A bromine extraction coupled hydrogen production device and method based on forced convection

Abstract

The present invention discloses a bromine extraction coupled hydrogen production device based on forced convection and its method, which relates to the technical field of synergistic hydrogen production from brine for bromine extraction. It is characterized in that: it includes a forced convection circulation flow cell, and 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, and the anode electrode adopts acid heat-treated graphite felt or its CO<subgt;2< / subgt>-activated product. A cathode electrode is arranged in the cathode chamber, and the cathode electrode adopts platinum-loaded acid heat-treated graphite felt. The forced convection circulation flow cell constructed by the present invention is used for bromine extraction coupled hydrogen production, which can realize efficient bromine extraction under the condition of high Cl / Br ratio, significantly improve the bromine extraction rate, and at the same time greatly reduce the energy consumption, showing the characteristics of high efficiency and energy saving.

Description

Technical Field

[0001] This invention patent relates to the technical field of bromine extraction and hydrogen production in a synergistic 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. The electrochemical bromine extraction method 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 treating low-concentration bromide ions such as underground brine. Therefore, developing a highly efficient 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:

[0004] Taking the research of scholars such as Sun Mei in non-patent literature 1 as an example, their team used graphite as the anode to study the electrochemical bromine extraction process, but this research only targeted relatively high-concentration bromides (~1 g / L). In addition, the current efficiency of its electrolysis process is relatively low, only 60% to 90%, and the energy consumption is relatively high, reaching 6 kJ / g.

[0005] In patent literature 1, an innovative method for oxidizing bromide ions (Br - ) to elemental bromine (Br2) 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 Br2. This process provides a new technical path for the efficient extraction of bromine.

[0006] The anode and cathode described in this patent can be separated by a diaphragm to form an anode region and a cathode region. Each region allows only the liquid-phase electrolyte to flow freely through, 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 + , SO4 2- , NO3 - etc. on the bromine extraction ability.

[0007] 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 electrochemically treating the bromine-containing liquid to oxidize Br - to Br2, achieving a high removal rate of bromine in the liquid.

[0008] 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 in the range of 3000 - 4000). Therefore, traditional electrodes are difficult to achieve efficient extraction and recovery under low-concentration bromine resources and high chloride ion interference in a complex wastewater system.

[0009] In Patent Document 3, a method for separating bromine from a liquid by electrochemistry is disclosed. This invention discloses an Ov-Co3O4NNs / Ti electrode for electrochemically extracting bromine 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, restricting its potential for industrial application.

[0010] Although many efforts have been made in improving the electrochemically extracting bromine 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 restricts its potential for actual large-scale application. Thus, there is an urgent need to develop technical processes with simple processes and devices, easy to operate, low operating costs, and practical application feasibility.

[0011] 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.

[0012] Patent Document 1: Publication No. CN109371416A, "A Method for Recovering Bromine from Wastewater Containing Bromine".

[0013] Patent Document 2: Publication No. CN114956264A, "A Method for Separating Bromine from Liquid by Electrochemistry".

[0014] Patent Document 3: Publication No. CN116676621 A, "A Method for Separating Bromine from Liquid by Electrochemistry". Summary of the Invention

[0015] The present invention provides a low - energy - consumption and high - efficiency bromine extraction coupled with 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.

[0016] To solve the above problems, the following solutions are adopted in the present invention:

[0017] A bromine extraction coupled with hydrogen production device based on forced convection includes a forced - convection circulating flow cell, an anolyte system, and a catholyte system. The forced - convection circulating 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 uses acid - heat - treated graphite felt AHGF or its CO2 - activated product AHGF - Y. A cathodic electrode is arranged in the cathodic chamber, and the cathodic electrode uses platinum - loaded acid - heat - treated graphite felt AHGF - Pt. The anolyte system is connected to the anodic chamber of the forced - convection circulating flow cell, and the catholyte system is connected to the cathodic chamber of the forced - convection circulating flow cell.

[0018] 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 circulating 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 realize 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 realize the circulation of the catholyte.

[0019] The present invention also provides a method for bromine extraction coupled with hydrogen production 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 by a flow pump to achieve bromine extraction coupled with hydrogen production:

[0020] (1) Extraction of bromine

[0021] 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;

[0022] (2) Hydrogen production

[0023] 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 cathode electrode to generate hydrogen. The hydrogen generated in the cathode chamber is collected by a gas collection device.

[0024] The present invention also provides a forced convection circulating flow cell, comprising an anode chamber and a cathode chamber, the anode chamber and the cathode chamber being separated by a diaphragm, an anode electrode being arranged in the anode chamber, the anode electrode being made of acid-heat-treated graphite felt AHGF or its CO2 activated product AHGF-Y, and a cathode electrode being arranged in the cathode chamber, the cathode electrode being made of platinum-loaded acid-heat-treated graphite felt AHGF-Pt.

[0025] Further:

[0026] The diaphragm is a proton exchange membrane, and Nafion 117 is particularly preferred.

[0027] The flow channel plate is a flow channel plate with a current collecting function.

[0028] The anode electrode and the cathode electrode are embedded in the anode chamber and the cathode chamber.

[0029] The acid-heat-treated graphite felt AHGF is prepared by the following method: immersing the graphite felt GF in a 3-12 M sulfuric acid solution for 12-36 hours, washing with deionized water to a neutral pH, and then placing it in a vacuum oven for drying to prepare an acid-modified graphite felt AGF; and further air-heat-treating it at 200-400 degrees for 1-6 hours to obtain the acid-heat-treated graphite felt AHGF.

[0030] The CO2 activation product AHGF-Y of the acid heat-treated graphite felt 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 perform air heat treatment at 200-400 °C for 1-6 h to obtain the acid heat-treated graphite felt AHGF; in a tubular furnace, heat it to 800-900 °C under a CO2 atmosphere and maintain it at this temperature for 0.5-2.5 hours, and then cool it in a nitrogen stream to obtain the CO2 activation product AHGF-Y of the acid heat-treated graphite felt.

[0031] 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 perform 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 in an H2PtCl6·6H2O solution and magnetically stir it 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.

[0032] 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 provided on the end plate for the inflow and outflow of the electrolyte; the anode electrode and the cathode electrode are respectively installed on the electrode frame in an embedded manner; 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.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (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 the H-type cell under low bromine concentration conditions are solved, and high-efficiency and low-energy-consumption bromine extraction is realized.

[0035] (2) High Cl / Br ratio adaptability: By adopting the CO2-activated AHGF-Y electrode, the present invention achieves efficient bromine extraction under high Cl / Br ratio conditions in a 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.

[0036] (3) Wide range of operation and low energy consumption: Under constant current operation conditions (current range 15 - 100 mA), the present invention can still achieve a relatively high bromine extraction rate and low energy consumption (0.5 - 5.1 kJ / g) in a low bromine concentration (0.05 g / L to 1 g / L Br - ) and high Cl / Br ratio system, demonstrating excellent performance stability.

[0037] (4) Strong environmental adaptability: In low bromine concentration and high Cl / Br ratio complex underground brines containing various interfering ions (such as Cl - , Ba 2+ , Ca 2+ , K + , SO4 2- , NO3 - , etc.), the device of the present invention can still maintain a stable bromine extraction efficiency, demonstrating strong environmental adaptability and industrial application potential.

[0038] (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.

[0039] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0040] Figure 1 It is the result of chemical composition analysis of the AHGF-15 electrode sample prepared in Example 1 by the SEM-EDS method.

[0041] 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.

[0042] Figure 3 It is the structural schematic diagram of the forced convection circulation flow cell described in the present invention.

[0043] 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.

[0044] Figure 5Comparison chart of LSV curves of AHGF-Y electrodes prepared in Examples 1 and 5 and AHGF electrodes prepared in Example 6.

[0045] Figure 6 Constant current test chart of AHGF-Y electrodes prepared in Examples 1 and 5 and AHGF electrodes prepared in Example 6.

[0046] 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. Specific implementation manners

[0047] 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 thereto. The raw materials and equipment described in the embodiments are all known or commercially available products unless otherwise specified.

[0048] Example 1

[0049] Preparation of a CO2 activation product (AHGF-Y) of acid-treated graphite felt includes the following steps:

[0050] 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 an acid-modified graphite felt AGF. Further air heat treatment (300 °C, 2 h) is carried out to obtain an acid-treated graphite felt, marked as AHGF.

[0051] The previously prepared AHGF is passed through CO2 gas, activated at 850 °C for 1.5 hours, and then naturally cooled to room temperature under a N2 atmosphere to obtain a CO2 activation product of acid-treated graphite felt, marked as AHGF-15.

[0052] Examples 2 to 6

[0053] The preparation method is the same as that in Example 1, except that for the prepared AHGF electrodes, the CO2 activation process is adjusted to prepare AHGF-Y electrodes with different performances, as shown in Table 1:

[0054] Table 1,

[0055] .

[0056] Combined with Table 1, Figures 1 to 2 as shown:

[0057] 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 1The results show that the prepared AHGF-15 electrode sample is mainly composed of carbon, nitrogen, and oxygen, and is evenly distributed.

[0058] Figure 2 XRD patterns of AHGF-Y electrodes prepared by different processes in Examples 1, 5, and 6. As Figure 2 shown, by comparing the AHGF-Y electrode treated with the CO2 activation process and the AHGF electrode without the CO2 activation process, it is found that the crystal structure of the graphite felt is not affected by the CO2 activation.

[0059] Example 7

[0060] This example relates to the preparation of an AHGF-Pt electrode, which includes the following steps:

[0061] (1) Immerse the graphite felt GF in a 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 is prepared. Further air heat treatment is carried out at 300 °C for 2 h to obtain AHGF.

[0062] (2) Immerse the AHGF electrode completely into a 19 mM solution of hexachloroplatinic acid hexahydrate (H2PtCl6·6H2O) so that the AHGF electrode is in full contact with the hexachloroplatinic acid solution; then stir magnetically at 30 °C for 1 hour.

[0063] (3) Transfer the above-treated graphite felt to a calcination tube and heat it at a heating rate of 5 °C / min in a hydrogen-argon mixed atmosphere at 400 °C for 5 hours to prepare the AHGF-Pt electrode.

[0064] Example 8

[0065] This example relates to the preparation of an AHGF-Pt electrode, which includes the following steps:

[0066] (1) Immerse the graphite felt GF in a 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 is prepared. Further air heat treatment is carried out at 300 °C for 2 h to obtain AHGF.

[0067] (2) Immerse the prepared AHGF electrode completely into a 10 mM solution of hexachloroplatinic acid hexahydrate (H2PtCl6·6H2O) so that the AHGF electrode is in full contact with the hexachloroplatinic acid solution; then stir magnetically at 50 °C for 0.5 hour.

[0068] (3) Transfer the above-treated graphite felt into a calcination tube, and heat it at a heating rate of 2 °C / min in a hydrogen-argon mixed atmosphere at 300 °C for 10 hours to prepare the AHGF-Pt electrode.

[0069] Example 9

[0070] This example relates to the preparation of an AHGF-Pt electrode, including the following steps:

[0071] (1) Immerse the graphite felt GF in a 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 heat-treat it in air at 300 °C for 2 h to obtain AHGF.

[0072] (2) Immerse the prepared AHGF electrode completely into a 50 mM solution of chloroplatinic acid hexahydrate (H2PtCl6·6H2O) so that the AHGF electrode is in full contact with the chloroplatinic acid hexahydrate solution; then stir magnetically at 25 °C for 5 hours.

[0073] (3) Transfer the above-treated graphite felt into 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.

[0074] Example 10

[0075] This example 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:

[0076] (1) Construct a forced convection circulation flow cell

[0077] Figure 3 A specific embodiment 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 out. The electrodes 4 are all embedded and installed on the electrode frame 3. The membrane frame 2, the electrode frame 3, the flow channel plate 5, the sealing gasket 6, and the end plate 7 are connected into one body by hexagon screws 8. An inlet 10 and an outlet 9 are provided on the end plate 7 for the inflow and outflow of the electrolyte.

[0078] The electrode 4 includes an anode electrode and a cathode electrode, where: 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 CO2 activation product (AHGF-Y) of acid-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 platinum-loaded AHGF (AHGF-Pt), which efficiently catalyzes the hydrogen generation reaction (HER).

[0079] (2)Hydrobromine extraction coupled hydrogen production device HBFC based on forced convection

[0080] The above-mentioned forced convection circulation flow cell constructed by the present invention is used for hydrobromine extraction coupled hydrogen production, and a hydrobromine extraction coupled hydrogen production device HBFC based on forced convection is formed, specifically as Figure 4 shown: The hydrobromine extraction coupled hydrogen production device HBFC includes a power supply 11, a forced convection circulation flow cell 12, an anolyte system 13, a catholyte system 14. The anolyte system 13 is connected to the anode chamber of the forced convection circulation flow cell 12, and the catholyte system 14 is connected to the cathode chamber of the forced convection circulation flow cell 12.

[0081] The anolyte system 13 includes a first container 131 and a second container 132. The first container 131 contains an anolyte (bromine-containing solution). The first container 131 is connected to the water inlet of the anode chamber. A flow pump 15 is arranged between the first container 131 and the forced convection circulation flow cell 12 to achieve forced convection, full mixing and circulation of the electrolyte. The second container 132 contains carbon tetrachloride (CCl4). The second container 132 is connected to the water outlet 9 of the anode chamber. The first container 131 and the second container 132 are connected by a flow pump to achieve the circulation of the anolyte.

[0082] The catholyte system 14 includes a third container 141. The third container 141 is used to contain a catholyte (H2SO4). 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. The water outlet 9 of the cathode chamber is connected to the third container 141 to achieve the circulation of the catholyte.

[0083] The power supply 11 can adopt different forms of power supplies, such as a wind power supply.

[0084] The hydrobromine extraction coupled hydrogen production process of the present invention is as follows:

[0085] 1. Hydrobromine extraction

[0086] In the bromine extraction coupled hydrogen production device HBFC based on forced convection of the present invention, the anolyte is fully mixed and circulated by a flow pump and transported to the anode chamber to ensure sufficient contact between bromide ions and the anode electrode. The bromine generated in the anode chamber is extracted by carbon tetrachloride, and the amount of bromine extracted is quantitatively analyzed by ion chromatography.

[0087] 2. Hydrogen production

[0088] The catholyte is transported to the cathode chamber by a flow pump. In the cathode chamber, protons obtain electrons on the surface of the AHGF-Pt electrode to generate hydrogen gas, and the hydrogen gas generated in the cathode chamber is collected by a gas collection device for subsequent use.

[0089] The bromine extraction coupled hydrogen production device HBFC based on forced convection of the present invention can be used for cyclic tests and non-cyclic tests:

[0090] 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.

[0091] In the non-cyclic test, the mother liquor after extraction is not continuously transported back to the system for repeated extraction.

[0092] The performance of the bromine extraction coupled 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 the constant current mode, the current is set to 15 mA, and is controlled by an electrochemical workstation.

[0093] Regarding the experimental results of bromine extraction, they are characterized by energy consumption, bromine extraction rate, and Faraday efficiency:

[0094] Energy consumption (kJ g -1 )

[0095] .

[0096] Bromine extraction rate (%)

[0097] .

[0098] Faraday efficiency (%)

[0099] .

[0100] Among them: 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 anolyte in the anode chamber, V is the voltage (V), represents the molar concentration of bromide, where the subscripts "0" and "1" represent the initial and end moments of the operation, respectively. z represents the number of electron transfers per Br ion molecule (z = 1).

[0101] Example 11

[0102] 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 coupled with hydrogen production to test the bromine extraction performance of different electrodes in the forced convection circulation flow cell.

[0103] The specific test methods and results are as follows:

[0104] 1. Electrolyte preparation:

[0105] Anode electrolyte preparation: Prepare a solution of 1 g / L Br - and 17 g / L Cl - using NaCl and NaBr as the bromine extraction mother liquor. Take 40 mL of the bromine extraction mother liquor and place it in a first container. Take another 20 mL of the bromine extraction mother liquor and mix it with 20 mL of carbon tetrachloride ( CCl4) and place it in a second container.

[0106] Cathode electrolyte preparation: Add 15 mL of 0.5 M H2SO4 solution to a third container to promote the hydrogen evolution reaction (HER).

[0107] 2. Performance test:

[0108] The linear sweep voltammetry (LSV) method is used to evaluate the electrode performance. LSV tests are carried out in a solution of 1 g / L Br - and 17 g / L Cl - The LSV test window is 0.4 - 1.4 V, and the long-term stability of the electrode is evaluated through 3 cyclic tests to ensure its high efficiency performance in the electrochemical bromine extraction process.

[0109] (1) Linear sweep voltammetry

[0110] Figure 5 shows the comparison diagram of the LSV curves of different electrodes prepared in Examples 1, 5, and 6. As Figure 5The LSV test results show that: after CO2 activation, the LSV onset potential of AHGF-Y is significantly shifted forward compared to AHGF, which proves that CO2 activation enhances the catalytic ability of bromide 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.

[0111] (2)Chronocoulometry

[0112] Figure 6 Figures and Table 2 show the chronocoulometry diagrams of different electrodes prepared in Examples 1, 5, and 6 in a flow cell, demonstrating the bromine extraction capabilities of different electrodes. As Figure 6 shown in Figures and Table 2: The chronocoulometry diagrams of AHGF and AHGF-Y electrodes in a flow cell demonstrate the bromine extraction capabilities of different electrodes. The improved affinity of the AHGF-Y electrode solves the bromine oxidation problem, inhibits side reactions, thereby improving the bromine extraction performance and exhibiting excellent durability, among which: the use of the AHGF-15 anode electrode shows superior performance and good cycle stability.

[0113] Table 2. Bromine extraction performance of AHGF and AHGF-Y electrodes in a flow cell

[0114] 。

[0115] (3)Cycle stability test

[0116] To further explore the stability of active sites, a cycle stability test was carried out on the AHGF-15 electrode prepared in Example 1 in a flow cell: after one chronocoulometric bromine extraction, the electrolytes in the anode chamber and the cathode chamber were all replaced, but the electrodes on both sides were not replaced, and the chronocoulometric bromine extraction test was repeated.

[0117] Figure 7 Figures show the test results of the cycle stability of the AHGF-15 electrode prepared in Example 1, demonstrating the performance changes of the AHGF-15 electrode in 3 cycle tests. As Figure 7 shown: after three cycles, the bromine extraction performance of the AHGF-15 electrode remains stable. The cycle 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.

[0118] Example 12

[0119] 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.

[0120] (1) Electrolyte preparation:

[0121] Anodic electrolyte preparation: Take 83 mL of a bromide ion solution with a concentration of 1 g / L (Br - ) and mix it with a chloride ion solution with a concentration of 17 g / L (Cl - ) to obtain the mother liquor for bromine extraction. Take 53 mL of the mother liquor for bromine extraction and place it in the first container. Separately, take 30 mL of the mother liquor for bromine extraction and mix it with 20 mL of carbon tetrachloride ( CCl4), and place the mixture in the second container.

[0122] Cathodic electrolyte preparation: Add 30 mL of 0.5 M sulfuric acid solution (H2SO4) to the cathode chamber to promote the hydrogen evolution reaction (HER).

[0123] (2) Test conditions

[0124] The constant current is set to 15 - 100 mA, and the experimental duration is set to 1000 seconds. A cyclic test of bromine extraction performance is carried out.

[0125] Table 3. Bromine extraction performance of AHGF-15 at different currents

[0126] .

[0127] As shown in Table 3: At a current of 15 mA, in 83 ml of electrolyte, the bromine extraction efficiency and Faraday efficiency during 1000 s of electrochemical bromine extraction cannot be compared with the bromine extraction efficiency at the theoretical bromine extraction completion time of 4830 s. By adjusting the current, the bromine extraction efficiency and Faraday efficiency are improved while reducing energy consumption.

[0128] 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.

[0129] Example 13

[0130] 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.

[0131] (1) Electrolyte preparation:

[0132] Anolyte preparation: Bromine extraction mother liquors with different bromide ion concentrations were prepared by mixing NaCl and NaBr, as shown in Table 4. 40 mL of the bromine extraction mother liquor was placed in a first container, and another 20 mL of the bromine extraction mother liquor was mixed with 20 mL of carbon tetrachloride ( CCl4) and placed in a second container.

[0133] Catholyte preparation: 15 mL of 0.5 M H2SO4 solution was added to a third container to promote the hydrogen evolution reaction (HER).

[0134] (2) Performance testing

[0135] A cyclic test of bromine extraction performance was carried out at a constant current of 15 mA under the theoretical bromine extraction completion time.

[0136] Table 4. Bromine extraction performance of AHGF-15 under theoretical complete charge extraction

[0137] .

[0138] In this example, the bromine extraction performance of the AHGF-15 sample was studied 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 slightly increases, but compared with the reported bromine extraction systems, it can still maintain a high bromine extraction performance at a lower bromine concentration.

[0139] Example 14

[0140] This example mainly tested 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, and the bromine extraction performance of the AHGF-15 electrode for real underground brine was tested at different bromine extraction times.

[0141] (1) Electrolyte preparation:

[0142] Anolyte preparation:

[0143] Take real underground brine. First, extract the underground brine with CCl4 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 SO4 2- and 0.027 g L -1 NO3 -。Take 40 mL of the above-mentioned bromine-extracted mother liquor and place it in the first container. Separately, take 20 mL of the bromine-extracted mother liquor and mix it with 20 mL of carbon tetrachloride (CCl4), and place it in the second container.

[0144] Catholyte configuration:

[0145] Add 15 mL of 0.5 M H2SO4 solution to the third container to promote the hydrogen evolution reaction (HER).

[0146] Test conditions:

[0147] Perform cyclic tests on the bromine extraction performance at a constant current of 15 mA under the bromine extraction time corresponding to Table 5.

[0148] Table 5. Bromine extraction performance of AHGF-15 in underground brine

[0149] 。

[0150] As shown in Table 5: At a certain bromine extraction time, the extraction rate is significantly improved 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, despite the interference of anionic impurities such as Cl - , SO4 2- , NO3 - and cationic impurities such as Ba 2+ , Ca 2+ , K + etc., this electrode can still maintain high-efficiency bromine extraction performance for a long time.

[0151] Example 15

[0152] This example mainly tests the bromine extraction performance of the electrode in the scaled-up device: Using the AHGF-15 electrode prepared in Example 1 as the anode and the AHGF-Pt electrode prepared in Example 7 as the cathode, construct a forced convection circulation flow cell according to the method of Example 10 to test the bromine extraction performance of the scaled-up device.

[0153] (1) Electrolyte configuration:

[0154] Anolyte configuration: Prepare a solution of 1 g / L Br - and 17 g / L Cl - using NaCl and NaBr as the bromine-extracted mother liquor. A total of 1 L of the bromine-extracted mother liquor is taken for bromine extraction, 500 mL of which is placed in the first container, and another 500 mL of the bromine-extracted mother liquor is mixed with 500 mL of carbon tetrachloride (CCl4) and placed in the second container.

[0155] Catholyte configuration: Add 100 mL of 0.5 M H2SO4 solution for promoting hydrogen evolution reaction (HER).

[0156] (2) Test conditions:

[0157] Under a constant current of 15 mA, a non-cyclic test was carried out. After the bromine extraction was completed in 4000 s, the Faraday efficiency reached 99.7% while the energy consumption was only 2.57 kJ / g.

[0158] 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 replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A bromine extraction and hydrogen production coupling device based on forced convection, characterized in that: The invention comprises a forced convection circulating flow cell, an anolyte system, and a catholyte system; the forced convection circulating flow cell comprises 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 adopts AHGF-Y, a CO2 activation product of acid-heat-treated graphite felt, and a cathode electrode is arranged in the cathode chamber, the cathode electrode adopts AHGF-Pt, an acid-heat-treated graphite felt loaded with platinum, the anolyte system is connected to the anode chamber of the forced convection circulating flow cell, and the catholyte system is connected to the cathode chamber of the forced convection circulating flow cell; 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 tube furnace, heated to 800-900° C. under a CO2 atmosphere, maintained at this temperature for 1-2 hours, and then cooled in a nitrogen flow to obtain the CO2 activated product AHGF-Y of the acid-heat treated graphite felt.

2. The bromine extraction coupled hydrogen production device based on forced convection according to claim 1, wherein: The anolyte system includes a first container and a second container, wherein the first container contains anolyte, the first container is connected to the water inlet of the anode chamber, a flow pump is provided between the first container and the forced convection circulation flow pool, and the flow pump is used to realize forced convection, sufficient 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, and the first container and the second container are connected by the flow pump to realize circulation of the anolyte; the cathode electrolyte system includes a third container, the third container is used to accommodate cathode electrolyte, the third container is connected to the water inlet of the cathode chamber, a flow pump is provided between the third container and the cathode chamber, and the flow pump is used to realize forced convection, sufficient mixing and circulation of the electrolyte, and the water outlet of the cathode chamber is connected to the third container to realize circulation of the cathode electrolyte.

3. A bromine extraction coupled with hydrogen production method based on forced convection, characterized in that: In the bromine extraction coupled with hydrogen production device based on forced convection as described in claim 1 or 2, forced convection, sufficient mixing and circulation of the electrolyte are achieved by a flow pump to achieve bromine extraction coupled with 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 through 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 circulation flow cell, 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, wherein an anode electrode is arranged in the anode chamber, wherein the anode electrode adopts AHGF-Y, a CO2 activated product of acid-heat-treated graphite felt, and a cathode electrode is arranged in the cathode chamber, wherein the cathode electrode adopts AHGF-Pt, an acid-heat-treated graphite felt loaded with platinum; The CO2 activation product AHGF-Y of the acid heat-treated graphite felt 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 dry it in a vacuum oven to prepare the acid-modified graphite felt AGF; Heat-treat the acid-modified graphite felt AGF in air at 200-400 °C for 1-6 h to obtain the acid heat-treated graphite felt AHGF; Place the acid heat-treated graphite felt AHGF in a tubular furnace, heat it to 800-900 °C in a CO2 atmosphere, and keep it at this temperature for 1-2 hours, and then cool it in a nitrogen stream to obtain the CO2 activation product AHGF-Y of the acid heat-treated graphite felt.

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

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

7. The forced convection circulation flow cell according to claim 4, characterized in that: 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 dry it in a vacuum oven to prepare the acid-modified graphite felt AGF; Heat-treat the acid-modified graphite felt AGF in air 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 in an H2PtCl6·6H2O solution, magnetically stir it at 25-50 °C for 0.5-5 hours, then transfer it 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.

8. The forced convection circulation flow cell according to claim 4, characterized in that: 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 to the outside 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 provided 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 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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