Humidifying adsorption material formed based on ice template method, preparation method and application

Abstract

The invention discloses a humidifying adsorption material formed based on an ice template method, a preparation method and application, and belongs to the field of carbon dioxide capture adsorbents. The preparation method comprises the following steps: adding the pretreated adsorption material and the reaction carrier into a dimethyl sulfoxide solution, and uniformly mixing; adding an initiator into the mixed solution, uniformly mixing, then pouring into a carrier container, forming a directional pore channel structure at low temperature by adopting a one-way freezing forming method, and refrigerating to obtain formed gel; and unfreezing the formed gel, drying to constant weight, and soaking in a carbonate base solution or a hydroxyl base solution until the ion exchange reaction is completed, thereby obtaining the wetting adsorption material. According to the invention, the ice template method is applied to the forming process of the direct air trapping variable-humidity adsorption material, and the prepared variable-humidity adsorption material has a rich pore structure, so that the adsorption capacity and the adsorption rate of carbon dioxide are favorably improved, and a new technology is provided for the forming process of the direct air trapping adsorbent.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide capture adsorbents, and particularly relates to a variable humidity adsorption material formed by an ice templating method, a preparation method and an application thereof. Background Art

[0002] Developing direct air capture technology (DAC) is one of the important means to address global climate change. With the continuous increase of anthropogenic carbon dioxide emissions, the global temperature rise and extreme weather events have become more severe, and traditional emission reduction measures are facing huge challenges. Direct air capture technology can directly remove low-concentration carbon dioxide from the air, providing an effective solution for mitigating climate warming. Different from traditional carbon capture technologies, DAC does not rely on specific emission sources and has broad application potential, providing a feasible path for future negative carbon emissions.

[0003] In terms of carbon dioxide capture adsorbent materials, porous materials such as metal-organic frameworks (MOF), carbon-based materials and modified zeolites are usually used. These materials have a high specific surface area and excellent carbon dioxide adsorption performance, but their performance often decays under humid conditions. The variable humidity adsorption method realizes the adsorption and desorption of carbon dioxide through the regulation of humidity, providing an efficient, energy-saving and humidity-adaptive carbon dioxide capture method. The variable humidity adsorption materials used are usually quaternary ammonium-based ionic polymer materials, which can adsorb in a low-humidity environment and desorb in a high-humidity environment, and have great commercial application potential.

[0004] Regarding the forming process, the specific surface area of the membrane materials formed by conventional hot pressing, casting and dip coating methods decreases, which limits the improvement of the adsorption rate. Therefore, the ice templating method has attracted attention as an innovative forming technology. The membrane materials prepared by the ice templating method can form a pore structure with a high specific surface area during the forming process, effectively improving the loading amount and distribution uniformity of the active components, thereby enhancing the adsorption performance of the membrane materials. This method has the advantages of simplicity, low cost and high efficiency, and is expected to become one of the key technologies for the preparation of future variable humidity adsorption membrane materials. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a preparation method of a variable humidity adsorption material formed by an ice templating method. The forming material in the present invention has a regular and rich pore structure, which is beneficial to the gas flow and the improvement of the adsorption rate, and provides a new method for the variable humidity adsorbent forming technology.

[0006] The specific technical solution adopted by the present invention is as follows:

[0007] In the first aspect, the present invention provides a preparation method of a variable humidity adsorption material formed by an ice templating method, and the specific steps are as follows:

[0008] S1: Add the pretreated adsorbent material and reaction carrier to dimethyl sulfoxide solution, and obtain a mixed solution after mixing evenly.

[0009] S2: Add an initiator to the mixed solution obtained in step S1 and mix evenly; pour the mixed solution added with the initiator evenly into a carrier container, and form oriented pores at a low temperature by the unidirectional freezing molding method, and obtain a molded gel after refrigeration.

[0010] S3: Wait for the molded gel obtained in step S2 to thaw and then dry to a constant weight; soak the dried product in a carbonate-based base solution or a hydroxide-based base solution until the ion exchange reaction is completed to obtain a moistened adsorbent material.

[0011] Preferably, the adsorbent material in step S1 is a strong base type I resin or a strong base type II resin; the pretreatment process is as follows: soak and wash the adsorbent material with absolute ethanol, hydrochloric acid solution, and sodium hydroxide solution in sequence, then wash the soaked adsorbent material with deionized water until it is neutral, dry and grind it into powder, and perform particle size screening with a sieve; the drying temperature is set at 70 °C, and the drying time is 24 - 48 h.

[0012] Preferably, the reaction carrier is a mixture of benzoyl peroxide, dodecyl acrylate, and polyethylene glycol dimethacrylate.

[0013] Further, in the mixed solution, the ratio of the adsorbent material, benzoyl peroxide, dodecyl acrylate, and polyethylene glycol dimethacrylate is (10 - 25%): 7%: 20%: 2%.

[0014] Preferably, the initiator in step S2 is N,N-dimethylaniline; the added volume of the initiator is 1 - 3% of the mixed solution; the carrier container is made of a glass sheet or silica gel.

[0015] Preferably, the specific process of the unidirectional freezing molding method in step S2 is as follows: place the carrier container uniformly loaded with the mixed solution on a cold stage at a temperature of -90 °C to -30 °C for pre-freezing, and then place it in a refrigerator at 0 - 10 °C for refrigeration for 24 - 48 h; the pre-freezing time is set at 10 - 25 min.

[0016] Preferably, the thawed molded gel in step S3 is washed with deionized water for multiple times, placed in a vacuum drying oven and dried for 12 - 24 h, and the temperature of the vacuum drying oven is set at 50 - 60 °C.

[0017] Preferably, the carbonate-based base solution in step S3 is a sodium carbonate solution or a potassium carbonate solution with a concentration of 0.5 to 2.0 mol / L, and the hydroxide-based base solution is a sodium hydroxide solution or a potassium hydroxide solution with a concentration of 0.5 to 2.0 mol / L; the time for the ion exchange reaction by soaking is 24 h.

[0018] In a second aspect, the present invention provides a variable humidity adsorption material obtained by using the preparation method described in the first aspect.

[0019] In a third aspect, the present invention provides an application method of the variable humidity adsorption material described in the second aspect in capturing carbon dioxide in the air.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention applies the ice template method to the forming process of the variable humidity adsorption material for direct air capture. The obtained variable humidity adsorption material has a regular and rich pore structure, which is beneficial to the gas flow and the improvement of the adsorption rate. The variable humidity adsorption material prepared by the present invention has a high carbon dioxide adsorption capacity and adsorption rate, providing a new technology for the forming process of the direct air capture adsorbent. Description of the Drawings

[0022] Figure 1 It is a flow chart of the preparation method of the variable humidity adsorption material formed based on the ice template method provided by the present invention;

[0023] Figure 2 It is a diagram of the variable humidity adsorption material prepared in Example 2;

[0024] Figure 3 It is a comparative curve graph of the carbon dioxide adsorption amounts of the variable humidity adsorption materials prepared in Examples 1 to 3 and the materials prepared in Comparative Examples 1 to 3. Detailed Embodiments

[0025] The present invention will be further described and explained below with reference to the drawings and specific embodiments. The technical features of each embodiment in the present invention can be combined correspondingly without conflict.

[0026] Example 1

[0027] This example provides a preparation method of a variable humidity adsorption material formed based on the ice template method, and the specific steps are as follows:

[0028] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic resin type I with a volume ratio of 25%, 2-acryloyloxy dodecane with a volume ratio of 20%, polyethylene glycol dimethacrylate with a volume ratio of 2%, and benzoyl peroxide with a volume ratio of 7%. Stir at room temperature for at least 1 h. After mixing evenly, a mixed solution is obtained;

[0029] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix evenly; pour the mixed solution with the initiator added into a glass slide template container evenly, and adopt the unidirectional freezing molding method. After pre-freezing at -50°C on a cold stage for 15 min, place it in a refrigerator at 4°C and refrigerate for 36 h to promote the chemical cross-linking reaction and obtain a molded gel.

[0030] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50°C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0031] The variable humidity adsorption materials prepared in all examples and the materials obtained in the comparative example were all tested for carbon dioxide adsorption performance using a German NETZSCH STA449F3 synchronous thermal analyzer. The membrane after ion exchange with the alkaline solution was washed with deionized water multiple times and then placed in a crucible for testing. First, purge with nitrogen at 20°C and 60% RH for 0.5 h to remove residual CO2, then purge with dry nitrogen at 20°C for 1.5 h to dry the adsorption membrane, and finally purge with a mixed gas of 20°C, 10% RH, and 400 ppm CO2@N2 for 4.0 h to complete the adsorption process test.

[0032] Example 2

[0033] (1) In 20 mL of dimethyl sulfoxide solution, add strong base type I resin with a volume ratio of 10%, 2-acryloyloxy dodecane with a volume ratio of 20%, polyethylene glycol dimethacrylate with a volume ratio of 2%, and benzoyl peroxide with a volume ratio of 7%. Stir at room temperature for at least 1 h, and after mixing evenly, obtain a mixed solution.

[0034] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix evenly; pour the mixed solution with the initiator added into a glass slide template container evenly, and adopt the unidirectional freezing molding method. After pre-freezing at -50°C on a cold stage for 15 min, place it in a refrigerator at 4°C and refrigerate for 36 h to promote the chemical cross-linking reaction and obtain a molded gel.

[0035] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50°C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0036] Example 3

[0037] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic resin type II with a volume ratio of 10%, dodecyl acrylate with a volume ratio of 20%, polyethylene glycol dimethacrylate with a volume ratio of 2%, and benzoyl peroxide with a volume ratio of 7%. Stir at room temperature for at least 1 h. After mixing evenly, a mixed solution is obtained;

[0038] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix evenly; pour the mixed solution added with the initiator evenly into a glass slide template container. Using the unidirectional freezing molding method, pre-freeze at -50 °C on a cold stage for 15 min and then place it in a 4 °C refrigerator for refrigeration for 36 h to promote the chemical cross-linking reaction and obtain a molded gel;

[0039] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50 °C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0040] Comparative Example 1

[0041] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic resin type I with a volume ratio of 25%, dodecyl acrylate with a volume ratio of 20%, polyethylene glycol dimethacrylate with a volume ratio of 2%, and benzoyl peroxide with a volume ratio of 7%. Stir at room temperature for at least 1 h. After mixing evenly, a mixed solution is obtained;

[0042] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix evenly; pour the mixed solution added with the initiator evenly into a glass slide template container. Using the non-directional freezing molding method, directly place it in a 4 °C refrigerator for refrigeration for 36 h to promote the chemical cross-linking reaction and obtain a molded gel;

[0043] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50 °C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0044] Comparative Example 2

[0045] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic resin type I with a volume ratio of 10%, dodecyl acrylate with a volume ratio of 20%, polyethylene glycol dimethacrylate with a volume ratio of 2%, and benzoyl peroxide with a volume ratio of 7%. Stir at room temperature for at least 1 h. After mixing evenly, a mixed solution is obtained;

[0046] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix well; pour the mixed solution with the initiator evenly into a glass slide template container, and use the non-directional freezing molding method to directly place it in a 4°C refrigerator for refrigeration for 36 h to promote the chemical cross-linking reaction and obtain a molded gel;

[0047] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50°C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0048] Comparative Example 3

[0049] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic type II resin with a volume ratio of 10%, 20% of dodecyl acrylate, 2% of polyethylene glycol dimethacrylate, and 7% of benzoyl peroxide, stir at room temperature for at least 1 h, and mix well to obtain a mixed solution;

[0050] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator and mix well; pour the mixed solution with the initiator evenly into a glass slide template container, and use the non-directional freezing molding method to directly place it in a 4°C refrigerator for refrigeration for 36 h to promote the chemical cross-linking reaction and obtain a molded gel;

[0051] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50°C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0052] Figure 3 It is a comparative curve graph of the carbon dioxide adsorption amounts of the variable humidity adsorption materials prepared in Examples 1 to 3 and the materials prepared in Comparative Examples 1 to 3. The results show that: as the addition amount of the adsorption raw material increases, the adsorption amount also increases. Under the same content of the adsorption raw material, compared with the regular pore structure generated by the unidirectional freezing ice template method, the pores generated by the non-directional freezing method are more disordered, so the adsorption amount decreases slightly, and the pore structure has a greater impact on the adsorption rate, and the adsorption rate decreases significantly.

[0053] Comparative Example 4

[0054] (1) In 20 mL of dimethyl sulfoxide solution, add strongly basic type II resin with a volume ratio of 25%, 20% of dodecyl acrylate, 2% of polyethylene glycol dimethacrylate, and 7% of benzoyl peroxide, stir at room temperature for at least 1 h, and mix well to obtain a mixed solution;

[0055] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator, and mix evenly; pour the mixed solution with the initiator evenly into a glass slide template container, and adopt the unidirectional freezing molding method. After pre-freezing at -50°C for 15 min on a cold stage, place it in a refrigerator at 4°C for refrigeration for 36 h to promote the chemical cross-linking reaction.

[0056] (3) Thaw the obtained molded gel at room temperature for 48 h, wash it with deionized water multiple times, and place it in a vacuum drying oven at 50°C for drying for 12 h until constant weight; soak the dried product in a sodium carbonate solution for 24 h until the ion exchange reaction is completed to obtain a variable humidity adsorption material.

[0057] Compared with Example 1, the adsorption material used in this comparative example is a strong base type II resin, and the addition amount is 25%. However, due to the relatively high proportion of ion exchange resin and the poor mechanical properties of the raw materials, obvious stratification occurred in the product taken out of the refrigerator after thawing, and a uniform gel was not formed.

[0058] Comparative Example 5

[0059] (1) In 20 mL of dimethyl sulfoxide solution, add a strong base type II resin with a volume ratio of 25%, 20% of dodecyl acrylate, 2% of polyethylene glycol dimethacrylate, and 7% of benzoyl peroxide, and stir at room temperature for at least 1 h. After mixing evenly, a mixed solution is obtained;

[0060] (2) Add N,N-dimethylaniline with a volume ratio of 2% to the mixed solution as an initiator, and mix evenly; pour the mixed solution with the initiator evenly into a glass slide template container, and adopt the non-directional freezing molding method. Directly pour the mixed solution into a glass mold, and immediately place it in a refrigerator at 4°C for refrigeration for 36 h for reaction.

[0061] Compared with Example 1, the adsorption material used in this comparative example is a strong base type II resin, and the addition amount is 25%. The non-directional freezing ice template method is adopted. Due to the poor mechanical properties of the type II raw materials, the material is not formed at this ratio.

[0062] The above-described embodiments are only a preferred solution of the present invention, but it is not intended to limit the present invention. Those of ordinary skill in the relevant technical fields can still make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by adopting equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A preparation method of a variable humidity adsorption material formed by an ice templating method, characterized in that, The specific steps are as follows: S1: Add the pretreated adsorption material and reaction carrier into a dimethyl sulfoxide solution, and after mixing evenly, obtain a mixed solution; S2: Add an initiator to the mixed solution obtained in step S1 and mix evenly; pour the mixed solution added with the initiator evenly into a carrier container, and form unidirectional pores at a low temperature by a unidirectional freezing molding method, and obtain a molded gel after refrigeration; S3: Wait for the molded gel obtained in step S2 to thaw and then dry to a constant weight; soak the dried product in a carbonate-based base solution or a hydroxide-based base solution until the ion exchange reaction is completed to obtain a wet adsorption material.

2. The preparation method of the variable humidity adsorption material formed based on the ice templating method according to claim 1, characterized in that, In step S1, the adsorption material uses a strong base type I resin or a strong base type II resin; the pretreatment process is as follows: successively soak and wash the adsorption material with absolute ethanol, hydrochloric acid solution, and sodium hydroxide solution, and then wash the soaked adsorption material with deionized water until it is neutral, dry it and grind it into powder, and perform particle size screening with a sieve; the drying temperature is set at 70 °C and the drying time is 24-48 h.

3. The preparation method of the variable humidity adsorption material formed by the ice template method according to claim 1, characterized in that, The reaction carrier is a mixture of benzoyl peroxide, dodecyl acrylate, and polyethylene glycol dimethacrylate.

4. The preparation method of the variable humidity adsorption material formed by the ice template method according to claim 3, wherein, In the mixed solution, the ratio of the adsorption material, benzoyl peroxide, dodecyl acrylate, and polyethylene glycol dimethacrylate is (10-25%): 7%: 20%: 2%.

5. The preparation method of the variable humidity adsorption material formed based on the ice template method according to claim 1, characterized in that, In step S2, the initiator uses N,N-dimethylaniline; the added volume of the initiator is 1-3% of the mixed solution; the carrier container uses a glass sheet or silica gel.

6. The preparation method of the variable humidity adsorption material formed by the ice template method according to claim 1, characterized in that, The specific unidirectional freezing molding method in step S2 is as follows: Place the carrier container uniformly loaded with the mixed solution on a cold stage at a temperature of -90 °C to -30 °C for pre-freezing, and then put it in a refrigerator at 0 °C to 10 °C for refrigeration for 24-48 h; the pre-freezing time is set at 10-25 min.

7. The preparation method of the variable humidity adsorption material formed by the ice template method according to claim 1, characterized in that, In step S3, the thawed molded gel is washed with deionized water multiple times and placed in a vacuum drying oven to dry for 12-24 h, and the temperature of the vacuum drying oven is set at 50-60 °C.

8. The preparation method of the variable humidity adsorption material formed by the ice template method according to claim 1, characterized in that, The carbonate-based base solution in step S3 uses a sodium carbonate solution or a potassium carbonate solution with a concentration of 0.5-2.0 mol / L, and the hydroxide-based base solution uses a sodium hydroxide solution or a potassium hydroxide solution with a concentration of 0.5-2.0 mol / L; the soaking time for the ion exchange reaction is 24 h.

9. A wet adsorption material obtained by using the preparation method according to any one of claims 1-8.

10. A method for applying the wet adsorption material according to claim 9 in capturing carbon dioxide in the air.

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