Carbon dioxide capture microcapsule and preparation method thereof

Abstract

The invention discloses a carbon dioxide capture microcapsule and a preparation method thereof, and relates to the technical field of carbon dioxide capture, and the preparation method comprises the following steps: respectively inputting an internal phase fluid, a middle phase fluid and an external phase fluid into a microfluidic needle tube to generate liquid drops, and carrying out thermocuring on the liquid drops in the microfluidic needle tube in water at a specific temperature for a period of time to prepare the microcapsule, wherein the internal phase fluid comprises a sodium carbonate solution, the middle phase fluid comprises a shell material, the shell material is a mixed liquid of polydimethylsiloxane and a cross-linking agent, and the external phase fluid comprises a surfactant; the raw material solutions adopted by the invention are simple and easy to obtain and low in cost, and compared with a conventional method that a shell needs to be cured through ultraviolet rays during capsule preparation, the modified thermosetting material is higher in heat resistance, so that the prepared microcapsule is better in high temperature resistance and acid and alkali resistance.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, specifically a carbon dioxide capture microcapsule and its preparation method. Background Technology

[0002] With the development of modern industry, global energy consumption has been continuously increasing, especially the dramatic increase in the consumption of fossil fuels, primarily coal, oil, and natural gas. The massive emissions of CO2 accelerate the "greenhouse effect," exacerbating global warming, and severely disrupting the ecological balance, causing a series of ecological and environmental problems, thus posing a great threat to people's lives and production worldwide. Carbon dioxide is also an important carbon resource; it can be used as a raw material in the synthesis of organic matter, as an aid in the extraction of oil and natural gas, and as an extractant in supercritical conditions to extract many organic compounds. However, how to separate, recover, and utilize the CO2 generated during the combustion of fossil fuels and petrochemical production is a strategic issue of great concern to countries worldwide, aligning with current requirements for environmental governance and green development.

[0003] CO2 capture methods mainly include pre-combustion capture, in-combustion capture, and post-combustion capture. Post-combustion capture refers to capturing CO2 from the flue gas emitted from the combustion equipment outlet through separation technology. It is considered an important emission reduction technology with scalability potential, relatively low economic cost, relatively mature technology, and minimal impact on existing industrial facilities. Post-combustion capture technologies mainly include chemical absorption, adsorption, and membrane separation, with chemical absorption being the most widely used. Chemical absorption typically uses organic amine solutions as absorbents. The flue gas comes into close contact with the organic amine solution, utilizing the weak alkalinity of the solution to selectively absorb weakly acidic gases such as CO2 and H2S in the waste gas. Subsequently, a regeneration process is used to collect CO2 and recover the absorbent. Chemical absorption has advantages such as mature technology, wide application, compact equipment, and high selectivity. However, its drawbacks, such as high energy consumption for absorbent regeneration, easy volatility or decomposition, high viscosity, and corrosiveness, are technical bottlenecks that are difficult to overcome and hinder its further development. Summary of the Invention

[0004] In view of this, the present invention proposes a carbon dioxide capture microcapsule and its preparation method. A CO2-permeable polymeric material is used as the outer shell to encapsulate a liquid absorbent inside the shell, thereby obtaining a microcapsule with CO2 capture effect. It can be cyclically used for carbon dioxide absorption and desorption multiple times, and has low production cost, high reliability, and high production efficiency.

[0005] This invention discloses a method for preparing carbon dioxide capture microcapsules, comprising the following steps: The inner phase fluid, middle phase fluid, and outer phase fluid are respectively introduced into a microfluidic needle to generate droplets. The droplets in the microfluidic needle are then thermo-cured at 45~120℃ for 10~30 min to obtain microcapsules. The internal phase fluid includes a sodium carbonate solution; The intermediate phase fluid includes a shell material, which is a mixture of polydimethylsiloxane and a crosslinking agent. The crosslinking agent is one of borosilicate or alkyne-terminated polysilsesquioxane, and the amount of crosslinking agent added is 1-10% of the polydimethylsiloxane by mass fraction. External phase fluids include surfactants.

[0006] One embodiment of the present invention is that the surfactant is one or more of tetraethoxysilane, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, Pluronic F-127, Pluronic F-108, and polyvinyl alcohol.

[0007] One embodiment of the present invention is that the alkynyl-terminated polysilsesquioxane is a monoalkynyl-terminated cage-type polysilsesquioxane with a molecular weight range of 800~1500 g / mol.

[0008] One embodiment of the present invention is that the borosilicate crosslinking agent is one of methyl polysiloxane, boric acid modified hydrogen-containing silicone oil, and triisopropanolamine cycloboronic acid ester.

[0009] In one embodiment of the present invention, the concentration of the sodium carbonate solution is 5-30 wt%; the internal phase fluid is composed of a mixture of sodium carbonate solution and thymol blue indicator, wherein the amount of thymol blue indicator added to each 50 ml sodium carbonate solution is 6-7 drops.

[0010] Adding an acid-base indicator to the liquid adsorption core of the microcapsule causes the unloaded internal phase to exhibit a specific color. When the maximum carbon absorption is reached, the color changes. This color change can be used as an effective colorimetric indicator of CO2 saturation for liquid carbonate adsorbents.

[0011] One embodiment of the present invention is that the microfluidic needle tube includes a first dispensing needle, a second dispensing needle, a third dispensing needle, a T-shaped tee, a male Luer connector, and a four-way cross-connector. The tip of the first dispensing needle is inserted into one set of coaxial through holes in the T-shaped tee, the other set of coaxial through holes in the T-shaped tee is connected to the male Luer connector, the male Luer connector is connected to the tail of the second dispensing needle, the tip of the second dispensing needle is inserted into the four-way cross-connector, and the through hole on the opposite side of the four-way cross-connector coaxial with the second dispensing needle is connected to the tail of the third dispensing needle.

[0012] The structure of the microfluidic needle can be referenced from the structure of the microfluidic device disclosed in Chinese Patent CN202310062567.0. In this invention, the first dispensing needle can correspond to the first microchannel in the reference patent, the second dispensing needle can correspond to the second microchannel in the reference patent, the third dispensing needle can correspond to the third microchannel in the reference patent, the T-shaped tee can correspond to the T-shaped tube in the reference patent, the male Luer connector can correspond to the second male Luer connector in the reference patent, and the four-way cross-connection can correspond to the cross-connecting tube in the reference patent.

[0013] Furthermore, the dimensions of the first dispensing needle are as follows: length 2.0 inches, needle diameter 30G, inner diameter 0.16mm, outer diameter 0.31mm; the dimensions of the second dispensing needle are as follows: length 0.5 inches, needle diameter 23G, inner diameter 0.39mm, outer diameter 0.63mm; and the dimensions of the third dispensing needle are as follows: length 0.25 inches, needle diameter 19G, inner diameter 0.84mm, outer diameter 1.08mm.

[0014] Furthermore, the dimensions of the T-shaped tee are: length 20mm, inner diameter 1.0mm, outer diameter 1.6mm; the dimensions of the male Luer connector are: length 14mm, inner diameter 1.0mm, outer diameter 1.6mm; and the dimensions of the cross-linked four-way connector are: length 15.2mm, inner diameter 1.0mm, outer diameter 1.6mm.

[0015] Furthermore, the inner phase fluid is injected into the microfluidic needle tube through the tail of the first dispensing needle at a flow rate of 5~30 μL / min; the middle phase fluid is injected into the microfluidic needle tube through the non-coaxial side through-hole of the T-shaped tee at a flow rate of 5~30 μL / min; and the outer phase fluid is injected into the microfluidic needle tube perpendicularly to the inner phase fluid through the two sets of side holes of the four-way cross-linked tee at a flow rate of 150~220 μL / min.

[0016] And carbon dioxide capture microcapsules prepared using the above method.

[0017] The technical advantages of this invention are as follows: 1. The raw material solutions used in this invention are simple, readily available, and inexpensive. Furthermore, the modified polydimethylsiloxane curing material is used as the outer shell material. Compared to conventional capsule preparation which requires UV curing of the outer shell, this invention does not require the addition of lipophilic stabilizers to prevent agglomeration before curing. Moreover, the modified thermosetting material has stronger heat resistance, resulting in microcapsules with better high-temperature resistance and acid and alkali resistance.

[0018] 2. This invention employs a production apparatus assembled from distribution needles of 30g internal phase, 23g intermediate phase, and 19g external phase, enabling the prepared capsule droplet core droplet diameter to reach 600 micrometers. This effectively controls the droplet size and achieves a high degree of monodispersity. 3. The preparation device used in this invention is formed by combining dispensing needles and syringes of different sizes. The materials are readily available, the cost is low, and it is easy to clean and reusable. Attached Figure Description

[0019] Figure 1 Images showing the surface morphology of the carbon dioxide capture microcapsules in this invention; Figure 2 This is a diagram showing the particle size distribution of the carbon dioxide capture microcapsules in this invention. Figure 3 This is a diagram showing the results of the swelling experiment of carbon dioxide capture microcapsules in sodium carbonate solution in this invention; Figure 4 Image a shows the microscopic results of the carbon dioxide capture microcapsules in Example 1 after the temperature resistance test; Figure 4 Figure b shows the microscopic results of the carbon dioxide capture microcapsules in Comparative Example 1 after the temperature resistance experiment; Figure 5 Image a shows the microscopic results of the carbon dioxide capture microcapsules in Example 2 after the acid and alkali resistance test; Figure 5 Figure b shows the microscopic results of the carbon dioxide capture microcapsules in Comparative Example 1 after the acid and alkali resistance test. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0021] Example 1

[0022] A mixture of 5 wt% sodium carbonate solution and thymol blue indicator was used as the inner phase fluid, with 6 drops of thymol blue indicator added per 50 mL of sodium carbonate solution. A shell material obtained by mixing boron-containing siloxane as a crosslinking agent with polydimethylsiloxane at room temperature was used as the intermediate phase fluid. The boron-containing siloxane was a high-refractive-index tackifier (Z-1501) and accounted for 10% of the mass of polydimethylsiloxane. The surfactant plurnic was used. A mixture of F-127 and 10wt% polyvinyl alcohol (PVA) in a 2:1 volume ratio was used as the external phase fluid. In a microfluidic needle, the internal phase fluid was injected into the microfluidic needle at a flow rate of 10 μL / min through the tail of the first dispensing needle, the middle phase fluid was injected into the microfluidic needle at a flow rate of 25 μL / min through the non-coaxial side passage of the T-shaped tee, and the external phase fluid was injected into the microfluidic needle perpendicularly to the internal phase fluid through the two sets of cross-linked side passages of the four-way connector at a flow rate of 180 μL / min. The injection was continued for 6 hours, and the resulting droplets were transferred to water at 80°C and subjected to thermosetting reaction for 20 minutes to obtain microcapsules containing a single droplet with a core droplet diameter of 300~500 μm.

[0023] Example 2

[0024] A mixture of 5 wt% sodium carbonate solution and thymol blue indicator was used as the inner phase fluid, with 6 drops of thymol blue indicator added per 50 mL of sodium carbonate solution. An intermediate phase fluid was obtained by mixing alkyne-functionalized cage-like polysilsesquioxane as a crosslinking agent with polydimethylsiloxane at room temperature, wherein the alkyne-terminated polysilsesquioxane crosslinking agent accounted for 5% of the mass of polydimethylsiloxane. The surfactant plurnic was used. A mixture of F-127 and 10wt% polyvinyl alcohol (PVA) in a 2:1 volume ratio was used as the external phase fluid. In a microfluidic syringe, the internal phase fluid was injected into the microfluidic syringe at a flow rate of 15 μL / min through the tail of the first dispensing needle, the middle phase fluid was injected into the microfluidic syringe at a flow rate of 25 μL / min through the non-coaxial side passage of the T-shaped tee, and the external phase fluid was injected into the microfluidic syringe perpendicularly to the internal phase fluid through the two sets of cross-linked side passages of the four-way connector at a flow rate of 180 μL / min. The injection was continued for 6 hours. The resulting droplets were transferred to water at 80°C and subjected to thermosetting reaction for 20 minutes to obtain microcapsules containing a single droplet with a core droplet diameter of 300~400 μm.

[0025] Comparative Example 1 A mixture of 5 wt% sodium carbonate solution and thymol blue indicator was used as the internal phase fluid, with 6 drops of thymol blue indicator added per 50 mL of sodium carbonate solution. Hydrogen-containing polydimethylsiloxane (PHMS) was used as the shell material obtained by mixing it with the prepared polydimethylsiloxane at room temperature as a traditional hydrogen-containing silicone oil crosslinking agent, and 10 ppm of chloroplatinic acid catalyst was added. PHMS accounted for 10% of the mass of the prepared polydimethylsiloxane. The surfactant plurnic was used as the internal phase fluid. A mixture of F-127 and 10wt% polyvinyl alcohol (PVA) in a 2:1 volume ratio was used as the external phase fluid. In a microfluidic needle, the internal phase fluid was injected into the microfluidic needle at a flow rate of 15 μL / min through the tail of the first dispensing needle, the middle phase fluid was injected into the microfluidic needle at a flow rate of 25 μL / min through the non-coaxial side passage of the T-shaped tee, and the external phase fluid was injected into the microfluidic needle perpendicularly to the internal phase fluid through the two sets of cross-linked side passages of the four-way connector at a flow rate of 180 μL / min. The injection was continued for 6 hours, and the resulting droplets were transferred to water at 80°C and subjected to thermosetting reaction for 6 hours to obtain microcapsules containing a single droplet with a core droplet diameter of 300~400 μm.

[0026] Comparative Example 2 A mixture of 5 wt% sodium carbonate solution and thymol blue indicator was used as the inner phase fluid, with 6 drops of thymol blue indicator added per 50 mL of sodium carbonate solution. Pure polydimethylsiloxane material without crosslinking agent was used as the intermediate phase fluid, and a mixture of surfactant plurnic F-127 and 10 wt% polyvinyl alcohol (PVA) in a 2:1 volume ratio was used as the outer phase fluid. In a microfluidic needle, the inner phase fluid was injected into the microfluidic needle at a flow rate of 15 μL / min through the tail of the first dispensing needle, the intermediate phase fluid was injected into the microfluidic needle at a flow rate of 25 μL / min through the non-coaxial side passage of the T-shaped tee, and the outer phase fluid was injected into the microfluidic needle perpendicularly to the inner phase fluid through the two sets of crosslinked side passages of the four-way connector at a flow rate of 180 μL / min. The injection was continued for 6 h, and the generated droplets were transferred to water at 100 °C for thermosetting reaction for 5 h.

[0027] To better illustrate the technical effects of the present invention, the following provides corresponding characterization and performance evaluation of the relevant embodiments.

[0028] Performance Evaluation I. Morphological Observation The surface morphology and core-shell encapsulation properties of the microcapsules generated in Example 1 were observed using an optical microscope at 400x magnification. The results are as follows: Figure 1 As shown, the prepared capsules have a distinct core-shell structure, a smooth and regular surface, strong encapsulation properties, and no air bubbles.

[0029] II. Particle Size Distribution Test The morphology of the microcapsules prepared in Example 1 was observed by sampling using an NJF-120A metallurgical microscope. The results were compared with a standard scale. Figure 2 The particle size distribution shown indicates that the carbon dioxide capture microcapsules, produced under the specific conditions described above, have a uniform size distribution. The size variation is approximately 300–500 μm, ranging from 5% to 20%. The maximum size variation is 15%, demonstrating the good compatibility between the thermosetting material and the absorbent solvent and external fluid, and proving that carbon dioxide capture microcapsules with good monodispersity and uniform size can be obtained.

[0030] III. Evaluation of Swelling Stability The microcapsules prepared in Example 1 were thermoset and then stored in an isotonic solution of sodium carbonate. The microcapsules were kept in the isotonic solution in the bottle for one month. Figure 3 As shown, the capsules did not show any signs of swelling or leakage in the sodium carbonate isotonic solution and still had good adsorption effect.

[0031] IV. Evaluation of Temperature and Acid / Alkali Resistance The capsules prepared in Examples 1 and 2 and Comparative Examples 1 and 2 after curing were subjected to temperature resistance and acid / alkali resistance tests. The temperature resistance test conditions were as follows: the cured microcapsules were placed in a 120°C oven and left to stand for 1 hour. Afterward, they were soaked in an isotonic sodium carbonate solution for one day. The external morphology of the microcapsules was then observed under a 400x microscope. Taking the results of Example 1 and Comparative Example 1 as examples, it was observed that the microcapsules in Comparative Example 1... Figure 4 As shown in Figure b, some capsules are clustered together, and most have ruptured and collapsed, making them unusable. It can be concluded that Comparative Example 1 cannot withstand this temperature condition. In contrast, the microcapsules of Example 1... Figure 4 As shown in Figure a, there is no adhesion between the capsules, and the capsules show almost no breakage or collapse, so it can be considered that Example 1 can withstand the temperature conditions.

[0032] The acid and alkali resistance test conditions were as follows: after storage in an environment with a pH of 10-12 for 6 hours, the corrosion was observed under a 400x microscope. Taking the results of Example 2 and Comparative Example 1 as examples, it was observed that the microcapsules in Comparative Example 1... Figure 5 As shown in Figure b, it can be seen that some capsules originally had smooth, regular shells with a certain thickness. After corrosion, the capsules deformed severely, the shell thickness decreased, and some ruptured. It can be considered that Comparative Example 1 could not withstand the pH conditions. The microcapsules of Example 2, however, show... Figure 5 As shown in Figure a, the microcapsules still have an intact capsule structure and no damage was found, so it can be considered that Example 1 can withstand this pH condition.

[0033] After conducting the above experiments on the remaining embodiments and comparative examples, the experimental results are shown in Table 1: Table 1. Performance comparison of capture capsules between the examples and comparative examples

[0034] As shown in Table 1, the present invention uses crosslinking agent-modified polydimethylsiloxane thermosetting material as the outer shell. This material remains stable throughout the curing process without the need for any stabilizers, making the resulting microcapsules more cost-effective. Compared to microcapsules prepared with traditional crosslinking agents, the curing speed is faster with hot water heat transfer. After curing, the microcapsules, stored in a sodium carbonate solution isotonic with the liquid core, showed no signs of expansion or leakage. Compared to polydimethylsiloxane curing materials prepared with traditional crosslinking agents, the microcapsules exhibit stronger chemical corrosion resistance and temperature resistance.

[0035] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims.

Claims

1. A method for preparing a carbon dioxide capturing microcapsule, characterized by, The method comprises the following steps: The inner phase fluid, the middle phase fluid and the outer phase fluid are respectively input into the microfluidic needle tube to generate droplets, and the droplets in the microfluidic needle tube are collected and heat cured in water at a temperature of 45-120℃ for 10-30 min to obtain the microcapsules; The inner phase fluid comprises a sodium carbonate solution; The middle phase fluid comprises a shell material, the shell material is a mixed liquid of polydimethylsiloxane and a crosslinking agent, the crosslinking agent is one of boron-containing siloxane and alkyne-terminated polysilsesquioxane, and the mass fraction of the crosslinking agent is 1-10% of the polydimethylsiloxane; The outer phase fluid comprises a surfactant.

2. The method of claim 1, wherein: The surfactant is one or more of tetraethoxysilane, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, Pluronic F-127, Pluronic F-108 and polyvinyl alcohol.

3. The method of claim 1, wherein: The alkyne-terminated polysilsesquioxane is a single alkyne-terminated cage polysilsesquioxane, and the molecular weight ranges from 800 to 1500 g / mol.

4. The method of claim 1, wherein: The boron-containing siloxane crosslinking agent is one of a silicon-boron tackifier, boric acid modified hydrogen-containing silicone oil and triisopropanolamine cyclic borate.

5. The method of claim 1, wherein: The concentration of the sodium carbonate solution is 5-30 wt%, and the inner phase fluid is composed of the sodium carbonate solution and thymol blue indicator, wherein the amount of the thymol blue indicator added in 50 ml of the sodium carbonate solution is 6-7 drops.

6. The method of claim 1, wherein: The microfluidic needle tube comprises a first dispensing needle, a second dispensing needle, a third dispensing needle, a T-shaped tee, a male luer connector and a four-way crosslinking, wherein the needle of the first dispensing needle is inserted into a group of coaxial through holes in the T-shaped tee, another group of coaxial through holes of the T-shaped tee is connected to the male luer connector, the male luer connector is connected to the tail of the second dispensing needle, the needle of the second dispensing needle is inserted into the four-way crosslinking, and the through hole opposite to the second dispensing needle in the four-way crosslinking is connected to the tail of the third dispensing needle.

7. The method of claim 6, wherein the method further comprises: The size specifications of the first dispensing needle are as follows: length 2.0 inches, needle thickness 30G, inner diameter 0.16 mm and outer diameter 0.31 mm; the size specifications of the second dispensing needle are as follows: length 0.5 inches, needle thickness 23G, inner diameter 0.39 mm and outer diameter 0.63 mm; and the size specifications of the third dispensing needle are as follows: length 0.25 inches, needle thickness 19G, inner diameter 0.84 mm and outer diameter 1.08 mm.

8. The method of claim 6, wherein the method further comprises: The size specifications of the T-shaped tee are as follows: length 20 mm, inner diameter 1.0 mm and outer diameter 1.6 mm; the size specifications of the male luer connector are as follows: length 14 mm, inner diameter 1.0 mm and outer diameter 1.6 mm; and the size specifications of the four-way crosslinking are as follows: length 15.2 mm, inner diameter 1.0 mm and outer diameter 1.6 mm.

9. The method of claim 6, wherein the method further comprises: The inner phase fluid is injected into the microfluidic needle tube at a flow rate of 5-30 μL / min through the tail of the first dispensing needle; the middle phase fluid is injected into the microfluidic needle tube at a flow rate of 5-30 μL / min through the non-coaxial side through hole of the T-shaped tee; and the outer phase fluid is injected into the microfluidic needle tube at a flow rate of 150-220 μL / min through the two groups of side holes of the four-way crosslinking perpendicular to the inner phase fluid.

10. A carbon dioxide capturing microcapsule, characterized in that, The microcapsules are prepared by using the method in any one of claims 1-9.

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