Carbon-based metastable photoacid composite material, preparation method thereof, and application in CO2 capture

Abstract

The present invention discloses a carbon-based metastable photoacid composite material, a preparation method thereof, and an application in CO2 capture, belonging to the field of CO2 capture and solar energy utilization. The carbon-based metastable photoacid composite material is composed of a carbon-based material and a metastable photoacid, and the mass ratio of the carbon-based material to the metastable photoacid is 1:(1~30). The composite material utilizes the metastable photoacid to absorb the ultraviolet band in the solar spectrum, and the carbon-based material absorbs the visible-infrared band in the solar spectrum, thereby achieving full-spectrum solar absorption; wherein the ultraviolet band photons are converted into chemical energy by the metastable photoacid, and the visible-infrared band photons are converted into thermal energy by the carbon-based material. The synergistic conversion of solar light chemistry and heat causes the CO2-rich liquid to undergo chemical desorption and thermal desorption simultaneously, thereby achieving quality and efficiency improvement of the desorption of the CO2-rich liquid driven by solar energy. The present invention can realize the full-spectrum utilization of solar energy, solving the problem of inefficient solar energy utilization caused by the single conversion mode and low conversion efficiency of the existing solar carbon capture technology.

Description

Technical Field

[0001] The present invention belongs to the field of CO2 capture and solar energy utilization, and specifically relates to the preparation of a medium material for solar energy conversion and its application in capturing CO2 in industrial processes, energy utilization or the atmosphere. Background Art

[0002] CO2 capture is the most direct and effective large-scale greenhouse gas emission reduction technology available today, and it forms the foundation for the implementation of Carbon Capture, Utilization, and Storage (CCUS). However, traditional CO2 capture methods (such as chemical absorption) suffer from high energy consumption, volatile solvents, and equipment corrosion, which severely restrict the large-scale application and promotion of this technology.

[0003] In recent years, chemical absorption methods powered by solar energy have achieved green energy supply in the carbon capture process, opening up a new path to addressing the bottleneck of high energy consumption. Traditional solar-driven CO2 capture strategies use solar collectors to convert solar energy into thermal energy, partially replacing power plant extraction steam as the driving force for desorption of CO2-rich liquid. However, due to the poor absorption and conversion efficiency of solar energy by the collecting media (water, oil, and alcohols) (approximately 20%), large-scale solar collector arrays must be deployed to meet the energy requirements for CO2 capture, which undoubtedly increases the investment and operating costs of carbon capture. Furthermore, the intermittent and unstable nature of solar energy poses a serious challenge to the sustained and stable operation of CO2 capture systems. To improve the absorption performance of sunlight and enhance the efficiency of photothermal conversion, researchers have introduced photothermal materials into absorbent solutions. These materials can directly absorb and convert solar energy and act as heat treatment units, thermally treating the surrounding absorbent CO2 products to achieve CO2 desorption and absorbent regeneration. Carbon-based materials (graphene, carbon black, carbon nanotubes) are often used in solar-driven CO2 capture systems because they can produce continuous energy levels, exhibit wide-spectrum light absorption characteristics and strong photothermal conversion performance, and are cheap and readily available. For example, Yu et al. introduced reduced graphene (RGO) into a graphene nanofluid (DES500) composed of choline chloride (ChCl) and monoethanolamine (MEA). When irradiated with 1000 W / m² of sunlight for 120 minutes, the temperature of DES500 increased from 54.7 °C to 75.9 °C, and CO 22 The desorption capacity increased by 400% compared to pure ChCl / MEA solution. Nguyen et al. introduced 0.1wt% carbon black into MEA solution to construct a nanofluid with photothermal conversion properties. Under 2.6 W light irradiation, the CO2 desorption efficiency was four times that of the CO2-rich MEA solution without carbon black.

[0004] However, carbon-based materials lack the ability to capture the entire solar spectrum. Their response bands are primarily concentrated in visible and near-infrared light (400-2500 nm), with weak absorption of ultraviolet light (250-400 nm). This results in insufficient utilization of solar photon energy, and a ceiling for solar energy utilization efficiency (£60%), which cannot meet the full energy requirements for CO2 capture. Therefore, comprehensive exploration and overall optimization of solar-driven CO2 capture technologies are urgently needed to achieve more comprehensive solar energy capture, higher energy conversion, and more stable CO2 capture. Summary of the Invention

[0005] The purpose of the present invention is to address the major technical problems of existing solar carbon capture technology, such as low solar energy utilization efficiency caused by a single conversion mode and low conversion efficiency, which cannot meet the energy requirements of CO2 capture. The present invention provides a carbon-based metastable photoacid composite material, a preparation method thereof, and its application in CO2 capture. The composite material can provide sufficient energy for the desorption of CO2 rich liquid by absorbing and converting the entire spectrum of solar energy during the desorption of CO2 rich liquid, thereby improving the quality and efficiency of solar carbon capture.

[0006] The carbon-based metastable photoacid composite material provided by the present invention is composited with a carbon-based material and a metastable photoacid, wherein the mass ratio of the carbon-based material to the metastable photoacid is 1:(1-30).

[0007] The composite material utilizes the π-bonded conjugated structures, such as the benzene rings, within metastable photoacid molecules. These structures are then adsorbed onto the surface of a carbon-based material through π-π stacking, forming a carbon-based metastable photoacid composite material. This composite not only uniformly and tightly anchors the metastable photoacid molecules to the carbon-based surface, forming a molecular-level contact interface, but also promotes rapid transfer of photogenerated protons and heat, avoiding the light scattering and blocking issues associated with physical mixing. This ensures that both ultraviolet (metastable photoacid) and visible-infrared (carbon-based) light are fully captured (physical mixing can cause material agglomeration and partially block the absorption spectrum). This composite material aims to achieve full solar spectrum absorption, with the metastable photoacid absorbing the ultraviolet and the carbon-based material absorbing the visible-infrared. Simultaneously, absorbed ultraviolet photons are converted into chemical energy by the metastable photoacid, while visible-infrared photons are converted into thermal energy by the carbon-based material. This dual energy conversion effect causes the CO2-rich liquid to undergo chemical desorption and thermal desorption simultaneously, thereby improving the quality and efficiency of CO2-rich liquid desorption.

[0008] Furthermore, the carbon-based material includes but is not limited to one or more of carbon nanotubes, graphene, and carbon black; the metastable photoacid is at least one of a merocyanine-type metastable photoacid, an indazole-type metastable photoacid, and a tricyanofuran-type metastable photoacid, and their structural formulas are as follows:

[0009] ,

[0010] In the structural formula, R1, R2, and R3 are each one of H, OMe, OH, CHO, F, Cl, Br, and NO2, among which OMe, OH, and CHO are electron-donating groups, and F, Cl, Br, and NO2 are electron-withdrawing groups. R1, R2, and R3 may be the same or different.

[0011] Furthermore, the merocyanine-type metastable photoacid is prepared by the following method:

[0012] First, 2,3,3-trimethyl-3H-indole is added to 1,3-propane sultone, the temperature is raised to 60-90 °C, and the reaction is carried out in a N2 atmosphere for 6-24 hours. After the reaction is completed, the solid is filtered and collected, washed with ether, and freeze-dried for 8-12 hours. Subsequently, the intermediate product and 2-hydroxybenzaldehyde with different substituents are added to anhydrous ethanol in a molar ratio of (1.0-1.5):1, the temperature is raised to 90-120 °C, and the solid is refluxed under a N2 atmosphere for 8-12 hours. The solid is filtered and collected, washed with ethanol, and dried to obtain a merocyanine-type metastable photoacid. Different types of merocyanine-type metastable photoacids are obtained depending on the substituents of the 2,3,3-trimethyl-3H-indole used.

[0013] The indazole-type metastable photoacid is prepared by the following method:

[0014] 2-Methylbenzothiazole and 1,3-propane sultone were dissolved in toluene at a molar ratio of 1.0-1.5:1 and stirred under a nitrogen atmosphere for 5-12 hours. The solid was collected by filtration and washed with tetrahydrofuran to obtain the benzothiazole sulfonate. Subsequently, the benzothiazole sulfonate and 1H-indazole-7-carboxaldehyde were dissolved in ethanol at a molar ratio of 1.0-1.2:1. A catalytic amount of ammonium acetate was added and the mixture was refluxed for 2-4 hours. After cooling, the solid precipitate was filtered and washed with ethanol to obtain the indazole-type metastable photoacid. Different types of indazole-type metastable photoacids were obtained depending on the substituents on the 2-methylbenzothiazole.

[0015] The tricyanofuran-type metastable photoacid is prepared by the following method:

[0016] 20 wt.% sodium ethoxide was added to a solution of 3-hydroxy-3-methyl-2-butanone and malononitrile in anhydrous ethanol. The mixture was irradiated with red light under a nitrogen atmosphere and stirred at room temperature for 20–48 h. The solid was then rotary evaporated in a vacuum, washed with ethanol, and dried under vacuum to obtain the intermediate. Subsequently, a catalytic amount of ammonium acetate, the intermediate, and salicylaldehyde were added to the ethanol solution. The mixture was irradiated with red light under a nitrogen atmosphere and stirred at room temperature for 96 h. The solid precipitate was filtered and washed with cold ethanol to obtain a tricyanofuran-type metastable photoacid. Different types of tricyanofuran-type metastable photoacids were obtained depending on the substituents in the 3-hydroxy-3-methyl-2-butanone.

[0017] The method for preparing the carbon-based metastable photoacid composite material provided by the present invention is characterized by comprising the following steps:

[0018] The metastable photoacid and the carbon-based material dispersion are added to a certain amount of water, stirred until the metastable photoacid is dissolved, and then ultrasonically treated for 30 to 60 minutes to obtain the carbon-based metastable photoacid.

[0019] In the above method, further, the carbon-based material dispersion is prepared by dispersing the carbon-based material in pure water, or a mixed solvent of water and a water-soluble organic solution (such as DMSO, DMF).

[0020] In the above method, further, the mass concentration of the carbon-based material dispersion is 0.002%~0.02%.

[0021] The present invention also provides an application of the above-mentioned carbon-based metastable photoacid composite material in carbon capture, utilization and storage (CCUS), more specifically in solar-driven CO2 capture.

[0022] Furthermore, the application is to desorb CO2 rich liquid during CO2 capture by chemical absorption method based on organic alcohol amine, thereby achieving quality improvement and efficiency enhancement of CO2 rich liquid desorption and regeneration of chemical absorbent.

[0023] The present invention also provides a method for capturing CO2 using the carbon-based metastable photoacid composite material under solar-driven conditions, comprising the following steps:

[0024] Step 1: Dissolve the carbon-based metastable photoacid composite material and the chemical absorbent in a pre-prepared mixed solvent of a physical solvent and water to obtain an absorbent solution, and contact the absorbent solution with a gas containing CO2 to absorb CO2 and form a CO2-rich solution (a solution with a high CO2 loading).

[0025] Step 2: Place the CO2-rich solution in the above step under sunlight to promote rapid desorption of CO2. After desorption is completed, a CO2-lean solution (a solution with low CO2 load) is obtained.

[0026] Step 3: After the desorption of CO2 is completed, the CO2-lean liquid is placed in a dark place to promote the regeneration of the chemical absorbent and the carbon-based metastable photoacid for subsequent recycling.

[0027] Furthermore, in step 1, the amount of the carbon-based metastable photoacid is 0.05 to 3.0 times the amount of the chemical absorbent.

[0028] Furthermore, the chemical absorbent includes but is not limited to monoethanolamine, diethanolamine, N - at least one of methyldiethanolamine, 2-amino-2-methyl-1-propanol, ethylenediamine, triethylamine, piperazine, aqueous ammonia and potassium carbonate.

[0029] Furthermore, the physical solvent is toluene, carbon tetrachloride, N,N - one or more of dimethylamide, dimethyl sulfoxide, sulfolane and diethylene glycol dimethyl ether.

[0030] Furthermore, the mass ratios of the carbon-based metastable photoacid, chemical absorbent, physical solvent and water are (10% to 20%): (10% to 30%): (0% to 45%): (5% to 80%).

[0031] The present invention also provides a composition comprising the metastable photoacid prepared by the above method and the above carbon-based material, wherein the mass ratio of the carbon-based material to the metastable photoacid is 1:(1-30).

[0032] The present invention also provides a combined application of the metastable photoacid prepared by the above method and the above carbon-based material in CO2 capture. The application is to perform solar-driven desorption of CO2-rich liquid during CO2 capture by a chemical absorption method based on organic alcohol amines, thereby achieving quality improvement and efficiency enhancement of CO2-rich liquid desorption and regeneration of the chemical absorbent.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention adopts a carbon-based metastable photoacid composite material as a sunlight conversion medium, realizes the full absorption of the solar spectrum, and utilizes the photothermal effect and photochemical mechanism of the carbon-based metastable photoacid composite material to realize the conversion of sunlight into thermal energy and chemical energy, significantly improving the conversion efficiency of sunlight, meeting the CO2 capture energy requirements, and realizing the quality and efficiency improvement of CO2 rich liquid desorption.

[0035] 2. The present invention uses light as the energy source for CO2 desorption, which completely solves the bottleneck problems of high energy consumption and high cost of traditional absorption methods. In addition, light has the advantages of precise controllability in operation time and space, no introduction of chemical pollutants, and remote control. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The metastable photoacid (MCH + )of 1 H NMR spectrum.

[0037] Figure 2 It is the MCH prepared in Example 1 + of 13 C NMR spectrum.

[0038] Figure 3 The graphene / metastable photoacid composite material (MCH + / GOr), graphene (GOr) and metastable photoacid (MCH + )’s infrared spectrum.

[0039] Figure 4 It is the MCH prepared in Example 1 + / GOr, GOr and MCH + Raman spectrum of .

[0040] Figure 5 It is MCH + / GOr in N -UV-Vis-NIR spectral transmittance in methyldiethanolamine (MDEA) solution.

[0041] Figure 6 MCH in Example 1 + The CO2 desorption rate of CO2 rich liquid with MDEA as chemical absorbent is desorbed by / GOr, MCH, and Gor respectively over time.

[0042] Figure 7 is MCH in Example 1 + Comparison of the change of CO2 desorption rate over time in CO2-rich liquid with MDEA as chemical absorbent and cyclic desorption of Gor.

[0043] Figure 8 MCH in Example 2 + / GOr desorption of CO2 rich liquid with monoethanolamine (MEA) as chemical absorbent.

[0044] Figure 9 The carbon nanotube / metastable photoacid (MCH + Figure 3. CO2 desorption rate variation over time of CO2 rich solution with MDEA as chemical absorbent (CNT). DETAILED DESCRIPTION

[0045] The preparation method and application of the carbon-based metastable photoacid composite material of the present invention are further described below through specific embodiments.

[0046] Example 1

[0047] (1) Preparation of metastable photoacid: Weigh an appropriate amount of 2,3,3-trimethyl-3H-indole, add an equal molar amount of 1,3-propane sultone dropwise, heat to 90 °C, react under N2 atmosphere for 6 h, grind the obtained product, rinse with ether, and freeze-dry for 12 h to obtain 2,3,3-trimethyl-1-(3-sulfopropyl)-3H-indole. Weigh 2.85 g (10 mmol) of 2,3,3-trimethyl-1-(3-sulfopropyl)-3H-indole and dissolve it in 40 ml of anhydrous ethanol. Then add 1.22 g (10 mmol) of 2-hydroxybenzaldehyde, heat to 85 °C, react under N2 atmosphere for 12 h, filter, and freeze-dry for 12 h to obtain merocyanine-type metastable photoacid (MCH + ) (metastable photoacid spiropyran). Its structural characterization is shown in 1 H NMR ( Figure 1 )and 13 C NMR spectrum ( Figure 2 ), the chemical shifts of the proton peaks in the compound have been assigned in the spectrum, and the integrated area ratios of the proton resonance peaks are in good agreement with the theoretical values, indicating that the compound has been successfully synthesized.

[0048] (2) Preparation of graphene / metastable photoacid composite material: 5 mg of metastable photoacid and 1 mL of 5 mg / mL single-layer graphene oxide (GOr) dispersion were weighed and dissolved in 50 mL of deionized water, stirred for 3 h, and ultrasonicated for 30 min to obtain graphene / metastable photoacid composite material (MCH + / GOr) solution, freeze-dried to obtain MCH + / GOr, its FT-IR spectrum ( Figure 3 )MCH + / GOr MCH appeared + The characteristic absorption peak of Raman spectrum ( Figure 4 ) confirmed MCH + / GOr D peak (1352 cm -1 ) and G peak (1392 cm -1 ) relative to GOr (D peak at 1347 cm -1 , G peak is at 1592 cm -1 ) are red-shifted, and both confirm that MCH + Successfully loaded to GOr.

[0049] (3) MCH + Optical absorption properties of / GOr

[0050] 5 gN -Methyldiethanolamine (MDEA) was added to 50 mL of MCH + / GOr solution, fully mix and stir, and ultrasonicate for 10 minutes to obtain MDEA-MCH + / GOr solution. The transmission spectrum of 200~1100 nm was tested by UV-visible-near infrared spectrophotometer. The results showed that the introduction of MCH + / GOr, the MDEA solution has a low spectral transmittance in the 200~1100 nm range, especially in the 250~600 nm range, the spectral transmittance is basically 0, and decreases with the increase of GOr mass fraction. + When the mass ratio of MDEA / GOr is 1:20, the transmittance of the solution in the 600-1100 nm region is reduced by nearly 60% compared with the pure MDEA solution ( Figure 5 ), which shows that MCH + / GOr can significantly absorb sunlight from 200 to 1100 nm, that is, it can absorb the entire spectrum of ultraviolet, visible and near-infrared light.

[0051] (4) Desorption of CO2-rich solution by sunlight:

[0052] To MDEA-MCH + Simulated flue gas (15% CO2, 85% N2) is introduced into the / GOr solution. When the CO2 concentration at the outlet reaches 15%, MDEA-MCH is obtained. + / GOr CO2-rich solution. AM1.5 solar simulator simulates sunlight and irradiates MDEA-MCH + / GOr CO2-rich solution, light energy density 50 mW / cm 2 , N2 was used as carrier gas at a flow rate of 100 mL / min, and the exhaust CO2 concentration was monitored and recorded. Figure 6 Show MDEA-GOr / MCH + The desorption rate of CO2-rich solution changes with time and is compared with that of MDEA-MCH + CO2 rich liquid (MCH + The results showed that MDEA-MCH had a strong affinity to MDEA, and the mixed solution of MDEA and MDEA absorbed CO2, MDEA-GOr CO2 rich solution (the mixed solution of GOr and MDEA absorbed CO2 rich solution) and blank CO2 rich solution were compared under the same illumination conditions. + / GOr CO2 has a significant improvement in the desorption rate and amount of CO2-rich liquid. The desorption rate of CO2-rich liquid is 9 times that of blank CO2-rich liquid. This is attributed to the fact that MCH +The broad spectrum light capture capability of / GOr and its photothermal-photochemical synergistic conversion achieves efficient utilization of solar energy in all wavelengths. The solution after desorption of CO2 is placed in the dark to promote the regeneration of the absorbent and carbon-based metastable photoacid for subsequent recycling. Through 5 cycle tests ( Figure 7 )、GOr / MCH + The desorption performance of MDEA CO2-rich solution remains basically unchanged, indicating that it has a stable chemical structure.

[0053] Example 2

[0054] The operating process of this embodiment is different from that of embodiment 1 in that the chemical absorbent is monoethanolamine (MEA). Figure 8 As shown, MCH + / GOr can also desorb MEA CO2 rich solution under sunlight, and use MCH twice + / GOr desorption, the CO2 desorption rate (0.003 mmol / s) and CO2 desorption amount (15 mmol) of the desorbed MEA CO2 rich solution remained basically stable, proving that MCH + / GOr cycling stability.

[0055] Example 3 The operating process of this example is different from that of Example 1 in that the carbon-based material is carbon nanotubes, and the carbon-based metastable photoacid composite material is a carbon nanotube / metastable photoacid composite material.

[0056] Preparation of carbon nanotube / metastable photoacid composite materials:

[0057] 5 mg of the metastable photoacid prepared in Example 1 and 1 mL of a 5 mg / mL carbon nanotube dispersion were dissolved in 50 mL of deionized water and ultrasonicated for 30 minutes to obtain a carbon nanotube / metastable photoacid composite material (MCH + / CNT). Figure 9 As shown, (MCH + / CNT) can also desorb MDEA CO2-rich solution under sunlight irradiation. After irradiation for 8000 s, the CO2 desorption rate reaches a maximum value of 0.007 mmol / s.

Claims

1. A carbon-based metastable photoacid composite material, characterized in that: The composite material is composed of a carbon-based material and a metastable photoacid. The metastable photoacid molecule has a conjugated structure with a π bond and is adsorbed onto the surface of the carbon-based material through π-π superposition to form a carbon-based metastable photoacid composite material. The mass ratio of the carbon-based material to the metastable photoacid is 1:(1-30). The carbon-based material is at least one of carbon nanotubes, graphene, and carbon black. The metastable photoacid is at least one of a merocyanine metastable photoacid, an indazole metastable photoacid, and a tricyanofuran metastable photoacid. Their structural formulas are as follows: In the structural formula, R1, R2, and R3 are all one of H, OMe, OH, CHO, F, Cl, Br, and NO2.

2. The method for preparing the carbon-based metastable photoacid composite material according to claim 1, characterized in that: Includes the following: The metastable photoacid and the carbon-based material dispersion were added to a certain amount of water, stirred until the metastable photoacid was dissolved, and then ultrasonically treated for 30 to 60 minutes to obtain a carbon-based metastable photoacid composite material.

3. The method according to claim 2, characterized in that The carbon-based material dispersion is prepared by dispersing the carbon-based material in pure water or a mixed solvent of water and a water-soluble organic solvent; the mass concentration of the carbon-based material dispersion is 0.002% to 0.02%.

4. Use of the carbon-based metastable photoacid composite material according to claim 1 in carbon capture, utilization and storage.

5. The application according to claim 4, characterized in that: It is used in solar-driven CO2 capture.

6. The application according to claim 5, characterized in that: The application is to desorb CO2 rich liquid during the CO2 capture process based on the chemical absorption method of organic alcohol amine, thereby improving the quality and efficiency of CO2 rich liquid desorption and regenerating the chemical absorbent.

7. The method for capturing CO2 using the carbon-based metastable photoacid composite material under solar energy drive according to claim 1, characterized in that: The following steps are involved: Step 1: dissolving the carbon-based metastable photoacid composite material and the chemical absorbent in a pre-prepared mixed solvent of a physical solvent and water to obtain an absorbent solution, wherein the amount of the carbon-based metastable photoacid is 0.05 to 3.0 times the amount of the chemical absorbent; contacting the absorbent solution with a gas containing CO2 to absorb the CO2 and form a CO2-rich solution; Step 2: placing the CO2-rich solution in the above step under sunlight to promote rapid desorption of CO2, and obtaining a CO2-lean solution after desorption is completed; Step 3: After the desorption of CO2 is completed, the CO2-lean liquid is placed in a dark place to promote the regeneration of the chemical absorbent and the carbon-based metastable photoacid for subsequent recycling.

8. The method according to claim 7, characterized in that: The chemical absorbent is monoethanolamine, diethanolamine, N At least one of methyldiethanolamine, 2-amino-2-methyl-1-propanol, ethylenediamine, triethylamine, piperazine, ammonia water and potassium carbonate; the physical solvent is toluene, carbon tetrachloride, N,N - one or more of dimethylformamide, dimethyl sulfoxide, sulfolane and diethylene glycol dimethyl ether.

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