A method and system for capturing SO2 using dual batteries

Abstract

This invention proposes a method and system for capturing SO2 using a dual-cell system. The method involves a dual-cell system consisting of an acid cell and an alkaline cell connected in series. AgCl / Sb is used as the positive and negative electrodes of the acid cell, and SbOCl / Ag is used as the positive and negative electrodes of the alkaline cell. An aqueous solution containing 1-ethyl-3-methylimidazole chloride and sodium acetate is used as the electrolyte for a galvanic cell reaction. The electrolyte produced by the alkaline cell is continuously recycled back to the acid cell through an electrolyte storage tank. Then, the electrolyte produced by the acid cell is continuously recycled back to the alkaline cell through a vacuum stripper, thus achieving SO2 capture. This invention utilizes the electromotive force difference generated between the positive and negative electrodes of the dual-cell system to control the pH value of the electrolyte, thereby achieving selective adsorption and capture of SO2 in flue gas. It requires no chemical additives, is easy to implement, has no side reactions, no raw material waste or secondary pollution, low operating costs, and high electronic efficiency, showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the technical field of SO2 removal from the atmosphere, and more particularly to a method and system for capturing SO2 using dual batteries. Background Technology

[0002] Sulfur dioxide (SO2) is mainly produced in industries such as sulfuric acid production, petroleum refining, fertilizer production, power generation, and metallurgy. It is one of the major air pollutants, posing extremely serious hazards to human health, plants, textiles, building materials, and historical sites. It can also cause acid rain, acidify the environment, and damage the ecosystem. The use of fossil fuels results in massive SO2 emissions, harmfully impacting humans, animals, and plants. Therefore, the search for an efficient and environmentally friendly SO2 flue gas treatment technology has attracted great interest from researchers.

[0003] Controlling the SO2 content in the atmosphere primarily involves controlling SO2 emissions. Currently, there are hundreds of methods for treating SO2 flue gas, such as: circulating fluidized bed method, in-furnace absorbent injection technology, limestone pressure oxidation technology, rotary spray drying (SDA), magnesium hydroxide method, metal oxide desulfurization method, electron beam method, seawater method, catalytic oxidation method, activated carbon desulfurization method, and SO2 / NO... x Combined removal and regeneration processes, and simplified integrated dust removal and desulfurization technologies are some of the methods used to reduce SO2 emissions. While these methods have played a positive role in reducing SO2 emissions, they also have some drawbacks, such as high operating costs, incomplete pollution prevention, complex processes, and the potential for secondary pollution. In contrast, electrochemical methods for treating SO2 in flue gas offer numerous advantages. They reduce the use of chemical reagents, have simpler processes, are easier to operate, and can reduce energy consumption to some extent. Furthermore, sulfur is a valuable chemical resource, and separating and enriching SO2 from flue gas for resource recovery is of great significance. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a method and system for capturing SO2 using dual batteries. The method and system are based on the principle of galvanic cells and use the electromotive force difference generated between the positive and negative electrodes of the dual batteries to control the pH value in the electrolyte, thereby achieving selective adsorption and capture of SO2 in flue gas. It does not require the addition of chemical substances, is easy to implement, has no side reactions, no waste of raw materials or secondary pollution, has low operating costs, high electronic efficiency, and has good application prospects.

[0005] The present invention proposes a method for capturing SO2 using a dual-cell battery, comprising: in a dual-cell battery formed by connecting an acid battery and an alkaline battery in series, using AgCl / Sb as the positive and negative electrodes of the acid battery, using SbOCl / Ag as the positive and negative electrodes of the alkaline battery, and using an aqueous solution containing 1-ethyl-3-methylimidazole chloride and sodium acetate as the electrolyte to carry out a galvanic cell reaction.

[0006] During the galvanic cell reaction, the electrolyte produced by the alkaline cell is continuously circulated back to the acid cell through an electrolyte storage tank. The electrolyte produced by the alkaline cell adsorbs SO2 introduced into the electrolyte storage tank. Then, the electrolyte produced by the acid cell is continuously circulated back to the alkaline cell through a vacuum stripper. The vacuum stripper strips the SO2 dissolved in the electrolyte produced by the acid cell, thereby achieving SO2 capture.

[0007] Preferably, the electrochemical reaction in the alkaline battery is as follows:

[0008]

[0009] The electrochemical reaction in the acid battery is as follows:

[0010] .

[0011] In this invention, in two antimony-silver dual batteries connected in series, the pH of the electrolyte is changed via a Faraday reaction under an appropriate battery voltage. The pH value of the electrolyte is adjusted through a reversible electrochemical reaction. The acid battery (with AgCl / Sb as the positive and negative electrodes) provides H₂. + The process involves acidifying the SO2 dissolved in the electrolyte, then vacuum stripping it out using a vacuum stripper and collecting it in a SO2 collection tank. The alkaline battery (with SbOCl / Ag as the positive and negative electrodes) alkalizes the desulfurized electrolyte and regenerates the electrodes. The system operates in a cycle, and after one cycle (i.e., when there is no significant change in the pH value of the electrolyte), the electrolyte flow direction is switched using an electrolyte circulation pump, with the electrolyte flowing in the opposite direction. By switching the roles of the acid battery and the alkaline battery, continuous removal of SO2 from the atmosphere is achieved.

[0012] Preferably, the concentration of 1-ethyl-3-methylimidazole chloride in the electrolyte is 0.5-0.8 mol / L, and the concentration of sodium acetate is 0.1-0.5 mol / L.

[0013] Preferably, when the electrolyte generated by the alkaline battery is continuously recycled back to the acid battery through the electrolyte storage tank, and when the electrolyte generated by the acid battery is continuously recycled back to the alkaline battery through the vacuum stripper, the electrolyte flow rate is controlled at 1-3 mL / min, and the electrolyte temperature is controlled at 30-40℃.

[0014] Preferably, during the reaction of the primary battery, when the pH value in the electrolyte does not change, the electrolyte is switched to reverse circulation: that is, the electrolyte generated by the acid battery is continuously circulated back to the alkaline battery through the electrolyte storage tank, and the electrolyte generated by the alkaline battery is continuously circulated back to the acid battery through the vacuum stripper.

[0015] The present invention proposes a system for capturing SO2 using a dual-battery system, comprising a dual-battery system consisting of an acid battery and an alkaline battery connected in series, an electrolyte storage tank, and a vacuum stripper.

[0016] The positive and negative electrodes of the acid battery are AgCl / Sb, and the positive and negative electrodes of the alkaline battery are SbOCl / Ag. The electrolyte storage tank is equipped with a gas inlet so that SO2 can be introduced through the gas inlet, and the vacuum stripper is equipped with a gas outlet so that SO2 can be discharged through the gas outlet.

[0017] Furthermore, the acid battery, alkaline battery, electrolyte storage tank, and vacuum stripper are interconnected to form a circulation loop, so that the electrolyte containing 1-ethyl-3-methylimidazole chloride and sodium acetate circulates sequentially through the alkaline battery, electrolyte storage tank, acid battery, and vacuum stripper.

[0018] Preferably, the acid battery, alkaline battery, electrolyte storage tank, and vacuum stripper are all equipped with an electrolyte circulation outlet and an electrolyte circulation inlet;

[0019] The electrolyte circulation outlet of the alkaline battery is connected to the electrolyte circulation inlet of the electrolyte storage tank, the electrolyte circulation outlet of the electrolyte storage tank is connected to the electrolyte circulation inlet of the acid battery, the electrolyte circulation outlet of the acid battery is connected to the electrolyte circulation inlet of the vacuum stripper, and the electrolyte circulation outlet of the vacuum stripper is connected to the electrolyte circulation inlet of the alkaline battery.

[0020] Preferably, the system further includes an electrolyte circulation pump located on the circulation loop, which provides power for the electrolyte to circulate sequentially through the alkaline battery, the electrolyte storage tank, the acid battery, and the vacuum stripper.

[0021] Preferably, the system further includes an SO2 collection tank connected to a vacuum stripper so that SO2 stripped from the vacuum stripper can be collected.

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

[0023] 1. This invention is used for the effective capture of SO2 in the atmosphere. The electrolyte is recycled, and there is no waste or pollution of raw materials. It is a green process with potential commercial value.

[0024] 2. The capture technology of this invention has a simple process, is easy to control, operates under mild conditions, has low operating voltage, low energy consumption, and high electronic efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the SO2 capture system using dual batteries described in this invention.

[0026] Among them, 1-acid battery, 2-alkaline battery, 3-electrolyte storage tank, 4-vacuum stripper, 5-electrolyte circulation pump, 6-SO2 collection tank, 11-thermostatic bath, 12-Sb electrode, 13-AgCl electrode, 14-pH meter, 21-thermostatic bath, 22-SbOCl electrode, 23-Ag electrode, 24-pH meter. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0028] Example 1

[0029] Reference Figure 1 This embodiment proposes a system for capturing SO2 using dual batteries, including dual batteries, an electrolyte storage tank 3, a vacuum stripper 4, an electrolyte circulation pump 5, and an SO2 collection tank 6;

[0030] The dual battery consists of an acid battery 1 and an alkaline battery 2 connected in series;

[0031] The acid battery 1 includes a thermostatic bath 11, an Sb electrode 12, an AgCl electrode 13, and a pH meter 14. The Sb electrode 12 and the AgCl electrode 13 are arranged opposite each other in the thermostatic bath 11, with a gap of 1.5 mm between them. The electrode area is 9 cm². 2 The pH meter 14 is placed in the gap between the two electrodes; the acid battery 1 is also equipped with an electrolyte circulation outlet and an electrolyte circulation inlet that are connected to the gap between the two electrodes.

[0032] The alkaline battery 2 includes a thermostatic bath 21, an SbOCl electrode 22, an Ag electrode 23, and a pH meter 24. The SbOCl electrode 22 and Ag electrode 23 are also arranged opposite each other within the thermostatic bath 21, with a gap of 1.5 mm between them. The electrode area is 9 cm². 2 The pH meter 24 is placed in the gap between the two electrodes; the alkaline battery 2 is also equipped with an electrolyte circulation outlet and an electrolyte circulation inlet that are connected to the gap between the two electrodes.

[0033] The electrolyte storage tank 3 is equipped with a gas inlet and a gas outlet. The gas inlet is used to allow SO2-containing flue gas to enter the electrolyte storage tank 3. At the same time, the electrolyte storage device 3 is also equipped with an electrolyte circulation outlet and an electrolyte circulation inlet.

[0034] The vacuum stripper 4 is provided with a gas outlet for discharging SO2 from the vacuum stripper 4. The vacuum stripper 4 is also provided with an electrolyte circulation outlet and an electrolyte circulation inlet. In this embodiment, the vacuum stripper 4 is specifically a hollow fiber membrane contactor.

[0035] Among them, acid battery 1, alkaline battery 2, electrolyte storage tank 3 and vacuum stripper 4 are interconnected to form a circulation loop, so that the electrolyte containing 0.6 mol / L 1-ethyl-3-methylimidazole chloride and 0.5 mol / L sodium acetate circulates sequentially through alkaline battery 2, electrolyte storage tank 3, acid battery 1 and vacuum stripper 4.

[0036] In a specific embodiment, the electrolyte circulation outlet of the alkaline battery 2 is connected to the electrolyte circulation inlet of the electrolyte storage tank 3 via a circulation pipeline, and the electrolyte circulation outlet of the electrolyte storage tank 3 is connected to the electrolyte circulation inlet of the acid battery 1 via a circulation pipeline. In this embodiment, an electrolyte circulation pump 5 is also provided on the circulation pipeline. The electrolyte circulation outlet of the acid battery 1 is connected to the electrolyte circulation inlet of the vacuum stripper 4 via a circulation pipeline, and the electrolyte circulation outlet of the vacuum stripper 4 is connected to the electrolyte circulation inlet of the alkaline battery 2 via a circulation pipeline. In this embodiment, the gas outlet of the vacuum stripper 4 is connected to the SO2 collection tank 6 via a gas pipeline.

[0037] This invention also proposes a method for capturing SO2 using a dual-battery system. Specifically, in this embodiment, 1500 mL of electrolyte is first poured into the electrolyte storage tank 3. The electrolyte circulation pump 5 and vacuum stripper 4 are then turned on, driving the electrolyte to circulate through the electrolyte storage tank 3, acid battery 1, vacuum stripper 4, and alkaline battery 2. The electrolyte temperature is controlled at 35°C, and the flow rate is 1.5 mL / min. Specifically, flue gas containing SO2 is introduced into the electrolyte in the electrolyte storage tank 3 through the gas inlet. The electrolyte adsorbs the SO2 to form SO3. 2- The remaining unadsorbed gas is discharged through the gas outlet on the electrolyte storage tank 3, after which the SO3-containing gas... 2- The electrolyte then flows back into acid battery 1, where the H2 produced by the electrochemical reaction in acid battery 1... + With SO3 in the electrolyte 2- The reaction forms H2SO3; then, the electrolyte containing H2SO3 flows into the vacuum stripper 4, where H2SO3 decomposes into SO2, which is stripped by the vacuum stripper 4 and discharged from the gas outlet on the vacuum stripper 4. The SO2 is then continuously collected in the SO2 collection tank 6 via a gas pipeline. Afterward, the electrolyte flows into the alkaline battery 2 and then circulates back to the electrolyte storage tank 3. After 1 hour of this working cycle, the electrolyte flow is reversed, and the roles of the acid battery 1 and the alkaline battery 2 are interchanged. SO2 in the flue gas can be continuously removed and captured. This working cycle is repeated until 10 hours have passed. The electronic efficiency (i.e., relative Faraday efficiency, which is obtained by dividing the actual calculated Faraday efficiency by the theoretically maximum Faraday efficiency of this electrochemical reaction) is then calculated. Where m is the actual number of moles of the product, n is the number of electrons in the reaction, F is the Faraday constant, i.e. the amount of charge contained in one mole of electrons, I is the current, and t is the time, the percentage can reach 81%.

[0038] Example 2

[0039] Reference Figure 1 This embodiment also proposes a system and method for capturing SO2 using dual batteries, which is the same as the setup in Embodiment 1, except that the distance between the two electrodes is set to 1 mm, so that the electrolyte containing 0.5 mol / L 1-ethyl-3-methylimidazole chloride and 0.3 mol / L sodium acetate is circulated sequentially through alkaline battery 2, electrolyte storage tank 3, acid battery 1 and vacuum stripper 4, and the electrolyte temperature is controlled at 30°C. The above working cycle is repeated continuously until 10 hours of operation, and the electronic efficiency can reach 85%.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for capturing SO2 using dual cells, characterized by, include: In a dual-cell system consisting of an acid battery and an alkaline battery connected in series, AgCl / Sb is used as the positive and negative electrodes of the acid battery, and SbOCl / Ag is used as the positive and negative electrodes of the alkaline battery. An aqueous solution containing 1-ethyl-3-methylimidazolium chloride and sodium acetate is used as the electrolyte for the galvanic cell reaction. During the reaction of the galvanic cell, the electrolyte produced by the alkaline cell is continuously circulated back to the acid cell through the electrolyte storage tank. The electrolyte produced by the alkaline cell adsorbs the SO2 introduced into the electrolyte storage tank. Then, the electrolyte produced by the acid cell is continuously circulated back to the alkaline cell through a vacuum stripper. The vacuum stripper strips the SO2 dissolved in the electrolyte produced by the acid cell, thereby achieving SO2 capture. In the electrolyte, the concentration of 1-ethyl-3-methylimidazole chloride is 0.5-0.8 mol / L, and the concentration of sodium acetate is 0.1-0.5 mol / L; During the reaction of the galvanic cell, when the pH value in the electrolyte does not change, the electrolyte is switched to reverse circulation: that is, the electrolyte produced by the acid battery is continuously circulated back to the alkaline battery through the electrolyte storage tank, and the electrolyte produced by the alkaline battery is continuously circulated back to the acid battery through the vacuum stripper.

2. The method for capturing SO2 using dual batteries according to claim 1, characterized in that, The electrochemical reaction in the alkaline battery is as follows: The electrochemical reaction in the acid cell is: 。 3. The method for capturing SO2 using double cells according to claim 1 or 2, wherein, When the electrolyte generated by the alkaline battery is continuously recycled back to the acid battery through the electrolyte storage tank, and when the electrolyte generated by the acid battery is continuously recycled back to the alkaline battery through the vacuum stripper, the electrolyte flow rate is controlled at 1-3 mL / min and the electrolyte temperature is controlled at 30-40℃.

4. A system for capturing SO2 using dual cells for carrying out the method of any one of claims 1 to 3, characterized in that, It includes a dual battery consisting of an acid battery and an alkaline battery connected in series, an electrolyte storage tank, and a vacuum stripper; The positive and negative electrodes of the acid battery are AgCl / Sb, and the positive and negative electrodes of the alkaline battery are SbOCl / Ag. The electrolyte storage tank is equipped with a gas inlet so that SO2 can be introduced through the gas inlet, and the vacuum stripper is equipped with a gas outlet so that SO2 can be discharged through the gas outlet. Furthermore, the acid battery, alkaline battery, electrolyte storage tank, and vacuum stripper are interconnected to form a circulation loop, so that the electrolyte containing 1-ethyl-3-methylimidazole chloride and sodium acetate circulates sequentially through the alkaline battery, electrolyte storage tank, acid battery, and vacuum stripper.

5. The system for capturing SO2 using dual cells of claim 4, wherein, Acid batteries, alkaline batteries, electrolyte storage tanks, and vacuum strippers are all equipped with electrolyte circulation outlets and electrolyte circulation inlets; The electrolyte circulation outlet of the alkaline battery is connected to the electrolyte circulation inlet of the electrolyte storage tank, the electrolyte circulation outlet of the electrolyte storage tank is connected to the electrolyte circulation inlet of the acid battery, the electrolyte circulation outlet of the acid battery is connected to the electrolyte circulation inlet of the vacuum stripper, and the electrolyte circulation outlet of the vacuum stripper is connected to the electrolyte circulation inlet of the alkaline battery.

6. The system for capturing SO2 using dual cells according to claim 4 or 5, wherein, The system also includes an electrolyte circulation pump located on the circulation loop. The electrolyte circulation pump is used to provide power for the electrolyte to circulate sequentially through the alkaline battery, the electrolyte storage tank, the acid battery, and the vacuum stripper.

7. The system for capturing SO2 using dual cells according to claim 4 or 5, wherein The system also includes an SO2 collection tank in communication with the vacuum stripper such that SO2 stripped from the vacuum stripper is collected.

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