A K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, its preparation method and application

Abstract

This invention discloses a potassium-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, its preparation method, and its applications. The method utilizes silica extracted from treated and activated coal gangue as a silicon source, reducing preparation costs and effectively utilizing solid waste resources. By introducing an appropriate amount of potassium to alter the crystal structure, the carbon dioxide adsorption performance of the material is improved. Compared with existing technologies, the potassium-doped lithium silicate material prepared by this invention exhibits higher efficiency and stability in carbon dioxide adsorption, demonstrating excellent adsorption performance over a range from room temperature to high temperatures, making it suitable for industrial carbon dioxide sequestration.

Description

Technical Field

[0001] This invention relates to the fields of materials science and environmental engineering, specifically to a K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, its preparation method, and its applications. Background Technology

[0002] Currently, global climate change poses a serious challenge to the Earth's environment and human society, with carbon dioxide emissions becoming increasingly prominent. Therefore, developing efficient carbon dioxide sequestration materials is crucial. However, traditional material preparation methods are often limited by high silicon source costs and resource waste. Lithium silicate (Li4SiO4), as a material for high-temperature CO2 adsorption, has unique advantages. Compared with other adsorption materials, it does not require cooling before adsorption, which reduces energy consumption, saves energy, and ultimately lowers costs, thus enhancing its prospects for commercial applications. However, despite its good performance at high temperatures, lithium silicate exhibits weaker carbon dioxide adsorption performance, with limited adsorption efficiency and stability at low and medium temperatures. This limitation restricts the application of lithium silicate in industrial carbon dioxide sequestration. Therefore, there is an urgent need to develop a new material with a wide temperature adaptability range, high adsorption capacity, good cycle stability, and controllable adsorption / desorption rates. The development of such a material will help to more effectively capture and sequester carbon dioxide, providing important support for addressing climate change and protecting the environment. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a potassium-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, along with its preparation method and applications. Utilizing silica extracted from coal gangue as the primary silicon source, and through processing and activation, it achieves effective utilization of solid waste, solving the problem of high silicon source costs in traditional synthesis methods. Furthermore, the introduction of potassium forms a eutectic with lithium silicate and alters its crystal structure, thereby improving its performance in carbon dioxide adsorption. This material can be applied to applications including, but not limited to, industrial production, emissions reduction from coal-fired power plants, and vehicle exhaust emission reduction, playing a crucial role in mitigating climate change and improving environmental quality.

[0004] To address the problems in the existing technology, the technical solution adopted by this invention is as follows: A method for preparing K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range includes the following steps: S1. Select coal ore, crush and grind it to 200 mesh, and then activate it at 500-900℃ for 1-3 hours; S2. Soak the activated coal ash in a 5 mol / L hydrochloric acid solution at 60℃ for 2-5 hours. S3. After acid leaching, the sample is taken out, filtered, washed with water, and then dried to obtain silica as a silicon source precursor. S4. Grind and mix silica with lithium carbonate and potassium hydroxide in a molar ratio of nSi:nLi:nK = 1:4-x:x ~ 1:4.4-x:x, where x ranges from 0.03 to 0.15. Add organic solvent and grind thoroughly, then dry and grind until powdered. Finally, calcine to obtain K-doped lithium silicate material.

[0005] The purpose of calcination activation and acid leaching is to remove Al2O3 and other impurities from coal ash and increase the SiO2 content. This method has the advantages of reducing preparation costs, effectively utilizing solid waste, and improving the adsorption performance of lithium silicate.

[0006] Preferably, in step S1, the SiO2 content in the coal gangue is 52-65 wt%, the Al2O3 content is 16-36 wt%, and the remainder is impurities, including metal oxides such as Fe2O3, CaO, MgO, K2O and Na2O, as well as carbon-containing organic matter.

[0007] Preferably, the drying temperature in step S3 is 100°C.

[0008] Preferably, the calcination temperature in step S4 is 700-900℃, and the calcination time is 3-8 hours.

[0009] More preferably, the calcination in step S4 refers to raising the temperature from room temperature to 200°C within 100 min, holding the temperature at 200°C for 20 min, and then raising the temperature to 800°C within 100 min and holding the temperature at 800°C for 4 hours.

[0010] Preferably, the organic solvent in step S4 is ethanol or acetone.

[0011] The K-doped lithium silicate material prepared by the above preparation method.

[0012] Preferably, the PXRD data of the K-doped lithium silicate material shows characteristic peaks of Li4SiO4, and at 34... o The presence of characteristic peaks of Li3KSiO4 indicates that some Li in the crystal lattice has been replaced by K.

[0013] The above-mentioned preparation method is used to adsorb carbon dioxide in a wide temperature range.

[0014] Preferably, the wide temperature range is 25°C. o C~600 o C, at the temperature range mentioned, when carbon dioxide adsorption reaches equilibrium, the adsorption efficiency is between 5.1 wt% and 26 wt%.

[0015] Beneficial effects: This invention discloses a potassium-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, its preparation method, and its applications. Using silica from coal gangue (a solid waste material) as the main silicon source, potassium is introduced to form a eutectic with lithium silicate and alter its crystal structure, thereby controlling the chemical composition and crystal structure of the material. The resulting material exhibits excellent carbon dioxide adsorption performance over a wide temperature range, capable of handling carbon dioxide emissions at different temperatures, and has a wider range of applications in the field of carbon dioxide sequestration.

[0016] Compared with existing technologies, the specific advantages are as follows: 1. By utilizing precipitated silica extracted from coal gangue, the reuse and comprehensive utilization of resources are achieved. Furthermore, since precipitated silica is a byproduct of coal gangue, its utilization reduces the demand for other raw materials, helps conserve natural resources, lowers production costs, and also helps reduce the generation of solid waste, thus achieving effective resource utilization.

[0017] 2. The K-doped lithium silicate ceramic material of this invention exhibits higher efficiency and stability in carbon dioxide adsorption, demonstrating excellent adsorption performance over a wide temperature range. It can effectively capture and seal carbon dioxide emitted from industry. This technology is not only applicable to industrial production, emissions from coal-fired power plants, and vehicle exhaust reduction, but can also play a role in other fields. Its broad applicability demonstrates its important role in mitigating climate change and improving environmental quality, contributing positively to reducing greenhouse gas emissions. Attached Figure Description

[0018] Figure 1 XRD patterns of K-doped lithium silicate materials prepared by different methods; Figure 2 K-doped lithium silicate materials prepared by different methods at 25 o C ~ 600 o Carbon dioxide adsorption at C. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0020] A method for preparing lithium silicate carbon dioxide adsorbent using a solid-phase method with precipitated silica includes the following steps: Processing: The coal ore was crushed and ground to a fine 200 mesh and activated at 700°C for 2 hours. Subsequently, the activated coal ore was immersed in a 5 mol / L hydrochloric acid solution at 60°C (10 times the weight of the coal ore) for 4 hours. After acid leaching, the sample was filtered, washed with water, and then dried in an oven at 100°C, using pure silica as the silicon source.

[0021] Calcination: Silica, lithium carbonate, and potassium hydroxide were ground in a mortar to a 40-mesh powder in a molar ratio of n(Si):n(Li):n(K) = 1:3.97:0.03. 3 ml of ethanol was added and the mixture was ground thoroughly for 1 hour. The powder was then dried in an oven at 100°C for 2 hours to remove the ethanol. The powder was then ground further and placed in a muffle furnace for calcination. The temperature was first raised from room temperature to 200°C within 100 minutes and held at 200°C for 20 minutes. Then, the temperature was raised to 800°C within 100 minutes and held at 800°C for 4 hours. Finally, the mixture was cooled to room temperature in the furnace to obtain K-doped lithium silicate powder LiK-0.03.

[0022] Carbon dioxide adsorption test: Under the TGA experimental conditions, the sample was placed in a pure CO2 environment at 25℃, 50℃, 100℃, 200℃, 300℃, 400℃, 500℃ and 600℃ for 30 min to adsorb, and maintained for 30 min after reaching adsorption equilibrium. The change in the mass of the sample powder was then measured. Example 2

[0023] Except for changing the molar ratio of silica, lithium carbonate and potassium hydroxide to n(Si):n(Li):n(K) = 1:3.95:0.05, K-doped lithium silicate powder LiK-0.05 was obtained, and the rest was the same as in Example 1. Example 3

[0024] Except for changing the molar ratio of silica, lithium carbonate and potassium hydroxide to n(Si):n(Li):n(K) = 1:3.92:0.08, K-doped lithium silicate powder LiK-0.08 was obtained, and the rest was the same as in Example 1. Example 4

[0025] Except for changing the molar ratio of silica, lithium carbonate and potassium hydroxide to n(Si):n(Li):n(K) = 1:3.9:0.1, K-doped lithium silicate powder LiK-0.1 was obtained, and the rest was the same as in Example 1. Example 5

[0026] Except for changing the molar ratio of silica, lithium carbonate and potassium hydroxide to n(Si):n(Li):n(K) = 1:3.85:0.15, K-doped lithium silicate powder LiK-0.15 was obtained, and the rest was the same as in Example 1.

[0027] Comparative Example Except for changing the molar ratio of silica to lithium carbonate to n(Si):n(Li) = 1:4, lithium silicate powder Li4SiO4 was obtained, and the rest was the same as in Example 1.

[0028] from Figure 2 The results show that, compared with the pure-phase lithium silicate high-temperature carbon dioxide adsorbent, the obtained potassium-doped lithium silicate material exhibits good CO2 absorption performance in the range from room temperature to high temperature, reaching the theoretical adsorption value of 26 wt%, and has stable adsorption performance.

[0029] This invention first processes and activates coal gangue to extract a silicon source, primarily composed of precipitated silica, thus addressing the high cost of silicon sources in traditional synthesis methods and effectively reducing preparation costs. Using precipitated silica extracted from coal gangue as the silicon source helps reduce solid waste generation and achieves efficient resource utilization from an economic perspective, providing significant practical application value for the production of high-temperature CO2 adsorption materials. Therefore, the preparation method of this invention has the advantage of cost reduction, and the resulting material exhibits significant superiority in carbon dioxide adsorption.

[0030] Those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for preparing K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range, characterized in that, Includes the following steps: S1. Select coal gangue, crush and grind it to 200 mesh, and then activate it at 500-900℃ for 1-3 hours; S2. Soak the activated coal gangue in a 5 mol / L hydrochloric acid solution at 60℃ for 2-5 hours. S3. After acid leaching, the sample is taken out, filtered, washed with water, and then dried to obtain silica as a silicon source precursor. S4. Grind and mix silica, lithium carbonate, and potassium hydroxide thoroughly in a molar ratio, nSi:nLi:nK = 1:4-x:x ~ 1:4.4-x:x, where x ranges from 0.03 to 0.

15. Add an organic solvent and grind thoroughly, then dry and continue grinding until powdered. Calcine the powder to obtain K-doped lithium silicate material. The calcination process involves raising the temperature from room temperature to 200°C within 100 min, holding it at 200°C for 20 min, then raising the temperature to 800°C within 100 min, and holding it at 800°C for 4 hours.

2. The method for preparing a K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range as described in claim 1, characterized in that, In step S1, the SiO2 content in the coal gangue is 52-65wt%, the Al2O3 content is 16-36wt%, and the remainder is impurities.

3. The method for preparing a K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range as described in claim 1, characterized in that, The drying temperature in step S3 is 100℃.

4. The method for preparing a K-doped lithium silicate material suitable for carbon dioxide adsorption over a wide temperature range as described in claim 1, characterized in that, In step S4, the organic solvent is ethanol or acetone.

5. A K-doped lithium silicate material prepared by the preparation method according to any one of claims 1-4, characterized in that, The PXRD data of the K-doped lithium silicate material shows characteristic peaks of Li4SiO4, and at 34... o The characteristic peak of Li3KSiO4 is present at this location.

6. The application of the K-doped lithium silicate material prepared by the preparation method according to claims 1-4 in the adsorption of carbon dioxide over a wide temperature range, characterized in that, The wide temperature range is 25°C. o C~600 o C.

7. The application according to claim 6, characterized in that, Within the specified temperature range, when carbon dioxide adsorption reaches equilibrium, the adsorption efficiency is between 5.1 wt% and 26 wt%.

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