A honeycomb catalyst for simultaneously removing NOx and CO components of sintering flue gas and a preparation method thereof

Abstract

The application relates to a honeycomb catalyst for simultaneously removing NOx and CO components of sintering flue gas and a preparation method thereof, and belongs to the technical field of flue gas treatment. In the application, a catalyst carrier MnSO4 nanotube-TiO2 is prepared by a hydrolysis method, active components Ag and V2O5 are loaded on the catalyst carrier as active components, MoO3 and CuSO4 are loaded as active aids, and the honeycomb catalyst is prepared through an extrusion molding process and after drying and calcination. x The catalyst prepared in the application can simultaneously and efficiently remove NOx and CO under the condition of flue gas at 100 DEG C to 200 DEG C, the removal rates can all reach more than 90%, the catalyst has good sulfur resistance, water resistance and catalytic activity, and can be applied to the treatment of sintering flue gas in the steel industry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental protection catalysts, and particularly relates to a honeycomb catalyst for simultaneously removing NOx and CO components in sintering flue gas and a preparation method thereof. BACKGROUND

[0002] The sintering flue gas in the steel industry contains about 300 mg / Nm 3 of NOx components and 5000 mg / Nm 3 of CO components. The mainstream of current industrial flue gas denitrification is SCR denitrification technology, the principle of which is that, under the action of a catalyst, the NOx components in the flue gas react with the injected reducing agent NH3 to generate harmless N2 and H2O. At present, there are SCR denitrification catalysts for sintering flue gas on the market, but they can only effectively remove NOx components and have limited effect on other pollutants. Therefore, if a catalyst that can simultaneously and effectively remove NOx and CO components is developed on the basis of SCR denitrification technology, enterprises can use the new catalyst on the existing denitrification equipment to simultaneously achieve the purpose of controlling NOx and CO emissions without adding special CO removal equipment, which will save a lot of cost investment for enterprises.

[0003] At present, research on catalysts for simultaneously removing NOx and CO components in sintering flue gas is not common in China. Chinese patent 201911101249.0 discloses a carbon-based catalyst for simultaneously removing NOx and CO in sintering flue gas as well as a preparation method and application thereof. The catalyst uses FeOx and KOx oxides as active components and bituminous coal as a carrier, and has high catalytic oxidation efficiency for NOx and CO at 200-300°C. However, the temperature of sintering flue gas is usually in the range of 120-180°C, and the activity of the catalyst will certainly decrease at this temperature. In addition, a large amount of SO2 components also exist in sintering flue gas, which will react with the active components in the catalyst, causing the catalyst to be deactivated due to sulfur poisoning. At present, there is no catalyst that has high activity, sulfur resistance, water resistance, and can be used for simultaneously removing NOx and CO in sintering flue gas. SUMMARY

[0004] The present application is to solve the problem that the existing catalysts for sintering flue gas in the steel industry cannot simultaneously and efficiently remove NOx and CO, resulting in poor flue gas treatment effect, and provides a honeycomb catalyst for simultaneously removing NOx and CO components in sintering flue gas and a preparation method thereof.

[0005] The application adopts the following technical scheme: a honeycomb catalyst for simultaneously removing NOx and CO components of sintering flue gas, wherein MnSO4 nanotube-TiO2 is used as a catalyst carrier, the carrier accounts for 84.9%-91.9% of the total mass of the catalyst, Ag and V2O5 are used as catalyst active components, the content of Ag is 0.1% of the total mass of the catalyst, the content of V2O5 is 1%-2% of the total mass of the catalyst, MoO3 and CuSO4 are used as catalyst active assistants, the content of MoO3 is 4%-7% of the total mass of the catalyst, and the content of CuSO4 is 3%-6% of the total mass of the catalyst.

[0006] Further, the length of the MnSO4 nanotube is 1 nm-5 nm.

[0007] A preparation method of the honeycomb catalyst for simultaneously removing NOx and CO components of sintering flue gas, comprising the following steps:

[0008] S1. Preparation of the catalyst carrier MnSO4 nanotube-TiO2

[0009] Manganese chloride tetrahydrate and ammonium bisulfate are dissolved together according to a molar ratio of 1:1.1, and the solution is heated to 85-95 DEG C. After the temperature reaches, 1%-3% of the total mass of the solution is added to the hydrogen peroxide under stirring, and after stirring for 1 h, n-butyl titanate is slowly added, and the pH value of the solution is adjusted to 6.5-7.5 by using ammonia water. After continuing to stir for 30 min, the solution is left to stand for 24 h, and the precipitate is obtained by filtration. The precipitate is calcined at 400 DEG C for 4-6 h to obtain the nanoscale MnSO4 nanotube-TiO2 carrier.

[0010] S2. Preparation of catalyst mud

[0011] After the deionized water is heated to 80-85 DEG C, ammonium metavanadate is added, and monoethanolamine is slowly added dropwise until the ammonium metavanadate is completely dissolved. Then, silver nitrate, ammonium heptamolybdate, and copper sulfate pentahydrate are added and stirred until completely dissolved. The prepared mixed solution is added to the carrier prepared in S1, and a molding aid of 15-25% of the mass of the carrier is added after stirring uniformly. The molding aid is composed of, by mass percentage, 35% of kaolin, 30% of glass fiber, 15% of polypropylene fiber, 8% of hydroxypropyl methyl cellulose, 6% of polyethylene oxide, and 6% of stearic acid. After stirring for 2 h, the catalyst mud is obtained, and the mud is aged at room temperature for 24 h.

[0012] S3. Preparation of the catalyst

[0013] The mud obtained in S2 is filtered, and the honeycomb catalyst wet embryo is obtained by extrusion molding device extrusion. After the wet embryo is wrapped with a paper shell, it is slowly dried in multiple stages at a temperature in the range of 25 DEG C-60 DEG C. After drying, the catalyst embryo is calcined to obtain the honeycomb catalyst.

[0014] Further, the sintering procedure in S3 is 2 h to 150℃, 3 h at 150℃, 2.5 h to 320℃, 3 h at 320℃, 4 h to 450℃, and 6 h at 450℃.

[0015] The advantages of the present application are as follows:

[0016] (1) The catalyst provided by the present application has a removal rate of NOx and CO of more than 90% at 100℃ to 200℃. In the preparation of the carrier, manganese chloride tetrahydrate and ammonium bisulfate are used as raw materials, hydrogen peroxide is added to stabilize the valence state of Mn element, and n-butyl titanate is added to prepare a MnSO4-TiO2 mixed carrier with a specific surface area of 1 to 15 nm by a hydrolysis method. The MnSO4 is uniformly distributed in the form of 1 to 5 nm nanotubes on the TiO2. MnSO4 itself has the ability to catalytically oxidize CO, and also has the effects of adjusting the acidity and alkalinity of the carrier and improving the oxygen flow capacity of the catalyst surface. More importantly, the uniformly distributed Mn ions in the carrier can interact with the surface active sites, so that the active components of the catalyst can be uniformly distributed on the surface of the carrier, which plays an important role in improving the activity of the catalyst. In addition, the nanotube structure can enhance the flowability and adsorbability of NO x and CO on the surface of the catalyst, which also has a significant effect on improving the activity of the catalyst. In addition, the combination of vanadium pentoxide and molybdenum trioxide is a common active formula for denitration catalysts, which has high denitration activity. Vanadium pentoxide also has good effects on catalytic oxidation of CO, and a small amount of Ag can further improve the catalytic activity of the catalyst for NO x and CO. In addition, the active assistant CuSO4 not only has catalytic ability, but also can promote the formation of lattice defects in the catalyst and promote the fusion between the components of the catalyst, which also plays an important role in improving the activity of the catalyst.

[0017] (2) The catalyst uses MnSO4 nanotube-TiO2 as the carrier, and there is no water-resistant component. The nanotube-shaped MnSO4 also provides strong support for the structure of the catalyst, so that the catalyst has strong stability in actual water-containing flue gas and does not have the problem of structural collapse, and the service life is not affected by water vapor in the flue gas.

[0018] (3) It has good sulfur resistance. The sintering flue gas generally contains a high concentration of SO2 component, which is easy to react with some active components of the catalyst, causing the active sites of the catalyst to be sulfated and lose activity. The active components in the catalyst provided by the present application are not easy to react with SO2 under sintering flue gas conditions, and the active assistant CuSO4 and the MnSO4 component in the carrier can also hinder the adsorption of SO2 on the surface of the catalyst, so that the catalyst can be used stably in sulfur-containing flue gas.

[0019] (4) The SCR denitration reaction needs to pass in NH3 as a reducing agent, and when the catalyst provided by the application is used, the CO component in the flue gas can be used as a reducing agent to complete the denitration reaction. Therefore, after using the catalyst provided by the application, the amount of NH3 used can be reduced, and even when the CO concentration in the flue gas is higher than a certain degree, additional ammonia injection will no longer be needed, thereby greatly reducing the pollution control cost of enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A schematic diagram of the catalytic activity of the application examples 1-4 and the comparative examples at 100°C.

[0021] Figure 2 A schematic diagram of the catalytic activity of the application examples 1-4 and the comparative examples at 200°C. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be further described below. Example 1

[0023] Preparation of S1 catalyst carrier MnSO4 nanotube-TiO2

[0024] Dissolve 1.59 kg of manganese chloride tetrahydrate and 1.02 kg of ammonium bisulfate in 60 kg of water at the same time, heat the solution to 85°C, and add 0.63 kg of hydrogen peroxide under stirring. After stirring for 1 h, slowly add 63.75 kg of n-butyl titanate, and adjust the pH value of the solution to 6.5 with ammonia water. Continue stirring for 30 min, then let the solution stand for 24 h, filter the precipitate, and calcine the precipitate at 400°C for 4 h to obtain the MnSO4 nanotube-TiO2 carrier. The MnSO4 content in the carrier is 7.5%;

[0025] Preparation of S2 catalyst mud

[0026] Heat 9 kg of deionized water to 85°C, add 0.23 kg of ammonium metavanadate, and slowly add monoethanolamine until the ammonium metavanadate is completely dissolved. Then add 27.8 g of silver nitrate, 0.87 kg of ammonium heptamolybdate, 0.83 kg of copper sulfate pentahydrate, and stir until completely dissolved. Add the prepared mixed solution to the carrier prepared in step 1, stir uniformly, and then add 0.85 kg of kaolin, 0.73 kg of glass fiber, 0.37 kg of polypropylene fiber, 0.19 kg of hydroxypropyl methyl cellulose, 0.15 kg of polyethylene oxide, and 0.15 kg of stearic acid. Stir for 2 h to obtain the catalyst mud, and then let the mud stand at room temperature for 24 h.

[0027] S3 Preparation of the catalyst

[0028] The mud obtained in step 2 is filtered using a mud filtering device, and then a honeycomb catalyst wet body is obtained through an extrusion process. The wet body is wrapped with a paper shell, and then sequentially dried at 25°C for 72 h, at 30°C for 48 h, at 35°C for 48 h, at 40°C for 24 h, at 50°C for 12 h, and at 60°C for 12 h, and finally calcined to obtain a 18-hole honeycomb catalyst with an inner wall thickness of 0.8 mm, an outer wall thickness of 1.3 mm, and a cross-sectional size of 150 mm x 150 mm.

[0029] The honeycomb catalyst for simultaneously removing NO x The composition of the catalyst component prepared through the above steps comprises: 0.1% Ag, 1% V2O5, 4% MoO3, 3% CuSO4, and 91.9% MnSO4 nanotube-TiO2. Example 2

[0030] Preparation of the MnSO4 nanotube-TiO2 catalyst carrier S1

[0031] 60 kg of water is used to dissolve 3.47 kg of manganese chloride tetrahydrate and 2.22 kg of ammonium bisulfate at the same time, and the solution is heated to 95°C. 1.8 kg of hydrogen peroxide is added under stirring, and after stirring for 1 h, 63.75 kg of n-butyl titanate is slowly added. The pH value of the solution is adjusted to 7.5 with ammonia water, and the solution is continuously stirred for 30 min and then left to stand for 24 h. The precipitate is obtained by filtration, and the precipitate is calcined at 400°C for 6 h to obtain the MnSO4 nanotube-TiO2 carrier. The MnSO4 content in the carrier is 15%;

[0032] Preparation of the catalyst mud S2

[0033] 11.47 kg of deionized water is heated to 85°C, and 0.54 kg of ammonium metavanadate is added. Single ethanol amine is slowly added dropwise until the ammonium metavanadate is completely dissolved. Then 32.7 g of silver nitrate, 1.78 kg of ammonium heptamolybdate, and 1.95 kg of copper sulfate pentahydrate are added and stirred until completely dissolved. The prepared mixed solution is added to the carrier prepared in step 1, and after stirring uniformly, 1.54 kg of kaolin, 1.32 kg of glass fiber, 0.66 kg of polypropylene fiber, 0.35 kg of hydroxypropyl methyl cellulose, 0.27 kg of polyethylene oxide, and 0.27 kg of stearic acid are added. After stirring for 2 h, the catalyst mud is obtained, and the mud is aged at room temperature for 24 h.

[0034] Preparation of the catalyst S3

[0035] The mud obtained in step 2 is filtered using a mud filtering device, and then a honeycomb catalyst wet body is obtained through an extrusion process. The wet body is wrapped with a paper shell, and then sequentially dried at 25°C for 48 h, at 30°C for 48 h, at 35°C for 48 h, at 40°C for 48 h, at 50°C for 12 h, and at 60°C for 12 h, and finally calcined to obtain a 16-hole honeycomb catalyst with an inner wall thickness of 1.0 mm, an outer wall thickness of 1.5 mm, and a cross-sectional size of 150 mm x 150 mm.

[0036] The honeycomb catalyst for simultaneously removing NO x The composition of the catalyst component prepared through the above steps comprises 0.1% Ag, 2% V2O5, 7% MoO3, 6% CuSO4, and 84.9% MnSO4 nanotube-TiO2. Example 3

[0037] Preparation of the MnSO4 nanotube-TiO2 catalyst carrier S1

[0038] 1.89 kg of manganese chloride tetrahydrate and 1.21 kg of ammonium bisulfate are simultaneously dissolved in 55 kg of water, the solution is heated to 90°C, 1.2 kg of hydrogen peroxide is added under stirring, and after stirring for 1 h, 55.25 kg of n-butyl titanate is slowly added. The pH value of the solution is adjusted to 7.0 with ammonia water, and the solution is continuously stirred for 30 min and then left to stand for 24 h. The precipitate is obtained by filtration, and the precipitate is calcined at 400°C for 5 h to obtain the MnSO4 nanotube-TiO2 carrier, and the MnSO4 content in the carrier is 10%;

[0039] Preparation of the catalyst mud S2

[0040] 8.7 kg of deionized water is heated to 85°C, 0.32 kg of ammonium metavanadate is added, and monoethanolamine is slowly added dropwise until the ammonium metavanadate is completely dissolved. Then, 25.7 g of silver nitrate, 1.0 kg of ammonium heptamolybdate, and 1.28 kg of copper sulfate pentahydrate are added and stirred until completely dissolved. The prepared mixed solution is added to the carrier prepared in step 1, and after stirring uniformly, 1.01 kg of kaolin, 0.87 kg of glass fiber, 0.43 kg of polypropylene fiber, 0.23 kg of hydroxypropyl methyl cellulose, 0.17 kg of polyethylene oxide, and 0.17 kg of stearic acid are added. After stirring for 2 h, the catalyst mud is obtained, and the mud is aged at room temperature for 24 h.

[0041] Preparation of the catalyst S3

[0042] The mud obtained in step 2 is filtered using a mud filtering device, and then a honeycomb catalyst wet body is obtained through an extrusion process. The wet body is wrapped with a paper shell, and then sequentially dried at 25°C for 72 h, at 30°C for 48 h, at 35°C for 48 h, at 40°C for 48 h, at 50°C for 12 h, and at 60°C for 8 h, and finally calcined to obtain a 20-cell honeycomb catalyst with an inner wall thickness of 0.9 mm, an outer wall thickness of 1.4 mm, and a cross-sectional size of 150 mm x 150 mm.

[0043] The honeycomb catalyst for simultaneously removing NO x The composition of the catalyst component prepared through the above steps comprises: 0.1% Ag, 1.5% V2O5, 5% MoO3, 5% CuSO4, and 88.4% MnSO4 nanotube-TiO2. Example 4

[0044] Preparation of the MnSO4 nanotube-TiO2 catalyst carrier S1

[0045] Dissolve 2.86 kg of manganese chloride tetrahydrate and 1.82 kg of ammonium bisulfate in 70 kg of water at the same time, heat the solution to 95°C, and then add 1.6 kg of hydrogen peroxide under stirring. After stirring for 1 h, slowly add 68 kg of n-butyl titanate. Adjust the pH value of the solution to 7.0 with ammonia water, continue stirring for 30 min, and then let the solution stand for 24 h. Filter the precipitate, and then calcine the precipitate at 400°C for 5 h to obtain the MnSO4 nanotube-TiO2 carrier. The MnSO4 content in the carrier is 12%;

[0046] Preparation of the catalyst mud S2

[0047] Heat 10.9 kg of deionized water to 85°C, and then add 0.48 kg of ammonium metavanadate. Slowly add monoethanolamine dropwise until the ammonium metavanadate is completely dissolved. Then add 32.5 g of silver nitrate, 1.52 kg of ammonium heptamolybdate, and 1.29 kg of copper sulfate pentahydrate, and stir until completely dissolved. Add the prepared mixed solution to the carrier prepared in step 1, and then stir uniformly. Add 1.15 kg of kaolin, 0.98 kg of glass fiber, 0.49 kg of polypropylene fiber, 0.26 kg of hydroxypropyl methyl cellulose, 0.20 kg of polyethylene oxide, and 0.20 kg of stearic acid, and then stir for 2 h to obtain the catalyst mud. Let the mud stand at room temperature for 24 h.

[0048] Preparation of the catalyst S3

[0049] The mud obtained in step 2 is filtered by using a mud filtering device, and then a honeycomb catalyst wet blank is obtained by an extrusion process. The wet blank is wrapped with a paper shell, and then sequentially dried at 25℃ for 72 h, at 30℃ for 48 h, at 35℃ for 36 h, at 40℃ for 36 h, at 50℃ for 12 h and at 60℃ for 12 h, and finally calcined to obtain a 18-hole honeycomb catalyst with an inner wall thickness of 0.85 mm, an outer wall thickness of 1.35 mm and a cross-sectional size of 150 mm x 150 mm.

[0050] The honeycomb catalyst prepared by the above steps can simultaneously remove NO x and CO. The composition of the catalyst component prepared by the above steps comprises 0.1% Ag, 1.8% V2O5, 6% MoO3, 4% CuSO4 and 88.1% MnSO4 nanotube-TiO2.

[0051] Comparative example

[0052] The honeycomb SCR denitration catalyst and the CO removal catalyst are purchased.

[0053] The compressive strength and catalytic activity of the catalysts in Examples 1-4 and the comparative example are detected, and the catalytic activity detection conditions are as follows: the concentration of NOx is 350 mg / m 3 , the concentration of CO is 2000 mg / m 3 , the concentration of SO2 is 1200 mg / m 3 , the concentration of O2 is 5%, the concentration of H2O is 8%, the space velocity is 10000 h -1 , and the temperature is 100℃ and 200℃.

[0054] The compressive strength detection results of the catalysts are shown in Table 1.

[0055] Table 1 Compressive strength results

[0056]

[0057] As shown in Table 1, the compressive strength of the honeycomb catalysts prepared in Examples 1-4 is better than that of the commercial catalyst in the comparative example, that is, the compressive strength of the honeycomb catalyst prepared by the process provided by the present application is better than that of the commercial catalyst of the same type, which meets the requirements of industrial use.

[0058] As shown in Table 1, the compressive strength of the honeycomb catalysts prepared in Examples 1-4 is better than that of the commercial catalyst in the comparative example, that is, the compressive strength of the honeycomb catalyst prepared by the process provided by the present application is better than that of the commercial catalyst of the same type, which meets the requirements of industrial use. Figure 1 and Figure 2 It can be seen that the commercial SCR denitration catalyst and the CO removal catalyst only have single activity and cannot simultaneously and efficiently remove NO x and CO, while the catalysts in Examples 1-4 can simultaneously and efficiently remove NO x and CO, and the removal rates are all above 90%, which is obviously better than that of the catalysts in the comparative example, that is, the present application provides a catalyst for simultaneously removing NO xAnd CO catalyst can be used for steel industry sintering flue gas.

Claims

1. A honeycomb catalyst for simultaneously removing NOx and CO components from sintering flue gas, characterized in that: The catalyst uses MnSO4 nanotubes-TiO2 as a support, which accounts for 84.9% to 91.9% of the total mass of the catalyst. Ag and V2O5 are the active components of the catalyst, with Ag accounting for 0.1% of the total mass of the catalyst and V2O5 accounting for 1% to 2% of the total mass of the catalyst. MoO3 and CuSO4 are catalyst active promoters, with MoO3 accounting for 4% to 7% of the total mass of the catalyst and CuSO4 accounting for 3% to 6% of the total mass of the catalyst.

2. The honeycomb catalyst for simultaneously removing NOx and CO components from sintering flue gas as described in claim 1, characterized in that: The length of MnSO4 nanotubes ranges from 1 nm to 5 nm.

3. The method for preparing the honeycomb catalyst for simultaneously removing NOx and CO components from sintering flue gas as described in claim 1, characterized in that: Includes the following steps: Preparation of S1 catalyst support MnSO4 nanotubes-TiO2 Manganese chloride tetrahydrate and ammonium bisulfate were dissolved together at a molar ratio of 1:1.1 and the solution was heated to 85℃-95℃. After the temperature was reached, 1%-3% of hydrogen peroxide was added to the total mass of the solution under stirring. After stirring for 1 h, tetrabutyl titanate was slowly added. The pH of the solution was adjusted to 6.5-7.5 with ammonia. After stirring for 30 min, the solution was allowed to stand for 24 h. The precipitate was obtained by filtration. The precipitate was calcined at 400-450℃ for 4 h-6 h to obtain nano-sized MnSO4 nanotubes-TiO2 support. Preparation of S2 catalyst sludge After heating deionized water to 80-85℃, ammonium metavanadate was added. Monoethanolamine was slowly added dropwise until the ammonium metavanadate was completely dissolved. Then, silver nitrate, ammonium heptamolybdate, and copper sulfate pentahydrate were added and stirred until completely dissolved. The prepared mixed solution was added to the carrier prepared in S1 and stirred evenly. Then, 15-25% of the carrier mass of molding aid was added. The molding aid consisted of 35% kaolin, 30% glass fiber, 15% polypropylene fiber, 8% hydroxypropyl methylcellulose, 6% polyethylene oxide, and 6% stearic acid by mass percentage. After stirring for 2 hours, the catalyst sludge was obtained. The sludge was aged at room temperature for 24 hours. Preparation of S3 catalyst The sludge obtained from S2 is filtrated and extruded to obtain a honeycomb catalyst wet preform. The wet preform is wrapped in paper and then slowly dried in multiple stages within a temperature range of 25℃ to 60℃. After drying, the catalyst preform is calcined to obtain the honeycomb catalyst.

4. The method for preparing the honeycomb catalyst for simultaneously removing NOx and CO components from sintering flue gas as described in claim 3, characterized in that: The roasting process in S3 is as follows: 2 hours to 150°C, 3 hours to 150°C, 2.5 hours to 320°C, 3 hours to 320°C, 4 hours to 450°C, 6 hours to 450°C.

Images