Dry water-type carbon dioxide absorbent with photothermal conversion properties, its preparation method and application

Abstract

This invention discloses a dry-water type carbon dioxide absorbent with photothermal conversion properties, its preparation method, and its application. The dry-water type carbon dioxide absorbent includes an encapsulation material and an organic amine solution encapsulated within the encapsulation material; the encapsulation material includes a hydrophobic material and a light-absorbing material. This absorbent is formed by adhering the hydrophobic and light-absorbing materials to the surface of the organic amine solution through a high-speed moving organic amine solution, thus encapsulating the organic amine solution to form dry-water type liquid beads. The dry-water type carbon dioxide absorbent provided by this invention absorbs and stores energy under sunlight, and performs carbon dioxide desorption and release, so that the desorption-induced heating does not require an additional heat source, reducing regeneration energy consumption.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide absorption and desorption technology, specifically to a dry water-type carbon dioxide absorbent with photothermal conversion properties, its preparation method, and its application. Background Technology

[0002] In the chemical field, carbon dioxide absorbents are mainly classified into solid absorbents and solvent absorbents. The primary mechanism of solid adsorption is through intermolecular forces. During diffusion, gas molecules exchange and share electrons or atoms with solid molecules, generating new forces that more stably fix the gas molecules to the absorbent surface. However, this also makes absorbent regeneration more difficult. Solvent absorbents, on the other hand, involve a chemical reaction between a liquid absorbent and CO2. Under certain conditions, the absorbent solution is desorbed, achieving both carbon dioxide separation and enrichment while simultaneously recycling the absorbent. This method is widely used in industry due to its suitability for capturing large quantities of carbon dioxide after combustion.

[0003] Currently, the main types of absorbents used in chemical absorption methods include organic amines, alkaline ionic liquids, and ammonia. Among these, organic amine absorbents are widely used due to their relatively high absorption rate and large absorption capacity. MEA was the earliest organic solvent used as a carbon dioxide absorbent, and its use has a history of over 50 years. Subsequently, MDEA, DEA, sterically hindered amine materials, polynitrogen-containing organic amines, and mixed organic amine solutions have all been introduced as CO2 absorbents.

[0004] However, regardless of the organic amine solution chosen, chemical absorption methods present numerous challenges. All amine desorption processes share the common problem of requiring substantial energy consumption, and different organic amines exhibit unique characteristics. For example, MEA solutions readily react with CO2, are easy to produce, and are inexpensive, but their biggest drawback is their relatively low CO2 absorption capacity. MDEA, while possessing good CO2 absorption capacity, suffers from a slow absorption rate. Mixing different amine components to compensate for each other's shortcomings makes it difficult to control their physicochemical properties, leading to problems such as high viscosity, volatility, and corrosivity. In summary, amine solvents possess inherent corrosivity and volatility, placing high demands on absorption equipment. Furthermore, the desorption and regeneration of all absorbents often require significant energy input, impacting the environment and increasing treatment costs.

[0005] The introduction of "dry water" materials provides a research approach to solving this problem. The fundamental advantage of dry water materials lies in their ability to solidify liquid materials. This allows dry water absorbents to retain the high absorption efficiency and large absorption capacity of liquid absorbents, while also possessing the advantages of solid absorbents such as ease of transportation and minimal environmental impact. Furthermore, the uniquely small particle size of dry water further increases the absorption area, thereby improving the absorption rate. Therefore, coating amine solutions with hydrophobic powder to create dry water powder can effectively solve the problems of absorbent evaporation and corrosion associated with traditional organic amine chemical solvent methods, but it cannot solve the energy consumption problem associated with desorption. Summary of the Invention

[0006] The technical problem to be solved by this invention is that carbon dioxide absorbents have high desorption and regeneration energy consumption. This invention provides a dry water-type carbon dioxide absorbent with photothermal conversion characteristics, its preparation method and application, which solves the above problem. The dry water-type carbon dioxide absorbent absorbs and stores energy under sunlight and performs carbon dioxide desorption and release, so that the heating desorption process does not require an additional heat source and reduces regeneration energy consumption.

[0007] This invention is achieved through the following technical solution:

[0008] A dry-water type carbon dioxide absorbent with photothermal conversion properties includes an encapsulation material and an organic amine solution encapsulated within the encapsulation material; the encapsulation material includes a hydrophobic material and a light-absorbing material.

[0009] Conventional dry-water materials effectively address the volatilization and corrosion issues of absorbents in traditional organic amine chemical solvent methods, but they cannot overcome the energy consumption problem associated with desorption. This application addresses this issue by modifying the coating material, functionalizing the dry-water coating material. Applying this concept to carbon dioxide desorption solves the problem of additional energy consumption by directly utilizing photothermal energy to achieve the heating desorption process. Photothermal desorption not only saves energy but also offers the advantage of temperature control. Therefore, developing a functionalized dry-water material with photothermal properties is of great significance for solving the problem of absorbent regeneration.

[0010] The organic amine solution under high-speed shearing adheres hydrophobic and light-absorbing materials to the liquid surface, encapsulating the organic amine solution to form a dry-water type liquid marble. It is a movable semi-encapsulated liquid marble that has good elasticity and fluidity at room temperature and pressure. The hydrophobic powder on the surface is in a single layer or multiple layers, which ensures the stability of the marble.

[0011] Further optionally, the organic amine solution is a single-component organic amine solution or a multi-component mixed organic amine solution prepared by having the number of active hydrogen atoms on the amino group being primary amine, secondary amine, or tertiary amine.

[0012] The internal organic amine solution in this invention can be selected according to application requirements, and its absorption and desorption operation temperature is in the range of 20°C to 80°C.

[0013] Further optionally, the organic amine solution includes at least one of primary amine monoethanolamine, N-(2-hydroxyethyl)ethylenediamine, secondary amine diethanolamine, N-(2-aminoethyl)-1,2-ethylenediamine, diethylenetriamine, and N-diethylethanolamine.

[0014] As a preferred method, the organic amine solution is at least one of the commonly used industrial organic amines such as primary amine monoethanolamine (MDEA), N-(2-hydroxyethyl)ethylenediamine (AEEA), secondary amine diethanolamine (DEA), N-(2-aminoethyl)-1,2-ethylenediamine, diethanoltriamine (DETA), and N-diethylethanolamine (DEEA), but the present invention is not limited to the scope of the examples above.

[0015] Further optionally, the hydrophobic material includes at least one of metal powder, metal oxide powder, inorganic non-metallic powder, and organic polymer powder;

[0016] And / or the light-absorbing material includes at least one of graphene powder, carbon nanotubes, and two-dimensional transition metal carbides (Mxene).

[0017] The size of the hydrophobic material powder of this invention can be nanometer-scale, micrometer-scale, millimeter-scale, etc. The shape of the hydrophobic material powder can be at least one of the following: flake-shaped, spherical, block-shaped, etc.

[0018] Further, alternatively, for hydrophobic materials,

[0019] The metal powder includes at least one of iron powder, copper powder, and gold powder;

[0020] The metal oxide powder includes at least one of iron oxide powder, copper oxide powder, and titanium dioxide powder;

[0021] The inorganic non-metallic powder includes at least one of silica powder, talc powder, mica powder, and kaolin.

[0022] The organic polymer powder includes at least one of polypropylene powder, polytetrafluoroethylene powder, polydimethylsiloxane, and polystyrene powder.

[0023] Further optionally, the concentration of the organic amine solution is 2wt% to 25wt%; the selection of the concentration of the organic amine solution is related to the specific type of organic amine used. For example, when using MDEA, the concentration of the organic amine solution is preferably 2wt% to 20wt%.

[0024] And / or the mass ratio of the hydrophobic micro / nano material to the organic amine solution is 1:5 to 1:20; the amount of hydrophobic micro / nano material and organic amine solution used is related to the concentration of the organic amine solution. For example, when using MDEA, the mass ratio of hydrophobic micro / nano material to organic amine solution is preferably 1:5 to 1:10.

[0025] And / or the amount of the light-absorbing material used is 0.5% to 1.5% of the mass of the organic amine solution. If MDEA is used and graphene is used as the light-absorbing material, the amount of the light-absorbing material used is 0.5% to 1% of the mass of the organic amine solution.

[0026] If the amount of hydrophobic material powder is too small, it will be difficult for the hydrophobic material powder and light-absorbing material to effectively cover the surface of the organic amine liquid, which will cause the organic amine solution to be exposed or overflow from the inside of the dry water type liquid marble.

[0027] Alternatively, the absorbent may be a dry-water type liquid marble with a particle size of less than 300 μm.

[0028] A method for preparing a dry-water type carbon dioxide absorbent with photothermal conversion properties involves adhering hydrophobic and light-absorbing materials to the surface of an organic amine solution via a high-speed moving organic amine solution, thereby encapsulating the organic amine solution to form dry-water type liquid marbles.

[0029] This invention relates to dry-water type liquid marbles formed by coating one or more hydrophobic material powders and light-absorbing materials onto the surface of an organic amine solution at high speed, or dry water formed by high-speed movement of single-component hydrophobic material particles and light-absorbing materials with an organic amine solution. The term "possessing photothermal conversion characteristics" refers to the fact that the encapsulation material on the surface of the prepared dry-water type liquid marbles can absorb heat and heat up with increasing external light intensity, reaching the desorption temperature of the internal organic amine solution, thus providing good thermal conductivity for photothermal conversion applications.

[0030] In this invention, the method for high-speed movement of organic amine solutions includes, but is not limited to, mechanical stirring, ball milling dispersion, gas stirring, etc.

[0031] Preferably, a mechanical stirring process is used to move the organic amine solution at high speed. There are no limitations on the equipment used for this mechanical stirring process; it can be a homogenizer, mixer, garlic maker, or soy milk maker, or a self-made device with stirring function. The mechanical stirring device should be modified to give its surface superhydrophobic properties to prevent the organic amine solution from leaking and adhering to the surface, making it difficult to coat the liquid droplets and shrink them into a dry, watery state. Furthermore, the internal surface of the mechanical stirring device (especially the stirring paddle) should have better corrosion resistance and wear resistance.

[0032] When using mechanical stirring, the high-speed movement can be set to a speed greater than 500 r / min and the stirring time can be maintained for more than 5 seconds. Then, light-absorbing materials are added and stirred for less than 5 seconds to produce a dry water-type carbon dioxide absorbent with photothermal conversion characteristics.

[0033] Further, optionally, the specific preparation steps include:

[0034] First, an organic amine solution and a hydrophobic material are mixed. The hydrophobic material is then adhered to the surface of the organic amine solution and encapsulated by the high-speed moving organic amine solution to form liquid marbles.

[0035] Then, light-absorbing materials are added, and the hydrophobic and light-absorbing materials are adhered to the surface of the organic amine solution by high-speed moving organic amine solution, thus encapsulating the organic amine solution to form dry-water type liquid marbles.

[0036] The application of the above-mentioned dry water-type carbon dioxide absorbent with photothermal conversion characteristics or the absorbent prepared by the above-mentioned method for preparing dry water-type carbon dioxide absorbent with photothermal conversion characteristics in the absorption and desorption of carbon dioxide.

[0037] The dry-water type carbon dioxide absorbent with photothermal conversion properties provided by this invention can be applied to the field of carbon dioxide absorption and desorption, achieving carbon dioxide absorption and low-energy desorption, while also enabling mass transfer. The carbon dioxide absorption field includes applications involving the absorption of carbon dioxide generated during organic matter decomposition and fermentation, fossil fuel combustion, chemical product processing, and the operation of large diesel machinery. The mass transfer substance can be not only water, but also at least one of hydrogen sulfide, carbon dioxide, gaseous oxides of sulfur, gaseous oxides of nitrogen, volatile organic compounds, and other gases, but this invention is not limited to the examples listed above. The gaseous oxides of sulfur include, but are not limited to, SO2 and SO3; the gaseous oxides of nitrogen include, but are not limited to, N2O, NO2, and N2O3; and the volatile organic compounds include, but are not limited to, formaldehyde and acetone.

[0038] The present invention has the following advantages and beneficial effects:

[0039] 1. The dry-water carbon dioxide absorbent with photothermal conversion properties provided by this invention is a dry-water carbon dioxide absorbent using micro-nano-scale hydrophobic powder as the encapsulation material and an organic amine solution as the core material. This dry-water carbon dioxide absorbent has a marble-like structure, and the micro-nano-scale hydrophobic powder on its surface can migrate and rearrange as the organic amine solution expands or contracts. When the organic amine solution shrinks, the powder on the surface of the liquid marble is densely arranged; when the organic amine solution expands, the powder on the surface of the liquid marble is loosely arranged; however, the surface powder can stably exist at the gas-liquid interface, preventing leakage, and it does not exhibit the plastic fatigue failure characteristic of traditional encapsulation materials.

[0040] 2. The dry water-type carbon dioxide absorbent with photothermal conversion characteristics provided by the present invention uses micro-nano-scale hydrophobic powder as the encapsulation material. Therefore, the dry water-type carbon dioxide absorbent with photothermal conversion characteristics is non-sticky and elastic, does not aggregate when it collides with each other, and can automatically recover its original shape after deformation.

[0041] 3. The dry water-type carbon dioxide absorbent with photothermal conversion characteristics provided by the present invention is a dry water-type liquid marble with micro-nano-scale hydrophobic powder as the encapsulation material. The liquid marble has a large specific surface area and the gas passes quickly across the liquid surface. Therefore, the liquid marble with this encapsulation method enhances the gas flow rate and thus improves the absorption efficiency compared with pure solvent bubbling absorption of carbon dioxide.

[0042] 4. The dry-water type carbon dioxide absorbent with photothermal conversion characteristics provided by this invention provides a broader absorption spectrum because the hydrophobic powder on the surface of the liquid beads uniformly coats the light-absorbing material. Therefore, it can absorb more energy under the same light intensity, achieving carbon dioxide desorption under solar radiation. The dry-water type carbon dioxide absorbent absorbs and stores energy under sunlight for carbon dioxide desorption and release, eliminating the need for an additional heat source during the heating and desorption process, thus reducing regeneration energy consumption.

[0043] 5. This invention uses micro-nano-scale hydrophobic powder and light-absorbing materials as encapsulation materials to achieve active semi-encapsulation of organic amine solutions, which is completely different from any existing carbon dioxide absorbent with photothermal properties, and provides a brand-new technical solution for solid encapsulation and desorption of carbon dioxide absorption and desorption. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0045] Figure 1 Schematic diagram of a carbon dioxide fixed-bed absorption device; attached. Figure 1 Chinese markings and corresponding component names:

[0046] 1-Nitrogen storage tank, 2-Carbon dioxide gas storage tank, 3-Iron mesh, 4-Absorbent, 5-Gas detector.

[0047] Figure 2 The images shown are the appearance and flow diagrams of the hydrophobically modified silica dried water coated with different masses of organic amine solution in Example 1; wherein, Figure 2 (a) 1:10, Figure 2 (b)1:12.5, Figure 2 (c)1:15, Figure 2 (d)1:17.5, Figure 2 (e)1:20, Figure 2 (f) 1:22.5, the above ratios are all mass ratios of hydrophobic silica to organic amine solution.

[0048] Figure 3 The images show the appearance and flow charts of the dry-water type carbon dioxide absorbent using different concentrations of core solution in Example 2; wherein,

[0049] Core solution MDEA concentration 2wt% absorbent: Figure 3 (a) Below 100μm, Figure 3 (b) 100μm~300μm, Figure 3 (c) 300μm or larger;

[0050] Core solution MDEA concentration 5wt% absorbent: Figure 3 (d) Below 100μm, Figure 3 (e) 100μm~300μm, Figure 3 (f) 300μm or larger;

[0051] The core solution contains 10 wt% MDEA as an absorbent. Figure 3 (g) Below 100μm, Figure 3 (h) 100μm~300μm, Figure 3 (i) 300 μm or more.

[0052] Figure 4 The images show the appearance and flow charts of the dry-water type carbon dioxide absorbent using different concentrations of core solution and different amounts of graphene added in Example 3; wherein,

[0053] Adding an absorbent with a core solution containing 2 wt% MDEA: Figure 4 (a) 0.5 wt% graphene, Figure 4 (b) 1 wt% graphene, Figure 4 (c) 1.5 wt% graphene;

[0054] Adding an absorbent with a core solution containing 5 wt% MDEA: Figure 4 (d) 0.5 wt% graphene, Figure 4 (e) 1 wt% graphene, Figure 4 (f) 1.5 wt% graphene;

[0055] Adding an absorbent with a core solution containing 10 wt% MDEA: Figure 4 (g) 0.5wt% graphene, Figure 4 (h) 1wt% graphene, Figure 4 (i) 1.5 wt% graphene.

[0056] Figure 5 The image shows the contact angle evaluation diagrams for different liquids on hydrophobically modified silica surfaces and graphene surfaces used in Example 4; wherein,

[0057] Contact angles of different liquids on the SiO2 surface: Figure 5 (a) water, Figure 5 (b) 2wt% MDEA solution, Figure 5 (c) 5wt% MDEA solution, Figure 5 (d) 10 wt% MDEA solution;

[0058] Contact angles of different liquids on graphene surfaces: Figure 5 (e) Water, Figure 5 (f) 2wt% MDEA solution, Figure 5 (g) 5wt% MDEA solution, Figure 5 (h) 10wt% MDEA solution.

[0059] Figure 6 Microscopic images of MDEA solutions of different concentrations under an electron microscope; where: Figure 6 (a) 2wt%, Figure 6 (b) 5wt%, Figure 6 (c) 10wt%, Figure 6 (d) 15wt%, Figure 6 (e) 20wt%, Figure 6 (f) 25wt%.

[0060] Figure 7 This is a graph showing the results of the carbon dioxide absorption process of different dry-water type carbon dioxide absorbents tested in Example 5; wherein: Figure 7 (a) shows the carbon dioxide absorption curves of different core solution absorbents. Figure 7 (b) shows the relationship between the average rate of carbon dioxide absorption and the concentration of the core solution. Figure 7 (c) represents the relationship between MDEA utilization efficiency and kernel solution concentration.

[0061] Figure 8 Photothermal curves (200 W / m²) of different dry-water type carbon dioxide absorbents tested in Example 6. 2 ); among them, for dry water-type carbon dioxide absorbent particles smaller than 100μm, the core solution MDEA concentration is: Figure 8 (a) 2wt%, Figure 8

[0062] (b) 5wt%, Figure 8 (c) 10 wt%;

[0063] Dry water-type carbon dioxide absorbent particles of 100μm~300μm, MDEA concentration in the core solution: Figure 8 (d) 2wt%,

[0064] Figure 8 (e) 5wt%, Figure 8 (f) 10 wt%;

[0065] Dry water-type carbon dioxide absorbent particles larger than 300μm, core solution MDEA concentration: Figure 8 (g) 2wt%, Figure 8 (h)

[0066] 5wt%, Figure 8 (i) 10wt%.

[0067] Figure 9 Examples 7 show the continuous absorption curves and performance graphs of different dry-water type carbon dioxide absorbents tested; among them,

[0068] Dry-type carbon dioxide absorbent granules with a core solution concentration of 2wt% MDEA: Figure 9 (a) Changes in the absorption curve Figure 9 (b) Changes in average absorption rate Figure 9 (c) Changes in MDEA utilization efficiency;

[0069] Dry-type carbon dioxide absorbent granules with a core solution concentration of 5 wt% MDEA: Figure 9 (d) Changes in the absorption curve Figure 9 (e) Changes in average absorption rate, Figure 9 (f) Changes in MDEA utilization efficiency;

[0070] Dry-type carbon dioxide absorbent granules with a core solution concentration of 10 wt% MDEA: Figure 9 (g) Changes in the absorption curve Figure 9 (h) Change in average absorption rate Figure 9 (i) MDEA utilizes efficiency changes.

[0071] Figure 10 The absorption curves are for the core solution in Example 8, which has a concentration of 5 wt% to 25 wt%.

[0072] Figure 11 This is a microscopic morphology diagram of the dry water-type solid absorbent of this application. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0074] Since the organic amine solutions used in the following examples are all polar, the micro / nano hydrophobic powders used in the following examples are non-polar hydrophobic powders.

[0075] In the following examples, N-methyldiethanolamine (MDEA) solution is used as a representative organic amine solution for dry-water type carbon dioxide absorbents with photothermal conversion properties. MDEA is added to deionized water to prepare a 2wt%–15wt% dilute amine solution.

[0076] The preparation method of hydrophobically modified nano-sized silica (hereinafter referred to as hydrophobically modified silica) in the following examples is as follows: A fluorosilane ethanol solution (concentration of 1 wt%) is mixed with silica powder (approximately 30 nm), and the volume ratio of the fluorosilane ethanol solution to the mass of the silica powder is 1:1 (the volume of the fluorosilane ethanol solution is in mL, and the mass of the silica powder is in g). The mixture is then placed in a centrifuge tube and the tube is closed. The centrifuge tube is shaken to ensure that the silica powder is completely immersed in the fluorosilane ethanol solution, and the modification is carried out for 12 hours. Then, solid-liquid separation is performed, the fluorosilane ethanol solution is removed, and the modified silica is placed in an oven at 80°C and dried for more than 12 hours.

[0077] All absorption experiments in the following examples were performed using a fixed-bed absorption tower device, such as... Figure 1 As shown in the figure, the inlet gas is a standard mixture of nitrogen and carbon dioxide with a concentration ratio of 3:1 (flux ratio 300 ml / min: 100 ml / min). The absorption performance of the dry water can be evaluated by analyzing the changes in carbon dioxide concentration and subsequent calculation results.

[0078] Example 1

[0079] This embodiment provides a dry-water type carbon dioxide absorbent with photothermal conversion properties. The absorbent is encapsulated using hydrophobically modified silica powder as the coating material, and different masses of 5wt% MDEA aqueous solution are used as the core. The specific preparation steps are as follows:

[0080] Step 1: Place 1g of hydrophobic modified silica into a mechanical stirrer, and then add 10g, 12.5g, 15g, 17.5g, 20g, and 22.5g of 5wt% MDEA aqueous solution respectively.

[0081] Step 2: Hydrophobically modified silica and different masses of 5wt% MDEA aqueous solution are subjected to high-speed mechanical stirring in a mechanical stirring device to form liquid marbles.

[0082] Step 3: The liquid marbles formed in Step 2 are relatively large. Repeating Step 2 3-5 times can make the hydrophobically modified silica more uniformly coat the surface of the MDEA aqueous solution, forming smaller liquid marbles and better-performing dry-water type liquid marbles, such as... Figure 2 As shown.

[0083] The repeated stirring of the liquid marbles in step 3 can also be controlled by changing the rotation speed to prevent the liquid marbles from adhering and agglomerating due to intermittent operation. Comparison revealed that adding 10g of a 5wt% MDEA aqueous solution resulted in the most stable coating structure, which will be used as a reference for subsequent embodiments.

[0084] Example 2

[0085] This embodiment provides a dry-water type carbon dioxide absorbent with photothermal conversion properties. The absorbent is encapsulated using hydrophobically modified silica powder as the coating material, and different concentrations of 10g MDEA aqueous solution are used as the core. The specific preparation steps are as follows:

[0086] Step 1: Place 1g of hydrophobic modified silica into a mechanical stirrer, and then add 10g of 2wt%, 5wt%, and 10wt% MDEA aqueous solutions respectively.

[0087] Step 2: Add hydrophobically modified silica and MDEA aqueous solutions of different concentrations to a mechanical stirring device and perform high-speed mechanical stirring to form liquid marbles.

[0088] Step 3: The liquid marbles formed in Step 2 are relatively large. Repeating Step 2 3-5 times can make the hydrophobic modified silica more uniformly coated on the surface of the MDEA aqueous solution to form smaller liquid marbles and better-performing dry-water type liquid marbles.

[0089] Step 4: The liquid marbles prepared in Step 3 have the "dry water properties". Continue to mechanically stir 0.1g of light-absorbing material graphene and the prepared dry water type liquid marbles to obtain black dry water type liquid marbles.

[0090] Step 5: The black, dry-water liquid marbles prepared in Step 4 were sieved using metal sieves of different mesh sizes, resulting in three different particle size distributions of the dry-water liquid marbles, such as... Figure 3 As shown.

[0091] The black dry-water type liquid marbles in step 4 have good light absorption properties, which can promote the carbon dioxide desorption process. By sieving, dry-water type liquid marbles of the same particle size can be classified, which is more conducive to the gas absorption process.

[0092] Example 3

[0093] This embodiment provides a dry-water type carbon dioxide absorbent with photothermal conversion properties. The absorbent is encapsulated using hydrophobically modified silica powder as the coating material, and different concentrations of 10g MDEA aqueous solution are used as the core, with different masses of graphene added as the light-absorbing material. The specific preparation steps are as follows:

[0094] Step 1: Place 1g of hydrophobic modified silica into a mechanical stirrer, and then add 10g of 2wt%, 5wt%, and 10wt% MDEA aqueous solutions respectively.

[0095] Step 2: After adding hydrophobically modified silica and MDEA aqueous solutions of different concentrations into the stirring device, mechanical stirring is performed to form liquid marbles.

[0096] Step 3: The liquid marbles formed in Step 2 are relatively large. Repeating Step 2 3-5 times can make the hydrophobic modified silica more uniformly coated on the surface of the MDEA aqueous solution to form smaller liquid marbles and better-performing dry-water type liquid marbles.

[0097] Step 4: The dry-water type liquid marbles prepared in Step 3 already possess the "dry-water properties". Continue to mechanically stir 0.05g, 0.1g, and 0.15g of light-absorbing material graphene and the prepared dry-water type liquid marbles to obtain black dry-water type liquid marbles.

[0098] Step 5: The dried water-type liquid marbles prepared in Step 4 are sieved using metal sieves of different mesh sizes. Black dried water-type liquid marbles with a mesh size greater than 300 micrometers are selected as a control. Figure 4 As shown.

[0099] The black dry-water marbles in step 4 have good light absorption properties, which can promote the carbon dioxide desorption process. By adjusting the proportion of graphene, we can prevent excessive graphene from causing poor coating effect of silicon dioxide, which would ultimately lead to the adhesion and aggregation of liquid marbles.

[0100] Example 4

[0101] This embodiment uses hydrophobically modified silica and graphene as encapsulating materials for the powder, and deionized water and MDEA aqueous solutions of different concentrations (2wt%-25wt%) as the core, respectively, to observe static contact angle changes and microscopic images under a scanning electron microscope. The specific steps are as follows:

[0102] Step 1: Nanoscale hydrophobic modified silica and graphene are uniformly coated on the surface of a clean glass slide to prepare a hydrophobic substrate with single micro- and nano-particles.

[0103] Step 2: Deionized water and MDEA aqueous solutions of different concentrations are dropped onto the surface of hydrophobic modified silica substrate and graphene hydrophobic substrate, respectively.

[0104] Step 3: Use a contact angle meter to measure the contact angles of deionized water and MDEA aqueous solutions of different concentrations on different substrate surfaces to evaluate the hydrophobic effect, such as... Figure 5 As shown.

[0105] Step 4: Using a scanning electron microscope, observe the microstructure of the dried water prepared at kernel MDEA concentrations of 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, and 25wt%, respectively. Figure 6 As shown.

[0106] The hydrophobic powder spread in step 1 can be replaced with hydrophobic modified silica powder of different particle sizes, such as micron-sized hydrophobic modified silica powder with larger particle sizes.

[0107] In step 2, deionized water and MDEA aqueous solutions of different concentrations should be collected using a 10 μL pipette to prevent excessive liquid from damaging the surface structure of the hydrophobic substrate.

[0108] For the dry water-type carbon dioxide solid adsorbent in step 4, it is placed in an oven or freeze dryer beforehand to remove the core solution to avoid damage to the electron microscope lens in the vacuum environment. Therefore, the microstructure of the sample collapses slightly.

[0109] Example 5

[0110] This embodiment tests the absorption rate and utilization rate of the dry water-type carbon dioxide absorbent (particle size 100μm-300μm) prepared in Example 2, using methods such as... Figure 1 The equipment shown was tested. The inlet gas consisted of a standard mixture of nitrogen and carbon dioxide at a concentration ratio of 3:1 (flux ratio 300 ml / min: 100 ml / min). The changes in carbon dioxide concentration at the outlet and subsequent calculation results were analyzed. The specific testing procedures are as follows:

[0111] Step 1: Before the experiment begins, continuously introduce standard gas (nitrogen: carbon dioxide = 3:1) at a rate of 400 mL / min into the fixed-bed absorption tower without absorbent to purge the existing air.

[0112] Step 2: Add dry-water type liquid beads with MDEA concentrations of 2wt%, 5wt%, and 10wt% to the fixed-bed absorber, i.e., the dry-water type carbon dioxide absorbent prepared in Example 2. The carbon dioxide concentration will change after the standard gas passes through the dry-water type liquid beads.

[0113] Step 3: Use a tail gas analyzer to measure the change in carbon dioxide concentration at the outlet gas, and calculate the carbon dioxide absorption rate and absorption efficiency, such as... Figure 7 As shown.

[0114] The absorption rate and absorption saturation in step 3 are calculated using the following formulas:

[0115]

[0116]

[0117] V total and t total These represent the total volume and total time of carbon dioxide absorption during the absorption process (i.e., the stage where the carbon dioxide concentration in the exhaust gas is less than 25%). And mol CO2 and mol MDEA These refer to the amount of carbon dioxide absorbed and the amount of MDEA in the absorbent, respectively. These two indicators reflect the absorption rate of the absorbent and the utilization efficiency of MDEA.

[0118] Example 6

[0119] This embodiment tests the photothermal conversion performance of the dry water-type carbon dioxide absorbent (particle size 100μm-300μm) prepared in Example 3, using a xenon lamp source (light intensity 200W / m²). 2 The light and heat are increased by irradiation, and the photothermal changes are measured, such as... Figure 8 As shown.

[0120] The amount of graphene added directly affects the rate of temperature rise and the maximum temperature of dry water under light. The higher the graphene content in the coating material, the stronger the absorbent's ability to absorb light energy and convert it into heat energy.

[0121] Example 7

[0122] This embodiment tests the recycling performance of the dry water-type carbon dioxide absorbent (particle size 100μm-300μm) prepared in Example 2, using the following method: Figure 1 The device shown was used for adsorption testing. In this embodiment, the gas at the inlet was a standard gas mixture of nitrogen and carbon dioxide with a concentration ratio of 3:1 (flux ratio 300 ml / min: 100 ml / min). The change in carbon dioxide concentration at the outlet and subsequent calculation results were analyzed. After absorption, a xenon lamp source (light intensity 200 W / m²) was used. 2 As a light source for desorbing carbon dioxide, the liquid beads (i.e., dry-water carbon dioxide absorbent) are heated by light to desorb carbon dioxide. The specific steps are as follows:

[0123] Step 1: Before the experiment begins, continuously introduce standard gas (nitrogen: carbon dioxide = 3:1) at a rate of 400 mL / min into the fixed-bed absorption tower without absorbent to purge the existing air.

[0124] Step 2: Add dry water type liquid beads with MDEA concentrations of 2wt%, 5wt%, and 10wt% to the fixed bed absorption tower, which is the dry water type carbon dioxide absorbent prepared in Example 2. After the standard gas passes through the dry water type liquid beads, the carbon dioxide concentration will change.

[0125] Step 3: Use a tail gas analyzer to measure the change in carbon dioxide concentration at the outlet and calculate the carbon dioxide absorption rate and absorption efficiency.

[0126] Step 4: Place the dry-water type liquid marbles, after absorbing carbon dioxide, into a xenon lamp source (light intensity 200W / m²). 2 Desorption was performed, and the desorbed dry water-type liquid marbles were put back into the self-made fixed bed absorption tower. The tail gas analysis device was used again to measure the change in carbon dioxide concentration at the outlet gas, and the carbon dioxide absorption rate and absorption efficiency were calculated.

[0127] Step 5: Repeat step 4 2-3 times, and observe the changing trends of the absorption rate and absorption efficiency of the desorbed water-type liquid marbles. Figure 9 As shown.

[0128] Example 8

[0129] This embodiment adjusts the experimental environment of the dry-water type carbon dioxide absorbent (particle size 100μm-300μm) prepared in Example 4 to test its utilization performance under simulated flue gas (15% CO2). The following methods are employed: Figure 1 The device shown was used for adsorption testing. In this embodiment, the gas at the inlet was a mixture of nitrogen and carbon dioxide standard gas with a concentration ratio of 3:1 (flux ratio of 300 ml / min: 100 ml / min). The changes in carbon dioxide concentration at the outlet and the subsequent calculation results were analyzed.

[0130] Step 1: Before the experiment begins, continuously introduce standard gas (nitrogen: carbon dioxide = 3:1) at a rate of 400 mL / min into the fixed-bed absorption tower without absorbent to purge the existing air.

[0131] Step 2: Add dry water type liquid beads with an MDEA concentration of 5wt%-25wt% to the fixed bed absorption tower, which is the dry water type carbon dioxide absorbent prepared in Example 4. After the standard gas passes through the dry water type liquid beads, the carbon dioxide concentration will change.

[0132] Step 3: Use a tail gas analyzer to measure the change in carbon dioxide concentration at the outlet and calculate the carbon dioxide absorption rate, such as... Figure 10 As shown.

[0133] I. Structural Analysis

[0134] Images were acquired of the dry-water type carbon dioxide absorbents prepared in Examples 1-3, and the resulting photographs are shown below. Figures 2-4 As shown in the figure, the dry water-type carbon dioxide solid absorbent with photothermal conversion characteristics provided by the present invention exists in the form of black dry water-type liquid marbles after preparation, and has good mechanical stability and flowability.

[0135] II. Performance Analysis

[0136] 1. Wetting analysis of encapsulated powder

[0137] Example 4 conducted a preliminary experiment on the wettability of the materials before absorbent preparation to explore the importance of the encapsulation material characteristics for absorbent selection. In the experiments of this invention, the encapsulation materials were mainly graphene and hydrophobically modified silica. The surface composed of hydrophobically modified silica showed better hydrophobicity than the surface composed of graphene, which can be demonstrated by comparing the contact angles. Figure 5 (a) and Figure 5 (e)). Simultaneously, with the increase of MDEA concentration in the core absorbent, the contact angle of the silica substrate ( Figure 5 (b)- Figure 5 (d)) and graphene substrate ( Figure 5 (f)- Figure 5 The contact angle of MDEA (h) decreases. This is because the polarity of MDEA solution is different from that of water and the viscosity of MDEA solution is relatively high, resulting in the contact angle of MDEA being smaller than that of water on both hydrophobic substrates.

[0138] As can be seen from the above analysis, the dry water-type solid carbon dioxide absorbent with photothermal conversion characteristics provided by the present invention uses a good hydrophobic coating material, which is not easily miscible with MDEA aqueous solution, thus ensuring the long-term usability of the shell.

[0139] 2. Stability Analysis

[0140] (1) The amount of organic amine solution was varied in the preparation process of Example 1 to adjust the mass ratio of hydrophobic modified silica in the absorbent, thereby exploring the effect of the overall coating ratio of the absorbent on the mechanical properties. Using 5wt% MDEA aqueous solution as the coating core, dry water-type liquid marbles with a solid-liquid mass ratio (i.e., the mass ratio of hydrophobic modified silica to organic amine solution) of 1:10 to 1:22.5 were prepared, which are dry water-type carbon dioxide absorbents.

[0141] The results are as follows Figure 2 As shown, with the decrease in the proportion of hydrophobic modified silica, the dry-water type liquid marbles gradually exhibited agglomeration. When the mass ratio was 1:10, the dry-water type liquid marbles presented as a powder with good dispersibility and flowability; when the mass ratio decreased to 1:22.5, a large number of agglomerated particles and some slurry-like substances appeared (indicating insufficient coating), and the mobile phase also decreased significantly. This indicates that the coating of liquids by nano-hydrophobic silica has a certain range and limit. Exceeding this limit will lead to phenomena such as liquid leakage and particle agglomeration, as... Figure 2 As shown. Due to the larger surface area, better stability, and better flowability of the powdered structure, this invention determined the optimal coating ratio by controlling the ratio of the coating material to the core solution. It is worth noting that the content of hydrophobically modified silica should not be too high, as excessive hydrophobically modified silica will lead to over-coating and thus waste of material.

[0142] (2) Example 2 shows the changes in particle size of different dry water type liquid marbles, i.e. dry water type carbon dioxide absorbents, as the concentration of MDEA in the core solution increases.

[0143] Figure 3 The results showed that when the concentration of the core solution increased from 2 wt% to 10 wt%, the morphology of small dry-water liquid marbles (below 300 μm) did not change significantly and maintained good flowability. Among them, dry-water liquid marbles below 100 μm were in powder form due to their small particle size. Large dry-water liquid marbles above 300 μm, at an MDEA concentration of 2 wt%, still exhibited a relatively uniform particle size. Figure 3 (a)-Figure (c)). However, when the solution concentration was increased to 10 wt%, aggregated particles and incompletely coated droplets appeared, such as... Figure 3 (g)- Figure 3 As shown in (i), this indicates that at lower MDEA concentrations, the coating material can completely coat the solution into particulate matter, although the particle size will vary. However, when the MDEA concentration increases to the point that the coating material can no longer completely coat an equal amount of solution, the excess solution will form aggregated particles or exist directly as slurry droplets.

[0144] (3) Example 3 demonstrates the effect of graphene variations in the coating material on the morphology of the dry-water carbon dioxide absorbent. Increased graphene content leads to the formation of large aggregated particles and slurry droplets, as well as decreased flowability and stability. This effect becomes more pronounced with increasing MDEA concentration in the core solution. When the MDEA concentration in the core solution is 2 wt%, the increase in graphene has almost no effect on the morphology of the dry water. However, when the MDEA concentration in the core solution is increased to 10 wt% and graphene is added at 1.5 wt%, the dry water becomes almost entirely a slurry liquid, no longer exhibiting a particle or powder state, such as... Figure 4 As shown. To further increase the concentration of core MDEA (greater than 10 wt%), the coating mass ratio can be increased from 1:10 to 1:5 to obtain a dry-water type solid adsorbent, such as... Figure 6 As shown.

[0145] The above analysis shows that the main factors affecting the dry-type liquid marbles and their functionalization include: core solution concentration, overall coating ratio, and graphene ratio. A difference in polarity (different contact angles) between the coating material and the core solution necessitates a suitable mass ratio to form a powder or granular structure with both good stability and flowability. Increasing the core solution concentration and the amount of graphene added effectively reduces this polarity difference.

[0146] 3. Analysis of carbon dioxide absorption performance

[0147] Example 5 was used to analyze the carbon dioxide absorption of the dry-water type carbon dioxide absorbent obtained in Example 2. The test and analysis results are as follows: Figure 7 As shown. The concentration of MDEA in the core solution is the most direct factor affecting the dry water absorption performance. From a kinetic perspective, increasing the concentration of the core solution directly increases the concentration of the reactants. Therefore, a higher concentration of MDEA not only means a faster carbon dioxide absorption rate, but also increases the maximum dry water absorption capacity at the same stacking height. In this experiment, dry water-type carbon dioxide absorbents with core solution concentrations of 2 wt%, 5 wt%, and 10 wt% were selected for absorption testing (1:10 coating ratio, 100 μm–300 μm, 1 wt% graphene addition). From the absorption curves ( Figure 7 (a) As the concentration of the core solution increases, the absorption curve gradually shifts downward, and the absorption time also increases accordingly. The average absorption rate of carbon dioxide and the utilization efficiency of MDEA show an approximately linear increase with increasing MDEA water concentration. Figure 7 (b), Figure 7 (c) Further increasing the MDEA concentration can result in even better absorption, such as... Figure 10 As shown.

[0148] The above analysis shows that the core solution concentration is the main factor affecting the absorption performance of dry-type carbon dioxide absorbents. Increasing the core solution concentration will significantly improve the absorption rate, absorption efficiency, and absorption capacity of dry-type carbon dioxide absorbents.

[0149] 4. Photothermal desorption performance analysis

[0150] The photothermal conversion performance of the dry water-type carbon dioxide solid absorbent with photothermal conversion characteristics obtained in Example 3 was evaluated.

[0151] The amount of graphene added directly affects the heating rate and maximum temperature of water-based liquid marbles under light irradiation, and the particle size also influences the heating rate and maximum temperature. For water-based liquid marble particles with a particle size of 100μm to 300μm, their photothermal curves exhibit a relatively flat range before reaching the maximum temperature. This is because their higher graphene content allows for higher achievable temperatures, but the relatively small irradiated area limits the heating rate. The maximum temperature range achievable by water-based liquid marble particles smaller than 100μm is 55℃ to 75℃, while the maximum temperature range for particles between 100μm and 300μm is 50℃ to 65℃. However, the maximum temperature for particles larger than 300μm does not exceed 45℃. Since the absorption reaction of MDEA reverses above 50℃, water-based liquid marble particles larger than 300μm exhibit photothermal desorption capabilities. Figure 8 As shown.

[0152] The above analysis shows that the amount of graphene added and the particle size of the dry-water liquid marbles are the most important factors affecting the photothermal performance of the dry-water type, and the photothermal curves of the liquid marbles generally exhibit a logarithmic shape. Generally speaking, dry-water liquid particles with a particle size below 300 μm can meet the requirements for automatic photothermal desorption under sunlight intensity. However, the concentration of the core solution has no significant effect on improving the photothermal performance of the dry-water liquid marbles.

[0153] 5. Performance analysis of recycling after photothermal desorption

[0154] The desorption and regeneration performance of the dry-water type carbon dioxide absorbent obtained in Example 2 was evaluated as shown in Example 7. By directly heating to simulate a photothermal environment, two thermal desorption processes were performed on dry-water type liquid marble particles of different concentrations (coating ratio 1:10, 1 wt% graphene addition, particle size of dry-water type liquid marbles 100 μm to 300 μm) to determine their recyclability.

[0155] The results are as follows Figure 9As shown. Although the CO2 absorption performance of dry-water type liquid marbles decreases with increasing desorption cycles, the decrease is not significant. Even after two thermal desorption cycles, the utilization efficiency of MDEA is still higher than that of the traditional method (0.5 mol). CO2 / mol MDEA Approximately [value missing]. As the concentration of the core solution increases, the absorption performance of photothermal desorption for dry-type liquid marbles decreases significantly. This is because high-concentration alkanolamine solutions are more volatile, releasing more alkanolamines during thermal desorption. Furthermore, the decrease in absorption performance after the second thermal desorption is smaller than the first, also due to the decrease in the concentration of alkanolamines in the core solution, resulting in reduced volatilization.

[0156] The above analysis shows that the absorption performance of the dry water-type liquid marbles does not decrease significantly after thermal desorption, and it still has a relatively good ability to recycle and absorb carbon dioxide.

[0157] In summary, the dry-water type carbon dioxide absorbent with photothermal conversion characteristics provided by this invention has good mass transfer properties and can be used as a medium for carbon dioxide recovery in fossil fuel combustion processes. At the same time, it can absorb carbon dioxide generated in organic matter decomposition and fermentation, chemical product processing, and large diesel machinery operation, which meets the development needs of low-carbon and environmental protection.

[0158] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dry water type carbon dioxide absorbent having a photo-thermal conversion property, characterized by, The encapsulating material and the organic amine solution encapsulated in the encapsulating material; The encapsulating material comprises a hydrophobic material and a light-absorbing material; The hydrophobic material is hydrophobically modified silica, and the light-absorbing material is graphene. The organic amine solution is a single-component or multi-component mixed organic amine solution prepared from primary amines, secondary amines, and tertiary amines with a number of active hydrogen atoms on the amino group.

2. The dry aqueous carbon dioxide absorbent having light-to-heat conversion properties according to claim 1, wherein, The organic amine solution comprises at least one of monoethanolamine, N-(2-hydroxyethyl)ethylenediamine, diethanolamine, N-(2-aminoethyl)-1,2-ethylenediamine, diethylenetriamine, and N-diethyl ethanolamine.

3. The dry aqueous carbon dioxide absorbent having light-to-heat conversion properties according to claim 2, wherein, The concentration of the organic amine solution is 2wt%-25wt%, and / or the mass ratio of the hydrophobic material to the organic amine solution is 1:5-1:20, and / or the amount of the light-absorbing material is 0.5%-1.5% of the mass of the organic amine solution.

4. The dry aqueous carbon dioxide absorbent having a photothermal conversion property according to claim 1, characterized by, The absorbent is a dry water type liquid bead with a particle size of 300μm or less.

5. The dry aqueous carbon dioxide absorbent having photothermal conversion properties according to claim 1, wherein The hydrophobic material and the light-absorbing material are adhered to the surface of the organic amine solution and encapsulate the organic amine solution to form a dry water type liquid bead by moving the organic amine solution through high-speed shearing; the hydrophobic material is hydrophobically modified silica, and the light-absorbing material is graphene.

6. A method for preparing a dry water type carbon dioxide absorbent having a photo-thermal conversion property, characterized by, First, the organic amine solution and the hydrophobic material are mixed, and the hydrophobic material is adhered to the surface of the organic amine solution and encapsulates the organic amine solution to form a liquid bead by moving the organic amine solution through high-speed shearing; then, the light-absorbing material is added, and the hydrophobic material and the light-absorbing material are adhered to the surface of the organic amine solution and encapsulate the organic amine solution to form a dry water type liquid bead by moving the organic amine solution through high-speed shearing.

7. The method for preparing a dry-water type carbon dioxide absorbent with photothermal conversion characteristics according to claim 6, characterized in that, 8. The use of the absorbent prepared by the method of any one of claims 1-5 or 6-7 in the absorption and desorption of carbon dioxide. ​

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