Difunctional amino electrolyte as well as preparation method and application thereof
By using bifunctional amine-based electrolyte optimized by the preparation method during the electrochemical reduction of carbon dioxide, the problem of unsatisfactory carbon dioxide capture and utilization in the prior art is solved, and more efficient carbon dioxide capture and electroreduction effects are achieved.
Patent Information
- Application Number
- CN202510124640.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-26
- Publication Date
- 2025-06-06
AI Technical Summary
The existing carbon dioxide capture and utilization effect is not ideal, especially during the electrochemical reduction process, there are problems such as difficulty in inhibiting hydrogen evolution reaction and low Faraday efficiency of the product.
A bifunctional amine electrolyte is adopted, and the preparation method includes adding AM+ to an aqueous amine solution, after sonication and addition of CTAB, heating in a water bath and adjusting the pH to neutral, forming an electrolyte with optimized electrocatalytic properties.
Through this method, the cathode hydrogen evolution reaction is suppressed, the Faraday efficiency of the gas phase product is improved, the capture and utilization efficiency of carbon dioxide is significantly improved, and the CO2 conversion rate and product stability are also improved.
Smart Images
Figure CN120094377A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of industrial process waste gas purification, and specifically relates to a bifunctional amine-based electrolyte with in-situ capture and electrochemical conversion of carbon dioxide, and a preparation method and application thereof. Background Art
[0002] In industrial production processes, carbon dioxide (CO 2 The uncontrolled and large-scale emission of carbon dioxide has caused many serious climate change problems. Carbon capture, utilization and storage (CCUS) technology, as a feasible means, has been widely recognized and applied to reduce atmospheric CO 2 CCUS facilities currently capture more than 45 million tons of CO2 per year. 2 Most of the industrial pilot projects use amine solutions for post-combustion carbon capture, but CO 2 Desorption requires a lot of energy.
[0003] ICCU (Integrated Carbon Capture and Utilization) technology is based on the 2 In-situ catalytic conversion into high value-added chemicals (through thermal catalysis, electrocatalysis, photocatalysis, etc.) to save the need for enrichment, compression, and transportation of CO 2 Using renewable or clean electricity to convert CO 2 Electrocatalytic reduction to high-value products, while achieving energy storage and carbon utilization, is a highly promising approach in integrated carbon capture and utilization (ICCU).
[0004] Domestic and foreign studies have shown that the molecular structure and spatial configuration of bifunctional amine-based electrolytes affect the overpotential, current density and Faraday efficiency of electrocatalytic reactions. Adding ethanolamine (MEA) to aqueous solution will increase the concentration of protonated amine (R1R2NHH+), thereby enhancing the hydrogen evolution reaction and the CO 2 In addition, the presence of R1R2NHH+ reduces the charge density on the electrode surface, thereby reducing the reaction activity. 2 During the process, the structure-activity relationship of amines remains elusive, which poses a challenge to the rational design of bifunctional amine-based electrolytes. Summary of the invention
[0005] The purpose of the present invention is to solve the problem that the existing carbon dioxide capture and utilization effects are not ideal, and to provide a carbon dioxide capture and in-situ electrocatalytic bifunctional amine-based electrolyte and its preparation method and application, so as to effectively inhibit the hydrogen evolution reaction and improve the Faraday efficiency of the product, thereby improving the capture and utilization efficiency of carbon dioxide.
[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a bifunctional amine-based electrolyte, the method comprising:
[0008] Step 1: AM + adding into an amine aqueous solution and mixing evenly to obtain a precursor;
[0009] Step 2: Ultrasonicate the precursor at 50-60°C for 1-2 hours and then cool it to room temperature;
[0010] Step 3: Add CTAB to the precursor solution and heat it to 80°C in a water bath. After cooling it to room temperature, adjust the pH to neutral to reduce the by-products in the electro-reduction stage, thereby obtaining a bifunctional amine-based electrolyte.
[0011] The present invention preliminarily treats the amino solute, AM + Mixing with deionized water and then adding CTAB can reduce the concentration of protonated amines in the electrolyte, thereby inhibiting the cathode hydrogen evolution reaction, increasing the Faraday efficiency of the gas phase product, and achieving optimized carbon dioxide capture and electroreduction effects.
[0012] Furthermore, in step 1, the solute of the amine-based aqueous solution is one of monoethanolamine MEA, diethanolamine DEA, N-methyldiethanolamine MDEA, 3-aminopropylamine 3-AP, 1-aminopropylamine 1-AP, ethylenediamine EDA, 1,3-propylenediamine 13DAP, N-methylaminopropylamine MAPA, and diethylenetriamine DETA. The purity of the above reagents is 98% and they are purchased from Aladdin Reagent Co., Ltd.
[0013] Further, in step 1, the AM + (Metal cation compound) is at least one of sodium chloride, potassium chloride, lithium chloride and cesium chloride.
[0014] Preferably, the AM + It is a combination of potassium chloride and lithium chloride. There is no rigid requirement for the ratio between the two. For example, the ratio of potassium chloride to lithium chloride can be 1:0.1~1. Experiments show that according to the combination, the molecular structure and spatial configuration of the electrolyte can be effectively regulated, thereby promoting the capture and utilization of carbon dioxide.
[0015] Furthermore, in step 1, the mass concentration of the amine-based aqueous solution is 30%; the amine-based solute, AM + The molar concentration ratio of AM and CTAB is 2:2:0.35. + Combination with CTAB can increase the conductivity of amine-based solutions and improve the selectivity of electroreduction products.
[0016] Furthermore, in step three, the method for adjusting the pH is to drop a small amount of hydrochloric acid into the solution until the solution is neutral.
[0017] A bifunctional amine-based electrolyte prepared by the above preparation method.
[0018] An application of the bifunctional amine-based electrolyte prepared by the above preparation method, the application is:
[0019] Step 1: Using bifunctional amine-based electrolytes to absorb carbon dioxide from carbon dioxide-containing flue gas;
[0020] Step 2: Electroreduction at a certain potential, collecting gas phase products and liquid phase products.
[0021] Furthermore, the carbon dioxide content in the carbon dioxide-containing flue gas is 5-30%, and the nitrogen oxide content is less than 500 mg / m 3 , sulfur dioxide <1000mg / m 3 , particulate matter <100mg / m 3 .
[0022] Furthermore, in step 1, during the capture phase, the exhaust gas was continuously blown into the bifunctional amine electrolyte for 1 h at an exhaust gas flow rate of 200 sccm. After the electrolyte was cooled to room temperature, the exhaust gas was continuously blown into the electrolyte for half an hour. Finally, N 2 The trapping liquid was purged for 30 min and collected to remove dissolved CO in the solution. 2 And collect it with a gas collection bag. CO 2 It will dissolve in the amine electrolyte and be carried to the cathode for electrolysis through the solution flow, producing gaseous products. The nitrogen blowing is to blow out the products, collect and detect them. In theory, CO 2 When the conversion rate is high enough, the gas blown out does not contain CO 2 of.
[0023] Furthermore, in step 2, during the electroreduction phase, the cathode electrolyte is a CO-enriched 2 Bifunctional amine-based electrolyte; the anolyte is KOH, H 2 SO 4 , K 2 SO 4 Preferably, the anolyte is H 2 SO 4 , K 2 SO mixed solution, further the ratio is 1:5; the metal catalyst is one of Au, Ag, Zn nanoparticles, preferably Ag nanoparticles, loaded on a glassy carbon electrode; the reaction device selected in the electro-reduction stage is an H-type reactor; the potential range applied in the electro-reduction stage is -1.2V to -1.6V vs.Ag / AgCl; preferably -1.5V vs.Ag / AgCl.
[0024] The beneficial effects of the present invention compared to the prior art are:
[0025] 1. By using AM with a molar concentration ratio of 2:2:0.35 + The electrolyte is prepared by using amine-based solutes and CTAB, and then hydrochloric acid is titrated to adjust the pH to neutral, thereby improving the carbon dioxide absorption capacity and the Faradaic efficiency of the electroreduction products.
[0026] 2. Under optimal operating conditions, the Faraday efficiency of the product can be further improved, allowing carbon dioxide to be more efficiently converted into high value-added products.
[0027] Experiments show that the bifunctional amine-based electrolyte of the present invention can adsorb CO 2 After reaching saturation, electrocatalytic reduction is carried out in the membrane electrode, and the highest CO Faraday efficiency can reach 60%. After the reaction is carried out for 5 hours, the material maintains a stable Faraday efficiency of 25%. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is the test diagram of the H-type reactor and reaction system;
[0029] Figure 2 CV diagram of the bifunctional amine-based electrolyte prepared in Example 1;
[0030] Figure 3 This is the EIS graph of the bifunctional amine-based electrolyte prepared in Example 1;
[0031] Figure 4 Schematic diagram of the CO2 electrocatalytic reduction performance and stability test of the bifunctional amine-based electrolyte prepared in Example 1. DETAILED DESCRIPTION
[0032] The present invention is further described in detail below in conjunction with specific embodiments, and the examples given are only for illustrating the present invention, rather than for limiting the scope of the present invention. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources. The present invention is further described below in conjunction with examples, and the examples are only used to explain the present invention, rather than to limit the scope of the present invention. It should be understood that the present invention is not limited to the following specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims.
[0033] Example 1
[0034] Step a. Preparation of bifunctional amine-based electrolyte
[0035] a-1: 13DAP (1,3-propylenediamine) with a purity of 98% and deionized water were used in a weight ratio of 3:7 to prepare a 30wt% 13DAP solution, and a mixed solute of potassium chloride and lithium chloride (molar ratio of 1:2), 13DAP and CTAB (hexadecyltrimethylammonium bromide) were prepared in a molar concentration ratio of 2:2:0.35, and potassium chloride and lithium chloride were added to the 13DAP solution and mixed evenly to obtain a precursor;
[0036] a-2: The precursor was ultrasonicated at 50°C for 1 h and then cooled to room temperature;
[0037] a-3: Add CTAB to the precursor solution and heat it to 80° C. in a water bath. After cooling to room temperature, add hydrochloric acid to adjust the pH to neutral to obtain a bifunctional amine-based electrolyte.
[0038] Step b.CO 2 In-situ capture and electrocatalytic reduction performance test
[0039] The H-type reactor and reaction system were used to test the effect of bifunctional amine-based electrolytes on capturing and electrocatalytically reducing carbon dioxide. It mainly includes an H-type reactor, a gas mass flow controller, an electrochemical workstation and a gas chromatograph. The main body of the H-type reactor consists of two parts, the anode and cathode chambers, with a volume of 100 mL each. The two chambers are separated by a Nafion117 proton exchange membrane to prevent cross-mixing of products. A three-electrode system was used for testing, with a 1×1 cm 2 The platinum electrode was used as the counter electrode, the saturated Ag / AgCl electrode was used as the reference electrode, and the glassy carbon electrode (loaded with metal catalyst) (1×1 cm 2 ) as the working electrode.
[0040] First, the prepared bifunctional amine electrolyte was bubbled with CO for 1 h. 2 Waste gas (flow rate is 200 sccm). Since the amine solution absorbs CO 2 It is an exothermic reaction. When the solution is heated, CO 2 The absorption capacity will decrease. After cooling to room temperature, continue to blow waste gas into it for half an hour. Finally, use N 2 Purge the capture solution for 30 min to remove dissolved CO 2 The mixture was collected with an air collection bag. Preparation of nanosilver electrode: Silver nanoparticles, binder (5wt% Nafion and sustainion solution) and anhydrous ethanol were used to prepare catalyst slurry, and the silver nanoparticles were evenly dispersed in the slurry by ultrasonication for 30 minutes and magnetic stirring for 15 minutes. The catalyst slurry was evenly sprayed on the glassy carbon electrode using a spray gun, and the catalyst loading was determined by weighing, and the electrode silver catalyst loading was controlled to be 3mg / cm 2 .
[0041] During the experiment, the H-type reactor was first connected to the electrochemical workstation and the gas pipeline, and then the reaction was started and the gas flow controller switch was turned on (the gas flow rate was 60 sccm) to test the air tightness and sealing. The product detection was carried out in offline mode, and the N released from the high-pressure gas cylinder was 2 Enter the H-type reactor along the pipeline, purge the gas phase product of the working electrode, use a gas collection bag to collect the product, and then inject it into the gas chromatograph for offline concentration detection to calculate the Faraday efficiency of the reaction product. During the reaction, a magnetic stirrer was used to stir the cathode electrolyte solution to enhance material transfer. The Faraday efficiency and current density were tested in the potential range of -1.2V to -1.6V vs.Ag / AgCl. The electrode was subjected to a 20-120mV / s variable scan rate CV test in the non-Faraday potential window of -0.7 to -0.8V vs.Ag / AgCl; at a potential of -1.1V vs.Ag / AgCl, the frequency was swept from 100kHz to 10mHz, and the perturbation was 10mV for EIS test; a potential of 0 to -1.6V vs.Ag / AgCl was applied to the working electrode, and the scan rate was 5mV / s for LSV test; at 50mA / cm 2 The stability test was carried out at a current density of -1.3 V vs. Ag / AgCl; at the test potential of -1.3 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 20% and the current density was 1.1 mA / cm 2 .
[0042] Example 2
[0043] Compared with Example 1, the only difference is that the solute of the amine solution is changed, wherein AM + , the molar concentration ratio of the amine solute and CTAB are the same as those in Example 1, and the experimental groups are:
[0044] Group A: The amine-based solute is MEA;
[0045] Group B: The amine solute is DEA;
[0046] The test was carried out according to the method described in Example 1, and the results were:
[0047] Group A: At the test potential of -1.3 V vs. Ag / AgCl, the maximum CO Faradaic efficiency is 15% and the partial current density is 0.7 mA / cm 2 .
[0048] Group B: At the test potential of -1.4 V vs. Ag / AgCl, the maximum CO Faradaic efficiency was 21% and the partial current density was 0.9 mA / cm 2 .
[0049] By comparing Example 1 with Examples 2A and 2B, it can be seen that using 13DAP as the amine-based solution exhibits better carbon dioxide capture and conversion capabilities.
[0050] Example 3
[0051] Compared with Example 1, the only difference is that AM + The dosage remains unchanged, AM + The other operations and parameters are the same as those in Example 1;
[0052] The test was carried out according to the method described in Example 1. The results were as follows: at a test potential of -1.2 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 16% and the partial current density was 0.8 mA / cm 2 .
[0053] Example 4
[0054] Compared with Example 1, the difference is that AM + The solution is a mixture of sodium chloride and potassium chloride in a ratio of 2:1. + , the molar concentration ratio of the amine solute and CTAB are the same as those in Example 1, and other operations and parameters are the same as those in Example 1.
[0055] The test found that at the test potential of -1.2Vvs.Ag / AgCl, the maximum CO Faraday efficiency was 19% and the current density was 1.1mA / cm 2 .
[0056] Example 5
[0057] Compared with Example 1, the only difference is that the amine-based solute is a mixture of MEA and 13DAP in a ratio of 1:1, and AM + The molar concentration ratio of the solution, the amine solution and the CTAB is the same as that in Example 1, and the other operations and parameters are the same as those in Example 1.
[0058] The test found that at the test potential of -1.1V vs. Ag / AgCl, the maximum CO Faraday efficiency was 20% and the current density was 1.2mA / cm 2 .
[0059] Comparative Example 1
[0060] Compared with Example 1, the only difference is that AM is missing + The missing portion is supplemented by an equal amount of amine solution, and the other operations and parameters are the same as those in Example 1.
[0061] The test was carried out according to the method of Example 1. The results showed that at the test potential of -1.2 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 15% and the partial current density was 0.8 mA / cm 2.
[0062] Comparative Example 2
[0063] Compared with Example 1, the only difference is that the amine solution is missing and the missing portion is replaced by AM + The solution was replenished in equal amounts, and other operations and parameters were the same as in Example 1.
[0064] The test was carried out according to the method of Example 1. The results showed that at a test potential of -1.3 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 0.02% and the partial current density was 0.00003 mA / cm 2 .
[0065] Comparative Example 3:
[0066] Compared with Example 1, the only difference is that the amount of the amine solution is kept constant and the amount of the amine solution and the AM + The proportion of the solution was not controlled within the required range. For example, the experimental groups were:
[0067] Group A: Amine solution and AM + The molar concentration ratio of the solution is 1:1;
[0068] Group B: Amine solution and AM + The molar concentration ratio of the solution is 1:2;
[0069] The test was carried out according to the method described in Example 1, and the results were:
[0070] Group A: At the test potential of -1.2 V vs. Ag / AgCl, the maximum CO Faraday efficiency is 14.2% and the partial current density is 0.71 mA / cm 2 ;
[0071] Group B: At the test potential of -1.3 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 11.2% and the partial current density was 0.43 mA / cm 2 .
[0072] Comparative Example 4
[0073] Compared with implementation 1, the only difference is that CTAB is not added, and other operations and parameters are the same as those in the embodiment.
[0074] The test was carried out according to the method of Example 1. The results showed that at the test potential of -1.2 V vs. Ag / AgCl, the maximum CO Faraday efficiency was 13.1% and the partial current density was 0.72 mA / cm 2 .
[0075] Comparative Example 5
[0076] Compared with Example 1, the only difference is that the pH is not adjusted to neutral, and the other operations and parameters are the same as those in Example 1.
[0077] The test was carried out according to the method of Example 1. The results showed that the maximum CO Faraday efficiency was 15.1% and the partial current density was 0.62 mA / cm 2 .
[0078] Comparative Example 6
[0079] Compared with Example 1, the only difference is that N 2 The collecting liquid was purged for 30 min, and other operations and parameters were the same as those in the embodiment.
[0080] The test was carried out according to the method of Example 1. The results showed that the maximum CO Faraday efficiency was 16.2% and the partial current density was 0.68 mA / cm 2 .
Claims
1. A method for preparing a bifunctional amine-based electrolyte, characterized in that: The method is: Step 1: AM + adding into an amine aqueous solution and mixing evenly to obtain a precursor; Step 2: Ultrasonicate the precursor at 50-60°C for 1-2 hours and then cool it to room temperature; Step 3: Add CTAB to the precursor solution and heat it to 80°C in a water bath. After cooling it to room temperature, adjust the pH to neutral to obtain a bifunctional amine-based electrolyte.
2. The method for preparing a bifunctional amine-based electrolyte according to claim 1, characterized in that: In step 1, the solute of the amine-based aqueous solution is one of monoethanolamine MEA, diethanolamine DEA, N-methyldiethanolamine MDEA, 3-aminopropylamine 3-AP, 1-aminopropylamine 1-AP, ethylenediamine EDA, 1,3-propylenediamine 13DAP, N-methylaminopropylamine MAPA, and diethylenetriamine DETA.
3. The method for preparing a bifunctional amine-based electrolyte according to claim 1, characterized in that: In step 1, the AM + It is at least one of sodium chloride, potassium chloride, lithium chloride and cesium chloride.
4. The method for preparing a bifunctional amine-based electrolyte according to claim 1, characterized in that: In step 1, the mass concentration of the amine aqueous solution is 30%; the amine solute, AM + and CTAB molar concentration ratio is 2:2:0.
35.
5. The method for preparing a bifunctional amine-based electrolyte according to claim 1, characterized in that: In step 3, the method for adjusting the pH is to drop a small amount of hydrochloric acid into the solution until the solution is neutral.
6. A bifunctional amine-based electrolyte prepared by the preparation method according to any one of claims 1 to 5.
7. An application of a bifunctional amine-based electrolyte prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The application is: Step 1: Using bifunctional amine-based electrolytes to absorb carbon dioxide from carbon dioxide-containing flue gas; Step 2: Electroreduction at a certain potential, collecting gas phase products and liquid phase products.
8. The use of a bifunctional amine-based electrolyte according to claim 7, characterized in that: The carbon dioxide content in the carbon dioxide-containing flue gas is 5-30%, and the nitrogen oxides are less than 500 mg / m 3 , sulfur dioxide <1000mg / m 3 , particulate matter <100mg / m 3 .
9. The use of a bifunctional amine-based electrolyte according to claim 7, characterized in that: In step one, during the capture phase, waste gas is bubbled into the bifunctional amine electrolyte for 1 hour at a flow rate of 200 sccm. After it is cooled to room temperature, waste gas is bubbled into it for another half an hour. Finally, the capture liquid is purged with N2 for 30 minutes and collected to remove the dissolved CO2 in the solution and collect it with a gas collection bag.
10. The use of a bifunctional amine-based electrolyte according to claim 7, characterized in that: In step 2, during the electro-reduction stage, the cathode electrolyte is a CO2-enriched bifunctional amine-based electrolyte; the anode electrolyte is one of KOH, H2SO4, and K2SO4; the metal catalyst is one of Au, Ag, and Zn nanoparticles; the reaction device selected for the electro-reduction stage is an H-type reactor; the potential range applied during the electro-reduction stage is -1.2V to -1.6V vs. Ag / AgCl.