Electro-synthetic electronic-grade tetramethylammonium hydroxide double-titanium anode and unit tank

Abstract

The invention discloses an electro-synthetic electronic-grade tetramethylammonium hydroxide double-titanium anode and a unit cell. The double-titanium anode comprises a titanium anode I and a titanium anode II, the first titanium anode is of a rhombic stamping mesh structure, bears main current and has high electro-catalytic activity. And the titanium anode II is of a fan-shaped stretching mesh structure with higher aperture ratio, bears secondary current, forms a directional exhaust channel and has excellent bubble desorption and cavitation resistance. The coating is prepared by multi-layer coating, drying, oxidizing and sintering of coating liquid with a specific formula. According to the invention, the fan-shaped anodes effectively capture and guide away COs in an anode region, so that carbonate impurities in a cathode product are greatly reduced, and the purity of the product is improved; the bubble separation resistance is remarkably reduced by combining the high-opening structure with the air-repellent coating, and the electrolysis energy consumption is reduced; the current distribution, the activity and the durability are optimized through a partition coating strategy; and the near-membrane side anode can be independently replaced, the cost is low, and the existing equipment can be conveniently transformed.

Description

Technical Field

[0001] This invention relates to the field of anode unit cell application technology, specifically to an electrosynthesized electronic-grade tetramethylammonium hydroxide dual titanium anode and unit cell. Background Technology

[0002] In the field of high-end electronic chemical manufacturing, electronic-grade tetramethylammonium hydroxide (TMAH) is a core reagent in semiconductor etching processes. Trace amounts of carbonate impurities in TMAH can lead to residual development or excessive line edge roughness during the etching process. Currently, industrial production of electronic-grade TMAH primarily relies on the electrolytic process of tetramethylammonium bicarbonate (TMACO3). This process uses a cation exchange membrane to separate the anode and cathode chambers, with the cathode region generating the target product TMAH through electroreduction. However, the oxidation of bicarbonate ions generated at the anode continuously releases CO2 gas, accompanied by oxygen evolution side reactions. The resulting CO2 migrates and diffuses in the electrolytic environment, causing it to combine with the products at the cathode region, forming impurity compounds such as tetramethylammonium bicarbonate.

[0003] To address these issues, the industry has developed dual-anode electrolyzers in recent years. These electrolyzers create a physical isolation zone by adding an auxiliary anode chamber between the ion-exchange membrane and the main anode, aiming to prevent CO2 penetration into the cathode. However, this technology has significant limitations: both anodes typically use standardized titanium mesh substrates (such as uniform rhomboid stamping structures) and electrocatalytic coatings of the same composition (typically an IrO2-Ta2O5 mixture). This homogeneous design increases the anode area adjacent to the ion-exchange membrane and reduces energy consumption, but its dense mesh structure hinders bubble desorption, leading to a significant increase in local electrolyte resistance. Simultaneously, while the auxiliary anode region performs the actual gas collection function, its identical surface morphology and highly active coating to the main anode prevent it from achieving the desired effect commensurate with its precious metal content under low current density conditions. More importantly, the retention of bubbles in the auxiliary anode region still disrupts the gas-liquid two-phase flow, weakening the isolation effect.

[0004] The aforementioned defects collectively restrict the improvement of product purity and the economic efficiency of equipment operation. Therefore, there is an urgent need for a new dual-anode structure that can synergistically optimize reaction efficiency, gas management and electrode durability to meet the stringent requirements of high purity, low energy consumption and long-term stable operation of the electrosynthetic electronic-grade TMAH electrolyzer. Summary of the Invention

[0005] The purpose of this invention is to provide a dual titanium anode and unit cell for the electrosynthesis of electronic-grade tetramethylammonium hydroxide, so as to solve the problems of low product purity and high energy consumption caused by gas disturbance in the existing electrosynthesis of electronic-grade TMAH electrolytic cells.

[0006] To achieve the above objectives, the technical solution of the present invention is to design an electrosynthetic electronic-grade tetramethylammonium hydroxide dual titanium anode, wherein the dual titanium anode comprises titanium anode one and titanium anode two; The titanium anode has a surface coated with a first base layer, a first intermediate layer, and a first surface layer in sequence; wherein, the first base layer is an iridium titanium oxide coating; the first intermediate layer is an iridium titanium tin antimony oxide coating; and the first surface layer is an iridium tantalum oxide coating. The titanium anode is coated with a second bottom layer, a second intermediate layer and a second top layer in sequence on its two surfaces; wherein the second bottom layer is an iridium titanium oxide coating, the second intermediate layer is an iridium titanium tantalum platinum oxide coating, and the second top layer is an iridium manganese zirconium oxide coating.

[0007] Furthermore, the first titanium anode (far-film side) adopts a diamond-shaped mesh structure with an opening rate of 45-55%, preferably 50%; the second titanium anode (near-film side) adopts a fan-shaped mesh structure with an opening rate of 60-70%, preferably 65%.

[0008] Furthermore, the molar ratio of iridium to titanium in the first bottom layer of iridium titanium oxide coating is 1:(12-18), preferably 1:15; The molar ratio of iridium, titanium, tin and antimony in the iridium-titanium-tin-antimony oxide coating of the first intermediate layer is 1:(8-12):(14-18):1, preferably 1:10:16:1; The molar ratio of iridium to tantalum in the first surface iridium-tantalum oxide coating is (12-18):1, preferably 15:1.

[0009] Furthermore, the molar ratio of iridium to titanium in the second bottom layer iridium titanium oxide coating is 1:(12-18), preferably 1:15; The molar ratio of iridium, titanium, tantalum and platinum in the iridium-titanium-tantalum-platinum oxide coating of the second intermediate layer is (12-18):(140-160):1:1, preferably 15:150:1:1; The molar ratio of iridium, manganese and zirconium in the second surface iridium manganese zirconium oxide coating is (8-12):1:1, preferably 10:1:1.

[0010] A method for preparing an electrosynthetic electronic-grade tetramethylammonium hydroxide dual titanium anode, the preparation steps of which include: S1: Substrate treatment: After the titanium material is formed, it is sandblasted, pickled, washed and dried; S2: Coating solution preparation: Prepare coating solutions for titanium anode one and titanium anode two respectively; S3: Layered coating: Each coating in titanium anode one and titanium anode two is applied in layers, including the first bottom layer, the first intermediate layer, the second coating layer, and the second intermediate layer. After coating, they are dried at 100~120℃ for 10~15 minutes and oxidized at 480~490℃ for 10~20 minutes. After coating the first and second surface layers, dry at 100~120℃ for 10~15 minutes and oxidize at 480~490℃ for 40~60 minutes. Coating application repetitions: 2-3 times for both the first and second base coats, 4-6 times for the first intermediate coat, 2-3 times for the second intermediate coat, 3-5 times for the first top coat, and 1-2 times for the second top coat; S4: Sintering forms a metal oxide coating.

[0011] Furthermore, in step S2, the formulations of each coating are as follows, by weight: The first base coat consists of: 5-15 parts of chloroiridium acid, 150 parts of tetrabutyl titanate, 10-20 parts of acetylacetone, 40-60 parts of hydrochloric acid, and 800-1200 parts of n-butanol. The first intermediate coating solution includes: 5-15 parts of chloroiridium acid, 100 parts of tetrabutyl titanate, 12-20 parts of stannous octoate, 1 part of antimony chloride, 25-35 parts of acetylacetone, 40-60 parts of hydrochloric acid, and 500-1200 parts of n-butanol. The first surface coating solution includes: 10-30 parts of chloroiridium acid, 1 part of tantalum pentachloride, 20-40 parts of acetylacetone, 120-180 parts of hydrochloric acid, and 800-1200 parts of n-butanol; The second base coat consists of: 5-15 parts of chloroiridium acid, 150 parts of tetrabutyl titanate, 10-20 parts of acetylacetone, 40-60 parts of hydrochloric acid, and 800-1000 parts of n-butanol. The second intermediate coating solution includes: 10-20 parts of chloroiridium acid, 100-200 parts of tetrabutyl titanate, 1 part of tantalum pentachloride, 1 part of chloroplatinic acid, 20-40 parts of acetylacetone, 80-120 parts of hydrochloric acid, and 1400-1600 parts of n-butanol. The second surface coating solution includes: 5-15 parts of chloroiridium acid, 1 part of manganese chloride, 1 part of zirconium chloride, 10-30 parts of acetylacetone, 40-60 parts of hydrochloric acid, and 900-1100 parts of n-butanol.

[0012] Further, the coating preparation of titanium anode one: Titanium Anode - First Layer: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, a measured amount of the coating solution is applied evenly to the pre-treated diamond-shaped stamped titanium mesh using a brush. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 10-20 minutes. This coating-drying-oxidation process is repeated 2-3 times.

[0013] Titanium Anode - First Intermediate Layer: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, a measured amount of the coating solution is applied evenly to the surface of the diamond-shaped stamped titanium mesh containing the underlying coating using a brush. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 10-20 minutes. This coating-drying-oxidation process is repeated 4-6 times.

[0014] Titanium Anode - First Surface Layer: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, using a brush, a measured amount of the coating solution is evenly applied to the surface of the diamond-shaped stamped titanium mesh containing the base and intermediate coating layers. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 10-20 minutes. This coating-drying-oxidation process is repeated 3-5 times, with the high-temperature oxidation time for the final surface coating extended by 3-4 times.

[0015] Further, the coating preparation of titanium anode two Second layer of titanium anode: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, using a brush, a measured amount of the coating solution is evenly applied to the pre-treated fan-shaped stretched titanium mesh surface. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 10-20 minutes. This coating-drying-oxidation process is repeated 2-3 times.

[0016] Second intermediate layer of titanium anode: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, a measured amount of the coating solution is applied evenly to the surface of the fan-shaped stretched titanium mesh containing the underlayer coating using a brush. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 10-20 minutes. This coating-drying-oxidation process is repeated 2-3 times.

[0017] Second surface layer of titanium anode: The prepared coating solution is ultrasonically or stirred for 30-90 minutes. Then, a measured amount of the coating solution is applied evenly to the surface of the fan-shaped stretched titanium mesh containing the intermediate coating layer using a brush. After coating, the titanium mesh is placed in an oven and dried at 100-120℃ for 10-15 minutes. Finally, it is transferred to a high-temperature furnace and oxidized at 480-490℃ for 40-60 minutes. This coating-drying-oxidation process is performed only once.

[0018] Preferably, the titanium substrate of titanium anode one uses a diamond-shaped stamped titanium mesh with an opening rate of 50%, and is used after sandblasting, degreasing, pickling, water washing and drying. Preferably, the substrate of the second titanium anode uses a fan-shaped stretched mesh with an opening rate of 65%, and is prepared for use after sandblasting, degreasing, pickling, water washing, and drying. A unit cell for electrosynthesizing electronic-grade tetramethylammonium hydroxide, the unit cell comprising a dual titanium anode, wherein the dual titanium anode is the aforementioned electrosynthesizing electronic-grade tetramethylammonium hydroxide dual titanium anode, or a dual titanium anode prepared by the aforementioned preparation method.

[0019] Furthermore, the unit groove includes a groove body, a conductive post, and a sealing gasket. The dual titanium anode includes titanium anode one, titanium anode two, and an anode assembly. The anode assembly has conductive column grooves and anode mounting grooves. The dual titanium anodes are symmetrically welded to the anode mounting grooves by titanium anode one and titanium anode two. The groove is provided with conductive post holes; The anode is installed in the tank through conductive posts, through conductive post holes and conductive post grooves.

[0020] Furthermore, an inlet is provided on one side of the bottom of the tank, and an outlet is provided on the top of the other side of the tank opposite to the inlet; The tank body has an inlet and outlet liquid distribution port on the end wall connecting to the inlet and the outlet liquid distribution port on the end wall connecting to the outlet.

[0021] The conductive post is threaded to the tank body, and the sealing gasket is made of PTFE or PTFE / fluororubber composite material.

[0022] The advantages and beneficial effects of this invention are as follows: (1) The present invention provides a dual titanium anode and unit cell for electrosynthesis of electronic grade tetramethylammonium hydroxide, wherein a directional exhaust channel is constructed by providing a fan-shaped stretched mesh anode (titanium anode two) on the near-membrane side, and combined with the strong reactivity of the diamond-shaped stamped mesh anode (titanium anode one) on the far-membrane side, so that CO2 generated in the anode area is immediately captured and guided away from the ion membrane area, the carbonate impurity content in the cathode chamber product is greatly reduced, and CO2 backmixing pollution can be effectively blocked to generate high-purity products; (2) The present invention provides a dual titanium anode and unit cell for electrosynthesizing electronic grade tetramethylammonium hydroxide, wherein the opening ratio of the near-film side fan-shaped mesh anode (titanium anode two) is higher than that of the far-film side rhombic mesh anode (titanium anode one), and the outer titanium mesh gas-repellent coating significantly reduces the resistance to bubble detachment and reduces the energy consumption of the electrolytic cell. (3) The present invention provides a dual titanium anode and unit cell for electrosynthesizing electronic-grade tetramethylammonium hydroxide, which is characterized by a partitioned coating strategy: the bottom layer of the far-film side diamond-shaped stamped mesh anode (titanium anode one) is an iridium titanium oxide coating to enhance the bonding force with the substrate, the middle layer contains a tin antimony oxide coating to enhance conductivity, and the surface layer contains an iridium tantalum oxide tantalum coating to focus on high activity; the bottom layer of the near-film side fan-shaped stretched mesh anode (titanium anode two) is an iridium titanium oxide coating to enhance the bonding force with the substrate, the middle layer is an iridium titanium tantalum platinum oxide to improve cavitation resistance and enhance durability, and the surface layer contains a small amount of manganese zirconium oxide to accelerate bubble desorption and reduce the local resistance of the electrolyte; (4) The present invention provides a dual titanium anode and unit cell for electrosynthesizing electronic-grade tetramethylammonium hydroxide, wherein the diamond-shaped stamped mesh anode (titanium anode one) on the far-film side bears about 70% of the current, which plays the role of matching the high-activity coating with the high reaction load; the fan-shaped stretched mesh anode (titanium anode two) on the near-film side matches about 30% of the current, which plays the role of adapting the high-opening structure to gas treatment, thus eliminating the contradiction of homogeneous current distribution in traditional dual anodes; (5) The present invention provides a dual titanium anode and unit cell for electrosynthesizing electronic grade tetramethylammonium hydroxide, wherein the near-film side fan-shaped stretched mesh anode (titanium anode two) can be replaced independently, and the cost is lower than that of the far-film side rhomboid stamped mesh anode (titanium anode one). Furthermore, by replacing the electrode assembly, it is compatible with the existing dual anode electrolytic cell structure, and the modification cost is lower than the investment in new equipment.

[0023] (6) The present invention provides a dual titanium anode and unit cell for electrosynthesizing electronic grade tetramethylammonium hydroxide. By setting up dual anodes and differentiating the dual anode structure and surface coating, the present invention achieves the purpose of accelerating bubble desorption, increasing reaction area, improving product purity, and reducing energy consumption.

[0024] (7) In this invention, titanium anode one (far-film side) has a rhombic stamped mesh structure, coated with an iridium-titanium-tin-antimony-tantalum metal oxide coating, which carries the main current and has high electrocatalytic activity; titanium anode two (near-film side) has a fan-shaped stretched mesh structure with higher porosity, coated with an iridium-titanium-tantalum-platinum-manganese-zirconium metal oxide coating, which carries the secondary current, forms a directional exhaust channel and has excellent bubble desorption and anti-cavitation performance. The coating is prepared by multi-layer coating, drying and oxidative sintering of a specific formulation of coating solution. This invention effectively captures and guides CO2 away from the anode area through the fan-shaped anode, significantly reducing carbonate impurities in the cathode product and improving product purity; the high porosity structure combined with the gas-repellent coating significantly reduces bubble detachment resistance and reduces electrolysis energy consumption; the partitioned coating strategy optimizes current distribution, activity and durability; the near-film side anode can be replaced independently, with low cost and easy modification of existing equipment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a titanium anode and unit cell for the electrosynthesis of tetramethylammonium hydroxide according to the present invention; Figure 2 This is a schematic diagram of the electrosynthesis of tetramethylammonium hydroxide titanium anode and the anode decomposition in the unit cell according to the present invention; Figure 3 This is a schematic diagram of a titanium anode for the electrosynthesis of tetramethylammonium hydroxide and the tank body in a unit cell according to the present invention; Figure 4 This is a schematic diagram of the electrosynthesis of tetramethylammonium hydroxide titanium anode and the assembly of anode, conductive column and sealing gasket in unit cell according to the present invention; Figure 5 This is a scanning electron microscope (SEM) image of the surface of titanium anode one in Example 1; Figure 6 This is a scanning electron microscope (SEM) image of the surface of titanium anode two in Example 1; Figure 7 This is a water contact angle diagram of titanium anode one in Example 1; Figure 8 This is a water contact angle diagram of titanium anode two in Example 1; Figure 9 This is a diagram of the water-air contact angle of titanium anode two in Example 1.

[0026] In the diagram: 1. Double titanium anodes, 2. Tank body, 3. Conductive column, 4. Sealing gasket, 11. Titanium anode one, 12. Titanium anode two, 13. Anode assembly, 131. Conductive column groove, 132. Anode mounting groove, 21. Tank body flange face, 22. Conductive column hole, 23. Liquid inlet, 231. Liquid inlet distribution port, 24. Liquid outlet, 241. Liquid outlet distribution port. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0028] (I) Implementation Examples Example 1: A method for preparing an electrosynthetic electronic-grade tetramethylammonium hydroxide dual titanium anode, the preparation steps of which include: S1: Pretreatment of titanium substrate 1) The titanium plate is processed into diamond-shaped stamped titanium mesh and fan-shaped stretched titanium mesh. The diamond-shaped stamped titanium mesh has a flat surface and an opening rate of 50%. The fan-shaped stretched titanium mesh does not undergo a pressing operation after stretching, and the surface texture needs to be maintained with an opening rate of 65%.

[0029] 2) After sandblasting with brown fused alumina and rinsing clean, the titanium mesh is degreased in a 5% (w / w) sodium hydroxide solution at 85°C for 30 minutes. After removal, it is washed and dried. Then it is immersed in a 0.4M oxalic acid solution and acid-washed at 80°C for 20 minutes. After removal, it is washed and dried for later use.

[0030] S2: Preparation of coating solution Different coating solutions are used on titanium anode one and titanium anode two: 1) The titanium anode coating consists of three layers, each corresponding to a different coating solution, and each coating solution is applied a certain number of times.

[0031] The first bottom coating solution for the titanium anode is prepared as follows: 10 parts chloroiridium acid, 150 parts tetrabutyl titanate, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol. The first intermediate coating solution is prepared as follows: 10 parts chloroiridium acid, 100 parts tetrabutyl titanate, 16 parts stannous octoate, 1 part antimony chloride, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The first surface coating solution is prepared as follows: 15 parts chloroiridium acid, 1 part tantalum pentachloride, 30 parts acetylacetone, 150 parts hydrochloric acid, and 1000 parts n-butanol. Each prepared coating solution is ultrasonicated or stirred for 60 minutes and then set aside.

[0032] 2) The titanium anode second coating is also three layers, each layer corresponds to a coating liquid, and each coating liquid is applied a number of times.

[0033] The second bottom coating solution for titanium anode is prepared as follows: 10 parts chloroiridium acid, 150 parts tetrabutyl titanate, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol. The second intermediate coating solution is prepared as follows: 15 parts chloroiridium acid, 150 parts tetrabutyl titanate, 1 part tantalum pentachloride, 1 part chloroplatinic acid, 30 parts acetylacetone, 100 parts hydrochloric acid and 1500 parts n-butanol. The second surface coating solution is prepared as follows: 10 parts chloroiridium acid, 1 part manganese chloride, 1 part zirconium chloride, 15 parts acetylacetone, 50 parts hydrochloric acid, and 1000 parts n-butanol. Each prepared coating solution is ultrasonicated or stirred for 60 minutes and then set aside.

[0034] S3: Coating application and oxidation 1) Coating and oxidation of titanium anode one: Using a brush, apply a measured amount of the first base coat solution evenly to the pretreated diamond-shaped stamped titanium mesh surface. After coating, place the titanium mesh in an oven and dry at 120°C for 10 minutes. Finally, transfer it to a high-temperature furnace and oxidize at 480°C for 15 minutes. Repeat this coating-drying-oxidation process twice.

[0035] Using a brush, apply a measured amount of the first intermediate layer coating liquid evenly to the surface of the diamond-shaped stamped titanium mesh containing the bottom layer coating. After coating, place the titanium mesh in an oven and dry it at 120°C for 10 minutes. Finally, transfer it to a high-temperature furnace and oxidize it at 480°C for 15 minutes. This coating-drying-oxidation operation is repeated 4 times.

[0036] Using a brush, apply a measured amount of the first surface coating solution evenly to the surface of the diamond-shaped stamped titanium mesh containing the base and intermediate coating layers. After coating, place the titanium mesh in an oven and dry it at 120°C for 15 minutes. Finally, transfer it to a high-temperature furnace and oxidize it at 480°C for 15 minutes. This coating-drying-oxidation process is repeated three times, with the final surface coating undergoing a high-temperature oxidation time of 40 minutes.

[0037] 2) Coating and oxidation of titanium anode 2: Using a brush, apply a measured amount of the second base coat solution evenly to the pretreated fan-shaped stretched titanium mesh surface. After coating, place the titanium mesh in an oven and dry at 120°C for 10 minutes. Finally, transfer it to a high-temperature furnace and oxidize at 480°C for 15 minutes. Repeat this coating-drying-oxidation process twice.

[0038] Using a brush, apply a measured amount of the second intermediate layer evenly to the surface of the fan-shaped stretched titanium mesh containing the base layer. After coating, place the titanium mesh in an oven and dry it at 120°C for 10 minutes. Finally, transfer it to a high-temperature furnace and oxidize it at 480°C for 15 minutes. Repeat this coating-drying-oxidation process twice.

[0039] Using a brush, apply a measured amount of the second surface coating solution evenly to the surface of the fan-shaped stretched titanium mesh containing the intermediate coating layer. After coating, place the titanium mesh in an oven and dry it at 120°C for 10 minutes. Finally, transfer it to a high-temperature furnace and oxidize it at 480°C for 40 minutes. This coating-drying-oxidation process is performed only once.

[0040] Example 2: Compared with Example 1, the difference lies in the preparation of the first bottom coating solution of titanium anode one as follows: 5 parts chloroiridium acid, 150 parts tetrabutyl titanate, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0041] Example 3: Compared with Example 1, the difference lies in the preparation of the first bottom coating solution of titanium anode one as follows: 15 parts chloroiridium acid, 150 parts tetrabutyl titanate, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0042] Example 4: Compared with Example 1, the difference lies in the preparation of the first intermediate coating solution of titanium anode one as follows: 5 parts chloroiridium acid, 100 parts tetrabutyl titanate, 16 parts stannous octoate, 1 part antimony chloride, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The other preparation methods are the same as in Example 1.

[0043] Example 5: Compared with Example 1, the difference lies in the preparation of the first intermediate layer coating solution of titanium anode one as follows: 15 parts chloroiridium acid, 100 parts tetrabutyl titanate, 16 parts stannous octoate, 1 part antimony chloride, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The other preparation methods are the same as in Example 1.

[0044] Example 6: Compared with Example 1, the difference lies in the preparation of the first intermediate layer coating solution of titanium anode one as follows: 10 parts chloroiridium acid, 100 parts tetrabutyl titanate, 12 parts stannous octoate, 1 part antimony chloride, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The other preparation methods are the same as in Example 1.

[0045] Example 7: Compared with Example 1, the difference lies in the preparation of the first intermediate coating solution of the titanium anode: 10 parts chloroiridium acid, 100 parts tetrabutyl titanate, 20 parts stannous octoate, 1 part antimony chloride, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The other preparation methods are the same as in Example 1.

[0046] Example 8: Compared with Example 1, the difference lies in the preparation of the first surface coating solution of titanium anode one as follows: 10 parts chloroiridic acid, 1 part tantalum pentachloride, 30 parts acetylacetone, 150 parts hydrochloric acid and 1200 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0047] Example 9: Compared with Example 1, the difference lies in the preparation of the first surface coating solution of titanium anode one as follows: 30 parts chloroiridic acid, 1 part tantalum pentachloride, 30 parts acetylacetone, 150 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0048] Example 10: Compared with Example 1, the difference lies in the preparation of the second intermediate layer coating solution of titanium anode 2: 10 parts chloroiridic acid, 150 parts tetrabutyl titanate, 1 part tantalum pentachloride, 1 part chloroplatinic acid, 30 parts acetylacetone, 100 parts hydrochloric acid and 1500 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0049] Example 11: Compared with Example 1, the difference lies in the preparation of the second intermediate layer coating solution of titanium anode 2: 20 parts chloroiridic acid, 150 parts tetrabutyl titanate, 1 part tantalum pentachloride, 1 part chloroplatinic acid, 30 parts acetylacetone, 100 parts hydrochloric acid and 1500 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0050] Example 12: Compared with Example 1, the difference lies in the preparation of the second surface coating solution of titanium anode 2: 5 parts chloroiridic acid, 1 part manganese chloride, 1 part zirconium chloride, 30 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0051] Example 13: Compared with Example 1, the difference lies in the preparation of the second surface coating solution of titanium anode 2: 15 parts chloroiridic acid, 1 part manganese chloride, 1 part zirconium chloride, 30 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0052] Comparative Example 1: Compared with Example 1, the difference lies in the preparation of the first intermediate coating solution of titanium anode one as follows: 10 parts chloroiridium acid, 100 parts tetrabutyl titanate, 16 parts stannous octoate, 30 parts acetylacetone, 50 parts hydrochloric acid, and 1200 parts n-butanol. The other preparation methods are the same as in Example 1.

[0053] Comparative Example 2: Compared with Example 1, the difference lies in the preparation of the first surface coating solution of titanium anode one: 15 parts chloroiridium acid, 30 parts acetylacetone, 150 parts hydrochloric acid and 1000 parts n-butanol, while the other preparation methods are the same as in Example 1.

[0054] Comparative Example 3: Compared with Example 1, the difference lies in the preparation of the second intermediate layer coating solution of titanium anode 2: 15 parts chloroiridium acid, 150 parts tetrabutyl titanate, 1 part chloroplatinic acid, 30 parts acetylacetone, 100 parts hydrochloric acid and 1500 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0055] Comparative Example 4: Compared with Example 1, the difference lies in the preparation of the second intermediate layer coating solution of titanium anode 2: 15 parts chloroiridic acid, 150 parts tetrabutyl titanate, 1 part tantalum pentachloride, 30 parts acetylacetone, 100 parts hydrochloric acid and 1500 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0056] Comparative Example 5: Compared with Example 1, the difference lies in the preparation of the second surface coating solution of titanium anode 2: 10 parts chloroiridic acid, 1 part zirconium chloride, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, and the other preparation methods are the same as in Example 1.

[0057] Comparative Example 6: Compared with Example 1, the difference lies in the preparation of the second surface coating solution of titanium anode 2: 10 parts chloroiridic acid, 1 part manganese chloride, 15 parts acetylacetone, 50 parts hydrochloric acid and 1000 parts n-butanol, while the other preparation methods are the same as in Example 1.

[0058] (ii) Performance Testing (1) Electrode oxygen evolution potential test Electrode potential measurements were performed using a three-electrode system, with a platinum sheet as the auxiliary electrode. The reference electrode was a 1 M KOH / HgO electrode with a double salt bridge and an L-shaped Luggin capillary, with the capillary opening 0.1 mm from the working electrode. The electrolyte was a mixture of 0.5 M TMAH and 1 M NaOH in a 2:1 volume ratio. Linear sweep voltammetry (LSV) was used to measure the potential at a scan rate of 10 mV / s within the test voltage range of 0.5–1.2 V, at a test temperature of 25 ± 1 °C. The measured value was 250 mA / cm². 2 The corresponding potential E vsHg / HgO@25℃.

[0059] The test results are shown in the table below: (2) Water contact angle test Electrode water contact angle and water-air contact angle tests: The hydrophilic / hydrophobic properties of the electrode surface were characterized using an optical contact angle meter. The cleaned sample was fixed on the sample stage of the contact angle meter, ensuring the surface was horizontal. 5 μL of deionized water was drawn up using a microsyringe and slowly added dropwise to the center of the sample surface. After waiting 10–30 seconds, an image of the water droplet was captured using the instrument's built-in high-speed camera.

[0060] The gas-repellent properties of the electrode surface in water were characterized using an optical contact angle meter (including an underwater test cell). The sample was fixed in the underwater test cell and completely immersed in deionized water. 2 μL of gas was drawn up using a micro-gas injector and slowly released into the gas bubble 1 mm directly below the sample surface. After waiting 10–30 seconds, an image of the bubble on the sample surface was captured using a high-speed camera.

[0061] The test results are shown in the table below: sample Water contact angle (°) Air-water contact angle (°) Titanium anode in Example 1 80 — Titanium anode 2 in Example 1 136 128 (3) Accelerated Life Test The prepared anode unit cell, with a nickel wire mesh containing platinum oxide as the cathode, was subjected to accelerated life enhancement testing. The current density during the test was 4 kA / m², the solution system was 1 mol / L NaOH + 0.5 mol / L Na₂CO₃ solution to simulate the electrolyte composition in actual electrolysis, and the temperature was 60 ± 2 ℃.

[0062] The test results are shown in the table below: Example 1: Titanium Anode Cumulative accelerated lifespan (h) Rise 1 V 1092 Rise 2 V 1275 Rise 3 V 1426 Rise 4 V 1589 Rise 5 V 1643 Titanium Anode Cumulative accelerated lifespan (h) Example 1 1643 Example 6 1525 Example 7 1269 Example 8 1370 Example 9 1802 (4) Determination of impurity content in electrolytic cell products in Example 1 The concentrations (ppb) of metal ions (K, Ca, Na, Mg, Fe, Zn) were determined using inductively coupled plasma mass spectrometry (ICP-MS). The carbonate concentration (ppb) was determined using ion chromatography (IC). The specific test results are shown in the table below. Impurity type K Ca Na Mg Fe Zn <![CDATA[CO3 2- ]]> Content / ppb 0.92 0.85 1.15 0.79 1.02 0.71 16000 This invention achieves a significant technological breakthrough in the electrosynthesis of electronic-grade tetramethylammonium hydroxide through an innovative dual-titanium anode structure design and a zoned coating strategy. The directional exhaust channel design of the near-film side fan-shaped stretched mesh anode (titanium anode two), combined with the high reactivity of the far-film side diamond-shaped stamped mesh anode (titanium anode one), effectively reduces the carbonate impurity content (16000 ppb) in the cathode chamber product, reducing CO2 backmixing contamination and thus improving product purity. The high porosity and gas-repellent coating of titanium anode two (136° water contact angle, 128° gas contact angle) significantly reduce bubble removal resistance and optimize the energy consumption performance of the electrolyzer. The zoned coating strategy further enhances anode performance. Titanium anode one employs an iridium-titanium-tin-antimony-iridium-tantalum gradient coating, balancing conductivity and catalytic activity, exhibiting excellent durability (up to 1802 hours) in accelerated life testing, while the iridium-titanium-tantalum-platinum-manganese-zirconium coating of titanium anode two strengthens cavitation resistance and promotes bubble desorption. In terms of current distribution, titanium anode one bears 70% of the current load and is matched with a highly active coating, while titanium anode two focuses on gas handling. Their synergistic operation avoids the homogeneity issues inherent in traditional dual-anode systems. Potential data (titanium anode one 0.806 V, titanium anode two 0.912 V) show good compatibility. Furthermore, the independent replaceable design of titanium anode two reduces maintenance costs and is compatible with existing electrolytic cell structures, resulting in low modification costs and outstanding economic efficiency. In summary, the technical solution described in this invention demonstrates significant advantages in product purity, energy consumption optimization, electrode lifespan, and economic efficiency, providing a reliable solution for the efficient electrosynthesis of electronic-grade tetramethylammonium hydroxide.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electro-synthesis of electronic grade tetramethylammonium hydroxide double titanium anode, characterized by, The double titanium anode comprises a titanium anode one and a titanium anode two; The titanium anode one is coated with a first bottom layer, a first intermediate layer and a first surface layer in sequence; the first bottom layer is an iridium titanium oxide coating layer; the first intermediate layer is an iridium titanium tin antimony oxide coating layer; and the first surface layer is an iridium tantalum oxide coating layer; The titanium anode two is coated with a second bottom layer, a second intermediate layer and a second surface layer in sequence; the second bottom layer is an iridium titanium oxide coating layer; the second intermediate layer is an iridium titanium tantalum platinum oxide coating layer; and the second surface layer is an iridium manganese zirconium oxide coating layer.

2. An electro-synthesis of electronic grade tetramethylammonium hydroxide double titanium anode according to claim 1, characterized by, The titanium anode one adopts a rhombic mesh structure with an opening rate of 45-55%; and the titanium anode two adopts a fan-shaped mesh structure with an opening rate of 60-70%.

3. The double titanium anode for electro-synthesis of electronic-grade tetramethylammonium hydroxide according to claim 2, characterized in that, The molar ratio of iridium to titanium in the iridium titanium oxide coating layer of the first bottom layer is 1:(12-18); The molar ratio of iridium, titanium, tin and antimony in the iridium titanium tin antimony oxide coating layer of the first intermediate layer is 1:(8-12):(14-18):1; The molar ratio of iridium to tantalum in the iridium tantalum oxide coating layer of the first surface layer is (12-18):

1.

4. The double titanium anode for electro-synthesis of electronic-grade tetramethylammonium hydroxide according to claim 3, characterized in that, The molar ratio of iridium to titanium in the iridium titanium oxide coating layer of the second bottom layer is 1:(12-18); The molar ratio of iridium, titanium, tantalum and platinum in the iridium titanium tantalum platinum oxide coating layer of the second intermediate layer is (12-18):(140-160):1:1; The molar ratio of iridium, manganese and zirconium in the iridium manganese zirconium oxide coating layer of the second surface layer is (8-12):1:

1.

5. A method for the production of an electro-synthetic electronic grade tetramethylammonium hydroxide double titanium anode as claimed in any one of claims 1 to 4, characterized in that, The preparation steps include: S1: substrate treatment: after the titanium material is formed, it is subjected to sand blasting, acid pickling, water washing and drying; S2: coating liquid preparation: the coating liquid of each coating layer of the titanium anode one and the titanium anode two is prepared in a certain proportion; S3: layered coating: each coating layer in the titanium anode one and the titanium anode two is coated in layers, wherein the first bottom layer, the first intermediate layer, the second coating layer and the second intermediate layer are dried at 100-120℃ for 10-15 minutes and oxidized at 480-490℃ for 10-20 minutes after coating; The first surface layer and the second surface layer are dried at 100-120℃ for 10-15 minutes and oxidized at 480-490℃ for 40-60 minutes after coating; The number of coating layer coating repetitions: the first bottom layer and the second bottom layer are 2-3 times, the first intermediate layer is 4-6 times, the second intermediate layer is 2-3 times, the first surface layer is 3-5 times, and the second surface layer is 1-2 times; S4: sintering to form a metal oxide coating layer.

6. The method of claim 5, wherein the method is characterized by: In step S2, the formula of each coating layer is as follows in terms of weight parts: The first bottom layer coating liquid comprises 5-15 parts of chloroiridic acid, 150 parts of butyl titanate, 10-20 parts of acetylacetone, 40-60 parts of hydrochloric acid and 800-1200 parts of n-butanol; The first intermediate layer coating liquid comprises 5-15 parts of chloroiridic acid, 100 parts of butyl titanate, 12-20 parts of stannous octoate, 1 part of antimony chloride, 25-35 parts of acetylacetone, 40-60 parts of hydrochloric acid and 500-1200 parts of n-butanol; The second bottom layer coating liquid comprises 5-15 parts of chloroiridic acid, 150 parts of butyl titanate, 10-20 parts of acetylacetone, 40-60 parts of hydrochloric acid and 800-1200 parts of n-butanol; The second intermediate layer coating liquid comprises 5-15 parts of chloroiridic acid, 100 parts of butyl titanate, 12-20 parts of stannous octoate, 1 part of antimony chloride, 25-35 parts of acetylacetone, 40-60 parts of hydrochloric acid and 500-1200 parts of n-butanol; The first surface layer coating solution comprises 10-30 parts of chloroiridic acid, 1 part of pentachloride, 20-40 parts of acetylacetone, 120-180 parts of hydrochloric acid and 800-1200 parts of n-butanol; The second bottom layer coating solution comprises 5-15 parts of chloroiridic acid, 150 parts of butyl titanate, 10-20 parts of acetylacetone, 40-60 parts of hydrochloric acid and 800-1000 parts of n-butanol; The second intermediate layer coating solution comprises 10-20 parts of chloroiridic acid, 100-200 parts of butyl titanate, 1 part of pentachloride, 1 part of chloroplatinic acid, 20-40 parts of acetylacetone, 80-120 parts of hydrochloric acid and 1400-1600 parts of n-butanol; The second surface layer coating solution comprises 5-15 parts of chloroiridic acid, 1 part of manganese chloride, 1 part of zirconium chloride, 10-30 parts of acetylacetone, 40-60 parts of hydrochloric acid and 900-1100 parts of n-butanol.

7. An electro-synthetic cell for the production of electronic grade tetramethylammonium hydroxide, characterized in that, The unit cell comprises a double-titanium anode (1) prepared by any one of claims 1-4 or prepared by the preparation method of claims 5-6.

8. An electro-synthesis cell for the production of electronic grade tetramethylammonium hydroxide according to claim 7, characterized in that, The unit cell further comprises a cell body (2), a conductive column (3) and a sealing gasket (4), The double-titanium anode (1) comprises a titanium anode one (11), a titanium anode two (12) and an anode assembly (13), the anode assembly (13) is provided with a conductive column groove (131) and an anode mounting groove (132), and the double-titanium anode is symmetrically welded in the anode mounting groove (132) by the titanium anode one (11) and the titanium anode two (12); The cell body (2) is provided with a conductive column hole (22); The anode (1) is installed in the cell body through the conductive column (3) penetrating the conductive column hole (22) and the conductive column groove (131).

9. An electro-synthetic unit cell for the synthesis of electronic grade tetramethylammonium hydroxide according to claim 8, wherein, One side of the bottom of the cell body (2) is provided with a liquid inlet (23), and the other side of the top of the cell body (2) opposite to the liquid inlet (23) is provided with a liquid outlet (24).

10. An electro-synthetic unit cell for the production of electronic grade tetramethylammonium hydroxide according to claim 9, wherein, The cell body (2) is provided with a liquid inlet and distribution port (231) on the end wall connected with the liquid inlet (23), and the cell body (2) is provided with a liquid outlet and distribution port (241) on the end wall connected with the liquid outlet (24).

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