Thermally optimized process and installation for the production of an aqueous solution of 5-HMF

Abstract

The present invention relates to a method, and the corresponding installation, comprising:- a liquid-liquid extraction step (B) of an aqueous feedstock comprising 5-HMF and an aprotic polar synthesis solvent, producing an aqueous raffinate (5) and an organic extract;- a backwashing step (C) of the organic extract with an aqueous solvent producing an aqueous back-extract and an organic raffinate (8);- a regeneration step of the extraction solvent comprising a sub-step of concentrating the organic raffinate (8) in 5-HMF and a hydrodistillation sub-step (E); - a regeneration step of the synthesis solvent comprising at least one evaporation sub-step and one distillation sub-step (G). According to the invention, the aqueous raffinate (5) and / or said organic raffinate (8) are heated in heat exchange means (E1, E2, E3) with at least one gas phase (203) produced during said at least one evaporation sub-step. Figure 3 to be published

Description

Title of the invention: Process and installation for the production of an aqueous solution of 5-HMF thermally optimized Technical field

[0001] The present invention relates to the field of the production of 5-hydroxymethylfurfural (5-HMF), in particular a process and an installation for producing an aqueous solution of 5-HMF implementing heat exchanges between flows generated during said production with a view to thermal optimization. Prior art

[0002] 5-(hydroxymethyl)furfural, also called HMF or 5-HMF, is a compound of interest derived from biomass which can be used in many fields, particularly in pharmacy, agrochemistry or specialty chemistry.

[0003] The production of 5-HMF by dehydration of sugars has been known for many years and has been the subject of a large number of research studies. The dehydration conditions are numerous, the following methods can be cited as examples: - 5-HMF can be obtained in aqueous media, usually in the presence of an acid catalyst. This acid catalyst allows the dehydration of C6 sugar (hexose, and in particular fructose) into 5-HMF, but also catalyzes the rehydration of 5-HMF into formic acid and levulinic acid, which seriously affects the yield. - 5-HMF can also be obtained in a non-aqueous protic polar medium, with solvents such as methanol, ethanol or acetic acid, and in the presence of an acid catalyst. Under these conditions, 5-HMF is obtained in a mixture with an ether or ester derivative of 5-HMF depending on the reaction medium used. The formation of these secondary products is due to the reaction of 5-HMF with the reaction solvent in an acid medium. For example, application WO2007 / 104514 describes the synthesis of 5-HMF by dehydration of sugar using methanol or ethanol as solvent in the presence of an acid catalyst. In this case, the presence of said catalyst also catalyzes the etherification reaction of 5-HMF with alcohol to give a mixture of 5-HMF and its methyl or ethyl ether form depending on the alcohol used as solvent. - 5-HMF can also be produced in a polar aprotic medium with or without an acid catalyst. Particularly noteworthy is the use of dimethyl sulfoxide (DMSO), which, with or without an acid catalyst, can produce 5-HMF in very good yields and without the undesirable reactions listed above.

[0004] Furthermore, whatever the synthesis medium (water, methanol, DMSO, etc.), Polymeric side products called humins are formed during the production of 5-HMF (van Dam, HE; ​​Kieboom, APG; van Bekkum, H. (1986) The Conversion of Fructose and Glucose in Acidic Media: Formation of Hydroxymethyl-furfural. In: Starch - Stârke, vol. 38, no. 3, pp. 95-101).

[0005] The synthesis of 5-HMF in a medium such as DMSO is particularly interesting, because it makes it possible to obtain 5-HMF in its alcohol form (and not ether) with very good yields. However, the physicochemical properties of DMSO (or any other polar aprotic solvent) make it very difficult to separate from 5-HMF by the usual methods known to those skilled in the art.

[0006] A known method for isolating 5-HMF from DMSO is liquid-liquid extraction, followed by crystallization of the extract, as described in patent FR2669635.

[0007] The Applicant has already proposed an improvement to the process described in patent FR2669635, which was the subject of patent FR3071172. This improvement is based on the modification of the liquid-liquid extraction step, in particular by adding a backwashing step with water, and by recycling the backwashing water upstream of the liquid-liquid extraction to mix it with the 5-HMF / DMSO feedstock, said mixture optionally being filtered before the liquid-liquid extraction. This improvement makes it possible to increase the purity of the 5-HMF without loss of yield of the product of interest, and to carry out the 5-HMF crystallization step under more favorable conditions.

[0008] A liquid-liquid extraction method for isolating 5-HMF from DMSO is also described in patent application FR3131313, but this time within the framework of a process making it possible to recover 5-HMF not in crystallized form but in aqueous solution, which can be advantageous because the crystallization of 5-HMF remains an expensive operation. To this end, the process described in FR3131313 implements a liquid-liquid extraction step associated with a backwashing step with water of the organic extract comprising the 5HMF resulting from the liquid-liquid extraction, as well as a 5-HMF concentration step of the organic raffinate comprising the 5-HMF obtained in the backwashing step, and a hydrodistillation step of the concentrated stream resulting from said concentration step, in order to recover the 5-HMF in the form of an aqueous solution of 5-HMF.In the described process, various water-DMSO mixtures generated by the process steps can be sent to a treatment step comprising an evaporation section and a distillation section, making it possible to recover an aqueous effluent which can be used in whole or in part in the backwashing step and / or in the hydrodistillation step, but also upstream of the liquid-liquid extraction when mixing the 5-HMF / DMSO feedstock with water. This water-DMSO mixture treatment step also makes it possible to recover a DMSO-rich stream and a stream rich in impurities, in particular heavy impurities. such as humins.

[0009] Such recycling of an aqueous stream in the process makes it possible to limit the operating costs of the process and its environmental impact. Indeed, any water stream from the process needs to be treated before being discharged into the environment and thus the recycling of water in the process makes it possible to reduce the reprocessing costs of the process and its environmental impact. On the other hand, such recycling limits the supply of external pure water, which further reduces the operating costs of the process. Objectives and Summary of the Invention

[0010] With a similar objective of limiting the operating costs of the process and its environmental impact, the Applicant proposes a process for producing an aqueous solution of 5-HMF similar to that described in patent FR3131313, and an associated installation, implementing heat exchanges between certain flows generated during the process allowing thermal optimization of the process.

[0011] Thanks to the present invention, which takes advantage of certain hot streams available in the process for producing an aqueous solution of 5-HMF to heat certain cold streams, the consumption of hot utilities is significantly reduced, thus limiting energy expenditure and the associated environmental cost, as well as the operating costs of the process.

[0012] Thus, to achieve at least one of the above-mentioned objectives, among others, the present invention proposes, according to a first aspect, a method for producing an aqueous solution of 5-HMF, comprising the following steps: - a liquid-liquid extraction step (B) of an aqueous feedstock comprising 5-HMF and an aprotic polar synthesis solvent, in the presence of an extraction solvent, producing an aqueous raffinate comprising said aprotic polar synthesis solvent and an organic extract comprising 5-HMF and the extraction solvent; - a step of backwashing (C) the organic extract with an aqueous solvent producing an aqueous backextract and an organic raffinate comprising 5-HMF and an organic solvent; - a step of regeneration of the extraction solvent comprising: a sub-step of concentrating 5-HMF (D) by removing at least a portion of the organic solvent from said organic raffinate producing a concentrated organic raffinate comprising 5-HMF and residual organic solvent, and a first stream comprising organic solvent, and a hydrodistillation sub-step (E) carried out by distillation in the presence of water of said concentrated organic raffinate producing the aqueous solution of 5-HMF and a second stream comprising organic solvent; - a step of regeneration of the polar aprotic synthesis solvent (200) comprising: at least one evaporation sub-step (F, F1, F2, F3) for removing at least part of the impurities from said aqueous raffinate and producing a liquid stream concentrated in impurities and at least one stream comprising water and aprotic polar synthesis solvent, and a distillation sub-step (G) carried out by distillation of at least a portion of said stream comprising water and aprotic polar synthesis solvent producing an aqueous effluent and a stream of aprotic polar synthesis solvent recyclable in said process; and in which heating, in heat exchange means, said aqueous raffinate and / or said organic raffinate with at least one gas phase produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent.

[0013] According to one or more implementations of the invention, said organic raffinate is heated with a gas phase produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent (200).

[0014] According to one or more implementations of the invention, said organic raffinate is heated in two heat exchangers positioned in series with respectively two gas phases produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent (200).

[0015] According to one or more implementations of the invention, in the method: - the 5-HMF concentration sub-step (D) of the extraction solvent regeneration step comprises: heating said organic raffinate successively in a first heat exchanger and a second heat exchanger positioned in series with respectively a first gas phase and a second gas phase, then in a first external flow heat exchanger, and the gas-liquid separation of said reheated organic raffinate in a first separation tank; and - the step of regenerating the aprotic polar synthesis solvent (200) comprises at least: - a first evaporation sub-step (Fl) comprising heating said aqueous raffinate successively in a third heat exchanger with a third gas phase and in a second external flow heat exchanger, gas-liquid separation of said heated aqueous raffinate in a second separation tank producing said third gas phase and a liquid flow, and gas-liquid separation in a third separation tank of said third gas phase after its cooling in the third heat exchanger producing the second gas phase; and - a second evaporation sub-step comprising heating said liquid flow from the first evaporation sub-step successively in a fourth heat exchanger and in a third external flow heat exchanger, and gas-liquid separation of said heated liquid stream in a fourth separation tank producing the first cooled gas phase in the form of a stream in said fourth heat exchanger before sending it to the first heat exchanger at the 5-HMF concentration step (D).

[0016] According to one or more implementations of the invention, the method: - the 5-HMF concentration sub-step (D) of the extraction solvent regeneration step comprises: heating said organic raffinate successively in a first heat exchanger and a second heat exchanger positioned in series with respectively a first gas phase and a second gas phase, then in a first external flow heat exchanger, and the gas-liquid separation of said reheated organic raffinate in a first separation tank producing the first gas phase; and - the step of regenerating the aprotic polar synthesis solvent (200) comprises at least: - a first evaporation sub-step (Fl) comprising heating said aqueous raffinate successively in a third heat exchanger with a third gas phase and in a second external flow heat exchanger, gas-liquid separation of said heated aqueous raffinate in a second separation tank producing said second gas phase and a liquid stream, and gas-liquid separation in a third separation tank of said second gas phase after its cooling in the second heat exchanger common to the 5-HMF concentration sub-step (D); and - a second evaporation sub-step (F2) comprising heating said liquid flow from the first evaporation sub-step in a third external flow heat exchanger, and the gas-liquid separation of said heated liquid flow in a fourth separation tank producing the third gas phase.

[0017] According to one or more implementations of the invention, the step of regenerating the aprotic polar synthesis solvent (200) comprises three successive evaporation sub-steps (F1, F2, F3) so as to progressively concentrate the impurities of said aqueous raffinate into a liquid phase, the third evaporation sub-step (F3) producing a liquid stream of impurities discharged from the process and an effluent comprising water and aprotic polar synthesis solvent sent to the distillation sub-step (G).

[0018] According to one or more implementations of the invention, said at least one evaporation step is carried out at a temperature between 80°C and 130°C and at a pressure between 0.0001 MPa and 0.100 MPa.

[0019] According to one or more implementations of the invention, the process comprises a step (A) of bringing into contact a synthesis effluent containing 5-HMF and said polar aprotic synthesis solvent with an aqueous stream so as to obtain an aqueous feedstock comprising 5-HMF and an aprotic polar synthesis solvent, said synthesis effluent preferably being obtained from a step of synthesis of 5-HMF (A') from a sugar feedstock comprising a hexose in the presence of an acid dehydration catalyst and the polar aprotic synthesis solvent and carried out at a temperature of between 30°C and 200°C and at a pressure of between 0.001 MPa and 10 MPa.

[0020] According to one or more implementations of the invention, said polar aprotic synthesis solvent is chosen from pyridine, butan-2-one, acetone, acetic anhydride, N,N,N',N'-tetramethylurea, benzonitrile, acetonitrile, methyl ethyl ketone, propionitrile, hexamethylphosphoramide, nitrobenzene, nitromethane, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, N-methylpyrrolidone, dimethyl sulfoxide, propylene carbonate and y-valerolactone, taken alone or as a mixture, and preferably is dimethyl sulfoxide, and said extraction solvent is chosen from dichloromethane, diethyl ether, diisopropyl ether, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, thiophene, anisole and toluene, and preferably is methyl isobutyl ketone.

[0021] According to a second aspect, the present invention proposes an installation for producing an aqueous solution of 5-HMF, for implementing the method according to the invention, comprising: - means for liquid-liquid extraction of an aqueous feed comprising 5-HMF and an aprotic polar synthesis solvent, configured to bring an extraction solvent into contact with said feed and produce an aqueous raffinate depleted in 5-HMF and an organic extract enriched in 5-HMF; - backwashing means configured to contact said organic extract with an aqueous solvent and produce an aqueous backextract and an organic raffinate comprising 5-HMF and an organic solvent; - means for regenerating the extraction solvent comprising: — 5-HMF concentration means configured to eliminate at least part the organic solvent of said organic raffinate and producing a concentrated organic raffinate comprising 5-HMF and residual organic solvent, and a first stream comprising organic solvent; and — a hydrodistillation unit configured to distill said concentrated organic raffinate in the presence of water and produce the aqueous solution of 5-HMF and a second stream comprising organic solvent; - means for regenerating the aprotic polar synthesis solvent comprising at least one evaporation section configured to remove at least part of the impurities from said aqueous raffinate and produce a liquid stream concentrated in impurities and at least one stream comprising water and aprotic polar synthesis solvent and a distillation section configured to distill said stream comprising water and aprotic polar synthesis solvent and produce an aqueous effluent and a stream of aprotic polar synthesis solvent recyclable in said system; said installation comprising heat exchange means configured to heat said aqueous raffinate and / or said organic raffinate with at least one gas phase produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent.

[0022] According to one or more embodiments of the invention, the heat exchange means comprise at least one heat exchanger configured to heat said organic raffinate with a gas phase produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent.

[0023] According to one or more embodiments of the invention, the heat exchange means comprise two successive heat exchangers configured to heat said organic raffinate with respectively two gas phases produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent.

[0024] According to one or more embodiments of the invention, the installation comprises: - said 5-HMF concentration means successively comprising: a first heat exchanger and a second heat exchanger formed by said two successive heat exchangers of said heat exchange means, a first external flow heat exchanger and a first separation tank; - said means for regenerating the aprotic polar synthesis solvent comprising: — a first evaporation section successively comprising a third heat exchanger, a second external flow heat exchanger, a second separation tank and a third separation tank; — a second evaporation section configured to receive a liquid flow from said second separation tank and successively comprising a fourth heat exchanger, a third external flow heat exchanger, and a fourth separation tank; - said first heat exchanger and said second heat exchanger are configured to heat said organic raffinate with respectively a first gas phase and a second gas phase, said first gas phase coming from the fourth separation tank and cooled in the form of a flow in said fourth heat exchanger, and said second gas phase coming from the third separation tank; - said third heat exchanger being configured to heat said aqueous raffinate with a third gas phase from the second separation tank.

[0025] According to one or more embodiments of the invention, the installation comprises: - said 5-HMF concentration means successively comprising: a first heat exchanger, a second heat exchanger, a first external flow heat exchanger and a first separation tank; - said means for regenerating the aprotic polar synthesis solvent comprising: — a first evaporation section successively comprising a third heat exchanger, a second external flow heat exchanger, a second separation tank, said second heat exchanger common to said 5-HMF concentration means (D), and a third separation tank; — a second evaporation section configured to receive a liquid flow from said second separation tank and successively comprising a third external flow heat exchanger and a fourth separation tank; - said first heat exchanger and said second heat exchanger being configured to successively heat said organic raffinate with respectively a first gas phase from the first separation tank and a second gas phase from the second separation tank; - said third heat exchanger being configured to heat said aqueous raffinate with a third gas phase from the fourth separation tank.

[0026] According to one or more embodiments of the invention, said means for regenerating the aprotic polar synthesis solvent comprise three successive evaporation sections configured to progressively concentrate the impurities of said aqueous raffinate in a liquid phase, the third evaporation section being configured to produce a liquid stream of impurities to be removed from the system and an effluent comprising water and aprotic polar synthesis solvent sent to the distillation section.

[0027] Other objects and advantages of the invention will appear on reading the following description of particular examples of embodiments of the invention, given as of non-limiting examples, the description being made with reference to the appended figures described below. List of figures

[0028] [Fig.l]

[0029] [Fig.l] is a block diagram illustrating an embodiment of the method and installation according to the invention.

[0030] [Fig.2]

[0031] [Fig.2] is a block diagram illustrating another embodiment of the method and the installation according to the invention, in which the evaporation at the regeneration stage of the aprotic polar synthesis solvent is carried out in three successive stages.

[0032] [Fig.3]

[0033] [Fig. 3] illustrates the heat exchanges between streams of the process according to an embodiment of the invention, in which 3 heat exchangers are implemented in heat exchanges between streams involved in the regeneration of the extraction solvent and the regeneration of the aprotic polar synthesis solvent.

[0034] [Fig.4]

[0035] [Fig.4] illustrates the heat exchanges between streams of the process according to another embodiment of the invention, in which 4 heat exchangers are implemented in heat exchanges between streams involved in the regeneration of the extraction solvent and the regeneration of the aprotic polar synthesis solvent.

[0036] In the figures, the same references designate identical or similar elements. However, identical or similar elements may have different references. Description of the embodiments

[0037] In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the method and installation. However, it will be apparent to those skilled in the art that the method and installation may be implemented without necessarily all of these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0038] It is specified that, throughout this description, the expression “between ... and ...” must be understood as including the limits cited, unless otherwise specified.

[0039] In this description, the term "comprise" is synonymous with (means the same as) "comprise", "include" and "contain", and is inclusive or open and does not exclude other elements that are not mentioned. It is understood that the term "comprise" includes the exclusive and closed term "consist".

[0040] Further, when used in this specification, the terms "essen tially” or “substantially” or “approximately” in relation to a reference value correspond to an approximation of ± 10%, preferably ± 5%, very preferably ± 2%, or even more preferably ± 1% of this reference value, which may be a temperature, a pressure, a distance, a speed, a flow rate, a content of compound(s), etc.

[0041] Within the meaning of the present invention, the various embodiments presented may be implemented separately or in combination with each other, without limitation of combinations when this is technically feasible.

[0042] In the sense of the present invention, the different parameter ranges for a given step such as pressure ranges and temperature ranges may be used alone or in combination. For example, in the sense of the present invention, a preferred range of pressure values ​​may be combined with a more preferred range of temperature values.

[0043] In this description, pressures are expressed as absolute values, unless otherwise specified.

[0044] In the present description, the term aprotic solvent means a molecule acting as a solvent and all of whose hydrogen atoms are carried by carbon atoms.

[0045] In the present description, the term polar solvent means a molecule acting as a solvent whose dipole moment p expressed in Debye has a numerical value greater than or equal to 2.00 measured at 25°C.

[0046] In the present description, the term “aprotic polar solvent” is therefore understood to mean a molecule acting as a solvent in which all the hydrogen atoms are carried by carbon atoms and in which the dipole moment p expressed in Debye has a numerical value greater than or equal to 2.00 measured at 25°C.

[0047] In the present description, the expression “synthesis solvent” designates the polar aprotic synthesis solvent, i.e. the polar aprotic solvent used for the synthesis of 5-HMF.

[0048] For a better understanding of the invention, references appearing in Figures 1 to 4 are mentioned below to designate different elements of the method and the installation, without this limiting the scope or constituting a limitation to the particular embodiments described below.

[0049] The steps and the means capable of carrying out these steps are generally designated by the same references in the figures and in the description below. For example, the liquid-liquid extraction step and the liquid-liquid extraction means are referred to by the same reference “B”.

[0050] An object of the invention is a method for producing an aqueous solution of 5-HMF comprising the following steps: - a liquid-liquid extraction step (B) of the aqueous feedstock 3 comprising 5-HMF and a synthesis solvent, in the presence of the extraction solvent 4, producing the aqueous raffinate 5 comprising the synthesis solvent and the organic extract 6 comprising 5-HMF and the extraction solvent; - a backwashing step (C) of the organic extract 6 with the aqueous solvent 7 producing the aqueous counter-extract 9 and the organic raffinate 8 comprising 5-HMF and an organic solvent; - a step of regenerating the extraction solvent (100) comprising a sub-step of concentrating 5-HMF (D) by removing at least a portion of the organic solvent from the organic raffinate 8 producing the concentrated organic raffinate 10 comprising 5-HMF and residual organic solvent, and the first stream comprising organic solvent 11, and a sub-step of hydrodistillation (E) carried out by distillation in the presence of water 14 of the concentrated organic raffinate 10 producing the aqueous solution of 5-HMF 12 and the second stream 13 comprising organic solvent; - a step of regenerating the synthesis solvent (200) comprising at least one evaporation sub-step (F or F1, F2 and F3) to remove at least part of the impurities from the aqueous raffinate (5) and producing the liquid stream concentrated in impurities 17 ([Fig.l]) or 26 ([Fig.2]) and at least one stream comprising water and synthesis solvent (19 [Fig.l], and streams 22, 24, 25 [Fig.2]) and a distillation sub-step (G) implemented by distillation of at least part of said water-synthesis solvent stream (19, or 22, 24, 25) producing the aqueous effluent 15 and the synthesis solvent stream 16 recyclable in the process. According to the invention, the aqueous raffinate 5 and / or the organic raffinate 8 are heated in the heat exchange means with at least one gas phase produced during said at least one evaporation sub-step of the synthesis solvent regeneration step.

[0051] Another object of the invention is an installation for producing an aqueous solution of 5-HMF, suitable for implementing the method according to the invention, comprising: - liquid-liquid extraction means B of an aqueous feedstock 3 comprising 5-HMF and a synthesis solvent, configured to bring an extraction solvent 4 into contact with the feedstock 3 and produce an aqueous raffinate 5 depleted in 5-HMF and an organic extract 6 enriched in 5-HMF; - backwashing means C configured to bring the organic extract 6 into contact with an aqueous solvent 7 and produce an aqueous backextract 9 and an organic raffinate 8 comprising 5-HMF and an organic solvent; - means for regenerating the extraction solvent 100 comprising means of 5-HMF concentration D configured to at least partially remove the organic solvent from said organic raffinate 8 and produce a concentrated organic raffinate 10 comprising 5-HMF and residual organic solvent, and a first stream comprising organic solvent 11, and a hydrodistillation unit E configured to distill said concentrated organic raffinate 10 in the presence of water 14 and produce the aqueous 5-HMF solution 12 and a second stream comprising organic solvent 13; - means for regenerating the synthesis solvent 200 comprising at least one evaporation section (F or F1, F2, F3) configured to eliminate at least in part impurities from said aqueous raffinate 5 and produce the liquid stream concentrated in impurities (17 or 26) and at least one stream (19, or 22, 24, 25) comprising water and synthesis solvent, and a distillation section G configured to distill said water-synthesis solvent stream (19, or 22, 24, 25) and produce an aqueous effluent 15 and a synthesis solvent stream 16 recyclable in said system; - heat exchange means, as illustrated in figures 3 and 4 with the heat exchangers E1 to E4 and E1' to E3', configured to heat said aqueous raffinate 5 and / or said organic raffinate 8 with at least one gas phase (203, 218, 223 / 224, 206) produced in said at least one evaporation section of the synthesis solvent regeneration means 200.

[0052] Each of these steps of the method and associated means will now be described in detail below. The method and the installation according to the invention may further comprise steps of synthesis of 5-HMF and of preparation of the feedstock 3 sent to the liquid-liquid extraction B, such as also described below with steps A' and A.

[0053] The essential aspect of the invention relating to the heat exchanges between the aqueous raffinate 5 and / or the organic raffinate 8 and at least one gas phase produced during the evaporation sub-step(s) during the regeneration of the synthesis solvent, is described below in relation to the steps of regeneration of the extraction solvent (100) and of regeneration of the synthesis solvent (200), because said heat exchanges are carried out on flows involved in these steps.

[0054] Optional steps (A') and (A): step of dehydration of sugars into 5-HMF and mixing step

[0055] The process according to the invention may comprise a step (A) of bringing into contact a synthesis effluent 1 containing 5-HMF and synthesis solvent with an aqueous stream so as to obtain an aqueous feedstock 3 comprising 5-HMF and a synthesis solvent, said aqueous feedstock 3 being the feedstock sent to the liquid-liquid extraction step (B), optionally after a filtration step to remove the “humins” which precipitated during step (A). The synthesis effluent 1, sent to the mixing stage (A), is advantageously obtained from a synthesis step of 5-HMF (A') from a sugar feedstock Cs comprising a hexose, in the presence of an acid dehydration catalyst and the synthesis solvent S and carried out at a temperature between 30°C and 200°C and at a pressure between 0.001 MPa and 10 MPa.

[0056] Optional step (A') of dehydration of sugars into 5-HMF

[0057] By sugar charge Cs which comprises a hexose, it is meant that the hexose can be in monomeric form (monosaccharide) or be a unit belonging to a disaccharide, oligosaccharide or polysaccharide. A saccharide is a compound also called sugar.

[0058] Preferably the hexose is fructose or a fructosidic unit.

[0059] In one embodiment, the feedstock comprises either free fructose, alone or in admixture with any saccharide species, or comprises any oligosaccharide or polysaccharide feedstock containing one or more fructosidic units capable of releasing fructose by one or more hydrolysis steps, optionally in admixture with other saccharide species. Preferably, the sugar feedstock Cs treated in the method is crystalline fructose, a syrup containing fructose, a syrup containing fructose and glucose, or crystalline sucrose or a sucrose syrup.

[0060] Advantageously, the sugar charge Cs comprises fructose in monomeric, oligomeric or polymeric form.

[0061] By sugar filler containing free fructose taken in mixture with any saccharide species, we mean for example syrups of the High-Fructose-Com-Syrup type containing fructose and glucose in different proportions (glucose / fructose in mass or molar ratios 58 / 42, 45 / 55, 10 / 90 for example).

[0062] Syrup is understood to mean a solution of sugars, in particular saccharides, in water having a concentration of at least 30% by weight, preferably at least 50% by weight, preferably at least 70% by weight.

[0063] The sugar filler Cs may comprise a saccharide comprising one or more fructosidic units and one or more non-fructosidic units, fructose being able to be released by one or more hydrolysis steps, for example oligosaccharides and polysaccharides in which at least one monosaccharide unit is fructose, for example fillers such as sucrose, kestose, fructans, oligofructans, rinulin.

[0064] Advantageously, the saccharide fillers are capable of releasing monomeric fructose by osidic hydrolysis, said fructose produced being able to be transformed into 5-HMF.

[0065] Preferably, the oligosaccharide has the following molecular formula: (C6mHiom+205m+i) (C5nH8n+2O4n+i) where m and n are integers whose sum is between 2 and 6. The mono units saccharides composing said oligosaccharide are identical or not, and at least one unit of formula (C6mHi0m+2O5m+i) is fructose. By extension, preferably the polysaccharide has the empirical formula (C6mHi0m+2O5m+i) (C5nH8n+2O4n+i) where m and n are integers whose sum is greater than or equal to 7.

[0066] The polar aprotic synthesis solvent is advantageously chosen from all polar aprotic solvents whose dipole moment expressed in Debye (D) is greater than or equal to 2.00. Preferably, the aprotic polar solvents are chosen from pyridine (2.37), butan-2-one (5.22), acetone (2.86), acetic anhydride (2.82), N,N,N',N'-tetramethylurea (3.48), benzonitrile (4.05), acetonitrile (3.45), methyl ethyl ketone (2.76), propionitrile (3.57), hexamethylphosphoramide (5.55), nitrobenzene (4.02), nitromethane (3.57), N,N-dimethylformamide (3.87), N,N-dimethylacetamide (3.72), sulfolane (4.80), N-methylpyrrolidone (4.09) noted NMP, dimethyl sulfoxide (3.90) noted DMSO, propylene carbonate (4.94) and γ-valerolactone (4.71), alone or in mixture.

[0067] Preferably, the synthesis solvent is advantageously chosen from acetone, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, NMP, DMSO, propylene carbonate and γ-valerolactone, alone or as a mixture.

[0068] Preferably, the synthesis solvent is advantageously chosen from N,N-dimethylacetamide, NMP, DMSO, and γ-valerolactone, alone or as a mixture.

[0069] Very preferably, the synthesis solvent is DMSO.

[0070] The term “acid dehydration catalyst” means any Brônsted acid catalyst chosen from organic or inorganic, homogeneous or heterogeneous Brônsted acids capable of inducing the dehydration of sugars into 5-HMF.

[0071] Preferably, the acid dehydration catalyst is a Brpnsted acid having a pKa in the synthesis solvent, preferably in DMSO, of between 0 and 5.0, preferably of between 0.5 and 4.0 and more preferably of between 1.0 and 3.0. Said pKa are as defined in the article by FG ​​Bordwell et al. (J. Am. Chem. Soc., 1991, 113, 8398-8401).

[0072] Preferably, the acid dehydration catalyst is selected from HF, HCl, HBr, HI, H2SO3, H2SO4, H3PO2, H3PO4, HNO2, HNO3, H2WO4, H4SiW12O40, H3PW12O40, (NH4)6(W12O40).xH2O, H4SiMo12O40, H3PMo12O40, (NH4)6Mo7O24.xH2O, H2MoO4, HreO 4, H2CrO4, H2SnO3, H4SiO4, H3BO3, HclO4, HBF4, HSbF5, HPF6, H2FO3P, C1SO3H, FSO3H, HN(SO2F)2, HIO3, BF3, A1C13, Al(Otf)3, FeCl3, ZnCl2, SnCl2, CrCl3, CeCl3, ErCl3, formic acid, acetic acid, trifluoroacetic acid, lactic acid, levulinic acid, methanesulfinic acid, methanesulfonic acid, trifluoromethanesulfonic acid, bis(trifluoromethanesulfonyl)amine, benzoic acid, paratoluenesulfonic acid, 4-biphenylsulfonic acid, diphenylphosphate, and 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate. Preferably, the acid dehydration catalyst is chosen from HCl, H2SO4, H3PO2, H3PO4, HNO3, A1C13, acetic acid, trifluoroacetic acid, methanesulfinic acid, methanesulfonic acid, trifluoromethanesulfonic acid.

[0073] The dehydration step is carried out at a temperature between 30°C and 200°C, preferably between 50°C and 180°C, preferably between 70°C and 150°C and preferably between 90°C and 130°C, for example a temperature of 120°C. The dehydration step is carried out at a pressure between 0.001 MPa and 10 MPa, preferably between 0.001 MPa and 5 MPa, preferably between 0.01 MPa and 1 MPa. Depending on the pressure and temperature conditions, the reaction medium is above or below the bubble point of the mixture. Bubble point means the pressure and temperature conditions under which the first gas bubbles appear for a liquid.When the reaction medium is above the bubble point of the mixture, the vapor phase can be withdrawn from the reactor, optionally rectified, and condensed to form the condensates, which can be sent to the distillation sub-step (G) of the synthesis solvent regeneration step (200) (sending not shown in the figures).

[0074] Preferably, the acid dehydration catalyst is introduced into the dehydration step (A') in a molar ratio of the catalyst relative to the sugar feedstock Cs, denoted Acid / Sugar, expressed as a molar percentage (mol%), of between 0.01 and 10 mol%, preferably between 0.05 and 8 mol%, preferably between 0.1 and 6 mol%, preferably between 0.2 and 5 mol%, preferably between 0.3 and 4 mol% and very preferably between 0.5 and 3 mol%.

[0075] The dehydration step (A') can be carried out according to different embodiments. Thus, the step can advantageously be implemented discontinuously or continuously (the discontinuous mode being called "batch" according to English terminology). The addition of the sugar feedstock Cs can be progressive (called "fed-batch" according to English terminology) in the case of discontinuous implementation or staged in different CSTR reactors (Continuously Stirred Tank Reactor according to English terminology) in series in a continuous implementation. It can be carried out in a closed reaction chamber or in a semi-open reactor.

[0076] The synthesis effluent 1 obtained at the end of the optional dehydration step (A') comprises 5-HMF and synthesis solvent, preferably DMSO.

[0077] The synthesis solvent, typically DMSO, generally represents between 30 and 95% by weight of the synthesis effluent 1 from the dehydration step (A') and sent to step (A), preferably between 40 and 90% by weight, preferably between 50 and 90% by weight, preferably between 55 and 85% by weight.

[0078] 5-HMF generally represents at least 1% by weight of the synthesis effluent 1 from the dehydration step (A') and sent to step (A), preferably at least 10% by weight, preferably at least 15% by weight and preferably at most 50% by weight, preferably at most 40% by weight, more preferably at most 30% by weight.

[0079] Furthermore, said synthesis effluent 1 may contain water even before mixing in step (A) with an aqueous stream. Said water may come from the dehydration step, for example water is formed during the dehydration reaction of sugar into 5-HMF (3 moles of water generated per mole of 5-HMF produced). This water may also have been introduced with the sugar, in the case where, for practical reasons, a sugar syrup, for example at approximately 70% by weight in water, is used as sugar feedstock Cs. Advantageously, during the dehydration step, a water-synthesis solvent mixture (e.g. DMSO) may be recovered in the vapor phase. Said water-synthesis solvent mixture (e.g. DMSO) may advantageously be sent to the distillation sub-step (G) of the solvent regeneration step of (200) (sending not shown in the figures).Thus, the synthesis effluent 1 from the dehydration step (A') and introduced into the mixing step (A) may contain water, in a proportion generally between 0.1 and 30% by weight, preferably between 0.1 and 15% by weight, preferably between 0.1 and 10% by weight.

[0080] During the dehydration step, a concomitant extraction of water from the reaction medium can improve the selectivity of the reaction. 5-HMF selectivity is understood to mean the ratio between the number of moles of 5-HMF produced and the number of converted moles of fructose contained in the Cs sugar feed introduced into the process. In a polar aprotic medium, the presence of water degrades the conversion selectivity of the sugars in a manner that is all the more notable as the concentration of sugars in the DMSO is high. Continuous extraction of water during the synthesis of 5-HMF is therefore advantageous in this respect, and can also have the advantage of managing in a single step the extraction of the water that may be present in the Cs sugar feed if it is in the form of a syrup.

[0081] When the sugar feedstock Cs is in the form of a syrup, it may also be advantageous to reduce the water content present upstream of the dehydration step (A'), instead of or in addition to a concomitant extraction of water from the reaction medium during the dehydration step (A'). Thus, an extraction and substitution of the water from the sugar feedstock Cs in the form of syrup by a synthesis solvent, e.g. DMSO, may be carried out and a mixture sent to the dehydration step (A') may be obtained. The water from the syrup may be extracted at least in part after mixing the syrup with the synthesis solvent. Said solvent makes it possible to keep the sugar in a dilute medium and to substitute the dilution with water by dilution with the synthesis solvent. Such extraction of water may be carried out by different methods, such as evaporation, adsorption (e.g. in a molecular sieve), membrane separation, and is advantageously carried out by distillation, requiring that the synthesis solvent be less volatile than water.

[0082] The synthesis effluent 1 may also contain impurities, in particular humins.

[0083] The term "humins" refers to all the undesirable polymeric compounds formed during the synthesis of 5-HMF. Humins represent, in particular, less than 30% by weight of the converted sugar feedstock, preferably less than 20% by weight.

[0084] During the dehydration step (A'), the conversion rate of the sugar, e.g. fructose, is at least 80%, preferably at least 90% and even more preferably at least 98%.

[0085] By conversion rate, we mean the ratio between the sugar consumed during the reaction (difference between the total sugar used and the residual sugar at the end of the reaction) to the total sugar used in the reaction.

[0086] The selectivity of conversion of sugar to 5-HMF is defined as the molar ratio between the number of moles of 5-HMF produced by the reaction and the number of moles of sugar consumed by the reaction.

[0087] Finally, the molar yield of 5-HMF is defined as the molar ratio between the number of moles of 5-HMF produced by the reaction and the number of moles of sugar involved in the reaction. The molar yield is therefore the product of the conversion and the selectivity.

[0088] The molar yield of 5-HMF is at least 70%, preferably at least 80%.

[0089] An optional neutralization step (not shown) can be carried out on the synthesis effluent 1 from the dehydration step (A'), upstream of the mixing step (A). This makes it possible to reduce the reactivity of the medium and thus to avoid the degradation mechanisms of 5-HMF, or even to reduce the corrosion of the materials of the equipment downstream of the dehydration step. Since the dehydration reaction can produce some organic acids, the quantity of neutralization agent can advantageously make it possible to neutralize all of the acids present in the synthesis effluent 1 from the dehydration step. Such a neutralization step is advantageously carried out at a minimum at the stoichiometric ratio of the quantity of catalyst used, and generally carried out in slight over-stoichiometry relative to the catalyst used, preferably between 1 and 2 times the stoichiometric ratio, preferably between 1 and 1.5 times the stoichiometric ratio.The neutralizing agent may be a basic compound selected from NaOH, KOH, NH4OH, Na2 CO3, K2CO3, NaHCO3, KHCO3, Mg(OH)2, Ca(OH)2, Ba(OH)2. Optional mixing step (A)

[0090] The optional step (A) comprises bringing into contact (or mixing) the synthesis effluent 1 comprising 5-HMF and the synthesis solvent, e.g. DMSO, with a flow aqueous 27 so as to obtain an aqueous mixture, also called aqueous charge 3 sent to the liquid-liquid extraction step (B).

[0091] The aqueous stream 27 may be composed of pure water, external to the process, and / or water recycled from the process, for example the aqueous stream may advantageously comprise all or part of the intermediate aqueous counter-extract 9 from the backwashing step (C), and / or the water 15 produced in the step (200) of regeneration of the synthesis solvent, in particular during the distillation sub-step (G).

[0092] Preferably, the 5-HMF represents at least 1% by weight of the synthesis effluent 1 introduced in step (A), preferably at least 10% by weight, preferably at least 15% by weight and preferably at most 50% by weight, preferably at most 40% by weight, more preferably at most 30% by weight.

[0093] Preferably, the synthesis solvent (eg DMSO) represents between 30 and 95% by weight of the synthesis effluent 1 introduced in step (A), preferably between 40 and 90% by weight, preferably between 50 and 90% by weight, preferably between 55 and 85% by weight.

[0094] The synthesis effluent 1 introduced in step (A) may also contain water, in a proportion preferably between 0.1 and 30% by weight, preferably between 0.1 and 15% by weight and more preferably between 0.1 and 10% by weight.

[0095] Optionally, the synthesis effluent 1 may also contain humins. The humins represent, in particular, less than 30% by weight of the synthesis effluent 1, preferably less than 20% by weight.

[0096] The aqueous stream 27 comprises, and may consist of, water. When the aqueous stream 27 comprises a fraction of recycled process water, said fraction may comprise at least 60% by weight of water, preferably at least 70% by weight, more preferably at least 80% by weight, even more preferably at least 95% by weight or even 98% by weight of water. The aqueous stream 27 may comprise all or a fraction of the intermediate aqueous counter-extract 9 from step (C). Said intermediate aqueous counter-extract 9 comprises water, synthesis solvent (e.g. DMSO) and optionally 5-HMF. Advantageously, said intermediate aqueous counter-extract 9 contains at least 60% by weight of water, preferably at least 70% by weight of water and more preferably at least 80% by weight of water.

[0097] Advantageously, the aqueous mixture 3 obtained at the end of step (A) contains between 10% and 90% by weight of water, preferably between 20 and 80% by weight of water, preferably between 40 and 75% by weight of water.

[0098] Preferably, step (A) is carried out at a temperature between 0°C and 60°C, preferably between 5°C and 40°C, and is generally carried out at room temperature, i.e. at a temperature between 10°C and 40°C, preferably between 18°C ​​and 25°C.

[0099] By increasing the water content of the synthesis effluent 1 during step (A), a part of the humins present in the synthesis effluent 1 can precipitate. The mixture resulting from the contact of the synthesis effluent 1 with aqueous stream 27 can therefore advantageously be subjected to a liquid-solid separation step before being sent to the liquid-liquid extraction step (B), so as to obtain a liquid separated from suspended solid particles and a solid residue comprising humins and which is preferably removed from the process in the form of a solid stream 2. Such an optional liquid-solid separation step thus makes it possible to eliminate the “humins” which have precipitated in step (A) or upstream. At least part of the liquid obtained is then advantageously sent to the liquid-liquid extraction step (B), said part or preferably all of the liquid advantageously sent to step (B) corresponding to the aqueous mixture 3.Such a liquid-solid separation step in step (A) can be advantageously implemented when the quantity of humins precipitated in the mixture formed by the synthesis effluent 1 and the aqueous stream 27 in step (A) is for example greater than 1% by weight. Humins can be quantified in various ways well known to those skilled in the art, for example by size exclusion chromatography. The optional operation of liquid-solid separation, e.g. filtration, thus makes it possible to eliminate the "humins" which have precipitated. This optional liquid-solid separation step is preferably carried out at a temperature between 0°C and 60°C, preferably between 5°C and 40°C, and generally at room temperature (i.e. between 10°C and 40°C, preferably between 18°C ​​and 25°C). The optional liquid-solid separation step prior to step (B) is a simple solid-liquid separation, and can be carried out by any method known to those skilled in the art, such as by using a filter press, a belt filter, a clarifier, a decanter, a centrifuge, for example a plate centrifuge, said techniques being used alone or in combination, in any order. Preferably, the liquid-solid separation step is a filtration, preferably carried out by a filter press. Liquid-liquid extraction step (B)

[0100] The process according to the invention comprises a step (B) of liquid-liquid extraction of an aqueous feedstock 3, which is optionally the aqueous mixture from step (A), in the presence of an extraction solvent 4, so as to produce an aqueous raffinate 5 and an organic extract 6.

[0101] The aqueous raffinate 5 comprises synthesis solvent (eg DMSO), and the organic extract 6 comprises 5-HMF and extraction solvent. The aqueous raffinate 5 is depleted in 5-HMF and the organic extract 6 is enriched in 5-HMF.

[0102] The liquid-liquid extraction carried out in step (B) advantageously corresponds to washing the aqueous charge 3 with an organic extraction solvent 4. Preferably, the liquid-liquid extraction carried out in step (B) is a countercurrent extraction of the aqueous feedstock 3, preferably obtained in step (A), by an extraction solvent 4. This technique is well known to those skilled in the art. This step (B) is carried out in liquid-liquid extraction means B configured to bring the extraction solvent 4 into contact with the aqueous feedstock 3, preferably countercurrently, and produce the aqueous raffinate 5 depleted in 5-HMF and the organic extract 6 enriched in 5-HMF, and may for example comprise at least one of the following equipment: a battery of mixer-decanters, a column filled with bulk or structured packing, a pulsed column, or even a stirred column.

[0103] The liquid-liquid extraction step (B) is advantageously carried out at a temperature between 0°C and 60°C, preferably between 5°C and 40°C, and generally at room temperature (i.e. between 10°C and 40°C, preferably between 15°C and 30°C, more preferably between 18°C ​​and 25°C).

[0104] Generally, the extraction solvent rate, defined as the mass ratio between the extraction solvent flow rate and the feed entering the extraction step, results from the number of separation stages involved, the choice of extraction solvent and the 5-HMF recovery target defined as the ratio between the amount of 5-HMF entrained in the organic extract 6 and the amount of 5-HMF contained in the aqueous feed 3 sent to the extraction step (B). The targeted recovery rate is preferably between 80 and 100%, preferably between 90% and 99.9% and even more preferably between 95 and 99.9%.

[0105] The extraction solvent rate (mass ratio between the extraction solvent flow rate 4 and the aqueous charge 3) is preferably between 0.2 and 5, preferably between 1 and 3, preferably between 1.5 and 2.5.

[0106] The extraction solvent 4 introduced in step (B) is chosen from organic solvents immiscible with water, so as to form two liquid phases in step (B) and in the backwashing step (C). This property is highly dependent on the relative proportion of the flow rates of feedstock, back-extraction water and extraction solvent used in the process.

[0107] In a non-limiting manner, the extraction solvent is preferably chosen from chlorinated organic solvents, ethers, esters, ketones and aromatic compounds. Preferably the extraction solvent is a chlorinated solvent having between 1 and 10 carbon atoms, hereinafter referred to as C1-C10, an ether having between 2 and 10 carbon atoms (C2-C10), an ester having between 4 and 10 carbon atoms (C4-C10), a ketone having between 3 and 10 carbon atoms (C3-C10), an aldehyde between 1 and 10 carbon atoms (C1-C10), a C4-C10 aromatic compound. Preferably, the extraction solvent is chosen from dichloromethane, diethyl ether, diisopropyl ether, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, thiophene, anisole and toluene. Most preferably, the extraction solvent is methyl isobutyl ketone.

[0108] Advantageously, the extraction solvent is chosen so as to: - have a very high volatility difference with 5-HMF, in particular so as to facilitate its elimination in sub-step (D) of 5-HMF concentration during step (100) of regeneration of the extraction solvent, and limit the degradation of 5-HMF, i.e. so as to present in sub-step (D) a vaporization rate making it possible not to degrade 5-HMF and to minimize the quantity of residual solvent to be eliminated in sub-step (E) of hydrodistillation of step (100), while guaranteeing the absence of liquid phase separation in sub-step (E) of hydrodistillation when the concentrated organic raffinate 10 is brought into contact with water in sub-step (E), and - form, in sub-step (E) of hydrodistillation, a heterogeneous azeotrope with water, preferably rich in solvent, i.e. more than 50% by weight of solvent, preferably more than 60% by weight of solvent and more preferably more than 70% by weight of solvent.Advantageously, said azeotrope of the water / extraction solvent mixture has a boiling temperature significantly lower than that of water, preferably at least 5°C lower than the boiling temperature of water, preferably at least 8°C lower than the boiling temperature of water and preferably at least 10°C lower than the boiling temperature of water.

[0109] Advantageously, the organic solvent streams (extraction solvent) produced in the subsequent steps can be recycled to the liquid-liquid extraction step (B), as extraction solvent. These extraction solvent streams can contain impurities possibly generated during the implementation of the method. Advantageously, the extraction solvent streams produced in the subsequent steps can be distilled, for example periodically, to avoid the accumulation of said impurities.

[0110] Step (B) thus makes it possible to obtain, on the one hand, an aqueous stream depleted in 5-HMF, called aqueous raffinate 5, which contains a large part of the synthesis solvent (e.g. DMSO) initially contained in the aqueous feedstock 3, and on the other hand an organic stream enriched in 5-HMF, called organic extract 6, which contains a large part of the 5-HMF, initially contained in the aqueous feedstock 3, and the extraction solvent 4. This organic extract 6 may also contain synthesis solvent (e.g. DMSO). Preferably, said organic extract 6 contains 5-HMF and synthesis solvent (eg DMSO) in a weight ratio, 5-HMF / synthesis solvent (eg DMSO), of between 50 / 50 and 99 / 01, preferably of between 50 / 50 and 95 / 05, preferably of between 55 / 45 and 90 / 10, more preferably of between 60 / 40 and 85 / 15, preferably of between 65 / 35 and 85 / 15.

[0111] Advantageously, the organic extract 6 is sent directly to step (C) of backwash.

[0112] A fraction of solid particles, formed by precipitated humins, may also be present in step (B). These may be humins precipitated upstream of step (B), for example in the mixing step (A) if it is implemented, still present in the aqueous feed sent to step (B), or humins precipitated in step (B) or even in the backwashing step (C). Step (C) of backwashing

[0113] The method according to the invention comprises a step (C) of backwashing the organic extract 6, with an aqueous solvent 7, so as to produce an intermediate aqueous counter-extract 9 and an organic raffinate 8 comprising 5-HMF and an organic solvent. The intermediate aqueous counter-extract 9 can advantageously be sent in part or in whole to the optional step (A). The organic solvent is in particular composed at least in part of extraction solvent and can optionally comprise synthetic solvent (e.g. DMSO), preferably in small quantities.

[0114] The introduction of an aqueous solvent 7 in step (C) is carried out so as to implement a backwash, according to the general knowledge of a person skilled in the art. The introduction of the aqueous solvent 7 is carried out in such a way that the quantity of aqueous solvent is as low as possible so as to reduce costs, but sufficient to guarantee a weight content of synthesis solvent (e.g. DMSO) in the organic raffinate 8 which is low and preferably less than or equal to 20.0% by weight relative to the weight of the 5-HMF, preferably less than or equal to 10.0% by weight relative to the weight of the 5-HMF, preferably less than or equal to 2.0% by weight relative to the weight of the 5-HMF, very preferably less than or equal to 1.0% by weight relative to the weight of the 5-HMF, for example very preferably between 0.01% and 1.0% by weight relative to the weight of the 5-HMF.

[0115] Advantageously, the aqueous backwash solvent 7 introduced in step (C) comprises at least 95% by weight of water, preferably at least 98% by weight of water (100% being the maximum). The aqueous solvent may optionally comprise synthetic solvent (e.g. DMSO). The effectiveness of the backwash is higher the lower the amount of synthetic solvent (e.g. DMSO) present in the aqueous backwash solvent. The aqueous solvent may comprise at most 1.0% by weight, and preferably at most 0.1% by weight of synthetic solvent (e.g. DMSO). Advantageously, the aqueous backwash solvent 7 comes from the step (200) of regeneration of the synthesis solvent, and thus comprises at least a fraction of the recyclable aqueous effluent 15. In a preferred embodiment of the invention, the aqueous raffinate 5 composed of water and polar aprotic synthesis solvent (egDMSO), produced in step (B), is treated in step (200) of regeneration of the synthesis solvent which comprises a distillation sub-step (G). The water-rich distillate thus obtained at . the outcome of this sub-step (G), also called aqueous effluent 15 recyclable in the process, is advantageously used to form the aqueous backwash solvent 7 in step (C), optionally mixed with additional water, or can be used in the optional mixing step (A) to form the aqueous stream 27, optionally with at least one intermediate aqueous back-extract fraction 9 and / or additional water. Said recyclable effluent 15, e.g. water-rich distillate, may also contain a residual quantity of synthesis solvent (e.g. DMSO), preferably less than or equal to 1% by weight and preferably less than or equal to 0.1% by weight. The residual quantity of synthesis solvent (e.g.DMSO) in the aqueous effluent 15 (the distillate) is all the lower as the distillation from sub-step (G) to step (200) is carried out efficiently, in particular with a number of distillation stages greater than 5, and advantageously suitable reboiling and reflux rates.

[0116] The backwashing step (C) is advantageously a liquid-liquid extraction of an organic stream, in particular of the organic extract 6 obtained in step (B) against the current of the aqueous solvent 7. This technique is well known to those skilled in the art. This step (C) is carried out in backwashing means configured to bring the organic extract 6 into contact with the aqueous solvent 7, preferably countercurrently, and produce an aqueous backextract 9 and an organic raffinate 8 comprising the 5-HMF and an organic solvent. These backwashing means may, for example, comprise at least one of the following equipment: a battery of mixer-decanters, a column filled with bulk or structured packing, a pulsed column, or even a stirred column.

[0117] Step (C) is preferably carried out at a temperature between 0°C and 60°C, preferably between 5°C and 40°C and generally at room temperature (i.e. between 10°C and 40°C, preferably between 15°C and 30°C, more preferably between 18°C ​​and 25°C).

[0118] The weight ratio (weight / weight) of aqueous solvent 7 relative to organic extract 6 is preferably between 0.04 and 5, preferably between 0.07 and 3, preferably between 0.1 and 1.

[0119] Step (C) makes it possible to obtain an aqueous stream advantageously enriched in synthesis solvent (e.g. DMSO), called intermediate aqueous counter-extract 9, preferably containing at least 60% by weight of water, preferably at least 80% by weight of water, and an organic raffinate 8, advantageously depleted in synthesis solvent (e.g. DMSO). The intermediate aqueous counter-extract 9 can advantageously be sent, in part or preferably in full, to the mixing step (A) if it is implemented.

[0120] According to the invention, the organic raffinate 8 produced in step (C) is sent to step (100) of regeneration of the extraction solvent, in particular to sub-step (D) of concentration in 5-HMF.

[0121] Step (100) of regeneration of the extraction solvent

[0122] The method according to the invention comprises a step of regenerating the extraction solvent (100), carried out in means of the step of regenerating the extraction solvent 100, said step (100) comprising: - a 5-HMF concentration sub-step (D) operating by eliminating at least a portion of the organic solvent from the organic raffinate 8, carried out by 5-HMF concentration means adapted to such elimination, and producing a concentrated organic raffinate 10 comprising 5-HMF and residual organic solvent, as well as a first stream comprising, and preferably consisting of, organic solvent 11, and - a hydrodistillation sub-step (E) implemented by distillation in the presence of water 14 of the concentrated organic raffinate 10, carried out in a suitable hydrodistillation unit, and producing the aqueous solution of 5-HMF 12 targeted by the method and the installation according to the invention, and a second stream comprising organic solvent 13. Sub-step (D) of 5-HMF concentration

[0123] The organic solvent present in the organic raffinate 8 sent to sub-step (D), and at least partly eliminated during this sub-step (D), is advantageously composed in whole or in part of the extraction solvent and possibly of synthesis solvent (eg DMSO).

[0124] Preferably, in sub-step (D), the elimination of a portion of the organic solvent is carried out by vaporization, for example in 5-HMF concentration means adapted to such elimination by vaporization such as a distillation column at atmospheric pressure or under vacuum, in an evaporator typically comprising one or more heat exchangers and a separation flask, or by any other method and associated device known to those skilled in the art.

[0125] According to this preferred embodiment, the vaporization of the organic solvent is advantageously carried out at atmospheric pressure or under vacuum, preferably at a pressure of between 0.01 MPa and 0.1 MPa, preferably under vacuum at a pressure of between 0.01 MPa and 0.09 MPa, more preferably of between 0.01 MPa and 0.05 MPa, so as to limit the temperature of the liquid and therefore the degradation of the 5-HMF. Preferably, the temperature of the liquid is kept less than or equal to 130°C, preferably kept less than or equal to 100°C, preferably kept less than or equal to 90°C. The pressure level, in particular vacuum, to be applied to reach these temperatures is of course dependent on the organic solvent and more particularly on the extraction solvent used and on the vaporization rate of the organic solvent.

[0126] Sub-step (D) is preferably implemented with a mass rate of vapor rization (or evaporation rate), corresponding to the mass of vaporized organic solvent relative to the mass of the organic raffinate 8 from the backwashing step (C) (more particularly the mass quantity of the stream 11 relative to the mass quantity of the organic raffinate 8), of at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 75%, preferably at least 80% and preferably at most 99%. Advantageously, the vaporization rate is defined as a function of the extraction solvent so as not to degrade the 5-HMF, but also in order to minimize the quantity of residual solvent to be removed in the hydrodistillation sub-step (E) while guaranteeing the absence of liquid phase separation during hydrodistillation (i.e. while guaranteeing that the liquid phase remains single-phase).

[0127] Thanks to the combination of all the operating conditions of the preceding steps, the concentrated organic raffinate 10 obtained at the end of sub-step (D) very advantageously has a 5-HMF content of at least 30% by weight relative to the weight of the concentrated organic raffinate, preferably at least 40% by weight, preferably at least 50% by weight, and preferably at most 95% by weight, preferably at most 90% by weight and preferably at most 85% by weight relative to the weight of the concentrated organic raffinate 10. In other words, the concentrated organic raffinate 10 preferably has a residual organic solvent content of at least 5% by weight relative to the weight of the concentrated organic raffinate, preferably at least 10% by weight, and preferably at most 60% by weight, preferably at most 50% by weight, preferably at most plus 40% by weight, relative to the weight of the concentrated organic raffinate 10.

[0128] Advantageously, the organic solvent vaporized during sub-step (D) forms a first stream 11 comprising, preferably consisting of, organic solvent and is preferably recycled to the liquid-liquid extraction step (B).

[0129] Preferably, the first stream 11 is recycled, in whole or in part, to the liquid-liquid extraction step (B), for example forming at least part of the organic solvent stream 4.

[0130] According to one or more embodiments, before being recycled, in whole or in part, to step (B), said first stream 11 undergoes a liquid-liquid separation step, preferably by condensation after cooling by passing through a water cooler then separation in a flask, making it possible to separate the water from the organic solvent which concentrates in the stream recycled to step (B), the water separated in the form of a stream 18 preferably joining the aqueous stream 15 from the distillation sub-step of the step (200) of regeneration of the synthesis solvent in order to supply steps where a water stream is required such as the backwashing step (C) or the hydrodistillation sub-step (E).

[0131] Advantageously, the concentrated organic raffinate 10 is sent to the hydrodistillation sub-step (E).

[0132] According to the invention, heat exchange means are configured to heat the organic raffinate 8 from the backwashing step (C) and sent to the sub-step (D), and / or the aqueous raffinate 5 from the liquid-liquid extraction step (B), with at least one gas phase produced during an evaporation sub-step of the synthesis solvent regeneration step (200) in at least one evaporation section of the synthesis solvent regeneration means.

[0133] [Fig.3] and [Fig.4] illustrate such heat exchange means, integrated according to certain embodiments in the installation and the method according to the invention, in particular integrated in the 5-HMF concentration means of the 5-HMF concentration sub-step (D) during the regeneration of the extraction solvent, and in an evaporation section of an evaporation sub-step during the regeneration of the synthesis solvent.

[0134] Advantageously, the organic raffinate 8 is heated with a gas phase produced during at least one evaporation sub-step of the synthesis solvent regeneration step (200). The heat exchange means then comprise at least one heat exchanger (E2 or El') configured to heat the organic raffinate 8 with said gas phase (203 or 223 / 224).

[0135] [Fig. 3] illustrates one or more embodiments in which the organic raffinate 8 is heated successively in a first heat exchanger E1 (reheated outgoing flow of organic raffinate 101) and a second heat exchanger E2 (reheated outgoing flow of organic raffinate 102) positioned in series, with respectively a first gas phase 105 and a second gas phase 203, then in a first external flow heat exchanger 107, of the low pressure steam type (or "LPS" for Low pressure steam according to the English terminology), and the gas-liquid separation of the reheated organic raffinate 103 is carried out in a first separation tank VI producing the first gas phase 105. Advantageously, the 5-HMF concentration means then successively comprise: the first heat exchanger E1, the second heat exchanger E2, the first external flow heat exchanger 107 and the first separation tank VL

[0136] The second gas phase 203 sent to the second heat exchanger E2 comes from the evaporation sub-step F1 of the step (200) of regeneration of the synthesis solvent. More details on the evaporation during the regeneration of the synthesis solvent (200) in relation to [Fig. 3] are given later in the descriptive part corresponding to step (200).

[0137] The first gas phase 105 is cooled in the first heat exchanger E1 to give a flow 106 sent to the liquid-liquid extraction step (B) and possibly step (C) and / or (E). This flow 106 corresponds to the flow 11, or even also includes the water flow 18, of FIGS. 1 and 2.

[0138] From the first separation tank VI, the liquid stream 104 separated from the gas phase 105 corresponds to the concentrated organic raffinate 10 shown in FIGS. 1 and 2, and is sent to the hydrodistillation sub-step (E). A portion of said liquid stream 104 is preferably recycled upstream of the first exchanger E1 (not shown in [Fig.3]), thus rotating in circles, to reduce the vaporization rate in the exchangers while minimizing the residence time of the liquid.

[0139] [Fig.4] illustrates one or more other embodiments, in which the organic raffinate 8 is heated in two heat exchangers positioned in series (E1', E2') with respectively two gas phases produced during said at least one evaporation sub-step of the synthesis solvent regeneration step (200). The heat exchange means thus comprise the two successive heat exchangers (E1', E2') configured to heat the organic raffinate 8 with respectively said two gas phases (223 / 224 and 227). In particular, according to this or these embodiments, the 5-HMF concentration sub-step advantageously comprises the heating of said organic raffinate 8 successively in a first heat exchanger E1' (reheated outgoing flow of organic raffinate 108) and a second heat exchanger E2' (reheated outgoing flow of organic raffinate 109) positioned in series with respectively a first gas phase 223 / 224 and a second gas phase 227, then in a first external flow heat exchanger 113, of the LPS type, and the gas-liquid separation of the reheated organic raffinate 110 from the first external flow heat exchanger 113 in a first separation tank VI'. Advantageously, according to this or these embodiments, the 5-HMF concentration means comprise substantially the same equipment as those illustrated in [Fig. 3], and thus comprise successively: the first heat exchanger E1' and the second heat exchanger E2' positioned in series with the first exchanger E1', a first external flow heat exchanger, of the LPS 113 type, and a first separation tank VI'.

[0140] The first gas phase 223 / 224 sent to the first heat exchanger El' comes from a second evaporation sub-step (F2) of the step (200) of regeneration of the synthesis solvent.

[0141] The second gas phase 227 sent to the second heat exchanger E2' comes from the first evaporation sub-step (F1) of the step (200) of regeneration of the aprotic polar synthesis solvent.

[0142] More details on the evaporation sub-steps during the regeneration of the synthesis solvent (200) in relation to [Fig.4] are given later in the descriptive part corresponding to step (200).

[0143] From the first separation flask VI', a liquid stream 111 separated from the gas phase 112 corresponds to the concentrated organic raffinate 10 shown in Figures 1 and 2, and is sent to the hydrodistillation sub-step (E). A portion of said liquid stream 111 is preferably recycled upstream of the first exchanger El' (not shown in [Fig.4]), thus rotating in circles, to reduce the vaporization rate in the exchangers while minimizing the residence time of the liquid. The gas phase 112 from the tank VI' is sent to the liquid-liquid extraction step (B) and possibly step (C) and / or (E) in the case where a liquid-liquid separation is carried out, for example by condensation after cooling by passage through a water cooler then separation in a tank, to separate the water from the extraction solvent, as already described above: this flow 112 in fact corresponds to the flow 11, or even also includes the water flow 18, of figures 1 and 2.

[0144] The 5-HMF concentration means (D) can thus comprise an additional separation tank configured to receive the gas phase from the first separation tank (VI, VI') and previously condensed in a heat exchanger, such as the exchanger E1 in [Fig. 3] or an external flow heat exchanger, of the water cooler type, and produce a flow rich in extraction solvent 11 and a flow rich in water 18 which can be recycled in the process.

[0145] By heat exchanger, we conventionally mean a device for transferring thermal energy from one fluid to another without mixing them. In other words, this is an indirect contact between the fluids. The heat flow passes through the exchange surface which separates the fluids. Any heat exchanger known to those skilled in the art and adapted to the operating conditions of the sub-steps of concentration in 5-HMF (D) in step (100) and evaporation (F1, F2) in step (200) may be suitable, for example a tube / shell, plate, spiral or any other suitable technology heat exchanger. In the present description, a heat exchanger, as used in sub-steps (D) and (F1, F2), is understood as operating only with fluids from the process, typically effluents produced in the process steps, unlike external flow heat exchangers, understood as heat exchangers in which one of the fluids involved in the heat transfer is external to the process, for example water vapor external to the process in the case of an LPS type external flow heat exchanger, such as exchangers 107, 212 and 213 of [Fig. 3] and exchangers 113, 216 and 221 of [Fig. 4]. Sub-step (E) of hydrodistillation

[0146] The process according to the invention comprises a hydrodistillation sub-step (E) carried out by distillation in the presence of water of the concentrated organic raffinate 10 resulting from the 5-HMF concentration sub-step (D), and producing the aqueous solution of 5-HMF 12, and a second stream 13 comprising, and preferably consisting of, organic solvent.

[0147] Hydrodistillation (E) advantageously makes it possible to eliminate, at least in part, the residual organic solvent not eliminated during step (D). The residual organic solvent eliminated during the hydrodistillation sub-step, i.e. the second stream 13 comprising organic solvent, can advantageously be recycled to the liquid-liquid extraction step (B), alone or in a mixture with the first stream 11 from step (D).

[0148] Advantageously, a water-based stream 14 feeds the hydrodistillation step. The water-based stream 14 introduced into the hydrodistillation step preferably contains more than 95% by weight of water, preferably more than 98% by weight of water.

[0149] The water-based stream 14 may be pure water, possibly external to the process, which makes it possible to further minimize the residual synthesis solvent content (eg DMSO) in the aqueous solution 12 of 5-HMF produced in the hydrodistillation (E).

[0150] Water isolated within the process can also be used to feed the hydrodistillation sub-step, making it possible to limit the operating costs of the process and its environmental impact. Typically, if the sugar feedstock of the dehydration step is a sugar syrup at 70% by weight in water, approximately 1 tonne of water is available at the end of the dehydration step (the water from the sugar feedstock and the water produced during the dehydration reaction) per tonne of 5-HMF produced. This water, which is advantageously recovered, needs to be treated before being released into the environment.The process according to the invention can then advantageously use said water from the sugar feed and / or from the dehydration step to produce, at the end of the hydrodistillation step, an aqueous solution of 5-HMF concentrated preferably at 30% by weight or more, preferably at 40% by weight or more, and thus reduce the reprocessing costs of the process and its environmental impact.

[0151] Advantageously, the water-based stream 14 introduced into the hydrodistillation sub-step (E) may correspond to at least a fraction, possibly all, of the aqueous effluent 15 (distillate) produced from the distillation sub-step (G) in the step (200) of regeneration of the synthesis solvent. Said distillate may possibly contain a residual quantity of synthesis solvent (eg DMSO).

[0152] Advantageously, during hydrodistillation (E), the extraction solvent used in the process forms a heterogeneous azeotrope with water, said azeotrope preferably being rich in extraction solvent, preferably comprising more than 50% by weight of extraction solvent, preferably more than 60% by weight of extraction solvent and preferably more than 70% by weight of extraction solvent. Advantageously, said water / extraction solvent azeotrope has a boiling point significantly lower than that of water, preferably at least 5°C lower than the boiling point of water, preferably at least 8°C lower than the boiling point of water and preferably at least 10°C lower than the boiling point of water.

[0153] Thus, after contacting the concentrated organic raffinate 10 with the water-based stream 14, the residual organic solvent can be easily removed without degradation of the 5-HMF.

[0154] The hydrodistillation sub-step may be carried out at atmospheric pressure or under vacuum and in particular at a pressure of between 0.001 MPa and 0.1 MPa, preferably under vacuum at a pressure of between 0.005 MPa and 0.08 MPa. Advantageously, the hydrodistillation sub-step is carried out under vacuum, in particular at a pressure of between 0.001 MPa and 0.1 MPa, preferably between 0.005 MPa and 0.08 MPa, so as to facilitate the removal of the residual organic solvent without degradation of the 5-HMF.

[0155] Advantageously, the hydrodistillation sub-step is carried out in a distillation column, preferably at a column bottom temperature of less than or equal to 140°C, preferably less than or equal to 130°C, preferably less than or equal to 120°C, preferably less than or equal to 110°C and preferably less than or equal to 100°C, so as to facilitate the removal of the residual organic solvent without degradation of the 5-HMF.

[0156] In a particular embodiment, during the hydrodistillation sub-step, the concentrated organic raffinate 10 and the water-based stream 14 are mixed before introduction into a distillation column and the mixture is introduced at an intermediate point of the distillation column.

[0157] In another particular embodiment, during the hydrodistillation sub-step, the concentrated organic raffinate 10 is introduced into the upper part of the distillation column, preferably into the upper half of the distillation column, while the water-based stream 14 is also introduced into the distillation column. Mixing with the water-based stream is then carried out within the distillation column.

[0158] Given the formation of a heterogeneous azeotrope between the water and the extraction solvent during hydrodistillation, condensation of the overhead vapors from the distillation column generates two liquid phases: a phase rich in water which can advantageously be returned to the column as reflux, and a phase rich in organic solvent 13 which can advantageously be recycled to the liquid-liquid extraction step (B).

[0159] Advantageously, the aqueous solution 12 of 5-HMF obtained at the end of the hydrodistillation sub-step has a quantity of 5-HMF of at least 30% by weight, preferably at least 40% by weight, and preferably less than 90% by weight, preferably less than 85% by weight and more preferably less than 80% by weight, the percentages being given by weight of 5-HMF relative to the weight of aqueous solution of 5-HMF obtained at the end of the hydrodistillation sub-step.

[0160] The installation and the method according to the invention advantageously make it possible to produce an aqueous solution of 5-HMF having a weight content of synthesis solvent (eg DMSO) less than or equal to 10% by weight relative to the weight of 5-HMF, preferably less than or equal to 5% by weight relative to the weight of 5-HMF and preferably less than or equal to 3% by weight relative to the weight of 5-HMF.

[0161] Step (200) of regeneration of the synthesis solvent

[0162] The method according to the invention comprises a step of regenerating the synthesis solvent (eg DMSO) (200), carried out by means of regenerating the synthesis solvent 200, said step (200) comprising: - at least one evaporation sub-step (F or F1, F2 and F3) for removing at least part of the impurities from said aqueous raffinate (5), carried out in at least one evaporation section suitable for such removal, and producing a liquid stream concentrated in impurities 17 or 26 and at least one stream comprising water and synthesis solvent (19, 22, 24, 25), and - a distillation sub-step (G) implemented by distillation of at least part of the water-synthesis solvent stream (19, 22, 24, 25), carried out in a suitable distillation section, and producing an aqueous effluent 15 and a synthesis solvent stream (eg DMSO) 16 recyclable in the process.

[0163] Other streams from the process comprising a mixture of water and synthesis solvent (eg DMSO) can be sent to the distillation sub-step (G) of step (200), such as a water-DMSO mixture from the optional step of dehydrating sugars into 5-HMF (A') when the process includes such a step. Evaporation sub-step(s) (F1, F2, F3)

[0164] The method according to the invention comprises, in the step of regenerating the synthesis solvent, at least one evaporation sub-step (F or F1, F2, and F3) to remove at least part of the impurities from the aqueous raffinate (5) and produce the liquid stream concentrated in impurities (17, 26) and at least one stream comprising water and synthesis solvent (19, 22, 24, 25).

[0165] The impurities removed are in particular heavy impurities such as humins or unconverted sugars.

[0166] Said at least one evaporation sub-step is preferably carried out at a temperature between 80°C and 130°C, preferably between 80°C and 120°C, preferably initially between 100°C and 120°C, and at a pressure between 0.0001 MPa and 0.100 MPa. The temperature during the evaporation step(s) is chosen so as to limit the degradation of the synthesis solvent (e.g. DMSO).

[0167] Said at least one evaporation section comprises heat exchange means, such as one or more heat exchangers and one or more external flow exchangers, and gas-liquid separation means such as one or more separation tanks.

[0168] The stream(s) of water and synthesis solvent (19, 22, 24, 25) are sent to the distillation sub-step (G) described later, to produce streams of water and synthesis solvent which can be recycled in the process.

[0169] It is at least one gas phase (not detailed in figures 1 and 2) produced during said at least one evaporation sub-step which is involved in heat exchanges according to the invention, in particular to heat the aqueous raffinate 5 resulting from step (B) and / or the organic raffinate 8 resulting from sub-step (D).

[0170] [Fig.l] illustrates an embodiment of the system and method according to the invention comprising a single evaporation sub-step (F), whereas [Fig.2] illustrates an embodiment in which the evaporation is carried out in three successive sub-steps (F1, F2 and F3). In any case, according to an essential aspect of the invention, at least one gas phase is produced during an evaporation sub-step to heat, in heat exchange means, the aqueous raffinate 5 and / or said organic raffinate 8, said gas phase being produced in sub-step (F) of the embodiment illustrated in [Fig.l], and produced in the evaporation sub-steps (F1) and (F2) of the embodiment illustrated in [Fig.2],

[0171] According to the embodiment illustrated in [Fig.l], the single evaporation sub-step (F) is preferably carried out at a temperature between 80°C and 130°C, preferably between 80°C and 120°C, preferentially between 100°C and 120°C, and at a pressure between 0.0001 MPa and 0.100 MPa. The temperature is chosen so as to limit the degradation of the aprotic polar synthesis solvent (e.g. DMSO). Advantageously, the pressure is adjusted so as to limit the loss of synthesis solvent in the process (i.e. in the stream 17) while maintaining good operability, in particular an acceptable viscosity of the liquid stream concentrated in impurities to be removed 17.

[0172] The evaporation section in this sub-step (F) comprises heat exchange means, such as one or more heat exchangers (involving internal flows) and one or more external flow exchangers, and gas-liquid separation means such as one or more separation tanks. These heat exchange and gas-liquid separation means may be similar to those described below for the sub-step evaporation (Fl) or the evaporation sub-step (F2) of [Fig.2].

[0173] The aqueous raffinate 5 is sent to the evaporation sub-step (F), and is preferably heated in at least one heat exchanger and optionally one or more external flow exchangers, then the heated flow is sent to one or more separation tanks. The following flows are produced: a flow comprising water and synthesis solvent 19, sent to the distillation sub-step (G), a liquid flow concentrated in impurities removed from the process, and a flow comprising water and extraction solvent 20 advantageously sent to the hydrodistillation sub-step (E). According to the embodiment illustrated in [Fig.2], the three successive evaporation sub-stages (F1, F2, F3), implemented in the three successive evaporation sections (F1, F2, F3), make it possible to progressively concentrate the impurities of the aqueous raffinate 5 in a liquid phase, the third evaporation sub-stage in the third evaporation section F3 producing a liquid stream of impurities to be evacuated from the system 26 and an effluent of water and synthesis solvent 25 sent to the distillation sub-stage (G) in the distillation section of stage (G).

[0174] Preferably, the first evaporation sub-step (F1) is carried out at a temperature preferably between 80°C and 130°C, preferably between 80°C and 120°C, preferentially between 100°C and 120°C, and preferably at a pressure between 0.01 MPa and 0.1 MPa, preferentially between 0.05 MPa and 0.1 MPa. The temperature is in particular chosen so as to limit the degradation of the synthesis solvent (e.g. DMSO). The pressure is in particular chosen so that the loss of synthesis solvent (e.g. DMSO) in the vapor phase is limited, and for example remains less than 1% by weight (mass of the synthesis solvent in the vapor phase). The first evaporation section comprises one or more heat exchangers and gas-liquid separation means such as one or more separation tanks, and preferably comprises one or two heat exchangers involving internal flows, one heat exchanger with external flow, and two separation tanks. The first evaporation sub-step (F1) produces the following flows: a flow comprising water and synthesis solvent 22, sent to the distillation sub-step (G), a liquid flow enriched with impurities 21 sent to the second evaporation sub-step (F2), and a flow comprising water and extraction solvent 20 advantageously sent to the hydrodistillation sub-step (E).

[0175] Preferably, the second evaporation sub-step (F2) is carried out at a temperature preferably between 80 and 130°C, preferably between 80°C and 120°, preferentially between 100°C and 120°C, and preferably at a pressure between 0.001 MPa and 0.1 MPa, preferentially between 0.005 MPa and 0.05 MPa, more preferentially between 0.01 MPa and 0.03 MPa. The second evaporation sub-step aims in particular to minimize the synthetic solvent content (e.g. DMSO) to avoid losses of said solvent with the flow of impurities to be removed. The rest of the water is also evaporated in this second evaporation sub-step. For example, a synthetic solvent content of between 30% and 40% by weight is targeted in the liquid flow enriched with impurities 23 from sub-step (F2), in order to maintain an acceptable viscosity of said flow for good operability. The second evaporation section comprises one or more heat exchangers and gas-liquid separation means such as one or more separation tanks, and preferably comprises an external flow heat exchanger and a separation tank or a heat exchanger involving internal flows, an external flow heat exchanger, and a separation tank.

[0176] The second evaporation sub-step (F2) produces the following streams: a stream comprising water and synthesis solvent 24, sent to the distillation sub-step (G), a liquid stream even more enriched in impurities 23 sent to the third evaporation sub-step (F3).

[0177] Preferably, the third evaporation sub-step (F3) is carried out in a third evaporation section (F3), not detailed in Figures 3 and 4, producing a liquid stream of impurities (final) discharged from the process 26 and an effluent comprising water and synthesis solvent 25 sent to the distillation sub-step (G) in the distillation section G.

[0178] Preferably, the third evaporation sub-step is carried out at a temperature preferably between 80°C and 130°C, preferably between 80°C and 120°C, preferentially between 100°C and 120°C, and preferably at a pressure between 0.0001 MPa and 0.0200 MPa, preferentially between 0.0002 MPa and 0.0100 MPa, preferentially between 0.0005 MPa and 0.0100 MPa, preferentially between 0.0010 MPa and 0.010 MPa. Preferably, the third evaporation section comprises a scraped film evaporator (Thin film Evaporator TFE in English terminology).

[0179] Figures 3 and 4 illustrate embodiments in which the evaporation in the synthesis solvent regeneration step is carried out in three successive sub-steps (F1, F2 and F3) as illustrated in [Fig.2]. Only the first two evaporation sub-steps (F1) and (F2) are illustrated in Figures 3 and 4, through the representations of certain equipment of the heat exchanger and separation tank type. Figures 3 and 4 also show at least part of the 5-HMF concentration means of the extraction solvent regeneration step (100) already described above.

[0180] Thus, according to the embodiment shown in [Fig.3], the first evaporation sub-step (F1) is carried out in a first evaporation section successively comprising the third heat exchanger E3, the second heat exchanger external flow heat exchanger 212, of LPS type, the second separation tank V2, the second heat exchanger E2, which is common to the 5-HMF concentration means of step (D), and the third separation tank V3. The second evaporation sub-step (F2) is carried out in a second evaporation section configured to receive the liquid flow 204 from said second separation tank V2 and successively comprising a third external flow heat exchanger 213, of LPS type, and a fourth separation tank V4.

[0181] It is recalled that in the 5-HMF concentration step (D) in [Fig.3], the organic raffinate 8 is heated successively in a first heat exchanger E1 and a second heat exchanger E2 positioned in series with respectively a first gas phase 105 and a second gas phase 203, then in a first external flow heat exchanger 107, of the LPS type, and the reheated organic raffinate 103 is separated in a first separation tank VI producing the first gas phase 105 and a liquid phase 104 sent to the sub-step (E).

[0182] In [Fig. 3], in the first evaporation sub-step (F1), the aqueous raffinate 5 is heated successively in the third heat exchanger E3 with a third gas phase 206 and in the second external flow heat exchanger 212, then a gas-liquid separation of the heated aqueous raffinate 202 is carried out in the second separation tank V2 producing the second gas phase 203 and a liquid flow 204, then a gas-liquid separation is carried out in the third separation tank V3 of the second gas phase 203 after its cooling in the form of flow 209 in the second heat exchanger E2 common to the 5-HMF concentration sub-step (D). The third separation flask V3 separates a gas phase 211 containing mainly water and possibly extraction solvent, sent to the hydrodistillation sub-step (E), and a liquid phase 210 comprising water and synthesis solvent (egDMSO) sent to the distillation sub-step (F). The second cooled gas phase 225 from the second heat exchanger E2' is sent to the distillation sub-step (G). In the second evaporation sub-step (F2), the liquid stream 204 from the separation tank V2 is heated in the third external flow heat exchanger 213, and a gas-liquid separation of the heated liquid stream 205 is carried out in the fourth separation tank V4 producing the third gas phase 206. The liquid phase 207 from the fourth separation tank V4 is sent to the third evaporation step (F3) to evacuate a liquid stream of impurities and produce a mixture comprising water and synthesis solvent sent to the distillation sub-step (G). The third gas phase 206, comprising water and synthesis solvent, and cooled by its passage through the third heat exchanger E3, forms a flow 208 which is sent to the distillation sub-step (G).

[0183] Thus, in this embodiment shown in [Fig.3], the advantageous heat exchanges are carried out in: - the first heat exchanger E1 and the second heat exchanger E2 configured to successively heat the organic raffinate 8 with respectively the first gas phase 105 from the first separation tank VI and the second gas phase 203 from the second separation tank V2, and in - the third heat exchanger E3 configured to heat the aqueous raffinate 5 with the third gas phase 206 from the fourth separation tank V4. These advantageous heat exchanges therefore involve 3 heat exchangers carrying out thermal exchanges between flows involved in the regeneration of the extraction solvent and the regeneration of the synthesis solvent.

[0184] In [Fig.4], the first evaporation sub-step (F1) is carried out in a first evaporation section successively comprising a third heat exchanger E3', a second external flow heat exchanger 216, of the LPS type, a second separation tank V2' and a third separation tank V3'. The second evaporation sub-step (F2) is carried out in a second evaporation section configured to receive a liquid flow 217 from said second separation tank V2' and successively comprising a fourth heat exchanger E4', a third external flow heat exchanger 221, of the LPS type, and a fourth separation tank V4'.

[0185] It is recalled that in the 5-HMF concentration step (D) in [Fig.4], the organic raffinate 8 is heated successively in the first heat exchanger El' (reheated outgoing flow of organic raffinate 108) and the second heat exchanger E2' (reheated outgoing flow of organic raffinate 109) positioned in series with respectively the first gas phase 223 / 224 and the second gas phase 227, then in the first external flow heat exchanger 113, and the gas-liquid separation of the reheated organic raffinate 110 from the first external flow heat exchanger 113 is carried out in a first separation tank VI'.

[0186] In [Fig.4], in the first evaporation sub-step (F1), the aqueous raffinate 5 is heated successively in the third heat exchanger E3' with a third gas phase 218 and in the second external flow heat exchanger 216, and said third gas phase 218 and the liquid stream 217 are separated in the second separation tank V2' from the heated aqueous raffinate 215. A gas-liquid separation is then carried out in a fourth separation tank V4' of the third gas phase 218 after it has been cooled in the form of the stream 226 in the third heat exchanger E3' producing the second gas phase 227 which is sent to the second heat exchanger E2' in the 5-HMF concentration step (D), and a liquid stream 228 sent to the distillation step (G). The second gas phase cooled 225 from the second heat exchanger E2' is sent to the distillation sub-step (G). In the second evaporation sub-step (F2), the liquid stream 217 from the separation tank V2' is successively heated in the fourth heat exchanger E4' (heated stream 219) and in the third external flow heat exchanger 221 (heated stream 220), then a gas-liquid separation of the heated liquid stream 220 is carried out in the third separation tank V3' producing the first gas phase 223, cooled in the form of a stream 224 in the fourth heat exchanger E4' before it is sent to the first heat exchanger E1' in the 5-HMF concentration step (D), and a liquid phase 222 sent to the third evaporation step (F3) to evacuate a liquid stream of impurities and produce a mixture comprising water and synthesis solvent sent to the distillation sub-step (G).

[0187] Thus, in this embodiment shown in [Fig.4], the advantageous heat exchanges are carried out in: - the first heat exchanger E1' and the second heat exchanger E2' configured to successively heat the organic raffinate 8 with respectively the first gas phase 223 coming from the fourth separation tank V4' and cooled in the form of a flow 224 in the fourth heat exchanger E4', and the second gas phase 227 coming from the third separation tank V3', - the third heat exchanger E3' configured to heat the aqueous raffinate 5 with the third gas phase 218 from the second separation tank V2', and in - the fourth heat exchanger E4' configured to heat a reheated and separated flow from the aqueous raffinate 5 with the first gas phase 223 from the fourth separation tank V4'. These advantageous heat exchanges therefore involve 4 heat exchangers carrying out thermal exchanges between flows involved in the regeneration of the extraction solvent and the regeneration of the synthesis solvent. Distillation sub-step (G)

[0188] The distillation sub-step (G) makes it possible to finalize the regeneration of the synthesis solvent (eg DMSO).

[0189] The distillation sub-step (G) implements a distillation section advantageously comprising a distillation column, or several separate pieces of equipment, which may be two distillation columns. Preferably, a distillation column is implemented, at a temperature at the top of the column preferably between 25°C and 60°C, preferably between 45°C and 55°C, for example approximately 50°C, preferably at a temperature at the bottom of the column between 80°C and 140°C, preferably between 100°C and 130°C, for example approximately 120°C, preferably at a pressure between 0.001 MPa and 0.05 MPa, preferably between 0.005 MPa and 0.02 MPa and preferably between 0.008 MPa and 0.012 MPa, and preferably with a reflux ratio of between 0.01 and 0.50, preferably between 0.05 and 0.20.

[0190] Thus, the aqueous raffinate 5 produced in the liquid-liquid extraction step (B) comprising water and synthesis solvent (e.g. DMSO), and optionally the water-synthesis solvent mixture (e.g. DMSO) recovered in the optional dehydration step (A'), are evaporated during the evaporation sub-step(s), then at least one stream of water and synthesis solvent is recovered (19 in [Fig.l], 22, 24 and 25 in [Fig.2]) and distilled, preferably under vacuum, so as to produce a residue 16 rich in synthesis solvent (e.g. DMSO) on the one hand, a distillate 15 rich in water (corresponding to the aqueous effluent) on the other hand. By rich is meant here at least 95% by weight, preferably at least 98% by weight.

[0191] A portion or all of the water-rich distillate, or aqueous effluent 15, may advantageously be recycled to the backwashing step (C) as aqueous solvent for carrying out the backwashing step and / or to the hydrodistillation sub-step (E) in step (100) as aqueous stream. Said water-rich distillate may also be, in whole or in part, recycled as water introduced into the optional mixing step (A).

[0192] The residue rich in synthesis solvent 16 (eg DMSO) can advantageously be introduced into the optional dehydration step (A) directly or after distillation, allowing the removal of heavy products which could accumulate.

[0193] The residual quantity of synthesis solvent (eg DMSO) in the aqueous effluent produced at the end of the distillation sub-step (G) is all the lower the more efficiently the distillation is carried out according to the knowledge of a person skilled in the art. The same applies to the residual quantity of water in the residue rich in synthesis solvent (eg DMSO), for example the residue rich in synthesis solvent 16 contains less than 0.1% by weight of water. Examples

[0194] The examples below aim to show some of the advantages of the method and the installation according to the invention, operated according to the embodiments shown in Figures 3 and 4, together [Fig.2]. Thus, configuration A is that of the embodiment according to [Fig.3], involving the three heat exchangers E1, E2 and E3 operated in the sub-steps of concentration in 5-HMF (D) and evaporation (F1) and (F2), and configuration B is that of the embodiment according to [Fig.4], involving the four heat exchangers E1', E2', E3' and E4' operated in the sub-steps of concentration in 5-HMF (D) and evaporation (F1) and (F2).

[0195] Table 1 below summarizes the operating conditions operated in the 5-HMF concentration means and in the first and second evaporation sections of the process according to the invention.

[0196] Table 2 below summarizes the operating conditions of the heat exchanges carried out in the heat exchangers involving process flows according to the invention according to configuration A ([Fig.3]).

[0197] Table 3 below summarizes the operating conditions of the heat exchanges carried out in the heat exchangers involving process flows according to the invention according to configuration B ([Fig.4]).

[0198] [Tables] Configuration A (fig.3) Configuration B (fig.4) Stage (D) (F7) (F2) (D) (F7) (F2) Tank VI V2 V3 V4 vr V2' V3' V4' Temperature (°C) 90 120 100 120 90 120 100 120 Pressure (MPa) 0.015 0.090 0.089 0.015 0.015 0.090 0.089 0.015

[0199] [Tables2] Configuration A (fig.3) Exchanger Cold side Hot side Power (MW) No. inlet / outlet flow Pe (MPa) Te (°C) Ts (°C) No. inlet / outlet flow Pe (MPa) Te (°C ) Ts (°C) El 8 / 101 0.015 48 56 105 / 106 0.015 90 56 0.59 E2 101 / 102 0.015 56 82 203 / 209 0.090 120 98 1.63 E3 5 / 201 0.09 35 100 206 / 208 0.015 120 79 0.75

[0200] In Table 2 above, Pe and Te are respectively the pressure and temperature at the inlet of the exchanger, and Ts is the temperature at the outlet of the exchanger. The power corresponds to the thermal power exchanged in heat exchangers.

[0201] [Tables3] Configuration B (fig.4) Exchanger Cold side Hot side Power (MW) No. inlet / outlet flow Pe (MPa) Te (°C) Ts (°C) No. inlet / outlet flow Pe (MPa) Te (°C ) Ts (°C) El' 8 / 108 0.015 37 51 224 / 225 0.015 84 71 0.29 E2' 108 / 109 0.015 51 81 227 / 229 0.089 100 73 1.89 E3' 5 / 214 0.090 35 102 218 / 226 0.090 120 100 1.01 E4' 217 / 219 0.015 76 106 223 / 224 0.015 120 84 0.64

[0202] In Table 3 above, Pe and Te are respectively the pressure and temperature at the inlet of the exchanger, and Ts is the temperature at the outlet of the exchanger. The power corresponds to the thermal power exchanged in heat exchangers.

[0203] Table 4 below summarizes the results in terms of power (thermal power exchanged in heat exchangers) involved in thermal exchanges and consumption in hot utilities, for configuration A ([Fig.3]), configuration B ([Fig.4]), and a comparative process without thermal integration.

[0204] [Tables4] Without thermal integration Configuration A Configuration B Number of heat exchangers “E” involving 2 flows from the process 0 3 4 Energy exchanged in the exchangers “E” (MW) 0 2.97 3.83 Hot utilities consumption (MW) 9.36 6.39 5.56 Gain compared to the case without thermal integration (%) 0% 32% 41%

[0205] The method and the installation according to configurations A and B according to the invention allow a significant reduction in the consumption of hot utilities compared to a configuration not using any heat exchanger involving two flows from the process. This reduction in the consumption of hot utilities has a direct impact on energy expenditure and the associated environmental cost, as well as the operating costs of the process which are consequently reduced.

Claims

Claims

1. A process for producing an aqueous solution of hydroxymethylfurfural, referred to as 5-HMF, comprising the following steps: - a liquid-liquid extraction step (B) of an aqueous feedstock (3) comprising 5-HMF and an aprotic polar synthesis solvent, in the presence of an extraction solvent (4), producing an aqueous raffinate (5) comprising said aprotic polar synthesis solvent and an organic extract (6) comprising 5-HMF and the extraction solvent; - a step of backwashing (C) the organic extract (6) with an aqueous solvent (7) producing an aqueous counter-extract (9) and an organic raffinate (8) comprising 5-HMF and an organic solvent; - a step of regenerating the extraction solvent (100) comprising: a sub-step of concentrating 5-HMF (D) by removing at least part of the organic solvent from said organic raffinate (8) producing a concentrated organic raffinate (10) comprising 5-HMF and residual organic solvent, and a first stream comprising organic solvent (11), and a hydrodistillation sub-step (E) carried out by distillation in the presence of water (14) of said concentrated organic raffinate (10) producing the aqueous solution of 5-HMF (12) and a second stream (13) comprising organic solvent; - a step of regeneration of the polar aprotic synthesis solvent (200) comprising: at least one evaporation sub-step (F, F1, F2, F3) for removing at least part of the impurities from said aqueous raffinate (5) and producing a liquid stream concentrated in impurities (17, 26) and at least one stream comprising water and aprotic polar synthesis solvent (19, 22, 24, 25), and a distillation sub-step (G) carried out by distillation of at least a portion of said stream comprising water and aprotic polar synthesis solvent (19, 22, 24, 25) producing an aqueous effluent (15) and a stream of aprotic polar synthesis solvent (16) recyclable in said process; and in which heating, in heat exchange means, said aqueous raffinate (5) and / or said organic raffinate (8) with at least one gas phase (203, 218) produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent (200).

2. Method according to claim 1, wherein said organic raffinate (8) is heated with a gas phase (203 or 223 / 224) produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent (200).

3. Method according to any one of claims 1 and 2, in which said organic raffinate (8) is heated in two heat exchangers positioned in series (E1', E2') with respectively two gas phases produced during said at least one evaporation sub-step of the regeneration step of the aprotic polar synthesis solvent (200).

4. Method according to claim 3, wherein: - the 5-HMF concentration sub-step (D) of the extraction solvent regeneration step (100) comprises: heating said organic raffinate (8) successively in a first heat exchanger (E1') and a second heat exchanger (E2') positioned in series with respectively a first gas phase (223) and a second gas phase (227), then in a first external flow heat exchanger (113), and gas-liquid separation of said reheated organic raffinate (110) in a first separation tank (VT);and - the step of regenerating the aprotic polar synthesis solvent (200) comprises at least: - a first evaporation sub-step (F1) comprising the heating of said aqueous raffinate (5) successively in a third heat exchanger (E3') with a third gas phase (218) and in a second external flow heat exchanger (216), the gas-liquid separation of said reheated aqueous raffinate (215) in a second separation tank (V2') producing said third gas phase (218) and a liquid flow (217), and the gas-liquid separation in a third separation tank (V3') of said third gas phase (218) after its cooling in the third heat exchanger (E3') producing the second gas phase (227);and - a second evaporation sub-step (F2) comprising the heating of said liquid flow (217) from the first evaporation sub-step successively in a fourth heat exchanger (E4') and in a third external flow heat exchanger (221), and the gas-liquid separation of said heated liquid flow (220) in a fourth separation tank (V4') producing the first gas phase; (223) cooled in the form of a flow (224) in said fourth heat exchanger (E4') before being sent to the first heat exchanger (ET) at the 5-HMF concentration step (D).

5. A method according to any one of claims 1 and 2, wherein: - the 5-HMF concentration sub-step (D) of the extraction solvent regeneration step (100) comprises: heating said organic raffinate (8) successively in a first heat exchanger (E1) and a second heat exchanger (E2) positioned in series with respectively a first gas phase (105) and a second gas phase (203), then in a first external flow heat exchanger (107), and gas-liquid separation of said reheated organic raffinate (103) in a first separation tank (VI) producing the first gas phase (105);and - the step of regenerating the aprotic polar synthesis solvent (200) comprises at least: - a first evaporation sub-step (F1) comprising the heating of said aqueous raffinate (5) successively in a third heat exchanger (E3) with a third gas phase (206) and in a second external flow heat exchanger (212), the gas-liquid separation of said heated aqueous raffinate (202) in a second separation tank (V2) producing said second gas phase (203) and a liquid flow (204), and the gas-liquid separation in a third separation tank (V3) of said second gas phase (203) after its cooling in the second heat exchanger (E2) common to the 5-HMF concentration sub-step (D);and - a second evaporation sub-step (F2) comprising the heating of said liquid flow (204) from the first evaporation sub-step in a third external flow heat exchanger (213), and the gas-liquid separation of said heated liquid flow (205) in a fourth separation tank (V4) producing the third gas phase (206).;

6. Method according to any one of the preceding claims, in which the step of regenerating the aprotic polar synthesis solvent (200) comprises three successive evaporation sub-steps (F1, F2, F3) so as to progressively concentrate the impurities of said raffinate. aqueous (5) in a liquid phase, the third evaporation sub-step (F3) producing a liquid stream of impurities discharged from the process (26) and an effluent comprising water and aprotic polar synthesis solvent (25) sent to the distillation sub-step (G).

7. A method according to any one of the preceding claims, wherein said at least one evaporation step is carried out at a temperature between 80°C and 130°C and at a pressure between 0.0001 MPa and 0.100 MPa.

8. Method according to any one of the preceding claims, comprising a step of bringing into contact (A) a synthesis effluent (1) containing 5-HMF and said aprotic polar synthesis solvent with an aqueous stream (9) so as to obtain an aqueous feedstock (3) comprising 5-HMF and an aprotic polar synthesis solvent, said synthesis effluent (1) preferably being obtained from a step of synthesis of 5-HMF (A') from a sugar feedstock (Cs) comprising a hexose in the presence of an acid dehydration catalyst and the aprotic polar synthesis solvent (S) and carried out at a temperature of between 30°C and 200°C and at a pressure of between 0.001 MPa and 10 MPa.

9. A method according to any one of the preceding claims, wherein: - said polar aprotic synthesis solvent is selected from pyridine, butan-2-one, acetone, acetic anhydride, N,N,N',N'-tetramethylurea, benzonitrile, acetonitrile, methyl ethyl ketone, propionitrile, hexamethylphosphoramide, nitrobenzene, nitromethane, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, N-methylpyrrolidone, dimethyl sulfoxide, propylene carbonate and y-valerolactone, taken alone or as a mixture, and preferably is dimethyl sulfoxide, and - said extraction solvent (7) is selected from dichloromethane, diethyl ether, diisopropyl ether, methyl ethyl ketone, methylisopropyl ketone, methylisobutyl ketone, thiophene, anisole and toluene, and preferably is methylisobutyl ketone.

10. Installation for producing an aqueous solution of 5-HMF (12), for implementing the method according to one of the preceding claims, comprising: - liquid-liquid extraction means (B) of an aqueous charge (3) comprising 5-HMF and an aprotic polar synthesis solvent, configured to contact an extraction solvent (4) with said feedstock (3) and produce an aqueous raffinate (5) depleted in 5-HMF and an organic extract (6) enriched in 5-HMF; - backwashing means (C) configured to bring said organic extract (6) into contact with an aqueous solvent (7) and produce an aqueous backextract (9) and an organic raffinate (8) comprising 5-HMF and an organic solvent; - means for regenerating the extraction solvent (100) comprising: — means for concentrating 5-HMF (D) configured to at least partially remove the organic solvent from said organic raffinate (8) and produce a concentrated organic raffinate (10) comprising 5-HMF and residual organic solvent, and a first stream comprising organic solvent (11); and — a hydrodistillation unit (E) configured to distill said concentrated organic raffinate (10) in the presence of water (14) and produce the aqueous solution of 5-HMF (12) and a second stream (13) comprising organic solvent; - means for regenerating the aprotic polar synthesis solvent (200) comprising at least one evaporation section (F, F1, F2, F3) configured to remove at least part of the impurities from said aqueous raffinate (5) and produce a liquid stream concentrated in impurities (17) and at least one stream comprising water and aprotic polar synthesis solvent (19, 22, 24, 25), and a distillation section (G) configured to distill said stream comprising water and aprotic polar synthesis solvent (19, 22, 24, 25) and produce an aqueous effluent (15) and a stream of aprotic polar synthesis solvent (16) recyclable in said system; said installation comprising heat exchange means configured to heat said aqueous raffinate (5) and / or said organic raffinate (8) with at least one gas phase (203, 218) produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent (200).

11. Installation according to claim 10, wherein the heat exchange means comprise at least one heat exchanger (E2 or El') configured to heat said organic raffinate (8) with a gas phase (203 or 223 / 224) produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent (200).

12. Installation according to claim 10 or claim 11, in which the heat exchange means comprise two successive heat exchangers (ET, E2') configured to heat said organic raffinate (8) with respectively two gas phases produced in said at least one evaporation section of the means for regenerating the aprotic polar synthesis solvent (200).

13. Installation according to claim 12, in which: - said 5-HMF concentration means (D) successively comprise: a first heat exchanger (E1') and a second heat exchanger (E2') formed by said two successive heat exchangers of said heat exchange means, a first external flow heat exchanger (113) and a first separation tank (VT); - said means for regenerating the aprotic polar synthesis solvent (200) comprise: — a first evaporation section (F1) successively comprising a third heat exchanger (E3'), a second external flow heat exchanger (216), a second separation tank (V2') and a third separation tank (V3');— a second evaporation section (F2) configured to receive a liquid stream (217) from said second separation tank (V2') and successively comprising a fourth heat exchanger (E4'), a third external flow heat exchanger (221), and a fourth separation tank (V4'); - said first heat exchanger (E1') and said second heat exchanger (E2') are configured to heat said organic raffinate (8) with respectively a first gas phase (223) and a second gas phase (227), said first gas phase (223) coming from the fourth separation tank (V4') and cooled in the form of a stream (224) in said fourth heat exchanger (E4'), and said second gas phase (227) coming from the third separation tank (V3'); - said third heat exchanger (E3') being configured to heat said aqueous raffinate (5) with a third gas phase (218) coming from the second separation tank (V2').;

14. Installation according to claim 10 or claim 11, in which: - said means for concentrating 5-HMF (D) successfully comprise- sively: a first heat exchanger (El), a second heat exchanger (E2), a first external flow heat exchanger (107) and a first separation tank (VI); - said means for regenerating the aprotic polar synthesis solvent (200) comprise: — a first evaporation section (F1) successively comprising a third heat exchanger (E3), a second external flow heat exchanger (212), a second separation tank (V2), said second heat exchanger (E2) common to said 5-HMF concentration means (D), and a third separation tank (V3); — a second evaporation section (F2) configured to receive a liquid flow (204) from said second separation tank (V2) and successively comprising a third external flow heat exchanger (213) and a fourth separation tank (V4); - said first heat exchanger (El) and said second heat exchanger (E2) being configured to successively heat said organic raffinate (8) with respectively a first gas phase (105) coming from the first separation tank (VI) and a second gas phase (203) coming from the second separation tank (V2); - said third heat exchanger (E3) being configured to heat said aqueous raffinate (5) with a third gas phase (206) from the fourth separation tank (V4).

15. Plant according to any one of claims 10 to 14, wherein said means for regenerating the aprotic polar synthesis solvent (200) comprise three successive evaporation sections (F1, F2, F3) configured to progressively concentrate the impurities of said aqueous raffinate (5) in a liquid phase, the third evaporation section (F3) being configured to produce a liquid stream of impurities to be removed from the system (26) and an effluent comprising water and aprotic polar synthesis solvent (25) sent to the distillation section.

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