CO2 adsorbent and preparation method thereof
By preparing a modified magnesium oxide-based adsorbent and utilizing the synergistic effect of fulvic acid and waste lithium iron phosphate battery powder, the problems of sintering and pore structure collapse of magnesium-based adsorbents were solved, achieving efficient CO2 adsorption and cycle stability, and improving adsorption performance.
Patent Information
- Application Number
- CN202511520384.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-04-29
- Filing Date
- 2025-10-23
- Publication Date
- 2026-01-23
AI Technical Summary
Traditional magnesium-based CO2 adsorbents suffer from sintering and pore structure collapse during the cyclic adsorption-desorption process due to the decomposition and regeneration of MgCO3, which limits their industrial application.
A primary complex was formed by mixing magnesium oxide precursor with fulvic acid and then adding waste lithium iron phosphate battery powder to prepare a modified magnesium oxide-based adsorbent. The adsorption performance and stability were improved by utilizing the synergistic effect of the active functional groups of fulvic acid and Li+ and Fe2+ in lithium iron phosphate batteries.
It significantly improved the CO2 adsorption capacity, adsorption rate and cycle stability of the adsorbent, delayed the sintering phenomenon of MgO, enhanced the specific surface area and alkaline site density, and improved the CO2 adsorption efficiency and recycling effect.
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Figure CN121372301A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of adsorbents, and particularly relates to a CO2 adsorbent and a preparation method thereof. BACKGROUND
[0002] With the acceleration of industrialization, the global carbon dioxide (CO2) emissions show explosive growth.
[0003] In the carbon capture, utilization and storage (CCUS) technology system, post-combustion capture is considered as the most potential scheme because it can directly modify existing industrial facilities. Among them, the adsorption technology based on magnesium cycle has become a research hotspot in recent years because of its high theoretical adsorption capacity (1100mg CO2 / g MgO), moderate reaction temperature (200-400℃) and wide raw material sources. However, the traditional magnesium-based adsorbent has a fatal defect: during the cyclic adsorption-desorption process, the MgO particles formed by the decomposition and regeneration of MgCO3 will seriously sinter and collapse the pore structure, which greatly limits its industrial application. SUMMARY
[0004] The purpose of the present application is to overcome the above-mentioned deficiencies, and provide a CO2 adsorbent and a preparation method thereof
[0005] To achieve the purpose, the present application provides a preparation method of a CO2 adsorbent, comprising the following steps:
[0006] S1: stirring and mixing magnesium oxide precursor and distilled water, and adding fulvic acid to form a mixed solution, stirring and heating the mixed solution to carry out hydration reaction, after the reaction is completed, drying to obtain a primary composite;
[0007] S2: calcining the primary composite, and grinding into porous magnesium oxide powder after calcination is completed;
[0008] S3: stirring and mixing the prepared powder and waste lithium iron phosphate battery powder in distilled water, stirring and heating the mixed solution to carry out hydration reaction, after the reaction is completed, drying to obtain a modified magnesium oxide-based adsorbent.
[0009] Preferably, the magnesium oxide precursor includes at least one of anhydrous magnesium oxalate, anhydrous magnesium citrate, magnesium lactate, magnesium ethoxide and magnesium acetate.
[0010] Preferably, in S1, the mass fraction of magnesium oxide precursor is 85% to 95%, and the mass fraction of fulvic acid is 5% to 15%.
[0011] Preferably, in S2, a muffle furnace is used for calcination, the calcination temperature is 450 to 550℃, the heating rate is 2 to 10℃ / min, and the holding time is 30min.
[0012] Preferably, in the S3, the mass fraction of the porous magnesium oxide powder in the magnesium oxide-based adsorbent is 90% to 95%, and the mass fraction of the waste and old lithium iron phosphate battery powder is 5% to 10%.
[0013] Preferably, the drying conditions of S1 and S3 are both drying at 80°C for 12 hours.
[0014] Preferably, in the S3, the preparation method of the waste and old lithium iron phosphate battery powder is: after the recovered waste and old lithium iron phosphate battery is disassembled, it is broken to a particle size of <1mm; then pyrolysis is performed, the battery particle size is controlled to be <1mm through physical crushing, the subsequent pyrolysis reaction contact area is increased, and it is ensured that the binder (PVDF) is fully removed; the nano-level powder is obtained through ball milling treatment (zirconium oxide ball, rotation speed 300rpm, 4h); the specific surface area is increased, and the uniform mixing and interface reaction with the porous magnesium oxide powder are promoted.
[0015] Preferably, the pyrolysis conditions for preparing the waste and old lithium iron phosphate battery powder are: pyrolysis is performed in a reducing atmosphere; the atmosphere is selected to avoid oxidation of iron elements and to retain the active chemical state thereof.
[0016] Preferably, the reducing atmosphere adopts N2 / H2 mixed gas.
[0017] The application also provides a CO2 adsorbent prepared by the above preparation method.
[0018] The technical scheme provided by the application has at least the following technical effects:
[0019] In the application, the fulvic acid molecules are complexed and ion-exchanged with the surface of the magnesium oxide precursor particles through active functional groups such as carboxyl groups and phenolic hydroxyl groups. This process not only regulates the crystallization behavior of the precursor, but also lays a foundation for the formation of the subsequent porous material, thereby improving the carbonation performance of MgO and delaying the occurrence of MgO sintering. The pores generated by the pyrolysis of fulvic acid increase the specific surface area and basic site density of MgO, which is beneficial to the adsorption of CO2 and further delays the occurrence of MgO sintering.
[0020] By introducing the waste and old lithium iron phosphate battery powder, Li + and Fe 2+ are introduced into the adsorption system, and the functional synergy and waste resource utilization are realized. Specifically, Li + can enter the MgO lattice as a dopant or be enriched on the surface of the MgO lattice, forming strong alkaline low-coordination O 2 sites, thereby increasing the basic site density and improving the chemical adsorption capacity of CO2; Fe 2+ can be oxidized to Fe3+ , the adsorption-desorption kinetics of CO2 is regulated by the change of valence state, the reaction activation energy is effectively reduced, and the adsorption rate is improved. In order to protect the activity of Li + and Fe 2+ , the pretreatment stage uses N2 / H2 mixed atmosphere, which effectively inhibits the oxidation of metal elements. The synergistic effect of the two significantly improves the adsorption capacity, adsorption rate and cycle stability of the adsorbent. BRIEF DESCRIPTION OF DRAWINGS
[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0022] Figure 1 It is a process flow diagram of the present application;
[0023] Figure 2(a) is an adsorption / cycle regeneration diagram in the first embodiment of the present application;
[0024] Figure 2(b) is a SEM diagram of the sample in the first embodiment of the present application;
[0025] Figure 3(a) is an adsorption / cycle regeneration diagram in the second embodiment of the present application;
[0026] Figure 3(b) is a SEM diagram of the sample in the second embodiment of the present application;
[0027] Figure 4(a) is an adsorption / cycle regeneration diagram in the third embodiment of the present application;
[0028] Figure 4(b) is a SEM diagram of the sample in the first comparative example of the present application;
[0029] Figure 5(a) is an adsorption / cycle regeneration diagram in the second comparative example of the present application;
[0030] Figure 5(b) is a SEM diagram of the sample in the second comparative example of the present application.
[0031] Adsorption conditions: 340℃, 100% CO2, 15min; Regeneration conditions: 420℃, 100% N2, 5min. DETAILED DESCRIPTION
[0032] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the embodiments of the present application, and cannot be understood as a limitation of the present application.
[0033] Example 1: The present embodiment discloses a method for preparing a CO2 adsorbent, as shown in Figure 1 The specific steps are as follows:
[0034] First, anhydrous magnesium oxalate is added to 60 ml of distilled water and mixed rapidly. Then, fulvic acid is added, and the beaker containing the mixed solution is placed on a magnetic stirrer for mixing and gradually increasing the temperature. The mass ratio of anhydrous magnesium oxalate to fulvic acid is 88:12. After hydration, the beaker is placed in a drying oven and dried at 80°C for 12 hours. After the sample is fully dried, it is transferred to a muffle furnace for calcination, with a calcination temperature of 500°C, a heating rate of 2°C / min, and a reaction time of 30 min. After calcination is complete, the sample is removed and ground in a mortar until a uniform powder sample (porous magnesium oxide powder) is formed.
[0035] Subsequently, the prepared powder is mixed with waste lithium iron phosphate battery powder and added to 60 ml of distilled water, and mixed rapidly.
[0036] The preparation method of the waste lithium iron phosphate battery powder is as follows: After the recovered waste lithium iron phosphate battery is disassembled, it is broken to a particle size of <1 mm; the battery particle size is controlled to be <1 mm through physical crushing, which increases the contact area of the subsequent pyrolysis reaction and ensures that the binder (PVDF) is fully removed; a nano-sized powder is obtained through ball milling treatment (zirconia balls, rotation speed 300 rpm, 4 h), and the pyrolysis process is carried out in a reducing atmosphere, specifically N2 / H2 mixed gas in the present embodiment.
[0037] The mass ratio of the mixture to the lithium iron phosphate battery powder is 95:5. Then, the beaker containing the mixed solution is placed on a magnetic stirrer for mixing and increasing the temperature. After hydration, the beaker is placed in a drying oven and dried at 80°C for 12 hours. After the sample is fully dried, the obtained solid is a modified magnesium oxide-based adsorbent.
[0038] As shown in FIG. 2(a), the adsorption rate of the composite MgO-based adsorbent in the present embodiment for carbon dioxide can reach 0.52 g CO2 / g adsorbent. After 20 cycles of use, its adsorption efficiency is 0.31 g CO2 / g adsorbent. As can be seen from the electron microscope image of the sample prepared as shown in FIG. 2(b), the sample has a porous structure and a large specific surface area, which is beneficial to the adsorption of carbon dioxide.
[0039] Example 2: The present embodiment discloses a method for preparing a CO2 adsorbent, as shown in Figure 1 The specific steps are as follows:
[0040] First, anhydrous magnesium citrate was added to 60 ml of distilled water and mixed rapidly. Then fulvic acid was added, and the beaker containing the mixed solution was placed on a magnetic stirrer for mixing and gradual temperature increase. The mass ratio of anhydrous magnesium citrate to fulvic acid was 92:8. After hydration, the beaker was placed in a drying oven at 80°C for 12 hours. After the sample was fully dried, the obtained solid mixture was taken out and calcined in a muffle furnace at a temperature of 500°C, a heating rate of 2°C / min, and a reaction time of 30 minutes. After calcination, the sample was taken out and ground in a mortar to obtain a uniform powder sample.
[0041] Next, the prepared powder and waste lithium iron phosphate battery powder were added to 60 ml of distilled water and mixed rapidly.
[0042] The lithium iron phosphate battery powder was prepared by disassembling the recovered waste lithium iron phosphate battery, crushing it to a particle size of <1 mm, controlling the battery particle size to <1 mm through physical crushing to increase the contact area for subsequent pyrolysis reaction and ensure that the binder (PVDF) is fully removed, and obtaining a nano-scale powder through ball milling (zirconia balls, rotation speed 300 rpm, 4 h) and pyrolysis in a reducing atmosphere, specifically N2 / H2 mixed gas in this embodiment.
[0043] The mass ratio of the mixture to the waste lithium battery powder was 95:5. Then, the beaker containing the mixed solution was placed on a magnetic stirrer for mixing and temperature increase. After hydration, the beaker was placed in a drying oven at 80°C for 12 hours. After the sample was fully dried, the obtained solid was taken out to obtain the modified magnesium oxide-based adsorbent.
[0044] As shown in FIG. 3(a), the carbon dioxide adsorption rate of the composite MgO-based adsorbent in this embodiment can reach 0.50 g CO2 / g adsorbent. After 20 cycles, the adsorption efficiency remained at 0.30 g CO2 / g adsorbent. As shown in FIG. 3(b), the electron microscope image of the sample shows that it has a porous structure and a large specific surface area, which is beneficial to the adsorption of carbon dioxide.
[0045] In this comparative example, first, anhydrous magnesium oxalate was added to 60 ml of distilled water and mixed rapidly, then fulvic acid was added, and the beaker containing the mixed solution was placed on a magnetic stirrer for mixing and temperature increase. The mass ratio of anhydrous magnesium oxalate to fulvic acid was 92:8. After hydration, the beaker was placed in a drying oven at 80°C for 12 hours. After the sample was fully dried, the obtained solid mixture was taken out and calcined in a muffle furnace at a temperature of 500°C, a heating rate of 2°C / min, and a reaction time of 30 minutes. After calcination, the sample was taken out and ground in a mortar to obtain a uniform powder sample, i.e. a modified magnesium oxide-based adsorbent.
[0046] As shown in Figure 4(a), in the present embodiment, the adsorption rate of the composite MgO-based adsorbent to carbon dioxide is 0.42 g CO2 / g adsorbent. After 20 cycles of use, the adsorption efficiency is reduced to 0.22 g CO2 / g adsorbent. As can be seen from the sample electron microscope image shown in Figure 4(b), the sample has a porous structure, but the specific surface area is small.
[0047] In the present comparative example experiment, the lithium iron phosphate battery powder is not doped, and the adsorption rate of the lithium iron phosphate battery powder to carbon dioxide and the adsorption efficiency after the cycles of use are obviously lower than those of Example One and Example Two.
[0048] In the present comparative example experiment, the lithium iron phosphate battery powder is not doped, and the adsorption rate of the lithium iron phosphate battery powder to carbon dioxide and the adsorption efficiency after the cycles of use are obviously lower than those of Example One and Example Two.
[0049] As shown in Figure 5(a), in the present embodiment, the adsorption rate of the composite MgO-based adsorbent to carbon dioxide is 0.24 g CO2 / g adsorbent. After 20 cycles of use, the adsorption efficiency is still maintained at 0.09 g CO2 / g adsorbent. As can be seen from the sample electron microscope image shown in Figure 5(b), the sample without doping fulvic acid presents a sheet-like stacking structure, and the specific surface area is smaller than that of the sample with doping fulvic acid, and the adsorption rate of carbon dioxide and the adsorption efficiency after the cycles of use are both far lower than those of Example One and Example Two.
[0050] In summary, in the present application, the fulvic acid molecules are complexed and ion-exchanged with the surface of the magnesium oxide precursor particles through active functional groups such as carboxyl groups and phenolic hydroxyl groups, and the crystallization behavior of the precursor is regulated. The nanostructure characteristics lay the foundation for the formation of porous materials, improve the carbonation performance of MgO, and delay the sintering phenomenon. The channels generated by the pyrolysis of fulvic acid increase the specific surface area and the basic site density of MgO, which is beneficial to CO2 adsorption and further delays sintering.
[0051] The introduction of waste lithium iron phosphate battery powder will increase the Li + and Fe 2+ into the adsorption system to realize functional synergy and waste resource utilization. Specifically, Li + as a dopant into the MgO lattice or enriched on the surface, increases the basic site density and improves the CO2 chemical adsorption capacity; Fe 2+ is oxidized to Fe 3+, regulate CO2 adsorption-desorption kinetics, reduce reaction activation energy, and improve adsorption rate. The pretreatment stage uses N2 / H2 mixed atmosphere to ensure Li + Fe 2+ activity and inhibit metal element oxidation. Both of them significantly improve the adsorbent's adsorption capacity, rate and cycle stability.
[0052] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a CO2 adsorbent, characterized in that, Includes the following steps: S1: The magnesium oxide precursor was mixed with distilled water and fulvic acid was added to form a mixed solution. The mixed solution was stirred and heated to carry out a hydration reaction. After the reaction was completed, the solution was dried to obtain the primary complex. S2: The primary composite is calcined, and after calcination, it is ground into porous magnesium oxide powder; S3: Add the obtained powder and waste lithium iron phosphate battery powder to distilled water and stir to mix. Stir the mixture and heat it to carry out the hydration reaction. After the reaction is completed, dry it to obtain the modified magnesium oxide-based adsorbent.
2. The method for preparing the CO2 adsorbent according to claim 1, characterized in that, The magnesium oxide precursor includes at least one of anhydrous magnesium oxalate, anhydrous magnesium citrate, magnesium lactate, magnesium ethoxide, and magnesium acetate.
3. The method for preparing the CO2 adsorbent according to claim 1, characterized in that, In S1, the mass fraction of magnesium oxide precursor is 85%–95%, and the mass fraction of fulvic acid is 5%–15%.
4. The method for preparing the CO2 adsorbent according to claim 1, characterized in that, In S2, calcination is carried out in a muffle furnace at a temperature of 450–550°C, a heating rate of 2–10°C / min, and a holding time of 30 min.
5. The method for preparing the CO2 adsorbent according to claim 1, characterized in that, In S3, the magnesium oxide-based adsorbent contains 90%–95% porous magnesium oxide powder by mass and 5%–10% waste lithium iron phosphate battery powder by mass.
6. The method for preparing the CO2 adsorbent according to claim 1, characterized in that, The drying conditions for both S1 and S3 are 12 hours at 80°C.
7. The preparation method according to claim 1, characterized in that, In S3, the preparation method of waste lithium iron phosphate battery powder is as follows: after dismantling the recycled waste lithium iron phosphate battery, crush it to a particle size of <1mm, then pyrolyze to remove the PVDF binder, and finally ball mill to obtain nanoscale composite powder.
8. The preparation method according to claim 7, characterized in that, The pyrolysis conditions for preparing the waste lithium iron phosphate battery powder are: pyrolysis is carried out in a reducing atmosphere.
9. The preparation method according to claim 8, characterized in that, The reducing atmosphere is a N2 / H2 mixture.
10. A CO2 adsorbent, characterized in that, It is prepared by any one of the preparation methods described in claims 1-9.