Anion membrane electrode and its preparation method and a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide

Abstract

The present invention belongs to the field of electrochemistry, and specifically relates to an anion membrane electrode and a preparation method thereof, and a device for preparing synthesis gas by gas-phase electrolysis of carbon dioxide. The preparation method is as follows: a porous membrane protective layer is covered on the surface of a vacuum heating plate, and then an anion membrane is covered; then an anion exchange ionomer solution and a cathode catalyst anion exchange ionomer solution are sprayed on the surface in sequence. The present invention can reduce the structural damage to the anion membrane caused by the temperature fluctuation of the metal plate surface during the heating process of the vacuum heating plate by introducing a porous membrane protective layer between the anion membrane and the vacuum heating plate; the anion exchange ionomer layer is introduced between the catalyst layer and the anion membrane to increase the bonding strength between the catalyst layer and the anion membrane and increase the stability of the membrane electrode; during the volatilization process of the heating solvent, the solvent can be promoted to volatilize at low temperature by blowing dry, thereby accelerating the membrane electrode preparation process and improving the stability of the membrane electrode, thereby extending the service life of the device.

Description

Technical Field

[0001] The invention belongs to the field of electrochemistry, and in particular relates to an anion membrane electrode and a preparation method thereof, and a device for preparing synthesis gas by gas-phase electrolysis of carbon dioxide. Background Art

[0002] Carbon dioxide emitted from the combustion of fossil fuels has led to a continuous increase in the concentration of CO2 in the atmosphere, from 280ppm in 1760 to more than 415ppm today, causing a large number of environmental problems. Permanent emission reduction can be achieved through CO2 capture and utilization. The electrochemical reduction method, combined with clean energy such as solar energy and wind energy, can convert carbon dioxide into valuable chemicals such as carbon monoxide. It has the characteristics of mild reaction conditions and high conversion efficiency, and is considered to be one of the methods with potential for large-scale industrial application.

[0003] In the process of electrolyzing CO2 to produce chemicals using a zero-gap electrochemical reactor, membrane electrodes play a decisive role. Since the operating temperature of existing anion membranes is mostly below 50°C, the use of anion membranes to prepare membrane electrodes faces relatively large challenges, such as the problem of unstable heating temperature damaging the anion membrane structure, the slow volatilization of ionomer solvents at low temperatures, and the unstable bonding between the catalyst layer and the anion membrane.

[0004] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention is committed to providing an anion membrane electrode and a preparation method thereof and a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, so as to extend the service life of the anion membrane electrode and improve the operating stability of the carbon dioxide electrolysis system device.

[0006] The present invention provides a method for preparing an anion membrane electrode, the preparation method comprising the following steps:

[0007] (1) covering the surface of the vacuum heating plate with a porous membrane protective layer, and then continuing to cover the surface of the porous membrane protective layer with an anion membrane;

[0008] (2) spraying an anion exchange ionomer solution on the surface of the anion membrane to form an anion exchange ionomer layer to obtain a prefabricated membrane;

[0009] (3) Spraying a cathode catalyst anion exchange ionomer solution on the surface of the prefabricated membrane to form a cathode catalyst layer, thereby obtaining the anion membrane electrode.

[0010] Preferably, the heating temperature of the vacuum heating plate is 35-60° C., and the vacuum degree is 0.01-0.5 MPa;

[0011] And / or, during the spraying process, drying is performed by combining heating with a vacuum heating plate and air drying, wherein the wind speed during the air drying is 0.5 to 10 m / s.

[0012] Preferably, the porous membrane protective layer is one of PTFE membrane, cellulose membrane, carbon cloth, carbon paper, carbon felt, PVDF membrane, and PPS membrane;

[0013] And / or, the thickness of the porous membrane protective layer is 1 to 500 μm.

[0014] Preferably, the anion membrane has a thickness of 20 to 200 μm.

[0015] Preferably, the anion exchange ionomer solution consists of anion exchange ionomer and a solvent;

[0016] And / or, anion exchange ionomers act as ion conductors and binders, playing the role of bonding, dispersion and material transfer in the three-phase interface, and anion exchange ionomers include: quaternary ammonium ionomers (polyphenylene oxide ionomers, polystyrene ionomers, polybiphenyl alkylene ionomers, cycloaliphatic quaternary ammonium ionomers), aromatic ether-free ionomers (polynorbornene ionomers, quaternary ammonium polynorbornene ionomers, polyaryl piperidine ionomers, benzimidazole copolymer ionomers, polyaryl piperidine ionomers, polyphenyl ionomers, polyolefins and polybenzimidazole ionomers), etc.;

[0017] And / or, the solvent is one of DMSO, NMP, isopropanol, and ethanol;

[0018] and / or, the concentration of the anion exchange ionomer solution is 2 to 30 wt.%;

[0019] And / or, the thickness of the anion exchange ionomer layer is 2-100 μm.

[0020] Preferably, the cathode catalyst anion exchange ionomer solution consists of a cathode catalyst and anion exchange ionomer solution;

[0021] and / or, the mass ratio of the anion exchange ionomer to the cathode catalyst is 5:90 to 40:60;

[0022] And / or, the thickness of the cathode catalyst layer is 2 to 100 μm;

[0023] And / or, after spraying, the loading amount of the cathode catalyst is 0.5 to 20 mg / m 2 .

[0024] Among them: the cathode catalyst can be silver and silver alloys, gold and gold alloys, nickel alloys and single atom catalysts, etc.

[0025] Based on the same technical concept, another embodiment of the present invention is to provide an anion membrane electrode obtained by the above preparation method.

[0026] Based on the same technical concept, another solution of the present invention is to provide a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, comprising:

[0027] A double-chamber flow electrolyzer; the double-chamber flow electrolyzer comprises a cathode chamber, an anode chamber and the anion membrane electrode; the anion membrane electrode is arranged between the cathode chamber and the anode chamber, and the anode catalyst is an iridium oxide catalyst.

[0028] A carbon dioxide storage tank; the carbon dioxide storage tank is connected to the cathode chamber and is used to provide carbon dioxide to the cathode chamber; the carbon dioxide in the carbon dioxide storage tank often enters the cathode chamber through a humidifier, and its flow rate is 0.05 to 4 mL / min / cm 2 (Membrane Electrode Area).

[0029] A carbon dioxide absorption separator; the carbon dioxide absorption separator is connected to the cathode chamber and is used to receive the synthesis gas and unreacted carbon dioxide (reusable) produced by the cathode chamber, and the product synthesis gas is used as a product for further synthesis of green chemicals.

[0030] Anode gas-liquid separator; the anode gas-liquid separator is cyclically connected to the anode chamber; the anode gas-liquid separator is used to receive the oxygen and electrolyte generated by the anode chamber; the electrolyte can flow back to the anode chamber through the anode circulation pump.

[0031] Power supply; the power supply is connected to the dual-chamber flow electrolyzer to provide energy required for electrolysis.

[0032] Preferably, the anode chamber comprises an alkaline electrolyte.

[0033] The alkaline electrolyte is one or a combination of two or more of potassium carbonate electrolyte, potassium bicarbonate electrolyte, potassium hydroxide electrolyte, sodium hydroxide electrolyte, sodium carbonate electrolyte, sodium bicarbonate electrolyte, lithium hydroxide electrolyte, and lithium carbonate electrolyte;

[0034] And / or, the concentration of the alkaline electrolyte is 0.05-5 mol / L.

[0035] It should be noted that during the operation of the device, the current density is 5 to 400 mA / cm 2 The electrolysis temperature is 5 to 50° C., and the carbon-hydrogen ratio of the product synthesis gas is CO:H2=95:5 to 40:60.

[0036] The beneficial effects of the present invention are:

[0037] 1. Improved the structural stability of the anion membrane electrode: By introducing a porous membrane protective layer between the anion membrane and the vacuum heating plate, the structural damage to the anion membrane caused by the temperature fluctuation of the metal plate surface during the heating process of the vacuum heating plate can be reduced; the introduction of an anion exchange ionomer layer between the catalyst layer and the anion membrane can increase the bonding strength between the catalyst layer and the anion membrane and increase the stability of the membrane electrode; the introduction of a blow-drying process during the volatilization of the heating solvent can promote the volatilization of the solvent at low temperature, accelerate the membrane electrode preparation process and improve the stability of the membrane electrode; thereby extending the service life of the system device.

[0038] 2. The anode gas-liquid separator and electrolyte storage device are combined into one, which can reduce the device cost and floor space, thereby saving overall production costs; after the introduction of the carbon dioxide absorption separator, carbon dioxide can be recycled and reused, and a high-purity synthesis gas product can be obtained, which can be directly used to synthesize green chemicals; the whole system device improves the comprehensive utilization rate of the electrolyzer, which is of great significance for large-scale industrial production. By effectively utilizing carbon dioxide, the emission of this greenhouse gas is reduced, which helps to alleviate the problem of global warming. This technology is used in combination with clean energy such as solar energy and wind energy to further improve the environmental protection and sustainability of the entire system. By improving the electrolysis efficiency and regulating the carbon-hydrogen ratio in the synthesis gas, not only can the cost be reduced, but also the output and quality of the synthesis gas can be improved to meet the needs of different industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is the SEM image of the AgNi / C catalyst in Example 1.

[0041] Figure 2 This is a SEM image of the surface of the anion membrane electrode in Example 1.

[0042] Figure 3 Schematic diagram of the spraying process of the anion membrane electrode in Example 1.

[0043] Figure 4 It is a schematic diagram of the structure of the anion membrane electrode in Example 1.

[0044] Figure 5 This is a real picture of the anion membrane electrode in Example 1.

[0045] Figure 6It is a schematic diagram of the device for producing synthesis gas by gas-phase electrolysis of carbon dioxide in Example 1.

[0046] Figure 7 This is a graph showing the change in carbon-hydrogen ratio (CO / H2) with CO2 ventilation volume in Example 1.

[0047] Figure 8 This is a graph showing the change in current density with CO2 ventilation rate in Example 1.

[0048] Fig. 9 This is a graph showing the change in current density with electrolyte K2CO3 concentration in Example 1.

[0049] Fig.10 This is a graph showing the change in carbon-hydrogen ratio (CO / H2) with electrolyte K2CO3 concentration in Example 1.

[0050] Fig.11 1 is a graph showing the change of current density with electrolysis voltage in Example 1.

[0051] Fig.12 This is a graph showing the change in carbon-hydrogen ratio (CO / H2) with electrolysis voltage in Example 1.

[0052] Fig.13 This is a graph showing the CO2 conversion rate versus electrolysis voltage in Example 1.

[0053] Fig.14 This is a graph showing the variation of the synthesis gas volume fraction in the product gas with the electrolysis voltage in Example 1.

[0054] Fig.15 This is a graph showing the change in carbon-hydrogen ratio (CO / H2) over reaction time in Example 1.

[0055] Fig.16 This is the gas chromatogram of Example 1 with a carbon-hydrogen ratio (CO / H2) of 2.08.

[0056] Fig.17 This is a real picture of the anion membrane electrode in Example 2.

[0057] Fig.18 This is a real picture of the anion membrane electrode in Example 3.

[0058] Fig.19 This is the gas chromatogram of Example 3 with a carbon-hydrogen ratio (CO / H2) of 5.01.

[0059] Fig. 20 This is a schematic diagram of the spraying process of the anion membrane electrode in Comparative Example 1.

[0060] Fig.21 This is a real shot of the anion membrane electrode in Comparative Example 1.

[0061] Fig. 22This is a schematic diagram of the spraying process of the anion membrane electrode in Comparative Example 2.

[0062] Fig.23 This is a real picture after the anion membrane electrode test in Example 2.

[0063] Fig.24 This is a schematic diagram of the spraying process of the anion membrane electrode in Comparative Example 3.

[0064] Fig.25 This is a schematic diagram of the device for producing synthesis gas by gas-phase electrolysis of carbon dioxide in Comparative Example 4.

[0065] The accompanying drawings in the figure are marked as follows:

[0066] 1-vacuum heating plate; 2-porous membrane protection layer; 3-anion membrane; 4-anion exchange ionomer layer; 5-cathode catalyst layer; 6-sprayer; 7-dryer.

[0067] 8-dual-chamber flow electrolyzer; 81-cathode chamber; 82-anode chamber; 83-anion membrane electrode; 9-carbon dioxide storage tank; 10-humidifier; 11-carbon dioxide absorption separator; 12-anode gas-liquid separator; 13-anode circulation pump; 14-power supply. DETAILED DESCRIPTION

[0068] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0069] Example 1

[0070] This embodiment provides a method for preparing an anion membrane electrode, comprising the following steps:

[0071] (I) Preparation of silver-nickel-carbon catalyst:

[0072] 3.5g of carbon black was dispersed in 2.2L of deionized water, and 45g of silver nitrate, 13g of nickel sulfate and 5g of polyethylene glycol were added, and the mixture was stirred for 3h; 300mL of sodium hypophosphite aqueous solution (2.6mol / L) was added dropwise, and the mixture was stirred for 1h, and then 200mL of sodium hydroxide aqueous solution (5mol / L) was added dropwise, and the mixture was stirred for 2h; the mixture was filtered, vacuum dried at 80℃ for 24h, crushed in a pulverizer, and reduced at 600℃ for 2h in a 10% H2 / Ar atmosphere to obtain a nano-AgNi / C cathode catalyst, as shown in the SEM image. Figure 1 shown.

[0073] (II) Preparation of anionic membrane electrode:

[0074] (1) Weigh 2.0 g of nano-AgNi / C cathode catalyst and disperse it into 20 mL of 5 wt% anion exchange ionomer solution, and ultrasonically disperse it for 1 h to obtain a catalyst anion exchange ionomer solution for standby use;

[0075] (2) Laying a 100 μm thick porous membrane protective layer 2 (carbon cloth) on the vacuum heating plate 1, and then covering it with a 80 μm thick anion membrane 3;

[0076] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 2 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0077] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano-AgNi / C cathode catalyst loading is 4 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ).

[0078] The surface SEM image of the anion membrane electrode is as follows Figure 2 The schematic diagram of the anion membrane electrode spraying process is shown in Figure 3 As shown, the structural schematic diagram of the anion membrane electrode is as follows Figure 4 As shown, the actual picture of the anion membrane electrode is as follows Figure 5 shown.

[0079] refer to Figure 6 This embodiment further provides a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, which comprises:

[0080] A dual-chamber flow electrolyzer 8; the dual-chamber flow electrolyzer 8 comprises a cathode chamber 81, an anode chamber 82 and the anion membrane electrode 83; the anion membrane electrode 83 is arranged between the cathode chamber 81 and the anode chamber 82, and the anode catalyst is an iridium oxide catalyst.

[0081] Carbon dioxide storage tank 9; the carbon dioxide storage tank 9 is connected to the cathode chamber 81 and is used to provide carbon dioxide to the cathode chamber 81. The carbon dioxide in the carbon dioxide storage tank 9 often enters the cathode chamber 81 through the humidifier 10.

[0082] The carbon dioxide absorption separator 11 is connected to the cathode chamber 81 and is used to receive the synthesis gas and unreacted carbon dioxide (reusable) produced by the cathode chamber 81. The product synthesis gas is used as a product for further synthesis of green chemicals.

[0083] Anode gas-liquid separator 12; the anode gas-liquid separator 12 is cyclically connected to the anode chamber 82; the anode gas-liquid separator 12 is used to receive the oxygen and electrolyte produced by the anode chamber 82; the electrolyte can flow back to the anode chamber 82 through the anode circulation pump 13.

[0084] Power supply 14; the power supply 14 is connected to the dual-chamber flow electrolyzer 8 to provide energy required for electrolysis.

[0085] Test method: A dual-chamber flow electrolyzer was used, with humidified carbon dioxide gas flowing through the cathode chamber and potassium carbonate electrolyte flowing through the anode chamber, with an anion membrane electrode in the middle; the cathode side was an AgNi / C catalyst, and the anode side was an iridium oxide catalyst. The electrode working area of ​​the anode and cathode was 200 cm 2 .

[0086] During the test, an anode circulation pump was used to pass potassium carbonate electrolyte into the electrolytic cell at a flow rate of 3000mL / min, with a concentration of 0.1-1.5mol / L. CO2 gas was passed into the cathode at a flow rate of 50-300mL / min, and entered the cathode chamber after passing through a humidifier. The test temperature was 25℃-45℃, and the test electrolysis voltage was 2.6V-3.6V. The oxygen and electrolyte produced on the anode side were separated from the oxygen by a gas-liquid separator, and then circulated back to the anode chamber of the electrolytic cell through an anode circulation pump; the anode gas-liquid separator was also used as an electrolyte storage device. The synthesis gas and unreacted carbon dioxide mixed gas produced on the cathode side were separated by a carbon dioxide absorption separator, and the carbon dioxide was recycled, and the final product gas was mainly synthesis gas.

[0087] Test results: Figure 7 and Figure 8 As shown, the CO2 ventilation volume is between 50 and 300 mL / min, and the current density is stable at 40 mA / cm when the electrolysis voltage is 3.0 V. 2 The carbon-hydrogen ratio (CO / H2) of the product gas is between 2.0 and 2.5. Fig. 9 and Fig.10 As shown in the figure, when the potassium carbonate electrolyte concentration is between 0.1 and 1.5 mol / L and the electrolysis voltage is 3.0 V, the current density increases from 20 mA / cm 2 Increased to 40.5mA / cm 2 , the product gas carbon-hydrogen ratio (CO / H2) is between 1.59 and 2.05. Fig.11 and Fig.12As shown in Figure 2, when the electrolysis voltage is between 2.6V and 3.6V, the current density increases from 18.4mA / cm 2 Increased to 66.0mA / cm 2 , the product gas carbon-hydrogen ratio (CO / H2) is maintained between 1.96-2.16. Fig.13 and Fig.14 As shown, the electrolysis voltage increased from 2.6V to 3.6V, and the CO2 conversion rate increased from 8.5% to 28.4%. After being treated by the carbon dioxide adsorption separator, the volume fraction of the synthetic gas in the product was maintained at about 92%; while in the following comparative example 4, the electrolysis system without the carbon dioxide absorption separator was used, and the volume fraction of the synthetic gas in the product was less than 40%. By comparison, it can be seen that after adding the carbon dioxide absorption separator, the purity of the product synthetic gas is significantly improved, and it can be directly used for downstream Fischer-Tropsch synthesis of green chemicals. Fig.15 As shown in Figure 2, under the electrolysis voltage of 3.0 V, the carbon-hydrogen ratio (CO / H2) of the product gas can be stabilized at about 2.0 for 600 hours. The gas chromatogram with a carbon-hydrogen ratio of 2.08 is shown in Figure 2. Fig.16 shown.

[0088] Example 2

[0089] This embodiment provides a method for preparing an anion membrane electrode, comprising the following steps:

[0090] (I) Preparation of silver-nickel-carbon catalyst:

[0091] Disperse 3.5 g of carbon black in 2.2 L of deionized water, add 45 g of silver nitrate, 13 g of nickel sulfate and 5 g of polyethylene glycol, and stir and mix for 3 h; drop 300 mL of sodium hypophosphite aqueous solution (2.6 mol / L), stir and react for 1 h, then drop 200 mL of sodium hydroxide aqueous solution (5 mol / L), stir and react for 2 h; filter, vacuum dry at 80 ° C for 24 h, crush in a pulverizer, and reduce at 600 ° C for 2 h in a 10% H2 / Ar atmosphere to obtain a nano-AgNi / C cathode catalyst, which is the same as Example 1.

[0092] (II) Preparation of anionic membrane electrode:

[0093] (1) Weigh 2.0 g of nano-AgNi / C cathode catalyst and disperse it into 20 mL of 5 wt% anion exchange ionomer solution, and ultrasonically disperse it for 1 h to obtain a cathode catalyst anion exchange ionomer solution for standby use;

[0094] (2) A 20 μm thick porous membrane protective layer 2 (PTFE membrane) is laid on the vacuum heating plate 1, and then a 100 μm thick anion membrane 3 is covered;

[0095] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 2 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0096] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano AgNi / C cathode catalyst loading is 6 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ), the actual picture is Fig.17 shown.

[0097] This embodiment further provides a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, which differs from Embodiment 1 in that an anion membrane electrode (prepared using this embodiment) is used, and the rest is the same.

[0098] Test method: A dual-chamber flow electrolyzer was used, with humidified carbon dioxide gas flowing through the cathode chamber and potassium bicarbonate electrolyte flowing through the anode chamber, with an anion membrane electrode in the middle; the cathode side was an AgNi / C catalyst, and the anode side was an iridium oxide catalyst. The electrode working area of ​​the anode and cathode was 200 cm 2 .

[0099] During the test, an anode circulation pump was used to pass potassium bicarbonate electrolyte into the electrolytic cell at a flow rate of 3000mL / min with a concentration of 0.5mol / L. CO2 gas was passed into the cathode at a flow rate of 50mL / min, and entered the cathode chamber after passing through a humidifier. The test temperature was 25℃~45℃, and the test electrolysis voltage was 2.6V~3.6V. The oxygen and electrolyte produced on the anode side were separated from the oxygen by a gas-liquid separator, and then circulated back to the anode chamber of the electrolytic cell through an anode circulation pump; the anode gas-liquid separator was also used as an electrolyte storage device. The synthesis gas and unreacted carbon dioxide mixed gas produced on the cathode side were separated by a carbon dioxide absorption separator, and the carbon dioxide was recycled. The final product gas was mainly synthesis gas.

[0100] Test results: CO2 ventilation volume 50mL / min, electrolysis voltage 3.0V, potassium bicarbonate electrolyte concentration 0.5mol / L, current density 50.6mA / cm 2 , the product gas carbon-hydrogen ratio (CO / H2) is maintained at about 2.0, the CO2 conversion rate is about 27.5%, and the synthesis gas volume fraction in the final product is maintained at about 92%. Under the electrolysis voltage of 3.0V, the product gas carbon-hydrogen ratio (CO / H2) can be stabilized between 1.95 and 2.05 for 600 hours.

[0101] Example 3

[0102] This embodiment provides a method for preparing an anion membrane electrode, comprising the following steps:

[0103] (I) Preparation of silver-nickel-carbon catalyst:

[0104] Disperse 3.5 g of carbon black in 2.2 L of deionized water, add 45 g of silver acetate, 5 g of nickel chloride and 5 g of polyethylene glycol, and stir and mix for 3 h; drop 300 mL of sodium hypophosphite aqueous solution (2.6 mol / L), stir and react for 1 h, then drop 200 mL of sodium hydroxide aqueous solution (5 mol / L), stir and react for 2 h; filter, vacuum dry at 80 ° C for 24 h, crush in a grinder, and reduce at 600 ° C for 2 h in a 10% H2 / Ar atmosphere to obtain a nano-AgNi / C cathode catalyst.

[0105] (II) Preparation of anionic membrane electrode:

[0106] (1) Weigh 2.0 g of nano-AgNi / C cathode catalyst and disperse it into 20 mL of 5 wt% anion exchange ionomer solution, and ultrasonically disperse it for 1 h to obtain a cathode catalyst anion exchange ionomer solution for standby use;

[0107] (2) A 100 μm thick porous membrane protective layer 2 (carbon paper) is laid on the vacuum heating plate 1, and then a 20 μm thick anion membrane 3 is covered;

[0108] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 2 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0109] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano AgNi / C cathode catalyst loading is 3 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ), the actual picture is Fig.18 shown.

[0110] This embodiment further provides a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, which differs from Embodiment 1 in that an anion membrane electrode (prepared using this embodiment) is used, and the rest is the same.

[0111] Test method: A dual-chamber flow electrolyzer was used, with humidified carbon dioxide gas flowing through the cathode chamber and potassium bicarbonate electrolyte flowing through the anode chamber, with an anion membrane electrode in the middle; the cathode side was an AgNi / C catalyst, and the anode side was an iridium oxide catalyst. The electrode working area of ​​the anode and cathode was 200 cm 2 .

[0112] During the test, an anode circulation pump was used to pass potassium carbonate electrolyte into the electrolytic cell at a flow rate of 3000mL / min, and the test temperature was 25℃~45℃. The oxygen and electrolyte produced on the anode side were separated from the oxygen by the gas-liquid separator, and then circulated back to the anode chamber of the electrolytic cell through the anode circulation pump; the anode gas-liquid separator was also used as an electrolyte storage device. The synthesis gas and unreacted carbon dioxide mixed gas produced on the cathode side were separated by the carbon dioxide absorption separator, and the carbon dioxide was recycled. The final product gas was mainly synthesis gas.

[0113] Test results: CO2 ventilation volume at 50mL / min, electrolysis voltage at 3.0V, potassium carbonate electrolyte concentration at 0.5mol / L, current density at 32.1mA / cm 2 , the product gas carbon-hydrogen ratio (CO / H2) = 4.51 ~ 5.02; CO2 conversion rate is about 30.2%, and the synthesis gas volume fraction in the product is maintained at about 92%. The gas chromatogram of the product gas carbon-hydrogen ratio (CO / H2) = 5.01 is as follows Fig.19 shown.

[0114] Example 4

[0115] This embodiment provides a method for preparing an anion membrane electrode, comprising the following steps:

[0116] (I) Preparation of silver-nickel-carbon catalyst:

[0117] Disperse 3.5 g of carbon black in 2.2 L of deionized water, add 45 g of silver nitrate, 10 g of nickel sulfate and 5 g of polyethylene glycol, and stir and mix for 3 h; drop 300 mL of sodium hypophosphite aqueous solution (2.6 mol / L), stir and react for 1 h, then drop 200 mL of sodium hydroxide aqueous solution (5 mol / L), stir and react for 2 h; filter, vacuum dry at 80 ° C for 24 h, crush in a grinder, and reduce at 600 ° C for 2 h in a 10% H2 / Ar atmosphere to obtain a nano-AgNi / C cathode catalyst.

[0118] (II) Preparation of anionic membrane electrode:

[0119] (1) Weigh 2.0 g of nano-AgNi / C cathode catalyst and disperse it into 20 mL of 5 wt% anion exchange ionomer solution, and ultrasonically disperse it for 1 h to obtain a cathode catalyst anion exchange ionomer solution for standby use;

[0120] (2) Laying a 100 μm thick porous polymer protective layer on the vacuum heating plate 1, and then covering it with a 20 μm thick anion membrane 3;

[0121] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 3 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0122] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano AgNi / C cathode catalyst loading is 3 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ).

[0123] This embodiment further provides a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, which differs from Embodiment 1 in that an anion membrane electrode (prepared using this embodiment) is used, and the rest is the same.

[0124] Test method: A dual-chamber flow electrolyzer was used, with humidified carbon dioxide gas flowing through the cathode chamber and potassium bicarbonate electrolyte flowing through the anode chamber, with an anion membrane electrode in the middle; the cathode side was an AgNi / C catalyst, and the anode side was an iridium oxide catalyst. The electrode working area of ​​the anode and cathode was 200 cm 2 .

[0125] During the test, an anode circulation pump was used to pass potassium bicarbonate electrolyte into the electrolyzer at a flow rate of 3000mL / min, and the test temperature was 25℃~45℃. The oxygen and electrolyte produced on the anode side were separated from the oxygen by the gas-liquid separator, and then circulated back to the anode chamber of the electrolyzer through the anode circulation pump; the anode gas-liquid separator was also used as an electrolyte storage device. The synthesis gas and unreacted carbon dioxide produced on the cathode side were separated by the carbon dioxide absorption separator, and the carbon dioxide was recycled after absorption. The final product was mainly synthesis gas.

[0126] Test results: CO2 ventilation volume 50mL / min, electrolysis voltage 3.0V, potassium bicarbonate electrolyte concentration 0.5mol / L, current density 34.3mA / cm 2 The carbon-hydrogen ratio of the product gas (CO / H2) is 2.13-2.78; the CO2 conversion rate is about 27.4%, and the volume fraction of synthesis gas in the product is maintained at about 92%.

[0127] Example 5

[0128] This embodiment provides a method for preparing an anion membrane electrode, comprising the following steps:

[0129] (I) The cathode catalyst is a commercially available nano-silver-based catalyst

[0130] (II) Preparation of anionic membrane electrode:

[0131] (1) Weigh 2.0 g of a commercial nanosilver-based catalyst and disperse it into 20 mL of a 5 wt% anion exchange ionomer solution, and perform ultrasonic dispersion for 1 h to obtain a cathode catalyst anion exchange ionomer solution for standby use;

[0132] (2) A 100 μm thick porous membrane protective layer (carbon paper) is laid on the vacuum heating plate 1, and then a 50 μm thick anion membrane 3 is covered;

[0133] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 3 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0134] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano-AgNi / C cathode catalyst loading is 10 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ).

[0135] This embodiment further provides a device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, which differs from Embodiment 1 in that an anion membrane electrode (prepared using this embodiment) is used, and the rest is the same.

[0136] Test method: A dual-chamber flow electrolyzer was used, with humidified carbon dioxide gas flowing through the cathode chamber and potassium bicarbonate electrolyte flowing through the anode chamber, with an anion membrane electrode in the middle; the cathode side was a commercial nanosilver-based catalyst, and the anode side was an iridium oxide catalyst. The electrode working area of ​​the anode and cathode was 200 cm 2 .

[0137] During the test, an anode circulation pump was used to pass potassium bicarbonate electrolyte into the electrolyzer at a flow rate of 3000mL / min, and the test temperature was 25℃~45℃. The oxygen and electrolyte produced on the anode side were separated from the oxygen by the gas-liquid separator, and then circulated back to the anode chamber of the electrolyzer through the anode circulation pump; the anode gas-liquid separator was also used as an electrolyte storage device. The synthesis gas and unreacted carbon dioxide mixed gas produced on the cathode side were separated by the carbon dioxide absorption separator, and the carbon dioxide was recycled. The final product gas was mainly synthesis gas.

[0138] Test results: CO2 ventilation volume 50mL / min, electrolysis voltage 3.0V, potassium bicarbonate electrolyte concentration 0.5mol / L, current density 43.8mA / cm 2 The carbon-hydrogen ratio of the product gas (CO / H2) is 1.84-1.92; the CO2 conversion rate is about 26.3%, and the volume fraction of synthesis gas in the product is maintained at about 92%.

[0139] Comparative Example 1

[0140] (1) Weighing about 2.0 g of AgNi / C cathode catalyst and dispersing it into 20 mL of 5 wt% anion exchange ionomer solution, ultrasonically dispersing it for 1 h, and obtaining a cathode catalyst anion exchange ionomer solution for standby use;

[0141] (2) Lay the 80 μm thick anion membrane 3 flat on a 40°C vacuum heating plate 1 with a vacuum degree of 0.1 MPa;

[0142] (3) Cover the anion membrane 3 with a rectangular hollow template with a hollow area of ​​200 cm 2 , then spraying the anion exchange ionomer solution with a sprayer 6, and maintaining the wind speed of the blow dryer 7 at 2 m / s to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0143] (4) Spray the cathode catalyst anion exchange ionomer solution before the anion exchange ionomer layer is dried and solidified. The nano-AgNi / C cathode catalyst loading is 4 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ).

[0144] Comparative Example 1: Schematic diagram of the spraying process of the anion membrane electrode Fig. 20 When the porous membrane protective layer is not added, the metal heating plate and the anion membrane are attached together, which can easily cause structural damage to the anion membrane. The photo of the anion membrane electrode formed is shown in Fig.21 shown.

[0145] Comparative Example 2

[0146] (1) Weighing about 2.0 g of AgNi / C cathode catalyst and dispersing it into 20 mL of 5 wt% anion exchange ionomer solution, ultrasonically dispersing it for 1 h, and obtaining a cathode catalyst anion exchange ionomer solution for standby use;

[0147] (2) A 100 μm thick porous membrane protective layer 2 (carbon cloth) is laid on a vacuum heating plate 1, and an 80 μm thick anion membrane 3 is laid flat on a vacuum heating plate at 40° C. The vacuum degree is 0.1 MPa;

[0148] (3) Cover it with a rectangular hollow template with a hollow area of ​​200cm 2 , the wind speed of the blow dryer is 2m / s, the cathode catalyst anion exchange ionomer solution is sprayed, and the AgNi / C catalyst loading is 4mg / cm 2 , to form an anion catalyst layer 5, and the final membrane electrode area is 200cm 2 .

[0149] Comparative Example 2: Schematic diagram of the spraying process of the anion membrane electrode Fig. 22 Without spraying the anion exchange ionomer, the cathode catalyst layer 5 is not firmly bonded to the anion membrane 3, and after the catalytic reaction, the cathode catalyst layer 5 is separated from the membrane electrode due to salt precipitation and other reasons. Fig.23 This is a photo of the membrane electrode prepared in comparative example 2 after testing.

[0150] Comparative Example 3

[0151] (1) Weigh 2.0 g of nano-AgNi / C cathode catalyst and disperse it into 20 mL of 5 wt% anion exchange ionomer solution, and ultrasonically disperse it for 1 h to obtain a cathode catalyst anion exchange ionomer solution for standby use;

[0152] (2) Laying a 100 μm thick porous membrane protective layer 2 (carbon cloth) on the vacuum heating plate 1, and then covering it with a 80 μm thick anion membrane 3;

[0153] (3) The heating temperature of the vacuum heating plate 1 is maintained at 40°C and the vacuum degree is 0.1 MPa. A hollow template with a suitable shape is covered on the anion membrane 3, and the hollow area is 200 cm 2 , and then spraying an anion exchange ionomer solution using a sprayer 6 to form an anion exchange ionomer layer 4 to obtain a prefabricated membrane;

[0154] (4) Before the anion exchange ionomer layer 4 is dried and solidified, the cathode catalyst anion exchange ionomer solution is sprayed, and the nano-AgNi / C cathode catalyst loading is 4 mg / cm 2 , to form a cathode catalyst layer 5, and finally obtain an anion membrane electrode (area 200cm 2 ).

[0155] Fig.24 The schematic diagram of the spraying process of the anion membrane electrode of comparative example 3. Without using a blow dryer, the entire membrane electrode preparation time was extended by more than 1 time due to the low temperature resistance of the anion membrane, the heating plate temperature was lower than 45°C, and the solvent evaporated slowly.

[0156] Comparative Example 4

[0157] refer to Fig.25 This comparative example provides a device for preparing synthesis gas by gas-phase electrolysis of carbon dioxide, which does not contain a carbon dioxide absorption separator compared with Example 1. When there is no carbon dioxide absorption separator in the system device, the synthesis gas ratio is 20-35%, and when there is a carbon dioxide absorption separator, the synthesis gas ratio increases to more than 90%, which can be directly used for downstream Fischer-Tropsch synthesis reaction to further prepare green chemicals.

[0158] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing an anion membrane electrode, characterized in that: The preparation method comprises the following steps: (1) covering the surface of the vacuum heating plate with a porous membrane protective layer, and then continuing to cover the surface of the porous membrane protective layer with an anion membrane; (2) spraying an anion exchange ionomer solution on the surface of the anion membrane to form an anion exchange ionomer layer to obtain a prefabricated membrane; (3) Spraying a cathode catalyst anion exchange ionomer solution on the surface of the prefabricated membrane to form a cathode catalyst layer, thereby obtaining the anion membrane electrode.

2. The method for preparing anionic membrane electrode according to claim 1, characterized in that: The heating temperature of the vacuum heating plate is 35-60°C, and the vacuum degree is 0.01-0.5MPa; And / or, during the spraying process, drying is performed by combining heating with a vacuum heating plate and air drying, wherein the wind speed during the air drying is 0.5 to 10 m / s.

3. The method for preparing anionic membrane electrode according to claim 1, characterized in that: The porous membrane protective layer is one of PTFE membrane, cellulose membrane, carbon cloth, carbon paper, carbon felt, PVDF membrane and PPS membrane; And / or, the thickness of the porous membrane protective layer is 1 to 500 μm.

4. The method for preparing anionic membrane electrode according to claim 1, characterized in that: The thickness of the anion membrane is 20 to 200 μm.

5. The method for preparing anionic membrane electrode according to claim 1, characterized in that: The anion exchange ionomer solution consists of anion exchange ionomer and a solvent; And / or, the anion exchange ionomer is one of a quaternary ammonium ionomer and an aromatic ether-free ionomer; And / or, the solvent is one of DMSO, NMP, isopropanol, and ethanol; and / or, the concentration of the anion exchange ionomer solution is 2 to 30 wt.%; And / or, the thickness of the anion exchange ionomer layer is 2-100 μm.

6. The method for preparing anionic membrane electrode according to claim 1, characterized in that: The cathode catalyst anion exchange ionomer solution consists of a cathode catalyst and anion exchange ionomer solution; and / or, the mass ratio of the anion exchange ionomer to the cathode catalyst is 5:90 to 40:60; And / or, the thickness of the cathode catalyst layer is 2 to 100 μm; And / or, after spraying, the loading amount of the cathode catalyst is 0.5 to 20 mg / m 2 .

7. An anion membrane electrode obtained by the preparation method according to any one of claims 1 to 6.

8. A device for producing synthesis gas by gas-phase electrolysis of carbon dioxide, characterized in that: include: A dual-chamber flow electrolyzer; the dual-chamber flow electrolyzer comprises a cathode chamber, an anode chamber and the anion membrane electrode according to claim 7; the anion membrane electrode is arranged between the cathode chamber and the anode chamber; A carbon dioxide storage tank; the carbon dioxide storage tank is connected to the cathode chamber and is used to provide carbon dioxide to the cathode chamber; A carbon dioxide absorption separator; the carbon dioxide absorption separator is connected to the cathode chamber and is used to receive the synthesis gas and unreacted carbon dioxide generated by the cathode chamber; an anode gas-liquid separator; the anode gas-liquid separator is cyclically connected to the anode chamber; the anode gas-liquid separator is used to receive oxygen and electrolyte generated by the anode chamber; Power supply; the power supply is connected to the dual-chamber flow electrolyzer to provide energy required for electrolysis.

9. The device for producing synthesis gas by gas-phase electrolysis of carbon dioxide according to claim 8, characterized in that: The anode chamber includes an alkaline electrolyte.

10. The device for producing synthesis gas by gas-phase electrolysis of carbon dioxide according to claim 9, characterized in that: The alkaline electrolyte is one or a combination of two or more of potassium carbonate electrolyte, potassium bicarbonate electrolyte, potassium hydroxide electrolyte, sodium hydroxide electrolyte, sodium carbonate electrolyte, sodium bicarbonate electrolyte, lithium hydroxide electrolyte, and lithium carbonate electrolyte; And / or, the concentration of the alkaline electrolyte is 0.05-5 mol / L.

Images