Electrolyte treatment method for synthesizing adiponitrile through acrylonitrile electrolysis and method for synthesizing adiponitrile through acrylonitrile electrolysis

Abstract

The invention provides an electrolyte treatment method for synthesizing adiponitrile through acrylonitrile electrolysis, and the electrolyte treatment method comprises the following steps: 1) uniformly mixing an inert conductive material, an inert non-conductive material and magnesium, and filling the mixture into the lower section of an electrochemical three-dimensional electrode bed layer, uniformly mixing an inert conductive material and an inert non-conductive material, and filling the upper section of the electrochemical three-dimensional electrode bed layer with the mixture to construct a three-dimensional electrode system; and 2) carrying out electrolyte electrochemical deposition on acrylonitrile electrolytic synthesis adiponitrile by using the three-dimensional electrode system. The treated electrolyte is used for synthesizing adiponitrile through acrylonitrile electrolysis. A certain amount of magnesium particles are added to the lower section of the three-dimensional electrode bed layer, iron ions in electrolyte are further adsorbed, meanwhile, iron ion deposition on the surface of a cathode can be effectively restrained, hydrogen evolution side reaction is restrained, and the problems that in a traditional synthesis process, iron ions are deposited on the cathode, and an electrolytic bath needs to be frequently cleaned and replaced in the production process are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of adiponitrile preparation, and in particular to a method for treating an electrolyte for electrolytic synthesis of adiponitrile from acrylonitrile, and a method for electrolytic synthesis of adiponitrile from acrylonitrile Background Art

[0002] Adiponitrile (ADN), also known as 1,4-dicyanobutane, with the molecular formula NC(CH2)4CN, is an important organic chemical raw material. The most important industrial use of adiponitrile is to produce hexamethylenediamine. Hexamethylenediamine copolymerizes with adipic acid to form nylon 66 salt, and then nylon fiber is produced. Approximately 90% of the world's adiponitrile is used in the production of nylon 66 salt every year, and its cost accounts for about 40% of the production cost of nylon 66 salt. In addition, hexamethylenediamine can also obtain HDI (1,6-diisocyanate) through a photochemical reaction. HDI is the main raw material for producing high-grade environmentally friendly coatings, which is another important use of adiponitrile

[0003] At present, the production of adiponitrile is monopolized by foreign large multinational companies, such as Invista in the United States, Asahi Kasei in Japan, Rhodia in France, and BASF in Germany. The adiponitrile production technology is the development bottleneck of China's current nylon 66 industry, and it is urgent to solve the problem of breaking through the production technology blockade of foreign adiponitrile

[0004] The industrial process routes for producing adiponitrile mainly include adipic acid ammoniation dehydration method, acrylonitrile electrolytic dimerization method, and butadiene hydrocyanation method. Among them, the adipic acid ammoniation dehydration method has been eliminated at present due to its complex process, high raw material cost, low product yield, and poor quality. Although the butadiene hydrocyanation method has low raw material cost, mature process, and advanced technology, hydrocyanic acid is a highly toxic substance with huge potential risks, and the reaction process is long, so it is very difficult to develop this method in China. Compared with the adipic acid method and the butadiene method, the greatest advantage of the acrylonitrile electrolytic dimerization method is its simple reaction process and cheap and easily available raw materials. During the electrolysis reaction process, an oxidation reaction occurs at the anode to generate oxygen, and acrylonitrile undergoes a dimerization reaction at the cathode to generate adiponitrile

[0005] At present, the cathode of the electrolytic cell for electrochemically synthesizing adiponitrile mainly uses lead and cadmium, and the anode uses carbon steel. The carbon steel of the anode corrodes to generate iron ions and enters the electrolyte. During the recycling process of the electrolyte, iron ions are easily deposited on the cathode to form an iron coating, and then a hydrogen evolution reaction occurs. The main component of the electrolysis tail gas is oxygen, which has an explosion risk. Therefore, how to reduce iron ions in the aqueous phase and inhibit their deposition on the cathode is of great significance Summary of the Invention

[0006] In view of the above problems existing in the prior art, the present invention provides a method for treating an electrolyte for the electrolytic synthesis of adiponitrile from acrylonitrile, and a method for the electrolytic synthesis of adiponitrile from acrylonitrile. The iron ions in the aqueous phase are recovered by electrodeposition through a three-dimensional electrode, and at the same time, some magnesium particles are doped at the end of the three-dimensional electrode. Under the action of an electric field, the magnesium particles will quickly displace the iron ions in the solution, and at the same time release a certain concentration of magnesium ions into the electrolyte. The magnesium ions are easy to form a loose magnesium oxide layer on the cathode surface, which inhibits the deposition of iron ions on the electrode surface. In addition, the loose magnesium oxide layer detaches from the electrode surface at a relatively high plate flow rate, ensuring that no hydrogen evolution reaction occurs on the cathode surface.

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] A method for treating an electrolyte for the electrolytic synthesis of adiponitrile from acrylonitrile, comprising the following steps:

[0009] 1) Uniformly mix an inert conductive material, an inert non-conductive material, and magnesium, and fill them into the lower section of the electrochemical three-dimensional electrode bed layer. Uniformly mix the inert conductive material and the inert non-conductive material and fill them into the upper section of the electrochemical three-dimensional electrode bed layer to construct a three-dimensional electrode system.

[0010] 2) Electrochemically deposit the electrolyte for the electrolytic synthesis of adiponitrile from acrylonitrile using the above three-dimensional electrode system.

[0011] The deposited electrolyte can be used for the electrolytic synthesis of adiponitrile from acrylonitrile.

[0012] In the present invention, the electrolyte is first electrochemically deposited through a three-dimensional electrode system to remove iron ions in the electrolyte. In the upper bed layer, the iron ions are electrodeposited on the surface of the inert conductive material. In the lower bed layer, while the iron ions are electrodeposited on the surface of the inert conductive material, part of them are reduced by magnesium particles, and the magnesium ions enter the electrolyte solution. The electrolyte treated as above is added to the electrolytic cell for the electrolytic synthesis of adiponitrile from acrylonitrile.

[0013] In step 1) of the present invention, the inert non-conductive material is one or more of glass, ceramic materials, nylon materials, and plastics, preferably one or more of glass balls, ceramic balls, nylon balls, and plastic balls.

[0014] In step 1) of the present invention, the inert conductive material is one or more of titanium balls, ferrites, and graphite; among them, the titanium balls can also be titanium balls with a PbO2 coating, titanium balls with an IrO2 coating, and titanium balls with a RuO2 coating.

[0015] In step 1) of the present invention, in the upper section of the three-dimensional electrode bed layer, the weight ratio of the inert non-conductive material to the inert conductive material is 1:1 - 5, such as 1:1, 1:2, 1:3, 1:4, 1:5, etc., preferably 1:2 - 4.

[0016] In step 1) of the present invention, in the lower section of the three-dimensional electrode bed, the weight ratio of the inert non-conductive material, inert conductive material, and magnesium is 1:1 - 5: 0.1 - 0.5, such as 1:1: 0.1, 1:2: 0.2, 1:3: 0.3, 1:4: 0.4, 1:5: 0.5, etc., and preferably 1:2 - 4: 0.2 - 0.4.

[0017] Preferably, the magnesium is magnesium particles.

[0018] In step 1) of the present invention, the ratio of the height of the upper section to the height of the lower section of the three-dimensional electrode bed is 1: 0.1 - 0.5, and preferably 1: 0.2 - 0.3.

[0019] In step 1) of the present invention, the thickness of the three-dimensional electrode bed is 10 - 20 cm, preferably 12 - 15 cm, and the electrolyte flows through the three-dimensional electrode bed.

[0020] In step 1) of the present invention, a cathode and an anode are respectively provided at both ends of the three-dimensional electrode system. The cathode and the anode are respectively a platinum electrode, a platinum-titanium electrode, or a DSA electrode. The DSA electrode is preferably a Ti-based PbO2, IrO2, RuO2, or tin-antimony oxide electrode;

[0021] In the present invention, there are no special requirements for the shape and size of the electrode material. For example, in some examples, shapes such as circular, rectangular, and rhombic can be adopted; the size can be 3×3 - 5×5 cm.

[0022] In step 2) of the present invention, the mass content of iron ions in the electrolyte is 50 - 500 ppm.

[0023] In step 2) of the present invention, the temperature of the electrochemical deposition is 30 - 50 °C, such as 33 °C, 36 °C, 38 °C, 42 °C, 45 °C, and preferably 35 - 40 °C.

[0024] In step 2) of the present invention, the current density of the electrochemical deposition is 3 - 10 A / cm 2 , such as 3.5 A / cm 2 , 4.5 A / cm 2 , 5.5 A / cm 2 , 6.5 A / cm 2 , 7.5 A / cm 2 , 9.5 A / m 2 , and preferably 5 - 8 A / cm 2 ; the electrolysis time is 0.5 - 3 h, such as 0.8 h, 1.4 h, 1.8 h, 2.5 h, and preferably 1 - 2 h; preferably, constant current electrochemical deposition is adopted.

[0025] In step 2) of the present invention, the magnesium ions enter the electrolyte solution, and the mass content of magnesium ions in the electrolyte solution is 20-200 ppm, preferably 50-100 ppm.

[0026] The present invention also provides the application of the electrolyte solution treated by the treatment method of the present invention, which is used for the method of electrolytic synthesis of adiponitrile from acrylonitrile.

[0027] A method for electrolytic synthesis of adiponitrile from acrylonitrile, wherein adiponitrile is obtained by electrolyzing acrylonitrile in an electrolyte solution, and the electrolyte solution is treated by the treatment method of the present invention.

[0028] Preferably, the electrolyte solution comprises water, phosphate, EDTA, borate, acrylonitrile, and amide compounds. Among them, the water content is 75-88 wt%, the phosphate is 3-18 wt%, the EDTA is 0.5-6 wt%, the borate is 0.5-6 wt%, the amide compound is 0.5-3 wt%, and the acrylonitrile content is 0.3-3 wt%

[0029] Preferably, the water content is 80-85 wt%, the phosphate is 5-15 wt%, the EDTA is 1-5 wt%, the borate is 1-5 wt%, the amide compound is 0.5-3 wt%, and the acrylonitrile content is 0.5-2 wt%.

[0030] In the method for electrolytic synthesis of adiponitrile from acrylonitrile, the cathode electrode is a carbon steel cadmium-plated electrode or a lead electrode, and the anode electrode is a carbon steel electrode.

[0031] In the method for electrolytic synthesis of adiponitrile from acrylonitrile, the current density is 1000-2500 A / m 2 。

[0032] After the electrolyte solution for electrolytic synthesis of adiponitrile from acrylonitrile is used for a period of time, the electrolyte solution is treated by the treatment method of the present invention to remove the iron ions therein, and then the treated electrolyte solution is used for the electrolytic synthesis of adiponitrile from acrylonitrile.

[0033] The present invention proposes a new idea for removing iron ions in an aqueous phase using a three-dimensional electrode system. Compared with the prior art, the inventors unexpectedly found that a small amount of current passed through the three-dimensional electrode system can deposit iron ions in the electrolyte on the surface of an inert conductive material, avoiding the accumulation of iron ions in the system. In addition, a certain amount of magnesium is added to the lower section of the three-dimensional electrode bed. While further adsorbing iron ions in the electrolyte, magnesium will corrode to generate magnesium ions that enter the electrolyte solution. The magnesium ions can form a competitive reaction with iron ions at the cathode in the electrolytic synthesis of adiponitrile, effectively inhibiting the deposition of iron ions on the cathode surface. Moreover, the formed magnesium oxide is porous and easily falls off from the electrode surface, ensuring that there is no metal deposition adhered to the electrode surface and inhibiting the occurrence of the hydrogen evolution side reaction. It solves the problem that iron ions are deposited on the cathode in the traditional synthesis process, and the electrolytic cell needs to be frequently cleaned and replaced during the production process. It also has the advantages of simple process and low energy consumption, and is suitable for a wide range of industrial applications. Detailed Embodiments

[0034] The following further illustrates the present invention through specific examples. The examples described in the present invention are only for the purpose of explaining the present invention and do not limit the scope of the present invention.

[0035] The sources of the reagent raw materials used in the examples and comparative examples of the present invention are as follows:

[0036] Graphite material, Hebei Heiqing Carbon New Material Co., Ltd.;

[0037] Spherical ferrite: Dongguan Huantai Magnetoelectric Technology Co., Ltd., Y10T * 1.5 mm;

[0038] Glass beads: Hebei Guran New Material Technology Co., Ltd., grinding glass beads * 1.0 mm;

[0039] Platinum-titanium electrode, Xi'an Tajin Co., Ltd., coating thickness 1 μm;

[0040] Ti-based IrO2 anode, Jiangsu Yi'an Teng Special Electrodes Co., Ltd., iridium-titanium mesh 50×100;

[0041] Ti-based PbO2 anode, Jiangsu Yi'an Teng Special Electrodes Co., Ltd., lead-titanium mesh 50×100;

[0042] Ti-based RuO2 anode, Jiangsu Yi'an Teng Special Electrodes Co., Ltd., ruthenium-titanium mesh 50×100;

[0043] Unless otherwise specified, other raw materials or reagents are obtained through commercial channels available on the market.

[0044] The test methods used in the examples and comparative examples of the present invention are as follows:

[0045] In the following examples, the hydrogen spectrum structure of adiponitrile was characterized by a nuclear magnetic resonance spectrometer (Brucker ARX-400).

[0046] In the following examples, the deposited iron was characterized by an energy dispersive spectrometer (EDS SU3500); the iron content in the electrolyte before and after electrodeposition was characterized by inductively coupled plasma-mass spectrometry (Agilent 7500CS). The hydrogen content in the tail gas of the electrolytic synthesis of adiponitrile from acrylonitrile was characterized by gas chromatography.

[0047] Example 1

[0048] (1) The electrolytic synthesis of adiponitrile from acrylonitrile was carried out in the following steps:

[0049] 1): 4 g of acrylonitrile, 5 g of borax, 5 g of EDTA, 3 g of lauramide, 20 g of dipotassium hydrogen phosphate and 183 g of water were mixed evenly to prepare 220 g of electrolyte, and then added into a diaphragmless electrolytic cell.

[0050] 2): A cadmium-plated carbon steel electrode was used as the cathode electrode, and carbon steel was used as the anode electrode; the electrolyte was subjected to an electrolysis reaction at 20 °C, the electrolytic cell voltage was 5 V, and the electrolysis current density was 2000 A / m 2 , and acrylonitrile was continuously added dropwise at a rate of 4.5 g / h. The electrolysis time was 5 h. After the electrolysis reaction was completed, 210 g of the aqueous phase adiponitrile electrolyte was separated by standing. After detection, the iron ion content was 353.2 ppm.

[0051] (2) The purification of the aqueous phase of adiponitrile was carried out in the following steps:

[0052] S1: 10 g of glass balls, 20 g of titanium balls with a PbO2 coating and 2 g of magnesium particles were mixed evenly and filled into the lower section of the three-dimensional electrode bed layer, with a filling height of 1.36 cm. 50 g of glass balls and 100 g of titanium balls with a PbO2 coating were mixed evenly and filled into the upper section of the three-dimensional electrode bed layer, with a filling height of 13.64 cm. The thickness of the three-dimensional electrode bed layer was 15 cm. The anode used a platinum electrode, and the cathode used a Ti-based PbO2 electrode.

[0053] S2: 210 g of the adiponitrile electrolyte with an iron ion content of 350 ppm was pumped into the three-dimensional electrode electrolytic cell and reacted at 35 °C for 2 h. The current density of the electrolytic cell was 5 A / cm 2 , and the electrolysis voltage was 15.0 V.

[0054] After the electrolyte was treated, the magnesium ion content in it was detected to be 49.6 ppm, and the iron ion content was 65 ppm. The iron ion removal rate was calculated to be 81.6%. The treated electrolyte was continued to be electrolytically synthesized into adiponitrile according to the method described in step (1). After 5 h of electrolysis, the hydrogen content in the electrolysis tail gas was 0.02%.

[0055] Example 2

[0056] (1) Using the same method as step (1) of Example 1, acrylonitrile was electrolyzed to synthesize adiponitrile, and an adiponitrile electrolyte solution with an iron ion content of 353.2 ppm was obtained.

[0057] (2) The purification of the adiponitrile aqueous phase was carried out in the following steps:

[0058] S1: 10 g of ceramic balls, 30 g of graphite balls and 3 g of magnesium particles were mixed evenly and filled into the lower section of the three-dimensional electrode bed, with a filling height of 1.67 cm. 50 g of ceramic balls and 150 g of graphite balls were mixed evenly and filled into the upper section of the three-dimensional electrode bed, with a filling height of 8.33 cm. The thickness of the three-dimensional electrode bed was 10 cm. The anode was a platinum-titanium electrode and the cathode was a platinum electrode.

[0059] S2: 210 g of the adiponitrile electrolyte solution with an iron ion content of 353.2 ppm was pumped into the three-dimensional electrode electrolytic cell and reacted at 50 °C for 0.5 h. The current density of the electrolytic cell was 10 A / cm 2 , and the electrolysis voltage was 13.0 V.

[0060] After treatment with the electrolyte solution in Example 1, the magnesium ion content was detected to be 198.6 ppm and the iron ion content was 37 ppm. The iron ion removal rate was calculated to be 89.5%. The treated electrolyte solution was continued to electrolyze and synthesize adiponitrile according to the method described in step (1). After continuing electrolysis for 5 h, the hydrogen content in the electrolysis tail gas was 0.04%.

[0061] Example 3

[0062] (1) The electrolysis of acrylonitrile to synthesize adiponitrile was carried out in the following steps:

[0063] 1): 2 g of acrylonitrile, 11 g of boric acid, 3 g of EDTA, 5 g of lauramide, 15 g of potassium phosphate and 184 g of water were mixed evenly to prepare 220 g of electrolyte solution, and then added to a diaphragm-free electrolytic cell;

[0064] 2): A cadmium-plated carbon steel electrode was used as the cathode electrode and carbon steel was used as the anode electrode; the electrolyte solution was electrolyzed at 20 °C, the electrolytic cell voltage was 5 V, and the electrolysis current density was 2000 A / m 2 , and acrylonitrile was continuously added dropwise at a rate of 4.5 g / h. The electrolysis time was 5 h. After the electrolysis reaction was completed, the aqueous phase adiponitrile electrolyte solution of 213 g was separated by standing. After detection, the iron ion content was 315.9 ppm.

[0065] (2) The purification of the adiponitrile aqueous phase was carried out in the following steps:

[0066] S1: Mix 10 g of nylon balls, 10 g of titanium balls and 1 g of magnesium particles evenly and fill them into the lower section of the three-dimensional electrode bed, with a filling height of 2.77 cm. Mix 50 g of nylon balls and 50 g of titanium balls evenly and fill them into the upper section of the three-dimensional electrode bed, with a filling height of 9.23 cm. The thickness of the three-dimensional electrode bed is 12 cm. The anode uses a titanium-based PbO2 electrode and the cathode uses a platinum-titanium electrode.

[0067] S2: Pump 213 g of adiponitrile electrolyte with an iron ion content of 315.9 ppm into the three-dimensional electrode electrolytic cell and react at 40 °C for 3 h. The current density of the electrolytic cell is 3 A / cm 2 , and the electrolysis voltage is 11.5 V. After treatment with the electrolyte in Example 1, the magnesium ion content is detected to be 111.2 ppm and the iron ion content is 58 ppm. Calculate the iron ion removal rate to be 81.6%. Continue to electrolyze and synthesize adiponitrile for 5 h according to the method described in step (1) for the treated electrolyte, and the hydrogen content in the electrolysis tail gas is 0.04%.

[0068] Example 4

[0069] (1) Prepare adiponitrile electrolyte with an iron ion content of 315.9 ppm by referring to the method of electrolyzing acrylonitrile to synthesize adiponitrile in Example 3.

[0070] (2) Purify the aqueous phase of adiponitrile. The steps are as follows:

[0071] S1: Mix 10 g of plastic balls, 40 g of ferrite balls and 4 g of magnesium particles evenly and fill them into the lower section of the three-dimensional electrode bed, with a filling height of 5.71 cm. Mix 50 g of plastic balls and 200 g of ferrite balls evenly and fill them into the upper section of the three-dimensional electrode bed, with a filling height of 14.29 cm. The thickness of the three-dimensional electrode bed is 20 cm. The anode uses a titanium-based IrO2 electrode and the cathode uses a titanium-based PbO2 electrode.

[0072] S2: Pump 213 g of adiponitrile electrolyte with an iron ion content of 315.9 ppm into the three-dimensional electrode electrolytic cell and react at 30 °C for 1 h. The current density of the electrolytic cell is 8 A / cm 2 , and the electrolysis voltage is 17.2 V. After treatment with the electrolyte in Example 1, the magnesium ion content is detected to be 52.4 ppm and the iron ion content is 49 ppm. Calculate the iron ion removal rate to be 84.5%. Continue to electrolyze and synthesize adiponitrile according to the method described in step (1) for the treated electrolyte, and continue to electrolyze for 5 h. The hydrogen content in the electrolysis tail gas is 0.02%.

[0073] Example 5

[0074] (1) Prepare adiponitrile electrolyte with an iron ion content of 315.9 ppm by referring to the method of electrolyzing acrylonitrile to synthesize adiponitrile in Example 3.

[0075] (2) Aqueous phase purification of adiponitrile, the steps are as follows:

[0076] S1: Take 10 g of glass beads, 50 g of titanium balls coated with RuO2, and 5 g of magnesium particles, mix them evenly, and fill them into the lower section of the three-dimensional electrode bed layer, with a filling height of 5 cm. Take 50 g of glass beads and 250 g of titanium balls coated with RuO2, mix them evenly, and fill them into the upper section of the three-dimensional electrode bed layer, with a filling height of 10 cm. The thickness of the three-dimensional electrode bed layer is 15 cm. The anode uses a titanium-based RuO2 electrode, and the cathode uses a titanium-based IrO2 electrode.

[0077] S2: Pump 210 g of adiponitrile electrolyte with an iron ion content of 315.9 ppm into the three-dimensional electrode electrolytic cell, react at 35 °C for 1 h, the current density of the electrolytic cell is 5 A / cm 2 , and the electrolysis voltage is 14.3 V.

[0078] After treatment with the electrolyte in Example 1, the magnesium ion content is detected to be 21.7 ppm, and the iron ion content is 34 ppm. Calculate the iron ion removal rate to be 89.2%. Continue to electrolytically synthesize adiponitrile with the treated electrolyte according to the method described in step (1). After continuing electrolysis for 5 h, the hydrogen content in the electrolysis tail gas is 0.01%.

[0079] Comparative Example 1

[0080] Refer to the method for electrolytically synthesizing adiponitrile from acrylonitrile in Example 1 to prepare adiponitrile electrolyte with an iron ion content of 353.2 ppm. The difference is that the electrolyte is not purified, and the electrolysis reaction is continued with this electrolyte.

[0081] Using the method in Comparative Example 1, after electrolysis for 0.5 h, the iron ion content is 420 ppm, and the hydrogen content in the electrolysis tail gas is 4.6%.

[0082] Comparative Example 2

[0083] Refer to the method for electrolytically synthesizing adiponitrile from acrylonitrile in Example 1 to prepare adiponitrile electrolyte with an iron ion content of 353.2 ppm and purify the electrolyte. The difference is that magnesium particles are not added to the three-dimensional electrode bed layer.

[0084] After treatment with the electrolyte in Comparative Example 1, the magnesium ion content is detected to be 0 ppm, and the iron ion content is 192 ppm. Calculate the iron ion removal rate to be 45.6%. Use the treated electrolyte to continue electrolytically synthesize adiponitrile using the above steps. After electrolysis for 5 h, the hydrogen content in the electrolysis tail gas is 0.82%.

Claims

1. A method for treating electrolyte in the electrolytic synthesis of adiponitrile from acrylonitrile, characterized in that, It includes the following steps: 1) Uniformly mix an inert conductive material, an inert non-conductive material, and magnesium, and then fill the lower section of the electrochemical three-dimensional electrode bed layer. Uniformly mix the inert conductive material and the inert non-conductive material and fill the upper section of the electrochemical three-dimensional electrode bed layer to construct a three-dimensional electrode system; 2) Electrochemically deposit the electrolyte for the electrolytic synthesis of adiponitrile from acrylonitrile using the above three-dimensional electrode system.

2. The treatment method according to claim 1, characterized in that, The deposited electrolyte is used for the electrolytic synthesis of adiponitrile from acrylonitrile.

3. The treatment method according to claim 1, characterized in that, The inert non-conductive material is one or more of glass, ceramic materials, nylon materials, and plastics, preferably one or more of glass balls, ceramic balls, nylon balls, and plastic balls; Preferably, in step 1), the inert conductive material is one or more of titanium balls, ferrites, and graphite; preferably, the titanium balls are titanium balls with a PbO2 coating, titanium balls with an IrO2 coating, or titanium balls with a RuO2 coating.

4. The treatment method according to any one of claims 1 - 3, characterized in that, In step 1), in the upper section of the three-dimensional electrode bed layer, the weight ratio of the inert non-conductive material to the inert conductive material is 1:1 - 5; Preferably, in step 1), in the lower section of the three-dimensional electrode bed layer, the weight ratio of the inert non-conductive material, the inert conductive material, and magnesium is 1:1 - 5:0.1 - 0.5; Preferably, magnesium is magnesium particles.

5. The treatment method according to any one of claims 1 - 4, characterized in that, In step 1), the ratio of the height of the upper section to the height of the lower section of the three-dimensional electrode bed layer is 1:0.1 - 0.5, preferably 1:0.2 - 0.3; Preferably, in step 1), the thickness of the three-dimensional electrode bed layer is 10 - 20 cm, preferably 12 - 15 cm, and the electrolyte flows through the space between the three-dimensional electrode bed layers; Preferably, in step 1), a cathode and an anode are respectively provided at both ends of the three-dimensional electrode system. The cathode and the anode are respectively a platinum electrode, a platinum-titanium electrode, or a DSA electrode. The DSA electrode is preferably a Ti-based PbO2, IrO2, RuO2, or tin-antimony oxide electrode.

6. The treatment method according to any one of claims 1 - 5, characterized in that, In step 2), the mass content of iron ions in the electrolyte is 50 - 500 ppm; Preferably, in step 2), the temperature of the electrochemical deposition is 30 - 50 °C; Preferably, in step 2), the current density of the electrochemcial deposition is 3-10 A / cm 2 .

7. The treatment method according to any one of claims 1 - 6, characterized in that, In step 2), after the electrochemical deposition, the mass content of magnesium ions in the electrolyte is 20 - 200 ppm, preferably 50 - 100 ppm.

8. An application of the electrolyte treated by the treatment method according to any one of claims 1 - 7, which is used in the method for electrolytic synthesis of adiponitrile from acrylonitrile.

9. A method for electrolytic synthesis of adiponitrile from acrylonitrile, wherein adiponitrile is obtained by electrolyzing acrylonitrile in an electrolyte, and the electrolyte is treated by the electrolyte treated by the treatment method according to any one of claims 1 - 7.

10. The method according to claim 9, characterized in that, The electrolyte includes water, phosphate, EDTA, borate, acrylonitrile, and amide compounds; Preferably, the water content in the electrolyte is 75 - 88 wt%, the phosphate is 3 - 18 wt%, the EDTA is 0.5 - 6 wt%, the borate is 0.5 - 6 wt%, the amide compounds are 0.5 - 3 wt%, and the acrylonitrile content is 0.3 - 3 wt%; More preferably, the water content is 80 - 85 wt%, the phosphate is 5 - 15 wt%, the EDTA is 1 - 5 wt%, the borate is 1 - 5 wt%, the amide compounds are 0.5 - 3 wt%, and the acrylonitrile content is 0.5 - 2 wt%; Preferably, in the method for the electrolytic synthesis of adiponitrile from acrylonitrile, the cathode electrode is a cadmium-plated carbon steel electrode or a lead electrode, and the anode electrode is a carbon steel electrode; Preferably, in the method for electrolytic synthesis of adiponitrile from acrylonitrile, the current density is 1000 - 2500 A / m 2 .