A method for hydrodechlorination of high-concentration chlorinated aromatic compounds

Abstract

The present invention discloses a method for hydrodechlorination of high-concentration chlorinated aromatic compounds. The method is to add high-concentration chlorinated aromatic compounds into an alkaline solution to obtain a cathode solution, use an alkaline aqueous solution as the anode solution, use a palladium-modified electrode as the cathode, use stainless steel as the anode, and carry out an electrolysis reaction in an electrolytic cell separated by an ion exchange membrane. After the electrolysis reaction is completed, an electrolyte solution of the dechlorinated compound is obtained, and the electrolyte solution is separated and purified to obtain the dechlorinated compound. The palladium-modified electrode is prepared by a cathode deposition method. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds provided by the present invention simultaneously realizes high reactant concentration, high space-time yield, high selectivity, high current efficiency and high current density, can not only greatly reduce the dosage of the catalyst palladium and reduce the electrolysis energy consumption, but also produce high-value-added products during the treatment of chlorinated organic compounds.

Description

Technical Field

[0001] The present invention belongs to the field of water pollution treatment, and particularly relates to a method for hydrodechlorination of high-concentration chloroaromatic compounds. Background Art

[0002] Chloroaromatic compounds (CAPs) are a class of important persistent organic compounds, which are widely present in industrial wastewater generated in synthetic fields such as pesticides, pharmaceuticals, and dyes, and have very high toxicity to organisms and the environment. Removing chlorine atoms in CAPs to generate less toxic aromatic or alkane substances is a common environmental remediation route. Palladium-catalyzed electrochemical hydrogenation method has attracted much attention due to the advantages of not requiring expensive or dangerous external reducing agents, mild reaction conditions, and high reaction selectivity. Multiple CAPs in wastewater can be converted into the same substance through palladium-catalyzed selective hydrodechlorination reaction (for example, chlorophenols can all be dechlorinated into phenols, chlorophenoxyacetic acids can all be dechlorinated into phenoxyacetic acids, and chloropicolinic acids can all be dechlorinated into picolinic acids). A highly chemoselective hydrodechlorination method is expected to turn waste into treasure for CAPs in industrial wastewater.

[0003] Unfortunately, most of the current research on palladium-catalyzed electrochemical hydrodechlorination reactions focuses on the treatment of low-concentration (mg / L level) CAPs in water bodies, and requires a very high dosage of palladium catalyst. For example, the invention patent application with the application number 200910237763.7 discloses a palladium catalyst for treating chlorine-containing organic compounds in water and its preparation method, which uses an electrochemically reduced oxidation-coupled multifunctional palladium-loaded catalyst as the catalyst for the electrochemical cathode. Although it has a reduction dechlorination effect and makes full use of the reduction effect of the cathode to improve the electrochemical treatment efficiency of chlorine-containing organic compounds in water, it still has the above-mentioned deficiencies. This leads to a series of problems such as high catalyst cost per unit CAPs treatment amount, low current efficiency, low current density, and difficulty in recovering dechlorination products, and it is difficult to generate economic benefits. Therefore, it is of great application value to invent a hydrodechlorination method with low loading and high conversion rate and high selectivity for high-concentration CAPs. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for hydrodechlorination of high-concentration chloroaromatic compounds. A variety of CAPs are added to an alkaline solution to obtain a high-concentration electrolysis reaction solution, and then a palladium-modified conductive material is used as the cathode, and a chemically inert conductive material is used as the anode. An electrolysis reaction is carried out in an electrolytic cell separated by an ion exchange membrane, and various CAPs can achieve high-current-efficiency, high-current-density, high-space-time-yield, and high-selectivity dechlorination. The present invention can effectively solve the problems of low reactant concentration, low palladium utilization rate, low current efficiency, and small current density existing in the existing palladium-catalyzed dechlorination technology.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for hydrodechlorination of chloroaromatic compounds. The method is as follows: adding the chloroaromatic compound shown in formula (I) into an alkaline aqueous solution to obtain a cathode solution, using the alkaline aqueous solution as an anode solution, using a palladium-modified electrode as the cathode, using stainless steel as the anode, and performing an electrolysis reaction in an electrolytic cell separated by an ion exchange membrane. After the electrolysis reaction is completed, an electrolyte solution containing the dechlorinated compound shown in formula (II) is obtained, and the electrolyte solution is separated and purified to obtain the dechlorinated compound shown in formula (II).

[0007] XRCln XRHn

[0008] (I) (II)

[0009] In formula (I), R is a single benzene ring or a single pyridine ring; X is a hydroxyl group, a carboxyl group or a methoxy acetate group, and n is one of the positive integers between 1 and 5; R, X and n in formula (II) are the same as those in formula (I).

[0010] The concentration of the chloroaromatic compound shown in formula (I) in the cathode solution is 5 to 300 g / L.

[0011] The chloroaromatic compound shown in formula (I) is one or more of chloropicolinic acid, chlorophenol, chlorobenzoic acid, chlorophenoxyacetic acid.

[0012] The pH range of the cathode solution is 10 to 14, preferably 12 to 14, and more preferably 14.

[0013] The pH value of the anode solution is 13 to 14, preferably 12 to 14, and more preferably 14.

[0014] The conditions of the electrolysis reaction: the current density is 1 to 20 A / dm 2 , preferably 2 to 15 A / dm 2 , more preferably 2 to 12.5 A / dm 2 , and the temperature is 0 to 100 °C, preferably 10 to 80 °C, and more preferably 20 to 70 °C.

[0015] The alkaline aqueous solution is prepared by mixing water and a supporting electrolyte; the supporting electrolyte is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide or tetrapropylammonium hydroxide, preferably sodium hydroxide; the concentration of the supporting electrolyte in the electrolyte solution is 0.1 to 2.0 mol / L, preferably 1 to 2.0 mol / L.

[0016] The shape of the anode can be in the form of a plate, rod, wire, sieve, net, foam, wool or sheet, preferably a plate.

[0017] The electrolytic reaction described in the present invention can be carried out intermittently or in a continuous or semi - continuous manner. The electrolytic cell can be a stirred cell containing electrodes or any flow electrolytic cell of conventional design. The electrolytic cell can be a diaphragm electrolytic cell or a non - diaphragm electrolytic cell, and a diaphragm electrolytic cell is preferred.

[0018] The anodic reaction described in the present invention can be an oxygen - evolving reaction that releases oxygen, or it can include the release of chlorine and bromine molecules, a hydrogen oxidation reaction, the production of carbon dioxide by the oxidation of protective substances such as formate or oxalate, or the formation of valuable by - products by the oxidation of organic reactants. The oxygen - evolving reaction is preferred.

[0019] The palladium - modified electrode is prepared by a cathodic deposition method; further, the specific preparation method of the palladium - modified electrode is as follows:

[0020] (1) Prepare the electrode substrate: Use a conductive material as the electrode substrate. First, clean the grease on the surface of the substrate with an organic solvent, and then etch the oxide layer on the surface of the substrate with an acidic aqueous solution to obtain a treated electrode substrate;

[0021] (2) Cathodic deposition: Use the treated electrode substrate obtained in step (1) as the cathode, an inert material as the anode, an aqueous solution containing polyvinylpyrrolidone, sodium sulfate, and palladium salt as the catholyte, and an aqueous solution of sodium sulfate as the anolyte. Prepare a palladium - modified electrode with a palladium loading of 0.5 - 5 g / m 2 by the cathodic deposition method.

[0022] In step (1), the electrode substrate is selected from metals such as nickel, stainless steel, titanium, silver, or carbon materials such as graphite, carbon fiber, carbon felt, and glassy carbon. The organic solvent is one or more of acetone, ethanol, methanol, and ether. The acidic aqueous solution is one or more of aqueous solutions of sulfuric acid, hydrochloric acid, and nitric acid.

[0023] In step (2), the inert material is one of graphite, platinum, titanium, silver, stainless steel, etc.

[0024] In the catholyte of step (2), the concentration of polyvinylpyrrolidone is 0.5 g - 5 g / L, preferably 2 g - 4 g / L, more preferably 2.5 g / L. The palladium salt is one or more of palladium chloride, sodium tetrachloropalladate, palladium acetate, palladium sulfate, and palladium nitrate. The concentration of the palladium salt is 5 - 50 mg / L, preferably 20 - 30 mg / L, more preferably 25 mg / L. The concentration of sodium sulfate is 5 - 50 g / L, preferably 10 - 20 g / L, more preferably 14.2 g / L. In the anolyte of step (2), the concentration of sodium sulfate is 5 - 50 g / L, preferably 10 - 30 g / L, more preferably 14.2 g / L.

[0025] The process parameters of the cathode deposition method are as follows: the applied current density is 0.05 - 0.15 A / dm 2 , preferably 0.06 - 0.10 A / dm 2 , more preferably 0.075 A / dm 2 , and the deposition time is 20 - 60 min, preferably 25 - 40 min, more preferably 30 min.

[0026] In the present invention, the required electrolytic reduction is carried out by means well - known in the art. Generally, the raw material chloro - aromatic compound or its mixture is dissolved or partially dissolved in a solvent, a certain amount of supporting electrolyte is added, and then a sufficient current is passed through the electrolytic cell until the required degree of reduction is obtained. After the electrolytic reaction is completed, the reaction solution is further adjusted in pH and the product is recovered using traditional techniques, such as acid precipitation filtration or chemical extraction, etc.

[0027] The reactions involved in the electrochemical reduction of high - concentration chloro - aromatic compounds according to the present invention (taking chloropicolinic acid as an example):

[0028] (1) Neutralization reaction:

[0029]

[0030] (2) Cathode reaction:

[0031]

[0032] (3) Anode reaction:

[0033] 2n OH - →1 / 2n O2 + 2n e -

[0034] (4) Overall reaction:

[0035]

[0036] The beneficial effects of the present invention are mainly reflected in: the hydrodechlorination method of high - concentration chloro - aromatic compounds provided by the present invention can simultaneously achieve high reactant concentration (200 g / L), high current density (2 - 10 A / dm 2 ), low electrolysis voltage (≤3 V), high conversion rate (≥99%), high selectivity (≥98%), and low energy consumption per unit product of electrolytic production (SEEC≤6 kW h / kg -1 ). It can not only greatly reduce the dosage of the catalyst palladium and lower the electrolysis energy consumption, but also produce high - value - added products during the treatment of chloro - organic compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a comparative scanning electron microscope image of the palladium - modified nickel foam cathode prepared in Example 1 and Comparative Example 1. Detailed implementation manners

[0038] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0039] In the implementation manner of the present invention, the calculation formula for the energy consumption per unit product (SEEC) in electrolysis production is: SEEC = (I × t × U) / (1000 × ΔC × V) (kW h kg -1 )

[0040] Wherein: I is the current (A), t is the time (h), U is the average electrolysis voltage (V), ΔC is the mass concentration of the target product (kg / L), and V is the volume of the electrolyte solution (L).

[0041] Example 1 Preparation of Palladium-Modified Nickel Foam Cathode (PdNPs / Ni)

[0042] Cut a 2 cm × 2 cm nickel foam as the electrode substrate. First, clean the grease on the surface of the substrate with acetone, and then etch the oxide layer on the surface of the substrate with a nitric acid aqueous solution to obtain the treated electrode substrate. Using the above-treated electrode substrate as the working electrode, graphite as the counter electrode, an aqueous solution containing 2.5 g / L polyvinylpyrrolidone, sodium tetrachloropalladate with a palladium concentration of 25 mg / L, and 14.2 g / L sodium sulfate as the cathode electrolyte, and an aqueous solution containing 14.2 g / L sodium sulfate as the anode electrolyte, apply a current density of 0.075 A / dm 2 for 30 min.

[0043] Example 2 Electrochemical Hydrodechlorination of 3,6-Dichloropicolinic Acid (3,6-D) with a Concentration of 0.1 mol / L

[0044] In a diaphragm electrolytic cell separated by an ion exchange membrane, palladium-modified nickel foam is used as the cathode (the modification method follows Example 1), stainless steel is used as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 19.2 g / L 3,6-D is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and the current density is controlled at 2.5 A / dm 2 , and the electrolysis voltage is 1.8 V - 2.4 V. After electrolysis for 5 hours, transfer the cathode solution to a beaker, add sulfuric acid to adjust the pH = 4, and then analyze the conversion rate of 3,6-D by high performance liquid chromatography to be 100%, the yield of picolinic acid to be 95%, and the SEEC to be 6.08 kW h kg -1 .

[0045] The high-performance liquid chromatography analysis conditions are as follows: a chromatographic column (150 mm length × 4.6 mm i.d., 5 μm particle size) is used as the separation column, the mobile phase is a mixture of acetonitrile / methanol / water = 2 / 3 / 5 (containing 30 mmol / L phosphoric acid), the injection volume is 20 μL, the injection temperature is 30 °C, the flow rate is 1 mL / min for isocratic elution, the wavelength of the ultraviolet detector is 260 nm, and the external standard method is used to determine the standard curve for quantitative calculation of reactants and products.

[0046] Example 3 Electrochemical Hydrodechlorination of 3,6-Dichloropicolinic Acid (3,6-D) with a Concentration of 1 mol / L

[0047] In a diaphragm electrolytic cell separated by an ion-exchange membrane, palladium-modified nickel foam is used as the cathode (the modification method follows Example 1), stainless steel is used as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 192 g / L 3,6-D is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and different current densities are applied in segments according to the electrolysis time of 0 h to 1 h, 1 h to 3 h, and 3 h to 8 h, which are 25 A / dm 2 、12.5 A / dm 2 and 2.5 A / dm 2 , and the electrolysis voltages are 6.7 V to 11.2 V, 4.7 V to 5.5 V, and 2.9 V to 3.7 V respectively. After 8 hours of electrolysis, the cathode solution is transferred to a beaker, sulfuric acid is added to adjust the pH = 4, and then the conversion rate of 3,6-D is analyzed by high-performance liquid chromatography to be 100%, the yield of picolinic acid is 95%, and the SEEC is 8.94 kW h kg -1 .

[0048] The high-performance liquid chromatography analysis conditions are as follows: a chromatographic column (150 mm length × 4.6 mm i.d., 5 μm particle size) is used as the separation column, the mobile phase is a mixture of acetonitrile / methanol / water = 2 / 3 / 5 (containing 30 mmol / L phosphoric acid), the injection volume is 20 μL, the injection temperature is 30 °C, the flow rate is 1 mL / min for isocratic elution, the wavelength of the ultraviolet detector is 260 nm, and the external standard method is used to determine the standard curve for quantitative calculation of reactants and products.

[0049] Example 4 Electrochemical Hydrodechlorination of 4-Amino-3,6-dichloropicolinic Acid (4-N-3,6-D) with a Concentration of 0.1 mol / L

[0050] In a diaphragm electrolytic cell separated by an ion exchange membrane, palladium-modified nickel foam serves as the cathode (the modification method follows Example 1), stainless steel serves as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 20.7 g / L 4-N-3,6-D is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and the current density is controlled at 2.5 A / dm 2 , and the electrolysis voltage is 1.9 V to 2.4 V. After 8 hours of electrolysis, the cathode solution is transferred to a beaker, sulfuric acid is added to adjust the pH to 4, and then the conversion rate of 4-N-3,6-D is analyzed by high performance liquid chromatography to be 96%, the yield of 4-aminopicolinic acid is 95%, and the SEEC is 8.87 kW hkg -1 .

[0051] The high performance liquid analysis conditions are as follows: The chromatographic column (150 mm length × 4.6 mm i.d., 5 μm particle size) is used as the separation column, the mobile phase volume ratio is a mixture of acetonitrile / methanol / water = 2 / 3 / 5 (containing 30 mmol / L phosphoric acid), the injection volume is 20 μL, the injection temperature is 30 °C, the flow rate is 1 mL / min for isocratic elution, the wavelength of the ultraviolet detector is 260 nm, and the external standard method is used to determine the standard curve for quantitative calculation of reactants and products.

[0052] Example 5 Electrochemical Hydrodechlorination of 2,4-Dichlorophenol (2,4-DCP) with a Concentration of 0.1 mol / L

[0053] In a diaphragm electrolytic cell separated by an ion exchange membrane, palladium-modified nickel foam serves as the cathode (the modification method follows Example 1), stainless steel serves as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 16.3 g / L 2,4-DCP is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and the current density is controlled at 2.5 A / dm 2 , and the electrolysis voltage is 1.8 V to 2.4 V. After 8 hours of electrolysis, the cathode solution is transferred to a beaker, sulfuric acid is added to adjust the pH to 4, and then the conversion rate of 2,4-DCP is analyzed by high performance liquid chromatography to be 98%, the yield of phenol is 96%, and the SEEC is 12.68 kW hkg -1 .

[0054] The high-performance liquid analysis conditions are as follows: a chromatographic column (250 mm length × 4.6 mm i.d., 5 μm particle size) is used as the separation column, the mobile phase is a mixture of methanol / water = 4 / 1 (containing 30 mmol / L phosphoric acid), the injection volume is 20 μL, the injection temperature is 20 °C, the flow rate is 1 mL / min for isocratic elution, the wavelength of the ultraviolet detector is 280 nm, and the external standard method is used to measure the standard curve for quantitative calculation of reactants and products.

[0055] Examples 6 to 20

[0056] Examples 6 to 20 are carried out according to the experimental parameters in Table 1, and the remaining operations are the same as those in Example 2. 3,6-Dichloropicolinic acid, 4-chlorophenoxyacetic acid, 4-chlorocarboxylic acid, 4-chlorophenol, and 2,4,6-trichlorophenol are represented by 3,6-D, 4-CPA, 4-CBA, 4-CP, and 2,4,6-TCP, respectively.

[0057] Table 1 Experimental conditions and results of Examples 6 to 20

[0058]

[0059]

[0060]

[0061]

[0062] Comparative Example 1 Electrochemical hydrogenation dechlorination of 3,6-dichloropicolinic acid (3,6-D) with a concentration of 0.1 mol / L catalyzed by a traditional palladium-modified nickel foam cathode (Pd / Ni) (compared with Example 2)

[0063] The preparation of the Pd / Ni cathode follows Example 1, but polyvinylpyrrolidone is not added during the preparation process.

[0064] In a diaphragm electrolytic cell separated by an ion exchange membrane, Pd / Ni is used as the cathode and stainless steel is used as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 19.2 g / L 3,6-D is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and the current density is controlled at 2.5 A / dm 2 , and the electrolysis voltage is 1.8 V to 2.4 V. After electrolysis for 5 hours, the cathode solution is transferred to a beaker, sulfuric acid is added to adjust the pH = 4, and then the conversion rate of 3,6-D is analyzed by high-performance liquid chromatography to be 95%, the yield of picolinic acid is 59%, and the SEEC is 10.86 kW h kg -1 .

[0065] Comparative Example 1 shows that the electrochemical dechlorination of 3,6-D by traditional Pd / Ni cathode cannot achieve ideal results (low yield, low current efficiency).

[0066] Comparative Example 2 Electrochemical hydrogenation dechlorination of 3,6-dichloropicolinic acid (3,6-D) at a low concentration of 0.001 mol / L (compared with Example 2 and Example 3)

[0067] In a diaphragm electrolytic cell separated by an ion exchange membrane, palladium-modified nickel foam is used as the cathode (the modification method is in accordance with Example 1), stainless steel is used as the anode, and the distance between the anode and the cathode is 5 cm. 30 mL of 1.0 mol / L NaOH + 192 mg / L 3,6-D is used as the cathode solution; 30 mL of 1.0 mol / L NaOH is used as the anode solution. During the electrolysis process, the temperature is controlled at 25 °C, and the current density is controlled at 0.075 A / dm 2 , and the electrolysis voltage is 1.9 V - 2.3 V. After 5 hours of electrolysis, the cathode solution is transferred to a beaker, the pH is adjusted to 4 by adding sulfuric acid, and then the conversion rate of 3,6-D is analyzed by high performance liquid chromatography to be 100%, the yield of picolinic acid is 99%, and the SEEC is 11.15 kW hkg -1 .

[0068] Comparative Example 2 shows that the electrochemical dechlorination of low-concentration 2,4-D cannot achieve ideal results (low current density, low current efficiency, low space-time yield).

Claims

1. A method for hydrodechlorination of high-concentration chlorinated aromatic compounds, the method being: adding the chlorinated aromatic compound shown in formula (I) into an alkaline aqueous solution to obtain a cathode solution, using the alkaline aqueous solution as an anode solution, using a palladium-modified electrode as the cathode, using stainless steel as the anode, and performing an electrolysis reaction in an electrolytic cell separated by an ion exchange membrane. After the electrolysis reaction, an electrolytic solution containing the dechlorinated compound shown in formula (II) is obtained, and the electrolytic solution is separated and purified to obtain the dechlorinated compound shown in formula (II), characterized in that: The palladium-modified electrode is prepared by a cathodic deposition method; In formula (I), R is a single benzene ring or a single pyridine ring; X is a hydroxyl group, a carboxyl group or a methoxy acetate, and n is one of the positive integers between 1 and 5; R, X and n in formula (II) are the same as those in formula (I); The specific preparation method of the palladium-modified electrode is as follows: (1) Using a conductive material as the electrode substrate, first cleaning the grease on the substrate surface with an organic solvent, and then etching the oxide layer on the substrate surface with an acidic aqueous solution to obtain a treated electrode substrate; (2) Using the treated electrode substrate obtained in step (1) as the cathode, an inert material as the anode, an aqueous solution containing polyvinylpyrrolidone, sodium sulfate and palladium salt as the cathode electrolyte, and an aqueous solution of sodium sulfate as the anode electrolyte, and preparing a palladium-modified electrode by a cathodic deposition method.

2. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds according to claim 1, characterized in that: In step (1), the electrode substrate is a metal selected from nickel, stainless steel, titanium, silver or a carbonaceous material selected from graphite, carbon fiber, carbon felt, glassy carbon, the organic solvent is one or more of acetone, ethanol, methanol and ether, and the acidic aqueous solution is one or more of aqueous solutions of sulfuric acid, hydrochloric acid and nitric acid.

3. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds according to claim 1, characterized in that: In the electrolyte of step (2), the concentration of polyvinylpyrrolidone is 0.5 g to 5 g / L, the palladium salt is one or more of palladium chloride, sodium tetrachloropalladate, palladium acetate, palladium sulfate, palladium nitrate, the palladium concentration is 5 to 50 mg / L, and the sodium sulfate concentration is 5 to 50 g / L.

4. The method for hydrodechlorination of highly concentrated chlorinated aromatic compounds according to claim 1, wherein: The process parameters of the cathode deposition method are as follows: the applied current density is 0.05 - 0.15 A / dm 2 , and the deposition time is 20 - 60 min.

5. The method for hydrodechlorination of highly concentrated chlorinated aromatic compounds according to claim 1, characterized in that: The palladium loading of the palladium-modified electrode is 0.5 to 5 g / m 2 .

6. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds according to claim 1, wherein: The concentration of the chloroaromatic compound shown in formula (I) in the cathode solution is 5 to 300 g / L.

7. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds according to claim 1, characterized in that: The chloroaromatic compound shown in formula (I) is one or more of chloropicolinic acid, chlorophenol, chlorobenzoic acid, chlorophenoxyacetic acid.

8. The method for hydrodechlorination of high-concentration chlorinated aromatic compounds according to claim 1, characterized in that: The conditions for the electrolysis reaction are as follows: the current density is 1 to 20 A / dm 2 , and the temperature is 0 to 100 °C.

9. The method for hydrogenation dechlorination of high-concentration chlorinated aromatic compounds according to claim 1, characterized in that: The alkaline aqueous solution is prepared by mixing water and a supporting electrolyte; the concentration of the supporting electrolyte in the electrolyte is 0.1 to 2.0 mol / L.

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