A kaolin-based solid amine carbon dioxide adsorbent and its preparation method

Abstract

The present invention relates to the technical field of carbon dioxide adsorbents, and particularly relates to a kaolin-based solid amine carbon dioxide adsorbent and a preparation method thereof. The preparation method includes the following steps: S1. Kaolin is modified by using NaOH solution and HCl solution in sequence to obtain alkali-acid modified kaolin; S2. The alkali-acid modified kaolin is added to an ethanol solution of tetraethylenepentamine, and after stirring and reacting, it is dried and ground to obtain the kaolin-based solid amine carbon dioxide adsorbent. In the present invention, appropriately acid-base dual-treated kaolin improves the specific surface area without destroying the crystal structure, thereby promoting the organic amine loading amount, and further improving the carbon dioxide adsorption performance to the best.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide adsorbents, and particularly to a kaolin-based solid amine carbon dioxide adsorbent and a preparation method thereof. Background Art

[0002] In existing CO2 capture technologies, the efficient, energy-saving and environmentally friendly capture materials mainly include liquid amines, carbon-based adsorbents, zeolite-based adsorbents, metal-organic framework (MOFs)-based adsorbents, porous polymer-based adsorbents, and amine-functionalized solid adsorbents, etc. At present, liquid amines are highly corrosive to equipment, volatile, and have high renewable energy consumption; due to only physical adsorption in porous materials themselves, the adsorption capacity and adsorption rate are limited, and the adsorption stability needs to be further improved; amine-functionalized solid adsorbents have attracted much attention due to their low cost, physical-chemical synergistic adsorption, low required energy, and good stability.

[0003] For example: Chinese Patent with Application No. 202211720326.2 discloses a carbon-based solid amine carbon dioxide adsorbent and a preparation method thereof. The carbon-based solid amine carbon dioxide adsorbent is prepared by grafting a modifier onto a carbon-based carrier and then impregnating and modifying with an impregnating modifier and a surfactant for dispersion. Using mesoporous carbon or carbon nanotubes as carriers, ultrasonic-assisted grafting modification is first carried out, and then impregnation modification and addition of a surfactant for dispersion are adopted. The prepared adsorbent has a high amino utilization rate, good adsorption performance for CO2, and significantly improved cycle stability of the adsorbent. However, its carrier cost is high and the preparation process is complex.

[0004] Chinese Patent with Application No. 202111645042.7 discloses a preparation method of a gasification slag-based solid amine carbon dioxide adsorbent, belonging to the technical field of carbon dioxide adsorbents. An organic amine-gasification slag composite adsorbent is prepared by loading one or a mixture of organic amines such as polyethyleneimine, pentaethylenehexamine, and ethanolamine. The preparation method of the composite adsorbent is: dissolving the organic amine in an ethanol solution, adding gasification ash slag residual carbon material, fully stirring and impregnating, evaporating the solvent in a water bath at 75 °C, and drying overnight to obtain the amine-loaded gasification ash slag residual carbon composite adsorbent. However, the CO2 adsorption performance of the prepared amine-loaded gasification ash slag residual carbon composite adsorbent is average. Summary of the Invention

[0005] The purpose of the present invention is to propose a kaolin-based solid amine carbon dioxide adsorbent and a preparation method thereof in view of the above deficiencies of the prior art. On the premise of retaining the good kaolin structure, the specific surface area of kaolin is increased to load organic amines, and a high-performance carbon fixation material can be obtained.

[0006] A preparation method of a kaolin-based solid amine carbon dioxide adsorbent of the present invention comprises the following steps:

[0007] S1. Modify kaolin with NaOH solution and HCl solution in sequence to obtain alkali-acid modified kaolin;

[0008] S2. Add the alkali-acid modified kaolin into an ethanol solution of tetraethylenepentamine, stir and react, then dry and grind to obtain the kaolin-based solid amine carbon dioxide adsorbent.

[0009] Further, the specific process of modifying with NaOH solution is: add kaolin into a NaOH solution with a concentration of 15-20%, stir and react in a water bath, then centrifuge, wash, dry and grind to obtain alkali-modified kaolin.

[0010] Further, the mass-volume ratio of kaolin to NaOH solution is 5g:50mL.

[0011] Further, the specific process of modifying with HCl solution is: stir and react the alkali-modified kaolin with an HCl solution with a concentration of 1-6M in a water bath, then centrifuge, wash, dry and grind to obtain alkali-acid modified kaolin.

[0012] Further, the mass-volume ratio of alkali-modified kaolin to HCl solution is 1-2g:15mL.

[0013] Further, the water bath reaction temperature for modifying with NaOH solution and HCl solution is 80-85°C.

[0014] Further, the purity of kaolin is 85-99%.

[0015] Further, the mass ratio of alkali-acid modified kaolin to organic amine is 1:0.1-0.9.

[0016] Further, in step S2, the stirring speed of the stirring reaction is 100-300r / min, and the reaction time is 1-12h.

[0017] A kaolin-based solid amine carbon dioxide adsorbent prepared by the preparation method as described above.

[0018] The present invention uses appropriately double acid-base treated kaolin to increase the specific surface area without destroying the crystal structure, thereby promoting the organic amine loading amount, and further improving the carbon dioxide adsorption performance to the best. Inappropriate acid-base treatment will destroy the structure of kaolin, the specific surface area increases, and loading organic amine will improve the carbon dioxide adsorption performance to a certain extent, but it is much worse than that of kaolin without destroying the crystal structure.

[0019] The kaolin in the kaolin-based solid amine carbon dioxide adsorbent prepared by the present invention still retains the intrinsic structure of kaolin after treatment and has a high specific surface area. The intensity of the main peak (001) of the treated kaolin is >800, and the broad peak of the amorphous substance is not obvious. The specific surface area >25 m 2 / g. The carbon dioxide adsorption capacity of the treated kaolin loaded with 10-90% of TEPA is increased to 35-153 mg / g.

[0020] The treated kaolin of the present invention is used to load organic amine (TEPA) by impregnation method to prepare a carbon dioxide adsorbent. Through theoretical calculation, it is proved that among the four organic amines, TEPA has the largest interaction energy with kaolinite and the most stable combination. TEPA has the largest adsorption energy with CO2, and the adsorption performance of this organic amine is the best. Description of the Drawings

[0021] Figure 1 X-ray powder diffraction pattern of kaolin with a purity of 85.9% in Example 1 ;

[0022] Figure 2 Prepared in Example 1 X-ray powder diffraction pattern;

[0023] Figure 3 Theoretical calculation interaction energy diagrams of kaolinite and ethylenediamine (EDA), polyethyleneimine (PEI), diethylenetriamine (DETA) and tetraethylenepentamine (TEPA);

[0024] Figure 4 Theoretical calculation adsorption energy diagrams of ethylenediamine (EDA), polyethyleneimine (PEI), diethylenetriamine (DETA) and tetraethylenepentamine (TEPA) for adsorbing CO2;

[0025] Figure 5 Carbon dioxide adsorption capacity comparison diagram of the adsorbent prepared in Example 1;

[0026] Figure 6 Prepared in Example 1 Cycling performance;

[0027] Figure 7 Prepared in Example 1 Infrared spectra before and after adsorbing CO2;

[0028] Figure 8 Prepared in Example 1 and X-ray photoelectron spectroscopy comparison diagram;

[0029] Figure 9 Prepared in Example 1 X-ray photoelectron spectroscopy of N1s;

[0030] Figure 10 is the X-ray powder diffraction pattern of kaolin ZT-1 with a purity of 98% in Example 2;

[0031] Figure 11 is the X-ray powder diffraction pattern of ZT-1-HCl-NaOH prepared in Example 2;

[0032] Figure 12 is the comparison chart of carbon dioxide adsorption capacity of the adsorbent prepared in Example 2;

[0033] Figure 13 is the X-ray powder diffraction pattern of ZT-1-HCl-NaOH-TEPA-80% prepared in Example 3;

[0034] Figure 14 is prepared in Comparative Example 1 and the X-ray powder diffraction pattern of ZT-1-HCl-NaOH;

[0035] Figure 15 is prepared in this Comparative Example 1 and the comparison chart of carbon dioxide adsorption capacity of ZT-1-HCl-NaOH. Detailed implementation manners

[0036] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0037] Example 1:

[0038] This example prepares a kaolin-based solid amine material

[0039] Take 5 g of kaolin with a purity of 85.9% Add 50 mL of 15% NaOH to a water bath at 85 °C, stir at a speed of 200 r / min, and react for 1 h. After the reaction, centrifuge and separate at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain

[0040] Then take 2 g of Add 15 mL of 6 M HCl to a water bath at 80 °C, stir at a speed of 200 r / min, and react for 80 min. After the reaction, centrifuge and separate at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain

[0041] Then, 1 g of was separately added to 0.1 - 0.8 g of tetraethylenepentamine (TEPA) in 20 mL of ethanol in which it had been dissolved, and the stirring speed was 200 r / min. The reaction was carried out for 12 h. After the reaction, it was placed in an oven at 80 °C and dried for 12 h, cooled to room temperature, taken out and thoroughly ground to obtain a powdery sample.

[0042] The CO₂ adsorption performance of

[0043]

[0044] was measured by a thermogravimetric analyzer. The instrument was produced by Netzsch of Germany, and the model was STA449C. The protective atmosphere was set as N₂ (99.99%), and the purging atmosphere was 50 mL / min of CO₂ (99.99%). About 10 mg of the sample was placed in an alumina crucible, heated starting from room temperature at a rate of 10 °C / min to 100 °C, and kept adsorbed for 60 min in a 50 mL / min N₂ atmosphere to remove interference sources. After cooling to the selected temperature, the adsorption atmosphere of CO₂ was turned on, and it was kept adsorbed for 120 min, and the adsorption curve was recorded. The CO₂ adsorption capacity of the material is shown in Equation 1 - 1:

[0043]

[0044] See Appendix Figure 1 , which is the X-ray powder diffraction pattern of kaolin with a purity of 85.9% for the technical solution of this example. The results show that the main phase of kaolin is kaolinite, and there are also microcline impurity peaks.

[0045] See Appendix Figure 2 , which is the X-ray powder diffraction pattern of prepared according to the technical solution of this example. The crystal structure of kaolinite was not destroyed and the broad peak of amorphous matter was not obvious.

[0046] See Table 1, which is the structural characteristics of prepared according to the technical solution of this example. The specific surface area of 2 / g.

[0047] See Appendix Figure 3 , which is the theoretical calculation interaction energy map of kaolinite with ethylenediamine (EDA), polyethyleneimine (PEI), diethylenetriamine (DETA) and tetraethylenepentamine (TEPA). It shows that TEPA is most likely to have a strong interaction with the kaolin crystal plane. It shows that TEPA among the four organic amines is the most likely to combine with kaolinite and is easy to be loaded onto kaolinite. Therefore, kaolin can be used as an excellent carrier for loading TEPA.

[0048] See the appendix Figure 4 , which is the theoretical calculated adsorption energy diagram of ethylene diamine (EDA), polyethyleneimine (PEI), diethylenetriamine (DETA) and tetraethylenepentamine (TEPA) for CO2 adsorption in the technical solution of this embodiment. According to the adsorption energy ranking, TEPA > EDA > DETA > PEI. Therefore, from the perspective of organic amine adsorption of CO2, theoretical calculations show that TEPA is the best loading for CO2 adsorption.

[0049] See the appendix Figure 5 , which is the comparison diagram of CO2 adsorption capacity of prepared according to the technical solution of this embodiment. As the TEPA loading increases, the CO2 adsorption capacity of first increases and then decreases. The increase in loading will cause 2 the pore blockage of , which is not conducive to the diffusion and adsorption of CO

[0050] See the appendix Figure 6 , which is the CO2 cycle performance of prepared according to the technical solution of this embodiment. The cycle experiment adsorbs at 85 °C and desorbs at 110 °C. After 15 cycles, the CO2 adsorption capacity remains at 105.18 mg / g.

[0051] See the appendix Figure 7 , which is the infrared spectrogram of before and after CO2 adsorption prepared according to the technical solution of this embodiment. Infrared spectroscopy was used to successfully discover the formation of N-H (3374, 3285 and 1570 cm -1 ) and C-H (1475 cm -1 ) peaks, which indicates that TEPA is indeed loaded on kaolin. After CO2 adsorption, the C-O (1416 cm -1 ) peak appears, which indicates that has adsorbed CO2. The reaction equations for the primary and secondary amines contained in TEPA reacting with CO2 are as shown in 1-2 and 1-3.

[0052]

[0053] See the appendix Figure 8 and Figure 9 , according to the technical solution of this embodiment and XPS diagrams. After modification with TEPA, sharp XPS peaks appear at the binding energy centers of 285.3 (C 1s), 399.5 eV (N 1s) and 532 eV (O 1s), which indicates that There are amine groups in the sample. To further analyze the chemical properties of N, Figure 9 we studied the N 1s region in the high-resolution XPS spectrum, pointing out chemically different N species in it, and their N 1s binding energies are approximately 398.8 eV, 399.4 eV, and 401.0 eV, respectively. The main peak of N 1s with a binding energy of 398.9 eV can be attributed to C-NH-C. The two peaks at 399.4 eV and 401.0 eV can be attributed to -NH2 and -NH from the amine group, respectively. 3+ This is in line with the primary and secondary amines of TEPA.

[0054] The CO2 solid adsorbent loaded with TEPA on low-purity kaolin after acid-base treatment provided by the present invention After treatment, the intensity of the main peak (001) of the low-purity kaolin is >800 and the broad peak of the amorphous substance is not obvious. After its specific surface area increases and 60% of TEPA is loaded, the CO2 adsorption capacity reaches a maximum of 134.44 mg / g.

[0055] Example 2:

[0056] This example prepares the kaolin-based solid amine material ZT-1-HCl-NaOH-TEPA-30-80%.

[0057] Take 5 g of kaolin ZT-1 with a purity of 98% and add 50 mL of 15% NaOH in a water bath at 85 °C, stir at a speed of 200 r / min, and react for 1 h. After the reaction, centrifuge at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain ZT-1-NaOH.

[0058] Then take 2 g of ZT-1-NaOH and add 15 mL of 6 M HCl in a water bath at 80 °C, stir at a speed of 200 r / min, and react for 80 min. After the reaction, centrifuge at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain ZT-1-HCl-NaOH.

[0059] Then add 1 g of ZT-1-HCl-NaOH to 0.3 - 0.8 g of tetraethylenepentamine (TEPA) dissolved in 20 mL of ethanol, stir at a speed of 200 r / min, and react for 12 h. After the reaction, put it in an oven at 80 °C to dry for 12 h, cool to room temperature, take it out and grind it thoroughly to obtain the powdery sample ZT-1-HCl-NaOH-TEPA-30 - 80%.

[0060] The CO2 adsorption performance of ZT-1-HCl-NaOH-TEPA at 30-80% was measured by a thermogravimetric analyzer. The instrument used was Netzsch from Germany, model STA449C. The protective atmosphere was set as N2 (99.99%), and the purge atmosphere was 50 mL / min CO2 (99.99%). Approximately 10 mg of the sample was placed in an alumina crucible and heated starting from room temperature at a rate of 10 °C / min to 100 °C. It was kept in a 50 mL / min N2 atmosphere for 60 min to remove interference sources, then cooled to the selected temperature and the CO2 adsorption atmosphere was opened, and it was kept for adsorption for 120 min, and the adsorption curve was recorded. The CO2 adsorption capacity of the material is shown in Equation 1-1.

[0061] See Appendix Figure 10 , which is the X-ray powder diffraction pattern of kaolin ZT-1 with a purity of 98% according to the technical solution of this example. The results show that there are fewer impurity peaks, mainly kaolinite.

[0062] See Appendix Figure 11 , which is the X-ray powder diffraction pattern of ZT-1-HCl-NaOH prepared according to the technical solution of this example. The kaolinite crystal structure of ZT-1-HCl-NaOH is not destroyed.

[0063] See Table 2, which is the structural characteristics of ZT-1-HCl-NaOH prepared according to the technical solution of this example. The specific surface area of ZT-1-HCl-NaOH is 239.61 m 2 / g.

[0064] See Appendix Figure 12 , which is the comparison chart of the CO2 adsorption capacity of ZT-1-HCl-NaOH-TEPA from 30% to ZT-1-HCl-NaOH-TEPA 80% prepared according to the technical solution of this example. With the increase of the TEPA loading amount, the CO2 adsorption capacity of ZT-1-HCl-NaOH also increases first and then decreases. The CO2 adsorption capacity of ZT-1-HCl-NaOH-70% is the largest, which is 153 mg / g.

[0065] The CO2 solid adsorbent ZT-1-HCl-NaOH-TEPA with 30-80% TEPA loaded on high-purity kaolin after acid-base treatment provided by the present invention. The intensity of the main peak (001) of the treated high-purity kaolin > 800, and its specific surface area increases to 239.61 m 2 / g. After loading 70% of TEPA, the CO2 adsorption capacity reaches a maximum of 153 mg / g. Compared with Example 1, it is proved that on the premise of retaining a good kaolin structure, increasing the specific surface area and loading more organic amine (TEPA) can obtain a high-performance carbon fixation material.

[0066] Example 3:

[0067] In this example, the kaolin-based solid amine material ZT-1-HCl-NaOH-TEPA-80% was prepared.

[0068] Take 5 g of kaolin ZT-1 with a purity of 98% and add 50 mL of 20% NaOH in a water bath at 85 °C. Stir at a speed of 200 r / min for 1 h. After the reaction, centrifuge at a speed of 8000 r / min and wash with deionized water until the pH is neutral. Then place it in an oven at 80 °C to dry, cool to room temperature, and take it out and grind thoroughly to obtain ZT-1-NaOH.

[0069] Then take 2 g of ZT-1-NaOH and add 15 mL of 6 M HCl in a water bath at 80 °C. Stir at a speed of 200 r / min for 80 min. After the reaction, centrifuge at a speed of 8000 r / min and wash with deionized water until the pH is neutral. Then place it in an oven at 80 °C to dry, cool to room temperature, and take it out and grind thoroughly to obtain ZT-1-HCl-NaOH.

[0070] Then add 1 g of ZT-1-HCl-NaOH to 0.8 g of tetraethylenepentamine (TEPA) in 20 mL of ethanol in which it has been dissolved. Stir at a speed of 200 r / min for 12 h. After the reaction, place it in an oven at 80 °C to dry for 12 h, cool to room temperature, and take it out and grind thoroughly to obtain the powdery sample ZT-1-HCl-NaOH-TEPA-80%.

[0071] The CO2 adsorption performance of ZT-1-HCl-NaOH-TEPA-80% was measured by a thermogravimetric analyzer. The instrument was selected from Netzsch of Germany, model STA449C. Set the protective atmosphere as N2 (99.99%), the purge atmosphere as 50 mL / min CO2 (99.99%). Take about 10 mg of the sample in an alumina crucible, start heating from room temperature, and heat up to 100 °C at a rate of 10 °C / min. Keep adsorbing for 60 min under a 50 mL / min N2 atmosphere to remove interference sources. After cooling to the selected temperature, turn on the adsorption atmosphere CO2 and keep adsorbing for 120 min, and record the adsorption curve. The CO2 adsorption capacity of the material is shown in Equation 1-1.

[0072] See Appendix Figure 13 , which is the X-ray powder diffraction pattern of ZT-1-HCl-NaOH prepared according to the technical solution of this example. The kaolinite crystal structure of ZT-1-HCl-NaOH was not destroyed.

[0073] The high-purity kaolin-supported TEPA CO2 solid adsorbent ZT-1-HCl-NaOH-TEPA-80% provided by the present invention. After treatment, the intensity of the main peak (001) of the high-purity kaolin is >800, and its specific surface area increases to 266.49 m 2 / g. After loading 80% of TEPA, the CO2 adsorption capacity reaches a maximum of 166.67 mg / g. Compared with Example 2, it is proved that on the premise of retaining the good kaolin structure, adjusting the steps of acid-base treatment to further increase the specific surface area and load more organic amine (TEPA) can obtain a high-performance carbon fixation material.

[0074] Comparative Example 1:

[0075] This comparative example prepares kaolin-based solid amine materials and ZT-1-HCl-NaOH-80%.

[0076] Take 5 g of three different purities of kaolin raw ore (purity is 67.5%), and ZT-1, add 50 mL of 25% NaOH in a water bath at 85 °C, stir at a speed of 200 r / min, and react for 1 h. After the reaction, centrifuge and separate at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain and ZT-1-NaOH.

[0077] Then take 2 g of and ZT-1-NaOH, add 30 mL of 6 M HCl in a water bath at 80 °C, stir at a speed of 200 r / min, and react for 80 min. After the reaction, centrifuge and separate at a speed of 8000 r / min, wash with deionized water until the pH is neutral, put it in an oven at 80 °C to dry, cool to room temperature, take it out and grind it thoroughly to obtain and ZT-1-HCl-NaOH.

[0078] Then add 1 g of and ZT-1-HCl-NaOH to 0.8 g of tetraethylenepentamine (TEPA) added to 20 mL of ethanol in which it has been dissolved, stir at a speed of 200 r / min, and react for 12 h. After the reaction, put it in an oven at 80 °C to dry for 12 h, cool to room temperature, take it out and grind it thoroughly to obtain a powdery sample and ZT-1-HCl-NaOH-TEPA-80%.

[0079] The CO2 adsorption performance of ZT-1-HCl-NaOH-TEPA-80% was measured by a thermogravimetric analyzer. The instrument used was Netzsch from Germany, model STA449C. The protective atmosphere was set as N2 (99.99%), and the purge atmosphere was 50 mL / min CO2 (99.99%). About 10 mg of the sample was placed in an alumina crucible and heated from room temperature at a rate of 10 °C / min to 100 °C. It was kept in an atmosphere of 50 mL / min N2 for 60 min to remove interference sources. After cooling to the selected temperature, the adsorption atmosphere CO2 was opened, and it was kept for adsorption for 120 min, and the adsorption curve was recorded. The CO2 adsorption capacity of the material is shown in Equation 1-1.

[0080] See Appendix Figure 14 , which was prepared according to the technical solution of this comparative example and the X-ray powder diffraction patterns of ZT-1-HCl-NaOH. After alkali-acid treatment, the structures of kaolin were all destroyed, the main peaks disappeared, and the crystallinity became poor, showing a broad peak of amorphous substances. In terms of intensity the kaolin structure of

[0081] See Table 3, which are the structural characteristics of prepared according to the technical solution of this example and ZT-1-HCl-NaOH. 2 The specific surface area of is 405.91 m 2 / g, 2 the specific surface area of is 343.23 m

[0082] See Appendix Figure 15 , which was prepared according to the technical solution of this comparative example and the comparison chart of CO2 adsorption capacity of ZT-1-HCl-NaOH. For and ZT-1-HCl-NaOH, TEPA of 80% was loaded under the same conditions. The CO2 adsorption capacity is ranked as follows: ZT-1-HCl-NaOH, 122.58 mg / g > 79.88 mg / g > 70.67 mg / g. The 2 with a smaller specific surface area of 343.23 m instead has the largest CO2 adsorption capacity. This is related to the layered structure of kaolin. The lowest structural damage and the best retention of crystal structure are reflected in XRD. Compared with Example 1 and Example 2, it can also be verified that when the kaolin structure is damaged and there is a broad peak, the CO2 adsorption capacity of kaolin with a high specific surface area for loading TEPA is also lower than that of kaolin with a complete structure and a low specific surface area loaded with TEPA.

[0083] The CO2 solid adsorbent of TEPA loaded on kaolin after high-concentration acid-base treatment provided in this Comparative Example 1 and ZT-1-HCl-NaOH-80%. The CO2 adsorption capacities of ZT-1-HCl-NaOH-80% are 79.88 mg / g, 122.58 mg / g, and 70.67 mg / g respectively. Treating kaolin with high-concentration acid and base causes its structure to collapse and the specific surface area to increase. Although it can still load TEPA and have a certain CO2 adsorption performance. However, compared with kaolin loaded with TEPA with a complete structure and a small specific surface area after low-concentration treatment, the CO2 adsorption performance is not good.

[0084] Table 1

[0085]

[0086] Table 2

[0087]

[0088] Table 3

[0089]

[0090] Wherever not covered above, the prior art applies.

[0091] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a kaolin-based solid amine carbon dioxide adsorbent, characterized in that: The following steps are involved: S1, sequentially modifying kaolin with NaOH solution and HCl solution to obtain alkali-acid modified kaolin; S2, adding alkali-acid modified kaolin to an ethanol solution of tetraethylenepentamine, stirring for reaction, drying and grinding to obtain the kaolin-based solid amine carbon dioxide adsorbent; The specific process of NaOH solution modification is as follows: adding kaolin to NaOH solution and stirring in a water bath for reaction, centrifugation, washing, drying and grinding to obtain alkali-modified kaolin; wherein, when the purity of kaolin is 98-99%, the concentration of NaOH solution is 15-20%, and when the purity of kaolin is 85-85.9%, the concentration of NaOH solution is 15%; The specific process of HCl solution modification is as follows: after the alkali-modified kaolin is reacted with a 1-6 M HCl solution in a water bath, it is centrifuged, washed, dried and ground to obtain the alkali-acid-modified kaolin; The mass ratio of alkali-acid modified kaolin to tetraethylenepentamine is 1:0.3-0.9; The water bath reaction temperature for NaOH solution modification and HCl solution modification is 80-85°C; The kaolin-based solid amine carbon dioxide adsorbent retains the intrinsic structure of kaolin.

2. The preparation method according to claim 1, characterized in that: The mass volume ratio of kaolin and NaOH solution is 5 g:50 mL.

3. The preparation method according to claim 1, characterized in that: The mass volume ratio of alkali-modified kaolin to HCl solution is 1-2 g:15 mL.

4. The preparation method according to claim 1, characterized in that: In step S2, the stirring speed of the stirring reaction is 100-300 r / min, and the reaction is carried out for 1-12 h.

5. A kaolin-based solid amine carbon dioxide adsorbent prepared by the preparation method according to any one of claims 1 to 4.

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