Method for preparing hydrobromic acid through triggering type electric reduction of bromine

Abstract

The invention relates to a method for preparing hydrobromic acid through trigger type electric reduction of bromine, and belongs to the technical field of green electrochemistry, the method comprises the following steps: S1, adding an acidic electrolyte into an anode electrolytic bath, and installing a counter electrode; s2, deionized water is added into a cathode electrolytic cell, and a working electrode and a reference electrode are installed; wherein the working electrode is a carbon material electrode; s3, controlling the potential of the working electrode to be constant between-1.16 V and 0.24 V relative to the potential of the standard hydrogen electrode; s4, bromine is dropwise added into the cathode electrolytic cell to trigger an electroreduction reaction; and S5, after the bromine completely reacts, stopping the reaction, and obtaining the hydrobromic acid solution from the cathode electrolytic cell. According to the method, bromine molecules are used as a trigger and control core of the reaction, the electrolysis process can be accurately started or terminated by simply controlling feeding of bromine, the operation safety is good, the process flow controllability is high, and the method has good industrial application potential and popularization value.

Description

Technical Field

[0001] This invention relates to a method for preparing hydrobromic acid by triggered electroreduction of bromine, belonging to the field of green electrochemical technology. Background Technology

[0002] Hydrobromic acid, as an aqueous solution of hydrogen bromide, has important applications in many fields such as petroleum refining, chemical synthesis, and new material preparation. Currently, the main industrial methods for producing hydrobromic acid include the sulfur process, the red phosphorus process, and the combustion process. The sulfur process uses sulfur and bromine as raw materials, producing sulfuric acid as a byproduct while generating hydrobromic acid. The red phosphorus process uses red phosphorus and bromine, producing phosphoric acid as a byproduct during hydrobromic acid production. Although these methods can synthesize hydrobromic acid, they all have drawbacks: the reaction products need further distillation and purification to obtain high-purity hydrobromic acid, a process that is energy-intensive and prone to environmental pollution. Another method is the combustion process, which involves the combustion reaction of hydrogen and bromine in a specialized device under the action of a catalyst to produce hydrogen bromide gas, which is then absorbed to obtain hydrobromic acid. However, this method uses expensive catalysts, requires high-temperature conditions, is difficult to control, and has a complex combustion device structure, resulting in high overall production costs and limiting its industrial application. Therefore, there is an urgent need to develop an efficient, energy-saving, and environmentally friendly hydrobromic acid preparation process. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this invention provides a method for preparing hydrobromic acid by triggered electroreduction of bromine.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: One of the objectives of this invention is to provide a method for preparing hydrobromic acid by triggered electroreduction of bromine, which is carried out in a dual-chamber electrolysis device consisting of an anodic electrolytic cell and a cathode electrolytic cell separated by an ion exchange membrane. The method includes the following steps: S1. Add acidic electrolyte to the anodic electrolytic cell and install the counter electrode; S2. Add deionized water to the cathode electrolytic cell and install a working electrode and a reference electrode; wherein the working electrode is a carbon material electrode; S3. Use an electrochemical workstation to control the potential of the working electrode so that its potential relative to the standard hydrogen electrode is constant between -1.16V and 0.24V. S4. Under stirring conditions, bromine is added dropwise to the cathode electrolytic cell to trigger an electroreduction reaction; wherein the mass ratio of deionized water to added bromine in the cathode electrolytic cell is 1.1 to 20:1. S5. When the bromine has completely reacted and the current drops below the background current, stop the reaction and obtain a hydrobromic acid solution from the cathode electrolytic cell.

[0005] This invention uses carbon fiber as the working electrode, utilizing its adsorption and capture properties for bromine molecules to induce an electrochemical reduction reaction that converts bromine molecules into bromide ions, thereby achieving the preparation of hydrobromic acid. Based on the difference in reduction potential between bromine molecules and hydrogen ions in water, the potential of the working electrode is controlled to selectively induce the electroreduction reaction of bromine molecules (Br2) (Br2 + 2e-) - → 2Br - ), and avoid hydrogen ions (H) in water + The reduction and precipitation of bromine. In this process, bromine molecules act as triggers, initiating the electroreduction-electrooxidation reaction system in their presence and automatically terminating the reaction after their complete consumption.

[0006] The specific mechanism is as follows: In the cathode electrolyzer, some bromine molecules dissolve in deionized water and undergo hydrolysis to generate hydrobromic acid and hypobromic acid (hypobromic acid can be further electro-reduced to bromide ions), thus giving the system a certain conductivity; another part of the bromine molecules are adsorbed by the working electrode and trigger a reduction reaction, gaining electrons and transforming into bromide ions. At the same time, an electro-oxidation reaction of water occurs in the anode electrolyzer, where oxygen in the water molecules loses electrons to generate oxygen gas and produces hydrogen ions; these hydrogen ions migrate through the ion exchange membrane to the cathode electrolyzer, where they combine with bromide ions to form hydrobromic acid. With the continuous addition of bromine, the above electrochemical reduction-oxidation reaction continues, and hydrobromic acid gradually accumulates in the cathode cell; when the bromine molecules have completely reacted, the system current drops to the background current level, the reaction spontaneously stops, and the final cathode electrolyte is the target product, hydrobromic acid.

[0007] The background current refers to the stable current value measured when there is no bromine reaction in the system, which can usually be regarded as a current value of 0mA or close to 0mA.

[0008] Based on the above technical solution, the present invention can also be improved as follows: Furthermore, in step S1, the acidic electrolyte is an aqueous solution of sulfuric acid, phosphoric acid, and perchloric acid, with a mass concentration of 5% to 25%.

[0009] Furthermore, the mass ratio of water in the acidic electrolyte in step S1 to the mass ratio of deionized water in step S2 is 1 to 2:1.

[0010] Furthermore, in step S1, the counter electrode is any one of a carbon rod electrode, a platinum electrode, or a titanium electrode.

[0011] Furthermore, in step S2, the working electrode is any one of carbon paper electrode, carbon cloth electrode, and carbon felt electrode, preferably carbon felt electrode or carbon cloth electrode.

[0012] Furthermore, in step S2, the reference electrode is any one of an Ag / AgCl electrode, a saturated calomel electrode, or a mercurous sulfate electrode.

[0013] Furthermore, in step S3, the potential of the working electrode relative to the potential of the standard hydrogen electrode is -1.16V to 0.24V.

[0014] Furthermore, the ion exchange membrane is a proton exchange membrane or a cation exchange membrane.

[0015] Furthermore, the anode electrolytic cell has a stirring device.

[0016] Furthermore, the cathode electrolytic cell has a stirring device and a dripping device.

[0017] The method for preparing hydrobromic acid by triggered electroreduction of bromine provided by this invention has the following beneficial effects: 1. This invention uses carbon fiber materials such as carbon felt and carbon cloth as working electrodes. By utilizing their efficient adsorption and capture capabilities for bromine molecules, the electrochemical reduction process of bromine molecules to bromide ions is significantly promoted, thereby efficiently and directionally synthesizing hydrobromic acid.

[0018] 2. By precisely setting the potential of the working electrode, this invention utilizes the difference in reduction potential between bromine molecules and hydrogen ions to achieve selective triggering and control of the bromine molecule reduction reaction, ensuring a high degree of specificity in the reaction process.

[0019] 3. In the process of this invention, hydrogen ions generated at the anode migrate to the cathode through the ion-exchange membrane and combine with bromide ions to generate hydrobromic acid. The dilute acid electrolyte in the anode chamber can be recycled. The entire process generates no secondary waste, and the hydrobromic acid product obtained has high purity, meeting the requirements of green chemistry and clean production.

[0020] 4. This invention uses bromine molecules as the core for triggering and controlling the reaction. The electrolysis process can be precisely started or terminated by simply controlling the addition of bromine. It has good operational safety, strong process controllability, and good potential for industrial application and promotion. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the equipment for the triggered electroreduction of bromine to prepare hydrobromic acid according to the present invention. Detailed Implementation

[0022] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1 according to Figure 1The H-type dual-chamber electrolytic cell system was constructed as shown. A carbon paper electrode was used as the working electrode (W), a platinum electrode as the counter electrode (C), and an Ag / AgCl electrode as the reference electrode (R). The diaphragm between the anolyte and catholyte was a Nafion 117 proton exchange membrane. 100g of a 5% (w / w) sulfuric acid aqueous solution was added to the anolyte, and 95g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode (W), the positive electrode to the counter electrode (C), and the reference electrode (R) was connected to the reference channel. The potential of the working electrode (W) was set to -1.26V (vs. Ag / AgCl, approximately -1.06V vs. SHE). Stirring was started, and 5g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0mA, at which point electrolysis was stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 5%.

[0024] Example 2 according to Figure 1 The H-type dual-chamber electrolytic cell system was constructed as shown. A carbon cloth electrode was used as the working electrode (W), a titanium electrode as the counter electrode (C), and a saturated calomel electrode (SCE) as the reference electrode (R). The diaphragm between the anolyte and catholyte was a sulfonated polyether ether ketone (SPEEK) cation exchange membrane. 100 g of a 10% (w / w) phosphoric acid aqueous solution was added to the anolyte. 45 g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode (W), the positive electrode to the counter electrode (C), and the reference electrode (R) was connected to the reference channel. The potential of the working electrode (W) was set to -1.0 V (vs. SCE, approximately -0.76 V vs. SHE). Stirring was started, and 5 g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0 mA. Electrolysis was then stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 10%.

[0025] Example 3 according to Figure 1 The H-type dual-chamber electrolytic cell system was constructed as shown. A carbon felt electrode was used as the working electrode (W), a platinum electrode as the counter electrode (C), and a mercurous sulfate electrode as the reference electrode (R). A Nafion 115 proton exchange membrane was used as the diaphragm between the anolyte and catholyte. 100 g of a 15% (w / w) perchloric acid aqueous solution was added to the anolyte. 55 g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode (W), the positive electrode to the counter electrode (C), and the reference electrode (R) was connected to the reference channel. The potential of the working electrode (W) was set to -1.02 V (vs. Hg / Hg₂SO₄, approximately -0.36 V vs. SHE). Stirring was started, and 5 g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0 mA. Electrolysis was then stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 8%.

[0026] Example 4 according to Figure 1The H-type dual-chamber electrolytic cell system was constructed as shown. A carbon cloth electrode was used as the working electrode (W), a titanium electrode as the counter electrode (C), and a mercurous sulfate electrode as the reference electrode (R). An Ultrex CMI-7000 cation exchange membrane was used as the separator between the anolyte and catholyte. 100 g of a 20% (w / w) phosphoric acid aqueous solution was added to the anolyte. 60 g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode (W), the positive electrode to the counter electrode (C), and the reference electrode (R) was connected to the reference channel. The potential of the working electrode (W) was set to -0.42 V (vs. Hg / Hg₂SO₄, approximately 0.24 V vs. SHE). Stirring was started, and 15 g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0 mA. Electrolysis was then stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 20%.

[0027] Example 5 according to Figure 1 The H-type dual-chamber electrolytic cell system was constructed as shown. The carbon felt electrode was the working electrode W, the carbon rod electrode was the counter electrode C, and the saturated calomel electrode (SCE) was the reference electrode R. A Nafion 117 proton exchange membrane was used as the diaphragm between the anolyte and catholyte. 100g of a 25% (w / w) phosphoric acid aqueous solution was added to the anolyte. 45g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode W, the positive electrode to the counter electrode C, and the reference electrode R was connected to the reference channel. The potential of the working electrode W was set to -0.3V (vs. SCE, approximately -0.06V vs. SHE). Stirring was started, and 40g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0mA, at which point electrolysis was stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 48%.

[0028] Example 6 according to Figure 1 The H-type dual-chamber electrolytic cell system was constructed as shown. A carbon paper electrode was used as the working electrode (W), a titanium electrode as the counter electrode (C), and an Ag / AgCl electrode as the reference electrode (R). The diaphragm between the anolyte and cathode electrolytic cells was a sulfonated polyether ether ketone (SPEEK) cation exchange membrane. 100g of an 18% sulfuric acid aqueous solution was added to the anolyte. 46g of deionized water was added to the cathode electrolytic cell. The negative electrode of the electrochemical workstation was connected to the working electrode (W), the positive electrode to the counter electrode (C), and the reference electrode (R) was connected to the reference channel. The potential of the working electrode (W) was set to -0.46V (vs. Ag / AgCl, approximately -0.26V vs. SHE). Stirring was started, and 18g of bromine was slowly added dropwise to the cathode cell. After the addition was complete, electrolysis was continued until the current reached 0mA. Electrolysis was then stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 28%.

[0029] Example 7 according to Figure 1The H-type dual-chamber electrolytic cell system was constructed as shown. The carbon felt electrode was the working electrode W, the carbon rod electrode was the counter electrode C, and the saturated calomel electrode (SCE) was the reference electrode R. A Nafion 115 proton exchange membrane was used as the diaphragm between the anolyte and catholyte. 100 g of a 22% (w / w) phosphoric acid aqueous solution was added to the anolyte. 52 g of deionized water was added to the catholyte. The negative electrode of the electrochemical workstation was connected to the working electrode W, the positive electrode to the counter electrode C, and the reference electrode R was connected to the reference channel. The potential of the working electrode W was set to -0.8 V (vs. SCE, approximately -0.56 V vs. SHE). Stirring was started, and 28 g of bromine was slowly added dropwise to the catholyte. After the addition was complete, electrolysis was continued until the current reached 0 mA, at which point electrolysis was stopped, yielding a hydrobromic acid solution with a mass concentration of approximately 35%.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing hydrobromic acid by triggered electroreduction of bromine, characterized in that, The method is carried out in a dual-chamber electrolysis apparatus consisting of an anodic electrolytic cell and a cathode electrolytic cell, which are separated by an ion exchange membrane; The method includes the following steps: S1. Add acidic electrolyte to the anodic electrolytic cell and install the counter electrode; S2. Add deionized water to the cathode electrolytic cell and install a working electrode and a reference electrode; wherein the working electrode is a carbon material electrode; S3. Control the potential of the working electrode so that its potential relative to the standard hydrogen electrode is constant between -1.16V and 0.24V; S4. Under stirring conditions, bromine is added dropwise to the cathode electrolytic cell to trigger an electroreduction reaction; wherein the mass ratio of deionized water to added bromine in the cathode electrolytic cell is 1.1 to 20:

1. S5. When the bromine has completely reacted and the current drops below the background current, stop the reaction and obtain a hydrobromic acid solution from the cathode electrolytic cell.

2. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, In step S1, the acidic electrolyte is an aqueous solution of sulfuric acid, phosphoric acid, and perchloric acid, with a mass concentration of 5% to 25%.

3. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1 or 2, characterized in that, The mass ratio of water in the acidic electrolyte in step S1 to the mass ratio of deionized water in step S2 is 1 to 2:

1.

4. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, In step S1, the counter electrode is any one of a carbon rod electrode, a platinum electrode, or a titanium electrode.

5. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, In step S2, the working electrode is any one of carbon paper electrode, carbon cloth electrode, and carbon felt electrode.

6. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, In step S2, the reference electrode is any one of Ag / AgCl electrode, saturated calomel electrode, and mercurous sulfate electrode.

7. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, In step S3, the potential of the working electrode relative to the potential of the standard hydrogen electrode is -1.16V to 0.24V.

8. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, The ion exchange membrane is a proton exchange membrane or a cation exchange membrane.

9. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, The anodic electrolytic cell is equipped with a stirring device.

10. The method for preparing hydrobromic acid by triggered electroreduction of bromine according to claim 1, characterized in that, The cathode electrolytic cell has a stirring device and a dripping device.

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