A deammoniation agent for coke oven gas and its preparation method

Abstract

The application discloses a coke oven gas deaminating agent and a preparation method thereof. The deaminating agent takes zinc and copper metal salts as active components, nickel and cobalt metal salts as auxiliary component, and takes magnesium aluminate spinel prepared from aluminum oxide and magnesium oxide as a carrier. The deaminating agent has the characteristics of high deaminating activity, high ammonia content penetration, and renewable utilization, is used for gas phase deamination, and is particularly suitable for a coke oven gas purification process, and can reduce the ammonia content to 0.1 ppm.

Description

Technical Field

[0001] This invention relates to a deammoniation agent for coke oven gas and its preparation method, belonging to the field of coke oven gas purification. Background Technology

[0002] The steel industry has driven the development of the coking industry, making my country the world's largest coke producer. Compaction coking is a new coking process developed this year, suitable for my country's shortage of strongly caking coal. Each ton of coke can produce over 400 cubic meters of raw coal gas as a byproduct, its main components being methane and hydrogen, possessing abundant energy and chemical utilization value. Comprehensive utilization of coke oven gas reduces pollution and aligns with national industrial development requirements for building a resource-saving society, creating green industry, and a circular economy. The raw coal gas enters the gas collecting pipe from the riser pipe, where a large amount of circulating water is injected, lowering the temperature from approximately 700℃ to 80-85℃. A large amount of impurities such as tar, naphthalene, ammonia, hydrogen cyanide, and phenol are cooled down. The circulating ammonia water and raw coal gas flow concurrently into the primary cooler, where the gas continues to be cooled and condensed. The gas temperature exiting the primary cooler is 21~23℃. Tar mist is removed in the tar trap, then the gas is pressurized by a blower, hydrogen sulfide is removed in the desulfurization tower, ammonia is recovered in the ammonium sulfate unit, benzene is recovered in the benzene washing unit, and some organic sulfur is removed. The purified gas is called coke oven gas.

[0003] The comprehensive utilization of coke oven gas can be divided into three categories: fuel, reducing agent, and chemical raw material. Among these, coke oven gas has a broad market as a chemical raw material for methanol synthesis, and can be further used to produce olefins, formaldehyde, dimethyl ether, and other chemical products. The main processes for producing methanol from coke oven gas include: tar removal by filtration, pre-desulfurization, fine desulfurization, alkane conversion, methanol synthesis, and distillation.

[0004] Excessive ammonia content in coke oven gas can alter the structural properties of iron-molybdenum and cobalt-molybdenum hydrogenation catalysts, leading to the loss of active sites. Molybdenum in these catalysts reacts with ammonia to form salts, which adhere to the catalyst surface, clogging pores and active sites, resulting in irreversible catalyst deactivation. Simultaneously, ammonium salts can cause equipment corrosion and damage. In the presence of trace amounts of water, ammonia can react with copper in methanol catalysts to form copper-ammonia complex ions, causing copper loss and ultimately deactivating the methanol catalyst.

[0005] Therefore, installing a fixed-bed deammoniation tower in front of the coke oven gas buffer tank can prevent ammonium salt crystals from corroding equipment and clogging pipelines, avoid ammonia poisoning of iron-molybdenum, cobalt-molybdenum hydrodesulfurization catalysts and methanol synthesis catalysts, and improve the service life of catalysts and the stability of the production system. Summary of the Invention

[0006] The purpose of this invention is to provide a coke oven gas deammoniation agent and its preparation method, based on the current process of methanol synthesis from coke oven gas, which shows that ammonia has a toxic effect on the iron-molybdenum hydrogenation and cobalt-molybdenum hydrogenation catalysts in the desulfurization stage and the copper-based catalysts in the methanol synthesis stage.

[0007] The deammoniation agent involved in this invention uses magnesium aluminum spinel as a carrier, with active components and additives attached; wherein the active components are zinc and copper metal salts, and the additives are one or more of cobalt and nickel metal salts; based on the mass of the carrier, the zinc salt has a mass fraction of 14-18%, the copper salt has a mass fraction of 7-10%, and the additives have a mass fraction of 2-4%. The preparation method of the deammoniation agent includes the following steps:

[0008] Weigh out macroporous pseudoboehmite, microporous pseudoboehmite, magnesia powder, quick-release powder, and guar gum in a certain proportion, dry mix them evenly, add an aqueous solution of flux, knead and extrude into strips, then seal and cure for 24~48h, calcine at 400~450℃ for 4h, soak in water at 80℃ for 2h, filter, dry at 120℃, and calcine at 600~650℃ for 4~6h to obtain the carrier.

[0009] Weigh out copper, zinc, nickel, and cobalt salts in a certain proportion and dissolve them in deionized water. Heat the solution to 50-60°C until the metal salts are completely dissolved. Adjust the pH to 3-4 with sulfuric acid or phosphoric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution.

[0010] The impregnation solution from step (2) was loaded onto the carrier prepared in step (1) using the equal volume impregnation method. The impregnation time was 10-24 hours, and the carrier was dried at 80-100℃ to obtain the deammoniation agent.

[0011] The soaking solution in step (1) is used to prepare the Cu-Zn-Co-Ni salt soaking solution in step (2). Sulfuric acid or phosphoric acid is added to the soaking solution to adjust the pH so that the deaming agent is weakly acidic, which inhibits the ionization of inorganic sulfur and the formation of metal sulfides, and increases the ammonia capacity and regeneration times of the deaming agent.

[0012] Magnesia powder is made from brucite ore, which is finely ground to 400 mesh using a ball mill. The fine powder is then calcined in a muffle furnace at 400℃ for 3 hours. While still hot, the powder is rapidly cooled in deionized water, slurried, and allowed to stand for 24 hours. Finally, it is dried in a film at 120℃ and then flash-dried at 180℃ to obtain a grayish-white powder. The high-temperature calcination and low-temperature rapid cooling process improves the binding properties of the magnesia powder and the strength and water resistance of the magnesium aluminum spinel carrier.

[0013] The mass ratio of macroporous pseudoboehmite, microporous pseudoboehmite, magnesia powder, quick-release powder, guar gum, and additives is 25:45:12~18:10:1:2~3. Guar gum can be added as a dry powder or first added to an aqueous solution of the additives to form a slurry before being mixed in.

[0014] The flux is a ternary molten salt consisting of 35% zinc sulfate, 58% aluminum chloride, and 7% sodium phosphate. The aluminum chloride component can dissolve at low temperatures, ionizing to release Al. 3+ It can greatly promote the transformation of oxidized aluminum in the raw material into free Al. 3+ And Al 3+ The quantity will not decrease; however, the zinc sulfate component lowers the dissolution temperature of the molten salt, and under low-temperature conditions, Al 3+ This can promote the ionization of magnesium oxide and aluminum oxide to release Mg. 2+ And Al 3+ Sodium phosphate reduces the viscosity of molten salt, making Mg... 2+ And Al 3+ The migration rate is faster. The molten salt component can promote the migration of Mg from the raw materials during roasting. 2+ And Al 3+ The migration of these molecules lowers the formation temperature of the magnesium aluminum spinel crystal phase.

[0015] Copper, zinc, cobalt, and nickel salts are one or more of sulfates and chlorides. These metal salts all have a certain degree of hygroscopicity, adsorbing water in the gas phase and separating into salts containing water of crystallization. The water of crystallization can quickly capture ammonia in the gas phase and generate NH3·H2O, which then ionizes to release NH4+ and undergoes a chemical complexation reaction with the active components to achieve the purpose of removing ammonia.

[0016] A deammoniation tower is installed at the very beginning, meaning the coke oven gas passes through a fixed-bed deammoniation tower before entering the buffer gas holder. This removes ammonia from the gas phase, preventing the formation of ammonium chloride, ammonium carbonate, and other crystals from ammonia and chlorides / oxides in the buffer gas holder, which can corrode equipment and clog pipelines. The dechlorinating agent has an ammonia capacity of ≥8.0% at room temperature. The deammoniation agent regeneration process parameters are: nitrogen, air, or steam atmosphere, 140~160℃ / 5h, 180℃ / 1h, and a regeneration gas space velocity of 2000h⁻¹. -1 The regenerated ammonia capacity is ≥7.5%; the regenerated gas is condensed with water, and the by-product ammonia water can be used in the SCR denitrification section of the flue gas.

[0017] The above-described technical solution of the present invention has the following advantages:

[0018] Zinc and copper metal cations can undergo complexation reactions with ammonia at room temperature to form stable complexes, thereby achieving the purpose of ammonia removal. This ammonia removal agent has an ammonia capacity of over 8.0%. Cobalt and nickel ions are auxiliary components that readily undergo complexation reactions with ammonia and transfer ammonia to zinc and copper metal cations, promoting the ammonia adsorption rate. The ammonia removal accuracy of this ammonia removal agent reaches 0.1 ppm.

[0019] Adding sulfuric acid or phosphoric acid to the impregnation solution to adjust the pH makes the deaming agent weakly acidic, which can inhibit the adsorption, ionization and metal sulfide formation of hydrogen sulfide in the gas phase in the deaming agent, thereby improving the ammonia capacity and service life of the deaming agent.

[0020] The metal ion complex releases ammonia in the high-temperature gas phase, and the deaming agent is regenerated and can be reused. Using magnesium aluminum spinel as a carrier increases the number of times the deaming agent can be regenerated, and the deaming agent can be completely regenerated in a water vapor atmosphere. The ammonia capacity of the regenerated deaming agent is more than 7.5%.

[0021] In the preparation of magnesium aluminum spinel, the addition of molten salt components can promote the oxidation of Mg during the calcination process of the raw materials. 2+ And Al 3+ The migration of Mg and Aluminum spinel crystals reduces the formation time of the Mg-Aluminum spinel phase, i.e., calcination at 400~450℃ for 4 hours, melting of molten salt, and Mg 2+ And Al 3+ Under the action of molten salt, the minerals migrate and combine to initially form magnesium aluminum spinel nuclei. Calcination at 600-650℃ for 4-6 hours yields a magnesium aluminum spinel carrier with good crystallinity. Low-temperature calcination consumes less energy, and the resulting magnesium aluminum spinel exhibits high crystallinity and a large specific surface area, which is more conducive to the loading of active ingredients.

[0022] The regenerated gas washing solution is rich in ammonia and can be used for flue gas SCR denitrification. It produces no pollution emissions and no secondary pollution. It uses toxic substances in the gas phase to treat flue gas pollutants, thus treating waste with waste. Detailed Implementation

[0023] The characteristics, preparation method and deaming performance of the deaming agent of the present invention will be described in detail below with specific implementation examples. However, the present invention is not limited to these examples, nor does it constitute any limitation on the scope of the invention.

[0024] Example 1

[0025] Preparation of magnesium powder

[0026] Magnesia ore is used as raw material. It is finely ground to 400 mesh using a ball mill. The fine powder is placed in a muffle furnace and roasted at 400℃ for 3 hours. Then, while it is hot, the fine powder is added to deionized water and cooled rapidly. The mixture is slurryed and mixed evenly, and left to stand for 24 hours. Then, it is dried by scraping at 120℃ and flash drying at 180℃ to obtain magnesia powder.

[0027] Preparation of carrier

[0028] Weigh out 50g of macroporous pseudoboehmite, 90g of microporous pseudoboehmite, 36g of magnesia powder, 20g of quick-release powder, and 2g of guar gum, and mix them evenly with dry powder. Weigh out 0.7g of zinc sulfate, 1.16g of aluminum chloride, and 0.14g of sodium phosphate, dissolve them in 110g of water, and then slowly add them to the dry powder mixture. Mix them in a mortar for 30 minutes, extrude them into strips, place them in a sealed bag and cure them for 48 hours, calcine them at 450℃ for 4 hours, soak them in water at 80℃ for 2 hours, filter the water, dry them at 120℃, and calcine them at 600℃ for 6 hours to obtain carrier one.

[0029] Weigh out 50g of macroporous pseudoboehmite, 90g of microporous pseudoboehmite, 24g of magnesia powder, 20g of quick-release powder, and 2g of guar gum, and mix them evenly with dry powder. Weigh out 1.05g of zinc sulfate, 1.74g of aluminum chloride, and 0.21g of sodium phosphate, dissolve them in 110g of water, and then slowly add them to the dry powder mixture. Mix them in a mortar for 30 minutes, extrude them into strips, place them in a sealed bag and cure them for 24 hours, calcine them at 400℃ for 4 hours, soak them in water at 80℃ for 2 hours, filter the water, dry them at 120℃, and calcine them at 650℃ for 4 hours to obtain carrier two.

[0030] Weigh out 50g of macroporous pseudoboehmite, 90g of microporous pseudoboehmite, 28g of magnesia powder, 20g of quick-release powder, and 2g of guar gum, and mix them evenly with dry powder. Weigh out 0.91g of zinc sulfate, 1.51g of aluminum chloride, and 0.18g of sodium phosphate, dissolve them in 110g of water, and then slowly add them to the dry powder mixture. Mix them in a mortar for 30 minutes, extrude them into strips, place them in a sealed bag and cure them for 24 hours, calcine them at 450℃ for 4 hours, soak them in water at 80℃ for 2 hours, filter the water, dry them at 120℃, and calcine them at 650℃ for 5 hours to obtain carrier three.

[0031] The physicochemical properties of the carriers prepared by the above method are as follows:

[0032] name <![CDATA[Specific surface area / m 2 ·g -1 > <![CDATA[Pore volume / mL·g -1 > Aperture / nm <![CDATA[Strength / N·cm -1 > Carrier 1 252.12 0.5025 8.88 150.0 Carrier 2 278.39 0.5139 8.93 145.2 Carrier 3 268.86 0.5268 9.17 153.7

[0033] Example 2

[0034] Weigh 24.94g of zinc sulfate heptahydrate, 15.64g of copper sulfate pentahydrate, 3.63g of nickel sulfate heptahydrate, and 3.63g of cobalt sulfate heptahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix evenly, and adjust the pH to 3-4 with sulfuric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier one, let it stand for 10h, and dry at 100℃ to obtain deammonigenin A.

[0035] Example 3

[0036] Weigh out 14g of zinc chloride, 12.68g of copper chloride dihydrate, 3.67g of nickel chloride hexahydrate, and 3.66g of cobalt chloride hexahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix well, and adjust the pH to 3-4 with sulfuric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier one, let it stand for 24h, and dry at 80℃ to obtain deammoniation agent B.

[0037] Example 4

[0038] Weigh out 18g of zinc sulfate heptahydrate, 8.88g of copper chloride dihydrate, 1.83g of nickel chloride hexahydrate, and 1.71g of cobalt sulfate heptahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix well, and adjust the pH to 3-4 with phosphoric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier II, let it stand for 14h, and dry at 90℃ to obtain deammonigenin C.

[0039] Example 5

[0040] Weigh out 16g of zinc sulfate heptahydrate, 14.08g of copper sulfate pentahydrate, 3.63g of nickel sulfate heptahydrate, and 1.83g of cobalt chloride hexahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix well, and adjust the pH to 3-4 with phosphoric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier III, let it stand for 18h, and dry at 80℃ to obtain deammonigenin D.

[0041] Example 6

[0042] Weigh out 30.28g of zinc sulfate heptahydrate, 10.15g of copper chloride dihydrate, and 5.44g of cobalt sulfate heptahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix well, and adjust the pH to 3-4 with phosphoric acid to obtain Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier III, let it stand for 20h, and dry at 95℃ to obtain deammonigenin E.

[0043] Example 7

[0044] Weigh out 17.81g of zinc sulfate heptahydrate, 8g of zinc chloride, 6.26g of copper sulfate pentahydrate, 5.07g of copper chloride dihydrate, 1.81g of cobalt sulfate heptahydrate, 1.83g of cobalt chloride hexahydrate, 1.81g of nickel sulfate heptahydrate, and 1.83g of nickel chloride hexahydrate, dissolve them in deionized water, heat to 50-60℃ until the metal salts are completely dissolved, mix well, and adjust the pH to 3-4 with phosphoric acid to obtain a Cu-Zn-Co-Ni salt impregnation solution; use the equal volume impregnation method to attach the impregnation solution to 100g of carrier III, let it stand for 11h, and dry at 85℃ to obtain deammoniation agent F.

[0045] Example 8

[0046] The ammonia capacity of the deammoniation agent in the gas phase of coke oven gas was determined and evaluated through regeneration experiments. The laboratory-prepared coke oven gas contained 10% CO2, 35% CO, 4% H2, 50% N2, and 1% methane + ethane, with harmful substances including 200 ppm sulfides and 500 ppm ammonia. Using an outlet ammonia concentration of 0.1 ppm as an indicator, the ammonia capacity of the deammoniation agent prepared in the above examples was determined. Experimental parameters were: room temperature (35℃), normal pressure, space velocity 8000~15000 / h, a φ12mm inner diameter glass reactor with a built-in φ0.4mm thermocouple, and the deammoniation agent was pulverized to 40~60 mesh, resulting in 3 mL of the solution. The results are shown in the table below.

[0047]

Claims

1. A method for preparing a coke oven gas deammoniation agent, characterized in that: This deammoniation agent uses magnesium aluminum spinel as a carrier to load active components and additives; wherein the active components are zinc and copper metal salts, and the additives are one or more of nickel and cobalt metal salts; based on the mass of the carrier, the zinc salt has a mass fraction of 14-18%, the copper salt has a mass fraction of 7-10%, and the additives have a mass fraction of 2-4%; its preparation method includes the following steps: (1) Grind the magnesia ore to 400 mesh, roast at 400℃ for 3 hours, then add the fine powder to deionized water while it is hot and cool it quickly. Mix it evenly, let it stand for 24 hours, and then dry it by scraping at 120℃ and flash drying at 180℃ to obtain magnesia powder. (2) Weigh out macroporous pseudoboehmite, microporous pseudoboehmite, magnesia powder, quick-release powder, and guar gum in a certain proportion, dry mix them evenly, add an aqueous solution of flux, knead and extrude into strips, then seal and cure for 24~48h, calcine at 400~450℃ for 4h, soak in water at 80℃ for 2h, filter, dry at 120℃, and calcine at 600~650℃ for 4~6h to obtain the carrier; The flux is a ternary molten salt with a mass fraction of 35% zinc sulfate, 58% aluminum chloride, and 7% sodium phosphate. (3) Weigh out copper, zinc, nickel and cobalt salts in a certain proportion and dissolve them in deionized water. Heat to 50~60℃ until the metal salts are completely dissolved, and adjust the pH to 3~4 with sulfuric acid or phosphoric acid to obtain Cu-Zn-Co-Ni salt impregnation solution; (4) The impregnation solution from step (3) is loaded onto the carrier obtained in step (2) using the equal volume impregnation method. The impregnation time is 10~24h, and the carrier is dried at 80~100℃ to obtain the deammoniation agent.

2. The method for preparing a coke oven gas deammoniation agent according to claim 1, characterized in that: In step (3), the copper, zinc, cobalt and nickel salts are sulfates or metal chlorides; the immersion solution in step (2) is used to prepare the Cu-Zn-Co-Ni salt immersion solution in step (3).

3. The method for preparing a coke oven gas deammoniation agent according to claim 1, characterized in that: Ammonia capacity ≥ 8.0%, regenerator ammonia capacity ≥ 7.5%.

4. The method for preparing a coke oven gas deammoniation agent according to claim 1, characterized in that: The ammonia removal agent regeneration process is carried out in a nitrogen, air, or water vapor atmosphere at 140~160℃ / 5h or 180℃ / 1h, with a gas space velocity of 2000h⁻¹. -1 The regenerated gas is condensed with water, producing ammonia water as a byproduct.

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