Oligomerization method with headspace recycling

Abstract

The present invention relates to an oligomerization process carried out in a gas / liquid reactor containing a gaseous headspace recycle loop. In particular, the process relates to the oligomerization of ethylene to linear alpha-olefins, such as 1-butene, 1-hexene, 1-octene, or a mixture of linear alpha-olefins.

Description

[Technical field]

[0001] The present invention relates to an oligomerization process carried out in a gas / liquid reactor containing a headspace recycle loop, and more particularly to the oligomerization of ethylene to linear alpha-olefins, such as 1-butene, 1-hexene, 1-octene or a mixture of linear alpha-olefins. [Background technology]

[0002] The present invention relates to the field of oligomerization processes employing gas / liquid reactors, also called bubble columns. Due to the exothermic nature of the oligomerization reaction, bubble columns also contain a recirculation loop whereby a liquid fraction is withdrawn, cooled, and reintroduced into the reaction chamber. The recirculation loop allows high concentration uniformity and temperature control throughout the reaction volume due to the high heat transfer capacity associated with the recirculation loop.

[0003] One disadvantage encountered in oligomerization processes when using this type of column is the management of the gas phase, also known as the headspace, since said headspace contains gaseous components with low solubility in the liquid phase, inert compounds that are partially soluble in the liquid, and gaseous ethylene that is not soluble in the liquid. The passage of gaseous ethylene from the liquid phase towards the gaseous phase (or headspace) is a phenomenon called breakthrough. The headspace is purged to remove said gaseous compounds. When the amount of gaseous ethylene present in the headspace is significant, purging the headspace results in a significant loss of ethylene, which is detrimental to the productivity and cost of the oligomerization process.

[0004] Therefore, in order to improve the efficiency of the oligomerization process in terms of productivity and costs, it is important to limit the loss of unreacted ethylene contained in the headspace and improve its conversion in said process, while retaining a high selectivity towards the desired linear alpha-olefins.

[0005] Prior art processes employing a recirculation loop, as shown in FIG. 1, do not make it possible to limit the loss of gaseous ethylene; purging the headspace results in the exit of gaseous ethylene from the reactor, which is detrimental to the yield and costs of the process.

[0006] In patent applications (Patent Documents 1 and 2), the applicant describes methods that allow an increase in the contact surface area between the top of the liquid fraction and the headspace, by means of dispersion means or vortexes, to promote the passage of the ethylene contained in the headspace to the liquid / gas interface. However, these methods are insufficient when the amount of ethylene in the headspace is significant due to high levels of breakthrough.

[0007] Furthermore, in the course of the research, the Applicant has discovered that in a reactor operating at a constant injection rate of gaseous ethylene, the amount of dissolved ethylene, and therefore the level of breakthrough, depends on the dimensions of the reactor in which the process is carried out, and in particular on the height of the liquid phase: in fact, the lower the height, the shorter the time for gaseous ethylene to reach the liquid phase for dissolution, leading to a higher level of breakthrough.

[0008] The applicant has surprisingly found a new process employing a headspace recycling step to the bottom of the liquid phase, which allows optimization of the dissolution of the gaseous ethylene introduced into the process and regulation of the pressure in the reactor, without resulting in ethylene losses, regardless of the dimensions of the reactor employed. More specifically, the process allows the selective production of linear alpha-olefins, such as 1-butene, 1-hexene and 1-octene.

[0009] Another advantage of the recycling step according to the invention is that it allows a simple and economical compensation of the phenomenon of breakthrough of gaseous ethylene into the headspace in oligomerization processes, regardless of the reactor dimensions. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2019 / 011806 [Patent Document 2] International Publication No. 2019 / 011609 Summary of the Invention [Means for solving the problem]

[0011] BRIEF DESCRIPTION OF THE DRAWINGS The present invention relates to an oligomerization process carried out in a gas / liquid reactor at a pressure of 0.1-10.0 MPa and a temperature of 30-200° C., comprising the following steps: a) introducing an oligomerization catalyst system comprising a metal catalyst and an activator into a reaction chamber comprising a liquid phase in a lower zone and a gas phase in an upper zone; b) contacting said catalyst system with gaseous ethylene by introducing said ethylene into a lower zone of a reaction chamber; c) withdrawing the liquid fraction; d) cooling the fraction withdrawn in step c) by passing said fraction through a heat exchanger; e) introducing the cooled fraction from step d) into an upper portion of the lower zone of the reaction chamber; f) recycling the gas fraction withdrawn from the upper zone of the reaction chamber and introduced into the lower zone of the reaction chamber into the liquid fraction. The present invention relates to a method comprising the steps of:

[0012] Preferably, the liquid phase in the lower zone of the reaction chamber has a saturation level in dissolved ethylene of greater than 70.0%.

[0013] Preferably, the gas phase withdrawn in step f) is introduced in a mixture with the gaseous ethylene introduced in step b).

[0014] Preferably, the gaseous fraction withdrawal rate in step f) is 0.1 to 100% of the flow rate of the gaseous ethylene introduced in step b).

[0015] Preferably, the gaseous fraction withdrawn in step f) is introduced into the lower lateral part of the reaction chamber.

[0016] Preferably, the withdrawal rate of the gaseous fraction in step f) depends on the pressure in the reaction chamber.

[0017] Preferably, the second gaseous purge stream is withdrawn from the gas phase.

[0018] Preferably, the flow rate of the second gas stream is 0.005 to 1.00% of the flow rate of the ethylene introduced in step b).

[0019] Preferably, the gaseous hydrogen stream is introduced in step b) into the reaction chamber at a flow rate representing 0.2-1.0% by mass of the incoming ethylene flow rate.

[0020] Preferably, the concentration of catalyst in the catalyst system is from 0.1 to 50.0 ppm by mass of atomic metal relative to the reactant mass.

[0021] Preferably, the catalytic oligomerization reaction is carried out continuously.

[0022] Preferably, the linear olefin obtained contains from 4 to 20 carbon atoms.

[0023] The present invention relates to a device for carrying out the above-mentioned ethylene oligomerization process, comprising: i) a reaction chamber of elongated shape along a vertical axis, a liquid phase located in the lower zone, comprising, and preferably consisting of, the reaction products, gaseous and dissolved ethylene, the catalyst system, and optionally a solvent; and a gas phase containing gaseous ethylene and also non-condensable gases (particularly methane) disposed in an upper zone above the lower zone; means for - ii) means for introducing gaseous ethylene, said means being arranged at a lower side of said reaction chamber and employing means for distributing gaseous ethylene within said liquid phase of said reaction chamber; - iii) a means for introducing a catalytic system, said catalytic system comprising one metal catalyst, at least one activating substance and at least one additive substance, said means being placed in the lower part of the reaction chamber, - a recirculation loop iv) comprising withdrawal means at the base (preferably at the bottom) of the reaction chamber for withdrawing a liquid fraction towards a heat exchanger enabling said liquid to be cooled, and means for introducing said cooled liquid, said introduction taking place into the liquid phase in the upper part of the lower zone of the reaction chamber, v) a recycle loop for the headspace of the liquid phase to the lower zone, comprising means for withdrawing the gaseous fraction in the gas phase of the reaction chamber and means for introducing said withdrawn gaseous fraction into the liquid phase in the lower zone of the reaction chamber. The present invention also relates to a device comprising:

[0024] Preferably, in said device, the extracted gaseous fraction is introduced by means ii) for introducing gaseous ethylene.

[0025] Preferably, in said device, the gaseous fraction withdrawn in the recycle loop v) is introduced via a gas straightener. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] (Definitions and Abbreviations) Throughout this description, the following terms or abbreviations have the following meanings: Oligomerization is understood to mean the addition reaction of a first olefin with a second olefin, which is identical or different from the first olefin. The olefins thus obtained have the empirical formula C n H 2n where n is 4 or greater.

[0027] Alpha-olefin is understood to mean an olefin in which the double bond is located in the terminal position of the alkyl chain.

[0028] A catalyst system is understood to mean a mixture of at least one metal catalyst and at least one activating substance, optionally in the presence of at least one additive substance and optionally in the presence of at least one solvent.

[0029] Liquid phase is understood to mean any mixture of compounds that is in a liquid physical state under the temperature and pressure conditions of the reaction chamber.

[0030] The gas phase, also called headspace, is understood to mean all the mixtures of compounds that are in a gaseous physical state under the temperature and pressure conditions of the reaction chamber: in the form of gas bubbles present in a liquid and also in the form of gas bubbles present at the top of the reactor (reactor headspace).

[0031] The lower zone of the reaction chamber is understood to mean the part of the chamber which contains the liquid phase, gaseous ethylene, the products of the reaction, e.g. the desired linear alpha-olefins (i.e. but-1-ene, hex-1-ene, oct-1-ene), and the catalyst system.

[0032] The upper zone of the reaction chamber is understood to mean the apex of the chamber, in other words the part of the chamber located directly above the lower zone and consisting of the headspace.

[0033] The lateral lower part of the reaction chamber is understood to mean the part of the shell of the reactor that is placed in the bottom and on the side.

[0034] A non-condensable gas is understood to mean a substance in gaseous physical form that dissolves only partially in liquid at the temperature and pressure conditions of the reaction chamber and that can accumulate in the headspace of the reactor under certain conditions (e.g., ethane).

[0035] By t / h is understood the value of the velocity expressed in tons per hour, and by kg / s is understood the value of the flow rate expressed in kilograms per second.

[0036] The terms "reactor" or "device" mean all the means making it possible to carry out the oligomerization process according to the invention, such as in particular the reaction chamber and the redistribution loop.

[0037] Lower preferably means the lower quadrant of the reaction chamber.

[0038] Fresh gaseous ethylene is understood to mean ethylene external to the process which is introduced via means ii) of the process according to the invention in step b).

[0039] Detailed Description of the Invention It is expressly stated that throughout this specification the expression "between ... and ..." is to be understood as inclusive of the limitations referred to.

[0040] Within the meaning of the present invention, the various embodiments presented can be used alone or in combination with one another without any restrictions.

[0041] The present invention relates to an oligomerization process carried out in a gas / liquid reactor at a pressure of 0.1-10.0 MPa and a temperature of 30-200° C., comprising the following steps: a) introducing an oligomerization catalyst system comprising a metal catalyst and an activator into a reaction chamber comprising a liquid phase in a lower zone and a gas phase in an upper zone; b) contacting said catalyst system with gaseous ethylene by introducing said ethylene into a lower zone of a reaction chamber; c) withdrawing the liquid fraction; d) cooling the fraction withdrawn in step c) by passing said fraction through a heat exchanger; e) introducing the cooled fraction from step d) into an upper portion of the lower zone of the reaction chamber; f) recycling the gaseous fraction withdrawn from the upper zone of the reaction chamber and introduced into the lower zone of the reaction chamber into the liquid fraction. The present invention relates to a method comprising the steps of:

[0042] Preferably, in a gas / liquid reactor, the flow rate of gaseous ethylene introduced in step b) depends on the pressure in the reaction chamber. Thus, in the case of an increase in pressure in the reactor, due to a high level of breakthrough by ethylene into the gas phase, the flow rate of gaseous ethylene introduced in step b) falls, leading to a decrease in the amount of ethylene dissolved in the liquid phase and therefore in ethylene saturation. This decrease is detrimental to the conversion of ethylene, accompanied by a decrease in the productivity of the reactor and possibly a decrease in its selectivity.

[0043] The process according to the invention advantageously has a degree of saturation of ethylene dissolved in the liquid phase greater than or equal to 70.0%, preferably between 70.0 and 100%, preferably between 80.0 and 100%, preferentially between 80.0 and 99.0%, preferably between 85.0 and 99.0% and even more preferably between 90.0 and 98.0%.

[0044] The saturation of dissolved ethylene may be measured by any method known to those skilled in the art, for example by gas chromatography (commonly referred to as GC) analysis of a fraction of the liquid phase withdrawn from the reaction chamber.

[0045] Another advantage of the recycling step according to the invention is that it allows a simple and economical compensation for the phenomenon of breakthrough of gaseous ethylene into the headspace in oligomerization processes, regardless of the reactor size.

[0046] (Oligomerization Method) The oligomerization process according to the invention makes it possible to obtain linear alpha-olefins by contacting ethylene and a catalytic system, optionally in the presence of a solvent.

[0047] Any catalytic system known to a person skilled in the art and which can be employed in the dimerization, trimerization or tetramerization process, or more generally in the oligomerization process, according to the invention, falls within the field of the present invention. Said catalytic systems and also their implementation are described in particular in patent applications FR 2 984 311, FR 2 552 079, FR 3 019 064, FR 3 023 183, FR 3 042 989 or else in application FR 3 045 414.

[0048] Preferably, the catalyst system comprises, preferably consists of: - a metal precursor, preferably based on nickel, titanium or chromium, - activator, - optional added substances, and Optionally, a solvent.

[0049] (Metal Precursors) The metal precursors used in the catalyst system are selected from compounds based on nickel, titanium or chromium.

[0050] In one embodiment, the metal precursor is based on nickel, preferably comprising nickel having an oxidation state of (+II). Preferably, the nickel precursor is a nickel(II) carboxylate, such as nickel(II) 2-ethylhexanate, nickel(II) phenate, nickel(II) naphthenate, nickel(II) acetate, nickel(II) trifluoroacetate, nickel(II) triflate, nickel(II) acetylacetonate, nickel(II) hexafluoroacetylacetonate, π-allylnickel(II) chloride, π-allylnickel(II) bromide, methallylnickel(II) chloride dimer, η 3 -Allylnickel(II) hexafluorophosphate, η 3 - methallylnickel(II) hexafluorophosphate and nickel(II) 1,5-cyclooctadienyl in their hydrated or non-hydrated forms, employed alone or as a mixture.

[0051] In a second embodiment, the metal precursor is titanium-based, preferably comprising an aryloxy or alkoxy compound of titanium.

[0052] The titanium alkoxy compound is advantageously of the general formula [Ti(OR) 4

[0033] where R is a linear or branched alkyl group. Among suitable alkoxy groups, mention may be made, as non-limiting examples, of tetraethoxy, tetraisopropoxy, tetra(n-butoxy) and tetra(2-ethylhexyloxy).

[0053] The titanium aryloxy compound is advantageously of the general formula [Ti(OR') 4where R' is an aryl group, substituted or unsubstituted with alkyl or aryl groups. The R' group can include heteroatom-based substituents. Preferred aryloxy groups are selected from phenoxy, 2-methylphenoxy, 2,6-dimethylphenoxy, 2,4,6-trimethylphenoxy, 4-methylphenoxy, 2-phenylphenoxy, 2,6-diphenylphenoxy, 2,4,6-triphenylphenoxy, 4-phenylphenoxy, 2-(tert-butyl)-6-phenylphenoxy, 2,4-di(tert-butyl)phenoxy, 2,6-diisopropylphenoxy, 2,6-di(tert-butyl)phenoxy, 4-methyl-2,6-di(tert-butyl)phenoxy, 2,6-dichloro-4-(tert-butyl)phenoxy and 2,6-dibromo-4-(tert-butyl)phenoxy, biphenyl groups, binaphthoxy or 1,8-naphthalenedioxy.

[0054] According to a third embodiment, the metal precursor is based on chromium, preferably comprising chromium(II) salts, chromium(III) salts or salts with different oxidation states, which may contain one or more identical or different anions, such as halide, carboxylate, acetylacetonate or alkoxy or aryloxy anions. Preferably, the chromium-based precursor is CrCl 3 , CrCl 3 (Tetrahydrofuran) 3 , Cr(acetylacetonate) 3 , Cr(naphthenate) 3 , Cr(2-ethylhexanoate) 3 or Cr(acetate) 3 Selected from.

[0055] The concentration of nickel, titanium or chromium is between 0.01 and 300.0 ppm by weight of atomic metal relative to the reaction mass, preferably between 0.02 and 100.0 ppm, preferentially between 0.03 and 50.0 ppm, more preferentially between 0.5 and 20.0 ppm, even more preferentially between 2.0 and 50.0 ppm by weight of atomic metal relative to the reaction mass.

[0056] (Activator) Whatever the metal precursor, the catalyst system can be prepared by adding an aluminum-based compound, such as methylaluminum dichloride (MeAl 2 ), dichloroethylaluminum (EtAl 2 ), ethylaluminum sesquichloride (Et 3 Al 2 Cl 3 ), chlorodiethylaluminum (Et 2 AlCl), chlorodiisobutylaluminum (i-Bu 2 AlCl), triethylaluminum (AlEt 3 ), tripropylaluminum (Al(n-Pr) 3 ), triisobutylaluminum (Al(i-Bu) 3 ), diethylethoxyaluminum (Et 2 AlOEt), methylaluminoxane (MAO), ethylaluminoxane, and modified methylaluminoxane (MMAO).

[0057] (Additive substances) In some cases, the catalyst system includes one or more additional materials.

[0058] When the catalytic system is based on nickel, the additive material is chosen from: - compounds of the nitrogenous type, such as trimethylamine, triethylamine, pyrrole, 2,5-dimethylpyrrole, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-methoxypyridine, 3-methoxypyridine, 4-methoxypyridine, 2-fluoropyridine, 3-fluoropyridine, 3-trifluoromethylpyridine, 2-phenylpyridine, 3-phenylpyridine, 2-benzylpyridine, 3,5-dimethylpyridine, 2,6-di(tert-butyl)pyridine and 2,6-diphenylpyridine, quinoline, 1,10-phenanthroline, N-methylpyrrole, N-butyl pyrrole, N-methylimidazole, N-butylimidazole, 2,2'-bipyridine, N,N'-dimethylethane-1,2-diimine, N,N'-di(t-butyl)ethane-1,2-diimine, N,N'-di(t-butyl)butane-2,3-diimine, N,N'-diphenylethane-1,2-diimine, N,N'-bis(2,6-diisopropylphenyl)ethane-1,2-diimine, N,N'-diphenylbutane-2,3-diimine, N,N'-bis(2,6-dimethylphenyl)butane-2,3-diimine or N,N'-bis(2,6-diisopropylphenyl)butane-2,3-diimine, or - phosphine-type compounds independently selected from the following: tributylphosphine, triisopropylphosphine, tricyclopentylphosphine, tricyclohexylphosphine, triphenylphosphine, tris(o-tolyl)phosphine, bis(diphenylphosphino)ethane, trioctylphosphine oxide, triphenylphosphine oxide or triphenylphosphite, a compound corresponding to the general formula (I) or one of the tautomers of said compound:

[0059] [ka]

[0060] During the ceremony: - A and A' are the same or different and each is a single bond between an oxygen or phosphorus atom and a carbon atom; - R1a and R 1b The radicals are independently selected from: methyl, trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclohexyl or adamantyl radicals, which may be substituted or unsubstituted and may or may not contain heteroelements; phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-(n-butyl)phenyl, 2-methylphenyl, 4-methoxyphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropoxyphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-di(tert-butyl)-4-methoxyphenyl, 4-chlorophenyl, 3,5-di(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, bisphenyl, furanyl or thiophenyl radicals. - R 2 are independently selected from: methyl, trifluoromethyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclohexyl or adamantyl groups, which may be substituted or unsubstituted and may or may not contain heteroelements; phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-(n-butyl)phenyl, 4-methoxyphenyl, 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, bisnaphthyl, pyridyl, bisphenyl, furanyl or thiophenyl groups.

[0061] When the catalyst system is based on titanium, the additives are selected from diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, 2-methoxy-2-methylpropane, 2-methoxy-2-methylbutane, 2,2-dimethoxypropane, 2,2-di(2-ethylhexyloxy)propane, 2,5-dihydrofuran, tetrahydrofuran, 2-methoxytetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2,3-dihydropyran, tetrahydropyran, 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, dimethoxyethane, di(2-methoxyethyl)ether, benzofuran, glyme and diglyme, employed alone or in mixtures.

[0062] When the catalytic system is based on chromium, the additive material is chosen from: - compounds of the nitrogenous type, such as trimethylamine, triethylamine, pyrrole, 2,5-dimethylpyrrole, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-methoxypyridine, 3-methoxypyridine, 4-methoxypyridine, 2-fluoropyridine, 3-fluoropyridine, 3-trifluoromethylpyridine, 2-phenylpyridine, 3-phenylpyridine, 2-benzylpyridine, 3,5-dimethylpyridine, 2,6-di(tert-butyl)pyridine and 2,6-diphenylpyridine, quinoline, 1,10-phenanthroline, N-methylpyrrole, N-butylpyrrole, N-methylimidazole, N-butylimidazole, 2,2'-bipyridine, N,N'-dimethylethane-1,2-diimine, N,N'-di(t-butyl)ethane-1,2-diimine, N,N'-di(t-butyl)butane-2,3-diimine, N,N'-diphenylethane-1,2-diimine, N,N'-bis(2,6-dimethylphenyl)ethane-1,2-diimine, N,N'-bis(2,6-diisopropylphenyl)ethane-1,2-diimine, N,N'-diphenylbutane-2,3-diimine, N,N'-bis(2,6-dimethylphenyl)butane-2,3-diimine or N,N'-bis(2,6-diisopropylphenyl)butane-2,3-diimine, or - General formula [M(R 3 O) 2-n X n ] y Aryloxy compounds of the formula: M is selected from magnesium, calcium, strontium and barium, preferably magnesium; R 3 is an aryl group containing 6 to 30 carbon atoms, and X is a halogen or an alkyl group containing 1 to 20 carbon atoms; n is an integer that can take on the value 0 or 1, y is an integer from 1 to 10; preferably, y is equal to 1, 2, 3 or 4.

[0063] Preferably, the aryloxy group R 3 O is selected from 4-phenylphenoxy, 2-phenylphenoxy, 2,6-diphenylphenoxy, 2,4,6-triphenylphenoxy, 2,3,5,6-tetraphenylphenoxy, 2-(tert-butyl)-6-phenylphenoxy, 2,4-di(tert-butyl)-6-phenylphenoxy, 2,6-diisopropylphenoxy, 2,6-dimethylphenoxy, 2,6-di(tert-butyl)phenoxy, 4-methyl-2,6-di(tert-butyl)phenoxy, 2,6-dichloro-4-(tert-butyl)phenoxy and 2,6-dibromo-4-(tert-butyl)phenoxy. Two aryloxy groups may be carried by one and the same molecule, for example biphenoxy group, binaphthoxy or 1,8-naphthalenedioxy. Preferably, the aryloxy group R 3 O is 2,6-diphenylphenoxy, 2-(tert-butyl)-6-phenylphenoxy or 2,4-di(tert-butyl)-6-phenylphenoxy.

[0064] (solvent) In another embodiment according to the present invention, the catalyst system optionally comprises one or more solvents.

[0065] The solvent is selected from the group formed by aliphatic and cycloaliphatic hydrocarbons, for example hexane, cyclohexane, heptane, butane or isobutane.

[0066] Preferably, the solvent used is cyclohexane.

[0067] In one embodiment, a solvent or a mixture of solvents may be used during the oligomerization reaction, said solvents being advantageously independently selected from the group formed by aliphatic and cycloaliphatic hydrocarbons, such as hexane, cyclohexane, heptane, butane or isobutane.

[0068] Preferably, the linear alpha-olefin obtained comprises from 4 to 20 carbon atoms, preferably from 4 to 18 carbon atoms, preferably from 4 to 10 carbon atoms, preferably from 4 to 8 carbon atoms. Preferably, the olefin is a linear alpha-olefin selected from but-1-ene, hex-1-ene or oct-1-ene.

[0069] Advantageously, the oligomerization process is carried out at a pressure between 0.1 and 10.0 MPa, preferably between 0.2 and 9.0 MPa and preferentially between 0.3 and 8.0 MPa, and at a temperature between 30 and 200°C, preferably between 35 and 150°C and preferentially between 45 and 140°C.

[0070] The concentration of the catalyst in the catalyst system is preferably 0.1 to 50.0 ppm in terms of mass of atomic metal relative to the reaction mass, preferably 0.4 to 30.0 ppm in terms of mass of atomic metal relative to the reaction mass, preferably 0.6 to 20.0 ppm in terms of mass of atomic metal relative to the reaction mass, preferably 0.8 to 10.0 ppm in terms of mass of atomic metal relative to the reaction mass, and preferably 1.0 to 6.0 ppm in terms of mass of atomic metal relative to the reaction mass.

[0071] According to one embodiment, the oligomerization process is carried out batchwise. The catalytic system constituted as above is introduced into a reactor equipped with conventional stirring, heating and cooling devices, then pressurization with ethylene is carried out to the desired pressure and the temperature is adjusted to the desired value. The oligomerization device is maintained at a constant pressure by introducing gaseous ethylene until the total volume of the resulting liquid is, for example, 2 to 50 times the volume of the catalytic solution previously introduced. The catalyst is then destroyed by any conventional means known to those skilled in the art, and the products of the reaction and the solvent are then drawn off and separated.

[0072] According to another embodiment, the oligomerization process is carried out continuously. The catalytic system constituted as described above is injected simultaneously with ethylene into a stirred reactor by conventional mechanical means or external recirculation known to those skilled in the art and maintained at the desired temperature. The components of the catalytic system can also be injected separately into the reaction medium. Gaseous ethylene is introduced by an intake valve depending on the pressure, which keeps the pressure constant in the reactor. The reaction mixture is withdrawn by a valve depending on the liquid level, which keeps the reaction mixture constant. The catalyst is continuously destroyed by any usual means known to those skilled in the art, and then the products originating from the reaction, and also the solvent, are separated, for example by distillation. The unconverted ethylene can be recycled into the reactor. The catalyst residues contained in the heavy fraction can be incinerated.

[0073] (Step a) of Introducing the Catalytic System) The process according to the invention comprises a step a) of introducing a catalytic system comprising a metal catalyst and an activator, optionally a solvent or a mixture of solvents, into a reaction chamber comprising a liquid phase in a lower zone and a gas phase in an upper zone.

[0074] Preferably, the catalyst system is introduced into the liquid phase in the lower part of the reaction chamber, preferably at the bottom of the reaction chamber.

[0075] Preferably, the pressure for introduction into the reaction chamber is between 0.1 and 10.0 MPa, preferably between 0.2 and 9.0 MPa, preferentially between 0.3 and 8.0 MPa.

[0076] Preferably, the temperature for introduction into the reaction chamber is between 30 and 200°C, preferably between 35°C and 150°C, preferentially between 45°C and 140°C.

[0077] (Step b) of contacting with gaseous ethylene) The process according to the invention comprises a step b) of contacting the catalytic system introduced in step a) with gaseous ethylene, said gaseous ethylene being introduced in liquid phase at the bottom of the reaction chamber, preferably on a lower side of the reaction chamber. The introduced gaseous ethylene comprises fresh gaseous ethylene, preferably said fresh gaseous ethylene being combined with gaseous ethylene recycled in a separation step after the oligomerization process.

[0078] In carrying out the process according to the invention, after the step of introducing gaseous ethylene, the liquid phase comprises undissolved gaseous ethylene and therefore according to the zone of the reaction chamber the liquid phase corresponds in particular to a gas-liquid mixture between the liquid phase and the gaseous ethylene. Preferably, the zone at the bottom of the reaction chamber below the level at which the gaseous ethylene is introduced comprises a liquid phase free of gaseous ethylene.

[0079] Preferably, the gaseous ethylene is distributed by means capable of effecting said distribution homogeneously over the entire cross section of the reactor, by dispersion during its introduction into the liquid phase in the lower part of the reaction chamber. Preferably, the distribution means is chosen from a distribution plate network having a uniform distribution of ethylene injection points over the entire cross section of the reactor.

[0080] Preferably, the velocity of the gaseous ethylene at the outlet of the orifice is between 1.0 and 30.0 m / s. Its superficial velocity (volumetric gas velocity divided by the cross section of the reaction chamber) is between 0.5 and 10.0 cm / s, preferably between 1.0 and 8.0 cm / s.

[0081] Preferably, gaseous ethylene is introduced at a flow rate of 1 to 250 t / h, preferably 3 to 200 t / h, preferably 5 to 150 t / h, preferably 10 to 100 t / h.

[0082] Preferably, the flow rate of the gaseous ethylene introduced in step b) depends on the pressure in the reaction chamber.

[0083] According to a particular embodiment of the invention, a flow of gaseous hydrogen may also be introduced into the reaction chamber, the flow rate representing 0.2% to 1.0% by weight of the flow rate of the incoming ethylene. Preferably, the flow of gaseous hydrogen is introduced by the pipe employed for the introduction of gaseous ethylene.

[0084] (Step c) of withdrawing the liquid phase fraction) The process according to the invention comprises a step c) of withdrawing a fraction of the liquid phase, preferably at the bottom of the reaction chamber, which is carried out by any means making it possible to effect withdrawal, preferably by means of a pump.

[0085] The withdrawal carried out in step c) is preferably carried out in the lower part of the reaction chamber, preferably below the level of injection of gaseous ethylene, preferably at the bottom of the chamber. The withdrawal is carried out by any means capable of carrying out the withdrawal, preferably by a pump. The withdrawal flow rate is preferably 500 to 10,000 t / h, more preferably 800 to 7,000 t / h.

[0086] In one embodiment, a second stream is withdrawn from the liquid phase, said second stream corresponding to the effluent obtained at the end of the oligomerization process and may be sent to a separation section placed downstream of the device employed in the process according to the invention.

[0087] According to a preferred embodiment, the liquid fraction withdrawn from the liquid phase is split into two streams: the first, main stream is sent to the cooling step d) and the second stream corresponds to the effluent and is sent to the downstream separation section.

[0088] Advantageously, the flow rate of said second stream is regulated to maintain a constant liquid level in the reactor. Preferably, the flow rate of said second stream is 5 to 200 times lower than the liquid flow rate sent to the cooling step. Preferably, the flow rate of said effluent is 5 to 150 times lower, preferably 10 to 120 times lower, preferentially 20 to 100 times lower.

[0089] (Step d) of cooling the liquid fraction) The process according to the invention comprises a step d) of cooling the liquid fraction withdrawn in step c).

[0090] Preferably, the cooling step is carried out by passing the main liquid stream withdrawn in step c) through one or more heat exchangers placed inside or outside, preferably outside, the reaction chamber.

[0091] The heat exchanger allows a reduction in the temperature of the liquid phase of 1.0-30.0° C., preferably 2.0-20° C., preferably 2.0-15.0° C., preferably 2.5-10.0° C., preferably 3.0-9.0° C., preferably 4.0-8.0° C. Advantageously, cooling of the liquid fraction allows maintaining the temperature of the reaction medium within the desired temperature range.

[0092] Advantageously, the step of cooling the liquid through a recirculation loop also makes it possible to provide agitation of the reaction medium and therefore homogenization of the concentration of the reactants throughout the liquid volume of the reaction chamber.

[0093] (Step e) of introducing the cooled liquid fraction) The process according to the invention comprises a step e) of introducing the liquid fraction cooled in step d).

[0094] The introduction of the cooled liquid fraction resulting from step d) is carried out in the gaseous part of the reaction chamber, preferably at the top of said chamber, by any means known to those skilled in the art.

[0095] Preferably, the flow rate for the introduction of the cooled liquid fraction is between 500 and 10,000 t / h, preferably between 800 and 7000 t / h.

[0096] Steps c) to e) now constitute a redistribution loop, which advantageously allows stirring of the reaction medium and therefore homogenization of the reactant concentrations throughout the liquid volume of the reaction chamber.

[0097] (Step f) of recycling the gaseous fraction extracted from the gas phase) The process according to the invention comprises a step f) of recycling the gaseous fraction withdrawn from the gas phase in the reaction chamber and introduced at the lower part of the reaction chamber to the liquid phase, preferably at the lower lateral part of the reaction chamber, preferably at the bottom of the reaction chamber, where lower part means the lower quadrant of the reaction chamber.

[0098] Step f) of recycling the gaseous fraction is also called the recycle loop. The withdrawal of the gaseous fraction carried out in step f) is carried out by any means suitable for carrying out the withdrawal, preferably by means of a compressor.

[0099] One advantage of the recycling step according to the invention is that it compensates for the phenomenon of breakthrough of ethylene into the headspace. The phenomenon of breakthrough corresponds to gaseous ethylene crossing the liquid phase passing into the headspace without dissolving. If the flow rate of injected gaseous ethylene and the volume of the headspace are fixed at a given value, the breakthrough leads to an increase in the pressure in the reaction chamber. In the gas / liquid reactor employed according to the preferred method, the flow rate of the introduction of ethylene in step b) depends on the pressure in the reaction chamber. Thus, in the case of an increase in the pressure in the reactor due to a high level of breakthrough of ethylene into the gas phase, the flow rate of gaseous ethylene introduced in step b) is reduced, thus resulting in a decrease in the amount of ethylene dissolved in the liquid phase and therefore in a decrease in saturation. A decrease in saturation is detrimental to the conversion of ethylene and is accompanied by a decrease in the productivity of the reactor. The step of recycling the gaseous fraction according to the invention therefore makes it possible to optimize the saturation of the dissolved ethylene and therefore to improve the volumetric productivity of the process.

[0100] The gas phase withdrawn in step f) may be introduced into the reaction chamber alone or in admixture with the gaseous ethylene introduced in step b), preferably the gas phase is introduced in admixture with the gaseous ethylene introduced in step b).

[0101] In one particular embodiment, the gas phase withdrawn in step f) is introduced into the reaction chamber by being dispersed in the lower liquid phase of the reaction chamber by means capable of effecting said dispersion homogeneously over the entire cross section of the reactor, preferably the dispersion means being chosen from a network of distributor plates having a uniform distribution of the points of injection of the gas phase withdrawn in step f) over the entire cross section of the reactor.

[0102] Preferably, the velocity of the gas fraction extracted at the outlet of the orifice is between 1.0 and 30.0 m / s. Its superficial velocity (volumetric gas velocity divided by the cross section of the reaction chamber) is between 0.5 and 10.0 cm / s, preferably between 1.0 and 8.0 cm / s.

[0103] Preferably, the withdrawal rate of the fraction is between 0.1 and 100%, preferably between 0.5 and 90.0%, preferably between 1.0 and 80.0%, preferably between 2.0 and 70.0%, preferably between 4.0 and 60.0%, preferably between 5.0 and 50.0%, preferably between 10.0 and 40.0%, preferentially between 15.0 and 30.0% of the flow rate of gaseous ethylene introduced in step b).

[0104] Advantageously, the withdrawal rate of the gas fraction in step f) depends on the pressure in the reaction chamber, making it possible to maintain the pressure at a desired value or range and to compensate for the phenomenon of breakthrough of gaseous ethylene into the headspace.

[0105] In one particular embodiment, the gas fraction withdrawn in step f) is split into two streams: a first main gas stream that is recycled directly to the reaction chamber, and a second gas stream.

[0106] In one preferred embodiment, said second gas flow corresponds to a purging of the headspace and makes it possible to remove a portion of the non-condensable gases.

[0107] Preferably, the flow rate of the second gas stream is between 0.005 and 1.00%, preferably between 0.01 and 0.50%, of the flow rate of the ethylene introduced in step b).

[0108] (Oligomerization reaction device) Many reactors employing liquid and gas phases consist of a reaction chamber containing a liquid phase in a lower zone containing gaseous ethylene and a gas phase in an upper zone, and a loop for recirculating the liquid fraction through a heat exchanger, which allows it to be cooled before being reinjected into the main chamber. The flow rate in the recirculation loop allows an effective homogenization of the concentrations in the reaction chamber and control of the temperature in the liquid phase.

[0109] The reaction device employed by the method according to the invention belongs to the field of gas / liquid reactors, for example bubble columns. More specifically, the reaction device according to the invention comprises the following elements: i) a reaction chamber of elongated shape along a vertical axis, a liquid phase located in the lower zone, comprising, and preferably consisting of, the products of the reaction, dissolved gaseous ethylene, the catalyst system and optional solvent; and A gas phase located in an upper zone above the lower zone and containing gaseous ethylene and also non-condensable gases (especially ethane) a reaction chamber i) comprising - ii) means for introducing gaseous ethylene, said means being placed at the lower side of said reaction chamber and employing means for distributing gaseous ethylene within said liquid phase of said reaction chamber; - iii) a means for introducing a catalytic system, said catalytic system comprising one metal catalyst, at least one activating substance and at least one additive substance, said means being placed in the lower part of the reaction chamber, - a recirculation loop iv) comprising withdrawal means at the base (preferably at the bottom) of the reaction chamber for withdrawing a liquid fraction towards a heat exchanger enabling said liquid to be cooled, and means for introducing said cooled liquid, said introduction taking place into the liquid phase in the upper part of the lower zone of the reaction chamber, v) a recycle loop for the gas phase to the lower zone of the liquid phase, said recycle loop comprising means for withdrawing the gaseous fraction in the gas phase of the reaction chamber and means for introducing said withdrawn gaseous fraction into the liquid phase in the lower zone of the reaction chamber.

[0110] (i) Reaction chamber According to the invention, any reaction chamber known to the person skilled in the art and capable of carrying out the method according to the invention can be envisaged. Preferably, the reaction chamber is cylindrical in shape and has a height to width ratio (denoted H / W) of 1 to 17, preferably 1 to 8, preferably 2 to 7 and preferentially 2 to 4.

[0111] Preferably, the reaction chamber includes means for purging non-condensable gases in the vapor phase.

[0112] Preferably, the reaction chamber also comprises a pressure sensor, which makes it possible to control and preferably keep constant the pressure in the reaction chamber. Preferably, in case of a drop in pressure, said pressure is kept constant by the introduction of gaseous ethylene into the reaction chamber.

[0113] According to the invention, in the event of a breakthrough of ethylene into the gas phase, said pressure is kept constant by implementing a recycle loop v), which will be described below.

[0114] The headspace recycle loop therefore advantageously makes it possible, in the event of ethylene breakthrough, to maintain the saturation of dissolved ethylene in the liquid phase of the lower zone at a given value.

[0115] Preferably, the reaction chamber also comprises a liquid level sensor; said level is kept constant by adjusting the flow rate of the effluent withdrawn in step c). Preferably, the level sensor is located at the interface between the liquid phase and the headspace.

[0116] (ii) Means for introducing ethylene According to the invention, the reaction chamber i) comprises means for the introduction of gaseous ethylene placed in the lower part of said chamber, more particularly in the lower lateral part.

[0117] Preferably, the means ii) for the introduction of ethylene is selected from a pipe, a network of pipes, a multi-tubular distribution plate, a perforated plate or any other means known to a person skilled in the art.

[0118] In a particular embodiment, means for the introduction of ethylene are placed in the redistribution loop iv).

[0119] Preferably, a gas distribution plate is placed at the end of the introduction means ii) in the reaction chamber i). This gas distribution plate is a device that allows the gas phase to be distributed homogeneously over the entire liquid cross section. Said device comprises a network of perforated pipes. The diameter of the orifices of the perforated pipes is 1.0-12.0 mm, preferably 3.0-10.0 mm, so as to form millimeter-sized ethylene bubbles in the liquid.

[0120] (iii) Means for introducing the catalytic system According to the invention, the reaction chamber i) comprises means iii) for introducing a catalytic system.

[0121] Preferably, the introduction means iii) is located on the lower part of the reaction chamber, preferably at the bottom of said chamber.

[0122] According to an alternative embodiment, the catalyst system is introduced into the redistribution loop.

[0123] The means iii) for introducing the catalyst system is selected from any means known to the person skilled in the art, preferably a pipe.

[0124] In embodiments in which the catalytic system is employed in the presence of a solvent or mixture of solvents, said solvent is introduced into the lower part of the reaction chamber, preferably at the bottom of the reaction chamber, or else by an introduction means located in the recirculation loop.

[0125] (iv) Redistribution Loops According to the invention, the liquid phase is homogenized and the temperature in the reaction chamber is also regulated by the use of a recirculation loop, which comprises means for withdrawing a liquid fraction above the lower part of the reaction chamber, preferably at the bottom, towards one or more heat exchangers, thus allowing said liquid to be cooled, and means for introducing said cooled liquid into the liquid phase in the upper part of the reaction chamber.

[0126] The recirculation loop may advantageously be implemented by any necessary means known to the person skilled in the art, such as a pump for the withdrawal of the liquid fraction, means making it possible to regulate the flow rate of the withdrawn liquid fraction, or else a pipe for purging at least a part of the liquid fraction.

[0127] Preferably, the means for withdrawing the liquid fraction from the reaction chamber is a pipe.

[0128] The heat exchanger(s) capable of cooling the liquid fraction may be selected from any means known to those skilled in the art.

[0129] The recirculation loop allows for an effective homogenization of the concentration and makes it possible to control the temperature in the liquid phase within the reaction chamber.

[0130] (v) Headspace recycle loop According to the invention, the device comprises a loop for recycling the gas phase to the lower part of the liquid phase, said loop comprising means for withdrawing the gaseous fraction in the gas phase of the reaction chamber and means for introducing said withdrawn gaseous fraction into the liquid phase in the lower part of the reaction chamber.

[0131] The recycle loop advantageously makes it possible to compensate for the phenomenon of breakthrough and to prevent the pressure in the reaction chamber from increasing, while maintaining the saturation of dissolved ethylene in the liquid phase at the desired level.

[0132] Another advantage of the recycle loop is that it improves the volumetric productivity of the device and therefore reduces costs.In one preferred embodiment, the recycle loop further comprises a compressor.

[0133] In one embodiment, the withdrawn gaseous fraction is introduced by means ii) for introducing gaseous ethylene.

[0134] In another embodiment, the extracted gaseous fraction is introduced via a gas distribution plate, a device that allows homogeneous distribution of the gas phase over the entire liquid cross section and that is placed at the end of the introduction means in the reaction chamber i). Said device comprises a network of perforated plates, the diameter of the orifices of which is between 1.0 and 12.0 mm, preferably between 3.0 and 10.0 mm, so as to form millimeter-sized ethylene bubbles in the liquid.

[0135] Preferably, the means for introducing the withdrawn gaseous fraction is selected from a pipe, a network of pipes, a multi-tubular distributor plate, a perforated plate or any other means known to a person skilled in the art.

[0136] Description of the drawings [FIG. 1] FIG. 1 shows a reaction device according to the prior art. This device consists of a reaction chamber (1) containing a lower zone containing a liquid phase A and an upper zone containing a gas phase B, and means (2) for introducing gaseous ethylene into the liquid phase A via a gas distribution plate (3). The gas phase B contains pumping means (4). At the bottom of the reaction chamber (1) there is a pipe placed to withdraw the liquid fraction (5). Said fraction (5) is split into two streams: a first main stream (7) and a second stream (6), the first main stream (7) being sent to a heat exchanger (8) and then introduced into the liquid phase A via a pipe (9), and the second stream (6) corresponding to the effluent sent to the subsequent step. A pipe (10) at the bottom of the reaction chamber allows the introduction of a catalyst system.

[0137] [Figure 2] Figure 2 shows a device making it possible to carry out the process according to the invention. Said device differs from that of Figure 1 in that the gas fraction of the gas phase B is sent to a compressor (11) and recycled through a pipe (12) connected to a means (2) for introducing gaseous ethylene into the lower part of zone A containing the liquid phase A.

[0138] FIG. 2 provides a schematic diagram of one particular embodiment of the inventive subject matter, but is not intended to limit the scope of the invention.

[0139] (Example) The following examples illustrate the present invention but do not limit the scope of the invention.

[0140] (Example 1: Comparative Example Corresponding to FIG. 1) The ethylene oligomerization process is carried out in a bubble column reactor. The reactor is operated at a pressure of 5.0 MPa and a temperature of 120° C. The reaction volume is, according to the drawing 1, two zones A and B, a column with a diameter of 2.97 m, a liquid height of 6.0 m, and a total volume of 5.0 m. 3 It consists of a redistribution loop.

[0141] The column is equipped with a device for injecting gaseous ethylene located 1.0 m from the bottom of the column.

[0142] The catalytic system introduced into the reaction chamber is a chromium-based catalytic system having a chromium content of 4.37 ppm, in the presence of cyclohexane as solvent, as described in patent FR 3 019 064.

[0143] The purge flow rate is 0.0045 kg / s.

[0144] The volumetric productivity of this reactor is calculated per unit time and reaction volume (m 3 ) 0.134 tonnes of hex-1-ene is produced.

[0145] This reactor performance level allows for 62.0% saturation of dissolved ethylene.

[0146] The production of hex-1-ene is 6.25 tonnes / h, the selectivity for hex-1-ene is 81.2% by weight and the residence time in the reactor is 76 minutes for a solvent mass fraction of 1.0, calculated as the ratio by mass of the flow rate of injected solvent to the flow rate of injected gaseous ethylene.

[0147] (Example 2: corresponds to the invention corresponding to FIG. 2) An oligomerization process in accordance with the invention is carried out in a device having the same dimensions as the device employed in Example 1, and further comprising a loop for recycling the headspace to the liquid phase according to the invention as described in Figure 2. The ethylene oligomerization process is carried out in a bubble column reactor. The reactor is operated at a pressure of 5.0 MPa and a temperature of 120°C.

[0148] The catalytic system introduced into the reaction chamber is a chromium-based catalytic system, as described in patent FR 3 019 064, having a chromium content of 4.38 ppm in the presence of cyclohexane as solvent.

[0149] The volumetric productivity of this reactor is calculated per unit time and reaction volume (m 3 ) 0.194 tonnes of hex-1-ene produced.

[0150] The performance level of the oligomerization process according to the invention allows for 90.0% saturation of dissolved ethylene.

[0151] The production of hex-1-ene is 9.06 tonnes / h, the selectivity for hex-1-ene is 83.3% by weight and the residence time in the reactor is 52.5 minutes for a solvent mass fraction of 1.0, calculated as the ratio by mass of the flow rate of injected solvent to the flow rate of injected gaseous ethylene.

[0152] The process according to the invention therefore clearly makes it possible to increase the ethylene saturation in the liquid phase, which allows an improvement in the productivity of the oligomerization process due to shorter residence times and better selectivity for hex-1-ene. [Brief description of the drawings]

[0153] [Figure 1] 1 shows a reaction device according to the prior art; [Diagram 2] 1 shows a device allowing the implementation of the method according to the invention;

Claims

1. 1. An oligomerization process carried out in a gas / liquid reactor at a pressure of 0.1-10.0 MPa and a temperature of 30-200° C., comprising the following steps: a) introducing an oligomerization catalyst system comprising a metal catalyst and an activator into a reaction chamber comprising a liquid phase in a lower zone and a gas phase in an upper zone; b) contacting said catalyst system with gaseous ethylene by introducing said ethylene into a lower zone of a reaction chamber; c) withdrawing the liquid fraction; d) cooling the liquid fraction withdrawn in step c) by passing said fraction through a heat exchanger; e) introducing the cooled fraction from step d) into an upper portion of the lower zone of the reaction chamber; f) recycling the gaseous fraction withdrawn from the upper zone of the reaction chamber and introduced into the lower zone of the reaction chamber into the liquid fraction. A method comprising:

2. 10. The process of claim 1, wherein the liquid phase in the lower zone of the reaction chamber has a saturation of ethylene in the liquid phase of greater than 70.0%.

3. 3. The process according to claim 1 or 2, wherein the gas phase withdrawn in step f) is introduced in a mixture with the gaseous ethylene introduced in step b).

4. 4. The process according to claim 1, wherein the gaseous fraction extracted in step f) is introduced into a lower lateral part of the reaction chamber.

5. The method according to any one of claims 1 to 4, wherein the withdrawal rate of the gaseous fraction in step f) depends on the pressure in the reaction chamber.

6. 6. The method according to claim 1, wherein a flow of gaseous hydrogen is introduced into the reaction chamber in step b) at a flow rate representing 0.2 to 1.0% by weight of the flow rate of the introduced ethylene.

7. The process of any one of claims 1 to 6, wherein the concentration of catalyst in the catalytic system is from 0.1 to 50.0 ppm by mass of atomic metal relative to the reaction mass.

8. The process according to any one of claims 1 to 7, wherein the catalytic oligomerization reaction is carried out continuously.

9. The process according to any one of claims 1 to 8, wherein the linear olefin obtained contains from 4 to 20 carbon atoms.

10. A reaction device for carrying out the method according to any one of claims 1 to 9, comprising: a reaction chamber i) of elongated shape along a vertical axis, a liquid phase located in the lower zone and containing the reaction products, gaseous and dissolved ethylene, the catalyst system and optionally a solvent; and a gas phase containing gaseous ethylene and also non-condensable gases, located in an upper zone above the lower zone; a reaction chamber i) - ii) means for introducing gaseous ethylene, said means being placed at the bottom side of said reaction chamber and employing means for distributing gaseous ethylene in said liquid phase of said reaction chamber; - iii) a means for introducing a catalytic system, said catalytic system comprising one metal catalyst, at least one activating substance and at least one additive substance, said means being placed in the lower part of the reaction chamber, a recirculation loop iv) comprising withdrawal means at the base of the reaction chamber for withdrawing a liquid fraction towards a heat exchanger enabling said liquid to be cooled, and means for introducing said cooled liquid, said introduction taking place into the liquid phase in the upper part of the lower zone of the reaction chamber; v) a recycle loop for the gas phase to the lower zone of the liquid phase, comprising means for withdrawing the gaseous fraction in the gas phase of the reaction chamber and means for introducing said withdrawn gaseous fraction into the liquid phase in the lower zone of the reaction chamber. A reaction device comprising:

11. 11. The device according to claim 10, wherein the withdrawn gaseous fraction is introduced via ii) a means for introducing gaseous ethylene.

12. 12. A device according to claim 10 or 11, wherein the gaseous fraction withdrawn in the recycle loop is introduced via a gas distribution plate.

Images