Spherical solid ammonia CO2 adsorption material and preparation method thereof

Abstract

The invention discloses a preparation method of a spherical solid ammonia CO2 adsorption material, which comprises the following steps: in a water-in-water emulsion template formed by dextran, polyethylene glycol and nano cellulose crystal, taking polyethyleneimine as a matrix, and then crosslinking and curing with ethylene glycol diglycidyl ether to obtain the spherical solid ammonia CO2 adsorption material. According to the invention, the polyethyleneimine is used as a matrix, and the polyethyleneimine has a large number of amino groups which are all effective CO2 adsorption sites; meanwhile, a water-in-water emulsion template formed by glucan, polyethylene glycol and nano cellulose crystals is adopted, the existence of a large amount of water in the emulsion template is beneficial to full swelling of the adsorption material in the synthesis process, and the interior of the adsorption material can be fully crosslinked, so that the adsorption material can be formed at a relatively low crosslinking agent concentration due to uniform crosslinking; therefore, the amino group density is high. The swelling rate of the adsorbing material obtained by the preparation method is 198-296%, so that the adsorbing material can be fully swelled in a humid state, and efficient adsorption of CO2 is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption materials, and in particular relates to a spherical solid ammonia CO2 adsorption material and a preparation method thereof. Background Art

[0002] Since the Industrial Revolution, the CO2 emitted by the large-scale burning of fossil fuels has made the global warming problem increasingly serious. Therefore, effective methods need to be taken to solve this problem. The development of carbon dioxide capture, utilization and storage technology, especially capture technology, is considered to be an efficient method. The ideal CO2 adsorption material should have high adsorption capacity, good selectivity and low preparation and use costs. The adsorption capacity depends on the number of effective adsorption sites, the selectivity depends on the adsorption kinetics, and the cost is related to the raw materials, preparation process and regeneration performance of the material.

[0003] In order to obtain a higher adsorption capacity, people have loaded amines on porous materials by means of impregnation, grafting, and a combination of the two; in the document with DOI 10.1016 / j.seppur.2024.126884, tetraethylenepentamine (TEPA) was used to modify hydroxycopper phosphate Cu2(OH)PO4 by impregnation method to prepare an adsorbent with a maximum adsorption capacity of 6.54 mmol / g; in the document with DOI 10.1016 / j.energy.2023.127392, a porous carbon aerogel adsorbent grafted with polyethyleneimine (PEI) was developed. The adsorption capacity was tested in a simulated flue atmosphere and was 5.58 mmol / g. It also has the advantages of low regeneration energy consumption, good stability and water resistance. In the literature with DOI 10.1016 / j.ceramint.2024.03.175, N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO) and pentaethylenehexamine (PEHA) were used to functionalize mesoporous hollow silica nanoparticles (FHMS) by grafting and impregnation, respectively. This adsorbent overcomes the problems of easy loss during the impregnation cycle and low adsorption capacity of the grafting method. The adsorption capacity can reach 3.62 mmol / g, and it has high adsorption cycle stability and amine efficiency. However, excessive amine loading can easily lead to blockage of the pore structure, thereby affecting the amine efficiency and the adsorption performance of the material. In addition, although the matrix can provide a porous structure, it will reduce the amine density of the material to a certain extent.

[0004] In order to reduce costs, it is necessary to consider the cost of raw materials for material synthesis and the complexity of the synthesis process; in the literature with DOI 10.1021 / acs.langmuir.9b03694, a microsphere adsorbent was synthesized by a simple one-step ring-opening cross-linking reaction of polyethyleneimine and ethylene glycol diglycidyl ether, and its adsorption capacity was 7.28mmol / g, but a large amount of liquid paraffin and expensive surfactant Span-80 were required; in the literature with DOI 10.1007 / s10971-023-06165-z, resorcinol and aldehyde were used as carbon precursors, tetraethylenepentamine was used as nitrogen precursor and base catalyst, and then carbonization and activation were performed, and nitrogen-rich carbon microspheres were prepared by a one-pot hydrothermal synthesis, and its adsorption capacity could reach 2.97mmol / g, but carbonization and activation needed to be carried out at conditions greater than 600°C.

[0005] Existing solid amine adsorption materials are mainly loaded types. On the one hand, the material is required to have good mass transfer requirements for CO2 during the adsorption process to prevent excessive amine loading from clogging the pores, and the matrix will also reduce the adsorption capacity of the material; on the other hand, the general emulsion method for preparing microspheres requires the use of traditional oil-in-water (w / o) and water-in-oil (o / w) emulsions with a large amount of organic solvents and surfactants. A large amount of organic solvents can easily pollute the environment and increase the processing cost, and the suitable surfactants are relatively expensive, which increases the cost. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the main purpose of the present invention is to provide a method for preparing a spherical solid ammonia CO2 adsorbent material, which has the characteristics of energy saving, environmental protection and cost saving. At the same time, the prepared adsorbent material is spherical and has a swelling rate of 198-296%.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a spherical solid ammonia CO2 adsorption material is disclosed. The material is prepared by cross-linking and solidifying polyethylene imine as a matrix in a water-in-water emulsion template formed by dextran, polyethylene glycol and nanocellulose crystals.

[0009] In certain specific embodiments, the method for preparing the spherical solid amine CO2 adsorbent material specifically comprises the following steps:

[0010] S1) adding polyethylene glycol and nanocellulose crystals into deionized water and mixing them evenly to obtain a first mixed aqueous solution containing nanocellulose crystals and polyethylene glycol;

[0011] S2) adding the dextran and polyethyleneimine solution into deionized water and mixing them evenly to obtain a second aqueous solution containing polyethyleneimine and dextran;

[0012] S3) adding the first mixed aqueous solution obtained in step S1) to the second mixed aqueous solution obtained in step S2) and mixing them evenly, then adding ethylene glycol diglycidyl ether to carry out a cross-linking reaction, and after the reaction is completed, Soxhlet extraction, washing, solvent exchange, and freeze-drying are performed to obtain a spherical solid amine CO2 adsorption material.

[0013] In certain specific embodiments, the mass ratio of polyethylene glycol, dextran and nanocellulose crystals in step S1) is 0.5-1.5 g: 0.3-0.8 g: 20-40 mg.

[0014] Furthermore, the mass ratio of polyethylene glycol, dextran and nanocellulose crystals is 1.20 g:0.60 g:30 mg;

[0015] In certain specific embodiments, the mass ratio of dextran to polyethyleneimine in step S2) is 0.6:(1.50-2.25).

[0016] In certain specific embodiments, the average molecular weight of the polyethylene glycol is 15000-25000, the length×diameter of the nanocellulose crystal is (150-250)×(5-15) nm, and the average molecular weight of the dextran is 60000-80000.

[0017] Furthermore, the average molecular weight of the polyethylene glycol is 20,000, the length×diameter of the nanocellulose crystal is 200×10 nm, and the average molecular weight of the dextran is 70,000.

[0018] The mass ratio of polyethylene glycol to nanocellulose crystals in step S1) is (0.5-1.5) g: (20-40) mg.

[0019] In certain specific embodiments, the mass ratio of dextran to polyethyleneimine in step S2) is 1:(5-15).

[0020] In certain specific embodiments, the average molecular weight of the polyethylene glycol is 15000-25000, the length×diameter of the nanocellulose crystal is (150-250)×(5-15) nm, and the average molecular weight of the dextran is 60000-80000.

[0021] In certain specific embodiments, the mass ratio of polyethyleneimine to ethylene glycol diglycidyl ether is 1:(0.1-0.6).

[0022] In certain specific embodiments, the mass ratio of the polyethyleneimine to the deionized water in the reaction system is 1:(6.7-10).

[0023] In certain specific embodiments, the weight average molecular weight of polyethyleneimine in the polyethyleneimine solution is 3000-100000, and the mass fraction of the polyethyleneimine solution is 30-40%.

[0024] Furthermore: the weight average molecular weight of the polyethyleneimine is 100,000.

[0025] The larger the molecular weight of the polyethyleneimine used, the less crosslinking amount is needed for crosslinking into spheres. Since the crosslinking agent does not contain adsorption functional groups, the less the amount of crosslinking agent used, the higher the adsorption amount of the adsorbent per unit mass. The polyethyleneimine with a molecular weight that is too high will cause the viscosity of the emulsion to be too high, thus affecting the stability of the emulsion. However, in the w / w system, since both phases are water, the problem of high viscosity of the emulsion caused by the high molecular weight of PEI can be alleviated to a certain extent. Therefore, raw materials with a large molecular weight are preferred without affecting the stability of the emulsion.

[0026] The lower the concentration of the polyethyleneimine solution used, the more cross-linking agent is needed to cross-link it into a spherical shape, which will reduce its adsorption capacity per unit mass. If the concentration of the polyethyleneimine solution used is too high, the viscosity of the emulsion will be too high, affecting the stirring, so that the cross-linking agent cannot be evenly distributed after dropwise addition. At the same time, if the cross-linking and curing of polyethyleneimine is too fast, the stirrer will not be able to maintain stirring, which will eventually lead to uneven cross-linking of the adsorbent material and may affect the subsequent regeneration performance.

[0027] In certain specific embodiments, in step S3), the uniform mixing is achieved by stirring at a speed of 200-600 rpm for a time of 20-40 min; and the cross-linking reaction is achieved at a temperature of 25° C. for a time of 24 h.

[0028] When the stirring rate is too low, due to the high viscosity of the emulsion and the low solubility of ethylene glycol diglycidyl ether in water, the crosslinking agent is easily over-concentrated locally, resulting in an overly large diameter distribution of the microspheres. When the stirring rate is too high, due to the excessive mechanical shear force, the morphology of the microspheres is easily destroyed.

[0029] In certain specific embodiments, in step S3), the solvents used for the Soxhlet extraction and washing are deionized water and anhydrous ethanol, respectively, and the Soxhlet extraction times are 60 hours and 36 hours, respectively.

[0030] In certain specific embodiments, in step S3), the solvent used in the solvent exchange is deionized water, and the solvent exchange time is 12 hours.

[0031] In certain specific embodiments, in step S3), the drying method is freeze-drying, and the freeze-drying time is 48 hours.

[0032] The present invention also provides a spherical solid ammonia CO2 adsorption material prepared according to the above preparation method. The solid ammonia CO2 adsorption material is spherical and has an expansion rate of 198-396%.

[0033] Compared with the prior art, the present invention has at least the following advantages:

[0034] 1) The spherical solid amine CO2 adsorbent material provided by the present invention is based on polyethyleneimine, which has a large number of amine groups, all of which are effective CO2 adsorption sites; at the same time, a water-in-water emulsion template formed by dextran, polyethylene glycol and nanocellulose crystals is used. The presence of a large amount of water in the emulsion template is conducive to the full swelling of the adsorbent material during the synthesis process, and the adsorbent material can be fully cross-linked inside. The resulting uniform cross-linking can make the adsorbent material form at a lower cross-linking agent concentration, so it has a high amino density. In summary, the adsorbent material has more active sites per unit mass for adsorption, thereby significantly improving the CO2 adsorption capacity of the adsorbent material in a wet state.

[0035] 2) During the synthesis of the adsorbent material of the present invention, the dextran in the water-in-water emulsion template forms hydrogen bonds with the primary and secondary amines on the polyethyleneimine, inducing the arrangement of effective adsorption sites near the surface of the microspheres, thereby giving the adsorbent good adsorption kinetics;

[0036] 3) The adsorbent material synthesized by the present invention has a spherical structure, which is conducive to accelerating the mass transfer of CO2, and the adsorbent material can ensure that CO2 can be fully transferred to the interior of the spherical structure, thereby further increasing the adsorption amount;

[0037] 4) The synthesis process of the present invention does not require heating and avoids the pollution problem caused by organic solvents, which has the advantage of being environmentally friendly;

[0038] 5) The swelling rate of the adsorbent material synthesized by the present invention is 198-296%, thereby ensuring that the adsorbent material is fully swollen in a wet state to achieve efficient adsorption of CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below.

[0040] Figure 1 This is a Fourier transform infrared spectrum comparison diagram of the adsorbent material prepared in Example 1 of the present invention and PEI;

[0041] Figure 2 Ad are SEM images of the adsorbent materials prepared in Test Example 1, Test Example 2, Example 1, and Test Example 3 of the present invention, respectively;

[0042] Figure 3 From ae, they are SEM images of the adsorbent materials prepared in Experimental Example 5, Experimental Example 6, Experimental Example 7, Experimental Example 8, and Example 1 of the present invention;

[0043] Figure 4 Ad are SEM images of the adsorbent materials prepared in Test Example 10, Example 1, Test Example 11, and Test Example 12 of the present invention, respectively;

[0044] Figure 5 The adsorption breakthrough curve and adsorption amount relationship diagram of the adsorbent material prepared by different PEI concentrations of the present invention;

[0045] Figure 6 The adsorption penetration curve, adsorption amount and swelling rate diagram of the adsorbent material prepared by different mass ratios of PEI and EGDE in the present invention;

[0046] Figure 7 This is a graph of the adsorption capacity of the adsorbent material prepared in Example 1 of the present invention after 10 adsorption-desorption regenerations. DETAILED DESCRIPTION

[0047] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0048] When a certain amount, concentration or other value or parameter is expressed in the form of a range, a preferred range, or a preferred upper and lower numerical limit, it should be understood that it is equivalent to specifically revealing any range by combining any pair of upper range limits or preferred numerical values ​​with any lower range limit or preferred numerical value, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical range values ​​listed herein include the endpoints of the range, and all integers and fractions within the range.

[0049] Unless otherwise indicated, all percentages, parts, ratios, etc. herein are by weight.

[0050] The materials, methods, and examples herein are illustrative and are not to be construed as limiting unless specifically stated.

[0051] In the following embodiments, polyethylene glycol was purchased from Yuanye Biotechnology, the model is polyethylene glycol 20000, and its relative molecular mass is 20000; nanocellulose crystals were purchased from Shansi Technology, the model is cellulose nanocrystals (powder), and its length×diameter is 200×10nm; dextran was purchased from McLean, the model is dextran 70, and its weight average molecular weight is 70000; polyethylene imine was purchased from McLean, the model is 25-99% polyethylene imine aqueous solution, and its weight average molecular weight is 3000-100000.

[0052] The test methods used in the following embodiments include:

[0053] The adsorption performance of the adsorption material is reflected by testing the main properties of each test sample respectively; the main properties tested in this application include adsorption capacity, swelling rate, adsorption breakthrough curve, regeneration performance, etc.

[0054] 1) Adsorption capacity test;

[0055] The adsorption amount was calculated by the fixed bed method, where a certain concentration of CO2 was passed through a fixed bed filled with a sample purged with humid nitrogen at a flow rate of 20 mL / min for 12 hours, and the outlet CO2 concentration was continuously measured by gas chromatography to obtain a breakthrough curve, which was calculated by Formula 1;

[0056]

[0057] Among them, q t (mmol / g) is the amount of CO2 adsorbed at time t, t (min) is the adsorption time, c in and c eff (vol%) are the inflow concentration and outflow concentration of CO2, V (mL / min) is the total gas flow rate, and m is the mass of the dry sample.

[0058] 2) Swelling rate, adsorption amount and adsorption breakthrough curve test

[0059] The swelling ratio was determined by calculation according to Formula 2;

[0060] S r =(m s -m0)÷m0 Formula 2

[0061] Where S r (%) is the swelling rate, m s (g) is the mass after swelling, and m0(g) is the mass before swelling.

[0062] 3) Regeneration performance test

[0063] The adsorbed sample was placed in an adsorption column with circulating water in the interlayer, purged with nitrogen at a flow rate of 150 mL / min and heated with circulating water at 90°C. After maintaining for 30 minutes to complete the thermal regeneration of the adsorbent, the adsorption capacity was tested repeatedly.

[0064] Example 1

[0065] This embodiment provides a method for preparing a spherical solid amine CO2 adsorbent material, which comprises the following steps:

[0066] S1) Weigh 1.20 g polyethylene glycol (PEG, Mn =2.0×10 4 ) and 30 mg of nanocellulose crystals (CNC, 200×10 nm, length×diameter), then 5.00 g of deionized water was added, and the mixture was stirred and mixed to obtain a first mixed aqueous solution containing nanocellulose crystals and polyethylene glycol;

[0067] S2) Weigh 0.60 g of dextran (Dex, M n =7.0×10 4 ) and 6.43 g of a 35% polyethyleneimine aqueous solution (PEI, MW=100000), then 5.82 g of deionized water were added, and the mixture was stirred and mixed to obtain a second mixed aqueous solution containing polyethyleneimine and dextran;

[0068] S3) adding the first mixed aqueous solution (all) obtained in step S1) to the second mixed aqueous solution (all) obtained in step S2) to mix evenly, stirring at 500 rpm for 30 minutes, then adding 0.45 g of ethylene glycol diglycidyl ether (EGDE), keeping stirring, and performing cross-linking reaction at 25°C for 24 hours. After the reaction, using deionized water and anhydrous ethanol to perform Soxhlet extraction and washing for 60 hours and 36 hours respectively, the washed product is placed in deionized water for solvent exchange for 12 hours, and then the solvent exchanged product is frozen in a refrigerator at -15°C for 24 hours and then placed in a freeze dryer for freeze drying for 48 hours to obtain a spherical solid amine CO2 adsorption material.

[0069] The present application also performs a performance test on the spherical solid amine CO2 adsorbent material prepared in step S3), specifically: after the reaction in step S3, take out the spherical solid amine CO2 adsorbent material obtained in step S3) (labeled as 0.15PEI-0.2EGDE, wherein the 0.15 in front of PEI represents the mass ratio of PEI to deionized water in the entire reaction system, and the 0.2 in front of EGDE represents the mass ratio of EGDE to PEI, and the subsequent naming follows this rule) and pure polyethyleneimine (PEI), and perform Fourier transform infrared spectroscopy analysis on the two. The analysis results are shown in Figure 1 ,from Figure 1 It can be seen that: 1048cm -1 and 1099cm -1 The peaks at 1459cm are the symmetric stretching vibration peak and asymmetric stretching vibration peak of -COC-, and the peaks are slightly enhanced in the 0.15PEI-0.2EGDE spectrum. -1 and 1572cm -1The peaks at 1640cm in the 0.15PEI-0.2EGDE spectrum are attributed to the stretching vibration of the -NH-R bond and the bending vibration of the R-NH2 bond in the plane. After cross-linking, the intensity of the latter decreases, corresponding to the process of primary amines becoming secondary amines after cross-linking. -1 The newly appeared peak at is considered to be the C=O stretching vibration peak of carbamate formed by the adsorbent adsorbing CO2 in the air. In summary, it is proved that PEI and EGDE successfully undergo a ring-opening reaction and cross-link to generate 0.15PEI-0.2EGDE.

[0070] Example 2

[0071] This embodiment provides a method for preparing a spherical solid amine CO2 adsorbent material, which is basically the same as that of embodiment 2, except that the stirring rate in step S3) is different. The SEM images of the adsorbent materials prepared at different stirring rates are as follows: Figure 2 As shown, from Figure 2 It can be seen that when the stirring rate is too low (200rpm and 300rpm), due to the high viscosity of the emulsion and the low solubility of the crosslinker in water, the crosslinker is easily over-concentrated locally, which makes the diameter distribution of the microspheres too large. When the stirring rate is too high (600rpm), the microsphere morphology is easily destroyed due to the excessive mechanical shear force. In summary, due to the presence of the crosslinker, the stirring rate will affect the particle size distribution and morphology of the microspheres. A moderate stirring rate (500rpm) is selected to obtain microspheres with uniform size and complete morphology; and the specific stirring rates are shown in Table 1:

[0072] Table 1 Experimental results of different stirring rates

[0073] Test Example 1 Test Example 2 Example 1 Test Example 3 Stirring speed (rpm) 200 300 500 600

[0074] Example 3

[0075] This embodiment provides a method for preparing a spherical solid amine CO2 adsorbent material, which is basically the same as that of Example 2, except that the weight average molecular weight of the polyethyleneimine in step S2) is different. The SEM images of the adsorbent materials prepared by polyethyleneimine with different weight average molecular weights are shown in FIG. Figure 3 As shown, from Figure 3It can be seen that the adsorbent obtained by cross-linking with low molecular weight PE I (MW = 3000, 10000, 18000 and 70000) is insufficient to form a regular microsphere morphology due to the low degree of cross-linking, while the adsorbent obtained by cross-linking with higher molecular weight PE I (MW = 100000) has a more regular microsphere morphology. Generally speaking, in the actual preparation process, the use of too high a molecular weight of PE I will lead to too high viscosity of the emulsion, thereby affecting the stability of the emulsion and the uniformity of the cross-linking reaction. However, in the water-in-water emulsion system, due to the presence of sufficient water in the two phases, the problem of too high viscosity of the emulsion caused by too high a molecular weight of PE I can be alleviated to a certain extent. Therefore, PE I with a molecular weight of 100000 was selected for cross-linking to prepare microspheres; and the specific weight average molecular weight is shown in Table 2:

[0076] Table 2 Experimental results of polyethyleneimine with different weight average molecular weights

[0077]

[0078] Example 4

[0079] This embodiment provides a method for preparing a spherical solid amine CO2 adsorbent material, which is basically the same as that of Embodiment 2, except that the mass ratio of polyethyleneimine to deionized water in the reaction system in step S2) is different, and the specific mass ratio is shown in Table 3:

[0080] Table 3: Mass ratio of polyethyleneimine (PEI) to water in emulsion

[0081]

[0082] Example 5

[0083] This embodiment provides a method for preparing a spherical solid amine CO2 adsorbent material, which is basically the same as that of Example 2, except that the amount of ethylene glycol diglycidyl ether added to the reaction system is different, and the mass ratio of polyethyleneimine (PEI) to ethylene glycol diglycidyl ether (EGDE) is different. The SEM images of the adsorbent materials prepared by different proportions of ethylene glycol diglycidyl ether and different mass ratios of polyethyleneimine (PEI) to ethylene glycol diglycidyl ether (EGDE) are as follows: Figure 4 As shown, from Figure 4 It can be seen that only when the cross-linking agent concentration is greater than 0.1g / g PEI, the adsorbent can reach a sufficiently high degree of cross-linking to form a complete microsphere morphology; and the specific addition amount and mass ratio are shown in Table 4:

[0084] Table 4 Mass ratio of polyethyleneimine (PEI) to ethylene glycol diglycidyl ether (EGDE)

[0085] Test Example 10 Example 1 Test Example 11 Test Example 12 EGDE(g) 0.225 0.45 0.9 1.35 EGDE:PEI 0.1:1 0.2:1 0.4:1 0.6:1

[0086] Performance test example:

[0087] The present application also conducts performance tests on the adsorption materials prepared in each embodiment, specifically:

[0088] 1) Adsorption capacity test

[0089] This test measures the adsorption capacity of the adsorbent material prepared by adding different mass concentrations of polyethyleneimine into the system. The results are as follows: Figure 5 As shown, from Figure 5 It can be seen that as the PEI concentration increases, the adsorption capacity of the adsorbent increases. The amine efficiency of 0.12PEI-0.2EGDE and 0.15PEI-0.2EGDE is similar, but the amine efficiency of 0.10PEI-0.2EGDE is lower than the other two. From the perspective of adsorption kinetics, as the PEI concentration increases, the breakthrough time of the material is delayed and the time to reach equilibrium after the breakthrough is also reduced, which is manifested as a continuously increasing penetration saturation ratio. All of the above can be attributed to the increase in the final cross-linking density brought about by the high PEI concentration.

[0090] 2) Swelling rate, adsorption amount and adsorption breakthrough curve test

[0091] In this test, the swelling rate, adsorption amount and adsorption breakthrough curve of the adsorbent material prepared by adding different proportions of ethylene glycol diglycidyl ether or different mass ratios of polyethyleneimine (PEI) and ethylene glycol diglycidyl ether (EGDE) into the system were measured. The results are shown in Table 5 and Figure 6 As shown:

[0092] Table 5: Statistical table of swelling ratio and adsorption amount of adsorbent materials prepared in Experimental Examples 13-16

[0093] Swelling rate (%) Adsorption capacity (mmol / g) Test Example 10 296.38 9.99 Example 1 271.40 9.28 Test Example 11 230.80 7.61 Test Example 12 198.50 6.88

[0094] From Table 5 and Figure 6It can be seen that with the increase in the amount of cross-linking agent used, the adsorbent material introduces more hydrophobic skeletons, and its maximum adsorption capacity and swelling also decrease. Although the maximum adsorption capacity of 0.15PEI-0.1EGDE is slightly higher than that of 0.15PEI-0.2EGDE, by comparing the adsorption breakthrough curves of the two, 0.15PEI-0.2EGDE obviously has a higher penetration saturation ratio (0.81), that is, better adsorption kinetics, which is due to the complete microsphere morphology of 0.15PEI-0.2EGDE. The introduction of water during the swelling process not only changes the adsorption mechanism of the adsorbent material for CO2, but also increases the adsorption amount of CO2 by 1 mol of amine from 0.5 mol (dry state) to 1.0 mol (wet state) with the participation of water. In addition, during the swelling process, due to the low degree of cross-linking of the adsorbent material, the polymer chain segment is relatively soft, and its freedom of movement is higher, thereby exposing more adsorption sites inside the microspheres, which is conducive to the rapid diffusion of CO2.

[0095] 3) Regeneration performance test

[0096] This test takes Example 1 as an example, and the regeneration performance of the prepared adsorption material is tested at 90°C. The results are as follows: Figure 7 As shown in the figure, it can be seen that after 10 adsorption-desorption cycles, the regenerated adsorption capacity of the adsorbent material can reach 8.78 mmol / g.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a spherical solid ammonia CO2 adsorbent material, characterized in that: In a water-in-water emulsion template formed by dextran, polyethylene glycol and nanocellulose crystals, polyethylene imine is used as a matrix and then cross-linked and solidified with ethylene glycol diglycidyl ether.

2. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 1, characterized in that: The specific steps include: S1) adding polyethylene glycol and nanocellulose crystals into deionized water and mixing them evenly to obtain a first mixed aqueous solution containing nanocellulose crystals and polyethylene glycol; S2) adding the dextran and polyethyleneimine solution into deionized water and mixing them evenly to obtain a second aqueous solution containing polyethyleneimine and dextran; S3) adding the first mixed aqueous solution obtained in step S1) to the second mixed aqueous solution obtained in step S2) and mixing them evenly, then adding ethylene glycol diglycidyl ether to carry out a cross-linking reaction, and after the reaction is completed, Soxhlet extraction, washing, solvent exchange, and freeze-drying are performed to obtain a spherical solid amine CO2 adsorption material.

3. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 1, characterized in that: The mass ratio of polyethylene glycol, dextran and nanocellulose crystals in step S1 is 0.5-1.5 g: 0.3-0.8 g: 20-40 mg.

4. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 1, characterized in that: The mass ratio of dextran to polyethyleneimine in step S2) is 0.6:(1.50-2.25).

5. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 4, characterized in that: The average molecular weight of the polyethylene glycol is 15000-25000, the length×diameter of the nanocellulose crystal is (150-250)×(5-15) nm, and the average molecular weight of the dextran is 60000-80000.

6. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 1, characterized in that: The mass ratio of the polyethyleneimine to ethylene glycol diglycidyl ether is 1:(0.1-0.6).

7. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 1, characterized in that: The mass ratio of the polyethyleneimine to the deionized water in the reaction system is 1:(6.7-10).

8. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 4, characterized in that: The weight average molecular weight of polyethyleneimine in the polyethyleneimine solution is 3000-100000, and the mass fraction of the polyethyleneimine solution is 30-40%.

9. The method for preparing a spherical solid ammonia CO2 adsorbent material according to claim 4, characterized in that: In step S3), the mixing is carried out by stirring at a speed of 200-600 rpm and for a time of 20-40 min; and the reaction temperature of the cross-linking reaction is 25° C. and the reaction time is 24 h.

10. A spherical solid ammonia CO2 adsorption material prepared according to any one of the preparation methods of claims 1 to 9, characterized in that: The solid ammonia CO2 adsorption material is spherical, and its expansion rate is 198-396%.

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