Method for producing carboxylic acid

Abstract

This carboxylic acid production method enables a carboxylic acid to be produced efficiently, the method comprising: a step (A) for filtering a carboxylic acid-containing fermentation liquid by passing the same through a nano-filtration membrane to obtain a carboxylic acid-containing filtrate from the permeation side; and a step (B) for extracting, from the carboxylic acid-containing filtrate obtained in step (A), a carboxylic acid by using an extraction solvent that undergoes phase separation with respect to the filtrate, and recovering a carboxylic acid extract obtained as a phase separated from a water phase.

Description

[Technical field]

[0001] The present invention relates to a method for producing a carboxylic acid from a fermentation liquor containing the carboxylic acid. [Background technology]

[0002] Conventionally, as a means for recovering carboxylic acids from fermentation liquor containing carboxylic acids, extraction separation is often used in addition to adsorption separation using anion exchange resins, electrodialysis, crystallization, etc. In the extraction of carboxylic acids from fermentation liquor containing carboxylic acids, a phenomenon is known in which an intermediate phase containing solids that are not dissolved in either the aqueous or organic phase is generated at the phase interface between the fermentation liquor (aqueous phase) and the extraction solvent (organic phase), and this phenomenon is known to cause problems such as the need to add a solid removal step because it inhibits phase separation during extraction. As a means for solving this problem, a method using membrane filtration has already been proposed. For example, Patent Document 1 describes that in recovering amino acids by extraction from an amino acid fermentation liquor, the amino acid fermentation liquor is passed through an ultrafiltration membrane (UF membrane) through which molecules with a molecular weight of 1000 or less can pass in the pre-extraction stage, thereby removing cytoplasm and other solids, and thus accelerating phase separation between the amino acid fermentation liquor and the extraction solvent. Patent Document 2 describes that when recovering aliphatic dicarboxylic acids from an aliphatic dicarboxylic acid fermentation liquor by extraction, microorganisms are removed by passing the liquor through a microfiltration membrane (MF membrane), and phase separation between the aliphatic dicarboxylic acid fermentation liquor and the extraction solvent is accelerated, and that a microfiltration membrane is more suitable as a filtration membrane than an ultrafiltration membrane. In addition, Patent Document 3 describes that impurities are removed by passing a monocarboxylic acid fermentation liquor through a nanofiltration membrane, and the purity of the recovered monocarboxylic acid is increased. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 62-277349 [Patent Document 2] JP 2015-119738 A [Patent Document 3] JP 2010-095450 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Documents 1 and 2 disclose that phase separation during extraction is accelerated by passing the fermentation liquid through ultrafiltration or microfiltration, respectively. However, according to the investigations conducted by the present inventors, it was found that there is a problem in that phase separation between the aqueous phase and the organic phase during extraction is insufficient when the fermentation liquid containing a carboxylic acid is passed through either a microfiltration membrane or an ultrafiltration membrane (Comparative Example 1 of the present application).

[0005] Therefore, an object of the present invention is to find a method for improving the phase separation between the aqueous phase and the organic phase when extracting carboxylic acids from a carboxylic acid-containing fermentation liquor. [Means for solving the problem]

[0006] As mentioned above, a method for increasing the purity of monocarboxylic acid by passing a monocarboxylic acid-containing fermentation liquid through a nanofiltration membrane is known as a conventional technique, but no suggestion has been made about the effect of nanofiltration membrane treatment on the carboxylic acid extraction process. Rather, it has been suggested that a nanofiltration membrane with a smaller mesh size than an ultrafiltration membrane is less suitable than an ultrafiltration membrane. However, the present inventors have conducted intensive research to solve the above problems, and have found that phase separation between the aqueous phase and the organic phase after extraction is promoted by passing a carboxylic acid fermentation liquid through a nanofiltration membrane before subjecting it to the carboxylic acid extraction process, thereby completing the present invention.

[0007] That is, the present invention comprises the following (1) to (5). (1) A method for producing a carboxylic acid, comprising the following steps (A) and (B): (A) A step of filtering a carboxylic acid-containing fermentation liquid through a nanofiltration membrane to obtain a carboxylic acid-containing filtrate from the permeation side. (B) A step of extracting carboxylic acids from the carboxylic acid-containing filtrate obtained in step (A) with an extraction solvent that undergoes phase separation from the filtrate, and recovering the carboxylic acid extract that has separated from the aqueous phase. (2) The method according to (1), wherein the pH of the carboxylic acid-containing fermentation liquid and / or the carboxylic acid-containing filtrate is adjusted to 4.5 or less. (3) The method according to (1) or (2), further comprising a step of removing insoluble matter before passing the carboxylic acid-containing fermentation liquid through the nanofiltration membrane in step (A). (4) The method according to (3), wherein the step of removing the insoluble matter is a step of passing the carboxylic acid-containing fermentation liquid through a microfiltration membrane. (5) The method according to any one of (1) to (4), wherein the carboxylic acid has a molecular weight of 200 or less. Effect of the Invention

[0008] According to the present invention, in the case where carboxylic acids are recovered from a carboxylic acid-containing fermentation liquor by extraction, phase separation into an aqueous phase and an organic phase after extraction is promoted, and carboxylic acids can be produced efficiently. [Brief description of the drawings]

[0009] [Figure 1] 1 is a photograph taken immediately after contacting a carboxylic acid-containing filtrate obtained through a nanofiltration membrane with an extraction solvent in a test for extracting carboxylic acids from the carboxylic acid-containing filtrate. [Diagram 2] Photographs taken in a test of extracting carboxylic acids from a carboxylic acid-containing fermentation liquor that had not been passed through a nanofiltration membrane, taken immediately after (a) and 12 hours after (b) contacting the carboxylic acid-containing fermentation liquor with the extraction solvent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in more detail below, but the present invention is not limited to the following embodiments.

[0011] In the present invention, carboxylic acid is a general term for a compound having one or more carboxyl groups (COOH groups) in the molecule. The carboxylic acid in the present invention is not particularly limited, but carboxylic acids having a molecular weight of about 200 or less are preferred because they have high permeability through the nanofiltration membrane described below. Specific examples of preferred carboxylic acids include formic acid, acetic acid, propionic acid, oxalic acid, glycolic acid, gluconic acid, acrylic acid, butyric acid, isobutyric acid, γ-aminobutyric acid, valeric acid, isovaleric acid, pyruvic acid, lactic acid, hydroxybutyric acid, succinic acid, fumaric acid, maleic acid, itaconic acid, malic acid, tartaric acid, oxaloacetic acid, glutaric acid, 2-oxoglutaric acid, adipic acid, adipic acid semialdehyde, 3-oxoacetate, and 1-methylbutanediol. Examples include dipic acid, 3-hydroxyadipic acid, 3-hydroxyadipic acid-3,6-lactone, α-hydromuconic acid, β-hydromuconic acid, muconic acid, muconolactone, 2-keto-L-gulonic acid, 6-aminocaproic acid, aconitic acid, benzoic acid, 4-hydroxybenzoic acid, phenylacetic acid, terephthalic acid, isophthalic acid, shikimic acid, phenylalanine, tyrosine, and histidine.

[0012] In the present invention, the carboxylic acid-containing fermentation liquid includes not only a culture liquid in which a carboxylic acid is produced in a liquid medium containing fermentation raw materials such as a carbon source, a nitrogen source, inorganic salts, amino acids, and vitamins by the action of a microorganism, but also a culture liquid in which a microorganism is cultured in a liquid medium containing the fermentation raw materials and a carboxylic acid that has been separately chemically or biologically synthesized has been added.

[0013] Examples of carbon sources used in culturing microorganisms include monosaccharides such as glucose, sucrose, fructose, galactose, mannose, xylose, and arabinose, disaccharides and polysaccharides formed by combining these monosaccharides, and molasses, beet molasses, cane molasses, blackstrap molasses, starch saccharification liquid, and cellulose-containing biomass saccharification liquid, which contain these saccharides. Examples of nitrogen sources include ammonia gas, ammonia water, ammonium salts, urea, nitrates, and other supplementary organic nitrogen sources, such as oil cakes, soybean hydrolyzate, casein hydrolyzate, other amino acids, vitamins, corn steep liquor, yeast or yeast extract, meat extract, and peptides such as peptone. Examples of inorganic salts that can be added include phosphates, magnesium salts, calcium salts, iron salts, and manganese salts. In addition, waste biomass can be used as a fermentation raw material containing these carbon sources, nitrogen sources, inorganic salts, amino acids, and vitamins. Examples of waste biomass include food waste, livestock manure, sewage sludge, agricultural residues, and wood waste.

[0014] The microorganisms used for preparing the carboxylic acid-containing fermentation liquid are not particularly limited, and examples thereof include yeasts such as baker's yeast, bacteria such as Escherichia coli and coryneform bacteria, filamentous fungi, actinomycetes, etc. The microorganisms used may be those isolated from the natural environment, or may be those whose properties have been partially modified by mutation or genetic recombination.

[0015] [Process (A)] In the present invention, first, in step (A), a carboxylic acid-containing fermentation liquid is passed through a nanofiltration membrane to obtain a carboxylic acid-containing filtrate.

[0016] In the present invention, "passing through a nanofiltration membrane" means passing a carboxylic acid-containing fermentation liquid through a nanofiltration membrane and recovering a permeate containing a carboxylic acid from the permeate side. In addition, in this specification, the permeate of the nanofiltration membrane containing a carboxylic acid is referred to as a carboxylic acid-containing filtrate.

[0017] By passing the carboxylic acid-containing fermentation liquid through a nanofiltration membrane, the production of an intermediate phase containing solids that are not dissolved in either the aqueous or organic phase after the extraction of carboxylic acids in the subsequent step (B) is suppressed, and phase separation between the aqueous and organic phases is promoted.

[0018] The carboxylic acid in the carboxylic acid-containing fermentation liquor may be dissolved in water as the carboxylic acid or a salt of the carboxylic acid. Examples of the salt of the carboxylic acid include lithium salt, sodium salt, potassium salt, magnesium salt, calcium salt, ammonium salt, etc. A mixture of different salts of these may also be used.

[0019] The carboxylic acid concentration in the carboxylic acid-containing fermentation liquid filtered through the nanofiltration membrane is not particularly limited, but if the concentration is high, the carboxylic acid concentration in the carboxylic acid-containing filtrate is also high, which is suitable for reducing energy consumption during concentration. As a method for increasing the concentration of the carboxylic acid, i.e., a method for concentrating the carboxylic acid, an evaporation concentration method in which water is evaporated and removed, a reverse osmosis membrane concentration method in which water is removed by passing the fermentation liquid through a reverse osmosis membrane, or a combination of these methods can be used.

[0020] The nanofiltration membrane material used in the present invention can be a polymeric material such as cellulose acetate polymer, polyamide, polyester, polyimide, vinyl polymer, etc., but is not limited to a membrane made of one of the above materials, and may be a membrane containing multiple membrane materials. The membrane structure may be either an asymmetric membrane having a dense layer on at least one side of the membrane and gradually increasing pore sizes from the dense layer toward the inside of the membrane or the other side, or a composite membrane having a very thin functional layer made of another material on the dense layer of the asymmetric membrane. For example, a composite membrane can be used, which is a nanofiltration membrane made of a polyamide functional layer on a support membrane made of polysulfone as a membrane material, as described in JP-A-62-201606.

[0021] In the present invention, among these, a composite membrane having a polyamide functional layer is preferred, which has high pressure resistance, high water permeability, high solute removal performance, and excellent potential. Furthermore, in order to maintain durability against operating pressure, high water permeability, and blocking performance, a structure in which a polyamide is used as a functional layer and is supported by a support made of a porous membrane or nonwoven fabric is preferred. In a nanofiltration membrane having a polyamide functional layer, preferred carboxylic acid components of the monomer constituting the polyamide include, for example, aromatic carboxylic acids such as trimesic acid, benzophenone tetracarboxylic acid, trimellitic acid, pyromet acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, diphenyl carboxylic acid, and pyridine carboxylic acid, but in consideration of solubility in a membrane-forming solvent, trimesic acid, isophthalic acid, terephthalic acid, or a mixture thereof is more preferred.

[0022] Preferred amine components of the monomers constituting the polyamide include m-phenylenediamine, p-phenylenediamine, benzidine, methylenebisdianiline, 4,4'-diaminobiphenyl ether, dianisidine, 3,3',4-triaminobiphenyl ether, 3,3',4,4'-tetraaminobiphenyl ether, 3,3'-dioxybenzidine, 1,8-naphthalenediamine, m(p)-monomethylphenylenediamine, 3,3'-monomethylamino-4,4'-diaminobiphenyl ether, 4,N,N'-(4-amino- Examples of the diamine include primary diamines having an aromatic ring such as 2,2'-bis(4-aminophenylbenzoyl)-p(m)-phenylenediamine-2,2'-bis(4-aminophenylbenzimidazole), 2,2'-bis(4-aminophenylbenzoxazole), and 2,2'-bis(4-aminophenylbenzothiazole), and secondary diamines such as piperazine, piperidine, or derivatives thereof. Among them, nanofiltration membranes having a crosslinked polyamide containing piperazine or piperidine as a monomer as a functional layer are preferably used because they have pressure resistance, durability, heat resistance, and chemical resistance. More preferred are nanofiltration membranes having the crosslinked piperazine polyamide or crosslinked piperidine polyamide as the main component. Examples of nanofiltration membranes having a polyamide containing piperazine polyamide as a functional layer include those described in JP-A-62-201606, and specific examples include UTC-60 and UTC-63, which are crosslinked piperazine polyamide-based semipermeable membranes manufactured by Toray Industries, Inc.

[0023] Examples of the spiral-type nanofiltration membrane element used in the present invention include nanofilter modules SU-210, SU-220, SU-600, and SU-610 manufactured by Toray Industries, Inc., including UTC-60 and UTC-63 manufactured by the same company, which have a crosslinked piperazine polyamide functional layer. Other examples include nanofiltration membranes NF-45, NF-90, NF-200, and NF-400 manufactured by Filmtec Co., Ltd., which have a crosslinked piperazine polyamide functional layer, nanofiltration membranes NF99, NF97, and NF99HF manufactured by Alfa Laval Co., Ltd., which have a polyamide functional layer, and GEsepa, a cellulose acetate-based nanofiltration membrane manufactured by GE Osmonics.

[0024] In the present invention, the filtration of the carboxylic acid-containing fermentation liquid through the nanofiltration membrane may be performed under pressure. The filtration pressure is not particularly limited, but is preferably in the range of 0.1 MPa to 8 MPa, since a pressure lower than 0.1 MPa reduces the membrane permeation rate, and a pressure higher than 8 MPa damages the membrane, and is more preferably in the range of 0.1 MPa to 7 MPa, since the membrane permeation flux is high and the carboxylic acid can be efficiently permeated.

[0025] In the present invention, in the filtration of the carboxylic acid-containing fermentation liquor through a nanofiltration membrane, the retentate is returned to the raw water and the filtration is repeated, thereby improving the recovery rate of the carboxylic acid.

[0026] Nanofiltration membranes have the property that substances that are not ionized (undissociated) in a solution are more easily permeable than ionized (dissociated) substances, so by making the pH of the carboxylic acid-containing fermentation liquor acidic, the amount of carboxylic acid in the carboxylic acid state, not the carboxylate, increases, making it easier to permeate the nanofiltration membrane. On the other hand, if the pH is too low, there is a concern that the equipment may corrode, which is industrially disadvantageous. From these perspectives, the pH of the carboxylic acid-containing fermentation liquor that passes through the nanofiltration membrane is preferably adjusted to pH 4.5 or less, more preferably adjusted to pH 1.5 to 4.5, and even more preferably adjusted to pH 2.0 to 4.0.

[0027] The acid used to adjust the pH of the carboxylic acid-containing fermentation liquid passing through the nanofiltration membrane is not particularly limited as long as it can make the pH acidic, but mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and boric acid can be preferably used.

[0028] The carboxylic acid-containing fermentation liquor contains insoluble substances derived from bacteria and fermentation raw materials that are not assimilated, and biological substances such as proteins secreted from microorganisms. From the viewpoint of suppressing clogging of the nanofiltration membrane, it is preferable to remove the insoluble substances in the carboxylic acid-containing fermentation liquor prior to the above-mentioned nanofiltration membrane treatment, and it is more preferable to remove biological substances such as proteins in the carboxylic acid-containing fermentation liquor together with removing the insoluble substances.

[0029] As a method for removing insoluble substances from a carboxylic acid-containing fermentation liquor, for example, the carboxylic acid-containing fermentation liquor can be passed through a microfiltration membrane (MF membrane) to obtain a carboxylic acid-containing fermentation liquor from which insoluble substances have been removed from the permeate side. Alternatively, the carboxylic acid-containing fermentation liquor can be centrifuged to precipitate the insoluble substances and recover the supernatant to obtain a carboxylic acid-containing fermentation liquor from which insoluble substances have been removed. In the present invention, a step of removing insoluble substances using a microfiltration membrane is preferably adopted.

[0030] The microfiltration membrane is not particularly limited as long as it has the function of separating insoluble substances derived from bacterial cells and fermentation raw materials that are not assimilated, and examples of the material that can be used include porous ceramic membranes, porous glass membranes, porous organic polymer membranes, woven metal fiber bodies, and nonwoven fabrics. Of these, porous organic polymer membranes and ceramic membranes are particularly preferred.

[0031] The microfiltration membrane preferably includes a porous resin layer as a functional layer, for example, from the viewpoint of stain resistance.

[0032] The microfiltration membrane including a porous resin layer preferably has a porous resin layer acting as a functional layer on the surface of a porous substrate.

[0033] The material of the porous substrate is made of an organic material and / or an inorganic material, and organic fibers are preferably used. Preferred porous substrates are woven or nonwoven fabrics made of organic fibers such as cellulose fibers, cellulose triacetate fibers, polyester fibers, polypropylene fibers, and polyethylene fibers, and more preferably nonwoven fabrics that are relatively easy to control the density, easy to manufacture, and inexpensive.

[0034] The porous resin layer can be suitably made of an organic polymer membrane. Examples of the material of the organic polymer membrane include polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinylidene fluoride resins, polysulfone resins, polyethersulfone resins, polyacrylonitrile resins, cellulose resins, and cellulose triacetate resins. The organic polymer membrane may be a mixture of resins mainly composed of these resins. Here, the main component means that the component is contained in an amount of 50% by weight or more, preferably 60% by weight or more. The material of the organic polymer membrane is preferably polyvinyl chloride resins, polyvinylidene fluoride resins, polysulfone resins, polyethersulfone resins, and polyacrylonitrile resins, which are easy to form into a membrane from a solution and have excellent physical durability and chemical resistance, and polyvinylidene fluoride resins or resins mainly composed of them are most preferably used.

[0035] Here, as the polyvinylidene fluoride-based resin, a homopolymer of vinylidene fluoride is preferably used. Furthermore, as the polyvinylidene fluoride-based resin, a copolymer of vinylidene fluoride and a vinyl monomer copolymerizable therewith is also preferably used. Examples of the vinyl monomer copolymerizable with vinylidene fluoride include tetrafluoroethylene, hexafluoropropylene, and trichloroethylene fluoride.

[0036] As a method for removing biological substances such as proteins from a carboxylic acid-containing fermentation liquor, for example, the carboxylic acid-containing fermentation liquor can be passed through an ultrafiltration membrane (UF membrane) to obtain a carboxylic acid-containing fermentation liquor from the permeate side from which biological substances such as proteins have been removed.

[0037] The molecular weight cutoff of the ultrafiltration membrane is not particularly limited as long as it is in the range of 2,000 to 100,000, but the molecular weight cutoff is preferably in the range of 5,000 to 100,000, and more preferably in the range of 5,000 to 30,000.

[0038] Materials that can be used for the ultrafiltration membrane include polyethersulfone, polysulfone, polyacrylonitrile, polyvinylidene fluoride, regenerated cellulose, cellulose, cellulose ester, sulfonated polysulfone, sulfonated polyethersulfone, polyolefin, polyvinyl alcohol, polymethyl methacrylate, and polytetrafluoroethylene.

[0039] Specific examples of ultrafiltration membranes used in the present invention include GH (G-10) type, GK (G-20) type, and GM (G-50) type of the DESAL brand M series, P series, and G series manufactured by GE W&PT, HWS UF type and STD UF type of the "DURATHERM" (registered trademark) series, VT, MT, ST, SM, MK, MW, LY, BN, and BY manufactured by Synder, "Microza" (registered trademark) UF series manufactured by Asahi Kasei Corporation, and NTR-7410 and NTR-7450 manufactured by Nitto Denko Corporation.

[0040] The order in which insoluble substances derived from bacterial cells, fermentation raw materials, etc., and biological substances such as proteins are removed is not particularly limited. However, it is preferable to remove larger sized bacterial cells or insoluble substances derived from fermentation raw materials, etc., first, since this can prevent clogging of the ultrafiltration membrane.

[0041] [Process (B)] In the present invention, in step (B), carboxylic acids are extracted from the carboxylic acid-containing filtrate obtained in step (A) with an extraction solvent that undergoes phase separation from the filtrate, and the carboxylic acid extract that has separated from the aqueous phase is recovered.

[0042] The extraction solvent used in step (B) is not particularly limited as long as it can separate the carboxylic acid from the filtrate containing the carboxylic acid obtained in step (A) and extract the carboxylic acid. Examples of the extraction solvent include aliphatic hydrocarbon extraction solvents such as pentane, hexane, and heptane; aromatic hydrocarbon extraction solvents such as benzene, toluene, and xylene; chlorine-based extraction solvents such as carbon tetrachloride, chloroform, dichloromethane, and trichloroethylene; ester-based extraction solvents such as ethyl acetate and butyl acetate; ketone-based extraction solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; ether-based extraction solvents such as dimethyl ether, diethyl ether, diisopropyl ether, and dibutyl ether; butanone. Examples of the extraction solvent include alcohols having 4 or more carbon atoms, such as oleyl alcohol, hexanol, octanol, decanol, and oleyl alcohol; isopropanol mixed extraction solvents, such as chloroform / isopropanol mixed solution, dichloromethane / isopropanol mixed solution, and ethyl acetate / isopropanol mixed solution; long-chain amine extraction solvents, such as trioctylamine, trinonylamine, and tridecylamine; alkylphosphine oxide extraction solvents, such as tributylphosphine oxide and trioctylphosphine oxide; and ammonium, imidazolium, phosphonium, pyridinium, pyrrolidinium, and sulfonium ionic liquid extraction solvents. These extraction solvents may be used alone or as a mixture of two or more.

[0043] When a chloroform / isopropanol mixed solution, a dichloromethane / isopropanol mixed solution, or an ethyl acetate / isopropanol mixed solution is used as the extraction solvent, the ratio of isopropanol mixed is preferably 40% by volume or less. If the ratio of isopropanol mixed is high, the phase separation with the carboxylic acid-containing filtrate tends to decrease.

[0044] The extraction temperature in step (B) is not particularly limited, but from the viewpoint that it is preferable that the temperature range is such that the carboxylic acid-containing filtrate and the extraction solvent do not solidify or boil, it is more preferably 5°C or higher and 100°C or lower, even more preferably 10°C or higher and 90°C or lower, and particularly preferably 20°C or higher and 80°C or lower.

[0045] In step (B), the pH of the carboxylic acid-containing filtrate is not particularly limited as long as it is less than pH 7, which is an acidic condition, but since carboxylic acids that are not in the form of carboxylates tend to be more easily extracted into the extraction solvent, a lower pH is preferable. On the other hand, if the pH is too low, corrosion of the equipment becomes a concern, which is industrially disadvantageous. From these viewpoints, the pH of the carboxylic acid-containing filtrate in step (B) is preferably adjusted to pH 4.5 or less, more preferably adjusted to pH 1.5 to 4.5, and even more preferably adjusted to pH 2.0 to 4.0.

[0046] The acid used to adjust the pH of the carboxylic acid-containing filtrate in step (B) is not particularly limited as long as it can make the pH acidic. However, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and boric acid that are preferably used for adjusting the pH in step (A) can be preferably used.

[0047] The carboxylic acid concentration in the carboxylic acid-containing filtrate to be subjected to step (B) is not particularly limited, but the higher the concentration, the easier the carboxylic acid tends to move to the extraction solvent. Specifically, it is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, even more preferably 1% by weight or more, and particularly preferably 20% by weight or more. As a method for increasing the concentration of the carboxylic acid, that is, a method for concentrating the carboxylic acid, an evaporation concentration method for evaporating and removing water, a reverse osmosis membrane concentration method for removing water by passing through a reverse osmosis membrane, or a combination of these methods can be used. In addition, the concentration of the carboxylic acid-containing filtrate may be adjusted to a desired concentration by appropriately adjusting the concentration of the carboxylic acid-containing fermentation liquid to be subjected to step (A).

[0048] By contacting the raffinate, which is the aqueous phase after the carboxylic acids have been extracted with the extraction solvent, with fresh extraction solvent, the carboxylic acids remaining in the raffinate can be further recovered, thereby increasing the recovery rate of the carboxylic acids. The raffinate with a sufficiently reduced carboxylic acid concentration may be used as water to prepare a carboxylic acid-containing fermentation liquor, or may be purged to the outside of the system.

[0049] The extraction can be carried out by batch extraction, parallel current multiple extraction, countercurrent multiple stage extraction, etc. For continuous extraction on an industrial scale, a mixer-settler type extractor or a tower type extractor such as a perforated plate extraction tower, a pulse tower or a mixer-settler tower can be used.

[0050] [Subsequent process] The recovery of the carboxylic acid from the carboxylic acid extract can be carried out by a conventional method, such as a method of simply distilling off the extraction solvent, a method of distilling the carboxylic acid, a method of precipitating the carboxylic acid and then subjecting it to solid-liquid separation, a method of back-extracting the carboxylic acid into water and then separating it from water by distillation, concentration, or precipitation, etc.

[0051] The extraction solvent removed from the extract may be reused as it is as the extraction solvent in step (B) or may be purified by distillation and then reused as the extraction solvent in step (B). When the extraction solvent is purified by distillation, the amount of carboxylic acid recovered can be increased by recovering a trace amount of carboxylic acid contained in the extraction solvent.

[0052] [Other processes] In the present invention, the carboxylic acid-containing fermentation liquid to be subjected to step (A), the carboxylic acid-containing filtrate to be subjected to step (B), an aqueous solution containing carboxylic acid that may be produced in a step subsequent to step (B), etc. are passed through a reverse osmosis membrane (RO membrane) to concentrate the carboxylic acid. Here, "passing through a reverse osmosis membrane" means passing through the reverse osmosis membrane to filter, removing water from the permeate side, and recovering an aqueous solution containing carboxylic acid with an increased carboxylic acid concentration from the non-permeate side.

[0053] As the membrane material of the reverse osmosis membrane used in the present invention, generally commercially available polymeric materials such as cellulose acetate polymers, polyamides, polyesters, polyimides, vinyl polymers, etc. can be used, but the membrane is not limited to being made of one type of material, and may be made of a plurality of membrane materials. As the membrane form, any suitable form such as a flat membrane type, a spiral type, a hollow fiber type, etc. can be used.

[0054] Specific examples of the reverse osmosis membrane used in the present invention include polyamide reverse osmosis membranes (UTC) SU-710, SU-720, SU-720F, SU-710L, SU-720L, SU-720LF, SU-720R, SU-710P, SU-720P, SU-810, SU-820, SU-820L, and SU-820FA manufactured by Toray Industries, Inc., and cellulose acetate reverse osmosis membranes SC-L100R, SC-L200R, SC-L200R, and SC-L300R manufactured by Toray Industries, Inc. 1100, SC-1200, SC-2100, SC-2200, SC-3100, SC-3200, SC-8100, SC-8200, NTR-759HR, NTR-729HF, NTR-70SWC, ES10-D, ES20-D, ES20-U, ES15-D, ES15-U, LF10-D manufactured by Nitto Denko Corporation, RO98pHt, RO99, HR98PP, CE4040C-30D manufactured by Alfa Laval, GE Sepa manufactured by GE, and BW30-4040, TW30-4040, XLE-4040, LP-4040, LE-4040, SW30-4040, SW30HRLE-4040 manufactured by Filmtec.

[0055] Filtration through a reverse osmosis membrane is performed under pressure, and since a filtration pressure lower than 1 MPa reduces the membrane permeation rate, and a filtration pressure higher than 8 MPa can damage the membrane, the filtration pressure is preferably in the range of 1 MPa to 8 MPa, more preferably in the range of 1 MPa to 7 MPa, and even more preferably in the range of 2 MPa to 6 MPa. EXAMPLES

[0056] The present invention will be described in more detail below using Reference Examples, Examples, and Comparative Examples, but the present invention is not limited to these results.

[0057] [HPLC analysis conditions] The HPLC analysis was carried out under the following analytical conditions. Column 1: Synergi Polar-RP (Phenomenex) Column 2: Synergi Hydro-RP (Phenomenex) Column temperature: 45℃ Mobile phase 1: 5 mM formic acid aqueous solution / acetonitrile = 98 / 2 (vol / vol), 1 mL / min Mobile phase 2: (5 mM formic acid, 20 mM Bis-Tris, 0.1 mM EDTA-2Na) aqueous solution / acetonitrile = 98 / 2 (vol / vol), 1 mL / min Detection: Electrical conductivity.

[0058] [pH analysis method] A Horiba pH meter F-52 (Horiba, Ltd.) was used. pH calibration was performed using a pH 4.01 standard solution (FUJIFILM Wako Pure Chemical Industries, Ltd.), a pH 6.86 standard solution (FUJIFILM Wako Pure Chemical Industries, Ltd.), and a pH 9.18 standard solution (FUJIFILM Wako Pure Chemical Industries, Ltd.).

[0059] (Reference Example 1) Preparation of fermentation liquid containing carboxylic acids (acetic acid, succinic acid) A carboxylic acid-containing fermentation liquid (model fermentation liquid) was prepared by the following procedure. Escherichia coli NBRC3301 strain was inoculated into 5 mL of LB medium in a test tube and cultured overnight with shaking (preculture). The preculture liquid was inoculated into 1 L of medium with the composition shown below and cultured in a Sakaguchi flask (volume 2 L) with shaking for 24 hours. Acetic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) and succinic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were added to this culture liquid so that the concentrations of acetic acid and succinic acid were 10 g / L, respectively, to prepare a carboxylic acid-containing fermentation liquid.

[0060] [Medium composition] Glucose 10 g / L Ammonium sulfate 0.5g / L Potassium phosphate 50mM Magnesium sulfate 0.013g / L Iron sulfate 0.032mg / L Manganese sulfate 1.35mg / L Calcium chloride 0.17mg / L Sodium chloride 1.25g / L Bacto Tryptone 2.50g / L Yeast extract 1.25g / L pH 6.5.

[0061] (Reference examples 2~5) The carboxylic acid-containing fermentation liquid prepared in Reference Example 1 was passed through a microfiltration membrane (a porous membrane with a pore size of 0.01 μm or more and less than 1 μm; manufactured by Toray Industries, Inc.), and then through an ultrafiltration membrane (molecular weight cutoff of 10,000; manufactured by Toray Industries, Inc.). 1 L of this carboxylic acid-containing fermentation liquid was transferred to a raw water tank and passed through a nanofiltration membrane once under the following nanofiltration membrane treatment condition 1. The obtained carboxylic acid-containing filtrate lost its color and was a clear aqueous solution. The carboxylic acid concentration was analyzed by HPLC, and the transmittance was calculated according to the following formula. The calculated transmittance results are shown in Table 1.

[0062] Transmittance (%) = (concentration of compound in permeate) / (concentration of compound in raw water) × 100.

[0063] (Reference examples 6~9) The experiment was carried out in the same manner as in Reference Examples 2 to 5, except that concentrated sulfuric acid (Sigma-Aldrich) was added to the carboxylic acid-containing fermentation liquid after passing through the ultrafiltration membrane to adjust the pH to 4.0. The obtained carboxylic acid-containing filtrate was colorless and was a clear aqueous solution. The calculated transmittance is shown in Table 1.

[0064] (Reference examples 10~13) The same experiments as in Reference Examples 6 to 9 were carried out except that the pH was adjusted to 2.0. The obtained carboxylic acid-containing filtrate was colorless and was a clear aqueous solution. The calculated transmittance is shown in Table 1.

[0065] [Nanofiltration membrane treatment condition 1] Separation membrane: UTC-63 (manufactured by Toray Industries, Inc.) Membrane separation device: "SEPA" (registered trademark) CF-II (manufactured by GE W&PT) Operating temperature: 25℃ Filtration pressure: 0.21~2.03MPa.

[0066] Reference Examples 2 to 13 show that a carboxylic acid-containing filtrate, which is a permeate containing carboxylic acid, can be obtained by passing a carboxylic acid-containing fermentation liquid through a nanofiltration membrane. It was also shown that the permeability of carboxylic acid can be improved by adding an acid before passing through the nanofiltration membrane.

[0067] [Table 1]

[0068] (Reference example 14) 1 L of the carboxylic acid-containing fermentation liquid prepared in Reference Example 1 was passed through a microfiltration membrane (a porous membrane with a pore size of 0.01 μm or more and less than 1 μm; manufactured by Toray Industries, Inc.), and then through an ultrafiltration membrane (molecular weight cutoff of 10,000; manufactured by Toray Industries, Inc.), after which concentrated sulfuric acid (manufactured by Sigma-Aldrich) was added to adjust the pH to 4.0. This carboxylic acid-containing fermentation liquid was transferred to a raw water tank and passed through a nanofiltration membrane under the following nanofiltration membrane treatment condition 2.

[0069] [Nanofiltration membrane treatment condition 2] Separation membrane: UTC-63 (manufactured by Toray Industries, Inc.) Membrane separation device: "SEPA" (registered trademark) CF-II (manufactured by GE W&PT) Operating temperature: 25℃ Filtration pressure: 0.5MPa.

[0070] The carboxylic acid-containing filtrate was concentrated to 100 mL using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd.). The pH of the concentrated aqueous solution was 4.6. 0.5 mL of the aqueous solution and 0.5 mL of dichloromethane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 2 mL Eppendorf tube, and the tube was shaken at room temperature for 1 hour at 1500 rpm using a Cute Mixer CM-1000 (manufactured by Tokyo Rikakikai Co., Ltd.). After shaking, the carboxylic acid concentration in the aqueous phase was measured by HPLC, and the extraction rate was calculated according to the following formula. The results are shown in Table 2.

[0071] Extraction rate (%) = (1 - (concentration of the compound to be extracted in the raffinate) / (concentration of the compound to be extracted before extraction)) x 100.

[0072] (Reference example 15) The experiment was carried out in the same manner as in Reference Example 14, except that ethyl acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of dichloromethane. The results are shown in Table 2.

[0073] (Reference example 16) An experiment was carried out in the same manner as in Reference Example 14, except that methyl isobutyl ketone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of dichloromethane. The results are shown in Table 2.

[0074] (Reference example 17) An experiment was carried out in the same manner as in Reference Example 14, except that concentrated sulfuric acid (Sigma-Aldrich) was added to the concentrated solution of the carboxylic acid-containing filtrate to adjust the pH to 4.0. The results are shown in Table 2.

[0075] (Reference example 18) Except for using ethyl acetate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) instead of dichloromethane, an experiment was carried out in the same manner as in Reference Example 17. The results are shown in Table 2.

[0076] (Reference example 19) An experiment was carried out in the same manner as in Reference Example 17, except that methyl isobutyl ketone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of dichloromethane. The results are shown in Table 2.

[0077] [Table 2]

[0078] Reference Examples 14 to 19 show that carboxylic acids can be extracted from a carboxylic acid-containing filtrate into an extraction solvent. In addition, it was shown that the extraction rate tends to be higher when the pH of the carboxylic acid-containing filtrate is 4.5 or less.

[0079] Example 1 1 L of the carboxylic acid-containing fermentation liquid prepared in Reference Example 1 was passed through a microfiltration membrane (a porous membrane with a pore size of 0.01 μm or more and less than 1 μm; manufactured by Toray Industries, Inc.), and then passed through an ultrafiltration membrane (molecular weight cutoff of 10,000; manufactured by Toray Industries, Inc.), and then concentrated sulfuric acid (manufactured by Sigma-Aldrich) was added to adjust the pH to 4.0. This carboxylic acid-containing fermentation liquid was transferred to a raw water tank and passed through a nanofiltration membrane under the nanofiltration membrane treatment condition 2. The non-permeated liquid was returned to the raw water tank, and if the liquid volume was insufficient, pure water was added to the raw water tank to continue the nanofiltration membrane treatment, and a carboxylic acid-containing filtrate in which the entire amount of carboxylic acid was recovered on the permeated liquid side was obtained. This carboxylic acid-containing filtrate was concentrated to 100 mL using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd.), and concentrated sulfuric acid (manufactured by Sigma-Aldrich) was added to adjust the pH to 4.0. 10 mL of this aqueous solution was transferred to a glass separatory funnel (capacity 50 mL), 10 mL of ethyl acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was shaken 30 times. The ethyl acetate phase was collected, and 10 mL of ethyl acetate was further added to the raffinate and the mixture was shaken 30 times to collect the ethyl acetate phase. The same procedure was repeated, and carboxylic acids were extracted using a total of 100 mL of ethyl acetate to obtain a carboxylic acid extract (acetic acid extraction rate 95%, succinic acid extraction rate 73%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and the phases separated extremely quickly within 10 seconds (Figure 1).

[0080] Comparative Example 1 A carboxylic acid extract was obtained in the same manner as in Example 1, except that the carboxylic acid-containing fermentation liquor was not passed through a nanofiltration membrane (acetic acid extraction rate: 70%, succinic acid extraction rate: 55%). In this extraction, an intermediate phase containing solids was generated between the aqueous phase and the ethyl acetate phase, and no phase separation occurred immediately after shaking (Figure 2). Even after leaving the mixture to stand for 12 hours, the interface between the aqueous phase and the ethyl acetate phase was visible but not clear (Figure 2). Since it was necessary to recover the ethyl acetate phase without involving the intermediate phase, the amount of carboxylic acid extract recovered was reduced compared to Example 1.

[0081] Example 2 Except for using methyl isobutyl ketone instead of ethyl acetate as the extraction solvent, a carboxylic acid extract was obtained in the same manner as in Example 1 (acetic acid extraction rate: 85%, succinic acid extraction rate: 60%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the methyl isobutyl ketone phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0082] Comparative Example 2 A carboxylic acid extract was obtained in the same manner as in Example 2, except that the carboxylic acid-containing fermentation liquid was not passed through a nanofiltration membrane (acetic acid extraction rate: 63%, succinic acid extraction rate: 41%). In this extraction, an intermediate phase containing solids was generated between the aqueous phase and the methyl isobutyl ketone phase, and no phase separation occurred immediately after shaking. Even after leaving the mixture to stand for 12 hours or more, the interface between the aqueous phase and the methyl isobutyl ketone phase was visible but not clear. Since it was necessary to recover the methyl isobutyl ketone phase without involving the intermediate phase, the amount of the carboxylic acid extract recovered was reduced compared to Example 2.

[0083] Examples 1 and 2 and Comparative Examples 1 and 2 show that by passing through a nanofiltration membrane, phase separation during extraction becomes clear and rapid, and the carboxylic acid extract that has been phase-separated from the aqueous phase can be recovered.

[0084] Example 3 1 L of the carboxylic acid-containing fermentation liquid prepared in Reference Example 1 was passed through a microfiltration membrane (a porous membrane with a pore size of 0.01 μm or more and less than 1 μm; manufactured by Toray Industries, Inc.), concentrated sulfuric acid (manufactured by Sigma-Aldrich Co., Ltd.) was added to adjust the pH to 4.0, and then passed through an ultrafiltration membrane (molecular weight cutoff of 10,000; manufactured by Toray Industries, Inc.). Thereafter, nanofiltration membrane treatment and extraction were performed in the same manner as in Example 1 to obtain a carboxylic acid extract (acetic acid extraction rate 99%, succinic acid extraction rate 90%). In this extraction, no formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was observed, and phase separation occurred very quickly within 10 seconds.

[0085] Comparative Example 3 The same operation as in Example 3 was carried out except that the nanofiltration membrane treatment was not performed, and a carboxylic acid extract was obtained (acetic acid extraction rate 90%, succinic acid extraction rate 65%). In this extraction, an intermediate phase containing solids was generated between the aqueous phase and the ethyl acetate phase. In addition, it took 10 minutes to visually confirm clear phase separation.

[0086] Example 3 and Comparative Example 3 demonstrated that the effect of the nanofiltration membrane was clear even when the pH of the carboxylic acid-containing fermentation liquor was adjusted before it passed through the ultrafiltration membrane.

[0087] The 3-hydroxyadipic acid-3,6-lactone and α-hydromuconic acid used in Reference Example 20 shown below were produced by the method described in WO 2016 / 068108.

[0088] (Reference Example 20) Preparation of various carboxylic acid-containing fermentation liquids Instead of adding acetic acid and succinic acid in Reference Example 1, itaconic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), adipic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 3-hydroxyadipic acid-3,6-lactone, α-hydromuconic acid, cis,cis-muconic acid (manufactured by Sigma-Aldrich Co., Ltd.), 4-hydroxybenzoic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and L-phenylalanine (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were added to prepare a carboxylic acid-containing fermentation liquid. The concentrations of itaconic acid, adipic acid, 3-hydroxyadipic acid-3,6-lactone, and L-phenylalanine were each 10 g / L. The concentrations of α-hydromuconic acid and cis,cis-muconic acid were each 0.2 g / L. The concentration of 4-hydroxybenzoic acid was 2 g / L.

[0089] (Reference examples 21~41) The carboxylic acid-containing fermentation liquid prepared in Reference Example 20 was passed through a microfiltration membrane (a porous membrane with a pore size of 0.01 μm or more and less than 1 μm; manufactured by Toray Industries, Inc.), and then through an ultrafiltration membrane (molecular weight cutoff of 10,000; manufactured by Toray Industries, Inc.). 1 L of this carboxylic acid-containing fermentation liquid was transferred to a raw water tank and passed through the nanofiltration membrane once under the nanofiltration membrane treatment condition 1. The obtained carboxylic acid-containing filtrate lost its color and was a clear aqueous solution. The carboxylic acid concentration was analyzed by HPLC, and the transmittance was calculated according to the following formula. The calculated transmittance results are shown in Table 3.

[0090] Transmittance (%) = (concentration of compound in permeate) / (concentration of compound in raw water) × 100.

[0091] [Table 3]

[0092] (Reference examples 42~48) 20 mL of the carboxylic acid-containing filtrate prepared in Reference Examples 22, 25, 28, 31, 34, 37, and 40 was transferred to a glass separatory funnel (volume 100 mL), 20 mL of ethyl acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was shaken 30 times. After shaking, the carboxylic acid concentration in the aqueous phase was measured by HPLC, and the extraction rate was calculated according to the following formula. The results are shown in Table 4.

[0093] Extraction rate (%) = (1 - (concentration of compound to be extracted in raffinate) / (concentration of compound to be extracted before extraction)) x 100.

[0094] [Table 4]

[0095] Example 4 An experiment was carried out in the same manner as in Example 1, except that the itaconic acid-containing fermentation liquid prepared in Reference Example 20 was used, to obtain an itaconic acid extract (extraction rate: 45%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0096] Example 5 The experiment was carried out in the same manner as in Example 1, except that the adipic acid-containing fermentation liquid prepared in Reference Example 20 was used, and an adipic acid extract was obtained (extraction rate 90%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred very quickly within 10 seconds.

[0097] Example 6 The experiment was carried out in the same manner as in Example 1, except that the 3-hydroxyadipic acid-3,6-lactone-containing fermentation liquid prepared in Reference Example 20 was used, and a 3-hydroxyadipic acid-3,6-lactone extract was obtained (extraction rate 99%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0098] Example 7 An experiment was carried out in the same manner as in Example 1, except that the α-hydromuconic acid-containing fermentation liquid prepared in Reference Example 20 was used, and an α-hydromuconic acid extract was obtained (extraction rate 99%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0099] Example 8 The experiment was carried out in the same manner as in Example 1, except that the cis,cis-muconic acid-containing fermentation liquid prepared in Reference Example 20 was used, and a cis,cis-muconic acid extract was obtained (extraction rate: 85%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0100] Example 9 The experiment was carried out in the same manner as in Example 1, except that the 4-hydroxybenzoic acid-containing fermentation liquid prepared in Reference Example 20 was used, and a 4-hydroxybenzoic acid extract was obtained (extraction rate 99%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0101] Example 10 An experiment was carried out in the same manner as in Example 1, except that the L-phenylalanine-containing fermentation broth prepared in Reference Example 20 was used, to obtain an L-phenylalanine extract (extraction rate 99%). In this extraction, the formation of an intermediate phase containing solids between the aqueous phase and the ethyl acetate phase was hardly observed, and phase separation occurred extremely quickly within 10 seconds.

[0102] Examples 1 to 10 demonstrate that the present invention can be used to recover various carboxylic acids.

Claims

1. A method for producing a carboxylic acid, comprising the following steps (A) and (B): (A) A step of filtering a fermentation liquid containing a carboxylic acid having a molecular weight of 200 or less through a nanofiltration membrane to obtain a filtrate containing a carboxylic acid from the permeation side. (B) A step of extracting carboxylic acids from the carboxylic acid-containing filtrate obtained in step (A) with an extraction solvent that undergoes phase separation from the filtrate, and recovering the carboxylic acid extract that has separated from the aqueous phase.

2. The method according to claim 1, wherein the carboxylic acid contained in the carboxylic acid-containing filtrate is mainly composed of carboxylic acid not in a carboxylate state.

3. The method according to claim 1 or 2, wherein the pH of the carboxylic acid-containing fermentation liquid and / or the carboxylic acid-containing filtrate is adjusted to 4.5 or less.

4. The method according to any one of claims 1 to 3, further comprising removing insoluble matter before passing the carboxylic acid-containing fermentation liquid through a nanofiltration membrane in step (A).

5. 5. The method according to claim 4, wherein the step of removing the insoluble material is a step of passing the carboxylic acid-containing fermentation liquor through a microfiltration membrane.

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