Method for purifying organoaluminium compounds

Abstract

The invention relates to a method for purifying organoaluminium compounds which includes a step of sedimenting an organoaluminium compound to separate a clarified stream and a stream with an elevated slurry content; and a step of filtering the clarified stream on an inorganic membrane to obtain a purified product. The invention makes it possible to obtain highly purified and highly efficient organoaluminium compounds having a slurry content of less than 0.1 wt.%. The invention is also simple and energy-efficient due to the absence of energy-intensive centrifuging and / or vacuum distillation steps which generate waste that requires subsequent recovery. The invention also makes it possible to reduce the consumption rates of aluminium and olefins during the production of organoaluminium compounds.

Description

[0001] METHOD FOR PURIFYING ORGANOALUMINUM COMPOUNDS

[0002] Field of technology to which the invention relates

[0003] The present invention relates to a method for purifying organoaluminum compounds (OACs), such as triethylaluminum (TEA), triisobutylaluminum (TIBA), diisobutylaluminum hydride (DIBAH), other aluminum alkyls and their derivatives by filtration on inorganic membranes.

[0004] State of the art

[0005] Organoaluminum compounds have a wide range of applications in various processes. For example, document EP 0130607 [Union Carbide, published July 2, 1984] indicates that the polymerization of ethylene in the presence of a chromium catalyst can be significantly improved by adding a suitable organoaluminum compound, which helps both increase the reaction rate and reduce catalyst consumption. The use of organoaluminum compounds with metallocene catalysts as a neutralizer of poisons that reduce catalyst activity is also known [US 5614457, Fina Technology, published March 25, 1997].

[0006] The quality of semiconductor materials, in the synthesis of which alkylaluminum compounds, such as trimethylaluminum (TMA), are also used, largely depends on the impurities contained directly in the AOC.

[0007] Consequently, the efficiency of using AOCs in all the above-described areas depends on the impurities they contain, which means that the processes of obtaining highly pure or concentrated AOCs, in particular, purification processes, are the most important stages of AOC production.

[0008] Methods for purifying aluminum alkyls by settling are known [Korneev, N.I. Chemistry and Technology of Organoaluminum Compounds. Moscow: Chemistry, 1979, pp. 187-189]. This process is effective in removing large particles, but does not remove fine particles smaller than 50 microns, which are present in suspended aluminum alkylsulfide. Another disadvantage of this process is the significant time required to prepare a single batch of products.

[0009] Centrifugation is a more effective method for separating the bulk of impurities. Improved, but increasingly complex, centrifugation systems for AOS are being developed to remove fine solid particles. However, even modernized systems fail to achieve the required AOS purity.

[0010] European patent EP 1259516 [Akzo Nobel, published September 24, 2003] discloses a method for purifying organometallic compounds, such as TMA, by recrystallization from a solvent upon cooling. The organometallic compound is first mixed with a solvent to form a solution, and then recrystallized from the solvent upon cooling.

[0011] The main disadvantages of this method include the need to cool the solvents below 0°C, as well as their regeneration and recycling for the recrystallization of the organic organic compound. These processes lead to increased energy consumption. Furthermore, the solution described above is only applicable to organometallic compounds with carbon atoms ranging from 1 to .

[0012] A method for producing AOC is known from patent RU 2460733 [EKTOS-Volga Open Joint-Stock Company, published 10.09.2012], which involves the interaction of aluminum, hydrogen, olefin, and recycled AOC in an organic solvent at elevated temperature and pressure, followed by purification of the AOC solution from finely dispersed solid impurities by filtration. Before filtration, the AOC solution is further settled for 4-15 hours at a temperature of 10-30°C and with an AOC content in the initial solution of 40-70 wt.%.

[0013] This method is limited to products with an AOC content of 40 to 70% by weight in the feedstock. Furthermore, the method requires two lengthy settling stages, both for the feedstock prior to filtration and for the purified product itself in a separate vessel, as well as solvent distillation from the product under vacuum, which significantly reduces the energy efficiency of the process. It is also worth noting the use of solvents for filter cleaning, which contain sludge and traces of AOC and must then be sent for disposal.

[0014] The closest to the present solution is the invention in document EP 0024462 [Conoco, Inc., published February 17, 1981], which describes the filtration of triethylaluminum (TEA) from a solution consisting of TEA itself, a solvent, and aluminum impurities in the form of solid particles. To obtain a product suitable for the synthesis of fatty alcohols, the solid impurities are removed by using alternating tubular filter systems to ensure the continuous extraction of high-quality aluminum alkyls.

[0015] The following are significant disadvantages of this solution: a) the need to use solvents to empty the filtration feed tanks and, accordingly, their disposal; b) the need to use purified high-pressure inert gas to carry out the filter cleaning process, which can lead to cavitation of the filtration unit recycle circuit pump; c) the need to monitor the sludge content in the filtration feed tank (no more than 20 wt.%) with periodic unloading and further cleaning; d) the need for two or more filtration feed tanks to ensure continuous filtration; d) limitation of AOS filtration - the range of permissible solvent content is from 15 to 55 wt.%; e) the need to use filters with a pore size of 2-5 microns, which leads to the fact that a large proportion of small sludge particles remains in the product; g) limitation of the content of solid impurities (sludge) in the stream incoming for filtration - no more than 15 wt.%.

[0016] All of the inventions described above have a number of drawbacks that prevent maximum efficiency in the AOS cleaning process. Therefore, the search for an effective cleaning method is urgent.

[0017] Disclosure of invention

[0018] The objective of the present invention is to develop an effective method for purifying AOS such as TEA, TIBA, DIBAG, tri-n-hexylaluminum (TNGA), ethylaluminum sesquichloride (EAS), diethylaluminum chloride (DEAC), etc., from sludge by filtration on inorganic membranes.

[0019] The technical result consists in obtaining highly purified and highly efficient AOS, with a sludge content of less than 0.1 wt.%.

[0020] An additional technical benefit is the simplicity and energy efficiency of the process solution due to the elimination of energy-intensive centrifugation and / or vacuum distillation steps, which generate waste requiring subsequent disposal. Another additional technical benefit is the reduction in aluminum and olefin consumption rates in the AOS production process.

[0021] The specified technical problem is solved, and the required technical result is achieved by a method for purifying an organoaluminum compound, which includes: a) a stage of sedimentation of an organoaluminum compound with the separation of a clarified flow / layer and a flow with an increased sludge content, which is optionally sent to the beginning of the synthesis of the organoaluminum compound as a seed and / or for disposal; and b) a stage of filtration of the clarified flow on an inorganic membrane, the pore size of which can vary from 10 to 1000 nm, with the production of purified organoaluminum compound.

[0022] At the filtration stage, the clarified stream is separated into purified AOC - permeate, and into retentate, which is preferably sent for recycling within the filtration unit to maintain the operation of the unit, and / or is sent for recycling as a seed to the AOC synthesis stage, where the residual organoaluminum products in the sludge-containing stream act as an activator of fresh aluminum in the synthesis process, and unreacted aluminum from the sludge is returned to the synthesis process, which makes it possible to reduce the consumption rates of the initial raw materials, for example, aluminum and olefins, and / or can be sent in whole or in part for the disposal of waste containing AOC.

[0023] Brief description of the drawings

[0024] To explain the technical solutions that reveal the essence of the present invention, but without limiting it, Figs. 1-2 are presented.

[0025] Fig. 1 shows a diagram of a purification unit for filtration using inorganic membranes. Fig. 2 shows a diagram of the arrangement of the short and long siphons in the filtration feed tank.

[0026] Detailed description of the invention

[0027] In the following description, the terms "organoaluminum compounds" or "AOCs" denote organometallic compounds containing the Al-C bond, preferably aluminum alkyls.

[0028] The term "sludge" refers to solid compounds including unreacted aluminum powder, as well as aluminum compounds, in particular aluminum oxides and hydroxides, salts, oligomers and other low-molecular compounds, etc.

[0029] The term "retentate" refers to the AOC stream that exits the filtration unit with an increased sludge content and is recycled back to the filtration unit or as a feedstock for the AOC synthesis stage.

[0030] The term "seed" refers to a recycled stream of AOC with an increased sludge content, obtained after sedimentation or representing a retentate, and required to activate fresh aluminium at the beginning of the AOC production process.

[0031] The term "permeate" refers to the desired product, which is the sludge-free AOS.

[0032] The terms "transmembrane pressure" and "TMP" refer to the pressure difference between the membrane sides of the retentate and permeate.

[0033] The term "coarse particles" refers to solid particles larger than 200 µm in size.

[0034] In various embodiments, the present invention relates to a method for purifying organoaluminum compounds, preferably aluminum alkyls such as TEA, TIBA, DIBAG, TNGA, EASC, DEAC, etc., from sludge to obtain highly purified and highly effective products by filtration on inorganic membranes. In various embodiments of the present invention, the AOC may be in concentrated or solution form.

[0035] The organoaluminum compound before cleaning contains up to 30 wt.%, preferably up to 20 wt.% of the sludge.

[0036] The cleaning method is carried out on the installation shown in Fig. 1, which includes:

[0037] - a filtration unit, which is one or several filters Fl...Fn, containing inorganic membranes;

[0038] - one or more filtration feed tanks El...El / п, from which the AOS flow without large sludge particles is continuously fed to the filtration unit, while one or two of the tanks are sedimentation tanks;

[0039] - pump for flow 2 and retentate recycle flow 6 for membrane filtration, P1;

[0040] - optionally, a heat exchanger for cooling the retentate recycle stream, T1;

[0041] - optional, an intermediate storage tank for permeate E2 before sending the product to the loading / unloading rack or further to other synthesis processes, etc.;

[0042] - optionally, a tank for intermediate storage of permeate for backwashing EZ and a device for creating a reverse flow pulsation such as a piston pump, P2;

[0043] - optional, capacity for intermediate storage of retentate for seed E4.

[0044] In Fig. 1, stream 1, which is an unrefined AOC with a high sludge content, and which leaves the AOC synthesis stage from the reactor and / or storage tank, is directed to one or more filtration feed tanks E1...E1 / n, where at least in one tank E1 a sedimentation stage is carried out, where by gravity and / or due to the operation of the mixer, part of the sludge remains at the bottom, in the lower layer, and the purified clarified part, which is stream 2, with a sludge content of 0.2-30 wt.% is pumped out through the first siphon, which is a short siphon, to the filtration unit, which may contain one or more filters Fl...Fn, where it is purified on inorganic membranes by circulation using a centrifugal pump P1.The lower layer, through the second long siphon, from tank E1, in a flow with an increased content of sludge 8, then mixing with the retentate in tank E4, or separately, is sent to the stage of AOS synthesis as a seed, with the purpose of activating fresh aluminum and reducing the loss of unreacted aluminum.

[0045] The main part of the stream 3 leaving the filtration unit, containing 70-95 wt.%, preferably 80-90 wt.% of the total stream 2, purified from sludge, is a permeate stream, which is sent for further use in other processes, and / or to the loading / unloading rack, and / or to the intermediate tank E2.

[0046] To ensure uninterrupted membrane operation in various embodiments of the invention, when the pressure drop exceeds 0.5 MPa, the remaining permeate is sent to tank E3, from which stream 4 exits, fed to backwash the membranes using piston pump P2 or any other device capable of generating flow pulsation and / or high pressure. Backwashing can also be accomplished with high-pressure gas, preferably nitrogen.

[0047] The retentate is preferably discharged, in whole or in part, via stream 6, which is recycled within the filtration unit to maintain unit operation, and / or via stream 5 for disposal by neutralization, thermal decontamination, or other means. Retentate recycle stream 6 preferably passes through heat exchanger T1, which ensures safe and stable operation of the filtration unit, preventing uncontrolled heating and equipment deformation, and reducing the loss of organoaluminum products, which are sensitive to temperature fluctuations, as the temperature of stream 6 increases due to membrane friction and heat transfer from pump P1.

[0048] Part of the retentate from the filtration stage - 10-20 wt.% with a sludge concentration of up to 30 wt.% is sent via stream 7 to the AOC synthesis stage as a seed, thus reducing the consumption rates of aluminum and olefin to 15 wt.%, in the process of obtaining the AOC compound and / or to the intermediate tank E4 before being sent for seeding.

[0049] An inorganic membrane is a ceramic membrane. An inorganic membrane is, in particular, a porous, thin ceramic filter obtained by sintering metal oxides, such as aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), or mixtures thereof, at ultra-high temperatures. Ceramic membranes can have a symmetrical or asymmetrical structure with a macroporous supporting and active membrane layer. The macroporous support provides mechanical stability, while the active layer performs separation functions in the range from 10 to 10,000 nm—that is, in the range of microfiltration, ultrafiltration, and even nanofiltration.

[0050] The inorganic membrane always operates in continuous flow tangential filtration mode. The raw flow from the AOS or the clarified flow passes through one or more filters in the filtration unit at a high linear velocity in the range of 5-25 l / (h*mm). 2). When multiple filters are installed, the purification rate and, consequently, the yield of purified marketable product will be higher. Under the action of the TMD, the purified product passes through the membrane perpendicular to the circulation flow, while solid particles, such as sludge and high-molecular compounds, remain in the retentate.

[0051] In various embodiments, the inorganic membrane has a pore size of 10 to 1000 nm, preferably 20 to 500 nm, more preferably 50 to 200 nm.

[0052] In various embodiments, the inorganic membrane is cleaned by backwashing with a liquid, preferably permeate, or by backflushing with a high pressure gas, preferably nitrogen.

[0053] In various embodiments, the inorganic membrane is regenerated by backwashing with a pulsating device.

[0054] In various embodiments of the invention, at least one filtration feed tank has short and long siphons. The first siphon, through which the clarified AOC stream is pumped to the filtration unit, is a short siphon 1 as shown in Fig. 2. The second siphon is a long siphon 11, through which a layer with an increased sludge content, similar to the retentate obtained during filtration, is removed. In a preferred embodiment of the invention, a layer with an increased sludge content is removed through the long siphon and is recycled via stream 8 as a seed for the AOC synthesis stage for aluminum activation and / or for disposal. A distinctive advantage of the operation of siphons 1 and 11 is the absence of the need to wash the sedimentation tank, since there will be no concentration of sludge in it and, accordingly, no need for its further washing, dilution of sludge and emptying for disposal.According to the present invention, siphon 1 ensures the required quality of flow before - and - filtration, due to the absence of large sludge particles in it and / or a high concentration of these particles, while siphon ii ensures the constant removal of the lower layer with an increased sludge content further, preferably to the seed, without the need to dilute the accumulated sludge with a solvent and periodically pump it out for disposal, and without the need to interrupt the pumping of the clarified layer to the filtration stage, thereby making the filtration process continuous.

[0055] The authors of the present invention have unexpectedly discovered that the said technical result is achieved due to the fact that the AOC, preferably aluminum alkyls, for example, Lewis acids, have a chemical affinity with the membrane material, which is preferably made by sintering aluminum oxide AI2O3 of different forms - α-, β-, etc., which in this case exhibits its basic nature, the separation in such a ceramic membrane of the AOC, preferably aluminum alkyls from the sludge occurs more effectively than in a polymer or other membrane, or filter.

[0056] In various embodiments of the invention, purified AOCs can be effectively used in rubber and olefin polymerization processes as an additive to catalyst systems to improve their efficiency.

[0057] Implementation of the invention Description of test methods

[0058] 1. Free sludge was determined as follows:

[0059] A sample of liquid AOC (1-3 g) was filtered in a nitrogen box through a 0.45 µm syringe filter, washed with cyclohexane, and purged with nitrogen until constant mass. The increase in filter mass was measured, and the ratio to the initial mass of the flow passed through the filter was calculated. 2. Total aluminum was determined as follows.

[0060] A weighed sample of AOS (1-2 g) was diluted with diethyl ether (50 ml) and decomposed with 10 wt% aqueous hydrochloric acid under stirring. Inorganic aluminum was determined by complexometric titration of the aqueous solution.

[0061] 3. The determination of the granulometric composition of aluminum sludge was determined as follows.

[0062] The composition was determined using a Horiba LA-950V2 laser particle size analyzer by dispersing 20-50 mg of the concentrated sample in cyclohexane (15 ml) and comparing it with a sample of pure dried cyclohexane.

[0063] The present invention is more particularly described in the following examples, which are given solely to illustrate the present invention and do not limit it.

[0064] Example 1 (comparative)

[0065] Concentrated TIBA, with a 90% base material content, containing 9.67% sludge and an average particle size distribution of 0.81 microns, was placed in a container and allowed to settle for 12 hours. 150 kg of the clarified upper layer, containing 0.95% sludge, was then removed. The remaining 150 kg of the clarified upper layer was used as seed for the TIBA synthesis stage.

[0066] Example 2 (comparative)

[0067] A solution of DIBAG in oil with a main substance content of 76 wt.%, in the amount of 1044 kg with a sludge content of 5.93 wt.% with an average particle size distribution of 1.9 microns, was placed in a container, where it was settled for 12 hours. After that, the upper clarified layer in the amount of 626 kg, with a sludge content of 1.12 wt.%, was collected. The clarified layer was sent for centrifugation, after which 519 kg of DIBAG solution with a sludge content of 0.48 wt.%. DIBAG with a sludge concentration of 4.21 wt.%, in the amount of 107 kg, together with 418 kg of the lower layer obtained during settling, was sent to the stage of synthesis of DIBAG in oil as a seed.

[0068] Example 3 (according to the invention)

[0069] Concentrated TIBA with a main substance content of 90 wt.% in an amount of 300 kg with a sludge content of 9.67 wt.% was sent to the sedimentation stage in tank E1, where it was settled for 4 hours, after which the clarified layer with a sludge content of 7 wt.% with an average granulometric composition of 0.81 microns was collected through the first siphon in an amount of 200 kg and passed through one filtration tank containing a membrane with an average pore size of 200 nm, consisting of 99% a-Al2O3 and 1% ZrC>2. TIBA from the lower layer of tank E1 with a sludge content of 21 wt.% in an amount of 100 kg was sent to the TIBA synthesis stage as a seed.

[0070] During filtration, periodically, when permeate productivity dropped and / or TMP increased, backwashing with permeate was carried out to prevent clogging of the membrane pores and a decrease in productivity.

[0071] Purified TIBA permeate is a clear liquid with no visible sludge. The sludge content in pure TIBA is 0.073% by weight.

[0072] The TIBA retentate contained 34% by weight of aluminum sludge and was completely recycled within the filtration unit.

[0073] As a result of filtration, 185 kg (92.5 wt.% of the clarified layer) of purified TIBA was obtained.

[0074] Example 4 (according to the invention)

[0075] A solution of DIBAG in oil with a main substance content of 76 wt.%, in the amount of 1044 kg with a sludge content of 5.93 wt.% was sent to the sedimentation stage in tank El, where it settled for 6 hours, after which the clarified layer with a sludge content of 3.4 wt.% with an average particle size distribution of 1.9 microns, was collected in the amount of 875 kg and passed through one filtration tank containing a membrane with an average pore size of 200 nm, consisting of 95% a-Al2O3 and 5% TiO2. DIBAG from the lower layer of tank E1 with a sludge content of 19 wt.% in the amount of 169 kg was sent to the DIBAG synthesis stage as a seed.

[0076] During filtration, periodically, when permeate productivity dropped and / or TMP increased, backwashing with permeate was carried out to prevent clogging of the membrane pores and a decrease in productivity.

[0077] Purified DIBAG permeate is a clear liquid with no visible sludge. The sludge content in pure DIBAG is 0.045% by weight.

[0078] The DIBAG retentate with an aluminum sludge content of 7.3 wt.% was sent to the DIBAG synthesis stage as a seed in an amount of 10% of its consumption, the rest continued to circulate in the recycle of the filtration unit.

[0079] As a result of filtration, 748 kg (85.5 wt.% of the clarified layer) of purified DIBAG was obtained.

[0080] Example 5 (according to the invention)

[0081] Concentrated DEAC with a main substance content of 87.2 wt.% in an amount of 300 kg with a sludge content of 12.76 wt.% was sent to the sedimentation stage in tank E1, where it was settled for 6 hours, after which the clarified layer with a sludge content of 8.9 wt.% with an average granulometric composition of 0.1 micron was collected through the first siphon in an amount of 240 kg and passed through one filtration tank containing a membrane with an average pore size of 50 nm, consisting of 98% α-Al2O3, 1% TiO2 and 1% ZrO2. DEAC from the lower layer of tank E1 with a sludge content of 28 wt.% in an amount of 60 kg was sent to the DEAC synthesis stage as a seed.

[0082] During filtration, periodically, when permeate productivity dropped and / or TMP increased, backwashing with permeate was carried out to prevent clogging of the membrane pores and a decrease in productivity.

[0083] Purified DEAC permeate is a clear liquid with no visible sludge. The sludge content in pure DEAC is 0.018% by weight.

[0084] The DEAC retentate contained 44.6 wt.% aluminum sludge and was sent to the DEAC synthesis stage as a seed.

[0085] As a result of filtration, 192 kg (80% by weight of the initial mass) of purified DEAC was obtained.

[0086] Example 6: Polymerization with TIBA

[0087] The TIBA purified as described in Example 1 was added to the solution in a reactor, followed by the addition of a catalyst system for the synthesis of linear low-density polyethylene (PE). PE synthesis was carried out in an apparatus equipped with a stirrer and jacket at a temperature of 70-100°C. The product was then isolated and dried at a temperature of 50-80°C.

[0088] The activity of the catalyst in the presence of the cocatalyst TIBA is 5 kgPE / gcat.

[0089] Content of fine fraction (less than 375 microns) - 2.7 wt.%

[0090] Example 7: Polymerization with purified TIBA

[0091] The TIBA purified as in Example 3 was added to the solution in a reactor, followed by the addition of a catalytic system for PE synthesis. PE synthesis was carried out in an apparatus equipped with a stirrer and jacket at a temperature of 70-100°C. The product was then isolated and dried at 50-80°C.

[0092] The activity of the catalyst in the presence of purified TIBA cocatalyst is 5.9 kgPE / gcat.

[0093] Fine particle content (less than 375 µm) - 1.4 wt.% Example 8: Polymerization with DIBAG

[0094] DIBAG, purified as in Example 2, was added in solution to the catalyst system for the synthesis of SKD-ND butadiene rubber. The rubber was synthesized in an apparatus equipped with a stirrer and jacket at a temperature of 60-90°C. The product was then isolated and dried at a temperature of 80-90°C.

[0095] Complete conversion of butadiene was achieved within 1 hour of polymerization process.

[0096] Example 9: Polymerization with purified DIBAG

[0097] DIBAG, purified as in Example 4, was added in solution to the catalyst system for the synthesis of SKD-ND butadiene rubber. The rubber was synthesized in an apparatus equipped with a stirrer and jacket at a temperature of 60-90°C. The product was then isolated and dried at a temperature of 80-90°C.

[0098] Complete conversion of butadiene was achieved within 0.5 h of polymerization process.

[0099] As can be seen from Examples 3, 4, and 5, the inventive solution enables the purification of organoaluminum compounds, both in solution and concentrated form, from sludge to a content of less than 0.1 wt.%, namely, from 0.018 to 0.073 wt.%. Such organoaluminum compounds represent a finished commercial product. Moreover, a stream with an increased sludge content and retentate can be fed to the beginning of the organoaluminum compound synthesis without disposal losses, and this does not require additional equipment flushing with solvents during the purification process or the addition of solvents to the mass during the purification process. Furthermore, the return of streams with an increased sludge content, where residual organoaluminum products act as an activator for fresh aluminum during the synthesis process, and unreacted aluminum from the sludge is returned to the synthesis process, allows for a reduction in the consumption rates of the initial raw materials, such as aluminum and olefins.Examples 7 and 9 also demonstrate the effectiveness of the AOS obtained according to the present invention in processes such as polymerization. For the PE production process, an increase in the activity of the catalytic system and a decrease in the amount of non-target fraction are observed; for the rubber production process, a decrease in the reaction time is observed. This was subsequently transferred to pilot-scale testing of the synthesis of linear low-density polyethylene and SKD-N butadiene rubber, which were successful—the product obtained complies with technical specifications (TU), without a decrease in the activity of the catalytic complex or an increase in consumption rates.

Claims

CLAUSES OF THE INVENTION 1. A method for purifying organoaluminum compounds, which comprises: a) a stage of sedimentation of the organoaluminum compound with the separation of a clarified stream and a stream with an increased sludge content; and b) a stage of filtration of the clarified stream on an inorganic membrane with the production of a purified organoaluminum compound.

2. The method according to paragraph 1, wherein the stream with an increased sludge content is sent to the stage of synthesis of an organoaluminum compound as a seed and / or for disposal.

3. The method according to claim 1, wherein at the filtration stage the clarified flow is separated into purified permeate and retentate.

4. The method according to paragraph 3, wherein the retentate is sent for recycling within the filtration unit and / or is sent for recycling to the stage of synthesis of the organoaluminum compound as a seed, and / or can be sent in whole or in part for disposal.

5. The method according to claim 1, wherein the organoaluminum compound is triethylaluminum, triisobutylaluminum, diisobutylaluminum hydride, tri-n-hexylaluminum, ethylaluminum sesquichloride, diethylaluminum chloride and other aluminum alkyls.

6. The method according to claim 5, wherein the organoaluminum compound is triisobutylaluminum or diisobutylaluminum hydride.

7. The method according to paragraph 1, 5 or 6, wherein the organoaluminum compound may be in concentrated or solution form.

8. The method according to any one of paragraphs 1, 5-7, wherein the organoaluminum compound before purification contains up to 30 wt.%, preferably up to 20 wt.% of sludge.

9. The method according to claim 1, wherein the inorganic membrane is a ceramic membrane.

10. The method according to any one of paragraphs 1-9, wherein the inorganic membrane is selected from aluminum oxide, titanium oxide, zirconium oxide or a mixture thereof.

11. The method according to claim 1, wherein the filtration operates in the continuous flow tangential filtration mode.

12. The method according to claim 1, wherein the filtration step takes place in a filtration unit, which may contain one or more filters.

13. The method according to claim 1, wherein the inorganic membrane has a pore size of 10 to 1000 nm, preferably 20 to 500 nm, more preferably 50 to 200 nm.

14. The method according to claim 1, wherein a sedimentation stage is carried out in at least one filtration feed tank.

15. The method according to any one of paragraphs 1-14, wherein at the sedimentation stage, part of the sludge remains at the bottom of the filtration feed tank by gravity and / or due to the operation of the mixer.

16. The method according to paragraph 14, in which at least one filtration feed tank has a short and a long siphon, where the clarified flow of organoaluminum compound is pumped out through the short siphon, and the layer with an increased sludge content is removed through the long siphon.

17. The method according to claim 16, wherein the clarified flow of organoaluminum compound is pumped through a short siphon to a filtration unit.

18. The method according to paragraph 16, wherein a layer with an increased sludge content is removed through a long siphon and sent for recycling as a seed for the stage of synthesis of an organoaluminum compound.

19. The method according to any of paragraphs 1-17, wherein a clarified flow with a sludge content of 0.2-30 mass. % is pumped out through a short siphon.

20. The method according to claim 1, wherein the inorganic membrane is cleaned by backwashing with a liquid, preferably permeate, or by backflushing with a high-pressure gas, preferably nitrogen.

21. The method according to claim 1, wherein the inorganic membrane is regenerated by backwashing with liquid using a pulsating device.

22. The method according to claim 1, wherein the clarified stream and the retentate recycle stream in the filtration unit are pumped by one pump, preferably a centrifugal pump.

23. The method of claim 1, wherein the retentate recycle stream passes through a heat exchanger to stabilize the temperature of the stream.

24. The method of any one of claims 1-3, wherein the permeate stream represents 70-95 wt.%, preferably 80-90 wt.%, of the clarified stream and is sent for further use in other processes and / or to a loading / unloading rack and / or to an intermediate tank.

25. The method according to claim 1, wherein the clarified flow passes through one or more filters in the filtration unit at a high linear velocity in the range of 5-25 l / (h*mm 2 ) .

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