Preparation of Aluminoxanes

Europaisches Patentamt European Patent Office © Publication number: 0 463 555 A2 Office europeen des brevets

EUROPEAN PATENT APPLICATION

@ Date of filing: 19.06.91

© Priority: 28.06.90 US 544878 © Applicant: ETHYL CORPORATION Ethyl Tower 451 Florida Boulevard @ Date of publication of application: Baton Rouge Louisiana 70801 (US) 02.01.92 Bulletin 92/01 @ Inventor: Sangokoya, Samuel Ayodele © Designated Contracting States: 11888 Old Hammond Hwy, No. 16 BE DE FR GB IT Baton Rouge, Louisiana 7081 6(US)

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Rank Xerox (UK) Business Services 1 EP 0 463 555 A2 2

This invention relates generally to a process for using salt hydrates (acid-base products). preparing aluminoxanes and more specifically to I have now discovered a process for making the preparation of aluminoxanes, such as hydrocarbylaluminoxanes using hydrates which methylaluminoxane, by reacting a hydrocarbyl alu- greatly reduces the loss of aluminum values. minum compound with a hydrate of an alkali or 5 In accordance with this invention, there is pro- alkaline earth metal hydroxide such as lithium hy- vided a process for preparing a hydrocar- droxide monohydrate. bylaluminoxane comprising reacting a hydrocar- Vandenberg, U.S. 3,219,591, reported the cata- bylaluminum compound with a hydrate of an alkali lytic activity of compounds formed by the reaction metal hydroxide. of trialkyl aluminum with limited amounts of water 10 Hydrocarbylaluminoxanes may exist in the in the polymerization of epichlorohydrin and other form of linear or cyclic polymers with the simplest oxiranes. Shortly thereafter Manyik et al., U.S. compounds being a tetraalkylaluminoxane such as 3,242,099, reported the use of aluminoxanes, made tetramethylaluminoxane, (CH3)2AIOAI(CH3)2, or by reacting 0.85 - 1.05 moles of water with tetraethylaluminoxane, (C2H5)2AIOAI(C2H5)2. The hydrocarbyl aluminum compounds such as 15 compounds preferred for use in olefin polymeriza- triisobutyl aluminum, as co-catalysts with certain tion catalysts usually contain 4 to 20 of the repeat- transition metal compounds in the polymerization ing units: of mono-unsaturated a-olefins; e.g., ethylene and propylene. Isobutylaluminoxane was also made by adding an equal mole quantity of water to a hep- 20 tane solution of triisobutyl aluminum. Manyik et al. U.S. 3,300,458 prepare al- kylaluminoxane by passing a hydrocarbon through $ A I -0 } water to form a wet hydrocarbon and mixing the wet hydrocarbon and an alkyl 25 aluminum/hydrocarbon solution in a conduit. where R is Ci-Cs alkyl. Schoenthal et al. U.S. 4,730,071 show the The hydrates which are useful in the invention preparation of methylaluminoxane by dispersing include hydrates of alkali or alkaline earth metal water in toluene using an ultrasonic bath to cause hydroxides such as, for example, lithium, sodium, the dispersion and then adding a toluene solution 30 potassium, barium, calcium, magnesium, and of trimethyl aluminum to the dispersion. Schoenthal cesium hydroxides. These compounds can form et al. U.S. 4,730,072 is similar except it uses a high hydrates which readily lose water which permits speed, high shear-inducing impeller to form the the reaction to be carried out at room temperature water dispersion. or below. For example, sodium mono- and Edwards et al. U.S. 4,772,736 describe an al- 35 dihydrate, barium hydroxide octahydrate, potas- uminoxane process in which water is introduced sium dihydrate, cesium monohydrate and the like. below the surface of a solution of hydrocarbyl Especially preferred is LiOH*1H20 which is a well aluminum adjacent to a stirrer which serves to defined monohydrate. It is believed that these hy- immediately disperse the water in the hydrocarbon droxide hydrates differ from salt hydrates (acid- solution. 40 base products) in that the water of hydration is The preparation of alkyl aluminoxanes from FV more loosely bound through hydrogen bonding. AlOLi, formed by reacting AIR3 and anhydrous Any hydrocarbyl aluminum compound capable lithium hydroxide, and R2AICI2 has been reported of reacting with the hydrate to form an aluminoxane in the literature, for example, Ueyama et al., In- can be used. This includes, for example, trialkyl organic Chemistry, 12, No. 10,2218 (1973) and 45 aluminum, triaryl aluminum, mixed alkyl aryl alu- Aoyazi et al., Inorganic Chemistry, 12, No. 11,2702 minum, and the like. ~~ (1973). The preferred aluminum compounds are the Sinn et al. U.S. 4,404,344 prepare alkyl aluminum compounds, especially trialkyl alu- methylaluminoxane by adding trimethyl aluminum minum compounds such as trimethyl aluminum, to a slurry of CuSCU* 5H20 in toluene. Introducing 50 triethyl aluminum, triisobutyl aluminum, tri-n-hexyl water as a metal hydrate controls its reactivity with aluminum, tri-octyl aluminum and the like. Of these, the trimethyl aluminum. Kaminsky et al. U.S. the more preferred are the tri-Ci -4-alkylaluminum 4,544,762 is similar except it uses an aluminum compounds. sulfate salt hydrate to supply the water. Likewise, Of the various hydrocarbyl aluminoxanes, Welborn et al. U.S. 4,665,208 describe the use of 55 methylaluminoxane and ethylaluminoxane are the other metal salt hydrates such as FeSO4*7H20 as more difficult to prepare because of the extreme a water source in preparing aluminoxane. Substan- reactivity of trimethyl aluminum and triethyl alu- tial loss of aluminum values usually results when minum with water. The most reactive is trimethyl

2 3 EP 0 463 555 A2 4 aluminum and accordingly the most preferred em- filtered and the solid residue was washed with bodiment is the application of the process to make toluene. The clear filtrate and washings were com- methylaluminoxane. bined and analyzed for soluble aluminum content. The reaction is carried out in an inert solvent. Analysis showed that 85% of the original aluminum Any inert solvent can be used. The preferred sol- 5 content remained in the resulting solution product. vents are aliphatic and aromatic hydrocarbons. Ar- omatic hydrocarbons are more preferred such as Example 2 toluene, xylene, ethylbenzene, cumene, mesitylene and the like. The most preferred solvent is toluene. TMA (15.0 g, 0.20 mol) was dissolved in The concentration of the hydrocarbyl aluminum w toluene (200 ml) and LiOH*1H20 (6.6 g, 0.16 mol) compound in the inert solvent can range from 1 - was slowly added at room temperature, in batches, 30 weight percent. A preferred concentration is 5 - over about 15 minutes. The reaction was exother- 20 weight percent, more preferably 10-15 weight mic, and the temperature of the mixture rose to percent. 55 °C within 30 minutes. As the temperature start- The mole ratio of aluminum compound to alkali 15 ed to cool down, the slurry was filtered and the or alkaline earth metal hydroxide hydrate can vary residue was washed with toluene. The clear filtrate widely such as, for example, from 2:1 to 1:2. Ratios and washings were combined and analyzed for of about 2 moles of aluminum compound to about soluble aluminum content. The solution (204 g) was 1.5 moles of monohydrate are preferred. found to contain 2.28 wt % Al which is equivalent Unlike the reactions of prior art salt hydrates 20 to 86% of the initial aluminum content. which require heating to temperatures of 70 °C or more, and usually are accompanied by a 40-60% Example 3 loss of Al values, the process of the invention can be carried out at room temperature or below. This TMA (15 g, 0.20 mol) was dissolved in heptane reduces the loss of aluminum values to as low as 25 (80 ml) and then LiOH*1H20 (4.4 g, 0.10 mol) was 10 to 15 percent. The minimum temperature is that added slowly at room temperature over a period of at which the reaction will proceed and the maxi- about 1 hour. Gas evolution was vigorous, but the mum temperature is selected to optimize the yield reaction was only slightly exothermic (unlike the of aluminoxane without excessive loss of aluminum reaction in toluene). The reaction temperature rose values. Suitable temperatures range, for example, 30 to 35 °C before starting to cool down. The mixture from -20 °C to 60 °C with -5°C to 40 °C being was stirred for about 2.5 hours and then filtered. preferred. Representative reaction times depend The solid residue was washed with heptane. The upon the reaction temperature and aluminum alkyl combined washings and filtrate (100 g) analyzed concentration, for example, typically from 1 to 20 for 4.80 wt % Al, which is equivalent to 89% of the hours or more. 35 initial aluminum content. The process produces high yield of soluble hydrocarbylaluminoxane which has good selective Example 4 activity as a catalyst component for olefin polymerization. This preparation was carried out as described The invention is further illustrated by, but is not 40 in Example 2, except that the mixture was stirred intended to be limited to, the following examples. for a longer period (4.5 hours). The combined All experiments were carried out under inert at- filtrate and washings contained 0.142 mol of Al, mosphere conditions, using Schlenk glassware and which is 71% of the original aluminum content. vacuum line, in conjunction with a N2-dry box. Solvents were dried using standard methods. Filtra- 45 Example 5 tion and vacuum distillation were done inside the N2-dry box and distillates collected in a trap at This preparation was carried out as described -78° C. in Example 2, except that instead of a 4:3 molar ratio (TMA/LiOH*1H20) an equimolar of TMA and Example 1 50 LiOH*1H20 was employed. The reaction was com- pleted in about 2 hours. The combined filtrate and Trimethylaluminum (TMA) (15.0 g, 0.20 mol) washings (266 g) contained 1 .55 wt % of Al which was dissolved in toluene (200 ml). The solution was is equivalent to 76.5% of the initial aluminum used. cooled to -20 °C and then LiOH*1H20 (4.4 g, 0.10 mol) was added. Gas evolution was very slow at 55 Example 6 this point. The mixture was allowed to warm slowly to 0°C (within 30 minutes) and then kept at this Methylaluminoxane (MAO) prepared according temperature for about 20 hours. The slurry was to Example 1 was used in the polymerization of

3 5 EP 0 463 555 A2 6 ethylene. Dry toluene (750 ml) was charged to a 2:1. one liter autoclave which had been heated and purged with nitrogen for at least one hour. The The process of claim 5 wherein the mole ratio toluene solution of aluminoxane (7 mmoles Al) was of hydrocarbylaluminum to hydrate is about added and the system was heated to 80° C. A 1:1. freshly prepared solution of bis(cyclopentadienyl)- zirconiumdichloride (Cp2ZrCl2) containing 0.34 mmoles was added. The reactor was then pressur- ized to 60 psi with ethylene. Polymerization was conducted for ten minutes, 10 after which the polyethylene was dried and 77 g were collected.

Example 7 15 Methylaluminoxane (MAO) prepared according to Example 2 was used in the polymerization of ethylene. The polymerization was carried out as described in Example 6. The weight of dried poly- mer was 84.6 g. 20

Example 8

Methylaluminoxane (MAO) prepared according to Example 4 was also employed in the poly- 25 merization of ethylene. The procedure described in Example 6 was closely followed. The resulting dried polyethylene weighed 110.5 g.

Claims 30

A process for preparing a hydrocarbylaluminoxane comprising reacting a hydrocarbylaluminum compound with a hydrate of an alkali or alkaline earth metal hy- 35 droxide.

2. A process for preparing methylaluminoxane comprising reacting a solution of trimethylaluminum in an inert hydrocarbon sol- 40 vent with an alkali or alkaline earth metal hydroxide hydrate selected from lithium, sodium, potassium, barium, calcium, magnesium, and cesium hydroxide hydrate including mixtures thereof. 45

3. The process of claim 1 or 2 wherein the hydrate is LiOH*1H20.

4. The process of claim 1, 2 or 3 wherein the 50 reaction temperature is from -20° C to 60° C.

5. The process of any of the preceding claims wherein the mole ratio of hydrocarbylaluminum to hydrate ranges from 2:1 to 1:2. 55

6. The process of claim 5 wherein the mole ratio of hydrocarbylaluminum to hydrate is about