Composite rare earth low-temperature alkali metal-resistant, sulfur-resistant denitration catalyst and preparation method thereof

Abstract

The application discloses a composite rare earth low-temperature alkali metal-resistant and sulfur-resistant denitration catalyst and a preparation method thereof. The catalyst is made by mixing active material V2O5, additives (Mn-Sm-Mo)Ox and carrier material TiO2, and part of the additives CeO2-Nb2O5 is implanted in an impregnation mode. The catalyst comprises the following raw material components in mass fractions: 2-5 parts of vanadyl oxalate, 3-7 parts of ammonium molybdate, 1-3 parts of manganese nitrate, 0.2-0.5 parts of cerium nitrate, 0.1-0.4 parts of niobium oxalate, 0.2-0.3 parts of samarium nitrate and 1-10 parts of TiO2. The chemical formula of the low-temperature alkali metal-resistant and sulfur-resistant denitration catalyst is CeO2-Nb2O5 / (V-Mn-Sm-Mo)Ox / TiO2, wherein the CeO2-Nb2O5 is loaded on the surface of (V-Mn-Sm-Mo)Ox / TiO2. Compared with traditional commercial catalysts, the denitration catalyst has excellent sulfur resistance and alkali metal resistance and a longer service life under the condition of meeting deNOx at low temperature (less than or equal to 180 DEG C).

Description

Technical Field

[0001] This invention belongs to the field of industrial denitrification catalyst technology, and relates to a composite rare earth low-temperature alkali metal and sulfur-resistant denitrification catalyst and its preparation method. Technical Background

[0002] Nitrogen oxides (NOx) are one of the main pollutants in industrial air. With increasingly stringent domestic industrial flue gas emission standards, more and more coal-fired boilers, biomass boilers, and waste incineration boilers are undergoing upgrades to meet these standards. This places higher demands on environmental protection equipment manufacturers, as flue gas temperatures are decreasing and flue gas composition is becoming more complex. In low-temperature environments (≤180℃), non-thermal power industries such as waste incineration, biomass boilers, gas-fired boilers, and mobile source heavy oil internal combustion engines face SOx levels exceeding 35 mg / Nm³. 3 The catalyst generates NH4HSO4 and (NH4)2SO4, posing a poisoning risk; the alkali metal content is unstable; and NOx emissions must be ultra-low, <25 mg / Nm³. 3 Under certain conditions, traditional selective catalytic reduction (SCR) honeycomb catalyst supports (V₂O₅-WO₃ / MoO₃-TiO₂) cannot withstand SOx poisoning in flue gas at low temperatures (≤180℃). Similarly, traditional SCR honeycomb catalyst supports cannot withstand alkali metals and alkaline earth metals (K₂O₅-WO₃ / MoO₃-TiO₂). + Na + Ca + The damage caused by the catalyst can easily lead to chemical poisoning of the denitrification carrier, ultimately causing the catalyst to fail to reach its designed lifespan and need to be replaced prematurely. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a composite rare earth low-temperature alkali metal-resistant and sulfur-resistant denitrification catalyst and its preparation method. To address the sulfur resistance and alkali metal resistance issues of commercial low-temperature denitrification catalysts, this invention develops a honeycomb homogeneous catalyst based on a transition metal oxide (V₂O₅-MoO₃-Nb₂O₅-MnO₂) composite rare earth metal oxide (CeO₂-Sm₂O₃) and TiO₂-based substrate. In flue gas containing alkali metals at low temperatures (160-180℃), the denitrification efficiency can reach up to 95.80%. The layered structure of MoO₃ can effectively remove NH₃... 4+ The confined domain feature enables spatial separation of ammonium ions and hydrogen sulfate ions in ammonium bisulfate, significantly increasing the resistance to sulfur poisoning. The introduced NbOx is a typical n-type strong acid transition metal that can dissolve alkali metals, greatly increasing the catalyst's resistance to alkali metal poisoning. This solves the problem of physical and chemical poisoning of catalysts at low temperatures in waste incinerators, industrial silicon, and biomass boilers, and has certain commercial and social value.

[0004] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows:

[0005] In a first aspect, embodiments of the present invention provide a composite rare earth low-temperature alkali metal-resistant and sulfur-resistant denitrification catalyst, wherein the catalyst is made by mixing active material V2O5 and auxiliary agent (Mn-Sm-Mo)Ox with support material TiO2, and some of the auxiliary agent CeO2-Nb2O5 is implanted by impregnation.

[0006] The catalyst comprises, by mass fraction, the following raw material components: 2-5 parts vanadium oxalate, 3-7 parts ammonium molybdate, 1-3 parts manganese nitrate, 0.2-0.5 parts cerium nitrate, 0.1-0.4 parts niobium oxalate, 0.2-0.3 parts samarium nitrate, and 1-10 parts TiO2;

[0007] The chemical formula of the low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst is CeO2-Nb2O5 / (V-Mn-Sm-Mo)Ox / TiO2, wherein CeO2-Nb2O5 is supported on the surface of (V-Mn-Sm-Mo)Ox / TiO2.

[0008] Further, by mass fraction, the catalyst comprises the following raw material components: 3 parts vanadium oxalate, 5 parts ammonium molybdate, 1 part manganese nitrate, 0.3 parts cerium nitrate, 0.1 parts niobium oxalate, 0.2 parts samarium nitrate, and 8 parts TiO2.

[0009] Furthermore, the catalyst has a homogeneous honeycomb structure with BET ≥ 75m. 2 / g, Pv≥0.29cm 3 / g, mechanical strength: axial ≥2.0MPa, radial ≥1.3MPa.

[0010] Secondly, embodiments of the present invention provide a method for preparing the composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst described in the first aspect, comprising the following steps:

[0011] (1) According to the component ratio, put 0.1-0.4 parts of niobium oxalate and 0.2-0.5 parts of cerium nitrate into a paddle-type stirred tank, add 3-6 parts of 0.3-0.6 mol / L ethanol solution, set the stirring tank motor frequency to 40-60 rpm, turn on the heating device to raise the liquid temperature to 45-60℃, stir for 1-2 hours and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use;

[0012] (2) Mix 2-5 parts of vanadium oxalate, 3-7 parts of ammonium molybdate, 1-3 parts of manganese nitrate, 0.2-0.3 parts of samarium nitrate and 1-10 parts of titanium dioxide in a dry state to obtain mixture B;

[0013] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to the mixture B in step (2) and stir. Finally, adjust the pH value of the mixture to ≥7.7 and the plasticity value to 7-11 with ammonia water to obtain mixed mud C.

[0014] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene or stainless steel container for 12-24 hours at an aging temperature of 10-35℃ to obtain aged mud material.

[0015] (5) Filter the aged mud material from step (4) to remove impurities;

[0016] (6) Demold the filtered mud from step (5) into shape;

[0017] (7) Dehydrate and dry the shaped clay material from step (6);

[0018] (8) Place the dried clay material from step (7) into the impregnation solution A from step (1) and impregnate for 0.5-1h;

[0019] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0020] (10) The dried clay blanks from step (9) are calcined at high temperature.

[0021] Further, in step (3), the mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, liquid silicon and titanium dioxide (TiO2) in step (2) is: (0.02-0.03): (0.01-0.04): (0.1-0.3): (0.01-0.02): (0.02-0.04): (0.03-0.05): (0.2-0.6): 1.

[0022] Furthermore, the shaped clay material described in step (7) is dried and dehydrated using an electric oven. The heating rate during the drying process is 3-5℃ / h, and the constant temperature zone is 80-100℃ for 30-40h.

[0023] Furthermore, in step (8), a pressure impregnation tank is used during the impregnation process, and the impregnation tank is pressurized with N2, with the pressure maintained at 0.08-0.2MPa.

[0024] Furthermore, in step (10), the calcination equipment used during high-temperature calcination is a muffle furnace with a heating rate of 15-20℃ / min, a constant temperature zone temperature of 480-530℃, and a calcination time of 24-30h.

[0025] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0026] The theoretical and research basis of this invention is that the layered structure of MoO3 can convert NH4+ into NH4+. + The confined domain characteristic enables the realization of NH in ammonium hydrogen sulfate. 4+ Ions and HSO 4- Spatial separation effectively lowers the decomposition temperature of ABS. The introduction of n-type transition metal oxide NbOx, a highly acidic substance, not only dissolves some alkali metals but also provides more bronsted acidic sites for the catalyst, thereby improving its resistance to alkali metals. Mn has a wide valence distribution, and different Mn valence states can directly interconvert to produce redox properties, promoting the selective reduction of NO by NH3, thus promoting the SCR reaction. The CeO2 in CeO2... 4+ and Ce 3+ The redox transformation can improve the oxygen storage capacity of Mn-based catalysts and promote the oxygen migration ability of SCR. When SO2 is present in the reaction atmosphere, it will preferentially adsorb onto Ce atoms to form sulfate. In addition, cerium sulfate will form new bronsted acidic sites. By introducing CeO2 and incorporating Sm elements, the conversion of SO2 to SO3 can be inhibited, resulting in a significant reduction in the amount of NH4HSO4 generated. At the same time, the (Sm-Mn)Ox precursor material decomposes into metal oxides during high-temperature calcination and generates complexation, which can effectively inhibit the sulfation of active components and thus improve the catalyst's resistance to sulfur poisoning. It is particularly suitable for low-temperature flue gas denitrification in non-power industries. Attached Figure Description

[0027] Figure 1 These are the specific surface area test data of the denitrification catalyst prepared in Example 2.

[0028] Figure 2 The results are the pore volume test results of the denitrification catalyst prepared in Example 3.

[0029] Figure 3 This is a graph showing the axial strength test of the denitrification catalyst prepared in Example 4.

[0030] Figure 4 These are the axial and radial strength test results of the denitrification catalyst prepared in Example 4.

[0031] Figure 5 This is a scanning electron microscope image of the denitrification catalyst prepared in Example 3. Detailed Implementation

[0032] A composite rare earth low-temperature alkali metal resistant and sulfur denitrification catalyst is prepared by mixing active material V2O5 and auxiliary agent (Mn-Sm-Mo)Ox with support material TiO2. Some of the auxiliary agent CeO2-Nb2O5 is implanted by impregnation.

[0033] The catalyst comprises, by mass fraction, the following raw material components: 2-5 parts vanadium oxalate, 3-7 parts ammonium molybdate, 1-3 parts manganese nitrate, 0.2-0.5 parts cerium nitrate, 0.1-0.4 parts niobium oxalate, 0.2-0.3 parts samarium nitrate, and 1-10 parts TiO2;

[0034] The chemical formula of the low-temperature alkali metal resistant and sulfur denitrification catalyst is CeO2-Nb2O5 / (V-Mn-Sm-Mo)Ox / TiO2, wherein CeO2-Nb2O5 is supported on the surface of (V-Mn-Sm-Mo)Ox / TiO2.

[0035] In the aforementioned composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalysts, the precursor materials are ammonium molybdate, vanadium oxalate, manganese nitrate, niobium oxalate, cerium nitrate, samarium nitrate, and the support material TiO2. The dry basis mass of TiO2 in the catalyst is 80.0-85.0%; the dry basis mass of the promoter MoO3 is 3.0-10.0%; the dry basis mass of the transition metal oxide MnO2 is 1.0-3.0%; the dry basis mass of the rare earth metal oxide CeO2 is 0.3-1.20%; the dry basis mass of the transition metal oxide Nb2O5 is 0.1-1.0%; the dry basis mass of the rare earth metal oxide Sm2O3 is 0.5-1.5%; and the dry basis mass of the active material V2O5 is 2.0-5.0%.

[0036] The catalyst comprises the following raw material components by mass: 3 parts vanadium oxalate, 5 parts ammonium molybdate, 1 part manganese nitrate, 0.3 parts cerium nitrate, 0.1 parts niobium oxalate, 0.2 parts samarium nitrate, and 8 parts TiO2.

[0037] The catalyst has a homogeneous honeycomb structure and a BET ≥ 75m. 2 / g, Pv≥0.29cm 3 / g, mechanical strength: axial ≥2.0MPa, radial ≥1.3MPa.

[0038] The preparation method of the above-mentioned composite rare earth low-temperature alkali metal resistant and sulfur denitrification catalyst includes the following steps:

[0039] (1) According to the component ratio, put 0.1-0.4 parts of niobium oxalate and 0.2-0.5 parts of cerium nitrate into a paddle-type stirred tank, add 3-6 parts of 0.3-0.6 mol / L ethanol solution, set the stirring tank motor frequency to 40-60 rpm, turn on the heating device to raise the liquid temperature to 45-60℃, stir for 1-2 hours and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use;

[0040] (2) Mix 2-5 parts of vanadium oxalate, 3-7 parts of ammonium molybdate, 1-3 parts of manganese nitrate, 0.2-0.3 parts of samarium nitrate and 1-10 parts of titanium dioxide in a dry state to obtain mixture B;

[0041] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to the mixture B in step (2) and stir. Finally, adjust the pH value of the mixture to ≥7.7 and the plasticity value to 7-11 with ammonia water to obtain mixed mud C.

[0042] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, liquid silicon and titanium dioxide (TiO2) in step (2) is: (0.02-0.03): (0.01-0.04): (0.1-0.3): (0.01-0.02): (0.02-0.04): (0.03-0.05): (0.2-0.6): 1.

[0043] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene or stainless steel container for 12-24 hours at an aging temperature of 10-35℃ to obtain aged mud material.

[0044] (5) Filter the aged mud material from step (4) to remove impurities;

[0045] (6) Demold the filtered mud from step (5) into shape;

[0046] (7) Dehydrate and dry the shaped clay material in step (6); the shaped clay material is dried and dehydrated in an electric oven. The heating rate during the drying process is 3-5℃ / h, and the constant temperature zone is 80-100℃ for 30-40h.

[0047] (8) Place the dried mud blanks from step (7) into the impregnation solution A from step (1) and impregnate for 0.5-1h; during the impregnation process, use a pressure impregnation tank and pressurize the impregnation tank with N2, and maintain the pressure at 0.08-0.2MPa.

[0048] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0049] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment used is a muffle furnace, the heating rate is 15-20℃ / min, the constant temperature zone temperature is 480-530℃, and the calcination time is 24-30h.

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0051] Example 1

[0052] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0053] (1) Place 0.1 parts of niobium oxalate and 0.3 parts of cerium nitrate into a paddle-type stirred tank, and add 10L of 0.5mol / L ethanol solution. Set the stirring tank motor frequency to 40 rpm, turn on the heating device to raise the liquid temperature to 50℃, stir for 1.5h and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use, wherein the mass ratio of niobium oxalate to cerium nitrate is 0.7:1;

[0054] (2) Vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide are dry-mixed to obtain mixture B; wherein the mass ratio of vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide is 0.07:0.12:0.08:0.05:1;

[0055] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to the mixture B obtained in step (2) in stages, stir for 3 hours, then use a cooling fan to remove moisture from the mud for 18 minutes, and finally adjust the pH value to 8.0 with 20.0% ammonia water and the plasticity value to 10 to obtain mixed mud C.

[0056] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0057] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0058] (5) Filter impurities from the aged mud material in step (4). The filter screen is made of 304 stainless steel and has a size of 0.4*1.2mm.

[0059] (6) The mud material in step (5) is extruded and molded under a molding pressure of 5 MPa;

[0060] (7) The shaped clay blanks in step (6) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0061] (8) Place the dried mud material from step (7) into the pre-prepared impregnation liquid A from step (1) and impregnate for 0.5 hours. Pressurize the impregnation tank with N2 gas at a pressure of 0.1 MPa.

[0062] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0063] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0064] Example 2

[0065] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0066] (1) Place 0.3 parts of niobium oxalate and 0.3 parts of cerium nitrate into a paddle-type stirred tank, add 10L of 0.5mol / L ethanol solution, set the stirring tank motor frequency to 40 rpm, turn on the heating device to raise the liquid temperature to 50℃, stir for 1.5h and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use, wherein the mass ratio of niobium oxalate to cerium nitrate is 1:0.8;

[0067] (2) Vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide are dry-mixed and stirred to obtain mixture B for later use;

[0068] The mass ratio of the above-mentioned vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate, and titanium dioxide is 0.07:0.12:0.08:0.05:1;

[0069] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to mixture B in steps and stir for 3 hours. Then use a cooling fan to remove moisture from the mud for 18 minutes. Finally, adjust the pH value to 8.0 with 20.0% ammonia water and the plasticity value to 10 to obtain mixed mud C.

[0070] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0071] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0072] (5) Filter impurities from the aged mud material in step (4). The filter screen is made of 304 stainless steel and has a size of 0.5*1.3mm.

[0073] (6) The mud material from step (5) is extruded and molded under a molding pressure of 5.0 MPa;

[0074] (7) The shaped clay blanks in step (6) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0075] (8) Place the dried mud material from step (7) into the pre-prepared impregnation liquid A from step (1) and impregnate for 0.5 hours. Pressurize the impregnation tank with N2 gas at a pressure of 0.1 MPa.

[0076] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0077] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0078] Example 3

[0079] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0080] (1) Place 0.3 parts of niobium oxalate and 0.3 parts of cerium nitrate into a paddle-type stirred tank, add 10L of 0.5mol / L ethanol solution, set the stirring tank motor frequency to 40 rpm, turn on the heating device to raise the liquid temperature to 50℃, stir for 1.5h and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use, wherein the mass ratio of niobium oxalate to cerium nitrate is 1:0.8;

[0081] (2) Vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide are dry-mixed and stirred to obtain mixture B for later use;

[0082] The mass ratio of the above-mentioned vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate, and titanium dioxide is 0.07:0.12:0.13:0.05:1;

[0083] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to mixture B in steps and stir for 3 hours. Then use a cooling fan to remove moisture from the mud for 18 minutes. Finally, adjust the pH value to 8.0 with 20.0% ammonia water and the plasticity value to 10 to obtain mixed mud C.

[0084] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0085] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0086] (5) Filter impurities from the aged mud material in step (4). The filter screen is made of 304 stainless steel and has a size of 0.5*1.3mm.

[0087] (6) The mud material from step (5) is extruded and molded under a molding pressure of 5.0 MPa;

[0088] (7) The shaped clay blanks in step (6) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0089] (8) Place the dried mud material from step (7) into the pre-prepared impregnation liquid A from step (1) and impregnate for 0.5 hours. Pressurize the impregnation tank with N2 gas at a pressure of 0.1 MPa.

[0090] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0091] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0092] Example 4

[0093] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0094] (1) Place 0.3 parts of niobium oxalate and 0.5 parts of cerium nitrate into a paddle-type stirred tank, add 10L of 0.5mol / L ethanol solution, set the stirring tank motor frequency to 40 rpm, turn on the heating device to raise the liquid temperature to 50℃, stir for 1.5h and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use, wherein the mass ratio of niobium oxalate to cerium nitrate is 1:1;

[0095] (2) Vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide are dry-mixed and stirred to obtain mixture B for later use;

[0096] The mass ratio of the above-mentioned vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate, and titanium dioxide is 0.07:0.12:0.08:0.05:1;

[0097] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to mixture B in steps and stir for 3 hours. Then use a cooling fan to remove moisture from the mud for 18 minutes. Finally, adjust the pH value to 8.0 with 20.0% ammonia water and the plasticity value to 10 to obtain mixed mud C.

[0098] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0099] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0100] (5) Filter impurities from the aged mud material in step (4). The filter screen is made of 304 stainless steel and has a size of 0.5*1.3mm.

[0101] (6) The mud material from step (5) is extruded and molded under a molding pressure of 5.0 MPa;

[0102] (7) The shaped clay blanks in step (6) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0103] (8) Place the dried mud material from step (7) into the pre-prepared impregnation liquid A from step (1) and impregnate for 0.5 hours. Pressurize the impregnation tank with N2 gas at a pressure of 0.1 MPa.

[0104] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0105] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0106] Comparative Example 1

[0107] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0108] (1) Place 0.3 parts of niobium oxalate and 0.3 parts of cerium nitrate into a paddle-type stirred tank, add 10L of 0.5mol / L ethanol solution, set the stirring tank motor frequency to 40 rpm, turn on the heating device to raise the liquid temperature to 50℃, stir for 1.5h and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use, wherein the mass ratio of niobium oxalate to cerium nitrate is 1:0.8;

[0109] (2) Vanadium oxalate, ammonium molybdate, manganese nitrate, samarium nitrate and titanium dioxide are dry-mixed and stirred to obtain mixture B for later use;

[0110] The mass ratio of the above-mentioned vanadium oxalate, ammonium molybdate, manganese nitrate, and titanium dioxide is 0.07:0.12:0.08:1;

[0111] (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to mixture B in steps and stir for 3 hours. Then use a cooling fan to remove moisture from the mud for 18 minutes. Finally, adjust the pH value to 8.0 with 20.0% ammonia water and the plasticity value to 10 to obtain mixed mud C.

[0112] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0113] (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0114] (5) Filter impurities from the aged mud material in step (4). The filter screen is made of 304 stainless steel and has a size of 0.5*1.3mm.

[0115] (6) The mud material from step (5) is extruded and molded under a molding pressure of 5.0 MPa;

[0116] (7) The shaped clay blanks in step (6) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0117] (8) Place the dried mud material from step (7) into the pre-prepared impregnation liquid A from step (1) and impregnate for 0.5 hours. Pressurize the impregnation tank with N2 gas at a pressure of 0.1 MPa.

[0118] (9) Repeat step (7) to dry the soaked product from step (8) a second time;

[0119] (10) The dried clay blanks from step (9) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0120] Comparative Example 2

[0121] A method for preparing a composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst includes the following steps:

[0122] (1) Mixing vanadium oxalate, ammonium molybdate and titanium dioxide in a dry state to obtain mixture A;

[0123] The mass ratio of the above-mentioned vanadium oxalate, ammonium molybdate, and titanium dioxide is 0.08:0.15:1;

[0124] (2) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silicon to mixture A in steps, stir for 3.5h, then use a cooling fan to remove moisture from the mud for 15min, and finally adjust the pH value to 8.0 and the plasticity value to 10 with 20.0% ammonia water to obtain mixed mud B.

[0125] The mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, and liquid silicon is 0.3:0.8:5.0:0.5:1.0:0.8:3.0.

[0126] (3) The mixed mud material B in step (2) is moisturized and sealed in a polyethylene barrel for 20 hours at an aging temperature of 25°C to obtain aged mud material.

[0127] (4) Filter impurities from the aged mud material in step (3). The filter screen is made of 304 stainless steel and has a size of 0.4*1.2mm.

[0128] (5) The mud material from step (4) is extruded and molded under a molding pressure of 5.0 MPa;

[0129] (6) The shaped clay blanks in step (5) are dehydrated and dried. The heating rate during the drying process is 3℃ / h, and the constant temperature zone is 90℃ for 30h.

[0130] (7) The dried clay blanks from step (6) are subjected to high-temperature calcination. The calcination equipment is a muffle furnace with a heating rate of 15℃ / min, a constant temperature zone temperature of 510℃, and a calcination time of 25h.

[0131] Test content

[0132] (1) Weigh 0.7g of potassium oxide and dissolve it in 1000mL of deionized water. Stir evenly to obtain alkali metal solution A. Cut 75*75*300mm honeycomb catalyst samples from the catalyst samples obtained in Examples 1-4 and Comparative Examples 1-2 and place them in alkali metal solution A for 5h and then dry them. The heating rate during the drying process is 5℃ / h, the constant temperature zone is 95℃, and it is maintained for 5h. After drying, high-temperature calcination is carried out. The calcination equipment is a muffle furnace, the heating rate is 18℃ / min, the constant temperature zone temperature is 500℃, and the calcination time is 12h.

[0133] (2) The products impregnated with alkali metal solution A in Examples 1-4 and Comparative Examples 1-2 in step (1) above were calcined and then their performance was tested in the laboratory using a microreactor. The flue gas temperature was 160℃ and 180℃, and the space velocity was 5000h. -1 The NH3 / NO molar ratio is 1.05:1, and the NO concentration is 300 mg / Nm³. 3Under operating conditions, the gas mixing method in Table 1 was used to conduct continuous performance tests for 72 hours. The results of the denitrification performance test are shown in Tables 2 and 3.

[0134] Table 1. Gas mixing methods used in the denitrification performance tests of Examples 1-4 and Comparative Examples 1-2.

[0135]

[0136]

[0137] Table 2 shows the denitrification efficiency of the denitrification catalysts in Examples 1-4 and Comparative Examples 1-2 when the flue gas temperature is 180℃.

[0138]

[0139] Table 3 shows the denitrification efficiency of the denitrification catalysts in Examples 1-4 and Comparative Examples 1-2 when the flue gas temperature is 160℃.

[0140]

[0141] As can be seen from the data in Tables 2 and 3, the composite rare earth low-temperature alkali metal-resistant and sulfur-resistant denitrification catalyst of this invention, the V2O5 / MoO3-TiO2 catalyst incorporating Sm element, can inhibit the conversion of SO2 to SO3, thus significantly reducing the amount of NH4HSO4 generated. CeO2 utilizes Ce 4+ and Ce 3+ The redox transformation of Sm can improve the oxygen storage capacity of Mn-based catalysts and promote oxygen migration in SCR. The incorporation of Sm not only effectively inhibits the sulfation of the active component but also increases the SCR reaction pathway of the catalyst, which is beneficial for improving resistance to SO2 poisoning. Under the action of SO2, more bronsted acid sites will form on the surface of the Sm-Mn catalyst, adsorbing NH3 and generating more NH4+. 4+ It can undergo SCR reaction with gaseous or weakly adsorbed NO, thus maintaining a certain catalytic activity of the Sm-Mn catalyst and enhancing its resistance to SO2 poisoning. After doping with rare earth metal oxides such as MnO2, Sm2O3, and CeO2, it can achieve SCR reaction at 160℃ and 180℃, with sulfur (80mg) and alkali metal (K2O cumulative value 2.0mg / Nm). 3 Under flue gas conditions, the NOx removal rate can reach up to 95.8%. The catalyst manufactured in this invention, as tested by electron microscopy, surface area analyzer, and pressure tester, has a material BET ≥ 75m. 2 / g, see details Figure 1 Pv≥0.29cm 3 / g, see details Figure 2 Mechanical strength: Axial ≥2.0MPa, Radial ≥1.3MPa, see details. Figure 3 and 4The grain distribution is uniform. See details. Figure 5 It fully meets the market demand for commercial denitrification SCR catalysts in the field of low-temperature flue gas denitrification, and has great commercial value in practical applications, especially suitable for low-temperature flue gas denitrification in non-power industries.

[0142] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst, characterized in that, The catalyst is made by mixing active material V2O5, auxiliary agent (Mn-Sm-Mo)Ox and support material TiO2, and some of the auxiliary agent CeO2-Nb2O5 is implanted by impregnation. The catalyst comprises, by mass fraction, the following raw material components: 2-5 parts vanadium oxalate, 3-7 parts ammonium molybdate, 1-3 parts manganese nitrate, 0.2-0.5 parts cerium nitrate, 0.1-0.4 parts niobium oxalate, 0.2-0.3 parts samarium nitrate, and 1-10 parts TiO2; The chemical formula of the low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst is CeO2-Nb2O5 / (V-Mn-Sm-Mo)Ox / TiO2, wherein CeO2-Nb2O5 is supported on the surface of (V-Mn-Sm-Mo)Ox / TiO2.

2. The composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst according to claim 1, characterized in that, The catalyst comprises the following raw material components by mass: 3 parts vanadium oxalate, 5 parts ammonium molybdate, 1 part manganese nitrate, 0.3 parts cerium nitrate, 0.1 parts niobium oxalate, 0.2 parts samarium nitrate, and 8 parts TiO2.

3. The composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst according to claim 1, characterized in that, The catalyst has a homogeneous honeycomb structure, BET≥75m² / g, Pv≥0.29cm³ / g, and mechanical strength: axial ≥2.0MPa, radial ≥1.3MPa.

4. The preparation method of the composite rare earth low-temperature alkali metal resistant and sulfur resistant denitrification catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: (1) By mass fraction, put 0.1-0.4 parts of niobium oxalate and 0.2-0.5 parts of cerium nitrate into a paddle-type stirred tank, add 3-6 parts of 0.3-0.6 mol / L ethanol solution, set the stirring tank motor frequency to 40-60 rpm, turn on the heating device to raise the liquid temperature to 45-60℃, stir for 1-2 hours and then transfer to the impregnation tank to obtain pre-prepared impregnation solution A for later use; (2) Mix 2-5 parts of vanadium oxalate, 3-7 parts of ammonium molybdate, 1-3 parts of manganese nitrate, 0.2-0.3 parts of samarium nitrate and 1-10 parts of titanium dioxide in a dry state to obtain mixture B; (3) Add deionized water, stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC and liquid silica to mixture B in step (2) and stir. Finally, adjust the pH of the mixture to ≥ 7.7, with a plasticity value of 7-11, yields mixed clay material C; (4) The mixed mud material C in step (3) is moisturized and sealed in a polyethylene or stainless steel container for 12-24 hours at an aging temperature of 10-35℃ to obtain aged mud material. (5) Filter the aged mud material from step (4) to remove impurities; (6) Demold the filtered mud from step (5) into shape; (7) Dehydrate and dry the shaped clay material from step (6); (8) Place the dried clay blank from step (7) into the impregnation solution A from step (1) and impregnate for 0.5-1h; (9) Repeat step (7) to dry the soaked product from step (8) a second time; (10) The dried clay blanks from step (9) are calcined at high temperature.

5. The preparation method of the composite rare earth low-temperature alkali metal resistant and sulfur resistant denitrification catalyst according to claim 4, characterized in that, In step (3), the mass ratio of stearic acid, lactic acid, glass fiber, polypropylene fiber, polyethylene oxide, CMC, liquid silicon and titanium dioxide (TiO2) in step (2) is 0.02-0.03:0.01-0.04:0.1-0.3:0.01-0.02:0.02-0.04:0.03-0.05:0.2-0.6:

1.

6. The preparation method of the composite rare earth low-temperature alkali metal resistant and sulfur resistant denitrification catalyst according to claim 4, characterized in that, In step (7), the molded clay material is dried and dehydrated in an electric oven. The heating rate during the drying process is 3-5℃ / h, and the constant temperature zone is 80-100℃ for 30-40h.

7. The preparation method of the composite rare earth low-temperature alkali metal resistant and sulfur-resistant denitrification catalyst as described in claim 4, characterized in that, In step (8), a pressure impregnation tank is used during the impregnation process. The impregnation tank is pressurized with N2 and the pressure is maintained at 0.08-0.2 MPa.

8. The preparation method of the composite rare earth low-temperature alkali metal resistant and sulfur resistant denitrification catalyst according to claim 4, characterized in that, In step (10), the calcination equipment used during high-temperature calcination is a muffle furnace with a heating rate of 15-20℃ / min, a constant temperature zone temperature of 480-530℃, and a calcination time of 24-30h.

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