Compartmentalized Oligomerization Reactor

Abstract

To provide reactors permitting the oligomerization of olefins to give linear olefins.SOLUTION: There is provided a reactor, comprising: a reactor chamber 1 of elongate shape along the vertical axis; a plurality of n oligomerization zones Zn, which are delimited by internal compartmentalization walls 2, 4 arranged along the vertical axis of the chamber 1 and which are each able to contain a liquid part of catalytic activity and a gaseous part; means for connecting the n oligomerization zones in series; means for introducing, into the first compartment Z1, a flow comprising an olefinic feedstock E1; means for withdrawing, from the final compartment Zn, an oligomerization effluent E5, wherein n is an integer between 2 and 10; the internal compartmentalization walls are arranged in such a way as to delimit the n oligomerization zones Zn; and the n oligomerization zones Zn is interconnected in series so as to be able to transfer a liquid phase of catalytic activity from a zone Zn-1 to an adjacent zone Zn by way of the connection means.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to the field of gas / liquid reactors making it possible to oligomerize olefins to give linear olefins by homogeneous catalytic reactions, the reactors comprising a reaction chamber and vertical internal compartmentalization means.

[0002] The present invention also relates to the use of a compartmentalized gas / liquid reactor in a process for oligomerizing ethylene to obtain linear alpha-olefins, such as but-1-ene, hex-1-ene or oct-1-ene, or a mixture of linear alpha-olefins. Summary of the Invention [Means for solving the problem]

[0003] The applicant has developed a novel reactor compartmentalized into n oligomerization zones. Surprisingly, the use of said reactor in a process for the oligomerization of an olefinic feedstock, in particular ethylene, advantageously makes it possible to achieve higher levels of selectivity and conversion. In particular, the reactor according to the invention makes it possible to selectively obtain linear olefins, preferably alpha-olefins, such as but-1-ene, hex-1-ene and oct-1-ene. Effect of the Invention

[0004] Another advantage of the reactor according to the invention is that it facilitates the construction and therefore limits the costs for carrying out the oligomerization of ethylene in n oligomerization zones compared to carrying out in a chain of several reactors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] (Subject of the Invention) The subject of the present invention is therefore a reactor for the homogeneous catalytic oligomerization of olefins, comprising: A reactor chamber (1) of elongated shape along a vertical axis; a plurality of n oligomerization zones (Zn), bounded by internal compartmentalizing walls (2, 4) arranged along the vertical axis of the chamber (1) and each capable of containing a catalytically active liquid portion and a gaseous portion; means for connecting n oligomerization zones in series; means for introducing into the first zone (Z1) a stream comprising an olefinic feedstock; Means for withdrawing the oligomerization effluent from the last section (Zn) Including, n is an integer from 2 to 10; The internal compartmentalization walls are arranged to delimit the n oligomerization zones (Zn), which are interconnected in series such that the catalytically active liquid phase can be transferred from a zone (Zn-1) to an adjacent zone Zn by a passage in the connecting means. A reactor.

[0006] Preferably, the compartmentalization walls are identical or different and are selected from among flat plates, curved plates, cylindrical walls or spiral plates.

[0007] Preferably, at least one internal compartmentalization wall runs the entire length of the reactor, thereby preventing the passage of liquid between two adjacent oligomerization zones.

[0008] Preferably, the means of connection between two adjacent oligomerization zones is outside the reactor chamber (1).

[0009] Preferably, the reactor further comprises an internal connection means whereby gravity flow is achieved.

[0010] Preferably, the internal connection means is selected from among an orifice or a recess.

[0011] Preferably, the internal compartmentalizing walls have a triangular and / or circular shape in their upper part.

[0012] Preferably, the connecting means of an upstream compartmentalisation wall may advantageously be situated higher than the connecting means of the adjacent downstream compartmentalisation wall.

[0013] Preferably, the number n of oligomerization zones is 2-8.

[0014] Preferably, the reactor chamber (1) has a height to width ratio (denoted as H / W) of 1-17.

[0015] Preferably, each oligomerization zone contains one or more agitation means selected from among a recirculation loop and a mechanical agitation means.

[0016] Preferably, each oligomerization zone includes a recycle loop in combination with at least one heat exchanger.

[0017] Preferably, one or more of the oligomerization zones (Z2) to (Zn) comprises means for introducing an olefinic feedstock.

[0018] Preferably, the last oligomerization zone (Zn) does not include a means for introducing an olefinic feedstock.

[0019] Preferably, the gas / liquid oligomerization reactor comprises means for introducing a catalyst system into the first oligomerization zone (Z1), said means being located in the lower part, more particularly at the bottom, of said first oligomerization zone (Z1).

[0020] The present invention also relates to a process for homogeneous catalytic oligomerization using the reactor described above.

[0021] The various components of the reactor will be described by reference numerals throughout the drawings, with each component retaining the same reference numeral from one drawing to another.

[0022] (List of Drawings) Figure 1 is a graph depicting the change in conversion of ethylene (ordinate) as a function of the number of oligomerization zones (abscissa) arranged in series in the reactor for a selectivity of 90% and 91% of hex-1-ene. The values ​​are normalized by the reference values ​​obtained for one reactor and a selectivity of 90%. The results shown in Figure 1 were obtained by catalytic reaction with chromium as described in patent FR 3 019 064 and illustrated in the examples thereof.

[0023] Figure 2 shows a schematic three-dimensional view of a gas / liquid oligomerization reactor according to the invention. The reactor has a reactor chamber (1) in which three oligomerization zones arranged in series and labelled (Z1), (Z2) and (Z3) are delimited by internal compartmentalisation walls (2) and (4). Wall (2) is a vertical flat plate and wall (4) is a cylindrical plate. Compartments (Z1) and (Z2) are connected by a connecting means (3). The connecting means (3) corresponds to a triangular shaped recess in the upper part of the inner wall (2). Compartments (Z2) and (Z3) are connected by connecting means (5) and (6), which correspond respectively to rectangular and triangular shaped recesses in the upper part of the inner wall (4) and at a level below the connecting means (3). The dashed arrows indicate the direction of liquid flow between the series-connected oligomerization zones (Z1) to (Z3) in the reactor, and also indicate the introduction of the olefinic feedstock (E1) into the oligomerization zone (Z1) by an introduction means, and the withdrawal of the oligomerization effluent (E5) from the last zone (Z3) by an withdrawal means.

[0024] Figure 3 shows a schematic three-dimensional view of another gas / liquid oligomerization reactor according to the invention. The reactor of Figure 3 differs from that of Figure 2 in that an internal compartmentalization wall (2) extends to the top of the reactor chamber, thereby delimiting and isolating the oligomerization zones (Z1) and (Z2) from each other. The oligomerization zones (Z1) and (Z2) are connected by external connection means. The olefinic feedstock (E1) is introduced into the bottom of the oligomerization zone (Z1) and the liquid part of the reactor is withdrawn in stream (E2). Said stream (E2) is split into two streams (E3) and (E4). Stream (E4) is introduced into the oligomerization zone (E2). Streams (E2) and (E3) correspond to a recirculation loop of the oligomerization zone (Z1), making it possible to obtain a good mixing of the liquid part of zone (Z1). An olefinic feedstock (E1) is introduced into the oligomerization zone (Z1) by an introduction means and an oligomerized effluent (E5) is withdrawn from the last zone (Z3) by an withdrawal means. The dashed arrows indicate the direction of circulation of the flows in the different oligomerization zones of the reactor.

[0025] 4 is a schematic plan view of a reactor according to the invention, which comprises four oligomerization zones connected in series, the zones (Z1), (Z2) and (Z3) having the same dimensions. The zones (Z1), (Z2) and (Z3) are bounded by a flat internal compartmentalization wall (2). The zone (Z4) is bounded by a cylindrical internal wall. The dashed arrows indicate the direction of flow of the liquid fraction from zone (Z1) to zone (Z2), from zone (Z2) to zone (Z3) and from zone (Z3) to zone (Z4).

[0026] Figure 5 is another schematic plan view showing a reactor arrangement which differs from Figure 4 in that all the zones have different dimensions. In this particular case, the volumes of the sections increase gradually from (Z1) to (Z4), facilitating an increase in the residence time in the zones as oligomerization progresses.

[0027] FIG. 6 is another schematic plan view showing a reactor configuration in which five oligomerization zones are delimited by a combination of helical and flat plates.

[0028] (Definitions and Abbreviations) Throughout this specification, the following terms or abbreviations have the following meanings:

[0029] Oligomerization is understood to mean any addition reaction of a first olefin with a second olefin, which may be identical or different to the first olefin. The olefins thus obtained can be n H 2n of the type where n is 4 or greater.

[0030] Homogeneous catalysis is understood as meaning catalysis in which the catalyst system is soluble or dissolved in the liquid portion.

[0031] Alpha-olefin is understood as meaning an olefin in which the double bond is located at the terminal position of the alkyl chain.

[0032] A catalyst system is understood as meaning a mixture of at least one metal precursor, optionally at least one activator and optionally at least one ligand, optionally in a solvent.

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

[0034] The terms upstream and downstream are used in the context of the present invention with reference to the circulation of the liquid fraction in the reactor.

[0035] Throughout this specification, terms of spatial positioning, such as "vertical", "horizontal", "upper" or "lower", are to be understood with the reactor placed in its operating position in a horizontal plane, as shown in Figures 1 and 2.

[0036] Detailed Description of the Invention It is expressly stated that throughout this description, the expression "between ... and ..." is to be understood as including both limits referred to.

[0037] Within the meaning of the present invention, the different embodiments presented can be used alone or in combination with one another, without any restrictions to combinations where this is technically feasible.

[0038] Particular types of reactors according to the invention are, where technically appropriate, reactors consisting of a single embodiment or a combination of several embodiments as described below.

[0039] (Reactor) The invention therefore relates to a reactor for homogeneous catalytic oligomerization, preferably a gas / liquid reactor, comprising: A reactor chamber (1) having an elongated shape along a vertical axis; a plurality of n oligomerization zones (Zn); delimited by internal compartmentalizing walls (2, 4) arranged along the vertical axis of the chamber (1), each capable of containing a catalytically active liquid fraction and a gaseous fraction; means for connecting n oligomerization zones in series; means for introducing into the first zone (Z1) a stream comprising an olefinic feedstock; Means for withdrawing oligomerization effluent from the last zone Zn Including, n is an integer from 2 to 10; The internal compartmentalization walls are arranged to define the boundaries of the n oligomerization zones (Zn). The n oligomerization zones (Zn) are interconnected in series such that the connecting means allows the transfer of the catalytically active liquid phase from zone (Zn-1) to the adjacent zone (Zn).

[0040] Preferably, the oligomerization reactor, preferably a gas / liquid oligomerization reactor, comprises a plurality of n oligomerization zones, which are between 2 and 8, preferably between 2 and 6, with n preferably equal to 2, 3, 4 or 5.

[0041] The oligomerization zones according to the invention are connected in series and delimited along the vertical axis of the reactor so as to define zones having liquid portions with concentrations of reagents, catalysts and various products, making it possible to approach the hydrodynamic behavior of a plug-flow type reactor in all oligomerization zones contained in the reaction chamber. Another advantage of the reactor according to the invention is the obtaining of a plug-flow type arrangement in a single reactor, which significantly reduces the cost of the implementation of the reactor.

[0042] For the last zone (Zn) of the cascade of oligomerization zones, the effluent withdrawn by the withdrawal means corresponds to the effluent obtained at the end of the oligomerization process and can be conveyed to a separation section to separate the resulting linear olefins. Preferably, the withdrawal means is a pipe.

[0043] The reactor contains a reactor chamber (1) which preferably has a cylindrical wall.

[0044] Preferably, the reactor chamber (1) has a height to width ratio (expressed as H / W) of 1-17, preferably 1-8, suitably 2-6.

[0045] The oligomerization zones (Zn), bounded by internal compartmentalization walls, can be of the same size or can increase or decrease in the direction of flow of the liquid fraction in the reactor, depending on the desired hydrodynamic behavior.

[0046] (Recirculation Loop) Advantageously, the gas / liquid oligomerization reactor comprises one or more stirring means in each oligomerization zone, the stirring means being chosen from among recirculation loops and mechanical stirring means, said mechanical stirring means representing stirring blades, vanes or any other means known to the person skilled in the art.

[0047] In a preferred embodiment, the gas / liquid oligomerization reactor preferably comprises one recycle loop per oligomerization zone, each recycle loop comprising at least one withdrawal means, preferably in the lower part of the oligomerization zone, preferably at the bottom, and a means of introduction, preferably in the upper part of the oligomerization zone.

[0048] The recirculation loop makes it possible to achieve a good homogenization of the concentrations in the liquid parts of the oligomerization zones of the reactor, so that the homogenization in each of the oligomerization zones (Zn) can be regulated independently of each other.

[0049] Preferably, each of the n oligomerization zones (Zn) of the reactor according to the invention comprises a recycle loop.

[0050] The extraction is carried out by any means capable of performing the extraction, which is preferably a pipe, possibly combined with a pump.

[0051] For each oligomerization zone comprising a recirculation loop, withdrawal of liquid from a given oligomerization zone is preferably effected starting from a point situated below the point of introduction into said zone. For a given oligomerization zone comprising a recirculation loop, withdrawal is preferably effected in the lower part of the oligomerization zone. For each oligomerization zone comprising a recirculation loop, introduction into said oligomerization zone is preferably effected starting from a point situated above the point of withdrawal of liquid. For a given oligomerization zone comprising a recirculation loop, introduction is preferably effected in the upper part of said zone.

[0052] In another embodiment, all introductions and withdrawals are carried out along the reactor through tubes equipped with orifices, which may be cylindrical holes or slits, preferably spaced at regular intervals all along the introduction or withdrawal tube. The smallest characteristic dimension of the orifices (slit width or diameter) is preferably greater than 2 mm, preferably greater than 5 mm, suitably greater than 8 mm, thereby avoiding any risk of clogging.

[0053] Any other type of injection or extraction is possible, the objective being to maintain independent loops between each band.

[0054] Advantageously, the recirculation loop further comprises a heat exchanger or heat exchangers, by means of which the liquid fraction in the recirculation loop is cooled.

[0055] A suitable heat exchanger for cooling the liquid fraction may be selected from any means known to those skilled in the art.

[0056] Preferably, each oligomerization zone comprises a heat exchanger integrated in a recirculation loop. Preferably, each oligomerization zone has its own recirculation loop with its point of entry of liquid and its point of departure of liquid originating from said loop. The recirculation loop can advantageously be implemented by any necessary means known to the skilled person, such as a pump for the withdrawal of the liquid fraction, a means capable of regulating the flow rate of the withdrawn liquid fraction, and also a pipe for taking off at least a part of the withdrawn liquid fraction.

[0057] When the first oligomerization zone (Z1) comprises a recirculation loop and a heat exchanger, the introduction of the cooled liquid in said zone (Z1) is preferably carried out by any means known to those skilled in the art in a zone above the gaseous or liquid part. The withdrawal is preferably carried out below the level of the introduction of the olefinic feedstock, preferably at the bottom of the oligomerization zone.

[0058] The withdrawal is advantageously carried out by any means making it possible to carry out the withdrawal, in particular by using a pump.

[0059] Advantageously, for the oligomerization zone of the reactor according to the invention, the liquid phase is preferably withdrawn by means of an intake under control of the liquid level, whereby the liquid level is kept constant. The intake means may be any means known to the person skilled in the art, for example a valve.

[0060] (Internal compartmentalization walls) According to the invention, a gas / liquid reactor for homogeneous catalytic oligomerization comprises compartmentalization walls for delimiting n oligomerization zones, denoted (Zn), in the reactor, which makes it possible to approach the hydrodynamic behavior of a plug-flow type reactor with the force of n oligomerization zones arranged in series.

[0061] Preferably, the compartmentalization walls are identical or different and are selected from among flat plates, curved plates, cylindrical walls or spiral plates.

[0062] In a first particular embodiment, the internal compartmentalization wall spans the entire height of the reactor, i.e. from the bottom to the top of the reactor, thereby preventing the passage of liquid between two adjacent zones. The liquid parts of the compartments are therefore isolated from each other and the serial communication is provided by connection means located outside the reactor chamber (1), called external connection means.

[0063] In a second particular embodiment, the serial communication between the oligomerization zones is provided by connection means located inside the reactor chamber, in which case the internal connection means are advantageously orifices or recesses present above each of the internal compartmentalized zones, which ensure liquid flow, preferably by gravity, from an upstream zone to the adjacent downstream zone.

[0064] Preferably, whatever the embodiment, the upper gas phase is common to the different oligomerization zones.

[0065] Advantageously, when the reactor comprises internal connection means, said means are arranged, by the geometry of particular recesses in the internal compartmentalisation walls, to make the flow of liquid continuous, preferably by gravity flow, from the oligomerisation zone (Z1) to the adjacent oligomerisation zone (Z2) and from zone (Z2) to the adjacent zone (Z3), likewise to the last oligomerisation zone (Zn).

[0066] Without limitation, the internal compartmentalization walls can have a triangular or circular shape in their upper part, thus having a cross section of passage that increases as the liquid level rises during the operation of the reactor. The advantage of this type of geometry is that it maintains a stable level of liquid in the compartments while allowing flexibility in the operation of the reactor, especially in terms of adapting the flow rate / residence time.

[0067] When the oligomerization zones (Zn) are connected by gravity flow, the connecting means of the upstream compartmentalization wall may advantageously be positioned higher than the connecting means of the adjacent downstream compartmentalization wall.

[0068] A gas / liquid oligomerization reactor may comprise a combination of compartmentalization walls according to the first and second embodiments, said reactor then comprising a combination of internal and external connecting means.

[0069] In addition, the compartmentalization wall may be provided with openings, e.g. perforations, triangular, circular, square or rectangular shaped orifices, preferably at the bottom of the reactor, to better distribute the liquid from the upstream oligomerization zone to the adjacent downstream oligomerization zone in the direction of flow. Preferably, said orifices may be partially or totally on the upper part of the compartmentalization wall to impose a gravity flow. Advantageously, when the openings are located at the bottom of the reactor, they also make it easier to empty the entire reactor chamber, e.g. during shutdown phases and during maintenance operations.

[0070] In a particular embodiment, the external connection means of the oligomerization zones (Z2) to (Zn) (thus excluding the first oligomerization zone of the reactor) are liquid supply means for introducing a part of the liquid fraction withdrawn from the upstream oligomerization zone (Zn-1) into the adjacent downstream oligomerization zone (Zn). These supply means can be a pipe feeding directly into the oligomerization zone (Zn) in one embodiment, or a pipe connecting the recycle loop of the oligomerization zone (Zn-1) directly to the adjacent oligomerization zone (Zn), or a pipe connecting the recycle loop of the oligomerization zone (Zn-1) to the recycle loop of said adjacent oligomerization zone (Zn).

[0071] Preferably, the means for withdrawing the liquid portion in the final oligomerization zone (Zn) of the reactor is a pipe. The liquid fraction withdrawn through said pipe corresponds to the effluent of the oligomerization process used in the reactor according to the invention.

[0072] One advantage of the present invention is therefore that it makes it possible to achieve selectivities for linear olefins, preferably linear alpha-olefins, which are superior to those achieved by prior art reactors comprising only a single reactor chamber, and this is obtained while maintaining a high level of conversion to linear olefins.

[0073] Means for Introducing Olefinic Feedstock According to the invention, the gas / liquid oligomerization reactor comprises means for introducing the olefinic feedstock into the first oligomerization zone (Z1), said means being preferably located in the lower part of the reactor zone (Z1), more particularly at the bottom of said zone (Z1).

[0074] Advantageously, one or more of the oligomerization zones (Z2) to (Zn) may also comprise a means for the introduction of an olefinic feedstock. In a particular embodiment, one or more of the oligomerization zones (Z2) to (Zn-1) may comprise a means for the introduction of an olefinic feedstock, i.e. the last oligomerization zone (Zn) does not comprise a means for the introduction of an olefinic feedstock.

[0075] Preferably, the means for the introduction of the olefinic feedstock is selected from a pipe, a network of pipes, a multi-tube distributor, a perforated plate or any other means known to those skilled in the art.

[0076] Preferably, a gas distributor, which is a device making it possible to homogeneously distribute the gaseous olefinic feedstock throughout the liquid section of the oligomerization zone, is positioned at the end of said means for introducing said feedstock into the oligomerization zone of the reactor, said device comprising a network of perforated plates, the orifices of which have a diameter of 1-12 mm, preferably 3-10 mm, thereby forming millimeter-sized ethylene bubbles in the liquid.

[0077] Said gas / liquid oligomerization reactor may also comprise means for the introduction of a catalytic system in the first oligomerization zone (Z1), said means being placed in the lower part, more particularly at the bottom of said zone (Z1). Advantageously, one or more of the oligomerization zones (Z2) to (Zn) may also comprise means for the introduction of a catalytic system. According to an alternative embodiment, the catalytic system is introduced into the recycle loop of the oligomerization zone.

[0078] The distribution of catalytic activity in the different oligomerization zones (Z1) to (Zn) of the reactor according to the invention is determined by the amount of catalytic system introduced into each of the oligomerization zones.

[0079] (Method of extraction) According to the invention, the gas / liquid reactor for homogeneous catalytic oligomerization comprises means for withdrawing the oligomerization effluent from the final oligomerization zone (Zn).

[0080] Thus, in the reactor according to the invention, the combination of the means for the introduction of the olefinic feedstock in the first oligomerization zone (Z1), the means for withdrawal in the last oligomerization zone (Zn) and the means for linking the succession of oligomerization zones makes it possible to define the direction of flow from zone (Z1) to zone (Zn) and therefore to approach the hydrodynamic behavior of a plug-flow type reactor.

[0081] (Method of using the reactor according to the present invention) The present invention also relates to a process for oligomerization using the reactor according to the invention.

[0082] The process of oligomerization using the reactor according to the invention makes it possible to obtain linear olefins, in particular linear alpha-olefins, by contacting the olefin(s) and the catalytic system, optionally in the presence of additives and / or solvents, and by using said gas / liquid oligomerization reactor according to the invention.

[0083] Any homogeneous catalytic system known to those skilled in the art and that can be used in oligomerization processes, in particular dimerization, trimerization or tetramerization processes, falls within the scope of the present invention. Said catalytic systems, as well as their implementation, are described in particular in applications FR 2 984 311, FR 2 552 079, FR 3 019 064, FR 3 023 183, FR 3 042 989 and also in application FR 3 045 414. Preferably, the catalytic systems are based on nickel, titanium or chromium.

[0084] The olefinic feedstock is preferably a linear olefin containing from 2 to 10 carbon atoms; the olefinic feedstock is preferably ethylene.

[0085] The pressure when the oligomerization method is carried out is 1.0 to 10.0 MPa, preferably 2.0 to 8.0 MPa, more preferably 4.0 to 8.0 MPa, and more particularly 6.0 to 8.0 MPa. The temperature is 0°C to 200°C, preferably 30°C to 180°C, more preferably 30°C to 150°C, and even more preferably 40°C to 140°C.

[0086] The residence time of the reaction medium in the reactor according to the invention is, on average, from 2 to 400 minutes, preferably from 20 to 150 minutes, preferably from 30 to 120 minutes. The residence time of the reaction medium in each compartment is, on average, from 1 to 30 minutes, preferably from 5 to 20 minutes, even more preferably from 5 to 15 minutes.

[0087] The olefinic feedstock is preferably introduced by dispersion in the liquid part of the first oligomerization zone (Z1), preferably in the lower part of the compartmentalized gas / liquid reactor, more preferably in the compartment (Z1), more particularly in the bottom.

[0088] The olefinic feedstock may be introduced into each oligomerization zone of the gas / liquid reactor according to the invention, preferably exclusively into the first oligomerization zone, more particularly, when the olefin is introduced into an oligomerization zone, the introduction takes place in the lower part of said zone.

[0089] In one embodiment, the olefins may be introduced into one or more recycle loops.

[0090] Preferably, the linear olefin obtained by the process using the reactor according to the invention contains from 4 to 12 carbon atoms. Highly preferably, the linear olefin obtained is a linear alpha-olefin, preferably but-1-ene, hex-1-ene or oct-1-ene.

[0091] The following examples illustrate the present invention but do not limit the scope of the invention.

[0092] (Example) In the following examples, the means for the introduction of the feedstock (E1), the means for the withdrawal of the effluent (E5) and the means for connection are as shown in Figure 2. In the case where the zones are delimited by flat internal compartmentalization walls, the connection means are as shown in Figure 2 for the flat internal wall (2).

[0093] (Example 1: according to the present invention, corresponding to the reactor as in FIG. 2, the layout of the oligomerization zone as in FIG. 4) This example uses an ethylene oligomerization reactor, which contains four oligomerization zones, of identical volume, arranged as shown in Figure 4. The catalytic system introduced into each section of the reactor is a chromium-based catalytic system, as described in patent FR 3 019 064, with a chromium content of 4 ppm in the presence of a solvent, namely cyclohexane.

[0094] The reaction volume of each of the oligomerization zones was 36.7 m 3All of the zones are operated at a temperature of 135° C. and a pressure of 6.0 MPa.

[0095] The overall residence time in the reactor is 21.1 minutes.

[0096] The volumetric productivity of this reaction device is expressed as the product of time and volume of the total reaction volume (m 3 ) is 170 kg of alpha-olefins produced.

[0097] The performance qualities of the reactor according to the invention make it possible to convert 49.07% of the injected ethylene, for a solvent content by weight of (2.7), and to achieve a selectivity of 91.04% for hex-1-ene, illustrating the benefits of the reactor according to the invention.

[0098] (Example 2: according to the present invention, corresponding to the reactor as in FIG. 2, the layout of the oligomerization zone as in FIG. 5) This example uses an ethylene oligomerization reactor, which contains four oligomerization zones, of increasing volume in the direction of the flow of the liquid portion, arranged according to Figure 5. In contrast to the case treated in example 1, the catalytic system is introduced only in the first section. This catalytic system is a chromium-based catalytic system, as described in patent FR 3 019 064, with a chromium content of 4 ppm, and is introduced in the presence of a solvent, namely cyclohexane.

[0099] The reaction volume of the oligomerization zone was 36.2 m 3 , 43.8m 3 , 55.5m 3 and 73.2m 3 All of the zones are operated at a temperature of 135° C. and a pressure of 6.0 MPa.

[0100] The overall residence time in the reactor is 30.1 minutes.

[0101] The volumetric productivity of this reaction device is expressed as the product of the total reaction volume (m 3 ) yield of 120 kg of alpha-olefins.

[0102] The performance qualities of the reactor according to Example 2 make it possible to achieve the same selectivity for hex-1-ene (91.04%) as in the preceding case for the same conversion of injected ethylene (49.07%) and the same content by weight of solvent (2.7), with simplified use thanks to the presence of a single injection of the catalyst system into the reactor.

[0103] Example 3: according to the invention, corresponding to a reactor according to FIG. 2, with an oligomerization zone of increasing volume. This example uses an ethylene oligomerization reactor, which comprises three oligomerization zones, of increasing volume in the direction of the flow of the liquid portion, only the first two zones (Z1) and (Z2) having a gaseous injection of ethylene at the bottom of each of said zones (Z1) and (Z2). The catalytic system introduced exclusively in the first section is a chromium-based catalytic system, with a chromium content of 4 ppm in the presence of a solvent, namely cyclohexane, as described in patent FR 3 019 064.

[0104] The reaction volume of the oligomerization zone was 52.7 m 3 , 66.0m 3 and 89.2m 3 All of the zones are operated at a temperature of 135° C. and a pressure of 6.0 MPa.

[0105] The overall residence time in the reactor is 36.5 minutes.

[0106] The volumetric productivity of this reaction device is expressed as the product of time and total reaction volume (m 3 ) produces 120 kg of alpha-olefins.

[0107] The performance qualities of this reaction device in accordance with the invention make it possible to increase the conversion to 63.36% of the injected ethylene, for a solvent content of 2.8, with a selectivity for hex-1-ene of 89.78%, and allow a simplified use in a single reactor, by injecting the catalyst system in a single position. [Brief description of the drawings]

[0108] [Figure 1] 1 is a graph depicting the change in conversion of ethylene (ordinate) as a function of the number of oligomerization zones arranged in series in a reactor (abscissa) for a selectivity of hex-1-ene of 90% and 91%. [Diagram 2] FIG. 1 shows a schematic three-dimensional view of a gas / liquid oligomerization reactor according to the present invention. [Diagram 3] FIG. 2 shows a schematic three-dimensional view of another gas / liquid oligomerization reactor according to the present invention. [Figure 4] FIG. 1 is a schematic plan view of a reactor according to the present invention. [Diagram 5] FIG. 2 is another schematic plan view of a reactor according to the present invention. [Figure 6] FIG. 2 is another schematic plan view of a reactor according to the present invention.

Claims

1. A reactor for homogeneous catalytic oligomerization, comprising: - one reactor chamber (1) of elongated shape along a vertical axis; a plurality n of oligomerization zones (Zn), which are delimited by internal compartmentalizing walls arranged along the vertical axis of the chamber (1) and each of which can contain a catalytically active liquid fraction and a gaseous fraction; - means for connecting n oligomerization zones in series; - means for introducing into the first zone (Z1) a stream comprising an olefinic feedstock; - means for withdrawing the oligomerization effluent from the last section (Zn); Including, n is 3, said internal compartmentalization walls are arranged so as to delimit said n oligomerization zones (Zn) which are interconnected in series so that said connecting means allow the transfer of the catalytically active liquid phase from a zone (Zn-1) to an adjacent zone (Zn); Reactor.

2. 2. The reactor of claim 1, wherein the compartmentalization walls are identical or different and are selected from among flat plates, curved plates, cylindrical walls or spiral plates.

3. 3. The reactor of claim 1 or 2, wherein at least one internal compartmentalization wall runs the entire length of the reactor, thereby preventing the passage of liquid between two adjacent oligomerization zones.

4. 4. The reactor according to claim 3, wherein the means of connection between two adjacent oligomerization zones is outside the reactor chamber (1).

5. A reactor described in any one of claims 1 to 3, wherein serial communication between two adjacent oligomerization zones is provided by internal connecting means located inside the reactor chamber (1), thereby obtaining a gravity flow from the upstream zone to the adjacent downstream zone.

6. 6. The reactor of claim 5, wherein the interconnection means is selected from the group consisting of an orifice and a recess.

7. 7. The reactor according to claim 5 or 6, wherein the internal compartmentalization walls have a triangular and / or circular shape in their upper part.

8. Reactor according to any one of claims 5 to 7, wherein the connecting means of an upstream compartmentalisation wall may advantageously be situated higher than the connecting means of the adjacent downstream compartmentalisation wall.

9. The reactor according to any one of claims 1 to 8, wherein the number n of oligomerization zones is from 2 to 8.

10. The reactor according to any one of claims 1 to 9, wherein the reactor chamber (1) has a height to width ratio (denoted H / W) of 1 to 17.

11. A reactor according to any one of claims 1 to 10, wherein each oligomerization zone comprises one or more agitation means selected from among a recirculation loop and a mechanical agitation means.

12. 12. The reactor of claim 11, wherein each oligomerization zone comprises a recycle loop in combination with at least one heat exchanger.

13. The reactor according to any one of the preceding claims, wherein one or more of the oligomerization zones (Z2) to (Zn) comprise means for introducing an olefinic feedstock.

14. The reactor according to any one of claims 1 to 13, wherein the last oligomerization zone (Zn) does not comprise a means for introducing an olefinic feedstock.

15. A process for homogeneous catalytic oligomerization using a reactor according to any one of claims 1 to 14.

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