JPH1036310A - Organic acid production method - Google Patents

Abstract

(57) Abstract: An organic acid solution having a higher concentration than the saturated solubility (molarity) of an organic acid salt is produced by bipolar membrane electrodialysis. An organic acid salt solution is supplied to an acid chamber of an electrodialysis apparatus having an acid chamber and a base chamber formed by alternately arranging bipolar membranes and cation exchange membranes between electrodes to perform electrodialysis. Then, in a method for producing an organic acid that generates an organic acid in the acid chamber, a solid organic acid salt is added and dissolved in an organic acid salt solution existing in the acid chamber, and electrodialysis is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for producing an organic acid from an organic acid salt by electrodialysis using a bipolar membrane. Specifically, in a method for producing an organic acid in which an organic acid salt solution is supplied to an acid chamber of a bipolar membrane electrodialysis apparatus to perform an electrodialysis to generate an organic acid in the acid chamber, an organic acid existing in the acid chamber is used. This is a method for producing an organic acid, which is capable of producing a high-concentration organic acid in an acid chamber by additionally dissolving a solid organic acid salt in a salt solution and performing electrodialysis.

[0002]

2. Description of the Related Art Conventionally, methods for obtaining an organic acid from an organic acid salt include a method in which an aqueous solution of an organic acid salt is brought into contact with a hydrogen ion type cation exchange resin, and a method in which an organic acid salt is once converted into an ester and then converted into an ester. A method of obtaining an organic acid by hydrolysis after separation is known.

[0003] Japanese Patent Publication No. 33-2023 discloses a two-chamber electrodialysis method using a bipolar membrane and an anion exchange membrane or a cation exchange membrane to convert an acid and alkali solution from a salt solution comprising a weak acid or a weak base. There has been proposed a method of recovering the water.

[0004]

However, the method of using a cation exchange resin of the hydrogen ion type and the method of converting an organic acid salt into an ester are complicated in equipment for regenerating an ion exchange resin and equipment for subsequent hydrolysis. In addition to requiring a complicated process, it requires expensive equipment.

When the two-chamber electrodialysis method is applied to the production of the organic acid, the concentration of the organic acid due to the transfer of electroosmotic water in an acid chamber composed of a bipolar membrane and a cation exchange membrane is considered. Although there is an increase in the concentration of the obtained organic acid, the concentration of the obtained organic acid depends on the concentration of the organic acid salt present in the acid chamber. It was difficult to get.

[0006]

Means for Solving the Problems The present inventors have solved the above-mentioned problems in the method for producing an organic acid using an electrodialyzer using a bipolar membrane and a cation exchange membrane, and have solved the problem of the saturation of an organic acid salt. Intensive research was conducted to develop a method for producing a highly concentrated organic acid solution having a solubility (molar concentration) or higher.
As a result, in particular, when the solubility of the generated organic acid in the solvent is higher than the solubility of the organic acid salt, the solid organic acid salt is additionally dissolved in the organic acid salt solution present in the acid chamber, and the organic acid salt is substantially dissolved. The present inventors have found that it is possible to increase the concentration of an organic acid obtained from an acid chamber by performing electrodialysis while supplementing only an acid salt, and have completed the present invention.

In the present invention, the electrodes of the electrodialysis device are
Known ones can be used without any limitation. That is, platinum, titanium / platinum, carbon, nickel, ruthenium / titanium, iridium / titanium and the like are often used as the anode. As the cathode, iron, nickel, platinum,
Titanium / platinum, carbon, stainless steel, etc. are often used. In addition, a known structure is employed without particular limitation for the structure of the electrode. Examples of a general structure include a mesh shape and a lattice shape.

Further, in the present invention, the bipolar membrane of the electrodialysis apparatus is not particularly limited, and a conventionally known bipolar membrane, that is, a known bipolar membrane having a structure in which a cation exchange membrane and an anion exchange membrane are bonded to each other. Can be used.

[0009] Such a bipolar film can be manufactured by various known methods. For example, a method of laminating a cation exchange membrane and an anion exchange membrane with a mixture of polyethyleneimine-epichlorohydrin and bonding them together (Japanese Patent Publication No. 32-3962), bonding the cation exchange membrane and the anion exchange membrane with an ion exchange adhesive Method (Japanese Patent Publication No. 34-
No. 3961), a method in which a cation exchange membrane and an anion exchange membrane are coated with a fine powder of an ion exchange resin, or a paste-like mixture of an anion or cation exchange resin and a thermoplastic material, and pressed (Japanese Patent Publication No. 35-14531). A method of applying a paste-like substance comprising vinylpyridine and an epoxy compound to the surface of a cation exchange membrane and irradiating it with a paste (Japanese Patent Publication No. 38-16633); Of ion-exchange radiation and cross-linking after adhering an allylamine with a polymer electrolyte (Japanese Patent Publication No. 51-4113), a dispersion system of an ion exchange resin having an opposite charge on the surface of an ion exchange membrane, and a base polymer (Japanese Patent Application Laid-Open No. 53-37190), a sheet formed by impregnating and polymerizing a polyethylene film with styrene and divinylbenzene. The put scissors in a stainless steel frame,
After one side is sulfonated, the sheet is removed and the remaining part is chlormethylated and then aminated (US Pat. No. 3,562,139), or a specific metal ion is applied to the surface of the anion-cation exchange membrane. A method of pressing both ion-exchange membranes together (Electrochemical
Actor 31, pp. 1175-1176 (1986)).

[0010] The base material of the bipolar membrane in the present invention depends on the cation exchange membrane and the anion exchange membrane to be joined.
A styrene-divinylbenzene copolymer film, net, knit, woven fabric, non-woven fabric, or the like is used.

The cation exchange groups of the cation exchange membrane constituting the bipolar membrane are not particularly limited, and known cation exchange groups such as sulfonic acid groups and carboxylic acid groups can be used. In particular, a sulfonic acid group in which the exchange group is dissociated even under acidic conditions is desirable from the application of the bipolar membrane. Further, the anion exchange group of the anion exchange membrane constituting the bipolar membrane is not particularly limited either, and known anion exchange groups such as ammonium base, pyridinium base, primary amino group, secondary amino group, and tertiary amino group Ion exchange groups such as groups can be used. Among them, an ammonium base whose exchange group is dissociated even under basic conditions is desirable.

Further, in the present invention, the cation exchange membrane of the electrodialysis apparatus is not particularly limited, and a known cation exchange membrane can be used. For example, a cation exchange membrane in which sulfonic acid groups, carboxylic acid groups, and a plurality of these ion exchange groups are mixed can be used. In addition, the cation exchange membrane can be any of a polymerization type, a condensation type, a uniform type, and a non-uniform type, with or without a reinforcing core material, a hydrocarbon type, a fluorine type, and a material.
Any type and type of cation exchange membrane derived from the production method may be used.

The preferred cation exchange membrane of the present invention is particularly preferably a base-resistant cation exchange membrane because of its contact with the generated base.

In the present invention, the electrodialysis device is constituted by alternately arranging bipolar membranes and cation exchange membranes between electrodes to form an acid chamber and a base chamber.

FIG. 1 shows a schematic diagram of a typical embodiment of the electrodialysis apparatus used in the present invention.

That is, in FIG. 1, the electrodialysis apparatus has a cation exchange membrane (C) 1 and a bipolar membrane (B) 2 as membranes.
Are alternately arranged to form two chambers, an acid chamber and a base chamber. Here, the chamber between the anion exchanger side of the bipolar membrane (B) and the cation exchange membrane (C) is the base chamber 12, and the chamber between the cation exchanger side of the bipolar membrane (B) and the cation exchange membrane (C). Is an acid chamber 11. A typical configuration of the electrodes (anode 15 and cathode 16) and the film is an anode- (C
-B) _n- C-cathode (where n is the number of repetitions of the arrangement of the bipolar membrane and the cation exchange membrane), and n is generally suitably 1 to 100.

As the structure of the electrodialyzer, a known structure is employed without any particular limitation. The most preferred structure is a so-called filter press type structure in which bipolar membranes and cation exchange membranes are alternately arranged via a chamber frame having a cutout portion at the center for forming each chamber, and tightened from both ends. .
Each chamber frame is provided with a liquid supply port and a liquid discharge port, and each liquid supply port and the liquid discharge port are connected to a main pipe via a branch pipe as necessary. In addition, it is common to provide a spacer having a flow distribution function for keeping the thickness of the chamber frame uniform and making the flow of the supplied liquid uniform within the chamber frame.

As the organic acid to be used in the present invention, an organic acid having a saturated solubility (molar concentration) of an organic acid salt smaller than that of the organic acid is particularly preferably used.

Examples of such organic acids include formic acid, acetic acid, citric acid, lactic acid, gluconic acid, maleic acid, chloroacetic acid, oxalic acid, glycolic acid, tartaric acid and the like.

In the present invention, the organic acid salt used as a raw material for obtaining the above-mentioned organic acid includes sodium, potassium and lithium as cations, ammonia, primary and
Those having secondary or tertiary amine quaternary ammonium and the like are preferred. Specific examples of organic acid salts include sodium formate, sodium acetate, sodium lactate, sodium citrate, sodium gluconate, sodium glycolate, ammonium formate, ammonium acetate, ammonium lactate, ammonium citrate, ammonium gluconate, and glycol. Ammonium, potassium tartrate,
Lithium formate and the like.

The solvent of the solution of the organic acid salt is basically preferably water. However, a solvent containing an organic solvent may be used as long as a current can flow when the salt of the organic acid is dissolved. You may. Specifically, a solvent containing a polar solvent such as methanol, ethanol, dimethylformamide and the like in addition to the above-mentioned water is used.

In the present invention, the electrodialysis method uses the above-mentioned electrodialysis apparatus, as shown in FIG. 2, to provide an external tank (acid chamber solution tank 22, A method of providing a base chamber solution tank 22) and performing electrodialysis while circulating a liquid between each chamber and an external tank is suitably adopted.

In the present invention, an electrodialysis is performed by supplying an organic acid salt solution to the acid chamber of the electrodialyzer 21 in advance, and supplying the generated base solution to the base chamber. When the electrodialysis is continued, the organic acid salt is converted into an organic acid in the acid chamber, and a base is generated by the cation of the organic acid salt in the base chamber.

The feature of the present invention is that the organic acid salt in the organic acid salt solution existing in the acid chamber is converted to an organic acid to some extent, and the solid organic acid salt is additionally dissolved in the organic acid salt solution to perform electrodialysis. Is to do. That is, by such an operation, the organic acid salt in the organic acid salt solution is replenished and successively converted into an organic acid by electrodialysis, so that the concentration of the organic acid can be increased.

The supply of the solid organic acid salt may be performed continuously or intermittently. Further, if necessary, it may be performed only once during electrodialysis. The solid organic acid may be added in a dry state such as a powder or a granule, or in a slurry suspended in a solvent.

After the organic acid has a high concentration in the acid chamber, the supply of the organic acid is stopped, the electrodialysis is continued, and the remaining organic acid is consumed to obtain the organic acid solution. It is preferred to reduce the proportion of the organic acid salt therein.

The mode of additionally dissolving the solid organic acid salt in the organic acid salt solution existing in the acid chamber is not particularly limited,
It is preferable that the solid organic acid salt is additionally dissolved in the acid chamber solution liquid tank 22 provided in the middle of the acid solution circulation line 25 provided for circulating the organic acid salt solution existing in the acid chamber. That is, according to this aspect, compared to the method of directly charging the solid organic acid salt into the acid chamber, the phenomenon that the solid of the organic acid salt adheres to the inner wall of the acid chamber of the electrodialysis apparatus and the electrodialysis ability is reduced. There is no occurrence and stable operation can be performed.

As a specific dissolving means in the acid chamber solution tank, a solid organic acid salt is added into the tank,
A method of dissolving by stirring may be used. Also,
A method in which a packed layer filled with a solid organic acid salt is provided in the middle of the circulation line, and an organic acid salt solution is allowed to pass through the packed layer can also be suitably adopted.

According to the above-mentioned method, it is preferable to dissolve the solid organic acid salt to near the saturated dissolution amount in the solution.

In the above embodiment, more preferably, a filter 23 is installed at the inlet of the electrodialysis tank as shown in FIG. 1 so that no solid matter enters the electrodialysis tank.

The supply of the solid organic acid salt may be continuous or intermittent.

In the present invention, the temperature of various liquids during electrodialysis is usually in the range of 5 to 70 ° C., preferably 20 to 50 ° C. The current density is not particularly limited,
Generally, 1 to 30 A / dm ² , preferably ^{2 to} 20 A / dm ²
/ Dm ² . When it is attempted to completely convert an organic acid salt into an organic acid, it becomes difficult for an electric current to flow. Therefore, when the concentration of the organic acid increases to some extent, for example, reaches a conversion rate of about 95%, it is desirable to stop the electrodialysis and collect the solution.

The organic acid solution containing the recovered organic acid salt may be separated, if necessary, from the organic acid and the remaining organic acid salt. Such separations, in the case of organic acids and organic acid salts,
Generally, a distillation method utilizing a difference in boiling points and a method of converting the remaining organic acid salt into an organic acid by contact with a hydrogen ion type cation exchange resin are preferably employed.

[0034]

According to the present invention, it is possible to produce an organic acid solution having a concentration higher than the saturation solubility (molar concentration) of an organic acid salt by bipolar membrane electrodialysis, which is industrially extremely advantageous. It can be said that the method.

[0035]

EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which should not be construed as limiting the scope of the present invention. Example 1 As shown in FIG. 1, a bipolar membrane electrodialysis apparatus comprises a cation exchange membrane (manufactured by Tokuyama Corporation,
Product name: Neosepta CMB) and bipolar membrane (Neosceptor BP-1) are 6 and 5 respectively, and the effective membrane area of the cation exchange membrane and the bipolar membrane is 1
dm ² / sheets, the total effective membrane area are respectively 6,5dm ²⁾ arranged, a base chamber, a filter press type bipolar membrane electrodialysis device acid chamber are formed using.

Further, as shown in FIG.
A sodium formate aqueous solution having a concentration shown in Table 1 was supplied to the acid chamber No. 1 and circulated through the acid chamber solution tank 22 and the filter 23 by the circulation line 25. During the electrodialysis, 8 mol of solid sodium formate was charged into the acid chamber solution tank 22 and dissolved by stirring with a stirrer. On the other hand, a caustic soda aqueous solution having a concentration shown in Table 1 was circulated through the base chamber solution tank 24 in the base chamber.

The operating conditions were a constant voltage operation of 2 volts / cell, an average current of 8 A / dm ² during this period, and an energization time of 12 hours 1
It was 0 minutes. A concentration of 11.8 mol / l formic acid was obtained.
The temperature at the start of the operation was 20 ° C. At this time, the saturated solubility (molarity) of sodium formate was 9 mol / l.

Table 1 shows the composition of each chamber at the end of the operation.

[0039]

[Table 1]

COMPARATIVE EXAMPLE 1 As a comparative example, the results obtained when sodium formate was not added during energization are shown in Table 2 as a comparative example. The operating conditions were a constant voltage operation of 2 volts / cell, the average current during this period was 8 A / dm ² , and the energization time was 7 hours and 26 minutes.

The concentration of formic acid obtained remained at 6.8 mol / l.

[0042]

[Table 2]

Example 2 Table 3 shows the results when sodium acetate was converted to acetic acid in the same manner as in Example 1. The operating conditions were a constant voltage operation of 2 volts / cell, an average current during this period of 8 A / dm ² , and an energization time of 12 hours. Acetic acid having a concentration of 11.9 mol / l was obtained.

The temperature at the start of the operation was 20 ° C. At this time, the saturated solubility (molar concentration) of sodium acetate was 9.3 mol / l.

[0045]

[Table 3]

COMPARATIVE EXAMPLE 2 Table 4 shows the result when sodium acetate was not added during energization as a comparative example in comparison with Example 2 described above. The operating condition was a constant voltage operation of 2 volts / cell, during which the average current was 8
A / dm ² , and the energizing time was 7 hours and 15 minutes. The concentration of acetic acid obtained remained at 6.9 mol / l.

[0047]

[Table 4]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a two-chamber bipolar membrane electrodialysis apparatus.

FIG. 2 is a schematic diagram illustrating an exemplary embodiment for performing the method of the present invention.

[Explanation of symbols]

 1 Cation Exchange Membrane (C) 2 Bipolar Membrane (B) 11 Acid Chamber 12 Base Chamber 13 Anode Chamber 14 Cathode Chamber 15 Anode 16 Cathode 21 Electrodialyzer 22 Acid Chamber Solution Tank 23 Filter 24 Base Chamber Solution Tank 25 Acid Solution Circulation line

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[Procedure amendment]

[Submission date] July 30, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

Means for Solving the Problems The present inventors have solved the above-mentioned problems in the method for producing an organic acid using an electrodialyzer using a bipolar membrane and a cation exchange membrane, and have solved the problem of the saturation of an organic acid salt. Intensive research was conducted to develop a method for producing a highly concentrated organic acid solution having a solubility (molar concentration) or higher.
As a result, in particular, when the solubility of the generated organic acid in the solvent is higher than the solubility of the organic acid salt , the solid organic acid salt is additionally dissolved in the organic acid salt solution existing in the acid chamber inside or outside the acid chamber. Thus, it was found that by performing electrodialysis while substantially supplementing only the organic acid salt, it was possible to increase the concentration of the organic acid obtained from the acid chamber,
The present invention has been completed.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

The feature of the present invention is that the organic acid salt in the organic acid salt solution present in the acid chamber is converted to an organic acid to some extent, and the solid organic acid salt is additionally dissolved in the organic acid salt solution. Electrodialysis. That is, by such an operation, the organic acid salt in the organic acid salt solution is replenished and successively converted into an organic acid by electrodialysis, so that the concentration of the organic acid can be increased.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

The supply of the solid organic acid salt may be performed continuously or intermittently. In some cases
It is, may be performed only once during electrodialysis. The solid organic acid may be added in a dry state such as a powder or a granule, or in a slurry suspended in a solvent.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

The mode of additionally dissolving the solid organic acid salt in the organic acid salt solution existing in the acid chamber is not particularly limited,
Add dissolve the solid organic acid salt in the acid solution acid chamber <br/> soluble Ekita tank 22 provided in the middle of the circulation line 25 which is provided in order to circulate the organic acid salt solution present in the acid chamber Is preferred. That is, according to this aspect, compared to the method of directly charging the solid organic acid salt into the acid chamber, the phenomenon that the solid of the organic acid salt adheres to the inner wall of the acid chamber of the electrodialysis apparatus and the electrodialysis ability is reduced. There is no occurrence and stable operation can be performed.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Deleted

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C07C 53/16 2115-4H C07C 53/16 55/06 2115-4H 55/06 57/145 2115- 4H 57/145 59/06 2115-4H 59/06 59/08 2115-4H 59/08 59/105 2115-4H 59/105 59/255 2115-4H 59/255 59/265 2115-4H 59/265

Claims (1)

[Claims] An electrodialysis method comprising supplying an organic acid salt solution to an acid chamber of an electrodialysis apparatus having an acid chamber and a base chamber formed by alternately arranging bipolar membranes and cation exchange membranes between electrodes. A method for producing an organic acid in the acid chamber, wherein a solid organic acid salt is additionally dissolved in an organic acid salt solution present in the acid chamber and electrodialysis is performed. A method for producing an organic acid.