Method for electrochemically separating organic acids and bases

Abstract

The application discloses a method for electrochemically separating organic acid and alkali, wherein an organic acid salt solution to be separated is introduced into a central chamber of an assembled porous solid electrolyte reactor, a cathode reactant is introduced into a cathode chamber, an anode reactant is introduced into an anode chamber, and electrolysis is performed, so that finally the organic acid is obtained in the central chamber, and the alkali is recovered in the cathode, and the separation of the organic acid and the alkali is completed. The application has universality for obtaining organic acids by separating various organic acid salts, is green in production process, low in reaction energy consumption, and simple in separation steps.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochemistry, and particularly relates to a method for electrochemically separating organic acids and bases. BACKGROUND

[0002] Organic acids play a vital role in industrial production and are widely used in pharmaceutical, food and daily chemical industries. The traditional production process of organic acids mainly includes fermentation method and chemical synthesis method. The fermentation method is well-known for its mild production process and rich renewable raw material resources, and the chemical synthesis method is characterized by its clear purpose and strict production conditions. However, whether it is the fermentation method or the chemical synthesis method, the separation and purification of the product are involved in the production process.

[0003] The acidic substances produced in the process of producing organic acids by fermentation method can cause the overall pH value in the fermentation tank to decrease, and the corresponding basic substances need to be added to neutralize the excessive acid. This results in the need for acidification to obtain organic acids, involving a series of process operations such as organic acid separation and purification. This method not only requires a large amount of manpower and material resources, but also consumes a large amount of acid and alkali reagents and generates a large amount of waste liquid and waste residue, causing environmental pollution. In addition, in recent years, more and more renewable electric energy driven catalytic conversion processes have been developed to produce organic acids to realize product upgrading, such as formic acid, acetic acid, 2,5-furan dicarboxylic acid, lactic acid, succinic acid, etc. In the literature of Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel published by the team of Duan Haohong, a single-pass flow reactor was used to realize the production of 2,5-furan dicarboxylic acid on a kilogram scale; In the article of Strengthening the synergy between oxygen vacancies in electrocatalysts for efficient glycerol electrooxidation published by the team of Yao Xiangdong, a modified copper-cobalt oxide nanosheet catalyst was used to realize the production of formate by glycerol oxidation with a selectivity close to 100% and a faraday efficiency of about 99%; In the work of Selective and efficient CO2 electroreduction to formate on copper electrodes modified by cationic gemini surfactants by the team of Han Buxing, a new type of cationic gemini surfactant was designed and used for surface modification of the catalyst, and the modified electrode based on copper electrode obtained a formate selectivity of 96%, and in addition, in the system of flow cell, the catalyst modified based on bismuth oxide substrate realized a formate faraday efficiency of 91% and a current density of 510 mA cm -2 However, due to the intrinsic kinetic characteristics, most of the current electrocatalytic organic oxidation and carbon dioxide reduction reactions are basically carried out in alkaline electrolyte system, and the final products are all organic acid salts, which requires additional post-processing steps for separation, causing economic loss and energy consumption increase.

[0004] The current separation of organic acids usually relies on filtration, crystallization and distillation and other traditional chemical operations, although these operations can realize separation and purification, but at the same time, a large amount of pollutants are inevitably produced, and high energy consumption is accompanied, which makes them difficult to meet the urgent demand of modern society for "green production". Therefore, how to use environmentally friendly and effective means to effectively separate organic acid salts is an important problem that modern industrial production needs to face.

[0005] Among the newly developed technical means, membrane separation technology is widely studied. Bipolar membrane electrodialysis can be used as an effective means for recovering and separating organic acid salts. The device is formed by alternately arranging bipolar membranes, anion exchange membranes and cation exchange membranes. Under the action of a direct current electric field, the organic acid root ions in the organic acid salt solution introduced into the salt chamber combine with the protons generated on the positive membrane side of the bipolar membrane to form an acid solution through the anion exchange membrane, and at the same time, the alkali metal cations can combine with the hydroxyl groups generated on the negative membrane side of the bipolar membrane to form an alkali solution through the cation exchange membrane, realizing the separation of organic acid and alkali. Researchers have realized the separation of organic acid salts by optimizing the reaction conditions and designing innovative membrane systems, but in this bipolar membrane electrodialysis device, the activity and migration of organic acid root ions are low, and the resistance of organic acid root ions penetrating through the membrane is large, which will lead to high energy consumption of the bipolar membrane electrodialysis process. In addition, the low strength of the bipolar membrane and the high voltage of the water dissociation also increase the energy consumption in the reaction process. How to use a more green, energy-saving and consumption-reducing separation method to realize the effective separation of organic acid salts has become a difficult problem to solve. SUMMARY

[0006] The present application is proposed to overcome the shortcomings of high energy consumption in the separation process of organic acid salts in the prior art, and the purpose is to provide a method for electrochemically separating organic acid and alkali.

[0007] The present application is realized by the following technical scheme:

[0008] A method for electrochemically separating organic acid and alkali, comprising the following steps:

[0009] (I) Assembling a porous solid electrolyte reactor

[0010] (i) selecting a suitable cathode reaction and anode reaction, selecting a suitable cathode catalyst, anode catalyst, cathode reactant and anode reactant according to the cathode reaction and anode reaction, and preparing a cathode electrode and an anode electrode;

[0011] The cathode reaction is hydrogen production by electrolysis of water or oxygen reduction reaction;

[0012] The anode reaction is hydrogen oxidation or oxygen production by electrolysis of water;

[0013] When the cathode reaction is water electrolysis to produce hydrogen, the cathode catalyst is any one of ruthenium oxide or platinum-carbon; when the anode reaction is oxygen reduction, the cathode catalyst is any one of carbon tube or carbon black;

[0014] When the anode reaction is hydrogen oxidation, the anode catalyst is any one of platinum-carbon, ruthenium oxide or nickel hydroxide; when the anode reaction is water electrolysis to produce oxygen, the anode catalyst is any one of iridium oxide, ruthenium-iridium oxide, nickel-molybdenum alloy, nickel hydroxide, nickel-iron hydrotalcite or nickel-cobalt oxyhydroxide;

[0015] When the cathode reaction is water electrolysis to produce hydrogen, the cathode reactant is deionized water;

[0016] When the cathode reaction is oxygen reduction, the cathode reactant is a mixture of oxygen and deionized water;

[0017] When the anode reaction is hydrogen oxidation, the anode reactant is hydrogen;

[0018] When the anode reaction is water electrolysis to produce oxygen, the anode reactant is deionized water;

[0019] The cathode electrode is composed of a conductive substrate loaded with a cathode catalyst;

[0020] The anode electrode is composed of a conductive substrate loaded with an anode catalyst;

[0021] The conductive substrate is any one of carbon paper, titanium felt or carbon cloth;

[0022] When the cathode reaction or the anode reaction involves a gaseous reactant, the conductive substrate of the anode electrode or the cathode electrode is subjected to hydrophobic treatment;

[0023] (ii) assembling the cathode electrode, the anode electrode, the proton exchange membrane, the cation exchange membrane, the solid-state electrolyte and a gasket of corresponding size into a porous solid-state electrolysis reactor;

[0024] The proton exchange membrane is any one of Nafion 115 or Nafion 117;

[0025] The cation exchange membrane is any one of Nafion-N2100TX, Nafion 115, Nafion 117 or SIN-D117 membrane;

[0026] The solid-state electrolyte is a high-conductivity ion exchange resin, which is any one of IR120 or Dowex 50W X8, and the solid-state electrolyte layer supports the ion exchange membrane and provides ion transport channels, thereby reducing the resistance; ​

[0027] The reaction principle of the porous solid-state electrolyte reactor is as shown in Figure 1 The porous solid-state electrolyte reactor can adopt the structure of the patent "2024223389615-A large-area solid-state electrolyte reactor" or other commercially available solid-state electrolyte reactors.

[0028] (II) introducing the organic acid salt solution to be separated into the central chamber of the porous solid-state electrolyte reactor, introducing the cathode reactant into the cathode chamber, introducing the anode reactant into the anode chamber, and performing electrolysis to obtain the organic acid in the central chamber and the base recovered in the cathode, thereby completing the separation of the organic acid and the base.

[0029] The organic acid salt is any one of formate, acetate, lactate, succinate, glycolate, adipate, gluconate, or saccharate; the organic acid salt solution in the central chamber adopts one-way or circulating liquid feeding, and the flow rate of the organic acid salt solution introduced into the central chamber is 0.01 mL min -1 ~ 20 mL min -1 ;

[0030] When the cathode reactant is deionized water, the cathode reactant deionized water in the cathode chamber adopts one-way or circulating liquid feeding, and the flow rate of the deionized water introduced is 0.1 mL min -1 ~ 10 mL min -1 ;

[0031] When the cathode reactant is a mixture of oxygen and deionized water, the cathode reactant mixture of oxygen and deionized water in the cathode chamber adopts one-way liquid feeding, the flow rate of the oxygen introduced is 20 sccm ~ 100 sccm, and the flow rate of the deionized water introduced is 0.01 mL min -1 ~ 1 mL min -1 ;

[0032] When the anode reactant is hydrogen, the anode reactant hydrogen in the anode chamber adopts one-way gas feeding, and the flow rate of the hydrogen introduced is 20 sccm ~ 100 sccm;

[0033] When the anode reactant is deionized water, the anode reactant deionized water in the anode chamber adopts circulating liquid feeding, and the flow rate of the deionized water introduced is 0.1 mL min -1 ~ 10 mL min -1 ;

[0034] The current density of the electrolysis ranges from 10 mA·cm -2 ~ 1000 mA·cm -2 ;

[0035] The time of the electrolysis ends when the migration of alkali metal cations in the intermediate chamber to the cathode is completed;

[0036] When the cathode reactant in the cathode chamber adopts a one-way liquid inlet mode, i.e., the cathode liquid flows into the cathode chamber from the inlet and flows out from the outlet, the reaction endpoint can be indicated by the pH of the reaction liquid at the outlet of the cathode chamber, and when the cathode liquid becomes neutral, the migration of alkali metal cations is completed, and the reaction ends.

[0037] The cathode reactant in the cathode chamber adopts a circulating liquid inlet mode, i.e., the storage container of the cathode liquid is connected to the inlet and outlet of the cathode through a pipeline and a circulating pump, and the reaction can end at 200% to 400% of the electric quantity, and the migration effect of alkali metal cations can be detected;

[0038] The organic acid salt solution in the central chamber adopts a circulating liquid inlet mode, i.e., the storage container of the organic acid salt solution is connected to the inlet and outlet of the central chamber through a pipeline and a pump; higher separation efficiency of the organic acid and the base can be achieved;

[0039] The flow rates of the anode, the cathode and the intermediate chamber affect the reaction process, and matching appropriate flow rates can better contact the membrane and the catalyst, thereby improving the reaction performance.

[0040] The beneficial effects of the present application are:

[0041] The present application provides a method for separating organic acid and recovering base by using green and energy-saving electrochemical means, using a porous solid electrolyte reactor, under the action of an applied electric field, an oxidation reaction occurs at the anode to generate protons, which migrate across a proton exchange membrane to the central chamber to combine with organic acid radicals to form organic acid; at the same time, the alkali metal cations in the organic acid salt raw material migrate across a cation exchange membrane to the cathode chamber under the action of an electric field to combine with the hydroxide formed by the cathodic reduction to form a base. Figure 1 Compared with the traditional bipolar membrane electrodialysis device for separating organic acid, Figure 2 The porous solid electrolyte in the central chamber of the porous solid electrolyte reactor has the functions of supporting the ion exchange membrane and providing an ion transport channel, thereby reducing the electrical resistance, and thus the method has the advantages of high separation efficiency and low energy consumption; the base solution or alkaline hydrogen peroxide solution can be obtained through reduction reaction at the cathode side, wherein the base solution can be used as a capture liquid for carbon dioxide capture, and the alkaline hydrogen peroxide solution can be used as a reaction liquid for organic oxidation reaction to obtain other high-value-added products, such as formic acid prepared by glucose oxidation.

[0042] The present application can be widely applied to separating organic acid from organic acid salt produced by carbon dioxide electro-reduction, organic matter electro-oxidation, biological fermentation, etc., and recovering base, and provides a new idea and technical support for the separation of electro-catalytic organic acid and green production, and is expected to further achieve the development goal of energy saving and consumption reduction. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is the reaction principle diagram of separating organic acid by traditional bipolar membrane electrodialysis device;

[0044] Figure 2 is the reaction principle diagram of separating organic acid by porous solid electrolyte reactor of the present application, wherein light gray dots represent protons and dark gray dots represent alkali metal cations;

[0045] Figure 3 is the test result of the porous solid electrolyte reactor assembled in Example 1 of the present application under a current of 100 mA cm -2 -2; a is the percentage of the central chamber and the cross distribution of formate ions of anode and cathode; b is the pH change of the central chamber and the cathode chamber;

[0046] Figure 4 is the test result of the porous solid electrolyte reactor in Example 2 of the present application under a current of 100 mA cm -2 -2; a is the voltage change diagram over time during the reaction process, and b is the percentage of acetic acid content in the central chamber, i.e. the separation efficiency.

[0047] For those skilled in the art, other related drawings can be obtained according to the above drawings without creative labor. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application will be further described below in combination with the drawings of the specification and through specific embodiments.

[0049] Example 1

[0050] Separation of sodium formate solution by porous solid electrolyte reactor using cathode oxygen reduction coupled with anode water electrolysis reaction:

[0051] a: BP2000 is sprayed on hydrophobic carbon paper as cathode electrode, and hydrogen peroxide is prepared by oxygen reduction, the loading amount of BP2000 is 0.8 mg·cm -2 -2; iridium oxide is sprayed on carbon paper as anode to produce oxygen by water electrolysis reaction, the loading amount of iridium oxide is 1.2 mg·cm -2 ; IR120 as solid electrolyte; Nafion 117 as proton exchange membrane and SIN-D117 as cation exchange membrane to assemble the porous solid electrolyte reactor; the central chamber is circulated to pass sodium formate solution, the anode reaction chamber is circulated to pass deionized water, and the cathode reaction chamber is circulated to pass oxygen mixed with water for electrolysis;

[0052] b: First, the catalyst was activated using a voltammetric test, and then at 100 mA·cm -2 The reaction was carried out under the following conditions: 100 mL of 0.5 M sodium formate was introduced into the central chamber via a circulating inlet at a flow rate of 0.3 mL / min. -1 The oxygen flow rate in the cathode reaction chamber is 30 sccm, and the deionized water flow rate in the cathode reaction chamber is 1 mL min. -1 The liquid inlet method is unidirectional; the anolyte chamber is circulated with deionized water in a circulating mode, with a flow rate set to 3 mL / min. -1 .

[0053] c: Electrolysis for 8 hours. During the reaction, samples were taken every hour from the central chamber and the anode and cathode chambers to test the sodium ion concentration and formate cross-contamination. The pH of the liquid flowing out of the central chamber and cathode chamber was tested. The pH in the central chamber decreased to 2.4, while the pH in the cathode chamber increased to 12.3. Formate cross-contamination was not significant. Sampling tests revealed that 94.7% of the formate was distributed in the central chamber. The results are as follows... Figure 3 .

[0054] d: Glucose was oxidized directly using alkaline hydrogen peroxide from the cathode outlet to obtain formic acid as the main product, achieving a formic acid selectivity of 82.3%.

[0055] Example 2

[0056] A porous solid electrolyte reactor is used to separate potassium acetate solution by coupling a cathode electrolysis of water to produce hydrogen with an anode hydrogen oxidation reaction.

[0057] a: Platinum-carbon was sprayed onto hydrophilic carbon paper as the cathode electrode, and a hydrogen production reaction by water electrolysis occurred with a loading of 1.5 mg·cm⁻¹. -2 Hydrophobic carbon paper coated with platinum carbon was used as the anode, and a hydrogen oxidation reaction was carried out with a loading of 1.5 mg·cm³. -2 ; IR120 was used as the solid electrolyte; Nafion 117 was used as the proton exchange membrane and cation exchange membrane, and a porous solid electrolyte reactor was assembled. A 0.5M potassium acetate solution was circulated into the central chamber, hydrogen gas was introduced into the anode, and circulating water was introduced into the cathode for electrolysis.

[0058] b: First, the catalyst was activated using a voltammetric test, and then at 10, 25, 50, 100, and 200 mA cm⁻¹. -2 At a current density of 100 mA cm⁻¹, potassium acetate was introduced into the intermediate chamber at twice the theoretical flow rate for testing. -2 At that time, the potassium ion transport efficiency can reach 95.27%;

[0059] c: at 100mA·cm -2The reaction was carried out under the specified current conditions, wherein 50 mL of 0.5 M potassium acetate solution was circulated into the central chamber at a flow rate of 0.2 mL / min. -1 Deionized water is introduced into the cathode via a circulating inlet system, with a flow rate set at 4 mL / min. -1 The hydrogen flow rate was 30 sccm, and the reaction was completed after 4 hours.

[0060] c: During electrolysis, samples were taken from the central chamber and the anode and cathode every 1 hour to test the potassium ion concentration and potassium acetate cross-concentration. The separation efficiency of the acetic acid obtained after the reaction was calculated to be 81.3%. The results are as follows: Figure 4 .

[0061] Example 3

[0062] Separation of sodium lactate solution using a porous solid electrolyte reactor that couples cathodic electrolysis of water to produce hydrogen with anodic hydrogen oxidation:

[0063] a: Platinum-carbon was sprayed onto hydrophilic carbon paper as the cathode electrode, and a hydrogen production reaction by water electrolysis occurred with a loading of 1.5 mg·cm⁻¹. -2 Hydrophobic carbon paper coated with platinum carbon was used as the anode, and a hydrogen oxidation reaction was carried out with a loading of 1.5 mg·cm³. -2 A porous solid electrolyte reactor was assembled using Dowex 50WX8 as the solid electrolyte, Nafion 117 as the proton exchange membrane, and Vulcan XC-72 as the cation exchange membrane. Sodium lactate solution was introduced into the central chamber, hydrogen gas into the anode chamber, and deionized water into the cathode for electrolysis.

[0064] b: First, the catalyst was activated using cyclic voltammetry. Then, a 0.5M sodium lactate solution was introduced into the central chamber at twice the theoretical flow rate in a single pass, and performance tests were conducted at different current densities. It was found that at 200mA cm⁻¹... -2 At the current density, the sodium ion migration efficiency can reach 85.23% at twice the theoretical flow rate; in addition, in circulation mode, 200 mL of 0.5 M sodium lactate is introduced into the central chamber, and circulating water is introduced into the cathode at a flow rate of 4 mL / min. -1 The anode reaction chamber is unidirectionally supplied with hydrogen at a flow rate of 30 sccm, and a flow rate of 200 mA·cm is applied. -2 Electrolysis with current was performed, and after 8 hours of reaction, the separation efficiency of lactic acid was 84.5%.

[0065] c: The solution in the central chamber after the reaction was rotary evaporated and the evaporated liquid was collected. The volume was adjusted and the sample was tested by high performance liquid chromatography. The recovery rate of lactic acid was 76.6%.

[0066] Example 4

[0067] Separation of 2,5-furan dicarboxylic acid potassium solution by porous solid electrolyte reactor with cathode oxygen reduction reaction coupled with anode water electrolysis oxygen production reaction:

[0068] a: hydrophobic carbon paper was sprayed with multi-hydroxyl carbon tubes as cathode electrode for oxygen reduction to produce hydrogen peroxide, with a loading of 0.8 mg-cm -2 ; titanium felt sintered iridium oxide as anode for water electrolysis reaction to produce oxygen, with a loading of 1.2 mg-cm -2 ; Dowex 50W X8 as solid electrolyte; Nafion 117 as proton exchange membrane and Vulcan XC-72 as cation exchange membrane to assemble a porous solid electrolyte reactor. The central chamber was circulated with 2,5-furan dicarboxylic acid potassium solution, the anode was circulated with water, and the cathode was circulated with a mixture of oxygen and water for electrolysis.

[0069] b: first, the catalyst was activated by voltammetry test, then the reaction was carried out at a current of 100 mA-cm -2 ; the central chamber was circulated with 100 mL of 0.5M 2,5-furan dicarboxylic acid potassium solution at a flow rate of 0.3 mL-min -1 ; the cathode reaction chamber was single-pass liquid, with an oxygen flow rate of 50 sccm and a deionized water flow rate of 0.5 mL-min -1 ; the anode was circulated with water at a flow rate of 5 mL-min -1 ;

[0070] c: after 16 hours of electrolysis, the central chamber and anode and cathode solutions were sampled to test the potassium ion concentration and 2,5-furan dicarboxylic acid potassium cross, and the transfer efficiency of potassium ion was calculated to be 83.7%, and the separation efficiency of 2,5-furan dicarboxylic acid in the central chamber was 79.8%.

[0071] Example 5

[0072] Separation of 2,5-furan dicarboxylic acid potassium solution by porous solid electrolyte reactor with cathode oxygen reduction reaction coupled with anode water electrolysis oxygen production reaction:

[0073] a: hydrophobic carbon paper was sprayed with multi-hydroxyl carbon tubes as cathode electrode for oxygen reduction to produce hydrogen peroxide, with a loading of 0.8 mg-cm -2 ; titanium felt sintered iridium oxide as anode for water electrolysis reaction to produce oxygen, with a loading of 1.2 mg-cm -2 ; IR120 as solid electrolyte; Nafion 117 as proton exchange membrane and cation exchange membrane to assemble a porous solid electrolyte reactor. The central chamber was circulated with 2,5-furan dicarboxylic acid potassium solution, the anode was circulated with water, and the cathode was circulated with a mixture of oxygen and water for electrolysis;

[0074] b: First, the catalyst was activated by voltammetry test, then the reaction was carried out under the current condition of 250 mA-cm -2 , wherein the central chamber was connected to circulating 200 mL 1M sodium adipate solution, and the flow rate was 2.5 mL-min -1 ; the oxygen flow rate of the cathode was 80 sccm, and the water flow rate was 0.8 mL min -1 ; the liquid inlet mode of the cathode was one-way liquid inlet; the anode was connected to circulating water, and the flow rate was set to 6 mL min -1 ;

[0075] c: After electrolysis for 26 hours, the central chamber and the anode and cathode solutions were sampled and tested, and the migration efficiency of sodium ions was calculated to be 81.9%, and the separation efficiency of adipic acid in the central chamber was 76.3%.

[0076] Example 6

[0077] A porous solid electrolyte reactor for separating potassium succinate solution by coupling hydrogen production reaction of cathode electrolysis water with hydrogen oxidation reaction of anode:

[0078] a: The hydrophilic carbon paper was sprayed with ruthenium oxide as the cathode electrode to produce hydrogen by electrolysis of water, and the loading amount was 1 mg-cm -2 ; the hydrophobic carbon paper was sprayed with platinum carbon as the anode to produce hydrogen oxidation reaction, and the loading amount was 1.5 mg-cm -2 ; Dowex 50WX8 was used as the solid electrolyte; Nafion 117 was used as the proton exchange membrane and SIN-D117 was used as the cation exchange membrane, and a porous solid electrolyte reactor was assembled. The central chamber was connected to potassium succinate solution, the anode was connected to hydrogen, and the cathode was connected to circulating water for electrolysis;

[0079] b: First, the catalyst was activated by voltammetry test, then the reaction was carried out under the current condition of 80 mA-cm -2 , wherein the central chamber was connected to circulating 50 mL 2M potassium succinate solution, and the flow rate was 1.2 mL-min -1 ; the liquid inlet mode of the cathode chamber was one-way liquid inlet, wherein the oxygen flow rate was 60 sccm, and the deionized water flow rate was 0.6 mL min -1 ; the anode was connected to circulating water, and the flow rate was set to 5 mL min -1 ;

[0080] c: After electrolysis for 20 hours, the central chamber and the anode and cathode solutions were sampled and tested for potassium ion migration concentration, and the transfer efficiency of potassium ions was calculated to be 74.9%, and the separation efficiency of adipic acid in the central chamber was 71.7%.

[0081] Example 7

[0082] Separation of potassium glycolate solution using a porous solid electrolyte reactor that couples the cathode electrolysis of water to produce hydrogen with the anode hydrogen oxidation reaction:

[0083] a: Ruthenium oxide was sprayed onto hydrophilic carbon paper as the cathode electrode, and a hydrogen production reaction was generated by water electrolysis. The loading was 1 mg·cm⁻¹. -2 Hydrophobic carbon paper coated with platinum carbon was used as the anode, and a hydrogen oxidation reaction was carried out with a loading of 1.5 mg·cm³. -2 A porous solid electrolyte reactor was assembled using Dowex 50WX8 as the solid electrolyte, Nafion 117 as the proton exchange membrane, and SIN-D117 as the cation exchange membrane. Potassium glycolate solution was introduced into the central chamber, hydrogen gas was introduced into the anode, and deionized water was introduced into the cathode for electrolysis.

[0084] b: First, the catalyst was activated using a voltammetric test, and then at 200 mA·cm⁻¹. -2 The reaction was carried out under the specified current conditions, wherein 100 mL of 1.5 M potassium glycolate solution was circulated into the central chamber at a flow rate of 2 mL / min. -1 Hydrogen gas is introduced unidirectionally into the anode reaction chamber at a flow rate of 60 sccm; circulating water is introduced into the cathode at a flow rate of 6 mL / min. -1 ;

[0085] c: After 12 hours of electrolysis, the solutions in the central chamber and cathode were brought to a constant volume and samples were taken to test the potassium ion concentration and potassium glycolate cross-conversion. The calculated potassium ion transfer efficiency was 88.1%, and the separation efficiency of glycolic acid in the central chamber was 84.9%.

[0086] Example 8

[0087] Separation of sodium gluconate solution using a porous solid electrolyte reactor that couples the cathode oxygen reduction reaction with the anodic water electrolysis oxygen production reaction:

[0088] a: Hydrogen peroxide was prepared by spraying a polyhydroxy carbon tube onto hydrophobic carbon paper as the cathode electrode, and oxygen reduction occurred. The loading was 1.2 mg·cm³. -2 The iridium oxide coated on carbon paper is used as the anode to perform an electrolysis reaction to produce oxygen, with a loading of 2 mg·cm³. -2 A porous solid-state electrolyte reactor was assembled using a Dowex 50W X8 as the solid electrolyte, a Nafion 117 as the proton exchange membrane, and a Vulcan XC-72 as the cation exchange membrane. A sodium gluconate solution was introduced into the central chamber, circulating water was introduced into the anode, and a mixture of oxygen and water was introduced into the cathode for electrolysis.

[0089] b: First, the catalyst was activated using a voltammetric test, and then at 100 mA·cm -2; the central chamber is connected to circulating 100 mL of 0.25M sodium gluconate solution, and the flow rate is 0.2 mL·min -1 ; the cathode chamber is connected to circulating water, and the flow rate is 3 mL·min -1 ; the anode is connected to circulating water, and the flow rate is 2 mL·min -1 ;

[0090] c: After electrolysis for 4 hours, the sodium ion concentration of the central chamber and the anode and cathode solutions is tested, and the transfer efficiency of sodium ions is calculated to be 87.7%, and the separation efficiency of the central chamber gluconic acid is 83.6%.

[0091] Example 9

[0092] A porous solid electrolyte reactor for separating sodium gluconate solution by coupling hydrogen production by cathode electrolysis with hydrogen oxidation reaction in the anode:

[0093] a: RuO2 is sprayed on the hydrophilic carbon paper as the cathode electrode to produce hydrogen by electrolysis, and the loading is 1 mg·cm -2 ; Pt / C is sprayed on the hydrophobic carbon paper as the anode to produce hydrogen oxidation reaction, and the loading is 1.5 mg·cm -2 ; Dowex 50WX8 is used as the solid electrolyte; Nafion 117 is used as the proton exchange membrane and Vulcan XC-72 is used as the cation exchange membrane to assemble the porous solid electrolyte reactor; the central chamber is connected to the sodium gluconate solution, the anode is connected to hydrogen, and the cathode is connected to circulating water for electrolysis.

[0094] b: First, the catalyst is activated by voltammetry test, and then the reaction is carried out at a current of 200 mA·cm -2 ; the central chamber is connected to circulating 100 mL of 0.5M sodium gluconate solution, and the flow rate is 0.8 mL·min -1 ; the cathode chamber is connected to circulating water, and the flow rate is 3 mL·min -1 ; the anode is connected to hydrogen, and the flow rate is 60 sccm.

[0095] c: After electrolysis for 8 hours, the central chamber and the anode and cathode solutions are sampled and tested for sodium ion concentration and sodium gluconate cross, and the transfer efficiency of sodium ions is calculated to be 89.1%, and the separation efficiency of the central chamber sodium gluconate is 86.7%.

[0096] The present application is universal for the separation of various organic acid salts to obtain organic acids, and has the advantages of green production process, low reaction energy consumption, simple separation steps, etc. compared with traditional separation processes.

[0097] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict.

[0098] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for electrochemically separating organic acids and bases, characterized in that: (I) Assembling a porous solid electrolyte reactor (i) Select appropriate cathode and anode reactions, and select appropriate cathode catalysts, anode catalysts, cathode reactants and anode reactants according to the cathode and anode reactions to prepare cathode and anode electrodes; (ii) Assemble the cathode electrode, anode electrode, proton exchange membrane, cation exchange membrane, solid electrolyte and gaskets of appropriate size into a porous solid electrolyte reactor; (II) The organic acid salt solution to be separated is introduced into the central chamber of the porous solid electrolyte reactor, the cathode reactant is introduced into the cathode chamber, and the anode reactant is introduced into the anode chamber and electrolyzed. Finally, organic acid is obtained in the central chamber and alkali is recovered at the cathode, thus completing the separation of organic acid and alkali. The cathode reaction is either an electrolysis reaction to produce hydrogen or an oxygen reduction reaction; the anode reaction is either hydrogen oxidation or an electrolysis reaction to produce oxygen; when the cathode reaction is an electrolysis reaction to produce hydrogen, the cathode catalyst is either ruthenium oxide or platinum carbon; when the anode reaction is an oxygen reduction reaction, the cathode catalyst is either carbon tube or carbon black; when the anode reaction is an hydrogen oxidation reaction, the anode catalyst is either platinum carbon, ruthenium oxide, or nickel hydroxide; when the anode reaction is an electrolysis reaction to produce oxygen, the anode catalyst is either iridium oxide, ruthenium iridium oxide, nickel-molybdenum alloy, nickel hydroxide, nickel-iron hydrotalcite, or nickel-cobalt hydroxide; the cathode electrode is composed of a conductive substrate supporting the cathode catalyst; the anode electrode is composed of a conductive substrate supporting the anode catalyst; the conductive substrate is either carbon paper, titanium felt, or carbon cloth. When the cathode reactant is deionized water, the deionized water in the cathode chamber is fed in unidirectionally or through circulation. When the cathode reactant is a mixture of oxygen and deionized water, the mixture of oxygen and deionized water in the cathode chamber is fed in one direction. When the anode reactant is hydrogen, the hydrogen reactant in the anode chamber is introduced in one direction; When the anode reactant is deionized water, the deionized water in the anode chamber is fed in via a circulating system. The organic acid salt solution in the central chamber is supplied via unidirectional or cyclic injection.

2. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: When the cathode reaction is an electrolysis of water to produce hydrogen, the cathode reactant is deionized water; when the cathode reaction is an oxygen reduction reaction, the cathode reactant is a mixture of oxygen and deionized water; when the anode reaction is hydrogen oxidation, the anode reactant is hydrogen; when the anode reaction is an electrolysis of water to produce oxygen, the anode reactant is deionized water.

3. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: When the cathode reaction or anode reaction involves gaseous reactants, the conductive substrate of the anode electrode or cathode electrode is hydrophobically treated.

4. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: The proton exchange membrane is any one of Nafion 115 or Nafion 117; the cation exchange membrane is any one of Nafion-N2100TX, Nafion 115, Nafion 117 or SIN-D117 membrane; the solid electrolyte is a highly conductive ion exchange resin.

5. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: The organic acid salt is any one of formate, acetate, lactate, succinate, glycolate, adipate, gluconate, or gluconate.

6. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: The current density range for the electrolysis is 10 mA·cm⁻¹. -2 ~1000 mA·cm -2 .

7. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: When the cathode reactant is deionized water, the flow rate of the deionized water into the cathode chamber is 0.1 mL / min. -1 ~10 mL min -1 ; When the cathode reactant is a mixture of oxygen and water, the flow rate of oxygen in the cathode chamber is 20 sccm to 100 sccm; the flow rate of deionized water in the cathode chamber is 0.01 mL / min. -1 ~1 mLmin -1 ; When the anode reactant is hydrogen, the flow rate of the hydrogen reactant in the anode chamber is 20 sccm ~ 100 sccm; When the anolyte is deionized water, the flow rate of the deionized water into the anolyte chamber is 0.1 mL / min. -1 ~10 mL min -1 .

8. The method for electrochemical separation of organic acids and bases according to claim 1, characterized in that: The flow rate of the organic acid salt solution into the central chamber is 0.01 mL / min. -1 ~20 mL min -1 .

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