Aging-resistant high-selectivity metal-doped hydroxylated carrier loaded metal oxide denitration catalyst, and preparation method and application thereof

Abstract

This invention relates to an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, its preparation method, and its applications. The catalyst uses boehmite modified with rare earth metals (cerium, lanthanum, samarium, praseodymium, neodymium, gadolinium, etc.) as the hydroxylation support, and supports single or composite oxides of transition metals such as manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin as the active components. Through electron transfer and structural bridging between the rare earth metals and the active components, the catalyst's low-temperature denitration activity, nitrogen selectivity, and hydrothermal aging resistance are significantly enhanced, maintaining excellent catalytic performance even under high-temperature and high-humidity environments. Compared with existing technologies, this catalyst has a simple preparation process, low cost, and is suitable for the efficient catalytic purification of nitrogen oxides in low-temperature vehicle exhaust, possessing significant environmental application value.

Description

Technical Field

[0001] This invention relates to the field of motor vehicle exhaust purification technology, and in particular to an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, its preparation method, and its application. Background Technology

[0002] Nitrogen oxides (NO) x Fine particulate matter (PM2.5) is one of the major air pollutants. 2.5 The combined pollution of NH3 and ozone (O3) is a major cause of atmospheric pollution, seriously endangering the atmospheric environment and human health. Urea decomposes NH3 and selectively catalytically reduces NO. x (NH3-SCR) technology is widely used in vehicle exhaust aftertreatment systems. However, during cold starts and high-speed airflow, the exhaust temperature of vehicles is low, and the activity of commercially available SCR catalysts, such as Cu-CHA molecular sieves, is typically limited under these low-temperature, high-speed conditions, making it unable to effectively remove NO. x It is reduced to N2. Therefore, transition / rare earth composite metal oxide catalysts with excellent low-temperature catalytic reduction activity are gradually attracting more attention. Due to incomplete combustion of fuel during the cold start phase, a large amount of soot (HCs) particles are generated. To protect the downstream SCR catalyst from clogging, a particulate filter (DPF) is mainly used for filtration. However, the DPF regeneration process generates a high-temperature and high-humidity environment, leading to severe poisoning and deactivation of the downstream SCR catalyst. Therefore, for NO emissions from motor vehicle exhaust... x The key scientific challenge of effectively removing NO from vehicle exhaust lies in developing low-temperature, high-efficiency, highly selective, and hydrothermal-resistant denitrification catalysts. x Effective control of [the virus] has significant scientific and practical value.

[0003] In recent years, rare earth / transition metal composite oxides, mainly composed of Ce, Fe, and Mn, have shown superior SCR activity at low temperatures compared to molecular sieve catalysts due to their simple synthesis methods, low preparation costs, and easy modification processes. Furthermore, they possess unique oxygen dissociation capabilities and strong surface adsorption oxygen mobility. However, for common metal oxide catalysts, the biggest challenge in mobile source vehicle exhaust treatment is the hydrothermal aging and deactivation caused by oxide phase transformation and grain growth under high temperature and humidity conditions.

[0004] Therefore, if the excellent low-temperature denitrification activity of metal oxide catalysts can be maintained, and their hydrothermal aging stability and nitrogen selectivity can be enhanced by controlling the crystal structure, chemical composition, surface acidity, and redox properties of the catalysts, they are expected to be used as an alternative to molecular sieve catalysts in the low-temperature purification process of nitrogen oxides in motor vehicle exhaust. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, its preparation method, and its application. In the process of purifying nitrogen oxides in motor vehicle exhaust, existing molecular sieve catalysts suffer from insufficient activity at low temperatures and oxide catalysts often face hydrothermal aging and deactivation. The catalyst developed in this invention, while ensuring low-temperature denitration activity, also enhances the hydrothermal aging stability and nitrogen selectivity of the catalyst, which can greatly improve the practical value of the catalyst in the purification of nitrogen oxides in motor vehicle exhaust.

[0006] The objective of this invention can be achieved through the following technical solutions: This invention relates to a metal oxide denitration catalyst supported on a metal-doped modified hydroxylated support that is resistant to hydrothermal aging and has high selectivity, as well as its preparation method. The catalyst has excellent resistance to hydrothermal aging, low-temperature denitration activity, and high nitrogen selectivity. At the same time, the raw materials are simple, the preparation process is simple, and the cost is low. It has potential application value in the field of nitrogen oxide control and purification technology of motor vehicle exhaust in environmental protection.

[0007] One of the technical solutions of the present invention is to provide an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, wherein the denitration catalyst uses hydroxylated alumina as a support, transition metal oxide as an active component, and rare earth metal elements as modifying agents.

[0008] Furthermore, a rare earth metal-modified hydroxylation support was obtained by modifying hydroxylated alumina with rare earth metal elements; transition metal oxides were loaded onto the rare earth metal-modified hydroxylation support.

[0009] Furthermore, the rare earth metal element is selected from at least one of cerium, lanthanum, samarium, praseodymium, neodymium, and gadolinium.

[0010] Furthermore, the transition metal is selected from at least one of manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin.

[0011] The second technical solution of the present invention provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support for supporting metal oxide denitration catalyst, the preparation method comprising the following steps: a. Rare earth metal element modification of hydroxylated alumina support: The pseudoboehmite powder was dispersed in a solvent, then a modified metal precursor salt was added, stirred, the pH was adjusted to 9-10, stirring was continued, the mixture was filtered under reduced pressure, washed, dried, and the resulting white powder was calcined to obtain a rare earth metal modified hydroxylation carrier. b. Dispersion of active metal oxide precursor salts: The active metal precursor was dispersed in a solvent and sonicated to obtain a metal precursor salt solution. c. Loading of active metal oxide components: The metal precursor salt solution obtained in step b is added to the rare earth metal modified hydroxylation support obtained in step a above, stirred until it becomes muddy, dried, and the resulting powdered catalyst precursor is calcined to obtain a metal oxide catalyst supported on a metal-doped hydroxylation support. d. Hydrothermal aging treatment of denitrification catalysts: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is calcined, and air containing water vapor is introduced during the calcination process to carry out hydrothermal aging treatment, so as to obtain the hydrothermally aged metal-doped hydroxylated support-supported metal oxide catalyst, which is the denitrification catalyst.

[0012] Further, in step a, the solvent is at least one of water (deionized water) and ethanol (anhydrous ethanol).

[0013] Furthermore, in step a, the modified metal precursor salt is a rare earth metal element precursor salt.

[0014] Further, in step a, the modified metal precursor salt is at least one of cerium nitrate hexahydrate, lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, praseodymium nitrate hexahydrate, neodymium nitrate hexahydrate, and gadolinium nitrate hexahydrate.

[0015] Further, in step a, stir for 5-20 minutes, adjust the pH to 9-10 by adding ammonia dropwise, and continue stirring for 30-60 minutes.

[0016] Furthermore, in step a, the washing process involves washing with water (deionized water) 3 to 4 times.

[0017] Further, in step a, the drying process involves placing the item in an oven at 80-100°C for 10-12 hours.

[0018] Further, in step a, the calcination is carried out in a muffle furnace under an air atmosphere at 400~550 ℃ for 2~5 h, with a heating rate of 2~5 ℃ / min.

[0019] Further, in step a, the modified metal precursor salt is calcined to form a modified rare earth metal oxide component; the content of the modified rare earth metal oxide component is 3 to 20% of the mass of the rare earth metal modified hydroxylation carrier.

[0020] Further, in step b, the solvent is at least one of water (deionized water) and ethanol (anhydrous ethanol).

[0021] Furthermore, in step b, the ultrasound duration is 5 to 40 minutes.

[0022] Further, in step b, the active metal precursor is an active metal precursor salt, which is at least one of manganese nitrate tetrahydrate, copper nitrate trihydrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate, ammonium metatungstate, niobium oxalate hexahydrate, zirconium nitrate pentahydrate, and tin tetrachloride pentahydrate, and does not overlap with the modified metal precursor salt.

[0023] Furthermore, in step c, the active metal precursor in the powdered catalyst precursor is calcined to form an active metal oxide component; the content of the active metal oxide component is 5-20% of the mass of the rare earth metal modified hydroxylation support.

[0024] Further, in step c, the drying process involves placing the item in an oven at 80-100°C for 10-12 hours.

[0025] Further, in step c, the calcination is carried out in a muffle furnace under an air atmosphere at 400~550 ℃ for 2~5 h, with a heating rate of 2~5 ℃ / min.

[0026] Further, in step d, the calcination is performed by placing the sample in a hydrothermal aging muffle furnace and calcining it at 650~800 °C for 24~50 h.

[0027] Furthermore, in step d, the water vapor content in the air containing water vapor is 5-10% by mass.

[0028] Furthermore, in step d, the hydrothermal aging treatment time is 24~50 h.

[0029] The third technical solution of the present invention is to provide an application of a metal oxide denitrification catalyst supported on an aging-resistant and highly selective metal-doped hydroxylated support, wherein the denitrification catalyst is used for low-temperature purification of nitrogen oxides in motor vehicle exhaust.

[0030] The technical concept of this invention is as follows: This invention provides a metal oxide denitration catalyst supported on a metal-doped hydroxylated support that is resistant to aging and highly selective. The metal-doped hydroxylated support is prepared using a conventional equal-volume wet impregnation process with one or more modified hydroxylated alumina elements selected from rare earth metals such as cerium, lanthanum, samarium, praseodymium, neodymium, and gadolinium. Boehmite is a typical hydroxylated alumina, and its surface-rich hydroxyl structure provides numerous highly dispersed and fixed anchoring sites for the modified metal (rare earth metal elements), enhancing the affinity between the support and the modified metal ions, thereby promoting the anchoring and dispersion of the modified metal ions. The active component supported on the rare earth metal-modified hydroxylated support is a single oxide or a composite oxide of two or more transition metals such as manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin, and the catalyst can be prepared using a conventional equal-volume wet impregnation process. The supported active component primarily enhances the efficient interaction between the rare earth metal-modified hydroxylation support and the active component through effective electron transfer with the rare earth metal species in the modified hydroxylation support. This reduces the peroxidation capacity of the active component for ammonia, resulting in a highly selective catalytic reduction of nitrogen oxides. Furthermore, the rare earth metal elements in the modified hydroxylation support act as a bridge between the hydroxylated alumina support and the transition metal oxide active component, effectively suppressing the thermal aggregation effect of the surface-supported active metal oxide component during hydrothermal aging. This inhibits the crystallization, growth, and aggregation of the active metal oxide, thus maintaining a highly efficient and stable catalytic reduction effect even under high-temperature and high-humidity hydrothermal aging conditions. Ultimately, this leads to a comprehensive improvement in the catalyst's low-temperature denitrification activity, hydrothermal aging stability, and nitrogen selectivity.

[0031] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention provides an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, its preparation method, and its application. The denitration catalyst uses boehmite modified with one of the rare earth metals such as cerium, lanthanum, samarium, praseodymium, neodymium, and gadolinium as the hydroxylated alumina support. A single oxide or two or more composite oxides of transition metals such as manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin are uniformly anchored on the rare earth metal-doped modified hydroxylated support using an equal-volume impregnation method. The hydroxyl structure rich in hydroxylated alumina provides highly dispersed anchoring sites for the modified metal, enhancing the affinity between the support and the modified metal. The supported active component enhances the interaction between the support and the active component through electron transfer with the rare earth metal species in the modified hydroxylated support, increasing the surface defect concentration, redox capacity, and surface acidity of the catalyst, thus accelerating the NO removal process in the NH3-SCR reaction. xThe rare earth metal species in the hydroxylation support adsorb and activate NH3 species, and reduce the peroxidation capacity of the active metal for ammonia, thereby exerting a highly selective catalytic reduction of nitrogen oxides. In addition, the rare earth metal species in the hydroxylation support can inhibit the deactivation of the active metal during hydrothermal aging by establishing a bridge between the support and the active component, thus achieving a comprehensive improvement in the catalyst's low-temperature denitrification activity, hydrothermal aging stability, and nitrogen selectivity.

[0032] 2) This invention provides an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, its preparation method, and its application. The denitration catalyst is low-cost, requires minimal synthesis equipment, and simultaneously exhibits excellent low-temperature denitration catalytic activity, nitrogen selectivity, and resistance to hydrothermal aging and deactivation. It is suitable for the low-temperature, high-efficiency catalytic purification of nitrogen oxides in exhaust gases from mobile sources such as motor vehicles, contributing to PM2.5 purification. 2.5 Highly efficient elimination of combined pollution with ozone. Attached Figure Description

[0033] Figure 1 The NO denitrification catalyst prepared in Example 1 of this invention after hydrothermal aging x Conversion rate curve.

[0034] Figure 2 The N2 selectivity curve of the denitrification catalyst prepared in Example 1 of this invention after hydrothermal aging is shown. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Component models, material names, connection structures, control methods, and other features not explicitly stated in this technical solution are considered to be common technical features disclosed in the prior art.

[0036] This invention discloses a metal oxide denitration catalyst supported on a metal-doped hydroxylation support with high aging resistance and its preparation method, belonging to the field of motor vehicle exhaust purification technology. The catalyst uses boehmite modified with rare earth metals (cerium, lanthanum, samarium, praseodymium, neodymium, gadolinium, etc.) as the hydroxylation support, and supports single or composite oxides of transition metals such as manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin as active components. Through electron transfer and structural bridging between the rare earth metals and the active components, the catalyst's low-temperature denitration activity, nitrogen selectivity, and hydrothermal aging resistance are significantly enhanced, maintaining excellent catalytic performance even under high temperature and high humidity environments. The catalyst preparation process is simple and low-cost, suitable for the efficient catalytic purification of nitrogen oxides in low-temperature motor vehicle exhaust, and has significant environmental application value.

[0037] This invention provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, the method comprising the following steps: a. Rare earth metal modification of hydroxylated alumina support: A certain amount of boehmite powder was dispersed in deionized water or ethanol solvent, and then a certain amount of modified metal precursor salt was added to the solvent. The mixture was stirred for 5-20 min, and the pH was adjusted to 9-10 by adding ammonia dropwise. The mixture was stirred for another 30-60 min, filtered under reduced pressure, washed 3-4 times with deionized water, and dried in an oven at 80-100 ℃ for 10-12 h. The resulting white powder was placed in a muffle furnace and calcined in an air atmosphere at 400-550 ℃ for 2-5 h with a heating rate of 2-5 ℃ / min to obtain a rare earth metal modified hydroxylated carrier. b. Dispersion of active metal oxide precursor salts: The active metal precursor is dispersed in deionized water or ethanol solvent and sonicated for 5-40 min to obtain a metal precursor salt solution. c. Loading of active metal oxide components: The rare earth metal modified hydroxyl support prepared above is placed in a small crucible, and the metal precursor salt solution obtained in step b is added dropwise to the small crucible. It is stirred rapidly until it becomes a mud-like substance, and then dried in an oven at 80~100 ℃ for 10~12 h. The resulting powdered catalyst precursor is placed in a muffle furnace and calcined in an air atmosphere at 400~550 ℃ for 2~5 h with a heating rate of 2~5 ℃ / min to obtain a metal oxide catalyst supported on a metal-doped hydroxylated support. d. Hydrothermal aging treatment of denitrification catalysts: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c was placed in a self-made hydrothermal aging muffle furnace and calcined at 650~800 ℃ for 24~50 h. During the calcination process, air with a water vapor mass percentage of 5~10% was introduced to obtain the hydrothermally aged metal-doped hydroxylated support-supported metal oxide catalyst.

[0038] In the examples below, unless otherwise specified, the reagents used are commercially available products and the methods employed are those known in the art.

[0039] In this invention, an experimental system capable of hydrothermal aging is obtained by combining a muffle furnace with a water bath and an air generator. In the following embodiments, the hydrothermal aging treatment of the catalyst is mainly carried out in the above-mentioned experimental system.

[0040] Example 1 This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.0811 g of cerium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 3 h at a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.1616 g of manganese nitrate tetrahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 3 h with a heating rate of 2 ℃ / min to obtain the product, which is a fresh metal-doped hydroxylated support for metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0041] Catalyst denitrification performance testing: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity testing. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 90% at 120~240 ℃, with overall N2O production below 30 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as a dilution gas.

[0042] Hydrothermal aging resistance test of catalyst: The metal-doped hydroxylated support-supported metal oxide denitration catalyst obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹.-1 Under the specified conditions, the denitrification efficiency remained stable at over 90% at 120–240 °C, with overall N₂O generation below 30 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. This catalyst fully utilizes the structural characteristics of the support, significantly suppressing the selectivity decrease caused by excessive oxidation of ammonia molecules and mitigating the impact of hydrothermal aging on the catalyst's acidity and redox capacity, thereby improving the catalyst's hydrothermal aging performance and N₂ selectivity. This embodiment of the metal-doped hydroxylated support-supported metal oxide denitrification catalyst enhances both low-temperature performance and N₂ selectivity while ensuring the catalyst's hydrothermal aging performance.

[0043] Example 2 This embodiment is basically the same as embodiment 1, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.1147 g of samarium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 10 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in a 90 ℃ oven to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 4 h at a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.3209 g of copper nitrate tetrahydrate to 900 μL of deionized water, sonicate for 10 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite catalyst support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in a 90 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 4 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-doped hydroxylated support supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0044] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 85% at 200-300 °C, with overall N2O production below 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as a dilution gas.

[0045] Hydrothermal aging resistance test of catalyst: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the conditions of 30–450 °C and a space velocity of 100,000 h⁻¹, the reaction temperature was 30–450 °C. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% at 200-300 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a selective reduction denitrification catalyst for metal oxides exhibiting good hydrothermal aging stability and high selectivity. This catalyst utilizes the stable structure and electronic regulation of the samarium-doped hydroxylated support to effectively enhance the dispersion and anchoring of copper active species on the support surface, significantly inhibiting the peroxidation reaction and thus mitigating the adverse effects of hydrothermal aging on the catalyst surface acidity and redox performance. This embodiment of the metal-doped hydroxylated support-supported metal oxide denitrification catalyst further improves the catalyst's hydrothermal aging performance while maintaining its activity.

[0046] Example 3: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.0847 g of lanthanum nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 20 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 60 min, filtered, washed four times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 550 ℃ for 3 h at a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.1616 g of manganese nitrate tetrahydrate and 0.2473 g of tin tetrachloride tetrahydrate to 900 μL of anhydrous ethanol, sonicate for 30 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, dry it in an 80 ℃ oven to obtain powder, and then calcine it in a muffle furnace at 550 ℃ for 3 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst; d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0047] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 85% at 180~360 ℃, and the overall N2O production was less than 40 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0048] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% within the range of 180–360 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide catalyst in this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. By adjusting the crystal structure and redox behavior of manganese species through lanthanum doping of the hydroxylated support, the non-selective oxidation reaction of ammonia molecules was suppressed to a certain extent. The introduction of lanthanum slowed down the migration and activity decay of manganese species during hydrothermal aging, thereby weakening the impact of aging on catalyst selectivity. This allowed the metal-doped hydroxylated support-supported metal oxide denitrification catalyst to maintain good denitrification performance and N₂ selectivity even after hydrothermal aging.

[0049] Example 4: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 1.034 g of praseodymium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 15 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 40 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 450 ℃ for 5 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.2675 g of ferric nitrate nonahydrate to 900 μL of deionized water, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudo-alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 450 ℃ for 5 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0050] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 160~280 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0051] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% at 160–280 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. This catalyst fully utilizes the structural characteristics of the support, significantly reducing the impact of hydrothermal aging on the catalyst's acidity and redox capacity, thereby improving the catalyst's hydrothermal aging performance. This embodiment of the metal-doped hydroxylated support-supported metal oxide denitrification catalyst, while ensuring the catalyst's hydrothermal aging performance, also enhances the catalyst's low-temperature performance.

[0052] Example 5: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.4971 g of neodymium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 10 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 5 h at a heating rate of 3 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.6170 g of cobalt nitrate hexahydrate to 900 μL of anhydrous ethanol, sonicate for 20 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 5 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0053] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 85% at 200~320 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0054] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% at 200–320 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. The praseodymium-doped hydroxylated support modulates the electronic structure and interfacial interactions of iron species, ensuring the intrinsic denitrification activity of the iron-based catalyst while preventing excessive oxidation of ammonia molecules during the reaction, thus contributing to maintaining high N₂ selectivity. Simultaneously, the introduction of praseodymium enhances the interaction between the support and the active component to some extent, mitigating the impact of hydrothermal aging on the catalyst's acidity and the stability of active centers, allowing the catalyst to maintain relatively stable denitrification performance even after aging.

[0055] Example 6: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.07919 g of gadolinium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 20 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 50 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 550 ℃ for 4 h with a heating rate of 4 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.1308 g of ammonium molybdate tetrahydrate to 900 μL of deionized water, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 550 ℃ for 4 h with a heating rate of 4 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0056] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 250~360 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0057] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1Under the specified conditions, the denitrification efficiency remained stable at over 80% at 250–360 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. Gadolinium enhances the structural stability of the support and the anchoring effect of the active components. The synergistic effect between gadolinium and molybdenum species helps stabilize the acidity of the catalyst surface and regulate its redox properties, thereby improving the hydrothermal aging performance of the catalyst. This embodiment of the metal-doped hydroxylated support-supported metal oxide denitrification catalyst, while ensuring the hydrothermal aging performance of the catalyst, also enhances the low-temperature performance of the catalyst.

[0058] Example 7: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.1622 g of cerium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 10 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 450 ℃ for 4 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.2024 g of ferric nitrate nonahydrate and 0.4235 g of zirconium nitrate pentahydrate to 900 μL of deionized water, sonicate for 5 min, and obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 450 ℃ for 4 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0059] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 85% at 150~300 ℃, and the overall N2O production was less than 40 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0060] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 85% at 150–300 °C, with overall N₂O generation below 40 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. Through the synergistic effect of the cerium-doped hydroxylated support and the iron-zirconium composite oxide, a balanced regulation of activity and selectivity was achieved. The introduction of zirconium effectively weakened the excessive redox ability of iron species, allowing the catalyst to maintain good NH₃-SCR performance and selectivity even after aging. This embodiment of the metal-doped hydroxylated support-supported metal oxide denitrification catalyst enhances the catalyst's low-temperature performance while ensuring its hydrothermal aging performance.

[0061] Example 8: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.1694 g of lanthanum nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 10 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 2 h at a heating rate of 3 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.4391 g of niobium oxalate hexahydrate to 900 μL of deionized water, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 2 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal oxide catalyst supported on the metal-doped hydroxylated support obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal oxide denitration catalyst after hydrothermal aging treatment, namely the metal oxide denitration catalyst supported on the metal-doped hydroxylated support.

[0062] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 200~360 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0063] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 200–360 °C, with overall N2O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst in this embodiment is a relatively poor-performing selective reduction denitrification catalyst. While the combination of lanthanum-doped hydroxylated support and niobium oxide improves the support structure stability, the niobium species has limited activity, resulting in weak low-temperature denitrification performance. Furthermore, its inhibition of non-selective oxidation of ammonia molecules is limited, leading to insignificant improvement in activity and N2 selectivity after hydrothermal aging.

[0064] Example 9: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.1583 g of neodymium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 3 h with a heating rate of 5 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.847 g of zirconium nitrate pentahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudo-alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 3 h with a heating rate of 5 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0065] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 85% at 180~300 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0066] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1Under the specified conditions, the denitrification efficiency remained stable at over 85% at 180–300 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst in this embodiment is a relatively poor-performing selective reduction denitrification catalyst. While the combination of neodymium-doped hydroxylated support and zirconium oxide improves the support structure stability, the zirconium species themselves have limited redox activity and lack effective active centers for catalytic reaction. Therefore, this catalyst exhibits low-temperature denitrification performance, limited inhibition of non-selective ammonia oxidation, and no significant improvement in catalytic activity and N₂ selectivity after hydrothermal aging.

[0067] Example 10: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.4866 g of cerium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 15 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 30 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 550 ℃ for 3 h at a heating rate of 5 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.2473 g of tin tetrahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 550 ℃ for 3 h with a heating rate of 5 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the hydrothermally aged metal-doped hydroxylated support-supported metal oxide denitration catalyst.

[0068] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 210~360 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0069] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% at 210–360 °C, with overall N2O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst in this embodiment is a general-performance metal oxide selective reduction denitrification catalyst. While cerium doping enhances the support structure stability, the tin oxide activity is limited, making it difficult to provide effective denitrification active centers. The catalyst's low-temperature performance improvement is not significant, and its inhibition of non-selective ammonia oxidation is limited. Furthermore, the improvement in N2 selectivity after hydrothermal aging is limited, making it more suitable as a comparative example.

[0070] Example 11: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.2433 g of cerium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 40 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 450 ℃ for 5 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.1215 g of copper nitrate trihydrate and 0.0428 g of ammonium metatungstate to 900 μL of anhydrous ethanol, sonicate for 5 min, and obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 450 ℃ for 5 h with a heating rate of 3 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0071] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 180~320℃, with overall N2O production below 50ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as a dilution gas.

[0072] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% within the range of 180–320℃, with overall N2O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. This catalyst achieves a balanced regulation of activity and selectivity through the synergistic effect of the cerium-doped hydroxylated support and the copper-tungsten composite oxide. Cerium provides electronic regulation and structural stabilization, while tungsten modulates the redox ability of the copper active center, effectively suppressing the non-selective oxidation of ammonia molecules. This catalyst maintains good low-temperature denitrification activity and high N2 selectivity even under hydrothermal aging conditions, demonstrating excellent overall performance.

[0073] Example 12: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.3167 g of neodymium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 5 h at a heating rate of 4 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.2024 g of ferric nitrate nonahydrate and 0.0428 g of ammonium metatungstate to 900 μL of deionized water, sonicate for 5 min, and obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudo-alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 5 h with a heating rate of 4 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0074] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 220~360 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0075] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1Under the specified conditions, the denitrification efficiency remained stable at over 80% at 220–360 °C, with overall N₂O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. This catalyst fully utilizes the structural characteristics of the support, significantly reducing the impact of hydrothermal aging on the catalyst's acidity and redox capacity, thereby improving the catalyst's hydrothermal aging performance. In this embodiment, the catalyst, while ensuring its hydrothermal aging performance, also enhances its low-temperature performance.

[0076] Example 13: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.5174 g of praseodymium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 3 h at a heating rate of 4 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.6170 g of cobalt nitrate hexahydrate and 0.4391 g of niobium oxalate hexahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudo-alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 3 h with a heating rate of 4 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0077] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 220~400 ℃, with overall N2O production below 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0078] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 80% at 220–400 °C, with overall N2O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. This catalyst achieves a balance between low-temperature denitrification activity and selectivity through the synergistic effect of neodymium-doped hydroxylated support and iron-tungsten composite oxide. Neodymium enhances the structural stability of the support and the anchoring ability of the active components, while tungsten regulates the redox behavior of iron species, effectively inhibiting the non-selective oxidation reaction of ammonia molecules. This catalyst maintains good NH3-SCR activity and N2 selectivity even after hydrothermal aging, exhibiting excellent aging stability.

[0079] Example 14: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of deionized water, and 0.3960 g of gadolinium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 9 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 4 h at a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.1616 g manganese nitrate tetrahydrate and 0.4235 g zirconium nitrate pentahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 4 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0080] Denitrification performance testing of the catalyst: The metal oxide denitrification catalyst supported on the metal-doped hydroxylated support obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity testing. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 90% at 140~280 ℃, and the overall N2O production was less than 40 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0081] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 90% at 140–280 °C, with overall N₂O generation below 40 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance selective reduction denitrification catalyst for metal oxides. Through the synergistic effect of gadolinium-doped hydroxylated support and manganese-zirconium composite oxide, the catalyst enhances the structural stability of the support and the anchoring effect of the active components, thus inhibiting the non-selective oxidation of ammonia molecules to a certain extent. Zirconium regulates the redox ability of manganese species, allowing the catalyst to exert its low-temperature denitrification activity. Simultaneously, gadolinium doping slows down the migration of active components and acidic decay during hydrothermal aging.

[0082] Example 15: This embodiment is basically the same as the previous embodiments, except that: This embodiment provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of boehmite was dispersed in 40 mL of anhydrous ethanol, and 0.2541 g of lanthanum nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed 4 times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 5 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified boehmite catalyst support. b. Add 0.3085 g of cobalt nitrate hexahydrate and 0.0294 g of ammonium molybdate tetrahydrate to 900 μL of deionized water, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified pseudo-alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 5 h with a heating rate of 2 ℃ / min to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal-doped hydroxylated support-supported metal oxide catalyst obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor content of 5% by mass is introduced to obtain the product, which is the metal-doped hydroxylated support-supported metal oxide denitration catalyst after hydrothermal aging treatment.

[0083] Denitrification performance test of the catalyst: The catalyst obtained in step c was granulated to 40-60 mesh and placed in a reactor for activity and N2 selectivity tests. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 80% at 200~320 ℃, and the overall N2O production was less than 50 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as a dilution gas.

[0084] Hydrothermal aging resistance test: The metal oxide denitration catalyst supported on the metal-doped hydroxylated support obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1Under these conditions, the denitrification efficiency remained stable at over 80% at 200–320 °C, with overall N2O generation below 50 ppm. The metal-doped hydroxylated support-supported metal oxide denitrification catalyst of this embodiment is a high-performance metal oxide selective reduction denitrification catalyst. This catalyst achieves low-temperature denitrification activity and selectivity regulation through the synergistic effect of the lanthanum-doped hydroxylated support and the cobalt-molybdenum composite oxide. Lanthanum enhances the structural stability of the support and the anchoring ability of the active components, while molybdenum regulates the redox behavior of the cobalt active center, helping to suppress the non-selective oxidation of ammonia molecules. This allows the catalyst to maintain good NH3-SCR activity and N2 selectivity even under hydrothermal aging conditions.

[0085] Comparative Example 1 This comparative example provides a method for preparing a hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. Add 0.1616 g of manganese nitrate tetrahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution, and set aside for later use; b. Place 0.8000 unmodified pseudoboehmite support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, dry it in an 80 ℃ oven to obtain powder, and then calcine it in a muffle furnace at 500 ℃ for 3 h with a heating rate of 2 ℃ / min to obtain the product, which is the fresh hydroxylated support-supported metal oxide catalyst; c. Hydrothermal aging treatment of the catalyst: The hydroxylated supported metal oxide catalyst obtained in step b is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the hydrothermally aged hydroxylated supported metal oxide denitration catalyst.

[0086] Catalyst denitrification performance testing: The hydroxylated supported metal oxide denitrification catalyst obtained in step b was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity testing. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 90% at 160~280℃, and the overall N2O yield was higher than 130 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as dilution gas.

[0087] Hydrothermal aging resistance test of catalyst: The metal-doped hydroxylated support-supported metal oxide denitration catalyst obtained in step c was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 60% at 300-330 °C, with the overall N2O generation exceeding 160 ppm. The hydroxylated support-supported metal oxide denitrification catalyst in this comparative example is a poor-performing selective reduction denitrification catalyst. This catalyst lacks the electronic regulation of rare earth metals, leading to excessive and non-selective oxidation of the reactant NH3 to N2O or NO by the active metal. Furthermore, due to the loss of the structural bridge established between the support and the active component by the rare earth metal, hydrothermal aging treatment resulted in severe migration, agglomeration, and grain growth of the active metal, leading to deactivation and ultimately a significant decline in its hydrothermal aging resistance.

[0088] Comparative Example 2 This comparative example provides a method for preparing an aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst, comprising the following steps: a. 1.0600 g of alumina was dispersed in 40 mL of deionized water, and 0.0811 g of cerium nitrate hexahydrate was also added to the above solvent. The mixture was stirred for 5 min, and the pH was adjusted to 10 with ammonia water. The mixture was stirred for another 30 min, filtered, washed three times with deionized water, and dried overnight in an oven at 80 ℃ to obtain a white powder. The powder was then calcined in a muffle furnace at 500 ℃ for 3 h at a heating rate of 2 ℃ / min to obtain the product, which is the metal-modified oxide carrier. b. Add 0.1616 g of manganese nitrate tetrahydrate to 900 μL of anhydrous ethanol, sonicate for 5 min to obtain a solution for later use; c. Place 0.8000 g of metal-modified alumina support into a small crucible, and add the solution from step b dropwise into the small crucible; stir rapidly until it becomes a mud-like consistency, place it in an 80 ℃ oven to dry, and obtain powder. Then, calcine it in a muffle furnace at 500 ℃ for 3 h with a heating rate of 2 ℃ / min to obtain the product, which is a fresh metal-doped alumina support-supported metal oxide catalyst. d. Hydrothermal aging treatment of the catalyst: The metal oxide catalyst supported on a metal-doped alumina support obtained in step c is placed in a muffle furnace and calcined at 650 °C for 50 h. During the calcination process, air with a water vapor mass percentage of 10% is introduced to obtain the product, which is the denitrification catalyst supported on a metal-doped alumina support after hydrothermal aging.

[0089] Catalyst denitrification performance test: The metal oxide denitrification catalyst supported on the metal-doped γ-alumina support obtained in step c was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 °C and the space velocity was 100,000 h⁻¹. -1 Under these conditions, the denitrification efficiency remained stable at over 90% at 220-250 ℃, with overall N2O production below 80 ppm. The simulated flue gas contained 5 vol% O2, 500 ppm NO, 500 ppm NH3, and N2 was used as a dilution gas.

[0090] Hydrothermal aging resistance test of catalyst: The metal oxide denitration catalyst supported on metal doped alumina obtained in step d was granulated and sieved. 40-60 mesh catalyst particles were placed in a fixed-bed reactor for low-temperature nitrogen oxide catalytic reduction activity and N2 selectivity tests. The reaction temperature was 30-450 ℃ and the space velocity was 100,000 h⁻¹. -1 Under the specified conditions, the denitrification efficiency remained stable at over 60% at 350-380 °C, with the overall N2O generation below 120 ppm. The rare-earth-modified ordinary alumina-supported metal oxide denitrification catalyst in this comparative example is a poor-performing catalyst. This catalyst lacks abundant hydroxyl anchoring sites on the hydroxylation support surface, making it difficult to achieve high dispersion loading of rare-earth metals and active metal precursors, resulting in large clusters and a reduction in effective active sites. Simultaneously, due to the scarcity of hydroxyl groups on the support surface, a tight electron transfer and structural bridge cannot be established between the rare-earth, alumina, and active components, weakening the electronic regulation effect of rare-earth on the active metal. The active metal still readily and non-selectively oxidizes NH3 to N2O or NO, leading to a decrease in nitrogen selectivity. Furthermore, ordinary alumina itself is prone to phase transformation and specific surface area loss under high-temperature hydrothermal conditions, and rare-earth metals also migrate and agglomerate due to the lack of strong anchoring sites, losing their ability to inhibit active metal sintering. Ultimately, this results in a significant deterioration in both the low-temperature denitrification activity and nitrogen selectivity of the catalyst after hydrothermal aging. The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A metal oxide denitration catalyst supported on an aging-resistant, highly selective metal-doped hydroxylated alumina support, characterized in that, The denitrification catalyst uses hydroxylated alumina as a support, transition metal oxides as active components, and rare earth metal elements as modifying agents. Rare earth metal-modified hydroxylation supports were obtained by modifying hydroxylated alumina with rare earth metal elements, and transition metal oxides were loaded onto the rare earth metal-modified hydroxylation supports.

2. The aging-resistant, highly selective metal-doped hydroxylated support-supported metal oxide denitration catalyst according to claim 1, characterized in that, The rare earth metal element is selected from at least one of cerium, lanthanum, samarium, praseodymium, neodymium, and gadolinium; the transition metal is selected from at least one of manganese, copper, iron, cobalt, molybdenum, tungsten, niobium, zirconium, and tin.

3. A method for preparing an aging-resistant, highly selective metal-doped hydroxyl-supported metal oxide denitration catalyst as described in any one of claims 1-2, characterized in that, The preparation method includes the following steps: a. Rare earth metal element modification of hydroxylation supports: The pseudoboehmite powder was dispersed in a solvent, then a modified metal precursor salt was added, stirred, the pH was adjusted to 9-10, stirring was continued, the mixture was filtered under reduced pressure, washed, dried, and the resulting white powder was calcined to obtain a rare earth metal modified hydroxyl support. b. Dispersion of active metal oxide precursor salts: The active metal precursor was dispersed in a solvent and sonicated to obtain a metal precursor salt solution. c. Loading of active metal oxide components: The metal precursor salt solution obtained in step b is added to the rare earth metal modified hydroxylated support obtained in step a above, stirred until it becomes muddy, dried, and the resulting powdered catalyst precursor is calcined to obtain a metal oxide catalyst supported on a metal-doped hydroxyl support. d. Hydrothermal aging treatment of denitrification catalysts: The metal oxide catalyst supported on a metal-doped hydroxyl support obtained in step c is calcined, and air containing water vapor is introduced during the calcination process to carry out hydrothermal aging treatment, thereby obtaining the metal oxide catalyst supported on a metal-doped hydroxyl support after hydrothermal aging treatment, which is the denitrification catalyst.

4. The preparation method according to claim 3, characterized in that, In step a, the solvent is at least one of water and ethanol; In step a, the modified metal precursor salt is a rare earth metal element precursor salt. In step a, the modified metal precursor salt is at least one of cerium nitrate hexahydrate, lanthanum nitrate hexahydrate, samarium nitrate hexahydrate, praseodymium nitrate hexahydrate, neodymium nitrate hexahydrate, and gadolinium nitrate hexahydrate; In step a, stir for 5-20 minutes, adjust the pH to 9-10 by adding ammonia dropwise, and continue stirring for 30-60 minutes. In step a, the washing process involves washing with water 3 to 4 times; In step a, the drying process involves placing the item in an oven at 80-100°C for 10-12 hours. In step a, the calcination is carried out in a muffle furnace under an air atmosphere at 400-550 °C for 2-5 h, with a heating rate of 2-5 °C / min.

5. The preparation method according to claim 3, characterized in that, In step a, the modified metal precursor salt is calcined to form a modified rare earth metal oxide component; the content of the modified rare earth metal oxide component is 3 to 20% of the mass of the rare earth metal modified hydroxylation carrier.

6. The preparation method according to claim 3, characterized in that, In step b, the solvent is at least one of water and ethanol; In step b, the ultrasound duration is 5-40 minutes; In step b, the active metal precursor is an active metal precursor salt, which is at least one of manganese nitrate tetrahydrate, copper nitrate trihydrate, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, ammonium molybdate tetrahydrate, ammonium metatungstate, niobium oxalate hexahydrate, zirconium nitrate pentahydrate, and tin tetrachloride pentahydrate, and does not overlap with the modified metal precursor salt.

7. The preparation method according to claim 3, characterized in that, In step c, the active metal precursor in the powdered catalyst precursor is calcined to form an active metal oxide component; the content of the active metal oxide component is 5-20% of the mass of the rare earth metal modified hydroxylated alumina support.

8. The preparation method according to claim 3, characterized in that, In step c, the drying process involves placing the item in an oven at 80-100°C for 10-12 hours. In step c, the calcination is carried out in a muffle furnace under an air atmosphere at 400-550 °C for 2-5 h, with a heating rate of 2-5 °C / min.

9. The preparation method according to claim 3, characterized in that, In step d, the calcination is performed by placing the furnace in a hydrothermal aging muffle furnace and calcining it at 650~800 ℃ for 24~50 h. In step d, the water vapor content in the air containing water vapor is 5-10% by mass. In step d, the hydrothermal aging treatment takes 24 to 50 hours.

10. The application of a metal oxide denitration catalyst supported on an aging-resistant, highly selective metal-doped hydroxylation support as described in any one of claims 1-2, characterized in that, The denitrification catalyst is used for low-temperature purification of nitrogen oxides in motor vehicle exhaust.

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