PROCESS FOR THE OLIGOMERIZATION OF AN OLEFINIC FEEDSTOCK IN A TUBULAR LOOP REACTOR

Abstract

The present invention relates to a process for oligomerizing an olefinic feedstock comprising the following steps: a) injection into a tubular loop reactor of at least the olefinic feedstock and a catalytic system, said olefinic feedstock being injected by an injection means placed at a position A of the reactor, and formation of a liquid phase flowing continuously in the reactor; b) withdrawal of the products of the oligomerization reaction by a withdrawal means placed at a position B of the reactor located at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor. The present invention also relates to a tubular loop reactor for implementing the process according to the invention.

Description

Title of the invention: PROCESS FOR THE OLIGOMERIZATION OF AN OLEFINIC FEEDSTOCK IN A TUBULAR LOOP REACTOR Technical field

[0001] The present invention is in the field of the oligomerization of olefins, more particularly in the field of the oligomerization of olefins in a tubular loop reactor ("loop reactor" according to English terminology). Prior art

[0002] Processes for oligomerization of olefins, in particular ethylene, in tubular loop reactors are known from the prior art.

[0003] Loop tubular reactors are used to oligomerize olefinic compounds, such as ethylene or other short-chain olefins, to produce alpha olefins. These reactors are characterized by their loop-shaped tubular design, which allows for the continuous circulation of reactants and products. They are equipped with feed systems through which the gas phase, solvent and catalyst are introduced and maintained at the temperature and pressure conditions. A sub-draft system for withdrawing the product and a system for maintaining the flow circulation are provided, as well as a double jacket through which a cooling heat transfer fluid circulates to remove the heat from the exothermic reactions.

[0004] JP10087518 discloses a process for trimerizing ethylene to hexene-1 in a loop tubular reactor, the process of which can suppress the adhesion of by-product polymer to the surface of the reactor cooling wall, and maintain high heat removal efficiency of the reactor.

[0005] CN103896704 discloses a process for oligomerization of ethylene in a reactor Loop-tubular process. A catalyst component and a portion of the ethylene feedstock are pre-dissolved in a reaction solvent in an external container connected to the reactor, and then the solution is continuously introduced into the reactor. The other portion of the ethylene feedstock is directly introduced into the reactor filled with the reaction solvent. The process has the advantages of easy reactor pressure control and high catalyst activity.

[0006] CN104056583 discloses a control method for a tubular loop reactor in an ethylene oligomerization process. The control method allows both to adjust the flow rate of a thermal fluid in real time and to adjust the flow rate of an ethylene feedstock accordingly so as to allow the actual reaction temperature in the reactor to approach as closely as possible the defined reaction temperature, thus ensuring stable operation of the reactor.

[0007] There is a constant need to improve existing processes for the oligomerization of olefins in a tubular loop reactor.

[0008] The applicant has surprisingly demonstrated that in an olefin oligomerization process implemented in a loop tubular reactor, when the reaction products are withdrawn at a position as far as possible from the injection position of the olefinic feedstock in the direction of flow of the liquid phase within the reactor, significant gains are obtained in conversion of the olefinic feedstock as well as in productivity towards the desired olefins. Summary of the invention

[0009] The present invention relates to a process for oligomerization of an olefinic feedstock, carried out at a pressure of between 0.1 and 15.0 MPa and at a temperature of between 30 and 200°C, comprising the following steps:

[0010] a) injection into a loop tubular reactor of at least the olefinic feedstock and a catalytic system, said olefinic feedstock being injected by an injection means placed at a position A of the reactor, and formation of a liquid phase flowing continuously into the reactor;

[0011] b) withdrawing the products of the oligomerization reaction by a withdrawing means placed at a position B of the reactor situated at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0012] The present invention also relates to a tubular loop reactor capable of containing a liquid phase, comprising: - a means for injecting an olefinic feedstock placed at a position A of the reactor, - a means for withdrawing the products placed at a position B of the reactor located at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor. DETAILED DESCRIPTION OF THE INVENTION

[0013] According to the present invention, the expression "between ... and ..." and "between .... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this is not the case and the limit values ​​are not included in the range described, such precision will be provided by the present invention.

[0014] In the sense of the present invention, the different parameter ranges for a given step such as the pressure ranges and the temperature ranges can be used alone or in combination. For example, within the meaning of the present invention, a preferred pressure range may be combined with a more preferred temperature range.

[0015] In the following, particular embodiments of the invention may be described. They may be implemented separately or combined with each other, without limitation of combinations when this is technically feasible.

[0016] Oligomerization process

[0017] Charge

[0018] The feedstock used in the process according to the invention is an olefinic feedstock, i.e. a feedstock having an olefin content greater than 75% by weight, preferably greater than 85% by weight, more preferably greater than 95% by weight.

[0019] In one embodiment, the olefins present in the feedstock are olefins having between 2 and 6 carbon atoms.

[0020] Advantageously, the olefin present in the feedstock is ethylene.

[0021] The olefinic feedstock may be in liquid or gaseous form, preferably gaseous.

[0022] Advantageously, the olefinic feedstock is gaseous ethylene.

[0023] Operating conditions

[0024] In one embodiment, the oligomerization process is carried out at a pressure of between 0.2 and 14.5 MPa, preferably between 0.3 and 14.0 MPa, and at a temperature of between 35 and 180°C, preferably between 50 and 140°C.

[0025] Advantageously, the surface velocity of the liquid phase flowing in the reactor is between 1 and 20 ms', preferably between 1 and 15 ms'.

[0026] In the preferred embodiment in which the olefinic feedstock is ethylene injected in gaseous form into the reactor, the liquid phase flowing into the reactor consists either of the catalytic system, the solvent and the products of the oligomerization reaction which are created in liquid form, or of the catalytic system dissolved in a solvent and the products of the oligomerization reaction which are created in liquid form.

[0027] In one embodiment, when the feedstock is injected in gaseous form, the superficial velocity of the gaseous phase before its dissolution in the liquid phase is between 0.1 and 2 ms'.

[0028] “Superficial velocity” means the ratio between the volume flow rate of the fluid considered and the section through which the fluid passes.

[0029] In the area near the injection position of the olefinic feedstock, when the latter is injected in the form of a gas into the reactor, a gas / liquid mixture is present, and progressively when approaching the withdrawal position, the phase changes to an entirely liquid phase, because the injected gas progressively reacts / progressively dissolves in the liquid phase.

[0030] Advantageously, the oligomerization process according to the invention is operated in continuous mode, that is to say that the injections of the olefinic feedstock, of the catalytic system, optionally of a solvent are carried out continuously in the reactor, the withdrawal of the products of the oligomerization reaction are also withdrawn continuously from the reactor.

[0031] The oligomerization process according to the invention can be chosen from: - A dimerization process, for example a process for dimerizing ethylene to butene-1. - A trimerization process, for example a process for trimerizing ethylene to hexene-1. - A tetramerization process, for example a process for tetramerizing ethylene to octene-1.

[0032] Step a) of injection

[0033] The present invention comprises a step a) of injecting into a tubular loop reactor, at least the olefinic feedstock and a catalytic system, said olefinic feedstock being injected by an injection means placed at a position A of the reactor, and formation of a liquid phase flowing continuously in the reactor.

[0034] The term "position X" means the entirety of a given cross-section of the reactor tube. The means for injecting the olefinic feedstock may be of any configuration known to those skilled in the art, for example depending on the diameter of the section of the reactor tube or depending on the flow rates of feedstock injected. The injection means may be one or more single-point injectors arranged at a given position of the reactor, or a multi-point injector, the positions of the injection points being able to be located anywhere on the given cross-section, in any radial position along a radius r of the reactor tube, for example at r=0, i.e. at the center of the reactor tube, or at r=R with R the total length of a radius, i.e. at the external part of the section of the tube.It can also, for example, be annular in shape comprising multiple injection points arranged in a crown, or comprise several injectors staged over a given length of the reactor loop.

[0035] In a preferred embodiment where the feed is gaseous ethylene, the injection means comprises a gas distributor.

[0036] In one embodiment, the catalytic system is injected by an injection means placed at position A of the reactor.

[0037] In one embodiment, the catalytic system is injected by an injection means placed at a position C of the reactor different from position A and position B.

[0038] In one embodiment, step a) further comprises injecting a solvent in the tubular loop reactor.

[0039] In one embodiment, the solvent is injected by an injection means placed at position A of the reactor.

[0040] The solvent is advantageously chosen from ethers, alcohols, halogenated solvents and hydrocarbons, saturated or unsaturated, cyclic or not, aromatic or not, comprising between 1 and 20 carbon atoms, preferably between 4 and 15 carbon atoms, preferentially between 4 and 12 carbon atoms and even more preferentially between 4 and 8 carbon atoms.

[0041] Preferably, the solvent is chosen from pentane, hexane, cyclohexane, methylcyclohexane, heptane, butane or isobutane, cycloocta-1,5-diene, benzene, toluene, ortho-xylene, mesitylene, ethylbenzene, diethyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, dichloroethane, tetrachloroethane, hexachloroethane, chlorobenzene, dichlorobenzene, butene, hexene and octene, pure or as a mixture.

[0042] In one embodiment, the solvent may be chosen from the products of the oligomerization reaction.

[0043] In one embodiment, the catalytic system and the solvent are injected alone or as a mixture by one or more injection means placed at a position C of the reactor different from position A and position B.

[0044] In another embodiment, the catalytic system is injected by an injection means placed at a position C of the reactor and the solvent is injected by an injection means placed at a position D of the reactor, the position C and the position D being different from each other and different from the position A and the position B.

[0045] Catalytic system

[0046] The catalytic system used in the present invention may be a heterogeneous catalytic system such as a zeolitic material and / or a homogeneous catalytic system.

[0047] Advantageously, the catalytic system is a homogeneous catalytic system.

[0048] All homogeneous catalytic systems known to those skilled in the art and capable of being implemented in a dimerization, trimerization, tetramerization process and more generally in an oligomerization process according to the invention, are part of the field of the invention. An example of catalytic systems as well as their implementation are described in applications FR2984311, FR2552079, FR3019064, FR3023183, FR3042989 or FR3045414.

[0049] Preferably, the homogeneous catalytic system comprises, preferably consists of: - a metallic precursor preferably based on nickel, titanium or chromium, - optionally an activating agent, - optionally an additive.

[0050] The metallic precursor

[0051] The metal precursor used in the catalytic system is chosen from compounds based on nickel, titanium or chromium.

[0052] In one embodiment, the metal precursor is nickel-based and preferably comprises nickel with an oxidation state (+11). Preferably, the nickel precursor is chosen from nickel(II) carboxylates such as, for example, nickel 2-ethylhexanoate, nickel(II) phenates, nickel(II) naphthenates, nickel(II) acetate, nickel(II) trifluoroacetate, nickel(II) triflate, nickel(II) acetylacetonate, nickel(II) hexafluoroacetylacetonate, ir-allylnickel(II) chloride, ir-allylnickel(II) bromide, methal-lylnickel(II) chloride dimer, q'-allylnickel(II) hexafluorophosphate, q3-methallylnickel(II) hexafluorophosphate and nickel(II) 1,5-cyclooctadienyl, in their hydrated or non-hydrated form, taken alone or as a mixture.

[0053] In a second embodiment, the metal precursor is titanium-based and preferably comprises an aryloxy or alkoxy compound of titanium.

[0054] The titanium alkoxy compound advantageously corresponds to the general formula [Ti(OR)4 ] in which R is a linear or branched alkyl radical. Among the preferred alkoxy radicals, the following may be mentioned, by way of non-limiting example: tetraethoxy, tetraisopropoxy, tetra-n-butoxy and tetra-2-ethylhexyloxy.

[0055] The aryloxy compound of titanium advantageously corresponds to the general formula [Ti(OR')4] in which R' is an aryl radical substituted or not by alkyl or aryl groups. The radical R' may comprise heteroatom-based substituents. Preferred aryloxy radicals 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-ditertbutyl-6-phenylphenoxy, 2,6-diisopropylphenoxy, 2,6-ditert-butylphenoxy, 4-methyl-2,6-ditert-butylphenoxy, 2,6-dichloro-4-tert-butylphenoxy and 2,6-dibromo-4-tert-butylphenoxy, the biphenoxy radical, binaphthoxy, 1,8-naphthalenedioxy.

[0056] According to a third embodiment, the metal precursor is based on chromium and preferably comprises a chromium (II) salt, a chromium (III) salt, or a salt with a different oxidation state which may comprise one or more identical or different anions, such as, for example, halides, carboxylates, acetyla-ketonates, alkoxy or aryloxy anions. Preferably, the chromium-based precursor is chosen from CrCl3, CrCl3(tetrahydrofuran)3, Cr(acetylacetonate)3, Cr(naphthenate)3, Cr(2-ethylhexanoate)3, Cr(acetate)3.

[0057] The concentration of nickel, titanium or chromium is advantageously between 0.001 and 300.0 ppm by mass of atomic metal relative to the reaction mass, preferably between 0.002 and 100.0 ppm, preferentially between 0.003 and 50.0 ppm, more preferentially between 0.05 and 20.0 ppm and even more preferentially between 0.1 and 10.0 ppm by mass of atomic metal relative to the reaction liquid mass, i.e. the mass of liquid phase contained in the reactor.

[0058] The activating agent

[0059] Optionally, regardless of the metal precursor, the catalytic system comprises one or more activating agents chosen from aluminum-based compounds such as methylaluminum dichloride (MeAlCl2), dichloroethylaluminum (EtAlCl2), ethylaluminum sesquichloride (Et3Al2Cl3), chlorodiethylaluminum (Et2AlCl), chlorodiisobutylaluminum (i-Bu2AlCl), triethylaluminum (AlEt3), tripropylaluminum (Al(n-Pr)3), triisobutylaluminum (Al(i-Bu)3), diethyl-ethoxyaluminum (Et2A10Et), methylaluminoxane (MAO), ethylaluminoxane and modified methylaluminoxanes (MMAO).

[0060] The additive

[0061] Optionally, the catalytic system comprises one or more additives.

[0062] The additive is chosen from monodentate phosphorus compounds, bidentate phosphorus compounds, tridentate phosphorus compounds, olefinic compounds, aromatic compounds, nitrogen compounds, bipyridines, diimines, monodentate ethers, bidentate ethers, monodentate thioethers, bidentate thioethers, monodentate or bidentate carbenes, mixed ligands such as phosphinopyridines, iminopyridines, bis(imino)pyridines

[0063] When the metal precursor of the catalytic system is nickel-based, the additive is chosen from,

[0064] - nitrogen-type compounds, 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-trifluromethylpyridine, 2-phenylpyridine, 3-phenylpyridine, 2-benzylpyridine, 3,5-dimethylpyridine, 2,6-diterbutylpyridine and 2,6-diphenylpyridine, quinoline, 1,10-phenanthroline, N-methylpyrrole, N-butylpyrrole N-methylimidazole, N-butylimidazole, 2,2'-bipyridine, N,N'-dimethyl-ethane-1,2-diimine, N,N'-di-t-butyl-ethane-1,2-diimine, N,N'-di-t-butyl-butane-2,3-diimine, N,N'-diphenyl-ethane-1,2-diimine, N,N'-bis-(dimethyl-2,6-phenyl)-ethane-1,2-diimine, N,N'-bis-(diisopropyl-2,6-phenyl)-ethane-1,2-diimine, N,N'-diphenyl-butane-2,3-diimine, N,N'-bis-(dimethyl-2,6-phenyl)-butane-2,3-diimine, N,N'-bis-(diisopropyl-2,6-phenyl)-butane-2,3-diimine, or

[0065] - phosphine type compounds chosen independently from tributyl- phosphine, triisopropylphosphine, tricyclopentylphosphine, tricyclohexylphosphine, triphenylphosphine, tris(o-tolyl)phosphine, bis(diphenylphosphino)ethane, trioctylphosphine oxide, triphenylphosphine oxide, triphenylphosphite, or

[0066] - compounds corresponding to the general formula (I) or one of the tautomers of said compound :

[0067] [Chem.l]

[0068] in which

[0069] - A and A', identical or different, are independently an oxygen or a bond simple between the phosphorus atom and a carbon atom,

[0070] - the groups Rla and Rlb are independently chosen from the groups methyl, trifluoromethyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, pentyl, cyclohexyl, adamantyl, substituted or not, containing or not hetero-elements; phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 2-methylphenyl, 4-methoxyphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropoxyphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-ditert-butyl-4-methoxyphenyl, 4-chlorophenyl, 3,5-di(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, bisphenyl, furanyl, thiophenyl,

[0071] - the R2 group is independently chosen from methyl, tri fluoromethyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, pentyl, cyclohexyl, adamantyl, substituted or not, containing heteroelements or not; the phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, 3,5-dimethylphenyl, 4-n-butylphenyl, 4-methoxyphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-isopropoxyphenyl, 4-methoxy-3,5-dimethylphenyl, 3,5-ditert-butyl-4-methoxyphenyl, 4-chlorophenyl, 3,5-bis(trifluoromethyl)phenyl, benzyl, naphthyl, bisnaphthyl, pyridyl, bisphenyl, furanyl, thiophenyl groups.

[0072] When the metal precursor of the catalytic system is titanium-based, the additive is chosen from diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, 2-methoxy-2-methylpropane, 2-methoxy-2-methylbutane, dimethoxy- 2,2-propane, di(2-ethylhexyloxy)-2,2-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 taken alone or in mixture.

[0073] When the metal precursor of the catalytic system is based on chromium, the additive is chosen from,

[0074] - nitrogen-type compounds, 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-trifluromethylpyridine, 2-phenylpyridine, 3-phenylpyridine, 2-benzylpyridine, 3,5-dimethylpyridine, 2,6-diterbutylpyridine and 2,6-diphenylpyridine, quinoline, 1,10-phenanthroline, N-methylpyrrole, N-butylpyrrole N-methylimidazole, N-butylimidazole, 2,2'-bipyridine, N,N'-dimethyl-ethane-1,2-diimine, N,N'-di-t-butyl-ethane-1,2-diimine, N,N'-di-t-butyl-butane-2,3-diimine, N,N'-diphenyl-ethane-1,2-diimine, N,N'-bis-(dimethyl-2,6-phenyl)-ethane-1,2-diimine, N,N'-bis-(diisopropyl-2,6-phenyl)-ethane-1,2-diimine, N,N'-diphenyl-butane-2,3-diimine, N,N'-bis-(dimethyl-2,6-phenyl)-butane-2,3-diimine, N,N'-bis-(diisopropyl-2,6-phenyl)-butane-2,3-diimine, or

[0075] - aryloxy compounds of general formula [M(R3O)2nXn]y in which

[0076] * M is chosen from magnesium, calcium, strontium and barium, preferably magnesium,

[0077] * R3 is an aryl radical containing from 6 to 30 carbon atoms, X is a halogen or an alkyl radical containing from 1 to 20 carbon atoms,

[0078] * n is an integer that can take the values ​​of 0 or 1, and

[0079] * y is an integer between 1 and 10, preferably y is equal to 1, 2, 3 or 4.

[0080] Preferably, the aryloxy radical R3O is chosen from 4-phenylphenoxy, 2-phenylphenoxy, 2,6-diphenylphenoxy, 2,4,6-triphenylphenoxy, 2,3,5,6-tetraphenylphenoxy, 2-tert-butyl-6-phenylphenoxy, 2,4-ditertbutyl-6-phenylphenoxy, 2,6-diisopropylphenoxy, 2,6-dimethylphenoxy, 2,6-ditert-butylphenoxy, 4-methyl-2,6-ditert-butylphenoxy, 2,6-dichloro-4-tert-butylphenoxy and 2,6-dibromo-4-tert-butylphenoxy. The two aryloxy radicals can be carried by the same molecule, such as the biphenoxy radical, binaphthoxy or 1,8-naphthalenedioxy. Preferably, the aryloxy radical R3O is 2,6-diphenylphenoxy, 2-tert-butyl-6-phenylphenoxy or 2,4-ditert-butyl-6-phenylphenoxy.

[0081] In one embodiment, the homogeneous catalytic system is dissolved in a solvent. The solvent is advantageously chosen from ethers, alcohols, halogenated solvents and hydrocarbons, saturated or unsaturated, cyclic or not, aromatic or not, comprising between 1 and 20 carbon atoms, preferably between 4 and 15 carbon atoms, preferentially between 4 and 12 carbon atoms and even more preferentially between 4 and 8 carbon atoms.

[0082] Preferably, the solvent is chosen from pentane, hexane, cyclohexane, methylcyclohexane, heptane, butane or isobutane, cycloocta-1,5-diene, benzene, toluene, ortho-xylene, mesitylene, ethylbenzene, diethyl ether, tetrahydrofuran, 1,4-dioxane, dichloromethane, dichloroethane, tetrachloroethane, hexachloroethane, chlorobenzene, dichlorobenzene, butene, hexene and octene, pure or as a mixture.

[0083] In one embodiment, the solvent may be chosen from the products of the oligomerization reaction.

[0084] Step b) of drawing off

[0085] The present invention comprises a step b) of withdrawing the products of the oligomerization reaction by a withdrawal means placed at a position B of the reactor situated at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0086] Advantageously, the products of the oligomerization reaction withdrawn are included in the liquid phase flowing continuously in the reactor.

[0087] The products of the oligomerization reaction may comprise butene-1 in the case of an ethylene dimerization process.

[0088] The products of the oligomerization reaction may comprise hexene-1 in the case of an ethylene trimerization process.

[0089] The products of the oligomerization reaction may comprise octene-1 in the case of an ethylene tetramerization process.

[0090] The means for withdrawing the products of the oligomerization reaction may be of any configuration known to those skilled in the art.

[0091] Advantageously, position B is located at a distance from position A of between 75.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0092] Advantageously, position B is located at a distance from position A of between 80.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0093] Advantageously, position B is located at a distance from position A of between 85.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0094] Advantageously, position B is located at a distance from position A of between 90.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0095] Advantageously, position B is located at a distance from position A of between 95.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0096] Advantageously, position B is located at a distance from position A of between 97.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

[0097] Advantageously, position B is located at a distance from position A of between 99.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor. Oligomerization reactor

[0098] The present invention also relates to a tubular loop reactor 4 capable of containing a liquid phase, comprising: - a means for injecting an olefinic feedstock 1 placed at a position A of the reactor, - a means for withdrawing the products 3 placed at a position B of the reactor located at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0099] In one embodiment, the loop tubular reactor 4 further comprises a means for injecting a catalytic system 2 and optionally a solvent placed at a position C of the reactor 4 different from position A and position B.

[0100] In one embodiment, the loop tubular reactor further comprises a means for injecting a catalytic system 2 placed at a position C of the reactor, and a means for injecting a solvent 2' placed at a position D of the reactor, the position C and the position D being different from each other, and different from the position A and the position B.

[0101] Advantageously, position B is located at a distance from position A of between 75.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0102] Advantageously, position B is located at a distance from position A of between 80.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0103] Advantageously, position B is located at a distance from position A of between 85.00 and 99.99% of the total length of the loop of said reactor 4 in the direction flow 6 of the liquid phase within said reactor 4.

[0104] Advantageously, position B is located at a distance from position A of between 90.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0105] Advantageously, position B is located at a distance from position A of between 95.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0106] Advantageously, position B is located at a distance from position A of between 97.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0107] Advantageously, position B is located at a distance from position A of between 99.00 and 99.99% of the total length of the loop of said reactor 4 in the direction of flow 6 of the liquid phase within said reactor 4.

[0108] Advantageously, the reactor according to the invention further comprises one or more cooling means, for example a double jacket extending over at least part of the total length of the loop of the reactor 4 in which a cooling heat transfer fluid circulates, with the aim of eliminating the heat resulting from the exothermic reactions. Advantageously, these cooling means are located at the level of the straight portions of the reactor 4.

[0109] Advantageously, the reactor 4 according to the invention further comprises a pressure recovery system 5 to maintain the circulation of a liquid phase inside it, for example a recirculation pump or a turbine. LIST OF FIGURES [Fig. 1]

[0110] [Fig-1]: Schematic representation (not to scale) of a tubular reactor with loop 4 according to an embodiment of the invention and for implementing the oligomerization process according to an embodiment of the invention. In a first configuration, at position A is injected 1 the olefinic feedstock, the catalytic system and optionally a solvent. In a second configuration, at position A is injected 1 the olefinic feedstock, at position C is injected 2 a catalytic system accompanied or not by a solvent. In a third configuration, at position A is injected 1 the olefinic feedstock, at position C is injected 2 a catalytic system, and at position D is injected 2' a solvent. A recirculation pump 5 makes it possible to maintain the flow of the liquid phase within the reactor 4 in a circulation direction 6.The products of reaction 3 are withdrawn from reactor 4 by a withdrawal means placed at a position B of reactor 4, position B being able to be placed on reactor 4 in an area located at a distance from position A of between 70.00%. B' and 99.99% B” of the total length of the loop of said reactor 4 in the flow direction 6 of the liquid phase within said reactor 4. EXAMPLES

[0111] Example 1: Process according to an embodiment of the invention for the dimerization of ethylene into butene-1:

[0112] A process for the dimerization of ethylene into butene-1 is considered, carried out according to the scheme of [Fig.l]. An ethylene feedstock 1 and a homogeneous Ni-based catalytic system 2 are injected into reactor 4. Reactor 4 has a diameter of 0.55 m, and a total loop length of L = 1178 m. The temperature and pressure in reactor 4 are 50°C and 2.6 MPa. The feedstock is injected at a flow rate of 12.9 kg / s, the superficial velocity of the liquid phase in reactor 4 is 10.3 ms '.

[0113] The following table compares the conversion and productivity values ​​of the process for a withdrawal position B of the oligomerization products 3 located at a distance from the feed injection position A of 50% of L (589 m; comparative), and at a distance from the position A of 99.90% of L (1176.822 m; according to the invention) in the flow direction 6 of the liquid phase within the reactor 4.

[0114] [Tables 1] Distance between the withdrawal position B and the injection position of the load A Ethylene conversion rate (%) Productivity (kg-butene-1 ) / (kg-ethylene) 50% of L 85.28% 0.6461 99.90% of L 85.72% 0.6491 Gain (99.90% of L vs. 50% of L) +0.51% +0.46%

[0115] It is therefore observed that by placing the withdrawal position B of the products at a distance from the injection position A of the ethylene feedstock of between 70.00 and 99.99% of the total loop length of the reactor 4 in the flow direction 6 of the liquid phase within the reactor 4, a gain in ethylene conversion (+0.51%) and a gain in productivity (+0.46%) are obtained.

[0116] Example 2: Process according to an embodiment of the invention for trimerization of ethylene into hexene-1:

[0117] We consider a process for trimerization of ethylene into hexene-1 carried out according to the scheme of [Fig.l]. An ethylene feed 1, a homogeneous catalytic system 2 based on Cr and cyclohexane 2' as solvent are injected into reactor 4. Reactor 4 has a diameter of 0.25m, and a total loop length of L = 1330 m. The temperature and pressure in reactor 4 are 60°C and 13.5 MPa. Feed 1 is injected at a flow rate of 5.2 kg / s, solvent 2 is injected at a flow rate of 11.9 kg / s, the superficial velocity of the liquid phase in reactor 4 is 13 ms

[0118] The following table compares the conversion and productivity values ​​of the process for a withdrawal position B of the oligomerization products 3 located at a distance from the feed injection position A of 50% of L (665 m; comparative), and at a distance from position A of 99.90% of L (1128.87 m; according to the invention) in the flow direction 6 of the liquid phase within reactor 4.

[0119] [T ables 2] Distance between draw-off position B and feed injection position A Ethylene conversion rate (%) Productivity (kg-hexene-1) / (kg-ethylene) 50% of L 52.2% 0.4969 99.90% of L 52.9% 0.5036 Gain (99.99% of L vs. 50% of L) +1.34% +1.35%

[0120] It is therefore observed that by placing the withdrawal position B of the products at a distance from the injection position A of the ethylene feedstock of between 70.00 and 99.99% of the total loop length of the reactor 4 in the flow direction 6 of the liquid phase within the reactor 4, a gain in ethylene conversion (+1.34%) and a gain in productivity (+1.35%) are obtained.

Claims

Claims

1. A process for oligomerizing an olefinic feedstock, carried out at a pressure of between 0.1 and 15.0 MPa and at a temperature of between 30 and 200°C, comprising the following steps: a) injection into a tubular loop reactor of at least the olefinic feedstock and a catalytic system, said olefinic feedstock being injected by an injection means placed at a position A of the reactor, and formation of a liquid phase flowing continuously in the reactor; b) withdrawal of the products of the oligomerization reaction by a withdrawal means placed at a position B of the reactor located at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

2. The process of claim 1, wherein the olefinic feedstock is ethylene gas.

3. Method according to claim 1 or 2, in which the catalytic system is injected by an injection means placed at a position C of the reactor different from position A and position B.

4. A method according to any preceding claim, wherein step a) further comprises injecting a solvent into the tubular loop reactor.

5. Method according to claim 4, in which the catalytic system and the solvent are injected alone or in a mixture by one or more injection means placed at a position C of the reactor different from position A and position B.

6. A method according to claim 4, wherein the catalytic system is injected by an injection means placed at a position C of the reactor and the solvent is injected by an injection means placed at a position D of the reactor, the position C and the position D being different from each other and different from the position A and the position B.

7. A method according to any preceding claim, wherein the catalytic system is a homogeneous catalytic system.

8. A method according to claim 7, wherein the homogeneous catalytic system comprises a metal precursor based on nickel, titanium or chromium.

9. A method according to any preceding claim, wherein position B is located at a distance from position A of between 85.00 and 99.99% of the total length L of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

10. A method according to any one of the preceding claims, wherein position B is located at a distance from position A of between 95.00 and 99.99% of the total length L of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

11. A method according to any one of the preceding claims, wherein position B is located at a distance from position A of between 99.00 and 99.99% of the total length of the loop of said reactor in the direction of flow of the liquid phase within said reactor.

12. Tubular loop reactor (4) capable of containing a liquid phase, comprising: - a means for injecting an olefinic feedstock (1) placed at a position A of the reactor, - a means for withdrawing the products (3) placed at a position B of the reactor located at a distance from position A of between 70.00 and 99.99% of the total length of the loop of said reactor (4) in the direction of flow (6) of the liquid phase within said reactor (4).

13. Reactor (4) according to claim 12, further comprising means for injecting a catalytic system and optionally a solvent (2) placed at a position C of the reactor different from position A and position B.

14. Reactor (4) according to claim 12, further comprising means for injecting a catalytic system (2) placed at a position C of the reactor, and means for injecting a solvent (2') placed at a position D of the reactor, the position C and the position D being different from each other, and different from the position A and the position B.

15. Reactor (4) according to any one of claims 12 to 14, wherein position B is located at a distance from position A of between 85.00 and 99.99% of the total length L of the loop of said reactor (4) in the direction of flow (6) of the liquid phase within said reactor (4).

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