Electrochemical reactor with alternately assembled negative and positive membrane electrodes and application method thereof

Abstract

The invention discloses an electrochemical reactor with alternately assembled negative and positive membrane electrodes and application of the electrochemical reactor, and belongs to the field of electrochemistry. The reactor consists of a clamp, a bipolar plate, a partition plate, a composite membrane electrode and filler, and is provided with a cathode inlet, a cathode outlet, an anode inlet, an anode outlet, a reactor inlet and a reactor outlet. Wherein the composite membrane electrode is formed by compounding a plurality of layers of materials and is divided into a negative membrane electrode and a positive membrane electrode according to the types of ions generated by catalysis, and the negative membrane electrode and the positive membrane electrode are alternately assembled in the reactor assembly process. The reactor can be applied to an oxygen reduction reaction and an electro-thermal coupling reaction.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalytic chemistry, and particularly relates to an electrochemical reactor with alternately assembled anode and cathode membrane electrodes and its applications in electrocatalytic reactions and "electricity-heat" coupling reactions. Background Art

[0002] Traditional chemical processes are energy-consuming, have complex processes, serious pollution, and low safety. With the development of green and renewable energy, green electricity resources are becoming increasingly abundant. Introducing electricity into traditional chemical production processes and using electrocatalysis to reconstruct chemical processes, thereby reducing energy consumption, simplifying processes, reducing pollution, and improving safety, is an inevitable trend in the development of chemical engineering.

[0003] Common fuel cell reactors and hydrogen production reaction tanks for water electrolysis generally use membrane electrodes based on cation exchange membranes for assembly, thereby realizing the unidirectional transfer of protons from the anode to the cathode. However, both of these reactors are restricted by the type of ion exchange membrane and are only applicable to proton transfer reactions, lacking universality and scalability. With the development of anion exchange membranes and surface hydrophobic processes, anion membrane electrodes and membrane-free electrodes have gradually matured, making it possible for anions or molecules to be transferred in the reactor. However, due to the existing reactor structure and assembly method, effective coupled production cannot be achieved.

[0004] China's annual demand for hydrogen peroxide has exceeded tens of millions of tons, with an output value reaching tens of billions. Currently, most hydrogen peroxide production enterprises still use the traditional anthraquinone process. This process requires a series of operations such as hydrogenation, oxidation, extraction, and purification to produce hydrogen peroxide, while the electrocatalytic process for producing hydrogen peroxide can achieve the direct synthesis process from hydrogen and oxygen to hydrogen peroxide, which can be used immediately after production, has low energy consumption, low risk, and a simple process. Summary of the Invention

[0005] The purpose of the present invention is to provide an electrochemical reactor with alternately assembled anode and cathode membrane electrodes and its application method. The reactor structure in the present invention is simple, has high safety, is convenient to assemble, has strong adaptability, and rich scalability. The applications of the reactor in the present invention are for the preparation of hydrogen peroxide and olefin epoxidation.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] An electrochemical reactor with alternately assembled anode and cathode membrane electrodes, the reactor includes two clamps, one of the clamps is provided with an anode outlet and an anode inlet, and the other clamp is provided with a cathode outlet and a cathode inlet; between the two clamps, there are N + 2 bipolar plates, where N is an integer greater than or equal to 0;

[0008] A composite membrane positive electrode and a composite membrane negative electrode are provided between adjacent bipolar plates, and a separator is provided between the composite membrane positive electrode and the composite membrane negative electrode. A reactor inlet and a reactor outlet are provided on the separator.

[0009] In the technical solution of the present invention, N is an integer from 0 to 100.

[0010] In the technical solution of the present invention, a filler is provided in the middle of the separator. The filler is composed of a solid electrolyte and a powdered catalyst mixed in a certain proportion. The mass ratio of the solid electrolyte in the filler is 0.5 - 100%; the solid electrolyte is a polymer electrolyte and an oxide electrolyte, and the powdered catalyst is a molecular sieve catalyst, a carbon-based catalyst or a noble metal catalyst;

[0011] Preferably: the solid electrolyte is ion exchange resin DOWEX 50W*4, and the powdered catalyst is titanium silicate molecular sieve MACKLIN TS-1.

[0012] In the technical solution of the present invention, both the composite membrane positive electrode and the composite membrane negative electrode are composed of a diffusion layer, a catalytic layer and a transfer layer;

[0013] The diffusion layer is one of a porous titanium plate, carbon paper, carbon cloth, and carbon felt;

[0014] The catalytic layer is an electrocatalyst, and the catalyst is a hydrogen oxidation reaction catalyst, a water oxidation reaction catalyst or an oxygen reduction reaction catalyst;

[0015] The transfer layer is a proton exchange membrane, a polytetrafluoroethylene coating, a surface modification coating of the catalytic layer or an anion exchange membrane, and the effective area of the membrane electrode is 4 - 10000 cm 2 。

[0016] In the technical solution of the present invention, the catalytic layer of the composite membrane negative electrode is an oxygen reduction catalyst prepared by the method described in Example 1 of the content disclosed in CN117431559A.

[0017] In the technical solution of the present invention, the catalytic layer of the composite membrane positive electrode is a hydrogen oxidation reaction catalyst MACKLIN 20% platinum carbon and a water oxidation reaction catalyst Premetek 20% ruthenium carbon;

[0018] In the technical solution of the present invention, the transfer layer is a proton exchange membrane composite and an anion exchange membrane.

[0019] In the technical solution of the present invention, the fixtures are fixed by bolts.

[0020] In the technical solution of the present invention, the normal thickness of the separator is 0.5 - 10 mm.

[0021] A method for performing an oxidation reaction using an electrochemical reactor assembled by alternately arranging the above-mentioned anion and cation membrane electrodes, characterized in that in this method, the anode inlet feed is hydrogen or water, the cathode inlet feed is oxygen, an oxygen reduction reaction occurs at the cathode, the reactor feed is pure water, and hydrogen peroxide is directly synthesized with the protons generated at the anode;

[0022] Or the anode inlet feed is hydrogen or water, the cathode inlet feed is oxygen, an oxygen reduction reaction occurs at the cathode, the reactor feed is a solvent, if the oxide is in the gas phase, it is mixed with oxygen and fed from the cathode inlet, if the oxide is in the liquid phase, it is mixed with the solvent and fed from the reactor inlet, and an oxidation reaction is achieved through "electro-thermal" coupling.

[0023] In the technical solution of the present invention, the fixture is composed of an end plate and bolts, and its function is to fix the core components of the reactor, ensure that each component is directly and tightly fitted to ensure airtightness, and its assembly pressure is 0.5 - 10 MPa.

[0024] In the technical solution of the present invention, both sides of the bipolar plate have fluid flow channels and are composed of conductive materials such as graphite or metal.

[0025] In the technical solution of the present invention, the separator material is one or several of polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UPE), perfluoroalkoxy copolymer (PFA), polypropylene (PP), and polyvinyl chloride (PVC).

[0026] Beneficial effects brought by the technical solution provided by the examples of the present invention:

[0027] (1) The reactor described in the present invention has a simple structure, high safety, convenient assembly, strong adaptability, rich scalability compared with fuel cell reactors and hydrogen production reaction tanks for water electrolysis, can realize the transfer of anions or molecules in the reactor, and then carry out effective coupling reactions, and stably and efficiently produce.

[0028] (2) The application method described in the present invention is simple to operate and has mild conditions, greatly simplifies the anthraquinone process and the olefin epoxidation process, and realizes the one-step production of hydrogen peroxide or olefin epoxides. Description of the Drawings

[0029] Figure 1 It is a disassembled drawing of the reactor (taking 2 layers as an example).

[0030] Figure 2 It is an assembled drawing of the reactor (taking 6 layers as an example).

[0031] Figure 3 It is the 500-hour test result of the reactor outlet product in Example 1.

[0032] Figure 4Detection results of the reactor outlet products for 200 hours in Example 3..

[0033] In the figure: 1 - fixture; 2 - partition board; 3 - bipolar plate; 4 - packing; 5 - composite membrane electrode (anode); 6 - composite membrane electrode (cathode); 7 - anode outlet; 8 - anode inlet; 9 - cathode outlet; 10 - cathode inlet; 11 - reactor inlet; 12 - reactor outlet; 13 - bolt.

[0034] Table 1 shows the detection results of the reactor outlet product concentrations in Example 1, Comparative Example 1, Comparative Example 2, and Example 2.

[0035] Table 2 shows the detection results of indicators such as the H2O2 content, acidity, chromaticity, total organic carbon (TOC), acid radical ions, and metal impurities of the reactor outlet products in Example 1.

[0036] Table 3 shows the detection results of the reactor outlet product yields in Example 3 and Example 4. Specific implementation manners

[0037] The following examples will further illustrate the present invention, but the content of the present invention is not limited thereto at all. The reagents used in the following examples are conventional reagents that can be purchased in the art without special instructions; the methods used are conventional methods in the art without special instructions.

[0038] The reactor described in the present invention is assembled as follows:

[0039] Stack the fixture, bipolar plate, composite membrane electrode, partition board, etc. in sequence as Figure 1 shown, fill the packing into the cavity formed by the partition board and the composite membrane electrode, apply a normal pressure of 2 MPa relative to the fixture to ensure the sealing performance, and fix it with bolts. The specific content is as follows:

[0040] The reactor includes two fixtures, one of which is provided with an anode outlet 7 and an anode inlet 8, and the other is provided with a cathode outlet 9 and a cathode inlet 10; several bipolar plates 3 are provided between the two fixtures; a composite membrane anode electrode 5 and a composite membrane cathode electrode 6 are provided between the adjacent bipolar plates 3, and a partition board 2 is provided between the composite membrane anode electrode 5 and the composite membrane cathode electrode 6, and the partition board 2 is provided with a reactor inlet 11 and a reactor outlet 12.

[0041] The fixtures are fixed with bolts. The normal thickness of the partition board (2) is 5 mm.

[0042] Example 1:

[0043] When used for producing hydrogen peroxide, the effective area of the membrane electrode in the reactor is 900 cm 2, the number of reactor layers is 6 (including 7 bipolar plates 3 and 6 separators 2). The separator 2 is made of PTFE with a thickness of 2 mm. The filler in the separator is 100% solid electrolyte (ion exchange resin DOWEX 50W*4). The composite membrane anode 5 uses carbon paper (SGL 36BB), platinum-carbon catalyst (hydrogen oxidation reaction catalyst MACKLIN 20% platinum-carbon) and proton exchange membrane composite (DuPont N212). The composite membrane cathode 6 uses carbon paper (SGL 36BB), oxygen reduction catalyst (prepared by the method described in Example 1 of CN117431559A), and anion exchange membrane (FuMA-Tech) composite. After assembly, the reactor is cleaned with ultrapure water for 24 hours. The reactor is placed in a clean room. Hydrogen is introduced into the anode, oxygen is introduced into the cathode, and water flow is introduced into the reactor. A voltage of 12 V is applied to the anode and cathode of the reactor, and the products at the reactor outlet are taken for detection.

[0044] Comparative Example 1:

[0045] Only change the effective area of the membrane electrode to 1 cm 2 , the number of bipolar plates is 2, and other processes are the same as in Example 1.

[0046] Comparative Example 2:

[0047] Only change the cathode membrane electrode to use carbon paper and oxygen reduction catalyst (Example 1 of CN117431559A) composite, and other processes are the same as in Example 1.

[0048] Example 2:

[0049] When used for the production of hydrogen peroxide, the effective area of the membrane electrode in the reactor is 100 cm 2 , the number of reactor layers is 4 (including 5 bipolar plates 3 and 4 separators 2). The separator 2 is made of PEEK with a thickness of 2 mm. The filler in the separator is 100% solid electrolyte (ion exchange resin DOWEX 50Wx4). The composite membrane anode 5 uses carbon paper (SGL 36BB), ruthenium-carbon catalyst (water oxidation reaction catalyst Premetek 20% ruthenium-carbon) and proton exchange membrane composite (DuPont N212). The composite membrane cathode 6 uses carbon paper (SGL 36BB), oxygen reduction catalyst (prepared by the method described in Example 1 of CN117431559A), and anion exchange membrane (FuMA-Tech) composite. 0.1 M sulfuric acid solution is introduced into the anode, oxygen is introduced into the cathode, water flow is introduced into the reactor. A voltage of 8 V is applied to the anode and cathode of the reactor, and the products at the reactor outlet are taken for detection.

[0050] Example 3:

[0051] When used for the "electric - heat" coupling to achieve propylene oxidation reaction, the effective area of the membrane electrode in the reactor is 100 cm2 , the reactor has 4 layers (including 5 bipolar plates 3 and 4 separators 2). The separator 2 is made of PEEK with a thickness of 2 mm. The filler in the separator is a solid electrolyte (ion exchange resin DOWEX 50Wx4) and a powder catalyst (titanium silicate molecular sieve MACKLIN TS-1) mixed in proportion (the mass ratio of the resin is 99%). The composite membrane anode 5 uses carbon paper (SGL 36BB), platinum-carbon catalyst (hydrogen oxidation reaction catalyst MACKLIN 20% platinum-carbon) and proton exchange membrane composite (DuPont N212). The composite membrane cathode 6 uses carbon paper (SGL28BC), oxygen reduction catalyst (Example 1 of CN117431559A), and is surface modified with tetraethylammonium hydroxide. Hydrogen is introduced into the anode, a mixture of oxygen and propylene is introduced into the cathode, and methanol is introduced into the reactor. An 8V voltage is applied to the anode and cathode of the reactor, and the products at the outlet of the reactor are taken for detection.

[0052] Example 4:

[0053] When it is used for "electric-heat" coupling to achieve ethylene oxidation reaction, only the mixture of oxygen and propylene is changed to the mixture of oxygen and ethylene, and other processes are the same as in Example 3.

[0054] Figure 1 , Figure 2 Taking a 6-layer reactor as an example to illustrate the reactor structure and assembly method in Example 1, Figure 3 it shows that the reactor in Example 1 has good stability when it is used for producing hydrogen peroxide, Figure 4 it shows that the reactor in Example 3 also has good stability when it is used in the olefin oxidation process. Table 1 shows that the size of different reactors has an obvious influence on the concentration of the outlet products. Table 2 shows that by improving the reactor material and pipeline, the hydrogen peroxide product can meet the UP-4 grade hydrogen peroxide standard (HG / T 5736-2020). Table 3 shows that the reactor can realize the oxidation of various olefins through "electric-heat" coupling reaction.

[0055] Table 1 Detection results of the concentration of the outlet products of the reactors in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 2.

[0056]

[0057] Table 2 Detection results of the indicators such as the content of H2O2, acidity, chromaticity, total organic carbon (TOC), acid radical ions, and metal impurities of the outlet products of the reactor in Example 1.

[0058]

[0059]

[0060]

[0061] Table 3 shows the detection results of the reactor outlet product yields in Example 3 and Example 4.

[0062]

Claims

1. An electrochemical reactor with alternating assembly of anion and cation membrane electrodes, characterized in that, The reactor includes two fixtures, one of which is provided with an anode outlet (7) and an anode inlet (8), and the other is provided with a cathode outlet (9) and a cathode inlet (10); between the two fixtures, there are N + 2 bipolar plates (3), where N is an integer greater than or equal to 0; Between the connected bipolar plates (3), there are a composite membrane anodic electrode (5) and a composite membrane cathodic electrode (6), and between the composite membrane anodic electrode (5) and the composite membrane cathodic electrode (6), there is a separator (2), and the separator (2) is provided with a reactor inlet (11) and a reactor outlet (12).

2. The electrochemical reactor with alternately assembled cathode and anode membrane electrodes according to claim 1, wherein N is an integer from 0 to 100.

3. The electrochemical reactor with alternately assembled anode and cathode membrane electrodes according to claim 1, characterized in that, There is a filler in the middle of the separator (2), and the filler is composed of a solid electrolyte and a powdered catalyst mixed in proportion. The mass ratio of the solid electrolyte in the filler is 0.5 - 100%; the solid electrolyte is a polymer electrolyte and an oxide electrolyte, and the powdered catalyst is a molecular sieve catalyst, a carbon-based catalyst or a noble metal catalyst; Preferably: the solid electrolyte is ion exchange resin DOWEX 50W*4, and the powdered catalyst is titanium silicate molecular sieve MACKLIN TS-1.

4. The electrochemical reactor with alternately assembled anode and cathode membrane electrodes according to claim 1, characterized in that, Both the composite membrane anodic electrode (5) and the composite membrane cathodic electrode (6) are composed of a diffusion layer, a catalytic layer and a transfer layer; The diffusion layer is one of a porous titanium plate, carbon paper, carbon cloth, and carbon felt; The catalytic layer is an electrocatalyst, and the catalyst is a hydrogen oxidation reaction catalyst, a water oxidation reaction catalyst or an oxygen reduction reaction catalyst; The transfer layer is a proton exchange membrane, a polytetrafluoroethylene coating, a surface modification coating of the catalytic layer, or an anion exchange membrane, and the effective area of the membrane electrode is 4-10000 cm 2 .

5. The electrochemical reactor with alternately assembled cathode and anode membrane electrodes according to claim 4, characterized in that, The catalytic layer of the composite membrane cathodic electrode (5) is an oxygen reduction catalyst prepared by the method described in Example 1 of the content disclosed in CN117431559A.

6. The electrochemical reactor with alternately assembled anode and cathode membrane electrodes according to claim 4, characterized in that The catalytic layer of the composite membrane anodic electrode (6) is a hydrogen oxidation reaction catalyst MACKLIN 20% platinum carbon and a water oxidation reaction catalyst Premetek 20% ruthenium carbon.

7. The electrochemical reactor with alternately assembled cathode and anode membrane electrodes according to claim 4, characterized in that The transfer layer is a proton exchange membrane composite (DuPont N212), an anion exchange membrane (FuMA-Tech).

8. The electrochemical reactor with alternately assembled cathode and anode membrane electrodes according to claim 1, characterized in that The fixtures are fixed with bolts.

9. The electrochemical reactor with alternately assembled anode and cathode membrane electrodes according to claim 1, characterized in that The normal thickness of the separator (2) is 0.5 - 10 mm.

10. A method for performing an oxidation reaction using an electrochemical reactor assembled by alternately stacking the cathode and anode membrane electrodes described in claim 1, characterized in that, In this method, the anode inlet feeds hydrogen or water, the cathode inlet feeds oxygen, an oxygen reduction reaction occurs at the cathode, the reactor feeds pure water, and directly synthesizes hydrogen peroxide with the protons generated at the anode; Or the anode inlet feeds hydrogen or water, the cathode inlet feeds oxygen, an oxygen reduction reaction occurs at the cathode, the reactor feeds a solvent, if the oxide is in the gas phase, it is mixed with oxygen and fed from the cathode inlet, if the oxide is in the liquid phase, it is mixed with the solvent and fed from the reactor inlet, and an oxidation reaction is achieved through "electro-thermal" coupling.

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