Method for extracting an alcohol or a carboxylic acid from an aqueous solution in the presence of an enzyme catalyst in a two-phase medium in the form of a pickering emulsion

Abstract

The invention relates to a method for extracting a compound to be extracted, selected from among an alcohol and a carboxylic acid, from an aqueous solution by forming an ester in the presence of at least one reactant selected from among a carboxylic acid and an alcohol and of an enzyme catalyst, characterised in that the reaction mixture is in the form of a Pickering emulsion comprising at least a first water phase and an oil phase, the oil phase comprising at least one extraction solvent, wherein the ester formed in the oil phase is then hydrolysed in order to recover the compound to be extracted.

Description

[0001] METHOD FOR EXTRACTION OF AN ALCOHOL OR CARBOXYLIC ACID FROM AN AQUEOUS SOLUTION IN THE PRESENCE OF AN ENZYMATIC CATALYST IN A BIPHASIC MEDIUM IN THE FORM OF A PICKERING EMULSION.

[0002] technical field

[0003] The present invention relates to the field of extraction of alcohols or carboxylic acids in dilute and / or complex aqueous phases in a context of high demand for products from renewable resources and with low environmental impact.

[0004] State of the art

[0005] Alcohols and carboxylic acids can be obtained from biomass by fermentation, by oxidation (for carboxylic acids) of carbohydrates derived from biomass (cellulose, glucose, and glycerol), or by any process known to those skilled in the art. However, unlike the petrochemical industry, the processes used result in solutions that are dilute or even highly dilute in water. In addition, there are co-products due to the non-selectivity of the reactions and impurities present in the raw materials. These conditions therefore lead to highly complex mixtures.

[0006] One example is the production of bio-based alcohols as products of a must obtained after the fermentation of an aqueous solution of C5 and / or C6 sugars, as is known from IBE (Isopropanol / Butanol / Ethanol) or IBEA (Isopropanol / Butanol / Ethanol / Acetone) fermentation processes carried out by "solutogenic" Clostridium strains. Fermentation must refers to the aqueous medium in which fermentation took place. C5 and / or C6 sugars refer to monosaccharides with 5 or 6 carbon atoms. One of the challenges encountered in the development of fermentation processes is the recovery of products highly diluted in the fermentation must. This is a determining factor in the economic cost of these types of processes.In order to make this production process via fermentation economically viable, it is important to seek to limit the energy consumption related to the extraction phase of the molecules of interest from the fermentation must.

[0007] We can also cite, for example, the production of bio-based carboxylic acids, which is of interest to various sectors. They can be used directly, for example in the food industry as additives, or as reaction intermediates in many products used in the chemical, pharmaceutical and plastics industries (Chandel et al., Advances in Sugarcane Biorefinery Technologies, Commercialization, Policy Issues and Paradigm Shift for Bioethanol and By-Products, 2018 DOI: 10.1016 / C2015-0-02033-0).

[0008] In this perspective, carboxylic acids can be obtained in aqueous phase, for example in the case of the catalytic oxidation of glycerol as described in patent application WO2014199256, or by fermentation, derived from lignin.

[0009] One example is the conversion of carbohydrates (sugars, glucose, fructose, sucrose...) by fermentation which leads to acetic, succinic, lactic, itaconic, citric and gluconic acids as described by Lopez-Garzon CS (Lopez-Garzon, CS et al, Recovery of carboxylic acids produced by fermentation. Biotechnology Advances, 2014, 32, 873-904).

[0010] We can also mention the conversion of lignocellulosic carbohydrates by catalytic oxidation, which are reactions that are not very selective and lead to mixtures of very polar compounds.

[0011] Another example is the oxidation of glycerol (described in patent application WO2014199256), which leads to oxalic acid, formic acid, and alpha-hydroxy acids such as lactic acid, glycolic acid, glyceric acid, and tartronic acid. Their alcohol functional group gives them greater solubility in water, making their separation from water more difficult. Furthermore, some decompose when heated for distillation. Others also tend to polymerize, making their purification costly and complex.

[0012] Therefore, separation processes must be used to purify these compounds. However, these processes have an energy cost that significantly increases the carbon footprint of the final product. Examples include vaporization, distillation, or membrane separation (see patents US8906204B2, US11471786B2, and US10961489B2), or stripping of the fermentation wort with a gas stream (patent application WO2018 / 001628). Liquid-liquid extraction processes also exist, but these do not allow for 100% extraction of the compound of interest (see patent US0149757), especially if the compound is highly diluted in water.

[0013] Regarding carboxylic acids in particular, review articles detail recovery processes in fermentation processes (Lopez-Garzon, CS et al, Recovery of carboxylic acids produced by fermentation. Biotechnology Advances, 2014, 32, 873-904) and under conditions of high dilution (Talnikar, VD et al, Recovery of acids from dilute streams: A review of process technologies. Korean Journal of Chemical Engineering, 2014, 31 (10), 1720-1731). Distillation and extraction are examples, but they are difficult to implement and expensive. The concentration and purification of these carboxylic acids can represent 60% to 70% of the product cost, making these technologies impractical.

[0014] One example is precipitation in the form of a salt, for example a calcium salt, which has the disadvantage of generating many by-products because it is then necessary to clarify, that is to say, to add a mineral acid and recover a salt on one side and the carboxylic acid on the other.

[0015] Membrane separation (nanofiltration and reverse osmosis, electrodialysis) can also be mentioned, which has the disadvantage of clogging by impurities and high costs (production of membranes, clogging problems requiring frequent cleaning and reducing the lifespan of membranes).

[0016] We can also mention adsorption on resins which has the disadvantage of having short material lifespans and a cost associated with material regeneration.

[0017] Another method involves forming an ester and extracting it in a second phase. Van Den Berg et al. (Biotechnology Bioengineering, 110(1), 2013) propose reacting butanol formed by fermentation with butyric acid, both diluted in water, using an enzymatic catalyst in aqueous solution, and extracting the resulting ester, butyl butyrate, in an oil phase such as hexadecane. However, the contact surface area between the oil and water phases is small in this implementation, which significantly slows ester extraction and thus the esterification reaction. The process described in US patent 0178529 has the same drawback.

[0018] Patent CN 114606222 describes a process for reacting methanol in aqueous solution with lauric acid in an oil phase, in the presence of a biocatalyst. A Pickering emulsion is prepared to stabilize the emulsion and facilitate the exchange between the two phases. In this case, the methanol is in very high excess to maximize the conversion of lauric acid, as the purpose of this patent is the synthesis of an ester, not the extraction of an alcohol from an aqueous phase. The methanol is therefore highly concentrated in the water (15% to 50% wt%). Since this concentration is problematic for the enzyme used, the enzyme must be encapsulated beforehand, and these capsules containing the enzyme are used to prepare the Pickering emulsion.Given the size of the capsules, the size of the water phase droplets dispersed in the oil phase is particularly large (150 µm to 650 µm), that is, one to two orders of magnitude larger than what could be achieved with a Pickering emulsion not constrained by enzyme encapsulation. Since the exchange surface area between the two phases is inversely proportional to the droplet size, the exchange surface area is reduced in this case, thus hindering the transfer of molecules between the phases.

[0019] Subject of the invention: The applicant has developed a process for extracting an alcohol or a carboxylic acid by forming an ester in the presence of an enzymatic catalyst in a biphasic medium in the form of a Pickering emulsion, followed by a hydrolysis step of this ester to recover said alcohol or carboxylic acid. This process allows for extractions with optimized yields and rates from alcohols or carboxylic acids present in dilute aqueous solutions. This is particularly relevant when the alcohols or carboxylic acids are bio-based.

[0020] The biocatalyst (enzymatic catalyst) used in the invention also enables reactive extraction in a dilute medium where a chemical catalyst would not have allowed the same esterification reaction to occur. Furthermore, the temperatures involved are much lower in this case, thus reducing the carbon footprint of the process.

[0021] The use of an emulsion according to the invention also allows the ester to be extracted from the oil phase as it is formed. Since the esterification reaction is an equilibrium reaction, meaning it is not complete, the transfer of the ester to the oil phase shifts the equilibrium in a way that favors ester production and thus increases the extraction of the alcohol or carboxylic acid.

[0022] The use of a Pickering emulsion according to the invention allows the emulsion to be optimized by developing a large exchange surface between the two phases, which greatly promotes the extraction of the alcohol or carboxylic acid.

[0023] This large exchange surface area offers an additional advantage if one of the two reactants is introduced into the oil phase to facilitate its transfer from the oil phase to the water phase, where the reaction takes place in the presence of the biocatalyst. This is the case, for example, with fatty carboxylic acids and fatty alcohols, which have sufficiently long carbon chains to significantly reduce their water solubility. They are then solubilized in the oil phase. The Pickering emulsion allows their reaction in water despite their low water solubility. The large exchange surface area generated between the two liquid phases compensates for this low solubility, and the microreactors created by the Pickering emulsion promote the reaction kinetics.

[0024] The Pickering emulsion also eliminates the need for vigorous agitation, which is traditionally required to transfer a molecule between two liquid phases, thus reducing the energy demand of the process. The Pickering emulsion produces an emulsion that remains stable after its creation; no additional energy is needed to maintain contact between the two liquid phases.

[0025] Pickering emulsions thus also allow for continuous implementation, for example, by continuously adding reagent to the continuous phase and / or continuously withdrawing the continuous phase to separate the reaction products and / or by continuously adding aqueous solution containing the compound to be extracted. Pickering emulsions offer the additional advantage over surfactant-stabilized emulsions of not using products that could impact the environment and of using solids that are easily separable from liquids.

[0026] The present invention relates to a process for extracting a compound to be extracted, selected from an alcohol or a carboxylic acid in an aqueous solution, by forming an ester comprising the following steps: a) an esterification reaction is carried out on a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion to form an ester in the oil phase, said reaction mixture being obtained according to the following steps: a1) a biphasic mixture is formed comprising at least a first water phase and an oil phase, by contacting an aqueous solution comprising said compound to be extracted, at least one reagent selected from a carboxylic acid or an alcohol, at least one enzymatic catalyst, at least one organic extraction solvent and solid particles; a2) said biphasic mixture obtained in step a1) is emulsified to form a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion;said reaction mixture comprising:;

[0027] -either droplets of said oil phase stabilized by said solid particles in said first water phase;

[0028] -either droplets of said first water phase stabilized by said solid particles in said oil phase; b) said oil phase containing the ester formed at the end of step a) is separated; c) the ester obtained at the end of step b) is hydrolyzed to reform said compound to be extracted; d) said compound to be extracted is recovered.

[0029] Advantageously, the compound to be extracted is an alcohol and the reagent is a carboxylic acid.

[0030] Advantageously, the compound to be extracted is a carboxylic acid and the reagent is an alcohol.

[0031] Advantageously, the concentration of the compound to be extracted in said aqueous solution is between 0.001 mol / L and 0.4 mol / L when said compound to be extracted is an alcohol, and between 0.001 mol / L and 2 mol / L when said compound to be extracted is a carboxylic acid.

[0032] Advantageously, the molar ratio between said reagent and said compound to be extracted is between 1 and 10. Advantageously, said compound to be extracted is of bio-based origin.

[0033] Advantageously, the enzymatic catalyst added in step a1) is chosen from lipases of microbial or plant origin.

[0034] Preferably, the enzymatic catalyst added in step a1) is chosen from Candida antarctica lipase B, Candida rugosa lipase, or Rhizomucor miehei lipase.

[0035] Advantageously, the pH of the said first water phase is less than 7.

[0036] Advantageously, the solid particles added in step a1) are chosen from silica, clay, or synthetic polymer particles.

[0037] Advantageously, the droplet size of the Pickering emulsion obtained at the end of step a2) is between 1 pm and 140 pm.

[0038] Advantageously, the temperature of the esterification reaction in step a) is between 10°C and 90°C.

[0039] Advantageously, the mass concentration of solid particles added in step a1) is between 0.1 wt% and 10 wt% relative to the total weight of said two-phase mixture.

[0040] Advantageously, the ester is separated from said oil phase in a step b') between step b) and step c).

[0041] Advantageously, a step a') of production of said compound to be extracted chosen from said alcohol or said carboxylic acid in aqueous solution is carried out in combination with step a).

[0042] Detailed description of the invention

[0043] Definitions

[0044] The term "biomass" refers to all organic matter of plant or animal origin, but also any derived product or liquid effluent resulting from its mechanical, thermochemical, enzymatic or fermentation processes, as well as mixtures thereof.

[0045] The term "bio-based" or "renewable" means that the material / product / compound it describes is derived from biomass. In the text, the prefix "Bio" can also be used before the type of compound to characterize its bio-based nature: for example, biomethanol, bioethanol, biobutanol, bioisobutanol, bioacrylic acid, bioester. Emulsion and Pickering emulsion

[0046] An emulsion is a heterogeneous medium formed by the dispersion of one liquid in another. Emulsions are generally stabilized by surfactants due to their amphiphilic properties.

[0047] Emulsions can also be stabilized with solid particles; this is called a Pickering emulsion.

[0048] Pickering emulsions are indeed liquid / liquid dispersions stabilized by nanoparticles or aggregates of solid nanoparticles that accumulate at the interface between the two immiscible liquids (usually water and oil) and prevent coalescence (see for example the publication Pickering, SU (1907). J. Chem. Soc. Trans. 91, 2001-2021). In fact, the solid particles used to make Pickering emulsions are capable of irreversibly adhering to the interface between the two liquids, resulting in much more effective emulsion stabilization than surfactant adsorption (see, for example, the publication by Aveyard, R., Binks, B. P., and Clint, JH (Adv. Colloid Interface Sci. 100, 503-546, 2003)). The direction of the emulsion (water-in-oil or oil-in-water) is determined by the preferential wettability of the solid particles toward one phase or the other.In fact, the liquid that is most wetting towards the solid particles will constitute the continuous phase of the emulsion, and the least wetting the dispersed phase (see, for example, the publication Binks, B., and Lumsdon, S. (Langmuir 16, 8622-8631, 2000).

[0049] Pickering emulsions offer the advantage of facilitating mass transfer between the two liquid phases. Indeed, to ensure the transfer of a molecule between two liquid phases, it is necessary to create a large exchange surface between the two liquids.

[0050] An "emulsifier" is a compound or substance that acts as a stabilizer for emulsions, preventing liquids from separating.

[0051] A "hydrophobic" molecule or part of a molecule is a molecule that is repelled by a mass of water and other polar substances.

[0052] A "hydrophilic" molecule or part of a molecule is a molecule that tends to interact with or be dissolved by water and other polar substances.

[0053] "Amphiphile" is a term describing a chemical compound that possesses both hydrophilic and hydrophobic properties. Sizes of solids and...

[0054] Solid particle size: The solid particles according to the invention can be of various shapes and sizes, for example from a few nanometers to a few microns, or even tens of microns, in the form of substantially spherical or non-spherical beads (FB de Carvalho-Guimarães, K Leal Correa, T Pereira de Souza, JR Rodriguez Amado, RM Ribeiro-Costa and JO Carréra Silva-Júnior (2022) A Review of Pickering Emulsions: Perspectives and Applications, Pharmaceuticals, 15, 1413. https: / / doi.org / 10.3390 / ph15111413). The shape can be substantially spherical, or in the form of a rod, ellipsoid, needle, spindle, nanofibril, nanocage, plate, nanotube, nanocube, etc. (Li W, Jiao B, Li S, Faisal S, Shi A, Fu W, Chen Y and Wang Q (2022) Recent Advances on Pickering Emulsions Stabilized by Diverse Edible Particles: Stability Mechanism and Applications. Front. Nutr. 9:864943. doi: 10.3389 / fnut.2022.864943).The size can vary enormously, from a few nanometers to a few tens of microns. The size obviously depends on the morphology of the solid particles involved. It is generally determined by scanning and transmission electron microscopy. It is easy to define for spherical solid particles (diameter), and more difficult for solid particles whose shape deviates from sphericity (plates, rods, ellipsoids, needles, etc.). In these cases, two characteristic sizes are usually specified: the smallest and the longest. Another difficulty is related to the spontaneous formation of aggregates between the elementary solid particles. A distinction is then made between the size of the elementary solid particles and the size of the aggregates. For example, the commercial silica Aerosil R972 is a mixture of elementary solid particles between 5 and 50 nm with aggregates of average size on the order of 250 nm.

[0055] Preferably, the ratio in the emulsion between the largest dimension of the drops and the largest dimension of the solid particles is at least 100. (The largest dimension is understood to be the diameter when the solid particles are substantially spherical).

[0056] Droplet size: Droplet size refers to the largest dimension of the droplets measured by optical microscopy (notably by Olympus BX51 with analysIS software for image analysis).

[0057] Solubility

[0058] Solubility refers to the ability of a substance, called the solute, to dissolve in another substance, called the solvent. Depending on the solubility value, a certain percentage (mass fraction) of the substance is dissolved in the solvent. In the case of a liquid / liquid two-phase system, we speak of a substance's affinity for one phase. When a substance dissolves more than 50% of its mass in that phase, the remaining 100% is found in the other phase.

[0059] The invention relates to a process for extracting a compound to be extracted, selected from an alcohol or a carboxylic acid in an aqueous solution, by forming an ester comprising the following steps: a) an esterification reaction is carried out on a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion to form an ester in the oil phase, said reaction mixture being obtained according to the following steps: a1) a biphasic mixture is formed comprising at least a first water phase and an oil phase, by contacting an aqueous solution comprising said compound to be extracted, at least one reagent selected from a carboxylic acid or an alcohol, at least one enzymatic catalyst, at least one organic extraction solvent and solid particles; a2) said biphasic mixture obtained in step a1) is emulsified to form a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion;said reaction mixture comprising:;

[0060] -either droplets of said oil phase stabilized by said solid particles in said first water phase;

[0061] -either droplets of said first water phase stabilized by said solid particles in said oil phase; b) said oil phase containing the ester formed at the end of step a) is separated; c) the ester obtained at the end of step b) is hydrolyzed to reform said compound to be extracted; d) said compound to be extracted is recovered. to extract chosen an alcohol or an acid in a solution

[0062] The compound to be extracted, chosen from an alcohol or a carboxylic acid, can be obtained from biomass by fermentation and / or chemically using several processes.

[0063] Examples include the biorefinery processes aimed at producing alcohols and carboxylic acids, which are described by Laurent, P. et al., Biorefining, a promising alternative to petrochemistry, Biotechnology, Agronomy, Society and Environment, 2022, 15(4), 597-610; and by Takkellapati, S. et al., An overview of biorefinery-derived platform chemicals from a cellulose and hemicellulose biorefinery, Clean Technologies and Environmental Policy, 2018, 20(7), 1615-1630 or as described in patent FR2923840.

[0064] We can also mention the biomass transformation processes described by Straathof, AJJ et al., Transformation of biomass into commodity chemicals using enzymes or cells, Chem. Rev., 2014, 114, 1871-1908.

[0065] In particular, alcohols produced by fermentation processes (e.g., isopropanol and n-butanol) are among the most promising substitutes for petrochemical derivatives. ABE (Acetone-Butanol-Ethanol) fermentation, carried out by microorganisms of the genus Clostridium, is one of the oldest fermentations to have been industrialized and has since been extensively studied. More recently, IBE (Isopropanol-Butanol-Ethanol) fermentation, which produces a mixture of isopropanol, butanol, and ethanol and is also carried out by microorganisms of the genus Clostridium, has been the subject of relatively recent studies (Dos Santos Vieira et al., Acetone-free biobutanol production: Past and recent advances in the Isopropanol-Butanol-Ethanol (IBE) fermentation, Bioresource Technology, 2019, 287, 121425).Regarding the fermentation control method used in this type of process, batch production has been studied for ABE and IBE fermentations (see, for example, Jones DT, Woods DR, Acetone-Butanol Fermentation Revisited, Microbiol. Rew., 1986, 50(4), 484-524). Continuous processes have also been studied, initially with cells suspended in a homogeneous reactor. Improvements to continuous processes were then proposed by increasing the retention of microbial biomass in the bioreactor, notably by using cells immobilized on a substrate, and / or by using cell recycling with retention by means of filter membranes (Dos Santos Vieira et al., Acetone-free biobutanol production: Past and recent advances in the Isopropanol-Butanol-Ethanol (IBE) fermentation, Bioresource Technology, 2019, 287,121425).

[0066] Carboxylic acids can be produced through fermentation processes using different types of biomass.

[0067] One example is the conversion of carbohydrates (sugars, glucose, fructose, sucrose...) by fermentation which leads to acetic, succinic, lactic, itaconic, citric and gluconic acids as described by Lopez-Garzon CS (Lopez-Garzon, CS et al, Recovery of carboxylic acids produced by fermentation, Biotechnology Advances, 2014, 32, 873-904).

[0068] We can also cite Abrodo PA. et al., Fatty acid composition of cider obtained either by traditional or controlled fermentation, Food Chemistry, 2005, 92, 183-187; and Serra, S. et al., Microbial Fermentation of the Water-Soluble Fraction of Brewers' Spent Grain for the Production of High-Value Fatty Acids, Fermentation, 2023, 9, 1008.

[0069] Carboxylic acids can also be obtained chemically from biomass. These can be carbohydrates derived from lignocellulosic biomass, including cellulose, glucose, fructose, or glycerol. The various pathways for producing acids from biomass are well described by Deng W. et al., Production of organic acids from biomass resources, Current Opinion in Green and Sustainable Chemistry, 2016, 2, 54-58; and Li S. et al., Catalytic transformation of cellulose and its derivatives into functionalized organic acids, ChemSusChem, 2018, 11(13), 1995-2028; and Wang M. et al., Sustainable productions of organic acids and their derivatives from biomass via selective oxidation cleavage of CC bond, ACS Catalysis, 2018, 8(3), 2129-2165.

[0070] We can also cite in particular the oxidation of cellulose according to Wang F. et al., One-pot hydrothermal conversion of cellulose into organic acids with CuO as an oxidant, Industrial & Engineering Chemistry Research, 2014, 53(19), 7939-7946; and Jiang, Z. et al, Metal-oxide-catalyzed efficient conversion of cellulose to oxalic acid in alkaline solution under low oxygen pressure, ACS Sustainable Chemistry & Engineering, 2016, 4(1), 305-311.

[0071] We can cite the case of glucose oxidation, as for example according to Tang Z. et al., Transformation of cellulose and its derived carbohydrates into formic and lactic acids catalyzed by vanadyl cations, ChemSusChem, 2014, 7(6), 1557-1567.

[0072] We can also cite the case of the oxidation of glycerol, as described in patent application WO2014199256, which leads to oxalic acid, formic acid and alpha-hydroxy acids such as lactic acid, glycolic acid, glyceric acid and tartronic acid.

[0073] Carboxylic acids can also be obtained by hydrolysis or saponification of vegetable or animal oils following a process described by BANCOURT, H., Saponification, Tech. Ingé., 1991, J5810, 1-6 or SPITZ, L., Soap Technology for the 1990s, ed. SPITZ, L. AOCS Press, Champaign, Illinois, 1991, or SPITZ, L., Soaps and Detergents: A Theoretical and Practical Review, ed. SPITZ, L. AOCS Press, 1996, or WOOLLATT, E., The Manufacture of Soaps, Other Detergents and Glycerin, Ellis Horwood Limited, 1985.

[0074] Step a) Esterification reaction of a reaction mixture in the form of a Pickering emulsion.

[0075] The invention aims to extract a compound selected from an alcohol or a carboxylic acid contained in an aqueous solution, particularly a dilute one, by forming an ester through the addition to this aqueous solution of a reagent selected from a carboxylic acid or an alcohol and an enzymatic catalyst. Since the ester is insoluble in the aqueous solution, the invention utilizes the immiscibility between the aqueous solution containing the compound to be extracted and the ester produced to facilitate the extraction of the compound (in ester form) from the aqueous solution by preparing a biphasic mixture, particularly with the addition of an organic solvent, in the form of a Pickering emulsion.

[0076] Pickering emulsions are liquid-liquid (water-oil phase) dispersions stabilized by solid particles or aggregates of solid particles that accumulate at the interface between the two immiscible liquids and prevent coalescence. The direction of the emulsion (water-in-oil or oil-in-water) is determined by the preferential wettability of the solid particles toward one phase or the other. In fact, the liquid with the highest wetting ability toward the solid particles will constitute the continuous phase of the emulsion, and the one with the lowest wetting ability will constitute the dispersed phase. The direction of the emulsion will therefore depend on the nature of the solid particles, the organic extraction solvent, the water phase, the compound to be extracted, and the reagent.

[0077] Step a1) preparation of a two-phase mixture

[0078] The aqueous solution comprising the compound to be extracted chosen from the alcohol or the carboxylic acid, at least one reagent chosen from a carboxylic acid or an alcohol, at least one enzymatic catalyst, at least one organic extraction solvent and solid particles are brought into contact.

[0079] When all these species come into contact, a two-phase mixture is formed, consisting of a water phase and an oil phase. The different species distribute themselves between these two phases according to their affinity for one or the other. The exact composition of the different phases depends on the properties of each species present in the mixture.

[0080] Solution

[0081] The aqueous solution comprises at least the compound to be extracted, selected from the alcohol or carboxylic acid. According to one embodiment of the invention, the aqueous solution comprises the compound to be extracted in the form of micelles. This is then referred to as a micellar aqueous solution. This is the case, for example, with micellar solutions obtained by hydrolysis or saponification of vegetable oils. The fatty acid molecules thus obtained form micelles in solution in water. If the compound to be extracted is an alcohol, the concentration of the compound to be extracted in the aqueous solution is between 0.001 mol / L and 3 mol / L, preferably between 0.001 mol / L and 2 mol / L, preferably between 0.001 and 1 mol / L, and preferably between 0.001 and 0.4 mol / L.

[0082] If the compound to be extracted is a carboxylic acid, the concentration of the compound to be extracted in the aqueous solution is between 0.001 mol / L and 3 mol / L, preferably between 0.001 mol / L and 2 mol / L.

[0083] The said alcohol and the said carboxylic acid are described below.

[0084] Reactive:

[0085] The reagent is chosen from a carboxylic acid or an alcohol as described below. The reagent depends on the compound to be extracted from the aqueous solution.

[0086] The molar ratio between the reagent chosen from said carboxylic acid or said alcohol and the compound to be extracted from the aqueous solution chosen from said alcohol or said acid is greater than or equal to 1, preferably between 1 and 10 and most preferably between 1 and 5.

[0087] The choice of reagent added to the compound to be extracted will be made in such a way as to promote the separation of the alcohol and the carboxylic acid at the end of step d). A person skilled in the art will choose the physicochemical properties of the reagent to promote this separation. For example, the boiling point of the reagent will be chosen to be very different from that of the compound to be extracted to promote separation by distillation.

[0088] According to one variant of the invention, the reagent is chosen so as to remain predominantly in the oil phase at the end of step c) of ester hydrolysis, which promotes the separation of said alcohol and said carboxylic acid at the end of step d).

[0089] When the compound to be extracted from the aqueous solution is an alcohol, a carboxylic acid is added as a reagent to carry out the esterification reaction.

[0090] According to one embodiment of the invention, the reagent is already present in the aqueous solution. This can be the case, for example, when the reagent forms simultaneously with the compound to be extracted. This can occur in a fermentation process. Alcohol

[0091] Depending on the circumstances, the said alcohol is either the compound to be extracted from the aqueous solution or the reagent added to said aqueous solution to carry out the esterification reaction.

[0092] The alcohol according to the invention is any hydrocarbon compound comprising at least one alcohol functional group. The alcohol according to the invention preferably comprises a linear or non-linear, saturated or unsaturated, cyclic or non-cyclic, aromatic or non-aromatic carbon chain, comprising or not heteroatoms, preferably comprising 1 to 40 carbon atoms and possibly comprising other chemical functional groups. It may or may not be bio-based, derived from biomass such as cellulose, a sugar, a sterol, an alcohol formed by fermentation, or obtained by processing a bio-based product.

[0093] Without being exhaustive, the alcohol can be chosen from at least one of the following compounds: methanol, ethanol, 1-propanol, 2-propanol (or isopropanol), 1-butanol, 2-butanol, 2-methyl-1-propanol, tert-butanol, 3-hydroxybutanone (or acetoin), 1-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 1-heptanol (or n-heptanol), 2-octanol, 1-dodecanol (or lauryl alcohol), 1-tetradecanol (or myristyl alcohol), 1-hexadecanol (or cetyl alcohol), 1-octadecanol (or stearic alcohol), cis-9-octadecenol-1-ol (or octadecenol or oleyl alcohol), 1,2-ethanediol (or ethylene glycol), 1,2-propanediol (or propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, glycerol, trimethylolproprane, pentaerythritol, sorbitol, xylitol, glucose, fructose,5-Hydroxymethylfurfural (5-HMF), furfuryl alcohol, a phenol, a polyphenol.

[0094] Alcohols can be used alone or in mixtures.

[0095] According to a particular embodiment of the invention, said alcohol is of bio-based origin.

[0096] According to a particular embodiment of the invention, the alcohol is derived from an aqueous fermentation juice. In this case, the alcohols are used purified or unpurified. Thus, the fermentation alcohols are diluted in water with a concentration that varies according to their formation process.

[0097] Carboxylic acid

[0098] Depending on the circumstances, the said carboxylic acid is either the compound to be extracted from the aqueous solution or the reagent added to said aqueous solution to carry out the esterification reaction.

[0099] The carboxylic acid according to the invention is any hydrocarbon compound comprising at least one carboxylic acid functional group. The carboxylic acid according to the invention preferably comprises a linear or non-linear, saturated or unsaturated, cyclic or non-cyclic, aromatic or non-aromatic carbon chain, comprising or not heteroatoms, preferably comprising 1 to 40 carbon atoms and possibly comprising other chemical functional groups. It may or may not be bio-based, derived from biomass, from the transformation of a vegetable or animal oil, from fermentation, particularly of sugars, obtained by pressing biomass, or obtained by transforming a bio-based product, for example, by the oxidation of an alcohol. It may be in its acidic (or protonated) form or as a salt, for example, an alkali or alkaline earth metal salt or an ammonium salt. Without being exhaustive,The carboxylic acid may be chosen from at least one of the following compounds: formic acid, acetic acid, propanoic acid (or propionic acid), butanoic acid (or butyric acid), isobutyric acid, pentanoic acid (or valeric acid), isovaleric acid, hexanoic acid (or caproic acid), n-heptanoic acid, myristic acid, levulinic acid, behenic acid, gadoleic acid, succinic acid, adipic acid, glutaric acid, citric acid, aconitic acid, itaconic acid, palmitic acid, oleic acid, fumaric acid, glycolic acid, glyceric acid, tartronic acid, stearic acid, palmitoleic acid, linoleic acid, acid alinolenic acid, erucic acid, petroselinic acid, gondoic acid, sterculic acid, dihydrosterculic acid, calendic acid, α-eleostearic acid, punicic acid, eicosapentaenoic acid, docosahexaenoic acid, 10-undecenoic acid,ricinoleic acid, malic acid, gluconic acid, 3-hydroxypropionic acid, glyceric acid, ascorbic acid, glucosaminic acid, pyruvic acid, lactic acid, glycolic acid, glyceric acid, tartronic acid, malic acid, citric acid, 3-hydroxypropionic acid, 3-hydroxybutyric acid, 5-hydroxypentanoic acid, glyceric acid, ascorbic acid, acrylic acid, methacrylic acid, 2,5-furandicarboxylic acid, 2-keto-L-gulonic acid, 2-hydroxyisobutyric acid, benzoic acid, and glucosaminic acid.

[0100] According to one embodiment of the invention, the molecule bears both a carboxylic acid and an alcohol functional group and can be selected from lactic acid, glycolic acid, glyceric acid, tartronic acid, malic acid, citric acid, gluconic acid, 3-hydroxypropionic acid, 3-hydroxybutyric acid, 5-hydroxypentanoic acid, glyceric acid, ascorbic acid, 2-keto-L-gulonic acid, 2-hydroxyisobutyric acid, and glucosaminic acid. In this case, the molecule can be said compound to be extracted and / or said reagent.

[0101] Carboxylic acids can be used alone or in mixtures. According to a particular embodiment of the invention, said carboxylic acid is of bio-based origin.

[0102] Solid particles

[0103] Solid particles can be hydrophilic, hydrophobic, or amphiphilic. Preferably, solid particles are amphiphilic, meaning they have at least one hydrophilic and one hydrophobic function on their surface.

[0104] They can be modified to change their surface properties (in particular to modify their wettability). They can be of a single type, or be used in a mixture of several types of solid particles (in terms of size, shape and wettability).

[0105] Optionally, at least one surfactant can be added to the solid particles. This surfactant (or each of them if a mixture of surfactants is used) can be anionic, cationic, non-ionic, or amphoteric.

[0106] According to the invention, the solid particles can thus be chosen from: silica particles, preferably at least partially functionalized by hydrophobic hydrocarbon groups, clay particles, preferably at least partially modified with organic or amphiphilic molecules, magnetic particles, in particular FesCl, carbon nanotubes, graphene oxide particles, synthetic polymer particles, such as polyethylene glycol (PEG), polystyrene (PS), polylactic acid (PLA), polycaprolactone (PCL), or latex particles, particles of material of natural origin preferably chosen from hydroxyapatite, chitosan, cyclodextrin, dextran, particles in the form of cellulose nanocrystals or nanofibers, particles of biological material, in particular food grade, preferably chosen from starch, zein, soy proteins, bacteria and yeasts.

[0107] The size can vary enormously, from a few nanometers to a few tens of microns. The size obviously depends on the morphology of the solid particles involved. It is generally determined by scanning and transmission electron microscopy. It is easy to define for spherical solid particles (diameter), and more difficult for solid particles whose shape deviates from sphericity (plates, rods, ellipsoids, needles, etc.). In these cases, we generally distinguish between two characteristic sizes: the smallest and the longest. Another difficulty is related to the spontaneous formation of aggregates between the elementary solid particles. We then distinguish between the size of the elementary solid particles and the size of the aggregates. For example, the commercial silica Aerosil R972 is a mixture of elementary solid particles between 5 nm and 50 nm with aggregates of average size on the order of 250 nm.

[0108] In a particular embodiment of the invention, the solid particles are nanometric, with an average size between 1 nm and 500 nm, preferably between 5 nm and 300 nm.

[0109] The content of solid particles relative to the weight of the two-phase reaction mixture obtained at the end of step a) is between 0.1% by weight and 10% by weight, in particular between 1% by weight and 5% by weight, and preferably between 0.5% by weight and 2% by weight of solid particles relative to the weight of said two-phase reaction mixture obtained at the end of step a).

[0110] The ratio between the largest dimension of the droplets and the largest dimension of the solid particles is preferably at least 100. The largest dimension is understood to be the diameter when the particles are approximately spherical. They are located at the interface of the water / oil emulsion droplets.

[0111] The enzymatic catalyst is chosen from among lipases of animal, microbial or plant origin.

[0112] Different types of lipases can be used according to the invention. Without this being exhaustive, we will cite the lipases produced by Humicola lanuginosa, Rhizopus delemar, Geotrichum candidum, Rhizomucor miehei (Mucor miehei), Pseudomonas glumae, Candida rugosa (C. cylindraceae), Candida antarctica, Chromobacterium viscosum, Rhizopus arrhizus, Yarrowia lipolytica, Pseudomonas, Hansenula, Bacillus, Aspergillus, wheat germ, horse or bovine pancreas.

[0113] Preferably, the enzymatic catalyst is Candida antarctica lipase B, Candida rugosa lipase, or Rhizomucor miehei lipase. Preferably, Candida antarctica lipase B.

[0114] Enzymes can be commercially available or manufactured using techniques known to those skilled in the art. They are available either as a dilute solution or immobilized by grafting, adsorption, or trapping onto solid particles to facilitate their recovery. Those skilled in the art will adjust the quantity of enzyme according to its nature, reactivity, and dilution if the enzyme is in solution, or the amount of immobilized enzyme if it is supported on solid particles.

[0115] According to one embodiment of the invention, the enzyme is immobilized on the solid particles. According to this embodiment of the invention, the enzyme can be easily reused after filtration (Yin, Chengmei, et al. "Pickering emulsion biocatalysis: Bridging interfacial design with enzymatic reactions." Biotechnology Advances (2024)).

[0116] Enzyme immobilization can be achieved by any method known to those skilled in the art. Classically, enzyme immobilization can be physical (adsorption, trapping) or chemical (chemical grafting).

[0117] In the so-called physical method, there can be different types of interaction between the enzyme and the solid particle: hydrogen bonds, electrostatic forces, or hydrophobic interactions. The enzyme is immobilized simply by contact with the solid particle. Preferably, the solid particle is rich in hydrophobic groups to immobilize the enzyme. In the so-called chemical method, a chemical bond is formed between the enzyme and the solid particle. To achieve this, the surface of the solid particles can be modified by bifunctional agents that bridge the enzyme and the solid particle by reacting with the enzyme on one side and with the solid particle on the other. Bifunctional agents can be any compound well known to those skilled in the art, such as epichlorohydrin, glutaraldehyde, glyoxal, paraformaldehyde, carbodiimide, or ethylenediamine.Bifunctional agents can react with the chemical functions of an enzyme, such as an alcohol, thiol, or amine group. The most common method is to react with an amine group of the enzyme. In this case, it is common to also introduce an amine group onto the surface of the solid particle and to use glutaraldehyde, which will bridge an amine group of the enzyme with an amine group of the solid particle.

[0118] According to a particular embodiment of the invention, the solid particles on which the enzyme is immobilized are amphiphilic solid particles, that is to say, comprising on their surface at least one hydrophilic function and at least one hydrophobic function.

[0119] Organic extraction solvent

[0120] The organic extraction solvent constitutes at least one of the components of the oil phase of the emulsion. It allows the extraction of the ester produced by the esterification reaction.

[0121] The organic extraction solvent can be any liquid immiscible with the aqueous solution. A person skilled in the art would preferentially choose an organic solvent with a high partition coefficient for the ester formed and that is not toxic to the enzyme.

[0122] In one or more particular embodiments of the invention, the organic solvent can be chosen from vegetable or animal oils, fatty acid esters of natural or non-natural origin, ethers, alkyl glycerol ethers, glycol ethers and hydrocarbons or mixtures of hydrocarbons, branched or unbranched, aromatic or non-aromatic, which may contain other compounds (for example in the case of petroleum cuts or any mixture of hydrocarbons from petroleum refining).

[0123] Without being exhaustive, the organic solvent may be chosen from at least one of the following compounds: hexane, heptane, octane, decane, dodecane, hexadecane, cyclohexane, methylcyclohexane, toluene, paraxylene, metaxylene, orthoxylene, ethylbenzene, limonene, cyclopentyl methyl ether, diphenyl ether, methyl soyate, methyl or ethyl esters of rapeseed oil, palm oil, jatropha oil, olive oil, sesame oil, peanut oil, corn oil, poppy seed oil, safflower oil, soybean oil, sunflower seed oil, used oils or animal fats.

[0124] In one or more particular embodiments of the invention, the organic solvent may be the same compound as the product of the esterification reaction according to the invention.

[0125] In one or more particular embodiments of the invention, the solvent is the reactant if it is liquid under the conditions of implementation of the invention and is not miscible with the aqueous solution.

[0126] In one or more particular embodiments of the invention, the organic solvent has a boiling point very different from those of the ester formed, of said alcohol and of said carboxylic acid in order to promote its separation from the other species by distillation.

[0127] THE

[0128] According to step a1), the aqueous solution comprising the compound to be extracted selected from the alcohol or carboxylic acid, the reagent selected from a carboxylic acid or an alcohol, the enzymatic catalyst, the organic extraction solvent and solid particles are brought into contact.

[0129] When all these species are in contact, a biphasic mixture is formed, comprising at least a water phase and an oil phase. The different species distribute themselves between these two phases according to their affinity for one or the other phase.

[0130] The exact composition of the different phases depends on the properties of each species present in the mixture and evolves during the process.

[0131] After all the components have been brought into contact, the first water phase comprises at least water and at least a fraction of the compound to be extracted, chosen from the aforementioned alcohol or carboxylic acid. Depending on the affinity of the compound to be extracted initially in the aqueous solution for the oil phase, a portion may dissolve in the oil phase upon contact. The first water phase comprises between 40% and 100% by mass of the compound to be extracted, and the oil phase comprises between 0% and 60% by mass of the compound to be extracted. It is understood that the mass fraction of the compound to be extracted dissolved in the water phase and the mass fraction of the compound to be extracted dissolved in the oil phase represent 100% of the mass of the compound to be extracted.

[0132] Preferably, the compound to be extracted has a greater affinity for the first water phase. The first water phase then comprises a mass fraction greater than or equal to 50% of the compound to be extracted. The oil phase then comprises a mass fraction less than 50% of the compound to be extracted.

[0133] Depending on the reagent's affinity for the water phase, the first water phase also comprises a mass fraction of said reagent ranging from 0% to 100% relative to the total mass of the reagent chosen from said carboxylic acid or said alcohol, and the oil phase comprises between 0% and 100% of the reagent relative to its total mass. It is understood that the mass fraction of the reagent solubilized in the water phase and the mass fraction of the reagent solubilized in the oil phase each represent 100% of the total mass of the reagent.

[0134] According to one embodiment of the invention, the reagent exhibits a greater affinity for the oil phase. The first water phase then comprises a mass fraction of less than 50% of the reagent, and the oil phase comprises a mass fraction of 50% or more of the reagent.

[0135] The oil phase also includes the organic extraction solvent.

[0136] During the esterification reaction, the composition of the oil phase changes; specifically, the ester produced by the esterification reaction transitions into the oil phase. Additionally, water is produced by the esterification reaction and adds to the existing water phase.

[0137] At the end of the esterification step, the water phase is depleted of the compound to be extracted, and the oil phase is enriched in ester. The solid particles are at the interface between the two phases.

[0138] If the enzymatic catalyst is not immobilized on the solid particles, the water phase also contains the enzymatic catalyst.

[0139] The volume fraction of the first water phase in the two-phase reaction mixture prepared in step a1) is between 10% by volume and 90% by volume, preferably between 40% by volume and 60% by volume of the water phase relative to the total volume of said reaction mixture. This volume fraction changes during the process.

[0140] The pH of the first water phase depends on the nature of the enzymatic catalyst, the solid particles, and the nature of the alcohol, carboxylic acid, and extraction solvent. Those skilled in the art can adjust the pH by acidifying or alkalizing the medium to ensure optimal enzyme function. Preferably, the pH is less than 7 or greater than 8, with the pH preferably being less than 7.

[0141] The process according to the invention can be implemented in several embodiments depending on the method of obtaining the compound to be extracted and the hydrophilic or hydrophobic nature of said alcohol and said carboxylic acid.

[0142] According to a first embodiment of the invention, solid particles, an enzymatic catalyst, and an oil phase comprising an organic extraction solvent are brought into contact with a first water phase, comprising at least water and a fraction of an alcohol to be extracted from said aqueous solution. A carboxylic acid (reagent) having a greater affinity for the first water phase than for the oil phase is added. In this case, the mass fraction of the carboxylic acid (reagent) in the water phase is greater than or equal to 50% relative to the total mass of carboxylic acid. The mass fraction of the carboxylic acid in the oil phase is less than 50% relative to the total mass of carboxylic acid.

[0143] According to a second embodiment of the invention, solid particles, an enzymatic catalyst, and an oil phase comprising an organic extraction solvent are brought into contact with a first water phase, comprising at least water and a fraction of a carboxylic acid to be extracted from said aqueous solution. An alcohol (reagent) having a greater affinity for the first water phase than for the oil phase is added.

[0144] In this case, the mass fraction of the alcohol (reactant) in the water phase is greater than or equal to 50% relative to the total mass of alcohol. The mass fraction of the alcohol in the oil phase is less than 50% relative to the total mass of alcohol. According to a third embodiment of the invention, solid particles, an enzymatic catalyst, and an oil phase comprising an organic extraction solvent are brought into contact with a first water phase, comprising at least water and a fraction of an alcohol to be extracted from said aqueous solution. A carboxylic acid (reactant) having a greater affinity for the oil phase than for the water phase is added. In this case, the mass fraction of the carboxylic acid (reactant) in the oil phase is greater than or equal to 50% relative to the total mass of carboxylic acid. The mass fraction of the carboxylic acid in the water phase is less than 50% relative to the total mass of carboxylic acid.In this embodiment of the invention, the carboxylic acid is preferably dissolved in the oil phase before the two phases are brought into contact.

[0145] According to a fourth embodiment of the invention, solid particles, an enzymatic catalyst, and an oil phase comprising an organic extraction solvent are brought into contact with a first water phase, comprising at least water and a fraction of a carboxylic acid to be extracted from said aqueous solution. An alcohol (reagent) having a greater affinity for the oil phase than for the water phase is added. In this case, the mass fraction of the alcohol (reagent) in the oil phase is greater than or equal to 50% of the total mass of alcohol. The mass fraction of the alcohol in the water phase is less than 50% of the total mass of alcohol. In this embodiment of the invention, the alcohol is preferably dissolved in the oil phase before the two phases are brought into contact, forming an emulsion of

[0146] The biphasic mixture obtained in step a1) is emulsified to form a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion; said reaction mixture comprising

[0147] - either oil phase droplets stabilized by said solid particles in said first water phase;

[0148] - either water phase droplets stabilized by said solid particles in said oil phase.

[0149] Emulsification transforms the biphasic mixture obtained in step a1) into droplets dispersed in the continuous phase, forming a Pickering emulsion. The largest droplet size is between 1 pm and 1000 pm, preferably between 1 pm and 140 pm, preferably between 2 pm and 100 pm, and particularly between 10 pm and 50 pm. Note that the droplet size is measured by optical microscopy (specifically using an Olympus BX51 with AnalySIS software for image analysis).

[0150] The emulsification of a two-phase medium is achieved using any type of system that provides energy to generate the emulsification known to those skilled in the art. While not exhaustive, examples include rotor-stator type tools, propeller agitators, static mixers, colloid mills, membrane systems, ultrasonic stirring, and microfluidic systems. The principle of these mixers is described, for example, in the Techniques de l'ingénieur (Engineering Techniques) publication J2153V1: Emulsification Processes - Equipment Techniques, by M. Poux and JP Canselier, June 10, 2004. A microfluidic system is described, for example, in the Techniques de l'ingénieur publication J8010V1: Microfluidics and Formulation - Emulsions and Complex Colloidal Systems, by V. Nardello-Rataj and JF Ontiveros, May 10, 2019.

[0151] In a particular embodiment of the invention, emulsification is carried out using a rotor-stator system of the type of the system marketed under the name Ultra-Turrax.

[0152] The direction of the emulsion depends on the nature of the solid particles, the solvent, the water phase, and said alcohol and said carboxylic acid.

[0153] In a particular embodiment of the invention, the Pickering emulsion is a water-in-oil emulsion. The droplets, which comprise a first water phase including at least water and at least a fraction of the compound to be extracted selected from said alcohol or said carboxylic acid, are stabilized by solid particles in the oil phase including at least the extraction solvent. The reagent partitions between the oil phase and the first water phase according to its affinity for these phases. The enzymatic catalyst is either in the first water phase or immobilized on the solid particles, depending on its nature. During the reaction, the oil phase becomes enriched in ester.

[0154] In another particular embodiment of the invention, the Pickering emulsion is an oil-in-water emulsion. The droplets, which comprise the oil phase including at least the extraction solvent, are stabilized by solid particles in the first water phase, which includes at least water and at least a fraction of the compound to be extracted, selected from said alcohol or said carboxylic acid. The reagent partitions between the oil phase and the first water phase according to its affinity for these phases. The enzymatic catalyst is either in the water phase or immobilized on the solid particles, depending on its nature. During the reaction, the oil phase becomes enriched in ester.

[0155] Esterification reaction: The esterification reaction in step a) is carried out at a temperature between 10°C and 90°C to form the ester. Preferably, the temperature is between 20°C and 60°C, most preferably between 25°C and 50°C, and most preferably between 35°C and 45°C.

[0156] The pressure is advantageously between atmospheric pressure and 0.3 MPa absolute.

[0157] The esterification reaction is written as:

[0158] R1-OH+ R2-COOH R2-COO-R1 + H2O

[0159] The reaction is balanced and releases water. The ester, which is sparingly soluble in water, is extracted into the oil phase, while the water formed is extracted into the water phase. The ester is sparingly soluble in the water phase; however, the water phase may contain traces of ester. Conversely, the water formed is sparingly soluble in the oil phase; however, the oil phase may contain traces of water.

[0160] The elimination of one of the reaction products, by transfer from one phase to another, leads to shifting the reaction towards the formation of ester.

[0161] At the end of step a) of esterification, the said first water phase has become depleted in compound to be extracted and the oil phase has become enriched in ester.

[0162] A person skilled in the art will be able to use different implementations of this reaction. The reaction can be carried out with or without agitation.

[0163] In a particular embodiment of the invention, the reaction is conducted in a closed system (or batch).

[0164] In another particular embodiment of the invention, the reaction is conducted in an open (or continuous) system with continuous withdrawal of a fraction of the oil phase from the Pickering water-in-oil emulsion. The withdrawn fraction of the oil phase is sent to step c) of ester hydrolysis.

[0165] According to another particular embodiment of the invention, the oil phase is drawn off and sent to an ester separation step (optional step b'), and the oil phase, now depleted in ester, is then returned to step a). The ester is sent to ester hydrolysis step c). According to a particular embodiment of the invention, the oil phase is drawn off and sent to an optional separation step of the compound to be extracted contained in the oil phase (step d'), and the oil phase, now depleted in the compound to be extracted, is then returned to step a).

[0166] In another particular embodiment of the invention, the reaction is carried out in an open (or continuous) system with additions of aqueous solution containing the compound to be extracted, said alcohol or said carboxylic acid, to the oil-in-water Pickering emulsion. According to this embodiment of the invention, a portion of the first water phase can be withdrawn to control the ratio between the first water phase and the oil phase. According to this embodiment of the invention, an enzymatic catalyst can be added. This embodiment of the invention can be implemented in combination with the process for producing said compound to be extracted, selected from said alcohol or said carboxylic acid in aqueous solution (step a'), with or without withdrawal and reinjection of the water phase depleted of the compound to be extracted in step a') of production of said compound to be extracted.This embodiment of the invention is particularly suited to the use of an enzymatic catalyst immobilized on solid particles. It is understood that the term "in combination" means that steps a'), a), are carried out consecutively, or simultaneously, or sequentially.

[0167] In one or more particular embodiments of the invention, additions of reagent chosen from said alcohol or said carboxylic acid can be made, continuously or not, preferably via the continuous phase.

[0168] The reaction time in a closed (or batch) system or the liquid flow rates in an open (or continuous) system depend on the operating conditions and the enzyme's reactivity. These parameters will be adjusted by a person skilled in the art to obtain the desired ester yield within a desired timeframe.

[0169] In one or more particular embodiments of the invention, the optional step a') of producing said alcohol to be extracted or said carboxylic acid to be extracted, may be carried out in combination with step a).

[0170] This implementation has the advantage of promoting the production of said alcohol or carboxylic acid by extracting it as it is produced. This is particularly true when said alcohol or carboxylic acid is produced by fermentation or by an equilibrium reaction such as the hydrolysis of an ester, for example, the esters contained in vegetable and animal oils. Indeed, it is known to those skilled in the art that fermentation slows down as the concentration of fermentation products in the medium increases in the case of alcohol production (Lim, J. et al., Mathematical Modeling of Acetone-Butanol-Ethanol Fermentation with Simultaneous Utilization of Glucose and Xylose by Recombinant Clostridium acetobutylicum, Energy Fuels, 2019, 33, 8620-8631) and in the case of carboxylic acid production (Joglekar, HG et al.(Comparative assessment of downstream processing options for lactic acid, Separation and Purification Technology, 2006, 52(1), 1-17). Therefore, their extraction as they are produced prevents slowing down fermentation. Similarly, it is known to those skilled in the art that extracting a product from an equilibrium reaction, such as the hydrolysis of an ester, shifts the equilibrium towards the formation of that product. Combining step a') with steps a) and b) can be carried out in various ways, such as those described in US patents 2014 / 0178529 A1, US 9517985 B2, US 2010 / 0143993 A1, and US 8614077 B2, as well as by Woodley JM et al. Future directions for in-situ product removal (ISPR), J Chem Technol Biotechnol., 2008, 83,121-123. water

[0171] The oil phase containing the ester formed at the end of step a) is separated from the first water phase.

[0172] To achieve this, the Pickering emulsion is broken to separate the two liquid phases. Pickering emulsions can be broken using various mechanical or physicochemical methods. The principles used to destabilize these systems are well described in the journal article by C.P. Whitby and E.J. Wanless (2016), “Controlling Pickering Emulsion Destabilization: A Route to Fabricating New Materials by Phase Inversion,” Materials, 9, 626; doi:10.3390 / ma9080626. It is possible to break the emulsion by applying an external force that causes the interfacial film to rupture and the droplets to coalesce, such as shear, compression, or centrifugation. Another method involves adding a chemical that, through transfer from the continuous phase to the dispersed phase, destabilizes the interfacial film formed by the solid particles and causes the droplets to coalesce, thus breaking the emulsion.In the specific case of magnetic particles, a magnetic field can be used to destabilize the emulsion. It is also possible to break the emulsion by modifying the wettability of the solid particles to detach them from the interface and carry them into the continuous or dispersed phase. This can be done by adding a surfactant, which will adsorb onto the solid particles and change their wettability, or by modifying the pH in the case of pH-sensitive solid particles (such as proteins), or by modifying the temperature in the case of heat-sensitive solid particles. All the different mechanisms described above can also be combined (addition of a surfactant and shearing, modification of pH and centrifugation, these two examples being non-limiting).

[0173] In a particular embodiment of the invention, solid particles are removed from the reaction mixture using any solid / liquid separation technique such as filtration, centrifugation, or a combination of separation methods.

[0174] Once the emulsion has broken down, the two phases can be collected separately, for example in a decanter. At the end of step b), the oil phase enriched with ester is collected.

[0175] According to one embodiment of the invention, the oil phase is washed with salt water to extract any compounds from the oil phase other than the compound to be extracted according to the invention and the ester. The nature and salt concentration of the salt water will be adjusted by those skilled in the art to optimize the efficiency and selectivity of this washing. For example, saturated alkali or alkaline earth metal chlorides may be chosen.

[0176] According to one embodiment of the invention, any compounds in the oil phase other than the compound to be extracted according to the invention and the ester are adsorbed onto a solid by contacting the oil phase with that solid. Those skilled in the art will choose the adsorbent solid based on the nature of the compounds to be extracted.

[0177] According to one variant of the invention, the first water phase is returned to step a).

[0178] According to one variant of the invention, the first water phase is returned to step a').

[0179] Step b') (Optional) Separation of the ester from the oil phase

[0180] Optionally, the ester is separated from the oil phase. The separation of the ester from the oil phase can be carried out by any methods known to those skilled in the art, preferably by one or more methods chosen from distillation, vacuum distillation, steam distillation, pervaporation, membrane separation and precipitation.

[0181] According to a particular embodiment of the invention, several esters have been formed by the process according to the invention and are separated before the hydrolysis step of ester c).

[0182] The ester-depleted oil phase can be sent to step a) or step d).

[0183] The ester obtained at the end of step b) or optionally b') is hydrolyzed to reform said compound to be extracted chosen from said alcohol or said carboxylic acid.

[0184] The hydrolysis of an ester to form a carboxylic acid and an alcohol is a reaction well known to those skilled in the art. This reaction is very well described in the article by JP Guthrie (Hydrolysis of esters of oxy acids: PKa values ​​for strong acids; Brønsted relationship for attack of water at methyl; Free energies of hydrolysis of esters of oxy acids; And a linear relationship between free energy of hydrolysis and pKa holding over a range of 20 pK units, February 2011 Canadian Journal of Chemistry 56(17):2342-2354 DOI: 10.1139 / v78-385).

[0185] The hydrolysis reaction is written as:

[0186] R2-COO-R1 + H2O R1-OH+ R2-COOH

[0187] This is the reverse reaction to the esterification reaction, therefore, by this reverse reaction we obtain the compound to be extracted chosen from said alcohol or said carboxylic acid on the one hand and the reagent added in step a1) chosen from said carboxylic acid or said alcohol to carry out the esterification reaction on the other hand.

[0188] The ester hydrolysis step according to the invention uses a quantity of water at least equal to the number of moles of ester to be hydrolyzed and preferably a catalyst. According to one embodiment of the invention, the ester hydrolysis step uses a catalyst.

[0189] According to one embodiment of the invention, the ester hydrolysis catalyst is chosen from an acid, a base and an enzyme.

[0190] According to one embodiment of the invention, the catalyst is a mineral acid, preferably chosen from sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid, preferably the acid is sulfuric acid.

[0191] According to another embodiment of the invention, the catalyst is an organic acid or a salt of an organic acid, preferably chosen from metallic acetates, for example of manganese, tin, iron or calcium, p-toluenesulfonic acid, glacial acetic acid, formic acid, propionic acid, lactic acid, calcium lactate, stearic acid and oleic acid...

[0192] According to another embodiment of the invention, the catalyst is said carboxylic acid. According to another embodiment of the invention, the catalyst is an acidic solid, preferably chosen from supported HPAs (heteropolyanions), supported phosphoric acid (SPA), solids grafted with sulfones, zeolites, and acid resins.

[0193] According to another embodiment of the invention, the catalyst is a mineral or organic base, preferably chosen from a hydroxide or carbonate or hydrogen carbonate (or bicarbonate) of an alkali or alkaline earth metal or ammonium or an amine, a sodium alkoxide, preferably the catalyst is chosen from soda, potash, ammonium hydroxide, sodium methanoate, diethanolamine and triethanolamine.

[0194] According to another embodiment of the invention the catalyst is a basic solid preferably chosen from a magnesium oxide (MgO), a zinc oxide (ZnO) used alone or in mixture with their aluminum spinal.

[0195] According to another embodiment of the invention, the catalyst is a lipase or esterase-type enzyme of animal, microbial, or plant origin. Various types of enzymes can be used according to the invention. Without being exhaustive, examples include lipases produced by Humicola lanuginosa, Rhizopus delemar, Geotrichum candidum, Rhizomucor miehei, Pseudomonas glumae, Candida rugosa, Candida antarctica, Chromobacterium viscosum, Rhizopus arrhizus, Yarrowia lipolytica, Pseudomonas, Hansenula, Bacillus, Aspergillus, wheat germ, and horse or bovine pancreas. Preferably, the enzymatic catalyst is lipase B from Candida antarctica, lipase from Candida rugosa, or lipase from Rhizomucor miehei. Preferably, Candida antarctica lipase B. Hydrolysis can be carried out according to the methods described in patent EP0714983.

[0196] According to one embodiment of the invention, the water is introduced in liquid form.

[0197] According to another embodiment of the invention, the water is introduced in the form of water vapor.

[0198] According to one embodiment of the invention, the hydrolysis of an ester according to the invention uses a number of moles of hydroxide ions at least equal to the number of moles of ester to be hydrolyzed. The hydroxide ions can be supplied in the form of alkali or alkaline earth metal salts or ammonium salts, either solid or in aqueous solution. The temperature for carrying out the ester hydrolysis will be chosen according to the nature of the catalyst. If the catalyst is an enzyme, the temperature will preferably be below 100°C, preferably below 90°C. If the catalyst is not an enzyme, the temperature will preferably be above 50°C, preferably above 100°C. This reaction is well known to those skilled in the art. Reference should be made to the thesis of G.Poulenat, 2003 (INPT, Studies of transfer and exchange reactions in stirred batch reactor and in thermal induction heated hydrothermal reactor, case studies of the saponification reaction of high oleic sunflower oil and of the double decomposition reaction for obtaining lipophilic carboxylic acid salts.) or to the article by M. Harriet Norris and J. William McBain (A study of the rate of saponification of oils and fats by aqueous alkali under various conditions, Journal of the Chemical Society, Transactions, 1922, 121, 1362. doi .org / 10.1039 / CT9222101362).

[0199] A person skilled in the art will be able to adjust the system pressure if necessary so that the phases present are liquid.

[0200] According to one embodiment of the invention, the mixture is cooled by any method known to a person skilled in the art after the hydrolysis of the ester.

[0201] The addition of water and the reformation of the compound to be extracted, chosen from the alcohol or carboxylic acid and the reagent, forms a second water phase. The volume of this second water phase depends on the amount of water added to carry out the hydrolysis, the species present, and their affinity for each phase. said compound to be extracted

[0202] The compound to be extracted is recovered in the oil phase and / or in the second water phase, depending on its affinity for one or the other phase. The recovery process depends on the composition of the different phases.

[0203] According to one embodiment of the invention, step d) is carried out simultaneously with step c) so as to promote the hydrolysis reaction of the ester by simultaneous recovery of the compound to be extracted leading to the shift of the reaction equilibrium in the direction of hydrolysis of the ester and reformation of the compound to be extracted.

[0204] According to one embodiment of the invention, mineral salts are added to the aqueous phase to achieve a salting-out effect, a phenomenon known to those skilled in the art, which reduces the solubility of a solute in a solution. Increasing the salinity of the second water phase can facilitate the passage of certain compounds into the oil phase by lowering their solubility in the water phase. For example, alkali or alkaline earth metal chlorides could be used. In another embodiment of the invention, when the ester is separated from the oil phase in step b') before step c) of ester hydrolysis, a second water phase is formed containing the compound to be extracted and potentially containing reagent. Depending on its solubility in water, a fraction of the reagent may form a liquid phase that is immiscible with the second water phase.If the ester hydrolysis reaction was incomplete, the unhydrolyzed ester constitutes a liquid phase immiscible with the second water phase, which may contain a fraction of the reagent and / or a fraction of the compound to be extracted. If a liquid phase immiscible with the second water phase is formed, it is treated as the oil phase according to the invention.

[0205] In a first embodiment of the invention, the phases are not separated and the compounds are separated by methods known to those skilled in the art, preferably by one or more methods chosen from distillation, vacuum distillation, steam distillation, pervaporation, membrane separation, adsorption onto a solid and precipitation. The compound to be extracted is then recovered.

[0206] In a second embodiment of the invention, the oil phase and the second water phase are collected separately in a decanter. Once separated, the oil phase and the second water phase can be treated separately according to the optional steps d') and / or d”) to recover the compound to be extracted at the end of step d') and / or d”) according to its affinity for one or the other of the phases.

[0207] Step d') (optional) Treatment of the oil phase at the end of step c)

[0208] The oil phase obtained at the end of step c) may contain unconverted ester, said compound to be extracted solubilized in the oil phase, said reagent solubilized in the oil phase, organic solvent and other compounds.

[0209] In a particular embodiment of the invention, the oil phase is returned directly to step a) without a prior treatment or purification step.

[0210] In one or more particular embodiments of the invention, the oil phase contains a fraction of the compound to be extracted that is to be recovered. The selected compound to be extracted is then separated from the alcohol or carboxylic acid contained in the oil phase, and the oil phase, depleted in the selected alcohol or carboxylic acid, is returned to step a). The separation of the compound to be extracted from the oil phase can be carried out by any methods known to those skilled in the art, preferably by one or more methods chosen from distillation, vacuum distillation, steam distillation, pervaporation, membrane separation, and precipitation. The extracted compound is then recovered at the end of step d').

[0211] In one or more particular embodiments of the invention, the different compounds of the oil phase are separated by methods known to those skilled in the art, preferably by one or more methods selected from distillation, vacuum distillation, steam distillation, pervaporation, membrane separation, adsorption onto a solid, and precipitation. (Optional) Treatment of the second water phase after the

[0212] The second water phase from step c) comprises at least a fraction of the compound to be extracted. It may also contain a fraction of the reagent.

[0213] In a first embodiment of the invention, the second water phase, containing at least the compound to be extracted, is not treated or purified. According to a variant of the invention, the second water phase can be referred back to step a). This is particularly advantageous when the compound to be extracted is predominantly contained in the oil phase.

[0214] In a second particular embodiment, the compounds of the second water phase, comprising at least the compound to be extracted according to the invention, are separated by methods known to those skilled in the art, preferably by one or more methods chosen from distillation, vacuum distillation, steam distillation, pervaporation, membrane separation, adsorption onto a solid, and precipitation. The compound to be extracted is then recovered at the end of step d).

[0215] According to one variant of the invention, said reagent possibly recovered at this stage is returned to step a).

[0216] At the end of step d”) the second water phase can be returned to step a).

[0217] Examples:

[0218] Examples 1 through 15 describe the extraction of an alcohol as an ester formed by the reaction between the alcohol to be extracted and a carboxylic acid added to the reaction medium. The alcohol is present in a water phase and is extracted as an ester into an oil phase. In examples 1 through 11, the carboxylic acid is added to the water phase, and the esterification reaction is carried out under different conditions. In examples 12 through 15, the carboxylic acid is added to the oil phase, and the esterification reaction is carried out under different conditions. In all examples, the amount of alcohol extracted into the oil phase as an ester is determined by analyzing a sample of the oil phase using gas chromatography on an Agilent 7890 instrument equipped with an HP-1 ms column and hexadecane as an internal standard.The extraction rate of 1-butanol as an ester after one hour and six hours is given in Table 1. It is calculated by dividing the amount of 1-butanol extracted from the oil phase as an ester by the initial amount of 1-butanol. Analysis of the oil phase also allows for the quantification of 1-butanol extracted from the oil phase without being converted to an ester (due to solubility). The total extraction rate of 1-butanol is obtained by summing the two extraction rates.

[0219] Example 1 (not in accordance with the invention): biphasic mixture without biocatalyst (no Pickering emulsion)

[0220] 600 mL of water containing 0.1 mol / L of 1-butanol and 0.1 mol / L of butyric acid, and 600 mL of n-dodecane, are stirred at 40°C at 500 rpm for 6 hours using a magnetic stir bar. The initial pH of the water phase is 2.7. The 1-Butanol reacts with the butyric acid to form an ester, butyl butyrate, which is extracted in the oil phase containing n-dodecane.

[0221] Example 2 (not in accordance with the invention): biphasic mixture with biocatalyst (no Pickering emulsion)

[0222] The protocol is the same as in example 1 with the addition of 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution reference L3170-50ML supplied by Sigma-Aldrich.

[0223] Example 3 (not in accordance with the invention): biphasic mixture with biocatalyst and with adjustment of the initial pH to 4 (no Pickering emulsion)

[0224] The protocol is the same as in example 2 with adjustment of the initial pH of the water phase to 4 by adding potassium.

[0225] Example 4 (not in accordance with the invention): biphasic mixture with biocatalyst and with initial pH adjustment to 4.5 (no Pickering emulsion)

[0226] The protocol is the same as in Example 2, with the initial pH of the water phase adjusted to 4.5 by adding potassium hydroxide. Example 5 (not in accordance with the invention): Pickering emulsion in water and oil without a biocatalyst

[0227] 10.5 g of Aerosil® R972 supplied by Evonik, 600 mL of water containing 0.1 mol / L 1-butanol and 0.1 mol / L butyric acid, and 600 mL of n-dodecane are emulsified using an Ultra-Turrax for 10 minutes at 13,500 rpm to form a Pickering emulsion. The droplet size is between 10 and 50 µm. The Pickering emulsion is heated to 40°C and stirred at 500 rpm for 6 hours using a magnetic stir bar. The initial pH of the water phase is 2.7. The 1-butanol reacts with the butyric acid to form an ester, butyl butyrate, which is extracted into the oil phase containing n-dodecane.

[0228] Example 6 (according to the invention): Pickering water-in-oil emulsion with biocatalyst

[0229] 10.5 g of Aerosil® R972 supplied by Evonik, 600 mL of water containing 0.1 mol / L 1-butanol and 0.1 mol / L butyric acid, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50ML, supplied by Sigma-Aldrich, and 600 mL of n-dodecane are emulsified using an Ultra-Turrax for 10 minutes at 13,500 rpm to form the Pickering emulsion. The droplet size is between 10 and 50 µm. The initial pH of the water phase is 2.7. The 1-butanol reacts with the butyric acid to form an ester, butyl butyrate, which is extracted into the oil phase containing n-dodecane.

[0230] Example 7 (according to the invention): Pickering water-in-oil emulsion with biocatalyst and with initial pH adjustment to 4

[0231] The protocol is the same as in example 6 with adjustment of the initial pH of the water phase to 4 by adding potassium.

[0232] Example 8 (according to the invention): Pickering water-in-oil emulsion with biocatalyst and with initial pH adjustment to 4.5

[0233] The protocol is the same as in example 6 with adjustment of the initial pH of the water phase to 4.5 by adding potassium.

[0234] Example 9 (according to the invention): Pickering oil-in-water emulsion with biocatalyst and with initial pH adjustment to 4.5

[0235] 10.5 g of Aerosil® R816 supplied by Evonik, 600 mL of water containing 0.1 mol / L 1-butanol and 0.1 mol / L butyric acid, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50ML, supplied by Sigma-Aldrich, and 600 mL of n-dodecane are emulsified using an Ultra-Turrax for 10 minutes at 13,500 rpm to form the Pickering emulsion. The droplet size is between 10 and 40 µm. The initial pH of the water phase is adjusted to 4.5 by the addition of potassium hydroxide. The 1-butanol reacts with the butyric acid to form an ester, butyl butyrate, which is extracted into the oil phase containing n-dodecane. To extract the oil phase and determine the amount of alcohol extracted, the Pickering emulsion is centrifuged at 5000 rpm for 30 minutes to form two liquid phases. The oil phase sample is taken from the oil phase located above the water phase.

[0236] Example 10 (not in accordance with the invention): biphasic mixture with biocatalyst, excess butyric acid and with initial pH adjustment to 4 (no Pickering emulsion)

[0237] The protocol is the same as in example 3, introducing 0.3 mol / L of butyric acid into the water phase instead of 0.1 mol / L.

[0238] Example 11 (according to the invention): Pickering water-in-oil emulsion with biocatalyst, excess butyric acid and with initial pH adjustment to 4

[0239] The protocol is the same as in example 7, introducing 0.3 mol / L of butyric acid into the water phase instead of 0.1 mol / L.

[0240] Example 12 (not in accordance with the invention): biphasic mixture containing hexanoic acid with biocatalyst (not Pickering emulsion)

[0241] 600 mL of water containing 0.1 mol / L of 1-butanol, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50ML, supplied by Sigma-Aldrich, and 600 mL of n-dodecane containing 0.1 mol / L of hexanoic acid are stirred at 40°C at 500 rpm for 6 hours using a magnetic stir bar. The initial pH of the water phase is 6. The 1-butanol reacts with the hexanoic acid to form an ester, butyl hexanoate, which is extracted into the oil phase containing n-dodecane.

[0242] Example 13 (according to the invention): Pickering water-in-oil emulsion containing hexanoic acid with biocatalyst

[0243] 10.5 g of Aerosil® R972 supplied by Evonik, 600 mL of water containing 0.1 mol / L 1-butanol, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50 mL, supplied by Sigma-Aldrich, and 600 mL of n-dodecane containing 0.1 mol / L hexanoic acid are emulsified using an Ultra-Turrax for 10 minutes at 13,500 rpm to form a Pickering emulsion. The droplet size is between 10 and 50 µm. The initial pH of the water phase is 6. The 1-butanol reacts with the hexanoic acid to form an ester, butyl hexanoate, which is extracted into the oil phase containing n-dodecane. Example 14 (not in accordance with the invention): biphasic mixture containing palmitic acid with biocatalyst (not Pickering emulsion)

[0244] 600 mL of water containing 0.1 mol / L of 1-butanol, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50ML, supplied by Sigma-Aldrich, and 600 mL of n-dodecane containing 0.1 mol / L of palmitic acid are stirred at 40°C at 500 rpm for 6 hours using a magnetic stir bar. The initial pH of the water phase is 6. The 1-Butanol reacts with the palmitic acid to form an ester, butyl palmitate, which is extracted into the oil phase containing n-dodecane. Example 15 (according to the invention): Pickering water-in-oil emulsion containing palmitic acid with biocatalyst

[0245] 10.5 g of Aerosil® R972 supplied by Evonik, 600 mL of water containing 0.1 mol / L 1-butanol, 1.8 mL of the commercial Lipase B Candida antarctica (CaLB) solution, reference L3170-50 mL, supplied by Sigma-Aldrich, and 600 mL of n-dodecane containing 0.1 mol / L palmitic acid are emulsified using an Ultra-Turrax for 10 minutes at 13,500 rpm, followed by Pickering emulsion. The droplet size is between 10 and 50 µm. The initial pH of the water phase is 6. The 1-butanol reacts with the palmitic acid to form an ester, butyl palmitate, which is extracted in the oil phase containing n-dodecane.

[0246] Table 1

[0247] Examples 1 through 11 describe the extraction of an alcohol from an oil phase in its unconverted form and its conversion to an ester formed by the reaction between the alcohol to be extracted and a carboxylic acid added to the reaction medium. The alcohol is present in a first water phase and is extracted into an oil phase. The carboxylic acid is added to the first water phase, and the esterification reaction is carried out under different conditions. Comparative example 1 (biphasic medium) and comparative example 5 (medium in the form of a Pickering emulsion) first show that without the biocatalyst, there is no conversion of the alcohol to an ester, and the alcohol extraction is very low. Comparative examples 2, 3, and 4 show that, in the presence of a biocatalyst in a stirred biphasic medium without a Pickering emulsion, the total extraction rate of the alcohol into the oil phase is low after one hour of reaction.On the contrary, Examples 6, 7, and 8 of the invention show a total alcohol extraction rate in a water-in-oil Pickering emulsion after one hour that is significantly higher than that obtained in a two-phase medium, and is still higher after six hours. Examples 1 through 8 thus clearly demonstrate that the combination of a biocatalyst and a Pickering emulsion enables the fastest alcohol extraction kinetics for a given pH. These examples also show that performance increases as the pH becomes increasingly acidic within the studied range. Example 9 of the invention confirms that the advantages of the invention are maintained in the case of an oil-in-water Pickering emulsion.Example 11 according to the invention shows that an excess of carboxylic acid relative to alcohol increases the extraction of alcohol in ester form and the kinetics which is much higher than in comparative example 10 in stirred biphasic medium without Pickering emulsion.

[0248] Examples 13 and 15 according to the invention and comparative examples 12 and 14 employ carboxylic acids introduced into the oil phase, given their significantly greater solubility in the oil phase than in the water phase. It is once again evident that the implementation according to the invention results in a considerable increase in the rate of alcohol extraction, as demonstrated by the total alcohol extraction rate after one hour. This confirms that the invention offers an advantage whether the carboxylic acid is introduced into the water phase or the oil phase. The examples demonstrate that the combination of an enzymatic catalyst and a Pickering emulsion provides the most effective extraction of an alcohol from a water phase to an oil phase in ester form.

[0249] The examples also show that extractions of alcohol in ester form can be excellent for pH values ​​below 7.

[0250] Example 16: Separation of the oil phase from the first water phase (step b)

[0251] After 6 hours of reaction, the Pickering emulsion is centrifuged at 5000 revolutions per minute for 30 minutes to break the emulsion and form two liquid phases and one solid phase.

[0252] In the case of Aerosil® R972 silica, the solid phase is located between the two liquid phases. The mixture is transferred to a separatory funnel. The water phase, located below, is collected first. The oil phase, located above, is collected second, along with the solid phase. The oil and solid phases are then separated by centrifugation at 5000 rpm for 10 minutes.

[0253] In the case of Aerosil® R816 silica used in example 9, the solid phase is at the bottom of the centrifuge cups. The two liquid phases are collected without the solids and separated in a separatory funnel.

[0254] Example 17: Hydrolysis of the ester contained in the oil phase from Example 11, which is separated from the first water phase according to Example 16, and recovery of 1-butanol

[0255] To the 600 mL of oil phase from Example 11, separated according to the protocol of Example 16, 2.5 mL of a 1 M aqueous solution of p-toluenesulfonic acid are added. The mixture is heated for 6 hours with magnetic stirring in a round-bottom flask fitted with a 40 cm high distillation column, filled with Raschig rings and connected to a condenser. The heating mantle is set to 100°C to achieve boiling. In the first recipe, 1-butanol is released as an azeotrope with water at a temperature of approximately 93°C at the top of the distillation column. Heating is stopped when no more liquid is collected at this temperature. This recipe is unique in that it forms two phases containing only 1-butanol and water after cooling to room temperature. The two aqueous phases are separated in a separatory funnel.The 1-butanol content was determined in both phases by analyzing a sample diluted 7 times in water and analyzed by HPLC (high-performance liquid chromatography) on a Shimadzu LC-20AD instrument with an autosampler injecting 10 pL, an HPX-87H column (Bio-rad), a temperature of 60°C, a 0.01 N aqueous H₂SO₄ mobile phase at 0.6 mL / min, and detection by refractive index and UV-visible spectroscopy at 210 nm. 3.07 g of the upper phase was recovered, containing 80 wt% 1-butanol and 20 wt% water, or 2.45 g of 1-butanol. The mass ratio of 1-butanol to water was therefore 4, whereas it was approximately 7.10. -3in the initial aqueous solution. Additionally, 1.56 g of a lower phase is recovered, containing 8 wt% 1-butanol and 92 wt% water, or 0.12 g of 1-butanol. Since this phase contains very little 1-butanol, it is not processed in this example. In the process, it could be returned to the first step. The oil phase, thus depleted in 1-butanol and containing the butyric acid from the hydrolysis step and the ester that was not hydrolyzed, can be returned to the first step of the process to continue the extraction of 1-butanol from the first water phase that was not extracted.

[0256] Example 18: Hydrolysis of the ester contained in the oil phase from Example 13, which is separated from the first water phase according to Example 16, and recovery of 1-butanol. To the 600 mL of oil phase from Example 13, separated according to the protocol of Example 16, 2.2 mL of a 1 M aqueous solution of p-toluenesulfonic acid are added. The mixture is heated for 6 hours with magnetic stirring in a round-bottom flask equipped with a distillation column approximately 40 cm high, filled with Raschig rings and connected to a condenser. The heating mantle is set to 100°C to reach boiling point. The 1-butanol is recovered in the first recipe as an azeotrope with water at a temperature of approximately 93°C at the top of the distillation column. Heating is stopped when no more liquid is collected at this temperature.The recipe is unique in that it forms two phases containing only 1-butanol and water after cooling to room temperature. The two aqueous phases are separated in a separatory funnel. The 1-butanol content is determined in both phases as in Example 17. 2.77 g of the upper phase is recovered, containing 80% by weight of 1-butanol and 20% by weight of water, or 2.21 g of 1-butanol. The mass ratio of 1-butanol to water is therefore 4, whereas it was approximately 7.10. -3in the initial aqueous solution. Additionally, 1.41 g of a lower phase is recovered, containing 8 wt% 1-butanol and 92 wt% water, or 0.11 g of 1-butanol. Since this phase contains very little 1-butanol, it is not processed in this example. In the process, it could be returned to the first step. The oil phase, thus depleted in 1-butanol and containing the hexanoic acid from the hydrolysis step and the ester that was not hydrolyzed, can be returned to the first step of the process to continue the extraction of 1-butanol from the first water phase that was not extracted.

[0257] Example 19: Hydrolysis of the ester contained in the oil phase from Example 15, which is separated from the first water phase according to Example 16, and recovery of 1-butanol

[0258] To the 600 mL of oil phase from Example 15, separated according to the protocol of Example 16, 2.7 mL of a 1 M aqueous solution of p-toluenesulfonic acid are added. The mixture is heated for 6 hours with magnetic stirring in a round-bottom flask equipped with a 40 cm high distillation column, filled with Raschig rings and connected to a condenser. The heating mantle is set to 100°C to achieve boiling. In the first recipe, 1-butanol is released as an azeotrope with water at a temperature of approximately 93°C at the top of the distillation column. Heating is stopped when no more liquid is collected at this temperature. This recipe is unique in that it forms two phases containing only 1-butanol and water after cooling to room temperature. The two aqueous phases are separated in a separatory funnel. The 1-butanol content is determined in both phases as in example 17.We recovered 3.21g of the upper phase containing 80% by weight of 1-butanol and 20% by weight of water, i.e., 2.56g of 1-butanol. The mass ratio of 1-butanol to water is therefore 4, whereas it was approximately 7.10. -3 in the initial aqueous solution. Additionally, 1.64 g of a lower phase is recovered, containing 8 wt% 1-butanol and 92 wt% water, or 0.13 g of 1-butanol. Since this phase contains very little 1-butanol, it is not processed in this example. In the process, it could be returned to the first step. The oil phase, thus depleted in 1-butanol and containing the palmitic acid from the hydrolysis step and the ester that was not hydrolyzed, can be returned to the first step of the process to continue the extraction of 1-butanol from the first water phase that was not extracted.

Claims

DEMANDS 1. A process for extracting a compound to be extracted selected from an alcohol or a carboxylic acid in an aqueous solution, by formation of an ester comprising the following steps: a) an esterification reaction is carried out on a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion to form an ester in the oil phase, said reaction mixture being obtained according to the following steps: a1) a biphasic mixture is formed comprising at least a first water phase and an oil phase, by contacting an aqueous solution comprising said compound to be extracted, at least one reagent selected from a carboxylic acid or an alcohol, at least one enzymatic catalyst, at least one organic extraction solvent and solid particles; a2) said biphasic mixture obtained in step a1) is emulsified to form a reaction mixture in the form of an oil-in-water or water-in-oil Pickering emulsion;said reaction mixture comprising:; -either droplets of said oil phase stabilized by said solid particles in said first water phase; -either droplets of said first water phase stabilized by said solid particles in said oil phase; b) said oil phase containing the ester formed at the end of step a) is separated; c) the ester obtained at the end of step b) is hydrolyzed to reform said compound to be extracted; d) said compound to be extracted is recovered.

2. A process according to claim 1, wherein the compound to be extracted is an alcohol and the reagent is a carboxylic acid.

3. A process according to claim 1, wherein the compound to be extracted is a carboxylic acid and the reagent is an alcohol.

4. A process according to any one of the preceding claims, wherein the concentration of the compound to be extracted in said aqueous solution is between 0.001 mol / L and 0.4 mol / L when said compound to be extracted is an alcohol, and between 0.001 mol / L and 2 mol / L when said compound to be extracted is a carboxylic acid.

5. A method according to any one of the preceding claims, wherein the molar ratio between said reagent and said compound to be extracted is between 1 and 10.

6. A process according to any one of the preceding claims, wherein said compound to be extracted is of bio-based origin.

7. A method according to any one of the preceding claims, wherein the enzymatic catalyst added in step a1) is selected from lipases of microbial or plant origin.

8. A method according to any one of the preceding claims, wherein the enzymatic catalyst added in step a1) is selected from lipase B of Candida antarctica, lipase of Candida rugosa, or lipase of Rhizomucor miehei.

9. A process according to any one of the preceding claims, wherein the pH of said first water phase is less than 7.

10. A method according to any one of the preceding claims, wherein the solid particles added in step a1) are selected from solid particles of silica, clay, or natural or synthetic polymers.

11. A method according to any one of the preceding claims, wherein the droplet size of the Pickering emulsion obtained at the end of step a2) is between 1 pm and 140 pm.

12. A process according to any one of the preceding claims, wherein the temperature of the esterification reaction in step a) is between 10°C and 90°C.

13. A process according to any one of the preceding claims, wherein the mass concentration of solid particles added in step a1) is between 0.1% weight and 10% weight relative to the total weight of said two-phase mixture.

14. A process according to any one of the preceding claims, wherein the ester is separated from said oil phase in a step b') between step b) and step c).

15. A process according to any one of the preceding claims, wherein a step a') of producing said compound to be extracted selected from said alcohol or said carboxylic acid in aqueous solution is carried out in combination with step a).

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