Production of 5-HMF in a non-aqueous solvent with concentration of 5-HMF prior to liquid-liquid extraction

Abstract

The invention relates to a process for producing an aqueous solution of 5-hydroxymethylfurfural (5-HMF), comprising successively a) contacting a sugar feedstock with a polar aprotic synthesis solvent and an acid dehydration catalyst, at a temperature of 30-200°C and a pressure of 0.001-10 MPa, to produce a synthesis effluent containing 5-HMF, b) concentrating said synthesis effluent in 5-HMF, c) contacting the concentrated synthesis effluent with an aqueous stream, d) liquid-liquid extraction with an organic extraction solvent followed by a backwashing step e) with an aqueous solvent to obtain an organic raffinate rich in 5-HMF and solvent. The organic raffinate, possibly concentrated, is then subjected to a purification step g), for example hydrodistillation or crystallization, to obtain a stream of 5-HMF, for example in the form of aqueous 5-HMF solution or crystallized 5-HMF.Figure 1 to be published.

Description

Title of the invention: Production of 5-HMF in a non-aqueous solvent with concentration of 5-HMF prior to liquid-liquid extraction technical field

[0001] The invention relates to a process for producing hydroxymethylfurfural (HMF) from a feed containing sugars, in particular at least one hexose and preferably fructose, in the presence of at least one aprotic polar solvent. More particularly, the invention relates to a process for producing HMF, for example the production of an aqueous solution of HMF, comprising a liquid-liquid extraction step preceded by a step of concentrating the synthesis effluent sent to the liquid-liquid extraction into HMF. Previous technique

[0002] HMF, also called 5-(hydroxymethyl)furfural or 5-HMF, is a compound of interest derived from biomass that can be used in many fields, including pharmaceuticals, agrochemicals or specialty chemicals.

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

[0004] The synthesis of 5-HMF in a medium such as DMSO is particularly interesting because it allows 5-HMF to be obtained in its alcohol (and not ether) form with very good yields. However, the physicochemical properties of DMSO (or any other aprotic polar solvent) make it very difficult to separate from 5-HMF using the usual methods known to those skilled in the art.

[0005] A known method for isolating 5-HMF from DMSO is liquid-liquid extraction, followed by crystallization of the extract, as described in patent FR2669635.

[0006] 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 modifying the liquid-liquid extraction step, in particular by adding a water backwash step and recycling the backwash water upstream of the liquid-liquid extraction to mix it with the 5-HMF / DMSO feedstock, said mixture being optionally 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.

[0007] 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 for recovering 5-HMF not in crystalline form but in aqueous solution, which can be advantageous since the crystallization of 5-HMF remains a costly operation. To this end, the process described in X implements a liquid-liquid extraction step combined with a water backwashing step of the organic extract containing the 5-HMF obtained from the liquid-liquid extraction, as well as a 5-HMF concentration step of the organic raffinate containing the 5-HMF obtained in the backwashing step, and a hydrodistillation step of the concentrated stream from said concentration step, in order to recover the 5-HMF in the form of an aqueous 5-HMF solution.

[0008] During the synthesis of 5HMF by dehydration of the sugar feed using a synthetic solvent such as DMSO, it is known to those skilled in the art that diluting the sugar feed in DMSO improves the selectivity of the reaction and thus the molar yield of 5-HMF relative to the sugar feed committed as described in patent WO19137810.

[0009] However, this dilution of the sugar load in DMSO proves detrimental to liquid-liquid extraction as described in patents FR3071172 and FR3131313 in particular, due to the quantities of extraction solvent (e.g., methylisobutyl ketone or MIBK) and water involved, which are linked to the amount of DMSO used in the synthesis. Typically, the extraction solvent is an organic solvent immiscible with water, which is preferably recycled back into the process during the liquid-liquid extraction step, after its separation from the 5HMF downstream of the liquid-liquid extraction. Therefore, it is advantageous to minimize the amount of extraction solvent used in the liquid-liquid extraction, in order to simplify and reduce the cost of the extraction solvent recovery and recycling step. Similarly, water is needed to perform the liquid-liquid extraction, as well as to perform a possible backwash with water of the organic extract from the liquid extraction. The amount of water used in liquid-liquid extraction depends on the amount of DMSO in the feed introduced. Water is necessary to allow the extraction of 5-HMF by the extraction solvent because it enables the formation of a homogeneous liquid phase with the highly polar DMSO, preventing its solubilization with the extraction solvent (e.g., MIBK). Conversely, the extraction solvent has a greater affinity for 5-HMF, allowing it to solubilize and form an organic phase rich in 5-HMF that is immiscible with the aqueous phase containing DMSO. The two liquid phases can then be separated, for example, by simple decantation under suitable temperature and pressure conditions.

[0010] Furthermore, the quantity of water used in the water backwashing step depends on the quantity of extraction solvent used in the liquid-liquid extraction, itself dependent on the quantity of DMSO in the feed entering the liquid-liquid extraction step.

[0011] Thus, it is also advantageous to reduce the amount of water used in the process, for reasons of cost and complexity of water recycling processes in the process, but also for environmental reasons.

[0012] In practice, a compromise is generally made between, on the one hand, the quantity of DMSO required to obtain a good yield of 5-HMF during the synthesis, and on the other hand, the operating and investment costs (OPEX / CAPEX) and the complexity of the liquid-liquid extraction step related to the quantities of extraction solvent and water used.

[0013] In practice, a compromise is generally made between, on the one hand, the yield of 5-HMF during synthesis and, on the other hand, the operating and investment costs (OPEX / CAPEX) and the complexity of the liquid-liquid extraction step: a given quantity of synthesis solvent (e.g., DMSO) is chosen to be used which allows a satisfactory, although not optimal, yield of 5-HMF to be achieved, in order to maintain acceptable costs and complexity for the extraction step. liquid-liquid.

[0014] Overcoming such constraints would constitute a considerable improvement for the implementation of the 5-HMF production process based on this type of liquid-liquid synthesis and extraction. Summary of the invention

[0015] A general objective of the present invention is to provide a process for producing 5-HMF from the transformation of a sugar feedstock exhibiting good yield, good selectivity in 5-HMF, under relatively mild operating conditions (low temperature and pressure).

[0016] In the context described above, the present invention aims to overcome, at least in part, the problems of the prior art, and in particular aims to provide a process for the production of 5-HMF in which the two steps of the synthesis of 5-HMF by dehydration of fructose using a polar aprotic solvent and the liquid-liquid extraction step allowing the recovery of 5-HMF are decoupled, in order to maximize the molar yield of 5-HMF and / or simplify the liquid-liquid extraction step.

[0017] Thanks to the present invention, it is possible to avoid, or at least make less restrictive, the current compromise between the yield of 5-HMF during the synthesis step and the cost of liquid-liquid extraction related to the quantity of synthesis solvent used.

[0018] Thus, an objective of the present invention is to provide a process for the production of 5-HMF from the transformation of a sugar feed using a polar aprotic solvent and optionally an acid catalyst, exhibiting an improved 5-HMF yield and / or a simplification of the liquid-liquid extraction step compared to prior art processes, and in particular with regard to liquid-liquid extraction a reduction in the number of extraction stages and / or a reduction in the quantity of extraction solvent and water used for liquid-liquid extraction.

[0019] According to one aspect, the process according to the invention makes it possible to produce crystallized 5-HMF as an end product.

[0020] According to another aspect, the process according to the invention makes it possible to produce an aqueous solution of 5-HMF as a final product, making it possible to do without an additional crystallization step, thus limiting the operating costs, and making it possible to open up new possibilities for the valorization of 5-HMF in various applications, or for further transformations which could not be carried out either in the synthesis solvent or in the extraction solvent.

[0021] Thus, to achieve at least one of the aforementioned objectives, among others, the present invention proposes a process for producing 5-HMF comprising the steps following: - a step a) of contacting a sugar feed comprising a hexose with at least one aprotic polar synthesis solvent and at least one acid dehydration catalyst so as to produce a synthesis effluent containing 5-HMF and said aprotic polar synthesis solvent, said contacting being carried out at a temperature between 30°C and 200°C and at a pressure between 0.001 MPa and 10 MPa; - a step b) of concentrating said synthetic effluent in 5-HMF so as to obtain a concentrated synthetic effluent; - a step c) of bringing said concentrated synthetic effluent into contact with an aqueous flow, so as to obtain at least an aqueous mixture; - a step d) of liquid-liquid extraction of the aqueous mixture obtained at the end of step c) in the presence of an extraction solvent, so as to produce an aqueous raffinate comprising said aprotic polar synthesis solvent, and an organic extract comprising 5-HMF and extraction solvent; then - a step e) of counter-washing the organic extract with an aqueous solvent, so as to produce an intermediate aqueous counter-extract and an organic raffinate comprising 5-HMF and an organic solvent; - an optional step f) of concentration of said organic raffinate from step e) by removal of at least part of the organic solvent, producing a concentrated organic raffinate comprising 5-HMF, and residual organic solvent, and producing a first stream comprising organic solvent; - a step g) of purification of said organic raffinate or of said concentrated organic raffinate to produce a stream of 5-HMF.

[0022] According to one or more embodiments, the process further includes a step of neutralizing the synthesis effluent from step a) prior to step b), preferably by contacting said synthesis effluent with a basic compound.

[0023] According to one or more implementations, the mass concentration factor at step b), corresponding to the mass ratio between the synthesis effluent and the concentrated synthesis effluent, is between 1.2 and 20, preferably between 1.5 and 20, preferably between 1.5 and 15, and preferably between 2 and 10.

[0024] According to one or more implementations, the synthesis effluent from step a) comprises a 5-HMF / polar aprotic synthesis solvent ratio of between 5 / 95 and 40 / 60, and the concentrated synthesis effluent from step b) comprises a 5-HMF / polar synthesis solvent ratio of between 30 / 70 and 70 / 30.

[0025] According to one or more embodiments, step b) includes evaporation or distillation to vaporize a portion of the aprotic polar synthesis solvent, carried out at a temperature less than or equal to 200°C, preferably less than or equal to 150°C, and preferably less than or equal to 130°C, and at atmospheric pressure or under vacuum, preferably at a pressure between 0.0001 MPa and 0.1000 MPa, preferably under vacuum at a pressure between 0.0001 MPa and 0.0500 MPa.

[0026] According to one or more embodiments, the purification step g) is a hydrodistillation step carried out by distillation in the presence of water of the organic raffinate from step e) or of the concentrated organic raffinate from step f), to produce the 5-HMF stream being an aqueous solution of 5-HMF and a second stream comprising organic solvent, preferably said hydrodistillation being carried out in a distillation column, at atmospheric pressure or under vacuum, preferably at a pressure between 0.001 MPa and 0.1 MPa, and preferably under vacuum at a pressure between 0.005 MPa and 0.08 MPa, and at a column bottom temperature 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, preferably less than or equal to 100°C.

[0027] According to one or more embodiments, the purification step g) includes at least one step of crystallizing the 5-HMF contained in the organic raffinate from step e) or concentrated organic raffinate from step f), followed by filtration, to produce the 5-HMF stream comprising solid 5-HMF and an organic solvent-rich filtrate.

[0028] According to one or more embodiments, the process further comprises a step h) of treating at least one water-aprotic polar synthetic solvent mixture produced in the process to produce at least one recyclable aqueous effluent in said process, said mixture comprising said aqueous raffinate from step d).

[0029] According to one or more embodiments, the process further comprises a liquid-solid separation step, preferably a filtration of the aqueous mixture produced in step c) or of an intermediate liquid stream produced during the liquid-liquid extraction step d) or of the aqueous raffinate from step d).

[0030] According to one or more embodiments, step f) of concentration of the organic raffinate from step e) comprising vaporization of the organic solvent at atmospheric pressure or under vacuum, preferably at a pressure between 0.01 MPa and 0.10 MPa, and a liquid temperature maintained below or equal to 130°C, said concentrated organic raffinate comprising 5-HMF at a content greater than or equal to 30% by weight and residual organic solvent at a content less than or equal to 60% by weight.

[0031] According to one or more implementations, the hexose of the sugar charge is fructose or a fructosidic unit.

[0032] According to one or more embodiments, the aprotic polar synthesis solvent is chosen from pyridine, butan-2-one, acetone, acetic anhydride, the 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 in mixtures, and is preferably dimethyl sulfoxide.

[0033] According to one or more embodiments, the 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.

[0034] According to one or more implementations, in step c), the aqueous stream comprises all or a fraction of the intermediate aqueous counter-extract from step e).

[0035] According to one or more implementations, the aqueous effluent produced in step h) is used in whole or in part in step c) and / or in step e) and / or in step g).

[0036] Other objects and advantages of the invention will become apparent from the following description, particular embodiments of the invention given by way of non-limiting examples, the description being made with reference to the attached figure described below. FIGURE

[0037] [Fig.1]

[0038] Fig. 1 illustrates one embodiment of the process according to the invention. Description of the implementation methods

[0039] In the following detailed description, many specific details are set out to provide a more thorough understanding of the process. However, it will be apparent to those skilled in the art that the process can be carried out without necessarily including all of these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0040] It is specified that, throughout this description, the expression "between ... and ..." should be understood as including the limits mentioned, unless otherwise specified.

[0041] In this description, the term "include" is synonymous with (means the same as) "comprise", "include", and "contain", and is inclusive or open and does not exclude other elements not mentioned. It is understood that the term "include" includes the exclusive and closed term "consist".

[0042] Furthermore, when used in this description, the terms "essentially" or "substantially" or "approximately" in relation to a reference value correspond to an approximation of ±10%, preferably ±5%, most preferably ±2%, or even more preferably ±1% of that value. reference, which can be a temperature, a pressure, a distance, a speed, a flow rate, a content of compound(s), etc.

[0043] In the sense of the present invention, the different embodiments presented can be implemented separately or in combination with each other, without limitation of combinations when this is technically feasible.

[0044] In the sense of the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the sense of the present invention, a preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0045] In the present description, an aprotic solvent is understood to be a molecule acting as a solvent and in which all of the hydrogen atoms are carried by carbon atoms.

[0046] In the present description, a polar solvent is understood to be 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.

[0047] In the present description, a polar aprotic solvent is therefore understood to be a molecule acting as a solvent in which all of 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.

[0048] For a better understanding of the invention, reference is made below to numerical numbers appearing in [Fig.1] to designate different elements of the process, without this constituting a limitation to the particular embodiments described below. Step a) of dehydration of sugars into 5-HMF

[0049] The process according to the invention includes a step of dehydrating sugars into 5-HMF, by contacting a sugar feed comprising a hexose with a polar aprotic synthesis solvent and an acid dehydration catalyst so as to produce a synthesis effluent containing at least 5-HMF and the polar aprotic synthesis solvent.

[0050] The sugar charge implemented in the process according to the invention comprises a hexose.

[0051] A charge comprising a hexose is understood to mean that the hexose may be in monomeric form (monosaccharide) or be a unit belonging to a disaccharide, oligosaccharide, or polysaccharide. A saccharide is a compound also called a sugar.

[0052] Preferably the hexose is fructose or a fructosidic unit.

[0053] In one embodiment, the filler comprises either free fructose, alone or in mixture with any saccharide species, or comprises any oligosaccharide filler or polysaccharide containing one or more fructose units capable of releasing fructose by one or more hydrolysis steps, possibly mixed with other saccharide species. Preferably, the feedstock processed in the process is crystalline fructose, a syrup containing fructose, a syrup containing fructose and glucose, or crystalline sucrose or a sucrose syrup.

[0054] Advantageously, the charge comprises fructose in monomeric, oligomeric or polymeric form.

[0055] By load containing free fructose taken in mixture with any saccharidic species, we mean for example High-Fructose-Com-Syrup type syrups containing fructose and glucose in different proportions (glucose / fructose in mass or molar ratios 58 / 42, 45 / 55, 10 / 90 for example).

[0056] 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.

[0057] The load may include 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 loads such as sucrose, kestose, fructans, oligofructans, rinulin.

[0058] Advantageously, the saccharidic fillers are capable of releasing monomeric fructose by glycosidic hydrolysis, said fructose produced being able to be transformed into 5-HMF.

[0059] Preferably, the oligosaccharide has the molecular formula: (C6mH10m+2O5m+i)(C5nH8n+2O4n+i) where m and n are integers whose sum is between 2 and 6. The monosaccharide units composing said oligosaccharide may or may not be identical, and at least one unit of formula (C6mH10m+2O5m+i) is fructose. By extension, preferably the polysaccharide has the molecular formula (C6mH10m+2O5m+i)(C5nH8n+2O4n+i) where m and n are integers whose sum is greater than or equal to 7.

[0060] The aprotic polar synthesis solvent is advantageously chosen from among all aprotic polar 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) denoted NMP, dimethyl sulfoxide (3.90) denoted DMSO, the propylene carbonate (4.94) and y-valerolactone (4.71), alone or in mixture.

[0061] Preferably, the aprotic polar solvent is advantageously chosen from acetone, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, NMP, DMSO, propylene carbonate and γ-valerolactone, alone or in mixture.

[0062] Preferably, the aprotic polar solvent is advantageously chosen from N,N-dimethylacetamide, NMP, DMSO, and γ-valerolactone, alone or in mixture.

[0063] Preferably, the aprotic polar solvent is DMSO.

[0064] The term acid dehydration catalyst means any Brønsted acid catalyst selected from organic or inorganic, homogeneous or heterogeneous Brønsted acids capable of inducing the dehydration of sugars into 5-HMF.

[0065] Preferably, the acid dehydration catalyst is a Brpnsted acid having a pKa in the aprotic polar synthesis solvent, preferably in DMSO, between 0 and 5.0, preferably between 0.5 and 4.0 and preferably between 1.0 and 3.0. Said pKa values ​​are as defined in the article by FG ​​Bordwell et al. (J. Am. Chem. Soc., 1991, 113, 8398-8401).

[0066] Preferably, the acid dehydration catalyst is selected from HF, HCl, HBr, HI, H2SO3, H2SO4, H3PO2, H3PO4, HNO2, HNO3, H2WO4, H4SiWi2O40, H3PWi2O40, (NH4)6(Wi2O40).xH2O, H4SiMoi2O40, H3PMoi2O40, (NH4)6Mo7O24.xH2O, H2MoO4, HreO4, H2CrO4, H2SnO3, H4SiO4, H3BO3, HclO4, HBF4, HSbF5, HPF6, H2FO3P, C1SO3H, FSO3H, HN(SO2F)2, HIO3, BF3, Al(Otf)3, FeCl3, ZnCl2, SnCl2, CrCl3, CeCl3, ErCl3, formic acid, acetic acid, trifluoroacetic acid, lactic acid, levulinic acid, methanesulfinic acid, methanesulfonic acid, tri-fluoromethanesulfonic acid, bis(trifluoromethanesulfonyl)amine, benzoic acid, para-toluenesulfonic acid, 4-biphenylsulfonic acid, diphenyl phosphate, and l,l'-binaphthyl-2,2'-diyl hydrogen phosphate.Preferably, the acid dehydration catalyst is chosen from HCl, H2SO4, H3PO2, H3PO4, HNO3, AlCl3, acetic acid, trifluoroacetic acid, methanesulfinic acid, methanesulfonic acid, trifluoromethanesulfonic acid.

[0067] 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 performed 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. The bubble point refers to 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 the mixture, the vapor phase can be withdrawn from the reactor, optionally rectified, and condensed to form condensates which can be sent to a step h) of processing of the aprotic polar synthesis water-solvent mixtures.

[0068] Preferably, the acid dehydration catalyst is introduced at the dehydration step in a molar ratio of catalyst to sugar charge, denoted Acid / Sugar, expressed in 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, most preferably between 0.3 and 4 %mol and most preferably between 0.5 and 3 %mol.

[0069] The dehydration step can be carried out in various embodiments. For example, the step can advantageously be implemented batch or continuously (batch being referred to as "batch" in English terminology). The addition of the sugar feed can be gradual (referred to as "fed-batch" in English terminology) in the case of batch implementation or staged in several continuously stirred tank reactors (CSTRs) in series in continuous implementation. The process can be carried out in a closed reaction vessel or in a semi-open reactor.

[0070] The synthesis effluent 2 obtained at the end of the optional dehydration step comprises 5-HMF and aprotic polar synthesis solvent, preferably DMSO.

[0071] The aprotic polar synthesis solvent, typically DMSO, generally represents between 30 and 95% by weight of the synthesis effluent 2 from the dehydration step and sent to step b) of the process according to the invention, preferably between 40 and 90% by weight, preferably between 50 and 90% by weight, preferably between 55 and 85% by weight.

[0072] The 5-HMF represents at least 1% by weight of the synthesis effluent 2 from the dehydration step a) and sent to step b) of the process according to the invention, preferably at least 10% by weight, preferably at least 15% by weight and preferably at most 50% by weight of the synthesis effluent 2 from the dehydration step a), preferably at most 40% by weight, preferably at most 30% by weight.

[0073] Furthermore, said synthesis effluent 2 from the dehydration step may contain water even before mixing in step c) with the aqueous stream 5. Said water may originate from the dehydration step, for example, water is formed during the dehydration reaction of sugar to 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 about 70 wt% in water, is used. Advantageously, during the dehydration step, a water-solvent mixture of a polar aprotic synthesis (e.g., DMSO) can be recovered in phase steam. Said water-aprotic polar synthesis solvent mixture (e.g., DMSO) can advantageously be sent to step h) of treatment of water-aprotic polar synthesis solvent mixtures. Thus, the synthesis effluent 2 from the dehydration step a) and introduced into step b) of 5-HMF concentration may contain water, in a proportion generally between 0.1 and 30 wt%, preferably between 0.1 and 15 wt%, preferably between 0.1 and 10 wt%.

[0074] It can be advantageous to perform, during the dehydration step, a concomitant extraction of water from the reaction medium in order to reduce its content and thus improve the selectivity of the reaction. Selectivity for 5-HMF is defined as the ratio between the number of moles of 5-HMF produced and the number of moles of fructose converted from the sugar feed introduced into the process. In a polar aprotic medium, the presence of water degrades the sugar conversion selectivity, all the more significantly as the sugar concentration in the DMSO increases. Such continuous water extraction during the synthesis of 5-HMF is therefore beneficial in this respect, and also allows for the extraction of any water present in the sugar feed if it is in syrup form, to be managed in a single step. During such water extraction from the reaction medium, the reaction medium is above the bubble point of the mixture.The vapor phase can be withdrawn from the reactor, rectified, and condensed to form water condensates containing less than 10% by weight, preferably less than 5% by weight or even less than 1% by weight, of the aprotic polar synthesis solvent. The extracted water may be from dehydration and / or may have been introduced with the sugar feed, in cases where, for practical reasons, a syrup feed is used. Advantageously, at least 50% by weight, preferably at least 80% by weight, or even 90% by weight of the water present in the reaction medium is extracted. The water extracted from the reaction medium may represent at least 50% by weight, preferably at least 80% by weight or even 90% by weight of the water produced during dehydration.Water extraction can be carried out by various methods, such as evaporation, adsorption (for example, in a molecular sieve), membrane separation, or osmosis, and is advantageously achieved by distillation, provided that the aprotic polar synthesis solvent is less volatile than water. Advantageously, water extraction is carried out under conditions that allow at least 90% by weight, preferably at least 95% by weight or even 99% by weight, of the aprotic polar synthesis solvent used in the dehydration step to be recovered in the synthesis effluent obtained at the end of the dehydration step.The water thus extracted can, like the aqueous effluent 20 from step h) of treatment of the water-solvent mixtures of polar aprotic synthesis, be recycled to one or more steps of the process requiring the supply of an aqueous flow, or be mixed with said recyclable aqueous effluent 20, or be sent to step h) to be treated and remove the solvent from. polar aprotic synthesis which it may still contain, in particular to produce said recyclable aqueous effluent 20.

[0075] When the sugar feedstock is in syrup form, it can be advantageous to reduce the water content upstream of the sugar feedstock dehydration step, optionally by extracting the water resulting from the dehydration reaction during the dehydration step, as already described above and not repeated here. Thus, the water in the sugar feedstock in syrup form can be extracted and replaced with a polar aprotic synthetic solvent, e.g., DMSO, resulting in a mixture sent to the dehydration step. The water in the syrup can be extracted, at least partially, after mixing the syrup with the polar aprotic synthetic solvent. This solvent allows the sugar to remain in a dilute medium and replaces dilution by water with dilution by the synthetic solvent.Water extraction can be carried out by various methods, such as evaporation, adsorption (for example, in a molecular sieve), membrane separation, and is advantageously achieved by distillation, provided that the aprotic polar synthesis solvent is less volatile than water. Advantageously, the extracted water represents at least 50% by weight, preferably at least 80% by weight, or even at least 90% by weight, of the water present in the syrup. The extracted water can represent between 90% and 99% by weight of the water in the syrup. Advantageously, the extracted water comprises less than 10% by weight, preferably less than 5% by weight, or even less than 1% by weight, of the synthesis solvent.The water thus extracted can, like the aqueous effluent 20 from step h) of treatment of the water-aprotic polar synthesis solvent mixtures, be recycled to one or more steps of the process requiring the supply of an aqueous flow, or be mixed with said recyclable aqueous effluent 20, or be sent to step h) to be treated and remove the aprotic polar synthesis solvent that it may still contain, in particular to produce said recyclable aqueous effluent 20.

[0076] The synthesis effluent 2 from the dehydration step and introduced in step b) 1 may also contain impurities, in particular humins. Humins are defined as all undesirable polymeric compounds formed during the synthesis of 5-HMF. Humins represent, in particular, less than 30% by weight of the converted sugar feed, preferably less than 20% by weight.

[0077] During the dehydration step a), the rate of conversion of the sugar, e.g. fructose, is at least 80%, preferably at least 90% and even more preferably at least 98%.

[0078] By conversion rate, we mean the ratio between the sugar consumed during the reaction (difference between the total sugar involved and the residual sugar at the end of the reaction) relative to the total sugar involved in the reaction.

[0079] The selectivity of conversion of sugar into 5-HMF is defined as the molar ratio between the number of moles of 5-HMF produced by the reaction relative to the number of moles of sugar consumed by the reaction.

[0080] 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.

[0081] The molar yield in 5-HMF is at least 70%, preferably at least 80%.

[0082] An optional neutralization step can be carried out on the synthesis effluent 2 from the dehydration step a), upstream of the 5-HMF concentration step b), said synthesis effluent 2 containing the acid dehydration catalyst. This reduces the reactivity of the medium and thus prevents 5-HMF degradation mechanisms, or reduces corrosion of the equipment materials downstream of the dehydration step. Since the dehydration reaction may produce some organic acids, the quantity of neutralizing agent can advantageously neutralize all the acids present in the synthesis effluent 2 from the dehydration step.Such a neutralization step is advantageously carried out at a minimum stoichiometric ratio to the amount of catalyst used, and generally carried out at a slightly over-stoichiometric ratio with respect 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 can be a basic compound chosen from among NaOH, KOH, NH4OH, Na2CO3, K2CO3, NaHCO3, KHCO3, Mg(OH)2, Ca(OH)2, Ba(OH)2. Step b) of 5-HMF concentration

[0083] According to an essential aspect, the process according to the invention includes a step b) of concentrating in 5-HMF the synthesis effluent 2 from step a), optionally neutralized by contacting a basic compound as described above, so as to obtain a concentrated synthesis effluent 3.

[0084] The concentration step b) is therefore carried out on the synthesis effluent 2 obtained at the end of step a), i.e. having reached a maximum sugar conversion rate, preferably a sugar conversion rate, e.g. fructose, of at least 80%, preferably of at least 90% and even more preferably of at least 98%.

[0085] Advantageously, step b) of concentration in 5-HMF includes an evaporation or distillation step allowing to volatilize part of the synthesis solvent, thus taking advantage of the fact that 5-HMF has a high boiling point (>280°C). For reasons of thermal stability of 5-HMF, and incidentally of residual sugars and 5-HMF co-products, it is necessary to limit the temperature during Evaporation or distillation is used in this concentration step (b). Thus, the 5-HMF concentration step (b), which removes a portion of the synthesis solvent, e.g., DMSO, by vaporization, is carried out at a temperature of 200°C or lower, preferably 150°C or lower, and more preferably 130°C or lower. The thermal stability of the aprotic polar synthesis solvent may also constrain the temperature of this step. Preferably, the temperature is 150°C or lower, and preferably 130°C or lower, when DMSO is used as the aprotic polar synthesis solvent. Advantageously, the operating temperature in step (b) is 70°C or higher.

[0086] The operating pressure is a result of the properties of the substances (5-HMF and aprotic polar synthesis solvent). The pressure level, particularly the vacuum level, to be applied to reach these temperature values ​​is of course dependent on the synthesis solvent and its vaporization rate. Step b) is advantageously carried out at atmospheric pressure or under vacuum so as to limit the temperature of the liquid and therefore the degradation of the 5-HMF and the aprotic polar synthesis solvent, preferably at a pressure between 0.0001 MPa and 0.1000 MPa (absolute), preferably under vacuum at a pressure between 0.0001 MPa and 0.0500 MPa (absolute), more preferably between 0.0001 MPa and 0.0200 MPa (absolute), even more preferably between 0.0001 MPa and 0.0100 MPa (absolute), and even more preferably between 0.0001 MPa and 0.0050 MPa (absolute).

[0087] The concentrated synthesis effluent 3 has a higher 5-HMF content than the synthesis effluent 2 from step a), and therefore contains less aprotic polar synthesis solvent than the synthesis effluent from step a). Advantageously, the concentrated synthesis effluent 3 produced in step b) contains at most 70 wt% aprotic polar synthesis solvent, preferably at most 60 wt% and even more preferably at most 50 wt%, and preferably at least 10 wt% aprotic polar synthesis solvent, and preferably at least 20 wt%.

[0088] Advantageously, the concentration of the synthesis solvent at the end of step b) is determined so as not to degrade the 5-HMF at the chosen operating temperature. Indeed, it is known that 5-HMF is more thermally unstable the more concentrated it is and the longer the residence time under elevated temperature conditions.

[0089] Preferably, the concentration of 5-HMF in the synthesis effluent 2 from step a) is achieved in step b) by removing a portion of the synthesis solvent, e.g. DMSO, by vaporization, for example in a distillation column at atmospheric pressure or under vacuum, in an evaporator, or by any method known to man of the trade.

[0090] Step b) can be carried out using a simple evaporator or a distillation column allowing the vapor phase to be rectified and the separation between the synthesis solvent and the 5-HMF to be improved.

[0091] Given the temperature sensitivity of the products present, it may be necessary to use evaporation or distillation technologies with short residence times such as scraped film evaporators or short path distillations.

[0092] Depending on the concentration factor sought, step b) can be carried out in several successive steps: several successive vaporization operations of the aprotic polar synthesis solvent can be carried out under the conditions given above and with one or more of the equipment mentioned.

[0093] In a preferred mode, the solvent is vaporized by multi-effect evaporation or by mechanical recompression of the vapors, or by any other method known to those skilled in the art, so as to reduce the operating costs associated with solvent evaporation while limiting the risk of degradation of the product of interest, i.e., 5-HMF. For example, in the case of a triple-effect evaporator, the liquid temperature is maintained below 200°C in the first effect, below 150°C in the second effect, and below 130°C in the third effect. Thus, the temperature of the liquid phase is reduced as the 5-HMF is concentrated in the solvent, limiting any risk of degradation.

[0094] The mass concentration factor at step b) corresponds to the ratio between the quantity of synthesis effluent 2 (mass) entering the concentration step b) and the quantity of concentrated synthesis effluent 3 (mass) produced at the end of step b) and sent to step c), i.e. the ratio between the mass of effluent 2 from step a) and that of stream 3. This factor depends strongly on the dilution chosen at the dehydration step a) and the target concentration of 5-HMF at step b).

[0095] Preferably, the mass concentration factor is between 1.2 and 20, preferably between 1.5 and 20, preferably between 1.5 and 15, and more preferably between 2 and 10.

[0096] Advantageously, the synthesis effluent 2 from step a), and sent to step b), after possible neutralization, comprises a 5-HMF / polar aprotic synthesis solvent ratio of between 5 / 95 and 40 / 60, and the concentrated synthesis effluent 3 from step b) comprises a 5-HMF / polar synthesis solvent ratio of between 30 / 70 and 70 / 30.

[0097] Step b) also produces a stream 3' comprising synthetic solvent, and optionally water and a small amount of 5-HMF. The stream 3' comprising organic solvent can be recycled, advantageously in liquid form, in step h) of processing the water / synthetic solvent mixtures, or, if the synthetic solvent is more volatile than water, directly to the dehydration step a) (recycles at step a) not shown in [Fig.l]).

[0098] Step b) of 5-HMF concentration of the synthesis effluent allows a decoupling of the two steps, namely step a) of sugar dehydration into 5-HMF and step d) of liquid-liquid extraction, and in particular the decoupling of the constraints relating to the quantity of synthesis solvent used during step a) required to obtain a good yield of 5-HMF (significant dilution required of the sugar charge in the synthesis solvent) but suffered in step d) of liquid extraction, in particular with regard to the quantity of extraction solvent used, the water involved in the backwash associated with the liquid-liquid extraction, the size of the equipment for the liquid-liquid extraction, the downstream steps for the removal of the extraction solvent, etc.

[0099] Indeed, thanks in particular to step b) integrated into the process according to the invention, it is possible: - to obtain an improved yield of 5-HMF, for example through greater possible dilution in the synthesis solvent in step a), such dilution promoting 5-HMF selectivity during dehydration in step a), particularly for kinetic reasons, and / or - to simplify the liquid-liquid extraction step, for example: — by reducing the number of extraction stages for the same quantity of extraction solvent used, which implies a lower investment cost for the liquid-liquid extraction column, and / or — by reducing the amount of extraction solvent for a given amount of 5-HMF to be extracted, making it possible in particular to reduce the energy required and the investment and operating costs for the regeneration of the extraction solvent, and therefore the costs of the process. Step c) of mixing

[0100] The process according to the invention includes a step c) of contacting (or mixing) the concentrated synthesis effluent 3 comprising 5-HMF and the aprotic polar synthesis solvent, e.g. DMSO, from step b) with an aqueous stream 5 so as to obtain at least one aqueous mixture 6.

[0101] The aqueous stream 5 can be composed of pure water, external to the process, and / or recycled water from the process, for example the aqueous stream 5 can advantageously include all or part of the intermediate aqueous counter-extract 11 from step e) and / or water 20 produced in step h) of treatment of the aprotic polar synthetic water-solvent mixtures.

[0102] Preferably, 5-HMF represents at least 20% by weight of the concentrated synthesis effluent 3 introduced in step c) of the process according to the invention, preferably at least 30% by weight, preferably at least 40% by weight and preferably at most 80% by weight, preferably at most 60% by weight, preferably at most 50% by weight.

[0103] Preferably, the aprotic polar synthesis solvent (e.g. DMSO) represents between 10 and 70% by weight of the concentrated synthesis effluent 3 introduced in step c), preferably between 10 and 60% by weight, preferably between 10 and 50% by weight, preferably between 20 and 50% by weight.

[0104] The aqueous stream 5 comprises, and may consist of, water. When the aqueous stream 5 comprises a recycled process water fraction, said fraction may comprise at least 60% by weight of water, preferably at least 70% by weight, more preferably at least 80% by weight, and even more preferably at least 95% by weight or even 98% by weight of water. The aqueous stream 5 may comprise all or part of the intermediate aqueous counter-extract 11 from step e). Said intermediate aqueous counter-extract 11 comprises water, a polar aprotic synthesis solvent (e.g., DMSO), and optionally 5-HMF. Advantageously, said intermediate aqueous counter-extract 11 contains more than 60% by weight of water, preferably more than 70% by weight of water, and preferably more than 80% by weight of water.

[0105] Advantageously, the aqueous mixture 6 obtained at the end of step c) contains between 10% and 90% by weight of water, preferably between 20% and 70% by weight of water, preferably between 30% and 50% by weight of water.

[0106] Preferably, step c) 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.

[0107] By increasing the water content of the concentrated synthesis effluent 3 in step c), some of the humins present in the concentrated synthesis effluent 3 may precipitate. The mixture resulting from the contact of the concentrated synthesis effluent 3 with the aqueous stream 5 can therefore advantageously be subjected to a liquid-solid separation step before being sent to the liquid-liquid extraction step d), so as to obtain a liquid separated from suspended solid particles and a solid residue containing humins, which is preferably removed from the process in the form of a solid stream 4. Such an optional liquid-solid separation step thus makes it possible to remove the "humins" that precipitated in step c) or upstream. At least some of the liquid obtained is then advantageously sent to the liquid-liquid extraction step d), this part or preferably all of the liquid being advantageously sent to step d) corresponding to the aqueous mixture 6.Such a liquid-solid separation step in step c) can be advantageously implemented when the quantity of humins precipitated in the mixture formed by the concentrated synthesis effluent 3 and the aqueous stream 5 in step c) is, for example, greater than 1% by weight. Humans can be quantified in various well-known ways. The expert, for example by size exclusion chromatography. The optional liquid-solid separation operation, e.g. filtration, thus makes it possible to remove the "humins" that 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 ambient temperature (i.e., between 10°C and 40°C). The optional liquid-solid separation step prior to step d) is a simple solid-liquid separation and can be carried out by any method known to those skilled in the art, such as using a filter press, belt filter, clarifier, decanter, or centrifuge, for example, a plate centrifuge. These techniques may be used alone or in combination, in any order. Preferably, the liquid-solid separation step is filtration, preferably carried out by a filter press. Liquid-liquid extraction step d)

[0108] The process according to the invention includes a step d) of liquid-liquid extraction of the aqueous mixture 6 obtained at the end of step c) in the presence of an extraction solvent 7, so as to produce an aqueous raffinate 8 and an organic extract 9.

[0109] The liquid-liquid extraction carried out in step d) advantageously corresponds to washing the aqueous mixture 6 with an organic extraction solvent 7. Preferably, the liquid-liquid extraction carried out in step d) is a countercurrent extraction of the aqueous mixture 6 obtained in step c) with an extraction solvent 7. This technique is well known to those skilled in the art. It can be carried out, for example, in a battery of mixer-settlers, in a column packed with bulk or structured material, in a pulsed column, or even in a stirred column.

[0110] Liquid-liquid extraction may include the implementation of at least two theoretical separation stages. This is the case, for example, but not exclusively, when a liquid-solid separation stage is carried out on an intermediate liquid stream produced during liquid-liquid extraction step d), which can return to step d) once it has been freed of solid particles. A first liquid-liquid separation stage may then be carried out, producing said intermediate liquid stream sent to a liquid-solid separation stage in order to remove any precipitated humins present during the liquid-liquid extraction, and forming a particle-depleted intermediate liquid stream sent to the second liquid-liquid extraction stage of step d).

[0111] Step d) of liquid-liquid extraction 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).

[0112] Generally, the extraction solvent ratio, defined as the mass ratio between the extraction solvent flow rate and the feed entering the extraction stage, results the number of separation stages involved, the choice of extraction solvent and the 5-HMF recovery target defined as the ratio between the quantity of 5-HMF carried in the organic extract 9 and the quantity of 5-HMF contained in the aqueous mixture 6 sent to the extraction step d). 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%.

[0113] The extraction solvent 7 introduced in step d) is chosen from among organic solvents immiscible with water, so as to form two liquid phases in step d) and in the backwashing step e). This property is highly dependent on the relative proportion of the feed flow rates, backwash water, and extraction solvent used in the process.

[0114] By way of non-limiting agreement, the extraction solvent is preferably chosen from among 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 denoted 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 having between 1 and 10 carbon atoms (C1-C10), an aromatic compound C4-C10. 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.

[0115] Advantageously, the extraction solvent is chosen so as to have a very high difference in volatility with the 5-HMF, in particular so as to facilitate its removal in the optional step f) and limit the degradation of the 5-HMF, i.e. so as to present in step f) a rate of vaporization which does not degrade the 5-HMF and to minimize the amount of residual solvent to be removed in step g), while ensuring the absence of liquid phase separation in the case of a purification step g) involving hydrodistillation when the organic raffinate 12 or the concentrated organic raffinate 13 is brought into contact with water in step g).

[0116] The extraction solvent can also be chosen so as to form, in step g), if this step involves hydrodistillation, a heterogeneous azeotrope with water, preferably rich in solvent, i.e., with more than 50 wt% solvent, preferably with more than 60 wt% solvent, and preferably with more than 70 wt% solvent. Advantageously, said azeotrope of the water / extraction solvent mixture 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 lower than of at least 10°C above the boiling point of water.

[0117] Advantageously, the organic solvent streams (extraction solvent) produced in subsequent steps can be recycled to the extraction step (d) as extraction solvent. These extraction solvent streams may contain impurities generated during the implementation of the process. Advantageously, the extraction solvent streams produced in subsequent steps can be distilled, for example periodically, to prevent the accumulation of said impurities.

[0118] Step d) thus makes it possible to obtain, on the one hand, an aqueous stream depleted in 5-HMF, called aqueous raffinate 8, which contains a large part of the aprotic polar synthesis solvent (e.g., DMSO) initially contained in the concentrated synthesis effluent 3, and on the other hand, an organic stream enriched in 5-HMF, called organic extract 9, which contains a large part of the 5-HMF initially contained in the concentrated synthesis effluent 3 and the extraction solvent 7. This organic extract 9 may also contain aprotic polar synthesis solvent (e.g., DMSO). Preferably, said organic extract 9 contains 5-HMF and aprotic polar synthesis solvent (e.g., DMSO) in a weight ratio of 5-HMF / aprotic polar synthesis solvent (e.g., DMSO).DMSO), between 50 / 50 and 99 / 01, preferably between 50 / 50 and 95 / 05, preferably between 55 / 45 and 90 / 10, more preferably between 60 / 40 and 85 / 15, preferably between 65 / 35 and 85 / 15. .

[0119] Advantageously, the organic extract 9 is sent directly to the backwashing step e).

[0120] A fraction of solid particles, formed by precipitated humins, may also be present in step d). This may consist of humins precipitated in the upstream mixing step c), still present in the aqueous mixture 6 sent to step d), or of humins precipitated in step d) or even in the backwashing step e). Backwashing step e

[0121] The process according to the invention includes a step e) of backwashing the organic extract 9 with an aqueous solvent 10, so as to produce an intermediate aqueous counter-extract 11 and an organic raffinate 12 comprising 5-HMF and an organic solvent. The intermediate aqueous counter-extract 11 is advantageously sent in part or in whole to step c). The organic solvent is in particular composed at least in part of an extraction solvent and may optionally include a polar aprotic synthesis solvent (e.g., DMSO), preferably in small amounts.

[0122] The introduction of an aqueous solvent 10 in step e) is carried out in such a way as to implement a backwash, according to the general knowledge of those skilled in the art. The introduction of the aqueous solvent 10 is carried out in such a way that the quantity of aqueous solvent is as small as possible in order to reduce costs, but sufficient to guarantee a weight content of aprotic polar synthesis solvent (e.g. DMSO) in organic raffinate 12 low and preferably less than or equal to 20.0 wt% relative to the wt of 5-HMF, preferably less than or equal to 10.0 wt% relative to the wt of 5-HMF, preferably less than or equal to 2.0 wt% relative to the wt of 5-HMF, most preferably less than or equal to 1.0 wt% relative to the wt of 5-HMF.

[0123] Advantageously, the aqueous backwash solvent 10 introduced in step e) comprises at least 95 wt% water, preferably at least 98 wt% water (100% being the maximum). The aqueous solvent may optionally include a polar aprotic synthetic solvent (e.g., DMSO). The backwash efficiency is higher when the amount of polar aprotic synthetic solvent (e.g., DMSO) present in the aqueous backwash solvent is lower. The aqueous solvent may comprise at most 1.0 wt%, and preferably at most 0.1 wt%, of a polar aprotic synthetic solvent (e.g., DMSO). Advantageously, the aqueous backwash solvent 10 is obtained from step h) of the treatment of water-aprotic polar synthetic solvent mixtures produced within the process, and thus comprises at least a fraction of the recyclable effluent 20. In a preferred embodiment of the invention, the aqueous raffinate 8, composed of water and aprotic polar synthetic solvent (e.g.DMSO), produced in step d), is treated in step h), which advantageously includes distillation. The water-rich distillate thus obtained at the end of this step h), also called the recyclable aqueous effluent 20 in the process, is advantageously used to form the aqueous backwash solvent 10 in step e), optionally mixed with additional water, or is used in the mixing step c) to form the aqueous stream 5, optionally with at least one intermediate aqueous back-extract fraction 11 and / or additional water. This recyclable effluent 20, e.g., the water-rich distillate, may also contain a residual amount of aprotic polar synthetic solvent (e.g., DMSO), preferably less than or equal to 1 wt% and preferably less than or equal to 0.1 wt%. The residual amount of aprotic polar synthetic solvent (e.g., DMSO) isDMSO) in the aqueous effluent 20 (the distillate) is lower the more efficiently the distillation of step h) is carried out, in particular with a number of distillation stages greater than 5, and advantageously with suitable reboiling and reflux ratios.

[0124] The backwashing step (e) is advantageously a liquid-liquid extraction of an organic stream, in particular of the organic extract 9 obtained in step (d) against the aqueous solvent 10. This technique is well known to those skilled in the art. The extraction can be carried out, for example, in a battery of mixer-settlers, in a column packed with bulk or structured material, in a pulsed column, or even in a stirred column.

[0125] Step e) 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).

[0126] The weight ratio (weight / weight) of aqueous solvent 10 relative to the organic extract 9 is preferably between 0.04 and 5, preferably between 0.07 and 3, preferably between 0.1 and 1.

[0127] Step e) enables the obtaining of an aqueous stream advantageously enriched in aprotic polar synthesis solvent (e.g., DMSO), called intermediate aqueous counter-extract 11, preferably containing at least 60 wt% water, preferably at least 80 wt% water, and an organic raffinate 12, advantageously depleted in aprotic polar synthesis solvent (e.g., DMSO). Said intermediate aqueous counter-extract 11 is advantageously sent, in part or preferably in whole, to step c).

[0128] According to the invention, the organic raffinate 12 produced in step e) is sent to the optional step f) of concentration or directly to the step g) of purification.

[0129] Humins may still be present in the organic extract 9 sent to the backwash step e). If they precipitate at this step, forming undesirable solid particles, these could be removed at a liquid-solid separation step by sending the intermediate aqueous counter-extract 11, in part or in whole, to step d), which would contain the precipitated humins, and which could be sent to a liquid-solid separation step during step d) on an intermediate liquid stream produced in step d) and / or downstream of step d) on the aqueous raffinate 8. If the intermediate aqueous counter-extract 11 is sent in part or in whole to step c) to form part of the composition or to constitute the aqueous stream 5, the precipitated humins could also be separated during the optional liquid-solid separation of step c).

[0130] Optional step f) of post-extraction liquid-liquid concentration

[0131] The process according to the invention preferably comprises a step f) of concentrating the organic raffinate 12 from step e), by removing part of the organic solvent, producing a concentrated organic raffinate 13, comprising 5-HMF and residual organic solvent, and a first stream 14 comprising, preferably made up of, organic solvent, said organic solvent advantageously being composed in whole or in part of the extraction solvent and optionally of aprotic polar synthesis solvent (e.g. DMSO).

[0132] Preferably, the first stream 14 comprising organic solvent is recycled, in whole or in part, to the extraction step d), for example forming at least part of the organic solvent stream 7.

[0133] Preferably, in step f), the removal of part of the organic solvent is carried out by vaporization, for example in a distillation column at atmospheric pressure or under vacuum, in an evaporator, or any method known to humankind. job.

[0134] According to this preferred method, the vaporization of the organic solvent is advantageously carried out at atmospheric pressure or under vacuum, preferably at a pressure between 0.01 MPa and 0.1 MPa, preferably under vacuum at a pressure between 0.01 MPa and 0.09 MPa, so as to limit the temperature of the liquid and therefore the degradation of 5-HMF. Preferably, the temperature of the liquid is maintained at or below 130°C, preferably at or below 100°C, preferably at or below 70°C. The pressure level, particularly the vacuum level, to be applied to reach these temperatures is of course dependent on the organic solvent and more particularly on the extraction solvent used and the vaporization rate of the organic solvent.

[0135] In a preferred mode, the solvent is vaporized by multi-effect evaporation or by mechanical recompression of the vapors, or by any other method known to those skilled in the art, so as to reduce the operating costs associated with solvent evaporation while limiting the risk of degradation of the product of interest, i.e., 5-HMF. For example, in the case of a triple-effect evaporator, the liquid temperature is maintained below 130°C in the first effect, below 100°C in the second effect, and below 70°C in the third effect. Thus, the temperature of the liquid phase is reduced as the 5-HMF is concentrated in the organic solvent, limiting any risk of degradation.

[0136] The optional step f) is implemented with a mass vaporization rate (or evaporation rate), corresponding to the mass of organic solvent vaporized relative to the mass of the organic raffinate 12 from step e) (more particularly the mass quantity of the stream 14 relative to the mass quantity of the organic raffinate 12), 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 according to the extraction solvent so as not to degrade the 5-HMF, but also in order to minimize the amount of residual solvent to be removed in step g) while ensuring the absence of liquid phase separation if hydrodistillation is carried out in step g) (i.e. while ensuring that the liquid phase remains monophasic).

[0137] Thanks to the combination of all the operating conditions of the preceding steps a), b), c), d), e), and the optional step f), the concentrated organic raffinate 13 obtained at the end of step f) very advantageously has a 5-HMF content of at least 30 wt% relative to the weight of the concentrated organic raffinate, preferably at least 40 wt%, preferably at least 50 wt%, and preferably at most 95 wt%, preferably at most 90 wt%, and preferably at most 85 wt% relative to the weight of the concentrated organic raffinate 13. In other words, the Concentrated organic raffinate 13 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 40% by weight, relative to the weight of the concentrated organic raffinate 13.

[0138] Advantageously, the organic solvent vaporized during the optional step f) forms a first stream 14 comprising, preferably consisting of, organic solvent and is preferably recycled to the extraction step d).

[0139] Advantageously, the concentrated organic raffinate 13 is sent to the purification step g). Step g) of purification

[0140] The process according to the invention includes a step g) of purifying the organic raffinate 12 or the concentrated organic raffinate 13 to produce a stream of 5-HMF.

[0141] According to one or more embodiments, the purification step g) comprises, and may consist of, a hydrodistillation step carried out by distillation in the presence of water 17 of the organic raffinate 12 from step e) or of the concentrated organic raffinate 13 from the optional step f), to produce said 5-HMF stream which is then an aqueous solution of 5-HMF 15 and generating a second stream 16 comprising, and preferably consisting of, organic solvent.

[0142] The hydrodistillation step advantageously allows the removal, at least in part, of the residual organic solvent not removed during the optional step f). The residual organic solvent removed during the hydrodistillation step, i.e. the second stream 16 comprising organic solvent, can advantageously be recycled in the extraction step d), alone or mixed with the first stream 14 from the optional step f).

[0143] Advantageously, an aqueous liquid 17 feeds the hydrodistillation step. The aqueous liquid 17 introduced into the hydrodistillation step preferably contains more than 95% by weight of water, preferably more than 98% by weight of water.

[0144] In a particular embodiment of the invention, the aqueous liquid 17 is pure water, possibly external to the process, which makes it possible to further minimize the residual content of aprotic polar synthesis solvent (e.g. DMSO) in the aqueous solution 15 of 5-HMF produced in step g) comprising or consisting of hydrodistillation.

[0145] In another particular embodiment of the invention, isolated water within the process is used to feed the hydrodistillation step, thereby limiting the operating costs of the process and its environmental impact. Typically, if the sugar feedstock for the dehydration step is a sugar syrup at 70% wt% in water, approximately 1 tonne of water is available at the end of the dehydration step (the water from the (sugar feed and water produced during the dehydration reaction) per ton of 5-HMF produced. This water, which is advantageously recovered, requires treatment before being discharged into the environment. The process according to the invention can then advantageously use said water from the sugar feed and / or the dehydration step to produce, at the end of the hydrodistillation step, an aqueous solution of 5-HMF concentrated preferably to 30 wt% or more, preferably to 40 wt% or more, and thus reduce the reprocessing costs and its environmental impact.

[0146] Advantageously, the aqueous liquid 17 introduced at the hydrodistillation step may correspond to at least a fraction, possibly all, of the aqueous effluent 20 (distillate) produced at step h). Said distillate may optionally contain a residual amount of aprotic polar synthesis solvent (e.g. DMSO).

[0147] Advantageously, during the hydrodistillation step, 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.

[0148] Thus, after contacting the concentrated organic raffinate 13 or the organic raffinate 12 with the aqueous liquid 17, the residual organic solvent can be easily removed without degradation of the 5-HMF.

[0149] The hydrodistillation step can be carried out at atmospheric pressure or under vacuum, and in particular at a pressure between 0.00 MPa and 0.1 MPa, preferably under vacuum at a pressure between 0.005 MPa and 0.08 MPa. Advantageously, the hydrodistillation step is carried out under vacuum, in particular at a pressure 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.

[0150] Advantageously, the hydrodistillation 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.

[0151] In a particular embodiment, during the hydrodistillation step, the raffinate concentrated organic 13 or failing that organic raffinate 12 and aqueous liquid 17 are mixed before introduction into a distillation column and the mixture is introduced at an intermediate point of the distillation column.

[0152] In another particular embodiment, during the hydrodistillation step, the concentrated organic raffinate 13 or the organic raffinate 12 is introduced into the upper part of the distillation column, preferably into the upper half of the distillation column, while the aqueous liquid is also introduced into the distillation column. The mixing with the aqueous liquid is then carried out within the distillation column.

[0153] Given the formation of a heterogeneous azeotrope between water and the extraction solvent during the hydrodistillation step, the condensation of the vapors at the top of the distillation column generates two liquid phases: a water-rich phase which can advantageously be returned to the column as reflux, and an organic solvent-rich phase 16 which can advantageously be recycled in the extraction step d).

[0154] According to the invention, the aqueous solution 15 of 5-HMF obtained at the end of the hydrodistillation step, has an amount 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 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 step.

[0155] The process according to the invention advantageously makes it possible to produce an aqueous solution of 5-HMF having very advantageously a weight content of polar aprotic synthesis solvent (e.g. DMSO) less than or equal to 10% weight relative to the weight of 5-HMF, preferably less than or equal to 5% weight relative to the weight of 5-HMF and preferably less than or equal to 3% weight relative to the weight of 5-HMF.

[0156] According to one or more alternative embodiments to hydrodistillation, the purification step g) comprises, and may consist of, at least one step of crystallizing the 5-HMF contained in the organic raffinate 12 from step e) or said concentrated organic raffinate 13 from step f), followed by filtration, to produce a 5-HMF stream comprising solid 5-HMF (5-HMF crystals) and an organic solvent-rich filtrate.

[0157] Crystallization can be achieved by all methods known to those skilled in the art, for example by lowering the temperature, increasing the concentration of 5-HMF to be crystallized, increasing the concentration of 5-HMF to be crystallized with lowering the temperature, or by adding a third compound which is a poor solvent for the 5-HMF to be crystallized.

[0158] The conditions are those known to a person skilled in the art. The temperature is preferably less than or equal to 30°C, and generally between -100°C and 0°C, preferably between -50°C and 0°C, and even more preferably between -40°C and -10°C.

[0159] The filtrate rich in organic solvent, essentially extraction solvent, is advantageously recycled, in part or in whole (after possible purging) to step d) of liquid-liquid extraction to carry out a new extraction of 5-HMF.

[0160] According to methods known to the person skilled in the art, step g) of purification based on crystallization is carried out in one or more passes, and the crystals are washed and dried.

[0161] Optional step h) of treatment of aprotic polar synthetic water-solvent mixtures

[0162] The process according to the invention may include an optional step h) of treating water-aprotic polar synthetic solvent mixtures (e.g., DMSO) generated by the steps of the process according to the invention, to produce an aqueous effluent (also called distillate), which may be used in whole or in part in the backwashing step e) and / or in step c) and / or in step g). This step may also produce a stream 18 rich in aprotic polar synthetic solvent (e.g., DMSO) and a stream of impurities 19. At least one water-aprotic polar synthetic solvent mixture produced in the process is therefore treated in step h). Said mixture may be the aqueous raffinate 8 from step d).

[0163] This step makes it possible to separate within said at least one mixture (aqueous raffinate 8 from step d)), water, the aprotic polar synthesis solvent and reaction products extracted in the raffinate such as unconverted sugars, sugar oligomers, residual 5-HMF.

[0164] One or more other aprotic polar synthesis water-solvent mixtures produced within the process may be sent to step h).

[0165] If the process incorporates (i) concomitant water extraction from the reaction medium during step a) or (ii) a step of separating the water contained in the sugar feed upstream of step a), in the case where the latter is initially in the form of a syrup, comprising the extraction and substitution of the water from the syrup by aprotic polar synthesis solvent, then the synthesis solvent-rich stream 16 can be purged of its water at the same time as the water extraction in these two cases (i) and (ii).

[0166] The residual quantity of aprotic polar synthesis solvent (e.g. DMSO) in the aqueous effluent produced at the end of step h) is lower the more efficiently the distillation is carried out according to the knowledge of a person skilled in the art.

[0167] The water-solvent mixtures of aprotic polar synthesis (e.g., DMSO) generated by the process refer in particular to the aqueous raffinate 8 produced in step d), and even currently the water-solvent mixture of polar aprotic synthesis (e.g. DMSO) resulting from the dehydration step of sugars into 5-HMF.

[0168] Step h) of treatment of water-solvent mixtures of polar aprotic synthesis (e.g. DMSO) preferably implements an evaporation section of a water-solvent mixture of polar aprotic synthesis (e.g. DMSO), to remove any impurities in the form of stream 19 in particular heavy impurities such as humins or unconverted sugars, followed by a distillation section.

[0169] The evaporation section is operated at a temperature preferably between 80°C and 130°C, preferably between 100°C and 120°C, and preferably at a pressure between 0.0001 MPa and 0.0200 MPa, preferably between 0.0002 MPa and 0.0100 MPa, preferably between 0.0005 MPa and 0.0050 MPa. Preferably, the evaporation section is implemented by a thin film evaporator (TFE).

[0170] The distillation section advantageously uses a distillation column or several separate pieces of equipment. Preferably, the distillation section of step h) is advantageously implemented in a distillation column, at a column top temperature preferably between 25°C and 60°C, preferably between 45°C and 55°C, for example about 50°C, preferably at a column bottom temperature between 80°C and 140°C, preferably between 100°C and 130°C, for example about 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 between 0.01 and 0.50, preferably between 0.05 and 0.10.

[0171] Thus, the aqueous raffinate 8 produced in step d) and comprising water and aprotic polar synthesis solvent (e.g., DMSO), and optionally the water-aprotic polar synthesis solvent (e.g., DMSO) mixture recovered in the dehydration step, are evaporated, and then the gaseous phase is recovered and distilled, preferably under vacuum, so as to produce a residue 18 rich in aprotic polar synthesis solvent (e.g., DMSO) on the one hand, a distillate 20 rich in water (corresponding to the aqueous effluent) on the other hand, and, finally, a stream 19 containing the heavy fractions such as unfiltered humins and unconverted humin sugars. By rich, we mean here at least 95 wt., preferably at least 98 wt. Part or all of the water-rich distillate, or aqueous effluent, can advantageously be recycled in step e) as an aqueous solvent to carry out the backwashing step and / or to the hydrodistillation step in step g) as an aqueous stream.The said water-rich distillate can also be, in whole or in part, recycled as water introduced in step c).

[0172] The residue rich in aprotic polar synthesis solvent (e.g., DMSO) can advantageously be introduced at the dehydration step, either directly or after distillation allowing the removal of heavy products that could accumulate.

[0173] The example and figure described in detail below illustrate the invention without limiting its scope.

[0174] Figure 1 illustrates a particular embodiment of the process according to the invention. The sugar feed 1 is contacted in step a) with a polar aprotic synthesis solvent, e.g., DMSO, and an acid dehydration catalyst, at a temperature between 30°C and 200°C and at a pressure between 0.001 MPa and 10 MPa, so as to produce a synthesis effluent 2 containing 5-HMF and said polar aprotic synthesis solvent. The synthesis effluent 2, optionally neutralized with a basic compound, is sent to the concentration step b) to concentrate the synthesis effluent in 5-HMF and thus produce a concentrated synthesis effluent 3 and a stream 3' containing the synthesis solvent. The concentrated synthesis effluent 3, containing 5-HMF, aprotic polar synthesis solvent (e.g. DMSO) and humins, is sent to step c) and is brought into contact with an aqueous stream 5.The aqueous mixture 6 obtained at the end of step c) is sent to the extraction step d) and mixed with an extraction solvent 7 in order to extract the 5-HMF from the aqueous mixture by the extraction solvent and to obtain an aqueous raffinate 8 and an organic extract 9. The organic extract 9 is mixed with an aqueous solvent 10 in the backwashing step e). The organic raffinate 12 obtained at the end of step e) can be concentrated in the optional liquid-liquid post-extraction concentration step f) by removing the stream 14, which can be recycled in step d). The organic raffinate 12 obtained at the end of step e), or alternatively the concentrated organic raffinate 13 obtained at the end of step f) if it is carried out, is treated in a purification step g) comprising a hydrodistillation column in order to remove the residual organic solvent 16, and to obtain the aqueous solution 15 of 5-HMF. .

[0175] The aqueous raffinate 8 from the liquid-liquid extraction step d) is sent to step h) of treatment of the water-solvent mixtures of polar aprotic synthesis. Step h) produces an aqueous effluent 20, an enriched stream of polar aprotic synthesis solvent 18 and a heavy fraction stream 19 containing the unfiltered humins and unconverted sugars (humins and sugars being in liquid form although very viscous at the temperature of the mixture treatment).

[0176] In the embodiment shown, a liquid-solid separation step can be carried out on the mixture 6 formed in step c) to separate precipitated humines (solid particles) in step c) from the rest of said mixture, producing a solid stream 4.

[0177] The aqueous stream 5 used in step c) of mixing may include recycled water from the process, in particular the aqueous stream 5 includes the backwash extract 11 and may include a fraction of the aqueous effluent 20 produced in step h) of treatment of the aprotic polar synthetic water-solvent mixtures.

[0178] The aqueous solvent 10 used in backwashing step e) may comprise a fraction of the aqueous effluent 20 produced in step h) of the treatment of the aprotic polar synthetic water-solvent mixtures and makeup water (i.e., external to the process, in other words, neither produced nor recycled within the process). Alternatively, the aqueous solvent 10 used in backwashing step e) consists of a fraction of the aqueous effluent 20 produced in step g), without makeup water. In this case, makeup water may be sent to step c), to form the aqueous stream 5, which comprises a fraction of the aqueous effluent 20 produced in step h). The addition of makeup water to the process may be necessary despite the water recycling operations.

[0179] The aqueous stream 17 used in hydrodistillation in step g) can be made up of a fraction of the aqueous stream 20 produced in step h) of treatment of the aprotic polar synthesis water-solvent mixtures.

[0180] The extraction solvent 7 used in step d) of extraction can be composed of the solvent streams produced in steps f) and g). In other words, the organic solvent streams 14 and 16 produced respectively in steps f) and g) are recycled in step d), and in particular form part of the composition of the extraction solvent 7. This illustrated embodiment can therefore include recycling the aqueous effluent 20 from step h) of treatment of the water-solvent mixtures of polar aprotic synthesis in steps c), e) and g), and recycling of the organic solvent streams 14 and 16 in step d) of liquid-liquid extraction, which allows on the one hand optimal management of water within the process by integrating its treatment within the process and avoiding excessive water additions, and on the other hand minimizes the consumption of extraction solvent, the whole having in the end a favorable impact on the operating costs and the environmental impact of the process. The products obtained and their method of analysis

[0181] The product obtained by the process according to the invention is 5-hydroxymethylfurfural (5-HMF).

[0182] The contents of 5-HMF, organic acids, and residual sugars can be determined at the end of synthesis step a), or at the end of 5-HMF concentration step b) by high-performance liquid chromatography (HPLC). Humins are not eluted by this analytical system. At the synthesis stage, however, their concentration is estimated by performing a molar carbon balance. The deficit in the balance is attributed to humins.

[0183] List of numerical references used in the figure: 1: sugar load 2: synthetic effluent 3: Concentrated synthetic effluent 3': synthetic solvent flow 4: Solid flux 5: Aqueous flow 6: aqueous mixture 7: Extraction solvent 8: aqueous refiner 9: organic extract 10: aqueous solvent 11: intermediate aqueous counter-extract 12: organic refiner 13: Concentrated organic raffinate 14: first stream including organic solvent 15: aqueous solution of 5-HMF 16: second stream including organic solvent. 17: aqueous liquid 18: solvent-rich flux of aprotic polar synthesis (or rich "residue"...) 19: Impurity flux (or heavy fraction flux) 20: Recyclable aqueous effluent Examples

[0184] The examples below are intended to show some of the advantages of the process according to the invention, operated according to the embodiment shown in [Fig. 1], and producing an aqueous solution of 5-HMF. Table 1 below summarizes the results of the 5 examples presented thereafter.

[0185] [Tables 1] Parameters Units Example 1 Example 2 Example 3 Example 4 Example 5 Fructose / DMSO mass ratio at synthesis step a) 25 / 75 25 / 75 10 / 90 10 / 90 10 / 90 Concentration step b) and DMSO content at the outlet of b) No Yes 45% wt. DMSO Yes 80% wt. DMSO (Q = Q example 1) Yes 77% wt. DMSO (E = E example 1) Yes 45% wt. DMSO mass factor at concentration step b) [wt / wt] 1 3.1 2.7 3.2 7.8 5-HMF yield at synthesis [%mol] 80.0% 80.0% 85.0% 85.0% 85.0% 5-HMF yield at extraction (L / Ld) [%mol] 98.1% 99.8% 98.1% 98.5% 99.8% Overall 5-HMF yield [%mol] 78.5% 79.8% 83.4% 83.7% 84.8% Flow rate Q at the extraction inlet (L / Ld) [kg / h] 8957 2453 8964 7350 2462 Energy consumption [MW / t5.HMF] 14.9 5.3 17.3 14.8 7.5 E

[0186] Example 1 - Synthesis of 5-HMF according to the prior art, without a post-synthesis concentration step and liquid-liquid pre-extraction, and a fructose / DMSO ratio of 25 / 75 at synthesis

[0187] Example 1 is an embodiment of a prior art process, without step b) of concentrating the reaction effluent before the liquid-liquid extraction step. The process according to this example comprises steps a), c), d), e), f), g), and h) similar to those described for the process according to the invention. It serves as a reference to illustrate some of the advantages of the invention.

[0188] Step a) of sugar dehydration to 5-HMF is carried out in batch mode in a stirred tank. The tank is prepared by adding crystalline fructose, DMSO, and methanesulfonic acid (MSA) as a catalyst. The average hourly flow rate of fructose is 1 t / h. The mass ratio of sugar to DMSO is 25 / 75. The molar ratio of catalyst to sugar is 2.5 mol% MSA / fructose. The reaction is carried out at ambient pressure (0.1013 MPa), 120°C, for a duration of 2 h, after which the mixture is neutralized with sodium hydroxide (MSA / NaOH molar ratio = 1) and cooled to room temperature.

[0189] Under these conditions 99% of the fructose is converted with a molar carbon yield of 80% to 5-HMF, 19% to co-products and 1% to fructose.

[0190] Step c) of mixing, which brings the synthesis effluent from step a) into contact with an aqueous stream, is carried out at ambient pressure and temperature in a stirred tank. Water is added so that the water / DMSO mass ratio of the mixture is equal to 1.4. There is no liquid-solid separation in this example. The mixture is then transferred to step d) of liquid-liquid extraction.

[0191] Step d) of liquid-liquid extraction is carried out in a pulsed column comprising 9 theoretical stages. The extraction solvent is methyl isobutyl ketone (MIBK), and the extraction is performed at ambient pressure and temperature with a mass ratio of extraction solvent to feed (aqueous mixture 6) of 1.9 wt / w. Under these conditions, the extraction yield of 5-HMF is 98.0%.

[0192] The backwash step (e) is carried out in a structured packed column with two theoretical stages. It is operated at ambient pressure and temperature. The backwash solvent is recycled water from the process as described above in step (e) and illustrated in [Fig. 1] (aqueous effluent 20). The quantity used is such that the mass ratio of aqueous backwash solvent to feedstock (organic extract 9 from step (d)) is 0.1 wt / wt.

[0193] Step f) of post-extraction liquid-liquid concentration is an evaporation carried out at 90°C and 0.015 MPa absolute (150 mbar) which produces an organic raffinate enriched with a 5-HMF content of 50% by weight.

[0194] Purification step g) is hydrodistillation through a distillation column comprising 7 theoretical stages and operating pressure at the column head of 0.04 MPa absolute (400 mbar). The reflux ratio and reboiling power are adjusted to produce an aqueous 5-HMF solution containing 75 wt% 5-HMF and 0.1 wt% MIBK. The temperatures are 70°C at the column head (vapor phase exiting the column and entering its condenser) and 88°C at the reboiler outlet.

[0195] Step h) of the treatment of the water-solvent mixtures of polar aprotic synthesis is a succession of three evaporation systems (cascade exchangers / separation flask) operated at 120°C. The pressure is successively reduced to 0.09 MPa absolute / 0.015 MPa absolute / 0.0005 MPa absolute (900 mbara / 150 mbara / 5 mbara), which makes it possible to reach a residual value of DMSO in the stream 19 of the order of 15 wt%.

[0196] The vapors from these three steps are condensed to form three distillates, which are sent to a 9-plate distillation column operated with a reflux ratio of 15 wt% (mass ratio of reflux to column charge). The pressure at the top of the column is 0.01 MPa absolute (100 mbar). The bottom product is DMSO containing 0.1 wt% water, which is recycled in step a). At the top, the water produced is used in steps c) and e).

[0197] Under these conditions, the synthesis in step a) is therefore carried out with a DMSO dilution rate of 75% by weight. The inlet flow rate for step d) of liquid / liquid extraction is 8957 kg / h. The 5-HMF synthesis yield is 80% molar, and the 5-HMF extraction yield is 98.1%, resulting in a sugar-to-5-HMF yield of 78.5% molar. If we sum all the energy inputs to the process, the consumption is 14.9 MW / t5_HMF (MW / tonne of 5-HMF), supplied here by steam.

[0198] Example 2 - Synthesis of 5-HMF according to the invention, with a post-synthesis concentration step b) and liquid-liquid pre-extraction and a fructose / DMSO ratio of 25 / 75 at synthesis

[0199] In Example 2, the process is carried out under the same conditions as the process in Example 1 (pressure, temperatures, solvent ratios, sugar charge, synthesis catalyst, nature of solvents). According to the invention, the process according to Example 2 includes a step b) of 5-HMF concentration. Evaporation is carried out at 0.005 MPa absolute (50 mbar) and 120°C in step b). The effluent from the synthesis step a) is therefore neutralized, but not cooled. Under these conditions, the DMSO concentration decreases from 75 wt% at the synthesis outlet to 45 wt% at the end of the concentration step b), before being fed into the mixing step c).

[0200] Steps c), d) and e) are carried out with the same water and solvent ratios as in Example 1.

[0201] Step b) of concentration results in a reduction of the inlet flow rate of step d) of liquid-liquid extraction, compared to Example 1, which is 2453 kg / h (for a similar quantity of 5-HMF). By increasing the concentration of 5-HMF in step b), the liquid-liquid extraction performance is significantly improved and increased from 98.1% (Example 1) to 99.8% (Example 2), which makes it possible to achieve an overall molar yield of fructose to 5-HMF of 79.8%, representing an increase of 1.3% molar compared to the reference Example 1.

[0202] Similarly, reducing the flow rates of solvents treated in steps f) and h) allows for a significant energy saving: the requirement is 5.3 MW / t5 HMF in example 2, i.e. an energy saving of 65% compared to example 1.

[0203] Example 2 therefore illustrates the contribution of a concentration trap on the energy consumption of the process and the gain in 5-HMF yield attributable to the gain in performance of the liquid-liquid extraction.

[0204] Example 3 - Synthesis of 5-HMF according to the invention, with a post-synthesis concentration step b) and liquid-liquid pre-extraction and a fructose / DMSO ratio of 10 / 90 at synthesis

[0205] Example 3 illustrates in particular the interest of a step b) of concentration in 5-HMF with regard to the yield in 5-HMF during step a) of dehydration of sugars in 5-HMF.

[0206] Example 3 is identical in every respect to that of Example 1, except that it includes a concentration step b), and that the mass ratio between sugar (crystalline fructose) and DMSO is 10 / 90 instead of 25 / 75 in Example 1. Under these conditions the molar carbon yield is 85% to 5-HMF, i.e. a gain of 5% compared to Example 1.

[0207] The concentration step b) is carried out at 120°C and 0.0106 MPa absolute (106 mbara) in order to maintain a flow rate Q at the inlet of liquid-liquid extraction step d) of approximately 8960 kg / h, comparable to that of example 1.

[0208] Step c) of mixing is carried out in the same way and with the same ratio of water and solvent as in example 1 (water / DMSO of the mixture is equal to 1.4).

[0209] The performance of the liquid / liquid extraction in step d) is not impacted compared to Example 1, with an extraction yield of 5-HMF in Example 3 of 98.1% as in Example 1. Over the entire process according to Example 3, the yield of 5-HMF then reaches 83.4 mol%, an increase of 4.9 mol% compared to Example 1.

[0210] The operating conditions of steps d), e), f), g) and h) are identical to those presented in Example 1. This implementation results in overconsumption energy of the process linked to the concentration step. It reaches 17.3 MW / t5 HMF, an increase of 16% compared to example 1.

[0211] According to the implementation of the process described in this example 3, the process offers a significant gain in 5-HMF yield (+4.9 mol%), even if this is at the expense of an increase in energy requirement (+16%), which may be acceptable if priority is given to 5-HMF yield.

[0212] Example 4 - Synthesis of 5-HMF according to the invention, with a post-synthesis concentration step b) and liquid-liquid pre-extraction and a fructose / DMSO ratio of 10 / 90 at synthesis

[0213] In this Example 4, the process is implemented identically to Example 3, except that concentration step b) is carried out at a different pressure, 0.0099 MPa absolute (99 mbar) compared to 0.0106 MPa absolute (106 mbar) in Example 3. This slight decrease in pressure in step b) allows for slightly greater concentration of the 5-HMF in step b), resulting in a flow rate Q at the inlet of liquid-liquid extraction step d) of 7350 kg / h, lower than in Example 3 (8964 kg / h). The lower flow rate improves the 5-HMF extraction yield in step d), which is increased to 98.5%. The overall 5-HMF yield of the process is then 83.7% mol, an increase of 5.3% mol compared to the reference case of example 1.

[0214] The reduced flow rate at the inlet of step d) liquid-liquid extraction compensates for the energy requirement of step b) concentration. This results in a consumption of 17.4 MW / t5 HMF, similar to that of the reference case illustrated in Example 1.

[0215] According to this implementation example, the process therefore does not offer any gain in energy consumption but makes it possible to significantly improve the fructose to 5-HMF yield of the whole process.

[0216] Example 5 - Synthesis of 5-HMF according to the invention, with a post-synthesis concentration step and liquid-liquid pre-extraction and a fructose / DMSO ratio of 10 / 90 at synthesis

[0217] In this example 5, a contribution of the invention is illustrated both from the point of view of the yield in 5-HMF during the synthesis and the overall energy consumption of the process.

[0218] The implementation and operating conditions are equivalent to those of Examples 3 and 4, with the exception of concentration step b), which is carried out at an absolute pressure of 0.0036 MPa (36 mbar). Under these conditions, despite the high dilution of the reaction medium in step a) (fructose / DMSO mass ratio of 10 / 90), as in Examples 3 and 4, and therefore of the synthesis effluent, the synthesis effluent concentrated at the end of step b) contains 45% wt% DMSO, i.e., a "dilution" of 5-HMF in the concentrated effluent identical to that of the process described in work in example 2. We then find a flow rate at the inlet of step d) of liquid-liquid extraction and extraction performance comparable to those of example 2 (2462 kg / h at the inlet of step d) and an extraction yield of 5-HMF at step d) of 99.8%).

[0219] Compared to Example 1, the overall yield of the process in 5-HMF is increased from 78.5 mol% to 84.8 mol%, 5% being attributable to step a) via the mass ratio fructose / DMSO (high "dilution rate" of 5-HMF in DMSO) of the reaction, and 1.4% being related to a gain on the recovery of 5-HMF in step d) of liquid-liquid extraction carried out in both cases with an identical extraction solvent / feed ratio (aqueous mixture 6).

[0220] The total energy consumption of the process is 7.5 MW / t5 HMF, i.e. a gain of 50% compared to example 1.

[0221] This example 5, compared to example 1, illustrates the set of benefits shown in examples 2 to 4, offered by the invention: - Increased yield of 5-HMF is possible at the synthesis stage by increasing the dilution with the aprotic polar synthesis solvent (e.g., DMSO). - Increased 5-HMF extraction yield at step d) of liquid-liquid extraction by step b) of pre-concentrating the feed sent to the liquid-liquid extraction, - energy consumption gain of the process despite an additional step (step b) of concentration) downstream of step a) of dehydration of sugars into 5-HMF.

Claims

Claims

1. A process for producing hydroxymethylfurfural (5-HMF) comprising the following steps: - a step a) of contacting a sugar feedstock comprising a hexose (1) with at least one aprotic polar synthesis solvent and at least one acid dehydration catalyst so as to produce a synthesis effluent (2) containing 5-HMF and said aprotic polar synthesis solvent, said contacting being carried out at a temperature of between 30°C and 200°C and at a pressure of between 0.001 MPa and 10 MPa; - a step b) of concentrating said synthesis effluent (2) with 5-HMF so as to obtain a concentrated synthesis effluent (3); - a step c) of contacting said concentrated synthesis effluent (3) with an aqueous stream (5), so as to obtain at least one aqueous mixture (6);- a step d) of liquid-liquid extraction of the aqueous mixture (6) obtained at the end of step c) in the presence of an extraction solvent (7), so as to produce an aqueous raffinate (8) comprising said aprotic polar synthesis solvent, and an organic extract (9) comprising 5-HMF and the extraction solvent; then - a step e) of backwashing the organic extract (9) with an aqueous solvent (10), so as to produce an intermediate aqueous counter-extract (11) and an organic raffinate (12) comprising 5-HMF and an organic solvent; - an optional step f) of concentrating said organic raffinate (12) from step e) by removing at least a portion of the organic solvent, producing a concentrated organic raffinate (13) comprising 5-HMF, and residual organic solvent, and producing a first stream (14) comprising organic solvent;- a step g) of purifying said organic raffinate (12) or said concentrated organic raffinate (13) to produce a 5-HMF stream (15).;

2. Method according to claim 1, further comprising a step of neutralizing the synthesis effluent (2) from step a) prior to step b), preferably by bringing said synthesis effluent (2) into contact with a basic compound.

3. A method according to claim 1 or claim 2, wherein the concentration mass factor in step b), corresponding to the ratio mass ratio between said synthesis effluent (2) and said concentrated synthesis effluent (3), is between 1.2 and 20, preferably between 1.5 and 20, preferably between 1.5 and 15, and preferably between 2 and 10.

4. Process according to any one of the preceding claims, wherein said synthesis effluent (2) from step a) comprises a 5-HMF / aprotic polar synthesis solvent ratio of between 5 / 95 and 40 / 60, and said concentrated synthesis effluent (3) from step b) comprises a 5-HMF / polar synthesis solvent ratio of between 30 / 70 and 70 / 30.

5. A method according to any one of the preceding claims, wherein step b) comprises evaporation or distillation to vaporize a portion of the aprotic polar synthesis solvent, carried out at a temperature less than or equal to 200°C, preferably less than or equal to 150°C, and preferably less than or equal to 130°C, and at atmospheric pressure or under vacuum, preferably at a pressure of between 0.0001 MPa and 0.1000 MPa, preferably under vacuum at a pressure of between 0.0001 MPa and 0.0500 MPa.

6. A method according to any one of the preceding claims, wherein the purification step g) is a hydrodistillation step carried out by distillation in the presence of water (17) of said organic raffinate (12) from step e) or said concentrated organic raffinate (13) from step f), to produce said 5-HMF stream being an aqueous 5-HMF solution (15) and a second stream (16) comprising organic solvent, preferably said hydrodistillation being carried out in a distillation column, at atmospheric pressure or under vacuum, preferably at a pressure of between 0.001 MPa and 0.1 MPa, and preferably under vacuum at a pressure of between 0.005 MPa and 0.08 MPa, and 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, preferably less than or equal to 100°C.

7. A method according to any one of claims 1 to 5, wherein the purification step g) comprises at least one step of crystallization of the 5-HMF contained in said organic raffinate (12) from step e) or said concentrated organic raffinate (13) from step f), followed by filtration, to produce said 5-HMF stream comprising solid 5-HMF and a filtrate rich in organic solvent.

8. A method according to any preceding claim, further comprising a step h) of treating at least one water-solvent mixture of polar aprotic synthesis produced in said process to produce at least one aqueous effluent (20) recyclable in said process, said mixture comprising said aqueous raffinate (8) from step d).

9. Method according to any one of the preceding claims, further comprising a liquid-solid separation step, preferably a filtration of the aqueous mixture produced in step c) or of an intermediate liquid stream produced during the liquid-liquid extraction step d) or of the aqueous raffinate (8) from step d).

10. Method according to one of the preceding claims, comprising step f) of concentrating the organic raffinate (12) from step e) comprising vaporization of the organic solvent at atmospheric pressure or under vacuum, preferably at a pressure of between 0.01 MPa and 0.10 MPa, and a liquid temperature maintained less than or equal to 130°C, said concentrated organic raffinate (13) comprising 5-HMF at a content greater than or equal to 30% by weight and residual organic solvent at a content less than or equal to 60% by weight.

11. A method according to any preceding claim, wherein the hexose is fructose or a fructosidic unit.

12. A process according to any preceding claim, 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 in mixture, and is preferably dimethyl sulfoxide.

13. A method according to any preceding claim, wherein the 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.

14. A method according to any one of the preceding claims, wherein in step c) said aqueous stream (5) comprises all or a fraction of said intermediate aqueous counter-extract (11) from step e).

15. A method according to any one of claims 8 to 14, wherein said aqueous effluent (20) produced in step h) is used in whole or in part in step c) and / or in step e) and / or in step g).

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