Method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid

Abstract

The invention discloses a method for efficiently preparing ethylene by electrocatalytic reduction of a carbon dioxide capture liquid, which comprises the following steps: 1, cleaning hydrophobic porous carbon paper, depositing a copper film, oxidizing, washing and spraying a polymer solution to obtain a copper oxide-based catalyst electrode; 2, loading the copper oxide-based catalyst electrode serving as a cathode into an electro-catalysis CO2 capture and conversion integrated platform; and 3, introducing the simulated flue gas into the electrocatalytic CO2 capture and conversion integrated platform to realize high-efficiency preparation of ethylene by electrocatalytic reduction of the carbon dioxide capture liquid. According to the invention, an electro-catalysis CO2 capture and conversion integrated platform is designed, a copper oxide-based catalyst electrode and a CO2 absorber are adopted to capture CO2 in simulated flue gas, and a membrane electrode assembly type electrolytic bath carries out electro-catalysis reaction through catholyte and anolyte; and the continuous electrocatalytic reduction of the carbon dioxide capture liquid for high-efficiency preparation of ethylene can be realized within a relatively long test time.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalytic reduction of carbon dioxide to produce ethylene, and specifically relates to a method for efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid. Background Art

[0002] As global temperatures rise, the issue of carbon emission reduction is becoming increasingly prominent and affects all aspects of human life. In the sustainable development strategy of storing and utilizing carbon dioxide (CO2) to achieve a "negative carbon economy", converting CO2 into high-value-added chemicals or fuels is a very promising way to achieve zero or negative carbon emissions and efficient utilization of CO2. At present, the main methods for CO2 conversion and utilization include catalytic hydrogenation, catalytic reforming, electrocatalytic reduction, photoelectrocatalytic reduction and light-assisted biological reduction. Among them, the electrocatalytic CO2 reduction method has many advantages and has received widespread attention. The electrocatalytic reduction process has high power utilization rate and mild reaction conditions. The product can be adjusted by changing the type of electrode catalyst, such as reduction to synthesis gas, formic acid, methane, ethylene, ethanol, acetic acid, etc. The electricity driving the process can come from renewable clean energy such as solar energy, wind energy, hydropower, geothermal energy, and tides, thereby achieving zero or negative carbon production of chemical products. In addition, the electrocatalytic reactor system has a simple structure, modularity, flexible assembly, and is easy to scale up for industrial applications.

[0003] Among the many reported electrocatalytic products, ethylene (C2H4) is an important raw material for synthesizing other chemical products, with high mass specific energy density and economic added value. Therefore, the electrocatalytic reduction of CO2 to C2H4 has very important research significance and market application value. At present, most CO2 electrocatalytic direct reduction technologies for ethylene production rely heavily on the continuous supply of high-purity CO2 gas raw materials to the electrocatalytic system. However, the acquisition of high-purity CO2 requires high-energy-consuming processes such as carbon capture, thermal reduction, and high-pressure compression, resulting in low overall economic and energy efficiency of the system, and it is impossible to achieve large-scale application under industrial conditions. In the electrocatalytic system, by effectively integrating the capture and conversion process of CO2 and establishing an integrated platform for electrocatalytic CO2 capture and conversion, the source problem of continuous and high-purity CO2 can be fundamentally solved, and at the same time, the alkaline or neutral CO2 capture liquid can be directly electrocatalytically reduced to high-value-added chemicals or fuels. This technology has the characteristics of high economy, low energy consumption, and easy scale-up. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid in view of the deficiencies of the above-mentioned prior art. The method designs an integrated platform for electrocatalytic CO2 capture and conversion, and adopts a copper oxide-based catalyst electrode with a high specific surface area and multiple grain boundary active sites, wherein the CO2 absorber captures CO2 in the simulated flue gas to form a cathode electrolyte, the anode liquid reservoir is used to store the anode electrolyte, and the membrane electrode assembly type electrolyzer performs electrocatalysis through the transported cathode electrolyte and anode electrolyte, thereby realizing continuous electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene, and realizing highly selective ethylene gas preparation at a high current density within a long test time.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid, characterized in that the method comprises the following steps:

[0006] Step 1: clean the hydrophobic porous carbon paper, then deposit a copper film on the surface, then put it into an oxidizing solution for oxidation and washing, and finally spray a polymer solution and dry it to obtain a copper oxide-based catalyst electrode;

[0007] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0008] The electrocatalytic CO2 capture and conversion integrated platform comprises a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, a cathode and an anode separated by a bipolar membrane are installed in the membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, and the cathode and the anode are connected to the negative electrode and the positive electrode of a power supply respectively;

[0009] Step 3: Pass the simulated flue gas into the integrated electrocatalytic CO2 capture and conversion platform loaded with the cathode in step 2, turn on the power supply, adjust the current density, and achieve efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0010] The present invention obtains a copper oxide-based catalyst electrode with high specific surface area and multiple grain boundary active sites by cleaning hydrophobic porous carbon paper, depositing a copper film, and oxidizing and spraying a polymer. The electrode can achieve highly selective ethylene (C2H4) gas preparation at a high current density within a relatively long test time. An integrated electrocatalytic CO2 capture and conversion platform is designed, wherein a CO2 absorber captures CO2 in simulated flue gas to form a cathode electrolyte, an anode liquid reservoir is used to store the anode electrolyte, and a membrane electrode assembly type electrolyzer performs electrocatalysis through the transported cathode electrolyte and anode electrolyte, thereby achieving continuous electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene.

[0011] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the cleaning process in step 1 is ultrasonic cleaning with acetone, isopropanol, ethanol and deionized water in sequence, and then blown dry with nitrogen for standby use. The present invention controls the cleaning process to fully remove impurities on the surface of the hydrophobic porous carbon paper, which facilitates the subsequent deposition of a copper film with uniform thickness.

[0012] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the deposition in step 1 adopts a magnetron sputtering coating device or a thermal evaporation coating device, and the deposition rate of the copper film is The thickness of the copper film is 800nm ​​to 1.2μm. The present invention uses a magnetron sputtering coating apparatus or a thermal evaporation machine and controls the deposition rate of the copper film to deposit a copper film with uniformly distributed particles on the hydrophobic porous carbon paper, and controls the thickness of the copper film so that the hydrophobic porous carbon paper has an optimal copper particle loading amount, thereby improving the efficiency of electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene.

[0013] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the oxidizing liquid in step one is obtained by mixing 2.5M to 3.0M KOH solution and 0.01M to 0.05M (NH4)2S2O8 solution in a volume ratio of 1:1; the temperature of the oxidizing liquid in the oxidation is 60°C to 80°C, the oxidation time is more than 15 minutes, and the rinsing is performed with deionized water. The present invention controls the composition of the oxidizing liquid and the oxidation parameters to stably and uniformly generate CuOx nanosheet structures on hydrophobic porous carbon paper, copper oxide and cuprous oxide without the appearance of CuOx nanostructures of other morphologies, wherein the reaction between KOH and (NH4)2S2O8 forms a liquid-phase oxidant, which can simply and efficiently oxidize Cu to Cu(OH)2 nanostructures under mild reaction conditions, and the corresponding chemical reaction formula is: 2Cu+8KOH (aq) +4(NH4)2S2O 8(aq) →2Cu(OH)2+4K2SO 4(aq) +4NH 3(g) ↑+4H2O (l) Since the formed Cu(OH)2 nanostructure is unstable, the optimal controllable conditions are achieved by controlling the reaction time and the temperature of the oxidizing solution, and finally a stable and uniform CuOx nanosheet structure is formed. The reaction equation is: Cu(OH)2→CuOx+H2O.

[0014] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the polymer solution in step 1 is a Nafion proton exchange polymer solution with a mass fraction of 5%, and the amount of the polymer solution is 10 μL / cm2 ~50μL / cm 2 The present invention optimizes the transmission of cations in the copper oxide-based catalyst electrode during the electrocatalytic process by controlling the composition and dosage of the polymer solution, thereby increasing the cation concentration on the catalyst surface and facilitating the formation of ethylene products.

[0015] The above-mentioned method for efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the CO2 absorber in step 2 is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer adopts a zero-gap method to assemble the bipolar membrane, cathode and anode. The present invention uses a first peristaltic pump to transport the CO2 capture liquid after CO2 is captured in the CO2 absorber to the cathode of the membrane electrode assembly type electrolyzer as the cathode electrolyte, and the cathode electrolyte with a high pH value (about 12.6) after electrolysis is transported back to the CO2 absorber through the first peristaltic pump to re-capture CO2, thereby achieving reuse and reducing costs. The anolyte in the anolyte reservoir is transported to the anode of the membrane electrode assembly type electrolyzer through the second peristaltic pump as the anolyte, and the anolyte after electrolysis is transported back to the anolyte reservoir through the second peristaltic pump. The role of circulating the anolyte is to reduce the consumption of the anolyte and reduce costs. Because a bipolar membrane is used, OH is continuously generated on the anode side during the electrocatalytic process. - , thereby being able to stably maintain the alkaline environment required for the reaction of the anode nickel catalyst for a long time, and the anolyte after circulation can still meet the needs of long-term oxidation reaction; by assembling the bipolar membrane, cathode and anode in a zero-gap manner, the distance between the anode and the cathode is minimized, which can significantly reduce the operating voltage of the entire device. At the same time, the zero-gap membrane electrode structure eliminates the cathode liquid cavity in the traditional liquid flow electrolyzer structure, effectively simplifying the difficulty of assembling the electrolyzer device, which is conducive to commercial scale-up.

[0016] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that a 1M to 3M KOH solution is placed in the CO2 absorber in step 2 as the CO2 capture liquid. The present invention controls the composition and concentration of the CO2 capture liquid to fully absorb the CO2 in the simulated flue gas, and the reaction that occurs is: CO 2(g) +2KOH (aq) →K2CO 3(aq) , K2CO 3(aq) +CO 2(g) +H2O→KHCO 3(aq), so that the CO2 capture liquid after capturing CO2 mainly exists in the form of KHCO3 solution with a low pH value (about 8.4), which is convenient for the subsequent electrocatalytic reduction of the carbon dioxide capture liquid to efficiently produce ethylene.

[0017] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the anode described in step 2 is a nickel foam with a thickness of 200 μm to 300 μm, and the nickel foam is ultrasonically cleaned with a 0.1M to 0.5M dilute H2SO4 solution before use, and a 1M to 3M KOH solution is stored in the anolyte reservoir as an anolyte. The present invention has the advantages of low price, high catalytic efficiency, and stable performance in an alkaline environment by using nickel foam as an anode. Its porous structure can also increase the active area of ​​the electrochemical reaction and promote gas diffusion. At the same time, Ni will generate NiO, Ni(OH)2, NiOOH and other oxides on the surface during the anode reaction, and these oxides will not continue to dissolve, so the entire porous structure can remain stable for a long time, and by controlling the thickness, the nickel foam effectively increases the active sites of the catalytic reaction while maintaining a high porosity; by using a dilute H2SO4 solution to ultrasonically clean, the oxide layer on the surface of the commercial nickel foam in the production, transportation and storage links is effectively removed, and the fresh active sites on the surface of the nickel foam are increased, which is conducive to the catalytic reaction.

[0018] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the simulated flue gas in step 3 is composed of the following components by volume fraction: N2 70% to 76%, O2 8% to 14%, CO2 8% to 15% and the balance H2O. The present invention controls the composition of the simulated flue gas to represent the composition and proportion of the simulated flue gas of most factories, thereby ensuring that the electrocatalytic reduction of carbon dioxide capture liquid to efficiently prepare ethylene is more practical.

[0019] The above-mentioned method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid is characterized in that the current density in step 3 is 100 mA / cm 2 ~300mA / cm 2 The present invention improves the selectivity of products and the yield of ethylene by controlling the current density.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention designs an integrated platform for electrocatalytic CO2 capture and conversion, and adopts a copper oxide-based catalyst electrode with a high specific surface area and multiple grain boundary active sites. The CO2 absorber captures CO2 in simulated flue gas to form a cathode electrolyte, and the anolyte reservoir is used to store the anolyte. The membrane electrode assembly type electrolyzer uses the delivered cathode electrolyte and anolyte to carry out electrocatalysis, thereby realizing continuous electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene, and achieving highly selective ethylene gas preparation at a high current density over a long test time.

[0022] 2. The present invention obtains a copper oxide-based catalyst electrode with a high specific surface area and multiple grain boundary active sites by washing the hydrophobic porous carbon paper, depositing a copper film, oxidizing and spraying a polymer, thereby improving the selectivity of electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene.

[0023] 3. The present invention realizes reuse and reduces costs by re-transporting the cathode electrolyte after electrolysis back to the CO2 absorber through the first peristaltic pump to re-capture CO2. The present invention realizes reuse and reduces costs by re-transporting the anode electrolyte after electrolysis back to the anode liquid storage through the second peristaltic pump to reduce the consumption of the anode liquid and reduce costs.

[0024] 4. The present invention adopts a zero-gap method to assemble the bipolar membrane, cathode and anode, thereby minimizing the distance between the anode and the cathode, which can significantly reduce the operating voltage of the entire device. At the same time, the zero-gap membrane electrode structure eliminates the cathode liquid cavity in the traditional liquid flow electrolyzer structure, effectively simplifying the difficulty of assembling the electrolyzer device, which is conducive to commercial expansion.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the preparation of the copper oxide-based catalyst electrode in the present invention.

[0027] Figure 2 It is a schematic diagram of the structure of the integrated platform for electrocatalytic CO2 capture and conversion in the present invention.

[0028] Figure 3 It is a chemical reaction in the process of efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid in the present invention.

[0029] Figure 4 This is a distribution diagram of reduction products in the process of efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid in Examples 1 to 5 of the present invention.

[0030] Figure 5This is a distribution diagram of the selectivity of C2 products and C1 products in the process of efficiently producing ethylene from carbon dioxide capture liquid by electrocatalytic reduction in Examples 1 to 5 of the present invention.

[0031] Figure 6 This is a stability test diagram of the process of efficiently producing ethylene by electrocatalytic reduction of carbon dioxide capture liquid in Example 5 of the present invention.

[0032] Description of reference numerals:

[0033] 1—CO2 absorber; 2—CO2 capture liquid; 3—bipolar membrane;

[0034] 4—cathode; 5—anode; 6—anolyte reservoir;

[0035] 7—anolyte; 8—first peristaltic pump; 9—second peristaltic pump. DETAILED DESCRIPTION

[0036] Figure 1 is a flow chart of the preparation of the copper oxide-based catalyst electrode in the present invention, from Figure 1 It can be seen that the present invention deposits a copper film on the surface of the hydrophobic porous carbon paper to obtain a hydrophobic porous carbon paper with a copper film, namely, a copper film / hydrophobic porous carbon paper, which is then placed in an oxidizing solution for oxidation, and finally a polymer solution is sprayed to obtain a copper oxide-based catalyst electrode.

[0037] Figure 2 is a schematic diagram of the structure of the integrated platform for electrocatalytic CO2 capture and conversion in the present invention. Figure 2 It can be seen that the electrocatalytic CO2 capture and conversion integrated platform of the present invention includes a CO2 absorber 1, CO2 capture liquid 2 is placed in the CO2 absorber 1, the CO2 absorber 1 is connected to a "zero gap" electrode assembly-membrane electrode assembly (MEA) type electrolyzer, that is, a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode 4 and an anode 5 separated by a bipolar membrane 3 (BPM), the membrane electrode assembly type electrolyzer is connected to an anode liquid reservoir 6, and an anode electrolyte 7 is placed in the anode liquid reservoir 6. The CO2 absorber 1 is connected to the cathode 4 of the membrane electrode assembly type electrolyzer through a first peristaltic pump 8. The electrocatalytic CO2 capture and conversion integrated platform uses KOH solution as the CO2 capture liquid 2 in the CO2 absorber 1, and captures and absorbs the simulated flue gas in the CO2 absorber 1. The reaction that occurs is: CO 2(g) +2KOH (aq) →K2CO 3(aq) and K2CO 3(aq) +CO 2(g) +H2O→KHCO 3(aq)The CO2 capture liquid 2 after CO2 capture mainly exists in the form of a low pH KHCO3 (pH about 8.4) solution, and then the CO2 capture liquid 2 is directly pumped into the membrane electrode assembly type electrolyzer through the first peristaltic pump 8, as the cathode electrolyte and the only carbon source for the electrocatalytic CO2 reduction reaction, and reacts with the protons (H + ) to carry out the subsequent electrocatalytic reaction to produce ethylene gas. In the process of electrocatalytic reduction of CO2 to produce C2H4, OH is continuously produced at the cathode 4. - , the newly generated OH - The CO2 that does not participate in the electrochemical reaction can be absorbed to form a high-pH KOH and K2CO3 mixed solution (pH is about 12.6), and the mixed solution is recycled into the original CO2 absorber 1 through the first peristaltic pump 8 as a regenerated capture liquid to continue absorbing the simulated flue gas newly introduced into the system. Therefore, the platform can achieve uninterrupted continuous CO2 capture and conversion, and the anolyte reservoir 6 is connected to the anode 5 of the membrane electrode assembly type electrolyzer through the second peristaltic pump 9, and KOH solution is used as the anolyte 7. Under the catalytic action of the anode 5, the KOH solution OH - The oxygen produced is continuously consumed to generate oxygen, which flows out of the membrane electrode assembly type electrolyzer along with the KOH solution after the reaction and circulates back to the anode liquid storage 6. The oxygen that flows out is released into the environment or is recovered by adding a gas / liquid separation device later.

[0038] Figure 3 It is the chemical reaction in the process of electrocatalytic reduction of carbon dioxide capture liquid to efficiently produce ethylene in the present invention. Figure 3 The chemical reactions occurring during the electrocatalytic conversion of CO2 capture liquid are listed, wherein a bipolar membrane 3 (BPM) (produced by Fuel CellStore, model number: Fumasep FBM) is used as an ion exchange membrane to separate the cathode 4 and the anode 5. The present invention uses an inverted BPM assembly method, that is, the cation transport layer in the BPM faces the cathode 4, while the anion transport layer faces the anode 5. During the electrolysis process, water molecules in the solution are catalytically decomposed into protons (H + ) and hydroxide (OH - ), see formula ① in the figure, OH - Under the action of the electric field, the Ni catalyst surface that migrates to the anode 5 undergoes oxygen evolution reaction (OER), as shown in equation ② in the figure. At the same time, H +Under the action of the electric field, it migrates to the cathode liquid to react with the CO2 capture liquid, and CO2 reaction gas is generated and released in situ, as shown in formula ③ in the figure. A large number of CO2 bubbles migrate to the surface of the CuOx-based nanosheet catalyst of the cathode 4 under the action of the flow field, and CO2 electrocatalytic reduction reaction occurs to produce C2H4 gas, as shown in formula ④ in the figure, as well as other gases such as H2 or alcohol liquid products, which flow out of the electrolyzer system through the electrolyte flow field and are stored after detection, separation, collection and storage. The newly generated high pH KOH and K2CO3 mixed liquid in the CO2 electrocatalytic reduction project is circulated back to the CO2 absorber through an external peristaltic pump for subsequent CO2 capture, as shown in formula ⑤ in the figure.

[0039] Example 1

[0040] This embodiment includes the following steps:

[0041] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.67 M KOH solution and 0.03 M ammonium persulfate solution in a volume ratio of 1:1 at 60 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 30 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0042] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0043] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 2M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 300 μm, the nickel foam is ultrasonically cleaned with a 0.1M H2SO4 solution before use, and a 1M KOH solution is stored in the anolyte reservoir;

[0044] Step 3: Set the volume fraction of the simulated flue gas to 76% N2, 8% O2, 14% CO2 and the balance H2O. Load the cathode into the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 100 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0045] Example 2

[0046] This embodiment includes the following steps:

[0047] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.67 M KOH solution and 0.03 M ammonium persulfate solution in a volume ratio of 1:1 at 60 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 30 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0048] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0049] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 2M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 300 μm, the nickel foam is ultrasonically cleaned with a 0.1M H2SO4 solution before use, and a 1M KOH solution is stored in the anolyte reservoir;

[0050] Step 3: Set the volume fraction of the simulated flue gas to 76% N2, 8% O2, 14% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 150 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0051] Example 3

[0052] This embodiment includes the following steps:

[0053] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.67 M KOH solution and 0.03 M ammonium persulfate solution in a volume ratio of 1:1 at 60 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 30 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0054] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0055] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 2M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 300 μm, the nickel foam is ultrasonically cleaned with a 0.1M H2SO4 solution before use, and a 1M KOH solution is stored in the anolyte reservoir;

[0056] Step 3: Set the volume fraction of the simulated flue gas to 76% N2, 8% O2, 14% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 200 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0057] Example 4

[0058] This embodiment includes the following steps:

[0059] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.67 M KOH solution and 0.03 M ammonium persulfate solution in a volume ratio of 1:1 at 60 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 30 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0060] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0061] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 2M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 300 μm, the nickel foam is ultrasonically cleaned with a 0.1M H2SO4 solution before use, and a 1M KOH solution is stored in the anolyte reservoir;

[0062] Step 3: Set the volume fraction of the simulated flue gas to 76% N2, 8% O2, 14% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 250 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0063] Example 5

[0064] This embodiment includes the following steps:

[0065] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.67 M KOH solution and 0.03 M ammonium persulfate solution in a volume ratio of 1:1 at 60 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 30 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0066] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0067] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 2M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 300 μm, the nickel foam is ultrasonically cleaned with a 0.1M H2SO4 solution before use, and a 1M KOH solution is stored in the anolyte reservoir;

[0068] Step 3: Set the volume fraction of the simulated flue gas to 76% N2, 8% O2, 14% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 300 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0069] The reduction products of the electrocatalytic reduction of carbon dioxide capture liquid in the process of efficiently producing ethylene in Examples 1 to 5 were tested. The results are as follows: Figure 4 , Figure 4 The FE% on the vertical axis refers to the Faraday efficiency of the product generated by the electrocatalytic reaction, which is used to indicate the selectivity of the electrocatalytic reaction to generate a certain product. Figure 4 It can be seen that the copper oxide-based catalyst electrodes of Examples 1 to 5 can effectively convert the CO2 capture solution into multi-carbon products, such as ethylene and ethanol. At the same time, some one-carbon products, such as carbon monoxide and methane, and hydrogen products generated by the reduction of protons in the solution are also generated. The selectivity of each product, i.e., the Faraday efficiency, increases with the current density from 100 mA / cm 2 Increase to 300mA / cm 2 , will change accordingly. When the current density is 200mA / cm 2 The selectivity of ethylene is the highest.

[0070] The selectivity of C2 product and C1 product in the process of high-efficiency ethylene production by electrocatalytic reduction of carbon dioxide capture liquid in Examples 1 to 5 was tested. The results are as follows: Figure 5 , Figure 5 The FE% on the vertical axis refers to the Faraday efficiency of the product generated by the electrocatalytic reaction, which is used to indicate the selectivity of the electrocatalytic reaction to generate a certain product. Figure 5 It can be seen that the copper oxide-based catalyst electrodes of Examples 1 to 5 can effectively convert the CO2 capture liquid into multi-carbon products (i.e., the detected C2 products), such as ethylene and ethanol, while the C1 products are carbon monoxide and methane. By analyzing the Faraday efficiency of C2 and C1 products under various current density conditions and the ratio of C2 to C1, it can be clearly seen that the C2 and C1 products change with the current density. At the same time, it can also be known that when the current density is 200 mA / cm 2 When Figure 4 The current density at which the selectivity of ethylene reaches the highest value is consistent, which also shows that the main C2 product obtained using the copper oxide-based catalyst electrode is ethylene within the current density range studied.

[0071] The stability test of the high-efficiency ethylene production process of electrocatalytic reduction of carbon dioxide capture liquid in Example 5 was carried out. The results are as follows: Figure 6 , Figure 6 FE on the left ordinate 乙烯 % refers to the Faraday efficiency of ethylene generated by electrocatalytic reaction, which is used to indicate the selectivity of ethylene generated by electrocatalytic reaction. The vertical axis on the right indicates the operating voltage of the membrane electrode assembly type electrolyzer. Figure 6 It can be seen that when 200mA / cm 2 The current density was 2.38 W, and the membrane electrode assembly type electrolyzer operated stably during the test period of 80 hours, in which the operating voltage range was maintained at 3.7±0.2 V. At the same time, the Faraday efficiency of ethylene was maintained at 50% to 52%.

[0072] Example 6

[0073] This embodiment includes the following steps:

[0074] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 2.5 M KOH solution and 0.01 M ammonium persulfate solution in a volume ratio of 1:1 at 70 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 10 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0075] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0076] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 1M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 200 μm, the nickel foam is ultrasonically cleaned with a 0.3M H2SO4 solution before use, and a 2M KOH solution is stored in the anolyte reservoir;

[0077] Step 3: Set the volume fraction of the simulated flue gas to 70% N2, 14% O2, 15% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 200 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0078] Example 7

[0079] This embodiment includes the following steps:

[0080] Step 1: A hydrophobic porous carbon paper with a length × width of 3 cm × 3 cm and model Sigracet 22BB produced by Fuel Cell Store was ultrasonically cleaned with acetone, isopropanol, ethanol and deionized water in sequence, and then dried with nitrogen for later use. After that, a magnetron sputtering coater or a thermal evaporator was used to coat the carbon paper at a deposition rate of A copper film with a thickness of 800 nm to 1.2 μm was prepared on the surface of hydrophobic porous carbon paper, and then oxidized in an oxidizing solution obtained by mixing 3.0 M KOH solution and 0.05 M ammonium persulfate solution in a volume ratio of 1:1 at 80 °C for 15 min. The surface of the copper film gradually turned black, indicating that the surface of the copper film was oxidized and grown into CuOx nanosheets. It was then rinsed with deionized water and finally oxidized with 50 μL / cm 2 Spraying a 5% by mass Nafion proton exchange polymer solution to obtain a copper oxide-based catalyst electrode;

[0081] Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion;

[0082] The electrocatalytic CO2 capture and conversion integrated platform includes a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is installed with a cathode and an anode separated by a bipolar membrane, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, the cathode and the anode are respectively connected to the negative electrode and the positive electrode of the power supply; a 3M KOH solution is placed in the CO2 absorber as a CO2 capture solution; the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer assembles the bipolar membrane, cathode and anode in a zero-gap manner; the anode is a nickel foam with a thickness of 250 μm, the nickel foam is ultrasonically cleaned with a 0.5M H2SO4 solution before use, and a 3M KOH solution is stored in the anolyte reservoir;

[0083] Step 3: Set the volume fraction of the simulated flue gas to 75% N2, 12% O2, 8% CO2 and the balance H2O. Install the cathode in the integrated platform for electrocatalytic CO2 capture and conversion in step 2, turn on the power, and adjust the current density to 200 mA / cm 2 , achieving efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

[0084] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid, characterized in that: The method comprises the following steps: Step 1: clean the hydrophobic porous carbon paper, then deposit a copper film on the surface, then put it into an oxidizing solution for oxidation and washing, and finally spray a polymer solution and dry it to obtain a copper oxide-based catalyst electrode; Step 2: The copper oxide-based catalyst electrode prepared in step 1 is installed as a cathode into the integrated platform for electrocatalytic CO2 capture and conversion; The electrocatalytic CO2 capture and conversion integrated platform comprises a CO2 absorber, the CO2 absorber is connected to a membrane electrode assembly type electrolyzer, a cathode and an anode separated by a bipolar membrane are installed in the membrane electrode assembly type electrolyzer, the membrane electrode assembly type electrolyzer is connected to an anolyte reservoir, and the cathode and the anode are respectively connected to the negative electrode and the positive electrode of a power supply; Step 3: Pass the simulated flue gas into the integrated electrocatalytic CO2 capture and conversion platform loaded with the cathode in step 2, turn on the power supply, adjust the current density, and achieve efficient production of ethylene by electrocatalytic reduction of carbon dioxide capture liquid.

2. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The cleaning process in step 1 is to use acetone, isopropanol, ethanol and deionized water for ultrasonic cleaning in sequence, and then blow dry with nitrogen for later use.

3. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The deposition in step 1 is carried out by a magnetron sputtering coating apparatus or a thermal evaporation coating apparatus, and the deposition rate of the copper film is The copper film has a thickness of 800 nm to 1.2 μm.

4. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The oxidizing solution in step 1 is obtained by mixing 2.5M to 3.0M KOH solution and 0.01M to 0.05M (NH4)2S2O8 solution in a volume ratio of 1:1; the temperature of the oxidizing solution in the oxidation is 60°C to 80°C, the oxidation time is more than 15 minutes, and the rinsing is carried out with deionized water.

5. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The polymer solution in step 1 is a 5% mass fraction Nafion proton exchange polymer solution, and the amount of the polymer solution is 10 μL / cm 2 ~50μL / cm 2 .

6. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: In step 2, the CO2 absorber is connected to the cathode of the membrane electrode assembly type electrolyzer through a first peristaltic pump, and the anolyte reservoir is connected to the anode of the membrane electrode assembly type electrolyzer through a second peristaltic pump; the membrane electrode assembly type electrolyzer uses a zero-gap method to assemble the bipolar membrane, cathode and anode.

7. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: In step 2, a 1M to 3M KOH solution is placed in the CO2 absorber as a CO2 capture liquid.

8. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The anode in step 2 is a nickel foam with a thickness of 200 μm to 300 μm. The nickel foam is ultrasonically cleaned with a 0.1M to 0.5M dilute H2SO4 solution before use. The anode liquid reservoir stores a 1M to 3M KOH solution as an anode electrolyte.

9. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The simulated flue gas in step 3 is composed of the following components in volume fractions: N2 70% to 76%, O2 8% to 14%, CO2 8% to 15% and the remainder H2O.

10. The method for efficiently preparing ethylene by electrocatalytic reduction of carbon dioxide capture liquid according to claim 1, characterized in that: The current density in step 3 is 100 mA / cm 2 ~300mA / cm 2 .

Images