Bromine extraction coupling hydrogen production device and method based on forced convection

Abstract

The invention discloses a bromine extraction and hydrogen production coupling device and method based on forced convection, and relates to the technical field of brine bromine extraction and hydrogen production synergistically, the bromine extraction and hydrogen production coupling device based on forced convection is characterized by comprising a forced convection circulation flow cell, the forced convection circulation flow cell comprises an anode chamber and a cathode chamber, and the anode chamber and the cathode chamber are separated through a diaphragm; the positive electrode chamber is internally provided with a positive electrode, the positive electrode adopts an acid heat treatment graphite felt or a CO2 activation product thereof, the negative electrode chamber is internally provided with a negative electrode, the negative electrode adopts a platinum-loaded acid heat treatment graphite felt, and the constructed forced convection circulation flow cell is used for bromine extraction coupling hydrogen production, so that efficient bromine extraction under the condition of a high Cl / Br ratio can be realized; meanwhile, the energy consumption is greatly reduced, and the characteristics of high efficiency and energy conservation are shown.

Description

Technical Field

[0001] This invention patent relates to the technical field of bromine extraction and hydrogen production in a coordinated manner, and specifically relates to a bromine extraction coupled hydrogen production device and method based on forced convection. Background Art

[0002] Bromine is an important chemical raw material, widely used in fields such as medicine, flame retardants, and energy storage. However, traditional bromine extraction methods such as the air blowing method have problems such as high energy consumption, serious equipment corrosion, and environmental pollution, and it is difficult to meet the development needs of green chemistry. Electrochemical bromine extraction has gradually become a research hotspot due to its high efficiency, environmental friendliness, and strong controllability. However, existing electrochemical bromine extraction devices often face problems of low efficiency and high energy consumption when dealing with low-concentration bromide ions such as underground brine. Therefore, developing a high-efficiency and low-energy-consuming flow cell device is of great significance for promoting the industrial application of electrochemical bromine extraction technology.

[0003] In the field of electrochemical treatment of bromine-containing wastewater and bromine resource recovery, some experimental explorations have been carried out in existing research: Taking the research of scholars such as Sun Mei in Non-Patent Document 1 as an example, their team used graphite as the anode to study the electrochemical bromine extraction process, but this research was only for relatively high-concentration bromides (~1 g / L). In addition, the current efficiency of its electrolysis process was relatively low, only 60% to 90%, and the energy consumption was relatively high, reaching 6 kJ / g.

[0004] In Patent Document 1, an innovative method for oxidizing bromide ions (Br - ) to elemental bromine (Br 2 ) using electrolysis technology was disclosed. This method uses inert metals such as graphite, titanium (Ti), ruthenium (Ru), or platinum (Pt) as the working electrode, and by applying direct current (DC), Br - in the solution is converted into Br 2 . This process provides a new technical path for the efficient extraction of bromine elements.

[0005] The anode and cathode described in this patent can be separated by a diaphragm to form an anode area and a cathode area. Each area allows only the liquid-phase electrolyte to flow freely through, which is not forced convection. It can only extract bromine at a high bromine concentration of 1200 - 6000 ppm, and does not consider the influence of other interfering ions such as Cl - , Ba 2+ , Ca 2+ , K + , SO 4 2- , NO 3 - etc. on the bromine extraction ability.

[0006] In Patent Document 2, a method for separating bromine from a liquid by electrochemistry is disclosed. This method uses ruthenium (Ru), lead (Pb), tin (Sn), antimony (Sb), and titanium (Ti) as the working electrodes, directly performs electrochemical treatment on the bromine-containing liquid, and oxidizes Br - to Br 2 , achieving a high removal rate of bromine in the liquid.

[0007] However, Patent Document 2 also does not consider solving the influence of a large number of interfering components existing in actual wastewater. For example, the wastewater generated by the bromination process usually contains a large amount of interfering ions such as chloride ions. During the process of electrochemically oxidizing Br - , these interfering ions will compete with the oxidation of Br - , ultimately affecting the oxidation efficiency of Br - . In addition, this Patent Document 2 only treats wastewater with a chlorine element concentration of not less than 2000 mg / L and a bromide ion concentration of not less than N mg / L (N is a value within the range of 3000 - 4000). Therefore, it is difficult for traditional electrodes to achieve efficient extraction and recovery under low-concentration bromine resources and high chloride ion interference in a complex wastewater system.

[0008] In Patent Document 3, a method for separating bromine from a liquid by electrochemistry is disclosed. This invention discloses an Ov-Co 3 O 4 NNs / Ti electrode for electrochemical bromine extraction and its preparation method, but it has obvious deficiencies: the electrode preparation process is complex, mainly applicable to high-bromine concentration (1500 - 5805.22 mg / L) and low Cl / Br ratio systems, its current efficiency is low, it is difficult to meet the actual needs of treating low-bromine concentration liquids, and there are also challenges in large-scale production, limiting its potential for industrial application.

[0009] Although many efforts have been made in improving the electrochemical bromine extraction technology in recent years, key challenges such as high energy consumption, low bromine extraction efficiency, and insufficient applicability in low-bromine concentration and high Cl - / Br - ratio systems still exist, which seriously limit its potential for actual large-scale application. Thus, it is urgent to develop a technical process with a simple process and device, easy to operate, low operating cost, and practical application feasibility.

[0010] Non-Patent Document 1: Sun M, Lowry GV, Gregory KB. Selective oxidation ofbromide in wastewater brines from hydraulic fracturing. _Water Research_.2013, 47(11): 3723 - 3731.

[0011] Patent Document 1: Publication No. CN109371416A, "A Method for Recovering Bromine from Bromine-Containing Wastewater".

[0012] Patent Document 2: Publication No. CN114956264A, "A Method for Separating Bromine from Liquid by Electrochemistry".

[0013] Patent Document 3: Publication No. CN116676621 A, "A Method for Separating Bromine from Liquid by Electrochemistry". Summary of the Invention

[0014] The present invention provides a low-energy consumption and high-efficiency bromine extraction coupled hydrogen production device and method based on forced convection, aiming to solve the problems of low bromine extraction efficiency, high energy consumption and poor synergy of traditional electrolytic cells and H-type cells under low-concentration conditions. By optimizing the device structure and electrode materials, efficient and low-energy consumption bromine extraction is achieved, and at the same time, hydrogen production is coupled to improve resource utilization rate.

[0015] To solve the above problems, the following solutions are adopted in the present invention: A bromine extraction coupled hydrogen production device based on forced convection includes a forced convection circulation flow cell, an anolyte system, and a catholyte system. The forced convection circulation flow cell includes an anodic chamber and a cathodic chamber, which are separated by a diaphragm. An anodic electrode is arranged in the anodic chamber, and the anodic electrode adopts acid heat-treated graphite felt AHGF or its CO 2 activation product AHGF-Y. A cathodic electrode is arranged in the cathodic chamber, and the cathodic electrode adopts platinum-loaded acid heat-treated graphite felt AHGF-Pt. The anolyte system is connected to the anodic chamber of the forced convection circulation flow cell, and the catholyte system is connected to the cathodic chamber of the forced convection circulation flow cell.

[0016] Further settings are as follows: The anolyte system includes a first container and a second container. The first container contains anolyte, and the first container is connected to the water inlet of the anodic chamber. A flow pump is arranged between the first container and the forced convection circulation flow cell to achieve forced convection, full mixing and circulation of the electrolyte through the flow pump; The second container contains carbon tetrachloride, and the second container is connected to the water outlet of the anodic chamber. The first container and the second container are connected by a flow pump to achieve the circulation of the anolyte; The catholyte system includes a third container, which is used to contain catholyte. The third container is connected to the water inlet of the cathodic chamber. A flow pump is arranged between the third container and the cathodic chamber to achieve forced convection, full mixing and circulation of the electrolyte through the flow pump. The water outlet of the cathodic chamber is connected to the third container to achieve the circulation of the catholyte.

[0017] The present invention also provides a bromine extraction coupled with hydrogen production method based on forced convection. In the bromine extraction coupled with hydrogen production device based on forced convection, forced convection, sufficient mixing and circulation of the electrolyte are achieved through a flow pump, so as to realize bromine extraction coupled with hydrogen production: (1) Bromine extraction The anolyte is fully mixed and circulated through a flow pump and delivered to the anode chamber to ensure sufficient contact between bromide ions and the anode electrode. The bromine generated in the anode chamber is extracted and separated by carbon tetrachloride; (2) Hydrogen production The catholyte is delivered to the cathode chamber through a flow pump. In the cathode chamber, protons obtain electrons on the surface of the cathode electrode to generate hydrogen gas, and the hydrogen gas generated in the cathode chamber is collected by a gas collection device.

[0018] The present invention also provides a forced convection circulation flow cell, which includes an anode chamber and a cathode chamber. The anode chamber and the cathode chamber are separated by a diaphragm. An anode electrode is arranged in the anode chamber, and the anode electrode adopts acid heat-treated graphite felt AHGF or its CO 2 activation product AHGF-Y. A cathode electrode is arranged in the cathode chamber, and the cathode electrode adopts platinum-loaded acid heat-treated graphite felt AHGF-Pt.

[0019] Furthermore: The diaphragm adopts a proton exchange membrane, and particularly preferably a proton exchange membrane Nafion 117.

[0020] The flow channel plate adopts a flow channel plate with a current collection function.

[0021] The anode electrode and the cathode electrode are embedded and installed in the anode chamber and the cathode chamber.

[0022] The acid heat-treated graphite felt AHGF is prepared by the following method: impregnate the graphite felt GF in a 3-12 M sulfuric acid solution for 12-36 h, wash it with deionized water until the pH is neutral, and then put it into a vacuum oven for drying to prepare an acid-modified graphite felt AGF; further air heat-treat it at 200-400 °C for 1-6 h to obtain the acid heat-treated graphite felt AHGF.

[0023] The CO of the acid heat-treated graphite felt 2 The activation product AHGF-Y is prepared by the following method: impregnate the graphite felt GF in a 3-12 M sulfuric acid solution for 12-36 h, wash it with deionized water until the pH is neutral, and then put it into a vacuum oven for drying to prepare an acid-modified graphite felt AGF; further air heat-treat it at 200-400 °C for 1-6 h to obtain the acid heat-treated graphite felt AHGF; in a tubular furnace, CO 2Heat it to 800 - 900 °C under an atmosphere and maintain at this temperature for 0.5 - 2.5 hours. Subsequently, cool it in a nitrogen stream to obtain the CO of the acid heat-treated graphite felt 2 Activated product AHGF-Y.

[0024] The platinum-loaded acid heat-treated graphite felt AHGF-Pt is prepared by the following method: Immerse the graphite felt GF in a 3 - 12 M sulfuric acid solution for 12 - 36 h, wash it with deionized water until the pH is neutral, and then place it in a vacuum oven for drying to prepare the acid-modified graphite felt AGF; further conduct air heat treatment at 200 - 400 °C for 1 - 6 h to obtain the acid heat-treated graphite felt AHGF; Immerse the acid heat-treated graphite felt AHGF into the H 2 PtCl 6 ·6H 2 O solution and magnetically stir at 25 - 50 °C for 0.5 - 5 hours; then transfer the treated graphite felt to a calcination tube and heat it at a heating rate of 2 - 10 °C / min in a hydrogen-argon mixed atmosphere at 300 - 600 °C for 1 - 10 hours to obtain the platinum-loaded acid heat-treated graphite felt AHGF-Pt.

[0025] On both sides of the diaphragm, a membrane frame, an electrode frame, a flow channel plate, a sealing gasket, and an end plate are symmetrically arranged from the inside out in sequence. The membrane frame, the electrode frame, the flow channel plate, the sealing gasket, and the end plate are connected into one body by hexagon screws. An inlet and an outlet are arranged on the end plate for the inflow and outflow of the electrolyte; the anode electrode and the cathode electrode are respectively embedded and installed on the electrode frame; the side of the diaphragm where the anode electrode is installed is the anode chamber, and the side of the diaphragm where the cathode electrode is installed is the cathode chamber.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) High-efficiency bromine extraction and low energy consumption: The present invention provides a forced convection circulation flow cell, which effectively overcomes the mass diffusion limitation of the traditional static electrochemical cell, significantly improves the bromine extraction efficiency and the system energy utilization rate. By optimizing the device structure and the electrode material, the problems of low bromine extraction efficiency, high energy consumption, and poor synergy of the traditional electrolytic cell and H-type cell under low bromine concentration conditions are solved, and high-efficiency and low-energy-consumption bromine extraction is realized.

[0027] (2) High Cl / Br ratio adaptability: By adopting the CO 2 activated AHGF-Y electrode, the present invention realizes high-efficiency bromine extraction under high Cl / Br ratio conditions in the forced convection circulation flow cell device. The bromine extraction rate is significantly improved, and at the same time, the energy consumption is greatly reduced, showing the characteristics of high efficiency and energy saving.

[0028] (3) Wide-range operation and low energy consumption: Under the condition of constant current operation (current range: 15 - 100 mA), the present invention can still achieve a high bromine extraction rate and low energy consumption (0.5 - 5.1 kJ / g) in a system with a low bromine concentration (0.05 g / L to 1 g / L Br - ) and a high Cl / Br ratio, demonstrating excellent performance stability.

[0029] (4) Strong environmental adaptability: In complex underground brines with a low bromine concentration and a high Cl / Br ratio containing various interfering ions (such as Cl - , Ba 2+ , Ca 2+ , K + , SO 4 2- , NO 3 - , etc.), the device of the present invention can still maintain a stable bromine extraction efficiency, demonstrating strong environmental adaptability and industrial application potential.

[0030] (5) Bromine extraction coupled with hydrogen production: The HBFC system of the present invention simultaneously generates hydrogen in the cathode chamber, realizing the co-production of bromine and hydrogen, providing an innovative solution for green energy utilization and sustainable chemical processes, and having significant economic and environmental benefits.

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0032] Figure 1 It is the result of chemical composition analysis of the AHGF-15 electrode sample prepared in Example 1 by using the SEM-EDS method.

[0033] Figure 2 It is the XRD pattern of the AHGF-Y electrodes prepared in Examples 1 and 5 and the AHGF electrode prepared in Example 6.

[0034] Figure 3 It is the structural schematic diagram of the forced convection circulation flow cell described in the present invention.

[0035] Figure 4 It is the structural schematic diagram of the bromine extraction coupled with hydrogen production device HBFC based on forced convection described in the present invention.

[0036] Figure 5 It is the comparison chart of LSV curves of the AHGF-Y electrodes prepared in Examples 1 and 5 and the AHGF electrode prepared in Example 6.

[0037] Figure 6 It is the constant current test chart of the AHGF-Y electrodes prepared in Examples 1 and 5 and the AHGF electrode prepared in Example 6.

[0038] Figure 7 Cyclic stability test results of the AHGF-15 electrode prepared in Example 1, showing the performance changes of the AHGF-15 electrode in three cyclic tests. Detailed implementation mode

[0039] The present invention will be specifically introduced below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited. The raw materials and equipment described in the embodiments are all known or commercially available products unless otherwise specified.

[0040] Example 1

[0041] Preparation of a CO 2 activation product (AHGF-Y) of acid-treated graphite felt, including the following steps: Immerse the graphite felt GF in 6 M sulfuric acid solution for 12 h, wash it with deionized water until the pH is neutral, and then place it in a vacuum oven for drying to obtain acid-modified graphite felt AGF. Further air heat treatment (300 °C, 2 h) is carried out to obtain acid-treated graphite felt, marked as AHGF.

[0042] Pass the previously prepared AHGF into CO 2 gas, activate it at 850 °C for 1.5 hours, and then naturally cool it to room temperature under N 2 atmosphere to obtain the CO 2 activation product of acid-treated graphite felt, marked as AHGF-15.

[0043] Examples 2 to 6 The preparation method is the same as that in Example 1, except that: for the prepared AHGF electrode, adjust the CO 2 activation process to prepare AHGF-Y electrodes with different performances, as shown in Table 1: Table 1, .

[0044] Combined with Table 1, Figures 1 to 2 shown: As Figure 1 shown is the chemical composition analysis of the AHGF-15 electrode sample prepared in Example 1 by the SEM-EDS method. According to Figure 1 the results show that: the prepared AHGF-15 electrode sample is mainly composed of carbon, nitrogen, and oxygen, and is evenly distributed.

[0045] Figure 2 XRD patterns of AHGF-Y electrodes prepared by different processes in Examples 1, 5, and 6. As Figure 2 shown, using CO 2The AHGF-Y electrode treated by the activation process, and without CO 2 Comparing with the AHGF electrode treated by the activation process, it was found that the crystal structure of the graphite felt was not affected by CO 2 activation.

[0046] Example 7

[0047] This example relates to the preparation of the AHGF-Pt electrode, including the following steps: (1) Immerse the graphite felt GF in 6 M sulfuric acid solution for 12 h, wash it with deionized water until the pH is neutral, and then put it into a vacuum oven for drying. The acid-modified graphite felt AGF was prepared. Then further heat-treat it in air at 300 °C for 2 h to obtain AHGF.

[0048] (2) Immerse the AHGF electrode completely into a solution of hexachloroplatinic acid hexahydrate (H 2 PtCl 6 ·6H 2 O) with a concentration of 19 mM so that the AHGF electrode is in full contact with the hexachloroplatinic acid hexahydrate solution; then stir magnetically at 30 °C for 1 hour.

[0049] (3) Transfer the treated graphite felt to a calcination tube, and heat it at 400 °C for 5 hours at a heating rate of 5 °C / min in a hydrogen-argon mixed atmosphere to prepare the AHGF-Pt electrode.

[0050] Example 8

[0051] This example relates to the preparation of the AHGF-Pt electrode, including the following steps: (1) Immerse the graphite felt GF in 6 M sulfuric acid solution for 12 h, wash it with deionized water until the pH is neutral, and then put it into a vacuum oven for drying. The acid-modified graphite felt AGF was prepared. Then further heat-treat it in air at 300 °C for 2 h to obtain AHGF.

[0052] (2) Immerse the prepared AHGF electrode completely into a solution of hexachloroplatinic acid hexahydrate (H 2 PtCl 6 ·6H 2 O) with a concentration of 10 mM so that the AHGF electrode is in full contact with the hexachloroplatinic acid hexahydrate solution; then stir magnetically at 50 °C for 0.5 hour.

[0053] (3) Transfer the treated graphite felt to a calcination tube, and heat it at 300 °C for 10 hours at a heating rate of 2 °C / min in a hydrogen-argon mixed atmosphere to prepare the AHGF-Pt electrode.

[0054] Example 9

[0055] This embodiment relates to the preparation of an AHGF-Pt electrode, which includes the following steps: (1) Immerse the graphite felt GF in 6 M sulfuric acid solution for 12 h, wash it with deionized water until the pH is neutral, and then place it in a vacuum oven for drying. The acid-modified graphite felt AGF was prepared. Further air heat treatment was carried out at 300 °C for 2 h to obtain AHGF.

[0056] (2) Immerse the prepared AHGF electrode completely into a 50 mM solution of hexahydrate chloroplatinic acid (H 2 PtCl 6 ·6H 2 O ) so that the AHGF electrode is in full contact with the hexahydrate chloroplatinic acid solution; then magnetically stir at 25 °C for 5 hours.

[0057] (3) Transfer the above-treated graphite felt to a calcination tube, and heat it at a heating rate of 10 °C / min in a hydrogen-argon mixed atmosphere at 600 °C for 1 hour to prepare the AHGF-Pt electrode.

[0058] Example 10

[0059] This embodiment mainly describes the structure and working principle of a forced convection circulation flow cell and its bromine extraction coupled hydrogen production device based on forced convection: (1) Construct a forced convection circulation flow cell Figure 3 A specific implementation of the forced convection circulation flow cell is shown. The flow cell includes a diaphragm 1, and on both sides of the diaphragm 1, a membrane frame 2, an electrode frame 3, a flow channel plate 5, a sealing gasket 6, and an end plate 7 are symmetrically arranged in sequence from the inside to the outside. The electrodes 4 are all embedded and installed on the electrode frame 3. The membrane frame 2, electrode frame 3, flow channel plate 5, sealing gasket 6, and end plate 7 are connected into one body by hexagon head screws 8. An inlet 10 and an outlet 9 are provided on the end plate 7 for the inflow and outflow of the electrolyte.

[0060] The electrode 4 includes an anode electrode and a cathode electrode. Among them: the side of the diaphragm 1 where the anode electrode is installed is the anode chamber, and the side of the diaphragm 1 where the cathode electrode is installed is the cathode chamber. The anode electrode uses the CO 2 activation product (AHGF-Y) of acid heat-treated graphite felt, which has a high specific surface area and abundant oxygen-containing functional groups, significantly improving the catalytic activity of the bromine oxidation reaction (BrOR); the cathode electrode uses AHGF loaded with platinum (AHGF-Pt), which efficiently catalyzes the hydrogen generation reaction (HER).

[0061] (2) Bromine extraction coupled hydrogen production device HBFC based on forced convection The forced convection circulating flow pool constructed by the present invention is used for bromine extraction coupled with hydrogen production to form a bromine extraction coupled with hydrogen production device HBFC based on forced convection, as shown in the following example: Figure 4 As shown: the bromine extraction coupled hydrogen production device HBFC includes a power supply 11, a forced convection circulation flow cell 12, an anode electrolyte system 13, and a cathode electrolyte system 14. The anode electrolyte system 13 is connected to the anode chamber of the forced convection circulation flow cell 12, and the cathode electrolyte system 14 is connected to the cathode chamber of the forced convection circulation flow cell 12.

[0062] The anode electrolyte system 13 includes a first container 131 and a second container 132. The first container 131 contains an anode electrolyte (bromine solution). The first container 131 is connected to the water inlet of the anode chamber. A flow pump 15 is provided between the first container 131 and the forced convection circulation flow tank 12. The flow pump is used to realize forced convection, full mixing and circulation of the electrolyte. The second container 132 contains carbon tetrachloride (CCl 4 ), the second container 132 is connected to the water outlet 9 of the anode chamber, and the first container 131 and the second container 132 are connected by a flow pump to realize the circulation of the anode electrolyte.

[0063] The cathode electrolyte system 14 includes a third container 141, which is used to contain the cathode electrolyte (H 2 SO 4 ), the third container 141 is connected to the water inlet of the cathode chamber, a flow pump 15 is arranged between the third container 141 and the cathode chamber, and the water outlet 9 of the cathode chamber is connected to the third container 141 to realize the circulation of the cathode electrolyte.

[0064] The power source 11 can be a power source in different forms, such as a wind power source.

[0065] The process flow of bromine extraction coupled with hydrogen production of the present invention is as follows: 1. Extraction of bromine In the bromine extraction coupled hydrogen production device HBFC based on forced convection of the present invention, the anode electrolyte is fully mixed and circulated by a flow pump and transported to the anode chamber to ensure that the bromide ions are in full contact with the anode electrode. The bromine element generated in the anode chamber is extracted by carbon tetrachloride, and the amount of bromine extracted is quantitatively analyzed by ion chromatography.

[0066] 2. Hydrogen production The cathode electrolyte is transported to the cathode chamber through a flow pump. In the cathode chamber, protons obtain electrons on the surface of the AHGF-Pt electrode to generate hydrogen. The hydrogen generated in the cathode chamber is collected by a gas collection device for subsequent use.

[0067] The bromine extraction coupled hydrogen production device HBFC based on forced convection of the present invention can be used for cyclic testing and non-cyclic testing: In the cyclic test, the mother liquor after extraction is continuously transported back to the system for cyclic extraction until the constant-current reaction ends.

[0068] In the non-cyclic test, the mother liquor after extraction is not continuously transported back to the system for repeated extraction.

[0069] The performance of the bromine extraction and hydrogen production device HBFC based on forced convection of the present invention is tested in combination with different embodiments. Unless otherwise specified in the embodiments, the experiments are carried out under the following conditions: at room temperature (25±3 °C) under the theoretical bromine extraction completion time (the theoretical bromine extraction time in this embodiment is 4830 s); carried out in a constant-current mode with the current set at 15 mA and controlled by an electrochemical workstation.

[0070] Regarding the experimental results of bromine extraction, they are characterized by energy consumption, bromine extraction rate, and Faraday efficiency: Energy consumption (kJ g -1 ) .

[0071] Bromine extraction rate (%) .

[0072] Faraday efficiency (%) .

[0073] Where: I is the current (A), t is the total reaction time (seconds), F is the Faraday constant (96485 C·mol -1 ), V ol represents the volume of the electrolyte in the anode chamber, V is the voltage (V), represents the molar concentration of bromide, and the subscripts "0" and "1" represent the initial and end moments of operation respectively. z represents the number of electrons transferred per molecule of Br ion (z = 1).

[0074] Example 11

[0075] This example mainly tests the bromine extraction performance of different electrodes in a forced convection circulation flow cell: using the AHGF-Y electrodes prepared in Examples 1-6 as the anode and the AHGF-Pt electrode prepared in Example 7 as the cathode, constructing a forced convection circulation flow cell according to the method of Example 10, and applying it to bromine extraction and hydrogen production to test the bromine extraction performance of different electrodes in the forced convection circulation flow cell.

[0076] The specific test methods and test results are as follows: 1. Electrolyte preparation: Anode electrolyte preparation: Prepare 1 g / L Br by mixing NaCl and NaBr -and 17 g / L Cl - solution as the mother liquor for bromine extraction. Take 40 mL of the mother liquor for bromine extraction and place it in the first container. Additionally, take 20 mL of the mother liquor for bromine extraction and mix it with 20 mL of carbon tetrachloride ( CCl 4 ), and place the mixture in the second container.

[0077] Catholyte preparation: Add 15 mL of 0.5 M H 2 SO 4 solution to the third container to promote the hydrogen evolution reaction (HER).

[0078] 2. Performance testing: The linear sweep voltammetry (LSV) method was used to evaluate the electrode performance. LSV tests were carried out in a solution of 1 g / L Br - and 17 g / L Cl - . The LSV test window was 0.4 - 1.4 V, and the long-term stability of the electrode was evaluated through 3 cyclic tests to ensure its efficient performance in the electrochemical bromine extraction process.

[0079] (1) Linear sweep voltammetry Figure 5 shows the comparison diagram of LSV curves of different electrodes prepared in Examples 1, 5, and 6. As Figure 5 the LSV test results show: After activation by CO 2 , the LSV onset potential of AHGF-Y is significantly shifted forward compared to AHGF, which proves that CO 2 activation enhances the catalytic ability of bromide ion extraction. Among all the samples, the AHGF-15 electrode prepared in Example 1 exhibits the best bromine extraction ability and can rapidly oxidize bromine at a lower potential.

[0080] (2) Constant current test method Figure 6 and Table 2 show the constant current test diagrams of different electrodes prepared in Examples 1, 5, and 6 in the flow cell, demonstrating the bromine extraction ability of different electrodes. As Figure 6 and Table 2 show: The constant current test diagrams of AHGF and AHGF-Y electrodes in the flow cell demonstrate the bromine extraction ability of different electrodes. The improved affinity of the AHGF-Y electrode solves the bromine oxidation problem and suppresses side reactions, thereby improving the bromine extraction performance and showing excellent durability, among which: The use of the AHGF-15 anode electrode exhibits superior performance and good cycle stability.

[0081] Table 2. Bromine extraction performance of AHGF and AHGF-Y electrodes in the flow cell .

[0082] (3)Cyclic stability test To further explore the stability of the active sites, the cyclic stability test was carried out on the AHGF-15 electrode prepared in Example 1 in a flow cell: after one constant-current bromine extraction was completed, the electrolytes in the anode chamber and the cathode chamber were all replaced, but the electrodes on both sides were not replaced, and the constant-current bromine extraction test was repeated.

[0083] Figure 7 The test results of the cyclic stability of the AHGF-15 electrode prepared in Example 1 are shown, demonstrating the performance changes of the AHGF-15 electrode in three cyclic tests, as Figure 7 shown: after three cycles, the bromine extraction performance of the AHGF-15 electrode remains stable. The cyclic stability test results show that AHGF-15 performs best in terms of bromine extraction rate, energy consumption, and Faraday efficiency, and is suitable for large-scale applications.

[0084] Example 12

[0085] This example mainly tests the bromine extraction performance under different current conditions: using the AHGF-15 electrode prepared in Example 1 as the anode and the AHGF-Pt electrode prepared in Example 7 as the cathode, a forced-convection circulation flow cell was constructed according to the method of Example 10 and applied to bromine extraction coupled with hydrogen production to test its bromine extraction efficiency and system performance under different current conditions.

[0086] (1)Electrolyte preparation: Anode electrolyte preparation: Take 83 mL of a bromide ion solution (Br - ) with a concentration of 1 g / L and a chloride ion solution (Cl - ) with a concentration of 17 g / L and mix them as the mother liquor for bromine extraction. Take 53 mL of the bromine extraction mother liquor and place it in a first container. Take another 30 mL of the bromine extraction mother liquor and mix it with 20 mL of carbon tetrachloride ( CCl 4 ) and place it in a second container.

[0087] Cathode electrolyte preparation: Add 30 mL of 0.5 M sulfuric acid solution (H 2 SO 4 ) to the cathode chamber to promote the hydrogen evolution reaction (HER).

[0088] (2)Test conditions The constant current was set to 15 - 100 mA, and the experimental duration was set to 1000 seconds. A cyclic test of bromine extraction performance was carried out.

[0089] Table 3. Bromine extraction performance of AHGF-15 at different currents .

[0090] As shown in Table 3: Under the condition of 15 mA current, electrochemically extracting bromine for 1000 s in 83 ml of electrolyte, the bromine extraction efficiency and Faraday efficiency cannot be compared with the bromine extraction efficiency at the 4830 s duration required for the theoretical bromine extraction completion time. By adjusting the current, the bromine extraction efficiency and Faraday efficiency are improved while reducing energy consumption.

[0091] The present invention can still achieve a high bromine extraction rate and low energy consumption (0.5 - 5.1 kJ / g) in a wide range (current range 15 - 100 mA), demonstrating excellent performance stability.

[0092] Example 13

[0093] This example mainly tests the bromine extraction performance at different initial bromine concentrations: Using the AHGF-15 electrode prepared in Example 1 as the anode and the AHGF-Pt electrode prepared in Example 7 as the cathode, a forced convection circulation flow cell is constructed according to the method of Example 10 and applied to bromine extraction coupled with hydrogen production to test its bromine extraction performance at different initial bromine concentrations.

[0094] (1) Electrolyte preparation: Anode electrolyte preparation: Prepare bromine extraction mother liquors with different bromide ion concentrations by NaCl and NaBr, as shown in Table 4. Take 40 mL of the bromine extraction mother liquor and place it in the first container, and take another 20 mL of the bromine extraction mother liquor and mix it with 20 mL of carbon tetrachloride ( CCl 4 ), and place it in the second container.

[0095] Cathode electrolyte preparation: Add 15 mL of 0.5 M H 2 SO 4 solution to the third container to promote the hydrogen evolution reaction (HER).

[0096] (2) Performance test A cyclic test of bromine extraction performance is carried out with a constant current of 15 mA at the theoretical bromine extraction completion time.

[0097] Table 4. Bromine extraction performance of AHGF-15 under theoretical complete charge extraction .

[0098] This example tests the bromine extraction performance of the AHGF-15 sample at different initial bromine concentrations. The bromide ion concentration and bromine extraction results are shown in Table 4: As the bromide ion concentration decreases, the energy consumption increases slightly, but compared with the reported bromine extraction systems, it can still maintain a high bromine extraction performance at a lower bromine concentration.

[0099] Example 14

[0100] This example mainly tests the bromine extraction performance of the present invention for underground brine: using the AHGF-15 electrode prepared in Example 1 as the anode and the AHGF-Pt electrode prepared in Example 7 as the cathode, a forced convection circulation flow cell was constructed according to the method of Example 10 to test the bromine extraction performance of the AHGF-15 electrode for real underground brine at different bromine extraction times.

[0101] (1) Electrolyte configuration: Anode electrolyte configuration: Take real underground brine, first extract the underground brine with CCl 4 to remove most of the organic matter, and then use ion chromatography to determine its composition as: 0.15 g L -1 Br - , 17.0 g L -1 Cl - , 0.044 g L -1 SO 4 2- and 0.027 g L -1 NO 3 - . Take 40 mL of the above bromine extraction mother liquor and place it in the first container. Another 20 mL of the bromine extraction mother liquor is mixed with 20 mL of carbon tetrachloride (CCl 4 ) and placed in the second container.

[0102] Cathode electrolyte configuration: Add 15 mL of 0.5 M H 2 SO 4 solution to the third container to promote the hydrogen evolution reaction (HER).

[0103] Test conditions: A cyclic test of bromine extraction performance was carried out at a constant current of 15 mA under the bromine extraction time corresponding to Table 5.

[0104] Table 5. Bromine extraction performance of AHGF-15 in underground brine .

[0105] As shown in Table 5: At a certain bromine extraction time, the extraction rate is significantly increased and the energy consumption is significantly reduced, but a high efficiency can still be maintained at a lower concentration. The experimental results show that in real underground brine, although there are interfering anions such as Cl - , SO 4 2- , NO 3 - etc. and cations Ba 2+ , Ca 2+ , K +Despite interference such as... etc., the electrode can still maintain efficient bromine extraction performance for a long time.

[0106] Example 15

[0107] This example mainly tests the bromine extraction performance of the electrode in an enlarged device: The AHGF-15 electrode prepared in Example 1 is used as the anode, and the AHGF-Pt electrode prepared in Example 7 is used as the cathode. A forced convection circulation flow cell is constructed according to the method of Example 10 to test the bromine extraction performance of the enlarged device.

[0108] (1) Preparation of electrolyte: Preparation of anolyte: A solution of 1 g / L Br - and 17 g / L Cl - is prepared by mixing NaCl and NaBr as the mother liquor for bromine extraction. A total of 1 L of the mother liquor for bromine extraction is taken for bromine extraction. 500 mL of it is placed in the first container, and another 500 mL of the mother liquor for bromine extraction is mixed with 500 mL of carbon tetrachloride (CCl 4 ) and placed in the second container.

[0109] Preparation of catholyte: 100 mL of 0.5 M H 2 SO 4 solution is added to the cathode chamber to promote the hydrogen evolution reaction (HER).

[0110] (2) Test conditions: A non-circulating test is carried out under a constant current of 15 mA. After 4000 s of bromine extraction is completed, the Faraday efficiency reaches 99.7%, and the energy consumption is only 2.57 kJ / g.

[0111] It should be noted that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by means of equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A bromine extraction coupled hydrogen production device based on forced convection, characterized in that: It includes a forced convection circulation flow cell, an anolyte system, and a cathode electrolyte system; the forced convection circulation flow cell includes an anode chamber and a cathode chamber, the anode chamber and the cathode chamber are separated by a diaphragm, an anode electrode is arranged in the anode chamber, the anode electrode is made of acid-heat-treated graphite felt AHGF or its CO2 activated product AHGF-Y, and a cathode electrode is arranged in the cathode chamber, the cathode electrode is made of platinum-loaded acid-heat-treated graphite felt AHGF-Pt, the anolyte system is connected to the anode chamber of the forced convection circulation flow cell, and the cathode electrolyte system is connected to the cathode chamber of the forced convection circulation flow cell.

2. A bromine extraction coupled hydrogen production device based on forced convection according to claim 1, characterized in that: The anode electrolyte system comprises a first container and a second container, wherein the first container contains the anode electrolyte, the first container is connected to the water inlet of the anode chamber, a flow pump is arranged between the first container and the forced convection circulation flow tank, and the flow pump is used to realize the forced convection, full mixing and circulation of the electrolyte; the second container contains carbon tetrachloride, the second container is connected to the water outlet of the anode chamber, the first container and the second container are connected by the flow pump, and the circulation of the anode electrolyte is realized; the cathode electrolyte system comprises a third container, the third container is used to contain the cathode electrolyte, the third container is connected to the water inlet of the cathode chamber, a flow pump is arranged between the third container and the cathode chamber, and the flow pump is used to realize the forced convection, full mixing and circulation of the electrolyte, and the water outlet of the cathode chamber is connected to the third container, and the circulation of the cathode electrolyte is realized.

3. A method for bromine extraction coupled with hydrogen production based on forced convection, characterized in that: In the bromine extraction coupled hydrogen production device based on forced convection as described in claim 1 or 2, forced convection and sufficient mixing and circulation of the electrolyte are achieved by a flow pump to achieve bromine extraction coupled hydrogen production: (1) Extraction of bromine The anolyte is fully mixed and circulated by a flow pump and transported to the anode chamber to ensure that the bromide ions are fully in contact with the anode electrode. The bromine element generated in the anode chamber is extracted and extracted by carbon tetrachloride; (2) Hydrogen production The cathode electrolyte is transported to the cathode chamber by a flow pump. In the cathode chamber, protons obtain electrons on the surface of the cathode electrode to generate hydrogen. The hydrogen generated in the cathode chamber is collected by a gas collection device.

4. A forced convection circulating flow pool, characterized in that: The invention comprises an anode chamber and a cathode chamber, wherein the anode chamber and the cathode chamber are separated by a diaphragm. The anode chamber is provided with an anode electrode, wherein the anode electrode is made of acid-heat-treated graphite felt AHGF or its CO2 activated product AHGF-Y. The cathode chamber is provided with a cathode electrode, wherein the cathode electrode is made of acid-heat-treated graphite felt AHGF-Pt loaded with platinum.

5. A forced convection circulation flow pool according to claim 4, characterized in that: The diaphragm is a proton exchange membrane.

6. A forced convection circulation flow pool according to claim 4, characterized in that: The anode electrode and the cathode electrode are embedded in the anode chamber and the cathode chamber.

7. A forced convection circulation flow pool according to claim 4, characterized in that: The acid-heat-treated graphite felt AHGF is prepared by the following method: the graphite felt GF is immersed in a 3-12 M sulfuric acid solution for 12-36 hours, washed with deionized water to a neutral pH, and then placed in a vacuum oven for drying to prepare an acid-modified graphite felt AGF; the acid-modified graphite felt AGF is air-heat-treated at 200-400° C. for 1-6 hours to obtain an acid-heat-treated graphite felt AHGF.

8. A forced convection circulation flow pool according to claim 4, characterized in that: The CO2 activated product AHGF-Y of the acid-heat treated graphite felt is prepared by the following method: the graphite felt GF is immersed in a 3-12 M sulfuric acid solution for 12-36 hours, washed with deionized water to a neutral pH, and then placed in a vacuum oven for drying to prepare an acid-modified graphite felt AGF; the acid-modified graphite felt AGF is air-heat treated at 200-400° C. for 1-6 hours to obtain an acid-heat treated graphite felt AHGF; the acid-heat treated graphite felt AHGF is placed in a tubular furnace, heated to 800-900° C. in a CO2 atmosphere, and maintained at this temperature for 0.5-2.5 hours, and then cooled in a nitrogen flow to obtain the CO2 activated product AHGF-Y of the acid-heat treated graphite felt.

9. A forced convection circulation flow pool according to claim 4, characterized in that: The platinum-loaded acid-heat-treated graphite felt AHGF-Pt is prepared by the following method: the graphite felt GF is immersed in a 3-12 M sulfuric acid solution for 12-36 hours, washed with deionized water to a neutral pH, and then placed in a vacuum oven for drying to prepare an acid-modified graphite felt AGF; the acid-modified graphite felt AGF is air-heat-treated at 200-400°C for 1-6 hours to obtain an acid-heat-treated graphite felt AHGF; the acid-heat-treated graphite felt AHGF is immersed in a H2PtCl6·6H2O solution, and after magnetic stirring at 25-50°C for 0.5-5 hours, it is transferred to a calcination tube and heated at 300-600°C for 1-10 hours at a heating rate of 2-10°C / min in a hydrogen-argon mixed atmosphere to obtain a platinum-loaded acid-heat-treated graphite felt AHGF-Pt.

10. A forced convection circulation flow pool according to claim 4, characterized in that: A membrane frame, an electrode frame, a flow channel plate, a sealing gasket, and an end plate are symmetrically arranged on both sides of the diaphragm from the inside to the outside. The membrane frame, the electrode frame, the flow channel plate, the sealing gasket, and the end plate are connected as a whole by hexagonal screws. A water inlet and a water outlet are arranged on the end plate for the flow in and out of the electrolyte; the anode electrode and the cathode electrode are respectively embedded and installed on the electrode frames on both sides of the diaphragm; The side of the diaphragm where the anode electrode is installed is the anode chamber, and the side of the diaphragm where the cathode electrode is installed is the cathode chamber.

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