Method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis

Abstract

The invention discloses a method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis, and belongs to the field of preparation of tetramethylammonium hydroxide. The method comprises the following steps: based on an electrodialysis device with a bipolar membrane electrodialysis membrane stack, adding a tetramethyl ammonium halide solution into a material chamber, adding water or an acid solution corresponding to tetramethyl ammonium halide into an acid chamber, adding water or a tetramethyl ammonium hydroxide solution into an alkali chamber, and adding a tetramethyl ammonium hydroxide solution into an electrode water chamber; concentrating a product obtained in the material chamber by adopting a reverse osmosis technology, and then adding the concentrated product into the material chamber in the electrodialysis device again to serve as a starting solution. According to the method, impurity ions in TMAH can be effectively reduced, and high-purity TMAH can be prepared at low cost; meanwhile, the production of industrial wastewater and waste gas is reduced to a great extent, and the preparation method is green, environment-friendly and safe.

Description

Technical Field

[0001] The invention belongs to the field of tetramethylammonium hydroxide preparation, and particularly relates to a method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis. Background Art

[0002] The developer can remove the exposed area of ​​the photoresist material after the photoresist material is exposed to light, thereby forming a complex pattern on the semiconductor wafer. At present, the popularization of electronic devices and technological advances (such as 5G and the Internet of Things) have driven the growing demand for semiconductors, thereby driving the development of the developer market. Tetramethylammonium hydroxide (hereinafter referred to as TMAH) is a strong alkaline chemical substance with strong corrosiveness. It is usually used as an alkaline developer and is the main source of developer. At present, the main methods for preparing TMAH are silver chloride method, ion exchange resin method, alkali replacement method and electrolysis method. Among them, most of the domestic production of TMAH uses the silver chloride method, that is, tetramethylammonium chloride and silver oxide are used to react to generate TMAH, but the reaction raw materials are expensive, and trace silver ions will be mixed into the product to affect the quality of TMAH. Adding a tetramethylammonium salt solution to an excess of calcium hydroxide suspension can also react to generate TMAH, but too many impurities are introduced during the reaction, which also reduces the purity of the product. The ion exchange resin method uses tetramethylammonium halide as raw material to produce TMAH, but the anion exchange resin and sodium hydroxide used in this method will introduce more impurities, and the quality of the product produced is not high. The emerging ion membrane electrolysis method uses a combination of electrolysis and ion membrane to successfully produce high-purity TMAH, meeting the requirements of the electronics industry. The main electrolytic raw material used in China is tetramethylammonium bicarbonate, which is a relatively environmentally friendly green production process, but the electrolysis efficiency is only 50% of that of tetramethylammonium chloride. Although the use of tetramethylammonium chloride as an electrolytic raw material abroad can greatly improve the current efficiency, how to deal with the chlorine produced in the process is also a major problem.

[0003] The disadvantages are as follows:

[0004] (1) The traditional process has high preparation cost and low purity;

[0005] (2) The emerging process has high purity but low efficiency;

[0006] (3) There are potential safety hazards in the preparation process;

[0007] Therefore, it is urgent to provide a new method for preparing tetramethylammonium hydroxide based on electrodialysis. Summary of the invention

[0008] The object of the present invention is to overcome the defects in the prior art and provide a method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis. The method of the present invention includes providing an electrodialysis device and a reverse osmosis device, wherein the electrodialysis device includes a three-compartment electrodialysis device and a bipolar membrane electrodialysis membrane stack, and a tetramethylammonium halide solution can be converted into an acid solution of tetramethylammonium hydroxide (hereinafter referred to as TMAH) and its counterions, overcoming the deficiencies and defects mentioned in the above background. The method can effectively reduce the impurity ions in TMAH and prepare high-purity TMAH at low cost. At the same time, the generation of industrial wastewater and waste gas is also greatly reduced, and it is a green, environmentally friendly and safe preparation method.

[0009] The specific technical solutions adopted by the present invention are as follows:

[0010] The present invention provides a method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis, and the method is specifically as follows:

[0011] S1: Based on an electrodialysis device with a bipolar membrane electrodialysis membrane stack, a tetramethylammonium halide solution is added to a material chamber, water or an acid solution corresponding to the tetramethylammonium halide is added to an acid chamber, water or a tetramethylammonium hydroxide solution is added to an alkali chamber, and a tetramethylammonium hydroxide solution is added to an extreme water chamber; after the power supply is turned on and the reaction is fully carried out, a tetramethylammonium halide solution with a reduced concentration is obtained in the material chamber, an acid solution corresponding to the tetramethylammonium halide is obtained in the acid chamber, and a tetramethylammonium hydroxide solution is obtained in the alkali chamber;

[0012] S2: The product obtained from the material chamber is concentrated by reverse osmosis technology and then added back into the material chamber of the electrodialysis device as a starting solution.

[0013] Preferably, the bipolar membrane electrodialysis membrane stack is arranged between the positive plate and the negative plate, and includes, in the order from the positive plate to the negative plate, an alternately arranged polar water separator, bipolar membrane, acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, acid chamber separator... acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, polar water separator; based on the above arrangement order, the bipolar membrane, acid chamber separator and anion exchange membrane constitute the acid chamber, the anion exchange membrane, material separator and cation exchange membrane constitute the material chamber, the cation exchange membrane, alkali chamber separator and bipolar membrane constitute the alkali chamber, and the bipolar membrane, polar water separator and positive / negative plate constitute the polar water chamber.

[0014] Furthermore, the material chamber, acid chamber, alkali chamber and polar water chamber are independent of each other, and the operating temperature is 20-35°C.

[0015] Furthermore, the positive electrode plate and the negative electrode plate are one or more of nickel plates, ruthenium titanium plates, and graphite materials.

[0016] Furthermore, the bipolar membrane material is one or more of PES, PVC, PE, PS, and PP.

[0017] Preferably, the S1 reacts under direct current, the power supply voltage is 20-35V, and the current density is 600-800A / m 2 .

[0018] Preferably, the tetramethylammonium halide is tetramethylammonium chloride, and the concentration of the tetramethylammonium chloride starting solution in the material chamber is 13wt%-22wt%.

[0019] Preferably, water is added into the acid chamber as a starting solution, and water is added into the alkali chamber as a starting solution; an acid solution is added into the acid chamber as a starting solution, and a tetramethylammonium hydroxide solution is added into the alkali chamber as a starting solution, and the concentrations of the acid solution and the tetramethylammonium hydroxide solution are the same and do not exceed 2 mol / L.

[0020] Preferably, the volumes of the acid chamber and the base chamber are the same.

[0021] Preferably, the concentration of the tetramethylammonium hydroxide solution added into the polar water chamber is 2 wt % to 4 wt %.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention can be used for preparing TMAH in industrial production: 1) compared with the existing preparation method, the present method does not generate waste gas and waste water, and is a green and environmentally friendly process; 2) effectively reduces the content of impurity ions in TMAH, and prepares high-purity TMAH at a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the electrodialysis device of the present invention;

[0025] Figure 2 for Figure 1 A schematic diagram of the overall structure of a bipolar membrane electrodialysis membrane stack;

[0026] Figure 3 A schematic diagram of the electrodialysis device during the preparation process of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0028] The present invention provides a method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis, and the steps of the method are as follows:

[0029] S1: Based on an electrodialysis device with a bipolar membrane electrodialysis membrane stack, a tetramethylammonium halide solution is added in a material chamber as a starting solution, water or an acid solution corresponding to the tetramethylammonium halide is added in an acid chamber as a starting solution, water or a tetramethylammonium hydroxide solution is added in an alkali chamber as a starting solution, and a tetramethylammonium hydroxide solution is added in an extreme water chamber as a starting solution; after the power supply is turned on and the reaction is fully carried out, a tetramethylammonium halide solution with a reduced concentration is obtained in the material chamber, an acid solution corresponding to the tetramethylammonium halide is obtained in the acid chamber, and a tetramethylammonium hydroxide solution is obtained in the alkali chamber;

[0030] S2: The product obtained from the material chamber (ie, tetramethylammonium halide solution) is concentrated by reverse osmosis technology, and then re-added to the material chamber in the electrodialysis device of S1 as a starting solution for recycling.

[0031] As a preferred embodiment of the present invention, Figure 1 and 2 As shown, the bipolar membrane electrodialysis membrane stack is arranged between the positive plate and the negative plate, and includes, in the order from the positive plate to the negative plate, an alternately arranged polar water separator, bipolar membrane, acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, acid chamber separator... acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, polar water separator. Based on the above arrangement order, the adjacent bipolar membrane, acid chamber separator and anion exchange membrane constitute the acid chamber, the adjacent anion exchange membrane, material separator and cation exchange membrane constitute the material chamber, the adjacent cation exchange membrane, alkali chamber separator and bipolar membrane constitute the alkali chamber, and the adjacent bipolar membrane, polar water separator and positive / negative plate constitute the polar water chamber.

[0032] In addition, the outlet of the polar water chamber can be connected to the inlet of the polar water chamber storage tank through a pipeline, and the outlet of the polar water chamber storage tank is connected to the inlet of the polar water chamber through a pipeline; similarly, the outlet of the acid chamber can be connected to the inlet of the acid product storage tank through a pipeline, and the outlet of the acid product storage tank is connected to the inlet of the acid chamber through a pipeline; the outlet of the alkali chamber can be connected to the inlet of the alkali product storage tank through a pipeline, and the outlet of the alkali product storage tank is connected to the inlet of the alkali chamber through a pipeline; the outlet of the material chamber can be connected to the inlet of the material chamber storage tank through a pipeline, and the outlet of the material chamber storage tank is connected to the inlet of the material chamber through a pipeline. The circulation loop of the polar water chamber, the circulation loop of the acid chamber, the circulation loop of the alkali chamber, and the circulation loop of the material chamber are all provided with circulation power by a water pump.

[0033] In actual use, the material chamber, acid chamber, alkali chamber and polar water chamber are independent of each other, and the operating temperature is 20-35°C. The supporting equipment includes circulating cooling water. The positive and negative plates are one or more of nickel plates, ruthenium titanium plates, and graphite materials. The bipolar membrane material is one or more of PES, PVC, PE, PS, and PP.

[0034] As a preferred embodiment of the present invention, the electrodialysis device in S1 is reacted under direct current, the power supply operating voltage is 20-35V, and the current density is 600-800A / m 2 .

[0035] As a preferred embodiment of the present invention, tetramethylammonium halide can be tetramethylammonium chloride, wherein the concentration of the tetramethylammonium chloride starting solution in the material chamber is 13wt%-22wt% (i.e. Figure 3 high concentration materials in the

[0036] As a preferred embodiment of the present invention, if water is used as the starting solution in the acid chamber, water should also be added to the alkali chamber as the starting solution; if an acid solution is used in the acid chamber (for example, in this embodiment, when tetramethylammonium halide is tetramethylammonium chloride, the acid solution is hydrogen chloride solution) as the starting solution, tetramethylammonium hydroxide solution should also be added to the alkali chamber as the starting solution, and the concentrations of the acid solution and the tetramethylammonium hydroxide solution are the same and do not exceed 2 mol / L. However, in consideration of cost saving, in this embodiment, if Figure 3 As shown, deionized water is used as the starting solution in both the acid chamber and the alkali chamber.

[0037] As a preferred embodiment of the present invention, the volumes of the acid chamber and the alkali chamber are the same.

[0038] As a preferred embodiment of the present invention, the concentration of the tetramethylammonium hydroxide solution added into the polar water chamber is 2wt% to 4wt%.

[0039] In the process of preparing TMAH by the above method of the present invention, the concentration of tetramethylammonium halide produced after S2 reverse osmosis concentration is above 15wt%, the concentrations of TMAH and hydrochloric acid solution prepared by S1 bipolar membrane electrodialysis technology are both greater than 2mol / L, and the metal ion impurities in TMAH prepared by S1 bipolar membrane electrodialysis technology can be reduced to below 10ppb.

[0040] For example, tetramethylammonium halide uses tetramethylammonium chloride, and both the acid chamber and the base chamber use deionized water as the starting solution. Figure 3 As shown, the operating principle of the bipolar membrane electrodialysis technology in S1 is as follows:

[0041] Given a system DC current, the bipolar membrane can convert H2O into H + With OH - , and migrate to the negative and positive sides of the bipolar membrane respectively; in the case of electrical drive, the monovalent cations in the material chamber (i.e. (CH3)4N + ) passes through the cation exchange membrane and reacts with the OH produced on the negative side of the bipolar membrane - Combine to form a base (ie TMAH); anion (ie Cl -) passes through the anion exchange membrane and reacts with the H generated on the positive side of the bipolar membrane + Combine to generate acid (i.e. HCl); at the same time, the material chamber undergoes ion exchange, and the high-concentration tetramethylammonium chloride solution is converted into low-concentration tetramethylammonium chloride, which can be concentrated through reverse osmosis technology and then re-enter the material chamber as a starting solution for repeated recycling.

[0042] The steps and effects of the method of the present invention will be specifically described below through examples.

[0043] Example 1

[0044] This embodiment uses Figure 1 The electrodialysis device with a bipolar membrane electrodialysis membrane stack shown in FIG. 1 is used to prepare TMAH, and the preparation method is not described in detail. Figure 2 The bipolar membrane electrodialysis stack shown in the figure prepared acid and base for 1.0, 1.5, 2.0, and 2.5 mol / L tetramethylammonium chloride, respectively, wherein deionized water was initially placed in both the acid chamber and the base chamber, and the volume ratio of the acid chamber to the base chamber was 1:1, and the results are shown in Table 1. The results show that the TMAH yield is high, all above 90%, and the metal impurity content is less than 10 ppb.

[0045] The design parameters of this embodiment are: a group of membrane partial pressure ≤ 2V, current density 800A / m 2 , operating temperature 20 ~ 35 ℃.

[0046] Table 1 Current density at 800A / m 2 Under different content, material output rate and impurity content

[0047]

[0048]

[0049] As can be seen from Table 1, the current efficiency increases first and then decreases with the increase of the raw material (i.e., tetramethylammonium chloride) concentration. When the raw material concentration is 2 mol / L, the current efficiency is the highest, and when the raw material concentration is greater than 2 mol / L, the current efficiency decreases instead. This is because, in the early stage of the experiment, the conductivity of the entire system gradually increases with the increase of the material concentration, which reduces the overall resistance and increases the current efficiency; and when the material liquid concentration continues to increase to more than 2 mol / L, there is a large gap between the material chamber concentration and the alkali product chamber concentration, which reduces the membrane's ion selectivity, causes counter-ion penetration, and reduces the current efficiency.

[0050] In a preferred embodiment of the present invention, in order to improve current efficiency and reduce costs, the material concentration is maintained between 13wt% and 22wt%.

[0051] Example 2

[0052] This embodiment uses Figure 1 The electrodialysis device with a bipolar membrane electrodialysis membrane stack shown in FIG. 1 is used to prepare TMAH, and the preparation method is not described in detail. Figure 2 The bipolar membrane electrodialysis stack shown is at 400, 600, 800, and 1000 A / m 2 2 mol / L tetramethylammonium chloride was prepared for acid and base at a current density of , wherein deionized water was initially placed in the acid chamber and the base chamber at a volume ratio of 1:1. The results are shown in Table 2.

[0053] The design parameters of this embodiment are: a group of membrane partial pressure ≤ 2V, current density 400-1000A / m 2 , operating temperature 20 ~ 35 ℃.

[0054] Table 2 Current efficiency and product yield at different current densities

[0055]

[0056] From Table 2, we can see that the current density is 800A / m 2 The current efficiency and TMAH output rate of the system are the highest at 1000A / m. This is because at lower current density, the external electric field is insufficient to drive the charged ions, causing their migration speed to be slower, the system operation time to be longer, and part of the electrical energy to be used for heat generation in the membrane stack, resulting in lower current efficiency. At 1000A / m 2 Under excessively high current density, polarization is likely to occur on the surface of the ion exchange membrane, and the generated H + Inhibition of (CH3)4N + The migration of ions also causes the current efficiency to decrease.

[0057] In a preferred embodiment of the present invention, in order to improve current efficiency and reduce costs, the current density should be maintained at 600-800A / m 2 between.

[0058] It can be seen that the present invention converts the industrial raw material tetramethylammonium halide into TMAH solution and hydrochloric acid solution through an electrodialysis device. The yield of TMAH produced by this method is not less than 95%; and no additional impurities are introduced, the purity of TMAH is very high, and the metal impurities can be reduced to less than 10ppb; the low-concentration tetramethylammonium chloride remaining in the material chamber can be re-concentrated by reverse osmosis technology and enter the bipolar membrane system as a raw material to produce TMAH again, realizing recycling and green process in the system.

[0059] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis, characterized in that: The details are as follows: S1: Based on an electrodialysis device with a bipolar membrane electrodialysis membrane stack, a tetramethylammonium halide solution is added to a material chamber, water or an acid solution corresponding to the tetramethylammonium halide is added to an acid chamber, water or a tetramethylammonium hydroxide solution is added to an alkali chamber, and a tetramethylammonium hydroxide solution is added to an extreme water chamber; after the power supply is turned on and the reaction is fully carried out, a tetramethylammonium halide solution with a reduced concentration is obtained in the material chamber, an acid solution corresponding to the tetramethylammonium halide is obtained in the acid chamber, and a tetramethylammonium hydroxide solution is obtained in the alkali chamber; S2: The product obtained from the material chamber is concentrated by reverse osmosis technology and then added back into the material chamber of the electrodialysis device as a starting solution.

2. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: The bipolar membrane electrodialysis membrane stack is arranged between the positive plate and the negative plate, and includes, in the order from the positive plate to the negative plate, an alternately arranged polar water separator, bipolar membrane, acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, acid chamber separator... acid chamber separator, anion exchange membrane, material separator, cation exchange membrane, alkali chamber separator, bipolar membrane, polar water separator; based on the above arrangement order, the bipolar membrane, acid chamber separator and anion exchange membrane constitute the acid chamber, the anion exchange membrane, material separator and cation exchange membrane constitute the material chamber, the cation exchange membrane, alkali chamber separator and bipolar membrane constitute the alkali chamber, and the bipolar membrane, polar water separator and positive / negative plate constitute the polar water chamber.

3. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 2, characterized in that: The material chamber, acid chamber, alkali chamber and polar water chamber are independent of each other, and the operating temperature is 20-35°C.

4. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 2, characterized in that: The positive electrode plate and the negative electrode plate are one or more of nickel plate, ruthenium titanium plate and graphite material.

5. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 2, characterized in that: The bipolar membrane material is one or more of PES, PVC, PE, PS and PP.

6. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: The S1 reacts under direct current, the power supply voltage is 20-35V, and the current density is 600-800A / m 2 .

7. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: The tetramethylammonium halide is tetramethylammonium chloride, and the concentration of the tetramethylammonium chloride starting solution in the material chamber is 13wt%-22wt%.

8. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: Water is added into the acid chamber as a starting solution, and water is added into the alkali chamber as a starting solution; an acid solution is added into the acid chamber as a starting solution, and a tetramethylammonium hydroxide solution is added into the alkali chamber as a starting solution, and the concentrations of the acid solution and the tetramethylammonium hydroxide solution are the same and do not exceed 2 mol / L.

9. A method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: The volumes of the acid chamber and the base chamber are the same.

10. The method for preparing tetramethylammonium hydroxide based on bipolar membrane electrodialysis according to claim 1, characterized in that: The concentration of the tetramethylammonium hydroxide solution added into the polar water chamber is 2 wt % to 4 wt %.

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