CO-SCR denitration catalyst and preparation method thereof

Abstract

The invention provides a CO-SCR denitration catalyst and a preparation method thereof, and relates to the technical field of flue gas denitration, and the preparation method comprises the following steps: S1, placing an active component precursor salt in water, and heating and stirring to obtain an active component precursor solution; the active component precursor salt comprises transition metal oxide precursor salt and rare earth oxide precursor salt; s2, adding a composite oxide carrier into the active component precursor solution while stirring, then adjusting the pH value, and carrying out high-speed stirring to obtain a mixed material; s3, adding a forming aid into the mixed material, and stirring to obtain a wet material block; and S4, carrying out molding treatment on the wet material block, and drying and roasting to obtain the CO-SCR denitration catalyst. The catalyst has the advantages of high efficiency, high mechanical strength, low production cost and the like, and can be suitable for treating flue gas containing high-concentration CO in steel sintering, coke ovens, industrial boilers and the like.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, and in particular to a CO-SCR denitrification catalyst and its preparation method. Background Technology

[0002] Nitrogen oxides (NO) x Nitrogen oxides (NOx) are one of the main pollutants causing air pollution. On the one hand, nitrogen oxides (NOx) in the atmosphere... x When nitrogen oxides (NOx) and hydrocarbons reach a certain concentration, they undergo a series of chemical reactions under sunlight to form photochemical smog. On the other hand, nitrogen oxides (NOx) in the atmosphere... x Nitric acid and nitrate fine particulate matter can be formed, accelerating the deterioration of regional acid rain. Currently, the most commonly used denitrification method is Selective Catalytic Reduction (SCR), which uses ammonia (NH3) or urea as a reducing agent to remove nitrogen oxides (NOx) from flue gas under the action of a catalyst. x This technology converts flue gas into nitrogen and water for denitrification. While it offers significant denitrification benefits, it suffers from drawbacks such as high energy consumption (typically requiring flue gas to be heated to over 250°C) and secondary pollution from ammonia escape.

[0003] Therefore, research and development can utilize CO in sintering flue gas to catalytically reduce NO. x To remove NO x The development of CO-SCR denitrification catalysts is of great significance.

[0004] Currently, most CO-SCR denitration catalysts use noble metals as active components. For example, patent CN202211379214.5 discloses a monolithic wire mesh catalyst with single-atom clusters of noble metals for CO to reduce NO. This monolithic catalyst uses ultrathin TiO2 nanosheets grown in situ on a Ti mesh as a support, and one or more single-atom cluster noble metals such as Pt, Rh, Pd, Ir, and Ru as active components. It is prepared by in-situ growth using raw materials such as urea, chloroplatinic acid, sodium hexachlororhodium, palladium nitrate, chloroiridic acid, and ruthenium nitrate. Compared to expensive noble metals, transition metals have attracted widespread attention in the field of CO-SCR catalysis technology due to their low cost, availability, and multiple valence states.

[0005] Patent CN202310799144.7 discloses a multifunctional catalyst for medium- and low-temperature flue gas purification and its preparation method. The multifunctional catalyst is characterized by comprising CuO, Co3O4, and MgO, wherein the mass of CuO accounts for 0.5%-10% of the mass of the Co3O4-MgO (CoMgO) composite oxide support, and the molar ratio x of Mg to the total amount of Co-Mg metal elements in the composite oxide support is 0.05-0.25. This multifunctional catalyst is simultaneously applied to CO catalytic oxidation and CO-NO reduction reactions, exhibiting good medium- and low-temperature catalytic activity. However, the Co3O4-MgO (CoMgO) composite oxide support in this patent has a small specific surface area and poor structural stability, limiting its application range.

[0006] Patent 202311174426.4 discloses a single-atom catalyst, its preparation method and application. The single-atom catalyst includes a support and a single-atom active component loaded on the surface of the support. The single-atom active component is selected from at least one of copper, iron and manganese. The support is a composite oxide of alumina and cerium oxide. However, the composite oxide support of alumina and cerium oxide is difficult to form and cannot be industrialized.

[0007] However, the catalysts provided by the above patents all have drawbacks such as complex manufacturing processes and inability to be industrially produced. Therefore, there is an urgent need for a CO-SCR denitrification catalyst that is inexpensive and readily available, has a simple and reliable production process, high yield, and can be used industrially. Summary of the Invention

[0008] To achieve the removal of NO via CO catalytic reduction, this invention provides a CO-SCR denitrification catalyst. This catalyst uses a composite oxide of titanium dioxide and alumina as a support and transition metal oxides combined with rare earth oxides as the active material, enabling denitrification at low temperatures (below 200°C). This catalyst possesses advantages such as high efficiency, high mechanical strength, and low production cost, and is suitable for treating flue gas containing high concentrations of CO from steel sintering, coke ovens, and industrial boilers.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention provides a method for preparing a CO-SCR denitrification catalyst, comprising the following steps:

[0011] S1: Place the active component precursor salt in water and heat and stir to obtain an active component precursor solution;

[0012] The active component precursor salts include transition metal oxide precursor salts and rare earth oxide precursor salts.

[0013] S2: The composite oxide carrier is added to the active component precursor solution while stirring. After the process is completed, the pH is adjusted and the mixture is stirred at high speed to obtain the mixture.

[0014] S3: Add the molding aid to the mixture and stir to obtain a wet material mass;

[0015] S4: The wet material clumps are shaped, dried and calcined to obtain a CO-SCR denitrification catalyst.

[0016] Furthermore, based on the above technical solution, the mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is (1-2):(1-4).

[0017] And / or, the transition metal oxide precursor salt includes one or more of the following: copper oxide precursor salt copper acetate, copper oxide precursor salt copper nitrate, copper oxide precursor salt basic copper carbonate, manganese oxide precursor salt manganese nitrate, and zirconium oxide precursor salt zirconium nitrate.

[0018] And / or, the rare earth oxide precursor salt includes one or more of cerium oxide precursor salt cerium nitrate and lanthanum oxide precursor salt lanthanum nitrate;

[0019] And / or, the molding aids include at least two of monoethanolamine, stearic acid, lactic acid, limestone, carboxymethyl cellulose, pulp, glass fiber, polyethylene oxide, and aminocellulose.

[0020] Furthermore, based on the above technical solution, the composite oxide carrier is a composite oxide of alumina and titanium oxide;

[0021] The preparation method of the composite oxide of titanium dioxide and aluminum oxide includes the following steps:

[0022] (1) Add aluminum salt and titanium salt to water and stir to obtain a mixed salt solution;

[0023] (2) Add the precipitant to the mixed salt solution and stir until the pH is 8.5-9. Then let it stand and age to obtain the slurry.

[0024] (3) The slurry is pressure filtered to obtain a filter cake, which is then dried and calcined to obtain a composite oxide of titanium dioxide and aluminum oxide.

[0025] Furthermore, based on the above technical solution, the aluminum salt includes Al(NO3)3·9H2O;

[0026] And / or, the titanium salt includes TiOSO4;

[0027] And / or, the mass ratio of the aluminum salt to the titanium salt is 1:(1-2);

[0028] And / or, the concentration of the mixed salt solution is 0.1-1 mol / L;

[0029] And / or, the precipitant is ammonia solution with a volume percentage concentration of 22-27%;

[0030] And / or, in step (2), the stirring speed is 200-300 rpm;

[0031] And / or, in step (2), after stirring until the pH is 8.5-9, continue stirring for 25-35 minutes, and then allow to stand for aging;

[0032] And / or, the settling and aging time is 2-4 hours;

[0033] And / or, the filtration is performed using a plate and frame filter press;

[0034] And / or, the drying refers to drying the filter cake until the moisture content of the powder is ≤5%, and then stopping the drying process;

[0035] And / or, the calcination is carried out in a rotary kiln at a temperature of 450-550℃ for 3-5 hours.

[0036] Furthermore, based on the above technical solution, in step S1, the heating and stirring temperature is 80-100℃;

[0037] And / or, the mass percentage concentration of the active component precursor solution is 40%-50%;

[0038] And / or, in step S2, adjusting pH means using ammonia to adjust the pH value to 7-8; the volume percentage concentration of ammonia is 20-25%;

[0039] And / or, in step S2, the high-speed stirring speed is 300-600 rpm and the stirring time is 60-90 min;

[0040] And / or, in step S3, the stirring includes:

[0041] First, heat and stir, then stir at low speed;

[0042] The heating and stirring temperature is 70-90℃, the stirring speed is 300-600rpm, and the stirring time is 30-40min;

[0043] The low-speed stirring speed is 120-300 rpm, and the stirring time is 60-90 min.

[0044] Furthermore, based on the above technical solution, taking the total mass of the carrier, active component precursor salt, and molding aid as 100%, the content of the active component precursor salt is 8-35 wt%, the content of the carrier is 52-83 wt%, and the content of the molding aid is 5-20 wt%.

[0045] Furthermore, based on the above technical solution, in step S4, the molding process includes: using an extruder to extrude the wet material mass into a perforated plate with a four-leaf clover structure, and then drying and calcining to obtain the finished four-leaf clover catalyst.

[0046] Alternatively, the wet material pellets can be coated onto a stainless steel mesh, dried, and calcined to obtain a finished flat-plate catalyst.

[0047] Alternatively, the wet material can be placed in a kneader with a filter screen for filtration and pre-extrusion into brick-shaped clay. The pre-extruded brick-shaped clay can then be placed in a vacuum extruder, extruded into shape as a whole through a mold, cut into sections, dried, and calcined to obtain a honeycomb catalyst product.

[0048] Furthermore, based on the above technical solution, the drying temperature of the clover-shaped catalyst is 70-90℃, and the drying time is 16-24h.

[0049] The drying temperature of the plate-type catalyst is 90-120℃, and the drying time is 2-4h.

[0050] The drying temperature of the honeycomb catalyst is 60-70℃, and the drying time is 120-144h.

[0051] The calcination temperature of the clover-shaped catalyst is 400-500℃, and the calcination time is 2-4h.

[0052] The calcination temperature of the plate-type catalyst is 400-500℃, and the calcination time is 4-8h;

[0053] The honeycomb catalyst is calcined at a temperature of 400-500℃ for 8-12 hours.

[0054] The present invention also provides a CO-SCR denitrification catalyst prepared by the method described above.

[0055] Furthermore, based on the above technical solution, the active components in the CO-SCR denitrification catalyst include transition metal oxides and rare earth oxides, and the active components are uniformly dispersed on the support.

[0056] The transition metal oxide includes one or more of copper oxide, manganese oxide, and zirconium oxide;

[0057] The rare earth oxides include one or more of cerium oxide and lanthanum oxide.

[0058] The present invention provides a CO-SCR denitrification catalyst and its preparation method, which have the following beneficial effects:

[0059] 1. Compared with the traditional NH3-SCR denitrification technology, the reducing agent CO used in this invention can come from industrial waste gas (such as iron and steel sintering flue gas and coking flue gas), without the need to add ammonia (NH3) or urea, and there is no risk of secondary pollution from ammonia escape.

[0060] 2. The CO-SCR denitrification catalyst provided by this invention has significant denitrification efficiency in the range of 150-300℃, and is suitable for the treatment of flue gas containing high concentrations of CO, such as steel sintering, coke ovens, and industrial boilers.

[0061] 3. The preparation method of the CO-SCR denitrification catalyst provided by the present invention has a simple production process, reliable technology, high yield, and can be used for industrial applications and large-scale industrial use. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0063] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0064] According to a first aspect of the present invention, a method for preparing a CO-SCR denitrification catalyst is provided, comprising the following steps:

[0065] S1: Place the active component precursor salt in water and heat and stir to obtain an active component precursor solution;

[0066] The active component precursor salts include transition metal oxide precursor salts and rare earth oxide precursor salts.

[0067] S2: The composite oxide carrier is added to the active component precursor solution while stirring. After the process is completed, the pH is adjusted and the mixture is stirred at high speed to obtain the mixture.

[0068] S3: Add the molding aid to the mixture and stir to obtain a wet material mass;

[0069] S4: The wet material clumps are shaped, dried and calcined to obtain a CO-SCR denitrification catalyst.

[0070] As an optional embodiment of the present invention, the mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is (1-2):(1-4), such as 1.2:1.5, 1.2:1.7, 1.2:2, 1.2:2.5, 1.2:3, 1.2:3.5, 1.2:3.7, 1.5:1.5, 1.5:1.7, 1.5:2, 1.5:2.5, 1.5:3, 1.5:3.5, 1.5:3.7, 1.7:1.5, 1.7:1.7, 1.7:2, 1.7:2.5, 1.7:3, 1.7:3.5, 1.7:3.7, etc.

[0071] Specifically, after the above preparation method, the transition metal oxide precursor salt is transformed into a transition metal oxide, which is the main active component of the catalyst, and its content directly affects the activity of the catalyst.

[0072] After being prepared using the above method, rare earth oxide precursor salts are transformed into rare earth oxides, which play a role in improving the structural stability of the catalyst and preventing the transition metal oxides from sintering at high temperatures. An appropriate ratio of rare earth oxide precursor salts to transition metal oxide precursor salts helps maintain the structural integrity of the catalyst, ensuring its stable performance during long-term use.

[0073] If the mass ratio of transition metal oxide precursor salt to rare earth oxide precursor salt is too high (e.g., 2.3:1), the active sites may become too concentrated, affecting the selectivity of the reaction and leading to a decrease in catalyst activity or even deactivation. If the mass ratio of transition metal oxide precursor salt to rare earth oxide precursor salt is too low (e.g., 1:5), it may not be able to provide enough active sites, thus reducing catalytic efficiency.

[0074] As an optional embodiment of the present invention, the transition metal oxide precursor salt includes one or more of the following: copper oxide precursor salt copper acetate, copper oxide precursor salt copper nitrate, copper oxide precursor salt basic copper carbonate, manganese oxide precursor salt manganese nitrate, and zirconium oxide precursor salt zirconium nitrate.

[0075] The rare earth oxide precursor salt includes one or more of cerium oxide precursor salt cerium nitrate and lanthanum oxide precursor salt lanthanum nitrate.

[0076] The molding aids include at least two of the following: monoethanolamine, stearic acid, lactic acid, limestone, carboxymethyl cellulose, pulp, glass fiber, polyethylene oxide, and aminocellulose.

[0077] As an optional embodiment of the present invention, the composite oxide carrier is an aluminum oxide and titanium oxide composite oxide;

[0078] The preparation method of the composite oxide of titanium dioxide and aluminum oxide includes the following steps:

[0079] (1) Add aluminum salt and titanium salt to water and stir until dissolved to obtain a mixed salt solution;

[0080] (2) Add the precipitant to the mixed salt solution and stir until the pH is 8.5-9. Then let it stand and age to obtain the slurry.

[0081] (3) The slurry is pressure filtered to obtain a filter cake, which is then dried and calcined to obtain a composite oxide of titanium dioxide and aluminum oxide.

[0082] As an optional embodiment of the present invention, the aluminum salt includes Al(NO3)3·9H2O;

[0083] And / or, the titanium salt includes TiOSO4;

[0084] And / or, the mass ratio of the aluminum salt to the titanium salt is 1:(1-2), such as 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, etc.;

[0085] And / or, the concentration of the mixed salt solution is 0.1-1 mol / L (e.g., 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, etc.), that is, each liter of the mixed salt solution contains 0.1-1 mol of total salt (aluminum salt and titanium salt);

[0086] And / or, the precipitant is ammonia solution with a volume percentage concentration of 22-27% (e.g., 23%, 24%, 25%, 26%, etc.);

[0087] And / or, in step (2), the stirring speed is 200-300 rpm;

[0088] And / or, in step (2), after stirring until the pH is 8.5-9, continue stirring for 25-35 minutes (e.g., 27 minutes, 30 minutes, 33 minutes, etc.), and then allow to stand for aging;

[0089] And / or, the settling and aging time is 2-4 hours (e.g., 2.5 hours, 3 hours, 3.5 hours, etc.);

[0090] And / or, the filtration is performed using a plate and frame filter press;

[0091] And / or, the drying refers to drying the filter cake until the moisture content of the powder is ≤5%, and then stopping the drying process;

[0092] And / or, the calcination is carried out in a rotary kiln at a temperature of 450-550℃ (e.g., 470℃, 500℃, 530℃, etc.) and held for 3-5 hours (e.g., 3.5 hours, 4 hours, 4.5 hours, etc.).

[0093] Specifically, in the preparation method provided by this invention, a composite oxide of titanium dioxide and alumina is used as the support because simply mixing titanium dioxide and alumina monomers physically results in an insufficiently tight interface, making them prone to defects or separation, affecting structural stability, and having a small specific surface area. This leads to poor dispersion of the active components loaded on the support and low catalytic activity. In contrast, this invention prepares a composite oxide by mixing titanium dioxide and alumina, which has a larger specific surface area, providing more active sites and better diffusion performance for chemical reactions, thus providing a favorable environment for the reaction. Furthermore, the composite oxide has a more stable structure, better supporting the active components and preventing aggregation or sintering under high temperature or high flow rate conditions, thereby improving the catalyst's lifespan and stability.

[0094] As an optional embodiment of the present invention, in step S1, the heating and stirring temperature is 80-100℃ (e.g., 85℃, 90℃, 95℃, etc.).

[0095] As an optional embodiment of the present invention, the mass percentage concentration of the active component precursor solution is 40%-50% (e.g., 42%, 45%, 47%, etc.).

[0096] As an optional embodiment of the present invention, in step S2, the stirring speed of the composite oxide carrier adding the active component precursor solution while stirring is 120-300 rpm (e.g., 150 rpm, 200 rpm, 250 rpm, etc.).

[0097] In step S2, adjusting the pH means using ammonia to adjust the pH value to 7-8; the volume percentage concentration of the ammonia is 20-25% (e.g., 22%, 23%, 24%, etc.).

[0098] In step S2, the high-speed stirring speed is 300-600 rpm (e.g., 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, etc.), and the stirring time is 60-90 min (e.g., 65 min, 70 min, 80 min, etc.) until the active substance and the carrier are fully mixed.

[0099] In an optional embodiment of the present invention, step S3, the stirring includes:

[0100] First, heat and stir, then stir at low speed;

[0101] The heating and stirring temperature is 70-90℃ (e.g., 75℃, 80℃, 85℃, etc.), the stirring speed is 300-600rpm (e.g., 350rpm, 400rpm, 450rpm, 500rpm, 550rpm, etc.), and the stirring time is 30-40min (33min, 35min, 37min, etc.).

[0102] The low-speed stirring speed is 120-300 rpm (150 rpm, 200 rpm, 250 rpm, 270 rpm, etc.), and the stirring time is 60-90 min (e.g., 65 min, 70 min, 80 min, 85 min, etc.).

[0103] Specifically, the purpose of heating and stirring is to allow various molding aids to be more fully integrated. However, molding aids such as monoethanolamine or polyethylene oxide, whose performance is affected by high temperatures, are added to the system after heating and stirring are completed and then stirred at low speed.

[0104] Furthermore, in step S3, before adding the molding aid, the mixer speed needs to be adjusted to 200 rpm and stirred at low speed for 25 minutes.

[0105] As an optional embodiment of the present invention, the total mass of the carrier, active component precursor salt, and molding aid comprises 8-35 wt% (e.g., 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 33 wt%, etc.) of the active component precursor salt, 52-83 wt% (e.g., 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, etc.) of the carrier, and 5-20 wt% (e.g., 7 wt%, 10 wt%, 13 wt%, 15 wt%, 17 wt%, etc.) of the molding aid.

[0106] Specifically, the content of the active component precursor salt is limited to 8-35 wt% in this invention because too little content will lead to weak catalytic activity, while too much content will cause the catalytic activity to decrease. Moreover, too much active component will affect the strength of the product after catalyst molding.

[0107] Furthermore, this invention limits the support content to 52-83 wt% because the support content directly affects the porosity and diffusion performance of the catalyst. An appropriate support content ensures that reactants can effectively diffuse to the active sites, thereby optimizing reaction performance. The support plays a supporting role in the catalyst. If the support content is too high, the content of the active component will be relatively reduced, leading to decreased catalyst activity and an inability to effectively promote the target reaction. The support not only provides physical support but also affects the pore structure and specific surface area of ​​the catalyst. Therefore, if the support content is too low, the catalyst structure may be unstable and prone to breakage, especially under high temperature or high stress conditions, affecting the catalyst's lifespan.

[0108] Furthermore, the content of the molding aid is limited to 5-20 wt% in this invention because the catalyst of this invention is an industrial product with a certain structural shape, and molding aids need to be introduced during the production process to increase the plasticity of the material. At the same time, the catalyst of this invention needs to be used in high-temperature, high-pressure, or high-flow-rate flue gas environments, thus requiring higher mechanical strength and erosion resistance. Molding aids can significantly enhance the structural stability of the catalyst, preventing breakage or pulverization under flue gas erosion, thereby extending the catalyst's service life. If the aid content is too low, the catalyst may fail to form or its structure may be insufficiently stable, making it prone to breakage or pulverization in high-temperature or high-flow-rate flue gas environments, affecting the catalyst's service life and stability.

[0109] As an optional embodiment of the present invention, in step S4, the molding process includes: extruding the wet material mass using an extruder to extrude a perforated plate with a four-leaf clover structure, and then drying and calcining it to obtain the four-leaf clover catalyst product.

[0110] Alternatively, the wet material pellets can be coated onto a stainless steel mesh, dried, and calcined to obtain a finished flat-plate catalyst.

[0111] Alternatively, the wet material can be placed in a kneader with a filter screen for filtration and pre-extrusion into brick-shaped clay. The pre-extruded brick-shaped clay can then be placed in a vacuum extruder, extruded into shape as a whole through a mold, cut into sections, dried, and calcined to obtain a honeycomb catalyst product.

[0112] As an optional embodiment of the present invention, the drying temperature of the clover-shaped catalyst is 70-90℃ (e.g., 75℃, 80℃, 85℃, etc.), and the drying time is 16-24h (e.g., 18h, 20h, 22h, etc.).

[0113] The drying temperature of the plate-type catalyst is 90-120℃ (e.g., 95℃, 100℃, 115℃, etc.), and the drying time is 2-4h (e.g., 2.5h, 3h, 3.5h, etc.).

[0114] The drying temperature of the honeycomb catalyst is 60-70℃ (e.g., 62℃, 65℃, 67℃, etc.), and the drying time is 120-144h (e.g., 125h, 130h, 140h, etc.).

[0115] The calcination temperature of the clover-shaped catalyst is 400-500℃ (e.g., 420℃, 450℃, 470℃, etc.), and the calcination time is 2-4h (e.g., 2.5h, 3h, 3.5h, etc.).

[0116] The calcination temperature of the plate-type catalyst is 400-500℃ (e.g., 420℃, 450℃, 470℃, etc.), and the calcination time is 4-8h (e.g., 5h, 6h, 7h, etc.).

[0117] The calcination temperature of the honeycomb catalyst is 400-500℃ (e.g., 420℃, 450℃, 470℃, etc.), and the calcination time is 8-12h (e.g., 9h, 10h, 11h, etc.).

[0118] After calcination, the catalyst is slowly cooled to obtain the catalyst described in this invention.

[0119] According to a second aspect of the present invention, a CO-SCR denitrification catalyst prepared by the method described above is provided.

[0120] As an optional embodiment of the present invention, the active components in the CO-SCR denitrification catalyst include transition metal oxides and rare earth oxides, and the active components are uniformly dispersed on the support.

[0121] The transition metal oxide includes one or more of copper oxide, manganese oxide, and zirconium oxide;

[0122] The rare earth oxides include one or more of cerium oxide and lanthanum oxide.

[0123] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0124] First, it should be noted that the composite oxide carriers used in the embodiments of the present invention are all composite oxides of alumina and titanium oxide, and the preparation method of the composite oxides of titanium oxide and alumina includes the following steps:

[0125] (1) Add Al(NO3)3·9H2O and TiOSO4 in a mass ratio of 1:1.3 to deionized water and stir until dissolved to obtain a mixed salt solution with a concentration of 1 mol / L.

[0126] (2) Add 25% ammonia water by volume to the mixed salt solution and stir at 200 rpm until the pH reaches 9. Continue stirring for 30 min and let stand for 3 h to obtain the slurry.

[0127] (3) The slurry is pressed and filtered to obtain a filter cake. The filter cake is dried until the moisture content of the powder is ≤5%. The drying is stopped. The filter cake is calcined in a rotary kiln at a temperature of 500℃ for 5 hours to obtain a composite oxide of titanium oxide and aluminum oxide.

[0128] Example 1

[0129] This embodiment provides a CO-SCR denitrification catalyst, comprising active components (copper oxide, manganese oxide, and cerium oxide) and a composite oxide support; the active components are supported on the composite oxide support.

[0130] This embodiment also provides a method for preparing a CO-SCR denitrification catalyst, comprising the following steps:

[0131] (1) Preparation of aqueous solution of active component precursor: Heat pure water to 90°C, add active component precursor salt while stirring, and let it dissolve completely. This solution is called active component precursor solution A.

[0132] The active component precursor salts include transition metal oxide precursor salts and rare earth oxide precursor salts;

[0133] The transition metal oxide precursor salt includes 25.10 kg of copper oxide precursor salt copper acetate and 43.31 kg of manganese oxide precursor salt manganese nitrate.

[0134] The rare earth oxide precursor salt includes 63.08 kg of cerium oxide precursor salt cerium nitrate;

[0135] The mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is 1.08:1;

[0136] The above-mentioned active component precursor salt was dissolved to prepare an aqueous solution of active component precursor with a concentration of 45%.

[0137] (2) Loading of active material: Add 360 kg of composite oxide carrier of titanium dioxide and aluminum oxide to the mixer, add the active component precursor solution A while stirring at 200 rpm, add 20% ammonia water by volume, adjust the pH value to 7.0, stir at high speed for 35 minutes (400 rpm) until the active material and carrier are fully mixed.

[0138] (3) Introduce molding aids: Adjust the speed of the mixer to 200 rpm and stir at low speed for 25 minutes. Then add 6 kg of lactic acid, 40 kg of glass fiber, 5 kg of pulp, 1.2 kg of carboxymethyl cellulose (CMC), and 50 kg of limestone in sequence. Heat and stir at 80°C for 75 minutes at a speed of 400 rpm. The time interval between each addition is 5 minutes.

[0139] (4) Material mixing: Add 7.5 kg monoethanolamine and 6 kg polyethylene oxide (PEO) to the mixer in sequence and stir at low speed for 25 min (200 rpm) to obtain a wet material with certain plasticity;

[0140] (5) Catalyst molding: The wet material is placed in a kneader with a filter screen for filtration and pre-extrusion into brick mud. The pre-extruded brick mud is placed in a vacuum extruder and extruded as a whole through a mold. After being cut into sections and dried, a honeycomb catalyst blank is obtained.

[0141] Of which, based on the total mass of the carrier, active component precursor salt and molding aid, the active component precursor salt content is 21.66 wt%, the carrier content is 59.29 wt%, and the molding aid content is 19.05 wt%.

[0142] The honeycomb catalyst preform has dimensions of 150mm×150mm×L, where L ranges from 500 to 1300mm.

[0143] (6) Drying: The CO-SCR catalyst blank is placed in a drying chamber. The drying temperature of the honeycomb catalyst is 65°C and the drying time is 130h.

[0144] (7) Calcination: The dried CO-SCR catalyst preform is placed in a mesh belt kiln for calcination at a temperature of 450℃ for 10h to obtain the finished CO-SCR catalyst, denoted as CAT1.

[0145] Example 2

[0146] This embodiment provides a CO-SCR denitrification catalyst, comprising active components (copper oxide, manganese oxide, cerium oxide, and lanthanum oxide) and a composite oxide support; the active components are supported on the composite oxide support.

[0147] This embodiment also provides a method for preparing a CO-SCR denitrification catalyst, comprising the following steps:

[0148] (1) Preparation of aqueous solution of active component precursor: Heat pure water to 90°C, add active component precursor while stirring, and let it dissolve completely. This solution is called active component precursor solution A.

[0149] The active component precursor salts include transition metal oxide precursor salts and rare earth oxide precursor salts;

[0150] The transition metal oxide precursor salts include: 37.97 kg of copper oxide precursor salt copper nitrate and 43.31 kg of manganese oxide precursor salt manganese nitrate.

[0151] The rare earth oxide precursor salt includes 75.69 kg of cerium oxide precursor salt cerium nitrate and 6.65 kg of lanthanum oxide precursor salt lanthanum nitrate.

[0152] The mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is 1:1.01;

[0153] The above-mentioned active component precursor salt was dissolved and prepared into an aqueous solution of active component precursor with a concentration of 50%.

[0154] (2) Loading of active material: Add 417.5 kg of composite oxide carrier of titanium oxide and aluminum oxide to the mixer, add active solution A while stirring at 200 rpm, add 20% ammonia water by volume, adjust the pH value to 7.5, stir at high speed for 40 minutes (600 rpm) until the active material and carrier are fully mixed.

[0155] (3) Introduce molding aids: Adjust the speed of the mixer to 300 rpm and stir at low speed for 25 min. Then add 6 kg of lactic acid, 20 kg of glass fiber and 1.2 kg of carboxymethyl cellulose (CMC) in sequence. Heat and stir at 90°C for 60 min at a speed of 600 rpm. The time interval between adding materials is 5 min.

[0156] (4) Material mixing: Add 7.5 kg monoethanolamine and 6 kg polyethylene oxide (PEO) to the mixer and stir at low speed for 25 min (300 rpm) to obtain a wet material with certain plasticity;

[0157] (5) Catalyst forming: The wet material is coated on a stainless steel mesh, and then dried and calcined to obtain a flat catalyst blank.

[0158] Of which, based on the total mass of the carrier, active component precursor salt and molding aid, the active component precursor salt content is 26.31 wt%, the carrier content is 67.14 wt%, and the molding aid content is 6.55 wt%.

[0159] (6) Drying: The CO-SCR catalyst blank is placed in a drying chamber. The drying temperature of the plate-type catalyst is 100°C and the drying time is 3 hours.

[0160] (7) Calcination: The dried CO-SCR catalyst preform is placed in a mesh belt kiln for calcination at a temperature of 450℃ for 4 hours to obtain the finished CO-SCR catalyst, denoted as CAT2.

[0161] Example 3

[0162] This embodiment provides a CO-SCR denitrification catalyst, comprising active components (copper oxide, manganese oxide, zirconium oxide, lanthanum oxide, and cerium oxide) and a support; the active components are supported on the support.

[0163] This embodiment also provides a method for preparing a CO-SCR denitrification catalyst, comprising the following steps:

[0164] (1) Preparation of aqueous solution of active component precursor: Heat pure water to 100°C, add active component precursor salt while stirring, and let it dissolve completely. This solution is called active component precursor solution A.

[0165] Among them, the active component precursor salts are transition metal oxide precursor salts and rare earth oxide precursor salts;

[0166] The transition metal oxide precursor salt includes 27.80 kg of copper oxide precursor basic copper carbonate, 43.31 kg of manganese oxide precursor salt manganese nitrate, and 34.84 kg of zirconium oxide precursor salt zirconium nitrate.

[0167] The rare earth oxide precursor salt includes 100.92 kg of cerium oxide precursor salt cerium nitrate and 6.65 kg of lanthanum oxide precursor salt lanthanum nitrate.

[0168] The mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is 1:1.02;

[0169] The above-mentioned active components were dissolved and prepared into an aqueous solution of active component precursor with a concentration of 40%.

[0170] (2) Loading of active material: Add 350 kg of composite oxide carrier of titanium dioxide and aluminum oxide to the mixer, add the active component precursor solution A while stirring at 200 rpm, add 20% ammonia water by volume, adjust the pH value to 6.5, stir at high speed for 30 minutes (300 rpm) until the active material and carrier are fully mixed.

[0171] (3) Introduce molding aids: Adjust the speed of the mixer to 120 rpm and stir at low speed for 30 min. Then add 6 kg of lactic acid, 20 kg of glass fiber, 5 kg of pulp, 1.2 kg of carboxymethyl cellulose (CMC), and 50 kg of limestone in sequence. Heat and stir at 95°C for 300 rpm for 90 min. The time interval between adding materials is 10 min.

[0172] (4) Material mixing: Add 7.5 kg monoethanolamine and 6 kg polyethylene oxide (PEO) to the mixer in sequence and stir at low speed for 30 min (120 rpm) to obtain a wet material with certain plasticity;

[0173] (5) Catalyst molding: The wet material is extruded and molded using an extruder, and a four-leaf clover catalyst preform is obtained by extruding through a perforated plate with a four-leaf clover structure.

[0174] Of which, based on the total mass of the carrier, active component precursor salt and molding aid, the active component precursor salt content is 32.39 wt%, the carrier content is 53.09 wt%, and the molding aid content is 14.52 wt%.

[0175] (6) Drying: The CO-SCR catalyst blank is placed in a drying chamber. The drying temperature of the clover-shaped catalyst is 70°C and the drying time is 24h.

[0176] (7) Calcination: The dried CO-SCR catalyst preform is placed in a mesh belt kiln for calcination at a temperature of 450℃ for 3 hours to obtain the finished CO-SCR catalyst, denoted as CAT3.

[0177] Comparative Example 1

[0178] The main difference between this comparative example and Example 1 is that the mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is 1:5, specifically:

[0179] The transition metal oxide precursor salt includes 8.04 kg of copper oxide precursor salt copper acetate and 13.87 kg of manganese oxide precursor salt manganese nitrate.

[0180] The rare earth oxide precursor salt includes 109.58 kg of cerium oxide precursor salt cerium nitrate;

[0181] The remaining steps and technical parameters are the same as in Example 1, and the CO-SCR catalyst product is prepared and denoted as DB1.

[0182] Comparative Example 2

[0183] The main difference between this comparative example and Example 1 is that the mass ratio of the transition metal oxide precursor salt to the rare earth oxide precursor salt is 2.3:1, specifically:

[0184] The transition metal oxide precursor salt includes 33.62 kg of copper oxide precursor salt copper acetate and 58.02 kg of manganese oxide precursor salt manganese nitrate.

[0185] The rare earth oxide precursor salt includes 39.85 kg of cerium oxide precursor salt cerium nitrate;

[0186] The remaining steps and technical parameters are the same as in Example 1, and the CO-SCR catalyst product is prepared and denoted as DB2.

[0187] Comparative Example 3

[0188] The main difference between this comparative example and Example 1 is that the support is a simple physical mixture of monomeric alumina and monomeric titanium dioxide, with a mass ratio of 1:5.5. The remaining steps and technical parameters are the same as in Example 1, and the CO-SCR catalyst product is prepared and designated as DB3.

[0189] Comparative Example 4

[0190] The main difference between this comparative example and Example 1 is that the content of the carrier is 88 wt%, specifically including: a composite oxide carrier of 534.33 kg of titanium dioxide and aluminum oxide.

[0191] The content of the active component precursor salt is 1.18 wt%, specifically including:

[0192] The transition metal oxide precursor salt includes 1.37 kg of copper oxide precursor salt copper acetate and 2.36 kg of manganese oxide precursor salt manganese nitrate.

[0193] The rare earth oxide precursor salt includes 3.43 kg of cerium oxide precursor salt cerium nitrate;

[0194] The molding aid content is 10.82 wt%, specifically including:

[0195] 6 kg lactic acid, 40 kg glass fiber, 5 kg pulp, 1.2 kg carboxymethyl cellulose (CMC), 7.5 kg monoethanolamine, and 6 kg polyethylene oxide;

[0196] The remaining steps and technical parameters are the same as in Example 1, and the CO-SCR catalyst product is prepared and designated as DB4.

[0197] Comparative Example 5

[0198] The main difference between this comparative example and the embodiment is that the carrier content is 50%, specifically including: a composite oxide carrier containing 303.60 kg of titanium dioxide and aluminum oxide.

[0199] The content of the active component precursor salt is 30.95 wt%, specifically including:

[0200] The transition metal oxide precursor salt includes 35.87 kg of copper oxide precursor salt copper acetate and 61.90 kg of manganese oxide precursor salt manganese nitrate.

[0201] The rare earth oxide precursor salt includes 90.16 kg of cerium oxide precursor salt cerium nitrate;

[0202] The molding aid content is 19.05 wt%, specifically including:

[0203] 6 kg lactic acid, 40 kg glass fiber, 5 kg pulp, 1.2 kg carboxymethyl cellulose (CMC), 50 kg limestone, 7.5 kg monoethanolamine and 6 kg polyethylene oxide;

[0204] The remaining steps and technical parameters are the same as in Example 1;

[0205] In this comparative example, due to the low content of the support, the prepared catalyst could not be formed and its performance could not be tested.

[0206] Performance testing

[0207] The catalyst was tested under simulated flue gas conditions, and the results are shown in the table below.

[0208] The catalysts prepared in the examples and comparative examples were equipped in a denitrification device. The NO conversion rate was calculated based on the NO concentration at the inlet and outlet of the denitrification device to determine the reactivity of the catalyst.

[0209] Specific testing procedures: CO concentration 900ppm, NO concentration 300ppm, 5v.% H2O, N2 equilibrium, volume hourly space velocity 30000h. -1 The test temperature is 100-300℃.

[0210] The formula for NO conversion rate (η) is:

[0211]

[0212] Among them, C in NO concentration at the inlet of the denitrification unit (unit: ppm, under standard conditions);

[0213] C out NO concentration at the outlet of the denitrification unit (unit: ppm, under standard conditions);

[0214] Q in : Inlet flue gas flow rate (unit: m3 / h, under standard conditions);

[0215] Q out : Outlet flue gas flow rate (unit: m3 / h, under standard conditions).

[0216] Results data

[0217] Catalysts prepared in Examples 1-3 and Comparative Examples 1-4, and the denitrification rate (%) of the comparative examples.

[0218]

[0219] As shown in Table 1, in Comparative Example 1, the mass ratio of transition metal oxide precursor salt to rare earth oxide precursor salt is 1:5, which exceeds the mass ratio range defined in this invention. As a result, the content of transition metal oxide precursor salt is insufficient and cannot provide enough active sites, thus affecting the denitrification efficiency of catalyst DB1.

[0220] As shown in Table 1, in Comparative Example 2, the mass ratio of transition metal oxide precursor salt to rare earth oxide precursor salt was 2.3:1. The excessive content of transition metal oxide precursor salt and the overly concentrated active sites affected the selectivity of the reaction, resulting in a decrease in the activity of catalyst DB2 and affecting the denitrification efficiency.

[0221] As shown in Table 1, the support in Comparative Example 3 is a simple physical mixture of monomeric alumina and monomeric titanium dioxide. It has a small specific surface area and poor structural stability, resulting in poor dispersion of the supported active components and affecting the denitrification efficiency of catalyst DB3.

[0222] As shown in Table 1, in Comparative Example 4, the content of the support was 88 wt%, which was too high. The content of the active component was relatively reduced to 1.18 wt%, which led to a significant decrease in the activity of catalyst DB4 and affected the denitrification efficiency.

[0223] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a CO-SCR denitration catalyst, characterized by, It comprises the following steps: S1: Put the active component precursor salt into water for heating and stirring to obtain an active component precursor solution; The active component precursor salt comprises a transition metal oxide precursor salt and a rare earth oxide precursor salt; S2: Add the composite oxide carrier to the active component precursor solution while stirring, and then adjust the pH after the end of the process, and perform high-speed stirring to obtain a mixture; S3: Add a molding aid to the mixture and stir to obtain a wet material; S4: Perform molding treatment on the wet material, and after drying and calcination, obtain a CO-SCR denitration catalyst.

2. The method of producing a CO-SCR denitration catalyst according to claim 1, characterized by, The mass ratio of the transition metal oxide precursor salt and the rare earth oxide precursor salt is (1-2):(1-4); And / or, the transition metal oxide precursor salt comprises one or more of copper oxide precursor salts such as copper acetate, copper nitrate, and basic copper carbonate, manganese oxide precursor salt manganese nitrate, and zirconium oxide precursor salt zirconium nitrate; And / or, the rare earth oxide precursor salt comprises one or more of cerium oxide precursor salt cerium nitrate and lanthanum oxide precursor salt lanthanum nitrate; And / or, the molding aid comprises at least two of monoethanolamine, stearic acid, lactic acid, limestone, carboxymethyl cellulose, paper pulp, glass fiber, polyethylene oxide, and amino cellulose.

3. The method of claim 1, wherein the CO-SCR de-NOx catalyst is prepared by the steps of: The composite oxide carrier is an aluminum oxide and titanium oxide composite oxide; The preparation method of the composite oxide of titanium oxide and aluminum oxide comprises the following steps: (1) Add aluminum salt and titanium salt to water and stir to obtain a mixed salt solution; (2) Add a precipitating agent to the mixed salt solution and stir until the pH is 8.5-9, then stand and age to obtain a slurry; (3) Filter the slurry to obtain a filter cake, and after drying and calcination, obtain a composite oxide of titanium oxide and aluminum oxide.

4. The preparation method of the CO-SCR denitration catalyst according to claim 3, wherein The aluminum salt comprises Al(NO3)3·9H2O; And / or, the titanium salt comprises TiOSO4; And / or, the mass ratio of the aluminum salt and the titanium salt is 1:(1-2); And / or, the concentration of the mixed salt solution is 0.1-1 mol / L; And / or, the precipitating agent is ammonia water with a volume percentage concentration of 22-27%; And / or, in step (2), the stirring speed is 200-300 rpm; And / or, in step (2), after stirring until the pH is 8.5-9, continue stirring for 25-35 min, and then stand and age; And / or, the standing and aging time is 2-4 h; And / or, the filter pressing is performed using a plate-and-frame filter press; And / or, the drying refers to drying the filter cake to a powder with a water content of ≤5%, and stopping the drying; And / or, the calcination is performed in a rotary kiln at a temperature of 450-550℃ for 3-5 h.

5. The method for preparing the CO-SCR denitration catalyst according to claim 1, characterized in that, In step S1, the heating and stirring temperature is 80-100℃; And / or, the mass percentage concentration of the active component precursor solution is 40%-50%. And / or, in step S2, adjusting the pH refers to adjusting the pH value to 7-8 using ammonia water; the volume percentage concentration of the ammonia water is 20-25%; And / or, in step S2, the speed of the high-speed stirring is 300-600 rpm, and the stirring time is 60-90 min; And / or, in step S3, the stirring includes: first heating and stirring, and then low-speed stirring; wherein the temperature of the heating and stirring is 70-90°C, the stirring speed is 300-600 rpm, and the stirring time is 30-40 min; the speed of the low-speed stirring is 120-300 rpm, and the stirring time is 60-90 min.

6. The method of claim 1, wherein the CO-SCR de-NOx catalyst is prepared by the steps of: The content of the active component precursor salt is 8-35 wt%, the content of the carrier is 52-83 wt%, and the content of the forming aid is 5-20 wt%, based on the total mass of the carrier, the active component precursor salt, and the forming aid.

7. The method for preparing the CO-SCR denitrification catalyst according to claim 1, characterized in that, In step S4, the forming treatment includes: using an extruder to extrude the wet dough into a four-leaf clover shape, drying, and calcining to obtain a four-leaf clover catalyst product; or, coating the wet dough on a stainless steel mesh, drying, and calcining to obtain a flat plate catalyst product; or, putting the wet dough into a kneader with a filter screen to filter and pre-extrude the wet dough into a brick mud, and then putting the obtained pre-extruded brick mud into a vacuum extruder, and extruding the pre-extruded brick mud into a honeycomb catalyst product through a mold.

8. The preparation method of the CO-SCR denitration catalyst according to claim 7, wherein, the drying temperature of the four-leaf clover catalyst is 70-90°C, and the drying time is 16-24 h; the drying temperature of the flat plate catalyst is 90-120°C, and the drying time is 2-4 h; the drying temperature of the honeycomb catalyst is 60-70°C, and the drying time is 120-144 h; the calcination temperature of the four-leaf clover catalyst is 400-500°C, and the calcination time is 2-4 h; the calcination temperature of the flat plate catalyst is 400-500°C, and the calcination time is 4-8 h; the calcination temperature of the honeycomb catalyst is 400-500°C, and the calcination time is 8-12 h.

9. A CO-SCR denitration catalyst prepared by the preparation method of any one of claims 1-8.

10. The CO-SCR De-NOx catalyst according to claim 9, characterized in that, The active component in the CO-SCR denitration catalyst includes a transition metal oxide and a rare earth oxide, and the active component is uniformly dispersed on the carrier; The transition metal oxide includes one or more of copper oxide, manganese oxide, and zirconium oxide; The rare earth oxide includes one or more of cerium oxide and lanthanum oxide.

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