Preparation method and application of a double cobalt atom catalyst

Abstract

The application belongs to the technical field of catalytic materials, and discloses a preparation method and application of a double cobalt atom catalyst. The target catalyst Co2-DAC is prepared through the steps of mixed liquid preparation, preheating dropwise adding, constant temperature refluxing and post-treatment purifying, and the reaction condition is mild, inert gas protection is not needed, the process is simple, and the cost is relatively low. The prepared catalyst takes double cobalt atoms as the active center, the atoms are uniformly dispersed, and the structure is stable. With the synergistic effect of the double active sites, the charge transport and CO2 activation performance can be improved, the catalyst shows high activity and stability in the photocatalytic CO2 reduction reaction, can effectively convert CO2 into high value-added products, and provides guidance for designing double atom catalysts with high photocatalytic CO2 reduction activity.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a method for preparing a dual-cobalt atom catalyst and its application. Background Technology

[0002] With the continuous increase in global carbon dioxide (CO2) emissions and the growing severity of environmental problems such as the greenhouse effect and climate change, the efficient conversion of CO2 into high-value-added carbon-based fuels or chemicals has become a core research direction for achieving carbon cycling and sustainable development. Photocatalytic CO2 reduction technology can directly utilize solar energy to drive the conversion of CO2 and H2O into gaseous or liquid products such as carbon monoxide (CO) and hydrogen (H2). It has advantages such as mild reaction conditions and environmental friendliness, and is one of the most promising pathways for the resource utilization of CO2.

[0003] In current photocatalytic CO2 reduction systems, photocatalysts generally suffer from problems such as narrow photoresponse range, severe recombination of photogenerated carriers, and insufficient active sites, resulting in low catalytic efficiency. Single-atom metal catalysts exhibit good activity in photocatalytic CO2 reduction due to their high atom utilization and unique electronic structure; however, a single metal active center cannot meet the multi-step proton-coupled electron transfer requirements of CO2 reduction, and cannot break the linear proportional relationship of reaction intermediate states, making it difficult to further improve product selectivity and catalytic activity.

[0004] Diatomic catalysts, through the synergistic effect of bimetallic sites, can optimize the activation energy of CO2 adsorption, accelerate charge transfer, and regulate the reaction pathway, effectively overcoming the performance bottleneck of single-atom catalysts. Currently, diatomic catalysts are mostly concentrated in the field of electrocatalysis, and research on their structural design, controllable synthesis, and structure-activity relationship in photocatalytic CO2 reduction remains relatively lacking. Based on this, this invention provides a dicobalt atom catalyst that achieves precise anchoring and atomic-level dispersion of dicobalt atoms through a Schiff base reaction, utilizing the synergistic effect of the two active sites to improve the photocatalytic CO2 reduction performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a dual-cobalt atom catalyst. This catalyst has dual cobalt atoms as active centers, exhibiting a stable structure and uniform atomic dispersion. Utilizing the synergistic effect of the two active sites, charge transfer can be accelerated, thereby enhancing the photocatalytic CO2 reduction activity. To achieve the above objective, this invention provides the following technical solution: A method for preparing a cobalt-2 atom catalyst (Co2-DAC), characterized by comprising the following steps: S1. Preparation of the mixture: Dissolve 1.4-1.8 mmol of Co(NO3)2·6H2O and 1.4-1.8 mmol of 2,6-dimethoxy-p-cresol together in 15-25 mL of methanol. Stir the mixture at 200-400 r / min under normal pressure and without inert gas protection to obtain an orange-red transparent mixture. S2. Preheating and Dropping: Transfer the above mixture to a round-bottom flask, heat to reflux at 65-85℃, and stir at 200-400 r / min for 10-20 min; then, while maintaining reflux and stirring, slowly add 1.4-1.8 mmol of 1,3-diaminopropane (dropping time controlled at 10-20 min); S3. Constant temperature reflux reaction: After the addition is complete, maintain the temperature at 65-85℃ and continue the reflux reaction for 2.5-3.5 h. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the mixture is naturally cooled to room temperature. The precipitated solid is collected by filtration and washed 2-4 times with cold methanol at 2-8℃. After each wash, the solid is separated by vacuum filtration. Finally, the washed solid is dried under vacuum at 60-80℃ for 12-24 h to obtain an orange crystalline solid, which is the target product Co2-DAC.

[0006] The advantages of this invention compared to the prior art are as follows: This invention anchors cobalt atoms into the organic framework via a Schiff base reaction, achieving atomic-level dispersion of bimetallic active centers. Compared to single-atom catalysts, the cobalt atom catalyst Co2-DAC possesses more active sites. Furthermore, by utilizing the synergistic effect of the two active sites, the transfer of charge from the photosensitizer to the catalyst can be accelerated, thereby improving the photocatalytic CO2 reduction activity.

[0007] The preparation method of this invention has relatively mild conditions, does not require inert gas protection, can be completed under normal air pressure, has a relatively simple process, and is easy to scale up for production.

[0008] The cobalt used in this invention is a non-precious metal, resulting in lower raw material costs. The entire synthesis process employs conventional reaction apparatus and operations, requiring no special equipment, which helps to lower the economic barrier to catalyst preparation and provides an easily applicable diatomic catalyst synthesis route for the field of photocatalytic CO2 reduction.

[0009] The cobalt-atom catalyst prepared by the method of this invention exhibits excellent catalytic performance in the photocatalytic CO2 reduction reaction. The CO and H2 generation rates are high, and after four consecutive cycles, the catalytic activity did not show a significant decrease, demonstrating good stability for repeated use. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the Co2-DAC catalyst prepared in Example 1; Figure 2 This is the X-ray diffraction (XRD) pattern of the Co2-DAC catalyst prepared in Example 1; Figure 3 The infrared spectrum of the Co2-DAC catalyst prepared in Example 1 is shown below. Figure 4 This is the liquid chromatography-mass spectrum (HPLC) of the Co2-DAC catalyst prepared in Example 1; Figure 5 These are transmission electron microscope (TEM) images (a) and energy dispersive spectroscopy (EDS) spectra (b) of the Co2-DAC catalyst prepared in Example 1. Figure 6 The X-ray photoelectron spectroscopy (XPS) of the Co2-DAC catalyst prepared in Example 1 is shown in (a) as the full spectrum, (b) as the C 1s spectrum, (c) as the N 1s spectrum, and (d) as the Co 2p spectrum. Figure 7 The steady-state fluorescence spectra (PL) of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2 are shown. The black curve is the PL curve of the photosensitizer [Ru(bpy)3]Cl2·6H2O, which is used as a base for control. Figure 8 These are the electrochemical impedance spectroscopy (EIS) spectra of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2. Figure 9 The images show the temperature-time curves (a) and corresponding infrared thermal images (b) of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2 during irradiation. Figure 10 This is a comparison chart of the photocatalytic CO2 reduction performance of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, the Ni2-DAC catalyst prepared in Comparative Example 2, and the Fe2-DAC catalyst prepared in Comparative Example 3. Figure 11 These are the cyclic H2 stability test (a) and cyclic CO stability test (b) of the Co2-DAC catalyst prepared in Example 1; Figure 12 These are long-term H2 generation rate graphs (a) and long-term CO generation rate graphs (b) of the Co2-DAC catalyst prepared in Example 1. Detailed Implementation

[0011] To make the above-mentioned objectives, features, and advantages of the present invention more readily understood, the specific embodiments of the present invention will be described in detail below with reference to examples. The following content is only for illustrative purposes and explanation of the inventive concept. Those skilled in the art can make various modifications, additions, or similar substitutions to the specific embodiments described, as long as they do not deviate from the core concept of the present invention or exceed the scope defined by the claims, they should all be included in the protection scope of the present invention.

[0012] The preparation method of the present invention will be described in detail below through specific embodiments and comparative examples.

[0013] Example 1 A method for preparing a cobalt-atom catalyst Co2-DAC includes the following steps: S1. Preparation of the mixture: 1.6 mmol of Co(NO3)2·6H2O and 1.6 mmol of 2,6-dimethoxy-p-cresol were dissolved together in 20 mL of methanol. The mixture was stirred at 300 r / min under normal pressure and without inert gas protection to obtain an orange-red transparent mixture. S2. Preheating and addition: Transfer the above mixture to a round-bottom flask, heat it to reflux at 75°C, and stir at 300 r / min for 15 min; then, while maintaining reflux and stirring, slowly add 1.6 mmol of 1,3-diaminopropane (the addition time is controlled at 15 min). S3. Constant temperature reflux reaction: After the addition is complete, maintain the temperature at 75°C and continue the reflux reaction for 3 hours. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the solid precipitate is naturally cooled to room temperature, filtered and collected, and washed three times with cold methanol at 5°C. After each wash, the precipitate is separated by vacuum filtration. Finally, the washed solid is vacuum dried at 70°C for 18 h to obtain an orange crystalline solid, which is the target product Co2-DAC.

[0014] Example 2 A method for preparing a cobalt-atom catalyst Co2-DAC includes the following steps; S1. Preparation of the mixture: 1.4 mmol of Co(NO3)2·6H2O and 1.4 mmol of 2,6-dimethoxy-p-cresol were dissolved together in 15 mL of methanol. The mixture was stirred at 200 r / min under normal pressure and without inert gas protection to obtain an orange-red transparent mixture. S2. Preheating and addition: Transfer the above mixture to a round-bottom flask, heat it to reflux at 65°C, and stir at 200 r / min for 10 min; then, while maintaining reflux and stirring, slowly add 1.4 mmol of 1,3-diaminopropane (the addition time is controlled at 10 min). S3. Constant temperature reflux reaction: After the addition is complete, maintain reflux at 65°C for 2.5 h. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the solid precipitate is naturally cooled to room temperature, filtered and collected, and washed twice with cold methanol at 2°C. After each washing, the precipitate is separated by vacuum filtration. Finally, the washed solid is vacuum dried at 60°C for 12 h to obtain an orange crystalline solid, which is the target product Co2-DAC.

[0015] Example 3 A method for preparing a cobalt-atom catalyst Co2-DAC includes the following steps: S1. Preparation of the mixture: 1.8 mmol of Co(NO3)2·6H2O and 1.8 mmol of 2,6-dimethoxy-p-cresol were dissolved together in 25 mL of methanol. The mixture was stirred at 400 r / min under normal pressure and without inert gas protection to obtain an orange-red transparent mixture. S2. Preheating and addition: Transfer the above mixture to a round-bottom flask, heat it to reflux at 85°C, and stir at 400 r / min for 20 min; then, while maintaining reflux and stirring, slowly add 1.8 mmol of 1,3-diaminopropane (the addition time is controlled at 20 min). S3. Constant temperature reflux reaction: After the addition is complete, maintain reflux at 85°C for 3.5 h. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the solid precipitate is naturally cooled to room temperature, filtered and collected, and washed 4 times with cold methanol at 8°C. After each washing, the precipitate is separated by vacuum filtration. Finally, the washed solid is vacuum dried at 80°C for 24 h to obtain an orange crystalline solid, which is the target product Co2-DAC.

[0016] Comparative Example 1 (Co-SAC catalyst with a single cobalt atom) A method for preparing a single cobalt atom Co-SAC catalyst includes the following steps: S1. Preparation of the mixture: 0.8 mmol of Co(NO3)2·6H2O and 1.6 mmol of 5-methylsalicylaldehyde were dissolved together in 20 mL of methanol. The mixture was stirred at 300 r / min under normal pressure and without inert gas protection to obtain a homogeneous mixture. S2. Preheating and addition: Transfer the above mixture to a 50 mL round-bottom flask, heat to reflux at 75 °C, and stir at 300 r / min for 15 min; then, while maintaining reflux and stirring, slowly add 0.8 mmol of 1,3-diaminopropane dropwise over a period of 15 min. S3. Constant temperature reflux reaction: After the addition is complete, maintain the temperature at 75°C and continue the reflux reaction for 3 hours. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the mixture is naturally cooled to room temperature, and the precipitated solid is collected by filtration. The precipitate is washed three times with cold methanol at 5°C, and separated by vacuum filtration after each wash. Finally, the washed solid is vacuum dried at 70°C for 18 h to obtain a purple crystalline solid, which is the target product, the single cobalt atom catalyst Co-SAC.

[0017] Comparative Example 2 (Ni2-DAC, a double nickel atom catalyst) A method for preparing a Ni2-DAC catalyst with two nickel atoms includes the following steps: S1. Preparation of the mixture: 3.5 mmol of NiCl2·6H2O, 2.4 mmol of 2,6-dicarboxy-4-methylphenol and 1.6 mmol of 1,3-diaminopropane were dissolved together in 50 mL of isopropanol. The mixture was stirred at 300 r / min under normal pressure and without inert gas protection to obtain a homogeneous mixture. S2, reflux reaction at constant temperature: Transfer the above mixture to a 100 mL round-bottom flask and reflux at 75 °C for 18 h. The entire reaction process is carried out under normal pressure and air atmosphere. S3. Post-processing purification: After the reaction is completed, the mixture is allowed to cool naturally to room temperature, and the precipitated solid precipitate is collected by filtration. The precipitate is washed with boiling methanol in 40 mL for 3 h, and then filtered while hot to remove insoluble residue. The filtrate is evaporated by rotary evaporation to obtain light green flaky crystals, which are the target product, the double nickel atom catalyst Ni2-DAC.

[0018] Comparative Example 3 (Fe2-DAC, a dual-iron catalyst) A method for preparing a double-iron Fe2-DAC catalyst includes the following steps: S1. Pre-reaction treatment: Methanol is subjected to strict deoxygenation treatment by bubbling with nitrogen for 30 minutes before use.

[0019] S2. Preparation of the mixture: Under nitrogen protection, 1.4 mmol of FeCl2·4H2O was placed in a 100 mL round-bottom flask, and 8.75 mL of the above-mentioned deoxygenated methanol was added. The mixture was stirred at 300 r / min and heated to reflux while maintaining a flowing nitrogen atmosphere.

[0020] S3. Sequential Addition and Reaction: Under reflux, stirring, and nitrogen protection, add the following two pre-prepared solutions sequentially to the flask: first, add 1.25 mL of a boiling, deoxygenated methanol solution containing 2.1 mmol of 1,3-diaminopropane; then, add 8.75 mL of a boiling, deoxygenated methanol solution containing 1.23 mmol of 2,6-dicarboxy-4-methylphenol. After the addition is complete, continue reflux for 120 min.

[0021] S4. Post-processing purification: After the reaction is completed, the mixture is naturally cooled to room temperature. Under nitrogen protection, the dark purple crystalline precipitate is collected by filtration. It is washed three times with cold methanol at 5°C. After separation by vacuum filtration, it is dried under vacuum at 70°C for 18 h to obtain the target product Fe2-DAC.

[0022] Figure 1 This is a schematic diagram of the structure of the Co2-DAC catalyst prepared in Example 1.

[0023] Figure 2 The XRD pattern of the Co2-DAC catalyst prepared in Example 1 shows that the diffraction peaks of the Co2-DAC sample are consistent with the theoretical XRD diffraction peaks, proving the successful preparation of the catalyst.

[0024] Figure 3 This is the infrared spectrum of the Co2-DAC catalyst prepared in Example 1, with a wavenumber of 1551 cm⁻¹. -1 The stretching vibration corresponding to the C=N double bond revealed that the catalyst contains C=N bonds, confirming the successful synthesis of the catalyst.

[0025] Figure 4 The HPLC spectrum of the Co2-DAC catalyst prepared in Example 1 shows a significant peak at 693.03, which is consistent with the theoretical relative molecular mass of Co2-DAC, further proving the successful preparation of the catalyst.

[0026] Figure 5 These are TEM images (a) and EDS images (b) of the Co2-DAC catalyst prepared in Example 1. The TEM images show that the Co2-DAC photocatalyst has a rhomboid block morphology, and the EDS analysis confirms the highly uniform distribution of the constituent elements (C, N, O, and Co) in the Co2-DAC photocatalyst.

[0027] Figure 6The XPS spectra of the Co2-DAC catalyst prepared in Example 1 are shown in Figure (a), which is the full spectrum, (b) is the C 1s spectrum, (c) is the N 1s spectrum, and (d) is the Co 2p spectrum. Figure (a) shows the complete XPS spectrum of the Co2-DAC catalyst, revealing that the main elements in the Co2-DAC catalyst are C, N, O, and Co. From the high-resolution C 1s spectrum in Figure (b), it can be seen that the four characteristic peaks located at 284.7, 285.6, 286.2, and 286.9 eV correspond to CC / C=C, CN, CO, and C=N bonds, respectively. The high-resolution C 1s spectrum shows that the Co2-DAC sample contains C=N bonds and lacks C=O functional groups, which corresponds to the results of the infrared spectroscopy. In the high-resolution N 1s spectrum of Figure (c), four characteristic peaks appear at binding energies of 399.2 eV, 400.4 eV, 403.1 eV, and 406.7 eV, corresponding to C=NC, C=N-Co, NO, and amines containing functional groups, respectively, confirming the presence of Co-N coordination in the Co2-DAC. The high-resolution XPS spectrum of Co 2p in Figure (d) can be divided into four main peaks located at 781.4, 786.2, 796.6, and 802.5 eV, corresponding to Co 2p... 3 / 2 Co 2p 3 / 2 Satellite peak, Co 2p 1 / 2 and Co 2p 1 / 2 Satellite Peak.

[0028] Figure 7 The photoluminescence (PL) values ​​are for the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2. The black curve represents the PL curve of the photosensitizer [Ru(bpy)3]Cl2·6H2O, which serves as a blank control. Compared to the blank photosensitizer [Ru(bpy)3]Cl2·6H2O, the steady-state fluorescence peak emission intensity significantly decreased with the addition of Co2-DAC, Co-SAC, and Ni2-DAC, indicating that fluorescence emission was effectively quenched. This demonstrates that all three catalysts can effectively accept photogenerated electrons from the photosensitizer. Compared to the Co-SAC and Ni2-DAC samples, the fluorescence emission peak intensity of the Co2-DAC catalyst decreased more significantly, indicating that the cobalt-atom active sites can more effectively enhance the electron-hole separation efficiency in the photosensitizer, thereby improving the photocatalytic CO2 reduction performance.

[0029] Figure 8The EIS of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2 are shown. The radius of the arc in the impedance spectrum of the Co2-DAC sample is much smaller than that of Co-SAC and Ni2-DAC, indicating that the charge transfer ability of the Co2-DAC sample in CO2 reduction is much higher than that of Co-SAC and Ni2-DAC at the solid-electrolyte interface. The active sites of the two cobalt atoms promote the photoinduced charge separation process, thereby improving the photoreduction efficiency of CO2.

[0030] Figure 9 Figure (a) shows the temperature-time curves (and corresponding infrared images) during irradiation of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, and the Ni2-DAC catalyst prepared in Comparative Example 2. The initial temperature of the CO2 reduction reaction system was approximately 25 °C. The system temperature rose rapidly in the initial stage and reached a steady state within 1 h. The final reaction temperature of the Co2-DAC catalyst reached 53.1 °C, significantly higher than that of Co-SAC (42.1 °C) and Ni2-DAC (43.0 °C). Infrared imaging of the final temperatures of the Co2-DAC, Co-SAC, and Ni2-DAC reaction systems confirmed this result (Figure b). The results clearly show that Co2-DAC is most helpful in increasing the reaction temperature, thereby accelerating the photocatalytic CO2 reduction process.

[0031] Figure 10This is a comparison of the photocatalytic CO2 reduction performance of the Co2-DAC catalyst prepared in Example 1, the Co-SAC catalyst prepared in Comparative Example 1, the Ni2-DAC catalyst prepared in Comparative Example 2, and the Fe2-DAC material prepared in Comparative Example 3. The photocatalytic CO2 conversion experiment was conducted in a sealed 80 mL reactor at room temperature and pressure. The reaction light source was a 300 W xenon lamp with a cutoff filter of λ ≥ 420 nm. First, 1 mg of catalyst and 10 mg of [Ru(bpy)3]Cl2·6H2O were added to a mixed solution of acetonitrile, H2O, and triethanolamine (TEOA) (volume ratio 3:1:1, total volume 5 mL), and then sonicated for 5 min to obtain a homogeneous solution. The solution was then sealed, and high-purity CO2 (99.999%) gas was passed through the solution for 30 min to purge air. The resulting H2 was analyzed on a gas chromatograph (GC-1690) equipped with a thermal conductivity detector (TCD), using Ar as the carrier gas. The generated CO2 was analyzed using a gas chromatograph (GC-5190) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD), with N2 as the carrier gas. In the first 3 hours of the photocatalytic experiment, the rate of CO2 reduction to CO by the Co2-DAC catalyst reached 16.74 mmol g. -1 h -1 The H2 production rate was 25.38 mmol g. -1 h -1 With the single-Co atom catalyst Co-SAC (CO: 11.97 mmol g) -1 h -1 H2: 6.91 mmol g -1 h -1 Compared to Ni2-DAC and Fe2-DAC, CO production increased by 1.4 times and H2 production increased by 4 times, which was also significantly higher.

[0032] Figure 11 The images show the cyclic H2 stability test (a) and cyclic CO stability test (b) of the Co2-DAC catalyst prepared in Example 1. After four consecutive cycles (12 h in total), the CO and H2 production rates decreased slightly. The reduction in CO and H2 production rates is likely due to the consumption of the sacrificial agent TEOA, indicating that Co2-DAC has excellent photocatalyst stability.

[0033] Figure 12The figures (a) and (b) show the long-term H2 production rate and CO production rate of the Co2-DAC catalyst prepared in Example 1. The optimal experimental results for long-term photocatalytic CO2 reduction and the production of CO and H2 were tested under monochromatic light (λ=420 nm). The results show that the production of H2 and CO gradually increases over 24 h, further confirming the stability of the Co2-DAC catalyst. However, with increasing irradiation time, the production rates of CO and H2 gradually decrease. This is likely due to the decomposition of the photosensitizer [Ru(bpy)3]Cl2·6H2O over a longer reaction time, rather than catalyst deactivation.

Claims

1. The application of a dual-cobalt atom catalyst, characterized in that, Application of this catalyst in the photocatalytic reduction of CO2 to produce H2 and CO; The method for preparing the catalyst includes the following steps: S1. Preparation of the mixture: Co(NO3)2·6H2O and 2,6-dimethoxy-p-cresol were dissolved together in methanol and stirred evenly to obtain an orange-red transparent mixture. S2. Preheating and Dropping: Transfer the mixture obtained in step S1 to a round-bottom flask, heat under reflux and stir; then, while maintaining reflux and stirring, slowly add 1,3-diaminopropane dropwise. S3. Refluxing at constant temperature: After the addition of 1,3-diaminopropane in step S2 is complete, the reflux reaction continues. The entire reaction process is carried out under normal pressure and air atmosphere. S4. Post-processing purification: After the reaction is completed, the mixture is allowed to cool naturally to room temperature. The precipitated solid is collected by filtration, washed with cold methanol and separated by vacuum filtration. Finally, the washed solid is dried under vacuum to obtain an orange crystalline solid, which is the target product Co2-DAC.

2. The application according to claim 1, characterized in that, In step S1 of the preparation method, the amount of Co(NO3)2·6H2O is 1.4-1.8 mmol, and the amount of 2,6-dimethoxy-p-cresol is 1.4-1.8 mmol.

3. The application according to claim 1, characterized in that, In step S1 of the preparation method, the amount of methanol used is 15-25 mL.

4. The application according to claim 1, characterized in that, In step S1 of the preparation method, the stirring conditions are atmospheric pressure, no inert gas protection, and a stirring speed of 200-400 r / min.

5. The application according to claim 1, characterized in that, In step S2 of the preparation method, the reflux temperature is 65-85℃ and the stirring time is 10-20 min.

6. The application according to claim 1, characterized in that, In step S2 of the preparation method, the amount of 1,3-diaminopropane used is 1.4-1.8 mmol, and the dropping time is controlled to be 10-20 min.

7. The application according to claim 1, characterized in that, In step S3 of the preparation method, the reflux reaction temperature is 65-85℃ and the reaction time is 2.5-3.5 h.

8. The application according to claim 1, characterized in that, In step S4 of the preparation method, the temperature of the cold methanol is 2-8℃, and the number of washing cycles is 2-4.

9. The application according to claim 1, characterized in that, In step S4 of the preparation method, the vacuum drying conditions are 60-80℃ and drying for 12-24 h.

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