Patent Application
20200094213
The present invention relates to a compartmentalized reactor which makes possible the oligomerization of olefins to give linear olefins and preferably to give linear α-olefins, comprising a reaction chamber, compartmentalization means and at least one heat exchanger(s). The compartmentalized reactor is also employed in a process for the oligomerization of ethylene to give linear α-olefins, such as but-1-ene, hex-1-ene or oct-1-ene, or a mixture of linear α-olefins.
The invention relates to the field of processes for the oligomerization, in particular for the dimerization, trimerization or tetramerization, of olefins to give linear olefins and more particularly to give linear α-olefins. The present invention applies to all the processes for the oligomerization of olefins, such as, for example, the trimerization of ethylene to give hex-1-ene, presented in the continuation of the description.
Typically, oligomerization processes are carried out in gas/liquid reactors, also known as bubble columns. Due to the exothermic nature of oligomerization reactions, bubble point reactors also comprise a loop for recirculation of a liquid fraction. The good heat transfer capacity related to the recirculation loop makes it possible to obtain a good homogeneity of the concentrations and to control the temperature throughout the reaction volume.
For a given operating temperature and a given operating pressure, the performance qualities of such a reactor, in terms of selectivity and of conversion, are limited by the kinetic scheme inherent to the catalytic system (the main and secondary reactions) and to the operating conditions under consideration (the temperature and the pressure).
The main oligomerization reactions correspond to the reactions for the dimerization, trimerization and tetramerization of the starting olefins to give final linear olefins, for example the conversion of ethylene to give hex-1-ene. The secondary reactions correspond to the reactions of the final linear olefins obtained during the main reactions, such as, for example, the reaction of hex-1-ene with ethylene to produce decenes. These secondary reactions result in a decrease in the yield of linear olefins in favor of non-upgradeable byproducts.
These byproducts associated with the operating conditions create a performance ceiling such as represented in the curve for selectivity as a function of the conversion (see
In particular, the processes of the prior art, employing a bubble point reactor, as illustrated in
Surprisingly, the applicant company has discovered a specific implementation of the oligomerization process which makes it possible to simultaneously achieve higher levels of selectivity and of conversion than in the prior art. Such a process is carried out in a novel specific gas/liquid reactor comprising a reaction chamber comprising a plurality of compartmentalization means and at least one heat exchanger. Such a reactor makes it possible to approach a hydrodynamic behavior of a reactor of plug-flow type: the compartmentalization makes possible the segregation of the concentrations and the achievement of a homogeneous and laminar flow of the gas phase and of the liquid phase, greatly, indeed even completely, limiting the turbulent flow of the liquid phase which is typically encountered in the devices according to the prior art. Thus, the compartmentalization of the chamber of the reactor defines reaction zones with different concentrations of reaction liquid, thus making it possible to earn conversion points, with an unchanging selectivity, this being the case despite the exothermicity of the reaction. Thus, the oligomerization process according to the invention makes it possible to obtain an increase in the conversion of olefin(s), while retaining a virtually unchanging selectivity for linear olefins and in particular for α-olefins. These advantages make it possible to limit the costs for implementation of said process.
The applicant company has developed a compartmentalized oligomerization reactor D having an upward stream of a liquid phase and of a gas phase forming a reaction medium, said reactor comprising:
characterized in that a plurality of compartmentalization means (8) are located inside the chamber (1) of said reactor (D), each compartmentalization means (8) extending radially over the entire section of the chamber (1) of said reactor, so as to form a plurality of reaction zones (Z1, Z2, . . . , Zn) laid out vertically in tiers, and in that each compartmentalization means (8) comprises a plurality of openings (12) with a diameter between 1 and 20 mm suitable for the passage of the liquid phase and of the gas phase from one reaction zone to the next, said plurality of openings (12) occupying between 3% and 60% of the total surface area of each compartmentalization means (8).
The applicant company has also discovered that said reactor can be employed in an olefin oligomerization process employing the reactor according to the invention, at a pressure between 1.0 and 10.0 MPa and at a temperature between 0° C. and 200° C., comprising the following stages:
The following terms are defined in order to improve the understanding of the invention:
The term “oligomerization” denotes any addition reaction of a first olefin with a second olefin identical to or different from the first olefin and comprises dimerization, trimerization and tetramerization. The olefin thus obtained is of CnH2n type, where n is equal to or greater than 4.
The term “olefin” denotes both an olefin and a mixture of olefins.
The term “α-olefin” denotes an olefin in which the double bond is located at the terminal position of the alkyl chain.
The term “heteroatom” is an atom other than carbon and hydrogen. A heteroatom can be chosen from oxygen, sulfur, nitrogen, phosphorus, silicon and halides, such as fluorine, chlorine, bromine or iodine.
The term “hydrocarbon” is an organic compound consisting exclusively of carbon (C) and hydrogen (H) atoms of empirical formula CmHp, with m and p natural integers.
The term “catalytic system” denotes a mixture of at least one metal precursor, of at least one activating agent, optionally of at least one additive and optionally of at least one solvent.
The term “alkyl” is a saturated or unsaturated, linear or branched, non-cyclic, cyclic or polycyclic hydrocarbon chain comprising between 1 and 20 carbon atoms, preferably from 2 to 15 carbon atoms and more preferably still from 2 to 8 carbon atoms, denoted C1-C20 alkyl. For example, C1-C6 alkyl is understood to mean an alkyl chosen from the methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, hexyl and cyclohexyl groups.
The term “aryl” is a fused or non-fused, mono- or polycyclic, aromatic group comprising between 6 and 30 carbon atoms, denoted C6-C30 aryl.
The term “alkoxy” is a monovalent radical consisting of an alkyl group bonded to an oxygen atom, such as the C4H9O— group.
The term “aryloxy” is a monovalent radical consisting of an aryl group bonded to an oxygen atom, such as the C6H5O— group.
The term “liquid phase” denotes the mixture of all the compounds which occur in the liquid physical state under the temperature and pressure conditions of the gas/liquid reactor.
The term “gas phase” denotes the mixture of all the compounds which occur in the gas physical state under the temperature and pressure conditions of the gas/liquid reactor: in the form of bubbles present in the liquid, and also in the top part of the gas/liquid reactor (also known as headspace of the reactor or gas headspace).
The term “lower part” of the reaction chamber of the compartmentalized gas/liquid reactor or of a reaction zone respectively denotes the lower half of the reactor or of the reaction zone.
The term “upper part” of the reaction chamber of the compartmentalized gas/liquid reactor or of a reaction zone respectively denotes the upper half of the reactor or of the reaction zone.
The term “withdrawal flow rate” denotes the weight of liquid withdrawn from the reactor per unit of time; it is expressed in tonnes per hour (t/h).
The term “non-condensable gas” denotes a byproduct resulting from the side reactions, in the gas physical form under the temperature and pressure conditions of the process, which accumulates in the headspace of the reactor. The non-condensable gases are, for example, ethane, methane or butane (non-exhaustive list).
The term “cocurrent” denotes the circulation of a first fluid in the same direction of circulation as a second fluid.
The term “exchange surface” represents the surface where heat exchanges take place between the reaction medium and the cooling liquid.
The term “solvent” denotes a liquid which has the property of dissolving, diluting or extracting other substances without chemically modifying them and without itself being modified. The expression “between . . . and . . . ” should be understood as including the limits mentioned.
The present invention is not limited to the implementations represented in the figures. The subject matter of the invention is illustrated in the figures through the specific case of the trimerization of ethylene to give hex-1-ene.
The figures do not represent all of the means necessary for the implementation of the reactors known to a person skilled in the art, such as the means for injection of the catalytic system, of the olefin, optionally of a solvent, the gas distributor, nor the means for control of the pressure and the temperature of the compartmentalized gas/liquid reactor. The subject matter of the present invention is not limited to the specific case of the trimerization of hex-1-ene, illustrated in the continuation of the description.
Within the meaning of the present invention, the different embodiments presented can be used alone or in combination with one another, without any limit to the combinations. In the continuation of the description, the subject matter of the invention is illustrated in particular through the case of the trimerization of ethylene to give hex-1-ene.
The applicant company has discovered that it is possible to improve the conversion of olefin(s), while retaining a high selectivity for desired linear olefin(s), and in particular α-olefin(s), by providing a specific device in the form of a compartmentalized gas/liquid reactor and at least one heat exchanger. Such a reactor makes it possible to approach a hydrodynamic behavior of a reactor of plug-flow type: the compartmentalization of the chamber makes possible the segregation of the concentrations and the achievement of a homogeneous and laminar flow of the gas phase and of the liquid phase, greatly, indeed even completely, limiting the turbulent flow of the liquid phase which is typically encountered in the devices according to the prior art (cf.
The invention thus relates to a compartmentalized oligomerization reactor D having an upward stream of a liquid phase and of a gas phase forming a reaction medium, said reactor comprising:
characterized in that a plurality of compartmentalization means (8) are located inside the chamber (1) of said reactor (D), each compartmentalization means (8) extending radially over the entire section of the chamber (1) of said reactor, so as to form a plurality of reaction zones (Z1, Z2, . . . , Zn) laid out vertically in tiers, and in that each compartmentalization means (8) comprises a plurality of openings (12) with a diameter between 1 and 20 mm suitable for the passage of the liquid phase and of the gas phase from one reaction zone to the next, said plurality of openings (12) occupying between 3% and 60% of the total surface area of each compartmentalization means (8).
The invention also relates to an olefin oligomerization process employing the reactor according to the invention, at a pressure between 1.0 and 10.0 MPa and at a temperature between 0° C. and 200° C., comprising the following stages:
The invention relates to a compartmentalized oligomerization reactor D having an upward stream of a liquid phase and of a gas phase forming a reaction medium, said reactor comprising:
Said reactor can also comprise a means for introduction of the olefin 3, located in the lower part of the reaction chamber, more particularly in the bottom of the chamber, employing a means for injection of the olefin within said liquid phase of the reaction chamber. Said reactor can also comprise a means for introduction of the catalytic system 4, located in the lower part, more particularly in the bottom of the reaction chamber.
According to the invention, the reaction chamber exhibits a height to width ratio (denoted H/W) between 1 and 8, preferably between 4 and 8. Preferably, the reaction chamber is of cylindrical shape.
The compartmentalized gas/liquid reactor comprises a means for bleeding off 5 the gas phase, which gas phase is located at the top of the reactor.
The compartmentalized gas/liquid reactor comprises a means for recovery 7 of a reaction effluent at the top of the chamber; preferably, the recovery means is located below the gas/liquid interface of the final reaction zone, in the direction of flow of the liquid phase and the gas phase.
Preferably, the gas/liquid reactor also comprises a pressure sensor which makes it possible to keep the pressure constant within the reaction chamber. Preferably, said pressure is kept constant by the introduction of additional olefin into the reaction chamber.
Preferably, the gas/liquid reactor also comprises a liquid level sensor; said level is kept constant by adjusting the flow rate of the effluent withdrawn in stage c) of the process according to the invention. Preferably, the level sensor is located at the interphase between the liquid phase and the gas headspace.
The compartmentalized gas/liquid reactor is preferably a gas/liquid/solid reactor, the solid phase comprising the catalyst.
According to the invention, the compartmentalized gas/liquid reactor D comprises compartmentalization means 8 within the reaction chamber. Said means extend radially over the entire section of the chamber 1 of said reactor, so as to form a plurality of reaction zones Z1, Z2, . . . , Zn laid out vertically in tiers. The reaction zones are defined on the sides by the internal wall of the reaction chamber, above by the upper compartmentalization means or the roof of the chamber (for the final reaction zone Zn) and below by the lower compartmentalization means or the floor of the chamber (for the first reaction zone Z1). “n” is defined as a natural integer between 2 and 30, preferably between 2 and 20, more preferably between 2 and 15 and more preferably still between 4 and 10.
Preferably, the reaction zones all have the same volume.
Any compartmentalization means well known to a person skilled in the art can be used, such as a perforated plate.
Each compartmentalization means 8 comprises a plurality of openings 12 with a diameter between 1 and 20 mm, preferentially between 2 and 15 mm, preferably between 6 and 12 mm, suitable for the passage of the liquid phase and of the gas phase from one reaction zone to the next. Said plurality of openings 12 occupy between 3% and 60% of the total surface area of each compartmentalization means 8, preferentially between 20% and 60%, preferably between 35% and 55%.
Said means are capable of allowing the passage of the liquid phase and the gas phase of the reaction medium. Said compartmentalization means make it possible to approach a hydrodynamic behavior of a reactor of plug-flow type by segregating the concentrations and by greatly limiting, indeed even eliminating, the turbulent flow of the liquid phase, thus making it possible to have an upward laminar homogeneous liquid movement within the reaction chamber.
According to the invention, the compartmentalized gas/liquid reactor D comprises at least one heat exchanger(s) 2 in order to regulate the temperature within the reactor, in which a cooling liquid 6 circulates. Preferably, the cooling liquid circulates cocurrentwise with respect to the reaction medium.
The total surface area for exchange between the reaction medium, present within the chamber of said reactor, and the cooling liquid 6 is between 50 and 15 000 m2. The surface area for exchange between the reaction medium and the cooling liquid, in each reaction zone, is between 2 and 8000 m2.
The heat exchangers suitable for cooling the liquid fraction are chosen from any means known to a person skilled in the art.
Preferably, each reaction zone comprises a heat exchanger incorporated in a recirculation loop; preferentially, there are as many reaction zones as recirculation loops comprising a heat exchanger. Preferably, each reaction 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 a person skilled in the art, such as a pump for the withdrawal of the liquid fraction, a means capable of regulating the flow rate of the withdrawn liquid fraction, or also a pipe for bleeding off at least a portion of the liquid fraction.
Preferably, the means for withdrawal of the liquid phase of the reaction medium from the chamber of the reactor is a pipe.
The heat exchanger(s) incorporated in the recirculation loop(s) make(s) possible good homogenization of the concentrations within each reaction zone and make it possible to control the temperature of the liquid phase of the reaction medium within the chamber.
The withdrawal means make it possible to send the withdrawn liquid to the heat exchanger. Thus, the heat produced by the reaction is removed and the withdrawn liquid is cooled in order to be introduced into the chamber via the introduction means.
For each reaction zone comprising a recirculation loop, the withdrawal of liquid from a given reaction zone is carried out starting from a point located below the point of introduction of the cooled liquid into said zone. For a given reaction zone, the withdrawal is preferably carried out in the lower part of the reaction zone.
For each reaction zone comprising a recirculation loop, the introduction of the cooled liquid into said reaction zone is carried out starting from a point located above the liquid withdrawal point. For a given reaction zone, the introduction is preferably carried out in the upper part of said zone.
For the heat exchanger of the final reaction zone Zn, in the direction of flow of the liquid phase and of the gas phase, the introduction of the cooled liquid is preferably carried out, into the gas phase, by any means known to a person skilled in the art.
For the heat exchanger of the first reaction zone Z1, in the direction of flow of the liquid phase and of the gas phase, the withdrawal is preferably carried out under the level of introduction of the olefin and preferentially in the bottom of the reaction chamber.
The withdrawal is carried out by any means capable of carrying out the withdrawal and preferably by using a pump.
The reaction mixture of said chamber is withdrawn by admission means under the control of the liquid level, so as to keep the latter constant. The admission means are any means well known to a person skilled in the art, such as a valve.
Advantageously, carrying out the cooling of the reaction medium via the recirculation loop also makes it possible to carry out the stirring of the medium and thus to homogenize the concentrations of the reactive entities throughout the liquid volume of the reaction chamber.
One advantage of the present invention is thus that of making it possible to achieve selectivities for linear olefins and preferably for linear α-olefins which are superior to those achieved with a reactor according to the prior art comprising only a single reaction chamber, this being obtained while retaining a high level of conversion into linear olefins and preferably into linear α-olefins.
According to the invention, the gas/liquid reactor D comprises a means for introduction 3 of the olefin, preferably located in the lower part of the reaction chamber, more particularly in the bottom of said chamber.
Preferably, the means for introduction of the olefin 3 is chosen from a pipe, a network of pipes, a multitubular distributor, a perforated plate or any other means known to a person skilled in the art.
Preferably, a gas distributor, which is a device which makes it possible to disperse the gas phase uniformly over the entire liquid section, is positioned at the end of the introduction means 3 within the chamber of the reactor. Said device comprises a network of perforated pipes, the diameter of the orifices of which is between 1 and 12 mm, preferably between 3 and 10 mm, in order to form ethylene bubbles in the liquid of millimetric size.
According to the invention, the compartmentalized gas/liquid reactor D comprises a means for introduction 4 of the catalytic system.
Preferably, the means for introduction of the catalytic system 4 is located in the lower part of the reaction chamber and preferably in the bottom of said chamber.
The means for introduction of the catalytic system 4 is chosen from any means known to a person skilled in the art and is preferably a pipe.
In the embodiment where the catalytic system is employed in the presence of a solvent or of a mixture of solvents, said solvent is introduced by an introduction means located in the lower part of the reaction chamber, preferably in the bottom of said chamber.
In one embodiment, the solvent can be introduced in one or more recirculation loops.
The process according to the invention makes it possible to obtain linear olefins and in particular linear α-olefins by bringing olefin(s) and a catalytic system into contact, optionally in the presence of an additive and/or of a solvent, and by the use of said compartmentalized gas/liquid reactor.
The oligomerization process is carried out at a pressure between 1.0 and 10.0 MPa, preferably between 2.0 and 8.0 MPa, more preferably between 4.0 and 8.0 MPa and more particularly between 6.0 and 8.0 MPa. The temperature is between 0° C. and 200° C., preferably between 30° C. and 180° C., more preferably between 30° C. and 150° C. and more preferably still between 40° C. and 140° C.
The residence time of the reaction medium in the reaction chamber is, on average, between 2 and 400 minutes, preferentially between 20 and 150 minutes, preferably between 30 and 120 minutes. The residence time of the reaction medium within each compartment is, on average, between 1 and 30 minutes, preferably between 5 and 20 minutes and more preferably still between 5 and 15 minutes.
The process according to the invention comprises a stage a) of introduction of the olefin and of the catalytic system comprising at least one metal precursor and at least one activating agent into the liquid phase of the gas/liquid reactor D.
The process according to the invention can comprise the introduction of olefin or of a mixture of olefins. Preferably, the olefin is ethylene.
The olefin is introduced by dispersion in the liquid phase of the compartmentalized gas/liquid reactor, preferably in the lower part of the compartmentalized gas/liquid reactor, more preferably in the compartment Z1 and more particularly in the bottom of the reaction chamber.
The olefin can be introduced into each reaction zone of the chamber of the compartmentalized gas/liquid reactor, more preferably into the reaction zones located in the lower part of said chamber. More particularly, when the olefin is introduced into a reaction zone, the introduction is carried out in the lower part of said zone.
In one embodiment, the olefin can be introduced in one or more recirculation loops.
Preferably, the olefin is introduced by a means capable of producing said dispersion uniformly over the entire section of the reaction chamber. Preferably, the dispersion means is chosen from a distributing system with a homogeneous distribution of the points for introduction of the olefin over the entire section of said chamber.
The olefin is introduced by at least one means for admission under the control of the pressure, which keeps the latter constant in the reactor. The admission means is any means well known to a person skilled in the art, such as a valve.
Preferably, the olefin is introduced at a flow rate between 1 and 200 t/h, preferably between 3 and 150 t/h, preferably between 5 and 100 t/h and preferably between 5 and 50 t/h.
According to a specific embodiment of the invention, a stream of gaseous hydrogen can also be introduced into the reaction chamber, with a flow rate representing from 0.2% to 1.0% by weight of the flow rate of olefin introduced. Preferably, the stream of gaseous hydrogen is introduced by the means employed for the introduction of the olefin.
According to one embodiment, the catalytic oligomerization reaction is carried out continuously and in homogeneous catalysis, in the absence of support. The olefin can be introduced just as easily via the means for introduction of the catalytic system as independently.
Preferably, the velocity of the olefin at the outlet of the orifices is between 1 and 30 m/s. Its superficial velocity (gas volumetric velocity divided by the section of the gas/liquid reactor) is between 0.5 and 10 cm/s and preferably between 1 and 8 cm/s.
According to one embodiment, the catalytic system is introduced into the lower part of the compartmentalized gas/liquid reactor, more preferably into the compartment Z1 and more particularly into the bottom of the reaction chamber.
In one embodiment, the catalytic system can be introduced in one or more recirculation loops.
Any catalytic system known to a person skilled in the art and capable of being employed in the dimerization, trimerization or tetramerization processes and more generally in the oligomerization processes according to the invention comes within the field of the invention. Said catalytic systems and also their implementations are described in particular in the applications FR 2 984 311, FR 2 552 079, FR 3 019 064, FR 3 023 183, FR 3 042 989 or also in the application FR 3 045 414.
Preferably, the catalytic systems comprise, preferably consist of:
The metal precursor used in the catalytic system is chosen from compounds based on nickel, on titanium or on chromium.
In one embodiment, the metal precursor is based on nickel and preferably comprises nickel with a (+II) oxidation state. 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, π-allylnickel(II) chloride, π-allylnickel(II) bromide, methallylnickel(II) chloride dimer, η3-allylnickel(II) hexafluorophosphate, η3-methallylnickel(II) hexafluorophosphate and nickel(II) 1,5-cyclooctadienyl, in their hydrated or nonhydrated form, taken alone or as a mixture.
In a second embodiment, the metal precursor is based on titanium and preferably comprises a titanium aryloxy or alkoxy compound.
The titanium alkoxy compound advantageously corresponds to the general formula [Ti(OR)4] in which R is a linear or branched alkyl radical. Mention may be made, among the preferred alkoxy radicals, as nonlimiting examples, of tetraethoxy, tetraisopropoxy, tetra(n-butoxy) and tetra(2-ethylhexyloxy).
The titanium aryloxy compound advantageously corresponds to the general formula [Ti(OR′)4] in which R′ is an aryl radical substituted or unsubstituted by alkyl or aryl groups. The R′ radical can comprise heteroatom-based substituents. The preferred aryloxy radicals are chosen 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)-6-phenylphenoxy, 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, the biphenoxy radical, binaphthoxy or 1,8-naphthalenedioxy.
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 can comprise one or more identical or different anions, such as, for example, halides, carboxylates, acetylacetonates or 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 or Cr(acetate)3.
The concentration of nickel, of titanium or of chromium is between 0.01 and 300.0 ppm by weight of atomic metal, with respect 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 and more preferentially still between 1.0 and 20.0 ppm by weight of atomic metal, with respect to the reaction mass.
Whatever the metal precursor, the catalytic system additionally 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), diethylethoxyaluminum (Et2AlOEt), methylaluminoxane (MAO), ethylaluminoxane and modified methylaluminoxanes (MMAO).
Optionally, the catalytic system comprises one or more additives.
When the catalytic system is based on nickel, the additive is chosen from:
in which:
When the catalytic system is based on titanium, the additive is chosen 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, taken alone or as a mixture.
When the catalytic system is based on chromium, the additive is chosen from:
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-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. The two aryloxy radicals can be carried by one and the same molecule, such as, for example, 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-di(tert-butyl)-6-phenylphenoxy.
In another embodiment according to the invention, the catalytic system optionally comprises one or more solvents.
The solvent is chosen from the group formed by aliphatic and cycloaliphatic hydrocarbons, such as hexane, cyclohexane, heptane, butane or isobutane.
Preferably, the solvent used is cyclohexane.
Stage b) of Bringing the Olefin and the Catalytic System into Contact
The olefin and the catalytic system are brought into contact in each reaction zone Z1, Z2, . . . , Zn. This time over which the olefin and the catalytic system are brought into contact in each reaction zone Z1, Z2, . . . , Zn is between 0.5 and 30 seconds, preferably between 1 and 20 seconds and more preferably still between 1 and 15 seconds.
The process according to the invention comprises a stage c) of cooling the reaction medium. The reaction medium present within the reaction chamber of the compartmentalized gas/liquid reactor is cooled by means of at least one heat exchanger.
As the reaction is exothermic, it is necessary to remove the heat produced by the reaction by cooling the reaction medium in order to control the temperature in the whole of the chamber of the reactor and thus to make possible the progression of the reaction.
Preferably, said stage consisting in cooling the reaction medium is carried out by the presence of at least one heat exchanger(s), inside or outside the chamber of the reactor, and preferably located inside. More preferably, a single heat exchanger is used and placed inside the chamber of the reactor.
The presence of at least one heat exchanger(s), in which a cooling liquid circulates, advantageously makes it possible to reduce the temperature of the reaction medium by 1.0° C. to 11.0° C., preferably by 2.0° C. to 10.0° C., preferably by 3.0° C. to 9.0° C. Preferably, the cooling liquid circulates cocurrentwise with respect to the reaction medium.
Advantageously, the cooling of the reaction medium makes it possible to keep the temperature of the reaction medium within the desired temperature ranges. Any type of heat exchanger known to a person skilled in the art which makes it possible to carry out said process can be used.
The withdrawal means make it possible, by virtue of a liquid recirculation pump, to send a fraction of the withdrawn liquid phase of the reaction medium to the heat exchanger. Thus, the heat produced by the reaction is removed and the withdrawn liquid is cooled in order to be introduced into said chamber via the introduction means.
For each recirculation loop, the withdrawal of the liquid phase of the reaction medium is carried out starting from a point located below the point of introduction of the cooled liquid into said chamber. For a given reaction zone, the withdrawal is preferably carried out in the lower part of the reaction zone.
For the first reaction zone Z1, in the direction of flow of the liquid phase and of the gas phase, the withdrawal is preferably carried out under the level of introduction of the olefin and preferentially in the bottom of the chamber.
The withdrawal is carried out by any means capable of carrying out the withdrawal and preferably by using a pump.
The liquid phase of the reaction medium of the chamber of the reactor is withdrawn by admission means under the control of the liquid level, so as to keep the latter constant. The admission means are any means well known to a person skilled in the art, such as a valve.
Preferably, the withdrawal flow rate is between 500 and 12 000 t/h and preferably between 800 and 8500 t/h. The withdrawal flow rate is regulated in order to maintain a constant liquid level in the reaction chamber.
For each recirculation loop, the introduction of the cooled liquid into the reaction chamber is carried out starting from a point located above the liquid withdrawal point. For a given reaction zone, the introduction is preferably carried out in the upper part of said reaction zone.
For the final reaction zone Zn of the series, in the direction of flow of the liquid phase and of the gas phase, the introduction is preferably carried out into the gas phase and by any means known to a person skilled in the art. Preferably, the flow rate for introduction of the cooled liquid into the reaction chamber is between 500 and 12 000 t/h and preferably between 800 and 8500 t/h.
Advantageously, carrying out the cooling of the reaction medium via the recirculation loop also makes it possible to carry out the stirring of the medium and thus to homogenize the concentrations of the reactive entities throughout the liquid volume of the chamber of the reactor.
The process according to the invention comprises a stage d) of recovery of a liquid reaction effluent, in the upper part of the reaction chamber of the reactor, preferably at the top of said chamber. The reaction effluent comprises the desired products, such as linear olefins and more particularly linear α-olefins, the reactants of the reaction (the catalytic system and potentially the olefin introduced) and optionally the solvent and/or the additive.
The catalytic system is advantageously deactivated continuously by any usual means known to a person skilled in the art and then the products resulting from the reaction, and also the solvent, are separated, for example by distillation. The residues of the catalytic system included in a heavy fraction can be incinerated. The olefin which has not been converted can be recycled.
The products resulting from the reaction are preferably linear α-olefins, such as linear olefins comprising from 4 to 12 carbon atoms, preferably from 4 to 8 carbon atoms. Preferably, the linear α-olefins are chosen from but-1-ene, hex-1-ene or oct-1-ene.
On referring to the curve of
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.
The entire disclosures of all applications, patents and publications, cited herein and of corresponding French application No. 18/58.608, filed Sep. 21, 2018, are incorporated by reference herein.
The examples below illustrate the invention without limiting the scope thereof.
Example 1 illustrates the reference case corresponding to the
A mixture of chromium tris(2-ethylhexanoate) (denoted Cr(2-EH)3), of bis(2-(tert-butyl)-6-phenylphenoxy)magnesium and of dibutyl ether (in a 1/1/2 molar ratio) at 0.3 mol/l in a cyclohexane/heptane mixture is prepared in accordance with the protocol described in the patent application FR 3 019 064.
The volumetric productivity of this reactor is 178 kg of α-olefin produced per hour and per m3 of reaction volume.
The performance qualities of this reactor make it possible to convert 50.80% of the injected ethylene and to achieve a selectivity of 89.50% for the desired α-olefin, for a content by weight of solvent of 3.7. Said content of solvent is calculated as the ratio by weight of the flow rate of injected solvent to the flow rate of injected gaseous ethylene.
Example 2 illustrates the case corresponding to the curve of
The reaction chamber of the reactor measures 3.41 m in diameter, with a liquid height of 20.48 m and a working volume of 188 m3. The H/W ratio is 6.0.
The catalytic composition used is identical to that used in example 1.
The volumetric productivity of this reactor is 166 kg of α-olefin produced per hour and per m3 of reaction volume.
The performance qualities of this reactor make it possible to convert 63.98% of the injected ethylene and to achieve a selectivity of 89.77% for the desired α-olefin, for a content by weight of solvent of 3.37. Said content of solvent is calculated as the ratio by weight of the flow rate of injected solvent to the flow rate of injected gaseous ethylene.
For one and the same selectivity for desired α-olefin as in the preceding example, the reactor according to the invention makes it possible to significantly improve the conversion of the ethylene: more than 25% extra conversion.
The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18/58.608 | Sep 2018 | FR | national |
