Preparation method of methanedisulfonic acid

Abstract

The invention discloses a preparation method of methanedisulfonic acid, which comprises the following steps: converting a sodium methanedisulfonate aqueous solution through a bipolar membrane electrodialysis process to directly obtain methanedisulfonic acid and corresponding sodium hydroxide; the molar concentration of the sodium methanedisulfonate aqueous solution is 0.8-1.6 mol / L, and the temperature of the preparation and operation process is 30-45 DEG C; an acid-resistant anion exchange membrane is adopted in the bipolar membrane electrodialysis process. According to the process for preparing the methane disulfonic acid by the three-chamber bipolar membrane electrodialysis method, the methane disulfonate is directly prepared into the methane disulfonic acid and the corresponding cation alkali by the three-chamber bipolar membrane electrodialysis device at the temperature of 30 DEG C or above through the use of the high-concentration methane disulfonate solution and the acid blocking membrane, the current efficiency of the system reaches 30% or above, and the operation is simple and convenient. The power consumption per ton of acid is lower than 2000 kilowatt-hours, and the industrial value is

Description

Technical Field

[0001] The invention belongs to a method for preparing a compound, and particularly relates to a method for preparing methanedisulfonic acid. Background Art

[0002] Methanedisulfonic acid is a very important chemical intermediate, widely used in electroplating, new energy and other fields. Generally, methanedisulfonic acid is prepared by precipitation reaction of sodium methanedisulfonate and barium salt to prepare barium methanedisulfonate, and then barium methanedisulfonate is acidified with sulfuric acid to obtain methanedisulfonic acid. This process uses a large amount of barium ions, which has certain environmental risks. At the same time, a large amount of barium methanedisulfonate and barium sulfate solids are produced. The solid-liquid separation pressure is high, the labor intensity is high, and the production cost is high. At the same time, since barium methanedisulfonate and the reaction product barium sulfate are both insoluble solids, a carrier is needed to disperse them. At the same time, due to the high temperature during the reaction, a solution is also needed for heat dispersion. Therefore, the solution ratio cannot be too low, resulting in a generally low concentration of the methanedisulfonic acid aqueous solution obtained by the reaction (10%). The amount of water that needs to be evaporated later is large, the energy consumption is high, and the equipment volume is large.

[0003] Although existing technologies have proposed using a bipolar membrane electrodialyzer to directly convert sodium methane disulfonate into methane disulfonic acid, due to the special properties of the methane disulfonate radical, the hydrogen ions in the system experience severe reverse osmosis during the process, causing the hydrogen ion concentration in the salt chamber of the electrodialyzer to increase abnormally. This results in extremely low current efficiency (less than 20%) during the electrodialysis process, resulting in extremely high operating costs and equipment investment, making it essentially unusable in actual processes. Summary of the Invention

[0004] Objective of the invention: The objective of the present invention is to provide a method for efficiently preparing methanedisulfonic acid.

[0005] Technical Solution: The present invention discloses a method for preparing methanedisulfonic acid, wherein an aqueous solution of sodium methanedisulfonate is converted through a bipolar membrane electrodialysis process to directly produce methanedisulfonic acid and the corresponding sodium hydroxide. The sodium methanedisulfonate aqueous solution has a molar concentration of 0.8-1.6 mol / L and is prepared and operated at a temperature of 30°C-45°C. The bipolar membrane electrodialysis process utilizes an acid-blocking anion exchange membrane. At this temperature, the sodium methanedisulfonate aqueous solution does not precipitate.

[0006] Preferably, the bipolar membrane electrodialysis process is an industrial process that converts salts in an aqueous solution into corresponding acids and bases using a bipolar membrane electrodialysis system composed of an acid-blocking anion exchange membrane, other cation exchange membranes, and a bipolar membrane.

[0007] The principle is that, driven by an external DC electric field, the selective permeability of the ion exchange membrane (i.e., cations can pass through the cation exchange membrane, and anions can pass through the anion exchange membrane) allows anions and cations to migrate toward the anode and cathode, respectively. During ion migration, if the fixed charge of the membrane is opposite to the charge of the ion, the ion can pass through; if the charges are the same, the ion is repelled. The bipolar membrane electrolyzes water to produce H+ and OH-. H+ combines with anions that pass through the anionic membrane to form an acid, and OH- combines with cations that pass through the cationic membrane to form a base.

[0008] Preferably, the acid-blocking anion exchange membrane is an anion exchange membrane prepared with weakly basic anion exchange groups or enhanced cross-linking density, which has a special barrier property to hydrogen ions compared with general strongly basic anion exchange membranes.

[0009] Preferably, the acid-blocking anion exchange membrane includes the ATD membrane produced by Hangzhou Lanran Technology Co., Ltd., the TWEDA1PB membrane sold by Shandong Tianwei Membrane Technology Co., Ltd., etc.

[0010] Preferably, the method comprises the following steps: assembling an electrodialyser with an anion and cation exchange membrane and a bipolar membrane; preparing an aqueous solution of sodium methanedisulfonate; adjusting the operating parameters of the equipment, applying power to perform electrodialysis, and obtaining methanedisulfonic acid and sodium hydroxide.

[0011] Preferably, the method comprises the following steps: installing and adjusting a three-electrode electrodialysis device, setting a dissolution temperature of 30°C-45°C in a thermostatic bath, and preparing a 0.8-1.6 mol / L sodium methanedisulfonate aqueous solution; starting the device cycle, turning on the power supply after stabilization, and operating the device to predetermined parameters to obtain methanedisulfonic acid and sodium hydroxide.

[0012] Preferably, the pH of the sodium methanedisulfonate aqueous solution is 0.5-9.

[0013] Preferably, the molar ratio of hydrogen ions to sodium ions in the sodium methanedisulfonate aqueous solution is in the range of 60:40-0:100.

[0014] Preferably, the methanedisulfonic acid is an aqueous solution of methanedisulfonic acid with a molar concentration of 0.5 mol / L-1.5 mol / L.

[0015] Preferably, the aqueous solution of methanedisulfonic acid is subsequently treated to reduce the sodium ion content.

[0016] Preferably, the subsequent treatment includes ion resin exchange.

[0017] Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages: The present invention proposes a process for preparing methanedisulfonic acid by a three-chamber bipolar membrane electrodialysis method. At above 30°C, methanedisulfonate is directly prepared into methanedisulfonic acid and its corresponding cationic base by a three-chamber bipolar membrane electrodialyzer through the use of a high-concentration methanedisulfonate solution (methanedisulfonic acid sodium concentration ≥ 0.8 mol / L) and an acid-blocking membrane. On the one hand, this method increases the concentration and temperature of the salt chamber so that methanedisulfonic acid ions with a large kinetic diameter can pass through the acid-blocking membrane with less resistance. On the other hand, the use of an acid-blocking anion exchange membrane effectively reduces the reverse osmosis of hydrogen ions from the acid chamber to the salt chamber, so that the current efficiency of the system reaches more than 30%, and the power consumption per ton of acid is less than 2000 degrees, making this method valuable for industrialization. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described below with reference to embodiments and comparative examples.

[0019] Examples 1 to 5 and Comparative Examples 1-2 were carried out according to the following experimental steps. Specific experimental conditions and results are shown in the table:

[0020] 1. Select anion and cation exchange membranes and bipolar membranes to assemble the electrodialyzer according to experimental needs, check for leakage and internal crosstalk, and connect the equipment; set the dissolution temperature in a constant temperature bath and prepare a sodium methane disulfonate solution of appropriate concentration;

[0021] 2. Start the magnetic pump, conduct a test run, and if all goes well, stop the magnetic pump and adjust the parameters;

[0022] 3. Turn on the power of the magnetic pump, adjust the flow rate of the salt chamber, acid chamber and alkali chamber to 40L / h, and the flow rate of the electrode chamber to 20L / h. After stabilization, turn on the power and start timing. Record the initial liquid volume, concentration, current and voltage data. Start the test and record the time and current and voltage changes at any time.

[0023] 4. After obtaining qualified acid and alkali solutions, turn off the power supply of the electrodialyzer and stop the magnetic pump.

[0024] Performance test experiment: The acid and base concentrations of the acid chamber, salt chamber and alkali chamber are tested by acid-base titration; the acid production current efficiency is calculated by the theoretical sodium ion charge transfer amount for producing a certain amount of acid, and then divided by the actual power consumption of the membrane stack.

[0025]

[0026] It can be seen that under the conditions of 30-45°C temperature, 0.8-1.6 mol / L sodium methanedisulfonate concentration and acid-blocking anion membrane in the method of the present invention, the current efficiency exceeds 30% and the acid production power consumption is less than 2000 degrees, which is significantly better than the comparative example.

Claims

1. A method for preparing methanedisulfonic acid, characterized in that: An aqueous solution of sodium methanedisulfonate is converted through a bipolar membrane electrodialysis process to directly obtain methanedisulfonic acid and the corresponding sodium hydroxide. The molar concentration of the aqueous solution of sodium methanedisulfonate is 0.8-1.6 mol / L, and the temperature during its preparation and operation is 30°C-45°C. The bipolar membrane electrodialysis process uses an acid-blocking anion exchange membrane.

2. The method for preparing methanedisulfonic acid according to claim 1, wherein The bipolar membrane electrodialysis process is an industrial process that converts salt in an aqueous solution into corresponding acid and base using a bipolar membrane electrodialysis system composed of an acid-blocking anion exchange membrane, other cation exchange membranes and a bipolar membrane.

3. The method for preparing methanedisulfonic acid according to claim 2, wherein: The acid-blocking anion exchange membrane is an anion exchange membrane prepared with weakly alkaline anion exchange groups or enhanced cross-linking density.

4. The method for preparing methanedisulfonic acid according to claim 1, wherein: The following steps are involved: An electrodialyzer is assembled with an anion and cation exchange membrane and a bipolar membrane; a sodium methanedisulfonate aqueous solution is prepared; and equipment parameters are adjusted and electricity is supplied to perform electrodialysis to obtain methanedisulfonic acid and sodium hydroxide.

5. The method for preparing methanedisulfonic acid according to claim 1, wherein: Install and adjust the three-electrode electrodialysis equipment, set the dissolution temperature at 30°C-45°C in a constant temperature bath, and prepare a 0.8-1.6 mol / L sodium methanedisulfonate aqueous solution; start the equipment circulation, turn on the power after stabilization, and run the equipment to the predetermined parameters to obtain methanedisulfonic acid and sodium hydroxide.

6. The method for preparing methanedisulfonic acid according to claim 1, wherein: The pH value of the sodium methanedisulfonate aqueous solution is 0.5-9.

7. The method for preparing methanedisulfonic acid according to claim 1, wherein: The molar ratio of hydrogen ions to sodium ions in the sodium methanedisulfonate aqueous solution is in the range of 60:40-0:

100.

8. The method for preparing methanedisulfonic acid according to claim 1, wherein: The methanedisulfonic acid is an aqueous solution of methanedisulfonic acid, and its molar concentration is 0.5 mol / L-1.5 mol / L.

9. The method for preparing methanedisulfonic acid according to claim 8, wherein: The aqueous solution of methanedisulfonic acid is subsequently treated to reduce the sodium ion content.

10. The method for preparing methanedisulfonic acid according to claim 9, characterized in that: The subsequent treatment includes ion resin exchange.

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