Activity regeneration method of Pt-P2O5 electrolytic tank in hydrocarbon analyzer

Abstract

The invention relates to an activity regeneration method of a Pt-P2O5 electrolytic tank in a hydrocarbon analyzer. The method comprises the following steps: carrying out grinding pretreatment on a platinum wire electrode, and carrying out ultrasonic wave-composite acid organic solution combined cleaning on the platinum wire electrode; uniformly coating the inner surface of the electrolytic tank with a P2O5 film layer by adopting a film coating solution; and carrying out activity judgment on the electrolytic tank coated with the P2O5 film layer through electrolysis. By means of the steps, the effects of removing platinum black covering pollutants of the platinum wire electrode and evenly covering the inner surface of the electrolytic tank are efficiently achieved, the problems that the platinum wire electrode of the Pt-P2O5 electrolytic tank in a hydrocarbon analyzer cannot be cleaned thoroughly, and a P2O5 film layer is prone to failure are effectively solved, and the method has the advantages of restoring the electrolytic activity of the Pt-P2O5 electrolytic tank, greatly improving the accuracy of hydrocarbon content measurement and improving the quality of the hydrocarbon analyzer. The method has great guiding significance.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic cells, and in particular to an active regeneration method for a Pt-P2O5 electrolytic cell in a carbon hydrogen analyzer. Background Art

[0002] The carbon and hydrogen content in coal is of great significance for judging the degree of coal metamorphism and studying the properties of coal. In most coals, the carbon content accounts for 45% to 55%, and the hydrogen content accounts for 4% to 6%. The sum of the two accounts for about 60%. Carbon and hydrogen elements constitute important indicators of coal quality, and provide basic data for power generation and chemical enterprise equipment design, CO2 emission control, operation condition optimization, and CO2 emission reduction implementation. It can be seen that the efficient and accurate determination of the carbon and hydrogen content in coal has great guiding significance. At present, the analytical methods for determining the carbon and hydrogen content in coal mainly include the coulometric-weight method. The coulometric-weight method uses the coulometric electrolysis method to measure hydrogen and the gravimetric method to measure carbon. The water generated in the coulometric-weight method reacts with phosphorus pentoxide to generate metaphosphoric acid. According to the amount of electricity consumed by electrolyzing metaphosphoric acid, the hydrogen content of coal is calculated by integrating the Faraday's law of electrolysis. The generated carbon dioxide is absorbed by soda lime or soda asbestos, and the carbon content of coal is calculated by the increment of the absorbent U-shaped tube.

[0003] The Pt-P2O5 electrolytic cell in the coulometric-gravimetric carbon-hydrogen analyzer is composed of a glass tube with an outer diameter of 8 mm and a length of about 150 mm. Two 0.5 mm platinum wires are embedded in parallel in the tube, and the distance between the platinum wires is about 0.3 mm. The inner surface of the electrolytic cell is coated with phosphorus pentoxide, which can absorb water generated by hydrogen combustion and electrolyze it. After the Pt-P2O5 electrolytic cell completes the detection of about 100 coal samples, the two parallel platinum wire coils will produce platinum black attachments, which not only reduces the effective distance between the platinum wires, but also increases the slowness of the electrolytic reaction and increases the electrolytic power. When multiple sample tests are completed, the P2O5 film layer coated on the inner surface of the electrolytic cell will gradually become thinner or damaged, resulting in a low final measurement result. It can be seen that regular regeneration of the Pt-P2O5 electrolytic cell in the coulometric-gravimetric carbon-hydrogen analyzer is of great significance to improving the accuracy of the measurement results.

[0004] In the prior art, washing powder is mainly used to clean platinum wire to remove the platinum black produced on the surface of the platinum wire coil, and the electrolyte composed of phosphoric acid and acetone is blown dry by cold air to form a P2O5 film on the inner surface of the electrolytic cell to improve the activity of the Pt-P2O5 electrolytic cell. However, the platinum black produced by the platinum wire in the prior art is not cleaned thoroughly, and the P2O5 film formed on the inner surface of the electrolytic cell is easy to fall off and become ineffective, and the activity of the Pt-P2O5 electrolytic cell needs to be further improved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer, which can further improve the activity of the Pt-P2O5 electrolytic cell.

[0006] In order to achieve the above object, the present invention provides a method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer, the method comprising: Grinding the platinum wire electrode for pretreatment; and performing ultrasonic-composite acid organic solution combined cleaning on the platinum wire electrode after the grinding pretreatment; A coating liquid is used to evenly coat the inner surface of the electrolytic cell with a P2O5 film layer; The activity of the electrolytic cell coated with the P2O5 film layer is determined by electrolysis.

[0007] Optionally, the grinding pretreatment includes: using a composite alumina-based grinding liquid to grind the surface of the platinum wire electrode into a mirror surface, and the composite alumina-based grinding liquid includes 10-15% organic acid, 15-20% abrasive, 20-25% dispersant, 10-15% lubricant, and 25-45% water by mass fraction.

[0008] Optionally, the organic acid is one or both of aminoethanesulfonic acid and sulfosuccinic acid; the abrasive is aluminum oxide particles with a particle size of 20-50 mesh; the dispersant is sodium polyacrylate; and the lubricant is one or both of zinc dithiophosphate and phosphate ester.

[0009] Optionally, the composite acid organic solution includes, by mass fraction, 6-8% composite acid, 5-6% surfactant, 4-5% dispersant, and the balance water.

[0010] Optionally, the composite acid comprises, by mass fraction, 1-2% aqua regia and 5-6% EDTA-2Na, or 1-2% dichromic acid and 5-6% dilute nitric acid.

[0011] Optionally, the surfactant includes one or two of fatty acid glycerides, fatty acid sorbitan, and polysorbate.

[0012] Optionally, the dispersant includes one or two of triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, and fatty acid polyethylene glycol esters.

[0013] Optionally, the frequency of the ultrasound is 50±5kHz, and the ultrasound time is 45-60min.

[0014] Optionally, after the combined cleaning is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is infinite, the cleaning is complete.

[0015] Optionally, the uniform coating of the P2O5 film layer on the inner surface of the electrolytic cell includes: introducing a coating liquid into two-thirds of the total volume of the electrolytic cell, passing a direct current of 50-100 mA for continuous electrolysis for 5±1 min, draining the coating liquid, and standing for 60±10 min to uniformly coat the P2O5 film layer on the inner surface of the electrolytic cell.

[0016] Optionally, the coating liquid comprises phosphoric acid and acetone, and the molar ratio of the phosphoric acid to the acetone is (1-5):1; the mass fraction of the coating liquid is 10-15%.

[0017] Optionally, after the P2O5 film layer is evenly coated, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is 50-80Ω, the coating is qualified.

[0018] Optionally, judging the activity of the electrolytic cell coated with the P2O5 film layer includes: tilting the tail end of the electrolytic cell upward by 10-15° for electrolysis, repeating 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.

[0019] Through the above technical scheme, the present invention effectively achieves the effect of removing the platinum black covering pollutants of the platinum wire electrode and uniformly coating the inner surface of the electrolytic cell through the steps of platinum wire electrode grinding pretreatment, ultrasonic-composite acid organic solution combined cleaning, uniform coating of the P2O5 film layer, and electrolytic cell activity judgment. It effectively solves the problems of unclear cleaning of the platinum wire electrode of the Pt-P2O5 electrolytic cell and easy failure of the P2O5 film layer in the carbon hydrogen analyzer, and has important guiding significance for restoring the electrolytic activity of the Pt-P2O5 electrolytic cell and greatly improving the accuracy of carbon hydrogen content determination.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0022] The present invention provides a method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer, the method comprising: Grinding pretreatment of platinum wire electrode; Performing ultrasonic-composite acid organic solution combined cleaning on the platinum wire electrode after the grinding pretreatment; A coating liquid is used to evenly coat the inner surface of the electrolytic cell with a P2O5 film layer; The activity of the electrolytic cell coated with the P2O5 film layer is determined by electrolysis.

[0023] According to the present invention, optionally, the grinding pretreatment includes: using a composite alumina-based grinding liquid to grind the surface of the platinum wire electrode into a polished mirror surface, and the composite alumina-based grinding liquid includes 10-15% organic acid, 15-20% abrasive, 20-25% dispersant, 10-15% lubricant, and 25-45% water by mass fraction.

[0024] According to the present invention, optionally, the organic acid is one or both of aminoethanesulfonic acid and sulfosuccinic acid; the abrasive is aluminum oxide particles with a particle size of 20-50 mesh; the dispersant is sodium polyacrylate; and the lubricant is one or both of zinc dithiophosphate and phosphate ester.

[0025] According to the present invention, optionally, the composite acid organic solution comprises, by mass fraction, 6-8% composite acid, 5-6% surfactant, 4-5% dispersant, and the balance water.

[0026] According to the present invention, optionally, the composite acid comprises, by mass fraction, 1-2% aqua regia and 5-6% EDTA-2Na, or 1-2% dichromic acid and 5-6% dilute nitric acid.

[0027] According to the present invention, optionally, the surfactant includes one or two of fatty acid glycerides, fatty acid sorbitan, and polysorbate.

[0028] According to the present invention, optionally, the dispersant includes one or two of triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, and fatty acid polyethylene glycol esters.

[0029] According to the present invention, optionally, the ultrasonic-compound acid organic solution combined cleaning includes: using a brush to clean the electrolytic cell with a compound acid organic solution, and then placing it in an ultrasonic cleaner for ultrasonic cleaning, the ultrasonic frequency is 50±5kHz, and the ultrasonic time is 45-60min. When the present invention uses the compound acid organic solution for cleaning, the two-pole leads cannot be brushed, otherwise the electrolytic cell will be damaged.

[0030] According to the present invention, optionally, after the combined cleaning is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is infinite, the cleaning is complete.

[0031] According to the present invention, optionally, the uniform coating of the P2O5 film layer on the inner surface of the electrolytic cell includes: introducing the coating liquid into two-thirds of the total volume of the electrolytic cell, then resetting, passing a direct current of 50-100 mA for continuous electrolysis for 5±1 min, draining the coating liquid, and standing for 60±10 min to uniformly coat the P2O5 film layer on the inner surface of the electrolytic cell. The coating liquid includes phosphoric acid and acetone, and the molar ratio of the phosphoric acid to the acetone is (1-5):1; the mass fraction of the coating liquid is 10-15%. Through the above implementation, phosphoric acid can be converted into phosphorus pentoxide to form a P2O5 film layer on the inner surface of the electrolytic cell. Compared with the method of preparing the P2O5 film layer by cold air drying, the P2O5 film layer electrolytically coated by the present invention is not easy to fall off, has strong adhesion, is not easy to hydrolyze, does not produce wrinkles, has good stability, is not easy to fail, and can complete multiple sample tests.

[0032] According to the present invention, optionally, after the P2O5 film layer is evenly coated, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is 50-80Ω, the coating is qualified.

[0033] According to the present invention, optionally, the activity judgment of the electrolytic cell coated with the P2O5 film layer includes: tilting the tail end of the electrolytic cell upward by 10-15° for electrolysis, repeating 3-5 times until the electrolysis current is ≤70mA, and then the activity is judged to be qualified. The present invention adjusts the tail end of the electrolytic cell slightly upward to prevent the coating from moving backward or even moving out of the platinum wire area, resulting in a tailing phenomenon in which the electrolysis cannot reach the end point for a long time, thereby avoiding distortion of the measured value.

[0034] The present invention effectively removes the platinum black-covered pollutants of the platinum wire electrode and uniformly coats the inner surface of the electrolytic cell through the steps of platinum wire electrode grinding pretreatment, ultrasonic-composite acid organic solution combined cleaning, P2O5 film uniform coating, and electrolytic cell activity judgment, effectively solves the problems of unclean cleaning of the platinum wire electrode of the Pt-P2O5 electrolytic cell and easy failure of the P2O5 film in the carbon hydrogen analyzer, and has important guiding significance for restoring the electrolytic activity of the Pt-P2O5 electrolytic cell and greatly improving the accuracy of carbon and hydrogen content determination. The present invention can provide an important basis for studying the distribution law, occurrence state, CO2 emission control, operation condition optimization and CO2 emission reduction implementation of carbon and hydrogen content in medium fuels such as coal.

[0035] In a specific embodiment of the present invention, a method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer comprises: The platinum wire electrode is pre-treated by grinding, and the surface of the platinum wire electrode is ground into a mirror surface using a composite alumina-based grinding liquid; the composite alumina-based grinding liquid includes, by mass fraction, 10-15% of an organic acid, 15-20% of an abrasive, 20-25% of a dispersant, 10-15% of a lubricant, and 25-45% of water; the organic acid is one or both of aminoethanesulfonic acid and sulfosuccinic acid; the abrasive is alumina particles with a particle size of 20-50 mesh; the dispersant is sodium polyacrylate; and the lubricant is one or both of zinc dithiophosphate and phosphate; The platinum wire electrode after grinding pretreatment is subjected to ultrasonic-composite acid organic solution combined cleaning; the composite acid organic solution includes composite acid 6-8%, surfactant 5-6%, dispersant 4-5%, and water balance in terms of mass fraction; the composite acid includes aqua regia 1-2% and EDTA-2Na 5-6%, or dichromic acid 1-2% and dilute nitric acid 5-6%; the frequency of the ultrasonic wave is 50±5kHz, and the ultrasonic time is 45-60min; after the combined cleaning is completed, the resistance value between the platinum wire electrodes is measured using a multimeter, and if the display shows infinity, the cleaning is intact; The coating liquid is used to uniformly coat the inner surface of the electrolytic cell with a P2O5 film layer; the coating liquid is introduced into two-thirds of the total volume of the electrolytic cell, and then reset, a direct current of 50-100 mA is passed for continuous electrolysis for 5±1 minutes, the coating liquid is emptied, and the coating liquid is left to stand for 60±10 minutes to uniformly coat the inner surface of the electrolytic cell with a P2O5 film layer. The coating liquid includes phosphoric acid and acetone, and the molar ratio of the phosphoric acid to the acetone is (1-5):1; the mass fraction of the coating liquid is 10-15%; after the coating is completed, the resistance value between the platinum wire electrodes is measured using a multimeter, and if the display is 50-80Ω, the coating is qualified.

[0036] The activity of the electrolytic cell coated with the P2O5 film layer is judged by electrolysis; the tail end of the electrolytic cell is tilted upward by 10-15 degrees, and the coating key is pressed to perform electrolysis, which is repeated 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.

[0037] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0038] Example 1 A method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer comprises: The platinum wire electrode is pre-treated by grinding, and the surface of the platinum wire electrode is ground into a mirror surface using a composite alumina-based grinding liquid; the composite alumina-based grinding liquid includes, by mass fraction, 15% aminoethanesulfonic acid, 20% alumina, 25% sodium polyacrylate, 10% zinc dithiophosphate, and 30% water; The platinum wire electrode after grinding pretreatment is cleaned by ultrasonic-composite acid organic solution; in terms of mass fraction, the composite acid solution includes 1% aqua regia, 6% EDTA-2Na, 5% fatty acid glyceride, 5% dispersant composed of sodium dodecyl sulfate and triethylhexyl phosphoric acid in a molar ratio of 1:1, and 83% water; wherein the frequency of the ultrasonic wave is 50kHz, and the ultrasonic time is 50min; after the cleaning is completed, the resistance value between the platinum wire electrodes is measured by a multimeter, and if it is displayed as infinity, the cleaning is intact; A coating liquid is used to uniformly coat a P2O5 film layer on the inner surface of the electrolytic cell; phosphoric acid and acetone are mixed in a molar ratio of 2:1 to form a coating liquid, and the coating liquid is introduced into two-thirds of the total volume of the electrolytic cell, and then reset, a direct current of 60 mA is passed for continuous electrolysis for 5 minutes, the coating liquid is emptied, and the cell is left to stand for 60 minutes to uniformly coat the P2O5 film layer on the inner surface of the electrolytic cell; after the coating is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes, and if it is displayed as 60Ω, the coating is qualified.

[0039] The activity of the electrolytic cell coated with the P2O5 film layer is judged by electrolysis; the tail end of the electrolytic cell is tilted upward by 10°, and the coating key is pressed to perform electrolysis. This is repeated 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.

[0040] Example 2 A method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer comprises: The platinum wire electrode is pre-treated by grinding, and the surface of the platinum wire electrode is ground into a mirror surface using a composite alumina-based grinding liquid; the composite alumina-based grinding liquid includes 10% sulfosuccinic acid, 15% alumina, 25% sodium polyacrylate, 15% phosphate, and 35% water by mass fraction; The platinum wire electrode after grinding pretreatment is cleaned by ultrasonic-composite acid organic solution; in terms of mass fraction, the composite acid solution includes 1.5% aqua regia, 5% EDTA-2Na, 5% fatty acid glyceride, 5% dispersant composed of sodium dodecyl sulfate and triethylhexyl phosphoric acid in a molar ratio of 1:1, and 83.5% water; wherein the frequency of the ultrasonic wave is 45kHz, and the ultrasonic time is 60min; after the cleaning is completed, the resistance value between the platinum wire electrodes is measured by a multimeter, and if it is infinite, it means that the cleaning is intact; A coating liquid is used to uniformly coat a P2O5 film layer on the inner surface of the electrolytic cell; phosphoric acid and acetone are mixed in a molar ratio of 2:1 to form a coating liquid, and the coating liquid is introduced into two-thirds of the total volume of the electrolytic cell, and then reset, a direct current of 80 mA is passed for continuous electrolysis for 6 minutes, the coating liquid is emptied, and the cell is left to stand for 70 minutes to uniformly coat the P2O5 film layer on the inner surface of the electrolytic cell; after the coating is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes, and if it is displayed as 80Ω, the coating is qualified.

[0041] The activity of the electrolytic cell coated with the P2O5 film layer is judged by electrolysis; the tail end of the electrolytic cell is tilted upward by 10°, and the coating key is pressed to perform electrolysis. This is repeated 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.

[0042] Example 3 A method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer comprises: The platinum wire electrode is pre-treated by grinding, and the surface of the platinum wire electrode is ground into a mirror surface using a composite alumina-based grinding liquid; the composite alumina-based grinding liquid includes, by mass fraction, 15% aminoethanesulfonic acid, 20% alumina, 25% sodium polyacrylate, 10% zinc dithiophosphate, and 30% water; The platinum wire electrode after grinding pretreatment is cleaned by ultrasonic-composite acid organic solution; in terms of mass fraction, the composite acid organic solution includes 1% dichromic acid and 6% dilute nitric acid, 5% fatty acid glyceride, 5% dispersant composed of sodium dodecyl sulfate and triethylhexyl phosphoric acid in a molar ratio of 1:1, and 83% water; wherein the frequency of the ultrasonic wave is 50kHz, and the ultrasonic time is 50min; after cleaning, the resistance value between the platinum wire electrodes is measured with a multimeter, and if it is displayed as infinity, the cleaning is intact; A coating liquid is used to uniformly coat a P2O5 film layer on the inner surface of the electrolytic cell; phosphoric acid and acetone are mixed in a molar ratio of 2:1 to form a coating liquid, and the coating liquid is introduced into two-thirds of the total volume of the electrolytic cell, and then reset, a direct current of 60 mA is passed for continuous electrolysis for 5 minutes, the coating liquid is emptied, and the cell is left to stand for 60 minutes to uniformly coat the P2O5 film layer on the inner surface of the electrolytic cell; after the coating is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes, and if it is displayed as 50Ω, the coating is qualified.

[0043] The activity of the electrolytic cell coated with the P2O5 film layer is judged by electrolysis; the tail end of the electrolytic cell is tilted upward by 10°, and the coating key is pressed to perform electrolysis. This is repeated 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.

[0044] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0045] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0046] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for regenerating the activity of a Pt-P2O5 electrolytic cell in a carbon-hydrogen analyzer, characterized in that: The method includes: Grinding pretreatment of platinum wire electrode; Performing ultrasonic-composite acid organic solution combined cleaning on the platinum wire electrode after the grinding pretreatment; A coating liquid is used to evenly coat a P2O5 film layer on the inner surface of the electrolytic cell; The activity of the electrolytic cell coated with the P2O5 film layer is determined by electrolysis.

2. The method according to claim 1, wherein: The grinding pretreatment comprises: using a composite alumina-based grinding fluid to grind the surface of the platinum wire electrode into a mirror surface; In terms of mass fraction, the composite alumina-based grinding fluid includes 10-15% organic acid, 15-20% abrasive, 20-25% dispersant, 10-15% lubricant, and 25-45% water; The organic acid is one or both of aminoethanesulfonic acid and sulfosuccinic acid; the abrasive is aluminum oxide particles with a particle size of 20-50 meshes; the dispersant is sodium polyacrylate; and the lubricant is one or both of zinc dithiophosphate and phosphate ester.

3. The method according to claim 1, wherein: Calculated by mass fraction, the composite acid organic solution includes 6-8% composite acid, 5-6% surfactant, 4-5% dispersant, and the balance water; Calculated by mass fraction, the composite acid includes 1-2% aqua regia and 5-6% EDTA-2Na, or 1-2% dichromic acid and 5-6% dilute nitric acid.

4. The method according to claim 3, wherein: The surfactant includes one or two of fatty acid glyceride, fatty acid sorbitan, and polysorbate; The dispersant includes one or two of triethylhexyl phosphoric acid, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide, and fatty acid polyethylene glycol ester.

5. The method according to claim 1, wherein: The frequency of the ultrasonic wave is 50±5kHz, and the ultrasonic time is 45-60min.

6. The method according to claim 1, wherein: After the combined cleaning is completed, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is infinite, the cleaning is complete.

7. The method according to claim 1, wherein: The method of uniformly coating the P2O5 film layer on the inner surface of the electrolytic cell comprises: The coating liquid is introduced into two-thirds of the total volume of the electrolytic cell, and a direct current of 50-100 mA is passed for continuous electrolysis for 5±1 min. The coating liquid is drained and allowed to stand for 60±10 min to evenly coat the inner surface of the electrolytic cell with a P2O5 film layer.

8. The method according to claim 7, wherein: The coating liquid includes phosphoric acid and acetone, and the molar ratio of the phosphoric acid to the acetone is (1-5):1; the mass fraction of the coating liquid is 10-15%.

9. The method according to claim 7, wherein: After the P2O5 film layer is evenly coated, a multimeter is used to measure the resistance value between the platinum wire electrodes. If the resistance value displayed is 50-80Ω, the coating is qualified.

10. The method according to claim 1, wherein: The activity determination of the electrolytic cell coated with the P2O5 film layer includes: Tilt the tail end of the electrolytic cell upward by 10-15° for electrolysis, and repeat 3-5 times until the electrolysis current is ≤70mA, and the activity is judged to be qualified.