Process for separation of olefins and paraffins

Abstract

The present disclosure relates to a process for separation of a mixture of olefins and paraffins. The olefins are transformed into dihalides, so that the dihalides and the paraffins can be separated. The dihalides are recovered, and subjected to a reductive elimination with one or more transition metals so that an effluent comprising the olefins and one or more metal halides is recovered. The one or more metal halides are recovered and subjected to an electrochemical reaction, so that the metal is recovered and also the halogen.

Description

[0001] Process for separation of olefins and paraffins

[0002] Field of the disclosure

[0003] The present disclosure relates to a process of separation of a mixture of olefins and paraffins.

[0004] Technical background

[0005] Olefin-paraffin separations are some of the most energy-intensive industrial processes. Various techniques are available, like distillations, separations with solid membranes based on zeolites or polymers or separations based on molecular sieving as described in the review of J. Hou (J. Mater. Chem. A., 2019, 7, 23483-23511). In particular, distillations are costly and consume a lot of energy.

[0006] In parallel, and while feedstocks become constrained, the demand for key olefins, such as ethylene and propylene, is projected to continue growing. Therefore, there is a need to find cost-effective and energy-efficient process for separating olefins from a mixture of olefins and paraffins.

[0007] Summary

[0008] According to the first aspect, the present disclosure relates to a process for separation of a mixture of olefins and paraffins, said process is remarkable in that it comprises the following steps: a) providing a first stream comprising a mixture of one or more olefins and one or more paraffins; b) providing a second stream comprising one or more halogens; c) contacting the first stream and the second stream under first operating conditions to produce a first effluent comprising one or more dihalides, one or more unreacted halogens, and one or more paraffins; d) separating from said first effluent a first liquid stream and a gaseous stream, wherein said first liquid stream comprises one or more dihalides and one or more unreacted halogens and said gaseous stream comprises one or more paraffins; e) recovering the first liquid stream from said first effluent; f) contacting the first liquid stream recovered at step (e) with one or more transition metals under second operating conditions comprising reductive elimination conditions so as to produce a second effluent comprising one or more olefins and one or more metal halides; g) separating from said second effluent the one or more olefins so as to recover a second liquid stream comprising said one or more metal halides; h) electrolyzing the one or more metal halides from the second liquid stream recovered at step (g) so as to recover at least said halogen.

[0009] Surprisingly, the present disclosure discloses a process enabling the separation of one or more olefins from a mixture comprising one or more olefins and one or more paraffins using dihalides intermediates and subsequent electrochemical recovery of the halogens that was necessary to form the dihalides intermediates. Halogenation of the olefins, and in particular bishalogenation, produces dihalides intermediates which have a higher boiling point than the corresponding olefins. The first effluent comprising one or more dihalides and one or more paraffins can thus be subjected to a separation step since the dihalides intermediates have a higher boiling point than the corresponding one or more paraffins. The final steps of the process of the present disclosure are an alkene synthesis by reductive elimination, implying the reaction between the bromide moieties and one or more transition metals. Such process presents lower capital and operating investments compared to existing analogues, and also has the advantages of preventing the loss of olefin streams and of avoiding the implementation of cumbersome debottleneck processes. Greenhouse gas (GHG) emissions are also minimized since the process uses an electrochemical cell to revert from the dihalides intermediates to the corresponding one or more olefins.

[0010] Advantageously, said process further comprises the additional step (i) of directing the halogen recovered at step (h) to the second stream provided at step (b).

[0011] It is also advantageous that the consumption, dictated by loss and mitigated by adding a makeup of halogens can also be minimized since the additional step (i) of the process of the present disclosure allow its recycling. This thus contributes to lower capital and operating investments compared to existing analogues.

[0012] Advantageously, the first stream comprises a mixture of one or more olefins and one or more paraffins that have the same number of carbon atoms.

[0013] Advantageously, the one or more halogens are selected from bromine, chlorine, fluorine, or any mixtures thereof. With preference, the halogen is bromine (Br2).

[0014] Advantageously, said one or more transition metals are selected from Zn, Fe, Cd, or any mixture thereof. With preference, the transition metal is Zn.

[0015] Advantageously, the first operating conditions comprise a molar ratio between the one or more olefins and the one or more halogens inferior to 1 , preferably a molar ratio of at most 0.99, more preferably of at most 0.95, even more preferably of at most 0.90. Advantageously, the mass ratio between the one or more olefins and the one or more paraffins of the mixture of the first stream is ranging between 95 / 5 and 5 / 95, or between 90 / 10 and 10 / 90, or between 80 / 20 and 20 / 80, or between 70 / 30 and 30 / 70, or between 60 / 40 and 40 / 60.

[0016] Advantageously, the molar ratio between the one or more transition metals and the one or more dihalides is at least 1.1 , preferably at least 2.0, more preferably at least 2.1 .

[0017] Advantageously, the first operating conditions of step (c) comprise carrying out the step (c) in the absence of UV light.

[0018] Advantageously, step (d) is carried out by distillation.

[0019] Advantageously, the second operating conditions of step (f) comprises a temperature between 10 to 120°C, preferably between 15 and 70°C, more preferably between 20 and 60°C.

[0020] Advantageously, the second operating conditions of step (f) comprises a pressure between 0.1 MPa and 7 MPa, preferably between 0.5 MPa and 5 MPa, more preferably between 1 MPa and 4 MPa, even more preferably between 1.5 MPa and 3 MPa.

[0021] Advantageously, in a first alternative, said step (h) comprises providing an electrochemical cell with an anode and a cathode; and said electrochemical cell further comprises a separation membrane between the anode and the cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode.

[0022] Advantageously, in a second alternative, said step (h) comprises providing an electrochemical cell with an anode and a cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode.

[0023] Advantageously, the step (h) of electrolyzing is carried out at a potential ranging between 1.0 V and 3.0 V, preferably between 1.2 V and 2.5 V, more preferably between 1.3 V and 2.1 V.

[0024] Advantageously, the step (h) of electrolyzing is carried out at a current density ranging between 100 A / m2and 5000 A / m2, 200 A / m2and 3000 A / m2, 500 A / m2and 2000 A / m2.

[0025] Advantageously, step (h) is carried out in the presence of one or more quaternary ammonium salts.

[0026] Description of the figures

[0027] Figure 1 : Scheme of a zinc bromine battery. Figure 2: ATR FTIR (Attenuated Total Reflectance Fourier Transform Infrared) spectrum showing the evolution of the 1 ,2-dibromopropane during the reaction.

[0028] Figure 3: Bubble column reactor used for transforming propylene into 1 ,2-dibromopropane.

[0029] Figure 4: Conversion of propylene into 1 ,2-dibromopropane monitored by microGC (Gas Chromatography).

[0030] Detailed description

[0031] For the purpose of the disclosure, the following definitions are given.

[0032] The terms "comprising", "comprises" and "comprised of' as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of" also include the term “consisting of”.

[0033] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g., 1 to 5 includes 1 , 2, 3, 4, 5 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the recited endpoint values themselves (e.g., from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0034] The term “transition metal” refers to an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell (IIIPAC definition). According to this definition, the transition metals are Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Ac, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, and Cn. The metals Ga, In, Sn, TI, Pb and Bi are considered as “post-transition” metals.

[0035] The reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The particular features, structures, characteristics or embodiments may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments, as would be understood by those in the art.

[0036] The present disclosure relates to a process for separation of a mixture of olefins and paraffins. Said process is remarkable in that it comprises the following steps: a) providing a first stream comprising a mixture of one or more olefins and one or more paraffins; b) providing a second stream comprising one or more halogens; c) contacting the first stream and the second stream under first operating conditions to produce a first effluent comprising one or more dihalides, one or more unreacted halogens, and one or more paraffins; d) separating from said first effluent a first liquid stream and a gaseous stream, wherein said first liquid stream comprises one or more dihalides and one or more unreacted halogens and said gaseous stream comprises one or more paraffins; e) recovering the first liquid stream from said first effluent; f) contacting the first liquid stream recovered at step (e) with one or more transition metals under second operating conditions comprising reductive elimination conditions so as to produce a second effluent comprising one or more olefins and one or more metal halides; g) separating from said second effluent the one or more olefins so as to recover a second liquid stream comprising said one or more metal halides; h) electrolyzing the one or more metal halides from the second liquid stream recovered at step (g) so as to recover at least said halogen.

[0037] The production of a first effluent comprising among others one or more dihalides allows to create a difference between the boiling point of the one or more paraffins and the boiling point of the one or more dihalides, making subsequently their separation easier. As the one or more dihalides can thus be converted back into the corresponding one or more olefins, the separation of mixture comprising those olefins and paraffins is enhanced. In addition, electrochemistry allows the regeneration of both the one or more transition metals and the one or more halogens that have been used in the process, so that the whole process presents lower capital and operating investments compared to existing analogues. Also, such process prevents the waste of olefins streams and avoid the implementation of cumbersome debottleneck processes.

[0038] Advantageously, said process further comprises the additional step (i) of directing the halogen recovered at step (h) to the second stream provided at step (b). This optional additional step allows for the recycling of the halogen. When such step is carried out, it further lowers the capital and operating investments compared to existing analogues separation processes. For example, the one or more olefins are selected from ethylene, propylene, butenes, pentenes, hexenes, heptenes, octenes or a mixture thereof, preferably from ethylene, propylene, butenes, pentenes or a mixture thereof. More preferably, the one or more olefins are ethylene and / or propylene.

[0039] For example, the one or more paraffins are selected from ethane, propane, butane, pentane, hexane, heptane, octane, or a mixture thereof, preferably from ethane, propane, butane, pentane or a mixture thereof.

[0040] For example, the first stream comprises a mixture of one or more olefins and one or more paraffins that have the same number of carbon atoms. Thus, for example, the first stream comprises a mixture of ethylene, ethane, propylene, propane, butenes, butane, pentene and pentane, or a mixture of ethylene, ethane, propylene and propane.

[0041] For example, the mass ratio between the one or more olefins and the one or more paraffins of the mixture of the first stream is ranging between 95 / 5 and 5 / 95, or between 90 / 10 and 10 / 90, or between 80 / 20 and 20 / 80, or between 70 / 30 and 30 / 70, or between 60 / 40 and 40 / 60.

[0042] For example, the one or more halogens are selected from bromine, chlorine, fluorine, or any mixtures thereof. With preference, the halogen is bromine (Br2).

[0043] Composition of said second stream comprising one or more halogens

[0044] Said second stream comprises at least one halogen, water, and at least one ionic compound.

[0045] For example, said one ionic compound is a transition metal halide, alkali metal halide, alkali earth metal halide, or organic ionic halide.

[0046] For example, said transition metal is one of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), lanthane (La), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg).

[0047] For example, said alkali metal is one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

[0048] For example, said alkali earth metal is one of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0049] In certain embodiments of the present disclosure, the halide anion applied in ionic compound, and free halogen (dihalogen) present in said second stream are the same halogen element. In certain embodiments of the present disclosure, the halide anion applied in ionic compound, and free halogen (dihalogen) present in said second stream are different halogen element.

[0050] For example, said organic ionic halide is a compound known as an “ionic liquid”, wherein said ionic liquid comprises, preferably consists of, a compound (e.g., a salt) comprising a halide anion and an organic cation, wherein said organic cation is a compound having at least one heteroatom selected from the group consisting of N, O, P, and S.

[0051] For the purpose of the present disclosure, the term "ionic liquid” (“IL”) is intended to denote a compound, preferably a salt, formed by the combination of a positively charged organic cation and a negatively charged anion in the liquid state at temperatures below 200°C, preferably below 150°C, particularly preferably below 100°C.

[0052] Preferably, one ionic liquid (IL) consists of, a halide anion, and an organic compound as cation, i.e., an organic cation. In particular, such organic cation (organic compound) is a compound that has at least one heteroatom selected from the group consisting of N, O, P, and S.

[0053] The cations associated with ILs may be structurally diverse. For instance, in certain embodiments, cations associated with ILs contain one or more nitrogen atoms that are part of a ring structure and can be converted to a quaternary ammonium. Examples of these cations include pyridinium, pyridazinium, pyrimidinium, pyrazinium, imidazolium, pyrazolium, oxazolium, triazolium, thiazolium, piperidinium, pyrrolidinium, quinolinium, and isoquinolinium. The anions associated with ILs can also be structurally diverse and can have a significant impact on the solubility of the ILs in different media. ILs containing hydrophilic anions such as chloride are completely miscible in water.

[0054] In accordance with the present disclosure, said ionic liquid contains a (negatively charged) halide anion. Said halide anion in said ionic liquid may be selected from the group consisting of a bromide anion, a chloride anion, a fluoride anion, and an iodide anion. In certain preferred embodiments, said halide anion in said ionic liquid is a bromide anion.

[0055] In certain embodiments of the present process, an ionic liquid is applied wherein said organic cation is selected from the group consisting of imidazolium, imidazolinium, ammonium, aminium, pyridinium, pyrrolidinium, piperidinium, pyridazinium, pyrimidinium, pyrazinium, pyrazolium, pyrazolinium, thiazolium, triazolium, sulfonium, phosphonium, oxonium, guanidium, cholinium, isouronium, and isothiouronium cations.

[0056] Suitable examples of organic cations include but are not limited to for instance 1-butyl-3- methyl-imidazolium, 2,3-dimethyl-1-butyl-imidazolium, 1 ,3-diethoxyimidazolium, 1 ,3- dihydroxyimidazolium, 1-benzyl-3-methyl-imidazolium, 1-methyloxymethyl-3-methyl- imidazolium, 1-methyl-3-propylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1-pentyl-3- methyl-imidazolium, 1-methyl-3-(3,3,4,4,5,5,6,6,6-nonafluorohexyl)imidazolium, 1 -heptyl-3- methyl-imidazolium, 1-decyl-3-methyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1,2- dimethyl-3-ethyl-imidazolium, N-heptyl-N-methylpyrrolidinium, 1-methyl-3-

[0057] (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)imidazolium, 1-butyronitrile-3-methyl-imidazolium, 1-butyronitrile-2,3-dimethyl-imidazolium, 1-(2-hydroxyethyl)-3-methyl-imidazolium, 1-hexyl-3- methyl-imidazolium, 2,3-dimethyl-1-hexyl-imidazolium, 1,3-dimethyl-imidazolium, 1-hydroxy- propyl-3-methylimidazolium, 1-nonyl-3-methyl-imidazolium, 1-octyl-3-methyl-imidazolium, 1- butyl-2-methyl-pyridinium, 1-benzyl-2-methyl-pyridinium, 1-butyl-3-methyl-pyridinium, 1- benzyl-3-methyl-pyridinium, 1-octyl-3-methyl-pyridinium, 1-benzyl-4-methyl-pyridinium, 1- butyl-nicotinic acid butyl ester, bis(2-hydroxyethyl)ammonium, 1-butyl-4-methyl-pyridinium, 1- butyl-1-methyl-pyrrolidinium, butylpyridinium, 1-benzyl-1-methyl-pyrrolidinium, 1-benzyl-4- methyl-pyridinium, 1-propyl-3-methyl-pyridinium, N-propyl-N-methyl-pyrrolidinium, N-pentyl-N- methyl-pyrrolidinium, 2-hydroxyethyltrimethylammonium, N,N-dimethylformamide, 1-ethyl-4- methyl-pyridinium, ethyl-pyridinium, S-Ethyl-N,N,N',N'-tetramethylisothiouronium, guanidinium, monoethanolaminium, 2-hydroxyethanaminium, 2-hydroxy-N-(2-hydroxyethyl)- N-methylethanaminium, 1-hexyl-3-methylpyridinium, 1-hexyl-1-methylpyrrolidinium, hexylpyridinium, N-methyl-2-hydroxyethylammonium, [2-

[0058] (methacryloyloxy)ethyl]trimethylammonium, 2-[2-hydroxyethyl (methyl) amino] ethanol, monoethanolaminium, choline, propylcholinium, butylcholinium, octylcholinium, methyltrioctylammonium, ethyldimethylpropylammonium, N,N,N,N-trimethylbutylammonium, methyl-tributylammonium, tetrabutylammonium, N-nonyl-N-methyl-pyrrolidinium, 1-octyl-1- methyl-pyrrolidinium, triisobutyl-methyl-phosphonium, tertra-N-butylphosphonium, tributyl(tetradecyl)phosphonium, trihexyl(tetradecyl)phosphonium, N-(2- hydroxyethyl)pyridinium, tri-(2-hydroxy-ethyl)-ammonium, 1 ,1 ,3,3-tetramethyl-guanidium, (p- Vinylbenzyl)trimethyl-ammonium, tetraethylammonium, tetramethylammonium, pyrrolidinium, and tributylsulfonium.

[0059] In certain embodiments of the present process, an ionic liquid is applied wherein said organic cation is selected from the group consisting of imidazolium, ammonium, aminium, pyridinium, pyrrolidinium, phosphonium, oxonium, guanidium, cholinium, and isothiouronium cations.

[0060] In certain embodiments, particular preference is given to ionic liquids with an imidazolium cation.

[0061] In certain preferred embodiments, said organic cation is selected from the group consisting of an imidazolium cation of formula (I): formula (I) wherein each of R1, R2, R3, R4and R5is independently selected from hydrogen, or a group consisting of hydroxyl, alkyl, haloalkyl, heteroalkyl, heterocyclyl, cycloalkyl, alkyloxy, alkyloxyalkyl, aryl, heteroaryl, and aryloxy, and wherein each of said groups can be unsubstituted or substituted with one or more substituents each independently selected from the group consisting of halogen, nitro, oxo, -C(O)OH, amino, hydroxyl, alkyl, aryl, alkyloxy, aryloxy, mono-alkylamino, di-alkylamino, alkylthio, and cyano.

[0062] When describing the present disclosure, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.

[0063] Whenever the term “substituted” is used in the present disclosure, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using “substituted” is replaced with a selection from the indicated group, provided that the indicated atom’s normal valency is not exceeded, and that the substitution results in a chemically stable compound, / .e., a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture.

[0064] The term "alkyl" as a group or part of a group, refers to a hydrocarbyl group of formula CnH2n+i wherein n is a number greater than or equal to 1 . Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups of this disclosure comprise from 1 to 20 carbon atoms, preferably from 1 to 18 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, more preferably 1 , 2, 3, 4, 5, 6 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term “Ci-2oalkyl”, as a group or part of a group, refers to a hydrocarbyl group of formula -CnH2n+i wherein n is a number ranging from 1 to 20. Thus, for example, Ci- 2oalkyl groups include all linear, or branched alkyl groups having 1 to 20 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / -propyl, 2-methyl-ethyl, butyl and its isomers (e.g. n-butyl, / -butyl and f-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers, decyl and its isomers, undecyl and its isomers, dodecyl and its isomers, tridecyl and its isomers, tetradecyl and its isomers, pentadecyl and its isomers, hexadecyl and its isomers, heptadecyl and its isomers, octadecyl and its isomers, and the like. For example, Ci- alkyl includes all linear, or branched alkyl groups having 1 to 10 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / - propyl, 2-methyl-ethyl, butyl and its isomers (e.g. n-butyl, / -butyl, and f-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers, decyl and its isomers and the like. For example, Ci-ealkyl includes all linear, or branched alkyl groups having 1 to 6 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / -propyl, 2-methyl-ethyl, butyl and its isomers (e.g., n-butyl, / -butyl, and f-butyl); pentyl and its isomers, hexyl and its isomers. In some embodiments, non-limiting examples of alkyl groups include for instance methyl, ethyl, propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, 2,2-dimethyl-propyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3- pentyl, 2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl and dodecyl groups. When the suffix "ene" is used in conjunction with an alkyl group, i.e. “alkylene”, this is intended to mean the alkyl group as defined herein having two single bonds as points of attachment to other groups. Alkylene groups may be linear or branched and may be substituted as indicated herein. Non-limiting examples of alkylene groups include methylene (-CH2-), ethylene (-CH2- CH2-), methylmethylene (-CH(CH3)-), 1-methyl-ethylene (-CH(CH3)-CH2-), n-propylene (-CH2- CH2-CH2-), 2-methylpropylene (-CH2-CH(CH3)-CH2-), 3-methylpropylene (-CH2-CH2-CH(CH3)- ), n-butylene (-CH2-CH2-CH2-CH2-), 2-methylbutylene (-CH2-CH(CH3)-CH2-CH2-), 4- methylbutylene (-CH2-CH2-CH2-CH(CH3)-), pentylene and its chain isomers, hexylene and its chain isomers.

[0065] As used herein and unless otherwise stated, the term “halo” or “halogen”, as a group or part of a group, is generic for any atom selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At).

[0066] The term "haloalkyl" as a group or part of a group, refers to an alkyl group having the meaning as defined above wherein at least one hydrogen atom is replaced with a halogen as defined herein. Non-limiting examples of such haloalkyl groups include chloromethyl, 1 -bromoethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1 ,1 ,1 -trifluoroethyl and the like.

[0067] The term “aryl”, as a group or part of a group, refers to a polyunsaturated, aromatic hydrocarbyl group having a single ring (i.e. phenyl) or multiple aromatic rings fused together (e.g., naphthyl), or linked covalently, typically containing 5 to 18 atoms, wherein at least one ring is aromatic. The aromatic ring may optionally include one to two additional rings (either cycloalkyl, heterocyclyl or heteroaryl) fused thereto. Examples of suitable aryl include Cs-isaryl, or C5- i2aryl, or Cs- aryl, or C6-i2aryl, or Ce- aryl. Non-limiting examples of aryl comprise phenyl, biphenylyl, biphenylenyl, or 1-or 2-naphthanelyl; 1-, 2-, 3-, 4-, 5- or 6-tetralinyl (also known as “1 ,2,3,4-tetrahydronaphtalene); 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-azulenyl, 4-, 5-, 6 or 7-indenyl; 4- or 5-indanyl; 5-, 6-, 7- or 8-tetrahydronaphthyl; 1 ,2,3,4-tetrahydronaphthyl; and 1 ,4- dihydronaphthyl; 1-, 2-, 3-, 4- or 5-pyrenyl. When the suffix "ene" is used in conjunction with an aryl group, this is intended to mean the aryl group as defined herein having two single bonds as points of attachment to other groups.

[0068] The term “alkoxy" or “alkyloxy”, as a group or part of a group, refers to a group having the Formula -ORx1wherein Rx1is alkyl as defined herein above. Examples of suitable alkyloxy include Ci-2oalkyloxy, or Ci-isalkyloxy, or Ci-i2alkyloxy, or Ci-ealkyloxy. Non-limiting examples of suitable alkoxy include, but are not limited to methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, and hexyloxy.

[0069] The term “aryloxy”, as a group or part of a group, refers to a group having the formula -ORx2wherein Rx2is aryl as defined herein. Examples of suitable aryloxy include Cs-3oaryloxy, or Ce- soaryloxy, or C6-i2aryloxy,

[0070] The term “cycloalkyl”, as a group or part of a group, refers to a cyclic alkyl group, that is to say, a monovalent, saturated, hydrocarbyl group having 1 or more cyclic structure. Generally, cycloalkyl groups of this disclosure comprise from 3 to 20 carbon atoms, preferably from 3 to 12 carbon atoms, preferably from 3 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, or from 3 to 6 carbon atoms, or from 5 to 6 carbon atoms. Cycloalkyl includes all saturated hydrocarbon groups containing 1 or more rings, including monocyclic or bicyclic groups. The further rings of multi-ring cycloalkyls may be either fused, bridged and / or joined through one or more spiro atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term “C3-2ocycloalkyl”, a cyclic alkyl group comprising from 3 to 20 carbon atoms. For example, the term “Cs- cycloalkyl”, a cyclic alkyl group comprising from 3 to 10 carbon atoms. For example, the term “Cs-scycloalkyl”, a cyclic alkyl group comprising from 3 to 8 carbon atoms. For example, the term “Cs-ecycloalkyl”, a cyclic alkyl group comprising from 3 to 6 carbon atoms. Examples of C3-i2cycloalkyl groups include but are not limited to adamantly, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, 1 ,2-diethylcyclohexyl, bicyclo[2.2.1]heptan-2yl, (1S,4R)-norbornan-2-yl, (1 R,4R)-norbornan-2-yl, (1S,4S)-norbornan- 2-yl, (1 R,4S)-norbornan-2-yl.

[0071] As used herein, the term “heteroatom” refers to a non-carbon atom, preferably an atom is selected from the group consisting of N, O, S, and P. In certain embodiments, the term “heteroatom” refers to a non-carbon atom selected from the group consisting of N, O and S. In certain embodiments, the term “heteroatom” refers to a non-carbon atom selected from the group consisting of N and O. The term “heterocyclyl”, as a group or part of a group, refers to non-aromatic, fully saturated or partially unsaturated ring system of 3 to 18 atoms including at least one N, O, S, or P (for example, 3 to 7 member monocyclic, 7 to 11 member bicyclic, or comprising a total of 3 to 10 ring atoms) wherein at least one ring is a heterocyclyl and wherein said ring may be fused to an aryl, cycloalkyl, heteroaryl and / or heterocyclyl ring. Each ring of the heterocyclyl may have 1 , 2, 3 or 4 heteroatoms selected from N, P, O or S, where the N and S heteroatoms may optionally be oxidized, and the N heteroatoms may optionally be quaternized; and wherein at least one carbon atom of heterocyclyl can be oxidized to form at least one C=O. The heterocyclic may be attached at any heteroatom or carbon atom of the ring or ring system, where valence allows. The rings of multi-ring heterocyclyls may be fused, bridged and / or joined through one or more spiro atoms.

[0072] The term “heteroaryl”, as a group or part of a group, refers to an aromatic ring system of 5 to 30 atoms including at least one N, O, S, or P, containing 1 or more rings, such as 1 or 2 or 3 or 4 rings, which can be fused together or linked covalently, each ring typically containing 5 to 6 atoms; at least one of said ring is aromatic, where the N and S heteroatoms may optionally be oxidized and the N heteroatoms may optionally be quaternized, and wherein at least one carbon atom of said heteroaryl can be oxidized to form at least one C=O. Such rings may be fused to an aryl, cycloalkyl, heteroaryl and / or heterocyclyl ring.

[0073] The term “heteroalkyl” as used herein refers to an alkyl wherein one or more carbon atoms are replaced by one or more atoms independently selected from the group consisting of O, P, N and S, with the proviso that said chain may not contain two adjacent O atoms or two adjacent S atoms. Said one or more atoms replacing said carbon atoms may be positioned at the beginning of the hydrocarbon chain, in the hydrocarbon chain or at the end of the hydrocarbon chain. This means that one or more -CH3 of said alkyl can be replaced by -NH2 and / or that one or more -CH2- of said alkyl can be replaced by -NH-, -O- or -S-. In some embodiments the term heteroalkyl encompasses an alkyl which comprises one or more heteroatoms in the hydrocarbon chain, said heteroatoms being selected from the atoms consisting of O, S, P, and N, whereas the heteroatoms may be positioned at the beginning of the hydrocarbon chain, in the hydrocarbon chain or at the end of the hydrocarbon chain. The S atoms in said chains may be optionally oxidized with one or two oxygen atoms, to afford sulfoxides and sulfones, respectively. Furthermore, the heteroalkyl groups in the compounds of the present disclosure can contain an oxo or thio group at any carbon or heteroatom that will result in a stable compound. Exemplary heteroalkyl groups include, but are not limited to, alcohols, alkyl ethers, primary, secondary, and tertiary alkyl amines, amides, ketones, esters, alkyl sulfides, and alkyl sulfones. The term heteroalkyl thus comprises but is not limited to -Rx4-S-; -Rx4-O-, -Rx4-N(Rx3)2 -O-Rx1, -NRx3-Rx1, -Rx4-O-Rx1, -O-Rx4-S-Rx1, -S-Rx4-, -O-Rx4-NRx3Rx1, -NRx3-Rx4-S-Rx1, -Rx4- NRx3-Rx1, -NRx3Rx4-S-Rx1, -S-Rx1, wherein Rx4is alkylene, Rx1is alkyl, and Rx3is hydrogen or alkyl as defined herein. In particular embodiments, the term encompasses heteroCi-^alkyl, heteroCi-galkyl and heteroCi-ealkyl. In some embodiments heteroalkyl is selected from the group consisting of alkyloxy, alkyl-oxy-alkyl, (mono or di)alkylamino, (mono or di-)alkyl-amino- alkyl, alkylthio, and alkyl-thio-alkyl.

[0074] The term “alkylthio", as a group or part of a group, refers to a group having the formula -S- Rx1wherein Rx1is alkyl as defined herein above. Non-limiting examples of alkylthio groups include methylthio (-SCH3), ethylthio (-SCH2CH3), n-propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio, tert-butylthio, and the like.

[0075] The term “mono- or di-alkylamino”, as a group or part of a group, refers to a group of formula -N(Rx3)(Rx1) wherein Rx3is hydrogen or alkyl as defined herein, and Rx1is alkyl as defined herein. Thus, “alkylamino” include mono-alkyl amino group (e.g. mono-alkylamino group such as methylamino and ethylamino), and di-alkylamino group (e.g. di-alkylamino group such as dimethylamino and diethylamino). Non-limiting examples of suitable mono- alkylamino groups include mono-Ci-ealkylamino groups such as n-propylamino, isopropylamino, n-butylamino, i-butylamino, sec-butylamino, t-butylamino, pentylamino, n- hexylamino, and the like. Non limiting examples of suitable di-alkylamino groups include di-Ci- ealkylamino group such as dimethylamino and diethylamino, di-n-propylamino, di- / - propylamino, ethylmethylamino, methyl-n-propylamino, methyl- / -propylamino, n- butylmethylamino, / -butylmethylamino, f-butylmethylamino, ethyl-n-propylamino, ethyl- / - propylamino, n-butylethylamino, i-butylethylamino, f-butylethylamino, di-n-butylamino, di- / - butylamino, methylpentylamino, methylhexylamino, ethylpentylamino, ethylhexylamino, propylpentylamino, propylhexylamino, and the like.

[0076] The term “nitro” as used herein refers to -NO2.

[0077] The term “amino” refers to the group -NH2.

[0078] The term “cyano” as used herein refers to -CN.

[0079] The term “hydroxyl” or “hydroxy”, as a group or part of a group, refers to the group -OH.

[0080] The terms described above and others used in the specification are well understood to those skilled in the art.

[0081] In certain preferred embodiments, said organic cation is selected from the group consisting of an imidazolium cation of general formula (I) wherein each of R1, R2, R3, R4and R5is independently selected from hydrogen or an alkyl, cycloalkyl, alkyloxy, alkyloxyalkyl, aryl, and aryloxy group, wherein each of said groups can be unsubstituted or substituted with one or more substituents each independently selected from the group consisting of halogen, nitro, oxo, -C(0)0H, amino, hydroxyl, alkyl, aryl, alkyloxy, aryloxy, mono-alkylamino, di-alkylamino, alkylthio, and cyano.

[0082] In certain preferred embodiments, said organic cation is selected from the group consisting of an imidazolium cation of general formula (I) wherein each of R1, R2, R3, R4and R5is independently selected from hydrogen or an alkyl or an aryl group, wherein each of said groups can be unsubstituted or substituted with one or more substituents each independently selected from the group consisting of halogen, nitro, oxo, -C(O)OH, amino, hydroxyl, alkyl, aryl, alkyloxy, aryloxy, mono-alkylamino, di-alkylamino, alkylthio, and cyano.

[0083] In certain embodiments, said organic cation is selected from the group consisting of an imidazolium cation of general formula (I) wherein R2, R4and R5are hydrogen and R1and R3, are each independently selected from hydrogen or a group consisting of hydroxyl, alkyl, haloalkyl, heteroalkyl, heterocyclyl, cycloalkyl, alkyloxy, alkyloxyalkyl, aryl, heteroaryl, and aryloxy, and wherein each of said groups can be unsubstituted or substituted with one or more substituents each independently selected from the group consisting of halogen, nitro, oxo, - C(O)OH, amino, hydroxyl, alkyl, aryl, alkyloxy, aryloxy, mono-alkylamino, di-alkylamino, alkylthio, and cyano.

[0084] In certain preferred embodiments, said organic cation is selected from the group consisting of an imidazolium cation of formula (I), wherein each of R1and R3is independently selected from alkyl, wherein said alkyl group is optionally substituted with one or more substituents each independently selected from the group consisting of halogen, nitro, oxo, -C(O)OH, amino, hydroxyl, alkyl, aryl, alkyloxy, aryloxy, mono-alkylamino, di-alkylamino, alkylthio, and cyano.

[0085] Suitable imidazolium cations for use in an ionic liquid as applied in the present process may be selected from the group consisting of 1-butyl-3-methyl-imidazolium, 2,3-dimethyl-1-butyl- imidazolium, 1 ,3-diethoxyimidazolium, 1 ,3-dihydroxyimidazolium, 1-benzyl-3-methyl- imidazolium, 1-methyloxymethyl-3-methyl-imidazolium, 1-methyl-3-propyl-imidazolium, 1 ,2- dimethyl-3-propyl-imidazolium, 1-pentyl-3-methyl-imidazolium, 1-methyl-3-(3,3,4,4,5,5,6,6,6- nonafluorohexyl)imidazolium, 1-heptyl-3-methyl-imidazolium, 1-decyl-3-methyl-imidazolium, 1-ethyl-3-methyl-imidazolium, 1 ,2-dimethyl-3-ethyl-imidazolium, 1-methyl-3- (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)imidazolium, 1-butyronitrile-3-methyl-imidazolium, 1-butyronitrile-2,3-dimethyl-imidazolium, 1-(2-hydroxyethyl)-3-methyl-imidazolium, 1-hexyl-3- methyl-imidazolium, 2,3-dimethyl-1-hexyl-imidazolium, 1 ,3-dimethyl-imidazolium, 1-hydroxy- propyl-3-methylimidazolium, 1-nonyl-3-methyl-imidazolium, and 1-octyl-3-methyl-imidazolium.

[0086] Particularly suitable examples of ionic liquid used in the present process may for instance include 1-ethyl-3-methyl-imidazolium bromide, 1-propyl-3-methyl-imidazolium bromide, 1- butyl-3-methyl-imidazolium bromide, 1-pentyl-3-methyl-imidazolium bromide, 1-hexyl-3- methyl-imidazolium bromide, 1-heptyl-3-methyl-imidazolium bromide, and 1-octyl-3-methyl- imidazolium bromide.

[0087] Formation of the dihalide intermediates and removal of the one or more paraffins

[0088] For example, the first operating conditions of step (c) comprise carrying out the step (c) in the absence of UV light. Thus, the halogenation reaction can be carried out in the dark. This allows the bromination to be carried out not using a radical pathway.

[0089] CnH2n + Hal2- CnH2nHal2

[0090] For example, the first operating conditions comprise a molar ratio between the one or more olefins and the one or more halogens inferior to 1 , preferably a molar ratio of at most 0.99, more preferably of at most 0.95, even more preferably of at most 0.90. Stoichiometric excess of halogen ensures full olefin extraction.

[0091] Once formed, corresponding hydrocarbon dihalides form mixed phase with said second stream. Separation of liquid from vapor phase comprising unreacted paraffins in step (d) could be carried out, for example by flash distillation or by distillation. As the one or more dihalides, such as the one or more dibromides, have a boiling point that is superior to 120°C, or superior to 150°C, it is therefore relatively practical to perform a distillation. For instance, a propane and propylene mixture leaving a polymerization reactor typically has composition of 65-70 wt.% of propylene and 30-35 wt.% of propane based on the total weight of the propane and propylene mixture. The boiling point of propane is -42°C and the boiling point for propylene is -47.6°C, which makes the separation very energy demanding. Produced dibromopropane has boiling point of 141.9 °C, which significantly reduces required distillation column size and required energy. Other high boiling hydrocarbons, for instance octane with boiling point of 125.7°C, are typically present in trace amounts and would not be disturbing for process operation. With preference, the mixture of olefins and paraffins from said first gaseous stream does not contain high boiling paraffins (>90°C) in amounts above 1.0 wt.% based on the total weight of the mixture of olefins and paraffins. During the distillation, the one or more paraffins are going into a gaseous stream that leaves at the top of the distillation column, while the one or more dihalides and the unreacted halogens are found in the liquid stream.

[0092] Recovery of the one or more olefins

[0093] Once the one or more dihalide intermediates have been recovered, a reaction using one or more transition metals will be implemented so to trigger their reductive elimination and therefore their transformation back into the one or more olefins. For example, said one or more transition metals are selected from Zn, Fe, Cd, or any mixture thereof. With preference, the transition metal is Zn.

[0094] The metal halide that is found in the second effluent produced when step (f) is carried out is staying in solution, so that the step (g) of separating from said second effluent the one or more olefins is achieved by flash separation or distillation. When the halogen is bromine and the transition metal is zinc, the metal halide that is found in the second effluent produced when step (f) is carried out is zinc bromide (ZnBr2). Zinc bromide has high solubility in aqueous electrolytes approaching 3880 g / L at 0 °C, and 6750 g / L at 100 °C.

[0095] In an embodiment, the metal halide that is found in the second effluent produced when step (f) forms a precipitate, so that the step (g) of separating from said second effluent the one or more olefins has a preceding step of filtration.

[0096] Advantageously, the second operating conditions of step (f) comprises a temperature between 10 to 120°C, preferably between 15 and 70°C, more preferably between 20 and 60°C.

[0097] Advantageously, the second operating conditions of step (f) comprises a pressure between 0.1 MPa and 7 MPa, preferably between 0.5 MPa and 5 MPa, more preferably between 1 MPa and 4 MPa, even more preferably between 1.5 MPa and 3 MPa.

[0098] For example, the molar ratio between the one or more transition metals and the one or more dihalide is at least 1.1 , preferably least 2.0, more preferably at least 2.1. Indeed, the reaction between the one or more transition metals, such as zinc,

[0099] For example, said step (h) comprises providing an electrochemical cell with an anode and a cathode; and said electrochemical cell further comprises a separation membrane between the anode and the cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode in “charge regime” and reverse reactions to those mentioned above in “discharge” regime. Such type of electrochemical cells is called flow battery, where the electrolyte is pumped to the anode and the cathode, so that the metal of the one or more metal halides is reduced at the cathode and the halide of the one or more metal halides is oxidized to the corresponding halogen at the anode.

[0100] For example, said step (h) comprises providing an electrochemical cell with an anode and a cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode in “charge regime” and reverse reactions to those mentioned above in “discharge” regime. Such type of electrochemical cell would be a membrane-less, or nondivided, wherein the metal of the one or more metal halides is reduced at the cathode and the halide of the one or more metal halides is oxidized to the corresponding halogen at the anode.

[0101] For example, the step (h) of electrolyzing is carried out at a potential ranging between 1.0 V and 3.0 V, preferably between 1.2 V and 2.5 V, more preferably between 1.3 V and 2.1 V.

[0102] For example, the step (h) of electrolyzing is carried out at a current density ranging between 100 A / m2and 5000 A / m2, 200 A / m2and 3000 A / m2, 500 A / m2and 2000 A / m2.

[0103] In particular, the present disclosure relates to a process for separation of a mixture of olefins and paraffins; and said process is remarkable in that it comprises the following steps: a) providing a first stream comprising a mixture of one or more olefins and one or more paraffins; b) providing a second stream comprising bromine (Br2); c) contacting the first stream and the second stream under first operating conditions to produce a first effluent comprising one or more dibromides, unreacted bromine, and one or more paraffins; d) separating from said first effluent a first liquid stream and a gaseous stream, wherein said first liquid stream comprises one or more dibromides and unreacted bromine and said gaseous stream comprises one or more paraffins; e) recovering the first liquid stream from said first effluent; f) contacting the first liquid stream recovered at step (e) with zinc under second operating conditions comprising reductive elimination conditions so as to produce a second effluent comprising one or more olefins and ZnBr2; g) separating from said second effluent the one or more olefins so as to recover a second liquid stream comprising ZnBr2; and h) electrolyzing the ZnBr2 from the second liquid stream recovered at step (g) so as to recover at least said bromine.

[0104] In that case, the step (h) of electrolyzing the ZnBr2 from the second liquid stream recovered at step (g) so as to recover at least said bromine can be carried out in existing Zn-Br flow batteries that are used for energy storage on petroleum site. Figure 1 illustrates such Zn-Br flow battery. The zinc of the ZnBr2 is thus reduced at the cathode and the bromine of the ZnBr2 is oxidized at the anode. The electrodes can be in carbon. Solid zinc metal plating can be observed on the cathode.

[0105] During step (h), usually additives like quaternary ammonium salts are added, in order to capture the toxic and corrosive Br2 that is generated. Examples of quaternary ammonium salts are / V-methyl-ZV-ethyl pyrrolidinium bromide (MEPBr), ZV-methyl-ZV-ethyl morpholinium bromide (MEM), and / V-ethyl pyridinium bromide (EpyBr), preferably / V-methyl-ZV-ethyl pyrrolidinium bromide (MEPBr).

[0106] For example, an electrolyte composition can be an aqueous solution comprising 0.5 M-1.1M of MEPBr, 0.2 M-0.8M of ZnCI2, 2.2 M-2.8M of ZnBr2and 5 mL / M-15 ML / L of Br2, such as an aqueous solution comprising 0.8M MEPBr, 0.5M of ZnCI2, 2.5M of ZnBr2, and 10 mL / L of Br2.

[0107] Examples

[0108] The embodiments of the present disclosure will be better understood by looking at the different examples below.

[0109] Example 1

[0110] The present example is related to recovery of propylene from 1 ,2-dibromopropane compound. All the chemicals used for the experiment were supplied from Sigma-Aldrich. The experimental setup included a round-bottom flask with a magnetic stirrer, an oil bath and a cork with an opportunity for liquid sampling for analysis purposes. First, a liquid homogeneous electrolyte was prepared by stirring the following mixture: 14.4001 g of isopropanol, 3.3216 g of ZnBr2, 0.4646 g of ZnCI2, 1.0552 g of methylethylpyrrolidinium bromide, 2.4836 g of deionized water. After homogeneous solution was formed, 1.9494 g of 1 ,2-dibromopropane were added and the stirring was continued for another 20 min. Obtained mixture was placed in the oil bath was at 50 °C for 15 min and then 2.10508 g of chopped Zn wire was added. The sampling was performed at 10 min intervals and aliquots were analysed by ATR FTIR, Perkin-Elmer Spectrum 3 with pike GladiATR cell (see figure 2). Disappearance Characteristic peak of 1 ,2- dibromopropane at 568 cm-1was used for reaction tracing. The analysis of the effluent by GC (not shown) indicated propylene presence.

[0111] Example 2

[0112] The present example is related to transformation of propylene into 1 ,2-dibromopropane compound. The experiment was performed in bubble column reactor at 50 °C, as shown on figure 3.

[0113] First, electrolyte solution was prepared. To 100 mL of deionized water, 7.6997 g of EMPyrrBr, 25.3932 g of ZnBr2, and 3.5606 g of ZnCI2were added under stirring. After homogeneous transparent solution was formed, 1.85 mL of Br2were added, which led to immediate formation of heavy polybromide phase at the bottom.

[0114] The reactor was heated by oil thermostat and equipped with membrane pump for recycle. Without recycle the flow rate of gas is too low to hold up the liquid above the glass frit. The flow rate of propylene was set to 3 mL / min and flow rate of N2to 57 mL / min. After the reactor was heated up and flow rates were turned on, the recycle was turned on to ensure proper circulation. The outlet was analysed by microGC. When the composition was steady according ot microGC data, the liquid electrolyte prepared earlier was transferred into the reactor. Transferred liquid incorporated both polybromide phase (bottom) and aqueous phase (top). The conversion was monitored by microGC readings and evaluated based on relative peak areas: area C3= / (area C3= + area N2) (see on figure 4). The reaction was started at the time point of ~5 min when the liquid electrolyte was introduced. Immediate decrease of propylene peak in microGC was observed. After, the flow rates of propylene and nitrogen were adjusted as indicated in the figure below. After all of the Br2 was consumed, which was indicated by the colour change, 1 ,2-dibromopropane was visible as a separate phase at the bottom of the liquid, extracted from the reactor.

Claims

Claims1. Process for separation of a mixture of olefins and paraffins, said process is characterized in that it comprises the following steps: a) providing a first stream comprising a mixture of one or more olefins and one or more paraffins; b) providing a second stream comprising one or more halogens; c) contacting the first stream and the second stream under first operating conditions to produce a first effluent comprising one or more dihalides, one or more unreacted halogens, and one or more paraffins; d) separating from said first effluent a first liquid stream and a gaseous stream, wherein said first liquid stream comprises one or more dihalides and one or more unreacted halogens and said gaseous stream comprises one or more paraffins; e) recovering the first liquid stream from said first effluent; f) contacting the first liquid stream recovered at step (e) with one or more transition metals under second operating conditions comprising reductive elimination conditions so as to produce a second effluent comprising one or more olefins and one or more metal halides; g) separating from said second effluent the one or more olefins so as to recover a second liquid stream comprising said one or more metal halides; h) electrolyzing the one or more metal halides from said second liquid stream recovered at step (g) so as to recover at least said halogen.

2. Process according to claim 1 , characterized in that said process further comprises the additional step (i) of directing the halogen recovered at step (h) to the second stream provided at step (b).

3. Process according to claim 1 or 2, characterized in that the one or more halogens are selected from bromine, chlorine, fluorine, or any mixtures thereof.

4. Process according to any one of claims 1 to 3, characterized in that the one or more halogens is bromine.

5. Process according to any one of claims 1 to 4, characterized in that said one or more transition metals are selected from Zn, Fe, Cd, or any mixture thereof, preferably Zn.

6. Process according to any one of claims 1 to 5, characterized in that one transition metals is Zn.

7. Process according to any one of claims 1 to 6, characterized in that the first operating conditions comprise a molar ratio between the one or more olefins and the one or more halogens inferior to 1.

8. Process according to any one of claims 1 to 7, characterized in that the mass ratio between the one or more olefins and the one or more paraffins of the mixture of the first stream is ranging between 95 / 5 and 5 / 95.

9. Process according to any one of claims 1 to 8, characterized in that the molar ratio between the one or more transition metals and the one or more dihalides is at least 1.1.

10. Process according to any one of claims 1 to 9, characterized in that the molar ratio between the one or more transition metals and the one or more dihalides is at least 2.0.11 . Process according to any one of claims 1 to 10, characterized in that the first operating conditions of step (c) comprise carrying out the step (c) in the absence of UV light.

12. Process according to any one of claims 1 to 11 , characterized in that step (d) is carried out by distillation.

13. Process according to any one of claims 1 to 12, characterized in that the second operating conditions of step (f) comprises a temperature between 10 to 120°C .

14. Process according to any one of claims 1 to 13, characterized in that the second operating conditions of step (f) comprises a pressure between 0.1 MPa and 7 MPa.

15. Process according to any one of claims 1 to 14, characterized in that said step (h) comprises providing an electrochemical cell with an anode and a cathode; and saidelectrochemical cell further comprises a separation membrane between the anode and the cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode.

16. Process according to any one of claims 1 to 15, characterized in that said step (h) comprises providing an electrochemical cell with an anode and a cathode; wherein the metal of the one or more metal halides is converted to reduce corresponding metal cations into metal on cathode and to oxidize corresponding halogen anions at the anode.

17. Process according to any one of claims 1 to 16, characterized in that the step (h) of electrolyzing is carried out at a potential ranging between 1.0 V and 3.0 V.

18. Process according to any one of claims 1 to 17, characterized in that the step (h) of electrolyzing is carried out at a current density ranging between 100 A / m2and 5000 A / m2.

19. Process according to any one of claims 1 to 18, characterized in that step (h) is carried out in the presence of one or more quaternary ammonium salts.

20. Process according to any one of claims 1 to 19, characterized in that the first stream comprises a mixture of one or more olefins and one or more paraffins that have the same number of carbon atoms.

Images