Desulfurization-enhanced modified calcium hydroxide and preparation method thereof

Abstract

The invention discloses modified calcium hydroxide for enhanced desulfurization and a preparation method thereof, and relates to the technical field of calcium hydroxide preparation. The modified calcium hydroxide adsorbent is prepared from the following raw materials in parts by weight: 65-85 parts of modified calcium hydroxide, 1-5 parts of an absorption aid, 10-15 parts of a nano filler and 5-10 parts of organic amine. The preparation method comprises the following steps: modifying calcium hydroxide by mixed organic acid, adding an absorption aid and a nano filler, stirring, drying, grinding, sieving and the like to obtain modified calcium hydroxide powder, and finally adding organic amine to obtain the modified calcium hydroxide powder for strengthening desulfurization. Calcium hydroxide is modified by organic acid, and organic amine is added, so that the specific surface area of calcium hydroxide particles can be increased, the sulfur capacity can be increased, and the absorption rate of sulfur dioxide can be increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of calcium hydroxide preparation, and specifically relates to a preparation method of modified calcium hydroxide for enhanced desulfurization. Background Art

[0002] Sulfur dioxide pollutants in the atmosphere mainly come from industrial processes such as coal-fired power plants, iron and steel smelting, and chemical production. The emission of sulfur dioxide can cause problems such as acid rain, smog, and respiratory diseases. Therefore, it is very important to control the emission of sulfur dioxide.

[0003] Existing flue gas desulfurization technologies mainly convert sulfur dioxide into relatively stable sulfur-containing compounds through absorbents or adsorbents. Calcium hydroxide is a commonly used absorbent and is often used in dry and semi-dry flue gas desulfurization technologies. Dry and semi-dry flue gas desulfurization technologies can reduce the water consumption and have no secondary pollution. However, the absorption efficiency of sulfur dioxide is lower than that of the limestone-gypsum method. Therefore, how to improve the adsorption efficiency of calcium hydroxide for sulfur dioxide is a problem that needs to be solved.

[0004] Patent CN112295395B discloses a flue gas desulfurization agent, which is prepared by modifying calcium hydroxide with a surfactant and then adding additives and binders to the modified calcium hydroxide. This desulfurization agent has a wide operating temperature range and low energy consumption. However, the contents of additives such as iron oxide and manganese sulfate added in this desulfurization agent are relatively low. After absorbing sulfur dioxide, stable compounds are formed, resulting in a decrease in the adsorption efficiency of the desulfurization agent for sulfur dioxide, and the adsorption products are not easy to handle. In addition, the desulfurization efficiency of this adsorbent is greatly affected by the moisture content in the flue gas. In actual production, it is necessary to control the moisture content in the flue gas to be moderate, and the operation is more complicated. Summary of the Invention

[0005] In order to solve the problems of existing desulfurization agents being greatly affected by the moisture content in the flue gas, the adsorption efficiency changing during use, and the insufficient anti-sintering performance of the adsorbent, the present invention provides a modified calcium hydroxide for enhanced desulfurization and its preparation method. The modified calcium hydroxide for enhanced desulfurization provided by the present invention has characteristics such as good anti-sintering performance, little influence by flue gas, and little change in adsorption efficiency during use.

[0006] The specific technical solution of the present invention is as follows:

[0007] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 65-85 parts of modified calcium hydroxide, 1-5 parts of absorption aid, 10-15 parts of nano filler, and 5-10 parts of organic amine.

[0008] The modified calcium hydroxide for enhanced desulfurization of the present invention reacts an organic acid with calcium hydroxide to form a porous structure on the surface of calcium hydroxide, shortening the diffusion distance of sulfur dioxide into the interior of calcium hydroxide particles and improving the reaction activity of calcium hydroxide. Benzoic acid in the mixed acid can improve the hydrophobic property of calcium hydroxide and prevent the excessive humidity in the flue gas from affecting the desulfurization effect. The absorption aid increases the adsorption amount of sulfur dioxide through a chemical reaction and improves the adsorption rate. Monoethanolamine, diethanolamine can react with water and sulfur dioxide to form stable bisulfites or sulfonates, increasing the adsorption capacity of calcium hydroxide for sulfur dioxide. Tertiary amines can accelerate the hydration dissolution of sulfur dioxide. The three act synergistically to greatly improve the adsorption capacity and adsorption rate of calcium hydroxide for sulfur dioxide. At the same time, organic amines have a high selectivity for sulfur dioxide and can preferentially adsorb sulfur dioxide when carbon dioxide, nitrogen oxides and sulfur dioxide coexist.

[0009] The modified calcium hydroxide is calcium hydroxide modified by an organic acid. The organic acid is a mixture of acetic acid, oxalic acid and benzoic acid, and the weight ratio of the three is 2:2:1.

[0010] The organic acid can form a porous structure on the surface of calcium hydroxide particles, increasing the specific surface area of calcium hydroxide. At the same time, the organic acid radical and calcium ions form soluble complexes, promoting the uniform dispersion of calcium hydroxide particles. Benzoic acid can improve the hydrophobic property of calcium hydroxide, enabling the modified calcium hydroxide to handle high-humidity sulfur-containing flue gas. The loose structure on the surface of the modified calcium hydroxide shortens the diffusion distance of sulfur dioxide into the particles and accelerates the reaction rate. In addition, the residual organic matter forms an isolation layer between calcium hydroxide particles, which can inhibit the high-temperature sintering of calcium hydroxide.

[0011] Preferably, the absorption aid is one or more of sodium hydroxide, potassium hydroxide, magnesium hydroxide. More preferably, the absorption aid is sodium hydroxide.

[0012] Strong base absorption aids can react with sulfur dioxide quickly and efficiently, improving the reaction rate of sulfur dioxide with calcium hydroxide.

[0013] Preferably, the filler is nano-silica.

[0014] Nano-silica can fill the macropores on the surface of calcium hydroxide particles to form a hierarchical pore structure, further enhancing the adsorption capacity of sulfur dioxide.

[0015] Preferably, the organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine and triethanolamine, and the weight ratio is 1:1:2:1.

[0016] Monoethanolamine, diethanolamine, water and sulfur dioxide can react to form stable bisulfites or sulfonates, which can increase the adsorption capacity of calcium hydroxide for sulfur dioxide. Tertiary amines can accelerate the hydration and dissolution of sulfur dioxide. The synergistic effect of the three can greatly improve the adsorption capacity and adsorption rate. At the same time, organic amines have a high selectivity for sulfur dioxide and can preferentially adsorb sulfur dioxide when carbon dioxide, nitrogen oxides and sulfur dioxide coexist.

[0017] A preparation method of modified calcium hydroxide for enhanced desulfurization is as follows: 1) Calcium carbonate is subjected to high-temperature calcination, crushing and screening, digestion, filtration, dehydration and drying to obtain crude calcium hydroxide powder; 2) An organic acid mixed solution, a nano filler and an absorption aid are added to the crude calcium hydroxide powder. After reaction, modified calcium hydroxide is obtained through drying activation and grinding and sieving; 3) Organic amine is added to the modified calcium hydroxide to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0018] Beneficial effects:

[0019] The modified calcium hydroxide for enhanced desulfurization of the present invention has a higher adsorption capacity for sulfur dioxide. In the wet desulfurization process, the adsorption rate is higher than that of ordinary calcium hydroxide. In the dry desulfurization process, it has a higher adsorption rate at low temperatures and is not easy to sinter. The modified calcium hydroxide for enhanced desulfurization of the present invention has a high selectivity for sulfur dioxide and can preferentially adsorb sulfur dioxide when carbon dioxide, nitrogen oxides and sulfur dioxide coexist. The manufacturing process is simple, the raw materials are easy to obtain, and no secondary pollution is generated. Specific embodiments

[0020] To better illustrate the technical effects of the present invention, the following specific examples and comparative examples are analyzed.

[0021] General example:

[0022] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 65-85 parts of modified calcium hydroxide, 1-5 parts of absorption aid, 10-15 parts of nano filler, and 5-10 parts of organic amine.

[0023] The modified calcium hydroxide is calcium hydroxide modified by organic acids, and the organic acids are a mixture of acetic acid, oxalic acid and benzoic acid, and the weight ratio of the three is 2:2:1.

[0024] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine and triethanolamine, and the weight ratio is 1:1:2:1.

[0025] A preparation method of modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After successive reactions in the three-stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it using a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-fillers and absorption aids and stir evenly. Then dry it at 100 - 120 °C and then perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 hour to decompose organic calcium salts. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300-mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0026] Example 1

[0027] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, 12.5 parts of nano-silica, and 7.5 parts of organic amine.

[0028] The modified calcium hydroxide is calcium hydroxide modified with organic acids. The organic acids are a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0029] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine, and the weight ratio is 1:1:2:1.

[0030] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After sequential reactions in the three-stage digester, obtain crude calcium hydroxide slurry. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it using a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C and then perform heat treatment at 200 - 300 °C for 1 hour in an inert atmosphere to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass through a 300-mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0031] Example 2

[0032] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 65 parts of modified calcium hydroxide, 1 part of sodium hydroxide, 10 parts of nano-silica, and 5 parts of organic amine.

[0033] The modified calcium hydroxide is calcium hydroxide modified by organic acid. The organic acid is a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0034] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine, and the weight ratio is 1:1:2:1.

[0035] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After sequential reactions in the three-stage digester, obtain crude calcium hydroxide slurry. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it using a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C and then perform heat treatment at 200 - 300 °C for 1 hour in an inert atmosphere to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass through a 300-mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain the modified calcium hydroxide powder with enhanced desulfurization performance.

[0036] Example 3

[0037] A modified calcium hydroxide with enhanced desulfurization performance is prepared from the following raw materials by weight: 85 parts of modified calcium hydroxide, 5 parts of sodium hydroxide, 15 parts of nano-silica, and 10 parts of organic amine.

[0038] The modified calcium hydroxide is calcium hydroxide modified by organic acids, and the organic acids are a mixture of acetic acid, oxalic acid, and benzoic acid with a weight ratio of 2:2:1.

[0039] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine with a weight ratio of 1:1:2:1.

[0040] A preparation method of a modified calcium hydroxide with enhanced desulfurization performance is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing, and screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After successive reactions in the three-stage digester, obtain a crude calcium hydroxide slurry. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it by a centrifuge. Finally, dry it at 150 - 300 °C to obtain a crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C, and perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 hour to decompose the organic calcium salt. Finally, grind the obtained modified calcium hydroxide powder and pass it through a 300-mesh sieve to obtain the modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain the modified calcium hydroxide powder with enhanced desulfurization performance.

[0041] Example 4

[0042] A modified calcium hydroxide with enhanced desulfurization performance is prepared from the following raw materials by weight: 75 parts of modified calcium hydroxide, 12.5 parts of nano-silica, and 7.5 parts of organic amine.

[0043] The modified calcium hydroxide is calcium hydroxide modified by organic acids, and the organic acids are a mixture of acetic acid, oxalic acid, and benzoic acid with a weight ratio of 2:2:1.

[0044] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine with a weight ratio of 1:1:2:1.

[0045] A preparation method of modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing, and screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After sequential reactions in the three-stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve tray and then dehydrate it by a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-silica and stir evenly. Then dry it at 100 - 120 °C and heat-treat it at 200 - 300 °C for 1 hour in an inert atmosphere to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300-mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0046] Example 5

[0047] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, and 7.5 parts of organic amine.

[0048] The modified calcium hydroxide is calcium hydroxide modified by organic acid. The organic acid is a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0049] The organic amine is a mixture of monoethanolamine, diethanolamine, N-methyldiethanolamine, and triethanolamine, and the weight ratio is 1:1:2:1.

[0050] A preparation method of modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three - stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After step - by - step reaction in the three - stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it by a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add sodium hydroxide and stir evenly. After drying at 100 - 120 °C, perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 h to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300 - mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0051] Example 6 A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, and 12.5 parts of nano - silica.

[0052] The modified calcium hydroxide is calcium hydroxide modified by organic acids. The organic acids are a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0053] The organic amine is a mixture of monoethanolamine, diethanolamine, N - methyldiethanolamine, and triethanolamine, and the weight ratio is 1:1:2:1.

[0054] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three - stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After step - by - step reaction in the three - stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it by a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano - silica and sodium hydroxide and stir evenly. After drying at 100 - 120 °C, perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 h to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300 - mesh sieve to obtain modified calcium hydroxide powder;

[0055] Example 7

[0056] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, 12.5 parts of nano-silica, and 7.5 parts of organic amine.

[0057] The modified calcium hydroxide is calcium hydroxide modified by organic acid, and the organic acid is a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0058] The organic amine is a mixture of diethanolamine, N-methyldiethanolamine, and triethanolamine, and the weight ratio is 1:2:1.

[0059] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing, and screen calcium oxide stones with a particle size less than 10 mm and place them in a three-stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After successive reactions in the three-stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it by a centrifuge, and finally dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano-silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C and heat-treat it at 200 - 300 °C in an inert atmosphere for 1 hour to decompose the organic calcium salt. Finally, grind the obtained modified calcium hydroxide crude powder and pass it through a 300-mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain a modified calcium hydroxide powder for enhanced desulfurization.

[0060] Example 8

[0061] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, 12.5 parts of nano-silica, and 7.5 parts of organic amine.

[0062] The modified calcium hydroxide is calcium hydroxide modified by organic acid, and the organic acid is a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0063] The organic amine is a mixture of monoethanolamine, N-methyldiethanolamine, and triethanolamine, and the weight ratio is 1:2:1

[0064] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three - stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After successive reactions in the three - stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it using a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano - silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C, and then perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 hour to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300 - mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder for enhanced desulfurization.

[0065] Example 9

[0066] A modified calcium hydroxide for enhanced desulfurization is prepared from the following raw materials in parts by weight: 75 parts of modified calcium hydroxide, 3 parts of sodium hydroxide, 12.5 parts of nano - silica, and 7.5 parts of organic amine.

[0067] The modified calcium hydroxide is calcium hydroxide modified by organic acids. The organic acids are a mixture of acetic acid, oxalic acid, and benzoic acid, and the weight ratio of the three is 2:2:1.

[0068] The organic amine is a mixture of monoethanolamine and diethanolamine, and the weight ratio is 1:1

[0069] A preparation method of a modified calcium hydroxide for enhanced desulfurization is as follows: 1) Put calcium carbonate into a rotary kiln and calcine it at a temperature of 900 - 1200 °C for 8 - 12 h. Add the calcined product to a crusher for crushing. Screen calcium oxide stones with a particle size less than 10 mm and place them in a three - stage digester. Add pure water with a mass 1.1 - 1.3 times that of calcium oxide to the digester for digestion reaction. After successive reactions in the three - stage digester, a crude calcium hydroxide slurry is obtained. Filter the obtained crude calcium hydroxide slurry through a sieve plate and then dehydrate it using a centrifuge. Finally, dry it at 150 - 300 °C to obtain crude calcium hydroxide powder; 2) Add a mixed acid of acetic acid, oxalic acid, and benzoic acid to the crude calcium hydroxide powder and stir at 50 - 70 °C for 1 - 2 h. Then add nano - silica and sodium hydroxide and stir evenly. Then dry it at 100 - 120 °C, and then perform heat treatment at 200 - 300 °C in an inert atmosphere for 1 hour to decompose the organic calcium salt. Finally, grind the obtained modified crude calcium hydroxide powder and pass it through a 300 - mesh sieve to obtain modified calcium hydroxide powder; 3) Add organic amine to the modified calcium hydroxide powder to obtain the modified calcium hydroxide powder with enhanced desulfurization ability.

[0070] Comparative Example 1

[0071] The calcium hydroxide powder in this comparative example was manufactured by a conventional process.

[0072] Measure the sulfur capacity performance and sulfur dioxide absorption performance of Examples 1 - 9 and Comparative Example 1

[0073] The test method for sulfur capacity performance was carried out according to the standard specified in HG / 2513.

[0074] Sulfur dioxide absorption performance test:

[0075] Take 10 g of the modified calcium hydroxide powder with enhanced desulfurization ability, dissolve it in 100 mL of distilled water, stir at 120 r / min, and introduce sulfur dioxide gas into the container at a flow rate of 0.1 L / min for 10 min, then calculate the sulfur dioxide absorption rate.

[0076] The test results are shown in Table 1: Table 1 Sulfur capacity % <![CDATA[Sulfur dioxide absorption rate (×10 -5 mol / m 2 ·s)]]> Example 1 47.3 12.57 Example 2 43.1 10.35 Example 3 49.6 11.29 Example 4 45.5 9.34 Example 5 45.3 12.57 Example 6 42.1 8.57 Example 7 45.6 11.49 Example 8 47.1 12.13 Example 9 47.3 11.59 Comparative Example 1 30 8.77

[0077] Comparing the data of Examples 1 - 4, it can be seen that the absorption aid has a great influence on the sulfur capacity and sulfur dioxide absorption rate of the modified calcium hydroxide. This is because the strong base absorption aid can increase the pH value of the slurry and accelerate the dissolution and absorption of sulfur dioxide.

[0078] Comparing the data of Example 1 and Example 5, it can be seen that the nano filler has no obvious influence on the sulfur dioxide absorption rate, but can increase the sulfur capacity of the modified calcium hydroxide. This is because after the organic acid reacts with the calcium hydroxide particles, a porous structure is formed on the surface of the calcium hydroxide particles, and nano - silica can fill the larger pores on the surface of the calcium hydroxide particles to a certain extent, thereby increasing the sulfur capacity.

[0079] Comparing the data of Example 1 and Example 6, it can be seen that the organic amine has a great influence on both the sulfur capacity and sulfur dioxide absorption rate of the modified calcium hydroxide. This is because the amino group of the organic amine can react with sulfur dioxide to achieve the adsorption of sulfur dioxide.

[0080] Comparing the data of Example 1 and Examples 7 - 9, it can be seen that monoethanolamine will affect the sulfur capacity and sulfur dioxide absorption rate of the modified calcium hydroxide, and diethanolamine, N - methyldiethanolamine, and triethanolamine will affect the sulfur dioxide absorption rate of the modified calcium hydroxide. This is because primary amines and secondary amines have a higher absorption efficiency for sulfur dioxide, but will produce relatively stable carbamates and are not easy to regenerate. While tertiary amine organic amines have a lower absorption rate but better regeneration performance.

[0081] The raw materials and equipment used in the present invention are all common raw materials and equipment in the art unless otherwise specified; the methods used in the present invention are all conventional methods in the art unless otherwise specified.

[0082] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any simple modification, change, and equivalent transformation made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A modified calcium hydroxide for enhanced desulfurization, characterized in that, It is prepared from the following raw materials in parts by weight: 65 - 85 parts of modified calcium hydroxide, 1 - 5 parts of absorption aid, 10 - 15 parts of nano filler, and 5 - 10 parts of organic amine.

2. The modified calcium hydroxide for enhanced desulfurization according to claim 1, wherein, The modified calcium hydroxide is calcium hydroxide modified by organic acid, and the organic acid is a mixture of acetic acid, oxalic acid, and benzoic acid.

3. The modified calcium hydroxide for enhanced desulfurization according to claim 1, wherein In the organic acid mixture, the weight ratio of acetic acid, oxalic acid, and benzoic acid is 2:2:

1.

4. The modified calcium hydroxide for enhanced desulfurization according to claim 1, characterized in that, The absorption aid is one or more of sodium hydroxide, potassium hydroxide, and magnesium hydroxide.

5. The modified calcium hydroxide for enhanced desulfurization according to claim 1, characterized in that, The nano filler is nano silica.

6. The modified calcium hydroxide for enhanced desulfurization according to claim 1, wherein The organic amine is a mixture of monoethanolamine, diethanolamine, N - methyldiethanolamine, and triethanolamine, and their weight ratio is 1:1:2:

1.

7. A preparation method of modified calcium hydroxide for enhanced desulfurization according to any one of claims 1-6, characterized in that, It includes the following steps: 1) Calcium carbonate is subjected to high - temperature calcination, crushing and screening, digestion, filtration, dehydration, and drying treatments to obtain crude calcium hydroxide powder. 2) An organic acid mixed solution, a nano filler, and an absorption aid are added to the crude calcium hydroxide powder. After reaction, modified calcium hydroxide is obtained through drying activation and grinding and sieving. 3) An organic amine is added to the modified calcium hydroxide powder to obtain modified calcium hydroxide powder with enhanced desulfurization.

8. The preparation method of the modified calcium hydroxide for enhanced desulfurization according to claim 7, characterized in that, The pure water added during the digestion treatment is 1.1 - 1.3 times the mass of calcium hydroxide.

9. The preparation method of the modified calcium hydroxide for enhanced desulfurization according to claim 7, characterized in that, The concentration of the organic acid mixed solution is 5 - 10%.

10. The preparation method of the modified calcium hydroxide for enhanced desulfurization according to any one of claims 7-9, characterized in that, The activation treatment is heat treatment at 200 - 300 °C for 1 hour in an inert atmosphere.