A flue gas denitrification method

Abstract

This invention provides a flue gas denitrification method in which flue gas is contacted with a corrugated plate catalyst in the presence of ammonia for denitrification treatment. The corrugated plate catalyst includes a support and active components, wherein the active components include oxides of cerium, vanadium, and tungsten. The mass ratio of cerium oxide to the support is (5-20):100, the mass ratio of vanadium oxide to the support is (0.5-10):100, and the mass ratio of tungsten oxide to the support is (1-12):100. This method has the advantages of high denitrification efficiency and good stability, effectively reducing pollutant emissions.

Description

Technical Field

[0001] This invention belongs to the field of flue gas treatment technology, and specifically relates to a flue gas denitrification method. Background Technology

[0002] With the rapid development of my country's economy and industrial production, nitrogen oxide (NOx) emissions have also increased. NOx causes pollution such as photochemical smog and the greenhouse effect, seriously endangering human health. To promote the comprehensive development of emission reduction technologies, how to reduce the generation and emission of NOx has become one of the main concerns.

[0003] Selective catalytic reduction (SCR) refers to the process in which a reducing agent reacts with NOx in flue gas under the action of a catalyst to produce non-toxic and non-polluting N2 and H2O. It is a relatively mature NOx purification method at present. Among them, the SCR technology using ammonia as a reducing agent (NH3-SCR) is widely used in the emission control of NOx from industrial stationary sources.

[0004] The catalyst is a core component of the SCR process, directly affecting its catalytic activity and thus the NOx conversion efficiency. For example, the catalysts disclosed in patent documents CN201110345605, CN101352679A, CN102500424A, and CN107138150B have small specific surface areas and uneven component distribution, which affect the denitrification effect. In addition, the catalysts are prone to cracking, difficult to form, and easily damaged. Summary of the Invention

[0005] This invention provides a flue gas denitrification method that brings flue gas into contact with a corrugated plate catalyst for denitrification treatment. This method has the advantages of high denitrification efficiency and good stability, and effectively reduces pollutant emissions.

[0006] In one aspect, the present invention provides a flue gas denitrification method, wherein flue gas is contacted with a corrugated plate catalyst in the presence of ammonia to perform denitrification treatment; the corrugated plate catalyst includes a support and an active component, wherein the active component includes oxides of cerium, vanadium, and tungsten; the mass ratio of cerium oxide to support is (5-20):100, the mass ratio of vanadium oxide to support is (0.5-10):100, and the mass ratio of tungsten oxide to support is (1-12):100; wherein the mass of cerium oxide is calculated as CeO2, the mass of vanadium oxide is calculated as V2O5, and the mass of tungsten oxide is calculated as WO3.

[0007] According to one embodiment of the present invention, the molar ratio of nitrogen oxides in ammonia flue gas is (0.8~1.2):1, wherein the nitrogen oxides are calculated as nitrogen atoms.

[0008] According to one embodiment of the present invention, ammonia gas is first injected into the denitrification reactor, and then flue gas is introduced into the denitrification reactor to contact the flue gas with the corrugated plate catalyst in the denitrification reactor.

[0009] According to one embodiment of the present invention, the temperature of the flue gas entering the denitrification reactor is 260°C to 420°C.

[0010] According to one embodiment of the present invention, the volume concentration of ammonia is 100 mg / Nm³. 3 ~1200 mg / Nm 3 .

[0011] According to one embodiment of the present invention, the thickness of the corrugated plate catalyst is 0.2 mm to 0.6 mm, the peak width of the corrugated plate catalyst is 4 mm to 8 mm, and the peak height of the corrugated plate catalyst is 4 mm to 10 mm.

[0012] According to one embodiment of the present invention, the volume hourly space velocity is 6000 h. -1 ~13000h -1 .

[0013] According to one embodiment of the present invention, the carrier includes a titanium dioxide carrier.

[0014] According to one embodiment of the present invention, a method for preparing a corrugated plate catalyst includes the following steps: uniformly mixing a cerium source, nano-oxides, and a support using a sol-gel method, and obtaining an intermediate after a first drying and a first calcination; dissolving the nano-oxides in the intermediate using an alkaline solution to obtain an alkaline-soluble product; mixing the alkaline-soluble product, a vanadium source, a tungsten source, a binder, and water to form a slurry, and stamping the slurry to obtain corrugated sheets, wherein the mass of water is 5%-60% of the mass of the slurry; stacking several of the corrugated sheets to obtain a green body, and obtaining a corrugated plate catalyst after a second drying and a second calcination.

[0015] According to one embodiment of the present invention, each corrugated sheet has a thickness of 0.2 mm to 0.6 mm, a crest width of 4 mm to 8 mm, and a crest height of 4 mm to 10 mm.

[0016] According to one embodiment of the present invention, the nano-oxide includes at least one of nano-alumina and nano-silica.

[0017] The implementation of this invention has at least the following beneficial effects:

[0018] The flue gas denitrification method provided by this invention uses a corrugated plate catalyst for denitrification. This corrugated plate catalyst has good formability, is easy to transport, occupies a small area, and has uniformly dispersed active components, which can play a synergistic role and greatly improve the catalytic activity of the catalyst. When in contact with flue gas, it can enable ammonia to preferentially undergo catalytic reduction reaction with nitrogen oxides, and has the advantages of high denitrification efficiency and good stability. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] The flue gas denitrification method provided by this invention involves contacting flue gas with a corrugated plate catalyst in the presence of ammonia to perform denitrification treatment. The corrugated plate catalyst includes a support and active components, wherein the active components include oxides of cerium, vanadium, and tungsten. The mass ratio of cerium oxide to support is (5-20):100, the mass ratio of vanadium oxide to support is (0.5-10):100, and the mass ratio of tungsten oxide to support is (1-12):100. The mass of cerium oxide is calculated as CeO2, the mass of vanadium oxide as V2O5, and the mass of tungsten oxide as WO3.

[0021] The inventors discovered that in the aforementioned corrugated plate catalyst, the active components cerium, tungsten, vanadium, and titanium work synergistically to preferentially reduce ammonia with nitrogen oxides, thereby improving denitrification efficiency. Secondly, this corrugated plate denitrification catalyst has advantages such as high molding rate, low manufacturing cost, low breakage rate, and small size, reducing space requirements and lowering costs. When used in flue gas denitrification treatment, it exhibits advantages such as high denitrification efficiency, good stability, and suitability for high space velocity environments.

[0022] The flue gas denitrification method provided by the present invention uses a corrugated plate catalyst as a catalyst for SCR denitrification. The specific process includes: placing the corrugated plate denitrification catalyst in a reactor, introducing a mixed gas containing ammonia and heating it, and simultaneously introducing flue gas to allow the flue gas to fully contact the catalyst for denitrification treatment.

[0023] In this invention, the flue gas can be selected from the flue gas emitted by conventional equipment, such as flue gas from a coal-fired power plant or flue gas from an ethylene cracking furnace.

[0024] In some embodiments, the molar ratio of ammonia to nitrogen oxides in flue gas is (0.8~1.2):1, for example, a range consisting of 0.8:1, 1:1, 1.1:1, 1.2:1 or any two thereof, wherein the number of moles of ammonia and nitrogen oxides is expressed in terms of the number of moles of nitrogen atoms.

[0025] In this invention, the temperature for denitrification treatment is 260°C-420°C. In the above embodiments, the temperature of the flue gas entering the denitrification reactor can be 260°C to 420°C.

[0026] The ammonia gas of the present invention can be introduced using conventional methods, such as in the form of ammonia gas. Preferably, the ammonia gas is mixed with other gases to form a mixer containing ammonia gas, and then the mixed gas is introduced. In some embodiments, the mixed gas containing ammonia gas is first injected into the denitrification reactor, and then the flue gas is allowed to enter the denitrification reactor so that the flue gas comes into contact with the corrugated plate catalyst in the denitrification reactor.

[0027] In the above embodiments, the concentration of ammonia is determined based on the NOx concentration in the flue gas, and can be 100 mg / Nm³. 3 ~1200 mg / Nm 3 .

[0028] In the above embodiment, the volume hourly space velocity is 6000 h⁻¹. -1 ~13000h -1 .

[0029] The carrier of the present invention can be a conventional carrier in the art, such as a titanium dioxide carrier.

[0030] The preparation method of the corrugated plate catalyst in this invention includes the following steps: uniformly mixing a cerium source, nano-oxides and a support using a sol-gel method, and obtaining an intermediate after a first drying and a first calcination; dissolving the nano-oxides in the intermediate using an alkaline solution to obtain an alkaline-soluble product; mixing the alkaline-soluble product, a vanadium source, a tungsten source, a binder and water to form a slurry, and stamping the slurry to obtain corrugated sheets, wherein the mass of water is 5%-60% of the mass of the slurry; stacking several of the corrugated sheets to obtain a green body, and obtaining a corrugated plate catalyst after a second drying and a second calcination.

[0031] In the specific implementation of the present invention, the preparation method of the corrugated plate catalyst may include the following steps: (1) mixing titanium source and alcohol solvent to obtain solution A; then mixing cerium source, nano oxide, barrier agent and glacial acetic acid, adjusting pH to 1-5 to obtain solution B, wherein the nano oxide includes at least one of nano alumina and nano silica; (2) adding solution B to solution A to form a gel, and obtaining an intermediate after first drying and first calcination; (3) using an alkaline solution to dissolve the intermediate to obtain an alkaline dissolved product; (4) mixing the alkaline dissolved product, vanadium source, tungsten source, dispersant and binder to obtain mud; pressing the mud into corrugated sheets, stacking several corrugated sheets to obtain a catalyst blank, and obtaining a corrugated plate denitrification catalyst after second drying and second calcination.

[0032] The method for preparing the corrugated plate denitration catalyst provided by this invention involves first incorporating cerium (Ce) into the titanium dioxide (TiO2) lattice using a sol-gel method, thereby encapsulating nano-oxides within the titanium dioxide. Then, an alkaline solution is used for alkali dissolution to remove the nano-oxides, yielding an alkali-dissolved product. Finally, the alkali-dissolved product is mixed with a vanadium source and a tungsten source to form a slurry. The slurry is then pressed into corrugated sheets, and several corrugated sheets are stacked to form a corrugated plate. After drying and calcination, the corrugated plate denitration catalyst is obtained. This method allows vanadium and tungsten oxides to be loaded onto a cerium-doped titanium dioxide support. This corrugated plate denitration catalyst has advantages such as high formability and high catalytic activity.

[0033] The inventors, through research and analysis, believe that in steps (1) and (2), by adding solution B to solution A, mixing the cerium source, titanium source, and nano-oxide, and then subjecting the mixture to a first drying and a first calcination, cerium (Ce) is incorporated into the titanium dioxide (TiO2) lattice, creating lattice defects in titanium dioxide, which is beneficial for the generation of oxygen vacancies. Simultaneously, the nano-oxide is encapsulated within the titanium dioxide. In step (3), the intermediate is dissolved using an alkaline solution, which dissolves the nano-oxide in the intermediate, greatly increasing the lattice defects and specific surface area of ​​the intermediate. In step (4), the alkaline solution product fully contacts the vanadium source and tungsten source, allowing the active components tungsten and vanadium to fill the nano-spaces and lattice defects, further improving the dispersion of the active components tungsten and vanadium. Furthermore, the catalyst is made into a corrugated plate, which helps to improve the yield of the prepared catalyst. In the above preparation process, the active components cerium, tungsten, and vanadium oxides are more uniformly loaded onto the titanium dioxide support, which is beneficial for improving the catalytic activity of the catalyst.

[0034] In step (1) above, the titanium source includes at least one of tetrabutyl titanate, titanium sulfate, titanium isopropoxide, and titanium tetrachloride, and the alcohol solvent includes ethanol. The volume ratio of the alcohol solvent to the titanium source is (3-20):1, preferably (5-10):1. The alcohol solvent enables the titanium source to form titanium hydroxide in solution A, which is beneficial for the formation of titanium dioxide crystals after subsequent calcination.

[0035] In the above embodiments, the cerium source includes at least one of cerium nitrate, cerium sulfate, and cerium chloride. The mass ratio of the cerium source to the titanium source is (5-20):100, preferably (6-12):100, wherein the mass of the cerium source is based on CeO2 and the mass of the titanium source is based on TiO2.

[0036] In the above embodiments, the nano-oxide includes at least one of nano-alumina and nano-silica, or it can be nano-alumina sol. The particle size of the nano-oxide can be 1nm-50nm, preferably 1nm-30nm.

[0037] In the above embodiments, the mass ratio of nano-oxide to titanium source is (0.5-5):100, preferably (0.5-2):100, wherein the mass of nano-oxide is calculated as Al2O3.

[0038] In the above embodiments, the mass ratio of the barrier agent to the titanium source is (0.3-5):100, preferably (0.5-2):100. The barrier agent can be polyethylene glycol, and the molecular weight of polyethylene glycol can be 400-10000, preferably 1500-2000.

[0039] In the above embodiments, the mass ratio of glacial acetic acid with catalytic activity to titanium source is (1-5):100, wherein the mass of titanium source is calculated as TiO2.

[0040] In the specific implementation of this invention, for example, cerium source, nano oxide, polyethylene glycol, glacial acetic acid, ethanol and water can be mixed and stirred, and an acid solution can be added to adjust the pH to 1-5 to obtain solution B, wherein the pH value is preferably 2-4.

[0041] In the above embodiments, step (1) adjusting the pH to 1-5 can be achieved by adding hydrochloric acid, which can be either dilute or concentrated hydrochloric acid. Adjusting the pH of the reaction system controls the rate at which metal ions react with hydroxyl groups to form polymers.

[0042] In the specific implementation of the present invention, step (2) specifically includes: slowly dripping solution B into solution A and stirring, controlling the temperature at a certain level, continuing to stir after the addition is complete to obtain a uniform sol, then obtaining a gel, aging the gel, and then performing a first drying and a first calcination to obtain an intermediate.

[0043] In step (2) above, on the one hand, cerium is doped into the titanium dioxide lattice, causing lattice defects. After the first calcination, the lattice defects become more stable. On the other hand, nano-oxides are wrapped in titanium dioxide, which helps to form more nano-spaces and lattice defects after subsequent alkali treatment.

[0044] In the above embodiments, solution B diffuses uniformly in solution A. The stirring process can be mechanical stirring or ultrasonic-assisted stirring. The aging time can be 0.5-10 days, preferably 2-5 days.

[0045] In the above embodiments, the temperature is generally controlled between 10℃ and 90℃, preferably between 20℃ and 60℃. In the specific implementation of the present invention, the temperature of solution A can be controlled between 10℃ and 90℃, and then solution B is added to solution A within the above temperature range.

[0046] In step (2) above, the temperature of the first drying is 60℃-180℃, preferably 60℃-90℃, and the time is 5h-50h, preferably 8h-30h.

[0047] In the above embodiments, the temperature of the first calcination is 400℃-680℃, preferably 450℃-610℃, and the time is 2h-35h, preferably 3h-20h.

[0048] In step (3) of this invention, an alkaline solution is used to dissolve the intermediate. The alkaline solution can dissolve the nano-oxides in the intermediate, forming lattice defects and nano-spaces, which further increases the lattice defects and specific surface area.

[0049] In the above embodiments, the solvent of the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide, the concentration of the alkaline solution is 0.1 mol / L-5.0 mol / L, and the volume ratio of the alkaline solution to the catalyst intermediate is (0.5-8):1, preferably (0.8-3):1.

[0050] In the above embodiments, the solid produced after alkali dissolution is further washed. Deionized water can be used as the washing liquid, and the washing is preferably repeated 3-5 times. Then, the product is obtained by filtration.

[0051] In step (4) of this invention, the alkali-soluble product, vanadium source, tungsten source, dispersant, binder and pore-forming agent are mixed to form a mud. The mud is first shaped and pressed into corrugated sheets. Several corrugated sheets are then stacked to obtain a catalyst blank. After a second drying and a second calcination, a corrugated plate denitrification catalyst is obtained. Since the alkali-soluble product has more lattice defects, the vanadium source and tungsten source can fill the lattice defects, which is beneficial to improving the dispersibility of the active components. At the same time, making the catalyst into a corrugated plate can improve the catalyst forming rate.

[0052] In the above embodiments, the dispersant includes at least one of polyacrylamide and polyvinylpyrrolidone, and the mass ratio of the dispersant to the titanium source is (0.2-3):100.

[0053] In the above embodiments, the binder includes at least one of carboxymethyl cellulose and hydroxypropyl cellulose, and the mass ratio of the second binder to the titanium source is (0.5-2):100.

[0054] In the specific implementation of this invention, the alkali-soluble product, vanadium source, tungsten source, dispersant, binder, pore-forming agent and water can be mixed to form a mud. The mud is then pressed into corrugated sheets, and several corrugated sheets are stacked to obtain a catalyst blank. After a second drying and a second calcination, a corrugated plate denitrification catalyst is obtained. The pore-forming agent can be at least one of polyethylene oxide, polymethyl methacrylate and guar gum powder. The mass ratio of the pore-forming agent to the titanium source is (0.2-2):100.

[0055] In the above embodiments, the water content in the mud can be 5%-60%, preferably 12-40%.

[0056] In the above embodiments, before forming the mud, the pH value is adjusted to 7-12, preferably 7.5-10.5, which helps with molding. Ammonia or other alkaline agents can be used to adjust the pH.

[0057] In the above embodiments, each corrugated sheet can be bonded together with resin adhesive, such as epoxy resin adhesive.

[0058] In the above embodiments, the temperature for the second drying is 50℃-150℃, preferably 60℃-100℃, and the time is 1-30 days, preferably 5-15 days. During the second drying process, the ambient humidity is controlled at 40%-99.5%, preferably 75%-98%.

[0059] In the above embodiments, the temperature of the second calcination is 450℃-680℃, preferably 450℃-610℃, and the time is 2h-40h, preferably 3h-20h.

[0060] In the above embodiments, the second calcination is carried out according to the following process of programmed heating: the heating rate is controlled to be no more than 1℃ / min, and after the temperature reaches the predetermined temperature of 450℃-680℃, it is calcined at a constant temperature for 2h-40h, and then a cooling process is carried out, with a cooling rate of no more than 4℃ / min, and the temperature is reduced to below 50℃, and the calcination ends.

[0061] In the above embodiments, the vanadium source includes at least one of ammonium vanadate and ammonium metavanadate, preferably ammonium vanadate, and the mass ratio of vanadium source to titanium source is (0.5-10):100, preferably (0.5-5):100, wherein the mass of vanadium source is V2O5 and the mass of titanium source is TiO2.

[0062] In the above embodiments, the tungsten source includes at least one of ammonium tungstate and ammonium metatungstate, preferably ammonium tungstate, and the mass ratio of tungsten source to titanium source is (1-12):100, preferably (2-8):100, wherein the tungsten source is calculated as WO3 and the titanium source is calculated as TiO2.

[0063] The corrugated plate denitrification catalyst provided by the present invention is prepared by the above-described preparation method. The corrugated plate denitrification catalyst can use titanium dioxide as a support and cerium, tungsten, and vanadium as active components of the denitrification catalyst.

[0064] In the above embodiments, the size of the corrugated plate denitrification catalyst is determined according to the actual situation. For example, the thickness of each corrugated plate can be 0.2 mm-0.6 mm, the width of the crest can be 4 mm-8 mm, and the height of the crest can be 4 mm-10 mm.

[0065] In the aforementioned corrugated plate denitration catalyst, cerium is doped into the titanium dioxide lattice, and tungsten and vanadium oxides are supported on the titanium dioxide support. The active components cerium, tungsten, and vanadium are uniformly dispersed on the titanium dioxide support. Cerium, tungsten, and vanadium work synergistically with titanium dioxide to enable ammonia to preferentially undergo catalytic reduction reactions with nitrogen oxides, thereby improving denitration efficiency. Secondly, the doping of cerium improves the catalyst's resistance to alkali metal poisoning and alkaline earth metal poisoning. In addition, this corrugated plate denitration catalyst has advantages such as high molding rate, low manufacturing cost, low breakage rate, and small size, which can reduce space occupation and lower costs.

[0066] The flue gas denitrification method provided by the present invention uses the above-mentioned corrugated plate catalyst as a catalyst for SCR denitrification. The active components in the catalyst work together to enable ammonia to preferentially undergo catalytic reduction reaction with nitrogen oxides, thereby improving the denitrification efficiency.

[0067] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0068] In all the embodiments and comparative examples, the other chemicals used were commercially available chemically pure reagents, and were evaluated using the following assay methods:

[0069] (1) Specific surface area

[0070] The specific surface area of ​​the sample was determined using the BET adsorption method.

[0071] (2) Denitrification efficiency

[0072] The flue gas is denitrified using the following methods:

[0073] The catalyst is placed in a fixed-bed reactor, and a mixture of oxygen and nitrogen is introduced, along with flue gas, to ensure that the flue gas and catalyst are in full contact for denitrification. The concentration of each component in the flue gas and tail gas is measured by a flue gas analyzer. The NOx conversion rate is calculated as (NOx concentration in flue gas - NOx concentration in tail gas) / NOx concentration in flue gas.

[0074] The flue gas analyzer is a Siemens ULTRAMAT23 continuous online flue gas analyzer; the O2 content in the reactor is 3% (v), and nitrogen is used as a balance gas; NO and N2 are also present. 2、 The NH3 is produced by Dalian Date Gas Co., Ltd., the O2 comes from the public utility air pipeline network at a pressure of 0.4-0.6 MPa, and the N2 comes from the public utility nitrogen pipeline network with a purity of 99.0% (V) and a pressure of 0.4-0.6 MPa.

[0075] Example 1:

[0076] The catalyst was prepared under the following conditions:

[0077] Solution A is prepared by mixing 100g of tetrabutyl titanate with first ethanol. Solution B is prepared by mixing 8g of cerium nitrate, 2.0g of nano-aluminum sol, 0.5g of polyethylene glycol, 5mL of glacial acetic acid, and second ethanol, adjusting the pH to 2 with hydrochloric acid, and then sonicating. The mass of tetrabutyl titanate is calculated as TiO2, the mass of cerium nitrate is calculated as CeO2, and the mass of nano-aluminum sol is calculated as Al2O3. The volume ratio of first ethanol to tetrabutyl titanate is 10:1, and the volume ratio of second ethanol to first ethanol is 1:1.

[0078] The temperature of solution A was controlled at 50°C. Solution B was slowly added to solution A and stirred. After the addition was complete, a gel was obtained. The gel was aged at room temperature for 3 days, then dried at 70°C for 20 hours, and then calcined in a muffle furnace at 450°C for 20 hours. The obtained solid was ground to obtain an intermediate.

[0079] The intermediate was impregnated with a 0.1 mol / L sodium hydroxide solution, and the impregnated product was obtained after washing and filtration, wherein the volume ratio of sodium hydroxide solution to intermediate was 1:1.

[0080] The impregnation product was mixed with 5.0g ammonium vanadate, 2.0g ammonium metatungstate, 8.0g carboxymethyl cellulose, 1.0g polyvinylpyrrolidone, 0.3g polymethyl methacrylate, and water to prepare a mud with a moisture content of 15%. The pH was adjusted to 8.0, and corrugated plates were stamped out. Epoxy resin was sprayed between the corrugated plates and then stacked to obtain a corrugated plate denitrification catalyst blank. After drying, the blank was calcined at 520℃ for 12h to obtain the corrugated plate NH3-SCR denitrification catalyst C1. The mass of ammonium metatungstate was calculated as WO3, and the mass of ammonium vanadate was calculated as V2O5.

[0081] Catalyst C1 was cut into 3×3×12cm cylindrical pieces and loaded into the reactor. The catalyst loading amount was 108mL. The denitrification effect of the catalyst was evaluated.

[0082] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 260°C, space velocity 6000 h⁻¹. -1 NO concentration in flue gas 500 mg / Nm 3 NH3 concentration 600 mg / Nm 3 ;

[0083] The catalyst obtained above has a specific surface area of ​​48 m². 2 / g, NO x The conversion rate was 90.7%.

[0084] Example 2

[0085] The catalyst was prepared under the following conditions:

[0086] Solution A is prepared by mixing 100g of titanium sulfate with first ethanol. Solution B is prepared by mixing 12.0g of cerium sulfate, 1.0g of nano-silica, 1.5g of polyethylene glycol, 2mL of glacial acetic acid, and second ethanol, adjusting the pH to 3 with hydrochloric acid, and then sonicating. The mass of titanium sulfate is calculated as TiO2, the mass of cerium sulfate is calculated as CeO2, and the mass of nano-silica is calculated as Al2O3. The volume ratio of first ethanol to titanium sulfate is 5:1, and the volume ratio of second ethanol to first ethanol is 1.5:1.

[0087] The temperature of solution A was controlled at 50°C. Solution B was slowly added to solution A and stirred. After the addition was complete, a gel was obtained. The gel was aged at room temperature for 4 days, then dried at 90°C for 12 hours, and then calcined in a muffle furnace at 450°C for 7 hours. The obtained solid was ground to obtain an intermediate.

[0088] The intermediate was impregnated with a 2 mol / L sodium hydroxide solution, and the impregnated product was obtained after washing and filtration, wherein the volume ratio of sodium hydroxide solution to intermediate was 1.2:1.

[0089] The impregnation product was mixed with 5.0g ammonium metavanadate, 8.0g ammonium metatungstate, 7.0g carboxymethyl cellulose, 0.8g polyvinylpyrrolidone, 1.0g polyoxyethylene, and water to prepare a mud with a moisture content of 25%. The pH was adjusted to 10.0, and corrugated plates were stamped out. Epoxy resin was sprayed between the corrugated plates and then stacked to obtain a corrugated plate denitrification catalyst blank. After drying, the blank was calcined at 550℃ for 8 hours to obtain the corrugated plate NH3-SCR denitrification catalyst C2. The mass of ammonium metatungstate was calculated as WO3, and the mass of ammonium metavanadate was calculated as V2O5.

[0090] Catalyst C2 was cut into 3×3×12cm cylindrical pieces and loaded into the reactor. The catalyst loading amount was 108mL. The denitrification effect of the catalyst was evaluated.

[0091] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 420°C, space velocity 13000 h⁻¹. -1 The NO concentration in the flue gas was 800 mg / Nm³. 3 NH3 concentration 800 mg / Nm 3 ;

[0092] The catalyst obtained above has a specific surface area of ​​57 m². 2 / g, NO x The conversion rate was 98.0%.

[0093] Example 3

[0094] The catalyst was prepared under the following conditions:

[0095] Solution A is prepared by mixing 100g of titanium isopropoxide with first ethanol. Solution B is prepared by mixing 6.0g of cerium sulfate, 0.5g of nano-alumina, 1.5g of polyethylene glycol, 3mL of glacial acetic acid, and second ethanol, adjusting the pH to 4 with hydrochloric acid, and then sonicating. The mass of titanium isopropoxide is calculated as TiO2, the mass of cerium sulfate is calculated as CeO2, and the mass of nano-silica is calculated as Al2O3. The volume ratio of first ethanol to titanium sulfate is 7:1, and the volume ratio of second ethanol to first ethanol is 1:1.

[0096] The temperature of solution A was controlled at 50°C. Solution B was slowly added to solution A and stirred. After the addition was complete, a gel was obtained. The gel was aged at room temperature for 5 days, then dried at 80°C for 20 hours, and then calcined in a muffle furnace at 450°C for 6 hours. The obtained solid was ground to obtain an intermediate.

[0097] The intermediate was impregnated with a 1.5 mol / L sodium hydroxide solution, and the impregnated product was obtained after washing and filtration, wherein the volume ratio of sodium hydroxide solution to intermediate was 2:1.

[0098] The impregnation product was mixed with 2.0g ammonium vanadate, 4.0g ammonium tungstate, 1.6g carboxymethyl cellulose, 1.6g polyvinylpyrrolidone, 1.0g polyoxyethylene, and water to prepare a mud with a moisture content of 25%. The pH was adjusted to 9.0, and corrugated plates were stamped out. Epoxy resin was sprayed between the corrugated plates and then stacked to obtain a corrugated plate denitrification catalyst blank. After drying, the blank was calcined at 600℃ for 5 hours to obtain the corrugated plate NH3-SCR denitrification catalyst C3. The mass of ammonium tungstate was calculated as WO3, and the mass of ammonium vanadate was calculated as V2O5.

[0099] Catalyst C3 was cut into 3×3×12cm cylindrical pieces and loaded into the reactor. The catalyst loading amount was 108mL. The denitrification effect of the catalyst was evaluated.

[0100] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 380°C, space velocity 10000 h⁻¹. -1 NO concentration in flue gas 800 mg / Nm 3 NH3 concentration 800 mg / Nm 3 ;

[0101] The catalyst obtained above has a specific surface area of ​​52 m². 2 / g, NO x The conversion rate was 99.3%.

[0102] Example 4

[0103] The catalyst was prepared under the following conditions:

[0104] Solution A is prepared by mixing 100g of titanium isopropoxide with first ethanol. Solution B is prepared by mixing 7.0g of cerium sulfate, 1.5g of nano-alumina, 2g of polyethylene glycol, 3mL of glacial acetic acid, and second ethanol, adjusting the pH to 3 with hydrochloric acid, and then sonicating. The mass of titanium isopropoxide is calculated as TiO2, the mass of cerium sulfate is calculated as CeO2, and the mass of nano-alumina is calculated as Al2O3. The volume ratio of first ethanol to titanium sulfate is 6:1, and the volume ratio of second ethanol to first ethanol is 1:1.

[0105] The temperature of solution A was controlled at 40°C. Solution B was slowly added to solution A and stirred. After the addition was complete, a gel was obtained. The gel was aged at room temperature for 3 days, then dried at 85°C for 14 hours, and then calcined in a muffle furnace at 500°C for 6 hours. The obtained solid was ground to obtain an intermediate.

[0106] The intermediate was impregnated with a 2 mol / L sodium hydroxide solution, and the impregnated product was obtained after washing and filtration, wherein the volume ratio of sodium hydroxide solution to intermediate was 1:1.

[0107] The impregnation product was mixed with 1.0g ammonium vanadate, 5.0g ammonium tungstate, 5.0g hydroxypropyl cellulose, 1.5g polyacrylamide, 1.0g guar gum powder, and water to prepare a mud with a moisture content of 30%. The pH was adjusted to 9.0, and corrugated plates were stamped out. Epoxy resin was sprayed between the corrugated plates and then stacked to obtain a corrugated plate denitrification catalyst blank. After drying, the blank was calcined at 600℃ for 5 hours to obtain the corrugated plate NH3-SCR denitrification catalyst C3. The mass of ammonium tungstate was calculated as WO3, and the mass of ammonium vanadate was calculated as V2O5.

[0108] Catalyst C3 was cut into 3×3×12cm cylindrical pieces and loaded into the reactor. The catalyst loading amount was 108mL. The denitrification effect of the catalyst was evaluated.

[0109] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 350°C, space velocity 8000 h⁻¹. -1 NO concentration in flue gas 1200 mg / Nm 3 NH3 concentration 1200 mg / Nm 3 ;

[0110] The catalyst obtained above has a specific surface area of ​​54 m². 2 / g, NO x The conversion rate was 99.0%.

[0111] Example 5

[0112] The catalyst was prepared under the following conditions:

[0113] Solution A is prepared by mixing 100g of tetrabutyl titanate with first ethanol. Solution B is prepared by mixing 6.0g of cerium sulfate, 2g of nano-alumina, 1g of polyethylene glycol, 3mL of glacial acetic acid, and second ethanol, adjusting the pH to 3 with hydrochloric acid, and then sonicating. The mass of tetrabutyl titanate is calculated as TiO2, the mass of cerium sulfate is calculated as CeO2, and the mass of nano-alumina is calculated as Al2O3. The volume ratio of first ethanol to titanium sulfate is 8:1, and the volume ratio of second ethanol to first ethanol is 1:1.

[0114] The temperature of solution A was controlled at 40°C. Solution B was slowly added to solution A and stirred. After the addition was complete, a gel was obtained. The gel was aged at room temperature for 3 days, then dried at 80°C for 15 hours, and then calcined in a muffle furnace at 470°C for 6 hours. The resulting solid was ground to obtain an intermediate.

[0115] The intermediate was impregnated with a 3.5 mol / L sodium hydroxide solution, and the impregnated product was obtained after washing and filtration, wherein the volume ratio of sodium hydroxide solution to intermediate was 1:1.

[0116] The impregnation product was mixed with 0.7g ammonium metavanadate, 6.0g ammonium tungstate, 2.0g carboxymethyl cellulose, 1.0g polyacrylamide, 1.5g guar gum powder, and water to prepare a mud with a moisture content of 35%. The pH was adjusted to 9.0, and corrugated plates were stamped out. Epoxy resin was sprayed between the corrugated plates and then stacked to obtain a corrugated plate denitrification catalyst blank. After drying, the blank was calcined at 580℃ for 7 hours to obtain the corrugated plate NH3-SCR denitrification catalyst C5. The mass of ammonium tungstate was calculated as WO3, and the mass of ammonium metavanadate was calculated as V2O5.

[0117] Catalyst C5 was cut into 3×3×12cm cylindrical pieces and loaded into the reactor. The catalyst loading amount was 108mL. The denitrification effect of the catalyst was evaluated.

[0118] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 330°C, space velocity 7000 h⁻¹. -1 NO concentration in flue gas 600 mg / Nm 3 NH3 gas concentration 550 mg / Nm 3 ;

[0119] The catalyst obtained above has a specific surface area of ​​55 m². 2 / g, NO x Conversion rate: 91.1%.

[0120] Comparative Example 1

[0121] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 330°C, space velocity 7000 h⁻¹. -1 NO concentration in flue gas 600 mg / Nm 3 NH3 gas concentration 550 mg / Nm 3 ;

[0122] The catalyst uses metal plates, glass fiber corrugated plates, and honeycomb ceramics as supports. Based on the mass of the support, the loading amounts are ZrO2 1.6%, V2O5 0.6%, WO3 3.9%, and Pr6O2 0.6%. 11 It is 0.2%;

[0123] The catalyst has a specific surface area of ​​42 m². 2 / g;NO x Conversion rate: 85.7%.

[0124] Comparative Example 2

[0125] Ammonia gas is injected into the denitrification reactor, and then flue gas is introduced into the reactor to contact the catalyst for denitrification treatment. The flue gas reaction conditions are: reaction temperature 420°C, space velocity 13000 h⁻¹. -1 The NO concentration in the flue gas was 800 mg / Nm³. 3 NH3 concentration 800 mg / Nm 3 ;

[0126] The catalyst was prepared as follows: 500g of titanium oxysulfate (calculated as TiO2) was dissolved in sulfuric acid solution to form a solution containing 35g / L TiO2. 12g of zirconium acetate solution (calculated as ZrO2) was added to an ammonium metatungstate solution (calculated as WO3). After mechanical stirring for 2 hours, ammonia was gradually added to adjust the pH to 9.5. After complete precipitation, the solution was filtered and washed. The washed material was then mixed with deionized water to form a slurry with a water content of 50%. 5g of ammonium metavanadate solution (calculated as V2O5) was added, and the mixture was stirred while ultrasonically vibrating for 1.5 hours. After direct drying, the mixture was calcined at 620℃ for 8 hours. The calcined powder was then mixed with 4.5g of ammonium molybdate solution (calculated as MoO3) to form a slurry with a water content of 30%. After stirring, 4g of urea was added, and the mixture was stirred for 40 minutes. After sealing and standing for 24 hours, the mixture was extruded into a corrugated plate shape and dried. 15g of nano-sized tungsten oxide was coated onto the slurry, and the mixture was calcined at 620℃ for 8 hours to obtain the denitrification catalyst.

[0127] The obtained catalyst has a specific surface area of ​​46 m². 2 / g, NO x Conversion rate: 96.3%.

[0128] Therefore, the flue gas denitrification method provided by the present invention uses the above-mentioned corrugated plate catalyst as a catalyst for SCR denitrification. The active components in the catalyst work together, and the catalyst has a large specific surface area, which enables ammonia to preferentially undergo catalytic reduction reaction with nitrogen oxides, thereby improving the denitrification efficiency.

[0129] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for flue gas denitrification, characterized in that, In the presence of ammonia, the flue gas is brought into contact with the corrugated plate catalyst for denitrification treatment; The corrugated plate catalyst includes a support and active components, the active components including cerium oxide, vanadium oxide, and tungsten oxide; The mass ratio of cerium oxide to the support is (5-20):100, the mass ratio of vanadium oxide to the support is (0.5-10):100, and the mass ratio of tungsten oxide to the support is (1-12):100; the support is a titanium dioxide support. The mass of cerium oxide is calculated as CeO2, the mass of vanadium oxide is calculated as V2O5, and the mass of tungsten oxide is calculated as WO3. The preparation method of the corrugated plate catalyst includes the following steps: (1) mixing titanium source and alcohol solvent to obtain solution A; then mixing cerium source, nano oxide, barrier agent and glacial acetic acid, adjusting pH to 1-5 to obtain solution B; (2) adding solution B to solution A to form a gel, and obtaining an intermediate after first drying and first calcination; (3) using an alkaline solution to dissolve the intermediate to obtain an alkaline dissolved product; (4) mixing the alkaline dissolved product, vanadium source, tungsten source, dispersant, binder, pore-forming agent and water to obtain mud; pressing the mud into corrugated sheets, stacking several corrugated sheets to obtain a catalyst blank, and obtaining a corrugated plate catalyst after second drying and second calcination.

2. The flue gas denitrification method according to claim 1, characterized in that, The molar ratio of ammonia to nitrogen oxides in the flue gas is (0.8~1.2):1, wherein the nitrogen oxides are calculated as nitrogen atoms.

3. The flue gas denitrification method according to claim 1, characterized in that, First, ammonia is injected into the denitrification reactor, and then flue gas is introduced into the denitrification reactor to contact the flue gas with the corrugated plate catalyst in the denitrification reactor.

4. The flue gas denitrification method according to claim 3, characterized in that, The temperature of the flue gas entering the denitrification reactor is 260°C to 420°C.

5. The flue gas denitrification method according to claim 1, characterized in that, The concentration of ammonia gas is 100 mg / Nm³. 3 ~1200 mg / Nm 3 .

6. The flue gas denitrification method according to claim 1, characterized in that, The volume hourly space velocity is 6000 h. -1 ~13000h -1 .

7. The flue gas denitrification method according to claim 1, characterized in that, The water content is 5%-60% of the mud content.

8. The flue gas denitrification method according to claim 1, characterized in that, Each of the corrugated sheets has a thickness of 0.2mm to 0.6mm, a crest width of 4mm to 8mm, and a crest height of 4mm to 10mm.

9. The flue gas denitrification method according to claim 1, characterized in that, The nano-oxides include at least one of nano-alumina and nano-silica.