A water-based denitration catalyst and preparation method thereof

Abstract

The present invention provides a water-based denitration catalyst and a preparation method thereof, comprising: dissolving a soluble cerium salt and a soluble transition metal salt in water to obtain a solution A; adding a coupling agent to n-butyl titanate while stirring, then adding glacial acetic acid, adding nitric acid after mixing evenly, to obtain a solution B; slowly adding solution A to solution B, mixing evenly, to obtain a water-based denitration catalyst. The preparation method of the present invention does not use an ethanol solvent, has a simple process, a short cycle, and is safe and environmentally friendly; the water-based denitration catalyst prepared by the present invention is a water-based clear solution, the catalyst is uniform, has no component segregation, is easy to coat, has low cost, is environmentally friendly and safe, and can be applied to various coating processes such as vacuum impregnation and spin coating, the coating is more uniform, and the pores are not easily blocked, and the occurrence of problems such as increased filtration resistance of the integrated dust removal and denitration material can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas denitration, and in particular to a water-based denitration catalyst and a preparation method thereof. Background Art

[0002] The control of combustion flue gas pollution is a strategic point in my country's energy and environmental fields. At present, flue gas denitrification and dust removal purification technologies are mainly completed in the denitrification unit and the dust removal unit respectively. The independent operation of the denitrification and dust removal units not only increases the floor space, but also significantly increases the equipment investment and operating costs. Therefore, integrating flue gas denitrification and dust removal, shortening the process flow, and reducing process costs have become an important development direction in the current flue gas denitrification and dust removal purification field. At present, the preparation method of integrated dust removal and denitrification materials is usually to load the SCR denitrification catalyst inside or on the surface of the ceramic carrier pores by sol-gel method, impregnation method, centrifugal coating method, etc., and obtain a dust removal and denitrification integrated material with both dust removal and denitrification functions after heat treatment, so as to achieve integrated denitrification and dust removal performance.

[0003] In the preparation process of integrated dust removal and denitration materials, vanadium-based catalysts are mainly selected as denitration catalysts. For example, patent CN111495379A discloses a denitration catalyst and its preparation method and application, using vanadate as the active component, titanium dioxide as the carrier, adding dispersants and enhancers to prepare denitration catalysts. Patent CN111036192A discloses a coated wear-resistant vanadium-based denitration catalyst and its preparation and application, using vanadium source, tungsten source, molybdenum source and titanium source to prepare catalyst powder, adding binder, structural enhancer, dispersant, deionized water, and obtaining catalyst slurry after ball milling. In addition, cerium-based catalysts have also been studied in the preparation process of integrated dust removal and denitration materials. However, the vanadium-based catalysts used in the preparation of integrated dust removal and denitrification materials are usually vanadium-based slurry systems, and the cerium-based catalysts are alcohol-based cerium-based solution systems. The following problems exist in the slurry preparation and loading: 1) When the catalyst is a slurry system, the slurry is usually an oxide particle slurry. Although it has a certain degree of dispersibility, the particle size is relatively large, and the components are segregated and uneven after long-term storage. In addition, the catalyst particles are large and easily clog the pores, resulting in a significant increase in the filtration resistance of the integrated dust removal and denitrification materials, a long production cycle, and a high catalyst cost. 2) When the catalyst is an alcohol-based solution system, ethanol is used as the solvent, which faces safety and environmental protection pressures, and has stringent experimental equipment requirements and high costs. Summary of the invention

[0004] The present invention provides a water-based denitration catalyst and a preparation method thereof to solve the above problems. The preparation method of the water-based denitration catalyst of the present invention has a simple process, a short cycle, safety and environmental protection, and the prepared water-based denitration catalyst is a water-based clear solution, the catalyst is uniform, has no component segregation, is easy to coat, has low cost, is environmentally friendly and safe, and can be applied to various coating processes such as vacuum impregnation and spin coating. The coating is more uniform, and it is not easy to clog the channels, which can avoid the occurrence of problems such as increased filtration resistance of dust removal and denitration integrated materials.

[0005] On the one hand, the present invention provides a method for preparing a water-based denitration catalyst, comprising the following steps: dissolving a soluble cerium salt and a soluble transition metal salt in water to obtain a solution A; adding a coupling agent to n-butyl titanate while stirring, then adding glacial acetic acid, mixing evenly, and then adding nitric acid to obtain a solution B; slowly adding the solution A to the solution B, mixing evenly, to obtain the water-based denitration catalyst.

[0006] In some embodiments of the present invention, when preparing solution A, the mass ratio of the soluble cerium salt, the soluble transition metal salt, and water is (5-10):(13-25):(15-20).

[0007] In some embodiments of the present invention, the soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate.

[0008] In some embodiments of the present invention, when preparing solution B, the mass ratio of n-butyl titanate, coupling agent and glacial acetic acid is 1:(0.05-0.5):(2-4).

[0009] In some embodiments of the present invention, the coupling agent is a silane coupling agent and / or a titanate coupling agent.

[0010] In some embodiments of the present invention, when preparing solution B, nitric acid is added to a pH of 0-2.5 to obtain solution B.

[0011] In some embodiments of the present invention, when preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

[0012] In some embodiments of the present invention, when the solution A is slowly added to the solution B, the adding rate of the solution A is 500 g / min.

[0013] On the other hand, the present invention further provides a water-based denitration catalyst, which is prepared according to any of the preparation methods described above.

[0014] In some embodiments of the present invention, when the reaction temperature of the water-based denitrification catalyst participating in denitrification is 180°C-400°C, the denitrification efficiency is 73%-98%; when the reaction temperature is 210°C-370°C, the denitrification efficiency reaches 95%-98%.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) When preparing the denitration catalyst in the preparation method of the present invention, water is used as a solvent to obtain a water-based denitration catalyst. No alcohol is used in the entire preparation process. Compared with the prior art using ethanol as the main solvent, the problems of high safety and environmental pressure, strict requirements on experimental equipment, high cost, etc. caused by ethanol solvents are avoided. The water-based catalyst prepared by the present invention is safer and more environmentally friendly, with a simple preparation process, simple equipment, short preparation cycle, and low cost.

[0017] (2) When preparing solution B in the preparation method of the present invention, a coupling agent is first added to n-butyl titanate. The coupling agent can modify the surface of the substance in the solution so that the hydrophilic component and the hydrophobic component are combined together. Then, an appropriate amount of glacial acetic acid is added, which not only dissolves n-butyl titanate but also plays a catalytic role. + The attack of NH4+ accelerates the hydrolysis and replaces the alkoxy group in tetrabutyl titanate in a coordinated form, directly bonding with titanium to form a hydrolysis complex Ti(OH) x (OAc) y , (wherein x+y=4), this type of complex is difficult to be destroyed during the hydrolysis and polycondensation process, thereby inhibiting the direct hydrolysis of n-butyl titanate to form Ti(OH)4 precipitation reaction. When solution A and solution B are mixed, no precipitate will be precipitated even if water is introduced; the addition of nitric acid plays a role in adjusting the acidity, providing a strong acid environment, and controlling the acidity of solution B at 0-2.5. The denitration catalyst finally prepared is more stable, has a better storage state, and can be stored for a long time.

[0018] (3) The preparation method of the present invention selects soluble cerium salts when preparing the denitration catalyst, and does not use vanadium components. It is a rare earth denitration catalyst, has the characteristics of being non-toxic, overcomes the disadvantage of vanadium-based catalysts being toxic, avoids the generation of hazardous wastes, and has no secondary pollution.

[0019] (4) The preparation method of the present invention limits the mass ratio of the soluble cerium salt, the soluble transition metal salt, and water in the preparation process of solution A to (5-10):(13-25):(15-20), and limits the mass ratio of n-butyl titanate, the coupling agent, and glacial acetic acid in the preparation process of solution B to 1:(0.05-0.5):(2-4). Under the premise of the modification effect of the coupling agent, the inhibition effect of glacial acetic acid on the formation of Ti(OH)4 precipitation, and the effect of nitric acid on the acidity adjustment, the limitation of the amount of each component allows the substances in the entire preparation system to react completely, the effects of each substance are optimized, and the prepared denitration catalyst is more uniform and does not show component segregation.

[0020] (5) The water-based denitration catalyst prepared by the present invention is a water-based clear solution. The catalyst is uniform, has no component segregation, is low in cost, is environmentally friendly and safe, and can be applied to various coating processes such as vacuum impregnation and spin coating. It is easy to coat on the surface of porous ceramic pores, and the coating is more uniform. It is not easy to clog the pores, and can avoid the occurrence of problems such as increased filtration resistance of integrated dust removal and denitration materials. In addition, the water-based denitration catalyst prepared by the present invention has a denitration efficiency of 73%-98% when the reaction temperature is 180℃-400℃; when the reaction temperature is 210℃-370℃, the denitration efficiency is as high as 95%-98%. According to the actual working conditions, the amount of each component can be adjusted within the range of the amount of each component specified in the preparation process of the present invention to achieve a denitration efficiency of up to 95%-98% under different working conditions (such as working temperature). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be described below.

[0022] Figure 1 This is a SEM image of the surface of the product after coating with a water-based denitration catalyst prepared by a preparation method according to an embodiment of the present invention;

[0023] Figure 2 This is a SEM image of the surface of the product after coating with a water-based denitration catalyst prepared by a preparation method according to another embodiment of the present invention;

[0024] Figure 3 This is a SEM image of the surface of the product after coating with a water-based denitration catalyst prepared by a preparation method according to another embodiment of the present invention;

[0025] Figure 4 This is a graph showing the denitration efficiency of a water-based denitration catalyst prepared by the preparation method of Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, various aspects of the present invention will be described in detail below in conjunction with specific embodiments. However, these specific embodiments are only used to illustrate the present invention and do not constitute any limitation on the scope of protection and essential content of the present invention.

[0027] The invention provides a method for preparing a water-based denitration catalyst, comprising the following steps: dissolving a soluble cerium salt and a soluble transition metal salt in water to obtain a solution A; adding a coupling agent to n-butyl titanate while stirring, then adding glacial acetic acid, mixing evenly, and then adding nitric acid to obtain a solution B; slowly adding the solution A to the solution B, mixing evenly, and obtaining a water-based denitration catalyst.

[0028] In the present invention, when preparing solution A, the mass ratio of soluble cerium salt, soluble transition metal salt and water is (5-10):(13-25):(15-20). The soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate.

[0029] In the present invention, when preparing solution B, the mass ratio of n-butyl titanate, coupling agent and glacial acetic acid is 1:(0.05-0.5):(2-4). The coupling agent is a silane coupling agent and / or a titanate coupling agent. When preparing solution B, nitric acid is added to pH=0-2.5 to obtain solution B. When preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

[0030] In the present invention, when solution A is slowly added to solution B, the addition rate of solution A is 500 g / min. Slowly adding solution A to solution B at an addition rate of 500 g / min can avoid particle precipitation caused by too fast an addition rate. The addition rate of 500 g / min provides sufficient time for the dissolution and reaction of each component in solution A and each component in solution B, so that the prepared denitration catalyst has better dispersibility.

[0031] The present invention also provides a water-based denitration catalyst, which is prepared according to the preparation method of the present invention. When the reaction temperature of the water-based denitration catalyst participating in denitration is 180°C-400°C, the denitration efficiency is 73%-98%; when the reaction temperature is 210°C-370°C, the denitration efficiency reaches 95%-98%.

[0032] Embodiment 1:

[0033] The present embodiment provides a method for preparing a water-based denitration catalyst, comprising the following steps: pouring water into a container A, pouring a soluble cerium salt and a soluble transition metal salt into the container A while stirring, dissolving the soluble cerium salt and the soluble transition metal salt in water, and stirring to obtain a clear solution to obtain a solution A; pouring n-butyl titanate into a water-free container B, adding a coupling agent into the container B while stirring, and then adding glacial acetic acid, mixing evenly, and then adding nitric acid to adjust the pH to pH=0-2.5 to obtain a solution B; slowly adding the solution A in the container A to the solution B in the container B at a rate of 500 g / min, stirring for 3-5 hours after all the solution A is added to the solution B, and mixing evenly to obtain a water-based denitration catalyst.

[0034] In this embodiment, when preparing solution A, the mass ratio of soluble cerium salt, soluble transition metal salt and water is 10:13:20. The soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate. Preferably, the soluble transition metal salt is copper nitrate and iron nitrate, and the mass ratio of copper nitrate to iron nitrate is 3:10.

[0035] In this embodiment, when preparing solution B, the mass ratio of n-butyl titanate, coupling agent, and glacial acetic acid is 1:0.1:(2-4). The coupling agent is a silane coupling agent. When preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

[0036] This embodiment also provides a water-based denitration catalyst, which is prepared according to the preparation method of the water-based denitration catalyst of this embodiment. After the water-based denitration catalyst prepared in this embodiment is coated (e.g., coated on the surface or inside of the porous ceramic channel), it is dried and calcined to obtain an integrated dust removal and denitration product. In order to detect the state of the water-based denitration catalyst prepared in this embodiment after coating, the surface of the product is characterized by morphology, such as Figure 1 As shown in the figure, a SEM image of the surface of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that the water-based denitration catalyst prepared by the preparation method of this embodiment is evenly coated and is not easy to block the pores. In addition, in order to detect the denitration effect of the water-based denitration catalyst prepared by this embodiment, the product was tested for its denitration efficiency under the conditions of flue gas nitrogen oxygen concentration of 600ppm (NOx 600ppm) and flue gas flow rate of 1m / min. Figure 4 As shown, a denitration efficiency curve of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that when the reaction temperature of the water-based denitration catalyst prepared in this embodiment participates in denitration at 240°C-400°C, the denitration efficiency is 73%-98%, especially when the reaction temperature is 300°C-370°C, the denitration efficiency is as high as 95%-98%.

[0037] Embodiment 2:

[0038] The present embodiment provides a method for preparing a water-based denitration catalyst, comprising the following steps: pouring water into a container A, pouring a soluble cerium salt and a soluble transition metal salt into the container A while stirring, dissolving the soluble cerium salt and the soluble transition metal salt in water, and stirring to obtain a clear solution to obtain a solution A; pouring n-butyl titanate into a water-free container B, adding a coupling agent into the container B while stirring, and then adding glacial acetic acid, mixing evenly, and then adding nitric acid to adjust the pH to pH=0-2.5 to obtain a solution B; slowly adding the solution A in the container A to the solution B in the container B at a rate of 500 g / min, stirring for 3-5 hours after all the solution A is added to the solution B, and mixing evenly to obtain a water-based denitration catalyst.

[0039] In this embodiment, when preparing solution A, the mass ratio of soluble cerium salt, soluble transition metal salt and water is 5:25:15. The soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate. Preferably, the soluble transition metal salt is copper nitrate, iron nitrate and manganese nitrate, and the mass ratio of copper nitrate, iron nitrate and manganese nitrate is 5:10:10.

[0040] In this embodiment, when preparing solution B, the mass ratio of n-butyl titanate, coupling agent, and glacial acetic acid is 1:0.05:(2-4). The coupling agent is a titanate coupling agent. When preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

[0041] This embodiment also provides a water-based denitration catalyst, which is prepared according to the preparation method of the water-based denitration catalyst of this embodiment. After the water-based denitration catalyst prepared in this embodiment is coated (e.g., coated on the surface or inside of the porous ceramic channel), it is dried and calcined to obtain an integrated dust removal and denitration product. In order to detect the state of the water-based denitration catalyst prepared in this embodiment after coating, the surface of the product is characterized by morphology, such as Figure 2 As shown in the figure, a SEM image of the surface of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that the water-based denitration catalyst prepared by the preparation method of this embodiment is evenly coated and is not easy to block the pores. In addition, in order to detect the denitration effect of the water-based denitration catalyst prepared by this embodiment, the product was tested for its denitration efficiency under the conditions of flue gas nitrogen oxygen concentration of 600ppm (NOx 600ppm) and flue gas flow rate of 1m / min. Figure 4As shown, a denitration efficiency curve of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that when the reaction temperature of the water-based denitration catalyst prepared in this embodiment participating in denitration is 210°C-320°C, the denitration efficiency is 73%-98%, especially when the reaction temperature is 250°C-290°C, the denitration efficiency is as high as 95%-98%.

[0042] Embodiment 3:

[0043] The present embodiment provides a method for preparing a water-based denitration catalyst, comprising the following steps: pouring water into a container A, pouring a soluble cerium salt and a soluble transition metal salt into the container A while stirring, dissolving the soluble cerium salt and the soluble transition metal salt in water, and stirring to obtain a clear solution to obtain a solution A; pouring n-butyl titanate into a water-free container B, adding a coupling agent into the container B while stirring, and then adding glacial acetic acid, mixing evenly, and then adding nitric acid to adjust the pH to pH=0-2.5 to obtain a solution B; slowly adding the solution A in the container A to the solution B in the container B at a rate of 500 g / min, stirring for 3-5 hours after all the solution A is added to the solution B, and mixing evenly to obtain a water-based denitration catalyst.

[0044] In this embodiment, when preparing solution A, the mass ratio of soluble cerium salt, soluble transition metal salt and water is 8:15:18. The soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate. Preferably, the soluble transition metal salt is copper nitrate.

[0045] In this embodiment, when preparing solution B, the mass ratio of n-butyl titanate, coupling agent, and glacial acetic acid is 1:0.5:(2-4). The coupling agent is a silane coupling agent and a titanate coupling agent. When preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

[0046] This embodiment also provides a water-based denitration catalyst, which is prepared according to the preparation method of the water-based denitration catalyst of this embodiment. After the water-based denitration catalyst prepared in this embodiment is coated (e.g., coated on the surface or inside of the porous ceramic channel), it is dried and calcined to obtain an integrated dust removal and denitration product. In order to detect the state of the water-based denitration catalyst prepared in this embodiment after coating, the surface of the product is characterized by morphology, such as Figure 3As shown in the figure, a SEM image of the surface of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that the water-based denitration catalyst prepared by the preparation method of this embodiment is evenly coated and is not easy to block the pores. In addition, in order to detect the denitration effect of the water-based denitration catalyst prepared by this embodiment, the product was tested for its denitration efficiency under the conditions of flue gas nitrogen oxygen concentration of 600ppm (NOx 600ppm) and flue gas flow rate of 1m / min. Figure 4 As shown, a denitration efficiency curve of the water-based denitration catalyst prepared by the preparation method of this embodiment is shown. It can be seen from the figure that when the reaction temperature of the water-based denitration catalyst prepared in this embodiment participates in denitration at 180°C-250°C, the denitration efficiency is 76%-95%, especially when the reaction temperature is 210°C-220°C, the denitration efficiency is as high as 95%.

[0047] Comprehensive Examples 1-3, such as Figure 4 As shown, a denitration efficiency curve of a water-based denitration catalyst prepared by the preparation method of Examples 1-3 is shown. The preparation method of the present invention defines the mass ratio of soluble cerium salt, soluble transition metal salt, and water as (5-10): (13-25): (15-20), and the mass ratio of n-butyl titanate, coupling agent, and glacial acetic acid as 1: (0.05-0.5): (2-4). Although Examples 1-3 only take a specific mass ratio in the range of each component, the denitration efficiency of the water-based denitration catalyst prepared therefrom can reach 95%-98% at different reaction temperatures. Therefore, according to actual working conditions, the amount of each component can be adjusted within the range of each component amount defined in the preparation process of the present invention to achieve a denitration efficiency of up to 95%-98% under different working conditions (such as working temperature), especially easy to achieve a denitration efficiency of up to 95%-98% at a reaction temperature of 210°C-370°C.

[0048] The present invention has been described above in conjunction with specific embodiments. These specific embodiments are merely exemplary and cannot be used to limit the scope of protection of the present invention. Those skilled in the art may make various modifications, changes or substitutions without departing from the essence of the present invention. Therefore, various equivalent changes made according to the present invention still fall within the scope covered by the present invention.

Claims

1. A method for preparing a water-based denitration catalyst, characterized in that: The following steps are involved: Dissolving a soluble cerium salt and a soluble transition metal salt in water to obtain a solution A; the mass ratio of the soluble cerium salt, the soluble transition metal salt and water is (5-10):(13-25):(15-20); Add a coupling agent to n-butyl titanate while stirring, then add glacial acetic acid, mix well and add nitric acid to obtain solution B; when preparing solution B, the mass ratio of n-butyl titanate, coupling agent and glacial acetic acid is 1:(0.05-0.5):(2-4); the coupling agent is a silane coupling agent and / or a titanate coupling agent; Slowly adding the solution A into the solution B and mixing them evenly to obtain the water-based denitration catalyst; The prepared water-based denitration catalyst is a water-based clear solution; When the solution A is slowly added to the solution B, the addition rate of the solution A is 500 g / min; When the reaction temperature of the water-based denitration catalyst participating in denitration is 180°C-400°C, the denitration efficiency is 73%-98%; when the reaction temperature is 210°C-370°C, the denitration efficiency reaches 95%-98%; when the reaction temperature is 210°C-220°C, the denitration efficiency is as high as 95%.

2. The preparation method according to claim 1, characterized in that The soluble cerium salt is cerium nitrate, and the soluble transition metal salt is at least one of copper nitrate, iron nitrate and manganese nitrate.

3. The preparation method according to claim 1, characterized in that: When preparing solution B, nitric acid is added to pH = 0-2.5 to obtain the solution B.

4. The preparation method according to claim 3, characterized in that: When preparing solution B, the amount of nitric acid added is 0.01-0.02 times the mass of n-butyl titanate.

5. A water-based denitration catalyst, characterized in that: The water-based denitration catalyst is prepared according to the preparation method according to any one of claims 1 to 4.

6. The water-based denitration catalyst according to claim 5, characterized in that: When the reaction temperature of the water-based denitration catalyst participating in denitration is 180°C-400°C, the denitration efficiency is 73%-98%; when the reaction temperature is 210°C-370°C, the denitration efficiency reaches 95%-98%.

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