EA044431B1 - METHOD FOR SEPARATING OLEFINS OLIGOMERIZATION PRODUCTS (OPTIONS) - Google Patents

Description

Field of technology to which the invention relates

The invention relates to the field of oligomerization of olefins, in particular ethylene, in order to obtain linear α-olefins, in particular 1-hexene, used for the production of linear low, medium and high density polyethylene, poly-a-olefins for anti-turbulence additives, etc. In particular, the invention relates to a method for separating olefin oligomerization products using an evaporator.

State of the art

US Pat. No. 7,718,838 proposes several options for separating the product stream of the oligomerization reaction. Thus, one of the options is a separation method that includes unloading from the oligomerization reactor a reaction mass containing the target and by-products of the oligomerization reaction, ethylene, and a catalytic system. Next, a deactivating agent is introduced into the line for unloading the reaction mass from the oligomerization reactor to deactivate the catalytic system. After this, the reaction mass containing the deactivated catalyst system is sent to a separator to separate unreacted olefin. The reaction mass remaining after the separation of unreacted ethylene is sent to a separation column, in which the reaction mass is divided into three streams: a stream of the target oligomerization product, a solvent stream, and a heavy product stream, including by-products of the oligomerization reaction, for example, C10 olefins, a polymer by-product, and deactivated catalytic system. In this case, the stream of heavy products can be sent to an additional separation column in order to isolate C10 olefins.

In this method, there is a need for periodic cleaning of equipment from the polymer by-product, as well as strict control of the molecular weight of the polymer by-product, because low molecular weight polymer by-product will form deposits in equipment.

Application WO 2015179337 also proposes a method for separating the flow of oligomerization reaction products, which includes unloading the reaction mass from the oligomerization reactor followed by introducing a deactivating agent into the line for unloading the reaction mass from the oligomerization reactor to deactivate the catalytic system. Next, the reaction mass containing the deactivated catalyst system is sent to the first separation device, for example, a separation column or evaporator, to obtain three streams: a light stream, including ethylene and butene-1, a stream of the target product, including hexene-1 and/or octene-1. 1, as well as a solvent and a heavy stream including heavy C10+ oligomers, a polymer by-product and a deactivated catalyst system. The heavy stream is then directed to a second separation device, for example a thin film evaporator, which separates the heavy stream into a stream predominantly containing heavy liquid C10+ oligomers and a stream predominantly containing polymer by-product and deactivated catalyst system.

In accordance with this method, the entire stream, including those containing the polymer by-product and the deactivated catalyst system, is directed to a separation column. The presence of a deactivated catalyst system and polymer by-product in the flow can lead to their deposition on the walls of the equipment, as well as an increase in energy costs for separating the entire flow.

In addition, from the prior art (PERP Report Alpha Olefins 06/07-5, Nexant Inc., 2008, pp. 81-82) a method for separating ethylene oligomerization products is known, which includes the following stages:

a) unloading from the oligomerization reactor a reaction mass comprising a solvent, for example, cyclohexane, unreacted ethylene, 1-hexene, C10+ olefins, components of the catalytic system and a polymer by-product;

b) feeding the reaction mass of stage a) into the separator, in which most of the unreacted ethylene is separated and subsequently recycled into the oligomerization reactor;

c) the remaining stream from ethylene separation in step b) is treated with a deactivating agent, for example 2-ethylhexanol, to deactivate the catalyst system;

d) the stream obtained in step c) containing hexene-1, C10+ olefins, solvent, deactivated catalyst system and polymer by-product is fed to a separation column where separation occurs into two streams: an overhead stream containing hexene-1 and solvent, e.g. , cyclohexane, and a bottoms stream containing C10+ olefins, polymer by-product and deactivated catalyst system;

e) the overhead stream from step d) containing 1-hexene and a solvent, for example cyclohexane, is sent to a solvent recovery column in which the solvent is separated from a fraction predominantly containing 1-hexene;

f) the fraction, predominantly containing hexene-1, from step e) is sent to the separation of hexene-1;

g) the bottom stream from step d) containing C10+ olefins, polymer by-product and deactivated catalyst system is sent to a fractionation column, preferably

- 1 044431 containing C10 olefins, to obtain a heavy fraction containing a polymer by-product and a deactivated catalyst system.

The disadvantage of this method is the later supply of the deactivating agent of the catalytic system, which leads to an increased risk of deposits of reaction by-products in the system before the supply of the deactivating agent.

Thus, methods known from the prior art for separating the stream of olefin oligomerization products are not effective enough, and at the same time they are expensive and energy-consuming.

In this regard, one of the promising directions is the development of an effective method for separating the flow of olefin oligomerization reaction products, which will be characterized by high-quality and complete deactivation of the catalytic system in order to reduce the occurrence of side reactions outside the reactor zone, preliminary concentration of the polymer by-product and its removal from the system in order to eliminating the formation of deposits in equipment and reducing energy costs for separation.

The essence of the invention

The objective of the present invention is to develop an effective method for separating reaction products of olefin oligomerization, allowing to minimize the amount of process equipment contaminated with polymer by-product.

The technical result consists in eliminating the presence of a polymer by-product in the separation unit of the target product and return solvent, as well as in maximizing the extraction of the target product and solvent from the reaction mass, and in obtaining a heavy fraction (fraction of products with a higher degree of oligomerization), in particular the C8+ fraction , purified from the components of the catalytic system and the polymer by-product, which in turn makes it possible to use the C8+ fraction for washing the oligomerization reactor.

An additional technical result is the exclusion of the catalytic system deactivation agent from entering the return solvent.

This technical problem is solved and the achievement of the technical result is ensured by implementing a method for separating the flow of olefin oligomerization reaction products, in which one of the stages is carried out in an evaporator.

According to a first embodiment of the present invention, a process for separating olefin oligomerization products is provided, which includes the following sequence of steps:

a) unloading the reaction mass from the oligomerization reactor;

b) bringing the reaction mass into contact with a deactivation agent of the catalytic system;

c) separating a fraction containing the original olefin from the reaction mass to form a stream of oligomerization reaction products;

d) separating the oligomerization reaction product stream in the evaporator into a fraction predominantly containing the target α-olefin and a fraction containing the polymer and the remaining components of the catalytic system;

e) separating the fraction predominantly containing the target α-olefin obtained in step d) into a light fraction, in particular the C ₂ -C ₄ fraction, a target α-olefin fraction, in particular the C6+ fraction, and a heavy oligomer fraction, in particular the C8+ faction.

In accordance with a second embodiment of the present invention, a method for separating olefin oligomerization products is provided, which includes the following sequence of steps:

a) unloading the reaction mass from the oligomerization reactor;

b) bringing the reaction mass into contact with a deactivation agent of the catalytic system;

c) separating from the reaction mass a fraction containing the original olefin, in particular ethylene, to form a stream of oligomerization reaction products;

c) * directing the first part of the flow of oligomerization reaction products from stage c) to the separation stage d)*; and directing the second portion of the oligomerization reaction product stream from step c) to step d);

d) * separation of the first part of the oligomerization reaction product stream from step c)* into a light fraction, in particular the C2-C ₄ fraction, the target α-olefin fraction, in particular the C6+ fraction and the heavy fraction of oligomers, in particular the C8+ fraction, followed by the heavy fraction of oligomers, in particular the C8+ fraction at stage d);

d) separating in the evaporator the heavy fraction of oligomers, in particular the C8+ fraction from step d)* and the second part of the oligomerization reaction product stream, into a fraction predominantly containing the target α-olefin, in particular C6+, and a fraction containing the polymer and the remaining components of the catalytic system ;

e) separating a fraction predominantly containing the target α-olefin, in particular C6+, semi-

- 2 044431 calculated in step d), into a light fraction, in particular the C2-C4 fraction, a target α-olefin fraction, in particular a C6+ fraction and a heavy oligomer fraction, in particular a C8+ fraction.

The present invention makes it possible to minimize the amount of process equipment contaminated with polymer by-product.

Description of the figures

To explain the technical solutions revealing the essence of the present invention, FIGS. 1, fig. 2 and fig. 3.

In fig. 1 is a flowchart showing a sequence of steps in accordance with a first embodiment of the present invention.

In fig. 2 is a flowchart showing a sequence of steps in accordance with a second embodiment of the present invention.

In fig. 3 is a flowchart showing the sequence of steps according to Comparative Example 3.

Detailed Description of the Invention

The following is a description of various aspects of implementing the present invention.

In accordance with the present invention, the olefin oligomerization process involves reacting, under oligomerization conditions, a feedstock containing an olefin feedstock with a catalyst system that contains 1) a chromium source, 2) a nitrogen-containing ligand, and 3) an aluminum alkyl, and optionally a zinc compound.

According to the present invention, the chromium source may be organic and/or inorganic chromium compounds. The oxidation state of chromium in compounds can vary and can be +1, +2, +3, +4, +5 and +6. In general, the chromium source is a compound with the general formula _CrXn , where X can be the same or different and n is an integer from 1 to 6. X can be organic or inorganic groups.

Organic groups X can contain from 1 to 20 carbon atoms and represent an alkyl group, an alkoxy group, a carboxyl group, an acetylacetonate group, an amino group, an amido group, etc.

Suitable inorganic groups X include halides, sulfates, etc.

Examples of chromium sources include chromium(III) chloride, chromium(III) acetate, chromium(III) 2-ethylhexanoate, chromium(III) acetylacetonate, chromium(III) pyrrolide, chromium(II) acetate, chromium(IV) dioxide dichloride (CrO2Cl2 ) and etc.

The nitrogen-containing ligand included in the catalytic system is an organic compound that includes a fragment of a pyrrole ring, that is, a five-membered aromatic ring with one nitrogen atom. Suitable nitrogen- _containing ligands include, but are not limited to, pyrrole, 2,5dimethylpyrrole, lithium pyrrolide _C4H4NLi , 2-ethylpyrrole, 2-allylpyrrole, indole, 2-methylindole, 4,5,6,7tetrahydroindole. Most preferably, pyrrole or 2,5-dimethylpyrrole is used.

Alkylaluminum may be an alkylaluminum compound, as well as a halogenated alkylaluminum compound, an alkoxyalkylaluminum compound, and mixtures thereof. To increase the selectivity of the catalytic system, it is preferable to use these compounds that have not been in contact with water (not hydrolyzed), represented by the general formulas AlR ₃ , AlR2X, AlRX2, AlR2OR, AlRXOR and/or Al2R ₃ X ₃ , where R is an alkyl group, X is a halogen atom. Suitable alkylaluminum compounds include, but are not limited to: triethylaluminum, diethylaluminum chloride, tripropylaluminum, triisobutylaluminum, diethylaluminum ethoxide and/or ethylaluminum sesquichloride, or mixtures thereof. Most preferred is the use of triethylaluminum or a mixture of triethylaluminum and diethylaluminum chloride.

According to the present invention, said catalyst system can be prepared by mixing a chromium source and a nitrogen-containing ligand in a hydrocarbon solvent, followed by mixing them with an aluminum alkyl. In this case, it is preferable to additionally activate alkylaluminum using microwave irradiation (microwave irradiation).

Mixing the components of the catalytic system can be accomplished by any method known in the art. Mixing of the components of the catalytic system is carried out for from 1 minute to 30 minutes, preferably no less than 2 minutes, no less than 4 minutes, no less than 8 minutes, no less than 15 minutes, no less than 25 minutes.

Alternatively, the aluminum alkyl that is activated by microwave irradiation can be gradually mixed with other components of the catalytic system directly from the container exposed to microwave irradiation, so that the mixing time can be any convenient time without the irradiated component losing the special properties acquired under the microwave irradiation. action of microwave radiation.

The order of mixing the components of the catalytic system can be any. Preferably, the aluminum alkyl is added to the mixture of the chromium source and the nitrogen-containing ligand. Mixing of the components is carried out in the presence of a hydrocarbon solvent in any suitable device known

- 3 044431 from the prior art, for example, in a bubbling apparatus, an apparatus with a stirrer, a static mixer.

Suitable hydrocarbon solvents include, but are not limited to: 1-hexene, benzene, toluene, ethylbenzene, xylene, or mixtures thereof. Preferably, aromatic hydrocarbons are used as a solvent to increase the stability of the catalyst system and obtain a highly active and selective catalyst system. Preferably, the aromatic hydrocarbon solvent is selected from the group consisting of toluene, ethylbenzene, or mixtures thereof. The most preferred aromatic hydrocarbon is ethylbenzene.

After the mixing step has been completed and the catalyst system has been prepared, it is possible to remove the hydrocarbon solvent from the mixture. As is known from the prior art (for example, patent RU 2104088), the presence of an aromatic hydrocarbon in the reaction mixture during the oligomerization process can reduce the activity of the catalytic system and increase the amount of by-products, such as polymers. Removal of the solvent can be carried out by any known method, for example, by creating a vacuum (vacuum). However, it is worth noting that solvent removal is not always necessary. Thus, in the case of carrying out the olefin oligomerization process at elevated temperatures, the presence of an unsaturated hydrocarbon solvent (for example, ethylbenzene) may be preferable, because at elevated temperatures, this solvent increases the stability of the catalytic system.

Microwave irradiation of alkylaluminum can be carried out both in the form of a compound as such, mainly in a liquid aggregate state, and in the form of a solution in a hydrocarbon solvent, for example, in hexane, cyclohexane, C ₁₀ -C ₁₂ hydrocarbon fractions.

During irradiation, it is necessary that the components of the catalytic system that undergo activation are in a vessel transparent to microwave radiation, for example, in a vessel made of glass, fluoroplastic, or polypropylene.

The microwave radiation used can have a frequency in the range from 0.2 to 20 GHz. Particularly preferable is the use of microwave radiation with a frequency of 2.45 GHz, which does not create radio interference and is widely used in domestic and industrial sources of microwave radiation.

The nominal power of microwave radiation ranges from 1 W to 5000 W per 1 g of alkylaluminum used in terms of elemental aluminum.

For best results, it is preferable that the irradiation time is between 20 seconds and 20 minutes, preferably 15 minutes. Irradiation lasting longer than 20 minutes usually does not provide additional benefits to the properties of the resulting catalyst system. Irradiation lasting less than 20 s may not be sufficient to significantly change the properties of the components that undergo activation, which in turn will lead to an insufficient increase in the activity and/or selectivity of the resulting catalytic system.

Mixing of alkylaluminum activated by microwave irradiation (microwave irradiation) with a chromium source and a nitrogen-containing ligand is carried out no more than 3 minutes after the end of irradiation, preferably no more than 1 minute after the end of irradiation.

If the time interval between mixing the irradiated aluminum alkyl with the chromium source and nitrogen-containing ligand is 3 minutes or more, the properties of the resulting catalytic system are significantly deteriorated compared to a system in which the specified time interval is less than 1 minute.

The ratios of the components of the catalytic system may vary. The mole ratio of aluminum to chromium can be from 5:1 to 500:1, preferably from 10:1 to 100:1, most preferably from 20:1 to 50:1. The mole ratio of alloy to chromium can vary from 2:1 to 50:1, preferably from 2.5:1 to 5:1.

As stated above, the olefin oligomerization process in accordance with the present invention can be carried out by reacting, under oligomerization conditions, a feedstock containing an olefin feedstock in the presence of a catalyst system, and optionally a zinc compound.

The zinc compound can be used either as an individual compound or in a mixture with other compounds, for example, in the form of a solution in hydrocarbons.

The zinc compound or mixture of such compounds may be added directly to the catalyst system during its preparation or separately to the oligomerization reactor.

A zinc compound is used as an additional activator of the catalytic center, in particular chromium. The zinc compound, in order to increase its stability, is preferably used in the absence of visible and UV radiation.

The zinc compound may be metallic zinc, zinc-copper pair, activated zinc, alkylzinc compounds, in particular dimethyl-, diethyl- and dibutylzinc, arylzinc compounds such as diphenyl- and ditolylzinc, zinc amides, in particular zinc pyrrolides and zinc porphyrin complexes , zinc oxygenates (including formate, acetate, basic acetate, 2ethylhexanoate and other zinc carboxylates), zinc halides, particularly anhydrous zinc chloride, or combinations thereof. It is preferable to use zinc compounds that are soluble in the solvents used in the oligomerization process.

- 4 044431

The zinc:chromium ratio can vary from 2:1 to 100:1, preferably from

5:1 to 50:1.

The catalyst system prepared in accordance with the present invention is introduced into the oligomerization reactor by any method known from the prior art in diluted or undiluted form. It is preferable to dilute the catalyst system with a hydrocarbon solvent. For the reasons stated above, it is particularly preferred to use a dilution with a saturated hydrocarbon solvent or a mixture thereof. However, it is preferable that the content of aromatic compounds does not exceed 2 wt.%.

A hydrocarbon solvent, for example, an alkane, a cycloalkane, a mixture of various alkanes and/or cycloalkanes, is used as a solvent in the oligomerization process. The hydrocarbon solvent may also contain unsaturated hydrocarbons, such as olefins or aromatic compounds. Suitable hydrocarbon solvents or solvent components include heptane, cyclohexane, decane, undecane, iso-decane fraction, 1-hexene. Preferably, heptane, cyclohexane, undecane are used as the solvent, most preferably cyclohexane or heptane is used.

The olefins used as the starting olefin in the olefin oligomerization process are ethylene (ethene), propylene (propene) and butylene (butene). Preferably, ethylene (ethene) is used as the starting olefin.

The process of olefin oligomerization is carried out to obtain oligomerization products - higher olefins. Industrially important processes are the processes for obtaining oligomerization products - α-olefins - from ethylene. α-Olefins are compounds with a carbon-carbon double bond (C=C) at the α position.

The α-olefins produced by the oligomerization process may include various C ₄ -C ₄₀ olefins and mixtures thereof. For example, α-olefins produced by ethylene oligomerization may be 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, higher α-olefins, or mixtures thereof. Preferably, the oligomerization process is a trimerization process of ethylene to produce the target α-olefin, 1-hexene.

The oligomerization process can be carried out in any of the reactors known in the art. Suitable reactors are continuous stirred tank reactor, batch reactor, plug flow reactor, tubular reactor. The reactor can be a gas-liquid reactor, for example, an autoclave with a stirrer, a bubble column (bubble reactor) with direct or counter-current supply of gas and liquid, as well as a bubble gas lift reactor.

In a preferred embodiment of the process, where the oligomerization process is the trimerization process of ethylene to produce 1-hexene, the ethylene pressure is varied in the range of 1 to 200 atm, preferably 10 to 60 atm, most preferably 15 to 40 atm. It is preferable to increase the ethylene pressure to increase the rate of oligomerization.

The temperature of the oligomerization process can vary in the range from 0 to 160°C, preferably from 40 to 130°C. It is most preferable to maintain the reactor temperature in the range of 80 to 120°C. At this temperature, the polymer by-product, in particular polyethylene, will not precipitate from solution, i.e. will be removed from the reactor in the form of a solution, and the catalytic system will be the most active and selective. Carrying out the oligomerization process at higher temperatures (above 120°C) can lead to deactivation of the catalytic system.

In accordance with the proposed method, the reaction time may vary. The reaction time can be defined as the residence time of the raw material and solvent in the oligomerization reaction zone. When using continuous flow reactors, the reaction time can be defined as the average residence time. Reaction times may vary depending on the olefin feedstock used, reaction temperature, pressure and other process parameters. In embodiments of the method, the reaction time does not exceed 24 hours. The reaction time can be less than 12 hours, less than 6 hours, less than 3 hours, less than 2 hours, less than 1 hour, less than 30 minutes, less than 15 minutes, less than 10 minutes. The most preferred reaction time is from 30 minutes to 90 minutes.

According to the proposed method, the olefin and the catalyst system can be contacted with hydrogen, which is supplied to the oligomerization reactor and used as a diluent. Hydrogen can accelerate the oligomerization reaction and/or increase the activity of the organometallic catalyst. In addition, hydrogen can reduce the amount of polymer byproduct produced and thereby limit the deposition of polymer on the walls of equipment.

The process of olefin oligomerization is carried out in the absence of water and oxygen.

The olefin feed, solvent and catalyst system can be introduced into the oligomerization reactor in any order. Preferably, the components are introduced in the following sequence: solvent, then catalyst system, followed by dosing of the starting olefin.

According to the present invention, the reaction mass leaving the reactor may contain a starting olefin, a catalyst system, a target α-olefin that is a target oligomer of the starting α-olefin, by-products, a solvent, and a polymer by-product that may be formed in the process of oligomerization.

The target α-olefin may include isomers of the target α-olefin, and the weight ratio of the target α-olefin to the corresponding isomers must be at least 99.5:0.5.

The reaction mass leaving the reactor is in step b) contacted with a catalyst system deactivation agent to obtain a reaction mass containing the remains of the catalytic system.

Suitable catalyst system deactivation agents known in the art include water, alcohols, amines, amino alcohols or mixtures thereof, as well as various sorbents such as silica gel, alumina, aluminosilicates or mixtures thereof with water, alcohols, amines, amino alcohols. Alcohols that can be used are, for example, methanol, ethanol, n-propanol, isopropanol, nbutanol, isobutanol, tert-butanol, 2-ethylhexanol, ethylene glycol, propylene glycol, triethylene glycol, polyethylene glycol or mixtures thereof. Examples of suitable amines are ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, tri-n-propylamine, diisopropylethylamine, tri-n-butylamine, piperazine, pyridine, ethylenediamine, diethylenetriamine, or mixtures thereof. Examples of amino alcohols include ethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, dodecyldiethanolamine, 1-amino-2-propanol, or mixtures thereof.

Preferably, alcohols or amino alcohols such as 2-ethylhexanol, ethylene glycol, propylene glycol, diethanolamine, triethanolamine are used as the deactivation agent for the catalytic system, most preferably 2-ethylhexanol is used.

The introduction of the catalytic system deactivation agent is carried out into the line for unloading the reaction mass from the oligomerization reactor. Preferably, the point of introduction of the decontamination agent is located near the oligomerization reactor. The specified line for unloading the reaction mass from the oligomerization reactor must have a minimum number of stagnant zones and reduced hydraulic resistance to increase the efficiency of deactivation of the catalytic system in order to avoid precipitation of the polymer by-product. Alternatively, a catalyst system deactivation agent may be introduced into the apparatus in which step c) isolating the fraction containing the starting olefin from the reaction mass is carried out.

After deactivation of the catalytic system, the reaction mass containing the remnants of the catalytic system enters stage c) of isolating the original olefin.

At stage c), a light fraction containing the starting olefin is separated from the reaction mass containing the remnants of the catalytic system, forming a stream of oligomerization reaction products.

Isolation of the light fraction containing the starting olefin from the reaction mass is carried out in any suitable equipment known in the art. Examples of such equipment include, but are not limited to, batch or continuous settling apparatuses, such as overflow wall settling apparatuses. The size and shape of the settling apparatus depend on the concentration of the polymer by-product suspension and the sedimentation rate.

The rate of settling depends on temperature, since when the temperature of the polymer by-product suspension changes, its viscosity changes.

The separation process is carried out at a temperature from 60 to 120°C, preferably from 70 to 110°C, more preferably at a temperature from 80 to 110°C, and a pressure from 0 to 60 atm, preferably from 0 to 40 atm, more preferably from 0 up to 30 atm.

The fraction containing the starting olefin isolated in step c) may also contain a C4 fraction containing butene-1 and butene-2 in an amount of not more than 2 wt.%, preferably not more than 1 wt.%, more preferably not more than 0.03 wt.%.

The fraction containing the original olefin isolated in step c) can be returned to the oligomerization reactor.

Also at stage c), settling of the oligomerization product stream can occur, in which concentration of the polymer by-product and the residues of the catalytic system is observed at the bottom of the settling apparatus to obtain a clarified part of the oligomerization reaction products, containing a small amount of the catalytic system and polymer by-product, and a concentrated part of the reaction products oligomerization, containing the bulk of the polymer by-product and the remainder of the catalytic system.

According to a first embodiment of the present invention, the oligomerization reaction product stream from step c) is directed to step d) separating the oligomerization reaction product stream into a fraction predominantly containing oligomers, in particular C6+, and a fraction containing polymer by-product and catalyst system residues.

According to the present invention, separation step d) is carried out in an evaporator. The evaporator may be, but is not limited to, vertical devices such as a film evaporator, a rotary film evaporator. Preferably, a rotary film evaporator is used.

- 6 044431

The separation process in the evaporator is carried out at a temperature from 64 to 175°C, more preferably at a temperature from 80 to 150°C, and a pressure from 0 to 6 atm g, preferably from 0 to 3 atm g, more preferably from 0 to 2 atm g.

The fraction obtained at stage d), predominantly containing oligomers, in particular C6+, includes the target α-olefin, preferably hexene-1 in an amount of 20 to 25 wt.%, the remains of the light fraction, in particular C ₂ -C ₄ fractions, in an amount not more than 1 wt.%, solvent in an amount from 73 to 79 wt.%, and a heavy fraction, in particular the C8+ fraction in an amount of not more than 2 wt.%.

The fraction obtained in step d) containing the polymer by-product and the remnants of the catalytic system is a suspension of the polymer by-product and the remnants of the catalytic system in the oligomerization reaction products, and also contains a catalyst system deactivation agent.

After separation, the fraction predominantly containing C6+ is sent to step e) to be separated into three fractions: a light fraction, in particular the C ₂ -C ₄ fraction, a target α-olefin fraction, in particular the C6+ fraction, and a heavy oligomer fraction, in particular the C8+ faction.

Step e) is carried out in any suitable apparatus known in the art. Examples of such apparatus include, but are not limited to, an evaporation column, a separation column equipped with various types of contact devices.

The separation process in step e) is carried out at a temperature of 64 to 140°C, more preferably at a temperature of 64 to 120°C, and a pressure of 0 to 4 atm, preferably 0 to 3 atm, more preferably 0 to 2 atm.

The light fraction obtained in step e), in particular the C2-C4 fraction, comprises a starting olefin, preferably ethylene, butene-1 and butene-2. The specified light fraction, in particular C ₂ -C ₄ , if necessary, is returned to the oligomerization reactor.

The target α-olefin fraction, in particular the C6+ fraction, obtained in step e) comprises the target α-olefin, preferably 1-hexene in an amount of 21 to 27% by weight, and a solvent. Also, the target α-olefin fraction (in particular the C6+ fraction) contains C8 olefins in an amount of 0.25 wt.% and C10 olefins in an amount of no more than 0.5 wt.%. the oligomer fraction (C6+ fraction) is then sent to the stage of isolating the target α-olefin, preferably 1-hexene.

The heavy fraction of oligomers obtained in step e), in particular C8+, contains C8 olefins, including 1-octene, C10 olefins, in particular decenes.

The heavy fraction of oligomers (in particular the C8+ fraction) is then sent to the stage of separating the target α-olefin together with the fraction of the target α-olefin (in particular the C6+ fraction) or to the stage of separating the target α-olefin and into the evaporator at stage d).

The stage of isolating the target α-olefin is carried out in a packed or plate-type distillation column. The content of the target α-olefin in the target α-olefin fraction, preferably 1-hexene, is at least 95 wt%, preferably 97 wt%, more preferably 99 wt%. The bottom product remaining after separation of the target α-olefin is sent to the solvent separation stage.

The solvent separation stage is carried out in a packed or plate-type distillation column. Preferably, the solvent released at this stage is returned to the reactor (return solvent). The purity of the return solvent is at least 90%, preferably at least 95%, more preferably at least 99%.

The bottom product of the recovery solvent recovery stage is a heavy fraction of oligomers (in particular the C8+ fraction), predominantly containing octenes in an amount from 95 to 99 wt.%, decenes in an amount from 0.5 to 4.7 wt.% and solvent in an amount of more than 2 wt.%. In addition, said bottom product may contain a small amount of a catalyst system deactivating agent, the amount of which should not exceed 0.005 wt.%, preferably 0.002 wt.%, most preferably 0.0005 wt.%. The specified heavy fraction of oligomers (C8+ fraction) can be used for washing the reaction equipment to clean it from polymer by-product sediment and catalytic system residues.

According to a second embodiment of the present invention, the oligomerization reaction product stream from step c) is directed to step c*), in which the first portion of the oligomerization reaction product stream from step c) is directed to the separation step d)*; and directing the second part of the oligomerization reaction product stream from step c) to step d).

At stage d)*, the first part of the oligomerization reaction product stream from stage c)* is separated in a separation column into a light fraction, in particular the C2-C4 fraction, a fraction of the target α-olefin, in particular the C6+ fraction, and a heavy fraction of oligomers, in particular the C8+ fraction, followed by sending the heavy fraction (in particular the C8+ fraction) to step d).

In accordance with the present invention, step d)* is carried out in conjunction with step e).

Step d)* and step e) are carried out in any suitable apparatus known in the art. Examples of such apparatus include, but are not limited to, an evaporation column, a separation column, equipped with various types of contact devices.

The separation process in stages d)* and e) is carried out at a temperature from 64 to 140°C, more preferably at a temperature from 64 to 120°C, and a pressure from 0 to 4 atm g, preferably from 0 to 1 atm g, more preferably from 0 to 2 atm g.

The light fraction obtained in steps d)* and e), in particular the C ₂ -C ₄ fraction, includes a starting olefin, preferably ethylene, as well as butene-1 and butene-2. Said light fraction (in particular the C ₂ -C ₄ fraction), if necessary, is returned to the oligomerization reactor.

The target α-olefin fraction, in particular the C6+ fraction, obtained in step d)* and e) comprises the target α-olefin, preferably 1-hexene in an amount of 21 to 27% by weight, and a solvent. Also, the C6+ fraction contains C8 olefins in an amount of 0.25 wt.% and C10 olefins in an amount of no more than 0.5 wt.%. The target α-olefin fraction (in particular the C6+ fraction) is then sent to the stage of isolating the target α-olefin, preferably 1-hexene.

The heavy fraction of oligomers obtained at stages d)* and e), in particular the C8+ fraction, contains C8 olefins, including 1-octene, C10 olefins, in particular decenes. The heavy fraction of oligomers (in particular the C8+ fraction) is then sent to the stage of separating the target α-olefin or to the stage of separating the target α-olefin and into the evaporator at stage d).

According to the present invention, separation step d) is carried out in an evaporator. The evaporator may be, but is not limited to, vertical devices such as a film evaporator, a rotary film evaporator. Preferably, a rotary film evaporator is used.

The separation process in the evaporator is carried out at a temperature of 64 to 175°C, more preferably at a temperature of 80 to 150°C, and a pressure of 0 to 6 atm, preferably 0 to 3 atm, more preferably 0 to 2 atm.

The target α-olefin fraction obtained in step d), in particular the fraction predominantly containing C6+, includes the target α-olefin oligomer, preferably 1-hexene in an amount of 20 to 25 wt.%, the remains of the light fraction, preferably the C ₂ -C ₄ fraction in an amount of not more than 1 wt.%, a solvent in an amount of from 73 to 79 wt.%, and a heavy fraction of oligomers (in particular the C8+ fraction) in an amount of not more than 2 wt.%.

The fraction obtained in step d) containing the polymer by-product and the remnants of the catalytic system is a suspension of the polymer by-product and the remnants of the catalytic system in the oligomerization reaction products, and also contains a catalyst system deactivation agent.

After separation, the target α-olefin fraction, in particular the fraction predominantly containing C6+, is sent to step e) to be separated into three fractions: a light fraction, in particular the C ₂ -C ₄ fraction, a target α-olefin fraction, in particular the C6+ fraction, and the heavy fraction of oligomers, in particular the C8+ fraction.

The solvent separation stage is carried out in a packed or plate-type distillation column. Preferably, the solvent released at this stage is returned to the reactor (return solvent). The purity of the return solvent is at least 90%, preferably at least 95%, more preferably at least 99%.

The bottom product of the recovery solvent recovery stage is a heavy fraction of oligomers (in particular the C8+ fraction), predominantly containing octenes in an amount of no more than 17 wt.%, decenes in an amount of up to 81 wt.% and solvent in an amount of no more than 2 wt.%. In addition, said bottom product may contain a small amount of a catalyst system deactivating agent, the amount of which should not exceed 0.005 wt.%, preferably 0.002 wt.%, most preferably 0.0005 wt.%. The specified C8+ fraction can be used for washing the reaction equipment to clean it from sediment of the polymer by-product and residues of the catalytic system.

One embodiment of the present invention is illustrated in more detail in FIG. 1, which shows a flow diagram of the olefin oligomerization process with the implementation of the method for separating oligomerization products according to the first embodiment of the present invention. According to FIG. 1 101 - oligomerization reactor, 102 - settling apparatus, 103 - evaporator at stage d), 104 - apparatus for separation at stage e), 105 - column for separating the target α-olefin, 106 - column for separating the return solvent.

According to the presented method, the initial olefin, which is preferably ethylene, a solvent and a catalytic system (1), is supplied to the oligomerization reactor 101. Next, the reaction mass (2), obtained during the oligomerization reaction and leaving the oligomerization reactor, is in contact with the deactivation agent of the catalytic system (3) to obtain a reaction mass containing the remains of the catalytic system. After this, the reaction mass containing the remnants of the catalytic system enters the settling apparatus 102, in which the fraction containing the original olefin (4) is separated to form a stream of oligomerization reaction products

- 8 044431 (5) . The fraction containing the original olefin (4) is optionally returned to the oligomerization reactor. Next, the stream of oligomerization reaction products (5) is sent to the evaporator 103, in which the stream of oligomerization reaction products is separated into a fraction of the target α-olefin (6), in particular predominantly containing C6+, and a fraction (7) containing a polymer by-product and catalytic residues systems. After this, the target α-olefin fraction (6), predominantly containing C6+, is sent to the separation apparatus 104 for separation into three fractions: C2-C4 fraction (8), C6+ fraction (11) and C8+ fraction (streams (9) and/or (10)). The C8+ fraction (9) together with the C6+ fraction (11) is then sent to the stage of isolating the target α-olefin (12) into 105 or the C8+ fraction (10) together with the C6+ fraction (11) is sent to the stage of isolating the target α-olefin (12) in 105 and C8+ fraction (10) is sent to the evaporator 103. The bottom product (13), remaining after the separation of the target α-olefin (12), is sent to the solvent separation stage in 106 to obtain return solvent (14) and bottom product (15) , containing the C8+ fraction.

A second embodiment of the present invention is explained in more detail in FIG. 2, which shows a flow diagram of the olefin oligomerization process with the implementation of the method for separating oligomerization products according to the second embodiment of the present invention. According to FIG. 2 101 - oligomerization reactor, 102 - settling apparatus, 103 - evaporator at stage d), 104 - apparatus for separation at stage e), 105 - column for separating the target α-olefin, 106 - column for separating the return solvent.

According to the presented method, the starting olefin (preferably ethylene), the solvent and the catalytic system (1) are supplied to the oligomerization reactor 101. Next, the reaction mass (2), obtained during the oligomerization reaction and leaving the oligomerization reactor, is in contact with the deactivation agent of the catalytic system (3) to obtain a reaction mass containing the remains of the catalytic system. After this, the reaction mass containing the remnants of the catalytic system enters the settling apparatus 102, in which the fraction containing the original olefin (4) is separated to form a stream of oligomerization reaction products, which is divided into two streams (5) and (6). The fraction containing the original olefin (4) is optionally returned to the oligomerization reactor. Next, the first part of the stream of oligomerization reaction products (5) is sent to the separation apparatus 104 for separation into three fractions: C ₂ -C ₄ fraction (7), C6+ fraction (8) and C8+ fraction (9). The second part of the stream of oligomerization reaction products is sent to the evaporator 103, in which the stream of oligomerization reaction products (6) is separated into a fraction of the target α-olefin (10), predominantly containing C6+, and a fraction (12) containing a polymer by-product and the remains of the catalytic system . After this, the target α-olefin fraction (10), predominantly containing C6+, is sent to the separation apparatus 104 for separation into three fractions: C2-C4 fraction (7), C6+ fraction (8) and C8+ fraction (stream (9) and/or (eleven)). The C8+ fraction (11) together with the C6+ fraction (8) is then sent to the stage of isolating the target α-olefin (13) in 105 or together with the C6+ fraction (8) is sent to the stage of isolating the target α-olefin (13) in 105 and the C8+ fraction (9) is sent to the evaporator 103. The bottom product (14), remaining after the separation of the target α-olefin (13), is sent to the solvent recovery stage 106 to obtain a return solvent (15) and a bottom product (16) containing the C8+ fraction.

Shown in FIGS. 1 and fig. 2 diagrams are examples of implementation of the present invention and do not limit it.

The present invention is more specifically described with reference to the following examples. These examples are provided only to illustrate the present invention and do not limit it.

Carrying out the invention

Solvent - cyclohexane.

Catalytic system:

1) source of chromium - chromium (III) 2-ethylhexanoate,

2) ligand - 2,5-dimethylpyrrole,

3) alkylaluminum - a mixture of triethylaluminum and diethylaluminum chloride. The deactivation agent of the catalytic system is 2-ethylhexanol.

Example 1. Separation of the product stream of the ethylene oligomerization reaction according to the first embodiment.

Cyclohexane, preheated to a temperature of 90°C, ethylene, preheated to a temperature of 70°C, and the catalytic system, using dosing pumps, enter an oligomerization reactor operating at a pressure of 25 atm.

The process of oligomerization of ethylene into hexene-1 is carried out at a temperature of 100-120°C and a pressure of 25 atm to a degree of ethylene conversion of approximately 50%. This reaction is exothermic and requires the use of a cooling system for the oligomerization reactor.

The reactor is a vertical heat exchanger-type apparatus with built-in tube bundles in the amount necessary to remove the heat of the trimerization reaction. Refrigerant is supplied to the annulus of the reactor. The gas, predominantly consisting of ethylene, is separated from the liquid reaction mass, removed through a separate fitting located at the top of the separation part of the reactor, and enters the heat exchanger, where it is cooled by a refrigerant and partially condensed.

Next, the liquid reaction mass is fed by gravity through two collectors into a settling apparatus designed for partial separation of unreacted ethylene and hydrogen.

To deactivate the catalytic system after the oligomerization reaction, the catalytic system deactivation agent - 2-ethylhexanol - is supplied to the collector after the reactor before the reaction mass enters the settling apparatus using dosing pumps.

In the settling apparatus, unreacted ethylene is removed, which is returned to the oligomerization reactor through a compression unit. The reaction mass containing the remnants of the catalytic system enters a rotary film evaporator, where the polymer by-product, in particular polyethylene, the remnants of the catalytic system and the deactivation agent of the catalytic system are separated. The rotary film evaporator operates at a temperature of 150°C and a pressure from 0.05 to 0.1 atm.

The reaction mass, purified from the polymer by-product, in particular, polyethylene, residues of the catalytic system and the deactivation agent of the catalytic system, enters the evaporation column from the rotary film evaporator. The evaporation column operates at temperatures from 64°C to 140°C and a pressure of 3.5 atm g.

In the evaporation column, the reaction mass is divided into three streams:

fraction C ₂ -C ₄ ;

the C6+ fraction, which enters the stage of isolation of hexene-1;

the C8+ fraction, partially returned to the rotary film evaporator, and partially sent to the stage of isolating the target product.

Isolation of hexene-1 is carried out in a packed-type distillation column at a temperature of 70 to 100°C and a pressure of 2 atm g.

Next, the C6+ fraction remaining after the separation of 1-hexene enters the stage of separation of the return solvent.

The stage of separating the return solvent is carried out in a packed-type distillation column at a temperature of 80 to 140°C and a pressure of 2 atm g.

The compositions of the streams are presented in Table. 1.

Example 2. Separation of the product stream of the ethylene oligomerization reaction according to the second embodiment.

Cyclohexane, preheated to a temperature of 90°C, ethylene, preheated to a temperature of 70°C, and the catalytic system, using dosing pumps, enter the oligomerization reactor operating at a pressure of 25 atm.

The process of oligomerization of ethylene into hexene-1 is carried out at a temperature of 100-120°C and a pressure of 25 atm to a degree of ethylene conversion of approximately 50%. This reaction is exothermic and requires the use of a cooling system for the oligomerization reactor.

The reactor is a vertical heat exchanger-type apparatus with built-in tube bundles in the amount necessary to remove the heat of the trimerization reaction. Refrigerant is supplied to the annulus of the reactor. The gas, predominantly consisting of ethylene, is separated from the liquid reaction mass, removed through a separate fitting located at the top of the separation part of the reactor, and enters the heat exchanger, where it is cooled by the refrigerant and partially condensed.

Next, the reaction mass is fed by gravity through two collectors into a settling apparatus designed for partial separation of unreacted ethylene and, if used, hydrogen.

To deactivate the catalytic system after the oligomerization reaction, the catalytic system deactivation agent - 2-ethylhexanol - is supplied to the collector after the reactor before the reaction mass enters the settling apparatus using dosing pumps.

In the settling apparatus, unreacted ethylene is removed, which is returned to the oligomerization reactor through a compression unit. Also in the settling apparatus, the concentration of the polymer by-product and the residues of the catalytic system at the bottom of the apparatus occurs, resulting in the formation of a clarified part of the reaction mass and a concentrated part of the reaction mass.

The clarified part of the reaction mass from the upper part of the settling apparatus enters the evaporation column. The evaporation column operates at temperatures from 64°C to 140°C and a pressure of 3.5 atm g.

In the evaporation column, the clarified part of the reaction mass is divided into three streams:

fraction C ₂ -C ₄ ;

the C6+ fraction, which enters the stage of isolation of hexene-1;

the C8+ fraction, partially returned to the rotary film evaporator, and partially sent to the stage of isolating the target product.

Isolation of hexene-1 is carried out in a packed-type distillation column at a temperature of 70 to 100°C and a pressure of 2 atm g.

- 10 044431

Next, the C6+ fraction remaining after the separation of 1-hexene enters the stage of separation of the return solvent.

The stage of separating the return solvent is carried out in a packed-type distillation column at a temperature of 80 to 140°C and a pressure of 2 atm g.

The C8+ fraction is sent to a rotary film evaporator, where additional separation of the C8+ fraction occurs, which is returned to the evaporation column and then, with the general flow of the C6+ fraction, enters the stage of hexene-1 separation. The rotary film evaporator operates at a temperature of 150°C and a pressure from 0.05 to 0.1 atm.

The concentrated part of the reaction mass, containing the polymer by-product and the remnants of the catalytic system, enters a rotary film evaporator, where the polymer by-product, in particular polyethylene, the remnants of the catalytic system and the deactivation agent of the catalytic system are separated.

The reaction mass, purified from the polymer by-product, in particular, polyethylene, residues of the catalytic system and the deactivation agent of the catalytic system, enters the evaporation column from the rotary film evaporator. The evaporation column operates at temperatures from 64°C to 140°C and a pressure of 3.5 atm g.

The compositions of the streams are presented in Table. 2.

When using methods for separating the stream of oligomerization reaction products given in examples 1 and 2, the presence of a polymer by-product at the stage of isolating the target product is eliminated (Table 1, commercial hexene-1 flow (12) from apparatus 105 and Table 2, commercial hexene flow -1 (13) from apparatus 105, polymer by-product content 0 wt.%) and the stage of separation of return solvent (Table 1, return solvent flow (14) from apparatus 106 and Table 2, return solvent flow (15) from apparatus 106, polymer by-product content 0 wt.%), maximum extraction of hexene-1 is ensured (hexene-1 content - Table 1, in the commercial hexene-1 stream (12) and Table 2, in the commercial hexene-1 stream (13 ) - is 99.01 wt.%) and return solvent (cyclohexane content - Table 1, in the return solvent flow (14) and Table 2, in the return solvent flow (15) is 99.5 wt.%) from the reaction mass, it is ensured that the C8+ fraction is obtained, purified from the components of the catalytic system and the polymer by-product (the content of the polymer by-product and the residues of the catalytic system is 0 wt.%, the flow of the C8+ fraction (15) (Table. 1) and (16) (Table 2), which in turn makes it possible to use the C8+ fraction for washing the oligomerization reactor.

Table 1

Compositions of streams according to example 1

Components Reaction mass (2) from 101 to 102 Reaction mass (3) from 102 to 103 Flow (11) from 104 to 105 Stream (9) from 104 to 105 Stream (6) from 103 to 104 Commodity hexene-1 (12) of 105 Flow (13) from 105 to 106 Solvent return (14) of 106 S8+ (15) out of 106 % May. % May. % May. % May. % May. % May. % May. % May. % May. hydrogen 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ethylene 34.07 6.30 0.19 0.00 6.30 0.00 0.00 0.00 0.00 1-butene 0.04 0.04 0.01 0.00 0.04 0.00 0.00 0.00 0.00 hexene-1 14.40 20.15 20.80 14.70 20.71 99.01 0.40 0.41 0.00 cyclohexane 49.37 70.56 77.40 80.79 72.06 0.32 96.91 99.50 0.05 cis-2-hexene 0.10 0.14 0.15 0.07 0.14 0.57 0.03 0.04 0.00 trans-2-hexene 0.02 0.02 0.02 0.01 0.02 0.10 0.01 0.01 0.00 ethylbenzene 0.24 0.35 0.36 0.90 0.22 0.00 0.45 0.03 16.28 1-octene 0.01 0.02 0.02 0.03 0.01 0.00 0.02 0.02 0.13 decenes 0.98 1.42 1.00 2.50 0.40 0.00 1.72 0.00 77.67 tetradecenes 0.19 0.27 0.05 1.00 0.10 0.00 0.15 0.00 5.87 Remains of the catalytic system 0.08 0.12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2-ethylhexanol 0.43 0.62 0.00 0.00 0.00 0.30 0.00 0.01

- 11 044431

Polymer by-product 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Total 100 100 100 100 100 100 100 100 100 Pressure atm g. 23 4 2 2 -0.2 2 1 3 1 Temperature, °C 99.1 83.6 116.5 116.5 162.1 40.0 96.6 89.9 60.0

table 2

Compositions of streams according to example 2

Components Reaction mass (2) from 101 to 102 Reaction mass (5) from 102 to 104 Poto to (8) from 104 to 105 Poto to (9) from 104 to 103 Poto to (10) from 103 to 104 Flow (12) from 103 Flow (8) at 105 Commercial hexene-1 (13) of 105 Poto to (14) from 105 to 106 Return solvent (15) of 106 S8+ (16) out of 106 % May. % May. % May. % May. % May. % May. % May. % May. % May. % May. % May. hydrogen 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ethylene 34.07 6.30 0.19 0.04 0.03 0.00 0.19 0.00 0.00 0.00 0.00 1-butene 0.04 0.04 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 hexene-1 14.40 20.15 20.54 9.47 14.64 0.00 21.39 99.01 0.40 0.41 0.00 cyclohexane 49.37 70.56 76.98 52.86 83.07 0.00 76.16 0.32 96.91 99.50 0.05 cis-2-hexene 0.10 0.14 0.15 0.07 0.07 0.07 0.15 0.57 0.03 0.04 0.00 trans-2-hexene 0.02 0.02 0.02 0.01 0.01 0.01 0.02 0.10 0.01 0.01 0.00 ethylbenzene 0.24 0.35 0.36 0.90 0.31 1.93 0.36 0.00 0.45 0.03 16.28 1-octene 0.01 0.02 0.02 0.03 0.01 0.05 0.02 0.00 0.02 0.02 0.13 decenes 0.98 1.42 1.37 7.85 1.32 19.36 1.35 0.00 1.72 0.00 77.67 tetradecenes 0.19 0.27 0.12 6.85 0.37 18.31 0.12 0.00 0.15 0.00 5.87 Remains of the catalytic system 0.08 0.12 0.00 4.88 0.00 8.03 0.00 0.00 0.00 0.00 0.00 2-ethylhexanol 0.43 0.62 0.24 16.83 0.14 46.22 0.24 0.00 0.30 0.00 0.01 Polymer by-product 0.00 0.00 0.00 0.21 0.00 0.57 0.00 0.00 0.00 0.00 0.00 Total 100 100 100 100 100 100 100 100 100 100 100 Pressure atm g. 23 4 4 4 3 -0.2 2 2 1 3 1 Temperature, °C 99.1 83.6 127.5 145.7 66.4 162.1 116.5 40.0 96.6 89.9 60.0

Example 3 (comparative). Separation of the ethylene oligomerization reaction product stream without using step d).

The detailed sequence of stages for this example 3 is presented in Fig. 3.

Cyclohexane, preheated to a temperature of 90°C, ethylene, preheated to a temperature of 70°C, and the catalytic system, using dosing pumps, enter (1) the oligomerization reactor (201), operating at a pressure of 25 atm.

The process of oligomerization of ethylene into hexene-1 is carried out at a temperature of 100-120°C and a pressure of 25 atm to a degree of ethylene conversion of approximately 50%. This reaction is exothermic and requires the use of a cooling system for the oligomerization reactor.

The reactors are devices of the vertical heat exchanger type with built-in tube bundles in the amount necessary to remove the heat of the trimerization reaction. Refrigerant is supplied to the annulus of the reactors. The gas, predominantly consisting of ethylene, is separated from the liquid reaction mass, removed through a separate fitting located at the top of the separation part of the reactors, and enters the heat exchanger, where it is cooled by a refrigerant and partially condensed.

Next, the reaction mass (2) is fed by gravity through two collectors into a settling apparatus (202), designed for partial separation of unreacted ethylene (4) and, if used, hydrogen.

To deactivate the catalytic system after the oligomerization reaction, the catalytic system deactivation agent (3) - 2-ethylhexanol - is supplied by dosing pumps to the collectors after the reactors before the reaction mass enters the settling apparatus.

-

Claims (41)

The reaction mass (5), containing the remnants of the catalytic system, enters the filtration system (203) to separate the polymer by-product and the remnants of the catalytic system (6). After passing through the filtration system, the reaction mass (7) enters the distillation column (204). The distillation column is designed to separate ethylene and hydrogen from the reaction mass (8). Next, the reaction mass (9), purified from ethylene and hydrogen, from the bottom of the distillation column is sent to the distillation column (205) to isolate the target product - 1-hexene. Isolation of hexene-1 is carried out in a packed-type distillation column at a temperature of 70 to 100°C and a pressure of 2 atm g. At the top of the column, hexene-1 (10) is released, the bottom product (11) is supplied to the rectification column (206) for recovering the return solvent (12). From the bottom of the column, a bottom product (13) containing the C8+ fraction is released. The stage of separating the return solvent is carried out in a packed-type distillation column at a temperature of 80 to 140°C and a pressure of 2 atm g. At the same time, upon startup of the installation, deposition of a polymer by-product almost immediately occurs on the walls of the equipment, including distillation columns and their elements, and a sharp decrease in the efficiency of the columns occurs, which does not allow obtaining reliable data on the composition of the flows and the quality of equipment operation. Thus, due to insufficient residence time of the reaction mass with the dissolved polymer by-product in the settling apparatus, most of the polymer by-product (up to 0.5 wt.% of the total flow) enters the ethylene and hydrogen separation column, and then into the hexene separation columns -1 and return solvent, resulting in periodic shutdowns of pumping equipment when clogged with a polymer by-product (1 or more times per day). Also, part of the polymer by-product enters the packed part of the distillation column and is deposited on the surface of the packing elements, which leads to a sharp decrease in the efficiency of separation of the reaction mass, so that it turns out to be possible either to isolate the return solvent of the required quality by reducing the quality of the product up to 20%, or to isolate the target product of the required quality and a solvent containing up to 20% of the product, and also leads to a reduction of up to 50% in the productivity of the distillation column. CLAIM 1. A method for separating olefin oligomerization products, which includes the following sequence of stages: a) unloading the reaction mass from the oligomerization reactor; b) bringing the reaction mass into contact with a deactivation agent of the catalytic system; c) separating from the reaction mass containing the remnants of the catalytic system a light fraction containing the original olefin, forming a stream of oligomerization reaction products; d) separating the oligomerization reaction product stream in the evaporator into a fraction containing the target α-olefin and a fraction containing the polymer and the remaining components of the catalytic system; e) separating the fraction containing the target α-olefin obtained in step d) into a light fraction, a fraction of the target α-olefin and a heavy oligomer fraction. 2. The method according to claim 1, characterized in that ethylene is used as the starting olefin. 3. Method according to any one of claims 1, 2, characterized in that the olefin oligomerization is an olefin trimerization. 4. The method according to claim 3, characterized in that the trimerization of the olefin is the trimerization of ethylene. 5. The method according to claim 4, characterized in that the fraction containing the target α-olefin is a C6+ fraction. 6. The method according to claim 4, characterized in that the light fraction is a C ₂ -C ₄ fraction. 7. The method according to claim 4, characterized in that the heavy fraction of oligomers is a C8+ fraction. 8. The method according to claim 1, characterized in that the target α-olefin fraction obtained in step e) includes hexene-1. 9. The method according to claim 1, characterized in that 1-hexene is isolated from the fraction of the target α-olefin obtained in step e). 10. The method according to claim 1, characterized in that the heavy fraction of oligomers obtained in step e) is sent to the stage of isolating the target α-olefin or to the stage of isolating the target α-olefin and to the evaporator. 11. The method according to claim 1, characterized in that the fraction isolated at stage c) containing the original olefin is sent to the oligomerization reactor. 12. The method according to claim 1, characterized in that the fraction isolated at stage d) containing the target α-olefin is sent to a separation column. - 13 044431 13. The method according to claim 12, characterized in that the fraction containing the target α-olefin is separated into a light fraction, a target α-olefin fraction and a heavy oligomer fraction. 14. The method according to claim 1, characterized in that the evaporator is a film evaporator or a rotary film evaporator. 15. The method according to claim 14, characterized in that the evaporator is a rotary film evaporator. 16. Method according to claim 1, characterized in that step d) is carried out at a temperature from 64 to 175°C. 17. Method according to claim 16, characterized in that step d) is carried out at a temperature from 80 to 150°C. 18. The method according to claim 1, characterized in that stage d) is carried out at a pressure from 0 to 6 atm g. 19. The method according to claim 18, characterized in that stage d) is carried out at a pressure from 0 to 3 atm g. 20. The method according to claim 18, characterized in that stage d) is carried out at a pressure from 0 to 2 atm g. 21. A method for separating olefin oligomerization products, which includes the following sequence of stages: a) unloading the reaction mass from the oligomerization reactor; b) bringing the reaction mass into contact with a deactivation agent of the catalytic system; c) separating from the reaction mass containing the remnants of the catalytic system a light fraction containing the original olefin, forming a stream of oligomerization reaction products; c)* directing the first part of the oligomerization reaction product stream from step c) to the separation column; and directing the second portion of the oligomerization reaction product stream from step c) to step d); d)* separating the first portion of the oligomerization reaction product stream from step c)* in a separation column into a light fraction, a target α-olefin fraction and a heavy oligomer fraction, followed by sending the heavy oligomer fraction to step d); d) separating in the evaporator the heavy fraction of oligomers from step d)* and the second part of the oligomerization reaction product stream into a fraction containing the target α-olefin and a fraction containing the polymer and the remaining components of the catalytic system; e) separating the fraction containing the target α-olefin obtained in step d) and the first part of the oligomerization reaction product stream from step c) into a light fraction, a target α-olefin fraction and a heavy oligomer fraction. 22. The method according to claim 21, characterized in that ethylene is used as the starting olefin. 23. The method according to claim 21 or 22, characterized in that the olefin oligomerization is an olefin trimerization. 24. The method according to claim 23, characterized in that the trimerization of the olefin is the trimerization of ethylene. 25. The method according to claim 24, characterized in that the fraction containing the target α-olefin is a C6+ fraction. 26. The method according to claim 24, characterized in that the light fraction is a C2-C4 fraction. 27. The method according to claim 24, characterized in that the heavy fraction of oligomers is a C8+ fraction. 28. The method according to claim 21, characterized in that the fraction of the target α-olefin obtained in step e) includes hexene-1. 29. The method according to claim 21, characterized in that 1-hexene is isolated from the fraction of the target αolefin obtained in step e). 30. The method according to claim 21, characterized in that the heavy fraction of oligomers obtained in step e) is sent to the stage of isolating the target α-olefin or to the stage of isolating the target α-olefin and to the evaporator. 31. The method according to claim 21, characterized in that the fraction containing the original olefin isolated in step c) is returned to the oligomerization reactor. 32. The method according to claim 21, characterized in that the fraction isolated at stage d) containing the target α-olefin is sent to a separation column. 33. The method according to claim 32, characterized in that the fraction containing the target α-olefin is separated into a light fraction, a target α-olefin fraction and a heavy oligomer fraction. 34. The method according to claim 21, characterized in that the evaporator is a film evaporator or a rotary film evaporator. 35. The method according to claim 34, characterized in that the evaporator is a rotary film evaporator. 36. The method according to claim 21, characterized in that stage d)* and stage e) are carried out together. 37. The method according to claim 21, characterized in that step d) is carried out at a temperature from 64 to 175°C. 38. The method according to claim 21, characterized in that step d) is carried out at a temperature from 80 to 150°C. 39. The method according to claim 21, characterized in that stage d) is carried out at a pressure from 0 to 6 atm g. 40. The method according to claim 39, characterized in that stage d) is carried out at a pressure from 0 to 3 atm g. 41. The method according to claim 39, characterized in that stage d) is carried out at a pressure from 0 to 2 atm g. -