by combining an organometallic compound of the metal of Groups IIA, IIB and IIIA of the Periodic Table with a halide of a metal of Groups IVB, VB or VIB of the Periodic Table are useful for polymerizing mono-1 olefins at low pressures and low temperatures to form resinous polyolefins. The Periodic Table referred to herein is published in Deming, General Chemistry (5th Edition, Wiley 1944) and is reprinted in Handbook of Chemistry and Physics, p.336 (31st Edition, Chem. Rubber, 1949).

While many Ziegler-type catalysts are known in the art and are quite efficient for certain purposes, the art is continuously seeking new and improved catalysts of this type. In particular, the art is continuously seeking improved catalysts of lower cost; greater ease of manufacture and handling; and particularly catalysts of high activity which leave very low levels of catalyst fragments in the polymers that are produced.

According to the present invention there is provided a process for preparing a supported, chemically modified titanium tetrachloride catalyst component comprising the sequential steps of: (a) suspending a finely-divided polymer in a solution of magnesium compound in an alkanol of from 1 to 4 carbon atoms, (b) vaporising alkanol from the suspension of step (a) to deposit a complex of magnesium compound with the alkanol on the surface of the finely-divided polymer, (c) adding an aluminium alkyl compound to the product of step (b) suspended in a liquid hydrocarbon; and (d) adding titanium tetrachloride compound to the suspension of step (c); The polymer employed in step (a) being an organic thermoplastic or thermosetting polymer, the particles of such polymer having at least one dimension not exceeding 600 microns; the magnesium compound employed in step (a) having the structure: MgX2.nH20 where X is Cl, F, Br, I, NO3, OCH3, OCOCH3, or -OOCH, and n is not greater than 6; the magnesium compound employed in step (a) constituting from 1 to 60 weight % of the combined weight of the finely-divided polymer and the magnesium compound; the aluminium alkyl compound employed in step (c) being a dialkyl aluminium hydride, dialkyl aluminium halide or trialkyl aluminium; the quantity of the aluminium alkyl employed in step (c) being not in excess of the quantity that will react with the magnesium compound-alkanol complex carried on the polymeric support; and the quantity of the titanium tetrachloride employed in step (d) being at least molarly equivalent to the quantity of the aluminium alkyl compound employed in step (c).

The present invention provides chemically modified, titanium tetrachloride compounds that are carried upon a polymeric support. These products, when activated by reaction with aluminium alkyls such as triethyl aluminium, provide highly active catalysts for the polymerization of olefins such as ethylene and give very high yields of polymers, as calculated on the metal content of the catalyst.

In the first step of the preparation of the supported, chemically-modified titanium tetrach chloride compounds, a finely divided polymeric support is suspended in an alkanol solution of the defined class of magnesium compounds. The polymeric support may be either an organic thermoplastic polymer or an organic thermosetting polymer. The polymeric catalyst support is a finely divided particulate form which has at least one dimension not exceeding 600 microns and preferably having one dimension falling within the range of 1 to 200 microns.

The polymeric support may be of any desired shape such as spheres, rods or cylinders.

Suitable polymeric materials include poly (triallyisocynaurate), polyethylene, polypropylene, poly (3-methylbutene), poly (4-methylpentene), polyamides, polyesters, polyacrylamides, polyacrylonitriles, polycarbonates and cellulose. Essentially any polymer not soluble in the alkanol can be employed.

Magnesium compounds found to be particularly suitable in the practice of the invention are magnesium chloride, magnesium methoxide, magnesium nitrate, and magnesium acetate.

The alkanol in which the magnesium compound will be dissolved is an alcohol containing 1-4 carbon atoms such as methanol, isopropanol and butanol. The alkanol solution contains a relatively high concentration (1 to 60 weight %) of the magnesium compound, desirably 5 to 25%by weight.

In carrying out the first step of the process, the polymeric support is be suspended in a sufficient quantity of the alkanol solution of the magnesium compound so that the magnesium compound contained therein will constitute 1-60 weight % and preferably 5-25 weight % of the combined weight of the polymeric support and the magnesium compound.

The polymeric carrier may be stirred with the alkanol solution of the magnesium compound to the extent required to wet and impregnate the polymeric carrier thoroughly with the alkanol solution.

In the second step of the process, alkanol is vaporized from the suspension of the polymeric carrier in the alkanol solution so as to deposit the magnesium compound uniformly over the polymeric carrier. The magnesium compound is deposited on the carrier in the form of a complex with the alkanol. The precise structure of the complex has not been established, but it is believed to contain 1 - 4 mols of alkanol per mol of magnesium compound. It is observed, however, that the magnesium compound-alkanol complex is in a highly active state particularly suitable for use in the preparation of the chemically-modified, titanium tetrachloride compounds in the subsequent steps of the process. To the extent that is practically feasible, all of the alkanol, except that complexed with the magnesium compound, should be removed as any excess alkanol will react with and consume the aluminum alkyl compound employed in the next step of the process.

The alkanol can be removed by simply distilling or evaporating the alkanol from the suspension of the polymeric carrier in the alkanol solution. When this technique is employed, the distillation or evaporation is preferably carried out under reduced pressure. Frequently the distillation or evaporation of the alkanol may be accelerated by passing an inert sweep gas such as nitrogen or argon over the surface of the alkanol solution. It is recommended that care should be exercised to remove the alkanol solution at moderate temperatures not exceeding 1500C. and preferably not exceeding 75"C. When a sweep gas is employed, special precautions should be employed to free the sweep gas of water, oxygen and other components recognized as having a deleterious effect upon Ziegler-type catalysts.

While a simple evaporation or distillation as described above may be used to remove the alkanol, somewhat better results are obtained if at least the final portions of the alkanol are removed by codistillation with an inert hydrocarbon. In this procedure a liquid hydrocarbon such as heptane, may be added to the reaction vessel preferably after a portion of the alkanol is removed as described previously. The hydrocarbon may then be distilled from the system under atmospheric or preferably reduced pressure. So long as any free uncomplexed alkanol remains in the system, the distillate being removed from the system will be a mixture of the hydrocarbon and alkanol. When the final traces of the uncomplexed alkanol are removed from the system, the vapor temperature of the distillate will rise to the boiling point of the hydrocarbon at the prevailing pressure employed in the distillation. Thus, the observed boiling point of the distillate serves as a criterion for determining when the removal of the alkanol is completed.

The hydrocarbon employed for removal of the alkanol may be of any of the hydrocarbon types conventionally employed in the preparation of Ziegler-type catalysts. The hydrocarbon employed should be purified in a manner so as to remove therefrom moisture and other materials known to have a deleterious effect upon the activity of Ziegler-type catalysts.

In the next step of the process, the polymeric carrier with the magnesium compound deposited thereon is suspended in a liquid hydrocarbon preferably of the type previously described. Such a slurry already will have been prepared if the alkanol is removed by azeotropic distillation as described immediately above. A suitable aluminum alkyl compound such as diethyl aluminum chloride may then then be added to the slurry. The aluminum alkyl reacts with the magnesium compound-alkanol complex carried on the polymeric support.

The mechanism by which the two components react and the structure of the resulting reaction product have not been fully established. The evidence that a chemical reaction takes place is that a gas, possibly an alkane, is formed when the aluminum alkyl is added to the reaction mixture, The reaction product formed in this step of the process is firmly bonded to the polymeric support.

The aluminum alkyl employed in the step of the process described immediately above is a di4kyl aluminum halide, a dialkyl aluminum hydride, or a trialkyl aluminum. Typical examples of suitable alkyl aluminums include triethyl aluminum, triisobutyl aluminum, diethyl aluminum hydride and diethyl aluminum chloride.

The aluminum alkyl should be employed in a quantity such that all of the aluminum alkyl added to the reaction mixture will react with the magnesium compound-alkanol complex carried on the polymeric support and so that the reaction system, after completion of this step of the process, contains little or no unreacted aluminum alkyl in the hydrocarbon phase of the reaction mixture. If an excess of the aluminum alkyl is employed, the remaining free unreacted aluminum alkyl will react with the transition metal chloride employed in the next step of the process to form a more conventional Ziegler-type catalyst as a coproduct. The presence of such conventional Ziegler-type catalyst will tend to reduce the advantages obtained with the present invention.

The precise quantity of aluminum alkyl to be employed depends somewhat upon the completeness with which uncomplexed alkanol is removed from earlier steps of the process.

This results from the fact that any free uncomplexed alkanol present in the reaction system will react with the aluminum alkyl compound. Ordinarily, it is preferable to employ 0.1 - 2.0 mols and preferably 0.25 - 0.5 mol of the aluminum alkyl for each mol of the magnesium compound present in the reaction system. If desired or believed to be necessary, the presence of unreacted aluminum alkyl can be determined either qualitatively or quantitively by removing a sample from the reaction system; filtering the solids from the slurry and measuring the concentration (if any) of the aluminum alkyl present in the hydrocarbon filtrate.

Analytical methods for measuring the concentration of aluminum alkyls in hydrocarbons are known in the art.

The use of less than the stoichiometrically required quantity of the alkyl aluminum has no serious effect upon the quality of the ultimate product. If the supported reaction product contains unreacted magnesium compound, the unreacted magnesium compound will react with the transition metal chloride in the next step of the process to provide a reaction product which will be converted into a slightly different polymerization catalyst in subsequent processing steps.

In the next step of the process, titanium tetrachloride is added to the reaction mixture of the previous step, which contains as the active reactant the reaction product formed between the supported magnesium compound-alkanol complex and the aluminum alkyl. The transition metal chloride reacts with the previously prepared reaction product arid is reduced to a lower valence state. This supported, chemically-modified titanium tetrachloride compound is the ultimately desired product and is insoluble in the hydrocarbon reaction medium. The structure of product has not been established, but probably is complex. Virtually all of the titanium becomes bound to the polymeric support, probably by reason of formation of a chemical or physical complex with the magnesium compound.

In this step of the process, from 1 to 2 mols of the titanium tetra-chloride will be preferably employed for each mole of aluminum alkyl employed in the previous step of the process. Not more than 2 mols of the transition metal chloride compound can be reduced by 1 mol of the previously-prepared reaction product, and any quantity of transition metal chloride added in excess of this quantity serves principally to drive the reaction to completion in the shortest possible period of time.

As the supported chemically-modified, titanium tetra-chloride product is insoluble in the hydrocarbon medium, it can be recovered by filtration and stored for future use if desired. If the product is recovered in this manner for storage, the hydrocarbon filtrate containing unconsumed transition metal chloride can be recovered and reused in the subsequent production of additional product. The recovered solid reaction product should preferably be washed with hydrocarbon to free it from any occluded unreacted transition metal chloride compound.

It is frequently desirable, however, to use the product shortly after it is prepared. In such situations, it is usually desirable to employ the product in the slurry in which it is prepared. In such situations, it is desirable to remove any unreacted transition metal chloride from the system. Such removal can be effected by simply distilling the high boiling hydrocarbon from the slurry at either atmospheric or reduced pressure. The unreacted transition metal chloride codistills with the hydrocarbon. The distillation is continued until the distillate gives a negative test for chloride.

To prepare catalyst compositions used for the polymerization of olefins; the supported, chemically-modified product is reacted with an aluminum alkyl compound in a hydrocarbon medium. The reaction is carried out in a manner generally equivalent to that employed to prepare conventional Ziegler-type catalysts. The supported, chemically-modified, product is employed in the same molar proportions as conventional transition metal chlorides are employed in their reactions with aluminum alkyls. Typically the two components are employed in proportions to provide an Al/Ti atomic ratio of 0.5 - 10.0, or preferably 1.0 - 5.0.

While dialkyl aluminum hydrides and dialkyl aluminum halides can be employed for-this purpose, the trialkyl aluminums, and particularly triethyl aluminum and triisobutyl aluminum, are the preferred aluminum alkyls to be employed in the preparation of such catalyst compositions.

The polymerization catalysts prepared as described above have a number of features which make them particularly effective and desirable for use in the polymerization of mono-1 olefins. Initially, it will be noted that the magnesium compound, the titanium tetrachloride, and the aluminum alkyl compounds can be employed in the precise quantities * required in the final catalyst composition. Thus, no expensive compounds need be employed in excess of their actual need, and the expense of recycling and/or recovering excess starting materials can be avoided. These factors, coupled with the high productivity rates of the catalysts, provide low production costs for the polymers produced. In addition, by reason of the high catalyst productivity, the finished polymers contain very low concentrations of metallic catalyst residues so that for most purposes they need not be removed from the polymers. Yet another advantage of the catalysts of the invention is that they have a specific gravity substantially the same as the hydrocarbon solvent employed in the olefin polymerization process. Thus, a uniform dispersion of the polymerization catalyst in the polymerization solvent is more easily obtained than is the case with more conventional Ziegler-type catalysts.

The catalyst compositions of this invention can be employed in the polymerization of mono-1 olefins having from 2 to 8 carbon atoms per molecule. Although not limited thereto, the novel catalysts are particularly effective in the polymerization of ethylene to produce polyethylene and in the copolymerization of ethylene with other mono-1 olefins containing from 3 to 8 carbon atoms.

The polymerizations can be effected with such catalysts by contacting the mono-1 olefin with the catalysts in the liquid or gaseous phase, and in the presence or absence of an inert solvent such as benzene, xylene, or saturated hydrocarbons such as isooctane, n-decane, n-hexane, n-heptane, pentane, decane or cyclohexane. The concentration of the catalyst composition in the polymerization zone is preferably maintained in the range of 0.01 to 4.0 g.

per liter of reactor volume. The polymerization reaction is generally conducted at a temperature of 0 - 250"C. and at a pressure of atmospheric or higher.

The polymerization process can be conducted batchwise, or by continuous polymerization methods known in the art. The polymerization process employing the novel catalyst compositions can be conducted in the absence or presence of hydrogen and other polymerization additives and/or modifiers known in the art, such as amines, ethers or dicumyl peroxide. The additives can be introduced onto the catalyst support prior to, during, or after treatment of the support with the titanium tetrachloride. It is also within the scope of the invention to introduce the additive directly into the polymerization reactor.

The effluent mixture withdrawn from the polymerization mixture comprises a polymer slurry which can be filtered to isolate the resinous polyolefin. Other conventional polymer separation steps can be employed in the separation of the polymer product from the remainder of the polymerization reactor effluent.

If desired, although not normally required because of high productivity of the reaction, catalyst residues can be separated from the polymer product by methods known in the art.

One method comprises stirring a slurry of the polymerization product in water or an alcohol such as methanol and then separating the resinous polyolefin by filtration to provide a white product. Polyolefins which are soluble in the reaction solvent can be precipitated from the solvent by adding an excess of methanol and filtering off precipitated polymer.

With the catalysts of the invention. a productivity of at least 10,000 gram of polymer per gram of titanium per hour can normally be obtained for olefin polymer products having molecular weights ranging from 20,000 to 2,000,000. These high productivities of the catalyst compositions eliminate the necessity in most instances for separating the very small catalyst residues remaining in the polymer product.

For the production of polyethylene the most preferred selection of the various disclosed features of the invention is a process which comprises a process for producing polyethylene comprising preparing a supported, chemically-modified titanium tetrachloride catalyst com ponent by the sequential steps of: (a) suspending the finely divided organic thermoplastic or thermosetting polymer in a 1-4 carbon atom alkanol solution of a magnesium compound, (b) distilling a portion of the alkanol from the suspension of step (a); (c) adding a liquid hydrocarbon to the slurry remaining at the conclusion of step (b), (d) distilling a hydrocarbon-alkanol mixture from the slurry of step (c) until the boiling point of the distillate rises to the boiling point of the hydrocarbon, (e) adding diethyl aluminium chloride to the slurry remaining at the conclusion ofstep (d), (fl adding titanium tetrachloride to the suspension of step (e); and (g) distilling hydrocarbons from the slurry of step (f) to remove any unreacted titanium tetrachloride as a distillate with the hydrocarbon; the particles of the polymer having at least one dimension not exceeding 600 microns; the magnesium compound being chloride methoxide, acetate or nitrate and constituting from 5 to 25 weight % of the combined weight of polymer and magnesium compound; the quantity of diethyl aluminium chloride employed in step (e) being not in excess fo the quantity that will react with the magnesium compound alkanol complex carried on the polymeric support; and the quantity of titanium tetrachloride employed in step (d) being at least molarly equivalent to the quantity of the diethyl aluminium chloride employed in step (e); reacting the catalyst component with the trialkyl aluminium to form a polymerisation catalyst; suspending the catalyst in a liquid hydrocarbon to form a slurry; passing ethylene gas through the slurry for a period of less than 5 minutes at substantially atmospheric pressure and ata temperature of less than 20"C; and contacting ethylene with the ethylene treated catalyst at a temperature above 20"C and at a pressure above atmospheric pressure.

The present invention will now be described, by way of illustration in the following Examples of which Examples 4 to 9 are given for comparison.

Example 1-3 Three catalyst components were prepared following the techniques of the present invention and were employed to polymerize ethylene.

Preparation ofSupport A 4-liter reaction vessel; fitted with a stirrer, a reflux condenser, a dropping funnel, and heating and cooling means, was charged with a methanolic solution of magnesium chloride prepared by dissolving 75 grams of magnesium chloride in 1 liter of methanol. Six hundred seventy grams of a finely divided powder of high density polyethylene having an average particle diameter of less than 40 microns was slurried in the methanolic solution of magnesium chloride. The slurry was heated to a temperature of 55 "C over a period of 30 minutes and stirring at this temperature was continued for another 30 minutes. This pressure then was reduced to about 10 mm of Hg to remove methanol from the system. Heating was continued for two hours under these conditions to assure removal of all methanol which did not form a complex with the magnesium chloride deposited on the polyethylene support. The powder was removed from the reaction vessel and ground to pass through a 40-mesh U.S. screen.

Treatment ofSupport with Diethyl Aluminum Chloride and Tics 4 The magnesium chloride treated polyethylene powder prepared as described above in the amount of 200 grams, an appropriate quantity of heptane and an appropriate quantity of diethyl aluminum chloride, was charged to a 4-liter reactor equipped as described above. This reaction mixture was stirred for one hour while maintaining the temperature at 250C.

Evolution of a gas was noted. At this point in the reaction, it is believed that the charged diethyl aluminum chloride has been chemically bonded to the polymeric support or one of the chemicals carried thereon. The reaction mixture then was heated to 800C and an appropriate quantity of TiCl4 was added to the reaction mixture from the dropping funnel over a period of one hour. The reaction mixture then was stirred for an additional 16-20 hours, while maintaining the temperature at 80"C. to assure complete reaction between the TiCl4 and the components carried on the support. Prior to the addition of the Tic4, the solids present in the slurry were light yellow in color, but the color changed to a purple-red shortly after the addition of the Tic4. The liquid present in the slurry was removed by decantation, and the solids were washed with several aliquots of heptane until the heptane gave no test for the presence of chlorides. The solids then were recovered and dried under vacuum at ambient temperature.

Ethylene Polymerization The catalyst components prepared as described above were employed to polymerize ethylene in a 1.5 liter pressure resistant reactor, equipped with a stirrer and means for feeding ethylene to the reactor. After purging the reactor twice with polymerization grade ethylene to remove oxygen. the reactor was charged with 1 liter of heptane 0.5 gram of the solid catalyst component, and 2 ml. of a 25% solution of triethyl aluminum in heptane. Twenty grams of polyethylene cubes (approximately 1/8" in diameter) were added to the reactor to prevent the polyethylene being produced from agglomerating and to prevent fouling of the reactor.

Polymerization grade ethylene was charged to the reactor to develop a pressure of 40 psig and the ethylene feed system was set to continuously feed ethylene to the reactor to maintain this pressure. The reaction mixture was heated to a temperature of 80"C. which initiated rapid polymerization. Polymerization was continued for a period sufficient to produce approximately 150 grams of polymer. Polymerization was terminated by shutting off the supply of ethylene gas and venting the reactor.

In all of the procedures described above, care was exercised to carry out all reactions under rigorously anhydrous conditions. All reactants employed were purified grades and contained no identifiable concentrations of water or reactive hydrogen compounds known to have a deleterious effect upon Ziegler-type polymerization reactions.

Table I below sets forth the quantity of reactants employed in the preparation of the catalyst components and also sets forth an analysis of the ultimate catalyst components. Table II sets forth the polymerization data.

TABLE I Section A Preparation of support Methanol- Mg Cl 2Sol'n Example Polyethylene Methanol Mg Cl2 No. Powder, gms ml gms 1 666 1,000 75 2 666 1,000 75 3 666 1,000 75 Section B Preparation Catalyst Component Example Catalyst Heptane DEAC(1) TiCL4 No. Support, gms ml gms gms 1 200 400 72 663 2 200 300 36 345 3 200 300 36 345 Section C Catalyst Analysis Example Magnesium Aluminum Chlorine Titanium Total No. wt % wt % wt % wt % Inorganic wt % 1 1.7 0.3 9.7 2.0 13.7 2 2.0 4.1 15.9 2.6 24.6 3 1.7 2.7 15.1 2.8 22.3 TABLE II Polymer Example Polymerization Yield g/g-cat/hour g/g-inorg/hour g/g-Ti/hour No. Time, minutes grams (1) (2) (3) 1 15 188 1500 10,960 75,076 2 8 139 2090 8,480 80,233 3 7 147 2520 11,300 89,996 (1) Grams of polymer per gram of catalyst per hour.

(2) Grams of polymer per gram of inorganic material contained in the catalyst per hour.

(3) Grams of polymer per gram of titanium contained in the catalyst per hour.

Comparative Examples 4- 9 For comparison purposes, five catalyst compositions were prepared from reactants similar to those employed in Examples 1-3 and were employed to polymerize ethylene.

The initial catalyst components were prepared by techniques essentially similar to those described above, except that where a polyethylene support was employed it was not impregnated with magnesium chloride deposited thereon by evaporation from a methanol solution.

The catalyst component of comparative Example 4 was prepared by mixing 1.4 grams of diethyl aluminum chloride with 6 ml of heptane and adding 17.3 grams of TiC14 thereto.

The catalyst component of comparative Example 5 was prepared by suspending 200 grams of polyethylene powder and 33.8 grams of diethyl aluminum chloride in 300 ml of heptane and adding 340 grams of TiCl4 thereto.

The catalyst component of comparative Example 6 was prepared by suspending 200 grams of polyethylene powder, 10.6 grams of diethyl aluminum chloride and 26.8 grams of diethyl aluminum ethoxide in 250 ml of heptane before adding 345 grams of TiCl4 thereto. The catalyst component of comparative Example 7 was prepared by adding 200 grams of polyethylene powder, 33.5 grams of diethyl aluminum chloride and 23.7 grams of methanol to 300 ml of heptane, before adding 345 grams of TiCl4 thereto.

The catalyst component of comparative Example 8 was prepared by adding 200 grams of polyethylene powder, 33.5 grams of diethyl aluminum chloride and 18.7 grams of magnesium chloride to 300 ml of heptane. The magnesium chloride was dry-mixed with the polyethylene powder and added to the heptane solution before the diethyl aluminum chloride was added thereto. Thereafter 345 grams of TiCl4 was added to the reaction mixture.

The above-described catalyst components were prepared in the same equipment employed in Examples 1-3. The same heating cycle was employed for the reaction ofTiCi4,</ provided polymers having an extremely low concentration of inorganic catalyst residues, inasmuch as the catalyst compositions provide a polymer yield in excess of 8,000 grams of polymer per gram of inorganic material per hour. The yield of polyethylene based-on the titanium content exceeded 75,000 grams of polyethylene per gram of titanium per hour.

By comparison, the data of Table IV indicate that significantly lower productivity rates are obtained when any departure is made from the precise mode of preparing the catalyst compositions of the invention. The maximum yield of polymer obtained in the comparative examples was less than 600 grams of polymer per gram of catalyst per hour. The maximum yield of polymer per gram of inorganic material was just in excess of 2,000 grams of polymer per gram of inorganic material.

Example 10 A polymerization catalyst was prepared by suspending 0.2 gram of the catalyst component of Example 1 in 50 ml of heptane and adding thereto 0.36 gram of triethyl aluminum (added as a 25 % solution in heptane). This catalyst mixture then was cooled to approximately 10 C.

and ethylene at atmospheric pressure was bubbled through the catalyst suspension. It was noted that the suspended catalyst solids appeared to grow in size, probably by reason of polymerization of ethylene on the catalyst particles.

The ethylene polymerization reactor described in Example 1 was purged twice with polymerization grade ethylene to remove oxygen and the reactor then was charged with 1 liter of heptane. The catalyst suspension described in the paragraph above then was added to the polymerization reactor. Polymerization grade ethylene then was charged to the reactor to develop a pressure of 40 psig and the ethylene feed system was set to continuously feed ethylene to the reactor to maintain this pressure. The reaction mixture was heated to 800 C.

and polymerization was continued for one hour. A yield of 1,633 grams of polymer per gram of catalyst per hour was obtained.

The catalyst employed in this Example 10 differed from the catalyst of Example 1 in that it was aged briefly in the presence of ethylene at low temperature and atmospheric pressure prior to being employed in polymerizing ethylene at elevated temperature and pressure. For reasons not fully understood, this preliminary aging treatment significantly modifies the properties of the polyethylene produced with the catalyst. The polymer particles produced during the polymerization reaction had a higher density, were easier to handle, and had less tendency to foul the reactor with low bulk density polymer.

In preparing modified catalysts of the type illustrated in Example 10, ethylene gas is passed in contact with the polymerization catalyst for a short period of time, usually from 1 to 5 minutes. The contact is made at ambient temperature of 20"C. or less, e.g., 10-15"C. being adequate. The contact is made at substantially atmospheric pressure, although moderately higher or lower pressures can be employed, e.g. 0.5-1.5 atmospheres. After this pretreatment step, the catalysts are employed to polymerize ethylene at more elevated temperatures and pressures. The principal advantage of this type of pretreated catalyst and its method of use is that the ethylene polymer produced has a higher bulk density and a reduced tendency to foul the polymerization reactor.

Example 11 Sixty-seven grams of high density polyethylene, having a particle size less than 40 microns, was suspended in 100 ml of methanol containing 7.5 grams of dissolved magnesium chloride in a 1-liter reaction vessel equipped as described in Example 1. Two hundred and fifty ml of heptane then was added to the reactor and the reaction mixture was heated to take off an overhead fraction having a boiling point of 59-60"C. After about 175 ml of distillate was recovered, the temperature of the distillate rose to the atmospheric boiling point of heptane.

The reactor was cooled to room temperature and 70 ml of a heptane solution containing 12.7 grams of diethyl aluminum chloride was added to the suspension of polymer-supported magnesium chloride in the reactor dropwise over a period of 15 minutes. A colorless gas was liberated and vented during this addition. Thereafter, the reaction mixture was heated to 80"C. and 138 grams of TiCl4 was added dropwise to the reaction system. At the start of the addition of the TiCl4 the reaction mixture was a straw yellow in color. but about 15 minutes after the addition of the TiCI4 had been completed, the solids in the reaction system changed to a purple-red color. Heating was continued with stirring for another 16 hours. Thereafter the reactor was cooled and the catalyst solids were recovered by filtration. The recovered solids were washed with aliquots of dry heptane until the wash heptane gave a negative test for soluble chlorides.

A total of 0.2 gram of catalyst component described in the paragraph above was suspended in 50 ml of heptane having dissolved therein 0.36 gram of triethyl aluminum. This suspension was cooled to 10-15"C. and ethylene at atmospheric pressure was bubbled through the catalyst suspension for 2 minutes. As in Example 10 above, the catalyst solids appeared to increase in size, probably by reason of the formation of polyethylene on the catalyst particles.

The catalyst suspension described in the paragraph above was added to 1000 ml of heptane and was employed to polymerize ethylene at a temperature of 85"C. and at an ethylene pressure of 40 psig. A total of 242 grams of polyethylene was produced in 1 hour. The yield was 1210 grams of polymer per gram of catalyst per hour.

Examples 12-15 Four additional catalyst components were prepared by the technique described in Example 11. The quantities of magnesium chloride, diethyl aluminum chloride and TiC14 were varied to illustrate the effect that the ratios of the individual chemicals have upon the activity of the catalyst component and the finished catalyst ultimately formed by reacting the catalyst component with triethyl aluminum. Each of the catalyst components were converted to a finished catalyst by reaction with triethyl aluminum in the same manner set forth in Example 11. Each of the finished catalysts was given a preliminary treatment with ethylene at atmospheric pressure and at about 15"C. for a period of two minutes before being employed to polymerize ethylene. The catalysts then were employed to polymerize ethylene at 850C.

under a pressure of 4 atmospheres as previously described. Details of the quantities of the chemicals employed to prepare the catalyst components are set forth in Table V. The polymerication results are set forth in Table VI.

TABLE V Chemicals Used in Preparation of Catalyst Component Example Polyethylene Methanol Mg Cl2 DEAC(1) Ti Cl4 No. Powder, gms ml gms gms gms 12 666 1,000 72 72 663 13 666 1,000 38 36 332 14 666 1,000 38 18 166 15 666 1,000 38 7 332 (1) Diethyl Aluminum Chloride TABLE VI Catalyst Activity Example g/g-cat/hour No. (I) 12 3,000 13 455 14 137 15 305 (1) Grams of polymer per gram of catalyst per hour.

WHAT WE CLAIM IS: 1. A process for preparing a supported, chemically-modified titanium tetrachloride catalyst component comprising the sequential steps of: (a) suspending a finely-divided polymer in a solution of a magnesium compound in an alkanoloffrom 1 to 4 carbon atoms (b) vaporising alkanol from the suspension of step (a) to deposit a complex of the magnesium compound with the alkanol on the surface of the finely-divided polymer (c) adding an aluminium alkyl compound to the product of step (b) suspended in a liquid hydrocarbon; and (d) adding titanium tetrachloride compound to the suspension of step (c); the polymer employed in step (a) being an organic thermoplastic or thermosetting polymer, the particles of such polymer having at least one dimension not exceeding 600 microns; the magnesium compound employed in step (a) having the structure: MgX2.nH2O where X is Cl, F, Br, I, NO3, OCH3, OCOCH3, or -OOCH, and n is not greater than 6; the magnesium compound employed in step (a) constituting from 1 to 60 weight % of the combined weight of the finely-divided polymer and the magnesium compound; the aluminium alkyl compound employed in step (c) being a dialkyl aluminium hydride, dialkyl aluminium halide, or trialkyl aluminium; the quantity of the aluminium alkyl employed in step (c) being not in excess of the quantity that will react with the magnesium compoundalkanol complex carried on the polymeric support; and the quantity of the titanium tetrach chloride employed in step (d) being at least molarly equivalent to the quantity of the aluminium alkyl compound employed in step (c).

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

and was employed to polymerize ethylene at a temperature of 85"C. and at an ethylene pressure of 40 psig. A total of 242 grams of polyethylene was produced in 1 hour. The yield was 1210 grams of polymer per gram of catalyst per hour.

Examples 12-15 Four additional catalyst components were prepared by the technique described in Example 11. The quantities of magnesium chloride, diethyl aluminum chloride and TiC14 were varied to illustrate the effect that the ratios of the individual chemicals have upon the activity of the catalyst component and the finished catalyst ultimately formed by reacting the catalyst component with triethyl aluminum. Each of the catalyst components were converted to a finished catalyst by reaction with triethyl aluminum in the same manner set forth in Example 11. Each of the finished catalysts was given a preliminary treatment with ethylene at atmospheric pressure and at about 15"C. for a period of two minutes before being employed to polymerize ethylene. The catalysts then were employed to polymerize ethylene at 850C.

under a pressure of 4 atmospheres as previously described. Details of the quantities of the chemicals employed to prepare the catalyst components are set forth in Table V. The polymerication results are set forth in Table VI.

TABLE V Chemicals Used in Preparation of Catalyst Component Example Polyethylene Methanol Mg Cl2 DEAC(1) Ti Cl4 No. Powder, gms ml gms gms gms

12 666 1,000 72 72 663

13 666 1,000 38 36 332

14 666 1,000 38 18 166

15 666 1,000 38 7 332 (1) Diethyl Aluminum Chloride TABLE VI Catalyst Activity Example g/g-cat/hour No. (I)

12 3,000

13 455

14 137

15 305 (1) Grams of polymer per gram of catalyst per hour.

WHAT WE CLAIM IS: 1. A process for preparing a supported, chemically-modified titanium tetrachloride catalyst component comprising the sequential steps of: (a) suspending a finely-divided polymer in a solution of a magnesium compound in an alkanoloffrom 1 to 4 carbon atoms (b) vaporising alkanol from the suspension of step (a) to deposit a complex of the magnesium compound with the alkanol on the surface of the finely-divided polymer (c) adding an aluminium alkyl compound to the product of step (b) suspended in a liquid hydrocarbon; and (d) adding titanium tetrachloride compound to the suspension of step (c); the polymer employed in step (a) being an organic thermoplastic or thermosetting polymer, the particles of such polymer having at least one dimension not exceeding 600 microns; the magnesium compound employed in step (a) having the structure: MgX2.nH2O where X is Cl, F, Br, I, NO3, OCH3, OCOCH3, or -OOCH, and n is not greater than 6; the magnesium compound employed in step (a) constituting from 1 to 60 weight % of the combined weight of the finely-divided polymer and the magnesium compound; the aluminium alkyl compound employed in step (c) being a dialkyl aluminium hydride, dialkyl aluminium halide, or trialkyl aluminium; the quantity of the aluminium alkyl employed in step (c) being not in excess of the quantity that will react with the magnesium compoundalkanol complex carried on the polymeric support; and the quantity of the titanium tetrach chloride employed in step (d) being at least molarly equivalent to the quantity of the aluminium alkyl compound employed in step (c).
2. A process according to claim 1, in which the alkanol is vaporized in step (b) by direct

distillation from the suspension.
3. A process according to claim 1, in which a hydrocarbon is added to the suspension formed in step (a) and the alkanol is vaporized in step (b) by co-distillation from the suspension with the hydrocarbon.
4. A process according to claim 1 or 2 or 3, in which said magnesium compound is magnesium chloride, magnesium methoxide, magnesium acetate or magnesium nitrate.
5. A process according to any of claims 1 to 4, in which the polymer is an organic thermoplastic polymer.
6. A process according to any preceding claim, comprising the sequential steps of: (a) suspending the finely-divided organic thermoplastic or thermosetting polymer in a 1-4 carbon atom alkanol solution of a magnesium compound, (b) distilling a portion of the alkanol from the suspension of step (a), (c) adding a liquid hydrocarbon to the slurry remaining at the conclusion of step (b) (d) distilling a hydrocarbon-alkanol mixture from the slurry of step (c) until the boiling point of the distillate rises to the boiling point of the hydrocarbon, (e) adding diethyl aluminium chloride to the slurry remaining at the conclusion of step (d), (f) adding titanium tetrachloride to the suspension of step (e); and (g) distilling hydrocarbon from the slurry of step (f) to remove any unreacted titanium tetrachloride as a distillate with the hydrocarbon; the magnesium compound employed in step (a) constituting 5-25 weight % of the combined weight of the finely-divided polymer and the magnesium compound;.
7. A supported, chemically-modified titanium tetrachloride catalyst component whenever prepared by the method claimed in any of claims 1 to 6.
8. A process for preparing an olefin polymerization catalyst which comprises reacting an aluminium alkyl compound with the supported, chemically-modified, titanium tetrachloride catalyst component claimed in Claim 7, the aluminium alkyl compound being a dialkyl aluminium hydride, dialkyl aluminium halide or trialkyl aluminium.
9. A process according to Claim 8, in which the aluminium alkyl is a trialkyl aluminium.
10. A polymerization catalyst whenever prepared by the method claimed in claim 8 or 9.
11. A process for polymerizing a mono- 1-olefin comprising contacting the mono- 1-olefin with a catalyst as claimed in Claim 10.
12. A process, according to claim 11, for polymerizing ethylene, comprising the steps of: (a) suspending a polymerization catalyst as claimed in Claim 10 in a liquid hydrocarbon to form a slurry; (b) passing ethylene gas through the slurry formed by step (a) for a period of less than 5 minutes at substantially atmospheric pressure and at a temperature of less than 20"C; and (c) contacting ethylene with the ethylene-treated catalyst formed in step (b) at a temperature above 20"C and at a pressure above atmospheric pressure.
13. Polyethylene whenever prepared by the process claimed in claim 12.
14. A process for producing polyethylene comprising preparing a supported, chemically modified titanium tetrachloride catalyst component by the sequential steps of: (a) suspending the finely-divided organic thermoplastic or thermosetting polymer in a 1-4 carbon atom alkanol solution of a magnesium compound, (b) distilling a portion of the alkanol from the suspension of step (a): (c) adding a liquid hydrocarbon to the slurry remaining at the conclusion of step (b) (d) distilling a hydrocarbon-alkanol mixture from the slurry of step (c) until the boiling point of the distillate rises to the boiling point of the hydrocarbon, (e) adding diethyl aluminium chloride to the slurry remaining at the conclusion of step (d), (f) adding titanium tetrachloride to the suspension of step (e); and (g) distilling hydrocarbon from the slurry of step (f) to remove any unreacted titanium tetrachloride as a distillate with the hydrocarbon; the particles of the polymer having at least one dimension not exceeding 600 microns; the magnesium compound being chloride methoxide. acetate or nitrate and constituting from 5 to 25 weight % of the combined weight of polymer and magnesium compound; the quantity of diethyl aluminium chloride employed in step (e) being not in excess of the quantity that will react with the magnesium compound alkanol complex carried on the polymeric support; and the quantity of titanium tetrachloride employed in step (d) being at least molarly equivalent to the quantity of the diethyl aluminium chloride employed in step (e); reacting the catalyst component with a trialkyl aluminium to form a polymerisation catalyst; suspending the catalyst in a liquid hydrocarbon to form a slurry; passing ethylene gas through the slurry for a period of less than 5 minutes at substantially atmospheric pressure and at a temperature of less than 20"C; and contacting ethylene with the ethylene treated catalyst at a temperature above 20"C and at a pressure above atmospheric pressure.
15. Polyethylene whenever produced by the process claimed in claim 14.
16. A process for preparing a supported, chemically modified titanium tetrachloride catalyst component according to any one of Examples 1 to 3 and 10 to 15 hereinbefore.