Process for separating the effluent obtained from the oligomerization step

Abstract

The present invention relates to a method for treating the effluent obtained from an oligomerization step in a vaporization step. In particular, the oligomerization step is a step of dimerizing ethylene to 1-butene using a nickel-based catalytic system.

Description

Field of the Invention

[0001] The present invention relates to a process for treating in a vaporization step an effluent obtained from an oligomerization step. In particular, the oligomerization step is a step for dimerizing ethylene to 1-butene using a nickel-based catalytic system. Prior art

[0002] Since the 1950s, the conversion of light olefins by means of homogeneous catalysts based on transition metals, in particular nickel, in combination with halogenated activators such as alkylaluminum chlorides has been studied. This research has led to the development and marketing of various processes.

[0003] For example, via Dimersol from Axens TM Octene or hexene or nonene, respectively, is produced by the dimerization of butene or the oligomerization of propylene (Revue de l'Institut Français du Pétrole, Vol. 37, No. 5, September-October 1982, p. 639). Octene can be converted into isononanol in high yield by hydroformylation followed by hydrogenation. These C9 alcohols (i.e. alcohols containing 9 carbon atoms) are used in particular for the synthesis of phthalate plasticizers for PVC. Hexene or nonene can also be used as a base material for fuels with excellent octane numbers.

[0004] The development of catalytic systems capable of dimerizing olefins is carried out by selecting suitable transition metals and ligands. In existing catalytic systems, several catalytic systems based on nickel using various ligands have been developed. Examples that can be particularly mentioned include: complexes of π-allyl nickel phosphine halides and Lewis acids as described in French patent FR1410430B, complexes of nickel phosphine halides and Lewis acids as described in patent US3485881A, complexes of nickel and imino-imidazole ligands as described in French patent FR2979836B, and complexes of nickel carboxylates and hydrocarbyl aluminum halides as described in patent US3321546A. In the dimerization method using such a catalyst, it is confirmed that it is necessary to neutralize the catalyst at the end of the reaction to prevent the reaction from continuing undesirably.

[0005] Patent FR2733497 describes a process for producing 1-butene involving a separation zone in which the reaction effluent is vaporized in two steps: a first vaporization step by means of a vaporizer followed by a vaporization step using a thin-film evaporator used at the same pressure as the thin-film evaporator.

[0006] Patent FR2992962B describes a process for producing and separating 1-hexene from a product mixture obtained from an ethylene trimerization zone. Specifically, the patent describes the use of a series of separation zones with staged flashes, vaporizing the liquid effluent along an increasing temperature gradient ranging from 150-200°C to 160-220°C.

[0007] In its research, the Applicant Company has developed a new method for separating spent oligomeric effluents using at least two vaporization steps along a decreasing pressure gradient.

[0008] Advantageously, the method according to the invention can remove the spent catalyst by vaporization at a mild temperature. Advantageously, the use of at least two vaporization steps at a mild temperature along a decreasing pressure gradient prevents the phenomenon of activity recovery of the spent catalyst, which causes the selectivity of the required olefins to be reduced. Therefore, the method according to the invention can maximize the output of the required olefins. The method according to the invention can also limit the cost associated with the maintenance of the production unit. SUMMARY OF THE INVENTION

[0010] The present invention relates to a method for treating an effluent obtained from an oligomerization step, said method comprising a step of spending said effluent to deactivate the catalytic composition, followed by a step of thermal separation of the spent effluent, said thermal separation step comprising:

[0011] - a first vaporization step, carried out at a pressure of 2.0-5.0 MPa and a temperature of 70-150° C., to obtain a liquid fraction sent to a second vaporization step and a gaseous fraction, which is preferably sent to a distillation section,

[0012] - a second vaporization step, which is carried out at a pressure of 0.5-3.0 MPa and a temperature of 70-150° C., to obtain a liquid fraction and a gaseous fraction; preferably, the gaseous fraction is sent to a distillation section,

[0013] - wherein the pressure of the first vaporization step is higher than the pressure of the second vaporization step, preferably at least 0.5 MPa higher, preferably at least 1.0 MPa higher, preferably at least 1.5 MPa higher.

[0014] Therefore, the thermal separation step of the process according to the invention can remove the spent catalyst by vaporization at mild temperatures. Advantageously, the use of at least two vaporization steps at mild temperatures along a decreasing pressure gradient prevents the phenomenon of activity recovery of the spent catalyst, which leads to a decrease in selectivity to the desired olefins.

[0015] A further advantage of the process according to the invention is that it maximizes the selectivity to 1-butene.

[0016] In a preferred embodiment, the first vaporization step is carried out at a pressure of 2.0 MPa-4.5 MPa, preferably 2.5 MPa-4.0 MPa, and a temperature of 80°C-140°C, preferably 90°C-130°C.

[0017] In a preferred embodiment, the second vaporization step is carried out at a pressure of 0.8 MPa-3.0 MPa, preferably 1.0 MPa-2.0 MPa, and a temperature of 80°C-140°C, preferably 90°C-130°C.

[0018] In a preferred embodiment, the thermal separation step involves sending the liquid fraction obtained from the second vaporization step to a third vaporization step, the third vaporization step being carried out at a pressure of 0.1-1.5 MPa and a temperature of 70-200° C. to obtain a liquid fraction and a gaseous fraction; preferably, the gaseous fraction is sent to a distillation section, and the pressure of the second vaporization step is higher than the pressure of the third vaporization step, preferably at least 0.5 MPa higher, preferably at least 0.8 MPa higher.

[0019] Preferably, the third vaporization step is performed at a pressure of 0.3 MPa-1.2 MPa, preferably 0.4 MPa-1.0 MPa, and a temperature of 80-140°C, preferably 80-130°C.

[0020] In a preferred embodiment, the first step and / or the second step and / or the third step of the thermal separation is carried out by means of a flash vessel, which is preferably coupled to a heat exchanger.

[0021] In a preferred embodiment, the gas fraction obtained from the first vaporization step and / or the gas fraction obtained from the second vaporization step and / or the gas fraction obtained from the third vaporization step is liquefied by lowering the temperature to reach a pressure of 2.0-5.0 MPa and is preferably sent to the distillation section.

[0022] In a preferred embodiment, the temperature at which the gas fraction or fractions obtained from the vaporization step are liquefied is from 0 to 60°C.

[0023] In a preferred embodiment, the oligomerization step uses a catalytic composition comprising an alkylaluminum halide and optionally a nickel precursor.

[0024] In a preferred embodiment, the alkylaluminum halide corresponds to the formula [Al m R 5 n X 3-n ] o ,in:

[0025] -R 5 is a straight or branched chain alkyl group containing 1 to 12 carbon atoms,

[0026] - X is a chlorine or bromine atom, preferably a chlorine atom, and

[0027] - m is selected from 1 and 2,

[0028] - n is selected from 0, 1 and 2,

[0029] - o Choose from 1 and 2.

[0030] In a preferred embodiment, the effluent obtained from the oligomerization step has a content of alkylaluminum halide in the range from 0.01 to 100 000 ppm by weight.

[0031] In a preferred embodiment, the step of deactivating the effluent obtained from the oligomerization step is carried out by contacting said effluent with a deactivation system in order to deactivate the catalytic composition, said deactivation system comprising:

[0032] - having the general formula R 1 OH alcohol, where the group R 1 Selected from:

[0033] * Straight-chain or branched alkyl containing 2 to 20 carbon atoms,

[0034] * an aromatic group containing 5 to 30 carbon atoms, and / or

[0035] - With the general formula NR 2 R 3 R 4 Amines, wherein the groups R 2 , R 3 and R 4 Independently selected from:

[0036] * Hydrogen,

[0037] * Straight-chain or branched alkyl containing 1 to 20 carbon atoms and optionally substituted by NH2 groups.

[0038] In a preferred embodiment, the temperature at which the spent system is contacted with the effluent obtained from the oligomerization step is the temperature at which the oligomerization step takes place.

[0039] In a preferred embodiment, the failure system comprises a 1 OH alcohols and have the general formula NR 2 R 3 R 4 of amines.

[0040] In a preferred embodiment, the molar ratio of the amine to the alcohol is 0.5-100. DETAILED DESCRIPTION OF THE INVENTION

[0042] It should be noted that, throughout the specification, the expression “... - ..." should be understood to include the mentioned limit values.

[0043] For the purpose of the present invention, the various embodiments presented can be used alone or in combination with each other, without any limitation on the combination.

[0044] For the purposes of the present invention, various parameter ranges of a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, for the purposes of the present invention, a preferred pressure value range can be combined with a more preferred temperature value range.

[0045] The present invention relates to a process for treating an effluent obtained, preferably directly obtained, from an oligomerization step, said process comprising a step of spending said effluent followed, preferably directly followed, by a step of thermal separation of the spent effluent, said thermal separation step comprising:

[0046] - a first vaporization step, which is carried out at a pressure of 2.0-5.0 MPa and a temperature of 70-150° C.; the liquid fraction obtained at the end of the first vaporization step is sent to a second vaporization step, and the gaseous fraction is sent to a distillation section,

[0047] - a second vaporization step, which is carried out at a pressure of 0.5-3.0 MPa and a temperature of 70-150° C.; the gas fraction obtained from the second vaporization step is sent to a distillation section,

[0048] - wherein the pressure of the first vaporization step is higher than the pressure of the second vaporization step, preferably at least 0.5 MPa higher, preferably at least 1.0 MPa higher, preferably at least 1.5 MPa higher.

[0049] Therefore, the thermal separation step according to the invention can remove the spent catalyst by vaporization at mild temperatures. Advantageously, the use of at least two vaporization steps at mild temperatures along a decreasing pressure gradient prevents the phenomenon of activity recovery of the spent catalyst, which results in a decrease in selectivity to the desired olefins.

[0050] Another advantage of the deactivation method according to the invention is that it maximizes the selectivity towards 1-butene.

[0051] Thermal separation step

[0052] Thus, the process according to the invention comprises a step of thermal separation, generally called vaporization, of the effluent obtained from the oligomerization step, said effluent having previously been spent in order to deactivate the catalytic composition, said thermal separation step comprising:

[0053] a first vaporization step, which is carried out at a pressure of 2.0-5.0 MPa and a temperature of 70-150° C., to obtain a liquid fraction sent to a second vaporization step, and a gaseous fraction which is preferably sent to a distillation section,

[0054] - a second vaporization step, which is carried out at a pressure of 0.5-3.0 MPa and a temperature of 70-150° C., to obtain a liquid fraction and a gaseous fraction; preferably, the gaseous fraction is sent to a distillation section,

[0055] - wherein the pressure of the first vaporization step is higher than the pressure of the second vaporization step, preferably at least 0.5 MPa higher, preferably at least 1.0 MPa higher, preferably at least 1.5 MPa higher.

[0056] The thermal separation step may advantageously remove spent catalyst and heavy (C12+) by-products produced during the oligomerization step and send the desired olefins to the distillation section in order to purify them.

[0057] Preferably, the spent catalyst and heavy (C12+) by-products separated in the vaporization step and contained in the liquid fraction obtained from the last vaporization step performed are sent to an incinerator.

[0058] The gaseous fraction sent to the distillation section comprises unconverted ethylene, products formed during the oligomerization step and possibly solvent.

[0059] Therefore, the thermal separation step according to the invention can remove the spent catalyst by vaporization at mild temperatures. Advantageously, the use of at least two vaporization steps at mild temperatures along a decreasing pressure gradient prevents the phenomenon of activity recovery of the spent catalyst, which results in a decrease in selectivity to the desired olefins.

[0060] Another advantage of the deactivation method according to the invention is that it maximizes the selectivity towards 1-butene.

[0061] Advantageously, the first vaporization step is carried out at a pressure of 2.0-5.0 MPa, preferably 2.2-4.5 MPa, preferably 2.4-4.0 MPa, preferably 2.5-3.5 MPa and a temperature of 70-150°C, 80-140°C, preferably 90-130°C, preferably 95-120°C.

[0062] Advantageously, the second vaporization step is carried out at a pressure of 0.5-3.0 MPa, preferably 0.8-3.0 MPa, preferably 1.0-2.0 MPa, preferably 1.1-1.8 MPa, very preferably 1.2-1.5 MPa and a temperature of 70-150°C, preferably 80-140°C, preferably 90-130°C, preferably 95-125°C.

[0063] Preferably, the thermal separation step involves sending the liquid fraction obtained from the second vaporization step to a third vaporization step, the third vaporization step being carried out at a pressure of 0.1-1.5 MPa and a temperature of 70-150° C. The third vaporization step can obtain a liquid fraction and a gas fraction; preferably, the gas fraction is sent to the distillation section.

[0064] In this case, the pressure of the second vaporization step is higher than the pressure of the third vaporization step, preferably at least 0.5 MPa higher, preferably at least 0.8 MPa higher, preferably at least 1.0 MPa higher, preferably at least 1.5 MPa higher.

[0065] Preferably, the final liquid fraction obtained at the end of the last vaporization step, i.e. the second vaporization step or the third vaporization step, is sent to the incinerator, and the gas fraction obtained at the end of the last vaporization step, i.e. the second vaporization step or the third vaporization step, is sent to the distillation section.

[0066] Advantageously, the third vaporization step is carried out at a pressure of 0.1-1.5 MPa, preferably 0.3-1.2 MPa, preferably 0.4-1.0 MPa, preferably 0.5-0.8 MPa and a temperature of 70-150°C, preferably 80-140°C, preferably 80-130°C, preferably 85-130°C, preferably 90-120°C, very preferably 95-110°C.

[0067] The term "flash" refers to gas / liquid separation by means of changes in pressure and / or temperature.

[0068] Preferably, the first step and / or the second step and / or the third step of thermal separation is carried out by means of a flash vessel, which is preferably coupled to a heat exchanger or any other sequence for partially vaporizing the effluent.

[0069] Thus, a wide selection of techniques may be used to carry out any of the thermal separation steps; preferably, the techniques are selected from:

[0070] - simple evaporators with jacket, coil or thermosyphon type (or natural convection),

[0071] – more complex evaporators including horizontal tubes, vertical tubes (e.g. “rising film” or “falling film” type) or inclined tubes with forced recirculation, and

[0072] - More specific thin film evaporator systems (vertical cone, horizontal cone, short path), optionally coupled with various heating modes (steam, oil, molten salt, inductive, etc.), plate evaporators.

[0073] In a preferred embodiment, the thermal separation step does not involve a thin film evaporator as described in patent FR2733497.

[0074] In a preferred embodiment, the gaseous fraction obtained from the first vaporization step and / or the gaseous fraction obtained from the second vaporization step and / or the gaseous fraction obtained from the third vaporization step is liquefied upstream of the distillation section by lowering the temperature so as to reach a pressure of 2.0-5.0 MPa and is preferably sent to the distillation section by means of a pump. Advantageously, this embodiment makes it possible not to use a compressor, which can limit the operating costs of the process for treating the effluent obtained from the oligomerization step. Preferably, the temperature at which the gaseous fraction or fractions obtained from the vaporization step are liquefied is between 0 and 60° C., preferably between 10 and 55° C., preferably between 20 and 50° C.

[0075] Failure steps

[0076] The method according to the invention comprises a step of deactivating the effluent obtained from the oligomerization step. Preferably, the deactivation step comprises contacting the effluent with a deactivation system comprising:

[0077] - having the general formula R 1 OH alcohol, where the group R 1 Selected from:

[0078] * Straight-chain or branched alkyl containing 2 to 20 carbon atoms,

[0079] * an aromatic group containing 5 to 30 carbon atoms, and / or

[0080] - With the general formula NR 2 R 3 R 4 Amines, wherein the groups R 2 , R 3 and R 4 Independently selected from:

[0081] * Hydrogen,

[0082] * a straight-chain or branched alkyl group containing 1 to 20 carbon atoms and optionally substituted by an NH2 group,

[0083] It is preferably composed of them.

[0084] Thus, the deactivation step makes it possible to obtain an effluent in which the catalytic composition is deactivated, ie inactivated. In other words, the composition no longer has any catalytic activity for the oligomerization reaction.

[0085] Advantageously, the group R 1It may be an alkyl group containing 3 to 15 carbon atoms, preferably 4 to 14 carbon atoms, preferably 6 to 12 carbon atoms, preferably 7 to 10 carbon atoms.

[0086] In a preferred embodiment, the group R 1 It is a branched chain alkyl.

[0087] In another preferred embodiment, the group R 1 It is a straight chain alkyl group.

[0088] In a preferred embodiment, the group R 1 It is an alkyl group substituted with one or more substituents selected from hydroxy (-OH) and amino (-NH2).

[0089] Advantageously, the group R 1 It may be an aryl group containing 5 to 30 carbon atoms, preferably 5 to 20 carbon atoms, preferably 6 to 18 carbon atoms, preferably 6 to 15 carbon atoms.

[0090] Preferably, the general formula R 1 The alcohol of OH is selected from 1-propanol, 2-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, 2-methyl-3-heptanol, 1-decanol, 2-decanol, 3-decanol, 4-decanol, 5-decanol, 1-undecanol, 2-undecanol, 7-methyl-2-decanol, alcohol, 1-dodecanol, 2-dodecanol, 2-ethyl-1-decanol, phenol, 2-methylphenol, 2,6-dimethylphenol, 2,4,6-trimethylphenol, 4-methylphenol, 2-phenylphenol, 2,6-diphenylphenol, 2,4,6-triphenylphenol, 4-phenylphenol, 2-tert-butyl-6-phenylphenol, 2,4-di-tert-butyl-6-phenylphenol, 2,6-diisopropylphenol, 2,6-di-tert-butylphenol and 4-methyl-2,6-di-tert-butylphenol, alone or as a mixture. Preferably, the general formula R 1 The alcohol of OH is 2-ethyl-1-hexanol.

[0091] Preferably, the radicals R, which may be identical or different 2 , R 3 and R 4 Independently selected from hydrogen, straight chain or branched chain alkyl containing 2-20 carbon atoms, preferably 4-14 carbon atoms, preferably 6-12 carbon atoms, more preferably 7-10 carbon atoms.

[0092] In a preferred embodiment, the group R 2 , R3 and R 4 At least one of them is selected from hydrogen.

[0093] In an even more preferred embodiment, the group R 2 , R 3 and R 4 At least two of them are selected from hydrogen.

[0094] In a particular embodiment, the amine is a polyamine, such as a diamine. In other words, the group R 2 , R 3 and R 4 At least one of the groups is substituted by an amino group (-NH2). 2 , R 3 and R 4 One of the groups is substituted by an amino group (-NH2).

[0095] Preferably, the general formula NR 2 R 3 R 4 The amine is selected from 1-propylamine, 2-propylamine, isopropylamine, 1-butylamine, 2-butylamine, isobutylamine, sec-butylamine, tert-butylamine, 1-pentylamine, 2-pentylamine, 3-pentylamine, 1-hexylamine, 2-hexylamine, 3-hexylamine, 1-heptylamine, 2-heptylamine, 3-heptylamine, 4-heptylamine, 1-octylamine, 2-octylamine, 3-octylamine, 4-octylamine, 2-ethyl-1-hexylamine, 2-methyl-3-heptylamine, 1-decylamine, 2-decylamine, 3-decylamine, 4-decylamine, 5-decylamine, 1-undecylamine, 2-undecylamine, 7-methyl-2-decylamine, 1-dodecylamine, 2-dodecylamine and 2-ethyl-1-decylamine, used individually or as a mixture.

[0096] In a preferred embodiment, the failure system comprises a 1 OH alcohols and have the general formula NR 2 R 3 R 4 of amines.

[0097] Advantageously, the alcohol R is used 1 OH and amine NR 2 R 3 R 4 As a spent system it is possible to deactivate the catalytic composition, overcoming the problems associated with corrosion and recovery of the activity of said system which results in a reduction in selectivity.

[0098] Specifically, the use of alcohols and amines can synergistically prevent the spent catalytic composition from regaining activity during subsequent effluent purification steps while limiting corrosion associated with the presence of the spent catalytic composition.

[0099] When the spent system comprises an alcohol and an amine, in one embodiment the effluent obtained from the oligomerization step is contacted sequentially with the amine and then with the alcohol.

[0100] In another embodiment, the effluent obtained from the oligomerization step is advantageously brought into contact with a mixture of alcohol and amine.

[0101] In another embodiment, it is advantageous to combine the effluent obtained from the oligomerization step with a 1 OH alcohol and having the formula NR 2 R 3 R 4 of amine contact.

[0102] Advantageously, the molar ratio of the amine to the alcohol is 0.5-100, preferably 1.0-90, preferably 1.1-80, preferably 1.5-70, preferably 2.0-60, preferably 2.2-50. In a preferred embodiment, the molar ratio of the amine to the alcohol is 0.5-40, preferably 1.0-30, preferably 1.1-20, preferably 1.5-15, preferably 2.0-10, preferably 2.2-5.0.

[0103] Advantageously, the molar ratio of the deactivation system to the alkyl aluminum halide is 0.5-100, preferably 1.0-90, preferably 1.5-80, preferably 2.0-70, preferably 3.0-60, preferably 3.5-50. In a preferred embodiment, the molar ratio of the deactivation system to the alkyl aluminum halide is 0.5-50, preferably 1.0-40, preferably 1.5-30, preferably 2.0-20, preferably 3.0-15, preferably 3.5-10.0.

[0104] Preferably, the effluent obtained directly from the oligomerization step has an alkylaluminum halide content of 0.01 to 100000 weight ppm, preferably 0.1 to 10000 weight ppm, preferably 1.0 to 1000 weight ppm, preferably 2.0 to 600 weight ppm, preferably 3.0 to 400 weight ppm, preferably 5.0 to 200 weight ppm, preferably 6.0 to 100 weight ppm, preferably 8.0 to 50 weight ppm, preferably 10 to 40 weight ppm, more preferably 12 to 30 weight ppm, relative to the total weight of the effluent.

[0105] Preferably, the effluent obtained directly from the oligomerization step has an alkylaluminum chloride content such that the chlorine content, relative to the total weight of the effluent, is from 0.1 to 100 000 ppm by weight, preferably from 1.0 to 10 000 ppm by weight, preferably from 2.0 to 1000 ppm by weight, preferably from 3.0 to 600 ppm by weight, preferably from 4.0 to 400 ppm by weight, preferably from 5.0 to 200 ppm by weight, preferably from 8.0 to 100 ppm by weight, preferably from 10 to 80 ppm by weight, preferably from 12 to 70 ppm by weight, more preferably from 15 to 60 ppm by weight.

[0106] The spent system is preferably brought into contact with the effluent obtained from the oligomerization step at a temperature ranging from -40 to 250° C., preferably from -20° C. to 150° C., preferably from 20° C. to 100° C., preferably from 30° C. to 80° C., very preferably from 40° C. to 60° C. Advantageously, the temperature at which the spent system is brought into contact with the effluent obtained from the oligomerization step is the temperature at which the oligomerization step takes place.

[0107] Advantageously, the general formula R 1 OH and / or alcohols having the general formula NR 2 R 3 R 4 The amines can be used in the same or different solvents. The solvent can be selected from any solvent that can dilute or dissolve the amine and / or the alcohol.

[0108] Advantageously, the solvent may be chosen from one or more solvents as described above for the catalytic composition.

[0109] "Optional" oligomerization step

[0110] Advantageously, the effluent treated in the process according to the invention is obtained at the end of an oligomerization step, preferably of ethylene to olefins, using a catalytic composition comprising an alkylaluminum halide and preferably a metal precursor, in particular a nickel precursor, said step allowing the production of said effluent treated in the process according to the invention, preferably in liquid form and comprising unconverted ethylene, the products formed during the oligomerization step, said catalytic composition and, optionally, a solvent.

[0111] Preferably, the olefins obtained at the end of the oligomerization step are 1-butene, 2-butene, 1-hexene and / or 1-octene, alone or as a mixture.

[0112] The oligomerization step is preferably carried out in the presence of the catalytic composition, which preferably comprises an alkylaluminum halide and a nickel precursor, wherein the nickel concentration is advantageously 10 -12 to 1.0 mol / L, preferably 10 -9 To 0.4mol / L.

[0113] Advantageously, the oligomerization step is carried out at a pressure of 0.1-20.0 MPa, preferably 0.1-15.0 MPa, preferably 0.5-8.0 MPa and a temperature of -40 to 250°C, preferably -20 to 150°C, preferably 20°C-100°C, preferably 30-80°C.

[0114] Preferably, the oligomerization step is a step of dimerization of ethylene into 1-butene and / or 2-butene, trimerization of ethylene into 1-hexene, or tetramerization of ethylene into 1-octene.

[0115] Advantageously, the oligomerization step can be carried out continuously or batchwise.

[0116] In a preferred embodiment, the ingredients of the catalytic composition are injected into a stirred reactor by conventional mechanical means or by external recirculation, wherein the olefin is preferably reacted under temperature control. In another embodiment, the alkylaluminum halide and the solution comprising the nickel precursor and optionally the ligand are injected into a stirred reactor by conventional mechanical means or by external recirculation, wherein the olefin is preferably reacted under temperature control.

[0117] Catalytic composition

[0118] Thus, the effluent treated in the process according to the invention is obtained from a step of oligomerization of ethylene to olefins using a catalytic composition comprising an alkylaluminum halide and preferably a nickel precursor.

[0119] Preferably, the nickel precursor is selected from nickel (II) chloride, nickel (II) chloride (dimethoxyethane), nickel (II) bromide, nickel (II) bromide (dimethoxyethane), nickel (II) fluoride, nickel (II) iodide, nickel (II) sulfate, nickel (II) carbonate, dimethylglyoxime nickel (II), nickel (II) hydroxide, nickel (II) hydroxyacetate, nickel (II) oxalate, nickel (II) carboxylate (e.g. nickel 2-ethylhexanoate), nickel (II) phenol, nickel (II) cyclohexane acid, nickel (II) acetate, nickel (II) trifluoroacetate, nickel (II) trifluoromethanesulfonate, nickel (II) stearate, nickel (II) formate, nickel (II) acetylacetonate, nickel (II) hexafluoroacetylacetonate, π-allyl nickel (II) chloride, π-allyl nickel (II) bromide, methylallyl nickel (II) chloride dimer, n-hexafluorophosphate 3 -Allyl nickel (II), hexafluorophosphate η 3 - Methylallylnickel(II) and 1,5-cyclooctadienylnickel(II), in the form of their hydrates or non-hydrates, used individually or as a mixture.

[0120] Preferably, the nickel precursor is selected from nickel (II) sulfate, nickel (II) carbonate, nickel (II) diacetyl oxime, nickel (II) hydroxide, nickel (II) hydroxyacetate, nickel (II) oxalate, nickel (II) carboxylate (e.g. nickel 2-ethylhexanoate), nickel (II) phenol, nickel (II) cyclohexane acid, nickel (II) acetate, nickel (II) trifluoroacetate, nickel (II) trifluoromethanesulfonate, nickel (II) acetylacetonate, nickel (II) hexafluoroacetylacetonate, π-allyl nickel (II) chloride, π-allyl nickel (II) bromide, methylallyl nickel (II) chloride dimer, n-hexafluorophosphate 3 -Allyl nickel (II), hexafluorophosphate η 3 - Methylallylnickel(II) and 1,5-cyclooctadienylnickel(II), in the form of their hydrates or non-hydrates, used individually or as a mixture.

[0121] Advantageously, the alkylaluminum halide corresponds to the formula [Al m R 5 n X 3-n ] o ,in:

[0122] -R 5 is a straight or branched chain alkyl group containing 1 to 12 carbon atoms,

[0123] - X is a chlorine or bromine atom, preferably a chlorine atom, and

[0124] - m is selected from 1 and 2,

[0125] - n is selected from 0, 1 and 2,

[0126] - o Choose from 1 and 2.

[0127] When m is equal to 2, the group R 5 Can be the same or different.

[0128] Preferably, R 5 It is selected from straight or branched chain alkyl groups containing 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms.

[0129] Preferably, R 5 is an alkyl group selected from methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl and octyl. 5 is an alkyl group selected from ethyl, propyl, isopropyl, n-butyl and tert-butyl.

[0130] Advantageously, the alkylaluminum halide is selected from methylaluminum dichloride (MeAlCl2), ethylaluminum dichloride (EtAlCl2), ethylaluminum sesquichloride (Et3Al2Cl3), diethylaluminum chloride (Et2AlCl), diisobutylaluminum chloride (iBu2AlCl) and isobutylaluminum dichloride (iBuAlCl2), used alone or as a mixture.

[0131] The molar ratio of the alkylaluminum halide to the nickel precursor, expressed as Al / Ni, is preferably greater than or equal to 5, more preferably greater than or equal to 6, and preferably less than or equal to 30, preferably less than or equal to 25, more preferably less than or equal to 20.

[0132] Advantageously, the catalytic composition may also comprise a ligand chosen from phosphines.

[0133] In another embodiment, the catalytic composition comprises a catalytic composition selected from the group consisting of 6 R 7 R 8 The phosphine ligand, wherein the group R 6 , R 7 and R 8 may be the same or different, optionally connected to each other, and are selected from:

[0134] - substituted or unsubstituted aromatic groups, optionally containing heteroelements,

[0135] - and / or cyclic or acyclic, substituted or unsubstituted alkyl, optionally containing hetero elements.

[0136] According to the invention, advantageously, the catalytic composition comprises at least one compound having the formula PR 6 R 7 R 8 The phosphine ligand, wherein the group R 6 , R 7 and R 8 same.

[0137] Phosphine ligand PR 6 R 7 R 8 The aromatic group R 6 , R 7 and R 8 Preferably, it is selected from phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropoxyphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-di-tert-butyl-4-methoxyphenyl, 4-chlorophenyl, 3,5-bis(trifluoromethyl)phenyl, benzyl, naphthyl, binaphthyl, pyridyl, biphenyl, furyl and thiophenyl.

[0138] Phosphine ligand PR 6 R 7 R 8 The alkyl R 6 , R 7 and R 8 Advantageously contains 1 to 20 carbon atoms, preferably 2 to 15 carbon atoms, preferably 3 to 10 carbon atoms. Preferably, the phosphine ligand PR 6 R 7 R 8 The alkyl R 6 , R 7 and R 8 Selected from methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, cyclopentyl, cyclohexyl, benzyl and adamantyl groups.

[0139] Advantageously, having the formula PR 6 R 7 R 8 The molar ratio between the phosphine ligand and the nickel precursor is 5-25, preferably 5-20, more preferably 5-15. Preferably, the molar ratio is 6-30, preferably 6-25, more preferably 6-20, even more preferably 6-15, even more preferably 7-14.

[0140] In a preferred embodiment, each component or mixture of components of the catalytic composition may be used in a solvent.

[0141] The solvent or solvents are advantageously selected from:

[0142] - ethers, alcohols, halogenated solvents and hydrocarbons, which are saturated or unsaturated, cyclic or acyclic, aromatic or non-aromatic and contain 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms, preferably 4 to 15 carbon atoms,

[0143] - Ionic liquids.

[0144] Preferably, the solvent is selected from pentane, hexane, cyclohexane, methylcyclohexane, heptane, butane or isobutane, 1,5-cyclooctadiene, benzene, toluene, o-xylene, mesitylene, ethylbenzene, diethyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, dichloroethane, chlorobenzene, dichlorobenzene, methanol and ethanol (pure substances or as mixtures) and ionic liquids.

[0145] In the case where the solvent is an unsaturated hydrocarbon, the solvent may advantageously be selected from the products of oligomerization reactions.

[0146] In the case where the solvent is an ionic liquid, the solvent is advantageously selected from N-butylpyridinium hexafluorophosphate, N-ethylpyridinium tetrafluoroborate, pyridinium fluorosulfonate, 3-butyl-1-methylimidazolium tetrafluoroborate, 3-butyl-1-methylimidazolium bistrifluoromethanesulfonimide, triethylsulfonium bistrifluoromethanesulfonimide, 3-butyl-1-methylimidazolium hexafluoroantimonate, 3-butyl-1-methylimidazolium hexafluoro phosphate, 3-butyl-1-methylimidazolium trifluoroacetate, 3-butyl-1-methylimidazolium trifluoromethanesulfonate, trimethylphenylammonium hexafluorophosphate, tetrabutylphosphonium tetrafluoroborate, tetrabutylphosphonium chloride, N-butylpyridinium chloride, ethylpyridinium bromide, 3-butyl-1-methylimidazolium chloride, diethylpyrazolium chloride, pyridinium hydrochloride, trimethylphenylammonium chloride, and butylmethylpyrrolidinium chloride.

[0147] Separation step in the "optional" distillation stage

[0148] Typically, the olefins obtained from the ethylene oligomerization step have a higher molecular weight than the unreacted ethylene. In general, the unreacted ethylene has a lower boiling point than the oligomers (e.g., 1-butene, 2-butene, 1-hexene, or 1-octene) obtained from the oligomerization step.

[0149] According to the invention, any separation means known to a person skilled in the art that exploits these differences in volatility and molecular weight between the products to be separated can be used in the separation step. Advantageously, according to the invention, the separation means used is any type of distillation column.

[0150] The process according to the invention optionally comprises a separation step which advantageously comprises a distillation section. Preferably, according to the process according to the invention, the gaseous fraction obtained from the thermal separation step, in particular the gaseous fraction comprising unconverted ethylene, formed products and solvent, is sent to a distillation section in the form of a gas / liquid mixture.

[0151] The distillation section advantageously comprises at least three distillation columns, preferably at least four distillation columns. According to a preferred variant of the invention, the distillation section comprises four distillation columns.

[0152] The following examples illustrate the invention without limiting its scope. Example

[0153] Implementation of the oligomerization step

[0154] 93 mL of n-heptane was placed in a reactor that had been dried under vacuum and placed under an ethylene atmosphere, and then 6 mL of a solution containing the nickel precursor Ni(2-ethylhexanoate)2 (expressed as Ni(2-EH)2, 40 µmol) and tricyclohexylphosphine (PCy3) (400 µmol) was added. Then 1-2 grams of ethylene was dissolved in the reactor, stirring was started, and the temperature was set to 40°C. After the reactor was degassed, the temperature was set to 45°C (test temperature). Then 1 mL of a solution of ethylaluminum dichloride (600 µmol) was introduced. The reactor was set at the test pressure (2 MPa). Stirring was started and the reaction was carried out under pressure control, and ethylene feed was used so that the pressure could be maintained at the test pressure. After the desired ethylene consumption was reached, the ethylene feed was stopped. The liquid effluent was invalidated using an invalidation system.

[0155] In the following examples, the gas effluent was quantitatively and qualitatively analyzed by gas chromatography (GC), and the liquid phase was quantitatively and qualitatively analyzed by GC.

[0156] Example 1: Thermal separation step with two vaporization steps in series (according to the invention)

[0157] The spent effluent obtained at the end of the above oligomerization step is compressed to a pressure of 3.25 MPa and then partially vaporized by heating in a heat exchanger to a temperature of 115° C. The gaseous fraction is then separated from the liquid fraction in a vessel. The gaseous fraction is sent to the distillation section and the liquid fraction to the second flash.

[0158] The liquid fraction produced by the first flash is expanded to a pressure of 1.35 MPa. The expanded liquid fraction is then partially vaporized by heating to a temperature of 117° C. in a heat exchanger. The gaseous fraction is then separated from the liquid fraction in a container. The gaseous fraction is sent to a distillation section, and the liquid phase containing the spent catalyst is sent to an incinerator.

[0159] The conditions of the various steps and the composition of each stream are listed in Table 1 below. The final liquid effluent obtained from the second flash contains heteroelements (Ni, P, Al, Cl, O, N, etc.) obtained from the catalytic system and one or more inhibitors and their associated organic fractions.

[0160] It can be seen that the use of a thermal separation step comprising two flash distillations in series allows the spent catalyst to be separated from the products of interest while maximizing the amount of olefins of interest (1-butene, denoted as B1, and 2-butene, denoted as B2) sent to the distillation section, which can maximize the productivity of the oligomerization process.

[0161] Furthermore, no isomerization problems are observed during the thermal separation step, which makes it possible to send more than 99% of the butenes formed during the oligomerization step to the distillation section without losing selectivity.

[0162] [Table 1]

[0163]

[0164] Table 1: Operating conditions and composition of streams entering and leaving the spent catalyst separation section.

[0165] Example 2: Thermal separation step with three vaporization steps in series (according to the invention)

[0166] The spent effluent obtained at the end of the above oligomerization step is compressed to a pressure of 3.25 MPa and then partially vaporized by heating to a temperature of 115° C. in a heat exchanger. The gaseous fraction is then separated from the liquid fraction in a vessel. The gaseous fraction is sent to the distillation section and the liquid fraction to the second flash.

[0167] The liquid fraction produced by the first flash is expanded to a pressure of 1.3 MPa. The expanded liquid fraction is then partially vaporized by heating to a temperature of 107° C. in a heat exchanger. The gaseous fraction is then separated from the liquid fraction in a container. The gaseous fraction is sent to the distillation section, and the liquid fraction is sent to the third flash.

[0168] The liquid fraction produced by the second flash was expanded to a pressure of 0.5 MPa. The expanded liquid fraction was then vaporized by heating to a temperature of 98°C in a heat exchanger.

[0169] The conditions of the various steps and the composition of each stream are listed in Table 2 below. The final liquid effluent obtained from the third flash contains heteroelements (Ni, P, Al, Cl, O, N, etc.) obtained from the catalytic system and one or more inhibitors and their associated organic fractions.

[0170] Advantageously, in this separation embodiment, isomerization of the desired olefin is not observed, which allows for maximizing the recovery of the product of interest.

[0171] [Table 2]

[0172]

[0173] Table 2: Operating conditions and composition of streams entering and leaving the spent catalyst separation section.

[0174] Example 3: Failure Steps

[0175] Failure steps

[0176] The effluent obtained at the end of the above oligomerization step was contacted with a spent system comprising 2-ethylhexylamine and 2-ethylhexanol at a temperature of 50°C and various molar ratios of amine and alcohol to ethylaluminium dichloride (denoted as Al). The results obtained are shown in the table below. Isomerization was monitored by GC.

[0177] [Table 3]

[0178]

[0179] Table 3: Conditions during the failure step

[0180] nd: Not detected.

[0181] Therefore, the deactivation system according to the invention, preferably one comprising an alcohol and an amine, makes it possible to ensure deactivation of the mixture while maintaining the selectivity towards the desired olefins obtained from the oligomerization step, while preventing corrosion problems associated with the presence of chlorine.

Claims

1. A method for treating an effluent obtained from an ethylene dimerization step, said method comprising a step of spending said effluent to deactivate the catalytic composition, followed by a step of thermal separation of the spent effluent, said thermal separation step comprising: - a first vaporization step, which is carried out at a pressure of 2.0-5.0 MPa and a temperature of 90-130° C., to obtain a liquid fraction sent to a second vaporization step, and a gaseous fraction sent to a distillation section, - a second vaporization step, which is carried out at a pressure of 0.5-3.0 MPa and a temperature of 90-130° C. to obtain a liquid fraction sent to a third vaporization step, and a gaseous fraction; said gaseous fraction is sent to a distillation section, - a third vaporization step, which is carried out at a pressure of 0.1-1.5 MPa and a temperature of 80-130° C. to obtain a liquid fraction and a gaseous fraction; the gaseous fraction is sent to a distillation section, - wherein the pressure of the first vaporization step is at least 0.5 MPa higher than the pressure of the second vaporization step, and the pressure of the second vaporization step is at least 0.5 MPa higher than the pressure of the third vaporization step. 2 . The method according to claim 1 , wherein the pressure of the first vaporization step is at least 1.0 MPa higher than the pressure of the second vaporization step.

3. The method according to claim 1, wherein the pressure of the first vaporization step is at least 1.5 MPa higher than the pressure of the second vaporization step. 4 . The method according to claim 1 , wherein the pressure of the second vaporization step is at least 0.8 MPa higher than the pressure of the third vaporization step.

5. The method according to claim 1, wherein the first vaporization step is performed at a pressure of 2.0 MPa to 4.5 MPa. The method according to claim 1 , wherein the first vaporization step is performed at a pressure of 2.5 MPa to 4.0 MPa.

7. The method according to any one of claims 1 to 6, wherein the second vaporization step is performed at a pressure of 0.8 MPa to 3.0 MPa.

8. The method according to any one of claims 1 to 6, wherein the second vaporization step is performed at a pressure of 1.0 MPa to 2.0 MPa.

9. The method according to any one of claims 1 to 6, wherein the third vaporization step is performed at a pressure of 0.3 MPa to 1.2 MPa.

10. The method according to any one of claims 1 to 6, wherein the third vaporization step is performed at a pressure of 0.4 MPa to 1.0 MPa.

11. The method according to any one of claims 1 to 6, wherein the first step and / or the second step and / or the third step of thermal separation is performed by a flash vessel, which is coupled to a heat exchanger.

12. The process according to any one of claims 1 to 6, wherein the gas fraction obtained from the first vaporization step and / or the gas fraction obtained from the second vaporization step and / or the gas fraction obtained from the third vaporization step is liquefied by lowering the temperature to reach a pressure of 2.0-5.0 MPa and sent to the distillation section.

13. The process according to claim 12, wherein the temperature at which the one or more gas fractions obtained from the vaporization step are liquefied is from 0 to 60°C.

14. The process according to any one of claims 1 to 6, wherein the ethylene dimerization step uses a catalytic composition comprising an alkylaluminum halide and optionally a nickel precursor.

15. The method of claim 14, wherein the alkylaluminum halide corresponds to the formula [Al m R 5 n X 3-n ] o ,in: -R 5 is a straight or branched chain alkyl group containing 1 to 12 carbon atoms, - X is a chlorine or bromine atom, and - m is selected from 1 and 2, - n is selected from 0, 1 and 2, - o Choose from 1 and 2.

16. The process according to claim 14, wherein the effluent obtained from the ethylene dimerization step has an alkylaluminum halide content of 0.01 to 100000 ppm by weight.

17. The process according to any one of claims 1 to 6, wherein the step of deactivating the effluent obtained from the ethylene dimerization step is carried out by contacting said effluent with a deactivation system comprising: - having the general formula R 1 OH alcohol, where the group R 1 Selected from: * A straight or branched chain alkyl group containing 2 to 20 carbon atoms or * an aromatic group containing 5 to 30 carbon atoms, and / or - With the general formula NR 2 R 3 R 4 Amines, wherein the same or different groups R 2 , R 3 and R 4 Independently selected from: * Hydrogen or * Straight-chain or branched alkyl containing 1 to 20 carbon atoms and optionally substituted by NH2 groups.

18. The method of claim 17, wherein the temperature at which the spent system is contacted with the effluent obtained from the ethylene dimerization step is the temperature at which the ethylene dimerization step occurs.

19. The method of claim 17, wherein the failure system comprises a 1 OH alcohols and have the general formula NR 2 R 3 R 4 of amines.

20. The method according to claim 19, wherein the molar ratio of the amine to the alcohol is 0.5-100.

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