Denitration catalyst preparation method, denitration catalyst and application thereof

Abstract

The present invention relates to the field of air pollution prevention and control materials in energy-saving and environmental protection industries, and in particular to a method for preparing a denitration catalyst, a denitration catalyst and its application. The method for preparing a denitration catalyst of the present invention comprises: a batching step: a mixture of powders of manganese ore and binder; a kneading step: adding water to the mixture and kneading; a molding step: molding the kneaded material to obtain a catalyst precursor; an activation step: activating the catalyst precursor in an activation environment to obtain a denitration catalyst, wherein, in the activation environment, the activation temperature is greater than 200°C, the molar ratio of oxygen in the activation atmosphere is greater than 10%, and the molar ratio of water vapor is greater than 20%. In the present invention, in the activation atmosphere with water vapor, the increase in oxygen content is conducive to the decomposition of crystal phases such as MnCO3 in rhodochrosite, and at the same time promotes the conversion of α-MnO2 and γ-MnO2 into β-MnO2, which promotes the increase in the number of active phases of the denitration reaction.

Description

Technical Field

[0001] The present invention relates to the field of air pollution prevention and control materials in energy-saving and environmental protection industries, and in particular to a denitration catalyst preparation method, a denitration catalyst and applications thereof. Background Art

[0002] The selective catalytic reduction technology (NH3-SCR) with NH3 or urea as the reducing agent is currently the most widely used flue gas denitrification technology. Its core is the catalyst, which can directly affect the overall denitrification efficiency and stability. The industrial catalyst is mainly a vanadium-titanium catalyst with anatase-type titanium dioxide loaded with vanadium pentoxide and other additives. Its reaction temperature is 220-420℃ and is widely used in medium and high temperature denitrification systems such as coal-fired power plants.

[0003] For non-power industries such as steel, coke, cement, glass, ceramics, electrolytic aluminum and other industries with low flue gas emission temperature (<180℃), traditional vanadium-titanium catalysts are difficult to meet the requirements due to high operating temperature, narrow use temperature window, and the active component vanadium has strong biological toxicity and may cause secondary pollution. It is necessary to develop new low-temperature NH3-SCR denitrification catalysts. Manganese-based catalysts have attracted more and more attention from researchers at home and abroad due to their good low-temperature denitrification activity, and are expected to replace vanadium-based catalysts in the field of low-temperature denitrification.

[0004] In the process of realizing the present invention, the applicant discovered that the conversion rate of manganese ore into active Mn element in the existing manganese-based denitration catalyst preparation process is low, resulting in low catalytic efficiency. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The present invention is expected to at least partially solve one of the above technical problems.

[0007] (II) Technical solution

[0008] The first aspect of the present invention provides a method for preparing a denitration catalyst, comprising:

[0009] Batching steps: preparing a mixture of manganese ore and binder powders;

[0010] Kneading step: adding water to the mixed material and kneading;

[0011] Molding step: molding the kneaded material to obtain a catalyst precursor;

[0012] Activation step: activating the catalyst precursor in an activation environment to obtain a denitration catalyst, wherein in the activation environment, the activation temperature is greater than 200° C., the molar proportion of oxygen in the activation atmosphere is greater than 10%, and the molar proportion of water vapor is greater than 20%.

[0013] In some embodiments of the present invention, in the activation step, the molar ratio of oxygen in the activation atmosphere is between 10% and 50%, and the molar ratio of water vapor is between 20% and 70%.

[0014] In a preferred embodiment of the present invention, the molar proportion of oxygen in the activation atmosphere is 40%, and the molar proportion of water vapor is 50%.

[0015] In some embodiments of the present invention, the activation step includes: a first activation sub-step: activation at a first activation temperature and an activation atmosphere, wherein the first activation temperature is between 200-280°C, and the activation time is between 2 and 12 hours; a second activation sub-step: activation at a second activation temperature and an activation atmosphere, wherein the second activation temperature is between 300-600°C, and the activation time is between 3 and 8 hours.

[0016] In some embodiments of the present invention, the activation step also includes: a preheating sub-step before the first activation step: heating the catalyst precursor to 120°C at a heating rate of 2 to 3°C / min and maintaining it for 10 to 60 minutes; the first activation sub-step includes: introducing an activation gas to obtain an activation atmosphere, heating the temperature to 200-280°C at a heating rate of 1 to 2°C / min, and maintaining it for 2 to 12 hours; the second activation sub-step includes: heating the temperature to 300-600°C at a heating rate of 1 to 2°C / min, and maintaining it for 3 to 8 hours, during which the activation atmosphere remains unchanged; after the second activation step, it also includes: a cooling sub-step, changing the activation atmosphere to a nitrogen atmosphere, cooling it to below 200°C, and then changing it to an air atmosphere, cooling it to below 50°C, to obtain a denitration catalyst.

[0017] In some embodiments of the present invention, before or during the kneading step, a mixing step is further included to mix the mixed materials uniformly.

[0018] In some embodiments of the present invention, after the kneading step and before the forming step, the following further comprises: an aging step: aging the kneaded material.

[0019] In some embodiments of the present invention, after the shaping step and before the activation step, the method further includes: drying the catalyst precursor at a temperature of 40-120° C. for 12-24 hours.

[0020] In some embodiments of the present invention, in the batching step, a mixture of powders of manganese ore, binder, and soluble metal salt is prepared; the soluble metal salt is a salt corresponding to one or more of the following metals: Ce, Cu, Zn, La, Fe, Co, and W.

[0021] In some embodiments of the present invention, in the batching step, the soluble metal salts are cerium nitrate and ferric nitrate, and the molar amount of the cerium nitrate and ferric nitrate are both between 0.1% and 5% of the molar amount of manganese in the mixed material.

[0022] In some embodiments of the present invention, in the batching step, the manganese ore includes: more than 50wt% of the main category of rhodochrosite; more than 30wt% of pyrolusite; the rest is hausmannite; wherein the main category of rhodochrosite includes one or more of the following: rhodochrosite, ferroxhose ore, and smithsonite.

[0023] In some embodiments of the present invention, in the batching step, the binder is one or more of the following materials: pseudo-boehmite, sesbania powder, carboxymethyl cellulose, polyethylene glycol, and its content is less than or equal to 20wt% of the manganese ore.

[0024] The second aspect of the present invention provides a denitration catalyst prepared by the above denitration catalyst preparation method.

[0025] The third aspect of the present invention provides an application of the above denitration catalyst in the denitration of low-temperature flue gas, wherein the low-temperature flue gas is industrial flue gas with a temperature between 100 and 180° C. and a water content of less than 15%.

[0026] (III) Beneficial effects

[0027] It can be seen from the above technical solution that the present invention has at least one of the following beneficial effects compared with the prior art:

[0028] (1) In the activation atmosphere with water vapor, the increase of O2 content has a significant effect on the catalyst performance. This may be because O2 has an important influence on the crystal transformation of rhodochrosite and pyrolusite. The increase of oxygen content is conducive to the decomposition of crystal phases such as MnCO3 in rhodochrosite, and at the same time promotes the conversion of α-MnO2 and γ-MnO2 into β-MnO2, which promotes the increase of the number of active phases in the denitrification reaction. At the same time, water vapor and O2 are conducive to the crystal transformation of pyrolusite.

[0029] (2) By adjusting the ratio of different types of manganese ores and modifying the metal additives of cerium nitrate and / or ferric nitrate, the N2 selectivity and water resistance of the catalyst in the denitrification process are improved. The catalyst has stable denitrification performance for flue gas with a high water content of 100-180°C.

[0030] (3) Using low-grade natural manganese ore resources, a denitrification catalyst with good low-temperature performance and water and sulfur resistance was prepared through a simple activation method. At the same time, by matching the proportions of different types of manganese ores, a good balance can be achieved in the three indicators of NO conversion rate, N2 selectivity, and catalyst strength, which is suitable for most application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flowchart of a method for preparing a denitration catalyst according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The characteristic of the present invention is that natural ore is used as the basic raw material, and the natural manganese ore is modified through a specific roasting activation procedure and doping with metal salts, so that the doped metal and the natural manganese ore generate composite metal oxides in situ, so that the catalyst has good denitrification activity, high N2 selectivity and water and sulfur resistance.

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and with reference to the accompanying drawings.

[0034] A first aspect of the present invention provides a method for preparing a denitration catalyst. Figure 1 Flow chart of the method for preparing a denitration catalyst according to an embodiment of the present invention. Figure 1 As shown, the method for preparing the denitration catalyst in this embodiment includes:

[0035] Batching steps: weighing manganese ore powder, soluble metal salt, binder and other materials;

[0036] Mixing step: mixing the above materials evenly in a kneader;

[0037] Mixing step: add appropriate amount of deionized water to the above mixture and mix for 10-120 minutes;

[0038] Aging step: After kneading, place for 120-720 minutes for aging;

[0039] Molding step: transferring the aged material into an extruder for extrusion molding, and the shape thereof can be one of strip, clover, four-leaf clover, and honeycomb;

[0040] Drying step: drying the catalyst precursor obtained after extrusion at a temperature of 40-120° C. for 12-24 hours;

[0041] Activation step: placing the catalyst precursor into an atmosphere calcining furnace, introducing a mixed gas for programmed temperature activation, and obtaining an ultra-low temperature denitrification catalyst with certain water and sulfur resistance after activation.

[0042] In the batching step, the manganese ore includes: rhodochrosite, pyrolusite, and hausmannite. Among them, the mass of rhodochrosite accounts for more than 50wt% of the total mass of the three, the mass of pyrolusite accounts for more than 30wt%, and the rest is hausmannite. Among various manganese ores, the manganese content in rhodochrosite is 10-45wt%, the manganese content in pyrolusite is 10-60wt%, and the manganese content in hausmannite is 10-65wt%. Among them, rhodochrosite can be replaced by other ores in the rhodochrosite category such as iron rhodochrosite and zinc manganese.

[0043] In this embodiment, a denitration catalyst having good low-temperature performance and water and sulfur resistance is prepared by a simple activation method using low-grade natural manganese ore resources.

[0044] Of course, those skilled in the art can also adjust the proportion of manganese ore according to actual work needs, or use one of the manganese ores. Although the effect is slightly worse than that of this embodiment, the present invention can also be implemented and is also within the protection scope of the present invention.

[0045] In the batching step, the soluble metal salt is one or more of Ce, Cu, Zn, La, Fe, Co, and W, and its amount is 0.1-5% of the molar amount of manganese in the manganese ore. Preferably, the soluble metal salt is cerium nitrate and / or iron nitrate.

[0046] In the present invention, the N2 selectivity and water resistance of the catalyst in the denitration process are improved by adjusting the ratio of different types of manganese ores and modifying the metal additives of cerium nitrate and / or ferric nitrate. The catalyst has a stable denitration performance for flue gas with a high water content of 100-180°C.

[0047] In the batching step, the amount of binder is ≤ 20wt% of the manganese ore, and the binder is one or a mixture of pseudo-boehmite, sesbania powder, carboxymethyl cellulose, and polyethylene glycol. The above manganese ore and binder are all 300 mesh powders. Of course, those skilled in the art can also use other binders known in the art.

[0048] In the activation step, the mixed gas used is composed of air, oxygen, nitrogen and water vapor. At different stages in the activation step, the mixed gas is obtained in the mixing tank in front of the atmosphere roasting furnace by adjusting the ratio of air, oxygen, nitrogen and water vapor to activate the catalyst. Among them, the activation temperature, the water vapor content and the oxygen content in the activation atmosphere are the most important process parameters. Generally, the activation temperature is greater than 200°C, the molar ratio of oxygen in the activation atmosphere is greater than 10%, and the molar ratio of water vapor is greater than 20%. Preferably, the molar ratio of oxygen in the activation atmosphere is between 10 and 50%, and the molar ratio of water vapor is between 20-70%. More preferably, the molar ratio of oxygen in the activation atmosphere is 40%, and the molar ratio of water vapor is 50%.

[0049] In an embodiment of the present invention, the activation step comprises:

[0050] Preheating sub-step: heating the catalyst precursor to 120° C. at a heating rate of 2 to 3° C. / min in an air atmosphere and maintaining the temperature for 30 minutes;

[0051] First activation sub-step: then start to introduce activation gas with an oxygen content of 10-50% and a water vapor content of 20-70%, raise the temperature to 200-280°C at a heating rate of 1-2°C / min, and maintain for 2-12 hours;

[0052] Second activation sub-step: then the temperature is raised to a second temperature point at the same rate as the first activation sub-step, the temperature point is between 300-600°C, the activation gas composition is 10-50% oxygen content, 20-70% water vapor, activation is performed at this temperature for 3-8 hours, and activation is completed;

[0053] Cooling sub-step: the gas is switched to nitrogen, and the temperature is lowered to 110°C under nitrogen purge, and then further lowered to 50°C under air purge and the catalyst is taken out.

[0054] In the present invention, in the activation atmosphere with water vapor, the increase of O2 content has a significant promotion on the catalyst performance. This may be because O2 has an important influence on the crystal transformation of rhodochrosite and pyrolusite. The increase of oxygen content is conducive to the decomposition of crystal phases such as MnCO3 in rhodochrosite, and at the same time promotes the conversion of α-MnO2 and γ-MnO2 into β-MnO2, which promotes the increase in the number of active phases of the denitration reaction. At the same time, water vapor and O2 are conducive to the crystal transformation of pyrolusite.

[0055] In this embodiment, in order to ensure the effect of the later catalyst, a mixing step, an aging step, a drying step, etc. are included, but the present invention is not limited thereto. In other embodiments of the present invention, these steps can be omitted, or the mixing step can be integrated into the kneading step, the aging step can be integrated into the kneading step, and the drying step can be integrated into the activation step. Although the effect of preparing the denitration catalyst may be slightly inferior to that of this embodiment, the present invention can be at least partially realized and is also within the protection scope of the present invention.

[0056] The present invention is described in detail below in conjunction with specific sequence experiments.

[0057] Sequence experiment 1: Denitrification performance of manganese ore composition after roasting in air

[0058] The following first introduces the preparation of each sample in this sequence experiment. For any incomplete information, please refer to the previous complete preparation method.

[0059] In the batching step, six samples of rhodochrosite, pyrolusite, hausmannite and a mixture of two of them in equal proportions with a manganese content of about 20% are weighed respectively; and pseudo-boehmite is weighed in an amount of 10wt% for each sample.

[0060] In the mixing step, the above materials were mixed in a kneader for 10 minutes.

[0061] In the kneading step, an appropriate amount of deionized water was added to the mixed sample and kneaded for 30 minutes.

[0062] In the aging step, the mixture is left to age for 120 minutes after the kneading is completed.

[0063] In the extrusion step, the aged material is transferred to an extruder and extruded into 6 mm strips.

[0064] In the drying step, the catalyst precursor obtained after extrusion was dried at a temperature of 120° C. for 8 h.

[0065] In the activation step, the catalyst precursor is placed in an atmosphere calcining furnace and air is introduced for programmed temperature activation. The activation process is as follows: the catalyst precursor is heated to 120°C at a heating rate of 5°C / min in an air atmosphere and maintained for 30 minutes, then heated to 250°C at a heating rate of 2°C / min and maintained for 2 hours; then heated to 500°C at the same heating rate, activated at this temperature for 3 hours, and the activation is completed; the gas is switched to nitrogen, and the temperature is lowered to 110°C under nitrogen purge, and then further lowered to 50°C under air purge and the denitration catalyst is taken out.

[0066] Table 1 Comparison of NO conversion rates of denitrification catalysts prepared with different manganese ore compositions

[0067] T / ℃ Pyrolusite Rhodochrosite Halotrichite Soft-Diamond Soft-Black Diamond-Black 100 67 33 10 59 51 21 120 82 42 17 68 61 33 150 100 57 33 87 83 49 180 100 65 49 99 95 57 200 100 75 55 100 100 63

[0068] Table 2 Comparison of N2 selectivity of denitrification catalysts prepared with different manganese ore compositions

[0069] T / ℃ Pyrolusite Rhodochrosite Halotrichite Soft-Diamond Soft-Black Diamond-Black 100 95 98 100 95 97.5 99 120 89 95 98 90 93.5 96.5 150 79 89 97 85 88 93 180 63 77 95 73 79 86 200 36 56 94 66 71 75

[0070] The calculation formulas for NO conversion and N2 selectivity in Tables 1 and 2 and subsequent experiments are as follows:

[0071] NO conversion rate:

[0072] NO Con. =[(c(NO) in -c(NO) out ) / c(NO) in ]×100%

[0073] N2 selectivity:

[0074] N 2Sel. =[1-2×c(N2O) out / (c(NO) in -c(NO) out )]×100%

[0075] Where:

[0076] NO Con. : NO conversion rate

[0077] N 2Sel. :N2 selectivity

[0078] c(NO) in : Inlet NO concentration

[0079] c(NO) out : Outlet NO concentration

[0080] c(N2O) out : Outlet N2O concentration

[0081] The above-mentioned denitration catalysts were evaluated for performance under the conditions of 100ppmNO, 105ppmNH3, 8%O2, 8%CO2, 10ppmSO2, residual gas N2, and air velocity 2000h-1, and the results are shown in Tables 1 and 2. Among the six catalysts, pyrolusite has the best low-temperature performance, with a NO conversion rate of 100% above 150°C, but its N2 selectivity is the worst and decreases fastest with increasing temperature; hausmannite has a low NO conversion rate, but the best N2 selectivity. After the three are mixed in pairs, the catalyst mixed with pyrolusite has a higher NO conversion rate, while the catalyst mixed with hausmannite has a better N2 selectivity.

[0082] At the same time, considering that rhodochrosite has the lowest strength. During the use of the catalyst, higher strength can ensure a small pressure drop in the catalyst bed and low dust at the outlet. Therefore, the present invention selects manganese ore including: more than 50wt% of rhodochrosite; more than 30wt% of pyrolusite; the rest is ferromanganese ore. In this case, it can ensure a good balance in the three indicators of NO conversion rate, N2 selectivity, and catalyst strength, which is suitable for most application scenarios.

[0083] Sequence experiment 2: Effect of oxygen content in activated atmosphere on denitrification performance

[0084] The following first introduces the preparation of each sample in this sequence experiment. For any incomplete information, please refer to the previous complete preparation method.

[0085] In the batching step, rhodochrosite, pyrolusite and hausmannite with a manganese content of about 20% are weighed respectively and mixed in a ratio of 1:1:1; pseudo-boehmite is weighed as a binder in an amount of 10wt% of the total mass of the manganese ore.

[0086] In the mixing step, the above materials were mixed in a kneader for 10 minutes.

[0087] In the kneading step, an appropriate amount of deionized water was added to the mixed sample and kneaded for 30 minutes.

[0088] In the aging step, the mixture is left to age for 120 minutes after the kneading is completed.

[0089] In the forming step, the aged material is transferred to an extruder and extruded into 6 mm strips.

[0090] In the drying step, the catalyst precursor obtained after extrusion was dried at a temperature of 120° C. for 8 h.

[0091] In the activation step, the catalyst precursor is divided into 5 parts, which are placed in an atmosphere calcining furnace respectively, and a mixed gas is introduced for programmed temperature activation. The activation process is as follows: the catalyst precursor is heated to 120°C at a heating rate of 5°C / min in an air atmosphere and maintained for 30 minutes, and then an activation atmosphere with different oxygen contents is introduced, as shown in Table 3, and the temperature is raised to 250°C at a heating rate of 2°C / min and maintained for 2 hours; then the temperature is raised to 500°C at the same heating rate, and activated at this temperature for 3 hours, and the activation is completed; the gas is switched to nitrogen, and the temperature is lowered to 110°C under nitrogen purge, and then the temperature is further lowered to 50°C under air purge and the catalyst is taken out. The water vapor content of each catalyst during the activation process is 50%, and the O2 content is 0%, ~10%, ~20%, 40%, and 50%, respectively. The activated catalysts are named S1-S5.

[0092] Table 3 Composition of different activation atmospheres

[0093] catalyst Activation atmosphere composition water vapor / % <![CDATA[O2 / %]]> S1 <![CDATA[50% N2 + 50% water vapor]]> 50 0 S2 50% air + 50% water vapor 50 ～10 S3 <![CDATA[38% air + 12% O2 + 50% water vapor]]> 50 ～20 S4 <![CDATA[12% air + 38% O2 + 50% water vapor]]> 50 40 S5 <![CDATA[50% O2 + 50% water vapor]]> 50 50

[0094] The above catalyst was heated in 100ppmNO, 105ppmNH3, 5%H2O(g), 8%O2, 8%CO2, 10ppmSO2, the remaining gas was N2, and the space velocity was 2000h -1 The performance evaluation was carried out under the conditions of , and the results are shown in Table 4 and Table 5.

[0095] After being treated with activation atmospheres with different oxygen contents, the NO conversion rate of the catalyst was the lowest under oxygen-free conditions. With the increase of oxygen content, the NO conversion rate first increased significantly and then stabilized. When the oxygen content reached 40%, the NO conversion rate of the catalyst reached the highest, continued to rise to 50%, and then slightly decreased. The N2 selectivity of the catalyst and the NO conversion rate have a relatively obvious trend of increasing and decreasing at the same time.

[0096] In the activation atmosphere with water vapor, the increase of O2 content has a significant effect on the catalyst performance. This may be because O2 has an important influence on the crystal transformation of rhodochrosite and pyrolusite. The increase of oxygen content is conducive to the decomposition of crystal phases such as MnCO3 in rhodochrosite, and at the same time promotes the conversion of α-MnO2 and γ-MnO2 into β-MnO2, which promotes the increase of the number of active phases in the denitrification reaction. At the same time, water vapor and O2 are conducive to the crystal transformation of pyrolusite.

[0097] MnCO3+O2→MnO2+CO2

[0098] Table 4 Comparison of NO conversion rate after denitration in activated atmosphere with different oxygen contents

[0099] T / ℃ S1 S2 S3 S4 S5 100 20 40 57 62 53 120 25 55 73 76 69 150 37 71 95 100 91 180 45 93 100 100 100 200 61 100 100 100 100

[0100] Table 5 Comparison of denitrification N2 selectivity after treatment with activated atmospheres with different oxygen contents

[0101] T / ℃ S1 S2 S3 S4 S5 100 98 97 93 90 95 120 98 95 85 85 87 150 95 87 73 72 73 180 93 75 65 66 68 200 80 68 53 51 54

[0102] Sequence experiment 3: Effect of additives on denitrification performance

[0103] The following first introduces the preparation of each sample in this sequence experiment. For any incomplete information, please refer to the previous complete preparation method.

[0104] In the batching step, 2 parts of rhodochrosite, pyrolusite and hausmannite with a manganese content of about 20% are weighed respectively and mixed in a ratio of 1:1:1; cerium nitrate and ferric nitrate with a molar amount of 5% of the manganese element in the manganese ore are weighed respectively and added to two parts of the manganese ores; pseudo-boehmite is weighed as a binder in an amount of 10wt% of the total mass of the manganese ore.

[0105] In the mixing step, the above materials were mixed in a kneader for 10 minutes.

[0106] In the kneading step, an appropriate amount of deionized water was added to the mixed sample and kneaded for 30 minutes.

[0107] In the aging step, the mixture is left to age for 120 minutes after the kneading is completed.

[0108] In the forming step, the aged material is transferred to an extruder and extruded into 6 mm strips.

[0109] In the drying step, the catalyst precursor obtained after extrusion was dried at a temperature of 120° C. for 8 h.

[0110] In the activation step, the catalyst precursor is placed in an atmosphere calcining furnace, and a mixed gas is introduced for programmed temperature activation. The activation process is as follows: the catalyst precursor is heated to 120°C at a heating rate of 5°C / min in an air atmosphere and maintained for 30 minutes, and then an activation gas with an oxygen content of 20% and a water vapor content of 50% is introduced, and the temperature is raised to 250°C at a heating rate of 2°C / min, and maintained for 2 hours; then the temperature is raised to 500°C at the same heating rate, and the activation gas composition is 15% oxygen content and 25% water vapor, and the activation is performed at this temperature for 3 hours, and the activation is completed; the gas is switched to nitrogen, and the temperature is lowered to 110°C under nitrogen purge, and then the temperature is further lowered to 50°C under air purge and the catalyst is taken out. The sample with the addition of cerium nitrate is marked as catalyst S6, and the sample with the addition of iron nitrate is marked as catalyst S7.

[0111] The above catalyst was heated in 100ppmNO, 105ppmNH3, 5%H2O(g), 8%O2, 8%CO2, 10ppmSO2, the remaining gas was N2, and the space velocity was 2000h -1 The performance was evaluated under the conditions of , and the results are shown in Tables 6 and 7.

[0112] The NO conversion rate of S6 catalyst with cerium nitrate added was significantly improved, but the N2 selectivity was low; the NO conversion rate of S7 catalyst with ferric nitrate added was slightly improved at low temperature, and with the increase of temperature, the NO conversion rate decreased to a certain extent compared with S3 without additives, but the N2 selectivity was maintained at a high level overall. In the activation process of the catalyst with additives, in addition to the decomposition of cerium nitrate and ferric nitrate into cerium oxide and iron oxide, cerium and iron may participate in the decomposition of MnCO3 to form MnO2, forming composite oxides, thereby improving the conversion rate or N2 selectivity of the catalyst.

[0113] Table 6 Comparison of NO conversion rate of denitration catalysts using different additives

[0114] T / ℃ S3 S6 S7 100 57 93 65 120 73 100 79 150 95 100 87 180 100 100 96 200 100 100 100

[0115] Table 7 Comparison of denitrification N2 selectivity after treatment with activated atmospheres with different oxygen contents

[0116] T / ℃ S3 S6 S7 100 93 74 97 120 85 65 95 150 73 55 92 180 65 43 89 200 53 37 85

[0117] The second aspect of the present invention provides a denitration catalyst. The denitration catalyst is prepared by the above-mentioned denitration catalyst preparation method. For the denitration catalyst preparation method, reference may be made to the relevant description of the previous embodiment, which will not be repeated here.

[0118] The third aspect of the present invention provides an application of a denitration catalyst in low-temperature flue gas denitration, wherein the low-temperature flue gas is industrial flue gas with a temperature between 100 and 180°C and a water content of less than 15%. The relevant content can refer to the denitration NO conversion rate and denitration N2 selection comparison of each sample in the sequence experiment, which will not be repeated here.

[0119] At this point, the various embodiments of the present invention have been introduced. According to the above description, those skilled in the art should have a clear understanding of the present invention.

[0120] It should be noted that, unless explicitly indicated to the contrary, the numerical parameters in the specification and claims of the present invention may be approximate values ​​and may be changed according to the content of the present invention. Specifically, all the numbers indicating the content of the composition, reaction conditions, etc. recorded in the specification and claims should be understood to be modified by the term "about" in all cases, and the meaning of the expression is to include a change of ±10% from a specific number in some embodiments.

[0121] Those skilled in the art should understand that in the claims and description of the present invention, the word "comprising" does not exclude the existence of elements (or steps) not listed in the claims. The word "a" or "an" preceding an element (or step) does not exclude the existence of multiple such elements (or steps).

[0122] For certain implementations, if they are not the key content of the present invention and are well known to ordinary technicians in the relevant technical field, they are not described in detail in the drawings or text of the specification due to space limitations. At this time, they can be understood by referring to the relevant prior art. In addition, the purpose of providing the above embodiments is only to make the present invention meet legal requirements, and the present invention can be implemented in many different forms and should not be interpreted as limited to the embodiments described herein. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in this field can simply change or replace them.

[0123] Similarly, it should be understood that in order to simplify the present invention, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the invention should not be interpreted as reflecting the following intention: the claimed invention requires more features than the features explicitly stated in each claim. More specifically, as reflected in the claims, each inventive aspect lies in less than all the features of the previous single embodiment. Moreover, the embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present invention.

[0124] The above specific embodiments provide a detailed description of the objectives, technical means and beneficial effects of the present invention. It should be understood that the purpose of the detailed description is to enable those skilled in the art to understand the present invention more clearly, and it is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a denitration catalyst, characterized in that: include: Batching steps: preparing a mixture of manganese ore and binder powders; Kneading step: adding water to the mixed material and kneading; Molding step: molding the kneaded material to obtain a catalyst precursor; Activation step: activating the catalyst precursor in an activation environment to obtain a denitration catalyst, wherein the activation temperature in the activation environment is greater than 200° C., the molar proportion of oxygen in the activation atmosphere is greater than 10%, and the molar proportion of water vapor is greater than 20%.

2. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the activation step, the molar ratio of oxygen in the activation atmosphere is between 10% and 50%, and the molar ratio of water vapor is between 20% and 70%.

3. The method for preparing a denitration catalyst according to claim 2, characterized in that: The molar ratio of oxygen in the activation atmosphere is 40%, and the molar ratio of water vapor is 50%.

4. The method for preparing a denitration catalyst according to claim 2, characterized in that: The activation step comprises: The first activation sub-step: activating at a first activation temperature and an activation atmosphere, wherein the first activation temperature is between 200-280° C. and the activation time is between 2 and 12 hours; The second activation sub-step: activating at a second activation temperature and activation atmosphere, wherein the second activation temperature is between 300-600° C. and the activation time is between 3 and 8 hours.

5. The method for preparing a denitration catalyst according to claim 4, characterized in that: The activation step further comprises: A preheating sub-step before the first activation step: heating the catalyst precursor to 120° C. at a heating rate of 2 to 3° C. / min and maintaining the temperature for 10 to 60 minutes; The first activation sub-step comprises: introducing activation gas to obtain the activation atmosphere, heating the temperature to 200-280° C. at a heating rate of 1-2° C. / min, and maintaining the temperature for 2-12 hours; The second activation sub-step comprises: heating the temperature to 300-600° C. at a heating rate of 1-2° C. / min and maintaining the temperature for 3-8 hours, during which the activation atmosphere is kept unchanged; The second activation step also includes a cooling sub-step, in which the activation atmosphere is changed to a nitrogen atmosphere, the temperature is lowered to below 200° C., and then changed to an air atmosphere, the temperature is lowered to below 50° C., to obtain a denitration catalyst.

6. The method for preparing a denitration catalyst according to claim 1, characterized in that: The kneading step may include: a mixing step to mix the mixed materials uniformly; and / or After the kneading step and before the forming step, the following further comprises: an aging step: aging the kneaded material; and / or After the shaping step and before the activation step, the method further comprises: drying the catalyst precursor at a temperature of 40-120° C. for 12-24 hours.

7. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the batching step, a mixture of powders of manganese ore, a binder and a soluble metal salt is prepared; The soluble metal salt is a salt corresponding to one or more of the following metals: Ce, Cu, Zn, La, Fe, Co, and W.

8. The method for preparing a denitration catalyst according to claim 7, characterized in that: In the batching step, the soluble metal salts are cerium nitrate and ferric nitrate, and the molar amounts of the two are between 0.1% and 5% of the molar amount of manganese element in the mixed material.

9. The method for preparing a denitration catalyst according to claim 1, characterized in that: In the batching step, the manganese ore includes: more than 50wt% of the rhodochrosite category; more than 30wt% of pyrolusite; the rest is ferromanganese; wherein the rhodochrosite category includes one or more of the following: rhodochrosite, ferromanganese, and ferromanganese; and / or In the batching step, the binder is one or more of the following materials: pseudo-boehmite, sesbania powder, carboxymethyl cellulose, polyethylene glycol, and its content is less than or equal to 20wt% of the manganese ore.

10. A denitration catalyst, characterized in that: Prepared by the denitration catalyst preparation method according to any one of claims 1 to 9.

11. Use of the denitration catalyst according to claim 10 in low-temperature flue gas denitration, characterized in that: The low-temperature flue gas is industrial flue gas with a temperature between 100 and 180° C. and a water content lower than 15%.

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