Supported rare earth metal SCR denitration catalyst and preparation method and application thereof

Abstract

The invention relates to the technical field of SCR (Selective Catalytic Reduction) denitration catalysts, and provides a supported rare earth metal SCR denitration catalyst as well as a preparation method and application thereof, and the catalyst prepared by the preparation method has relatively high specific surface area and strong poisoning resistance. The catalyst comprises a titanium dioxide carrier, a manganese dioxide auxiliary and an active component, wherein the manganese dioxide auxiliary and the active component are loaded on the carrier, and the active component is one or more of holmium, lanthanum and neodymium. The preparation method comprises the following steps: S1, uniformly mixing titanium dioxide, manganese salt and a dispersing agent in a first solvent to obtain a mixed solution, and adjusting the pH value of the mixed solution to 4-8; performing aging after stirring; carrying out first drying on the obtained mixed solution, and then carrying out first step roasting to obtain a carrier loaded with manganese dioxide; and S2, uniformly mixing the carrier loaded with manganese dioxide with an active component precursor in a second solvent, then carrying out second drying, and then carrying out second step roasting to obtain the catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR denitration catalysts, and in particular to a supported rare earth metal SCR denitration catalyst and a preparation method and application thereof. Background Art

[0002] Nitrogen oxides (NOx) released by coal combustion are a major cause of environmental pollution. Currently, selective catalytic reduction of NOx by ammonia is the primary method for controlling NOx emissions from coal-fired power plants. Compared with high-dust and low-dust arrangements, the tail arrangement can reduce wear and clogging of the SCR catalyst caused by high dust levels, thereby extending the service life of the SCR catalyst. As the core component of the SCR system, the performance of the catalyst directly determines the system's denitrification efficiency. In actual production, flue gas also contains a large amount of SO2, which can poison the catalyst and cause severe deactivation. Therefore, how to develop denitrification catalysts with excellent poisoning resistance is a research hotspot in this field. Summary of the Invention

[0003] The present invention provides a supported rare earth metal SCR denitration catalyst, a preparation method and application thereof. The catalyst prepared by the preparation method of the present invention has a high specific surface area, not only has strong anti-poisoning ability, but also has good denitration activity.

[0004] To achieve its purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a supported rare earth metal SCR denitration catalyst, wherein the catalyst comprises a titanium dioxide carrier, a manganese dioxide additive supported on the carrier, and an active component, wherein the active component is one or more of holmium, lanthanum, and neodymium, preferably one or two of holmium and neodymium, and more preferably neodymium;

[0006] The preparation method comprises the following steps:

[0007] S1. uniformly mixing titanium dioxide, a manganese salt, and a dispersant in a first solvent to obtain a mixed solution, adjusting the pH of the mixed solution to 4-8, preferably 5-7, more preferably 5.5-6.5; stirring and aging the mixed solution; then performing a first drying on the obtained mixed solution, and then performing a first step calcination to obtain a carrier loaded with manganese dioxide;

[0008] S2, mixing the carrier loaded with manganese dioxide and the active component precursor uniformly in a second solvent, then performing a second drying, and then performing a second step calcination to obtain the catalyst;

[0009] The first step calcination and the second step calcination independently include: first heating to 200-300°C for calcination, preferably keeping warm for 1-2 hours; then heating to 400-600°C for calcination, preferably keeping warm for 4-5 hours.

[0010] Furthermore, based on the total mass of the catalyst, the content of the auxiliary agent in terms of Mn element is 3-5 wt%, and the content of the active component is 1-2 wt%.

[0011] Preferably, in the catalyst, the mass ratio of manganese dioxide to titanium dioxide is 1:15-20.

[0012] Preferably, in step S1, the mass ratio of the titanium dioxide, the manganese salt, the dispersant and the first solvent is 10:(1-2):(2-3):(10-100);

[0013] And / or, in step S2, the mass ratio of the active component precursor to the second solvent is 1:(10-50).

[0014] Preferably, in step S1, the manganese salt is one or more of manganese nitrate, manganese acetate and hydrates thereof;

[0015] And / or, in step S1, the dispersant is one or more of citric acid and stearic acid;

[0016] And / or, in step S1, the first solvent is one or more of anhydrous ethanol and deionized water;

[0017] And / or, in step S1, the first drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours;

[0018] And / or, in step S1, after adjusting the pH, stirring for 6 to 10 hours, and then standing for 6 to 8 hours to perform the aging;

[0019] And / or, in step S1, the titanium dioxide is anatase titanium dioxide.

[0020] Preferably, in step S2, the second solvent is one or more of anhydrous ethanol and deionized water;

[0021] And / or, in step S2, the active component precursor is selected from one or more of holmium salts, lanthanum salts, neodymium salts and hydrates thereof, the holmium salts are, for example, one or more of holmium nitrate, holmium chloride and holmium carbonate, the lanthanum salts are, for example, one or more of lanthanum nitrate, lanthanum phosphate and lanthanum acetate, and the neodymium salts are, for example, one or more of neodymium nitrate, neodymium oxalate and neodymium chloride;

[0022] And / or, in step S2, the second drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours;

[0023] And / or, the support loaded with manganese dioxide obtained in step S1 is washed with water and dried before being used in step S2.

[0024] Preferably, in step S1, the material obtained by the first drying is ground and then subjected to the first step roasting;

[0025] In step S2, the material obtained by the second drying is ground and then subjected to the second step roasting.

[0026] The present invention also provides a catalyst prepared by the above-mentioned preparation method.

[0027] Furthermore, the pore size of the catalyst is 0.2-0.3 nm and the pore volume is 6-8 cm 3 / g, with a specific surface area of ​​50 to 80 m 2 / g.

[0028] The present invention also provides the use of the above-mentioned catalyst in SCR denitration.

[0029] The technical solution provided by the present invention has the following beneficial effects:

[0030] The present invention uses a two-step method to prepare the catalyst. First, manganese oxide is loaded onto a titanium dioxide support. In step S1, the solution pH is controlled during the preparation process. Subsequently, the support is calcined in a stepwise manner, first at 200-300°C and then at 400-600°C, to obtain a manganese dioxide-loaded support. The active component is then loaded and calcined in a stepwise manner, first at 200-300°C and then at 400-600°C. The catalyst prepared using the method of the present invention has a high specific surface area, good anti-poisoning ability, and excellent sulfur resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the NH3-SCR denitrification activity diagram of the catalyst;

[0032] Figure 2 These are the test results of the catalyst's tolerance to SO2 poisoning at 250°C. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items. The terms "first," "second," etc., are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

[0035] In one aspect, the present invention provides a method for preparing a supported rare earth metal SCR denitration catalyst, wherein the catalyst comprises a titanium dioxide support, a manganese dioxide additive supported on the support, and an active component, wherein the active component is one or more of holmium, lanthanum, and neodymium, preferably one or both of holmium and neodymium, and more preferably neodymium.

[0036] The preparation method comprises the following steps:

[0037] S1. uniformly mixing titanium dioxide, a manganese salt, and a dispersant in a first solvent to obtain a mixed solution, adjusting the pH of the mixed solution to 4-8 (e.g., pH 4, 5, 6, 7, or 8), preferably 5-7, more preferably 5.5-6.5; stirring and aging the mixed solution; then performing a first drying on the obtained mixed solution, and then performing a first step calcination to obtain a carrier loaded with manganese dioxide;

[0038] S2, mixing the carrier loaded with manganese dioxide and the active component precursor uniformly in a second solvent, then performing a second drying, and then performing a second step calcination to obtain the catalyst;

[0039] The first-step calcination and the second-step calcination independently include: first heating to 200-300°C (for example, 200, 250, 300°C) for calcination, preferably keeping warm for 1-2 hours; then heating to 400-600°C (for example, 400, 500, 600°C) for calcination, preferably keeping warm for 4-5 hours.

[0040] The present invention utilizes a two-step process to prepare the catalyst. First, manganese oxide is loaded onto a titanium dioxide carrier. During the preparation process, the solution pH is controlled at 4-8. The carrier is then calcined in a stepwise manner, first at 200-300°C and then at 400-600°C, to obtain a manganese dioxide-loaded carrier. The active component is then loaded and calcined in a stepwise manner, first at 200-300°C and then at 400-600°C. The catalyst prepared using the method of the present invention has a high specific surface area, good anti-poisoning ability, and excellent sulfur resistance.

[0041] Preferably, the active component is holmium and / or neodymium. Using the preferred active component, the prepared catalyst has better denitrification activity and anti-poisoning ability. More preferably, the active component is neodymium. The inventors have found that using neodymium as the active component, compared with other rare earth metals, not only is the raw material cost lower, but the prepared catalyst has better performance. Neodymium loaded on the manganese titanium catalyst has excellent performance for NH3 and NOx adsorption, can better broaden the temperature window of the SCR denitrification catalyst, and has better low-temperature NH3-SCR catalytic activity. The provided catalyst is conducive to promoting the SCR denitrification reaction through the LH mechanism, while having better anti-poisoning ability.

[0042] Preferably, in step S1, the pH of the mixed solution is adjusted to 5.5-6.5. The present inventors have found that adopting this preferred method to prepare the catalyst is conducive to further improving the denitrification activity and anti-poisoning ability of the obtained catalyst.

[0043] In a more preferred embodiment, the active component is neodymium, and in step S1, the pH of the mixed solution is adjusted to 5.5-6.5. In the method of the present invention, this preferred method is used to prepare the catalyst, which is conducive to obtaining a catalyst with both better denitrification activity and anti-poisoning ability.

[0044] Preferably, based on the total mass of the catalyst, the content of the promoter as Mn is 3-5 wt% (e.g., 3, 4, or 5 wt%), and the content of the active component (as rare earth metal) is 1-2 wt% (e.g., 1, 1.5, or 2 wt%). The specific amount of each raw material used in the preparation process can be determined based on the content of each component in the catalyst.

[0045] Preferably, in the catalyst, the mass ratio of manganese dioxide to titanium dioxide is 1:15 to 20, for example, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20.

[0046] Preferably, in step S1, the mass ratio of the titanium dioxide, the manganese salt, the dispersant and the first solvent is 10:(1-2):(2-3):(10-100).

[0047] Preferably, in step S2, the mass ratio of the active component precursor to the second solvent is 1:(10-50), for example, 1:10, 1:20, 1:30, 1:40 or 1:50.

[0048] In some embodiments, in step S1, the manganese salt is one or more of manganese nitrate, manganese acetate, and hydrates thereof;

[0049] In some embodiments, in step S1, the dispersant is one or more of citric acid and stearic acid; the addition of the above-mentioned dispersant in step S1 of the present invention is conducive to the uniform dispersion of the components, thereby making the active components and additives in the prepared catalyst highly dispersed, thereby helping to improve the catalytic activity of the catalyst.

[0050] In some embodiments, in step S1, the first solvent is one or more of anhydrous ethanol and deionized water;

[0051] In some embodiments, in step S1, the first drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours;

[0052] In some embodiments, in step S1, after adjusting the pH, stirring is performed for 6 to 10 hours, and then standing for 6 to 8 hours for aging.

[0053] Preferably, in step S1, the titanium dioxide is anatase titanium dioxide.

[0054] In some embodiments, in step S2, the second solvent is one or more of anhydrous ethanol and deionized water;

[0055] In some embodiments, in step S2, the active component precursor is selected from one or more of holmium salts, lanthanum salts, neodymium salts, and hydrates thereof, wherein the holmium salt is, for example, one or more of holmium nitrate, holmium chloride, and holmium carbonate; the lanthanum salt is, for example, one or more of lanthanum nitrate, lanthanum phosphate, and lanthanum acetate; and the neodymium salt is, for example, one or more of neodymium nitrate, neodymium oxalate, and neodymium chloride.

[0056] In some embodiments, in step S2, the second drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours;

[0057] Preferably, the manganese dioxide-loaded carrier obtained in step S1 is washed with water and dried before being used in step S2.

[0058] Preferably, in step S1, the material obtained by the first drying is ground and then subjected to the first step roasting;

[0059] In step S2, the material obtained by the second drying is ground and then subjected to the second step roasting.

[0060] Another aspect of the present invention provides a catalyst prepared using the preparation method described above. The catalyst provided by the present invention comprises a titanium dioxide support, a manganese dioxide promoter supported on the support, and an active component, wherein the active component is one or more of holmium, lanthanum, and neodymium, preferably holmium and / or neodymium, and more preferably neodymium. Preferably, based on the total mass of the catalyst, the promoter comprises 3-5% by weight of Mn, and the active component comprises 1-2% by weight of the rare earth metal.

[0061] Furthermore, the pore size of the catalyst is 0.2-0.3 nm and the pore volume is 6-8 cm 3 / g, with a specific surface area of ​​50 to 80 m 2 / g.

[0062] The catalyst provided by the present invention has a good effective lifespan, which can reach 100-120 hours.

[0063] Another aspect of the present invention provides use of the catalyst described above in SCR denitration.

[0064] The present invention is further described below by way of examples, but it should not be understood that the present invention is limited thereto.

[0065] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. Reagents or instruments used without specifying the manufacturer are all commercially available conventional products.

[0066] Specific surface area, pore size, and pore volume determination methods: To determine specific surface area, pore size, and pore volume, physical adsorption analysis was performed using the BET and BJH methods. The catalyst was ground into 100-mesh particles, and 0.2 g was weighed and measured at liquid nitrogen temperature (-196°C).

[0067] The titanium dioxide used in the following examples and comparative examples is all anatase titanium dioxide.

[0068] Example 1

[0069] S1. Dissolve 1.6g of Mn(NO3)2·4H2O and 2g of citric acid in 10ml of deionized water, then add 10g of TiO2 and mix evenly; add 1mol / L of dilute nitric acid dropwise to the mixed solution and stir rapidly until the pH reaches 6, stop adding, stir thoroughly for 6h, and then let it stand for 6h. Then dry it in a 105℃ blast drying oven for 10h; then grind the obtained material and place it in a muffle furnace, first heat it from room temperature to 250℃ and keep it warm for 2h, then heat it to 450℃ and keep it warm for 4h; then rinse it with deionized water and dry it in a 105℃ blast drying oven for 10h to obtain a carrier loaded with manganese dioxide, that is, a Mn / TiO2 powder catalyst;

[0070] S2. The Mn / TiO2 powder catalyst obtained in step S1 was dispersed in 10 ml of anhydrous ethanol, 0.4 g of holmium nitrate pentahydrate was added and stirred thoroughly, and the mixture was dried in a forced air drying oven at 105° C. for 10 h. The resulting material was then ground and placed in a muffle furnace. The temperature was first raised from room temperature to 250° C. and kept warm for 2 h, and then raised to 450° C. and kept warm for 4 h. The powder was collected to obtain the HoMn / TiO2 powder catalyst.

[0071] The prepared catalyst contained 3.27 wt% Mn and 1.40 wt% holmium. The mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0072] Example 2

[0073] The same process was carried out as in Example 1, except that 0.4 g of holmium nitrate pentahydrate in step S2 was replaced with 0.4 g of lanthanum nitrate hexahydrate (La(NO3)3·6H2O), thereby obtaining a LaMn / TiO2 powder catalyst.

[0074] The prepared catalyst had a Mn content of 3.27 wt%, a lanthanum content of 1.20 wt%, and a mass ratio of manganese dioxide to titanium dioxide of 1:18. Other experimental results are shown in Tables 1-3.

[0075] Example 3

[0076] The same process was carried out as in Example 1, except that 0.4 g of holmium nitrate pentahydrate in step S2 was replaced with 0.4 g of neodymium nitrate hexahydrate (Nd(NO3)3·6H2O), thereby obtaining a NdMn / TiO2 powder catalyst.

[0077] The prepared catalyst contained 3.27 wt% Mn and 1.38 wt% Nd; the mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0078] Example 4

[0079] S1. Dissolve 1.6g of Mn(NO3)2·4H2O and 2g of citric acid in 10ml of deionized water, then add 10g of TiO2 and mix evenly; add 1mol / L of dilute nitric acid dropwise to the mixed solution and stir rapidly until the pH reaches 5, stop adding, stir thoroughly for 6h, and then let it stand for 6h. Then dry it in a 105℃ blast drying oven for 10h, then grind the resulting material and place it in a muffle furnace, first heating it from room temperature to 250℃ and keeping it warm for 2h, then heating it to 450℃ and keeping it warm for 4h; then rinse it with deionized water and dry it in a 105℃ blast drying oven for 10h to obtain a carrier loaded with manganese dioxide, that is, a Mn / TiO2 powder catalyst;

[0080] S2. Disperse the Mn / TiO2 powder catalyst obtained in step S1 in 10 ml of anhydrous ethanol, add 0.4 g of neodymium nitrate hexahydrate (Nd(NO3)3·6H2O), stir well, and dry in a blast drying oven at 105°C for 10 h; then grind the resulting material, place it in a muffle furnace, first heat it from room temperature to 250°C and keep it warm for 2 h, then heat it to 450°C and keep it warm for 4 h to obtain a catalyst.

[0081] The prepared catalyst contained 3.27 wt% Mn and 1.38 wt% Nd; the mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0082] Example 5

[0083] S1. Dissolve 1.6g of Mn(NO3)2·4H2O and 2g of citric acid in 10ml of deionized water, then add 10g of TiO2 and mix evenly; add 1mol / L of dilute nitric acid dropwise to the mixed solution and stir rapidly until the pH reaches 7, stop adding, stir thoroughly for 6h, and then let it stand for 6h. Then dry it in a 105℃ blast drying oven for 10h, then grind the resulting material and place it in a muffle furnace, first heating it from room temperature to 250℃ and keeping it warm for 2h, then heating it to 450℃ and keeping it warm for 4h; then rinse it with deionized water and dry it in a 105℃ blast drying oven for 10h to obtain a carrier loaded with manganese dioxide, that is, a Mn / TiO2 powder catalyst;

[0084] S2. Disperse the Mn / TiO2 powder catalyst obtained in step S1 in 10 ml of anhydrous ethanol, add 0.4 g of neodymium nitrate hexahydrate (Nd(NO3)3·6H2O), stir well, and dry in a blast drying oven at 105°C for 10 h; then grind the resulting material, place it in a muffle furnace, first heat it from room temperature to 250°C and keep it warm for 2 h, then heat it to 450°C and keep it warm for 4 h to obtain a catalyst.

[0085] The prepared catalyst contained 3.27 wt% Mn and 1.38 wt% Nd; the mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0086] Comparative Example 1

[0087] Preparation of Mn / TiO2 catalyst by impregnation method:

[0088] 2 g of Mn(NO₃)₂·4H₂O was dissolved in 10 ml of deionized water, followed by the addition of 10 g of TiO₂ and the mixture was thoroughly stirred for 6 hours and then allowed to stand for 6 hours. The mixture was then dried in a forced air drying oven at 105°C for 10 hours. The resulting mixture was then ground and calcined in a muffle furnace, following the same calcination process as in Step S1 of Example 1, to obtain a Mn / TiO₂ catalyst. Other experimental results are shown in Tables 1-3.

[0089] Comparative Example 2

[0090] The catalyst was prepared by referring to Example 1, except that the catalyst was prepared by a one-step method. The specific steps are as follows:

[0091] 1.6g of Mn(NO3)2·4H2O and 0.4g of holmium nitrate pentahydrate (Ho(NO3)3·5H2O) were dissolved in 10ml of deionized water, followed by the addition of 10g of TiO2. The mixture was stirred thoroughly for 6 hours and then allowed to stand for 6 hours. The mixture was then dried in a 105°C forced air oven for 10 hours. The resulting mixture was then ground and placed in a muffle furnace. The temperature was first raised from room temperature to 250°C and maintained for 2 hours, then to 450°C and maintained for 4 hours, yielding a one-step HoMn / TiO2 catalyst.

[0092] Experimental Results: The prepared catalyst contained 3.27 wt% Mn and 1.40 wt% holmium. The mass ratio of manganese dioxide to titanium dioxide was 1:18. See Tables 1-3 for other experimental results.

[0093] Example 6

[0094] The process is carried out in accordance with Example 3, except that in step S1, the pH of the mixed solution is adjusted to 4.

[0095] Experimental results:

[0096] The prepared catalyst contained 3.27 wt% Mn and 1.38 wt% Nd; the mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0097] Example 7

[0098] The process is carried out in accordance with Example 3, except that in step S1, the pH of the mixed solution is adjusted to 8.

[0099] Experimental results:

[0100] The prepared catalyst contained 3.27 wt% Mn and 1.38 wt% Nd; the mass ratio of manganese dioxide to titanium dioxide was 1:18. Other experimental results are shown in Tables 1-3.

[0101] Table 1 Pore volume, pore diameter and specific surface area data of catalysts

[0102]

[0103]

[0104] The experimental results in Table 1 show that the catalysts prepared in the examples of the present invention have larger specific surface areas than the comparative examples. Among Examples 1-3, the HoMn / TiO2 powder catalysts and NdMn / TiO2 powder catalysts prepared in Examples 1 and 3 have larger specific surface areas than the lanthanum-loaded catalyst prepared in Example 2, with the NdMn / TiO2 powder catalyst prepared in Example 3 having a larger specific surface area.

[0105] Denitrification activity evaluation:

[0106] The catalyst denitrification activity evaluation experiments for the examples and comparative examples were all conducted in a fixed-bed quartz tube reactor. The volume of each catalyst used was approximately 0.538 cubic centimeters (over 100 mesh), and the catalysts were fixed in place by high-temperature quartz wool. The composition of the simulated flue gas contained 600 ppm NO, 600 ppm NH3, 5% O2, 5% H2O, 100 ppm SO2, and 100 ppm Ar. The gas hourly space velocity of the simulated flue gas was 108,000 h -1 In addition, the inlet and outlet NH3 and NO concentrations were continuously monitored using a flue gas analyzer and an infrared spectrometer detector.

[0107] The experimental results are shown in Table 2. The NH3-SCR denitrification activity diagram drawn based on Table 2 is shown in Figure 1 .

[0108] Table 2. Experimental results of NH3-SCR denitrification activity of catalysts

[0109]

[0110]

[0111] As can be seen from the experimental results in Table 2, the denitration catalysts prepared in each embodiment of the present invention have better denitration activity than those in Comparative Examples 1 and 2. In Examples 1-3, the NdMn / TiO2 catalyst prepared in Example 3 has significantly better denitration activity than the Ho-doped or La-doped Mn / TiO2 catalysts prepared in Examples 1 and 2, and has a wider temperature window; and the Ho-doped Mn / TiO2 catalyst prepared in Example 1 has better denitration activity than the La-doped Mn / TiO2 catalyst prepared in Example 2. As can be seen from Examples 3-7, the pH in the preparation process of step S1 has a key influence on the catalyst activity, and the catalyst denitration activity and activation temperature obtained when pH = 5.5-6.5 are optimal.

[0112] Anti-poisoning performance evaluation:

[0113] Experimental method: The anti-poisoning experiment was carried out with reference to the denitrification activity evaluation experiment, with the following difference: during the experiment, 100 ppm of SO2 was introduced at the beginning of the first hour and the introduction of 100 ppm of SO2 was stopped at the eighth hour. The main purpose was to test the catalyst's SO2 tolerance at 250°C.

[0114] The experimental results are shown in Table 3. The SO2 tolerance results of the catalyst at 250°C drawn according to Table 3 are shown in Figure 2 .

[0115] Table 3. SO2 tolerance of catalysts at 250°C (NO conversion, %)

[0116]

[0117] From the experimental results in Table 3, it can be seen that the denitration catalysts prepared in various embodiments of the present invention have better SO2 poisoning tolerance than comparative examples 1 and 2. In Examples 1-3, the NdMn / TiO2 catalyst prepared in Example 3 has significantly better SO2 poisoning tolerance than the Ho-doped or La-doped Mn / TiO2 catalysts prepared in Examples 1 and 2; and the Ho-doped Mn / TiO2 catalyst prepared in Example 1 has better anti-poisoning performance than the La-doped Mn / TiO2 catalyst prepared in Example 2. From the comparison of Examples 3-7, it can be seen that the pH in the preparation process of step S1 also has an effect on the anti-poisoning activity of the catalyst. The catalyst obtained at pH = 5.5-6.5 has significantly better anti-poisoning performance; compared with Examples 6-7, the denitration efficiency of Examples 4-5 can be restored to a higher level at 10h.

[0118] It will be readily understood that the above embodiments are merely examples for clarity of description and are not intended to limit the present invention to these examples. Those skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a supported rare earth metal SCR denitration catalyst, characterized in that: The catalyst comprises a titanium dioxide carrier, a manganese dioxide promoter supported on the carrier, and an active component, wherein the active component is one or more of holmium, lanthanum, and neodymium, preferably one or two of holmium and neodymium, and more preferably neodymium; The preparation method comprises the following steps: S1. uniformly mixing titanium dioxide, a manganese salt, and a dispersant in a first solvent to obtain a mixed solution, adjusting the pH of the mixed solution to 4-8, preferably 5-7, more preferably 5.5-6.5; stirring and aging the mixed solution; then performing a first drying on the obtained mixed solution, and then performing a first step calcination to obtain a carrier loaded with manganese dioxide; S2, mixing the carrier loaded with manganese dioxide and the active component precursor uniformly in a second solvent, then performing a second drying, and then performing a second step calcination to obtain the catalyst; The first step calcination and the second step calcination independently include: first heating to 200-300°C for calcination, preferably keeping warm for 1-2 hours; then heating to 400-600°C for calcination, preferably keeping warm for 4-5 hours.

2. The preparation method according to claim 1, characterized in that Based on the total mass of the catalyst, the content of the auxiliary agent calculated as Mn element is 3-5 wt %, and the content of the active component is 1-2 wt %.

3. The preparation method according to claim 1 or 2, characterized in that In the catalyst, the mass ratio of manganese dioxide to titanium dioxide is 1:15-20.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step S1, the mass ratio of the titanium dioxide, the manganese salt, the dispersant and the first solvent is 10:(1-2):(2-3):(10-100); And / or, in step S2, the mass ratio of the active component precursor to the second solvent is 1:(10-50).

5. The preparation method according to any one of claims 1 to 4, characterized in that In step S1, the manganese salt is one or more of manganese nitrate, manganese acetate and hydrates thereof; And / or, in step S1, the dispersant is one or more of citric acid and stearic acid; And / or, in step S1, the first solvent is one or more of anhydrous ethanol and deionized water; And / or, in step S1, the first drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours; And / or, in step S1, after adjusting the pH, stirring for 6 to 10 hours, and then standing for 6 to 8 hours to perform the aging; And / or, in step S1, the titanium dioxide is anatase titanium dioxide.

6. The preparation method according to any one of claims 1 to 5, characterized in that In step S2, the second solvent is one or more of anhydrous ethanol and deionized water; And / or, in step S2, the active component precursor is selected from one or more of holmium salts, lanthanum salts, neodymium salts and hydrates thereof, the holmium salts are, for example, one or more of holmium nitrate, holmium chloride and holmium carbonate, the lanthanum salts are, for example, one or more of lanthanum nitrate, lanthanum phosphate and lanthanum acetate, and the neodymium salts are, for example, one or more of neodymium nitrate, neodymium oxalate and neodymium chloride; And / or, in step S2, the second drying conditions include: a temperature of 80 to 110° C., and a time preferably of 10 to 12 hours; And / or, the support loaded with manganese dioxide obtained in step S1 is washed with water and dried before being used in step S2.

7. The preparation method according to any one of claims 1 to 6, characterized in that In step S1, the material obtained by the first drying is ground and then subjected to the first step roasting; In step S2, the material obtained by the second drying is ground and then subjected to the second step roasting.

8. A catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. The catalyst according to claim 8, characterized in that The pore size of the catalyst is 0.2-0.3 nm and the pore volume is 6-8 cm 3 / g, with a specific surface area of ​​50 to 80 m 2 / g.

10. Use of the catalyst according to claim 8 or 9 in SCR denitration.

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