Carbon dioxide adsorbent as well as preparation method and application thereof

Abstract

The invention provides a carbon dioxide adsorbent as well as a preparation method and application thereof. The method comprises the following steps: S1, mixing a lithium precursor and an alcohol solvent to obtain a precursor solution, mixing the precursor solution and silicon dioxide particles to obtain a first mixture, carrying out first modification treatment on the first mixture at 65-95 DEG C, then removing the alcohol solvent, and carrying out post-treatment to obtain a first solid product; s2, mixing the first solid product with a salt solution of alkali metal to obtain a second mixture, performing second modification treatment on the second mixture at 65-90 DEG C, and performing post-treatment to obtain a second solid product; wherein the mass concentration of alkali metal in the salt solution of the alkali metal is 5-30%; s3, calcining the second solid product to obtain the carbon dioxide adsorbent. The carbon dioxide adsorbent is simple in preparation method and good in adsorption effect.

Description

Technical Field

[0001] The present invention relates to the technical field of gas adsorbents, and in particular to a carbon dioxide adsorbent and a preparation method and application thereof. Background Art

[0002] At present, the main ways to capture carbon dioxide are pre-combustion capture, oxygen-enriched combustion and post-combustion capture. Among them, the industrialization process of post-combustion capture technology is the fastest and it is already in the industrial application stage, while pre-combustion capture and oxygen-enriched combustion capture technologies are still in the industrial demonstration and pilot demonstration stages respectively. Post-combustion capture technology is to separate carbon dioxide from flue gas in the capture system to form a high concentration of carbon dioxide. The steel industry mainly uses post-combustion capture, and commonly used technologies include physical adsorption, chemical absorption and membrane separation. Through post-combustion carbon capture technology, carbon dioxide emitted from each process can be effectively captured.

[0003] In order to capture carbon dioxide directly from high-temperature flue gas more efficiently, more and more researchers are focusing on high-temperature carbon dioxide solid adsorbents to achieve the adsorption and separation of carbon dioxide directly under high-temperature conditions. In recent years, scholars have made certain progress in the research and development of high-temperature carbon dioxide adsorbents, mainly including calcium-based adsorbents and lithium-based adsorbents. As a typical high-temperature carbon dioxide solid adsorbent, lithium-based adsorbents represented by Li4SiO4 have attracted widespread attention from scholars around the world due to their excellent cycle stability, high adsorption performance and other advantages.

[0004] The adsorption process of Li4SiO4 is mainly divided into chemical adsorption process and diffusion process. Among them, the diffusion of carbon dioxide is the main factor restricting the entire Li4SiO4 adsorption process. In order to improve its performance, it can generally be achieved through microstructure modification of Li4SiO4 adsorbent, alkali doping, transition metal doping, effective use of silicon source and lithium source, and alkaline earth metal doping.

[0005] For example, CN109621891B discloses a lithium-based CO2 adsorbent and a preparation method thereof. The process selects wollastonite as a raw material, crushes and grinds the wollastonite to obtain wollastonite particles; adds the wollastonite particles into a lithium hydroxide monohydrate solution and stirs until the water evaporates to obtain a solid substance containing a silicon-calcium compound and lithium hydroxide; and calcines the solid substance so that the silicon-calcium compound therein reacts fully with the lithium hydroxide to obtain the desired lithium-based CO2 adsorbent.

[0006] CN111362274B discloses a micron-sized spherical lithium-based CO2 adsorbent and a preparation method thereof. The process comprises the following steps: adding a surfactant and a lithium source into an alcohol solution to obtain a mixed solution; adding tetraethyl orthosilicate and ammonia water into the mixed solution, and then ultrasonically treating the mixed solution for a preset time to obtain a white suspension; and calcining the white suspension for a preset time to obtain a solid product, which is the micron-sized spherical lithium-based CO2 adsorbent.

[0007] However, the prior art still has problems such as complex preparation methods, insufficient adsorption effect and adsorption stability. Summary of the invention

[0008] In order to solve the above problems in the prior art, the purpose of the present invention is to provide a carbon dioxide adsorbent and a preparation method and application thereof. The preparation method of the carbon dioxide adsorbent is simple and has good adsorption effect.

[0009] In order to achieve the above object, according to a first aspect of the present invention, a method for preparing a carbon dioxide adsorbent is provided, which comprises:

[0010] S1, mixing a lithium precursor and an alcohol solvent to obtain a precursor solution, mixing the precursor solution and silicon dioxide particles to obtain a first mixture, subjecting the first mixture to a first modification treatment at 65-90° C., then removing the alcohol solvent, and performing post-treatment to obtain a first solid product;

[0011] S2, mixing the first solid product and an alkali metal salt solution to obtain a second mixture, subjecting the second mixture to a second modification treatment at 65-90° C., and performing post-treatment to obtain a second solid product; wherein the mass concentration of the alkali metal in the alkali metal salt solution is 5-30%;

[0012] S3, calcining the second solid product to obtain the carbon dioxide adsorbent.

[0013] According to the method of the present invention, the raw material sources for preparing the carbon dioxide adsorbent are wide and the preparation method is simple. In addition, the present invention selects a suitable alkali metal salt solution concentration (5 to 30 wt%). Within this range, the obtained carbon dioxide adsorbent has good adsorption performance.

[0014] In some preferred embodiments of the present invention, in the precursor solution, the mass concentration of the lithium precursor is 3-8 wt %.

[0015] In some preferred embodiments of the present invention, the mass ratio of the lithium precursor to the silicon dioxide particles is 0.5 to 2:1.

[0016] In some preferred embodiments of the present invention, the average particle size of the silicon dioxide particles is 5-15 μm.

[0017] In some preferred embodiments of the present invention, the solid-to-liquid ratio of the first solid product to the alkali metal salt solution is 1 g:2-10 ml.

[0018] In some preferred embodiments of the present invention, in S1, the post-treatment comprises: drying the product after removing the alcohol solvent at 103-108° C. for 2-4 hours, and then grinding it.

[0019] In some preferred embodiments of the present invention, in S2, the post-treatment comprises: centrifuging the product after the second modification treatment to obtain a solid phase product, then drying the solid phase product at 103-108°C for 2-4h, and then grinding it.

[0020] In some preferred embodiments of the present invention, the lithium precursor includes lithium oxalate and / or lithium nitrate.

[0021] In some preferred embodiments of the present invention, the alcohol solvent includes ethanol and / or methanol.

[0022] In some preferred embodiments of the present invention, the alkali metal salt solution includes potassium carbonate solution and / or sodium carbonate.

[0023] In some preferred embodiments of the present invention, the calcination treatment is carried out at a temperature of 600-900°C, for a time of 6-12 hours, and at a heating rate of 5-15°C / min.

[0024] According to another aspect of the present invention, a carbon dioxide adsorbent obtained according to the above preparation method is also provided.

[0025] According to another aspect of the present invention, there is also provided an application of the above-mentioned carbon dioxide adsorbent.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] 1. A simple and convenient method for preparing a lithium-based carbon dioxide adsorbent is provided, which realizes the modification of the lithium-based carbon dioxide adsorbent with silicon dioxide and alkali metal elements. The modified carbon dioxide adsorbent has excellent carbon dioxide adsorption performance;

[0028] 2. The preparation method of the present invention is simple and the raw materials are widely available, which is conducive to industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1The SEM morphology of the carbon dioxide adsorbent prepared in Example 1 is shown. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0031] Example 1

[0032] This embodiment provides a method for preparing a carbon dioxide adsorbent, which comprises:

[0033] S1, 10 ml of a lithium oxalate solution with a mass concentration of 10% and 10 ml of anhydrous ethanol are mixed, stirred for 10 minutes to obtain a precursor solution, the precursor solution and 1 g of silicon dioxide particles with an average particle size of 8 μm are mixed, stirred for 15 minutes to obtain a first mixture, the first mixture is heated in a water bath at 80° C. for a first modification treatment, then the alcohol solvent is evaporated, and the obtained solid is dried in a 105° C. forced drying oven for 2 hours, ground into powder, and a first solid product is obtained;

[0034] S2, mixing the first solid product and potassium carbonate solution (mass concentration of 5%) at a solid-liquid ratio of 1g:5ml to obtain a second mixture, subjecting the second mixture to a second modification treatment at 80°C with stirring for 30min, and then separating the solid phase product using a high-speed centrifuge at 8000r / min, and then drying the obtained solid phase product in a 105°C forced air drying oven for 2 hours, and grinding it into powder to obtain a second solid product;

[0035] S3, calcining the second solid product, the calcination conditions are: heating rate 5°C / min, temperature 750°C, time 6h; after calcination, cool to room temperature, grind, and obtain a carbon dioxide adsorbent.

[0036] Example 2

[0037] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 5%.

[0038] Example 3

[0039] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 15%.

[0040] Example 4

[0041] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 20%.

[0042] Example 5

[0043] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 25%.

[0044] Example 6

[0045] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 30%.

[0046] Example 7

[0047] The only difference from Example 1 is that the calcination temperature is 600°C.

[0048] Example 8

[0049] The only difference from Example 1 is that the calcination temperature is 650°C.

[0050] Example 9

[0051] The only difference from Example 1 is that the calcination temperature is 700°C.

[0052] Example 10

[0053] The only difference from Example 1 is that the calcination temperature is 800°C.

[0054] Embodiment 11

[0055] The only difference from Example 1 is that the calcination temperature is 850°C.

[0056] Example 12

[0057] The only difference from Example 1 is that the calcination temperature is 900°C.

[0058] Embodiment 13

[0059] The only difference from Example 1 is that the calcination time is 7 hours.

[0060] Embodiment 14

[0061] The only difference from Example 1 is that the calcination time is 8 hours.

[0062] Embodiment 15

[0063] The only difference from Example 1 is that the calcination time is 9 hours.

[0064] Example 16

[0065] The only difference from Example 1 is that the calcination time is 10 h.

[0066] Embodiment 17

[0067] The only difference from Example 1 is that the calcination time is 11 hours.

[0068] Embodiment 18

[0069] The only difference from Example 1 is that the calcination time is 12 hours.

[0070] Comparative Example 1

[0071] The only difference from Example 1 is that the mass concentration of the potassium carbonate solution is 0%, that is, no potassium carbonate is added.

[0072] Application Examples

[0073] The carbon dioxide adsorbents obtained in the above-mentioned embodiments and comparative examples were subjected to a carbon dioxide adsorption test under the following conditions: adsorption temperature of 500° C., adsorption time of 60 min, and the volume fraction of carbon dioxide gas in the introduced gas of 20%.

[0074] The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] As can be seen from Table 1, the carbon dioxide adsorption performance of the carbon dioxide adsorbent obtained by the method of the present invention is better than that of the comparative example. Among them, the carbon dioxide adsorbent modified with a potassium carbonate solution with a mass concentration range of 5 to 30% and calcined at 650-800°C for 6-8h has particularly good carbon dioxide adsorption performance.

[0078] Figure 1 The SEM morphology of the carbon dioxide adsorbent prepared in Example 1 is shown. Figure 1 It can be seen that the particle size distribution of the carbon dioxide adsorbent of the present invention is uniform.

Claims

1. A method for preparing a carbon dioxide adsorbent, characterized in that: include: S1, mixing a lithium precursor and an alcohol solvent to obtain a precursor solution, mixing the precursor solution and silicon dioxide particles to obtain a first mixture, subjecting the first mixture to a first modification treatment at 65-90° C., then removing the alcohol solvent, and performing post-treatment to obtain a first solid product; S2, mixing the first solid product and an alkali metal salt solution to obtain a second mixture, subjecting the second mixture to a second modification treatment at 65-90° C., and performing post-treatment to obtain a second solid product; wherein the mass concentration of the alkali metal in the alkali metal salt solution is 5-30%; S3, calcining the second solid product to obtain the carbon dioxide adsorbent.

2. The preparation method according to claim 1, characterized in that: In the precursor solution, the mass concentration of the lithium precursor is 3-8wt%.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the lithium precursor to the silicon dioxide particles is 0.5 to 2:

1.

4. The preparation method according to claim 1, characterized in that: The average particle size of the silicon dioxide particles is 5-15 μm.

5. The preparation method according to claim 1, characterized in that: The solid-to-liquid ratio of the first solid product to the alkali metal salt solution is 1g:2-10ml.

6. The preparation method according to claim 1, characterized in that: In S1, the post-treatment comprises: drying the product after removing the alcohol solvent at 103-108° C. for 2-4 hours, and then grinding; and / or, In S2, the post-treatment includes: centrifuging the product after the second modification treatment to obtain a solid phase product, then drying the solid phase product at 103-108°C for 2-4h, and then grinding it.

7. The preparation method according to claim 1, characterized in that: The lithium precursor includes lithium oxalate and / or lithium nitrate; and / or, The alcohol solvent includes ethanol and / or methanol; and / or, The alkali metal salt solution includes potassium carbonate solution and / or sodium carbonate.

8. The preparation method according to claim 1, characterized in that: The calcination treatment is carried out at a temperature of 600-900°C, for a time of 6-12 hours, and at a heating rate of 5-15°C / min.

9. A carbon dioxide adsorbent, characterized in that: The carbon dioxide adsorbent is prepared according to the preparation method described in any one of claims 1 to 8.

10. Use of the carbon dioxide adsorbent according to claim 9 in carbon dioxide adsorption.

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