Preparation method of medium-temperature corrugated plate SCR (Selective Catalytic Reduction) denitration catalyst

Abstract

The invention relates to the technical field of catalysts, in particular to a medium-temperature corrugated plate SCR denitration catalyst for a power plant and a preparation method thereof.The preparation method comprises the following steps that titanium dioxide, auxiliaries and deionized water are evenly mixed in proportion, and a vanadium source, a tungsten source and a binder are added to prepare active slurry; coating a corrugated fiber carrier with the active slurry, and drying to obtain a catalyst semi-finished product; and roasting the catalyst semi-finished product to obtain the medium-temperature corrugated plate SCR denitration catalyst. According to the catalyst prepared by the invention, the active components are uniformly dispersed by adding the auxiliaries; after calcination, a large number of pores can be formed in the surface of the corrugated plate catalyst, the gas reaction area is increased, gas adsorption and diffusion are facilitated, and high denitration activity can still be kept at a high space velocity; the coating of the catalyst is thin, the loading capacity is low, the coating cost of the catalyst is saved, and the aperture ratio of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst technology, and in particular to a method for preparing a medium-temperature corrugated plate SCR denitrification catalyst. Background Technology

[0002] With the ultra-low emission retrofitting of coal-fired power units, flue gas denitrification catalysts are widely used for the conversion and removal of nitrogen oxides in flue gas. Commonly used flue gas denitrification catalysts include flat plate, honeycomb, and corrugated plate types. Among them, corrugated plate denitrification catalysts are made by cross-laden corrugated glass fiber as the substrate, followed by impregnation and calcination. Existing conventional corrugated plate denitrification catalysts have defects such as low porosity, large pressure drop, easy pore clogging, and low axial strength, resulting in less than ideal denitrification performance, especially at conditions above 300℃, making it difficult to meet production requirements. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a medium-temperature corrugated plate SCR denitrification catalyst. The advantages of this method are that it achieves uniform dispersion of the active components by adding key additives, and after calcination, it forms a large number of pores on the surface of the corrugated plate catalyst, increasing the reaction contact sites and facilitating gas adsorption and diffusion. Furthermore, it is less prone to slurry buildup during coating preparation, ensuring that the final catalyst does not clog the catalyst channels, thus achieving high porosity and low pressure drop.

[0004] The present invention specifically adopts the following technical solution:

[0005] A method for preparing a medium-temperature corrugated plate SCR denitration catalyst includes the following steps:

[0006] S1: Mix titanium dioxide, additives and deionized water in a certain proportion, and add vanadium source, tungsten source and binder to prepare an active slurry;

[0007] S2: The active slurry is coated onto a corrugated fiber carrier and dried to obtain a catalyst semi-finished product.

[0008] S3: The catalyst semi-finished product is roasted to obtain the medium-temperature corrugated plate SCR denitrification catalyst.

[0009] The present invention is further configured such that, in step S1, the mass ratio of titanium dioxide, additives and deionized water is (60-75):(1-7):110.

[0010] The present invention is further configured such that the mass ratio of vanadium source, tungsten source, binder and titanium dioxide in step S1 is (2-10):(1-6):(20-100):(60-75).

[0011] The present invention is further configured such that the auxiliary agent is a mixture of auxiliary agent A and auxiliary agent B, wherein the mass ratio of auxiliary agent A to auxiliary agent B is (1-6):(0.1-0.5).

[0012] The present invention is further configured such that: Auxiliary agent A is one or more of alkylbenzene sulfonate, fatty alcohol sulfate, polyvinyl alcohol, polypolyol, polyacrylamide, alkylolamide and imidazoline; and Auxiliary agent B is one or more of ammonia, ethanolamine, resin, ethylene glycol, glycerol, butanol, isobutanol, alkyne, ether, organosilicon, mineral oil, phosphate ester, polyether, polycarboxylate and polyacrylic acid.

[0013] The present invention is further configured such that the vanadium source is one or more of a soluble salt of vanadium, a soluble metal acid, a dispersible oxide, or nanoparticles.

[0014] The present invention is further configured such that the tungsten source is one or more of a soluble salt of tungsten, a soluble metal acid, a dispersible oxide, or nanoparticles.

[0015] The present invention is further configured such that the binder is one or more of silica sol, aluminum sol, silica-alumina sol, titanium sol or zirconium sol.

[0016] The present invention is further configured such that the corrugated fiber carrier is a corrugated glass fiber carrier or a corrugated ceramic fiber carrier.

[0017] The present invention is further configured such that, in step S2, the coating method is one of dip coating, spray coating, vacuum coating, dip coating or pressure coating, and the drying method is one of vacuum drying, hot air drying, natural air drying or microwave drying; in step S3, the calcination temperature is 450-550 ℃, and the calcination time is 2-6 h.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. By adding additives, the active components can be uniformly dispersed. After calcination, a large number of pores can be formed on the surface of the corrugated plate catalyst, which increases the reaction contact sites and is beneficial to the adsorption and diffusion of gases.

[0020] 2. The coating slurry has low viscosity, making it less prone to sticking during coating and preventing clogging of the catalyst pores, thus achieving a high porosity and low pressure drop in the denitrification catalyst.

[0021] 3. The prepared catalyst has high structural strength, high powder adhesion rate, and is resistant to thermal shock, exhibiting excellent denitrification activity at high space velocities. Attached Figure Description

[0022] Figure 1 The graph shows the denitrification conversion results of the denitrification catalysts prepared in Examples 1-4 and Comparative Examples 1-2. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The corrugated plate SCR denitration catalyst of this invention is prepared by the following method: titanium dioxide, additives and deionized water are mixed evenly in a certain proportion (the mass ratio of titanium dioxide, additives and deionized water is (60-75):(1-7):110), vanadium source, tungsten source and binder are added to prepare an active slurry, the mass ratio of vanadium source, tungsten source, binder and titanium dioxide is (2-10):(1-6):(20-100):(60-75); the active slurry is coated on a corrugated fiber carrier (corrugated glass fiber carrier or corrugated ceramic fiber carrier) by one of the following methods: impregnation coating, spray coating, vacuum coating, dip coating or pressure coating; the catalyst semi-finished product is dried by one of the following methods: vacuum drying, hot air drying, natural air drying or microwave drying; the catalyst semi-finished product is calcined at 450-550 °C for 2-6 h to obtain the final product.

[0025] The additive is a mixture of additive A and additive B, with a mass ratio of (1-6):(0.1-0.5). Additive A is at least one of alkylbenzene sulfonates (such as sodium dodecylbenzene sulfonate), fatty alcohol sulfates, polyvinyl alcohol, polypolyols (such as polyethylene glycol), polyacrylamide, alkylolamides, and imidazoline, or a combination of at least one of alkylbenzene sulfonates, fatty alcohol sulfates, polyvinyl alcohol, polypolyols, polyacrylamide, alkylolamides, and imidazoline with the PEEK / HA composite material. Additive B is one or more of ammonia, ethanolamine, resin, ethylene glycol, glycerol, butanol, isobutanol, alkynes, ethers, organosilicon, mineral oil, polyether, phosphate esters, polycarboxylate, and polyacrylic acid. The vanadium source is one or more of soluble salts of vanadium, soluble metal acids, dispersible oxides, or nanoparticles, such as ammonium metavanadate and vanadium oxalate. The tungsten source is one or more of the following: soluble salts of tungsten, soluble metal acids, dispersible oxides, or nanoparticles, such as ammonium metatungstate. The binder is one or more of the following: silica sol, aluminum sol, silica-alumina sol, titanium sol, or zirconium sol.

[0026] Example 1

[0027] S1. Dissolve 1.5 kg of polyethylene glycol and 200 g of poly(dimethylsiloxane-3-hydroxypropylmethylsiloxane) polyoxyethylene polyoxypropylene ether (CAS: 68937-55-3) in 110 kg of water, add 65 kg of titanium dioxide, and stir and mix at a rate of 50 r / min for 2 h.

[0028] S2. Add 2.5 kg of ammonium metavanadate, 4.2 kg of ammonium metatungstate and 5.2 kg of titanium sol to the suspension in S1 and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain an active slurry (slurry viscosity ≤ 1000 mPa·s).

[0029] S3. Place a 450mm×450mm×450mm corrugated glass fiber carrier (bulk density 60g / L) into a mold, and apply the active slurry to the carrier by impregnation coating. After the active slurry stays on the carrier for 1 minute, remove it and purge it with air (purge air pressure 60psi, purge air rate 5L / min, time 2min). Microwave dry at 100℃ for 2 hours to obtain the catalyst semi-finished product.

[0030] S4. The catalyst semi-finished product is calcined at 450℃ for 2 hours to obtain the medium-temperature SCR denitrification catalyst.

[0031] Example 2

[0032] S1. Dissolve 2 kg of sodium dodecylbenzenesulfonate and 100 g of mineral oil (purchased from Shanghai Beyotime Biotechnology Co., Ltd., model ST275) in 110 kg of water, add 65 kg of titanium dioxide, and stir and mix at a rate of 200 r / min for 2 h.

[0033] S2. Add 7.5 kg of vanadium oxalate, 4.2 kg of ammonium metatungstate and 4.8 kg of aluminum sol to the suspension in S1, and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain the active slurry.

[0034] S3. Place a 450mm×450mm×450mm corrugated glass fiber carrier into a mold, and coat the active slurry onto the carrier by vacuum coating. After vacuum coating at -20kPa for 60s, remove the catalyst and purge it with air (purge pressure of 60psi, purge air rate of 5L / min, time of 2min). Dry it under vacuum at 100℃ for 2h to obtain a catalyst semi-finished product.

[0035] S4. The SCR catalyst semi-finished product is calcined at 550℃ for 2 hours to obtain the medium-temperature SCR denitration catalyst.

[0036] Example 3

[0037] S1. Dissolve 6 kg of polyvinyl alcohol and 200 g of polyvinyl ether (CAS#:25104-37-4) in 110 kg of water, add 70 kg of titanium dioxide, and ultrasonically disperse for 2 h under stirring at a rate of 200 r / min.

[0038] S2. Add 9.5 kg of vanadium oxalate, 5.2 kg of ammonium metatungstate and 6.1 kg of silica sol to the suspension in S1, and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain an active slurry.

[0039] S3. Place a 450mm×450mm×450mm corrugated glass fiber carrier into an immersion frame. Apply the active slurry to the carrier by lifting and coating (each immersion time is 20s). Place the catalyst module into the immersion frame and lift and coat it repeatedly for 120s. Then remove it and purge it with air (purge air pressure is 60psi, purge air rate is 5L / min, time is 2min). Dry it with forced air at 100℃ for 2h to obtain the catalyst semi-finished product.

[0040] S4. The catalyst semi-finished product is calcined at 500℃ for 2 hours to obtain the medium-temperature SCR denitration catalyst.

[0041] Example 4

[0042] S1. Dissolve 3 kg of polyacrylamide and 150 g of dimethyl methyl phosphate (CAS#:813-78-5) in 110 kg of water, add 65 kg of titanium dioxide, and stir at a rate of 200 r / min for 2 h.

[0043] S2. Add 2.5 kg of ammonium metavanadate, 4.2 kg of ammonium metatungstate and 5.7 kg of silica sol to the suspension in S1, and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain an active slurry;

[0044] S3. Place a 450mm×450mm×450mm corrugated ceramic fiber carrier into a mold, and apply the active slurry to the carrier by impregnation coating. After the active slurry stays on the catalyst carrier for 1 minute, remove it and purge it with air (purge air pressure is 60psi, purge air rate is 5L / min, time is 2min). Dry it with forced air at 100℃ for 1 hour to obtain the catalyst semi-finished product.

[0045] S4. The catalyst semi-finished product is calcined at 450℃ for 3 hours to obtain the medium-temperature SCR denitration catalyst.

[0046] Example 5

[0047] S1. Dissolve 1.3 kg of polyethylene glycol and 200 g of poly(dimethylsiloxane-3-hydroxypropylmethylsiloxane) polyoxyethylene polyoxypropylene ether (CAS: 68937-55-3) in 110 kg of water, add 65 kg of titanium dioxide, and then add 0.2 kg of PEEK / HA composite material (preparation method: weigh equal amounts of 4,4'-difluorobenzophenone and hydroquinone into a reactor, add solvent diphenyl sulfone, m monomer (4,4'-difluorobenzophenone + hydroquinone): m diphenyl sulfone = 1:4.5; slowly heat and stir under nitrogen protection, and when the temperature rises to 180°C, add the salting agent (the mass ratio of hydroquinone to salting agent is 1:1.2, and the salting agent is a mixture of anhydrous sodium carbonate and anhydrous potassium carbonate in a mass ratio of 1:19); continue heating to 200°C. The temperature was raised to 320℃ after 20 minutes and maintained at a constant temperature for 3 hours. After the reaction was completed, sulfolane (equal in mass to diphenyl sulfone) preheated to 250℃ and nano-hydroxyapatite were slowly added to the reactor, and the mixture was stirred at 300℃ until homogeneous. While still hot, the product was quickly poured into a container filled with room temperature distilled water to coagulate and disperse, resulting in a blocky solid. The product was then crushed into powder and repeatedly extracted with acetone and distilled water to remove unreacted monomers, solvents, and inorganic salts. The powder was dried in a vacuum oven at 100℃ for more than 12 hours to obtain a grayish-white powder sample, i.e., the PEEK / HA composite material (HA accounts for 10 wt% in the PEEK / HA composite material). The mixture was stirred at a rate of 50 r / min for 2 hours.

[0048] S2. Add 2.5 kg of ammonium metavanadate, 4.2 kg of ammonium metatungstate and 4.7 kg of titanium sol to the suspension in S1 and stir evenly (stirring speed not exceeding 30 rpm / min and stirring time not less than 60 min) to obtain an active slurry.

[0049] S3. Prepare the SCR denitrification catalyst according to steps S3 and S4 of Example 1.

[0050] S4. The catalyst semi-finished product is calcined at 450℃ for 3 hours to obtain the medium-temperature SCR denitration catalyst.

[0051] Comparative Example 1

[0052] S1. Add 2.5 kg of ammonium metavanadate and 4.2 kg of ammonium metatungstate to 110 kg of water, add 65 kg of titanium dioxide, and stir at a rate of 200 r / min for 2 hours;

[0053] S2. Add 6.1 kg of silica sol to the S1 slurry and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain an active slurry;

[0054] S3. Prepare the SCR denitrification catalyst according to steps S3 and S4 of Example 1.

[0055] Comparative Example 2

[0056] S1. Dissolve the substance in 110kg of water, add 70kg of titanium dioxide, and stir at a rate of 200r / min for 2h.

[0057] S2. Add 9.5 kg of vanadium oxalate, 5.2 kg of ammonium metatungstate and 5.2 kg of silica sol to the suspension in S1 and stir evenly (stirring speed not exceeding 30 rpm / min, stirring time not less than 60 min) to obtain the active slurry.

[0058] S3. Prepare the SCR denitrification catalyst according to steps S3 and S4 of Example 3.

[0059] Comparative Example 3

[0060] The SCR denitrification catalyst was prepared according to the method in Example 5, but the PEEK / HA composite material was replaced by an equal mass of hydroxyapatite (HA).

[0061] Comparative Example 4

[0062] The SCR denitrification catalyst was prepared according to the method in Example 5, but the PEEK / HA composite material was replaced with PEEK (polyether ether ketone) by an equal mass. The PEEK preparation method was as follows: equal amounts of 4,4'-difluorobenzophenone and hydroquinone were weighed into a reactor, and diphenyl sulfone was added as solvent. The ratio of m monomer (4,4'-difluorobenzophenone + hydroquinone): m diphenyl sulfone = 1:4.5. Under nitrogen protection, the mixture was slowly heated and stirred. When the temperature reached 180°C, the composite salt (the mass ratio of hydroquinone to composite salt was 1:1.2, and the composite salt was a mixture of anhydrous sodium carbonate and anhydrous potassium carbonate in a mass ratio of 1:9) was added. The temperature was further increased to 200°C, and after 20 minutes, it was increased to 320°C and kept constant for 3 hours. After the reaction, the mixture was subjected to nitrogen treatment. Cool to room temperature under an atmospheric pressure, add acetone and boil until the product can be poured out. Crush the crude product into powder and repeatedly extract and wash it with acetone and distilled water to remove unreacted monomers, solvents and inorganic salts. Dry it in a vacuum oven at 100°C for more than 12 hours to obtain PEEK.

[0063] Performance testing:

[0064] (1) Loading test: Accurately weigh the mass (W0) of the initially clean and dry corrugated fiber support and the mass (W1) of the final catalyst. The volume of the final catalyst sample is known to be V. Calculate the loading (total coating) according to the following formula: Loading (total coating) = (W1 - W0) / V.

[0065] (2) Adhesion rate test: The catalyst was cut into cubes of 50mm×50mm×50mm, dried at 110℃ for 2h, and the initial weight of the catalyst was recorded as m1. The sample was immersed in ultrapure water and sonicated for 30min. After sonication, the catalyst sample was dried at 110℃ for 2h, and the mass of the catalyst was recorded as m2.

[0066] Calculate using this formula: .

[0067] (3) Pressure drop, porosity and denitrification conversion rate (i.e. denitrification efficiency) were tested in accordance with the method of GB / T 39703-2020 "Technical Specification for Testing Corrugated Plate Denitrification Catalyst".

[0068] In the denitrification conversion rate test, the sample volume was 150mm × 150mm × 300mm, and the catalyst sample pitch was 3.2mm. The fixed-bed reactor was subjected to programmed temperature increase. After the reaction reached adsorption equilibrium, the inlet and outlet concentrations of the catalyst before and after the reaction were measured using a flue gas analyzer. The denitrification conversion rates of the medium-temperature SCR catalysts in Examples 1-4 and Comparative Examples 1-2 were calculated as follows: Figure 1 As shown. Test conditions: NO concentration 350 ppm, ammonia-nitrogen molar ratio = 1:1, O2 vol% = 3%, H2O vol% = 6%, reaction space velocity SV = 45000 h⁻¹ -1 .

[0069] (4) Refer to GB / T 31587-2015 to test the axial compressive strength: cut a sample with length × width × height = 50cm × 26cm × 26cm, place the test sample between two parallel pressure plates of the universal testing machine, ensure that the force-bearing surface is flat and in complete contact with the pressure plates, apply axial pressure at a constant rate of 2mm / min; record the maximum pressure value (F) at the moment the sample is crushed, in N; calculate the axial strength (MPa) = maximum pressure (N) / cross-sectional area of ​​the sample (mm²).

[0070] The performance test results of the catalysts prepared in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1.

[0071] Table 1

[0072]

[0073] The catalysts prepared in Comparative Examples 3 and 4 had pressure drops of 256 and 278 Pa, respectively, axial compressive strengths of 1.7 MPa and 1.9 MPa, respectively, and denitrification conversion rates of 91.04% and 92.7% at 320℃, respectively.

[0074] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a medium-temperature corrugated plate SCR denitration catalyst, characterized in that, Includes the following steps: S1: Mix titanium dioxide, additives and deionized water in a certain proportion, and add vanadium source, tungsten source and binder to prepare an active slurry; S2: The active slurry is coated onto a corrugated fiber carrier and dried to obtain a catalyst semi-finished product. S3: The catalyst semi-finished product is roasted to obtain the medium-temperature corrugated plate SCR denitrification catalyst.

2. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, In step S1, the mass ratio of titanium dioxide, additives and deionized water is (60-75):(1-7):

110.

3. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The mass ratio of vanadium source, tungsten source, binder and titanium dioxide in step S1 is (2-10):(1-6):(20-100):(60-75).

4. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The additive is a mixture of additive A and additive B, with a mass ratio of additive A to additive B of (1-6):(0.1-0.5).

5. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 4, characterized in that, Additive A is one or more of alkylbenzene sulfonates, fatty alcohol sulfates, polyvinyl alcohol, polypolyols, polyacrylamide, alkylolamides, and imidazoline; Additive B is one or more of ammonia, ethanolamine, resin, ethylene glycol, glycerol, butanol, isobutanol, alkynes, ethers, organosilicon, mineral oil, phosphate esters, polyethers, polycarboxylates, and polyacrylic acids.

6. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The vanadium source is one or more of the following: soluble salts of vanadium, soluble metal acids, dispersible oxides, or nanoparticles.

7. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The tungsten source is one or more of the following: soluble salts of tungsten, soluble metal acids, dispersible oxides, or nanoparticles.

8. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The binder is one or more of silica sol, aluminum sol, silica-alumina sol, titanium sol, or zirconium sol.

9. The preparation method of a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, The corrugated fiber carrier is either a corrugated glass fiber carrier or a corrugated ceramic fiber carrier.

10. The method for preparing a medium-temperature corrugated plate SCR denitration catalyst according to claim 1, characterized in that, In step S2, the coating method is one of dip coating, spray coating, vacuum coating, dip coating or pressure coating, and the drying method is one of vacuum drying, hot air drying, natural air drying or microwave drying; in step S3, the calcination temperature is 450-550℃, and the calcination time is 2-6h.

Images