Hydrogen peroxide synthesis device and hydrogen peroxide preparation method

Abstract

The invention discloses a hydrogen peroxide synthesis device and a hydrogen peroxide preparation method, the device comprises: an anode tank, two sides of which are respectively provided with an electrolyte inlet and an electrolyte outlet; an electrolyte inlet and a product outlet are respectively formed in two sides of the cathode tank; a gas inlet and a gas outlet are respectively formed in two sides of the gas chamber; an anode electrode is arranged between the anode tank and the cathode tank, an anion exchange membrane is arranged between the anode electrode and the cathode tank, and a cathode electrode is arranged between the cathode tank and the gas chamber. The device is a three-chamber flow type electrolytic cell, a three-phase interface formed by the device is uniform and stable, and gas and liquid can be in uniform contact with a catalyst, so that catalytic sites on the surface of the catalyst are fully utilized. Excessive oxygen penetrates through the carbon paper to cause extra pressure on a catalytic interface, so that newly generated hydrogen peroxide is quickly extruded into electrolyte from active sites, the local high-concentration effect of hydrogen peroxide is reduced, the preparation efficiency of hydrogen peroxide is improved, and meanwhile, catalytic sites are protected.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemistry, and in particular to a hydrogen peroxide synthesis device and a hydrogen peroxide preparation method. Background Art

[0002] Hydrogen peroxide is one of the most important inorganic compounds in the world. It is used as an oxidant or fuel in chemical production, electronic manufacturing and water treatment industries, and is also a green disinfectant for public health use. It is also a high-value environmentally friendly oxidant, and its reaction product is only water, which is recognized as one of the cleanest chemicals. At present, the annual production of hydrogen peroxide is about 4 million tons, of which more than 95% is produced by the anthraquinone method, which is energy-intensive, requires large investments, and has a complex operating process. In contrast, the direct preparation of hydrogen peroxide using electrical energy to reduce oxygen uses renewable electricity as a low-cost, energy-saving, and direct preparation method. This method provides a promising direction for the production of hydrogen peroxide.

[0003] The electrolyzers currently used in electrocatalysis are basically two-chamber flow-type electrolyzers, where the reactant oxygen and the electrolyte are introduced simultaneously to react on the electrode surface. However, this device cannot evenly form a solid-liquid-gas three-phase interface, and it is easy to form a state of local oxygen or local liquid, resulting in the inability to fully utilize the catalytic sites on the catalyst surface. Moreover, at industrial current densities (>300mA cm -2 ), a large amount of hydrogen peroxide generated instantly cannot leave in time and accumulates at the gas diffusion electrode reaction interface, causing the local hydrogen peroxide concentration to be too high. A high local concentration of hydrogen peroxide will have the following hazards: 1. Corrosion of the catalytic interface, reducing the catalytic sites; 2. Hydrogen peroxide is further reduced to water on the catalyst surface, or undergoes disproportionation reaction, resulting in reduced hydrogen peroxide yield and selectivity; 3. Accelerate the hydrophilic evolution of the catalyst surface, hindering gas transfer.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a hydrogen peroxide synthesis device and a hydrogen peroxide preparation method, so as to solve the problem that it is difficult to prepare hydrogen peroxide by reducing oxygen efficiently and stably under industrial-grade current density.

[0006] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0007] A first aspect of the present invention provides a hydrogen peroxide synthesis device, comprising:

[0008] an anode tank, wherein one side of the anode tank is provided with an electrolyte inlet, and the other side of the anode tank is provided with an electrolyte outlet;

[0009] A cathode tank, wherein one side of the cathode tank is provided with an electrolyte inlet, and the other side of the cathode tank is provided with a product outlet;

[0010] A gas chamber, wherein one side of the gas chamber is provided with an air inlet, and the other side of the gas chamber is provided with an air outlet;

[0011] An anode electrode is arranged between the anode tank and the cathode tank, an anion exchange membrane is arranged between the anode electrode and the cathode tank, and a cathode electrode is arranged between the cathode tank and the gas chamber.

[0012] Preferably, the cathode electrode is carbon paper.

[0013] Preferably, one side of the carbon paper coated with the hydrophobic layer faces the electrolyte, and the other side faces the gas chamber.

[0014] A second aspect of the present invention provides a method for preparing hydrogen peroxide using the above-mentioned synthesis device, the method comprising the following steps:

[0015] The electrolyte is introduced through the electrolyte inlet on the cathode tank and the electrolyte inlet on the anode tank, wherein the electrolyte includes water and electrolyte;

[0016] introducing oxygen through the gas inlet of the gas chamber;

[0017] Connecting the cathode electrode and the anode electrode to an external power source;

[0018] The water in the electrolyte reacts with the introduced oxygen on the cathode electrode to generate hydroxide and hydrogen peroxide, and the hydrogen peroxide is discharged through the product outlet on the cathode tank and then collected.

[0019] Preferably, the current density of the external power supply is 1 to 1500 mA / cm 2 The flow rate of the oxygen gas is 1-100 mL / min.

[0020] Preferably, the electrolyte is selected from one of sulfuric acid, hydrochloric acid, sodium sulfate, potassium sulfate, potassium hydroxide and sodium hydroxide.

[0021] Preferably, when the electrolyte is potassium hydroxide or sodium hydroxide, the molar concentration of the cations in the electrolyte is 0.01-10 mol / L.

[0022] Preferably, when the electrolyte is potassium sulfate or sodium sulfate, the molar concentration of sodium ions in the electrolyte is 0.01-10 mol / L.

[0023] Preferably, the flow rate of the electrolyte is 1-50 mL / min.

[0024] Beneficial effects:

[0025] The invention discloses a hydrogen peroxide synthesis device and a hydrogen peroxide preparation method. The hydrogen peroxide synthesis device provided by the invention is a three-chamber flow-type electrolyzer. The device can realize that oxygen passes through a gas diffusion electrode to reach a catalytic surface, and is reduced on the catalyst to generate hydrogen peroxide. At the same time, excess oxygen passes through carbon paper to reach a catalytic layer, and the generated hydrogen peroxide is pushed away from the catalyst surface, thereby reducing the local high concentration effect of the catalytic layer. The three-phase interface formed by the device is uniform and stable, and both gas and liquid can be in uniform contact with the catalyst, so that the catalytic sites on the catalyst surface are fully protected and utilized, thereby improving the preparation efficiency of hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a hydrogen peroxide synthesis device in a preferred embodiment of the present invention;

[0027] Figure 2 The stability test data in the preferred embodiment of the present invention;

[0028] Figure 3 Use different types of carbon paper at 100~1000mA / cm 2 Faradaic efficiency of hydrogen peroxide preparation at different current densities. DETAILED DESCRIPTION

[0029] The present invention provides a hydrogen peroxide synthesis device and a hydrogen peroxide preparation method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] The embodiment of the present invention provides a hydrogen peroxide synthesis device, such as Figure 1 As shown, the device includes, from left to right: an anode tank, an electrolyte inlet is provided on one side of the anode tank, and an electrolyte outlet is provided on the other side of the anode tank; an anode electrode, the anode electrode is a titanium felt attached with iridium dioxide; an anion exchange membrane; a cathode tank, an electrolyte inlet is provided on one side of the cathode tank, a product outlet is provided on the other side of the cathode tank, a reference electrode is provided at the top of the cathode tank, and the reference electrode is a saturated silver chloride electrode; the cathode electrode is a GDL340 model commercial carbon paper; an air inlet is provided on one side of the gas chamber, and an air outlet is provided on the other side of the gas chamber.

[0031] The side of the carbon paper coated with a hydrophobic layer is close to the electrolyte, and the other side is close to the gas chamber; the working area of ​​the cathode electrode is 1*1cm 2 ; Use heat-resistant tape to stick the anode electrode to the polytetrafluoroethylene spacer. The polytetrafluoroethylene spacer serves as a support carrier between the units and prevents water leakage.

[0032] The embodiment of the present invention uses commercial carbon paper as a gas diffusion electrode without any supported catalyst, and directly electrocatalytically reduces oxygen to prepare hydrogen peroxide. Commercial carbon paper contains carbon black material, which has abundant oxygen-containing groups, which are active sites for oxygen reduction and have high efficiency in hydrogen peroxide electrosynthesis activity. At the same time, the surface of the carbon paper is not covered with a catalyst layer, and is rich in microporous and mesoporous channels, which is conducive to the diffusion of oxygen.

[0033] In some embodiments, different types of carbon papers can be used to produce hydrogen peroxide by electro-reduction of oxygen in the three-chamber device, and industrial-grade production efficiency can be achieved.

[0034] The embodiment of the present invention provides a method for preparing hydrogen peroxide using the above-mentioned synthesis device, and the method comprises the following steps:

[0035] 40 mL of 1 mol / L potassium hydroxide solution is introduced into the hydrogen peroxide synthesis device through the electrolyte inlets on the cathode tank and the anode tank, and a peristaltic pump is used to maintain the electrolyte flow rate at 15 mL / min for circulation during the reaction;

[0036] Passing O2 into the hydrogen peroxide synthesis device through the gas inlet of the gas chamber at a flow rate of 30 mL / min;

[0037] The cathode electrode and the anode electrode were connected to a power source with a current density of 300 mA / cm 2 . ;

[0038] The water in the electrolyte combines with the oxygen introduced at the cathode electrode to generate OH - and product H2O2, which was discharged through the product outlet on the cathode tank and then collected, with a hydrogen peroxide preparation rate of 3.13 mg cm -2 min -1 . ;

[0039] The OH - The oxygen reaches the anode electrode through the anion exchange membrane and reacts with water in the electrolyte to generate O2, which is discharged through the electrolyte outlet on the anode tank.

[0040] When the current density of the external power source is in the range of 100-1000 mA / cm 2The theoretical oxygen flow rate required for the reaction is less than 7 mL / min, but the embodiment of the present invention changes the amount of oxygen introduced into the back of the carbon paper (30 mL / min), and the oxygen passes through the carbon paper to reach the reaction interface, so that the reaction interface is obviously filled with excess oxygen. In addition to being a reactant for preparing hydrogen peroxide, excess oxygen will cause additional pressure at the catalytic interface, causing the newly generated hydrogen peroxide to be quickly squeezed out of the active site into the electrolyte. It is used to reduce the local excessive hydrogen peroxide concentration, so that the carbon paper can achieve the excellent electrocatalytic performance it has.

[0041] This effect can also be achieved by replacing excess oxygen with a mixture of appropriate amounts of oxygen and other inert gases. However, during the preparation process, at the same current density, the overpotential of the mixed gas is higher than that of pure oxygen, resulting in a waste of resources.

[0042] In some embodiments, the electrolyte is selected from one of potassium hydroxide, potassium sulfate, sodium hydroxide, and sodium sulfate.

[0043] In some embodiments, when the electrolyte is selected from potassium hydroxide or potassium sulfate, the molar concentration of potassium ions in the electrolyte is 1 mol / L. When the electrolyte is selected from sodium hydroxide or sodium sulfate, the molar concentration of sodium ions in the electrolyte is 1 mol / L.

[0044] In the stability test using GDL340 carbon paper, the -2 At a current density of 10000 rpm, the Faraday efficiency is guaranteed to be higher than 80% and the system can run stably for more than 80 hours. Figure 2 ).

[0045] In the constant current experiment, carbon papers from different companies were used at 100-1000 mA / cm 2 The Faradaic efficiency of hydrogen peroxide preparation at current density is above 90% ( Figure 3 ).

[0046] The embodiment of the present invention proposes a hydrogen peroxide synthesis device, which is a three-chamber flow-type electrolyzer for producing hydrogen peroxide. The use of three chambers can realize the introduction of oxygen at the back, passing through the gas diffusion electrode (cathode electrode) to the catalytic surface, and reducing on the catalyst to generate hydrogen peroxide. The three-phase interface formed by the device is uniform and stable, and both gas and liquid can be in uniform contact with the catalyst. When using this device, the amount of oxygen introduced into the back of the carbon paper can be changed, and the oxygen passes through the carbon paper to reach the reaction interface, so that there is excess oxygen on the reaction interface. In addition to being a reactant for preparing hydrogen peroxide, excess oxygen will cause additional pressure at the catalytic interface, causing the newly generated hydrogen peroxide to be quickly squeezed out from the active site into the electrolyte. It is used to reduce the local excessive hydrogen peroxide concentration, so that the carbon paper can achieve the excellent electrocatalytic oxygen reduction performance of hydrogen peroxide.

[0047] The traditional two-chamber electrolyzer reacts the oxygen-water mixture on the surface, and the liquid-gas-solid three-phase interface cannot be well maintained, and there is no extrusion effect of oxygen. The generated hydrogen peroxide easily accumulates on the catalyst surface, further causing side reactions. The device provided by the embodiment of the present invention can stably form a three-phase interface, and at the same time has an oxygen extrusion effect, avoiding the negative impact of local high-concentration hydrogen peroxide, improving the mass transfer of the hydrophobic reaction interface while protecting the highly active sites. Therefore, the use of this device can make carbon paper have excellent electrochemical performance at high current density, even at 1Acm -2 Efficient catalytic preparation of hydrogen peroxide at a current density of .

[0048] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A hydrogen peroxide synthesis device, characterized in that: include: an anode tank, wherein one side of the anode tank is provided with an electrolyte inlet, and the other side of the anode tank is provided with an electrolyte outlet; A cathode tank, wherein one side of the cathode tank is provided with an electrolyte inlet, and the other side of the cathode tank is provided with a product outlet; A gas chamber, wherein one side of the gas chamber is provided with an air inlet, and the other side of the gas chamber is provided with an air outlet; An anode electrode is arranged between the anode tank and the cathode tank, an anion exchange membrane is arranged between the anode electrode and the cathode tank, and a cathode electrode is arranged between the cathode tank and the gas chamber.

2. The hydrogen peroxide synthesis device according to claim 1, characterized in that: The cathode electrode is carbon paper.

3. The hydrogen peroxide synthesis device according to claim 2, characterized in that: The side of the carbon paper coated with the hydrophobic layer faces the electrolyte, and the other side faces the gas chamber.

4. A method for preparing hydrogen peroxide using the hydrogen peroxide synthesis device according to claims 1-3, characterized in that: The method comprises the following steps: The electrolyte is introduced through the electrolyte inlet on the cathode tank and the electrolyte inlet on the anode tank, wherein the electrolyte includes water and electrolyte; introducing oxygen through the gas inlet of the gas chamber; Connecting the cathode electrode and the anode electrode to an external power source; The water in the electrolyte reacts with the introduced oxygen on the cathode electrode to generate hydroxide and hydrogen peroxide, and the hydrogen peroxide is discharged through the product outlet on the cathode tank and then collected.

5. The method according to claim 4, characterized in that The current density of the external power supply is 1-1500 mA / cm 2 The flow rate of the oxygen gas is 1-100 mL / min.

6. The method according to claim 4, characterized in that The electrolyte is selected from one of sulfuric acid, hydrochloric acid, sodium sulfate, potassium sulfate, potassium hydroxide and sodium hydroxide.

7. The method according to claim 6, characterized in that When the electrolyte is potassium hydroxide or sodium hydroxide, the molar concentration of the cations in the electrolyte is 0.01-10 mol / L.

8. The method according to claim 6, characterized in that When the electrolyte is potassium sulfate or sodium sulfate, the molar concentration of sodium ions in the electrolyte is 0.01-10 mol / L.

9. The method according to claim 4, characterized in that The flow rate of the electrolyte is 1-50 mL / min.

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