Flow cell reaction system based on tubular permeable diffusion electrodes, and operation method

Abstract

The present invention relates to a flow cell reaction system based on tubular permeable diffusion electrodes, and an operation method. The system comprises a flow cell reactor and a gas-liquid separation device; the flow cell reactor comprises a cathode chamber and an anode chamber which are separated by a proton exchange membrane; the cathode chamber is internally provided with multi-channel tubular permeable diffusion electrodes which are arranged in a linear or array mode and have a plurality of gas guide channels, each tube wall is of a porous layered wall structure, the outlet end of each multi-channel tubular permeable diffusion electrode is blocked, a reaction gas is guided into the inlet end of each multi-channel tubular permeable diffusion electrode through a gas guide tube assembly, and the gas is forced to diffuse to the surface of each electrode through the porous layered wall under the action of a pressure so as to form a gas-liquid-solid three-phase reaction interface; the gas-liquid separation device is used for carrying out gas-liquid separation on a gas-liquid mixture output from the cathode chamber, the separated gas and liquid are respectively returned into the multi-channel tubular permeable diffusion electrodes and the cathode chamber to form a loop, and detection points are provided on the loop to carry out product recovery on the basis of detection conditions. The present invention achieves efficient and stable operation of electro-reduction reaction systems, and is suitable for large-scale industrial application.

Description

Flow cell reaction system based on tubular diffusion electrode and operation method Technical Field

[0001] The present invention relates to the field of electrocatalysis technology, and in particular to a flow cell reaction system based on a tubular diffuse electrode and an operating method thereof. Background Art

[0002] Traditional flow electrolysis cells, as energy conversion devices, primarily convert cathode reactant gases (CO, CO2, N2, nitrogen oxides, CO2 and N2, or CO2 and nitrogen oxides) into high-value-added products through electrochemical processes. Although significant progress has been made in electroreduction, the low solubility of the reactant gases and the long mass transfer distance hinder gas transport, resulting in very limited current densities of only tens of mA / cm 2 , which is far below the requirements of industrial applications. One strategy to solve this problem is to coat a highly active catalyst on a microporous layer decorated with superhydrophobic polytetrafluoroethylene and conductive carbon particles to construct a gas diffusion electrode (GDE). GDE is a porous membrane electrode that is integrated with a flow cell or membrane electrode assembly to promote the rapid diffusion of reactant gases to the active sites, thereby enabling the reaction to proceed at an industrial-scale current density (≥300mA / cm 2 ) is operated under the condition of a low pressure, which reduces the mass transfer limitation of the reaction gas. However, in the long-term operation of the traditional flow electrolysis cell system, it can be observed that the GDE is degraded and the binder integrated in the GDE ages and loosens during long-term electrolysis. This problem of the GDE itself seriously affects the efficient and stable operation of the system. In addition, due to the relatively small surface / volume of the GDE in the traditional flow electrolysis cell system, the system can only be used for small-scale laboratory experiments and is not suitable for large-scale applications. In addition, during the reaction process, the traditional flow electrolysis cell also has problems such as a large amount of reaction gas escaping through the gas diffusion layer of the GDE into the electrolyte on the other side, resulting in the loss of reaction gas. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides a flow cell reaction system and operation method based on tubular diffuse electrodes, aiming to achieve efficient conversion, stable operation and large-scale application of the flow electrolytic cell.

[0004] The technical solution adopted in the present invention is as follows:

[0005] The present invention provides a flow cell reaction system based on tubular diffuser electrodes, comprising a flow cell reactor, wherein a cathode chamber and an anode chamber separated by a proton exchange membrane are provided inside the flow cell reactor, wherein the cathode chamber is connected to a reaction gas input pipe, a cathode electrolyte input pipe, and a gas-liquid output pipe, respectively used for inputting reaction gas and cathode electrolyte and outputting gas-liquid products after the reaction, an air guide pipe assembly and a plurality of multi-channel tubular diffuser electrodes are provided in the cathode chamber, an inlet of the air guide pipe assembly is connected to an outlet of the reaction gas input pipe, and a plurality of outlets are provided on the air guide pipe assembly, respectively connected to the inlet ends of the plurality of multi-channel tubular diffuser electrodes, and the outlet ends of the multi-channel tubular diffuser electrodes are sealed; an anolyte input pipe for inputting anolyte is connected to the anode chamber, an anode electrode is provided in the anode chamber, and the anode electrode and the multi-channel tubular diffuser electrodes are respectively connected to two ends of a power supply;

[0006] The multi-channel tubular diffuse electrode is made of a single metal material, which is manufactured by phase conversion and sintering methods. It has multiple channels for gas mass transfer and diffusion, and is closed at one end. The tube wall is a porous layered wall structure. Alternatively, the catalytic active sites on the electrode surface are regulated by surface reconstruction based on the single metal material.

[0007] The invention also includes a gas-liquid separation device for performing gas-liquid separation on the reacted gas-liquid mixture output from the cathode chamber, the gas-liquid separation device being provided with a gas-liquid inlet, a gas outlet, and a liquid outlet, the gas-liquid inlet being connected to the outlet of the gas-liquid output pipe, the gas outlet being connected to the reaction gas input pipe through a first connecting pipe and then to the inlet of the gas guide pipe assembly, and the liquid outlet being connected to the cathode electrolyte input pipe through a second connecting pipe and then to the cathode chamber;

[0008] The first connecting pipe is provided with a first circulation pump, a gas detection point and a first three-way valve in sequence, and the other outlet of the first three-way valve is used to be connected to the gas product collection end;

[0009] The second connecting pipe is provided with a second circulation pump, a liquid detection point and a second three-way valve in sequence, and another outlet of the second three-way valve is used to be connected to the liquid product collection end.

[0010] Further technical solutions are:

[0011] The surface reconstruction includes doping a single metal substrate with carbon nanotubes, introducing ZIF materials, doping with other single metals or doping with other heteroatoms, or modifying the surface of a multi-channel tubular diffuse electrode of a single metal substrate by in-situ electro-etching or in-situ wet chemical method.

[0012] The plurality of multi-channel tubular diffuse electrodes are arranged in a straight line or distributed in an array;

[0013] The air guide pipe assembly includes a main pipe and a plurality of branch pipes connected to the main pipe and arranged in parallel, and the outlet of the air guide pipe assembly is located at the beginning of each branch pipe;

[0014] The air guide tube assembly is a metal part and is connected to the power supply via a wire.

[0015] The first inlet of the reaction gas input pipe is connected to the outlet of the first connecting pipe, and the second inlet of the reaction gas input pipe is connected to an external reaction gas source; the reaction gas input pipe is provided with a first electric valve, a mass flow meter and a gas pressure gauge.

[0016] The inlet of the cathode electrolyte input pipe is connected to the cathode electrolyte storage barrel, and a second electric valve is provided on the cathode electrolyte input pipe.

[0017] The inlet of the anolyte input pipe is connected to the anolyte storage barrel, and the anolyte input pipe is provided with a third electric valve and a liquid pressure gauge.

[0018] The anode chamber is also connected to an exhaust pipe for outputting the gas generated by the reaction in the anode chamber.

[0019] A rotating separation element is provided in the gas-liquid separation device for separating the gas-liquid mixture after the reaction through rotational motion.

[0020] The present invention also provides a method for operating the flow cell reaction system based on the tubular diffuse electrode, comprising:

[0021] Catholyte is input into the cathode chamber through the cathode electrolyte input pipe, anolyte is input into the anode chamber through the anolyte input pipe, external reaction gas is input into a plurality of multi-channel tubular diffuser electrodes through the reaction gas input pipe and the gas guide pipe assembly, the power is turned on, the reaction gas flows into the channels of the multi-channel tubular diffuser electrodes and is evenly diffused to the electrode surface through the porous layered wall to generate an electro-reduction reaction, and the escaping reaction gas, electrolyte and electro-reduction products are discharged into the gas-liquid separation device through the gas-liquid output pipe for gas-liquid separation;

[0022] The gas after gas-liquid separation returns to the multi-channel tubular diffuser electrode through the first connecting pipe, the reaction gas input pipe, and the gas guide pipe assembly to continue to participate in the electro-reduction reaction, forming a closed circulation loop;

[0023] The liquid after gas-liquid separation returns to the cathode chamber through the second connecting pipe and the cathode electrolyte input pipe, forming a closed circulation loop;

[0024] When the product is gas, the concentration of the reaction gas is detected by the gas detection point. When the concentration of the reaction gas is less than a first set value, the first three-way valve is switched to transport the gas in the first connecting pipe to the external gas product collection end, and the flow rate of the external reaction gas is adjusted to maintain the total pressure in the multi-channel tubular diffused electrode unchanged until the concentration of the reaction gas measured at the gas detection point is greater than a second set value. The first three-way valve is switched again to allow the gas in the first connecting pipe to re-enter the multi-channel tubular diffused electrode to participate in the electro-reduction reaction;

[0025] When the product is liquid, the concentration of the liquid product is detected by the liquid detection point. When the concentration of the liquid product is greater than a third set value, the second three-way valve is switched to transport the liquid in the second connecting pipe to the external liquid product collection end, and at the same time, the cathode electrolyte is replenished to the cathode chamber through the cathode electrolyte input pipe until the liquid product concentration measured at the liquid detection point is less than a fourth set value. The second three-way valve is switched again to allow the liquid in the second connecting pipe to re-enter the cathode chamber;

[0026] H generated by electrolysis of the anolyte + Entering the cathode chamber through the proton exchange membrane, it provides sufficient H for the electroreduction reaction in the cathode chamber. + At the same time, the O2 generated in the anode chamber is discharged through the exhaust pipe.

[0027] The reaction gas includes one of CO, CO2, N2, nitrogen oxides, a mixture of CO2 and N2, and a mixture of CO2 and nitrogen oxides;

[0028] By using multi-channel tubular diffused electrodes made of corresponding materials, CO can be directionally converted into methane, methanol, formic acid, ethane, ethylene, ethanol or acetic acid, CO2 can be directionally converted into CO, methane, methanol, formic acid, ethane, ethylene, ethanol or acetic acid, N2 and nitrogen oxides can be directionally converted into ammonia or ammonia water, and a mixture of CO2 and N2, and a mixture of CO2 and nitrogen oxides can be directionally converted into urea.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention achieves efficient conversion, stable operation and large-scale application of the system at industrial-grade current density, and specifically has the following advantages:

[0031] 1. Compared with traditional plate electrodes, the multi-channel tubular diffuse electrode of the present invention has a higher surface area to volume ratio, which facilitates the expansion of a single tubular diffuse electrode into a plurality of well-arranged tubular diffuse electrode arrays, thereby achieving the expansion of the scale of the electroreduction reaction.

[0032] 2. Compared with the traditional plate-type flow cell reaction system, the flow cell reaction system based on tubular diffuse electrodes of the present invention is equipped with a gas-liquid separation device, combined with an automatic control module and corresponding actuators, including an electric valve, a three-way valve, a gas-liquid detection point, a pressure gauge, a mass flow meter, etc., to achieve automatic operation of the system and efficient separation of gas and liquid products. When the enrichment concentration of the product reaches the industrial purification concentration, it can be automatically discharged, thereby improving the degree of system automation and reducing manpower consumption.

[0033] 3. The present invention can achieve the directional preparation of different high-value-added products by electro-reduction of multiple reaction gases by changing the electrode material of the multi-channel tubular diffuse electrode and regulating the catalytic active sites of the electrode material.

[0034] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a schematic diagram of the system structure of an embodiment of the present invention.

[0036] FIG2 is a longitudinal cross-sectional view of the multi-channel tubular diffusion electrode arrangement structure in FIG1.

[0037] FIG3 is a transverse cross-sectional view of the multi-channel tubular diffusion electrode arrangement structure in FIG1 .

[0038] In the figure: 1. Flow cell reactor; 2. Gas-liquid separation device;

[0039] 11. Cathode chamber; 12. Anode chamber; 13. Proton exchange membrane; 14. Power supply;

[0040] 21. Rotating separator; 22. Gas-liquid inlet; 23. Gas outlet; 24. Liquid outlet; 25. First circulation pump; 26. First three-way valve; 27. Gas detection point; 28. Second circulation pump; 29. ​​Second three-way valve; 210. Liquid detection point; 211. First connecting pipe; 212. Second connecting pipe;

[0041] 111. Gas guide tube assembly; 112. Multi-channel tubular diffused electrode; 113. Reaction gas inlet pipe; 114. Catholyte inlet pipe; 115. Gas-liquid outlet pipe; 116. External reaction gas source; 117. First electric valve; 118. Mass flow meter; 119. Gas pressure gauge; 1110. Catholyte storage tank; 1111. Second electric valve; 1121. Channel;

[0042] 121. Anode electrode; 122. Anolyte inlet pipe; 123. Exhaust pipe; 124. Anolyte storage tank; 125. Third electric valve; 126. Liquid pressure gauge. DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0044] Example 1

[0045] Referring to Figure 1, a flow cell reaction system based on a tubular diffuse electrode in this embodiment includes a flow cell reactor 1, which is provided with a cathode chamber 11 and an anode chamber 12 separated by a proton exchange membrane 13. The cathode chamber 11 is connected to a reaction gas input pipe 113, a cathode electrolyte input pipe 114 and a gas-liquid output pipe 115, which are respectively used to input reaction gas, cathode electrolyte and output gas and liquid products after the reaction. A gas guide pipe assembly 111 and a plurality of multi-channel tubular diffuse electrodes 112 are provided in the cathode chamber 11. The inlet of the gas guide pipe assembly 111 is connected to the outlet of the reaction gas input pipe 113. The gas guide pipe assembly 111 is provided with a plurality of outlets, which are respectively connected to the inlet ends of the plurality of multi-channel tubular diffuse electrodes 112. The outlet ends of the multi-channel tubular diffuse electrodes 112 are closed.

[0046] The anode chamber 12 is connected to an anolyte input pipe 122 for inputting an anolyte. An anode electrode 121 (an inert electrode) is provided in the anode chamber 12. The anode electrode 121 and the multi-channel tubular diffuse electrode 112 are respectively connected to both ends of a power supply 14.

[0047] The device further includes a gas-liquid separation device 2 for performing gas-liquid separation on the gas-liquid products after the reaction in the cathode chamber 11. The gas-liquid separation device 2 is provided with a gas-liquid inlet 22, a gas outlet 23, and a liquid outlet 24. The gas-liquid inlet 22 is connected to the outlet of the gas-liquid output pipe 115, the gas outlet 23 is connected to the reaction gas input pipe 113 through a first connecting pipe 211 and then to the inlet of the gas guide pipe assembly 111, and the liquid outlet 24 is connected to the cathode electrolyte input pipe 114 through a second connecting pipe 212 and then to the cathode chamber 11.

[0048] The first connecting pipe 211 is provided with a first circulation pump 25, a gas detection point 27 and a first three-way valve 26 in sequence. The other outlet of the first three-way valve 26 is connected to the gas product collection end.

[0049] The second connecting pipe 212 is provided with a second circulation pump 28, a liquid detection point 210 and a second three-way valve 29 in sequence. Another outlet of the second three-way valve 29 is used to be connected to the liquid product collection end.

[0050] Specifically, the first inlet of the reaction gas input pipe 113 is connected to the outlet of the first connecting pipe 211, and the second inlet of the reaction gas input pipe 113 is connected to the external reaction gas source 116; the reaction gas input pipe 113 is provided with a first electric valve 117, a mass flow meter 118 and a gas pressure gauge 119.

[0051] Specifically, the inlet of the cathode electrolyte input pipe 114 is connected to the cathode electrolyte storage tank 1110 , and a second electric valve 1111 is provided on the cathode electrolyte input pipe 114 .

[0052] Specifically, the inlet of the anolyte input pipe 122 is connected to the anolyte storage tank 124 , and the anolyte input pipe 122 is provided with a third electric valve 125 and a liquid pressure gauge 126 .

[0053] Specifically, the anode chamber 12 is further connected to an exhaust pipe 123 for outputting the gas generated by the reaction in the anode chamber 12 .

[0054] Specifically, a rotating separation element 21 is provided in the gas-liquid separation device 2 for separating the gas-liquid mixture after the reaction through rotational motion.

[0055] 2 and 3 , a plurality of multi-channel tubular diffuse electrodes 112 are arranged in a straight line or distributed in an array;

[0056] The air duct assembly 111 includes a main pipe and several branch pipes connected to the main pipe and arranged in parallel. The outlet of the air duct assembly 111 is located at the beginning of each branch pipe. The air duct assembly 111 is a metal part and is connected to the power supply 14 through a wire.

[0057] The multi-channel tubular diffuse electrode 112 of this embodiment is manufactured by phase conversion and sintering. The specific manufacturing method includes:

[0058] Silver powder, N-methylpyrrolidone and a binder are mixed in proportion and then ball-milled to prepare a film-forming solution;

[0059] performing vacuum degassing on the membrane liquid;

[0060] The membrane liquid after vacuum degassing is used as the shell liquid, the coagulant is used as the core liquid, and the membrane liquid is squeezed into water through the spinning head of the spinning device to obtain a multi-channel tubular diffused electrode precursor.

[0061] The precursor is first sintered at a high temperature and then reduced in a hydrogen atmosphere to form a silver-based multi-channel tubular diffuse electrode, which can be used to achieve electrocatalytic CO2 reduction and directional conversion into CO;

[0062] The obtained multi-channel tubular diffusion electrode has multiple tubular channels, and the tube wall is a porous layered wall.

[0063] The multi-channel tubular diffusion electrode 112 has multiple (4 in this embodiment) channels 1121. The inlet of the channel 1121 is connected to the outlet of the gas guide tube assembly 111, and the outlet is closed. The wall surface of the multi-channel tubular diffusion electrode is a porous layered wall structure, that is, the tube wall has multi-layer and porous characteristics, which is conducive to gas diffusion.

[0064] During operation, reactant gas is introduced into channels 1121 of multi-channel tubular diffuser electrode 112 through gas guide assembly 111. Since the outlets of channels 1121 are sealed, the reactant gas flows along channels 1121 and diffuses evenly through the porous layered walls onto the electrode surface. The direction of gas flow is indicated by the arrows in Figures 2 and 3. A gas-liquid-solid three-phase reaction interface forms on the surface of multi-channel tubular diffuser electrode 112, where the reactant gas undergoes an electroreduction reaction.

[0065] This embodiment also provides a method for operating the flow cell reaction system based on the tubular diffuser electrode. The multi-channel tubular diffuser electrode 112 used is made of a silver-based material, which can achieve directional conversion of CO2 into CO, including the following process:

[0066] Open the second electric valve 1111, and the cathode electrolyte in the cathode electrolyte storage tank 1110 is fed into the cathode chamber 11 through the cathode electrolyte inlet pipe 114 and fills the cathode chamber 11, so that the multi-channel tubular diffuse electrode 112 is immersed therein;

[0067] The third electric valve 125 is opened, and the anolyte in the anolyte storage tank 124 is input into the anode chamber 12 through the anolyte input pipe 122 and fills the anode chamber 12, so that the anode electrode 121 is immersed therein;

[0068] The first electric valve 117 is opened, allowing the reaction gas CO2 from the external reaction gas source 116 to be input into the plurality of multi-channel tubular diffuser electrodes 112 through the reaction gas input pipe 113 and the gas guide pipe assembly 111. The power supply 14 is turned on, and the reaction gas flows into the channels 1121 of the multi-channel tubular diffuser electrodes 112 and is uniformly diffused to the electrode surface through the porous layered walls to cause an electro-reduction reaction. The escaping reaction gas, electrolyte, and electro-reduction products are discharged into the gas-liquid separation device 2 through the gas-liquid output pipe 115 for gas-liquid separation.

[0069] The gas after gas-liquid separation is returned to the multi-channel tubular diffuser electrode 112 through the first connecting pipe 211, the reaction gas input pipe 113, and the gas guide pipe assembly 111 under the action of the first circulation pump 25 to continue participating in the electro-reduction reaction, forming a closed circulation loop.

[0070] The reaction gas concentration is detected by the gas detection point 27. When the reaction gas CO2 concentration is less than a first set value (set to 5% in this embodiment), the first three-way valve 26 is switched to transport the gas product in the first connecting pipe 211 to the external gas product collection end. At the same time, the gas flow rate of the external reaction gas source 116 is automatically adjusted by the mass flow meter 118 to maintain the total pressure in the multi-channel tubular diffuse electrode 112 unchanged. Until the reaction gas CO2 concentration measured at the gas detection point 27 is greater than a second set value (set to 99% in this embodiment), the first three-way valve 26 is switched again, and the gas in the first connecting pipe 211 is re-entered into the multi-channel tubular diffuse electrode 112 through the reaction gas input pipe 113 by the first circulation pump 25 to participate in the electro-reduction reaction;

[0071] The liquid (electrolyte) after gas-liquid separation is returned to the cathode chamber 11 through the second connecting pipe 212 and the cathode electrolyte input pipe 114 under the action of the second circulation pump 28, forming a closed circulation loop;

[0072] H generated by electrolysis of the anolyte + Entering the cathode chamber 11 through the proton exchange membrane 13, it provides sufficient H for the electroreduction reaction in the cathode chamber 11. + , while the O2 generated in the anode chamber 12 is discharged through the exhaust pipe 123; the third electric valve 125 is automatically adjusted in real time to replenish the anode electrolyte in the anode electrolyte storage barrel 124 into the anode chamber 12.

[0073] Example 2

[0074] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0075] The electrode material of the multi-channel tubular diffusive electrode is a copper-based material. Carbon nanotubes are mixed with the membrane liquid, and the subsequent steps are the same as above, so that the carbon material is used as a conductive support for the copper nanoparticles to achieve surface reconstruction of the multi-channel tubular diffusive electrode on the copper substrate. The electrode after surface reconstruction can catalyze the electroreduction of CO2 into CH4.

[0076] The operating method of this embodiment is the same as that of Example 1, and the reaction gas used is also CO2. The difference is that a copper-based multi-channel tubular diffuse electrode doped with carbon nanotubes is used to electrocatalyze the directional conversion of CO2 into CH4.

[0077] Example 3

[0078] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0079] The electrode material of the multi-channel tubular diffuse electrode is copper-based material. The surface structure of the copper-based material is modified by in-situ electro-etching to obtain valley-shaped catalytic active sites.

[0080] Among them, the in-situ electro-etching method is specifically as follows: placing the obtained copper-based material multi-channel tubular diffused electrode in an acidic electrolyte, applying a voltage of 2V (vs. Ag / AgCl), and performing electrochemical etching to construct a valley-like structure on the surface of the electrode material.

[0081] The operating method of this embodiment is the same as that of Example 1, and the reaction gas used is also CO2. The difference is that a copper-based multi-channel tubular diffuse electrode after in-situ electro-etching is used to electrocatalyze the directional conversion of CO2 into C2H4.

[0082] Example 4

[0083] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0084] The electrode material of the multi-channel tubular diffuse electrode is copper-based material. The surface structure of the copper-based material is modified by in-situ wet chemistry to obtain catalytic active sites with nanocavity structure.

[0085] Among them, the in-situ wet chemical method is specifically as follows: placing the obtained copper-based material multi-channel tubular diffuse electrode in an acidic etching solution and conducting a wet chemical reaction for 60 seconds, thereby inducing the generation of a nanocavity structure on the surface of the electrode material.

[0086] The operating method of this embodiment is the same as that of Example 1, and the reaction gas used is also CO2. The difference is that a copper-based multi-channel tubular diffuse electrode after in-situ wet chemical reaction is used to electrocatalyze the directional conversion of CO2 into C2H6.

[0087] Example 5

[0088] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0089] The electrode material of the multi-channel tubular diffuse electrode is copper-based material. The surface structure of the copper-based material is modified by in-situ electro-etching to obtain valley-shaped catalytic active sites.

[0090] The operating method of this embodiment is the same as that of Example 1, except that the reaction gas used is CO, and the copper-based multi-channel tubular diffuse electrode after in-situ electro-etching can electrocatalyze the directional conversion of CO into CH4.

[0091] Example 6

[0092] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0093] The electrode material of the multi-channel tubular diffuse electrode is copper-based material. The surface structure of the copper-based material is modified by in-situ wet chemistry to obtain catalytic active sites with nanocavity structure.

[0094] The operating method of this embodiment is the same as that of Example 1, except that the reaction gas used is CO, and the copper-based multi-channel tubular diffused electrode after the in-situ wet chemical reaction can electrocatalyze the directional conversion of CO into C2H4.

[0095] Example 7

[0096] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0097] The electrode material of the multi-channel tubular diffused electrode is copper-based material. Graphite carbon nitride is mixed with the membrane liquid. The subsequent steps are the same as

[0098] In Example 1, nitrogen atoms are doped into a copper-based multi-channel tubular diffuse electrode by this method to obtain catalytic active sites doped with nitrogen atoms.

[0099] The operating method of this embodiment is the same as that of Example 1, except that the reaction gas used is CO, and a nitrogen-doped copper-based multi-channel tubular diffuse electrode is used to electrocatalyze the directional conversion of CO into C2H6.

[0100] Example 8

[0101] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 1 is as follows:

[0102] The electrode material of the multi-channel tubular diffuse electrode is a tin-based material. The ZIF material is introduced into the tin-based material by impregnation to modify its surface structure and obtain catalytic active sites with rich porous structure.

[0103] Among them, ZIF material is introduced into the tin-based material to modify its surface structure, specifically including: placing the obtained tin-based material multi-channel tubular diffuse electrode in the impregnation solution of the ZIF material, performing an impregnation reaction, thereby generating a rich porous structure on the surface of the electrode material.

[0104] The operating method of the flow cell reaction system based on the tubular diffuse electrode of this embodiment uses a multi-channel tubular diffuse electrode with a ZIF material introduced to reconstruct the surface of the tin-based material to achieve the directional conversion of NO into ammonia water or ammonia gas, including the following process:

[0105] Open the second electric valve 1111, and the cathode acidic or alkaline electrolyte in the cathode electrolyte storage tank 1110 is input into the cathode chamber 11 through the cathode electrolyte input pipe 114 and fills the cathode chamber 11, so that the multi-channel tubular diffuse electrode 112 is immersed therein;

[0106] The third electric valve 125 is opened, and the anode acidic or alkaline electrolyte in the anode electrolyte storage tank 124 is input into the anode chamber 12 through the anode electrolyte input pipe 122 and fills the anode chamber 12, so that the anode electrode 121 is immersed therein;

[0107] The first electric valve 117 is opened, allowing the reaction gas NO from the external reaction gas source 116 to be input into the plurality of multi-channel tubular diffuser electrodes 112 through the reaction gas input pipe 113 and the gas guide pipe assembly 111. The power supply 14 is turned on, and the reaction gas flows into the channels 1121 of the multi-channel tubular diffuser electrodes 112 and is uniformly diffused to the electrode surface through the porous layered walls to cause an electro-reduction reaction. The escaping reaction gas, electrolyte, and electro-reduction product (ammonia water or ammonia gas) are discharged into the gas-liquid separation device 2 through the gas-liquid output pipe 115 for gas-liquid separation.

[0108] When the cathode and anode electrolytes are acidic, the product of NO electroreduction is mainly a liquid product, ammonia water. Therefore, the liquid separated by the gas-liquid separator 2 is returned to the cathode chamber 11 through the second connecting pipe 212 and the cathode electrolyte input pipe 114 under the action of the second circulation pump 28, forming a closed circulation loop; the concentration of the liquid product is detected by the liquid detection point 210. When the liquid product NH4 + When the concentration is greater than or equal to the third set value (set to 0.414 g / mL in this embodiment), the second three-way valve 29 is switched to transport the liquid in the second connecting pipe 212 to the external liquid product collection end. At the same time, the second electric valve 1111 is automatically adjusted to replenish the cathode electrolyte to the cathode chamber 11 through the cathode electrolyte input pipe 114 until the liquid product NH4 measured at the liquid detection point 210 is + If the concentration is less than the fourth set value (set to 1 μg / mL in this embodiment), the second three-way valve 29 is switched again to allow the liquid in the second connecting pipe 212 to re-enter the cathode chamber 11 through the cathode electrolyte input pipe 114;

[0109] When the cathode and anode electrolytes are alkaline electrolytes, the product of NO electroreduction is mainly ammonia gas. Therefore, the gas separated by the gas-liquid separation device 2 returns to the multi-channel tubular diffuser electrode 112 through the first connecting pipe 211, the reaction gas input pipe 113, and the gas guide pipe assembly 111 to continue participating in the electroreduction reaction, forming a closed loop. When the NO concentration of the reaction gas measured at the gas detection point 27 is less than the first set value (set to 5% in this embodiment), the first three-way valve 26 is cut to collect the gaseous product ammonia. At the same time, the mass flow meter 118 automatically adjusts the flow rate of the external reaction gas source 166 to maintain the total pressure in the multi-channel tubular diffuser electrode 112 unchanged. When the NO concentration of the reaction gas measured at the gas detection point 27 is greater than the second set value (set to 99% in this embodiment), the second three-way valve 26 is cut again, and the gas delivered by the first circulation pump 25 re-enters the multi-channel tubular diffuser electrode 112 to participate in the electroreduction reaction.

[0110] Example 9

[0111] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 8 is as follows:

[0112] The electrode material of the multi-channel tubular diffuse electrode adopts tin-based material, and bimetallic catalytic sites are constructed by introducing copper metal material into the tin-based material.

[0113] The operating method of this embodiment is the same as that of Example 8, except that the reaction gas used is N2, and the difference is that a tin-based multi-channel tubular diffuse electrode with bimetallic catalytic sites is used to electrocatalyze the directionally conversion of N2 into ammonia water or ammonia gas.

[0114] Example 10

[0115] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 8 is as follows:

[0116] The operating method of the flow cell reaction system based on tubular diffuse electrodes of this embodiment uses a multi-channel tubular diffuse electrode made of a copper-based material. By introducing palladium metal material into the copper-based material to construct a bimetallic catalytic site, the directional conversion of CO2 and N2 into urea is achieved, including the following process:

[0117] Open the second electric valve 1111, and the cathode electrolyte in the cathode electrolyte storage tank 1110 is fed into the cathode chamber 11 through the cathode electrolyte inlet pipe 114 and fills the cathode chamber 11, so that the multi-channel tubular diffuse electrode 112 is immersed therein;

[0118] The third electric valve 125 is opened, and the anolyte in the anolyte storage tank 124 is input into the anode chamber 12 through the anolyte input pipe 122 and fills the anode chamber 12, so that the anode electrode 121 is immersed therein;

[0119] The first electric valve 117 is opened, and the reaction gases CO2 and N2 from the external reaction gas source 116 are input into the plurality of multi-channel tubular diffuser electrodes 112 through the reaction gas input pipe 113 and the gas guide pipe assembly 111. The power supply 14 is turned on, and the reaction gases flow into the channels 1121 of the multi-channel tubular diffuser electrodes 112 and are uniformly diffused to the electrode surface through the porous layered walls to cause an electro-reduction reaction. The escaping reaction gases CO2 and N2, the electrolyte, and the electro-reduction product urea are discharged into the gas-liquid separation device 2 through the gas-liquid output pipe 115 for gas-liquid separation.

[0120] The gas after gas-liquid separation is returned to the multi-channel tubular diffuser electrode 112 through the first connecting pipe 211, the reaction gas input pipe 113, and the gas guide pipe assembly 111 under the action of the first circulation pump 25 to continue participating in the electro-reduction reaction, forming a closed circulation loop.

[0121] The liquid after gas-liquid separation is returned to the cathode chamber 11 through the second connecting pipe 212 and the cathode electrolyte input pipe 114 under the action of the second circulation pump 28, forming a closed circulation loop; the liquid product concentration is detected by the liquid detection point 210. When the product urea concentration measured at the liquid detection point 210 is ≥1.05 g / mL, the second three-way valve 29 is switched to transport the liquid in the second connecting pipe 212 to the external liquid product collection end. At the same time, the second electric valve 1111 is automatically adjusted to replenish the cathode electrolyte to the cathode chamber 11 through the cathode electrolyte input pipe 114 until the liquid product urea concentration measured at the liquid detection point 210 is less than 1 μg / mL. The second three-way valve 29 is switched again to allow the liquid in the second connecting pipe 212 to re-enter the cathode chamber 11 through the cathode electrolyte input pipe 114;

[0122] H generated by electrolysis of anolyte 127 + Entering the cathode chamber 11 through the proton exchange membrane 13, it provides sufficient H for the electroreduction reaction in the cathode chamber 11. + At the same time, the O2 generated in the anode chamber 12 is discharged through the gas outlet 123; the third electric valve 125 is automatically adjusted in real time to replenish the anode electrolyte in the anode electrolyte storage barrel 124 into the anode chamber 12.

[0123] Example 11

[0124] The difference between the flow cell reaction system based on tubular diffuse electrodes in this embodiment and that in Example 10 is:

[0125] The multi-channel tubular diffuse electrode uses copper-based materials. The surface structure of the copper-based material is modified by in-situ wet chemistry to obtain catalytic active sites with nanocavity structures.

[0126] The operating method of this embodiment is the same as the operating method of Example 10, except that the reaction gas used is a mixture of CO2 and NO. The difference is that the structure of the surface of the copper-based material is modified by in-situ wet chemistry to obtain catalytic active sites with nanocavity structures, which can realize the directional conversion of CO2 and NO into urea.

[0127] During the operation of the systems of the above embodiments, the electric valves are automatically adjusted in real time so that the electrolyte is replenished into the anode chamber 12 and the cathode chamber 11 in a timely manner.

[0128] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will be able to modify the technical solutions described in the foregoing embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A flow cell reaction system based on a tubular diffuse electrode, characterized in that: The invention comprises a flow cell reactor (1), wherein a cathode chamber (11) and an anode chamber (12) separated by a proton exchange membrane (13) are provided inside the flow cell reactor; the cathode chamber (11) is connected to a reaction gas input pipe (113), a cathode electrolyte input pipe (114) and a gas-liquid output pipe (115), which are respectively used to input reaction gas and cathode electrolyte and output gas and liquid products after reaction; an air guide pipe assembly (111) and a plurality of multi-channel tubular diffuse electrodes (112) are provided inside the cathode chamber (11); an inlet of the air guide pipe assembly (111) is connected to the reaction gas inlet pipe (113), a cathode electrolyte inlet pipe (114) and a gas-liquid output pipe (115), and the gas-liquid output pipe (115) is connected to the cathode chamber (11) to form a gas guide pipe assembly (111). The inlet pipe (113) is connected to the outlet of the inlet pipe (113), the air guide pipe assembly (111) is provided with a plurality of outlets, which are respectively connected to the inlet ends of the plurality of multi-channel tubular diffuse electrodes (112), and the outlet end of the multi-channel tubular diffuse electrode (112) is sealed; the anode chamber (12) is connected to an anode electrolyte inlet pipe (122) for inputting an anode electrolyte, an anode electrode (121) is provided in the anode chamber (12), and the anode electrode (121) and the multi-channel tubular diffuse electrode (112) are respectively connected to two ends of a power source (14); The multi-channel tubular diffuse electrode (112) is made of a single metal material, is manufactured by phase conversion and sintering, has a plurality of channels (1121) for gas mass transfer and diffusion and is closed at one end, and the tube wall is a porous layered wall structure; or the catalytic active sites on the electrode surface are regulated by surface reconstruction based on the single metal material; It also comprises a gas-liquid separation device (2) for performing gas-liquid separation on the gas-liquid mixture after the reaction outputted from the cathode chamber (11); the gas-liquid separation device (2) is provided with a gas-liquid inlet (22), a gas outlet (23) and a liquid outlet (24); the gas-liquid inlet (22) is connected to the outlet of the gas-liquid output pipe (115); the gas outlet (23) is connected to the reaction gas input pipe (113) through a first connecting pipe (211) and then connected to the inlet of the gas guide pipe assembly (111); the liquid outlet (24) is connected to the cathode electrolyte input pipe (114) through a second connecting pipe (212) and then connected to the cathode chamber (11); The first connecting pipe (211) is provided with a first circulation pump (25), a gas detection point (27) and a first three-way valve (26) in sequence, and the other outlet of the first three-way valve (26) is used to be connected to a gas product collection end; The second connecting pipe (212) is provided with a second circulation pump (28), a liquid detection point (210) and a second three-way valve (29) in sequence, and the other outlet of the second three-way valve (29) is used to be connected to a liquid product collection end.

2. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The surface reconstruction includes doping a single metal substrate with carbon nanotubes, introducing ZIF materials, doping with other single metals or doping with other heteroatoms, or surface modification of a multi-channel tubular diffuse electrode (112) of a single metal substrate by in-situ electro-etching or in-situ wet chemical method.

3. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The plurality of multi-channel tubular diffuse electrodes (112) are arranged in a straight line or distributed in an array; The air guide pipe assembly (111) comprises a main pipe and a plurality of branch pipes connected to the main pipe and arranged in parallel, and the outlet of the air guide pipe assembly (111) is located at the beginning of each of the branch pipes; The air guide tube assembly (111) is a metal part and is connected to the power source (14) via a wire.

4. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The first inlet of the reaction gas input pipe (113) is connected to the outlet of the first connecting pipe (211), and the second inlet of the reaction gas input pipe (113) is connected to an external reaction gas source (116); the reaction gas input pipe (113) is provided with a first electric valve (117), a mass flow meter (118) and a gas pressure gauge (119).

5. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The inlet of the cathode electrolyte input pipe (114) is connected to the cathode electrolyte storage tank (1110), and a second electric valve (1111) is provided on the cathode electrolyte input pipe (114).

6. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The inlet of the anolyte input pipe (122) is connected to the anolyte storage tank (124), and a third electric valve (125) and a liquid pressure gauge (126) are provided on the anolyte input pipe (122).

7. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: The anode chamber (12) is also connected to an exhaust pipe (123) for outputting the gas generated by the reaction in the anode chamber (12).

8. The flow cell reaction system based on tubular diffuse electrodes according to claim 1, characterized in that: A rotating separation element (21) is provided in the gas-liquid separation device (2) for separating the gas-liquid mixture after the reaction through a rotating motion.

9. A method for operating a flow cell reaction system based on a tubular diffuse electrode according to any one of claims 1 to 8, characterized in that: include: A cathode electrolyte is input into the cathode chamber (11) through a cathode electrolyte input pipe (114), an anode electrolyte is input into the anode chamber (12) through an anode electrolyte input pipe (122), an external reaction gas is input into a plurality of multi-channel tubular diffuser electrodes (112) through a reaction gas input pipe (113) and a gas guide pipe assembly (111), a power source (14) is turned on, the reaction gas flow enters the channels of the multi-channel tubular diffuser electrodes (112) and is evenly diffused to the electrode surface through the porous layered wall to generate an electro-reduction reaction, and the escaping reaction gas, electrolyte and electro-reduction product are discharged into a gas-liquid separation device (2) through a gas-liquid output pipe (115) for gas-liquid separation; The gas after gas-liquid separation returns to the multi-channel tubular diffuse electrode (112) through the first connecting pipe (211), the reaction gas input pipe (113), and the gas guide pipe assembly (111) to continue to participate in the electric reduction reaction, thereby forming a closed circulation loop; The liquid after gas-liquid separation returns to the cathode chamber (11) through the second connecting pipe (212) and the cathode electrolyte input pipe (114), forming a closed circulation loop; When the product is gas, the concentration of the reaction gas is detected through the gas detection point (27); when the concentration of the reaction gas is less than a first set value, the first three-way valve (26) is switched to transport the gas in the first connecting pipe (211) to the external gas product collection end, and at the same time, the flow rate of the external reaction gas is adjusted to keep the total pressure in the multi-channel tubular diffuse electrode (112) unchanged, until the concentration of the reaction gas measured at the gas detection point (27) is greater than a second set value, and the first three-way valve (26) is switched again to allow the gas in the first connecting pipe (211) to re-enter the multi-channel tubular diffuse electrode (112) to participate in the electric reduction reaction; When the product is liquid, the concentration of the liquid product is detected through the liquid detection point (210). When the concentration of the liquid product is greater than a third set value, the second three-way valve (29) is switched to transport the liquid in the second connecting pipe (212) to the external liquid product collection end, and at the same time, the cathode electrolyte is replenished to the cathode chamber (11) through the cathode electrolyte input pipe (114) until the concentration of the liquid product measured at the liquid detection point (210) is less than a fourth set value, and the second three-way valve (29) is switched again to allow the liquid in the second connecting pipe (212) to re-enter the cathode chamber (11); H generated by electrolysis of the anolyte + The protons enter the cathode chamber (11) through the proton exchange membrane (13) to provide sufficient H for the electroreduction reaction in the cathode chamber (11). + At the same time, the O2 generated in the anode chamber (12) is discharged through the exhaust pipe (123).

10. The operating method according to claim 9, characterized in that: The reaction gas includes one of CO, CO2, N2, nitrogen oxides, a mixture of CO2 and N2, and a mixture of CO2 and nitrogen oxides; By using a multi-channel tubular diffuse electrode (112) made of corresponding materials, CO can be converted into methane, methanol, formic acid, ethane, ethylene, ethanol or acetic acid, CO2 can be converted into CO, methane, methanol, formic acid, ethane, ethylene, ethanol or acetic acid, N2 and nitrogen oxides can be converted into ammonia or ammonia water, and a mixed gas of CO2 and N2, and a mixed gas of CO2 and nitrogen oxides can be converted into urea.

Images