Low-temperature denitration catalyst and preparation method thereof

Abstract

This invention discloses a low-temperature denitrification catalyst and its preparation method. The catalyst uses Mn, V, Cr, Co, Ce, and Cu as active components and corroded Al₂O₃ as a support. The active components are impregnated stepwise onto the corroded microporous support, followed by washing, drying, and calcination to form the low-temperature denitrification catalyst. The micropore volume on the surface of the microporous support accounts for 21.5%–25.4% of the total pore volume; after loading the active components, the micropore volume accounts for 17.2%–21.3% of the total pore volume of the support. The catalyst of this invention exhibits uniform distribution and synergistic effect of various active components, altering the influence of sulfur dioxide during the denitrification process, improving the competitive adsorption capacity of nitrogen oxides, and increasing the removal efficiency.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a low-temperature denitrification catalyst and its preparation method. Background Technology

[0002] With rapid economic development, the demand for fossil energy is increasing, leading to a corresponding increase in nitrogen oxide emissions. Currently, the main method for controlling NO emission concentrations both domestically and internationally is NH3-SCR technology, which utilizes tail gas purification technology to convert NO into non-toxic and harmless H2O and N2. Commonly used denitrification SCR catalysts include V2O5 / TiO2, but these catalysts operate at high ambient temperatures and have relatively short lifespans. Compared to high-temperature SCR technology, low-temperature SCR technology offers advantages such as lower flue gas velocity, longer residence time in the reaction section, reduced catalyst poisoning from SO2 after desulfurization via the SCR reactor, less ammonia slip, and lower outlet tail gas temperature.

[0003] Xu Cheng (Preparation and Performance Study of Low-Temperature Denitration Catalysts Based on Fe-Mn Transition Metal Oxides, Shandong Chemical Industry, Vol. 47, 2018) pointed out that MnO can be prepared by impregnation method. x With TiO2 catalyst, at a loading of 10% Mn-10% Fe and a reaction temperature of 160℃, the NO conversion rate reached 86%.

[0004] CN118142543A discloses a method for preparing a denitrification catalyst, which involves leaching iron-manganese slag with titanium dioxide waste acid, followed by solid-liquid separation to obtain leachate and leachate residue. The leachate is then precipitated by adding ammonia water as a precipitant. The precipitate is then extruded, dried, and calcined to obtain an Fe-Mn-based denitrification catalyst.

[0005] CN118491510A discloses a cerium-manganese composite oxide denitrification catalyst. It utilizes a hydrothermal method to enhance the catalyst's redox ability by doping with metallic manganese ions. By screening the proportion of doped manganese ions, a low-temperature NH3-SCR catalyst is obtained. In the range of 75-175℃, the NO conversion rate remains above 90%, and the nitrogen selectivity is 70%.

[0006] The above method has a low NO conversion rate during use and cannot meet emission standards. Summary of the Invention

[0007] Objective of the Invention: This invention addresses the problem of low NO conversion rates in the aforementioned methods, which fail to meet emission standards, by providing a low-temperature denitrification catalyst and its preparation method. Specifically, this invention provides a low-temperature denitrification catalyst for the reduction of NO gas emitted from combustion exhaust gases in refining, steel, and other industrial enterprises. The catalyst preparation method of this invention is simple, and the raw materials are readily available; the prepared molded catalyst has a radial crush resistance of 260-280 N / cm and exhibits structural stability. When using the catalyst of this invention for NO gas reduction, the NO conversion rate is high, and the purified flue gas can be directly emitted.

[0008] Technical solution: The objective of this invention is achieved through the following technical solution:

[0009] This invention provides a low-temperature denitrification catalyst, wherein the catalyst uses Mn, V, Cr, Co, Ce and Cu as active components and corroded Al2O3 as a support; the active components are impregnated in the corroded microporous support in steps, and after impregnation, the support is washed, dried and calcined to form the low-temperature denitrification catalyst.

[0010] The micropore volume on the surface of the multi-microporous carrier accounts for 21.5%-25.4% of the total pore volume; after loading the active component, the micropore volume accounts for 17.2%-21.3% of the total pore volume of the carrier.

[0011] The catalyst of this invention forms a multi-microporous structure through surface corrosion of the support. This abundant microporous structure enhances the adsorption and desorption of flue gas on the catalyst surface, thereby increasing the catalyst's ability to process flue gas per unit time. The synergistic effect of multiple metallic active components in the catalyst alters the influence of sulfur dioxide during the denitrification process, improves the competitive adsorption capacity of nitrogen oxides, and enhances the removal efficiency.

[0012] In a preferred embodiment of the present invention, the catalyst, based on the oxides of each element, has the following mass contents: Al₂O₃ 79%-84%; MnO₂ 3.0%-4.5%; V₂O₅ 1.5%-3.2%; CrO₂ 3.0%-3.5%; CoO₂ 2.5%-3.0%; CeO₂ 2.8%-3.5%; and CuO 2.6%-3.4%. The catalyst of the present invention exhibits a uniform distribution of various active components.

[0013] This invention also provides a method for preparing the above-mentioned low-temperature denitrification catalyst, comprising the following steps:

[0014] (1) Preparation of β-Al2O3 support;

[0015] (2) Preparation of the corroded Al2O3 support;

[0016] (3) Impregnate with Mn, Cr, Co, Ce and Cu nitrate solution of equal volume for 4-5 h, wash, dry, and program temperature to 430℃-460℃ to decompose nitrate; impregnate with V salt of equal volume for 4-5 h, wash, dry, and program temperature to 420℃-450℃ to decompose V salt, forming the low temperature denitration catalyst.

[0017] Preferably, in step (1), the β-Al2O3 support is prepared by the following method: boehmite is kneaded, sheeted and calcined at 1100-1200℃ for 4-5 hours with a programmed temperature increase of 5℃ / min to form the β-Al2O3 support.

[0018] Preferably, in step (2), the corroded Al2O3 support is prepared by the following method: the β-Al2O3 support is corroded by a sodium carbonate solution with a pH of 11-12 for 60-80 minutes to form a support with a multi-microporous surface structure.

[0019] Preferably, in step (3), the Mn, Cr, Co, Ce, and Cu nitrates are dissolved in water to form a homogeneous solution.

[0020] Preferably, in step (3), the V salt is ammonium metavanadate.

[0021] Furthermore, the ammonium metavanadate is dissolved in oxalic acid at a molar ratio of 1:2.

[0022] Preferably, in step (3), the drying temperature is 120°C and the drying time is 10-12 hours.

[0023] The present invention also provides a specific preferred embodiment in which the preparation method of the above-mentioned low-temperature denitrification catalyst includes the following steps:

[0024] (1) Boehmite is kneaded and dried to prepare alumina cakes. The alumina cakes are crushed and sieved through an 80-100 mesh sieve. The sieved particles are granulated to improve the interparticle strength. The granulated alumina particles are dried in an oven at 120℃ and then granulated by a granulator to form cylindrical catalyst particles. The temperature is increased to 1100-1200℃ at a programmed rate of 5℃ / min and calcined for 4-5 hours to form β-Al2O3 support.

[0025] (2) Prepare a sodium carbonate solution with a pH of 11-12, place the calcined β-Al2O3 in the alkaline solution, corrode for 60-80 minutes, filter and wash to form a microporous denitrification catalyst support.

[0026] (3) Weigh out the active component salts manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate, and dissolve them in deionized water to form a homogeneous solution. Weigh out ammonium metavanadate and oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution. Impregnate the active material stepwise: impregnate Mn, Cr, Co, Ce, and Cu active component nitrates in equal volumes for 4-5 hours, wash, and program the temperature to 430℃-460℃ to decompose the nitrates; impregnate V salt in equal volumes for 4-5 hours, wash, and program the temperature to 420℃-450℃ to decompose the V salt and form a catalyst.

[0027] This invention also provides the application of the above-mentioned low-temperature denitrification catalyst in NO gas reduction. The catalyst is packed into a fixed bed and reduced at 400°C with a 5% NH mixed gas for 5-6 hours, then cooled to 150-200°C. The simulated flue gas composition is: NO: 500-650 ppm, NH3: 500-600 ppm, SO2: 100 ppm, O2: 5%, and the remainder is balance gas N2; the space velocity is 5000... -1 h-6000h -1 .

[0028] Beneficial effects:

[0029] The low-temperature denitrification catalyst prepared by this invention utilizes abundant micropores to improve the adsorption and desorption of flue gas on the catalyst surface. The synergistic effect of multiple metal active components improves the denitrification efficiency, while avoiding the competitive adsorption of SO2 and NO during the denitrification process. Detailed Implementation

[0030] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0031] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0032] The catalyst strength of this invention is expressed by radial crushing pressure, according to the method in HG / T 2782-2011.

[0033] Example 1

[0034] (1) Weigh 248g of boehmite, place it in a kneader with 500ml of deionized water, knead for 30min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through an 80-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles with a granulator, and calcine them in a muffle furnace at a programmed temperature of 5℃ / min to 1100℃ for 4h to form a β-Al2O3 support.

[0035] (2) Prepare a sodium carbonate solution with pH 11, place the calcined β-Al2O3 in the alkaline solution, corrode for 80 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 23.8% of the total pore volume.

[0036] (3) Weigh out 18.2g of manganese nitrate, 19.4g of cadmium nitrate, 20.3g of cobalt nitrate, 15.8g of cerium nitrate, and 14.6g of copper nitrate, and dissolve them in 102ml of deionized water to form a homogeneous solution. Weigh out 11.2g of ammonium metavanadate and 17.2g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0037] (4) The active material was impregnated in steps with equal volumes. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 4 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 430°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrates. The catalyst was then impregnated in an ammonium metavanadate solution with equal volumes for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 430°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 20.6% of the total pore volume, and the radial crushing pressure was 264 N / cm, thus obtaining a low-temperature denitration catalyst.

[0038] The finished catalyst has the following mass contents: Al2O3 82.3%; MnO2 3.2%; V2O5 2.3%; CrO2 3.2%; CoO2 2.9%; CeO2 3.3%; CuO 2.8%.

[0039] Measure 100 ml of the above catalyst and place it in a fixed bed. Heat to 400°C and reduce with a 5% NH3 mixture for 5 hours. Cool to 200°C and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder as a balance gas N2. The space velocity is 5000. - 1The NO conversion rate can reach 96.5%. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0040] Example 2

[0041] (1) Weigh 256g of boehmite, place it in a kneader with 500ml of deionized water, knead for 30min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through a 100-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles with a granulator, and calcine them in a muffle furnace at a programmed temperature of 5℃ / min to 1150℃ for 5h to form a β-Al2O3 support.

[0042] (2) Prepare a sodium carbonate solution with pH 12, place the calcined β-Al2O3 in the alkaline solution, corrode for 60 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 22.4% of the total pore volume.

[0043] (3) Weigh 19.2g of manganese nitrate, 19.6g of cadmium nitrate, 19.3g of cobalt nitrate, 16.5g of cerium nitrate, and 15.4g of copper nitrate, and dissolve them in 104ml of deionized water to form a homogeneous solution. Weigh 12.2g of ammonium metavanadate and 18.9g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0044] (4) The active material was impregnated in equal volumes in steps. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 4 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrates. The catalyst was then impregnated in an ammonium metavanadate solution at an equal volume for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 19.6% of the total pore volume, and the radial crushing pressure was 269 N / cm, thus obtaining a low-temperature denitration catalyst.

[0045] The finished catalyst has the following mass contents: Al2O3 82.7%; MnO2 3.2%; V2O5 2.5%; CrO2 3.1%; CoO2 2.6%; CeO2 3.1%; CuO 2.8%.

[0046] Measure 100 ml of the above catalyst, place it in a fixed bed, heat to 400℃, reduce with a 5% NH mixed gas for 6 hours, cool to 160℃, and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder is balance gas N2; space velocity is 5000 - 1 The NO conversion rate can reach 97.2%. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0047] Example 3

[0048] (1) Weigh 264g of boehmite, place it in a kneader with 500ml of deionized water, knead for 45min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through a 100-mesh sieve, granulate the sieved particles to improve the interparticle strength, dry the granulated alumina particles in a 120℃ oven for 5h, and then granulate them into 4mm*4mm cylindrical catalyst particles using a granulator. Then, calcine them in a muffle furnace at a temperature of 5℃ / min to 1200℃ for 5h to form a β-Al2O3 support.

[0049] (2) Prepare a sodium carbonate solution with pH 12, place the calcined β-Al2O3 in the alkaline solution, corrode for 70 min, filter and wash to form a β-Al2O3 carrier with micropore volume accounting for 21.5% of the total pore volume.

[0050] (3) Weigh 16.2g of manganese nitrate, 18.6g of cadmium nitrate, 20.6g of cobalt nitrate, 18.8g of cerium nitrate, and 19.5g of copper nitrate, and dissolve them in 104ml of deionized water to form a homogeneous solution. Weigh 15.3g of ammonium metavanadate and 23.7g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0051] (4) The active material was impregnated in equal volumes in steps. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 4 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrate. The catalyst was then impregnated in an ammonium metavanadate solution at an equal volume for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 18.5% of the total pore volume, and the radial crushing pressure was 263 N / cm, thus obtaining a low-temperature denitration catalyst.

[0052] The finished catalyst has the following mass contents: Al2O3 79.2%; MnO2 4.5%; V2O5 3.2%; CrO2 3.5%; CoO2 3.0%; CeO2 3.4%; and CuO 3.2%.

[0053] Measure 100 ml of the above catalyst and place it in a fixed bed. Heat to 400°C and reduce with a 5% NH3 mixture for 5 hours. Cool to 150°C and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder N2 as a balance gas. The space velocity is 6000. - 1 The NO conversion rate can reach 96.4%. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0054] Example 4

[0055] (1) Weigh 235g of boehmite, place it in a kneader with 500ml of deionized water, knead for 40min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through an 80-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles using a granulator, and calcine them in a muffle furnace at a temperature of 5℃ / min to 1100℃ for 4h to form a β-Al2O3 support.

[0056] (2) Prepare a sodium carbonate solution with pH 12, place the calcined β-Al2O3 in the alkaline solution, corrode for 60 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 21.8% of the total pore volume.

[0057] (3) Weigh 15.2g of manganese nitrate, 14.6g of cadmium nitrate, 18.6g of cobalt nitrate, 16.8g of cerium nitrate, and 17.5g of copper nitrate, and dissolve them in 110ml of deionized water to form a homogeneous solution. Weigh 15.6g of ammonium metavanadate and 24.2g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0058] (4) The active material was impregnated in steps with equal volumes. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 5 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 460°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrates. The catalyst was then impregnated in an ammonium metavanadate solution with equal volumes for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 19.3% of the total pore volume, and the radial crushing pressure was 269 N / cm, thus obtaining a low-temperature denitration catalyst.

[0059] The finished catalyst has the following mass contents: Al2O3 83.0%; MnO2 3.0%; V2O5 2.3%; CrO2 3.0%; CoO2 2.5%; CeO2 2.8%; CuO 3.4%.

[0060] Measure 100 ml of the above catalyst and place it in a fixed bed. Heat to 400°C and reduce with a 5% NH3 mixture for 6 hours. Cool to 160°C and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder N2 as a balance gas. The space velocity is 5500. - 1 The NO conversion rate can reach 96.3%. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0061] Example 5

[0062] (1) Weigh 372g of boehmite, place it in a kneader with 500ml of deionized water, knead for 50min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through a 100-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles with a granulator, and calcine them in a muffle furnace at a temperature of 5℃ / min to 1200℃ for 5h to form a β-Al2O3 support.

[0063] (2) Prepare a sodium carbonate solution with pH 12, place the calcined β-Al2O3 in the alkaline solution, corrode for 80 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 21.5% of the total pore volume.

[0064] (3) Weigh 19.2g of manganese nitrate, 20.4g of cadmium nitrate, 19.6g of cobalt nitrate, 21.3g of cerium nitrate, and 18.5g of copper nitrate, and dissolve them in 118ml of deionized water to form a homogeneous solution. Weigh 18.2g of ammonium metavanadate and 28.2g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0065] (4) The active material was impregnated in steps with equal volumes. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 5 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrates. The catalyst was then impregnated in an ammonium metavanadate solution with equal volumes for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 420°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 18.5% of the total pore volume, and the radial crushing pressure was 280 N / cm, thus obtaining a low-temperature denitration catalyst.

[0066] The finished catalyst has the following mass contents: Al2O3 81.8%; MnO2 3.6%; V2O5 1.8%; CrO2 3.3%; CoO2 2.6%; CeO2 3.5%; and CuO 3.4%.

[0067] Measure 100 ml of the above catalyst, place it in a fixed bed, heat to 400℃, reduce with a 5% NH mixed gas for 5 h, cool to 170℃, and introduce NO: 600 ppm, NH3: 600 ppm, SO2: 100 ppm, 5% O2, and the remainder is balance gas N2; space velocity is 6000 - 1 The NO conversion rate can reach 96.1% in h. After flue gas purification, the concentration of nitrogen oxides is less than 50 ppm.

[0068] Example 6

[0069] (1) Weigh 228g of boehmite, place it in a kneader with 500ml of deionized water, knead for 30min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through an 80-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles using a granulator, and calcine them in a muffle furnace at a temperature of 5℃ / min to 1200℃ for 4h to form a β-Al2O3 support.

[0070] (2) Prepare a sodium carbonate solution with pH 11, place the calcined β-Al2O3 in the alkaline solution, corrode for 60 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 22.4% of the total pore volume.

[0071] (3) Weigh 15.3g of manganese nitrate, 17.6g of cadmium nitrate, 18.7g of cobalt nitrate, 16.8g of cerium nitrate, and 17.2g of copper nitrate, and dissolve them in 104ml of deionized water to form a homogeneous solution. Weigh 15.5g of ammonium metavanadate and 24.1g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0072] (4) The active material was impregnated in steps with equal volumes. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 4 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 430°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrates. The catalyst was then impregnated in an ammonium metavanadate solution with equal volumes for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 420°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 20.2% of the total pore volume, and the radial crushing pressure was 268 N / cm, thus obtaining a low-temperature denitration catalyst.

[0073] The finished catalyst has the following mass contents: Al2O3 82.2%; MnO2 4.5%; V2O5 1.5%; CrO2 3.2%; CoO2 2.8%; CeO2 2.9%; CuO 2.9%.

[0074] Measure 100 ml of the above catalyst, place it in a fixed bed, heat to 400℃, reduce with a 5% NH mixed gas for 6 hours, cool to 150℃, and introduce NO: 600 ppm, NH3: 600 ppm, SO2: 100 ppm, 5% O2, and the remainder is balance gas N2; the space velocity is 6000. - 1 The NO conversion rate can reach 96.3%. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0075] Example 7

[0076] (1) Weigh 247g of boehmite, place it in a kneader with 500ml of deionized water, knead for 40min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through an 80-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles with a granulator, and calcine them in a muffle furnace at a temperature of 5℃ / min to 1100℃ for 4h to form a β-Al2O3 support.

[0077] (2) Prepare a sodium carbonate solution with pH 12, place the calcined β-Al2O3 in the alkaline solution, corrode for 80 min, filter and wash to form a β-Al2O3 support with micropore volume accounting for 25.4% of the total pore volume.

[0078] (3) Weigh out 17.8g of manganese nitrate, 18.2g of cadmium nitrate, 19.3g of cobalt nitrate, 17.3g of cerium nitrate, and 25.6g of copper nitrate, and dissolve them in 103ml of deionized water to form a homogeneous solution. Weigh out 16.5g of ammonium metavanadate and 25.6g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0079] (4) The active material was impregnated in equal volumes in steps. After corrosion, β-Al2O3 was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 5 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 460°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the nitrate. The catalyst was then impregnated in an ammonium metavanadate solution at an equal volume for 5 hours, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then cooled naturally to decompose the ammonium metavanadate. The micropore volume accounted for 21.3% of the total pore volume, and the radial crushing pressure was 260 N / cm, thus obtaining a low-temperature denitration catalyst.

[0080] The finished catalyst has the following mass contents: Al2O3 81.3%; MnO2 4.1%; V2O5 2.8%; CrO2 3.2%; CoO2 2.7%; CeO2 3.2%; CuO 2.7%.

[0081] Measure 100 ml of the above catalyst, place it in a fixed bed, heat to 400℃, reduce with a 5% NH mixed gas for 6 hours, cool to 150℃, and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder is balance gas N2; space velocity is 6000 - 1The NO conversion rate can reach 96.6% in h. After flue gas purification, the nitrogen oxide concentration is less than 50 ppm.

[0082] Comparative Example 1

[0083] (1) Weigh 248g of boehmite, place it in a kneader with 500ml of deionized water, knead for 30min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cakes. Crush the alumina cakes with a pulverizer, pass them through an 80-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles using a granulator, and calcine them in a muffle furnace at a programmed temperature of 5℃ / min to 1100℃ for 4h to form a β-Al2O3 support. A β-Al2O3 support with a micropore volume accounting for 16.3% of the total pore volume is formed.

[0084] (2) Weigh out 18.2g of manganese nitrate, 19.4g of cadmium nitrate, 20.3g of cobalt nitrate, 15.8g of cerium nitrate, and 14.6g of copper nitrate, and dissolve them in 102ml of deionized water to form a homogeneous solution. Weigh out 11.2g of ammonium metavanadate and 17.2g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0085] (3) Stepwise equal-volume impregnation of active materials: The β-Al2O3 support was placed in a solution of manganese nitrate, cadmium nitrate, cobalt nitrate, cerium nitrate, and copper nitrate for 4 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 430°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then naturally cooled to decompose nitrates. The catalyst was then impregnated in an equal-volume ammonia solution of metavanadate for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 430°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and then naturally cooled to decompose the ammonia solution of metavanadate. The micropore volume accounted for 13.2% of the total pore volume, and the radial crushing pressure was 263 N / cm, thus obtaining the catalyst.

[0086] Measure 100 ml of the above catalyst and place it in a fixed bed. Heat to 400°C and reduce with a 5% NH3 mixture for 5 hours. Cool to 200°C and introduce NO: 500 ppm, NH3: 500 ppm, SO2: 100 ppm, 5% O2, and the remainder as a balance gas N2. The space velocity is 5000. - 1 h, the NO conversion rate can reach 79.5%.

[0087] Comparative Example 2

[0088] (1) Weigh 372g of boehmite, place it in a kneader with 500ml of deionized water, knead for 50min, remove the kneaded mixture, let it stand for 60min, remove the supernatant, and dry it in a 120℃ oven for 12h to prepare alumina cake. Crush the alumina cake with a pulverizer, pass it through a 100-mesh sieve, granulate the sieved particles to improve the interparticle strength, and dry the granulated alumina particles in a 120℃ oven for 5h. After drying, granulate them into 4mm*4mm cylindrical catalyst particles with a granulator, and calcine them in a muffle furnace at a temperature of 5℃ / min to 1200℃ for 5h to form a β-Al2O3 support.

[0089] (2) Weigh 22.3g of manganese nitrate, 25.4g of cadmium nitrate, and 18.5g of copper nitrate, and dissolve them in 105ml of deionized water to form a homogeneous solution. Weigh 18.2g of ammonium metavanadate and 28.2g of oxalic acid in a molar ratio of 1:2, and dissolve them to form a homogeneous ammonium metavanadate solution.

[0090] (3) Stepwise equal-volume impregnation of active materials: The β-Al2O3 support was placed in a solution of manganese nitrate, cadmium nitrate, and copper nitrate for 5 hours. The impregnated catalyst was removed, washed, dried in an oven at 120°C for 5 hours, heated to 450°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and allowed to cool naturally to decompose nitrates; the catalyst was then impregnated in an equal-volume ammonium meta-alum solution for 4 hours, washed, dried in an oven at 120°C for 5 hours, heated to 420°C in a muffle furnace at a programmed temperature of 5°C / min, held for 5 hours, and allowed to cool naturally to decompose ammonium meta-alum to obtain the catalyst.

[0091] Measure 100 ml of the above catalyst, place it in a fixed bed, heat to 400℃, reduce with a 5% NH mixed gas for 5 h, cool to 170℃, and introduce NO: 600 ppm, NH3: 600 ppm, SO2: 100 ppm, 5% O2, and the remainder is balance gas N2; space velocity is 6000 - 1 h, the NO conversion rate can reach 75.8%.

[0092] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A low-temperature denitrification catalyst, characterized in that, The catalyst uses Mn, V, Cr, Co, Ce, and Cu as active components and corroded Al2O3 as a support. The active components are impregnated in the corroded microporous support in steps, and then washed, dried, and calcined to form the low-temperature denitrification catalyst. The micropore volume on the surface of the multi-microporous carrier accounts for 21.5%-25.4% of the total pore volume; after loading the active component, the micropore volume accounts for 17.2%-21.3% of the total pore volume of the carrier.

2. The low-temperature denitrification catalyst according to claim 1, characterized in that, Based on the oxides of each element, the mass content of Al2O3 is 79%-84%; the mass content of MnO2 is 3.0%-4.5%; the mass content of V2O5 is 1.5%-3.2%; the mass content of CrO2 is 3.0%-3.5%; the mass content of CoO2 is 2.5%-3.0%; the mass content of CeO2 is 2.8%-3.5%; and the mass content of CuO is 2.6%-3.4%.

3. A method for preparing the low-temperature denitrification catalyst according to claim 1 or 2, characterized in that, Includes the following steps: (1) Preparation of β-Al2O3 support; (2) Preparation of the corroded Al2O3 support; (3) Impregnate with Mn, Cr, Co, Ce and Cu nitrate solution of equal volume for 4-5 h, wash, dry, and program temperature to 430℃-460℃ to decompose nitrate; impregnate with V salt of equal volume for 4-5 h, wash, dry, and program temperature to 420℃-450℃ to decompose V salt, forming the low temperature denitration catalyst.

4. The preparation method according to claim 3, characterized in that, In step (1), the β-Al2O3 support is prepared by the following method: boehmite is kneaded, sheeted and calcined at 1100-1200℃ for 4-5 hours with a programmed temperature increase of 5℃ / min to form the β-Al2O3 support.

5. The preparation method according to claim 3, characterized in that, In step (2), the corroded Al2O3 support is prepared by the following method: the β-Al2O3 support is corroded in sodium carbonate solution with pH 11-12 for 60-80 minutes to form a support with a multi-microporous surface structure.

6. The preparation method according to claim 3, characterized in that, In step (3), the Mn, Cr, Co, Ce and Cu nitrates are dissolved in water to form a homogeneous solution.

7. The preparation method according to claim 3, characterized in that, In step (3), the V salt is ammonium metavanadate.

8. The preparation method according to claim 7, characterized in that, The ammonium metavanadate is dissolved in oxalic acid at a molar ratio of 1:

2.

9. The preparation method according to claim 3, characterized in that, In step (3), the drying temperature is 120°C and the drying time is 10-12 hours.

10. The application of the low-temperature denitrification catalyst according to claim 1 or 2 in the reduction of NO gas, characterized in that, The catalyst was loaded into a fixed bed and reduced at 400℃ with a 5% NH mixed gas for 5-6 hours, then cooled to 150-200℃. The simulated flue gas composition was: NO: 500-650 ppm, NH3: 500-600 ppm, SO2: 100 ppm, O2: 5%, and the remainder being the balance gas N2; the space velocity was 5000. -1 h-6000h -1 .