Aminopropyltriethoxysilane modified gasification slag mesoporous material and application thereof in carbon dioxide adsorption

Abstract

The invention discloses an aminopropyltriethoxysilane modified gasified slag mesoporous material and application thereof to carbon dioxide adsorption, gasified slag is used as a raw material, the gasified slag is ground by a ball mill and then soaked in hydrochloric acid to prepare the mesoporous material, then aminopropyltriethoxysilane is used for modification, and the mesoporous material is obtained. The amino group is introduced into the surface of the mesoporous material in a chemical bond mode to realize firm combination with a mesoporous material framework, and the aminopropyltriethoxysilane modified gasification slag mesoporous material is obtained. Compared with the prior art, the obtained mesoporous material has good chemical stability and can be used in high temperature, strong acid and strong alkali for a long time; and the amino group on the mesoporous material has strong alkalinity, can be subjected to acid-base reaction with carbon dioxide, realizes capture of carbon dioxide, and has good adsorption rate and adsorption capacity. Meanwhile, the preparation method of the mesoporous material is easy to operate, raw materials are cheap, high-quality utilization of solid waste is achieved, and economic benefits are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon dioxide adsorption, and specifically relates to an aminopropyltriethoxysilane modified gasified slag mesoporous material and application thereof in adsorbing carbon dioxide. Background Art

[0002] At present, large-scale coal chemical or coking enterprises often emit tail gas containing a high volume fraction of carbon dioxide during the production process. Under the global trend of advocating low-carbon development, coal chemical enterprises need a CO2 capture and conversion technology with low energy consumption, high efficiency and resource utilization capabilities to meet emission reduction targets and create additional economic value. Traditional CO2 capture processes mostly use amine solvents (such as MEA and DEA), which have high energy consumption, prominent solvent corrosiveness, and increased operating costs.

[0003] Gasified slag refers to solid waste produced during the gasification process of fuels such as coal, oil, and natural gas. According to the particle size, gasified slag is usually divided into coarse slag and fine slag. Not only is the quantity huge, but if it is not handled properly, it will have a serious impact on the environment and land resources. However, because it has a developed porous structure, the pores are not only numerous, but also widely distributed. This porous structure gives the gasified slag a large specific surface area, increases the contact area between the gasified slag and the surrounding environment, is conducive to the adsorption function, and can become an ideal adsorption material. Therefore, in order to meet the capture of carbon dioxide, it is necessary to modify the surface of the gasified slag, such as using loaded organic amines for modification. In the invention patents with application numbers 202111611047.8 and 202111645042.7, gasified slag is used as a carrier, and organic amine compounds such as polyethyleneimine, pentaethylenehexamine, and ethanolamine are impregnated in organic solvents such as ethanol or acetone to obtain a cheap and easy-to-obtain high-efficiency carbon dioxide adsorbent. However, in these modification methods, organic amines usually volatilize before the matrix decomposes, resulting in weight loss, thereby reducing the thermal stability of the material and affecting the modification effect. In addition, under strong acid or strong base conditions, organic amines will decompose or fall off, resulting in a decrease in the performance of the material and poor modification effect. Secondly, loading organic amines will also cause the pore size of the adsorbent to become smaller, increase mass transfer resistance, and reduce the adsorption rate. In addition, organic amines are volatile, and their discharge may cause air pollution and water pollution, causing environmental pollution. The discarded adsorbent will become a solid waste that is difficult to handle due to the loading of organic amines. Summary of the invention

[0004] The purpose of the present invention is to provide an aminopropyltriethoxysilane modified gasification slag mesoporous material which has simple preparation process, safety and stability, low cost, long-lasting performance and no impact on the environment after being discarded.

[0005] The aminopropyltriethoxysilane modified gasified slag mesoporous material provided by the present invention is prepared by the following steps:

[0006] Step 1: Grind the gasified slag with a ball mill, and soak the ground fine slag in hydrochloric acid; after soaking, wash with distilled water and dry to obtain the gasified slag mesoporous material.

[0007] Step 2: Add the gasified slag mesoporous material obtained in step 1 into ethanol, ultrasonically stir at 30-40° C. for 1-2 hours, then add aminopropyltriethoxysilane, and add ammonia water to adjust the pH of the system to 8-10, heat and stir at 50-100° C. for 2-6 hours; after the reaction is completed, cool to room temperature, centrifuge, wash the precipitate with anhydrous ethanol, and vacuum dry to obtain aminopropyltriethoxysilane-modified gasified slag mesoporous material.

[0008] In the above step 1, the mass-volume ratio of the fine residue to hydrochloric acid is preferably 1 g: 2 to 10 mL.

[0009] In the above step 1, the mass fraction of the hydrochloric acid is preferably 10% to 20%.

[0010] In the above step 1, the soaking time is preferably 10 to 12 hours.

[0011] In the above step 1, the drying temperature is preferably 90-110°C.

[0012] In the above step 2, preferably, the mass ratio of the gasified slag mesoporous material to aminopropyltriethoxysilane is 1:0.1-1.

[0013] In the above step 2, it is further preferred that the mass ratio of the gasified slag mesoporous material to aminopropyltriethoxysilane is 1:0.3-0.5.

[0014] In the above step 2, the mass fraction of the ammonia water is preferably 10% to 20%.

[0015] In the above step 2, the reaction is preferably heated and stirred at 70 to 80° C. for 3 to 5 hours.

[0016] In the above step 2, the vacuum drying temperature is preferably 50-100°C.

[0017] The present invention also provides the use of the aminopropyltriethoxysilane modified gasification slag mesoporous material as an adsorbent in the adsorption of carbon dioxide.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The present invention pre-treats the gasified slag with hydrochloric acid, ultrasonically disperses it in ethanol, and modifies it with aminopropyltriethoxysilane under alkaline conditions, making full use of the large specific surface area and pore structure of the gasified slag, which is beneficial to the uniform distribution and stable existence of amino groups, and can produce a highly stable material, ensuring the good adsorption performance of the material to meet the requirements of long-term use.

[0020] 2. The present invention adopts aminopropyltriethoxysilane to modify the gasification slag mesoporous material. The amino group is connected to the surface of the mesoporous material by chemical bonding, so as to achieve a firm bond with the skeleton of the mesoporous material, enhance the overall structural stability of the material, and make it difficult for the amino group to fall off or migrate during chemical reactions, thereby ensuring the chemical stability of the material in long-term use. The presence of the amino group makes the surface of the material have a certain acid-base buffering capacity, which can resist acid-base erosion to a certain extent, thereby maintaining its structural integrity and stable performance.

[0021] 3. The aminopropyltriethoxysilane modified gasified slag mesoporous material prepared by the present invention has a higher adsorption capacity and adsorption rate for carbon dioxide. The amino functional groups in the aminopropyltriethoxysilane molecules introduce new active sites to the mesoporous material, which can interact with carbon dioxide molecules, thereby increasing the adsorption capacity. In addition, the introduction of aminopropyltriethoxysilane improves the surface properties of the mesoporous material, making it easier for carbon dioxide molecules to diffuse and adsorb on the surface of the material, thereby increasing the adsorption rate.

[0022] 4. The preparation method of the present invention is simple and time-saving. The gasified slag used is a solid waste material. Through a simple process, the gasified slag is converted into an adsorbent with high application value. The production process is non-toxic and harmless and environmentally friendly. The use of modified gasified slag not only helps to solve the problem of environmental pollution, but also realizes the resource utilization of waste, reduces the mining and consumption of primary resources, reduces the cost of waste treatment and disposal, helps to reduce the generation of waste, and reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the SEM image of the original gasification slag fine slag.

[0024] Figure 2 This is a SEM image of the aminopropyltriethoxysilane modified gasified slag mesoporous material prepared in Example 1. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with embodiments and drawings, but the protection scope of the present invention is not limited to these embodiments.

[0026] Example 1

[0027] Step 1: Grind the gasified slag with a ball mill, and sieve out the fine slag with a 1000-mesh standard sample sieve after grinding. Take 5g of the fine slag and add it to 15mL of 15% hydrochloric acid and soak it for 12 hours. After soaking, filter the solid matter and wash it with distilled water. After washing, dry it at 100°C for 8 hours until the water disappears, and obtain the gasified slag mesoporous material.

[0028] Step 2: Weigh 10 g of gasification slag mesoporous material, add it into a flask containing 360 mL of ethanol, ultrasonically stir it at 35°C for 1.5 hours, then add 3.5 g of aminopropyltriethoxysilane, and add 20% ammonia water to adjust the pH of the system to 9, heat it to 70°C in a water bath, and stir it at a constant temperature for 4 hours; after the reaction, cool it to room temperature, centrifuge the reaction mixture at 3000 rpm for 10 minutes, wash the precipitate after centrifugation with ethanol, and then vacuum dry it at 70°C for 24 hours to obtain aminopropyltriethoxysilane-modified gasification slag mesoporous material. Figure 1 and Figure 2 It can be seen that the unmodified original gasified slag has a porous structure, while the pores of the aminopropyltriethoxysilane-modified gasified slag mesoporous material are covered with a large number of solid particles, indicating that aminopropyltriethoxysilane is successfully loaded on the surface of the mesoporous material, but it still retains the mesoporous structure of the gasified slag.

[0029] Example 2

[0030] In step 2 of this embodiment, 10 g of gasified slag mesoporous material was weighed, added to a flask containing 360 mL of ethanol, ultrasonically stirred at 35 ° C for 1.5 hours, and then 4.5 g of aminopropyl triethoxysilane was added, and ammonia water with a mass fraction of 20% was added to adjust the pH of the system to 9, heated to 70 ° C in a water bath, and stirred at a constant temperature for 4 hours; after the reaction, it was cooled to room temperature, and the reaction mixture was centrifuged at 3000 rpm for 10 minutes. The precipitate after centrifugation was fully washed with ethanol, and then vacuum dried at 70 ° C for 24 hours. The other steps are the same as in Example 1 to obtain aminopropyl triethoxysilane modified gasified slag mesoporous material.

[0031] Example 3

[0032] In step 2 of this embodiment, 10 g of gasified slag mesoporous material was weighed, added to a flask containing 360 mL of ethanol, ultrasonically stirred at 35 ° C for 1.5 hours, and then 4.5 g of aminopropyl triethoxysilane was added, and ammonia water with a mass fraction of 20% was added to adjust the pH of the system to 9, heated to 80 ° C in a water bath, and stirred at a constant temperature for 4 hours; after the reaction, it was cooled to room temperature, and the reaction mixture was centrifuged at 3000 rpm for 10 minutes. The precipitate after centrifugation was fully washed with ethanol, and then vacuum dried at 70 ° C for 24 hours. The other steps are the same as in Example 1 to obtain aminopropyl triethoxysilane modified gasified slag mesoporous material.

[0033] Example 4

[0034] In step 2 of this embodiment, 10 g of gasified slag mesoporous material was weighed, added to a flask containing 360 mL of ethanol, ultrasonically stirred at 35 ° C for 1.5 hours, and then 4.5 g of aminopropyl triethoxysilane was added, and ammonia water with a mass fraction of 20% was added to adjust the pH of the system to 9, heated to 80 ° C in a water bath, and stirred at a constant temperature for 5 hours; after the reaction, it was cooled to room temperature, and the reaction mixture was centrifuged at 3000 rpm for 10 minutes. The precipitate after centrifugation was fully washed with ethanol, and then vacuum dried at 70 ° C for 24 hours. The other steps are the same as in Example 1 to obtain aminopropyl triethoxysilane modified gasified slag mesoporous material.

[0035] The carbon dioxide adsorption performance of the above examples 1 to 4 was tested under acidic conditions (pH = 3 to 4) at 100°C, simulating industrial carbon dioxide tail gas, setting the volume content of carbon dioxide to 30%, the flow rate to 30 mL / min, and adsorption for 4 hours. The adsorption capacity, stability performance and adsorption rate of each gram of adsorbent were tested. The specific test method is as follows:

[0036] Adsorption capacity test: the ratio of the total amount of carbon dioxide adsorbed (mmol) to the total adsorbent mass (g) within 4 hours. Stability performance test: after 20 cycles of adsorption, measure the first adsorption capacity (m) and the last adsorption capacity (M), and calculate according to the formula: M / m×100%. Adsorption rate test: measure the time required to adsorb 400mg of carbon dioxide.

[0037] The test results are shown in Table 1.

[0038] Table 1

[0039] Performance Indicators Example 1 Example 2 Example 3 Example 4 Adsorption amount (mmol) 5.53 5.82 5.97 5.74 Adsorption rate (min) 55 60 50 53 Adsorption performance (%) 99.95 99.97 99.98 99.96

[0040] As can be seen from Table 1, the aminopropyltriethoxysilane modified gasification slag mesoporous materials prepared in Examples 1 to 4 have good adsorption performance for carbon dioxide under high temperature and strong acid conditions, with stable adsorption effect, large adsorption amount and adsorption rate.

Claims

1. An aminopropyltriethoxysilane modified gasified slag mesoporous material, characterized in that: The mesoporous material is prepared by the following steps: Step 1: Grind the gasified slag with a ball mill, and soak the ground fine slag in hydrochloric acid; after soaking, wash with distilled water and dry to obtain the gasified slag mesoporous material; Step 2: Add the gasified slag mesoporous material obtained in step 1 into ethanol, ultrasonically stir at 30-40° C. for 1-2 hours, then add aminopropyltriethoxysilane, and add ammonia water to adjust the pH of the system to 8-10, heat and stir at 50-100° C. for 2-6 hours; after the reaction is completed, cool to room temperature, centrifuge, wash the precipitate with anhydrous ethanol, and vacuum dry to obtain aminopropyltriethoxysilane-modified gasified slag mesoporous material.

2. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 1, the mass-volume ratio of the fine residue to hydrochloric acid is 1 g: 2-10 mL.

3. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 2, characterized in that: In step 1, the mass fraction of the hydrochloric acid is 10% to 20%.

4. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 1, the soaking time is 10 to 12 hours; the drying temperature is 90 to 110°C.

5. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 2, the mass ratio of the gasified slag mesoporous material to aminopropyltriethoxysilane is 1:0.1-1.

6. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 2, the mass ratio of the gasified slag mesoporous material to aminopropyltriethoxysilane is 1:0.3-0.

5.

7. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 2, the mass fraction of the ammonia water is 10% to 20%.

8. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 2, the reaction is heated and stirred at 70-80° C. for 3-5 hours.

9. The aminopropyltriethoxysilane modified gasified slag mesoporous material according to claim 1, characterized in that: In step 2, the vacuum drying temperature is 50-100°C.

10. Use of the aminopropyltriethoxysilane modified fumed slag mesoporous material according to any one of claims 1 to 9 in the adsorption of carbon dioxide.

Images