Preparation method of novel composite carbon dioxide adsorbent

Abstract

The invention discloses a preparation method of a novel composite carbon dioxide adsorbent, which comprises the following steps: pretreating calcium hydroxide with an organic acid, and then mixing and granulating with sodium hydroxide, potassium hydroxide and an indicator to obtain the adsorbent. Calcium hydroxide is pretreated with organic acid, the pore structure of calcium hydroxide is changed, the crystal size of the calcium-based adsorbent is reduced, and the specific surface area is increased, so that the adsorption performance of the adsorbent is improved. Through organic acid treatment, calcium hydroxide becomes fluffy and porous, the attenuation rate of the adsorption performance of the adsorbent after adsorbing carbon dioxide gas is reduced, calcium carbonate blockage is not prone to occurring in the carbon dioxide adsorption process of the adsorbent, and therefore the recycling performance of the adsorbent is improved, and the service life of the adsorbent is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon dioxide adsorbents, and in particular relates to a preparation method of a novel composite carbon dioxide adsorbent. Background Art

[0002] CO 2 It is the main gas causing the greenhouse effect, accounting for about 1 / 3 of greenhouse gases. 2 Capture and storage technology is the process of converting CO 2 Capturing and separating emissions from combustion sources for long-term storage and burial is a method that can significantly reduce CO 2 There are many separation methods, such as absorption, adsorption, membrane separation, low temperature separation, etc. Among them, adsorption has been widely used in industry, and can be divided into physical adsorption and chemical adsorption based on the adsorption principle.

[0003] Invention patent CN201711261812.1 discloses an anti-crushing carbon dioxide adsorbent, including calcium hydroxide, sodium hydroxide, water and fiber. The invention utilizes the tensile and anti-cracking effect of fiber on the material, adds a small amount of fiber to the soda lime, and after mixed molding, greatly improves the anti-crushing performance of the soda lime, does not change the original chemical composition of the soda lime, and has no significant impact on the properties such as porosity and surface area. Compared with the prior art, it solves the problems of resource waste, low efficiency, difficulty in replacement, choking and alkaline burns to the human body caused by the crushing of soda lime.

[0004] Considering the source of raw materials, cost and preparation process, calcium hydroxide is regarded as a CO 2 The preferred material for adsorbents has always attracted much attention. However, calcium-based adsorbents also have their inevitable disadvantages: they are easy to sinter and agglomerate at high temperatures, resulting in a significant decrease in specific surface area and pore volume; at the same time, the generated calcium carbonate layer will cover the surface of the adsorbent, preventing further diffusion of carbon dioxide, thereby reducing the adsorption capacity. Summary of the invention

[0005] In view of the defects of the prior art, the present invention provides a method for preparing a composite carbon dioxide adsorbent.

[0006] The present invention is achieved through the following technical solutions: A method for preparing a novel composite carbon dioxide adsorbent comprises the following steps: (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 10-12 hours to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding citric acid monohydrate in an amount 2-3 times the mass of the calcium hydroxide powder, mixing well, and stirring in a water bath at 80-100° C. for 2-4 hours to obtain a mixed solution; (3) calcining the mixed solution at 700-900°C for 2-4h, adding 0.5-1 times the mass of sodium hydroxide powder and 0.2-0.5 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) Mix the mixed powder and water at a solid-liquid ratio of 100:(20-30), add 0.04%-0.05% phenolphthalein indicator solution by weight of the mixed liquid, stir evenly, put into a granulator for granulation, and dry at 92-98°C for 3-4h to obtain a carbon dioxide adsorbent.

[0007] As a further improvement of the present invention, the citric acid monohydrate used in step (2) can be replaced by one of tartaric acid, malic acid or glacial acetic acid.

[0008] As a further improvement of the present invention, the amount of tartaric acid added is 1.5-2 times the mass of calcium hydroxide powder, and the prepared mixed solution is reacted in a 100° C. water bath for 4 hours.

[0009] As a further improvement of the present invention, the amount of malic acid added is twice the mass of the calcium hydroxide powder.

[0010] As a further improvement of the present invention, the amount of glacial acetic acid added is 4 times the mass of calcium hydroxide powder.

[0011] The beneficial effects of the present invention are as follows: 1. The present invention utilizes organic acid to pretreat calcium hydroxide, changes the pore structure of calcium hydroxide, reduces the crystal size of the calcium-based adsorbent, increases the specific surface area, and thus improves the adsorption performance of the adsorbent.

[0012] 2. The present invention makes calcium hydroxide fluffy and porous through organic acid treatment, which reduces the attenuation rate of the adsorption performance of the adsorbent after adsorbing carbon dioxide gas. Calcium carbonate blockage is not likely to occur during the adsorbent's carbon dioxide adsorption process, thereby improving the recycling performance of the adsorbent and increasing the service life of the adsorbent.

[0013] 3. The present invention utilizes organic acid treatment to reduce the crystal particle size of calcium hydroxide, thereby increasing the distance between the crystal particles, making it easier for the adsorbent to undergo gas-solid reaction, thereby reducing the diffusion resistance of carbon dioxide, and allowing the adsorbed carbon dioxide to completely react with the adsorbent. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the embodiments. Example 1: A method for preparing a novel composite carbon dioxide adsorbent, comprising the following steps:

[0015] (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 10 h to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding citric acid monohydrate in an amount twice the mass of the calcium hydroxide powder, mixing well, and stirring in a water bath at 80° C. for 2 h to obtain a mixed solution; (3) calcining the mixed solution at 900° C. for 2 h, adding 0.5 times the mass of sodium hydroxide powder and 0.2 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) The mixed powder and water were mixed at a solid-liquid ratio of 100:20, 0.04% phenolphthalein indicator solution by weight of the mixed solution was added, the mixture was stirred evenly, and then put into a granulator for granulation, and dried at 92°C for 3h to obtain a carbon dioxide adsorbent. Example 2: A method for preparing a novel composite carbon dioxide adsorbent, comprising the following steps:

[0016] (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 12 h to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding tartaric acid in an amount twice the mass of the calcium hydroxide powder, mixing well, and stirring in a water bath at 100° C. for 4 hours to obtain a mixed solution; (3) calcining the mixed solution at 700° C. for 4 h, adding 1 times the mass of sodium hydroxide powder and 0.5 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) The mixed powder and water were mixed at a solid-liquid ratio of 100:30, 0.05% of the mass of the mixed liquid was added with phenolphthalein indicator solution, the mixture was stirred evenly and put into a granulator for granulation, and dried at 98°C for 4h to obtain a carbon dioxide adsorbent. Example 3: A method for preparing a novel composite carbon dioxide adsorbent, comprising the following steps:

[0017] (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 11 hours to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding malic acid twice the mass of the calcium hydroxide powder, mixing well, and stirring in a 90°C water bath for 3 hours to obtain a mixed solution; (3) calcining the mixed solution at 800° C. for 3 h, adding 0.6 times the mass of sodium hydroxide powder and 0.4 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) The mixed powder and water were mixed at a solid-liquid ratio of 100:25, 0.05% of the mass of the mixed liquid was added with phenolphthalein indicator solution, the mixture was stirred evenly and put into a granulator for granulation, and dried at 95°C for 3h to obtain a carbon dioxide adsorbent. Example 4: A method for preparing a novel composite carbon dioxide adsorbent, comprising the following steps:

[0018] (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 12 h to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding glacial acetic acid in an amount 4 times the mass of the calcium hydroxide powder, mixing well, and stirring in a 95°C water bath for 3 hours to obtain a mixed solution; (3) calcining the mixed solution at 850° C. for 3 h, adding 0.8 times the mass of sodium hydroxide powder and 0.4 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) The mixed powder and water were mixed at a solid-liquid ratio of 100:25, 0.05% of the mass of the mixed liquid was added with phenolphthalein indicator solution, the mixture was stirred evenly and put into a granulator for granulation, and dried at 95°C for 4 hours to obtain a carbon dioxide adsorbent.

[0019] The adsorbent prepared in Examples 1-4 was used to conduct a carbon dioxide adsorption test, as follows: In the flue gas emitted by a coal power plant, the three adsorbents prepared in Examples 1-3 were used to adsorb carbon dioxide, and the various properties of the adsorbents were recorded. See Table 1 for details.

[0020] Table 1:

[0021] From the data in Table 1, it can be seen that the adsorbents prepared in Examples 1-4 of the present invention have good CO 2 The adsorption performance is good. After 10 and 20 cycles of adsorption, the adsorption rates are still 78.8% and 64.2%, and the service life is very long.

[0022] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for preparing a novel composite carbon dioxide adsorbent, characterized in that: The following steps are involved: (1) Grind calcium hydroxide into powder, sieve it with a 140-mesh sieve, and dry it at 80° C. for 10-12 hours to obtain calcium hydroxide powder; (2) Mixing calcium hydroxide powder and water at a solid-liquid ratio of 1:30, then adding citric acid monohydrate in an amount 2-3 times the mass of the calcium hydroxide powder, mixing well, and stirring in a water bath at 80-100° C. for 2-4 hours to obtain a mixed solution; (3) calcining the mixed solution at 700-900°C for 2-4h, adding 0.5-1 times the mass of sodium hydroxide powder and 0.2-0.5 times the mass of potassium hydroxide powder after cooling, mixing and grinding to obtain a mixed powder; (4) Mix the mixed powder and water at a solid-liquid ratio of 100:(20-30), add 0.04%-0.05% phenolphthalein indicator solution by weight of the mixed liquid, stir evenly, put into a granulator for granulation, and dry at 92-98°C for 3-4h to obtain a carbon dioxide adsorbent.

2. The method for preparing the novel composite carbon dioxide adsorbent according to claim 1, characterized in that: The citric acid monohydrate in step (2) can be replaced by one of tartaric acid, malic acid or glacial acetic acid.

3. The method for preparing the novel composite carbon dioxide adsorbent according to claim 2, characterized in that: The amount of tartaric acid added is 1.5-2 times the mass of calcium hydroxide powder, and the prepared mixed solution is reacted in a 100° C. water bath for 4 hours.

4. The method for preparing the novel composite carbon dioxide adsorbent according to claim 2, characterized in that: The amount of malic acid added is twice the mass of calcium hydroxide powder.

5. The method for preparing the novel composite carbon dioxide adsorbent according to claim 2, characterized in that: The amount of glacial acetic acid added is 4 times the mass of calcium hydroxide powder.

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