PROCESS FOR MAKING ALUMINOXANES

Abstract: Water, hydrocarbylaluminum (e.g., trimethylaluminum), and organic solvent (e.g., toluene) are fed to a reactor in controlled proportions and under temperature control to form a dilute reaction product mixture of specified composition and concentration. This solution is then processed so as to form at least two product mixtures, one of which is essentially aluminoxane-free hydrocarbylaluminum dissolved in organic solvent, and another of which is a concentrated solution of organoaluminum compounds composed in essence of hydrocarbylaluminum and hydrocarbylaluminoxane in organic solvent in which the amount aluminoxane far exceeds the amount of hydrocarbylaluminum. It is advantageous to add the water to a solvent solution of a hydrocarbylaluminum compound and/or an aluminoxane by feeding the water through an orifice which is surrounded by a flow of solvent which carries the water into the solvent solution of hydrocarbylaluminum compound and/or aluminoxane.

Description: PROCESS FOR MAKTNG ALUMINOXANES TECHNICAL FIELD This invention relates to the production of alkylaluminoxanes by use of a novel cost-effective process which makes it possible to operate with no significant yield losses. More specifically this invention relates to an improved process for making aluminoxanes by the addition of free water to hydrocarbylalurninum compounds such as trimethyl- aluminum. BACKGROUND Aluminoxanes are of commercial importance as components used in forming polymerization and oligomerization catalysts. They are formed by controlled hydrolysis of aluminum alkyls such as trimemylaluininum. While the hydrolysis can be effected by use of hydrated crystalline salts such as the pentahydrate of copper sulfate or the like, this approach can lead to the presence in the product of small amounts of metal residues which can act as catalyst poisons. Thus the use of water itself to effect controlled hydrolysis of the aluminum alkyl in a hydrocarbon medium has proven to be the preferred general approach. Over the years considerable effort has been devoted to processes for conducting such controlled hydrolysis using water as the hydrolytic reagent. For example, Vandenberg, U.S. 3,219,591 reported the catalytic activity of compounds formed by the reaction of trialkylaluminum with limited amounts of water in the polymerization of epichlorohydrin and other oxiranes. Shortly thereafter, Manyik, et al. U.S. 3,242,099 reported the use of aluminoxanes, made by reacting 0.85 - 1.05 moles of water with hydrocarbylaluminum compounds such as triisobutylaluminum, as co-catalysts with certain transition metal compounds in the polymerization of mono-unsaturated alpha- olefins; e.g. ethylene and propylene. Isobutylaluminoxane was also made by adding an equal mole quantity of water to a heptane solution of triisobutylaluminum. Manyik, et al. U.S. 3,300,458 describe preparing alkylaluminoxane by passing a hydrocarbon through water to form a wet hydrocarbon and mixing the wet hydrocarbon and an alkyl aluminum/hydrocarbon solution in a conduit. Manyik, et al. in Journal of Catalysis Volume 47 published in 1977, at pages 197-209, refer to studies with catalysts formed from certain chromium compounds and partially hydrolyzed triisobutylaluminum. Schoenthal, et al. U.S. 4,730,071 shows the preparation of methy laluminoxane by dispersing water in toluene using an ultrasonic bath to cause the dispersion and then adding a toluene solution of trimemylaluminum to the dispersion. Schoenthal, et al. U.S. 4,730,072 is similar except it uses a high speed, high shear-inducing impeller to form the water dispersion. Edwards, et al. U.S. 4,772,736 describes an aluminoxane preparation process in which water is introduced below the surface of a solution of hydrocarbylaluminum adjacent to a stirrer which serves to immediately disperse the water in the hydrocarbon solution. Bottelberghe U.S. 4,908,463 describes an aluminoxane preparation process in which a static mixer is used to disperse water in a solvents and then impinges the water dispersion with a hydrocarbylaluminum solution in a T-shaped reactor. The solution is then removed to a finished reaction vessel which is stirred and can have a cooling means such as a heat-exchanger in an external pump-around loop. Bottelberghe U.S. 4,924,018 describes formation of aluminoxanes by feeding a hydrocarbon solution of aluminum alkyl to a reaction zone, feeding an emulsion of 0.5-10 weight percent water in an inert solvent to the reaction zone, the ratio of moles of water to aluminum atoms being 0.4-1 : 1 , and removing reaction mixture from the reaction zone to maintain a constant liquid level therein. The feeds are controlled so that the average residence time in the reaction zone is no more than about one hour. Smith, Jr., et al. U.S. 4,937,363 discloses forming aluminoxanes by forming in a column a thin falling film of a solution of aluminum alkyl in an inert solvent while passing an upward countercurrent flow of wet inert gas through the column. Davis U.S. 4,968,827 teaches introducing water into the free space above the surface of a cold (-80°C up to -10°C) solution of hydrocarbylaluminum compound in a liquid hydrocarbon which is being intensively agitated. Deavenport, et al. U.S. 5,041 ,585 and 5,206,401 teach preparation of aluminoxanes by contacting an organic solvent containing trialkylaluminum with atomized water. Preformed aluminoxane can be included in the solution as reaction moderator. Becker et al. U.S. 5,403,942 and Graefe et al. U.S. 5,427,992 describe batch processes for preparing aluminoxanes by injecting water into trialkylaluminum solutions using respectively, a jet loop reactor and a rotor/stator machine to mix the water and trialkylaluminum. U.S. 4,960,878; 5,041,584 and 5,086,024 also describe processes in which water and certain organoaluminum compounds are caused to interact. Despite all such intensive study and research, a need exists for practical, commercially-feasible process technology capable of producing concentrated aluminoxane solutions with no significant yield losses, especially where such technology can be applied both to batch and to continuous modes of operation. This invention is deemed to fulfill the foregoing need in a highly efficient manner. A problem associated with the direct addition of free water to solvent solution of hydrocarbylaluminum in order to form aluminoxanes is plugging of the orifice of the water delivery system. This is caused by local over oxidation of the hydrocarbylalu- minum to form insoluble products and can occur even when using a solution or dispersion of water in solvent. The plugging problem requires the orifice to be periodically cleaned which interrupts the aluminoxane production process. A method for reducing or eliminating the plugging problem has also been found. SUMMARY OF THE INVENTION The present invention is applicable to, and constitutes improvements in, processes wherein water, hydrocarbylaluminum, and organic solvent are used in forming hydrocarbylaluminoxane. In accordance with this invention the feeds of these materials to the reactor are controlled to form a dilute reaction product mixture which is then processed so as to form at least two product mixtures, one of which consists essentially of hydrocarbylaluminum dissolved in organic solvent, and another of which is a concen¬ trated solution of organoaluminum compounds (i.e. , a mixture consisting essentially of hydrocarbylaluminum and hydrocarbylaluminoxane) in organic solvent in which the amount aluminoxane far exceeds the amount of hydrocarbylaluminum therein. As used herein, the term "hydrocarbylaluminum" is distinct from and does not include "aluminoxane" or "hydrocarbylaluminoxane". In accordance with one embodiment of this invention the improvement comprises (a) feeding hydrocarbylaluminum, an organic solvent, and water to a reactor under temperature conditions and in proportions that form a solution containing in the range of 0.5 to 15 wt% of aluminum as hydrocarbylaluminum and hydrocarbylaluminoxane, and wherein for each mole part of aluminum in the solution, there is in the solution in the range of 0.1 to 0.9 mole part of hydrocarbylaluminum; and (b) separating the solution into a first portion consisting essentially of 0.5 to 15 wt% of aluminum as hydro¬ carbylaluminum dissolved in organic solvent, and a second portion consisting essentially of 3 to 20 wt% of total aluminum as hydrocarbylaluminum and hydrocarbylaluminoxane, and wherein for each mole part of aluminum in solution in said second portion, there is in the range of only 0.03 to 0.3 mole part of hydrocarbylaluminum. Substantially the entire balance of dissolved aluminum in the second portion is composed of hydrocarbylaluminoxane. In preferred embodiments, the first portion is recycled to the reactor. In particularly preferred embodiments, the process is conducted on a continuous basis, particularly in operations wherein the first portion is continuously recycled to the reactor. In conducting the process on a continuous basis it is highly desirable, though not essential, to perform the reaction in a continuous loop reactor or pump-around system such as described in USP 5,599,964. It is also advantageous, though not essential, to utilize the modes of water feed or injection described therein. It is advantageous, though not essential, to make aluminoxane compositions by the addition of water to a solvent solution of a hydrocarbylaluminum and/or an aluminoxane, by feeding the water through an orifice which is surrounded by a flow of solvent which carries the water into the solvent solution. Thus this invention also provides an improved process for making aluminoxane compositions by the addition of water to a solvent solution comprising a hydrocarbylaluminum compound and/or an aluminoxane in an organic solvent, wherein the improvement comprises feeding said water through an orifice which is surrounded by a flow of solvent which carries said water into said solvent solution of hydrocarbylaluminum and/or aluminoxane. These and other embodiments of the invention will be still further apparent from the ensuing description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 through 5 are various schematic process flow diagrams of plant facilities that can be used in the practice of this invention. Fig. 6 is a schematic diagram showing a pumparound reactor system used in the embodiment of the process of the invention described in Example 7. Fig. 7 is a schematic diagram showing a water injection system used in carrying out the embodiment of the process of the invention described in Example 7. Fig. 8 is a schematic diagram showing a pumparound reactor system used in the embodiment of the process of the invention described in Examples 8 and 9. Fig. 9 is a schematic cross-sectional view of a water and solvent injector and in¬ line mixing system used in the embodiment of the process of the invention described in Examples 8 and 9. Fig. 10 is a schematic diagram showing a pumparound reactor system used in the embodiment of the process of the invention described in Example 10. Fig. 11 is a schematic diagram showing a water injection system used in carrying out the embodiment of the process of the invention described in Examples 10 and 11. In Figs. 1 through 5 like numerals represent like components among the several views, and the drawings thereof are presented for purposes of illustration, and thus are simplified in the sense that valves, motors, holdup tanks, filters, additional pumps, etc., are not depicted therein. Such details are unnecessary for an understanding of this invention and can be provided as desired in accordance with well-established chemical engineering principles. FURTHER DESCRIPTION OF THE INVENTION Hydrocarbylaluminoxanes may exist in the form of linear, cyclic, caged or poly- meric strucmres with the simplest compounds being a tetraalkylaluminoxane such as tetramethylaluminoxane, (CH 3 ) 2 A10A1(CH 3 ) 2 , or tetraethylaluminoxane, (C 2 H 5 ) 2 AlOAl- (C 2 H 5 ) 2 . The compounds preferred for use in olefin polymerization catalysts are oligomers, and these usually contain 4 to 20 of the repeating units: R -(Al-O)- where R is C,-C 8 alkyl and is preferably methyl. The exact structure of aluminoxanes has not been defined and they may contain linear, cyclic, caged and/or cross-linked species. Methylaluminoxanes (MAOs) normally have lower solubility in organic solvents than higher alkylaluminoxanes and the memylaluminoxane solutions tend to be cloudy or gelatinous due to the separation of particles and agglomerates. In order to improve the solubility of the memylaluminoxane, higher alkyl groups, e.g. C 2 to C 20 can be included such as by hydrolyzing a mixture of trimethylaluminum with up to 50 mole percent of a C 2 to Qo alkylaluminum compound such as, for example, triethylaluminum, tri-n- propylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum or a triarylaluminum. The MAO's can also contain up to 20 mole percent, based on aluminum, of moieties derived from amines, alcohols, ethers, esters, phosphoric and carboxylic acids, thiols, alkyl and aryl disiloxanes and the like to further improve activity, solubility and/or stability. Except as the context otherwise indicates by virtue of the specific materials specified for use (e.g., in the Examples hereinafter), such modified and mixed methyl-higher alkyl or aryl aluminoxanes are included in the term " methy laluminoxane" as used herein. Any hydrocarbylaluminum compound or mixture of compounds capable of reacting with water to form an aluminoxane can be used. This includes, for example, trialkylaluminum, trialkeny .aluminum, triarylaluminum, tricycloalkylaluminurn, tri- aralkylaluminum, mixed alkyl arylaluminum, or dialkylaluminum hydride. Preferred hydrocarbylaluminum compounds are the alkylaluminum compounds, especially trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, trioctylaluminum, and the like. Of these, the more preferred are the tri-C M -alkylaluminum compounds. It will be appreciated that when the separated solution consisting essentially of hydrocarbylaluminum compound(s) and solvent is recycled, small amounts of aluminoxane may also be recycled therewith, although the less, the better. The process of the invention thus includes not only the addition of water to hydrocarbylaluminum compounds, but to mixtures of aluminoxanes and hydrocarbylaluminum compounds as well. The reaction is carried out in an inert solvent. Any inert solvent can be used. The preferred solvents are aliphatic and aromatic hydrocarbons. Aromatic hydrocarbons are more preferred. Examples include toluene, xylene, ethylbenzene, cumene, mesitylene and the like. The most preferred solvent is toluene. The water can be added to the reaction either neat and/or dissolved or dispersed in the solvent. The reactants are combined in proportions to provide from 0.5 to 8.0 moles of hydrocarbylaluminum compound per mole of water. When making methy laluminoxanes, the proportions are preferably from 1.3 to 6.0 moles of trimemylaluminum and more preferably from 2.0 to 4.0 or 5.0 moles per mole of water. Suitable reaction temperatures fall in the range of from -70 to 100 C C, with a preferred range being -50 to 50 °C. A more preferred range is from -20 to 20 °C. The following examples illustrate preferred procedures for conducting the process of this invention. All percentages given in these examples are by weight, and are approximate as they are largely based on computer simulations from bench scale studies. It is to be clearly understood that these examples are for the purposes of illustrating current best modes contemplated for carrying out the operations. They are not intended to limit, and should not be construed as limiting, the invention to the specific details set forth therein. EXAMPLE 1 To a continuous loop reactor system such as depicted in Fig. 1 hereof composed in essence of reactor 70, pump 72, cooler 30, and lines 10, 34, 36 and 38 (see also commonly-owned USP 5,599,964), are continuously charged via line 10, 718 kg/hr of 3.8 wt% of trimemylaluminum (TMA) in toluene, 13 kg/hr of toluene and 1.36 kg/hr of water. This provides a ratio of water to aluminum of 0.2. The reaction mixture is maintained at a temperature of about 2°C by circulation through cooler 30. The reaction product after degassing in degasser 40 is approximately 730 kg/hr of 96.3 wt% toluene, 3.0 wt% TMA, 0.7 wt% methylaluminoxane (MAO). With a 10 micron filter in the system (not shown), virtually no solids are detected, and thus under these reaction conditions, no aluminum is lost as solids. Continuous flash in still unit 50 operated at 105 mmHg and 55 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of about 712 kg/hr of a solution of approximately 3.0 wt% TMA and 97 wt% toluene, and (b) bottoms in line 22 at the rate of approximately 18 kg/hr of a product solution composed of about 27% MAO, 3% TMA, and 70% toluene. Heater 48 raises the temperature of the feed to unit 50 and thus supplies the heat used in the operation of unit 50. Addition via line 26 of 6 kg/hr of 100% TMA to the condensed overhead in line 24 regenerates the TMA feed rate, which is recycled to the loop reactor system. EXAMPLE 2 In this case the flow scheme as depicted in Fig. 2 is used. This is essentially the same arrangement as in Fig. 1 except that the bottoms in line 22 are directed to blending tank 52 to enable adjustment of concentration through dilution with additional solvent. Thus in this case there are continuously charged to the reactor 70, 454.5 kg/hr of 6.0 wt% TMA in toluene, 8.4 kg/hr of toluene and 1.36 kg/hr of water. This provides a ratio of water to aluminum of 0.2. The reaction mixture in the continuous loop reactor system is maintained at a temperature of about 2°C. The reaction product after degassing in degasser 40 is approximately 462 kg/hr of 94% toluene, 5% TMA, and 1 % MAO. With a 10 micron filter in the system (not shown), virtually no solids are detected. Thus under these reaction conditions, no aluminum is lost as solids. Continuous flash in unit 50 operated at 105 mmHg and 55 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of approximately 448.5 kg/hr of a mixmre of about 4.7% TMA and 95.3% toluene, and (b) bottoms in line 22 at the rate of approximately 13.5 kg/hr of a solution of about 35.8% MAO, 4.5% TMA, and 59.7% toluene. The overhead is liquefied in condenser 54 and recycled to the loop reactor system or section composed of reactor 70, pump 72, cooler 30, and lines 10, 34, 36 and 38, all as in Example 1. Addition via line 32 of approximately 4.3 kg/hr of toluene to the bottoms in tank 52 gives approximately 18 kg/hr of a desired product concentrate composed of about 27% MAO, 3% TMA, and 70% toluene. Addition via line 26 of 6 kg/hr of 100% TMA to the condensed overhead in line 24 regenerates the TMA feed rate, which is recycled to the loop reactor system. EXAMPLE 3 The system depicted in Fig. 3 is used in this example. The only difference between the systems of Figs. 1 and 3 resides in the product workup portion of the operation. Thus to the continuous loop reactor are continuously charged 419.5 kg/hr of 6.5 wt% TMA in toluene, 4.5 kg/hr of toluene and 1.36 kg/hr of water. This provides a ratio of water to aluminum of 0.2. The reaction mixture is maintained at a temperature of about 2°C. The reaction product after degassing is approximately 423.5 kg/hr of a mixmre composed of about 94% toluene, 5% TMA, and 1 % MAO. With a 10 micron filter (not shown) in the system, virtually no solids are detected. Thus under these reaction conditions, no aluminum is lost as solids. Continuous flash at 105 mrnHg and 55 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of approximately 404 kg/hr of a solution composed of about 5.1 % TMA and 94.9% toluene, and (b) bottoms in line 22 at the rate of about 19.3 kg/hr of a mixture containing about 69.3% toluene, 5.7% TMA and 25% MAO. The bottoms stream is transferred to a 10- stage stripper column 56, where it is introduced at the top, and 8.2 kg/hr of toluene vapor at 110°C is introduced at the bottom. The resulting overhead is approximately 9.6 kg/hr of a solution of approximately 5.1% TMA and 94.9% toluene. The two overhead streams after liquefaction in respective condensers 54 and 58 are merged into line 24 and combined with 6 kg/hr of 100% TMA from line 26 to regenerate the TMA feed rate, which is recycled to the loop reactor section. The stripper bottoms product is a concentrate of approximately 27% MAO, 3% TMA and 70% toluene obtained at the rate of about 18 kg/hr. EXAMPLE 4 Used is the system of Fig. 4 which includes a loop reactor arrangement as in Examples 1-3 above and a wiped film evaporator 60. Except for use of wiped film evaporator 60 instead of stripper column 56, the systems of Figs. 3 and 4 are essentially the same. The continuous feeds to the reactor 70 are 718 kg/hr of 3.8 wt% TMA solution, 135 kg/hr of toluene and 1.36 kg/hr of water, which equates to a ratio of water to aluminum of 0.2. The reaction mixture is maintained at a temperature of about 2°C. The reaction product after degassing in unit 40 is approximately 730 kg/hr of a mixmre composed of about 96.3 wt% toluene, 3.0 wt% TMA and 0.7 wt% MAO. With a 10 micron filter in the system, virtually no solids are detected. Thus under these reaction conditions, no aluminum is lost as solids. Continuous flash in unit 50 operated at 210 mmHg and 72 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of about 690 kg/hr of a solution composed of approximately 2.95 wt% TMA and 97.05 wt% toluene, and (b) bottoms in line 22 at the rate of about 40 kg/hr of approximate composition 12.2% MAO, 3.8% TMA and 84% toluene. The bottoms are continuously fed to the wiped film evaporator 60 operated at 105 mmHg and 55 °C which gives as overhead, about 22 kg/hr of a solution composed of approximately 3.7 wt% TMA and 96.3 wt% toluene, and as bottoms at the rate of about 18 kg/hr, a solution composed of about of 27% MAO, 4% TMA and 69% toluene. The two overhead streams after liquefaction in respective condensers 54 and 58 are merged and combined with 6 kg/hr of 100% TMA from line 26 to regenerate the proper TMA feed composition and rate, which composition is recycled to the loop reactor section. EXAMPLE 5 To the continuous loop reactor section of a system such as depicted in Fig. 1 hereof are continuously charged via line 10, 614 kg/hr of 4.3 wt% of trimemylaluminum (TMA) in toluene, 10 kg/hr of toluene and 1.36 kg/hr of water. This provides a ratio of water to aluminum of 0.2. The reaction mixmre in the loop reactor section is maintained at a temperature of about 2°C by circulation through cooler 30. The reaction product after degassing in degasser 40 is approximately 624 kg/hr of a mixmre of approximate composition 95.7 wt% toluene, 3.4 wt% TMA, 0.8 wt% methylaluminoxane (MAO). With a 10 micron filter in the system (not shown), very little solids are detected, and thus under these reaction conditions, essentially no aluminum is lost as solids. Continuous flash in still unit 50 operated at 105 mmHg and 55 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of about 606 kg/hr of a solution of approximately 3.3 wt% TMA in toluene, and (b) bottoms in line 22 at the rate of approximately 18 kg/hr of a product solution composed of about 27% MAO, 3% TMA, and 70% toluene. Addition via line 26 of 8 kg/hr of 80% TMA in toluene to the condensed overhead in line 24 regenerates the TMA feed, which is recycled to the loop reactor system. Example 6 illustrates a modification wherein less stringent process control is used in order to achieve process economies . In this embodiment, small losses in yield based on aluminum used are accepted and effectively dealt with, all in return for improved overall economies of plant operation. EXAMPLE 6 The overall system used is as schematically depicted in Fig. 5. It will be seen that this system is basically the same as that of Fig. 1 except that degasser unit 40 of Fig. 1 is replaced by settling and degasser unit 44. Unit 44 is designed to both de-gas the reaction product from the continuous loop reactor section and to cause solids in the reaction product to settle and be filtered from the liquid phase before the liquid reaction product is partitioned in unit 50. Thus, to the continuous loop reactor section comprising reactor 70, pump 72, cooler 30 and lines 10, 34, 36 and 38 are continuously charged via line 10, 364 kg/hr of 5.0 wt% of trimethylaluminum (TMA) in toluene, 22 kg/hr of toluene and 1.36 kg/hr of water, which corresponds to a ratio of water to aluminum of 0.3. The reaction mixture in the loop reactor section is maintained at a temperamre of about 2°C by circulation through cooler 30. The reaction product after degassing and solids removal in unit 44 is approximately 374 kg/hr of a mixmre of approximate composition 95.3 wt% toluene, 3.3 wt% TMA, 1.3 wt% methy laluminoxane (MAO). With a 10 micron filter in unit 44, a loss of about 3 mole % of total aluminum is incurred. Continuous flash in still unit 50 operated at 105 mmHg and 55 °C gives a separation into (a) an overhead or take-off in line 20 at the rate of about 356 kg/hr of a solution of approximately 3.3 wt% TMA in toluene, and (b) bottoms in line 22 at the rate of approximately 18 kg/hr of a product solution composed of about 27% MAO, 3% TMA, and 70% toluene. Addition via line 26 of 8 kg/hr of a solution of 80 wt% TMA in toluene to the condensed overhead in line 24 regenerates the TMA feed, which is recycled to the loop reactor section. When operating with solids formation as in Example 6, the solution from the reactor section should contain a limited amount of finely-divided aluminum-containing solids. In general, the total amount of aluminum in the solids should be not more than 10% of the total weight of all aluminum species present (i.e., in solution and in the solids). These finely divided solids, will typically have particle sizes in a range that will pass through a 50 micron filter but will be retained by a 10 micron filter. In preferred embodiments, this invention thus provides a continuous process of forming methy laluminoxane. The process involves in stage (a), continuously feeding trimemylaluminum, water, and organic solvent to a reactor under temperature conditions and in proportions that form a solution containing a total in the range of 0.5 to 8 wt% of aluminum as trimethylaluminum and methylaluminoxane, and wherein for each mole part aluminum in the solution, the solution contains in the range of 0.10 to 0.63 (most preferably in the range of 0.16 to 0.63) mole parts of trimethylaluminum. In stage (b) the reaction solution formed in (a) is continuously degassed. Then in stage (c), the degassed solution is continuously flashed to form an overhead which is essentially 0.5 to 8 wt% of aluminum as trimethylaluminum dissolved in organic solvent, and bottoms composed essentially of 4 to 20 wt% of aluminum as methy laluminoxane and trimemylaluminum. For each mole part of aluminum in solution in these bottoms, there is in the range of no more than 0.03 to 0.3 (most preferably in the range of 0.05 to 0.20) mole part of trimemylaluminum. Stage (d) involves recycling as a portion of the feed in stage (a), at least a portion of the overhead of stage (c). For such continuous operation, makeup trimemylaluiriinum and makeup inert solvent are included in the feed in stage (a), and most preferably trimethylaluminum and inert solvent of the feed of stage (a) are composed or made up of (i) the recycle from stage (d), (ii) the makeup trimethyl¬ aluminum, and (iii) the makeup inert solvent. In this way, the proportions of (a) are maintained by this feed. As indicated in the Drawings, it is desirable to combine the makeup trimethylaluminum (and more preferably also a portion of the makeup inert solvent) with the recycle from stage (d) before the feed in stage (a). Likewise, it is most preferred to mix together the water and a portion of the inert solvent of the feed of stage (a) before these are fed in stage (a). For this purpose the use of the modes of water feed or injection described in commonly -owned USP 5,599,964 or as described hereinafter in connection with Figs. 6 through 11 and Examples 7 through 11, are particularly advantageous. A particularly preferred way of effecting the feeds in stage (a) comprises combining the makeup trimemylaluminum and a portion of the makeup inert solvent with the recycle from stage (d) and feeding this combined mixmre in stage (a), and in addition, combining the water and another makeup portion of inert solvent and feeding this combined mixmre in stage (a). We mm now to the improved process of the invention for feeding water to a solvent solution of a hydrocarbylaluminum compound and/or an aluminoxane. In the embodiment of the process of the invention which is illustrated in Fig. 6, water, trimemylaluminum (TMA) and toluene are continuously injected into the inlet of an in-line mixer 1 which is located in a reactor loop 2. Alternatively TMA can be fed to the reactor at a different point, for example, between pump 4 and cooler 5 as illustrated in Fig. 8. The water and TMA react and the reaction mixture, which includes product methy laluminum (MAO) and unreacted TMA, are circulated through loop 2 to degassing tank 3 where methane gas is vented. The reaction mixmre is then pumped back to the inlet of in-line mixer 1 such as an IKA Works in-line disperser, whose rotor operates at speeds of from about 7,000 to 13,000 rpm, by pump 4. The heat of reaction is maintained within a selected temperature range by use of cooler 5. MAO product in solvent, which contains unreacted TMA, is continuously drawn off through line 6. TMA and solvent can be flashed from the crude MAO product and returned, for example, to degasser 3 or to line 2 ahead of the in-line mixer. The in-line mixer produces a homogeneous reaction zone and the large volume recycle of product stream provides both heat absorption and dilution of the reactants, especially the water, such that localized overheating and/or any significant temperature rise is avoided. The continuous introduction of reactant and withdrawal of product permits a constant concentration of reactants to be maintained in a steady state reaction which helps to achieve a more uniform and reproducible product in improved yields. It also permits the sequential production of a variety of products simply by adjustment of the reactant feed rates and ratios. Fig. 7 illustrates a device which is suitable for introducing water to a solvent solution of aluminum alkyl in accordance with the process of the invention illustrated in Fig. 6. Water passes through a capillary tube 13 which is coaxially arranged within mbe 15. The tip 14 of mbe 13 is recessed about 1 to 2 mm from the end 16 of mbe 15. Solvent passing through mbe 15 sweeps water from tip 14 of tube 13 and carries the water into the TMA in solvent and pumparound mixmre of TMA and MAO in solvent which enters through mbes 18 and 19 respectively and then into the mixing device (not shown). By using a flow of solvent to surround and sweep the water to the TMA containing mixmre, plugging of me end of the water delivery tube due to aluminum oxide formation can be avoided. Fig. 9 illustrates another device which is suitable for introducing water to a reaction zone in accordance with the process of the invention as illustrated in Fig. 8. The device is associated with reactor/ stator in-line mixer 1 which is driven by motor 12. Water passes through a capillary mbe 13 which is coaxially arranged within tube 15 which has a diameter of, for example, 3.0 mm. The tip 14 of capillary mbe 13 is recessed about 1 to 2 mm from the end 16 of mbe 15. Solvent passing through mbe 15 sweeps water from tip 14 into the reaction zone 17 where the water reacts with a TMA- MAO-solvent mixmre which enters reaction zone 17 through tube 19. The reaction mixmre exits from rotor/stator in-line mixer 1 through outlet 21. The inner diameter of capillary tube 13 can be selected to deliver either a stream or individual droplets of water. For example, inner diameters of from 0.001 to 0.1 mm. The end of the water injection tube or nozzle should be positioned so that the water sprays out without contacting the walls of the solvent conduit. Otherwise, the water may collect on the walls because of the two immiscible liquid phases. In general, the ratio of the weight of the flow of solvent used to carry the water to the reaction zone to the weight of water ranges from 10 to 1 to 1000 to 1 and preferably from 25 to 1 to 150 to 1. Other suitable devices in which the end of a nozzle or mbe carrying the water is positioned within a flow of solvent can be used to introduce water to the reaction. The water can be predispersed in a portion of the solvent. The shape of the mbes or conduits is not critical and they can have other than a circular cross-section. Also, other mixing devices can be used which provide high shear in the reaction zone including, but not limited to, ultrasonic, propeller and static mixers. In fact, it was found that a good product in high yield could be obtained even when the rotor/stator mixer was turned off. The hydrocarbylaluminum compounds and aluminoxane products are protected from oxygen and moismre by means of an inert gas atmosphere, such as dry nitrogen. The volumes and flow rates of the water, solvent and recycle stream provide a very dilute concentration of water to give a more uniform hydrolysis reaction. For example, the total stream is at least 200 times the volume of water feed, preferably 5,000 times greater, and more preferably at least 8,000 times greater. The water is entirely soluble in the higher flow of solvent and plugging of the reactor, which can occur when using a continuous T-type reactor due to localized over reaction, is avoided. The result is a stable reaction without need of interruption to clear blockages. The high pump- around flow minimizes any temperature rise due to the highly exothermic hydrolysis reaction. Relative concentrations of water and hydrocarbylaluminum compound in the reaction zone can be maintained substantially constant by continually adding makeup hydrocarbylaluminum and water in the proportions that they are reacted and removed from the pumparound flow. The reaction feed and product removal rates are adjusted to give a concentration of crude aluminoxane product in solvent of from 1 to 5 weight percent. The concentration of unreacted hydrocarbylalurninum can range from 0 to 10 weight percent. When making MAO, the MAO product concentration generally ranges from 20 to 30 weight percent and unreacted TMA from 2 to 10 weight percent based on the total weight of MAO, TMA and solvent. Feed rates depend upon the size of the reactor used. The crude aluminoxane product can be concentrated by the removal of solvent and unreacted alkylaluminum compound. The invention is further illustrated by, but is not intended to be limited to, the following examples. EXAMPLE 7 Example 7 was run using a reactor and water injection system similar to that illustrated in Figs. 6 and 7 to produce MAO. The flow rates were 2.80 kg/hour toluene, 0.04 kg/hour water, 2.26 kg/hour of 10 weight percent TMA in toluene and 13.18 kg/hour of the pumparound mixmre of 96.1 weight percent toluene 1.6 weight percent TMA and 2.3 weight percent MAO. The reaction temperature was about 6°C. The mbe and channel dimensions are given in Table 1. The tip 14 of water mbe 13 was recessed about 1 mm from the end 16 of solvent mbe 15, whose end 16 in turn extended abut 3 mm beyond the outlet of MAO tube 18. The in-line mixer 1 was a LKA Works UTL 25 with a dispersion chamber and "fine dispersing elements" operating at about 11 ,700 φm. No pluggage of capillary mbe 13 was observed during 100 minutes of run time. EXAMPLE 8 Example 8 was run using a reactor and water injection system similar to that illustrated in Figs. 8 and 9 to produce MAO. The TMA in toluene was injected into the pumparound flow between the cooler and the pump. The flow rates were 2.55 kg/hour toluene, 0.02 kg/hour water, 3.03 kg/hour 10 weight percent TMA in toluene, and 682 kg/hour of the pumparound mixmre of 1.9 weight percent TMA, 1.9 weight percent MAO and 96.2 weight percent toluene. The reaction temperature was about 6°C. The mbe and channel dimensions are given in Table 1. The tip 14 of water capillary mbe 13 was recessed about 1 mm from the end 16 of solvent mbe 15. The in-line mixer 1 was the same as used in Example 7 but the rotor was not turned on (0 rpm). No pluggage of capillary mbe 13 was observed during 2 hours of run time. EXAMPLE 9 Example 9 was run using an apparams and mixer similar to that used for Example 8 to produce MAO. The flow rates were 2.0 kg/hour toluene, 0.05 kg/hour water, 5.4- 5.7 kg/hour 10 weight percent TMA in toluene, and 682 kg/hour of pumparound mixmre of 5.6 weight percent TMA, 3.4 weight percent MAO and 91 weight percent toluene. The reaction temperamre was about 11 °C. The mbe and channel dimensions are given in Table 1. The in-line mixer was operated at 7,000 rpm. No pluggage of capillary mbe 13 was observed during 6 hours of operation. However, when the injection system was changed such that tip 14 of water capillary mbe 13 extended slightly past end 16 of solvent mbe 15, tip 14 plugged with white aluminum oxide in less than 1 minute after starting the water injection. 'ID = inner diameter in mm for each mbe in list 2 OD = outer diameter in mm for each mbe in list 3 N/A = not applicable (tube 18 does not exist) EXAMPLE 10 The apparams used is shown in Figs. 10 and 11. The water was injected into the pumparound loop 2 ahead of mixer 1 rather than at the inlet. Injector system 25 as illustrated in Fig. 10 has the solvent mbe 15 and water capillary mbe 13 arranged about perpendicular to the flow of solvent, product MAO and unreacted TMA in pumparound loop 2. Tip 14 of tube 13 is recessed about 1 mm from the end 16 of tube 15. The inner diameter of water capillary mbe 13 is 0.55 mm and its outer diameter is 0.65 mm. The inner diameter of solvent tube 15 is 1.4 mm and its outer diameter is 3.2 mm. The inner diameter of loop 2 is 9.4 mm and its outer diameter is 12.7 mm. The remainder of the system shown in Fig. 10 is the same as the system used in Example 8 (Fig. 8). The feeds were 12.3 weight percent TMA in toluene under nitrogen pressure, toluene (10 ppm water) under nitrogen pressure and deuterated water (purged with helium). The TMA solution and water were fed by metering pumps and the nitrogen was fed under nitrogen pressure. The degasser was charged with 3.65 kg (4.09 L) of TMA solution and the bulk temperamre was brought down to 2-3 °C. The flow through the mixer was 522 kg/hr and the mixer was started and set to run at 7500 rpm (t = 0). The toluene feed was started at t = 40 minutes (average: 1.5 kg/hr, 16.3 gmol/hr); the TMA feed at t = 48 minutes (average: 6.0 kg/hr: 0.7 kg/hr TMA + 5.26 kg/hr toluene, 10.2 gmol/hr TMA, 57.2 gmol/hr toluene); and the water feed at t = 140 min (0.4 g min, 1.33 gmol/hr H 2 O). The reaction zone temperature was 2-3 °C, the H 2 O /TMA mole feed ratio was 0.13, the bulk/H 2 O flow volume ratio was about 24,000 and the bulk/H 2 O mass flow ratio was about 22,000. The expected Al weight percent was 3.7 weight percent and the residence time constant was 29 minutes. Crude MAO was continuously withdrawn to maintain a constant level in the system and collected at t = 323 minutes, 6.3 time constants. After t = 248 minutes, the mixer was turned off and two samples were analyzed to look at steady state. The results are shown in Table 2. (a) sampled just after the mixer was turned off (b) mixer off EXAMPLE 11 The apparams used is shown in Figs. 10 and 11 except that part of the pump¬ around flow was sent through a second cooler arranged in parallel with cooler 5 and re- entered loop 2 after the crude MAO product removal point. This run was made without cleaning the water injection apparams from Example 10. Total run time = 11 hours. The rotor of mixer 1 was not turned on (rpm = 0). The feed materials were the same as for Example 10 except that deionized water was used. The degasser was charged with 6.4 kg, 7.2 L of TMA solution (12.3%) and the bulk temperamre was brought down to 1-3 °C. The flow through mixer 1 was 545 kg/hr. The TMA feed was started (t = 0) (average: 8.2 kg/hr, i.e., 1.0 kg/hr TMA + 7.2 kg/hr toluene; 14.0 gmol/hr TMA + 78 gmol/hr toluene) and then at t = 6 minutes the toluene feed was started (average: 1.2 kg/hr, 12.8 gmol/hr. The water feed was started at t = 21 minutes (0.89 g/min, 3.0 gmol/hr H 2 O). The reaction zone temperamre was 1-3 °C, the H 2 O TMA molar feed ratio was 0.21, the bulk/H 2 O flow volume ratio was about 11,000 and the bulk/hr mass flow ratio was about 10,000. The expected Al weight percent was 3.99 weight percent and the residence time constant was 41 minutes. The crude MAO was continuously withdrawn to maintain a constant level and at t = 213 minutes, 4.7 time constants collection was begun and ended at 273 minutes, 6.1 time constant with 10.9 kg collected. Analysis of a sample taken at t = 270 minutes gave 3.73 wt percent Al, 7.5 weight percent TMA, 72% Al as TMA. No visible solids were immediately observed in the crude MAO samples. After about one week of storage at -15 °C a very faint film of solids appeared at the bottom of the sample bottles. Aluminum yield was estimated to be greater than 99% . This feeding process of this invention is extraordinarily useful for adding water to aluminum alkyls without pluggage, so as to lower production costs through less downtime, less solvent recycle and better aluminum utilization. It provides a way to continuously add water to an aluminum alkyl and/or aluminoxane stream without process pluggage in immediate process piping. As long as the solvent is warm, it is also be possible to use this invention to inject water at subfreezing temperamres. The lower temperatures is expected to yield improvements in the reactor, particularly for the MAO pumparound production modes. Unless otherwise expressly stated, all boiling temperatures set forth in this disclosure and in the claims hereof are specified at atmospheric pressure.

Claims: Claims 1. A process wherein hydrocarbylaluminum, water, and organic solvent are fed to a reactor to form hydrocarbylaluminoxane, said process comprising (a) feeding such materials to the reactor under temperamre conditions and in proportions that form a solution containing in the range of 0.5 to 15 wt% of aluminum as hydrocarbylaluminum and hydrocarbylaluminoxane, and wherein for each mole part of aluminum in the solution, there is in the solution in the range of 0.1 to 0.9 mole part of hydrocarbyl¬ aluminum; and (b) separating the solution into a first portion consisting essentially of 0.5 to 15 wt% of aluminum as hydrocarbylaluminum dissolved in organic solvent, and a second portion consisting essentially of 3 to 20 wt% of total aluminum as hydrocarbyl¬ aluminoxane and hydrocarbylaliiminum, and wherein for each mole part of aluminum in solution in said second portion, there is in the range of no more than 0.03 to 0.3 mole part of hydrocarbylaluminum. 2. A process according to Claim 1 which further comprises recycling at least part of said first portion to the reactor. 3. A process according to Claim 1 wherein (a) and (b) are conducted on a continuous basis. 4. A process according to Claim 3 which further comprises continuously recycling at least part of said first portion to the reactor. 5. A process according to Claim 1 wherein (a) and (b) are conducted on a continuous basis and wherein the separation of (b) is effected by continuous flashing or distillation. 6. A process according to Claim 1 wherein the hydrocarbylaluminum is trimethylaluminum and the aluminoxane is methy laluminoxane. 7. A process according to Claim 6 wherein: (a) the trimethylaluminum, water, and organic solvent are continuously fed to a reactor under temperamre conditions and in proportions that form a solution containing a total in the range of 0.5 to 8 wt% of aluminum as dissolved hydrocarbylaluminum and methy laluminoxane species, and wherein for each mole part of aluminum in the solution there is in the solution in the range of 0.10 to 0.63 mole part of trimethylaluminum; (b) the reaction solution formed in (a) is continuously degassed; (c) the degassed solution is continuously flashed to form an overhead consisting essentially of 0.5 to 8 wt% of aluminum as trimethylaluminum dissolved in organic solvent, and bottoms consisting essentially of 4 to 20 wt% of aluminum as methy laluminoxane and trimethylaluminum, and wherein for each mole part of aluminum in solution in said bottoms, there is in the range of no more than 0.03 to 0.3 mole part of trimethylaluminum; and (d) at least a portion of the overhead of (c) is recycled as a portion of the feed in (a). 8. A process according to Claim 7 wherein makeup trimethylaluminum and makeup inert solvent are included in the feed in (a). 9. A process according to Claim 8 wherein trimethylaluminum and inert solvent of the feed of (a) are made up of the recycle from (d) and said makeup trimethylaluminum and said makeup inert solvent. 10. A process according to Claim 9 wherein the makeup trimethylaluminum is combined with the recycle from (d) before being fed in (a). 11. A process according to Claim 9 wherein the makeup trimethylaluminum and a portion of the makeup inert solvent are combined with the recycle from (d) before being fed in (a). 12. A process according to Claim 9 wherein the water and a portion of the inert solvent of the feed of (a) are mixed together before being fed in (a). 13. A process according to Claim 9 wherein the makeup trimethylaluminum and a portion of the makeup inert solvent are combined with the recycle from (d) before being fed in (a), and wherein the water and another makeup portion of the inert solvent of the feed of (a) are mixed together before being fed in (a). 14. A process according to Claim 7 wherein the solvent consists essentially of one or a mixmre of inert hydrocarbons. 15. A process according to Claim 7 wherein the solvent consists essentially of toluene. 16. A process according to Claim 7 wherein the reactor is a loop reactor. 17. A process according to Claim 7 wherein in (d) essentially the entire overhead of (c) is continuously recycled to form a part of the feed of (a). 18. A process according to Claim 7 wherein the solvent consists essentially of one or a mixmre of liquid inert hydrocarbons that has a boiling point or range below 250 °C; wherein the bottoms of (c) are fed to the top of a countercurrent stripper column and wherein one or a mixmre of inert hydrocarbons that has a boiling point or range below 250 °C is fed into the bottom of said stripper column such that the stripper column yields (i) an overhead consisting essentially of trimethylaluminum and one or a mixture of inert hydrocarbons that has a boiling point or range below 250°C, and (ii) bottoms consisting essentially of methy laluminoxane, trimemylaluminum and one or a mixmre of inert hydrocarbons that has a boiling point or range below 250°C, and wherein the overhead from said stripper column, and the overhead of (c) are recycled in (d) to form a part of the feed of (a). 19. A process according to Claim 18 wherein the reactor is a loop reactor. 20. A process according to Claim 19 wherein said one or a mixmre of inert hydrocarbons in both cases is essentially entirely composed of toluene. 21. A process according to Claim 7 wherein the solvent consists essentially of one or a mixture of inert hydrocarbons that has a boiling point or range below 250 °C; wherein the bottoms of (c) are fed to a wiped film evaporator to separate the bottoms into (i) an overhead consisting essentially of frimethylaluminum and one or a mixture of inert hydrocarbons that has a boiling point or range below 250 °C, and (ii) bottoms consisting essentially of memylaluminoxane, trimethylaluminum and one or a mixture of inert hydrocarbons that has a boiling point or range below 250°C; and wherein the overhead from said wiped film evaporator, and the overhead of (c) are recycled in (d) to form a part of the feed of (a). 22. A process according to Claim 21 wherein the reactor is a loop reactor. 23. A process according to Claim 22 wherein said one or a mixmre of inert hydrocarbons in both cases is essentially entirely composed of toluene. 24. A process according to Claim 7 wherein said temperamre conditions and proportions in (a) are such that for each mole part of aluminum in said solution of (a) there is in said solution of (a) in the range of 0.16 to 0.63 mole part of trimethyl¬ aluminum; and wherein for each mole part of aluminum in solution in the bottoms from the continuous flashing in (c), said solution contains in the range of no more than 0.05 to 0.20 mole part of trimethylaluminum. 25. A process according to Claim 7 wherein the solution formed in (a) also contains finely-divided alummum-containing solids, the aluminum content of said solids being not more than 10% of the total weight of aluminum in said dissolved hydrocarbyl- aluminum and memylaluminoxane species, and in said aluminum-containing solids; and wherein said aluminum-containing solids are continuously removed from the reaction solution formed in (a) . 26. A process according to Claim 25 wherein said temperamre conditions and proportions in (a) are such that for each mole part of aluminum in said solution of (a) there is in said solution of (a) in the range of 0.16 to 0.63 mole part of trimethyl¬ aluminum; and wherein for each mole part of aluminum in solution in the bottoms from the continuous flashing in (c), said solution contains in the range of no more than 0.05 to 0.20 mole part of trimethylaluminum. 27. A process according to Claim 26 wherein the reactor is a continuous loop reactor, and wherein the inert solvent in (a) and (c) is one or a mixmre of inert liquid hydrocarbons that has a boiling point or range below 250 °C. 28. A process according to any of the preceding claims taken individually wherein the hydrocarbylaluminum is fed to the reactor as a solution in an organic solvent, and wherein the water is fed through an orifice which is surrounded by a flow of organic solvent which carries said water into said solvent solution of hydrocarbylaluminum and/or aluminoxane. 29. A process according to Claim 28 wherein said water is fed through a first conduit which is surrounded by a second conduit which contains a flow of said solvent, the outlet of said first conduit being recessed from the outlet end of said second conduit. 30. A process according to Claim 29 wherein the outlet end of said first conduit is recessed at least about 1 mm from the outlet end of said second conduit. 31. A process according to Claim 28 wherein the ratio of the weight of said flow of solvent to the weight of water is from 10 to 1 to 1000 to 1. 32. A process according to Claim 31 wherein the rate of the weight of said flow of solvent to the weight of water is from 25 to 1 to 250 to 1. 33. A process according to Claim 28 wherein said hydrocarbylaluminum compound is trimethylaluminum and said aluminoxane composition is a methyl- aluminoxane. 34. An improved process for making aluminoxane compositions by the addition of water to a solvent solution comprising a hydrocarbylaluminum compound and/or an aluminoxane in an organic solvent, said process comprising feeding said water through an orifice which is surrounded by a flow of solvent which carries said water into said solvent solution of hydrocarbylaluminum and/or aluminoxane. 35. The process of Claim 34 wherein said water is fed through a first conduit which is surrounded by a second conduit which contains a flow of said solvent, the outlet of said first conduit being recessed from the outlet end of said second conduit. 36. The process of Claim 35 wherein the outlet end of said first conduit is recessed at least about 1 mm from the outlet end of said second conduit. 37. The process of Claim 34 wherein the ratio of the weight of said flow of solvent to the weight of water is from 10 to 1 to 1000 to 1. 38. The process of Claim 37 wherein the rate of the weight of said flow of solvent to the weight of water is from 25 to 1 to 250 to 1. 39. The process of Claim 34 wherein said hydrocarbylaluminum compound is trimethylaluminum and said aluminoxane composition is a memylaluminoxane.

Inventors: BURT EDWARD A, FARRITOR ROBERT E, ROBERG JOHN K, BURT, EDWARD, A., FARRITOR, ROBERT, E., ROBERG, JOHN, K.
Applicants: ALBEMARLE CORP, ALBEMARLE CORPORATION
Application year: 1997
Main classification: C07F5
IPC codes: C07F5