Biomass aerogel solid adsorbent, preparation method therefor, and use thereof

Abstract

The present invention provides a biomass aerogel solid adsorbent, a preparation method therefor, and a use thereof. The preparation method of the present invention comprises the following steps carried out in sequence: S1: soaking a wood material in a sodium bicarbonate solution, followed by stirring, ultrasonic oscillation, washing, and drying to obtain a biomass-modified framework; S2: soaking the biomass-modified framework in a mixed solution containing tris(hydroxymethyl)aminomethane and a water-retaining agent, and draining after soaking; S3: soaking the biomass-modified framework in a mixed solution containing acid-dissolved chitosan and acetic acid, draining after soaking, and vacuum drying to obtain a biomass aerogel solid adsorbent. The biomass aerogel solid adsorbent of the present invention has a large specific surface area and good air permeability, with low wind resistance, small pressure drop, and low energy consumption when adsorbing acidic gases such as carbon dioxide, and exhibits a high capture rate for acidic gases.

Description

Biomass aerogel solid adsorbent and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon capture, and particularly to a biomass aerogel solid adsorbent and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of industrialization, a large amount of greenhouse gases such as carbon dioxide is discharged after the use of fossil fuels, and the excessive greenhouse gases trap the long-wave radiation energy emitted from the earth's surface, forming a greenhouse effect, and further triggering global warming. Based on this, carbon capture, storage and utilization technology is developing rapidly, and how to handle carbon dioxide in power plants at low cost has great significance.

[0003] Carbon capture technology mainly includes chemical absorption method, physical absorption method, membrane separation method, etc. The chemical absorption method is to use a chemical absorbent to react with carbon dioxide in flue gas to form unstable salts, and then decompose these salts by heating or reducing pressure to release and collect carbon dioxide. Common absorbents include hot potassium base, ammonia water, alcohol amine, etc. The physical absorption method is to use temperature or pressure swing adsorption to capture carbon dioxide. Common physical adsorbents include activated carbon, zeolite molecular sieve, silica gel, etc. The membrane separation method uses the difference in the permeability of gas molecules through the membrane to separate and collect carbon dioxide. However, the specific surface area of the existing carbon capture adsorbent is small and the gas permeability is poor, and the wind resistance and energy consumption are large when adsorbing carbon dioxide, which is not conducive to improving the capture rate of carbon dioxide.

[0004] In view of this, the present application is proposed.

[0005] SUMMARY

[0006] The purpose of the present application is to provide a biomass aerogel solid adsorbent and a preparation method and application thereof. The biomass aerogel solid adsorbent has a large specific surface area and good gas permeability, low wind resistance, small pressure loss and low energy consumption when adsorbing acidic gases such as carbon dioxide, and a high capture rate of acidic gases.

[0007] The present application provides a preparation method of a biomass aerogel solid adsorbent, comprising the following steps performed in sequence:

[0008] S1: soaking a wooden material in a sodium bicarbonate solution, stirring, ultrasonic oscillation, washing and drying to obtain a biomass modified skeleton;

[0009] S2: soaking the biomass modified skeleton in a mixed solution containing tris(hydroxymethyl)aminomethane (TRIS) and a water-retaining agent, and draining after soaking;

[0010] S3: soaking the biomass modified skeleton in a mixed solution containing acid-soluble chitosan and acetic acid, draining and vacuum drying after soaking, and preparing a biomass aerogel solid adsorbent.

[0011] In step S1, the wood material is natural sunken wood; the mass content of sodium bicarbonate solution is 2-4%, the soaking time is 2-4h; the drying temperature is 160-200℃, and the drying time is 8-12h.

[0012] The wood material is soaked in sodium bicarbonate solution, which can neutralize the acidic substances in the wood material; in particular, sodium bicarbonate can release carbon dioxide during subsequent heating and drying, thereby completely opening the internal channels of the wood material, significantly increasing the specific surface area and greatly increasing the air permeability, which is beneficial to reducing the wind resistance during the adsorption of acidic gases such as carbon dioxide, thereby improving the capture rate of acidic gases.

[0013] In step S2, the mass content of tris-hydroxymethyl aminomethane in the mixed solution is 8-12%, and the mass content of water-retaining agent is 1-3%; the water-retaining agent is selected from at least one of calcium chloride and magnesium chloride; the soaking time is 6-10h.

[0014] When the biomass modified skeleton is soaked in the mixed solution containing tris-hydroxymethyl aminomethane and water-retaining agent, the appropriate concentration of water-retaining agent has a certain hygroscopicity, which can keep tris-hydroxymethyl aminomethane in a liquid-solid intermediate state, and the amino groups in tris-hydroxymethyl aminomethane in this state are completely activated, greatly improving its excellent adsorption capacity.

[0015] In step S3, the mass content of acid-soluble chitosan in the mixed solution is 1-3%, and the mass content of acetic acid is 0.05-0.15%; the soaking time is 2-6h; the vacuum drying temperature is 110-130℃, and the vacuum drying time is 10-14h.

[0016] Acid-soluble chitosan has good biocompatibility and biodegradability, carries a large number of active amino groups, has good film-forming property, and can maximize the retention of amino components; at the same time, under the action of a small amount of acetic acid, the amino groups of acid-soluble chitosan are fully protonated, which maximizes the capture of acidic gases. In particular, after the biomass modified skeleton is coated with acid-soluble chitosan, a viscous film can be formed by simple heating, which can firmly lock the effective functional groups and functional materials. In addition, vacuum drying can maximize the retention of the structure of the biomass modified skeleton, which has the advantages of large specific surface area, good air permeability, and low wind resistance, low pressure loss, and low energy consumption when applied to directly capture carbon dioxide in air.

[0017] The application also provides a biomass aerogel solid adsorbent prepared according to the above preparation method.

[0018] The application also provides application of the biomass aerogel solid adsorbent in adsorbing acid gases, which are not strictly limited, such as carbon dioxide, sulfur dioxide and the like.

[0019] The biomass aerogel solid adsorbent has excellent air permeability, can be combined into multiple units for use according to actual needs, is suitable for a wide range of carbon dioxide capture scenarios, and can be recycled and reused by heating at 100 DEG C; meanwhile, the biomass aerogel solid adsorbent is a biomass carbon-based material, has combustible properties and combustion heat value, and can also be directly mixed and burned in a boiler.

[0020] The implementation of the application has at least the following advantages:

[0021] 1. The application uses wood materials as raw materials, which are low in price, large in density, free of secondary pollution, friendly to the environment, and conducive to the preparation of solid adsorbents for quickly, efficiently and sustainably capturing carbon dioxide from air through subsequent modification;

[0022] 2. The application can completely open the internal vein channels of the wood materials, improve the specific surface area and air permeability of the wood materials, and is conducive to reducing the wind resistance in the process of adsorbing acid gases such as carbon dioxide, thereby improving the capture rate of acid gases;

[0023] 3. The application can completely activate the amino groups in the tris-hydroxymethyl aminomethane, thereby greatly exerting the excellent adsorption capacity of the tris-hydroxymethyl aminomethane;

[0024] 4. The application can not only protonate the amino groups of the acid-soluble chitosan to the greatest extent to capture acid gases, but also form a viscous film on the surface of the wood materials to lock the effective functional groups and functional materials, thereby ensuring the adsorption performance of the modified materials;

[0025] 5. The preparation method is simple, increases the specific surface area of the material through two-stage drying, and completely retains the dredged gas channels, so that the prepared biomass aerogel solid adsorbent has a large specific surface area and excellent air permeability, low wind resistance, small pressure loss and low energy consumption in the process of adsorbing acid gases such as carbon dioxide, and a high capture rate of acid gases;

[0026] 6、The biomass aerogel solid adsorbent has low application cost, low loss, low maintenance cost, and is not limited by application scenarios, can be used in a single biomass aerogel solid adsorbent module or multiple biomass aerogel solid adsorbent modules, so as to adapt to various scenarios, the whole process is green and environmentally friendly, and no pollution is caused, can be applied to a gas environment below 120 DEG C, and can be recycled and reused by heating at 80-100 DEG C, and has the advantages of low cost, simple operation, rapid effect, environmental friendliness, no maintenance, etc. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0028] Fig. 1 is a structural schematic view of a carbon dioxide capture device of test example 1. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0030] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form also includes the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0031] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0032] Example 1

[0033] The preparation method of the biomass aerogel solid adsorbent of the present embodiment is as follows:

[0034] 1) Preparation of biomass modified skeleton

[0035] The natural sunken wood is polished and cut into a sunken wood segment with a diameter of 10.8 cm and a length of 20 cm, and then soaked in a sodium bicarbonate solution with a mass content of 3% for 3 hours. After the sunken wood segment is infiltrated with sodium bicarbonate, surface impurities are washed by stirring at a suitable speed and ultrasonic oscillation, and then placed into a blast drying oven and heated at 180°C for 10 hours, and then naturally cooled to room temperature to obtain a biomass modified skeleton.

[0036] 2) First soaking treatment

[0037] The trimethylol aminomethane and food-grade magnesium chloride are fully stirred and dissolved in water to prepare a first mixed solution; the mass content of trimethylol aminomethane in the first mixed solution is controlled to be 10%, and the mass content of magnesium chloride is controlled to be 2%.

[0038] The biomass modified skeleton of step 1) is soaked in the above-mentioned first mixed solution for 8 hours, and then air-dried.

[0039] 3) Second soaking treatment

[0040] The acid-soluble chitosan is dissolved in a 0.1% acetic acid solution and fully stirred to prepare a second mixed solution; the mass content of acid-soluble chitosan in the second mixed solution is controlled to be 2%.

[0041] The biomass modified skeleton after the first soaking treatment of step 2) is soaked in the above-mentioned second mixed solution for 4 hours, and then dried at 120°C under vacuum for 12 hours to obtain a biomass aerogel solid adsorbent.

[0042] Example 2

[0043] The preparation method of the biomass aerogel solid adsorbent of the present example is as follows:

[0044] 1) Preparation of biomass modified skeleton

[0045] The natural sunken wood is polished and cut into a sunken wood segment with a diameter of 10.8 cm and a length of 20 cm, and then soaked in a sodium bicarbonate solution with a mass content of 2% for 4 hours. After the sunken wood segment is infiltrated with sodium bicarbonate, surface impurities are washed by stirring at a suitable speed and ultrasonic oscillation, and then placed into a blast drying oven and heated at 160°C for 12 hours, and then naturally cooled to room temperature to obtain a biomass modified skeleton.

[0046] 2) First soaking treatment

[0047] The trimethylol aminomethane and food-grade magnesium chloride are fully stirred and dissolved in water to prepare a first mixed solution; the mass content of trimethylol aminomethane in the first mixed solution is controlled to be 8%, and the mass content of magnesium chloride is controlled to be 1%.

[0048] The biomass modified skeleton of step 1) is soaked in the above-mentioned first mixed solution, and after soaking for 10 h, air blowing is used to drain.

[0049] 3) Second soaking treatment

[0050] The acid-soluble chitosan is dissolved in an acetic acid solution with a mass content of 0.05%, and after being fully stirred, a second mixed solution is prepared; the mass content of the acid-soluble chitosan in the second mixed solution is controlled to be 1%.

[0051] The biomass modified skeleton after the first soaking treatment of step 2) is soaked in the above-mentioned second mixed solution, soaked for 2 h, and after being drained, vacuum drying is performed at 110°C for 14 h, thereby obtaining a biomass aerogel solid adsorbent.

[0052] Example 3

[0053] The preparation method of the biomass aerogel solid adsorbent of the present example is as follows:

[0054] 1) Preparation of biomass modified skeleton

[0055] After the natural sunken wood is polished and cut into sunken wood segments with a diameter of 10.8 cm and a length of 20 cm, the sunken wood segments are soaked in a sodium bicarbonate solution with a mass content of 4% for 2 h; after the sunken wood segments are soaked in the sodium bicarbonate solution, surface impurities are washed away by stirring at a suitable speed and ultrasonic oscillation, and then the sunken wood segments are placed in a blast drying oven and heated at 200°C for 8 h, and then naturally cooled to room temperature, thereby obtaining a biomass modified skeleton.

[0056] 2) First soaking treatment

[0057] The tris-hydroxymethyl aminomethane and calcium chloride are fully stirred and dissolved in water to prepare a first mixed solution; the mass content of the tris-hydroxymethyl aminomethane in the first mixed solution is controlled to be 12%, and the mass content of the calcium chloride in the first mixed solution is controlled to be 3%.

[0058] The biomass modified skeleton of step 1) is soaked in the above-mentioned first mixed solution, and after soaking for 6 h, air blowing is used to drain.

[0059] 3) Second soaking treatment

[0060] The acid-soluble chitosan is dissolved in an acetic acid solution with a mass content of 0.15%, and after being fully stirred, a second mixed solution is prepared; the mass content of the acid-soluble chitosan in the second mixed solution is controlled to be 3%.

[0061] The biomass modified skeleton after the first soaking treatment of step 2) is soaked in the above-mentioned second mixed solution, soaked for 6 h, and after being drained, vacuum drying is performed at 130°C for 10 h, thereby obtaining a biomass aerogel solid adsorbent.

[0062] Comparative Example 1

[0063] Except for the absence of food-grade magnesium chloride in the preparation of the first mixture, the rest is basically the same as in Example 1.

[0064] Compare with Example 2

[0065] Except for dissolving acid-soluble chitosan in water when preparing the second mixture, the rest is basically the same as in Example 1.

[0066] Compare with Example 3

[0067] Except for not performing the first soaking treatment, it is basically the same as in Example 1.

[0068] Compare with Example 4

[0069] Except for not performing a second soaking treatment, and after the first soaking, the sample was air-dried and vacuum-dried at 120°C for 12 hours, the rest was basically the same as in Example 1.

[0070] Experimental Example 1

[0071] Referring to Figure 1, the process of capturing carbon dioxide from the air is as follows:

[0072] A PE hose with an inner diameter of 11cm was cut to approximately 2m. One end (A port) was inserted into a well-sealed acrylic chamber a. Chamber a had small perforations on all four sides for ventilation (to stabilize the flow). A vacuum pump was installed inside chamber a, with an external pagoda-shaped connector that was sealed to port A. A carbon dioxide detector (in ppm) was also installed inside chamber a. The other end (B port) was inserted into individual biomass aerogel solid adsorbent modules prepared from the biomass aerogel solid adsorbents of Examples 1-4 and Comparative Examples 1-4, respectively. These modules were then inserted into a well-sealed acrylic chamber b, which contained the same carbon dioxide detector as chamber a. The vacuum pump was turned on, and the gas flow rate was approximately 7.2m³ / s. 3 / h, after the data from the two carbon dioxide detectors stabilized, the data before and after the carbon dioxide capture treatment in the air were statistically analyzed, and the results are shown in Table 1.

[0073] The recovery method for biomass aerogel solid adsorbent is as follows:

[0074] The adsorption saturation state of the biomass aerogel solid adsorbent can be visually assessed using a carbon dioxide detector in the acrylic B chamber. When the data from the carbon dioxide detector rises significantly, the test is stopped. The biomass aerogel solid adsorbent is then removed and placed in a blower heating chamber at 100°C. A recovery bag can be connected to the outlet of the heating chamber, and a carbon dioxide detector is installed inside the pipeline. Once the data stabilizes, it indicates that the adsorbent recovery is complete and it can be reused. The captured carbon dioxide can also be recovered.

[0075] Experimental Example 2

[0076] Except for the insertion of two biomass aerogel solid adsorbent modules prepared from the biomass aerogel solid adsorbent of Example 1 into another B port, the rest is the same as in Example 1.

[0077] Table 1 shows the concentration changes of carbon dioxide capture before and after in the biomass aerogel solid adsorbent module.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a biomass aerogel solid adsorbent, characterized in that, The steps are performed in the following order: S1: The wood material is soaked in sodium bicarbonate solution, stirred, ultrasonically vibrated, washed and dried to obtain a biomass modified skeleton; S2: Immerse the biomass modified skeleton in a mixture containing tris(hydroxymethyl)aminomethane and a water-retaining agent, and drain after immersion; S3: The biomass modified skeleton is immersed in a mixture containing acid-soluble chitosan and acetic acid, drained and vacuum dried to obtain a biomass aerogel solid adsorbent.

2. The preparation method according to claim 1, characterized in that, The wood material is natural driftwood; the sodium bicarbonate solution contains 2-4% by mass.

3. The preparation method according to claim 1, characterized in that, In step S1, the soaking time is 2-4 hours; the drying temperature is 160-200℃, and the drying time is 8-12 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the mass content of tris(hydroxymethyl)aminomethane in the mixture is 8-12%, and the mass content of the water-retaining agent is 1-3%.

5. The preparation method according to claim 1, characterized in that, The water-retaining agent is selected from at least one of calcium chloride and magnesium chloride.

6. The preparation method according to claim 1, characterized in that, In step S2, the soaking time is 6-10 hours.

7. The preparation method according to claim 1, characterized in that, In step S3, the mass content of acid-soluble chitosan in the mixture is 1-3%, and the mass content of acetic acid is 0.05-0.15%.

8. The preparation method according to claim 1, characterized in that, In step S3, the soaking time is 2-6 hours; the vacuum drying temperature is 110-130℃, and the vacuum drying time is 10-14 hours.

9. A biomass aerogel solid adsorbent, characterized in that, Prepared according to the preparation method according to any one of claims 1-8.

10. The application of the biomass aerogel solid adsorbent according to claim 9 in the adsorption of acidic gases.

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