A highly dispersed denitration catalyst with a broadened active temperature range and its preparation process

Abstract

This invention relates to the field of denitrification catalyst preparation technology, specifically to a highly dispersed denitrification catalyst with a broadened active temperature range and its preparation process. This invention overcomes the problems of narrow active temperature range, low low-temperature activity, and poor resistance to poisoning found in traditional catalysts. A protective layer is constructed by in-situ hydrolysis modification of metatitanic acid slurry using tetraethyl orthosilicate and aluminum isopropoxide. During the impregnation stage, a methanesulfonic acid complexation system combined with ionic liquids induces high dispersion of multi-metal precursors, and the pH value is adjusted to prevent local hydrolysis and gelation of high-valence ions. An equal volume of the powder is sprayed into a carrier under strong fluidization using an acoustic spray device to avoid localized over-wetting and agglomeration, followed by long-term aging. Microwave rotary fluidized drying is used to achieve in-situ solidification of the components, and finally, the finished product is obtained through programmed temperature-controlled calcination. The resulting catalyst achieves good dispersion of the active components, broadens the active temperature range, and exhibits good sulfur and water resistance stability and high-temperature selectivity.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst preparation technology, specifically to a highly dispersed denitrification catalyst with a broadened active temperature range and its preparation process. Background Technology

[0002] Selective catalytic reduction (SCR) is the core technology for controlling nitrogen oxide (NOx) emissions from industrial flue gas. With the normalization of peak shaving in industrial kilns and power units, flue gas operating conditions fluctuate drastically, causing the operating temperature of denitrification systems to frequently switch within a wide range of 160-480℃. This necessitates that denitrification catalysts possess a wide activity temperature window to meet ultra-low emission requirements under all operating conditions.

[0003] However, the active components of traditional vanadium-titanium-based denitration catalysts typically rely on conventional kneading or uniform impregnation processes. Due to insufficient anchoring sites on the support surface, multi-metallic active components aggregate in heterogeneous systems, forming grains. The formation of coarse grains significantly reduces the specific surface area of ​​the catalyst, making ignition difficult at low temperatures below 300°C due to the shielding of active sites and the high activation energy of reductant adsorption. On the other hand, at high temperatures above 450°C, the amorphous active phase accelerates lattice aggregation and sintering under thermal stress, leading to the failure of active centers and micropore blockage due to capillary migration. To overcome this bottleneck, existing research attempts to introduce non-uniform loading methods such as ultrasonic mixing or co-precipitation to improve component dispersion. For example, in the research methods of wide-temperature-window denitration catalysts, although ultrasonication achieves good mixing of active components in the liquid phase, severe segregation and migration of the active precursor still occur during the subsequent precipitation and drying process due to the high surface energy of the support framework, resulting in a lack of strong molecular complexation and spatial binding between metal ions. Therefore, it is difficult to achieve long-term stable high dispersion of the active components deep within the micropores of the support, and strong electronic interactions between the metal and the support cannot be established. Consequently, the long-term operational stability of the catalyst over a wide active temperature range still fails to meet the expectations for industrial applications. Based on this, a highly dispersed denitrification catalyst with a broadened active temperature range and its preparation process are proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a highly dispersed denitrification catalyst with a broadened active temperature range and its preparation process. This overcomes the problems of narrow active temperature range, low low-temperature activity, and poor resistance to poisoning found in traditional catalysts. A protective layer is constructed by in-situ hydrolysis modification of metatitanic acid slurry using tetraethyl orthosilicate and aluminum isopropoxide. During the impregnation stage, a methanesulfonic acid complexation system combined with ionic liquids induces high dispersion of multi-metal precursors, and the pH value is adjusted to prevent local hydrolysis and gelation of high-valence ions. An ultrasonic spray device is used to spray the catalyst in equal volume onto a carrier under strong fluidization to avoid localized over-wetting and agglomeration of the powder, followed by long-term aging. Microwave rotary fluidized drying is then used to achieve in-situ solidification of the components, and finally, the finished product is obtained through programmed temperature-controlled calcination. The resulting catalyst achieves good dispersion of the active components, broadens the active temperature range, and exhibits good sulfur and water resistance stability and high-temperature selectivity.

[0005] To achieve the above objectives, the present invention provides a preparation process for a highly dispersed denitration catalyst that broadens the active temperature range: In-situ modification segment of S1 composite titanium carrier At 25-85℃, a titanate slurry is prepared into a suspension with a mass percentage concentration of 20%-45%. Under a stirring rate of 300-600 r / min, a mixture of tetraethyl orthosilicate, aluminum isopropoxide, acetylacetone, and anhydrous ethanol is added dropwise; wherein the acetylacetone acts as an inhibitor of rapid hydrolysis of aluminum isopropoxide, and its molar ratio with aluminum isopropoxide is 1-2:1. After the dropwise addition is complete, 1%-5% of polyetheramine is added according to the total mass of the slurry, and stirring is continued for 2-8 hours to induce in-situ hydrolysis and polycondensation of the silicon-aluminum components on the titanium matrix surface. The resulting mixed slurry is then dried in a pressure spray dryer to obtain composite titanium carrier powder.

[0006] Preferably, the treatment temperature of the suspension is 40-60℃.

[0007] Preferably, the volume ratio of the precursor to ethanol is 1:2 to 1:5.

[0008] Preferably, the molar ratio of silicon source precursor, aluminum source precursor and TiO2 molar amount converted in metatitanic acid is controlled to be (0.05-0.15):(0.02-0.08):1, and the dropping speed is limited to 3-15 mL / min.

[0009] Preferably, the pressure spray dryer is set with an inlet air temperature of 220-280℃, an outlet air temperature of 100-120℃, and an atomization pressure of 2.5-4.0MPa.

[0010] Preparation of S2 active impregnation solution Using a 10%-30% (w / w) aqueous methanesulfonic acid solution as the solvent, ammonium metavanadate, cerium nitrate, niobium oxalate, and zirconium nitrate were dissolved in proportion. First, ammonium metavanadate was dissolved in a portion of the methanesulfonic acid solution under heating at 50-80℃ and stirred until fully complexed and stable. Then, the system temperature was lowered to 30-40℃, and niobium oxalate solution, cerium nitrate solution, zirconium nitrate solution, and modifying agent solution were slowly added dropwise sequentially. Finally, an ionic liquid structure directing agent was added and the system was magnetically stirred until transparent, forming a precursor system with high complexation stability. The pH of the solution was adjusted to 1.5-2.5 using 5%-10% (w / w) dilute ammonia or dilute methanesulfonic acid solution to prevent localized excessive hydrolysis and precipitation of high-valence metal ions, ensuring that the multi-metal precursor remained in a stable, homogeneous ionic complex state.

[0011] The amount of the added ionic liquid structure directing agent is 0.5%-2% of the total mass of the active impregnation solution, that is, 4.0-11.5g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is added.

[0012] S3 Physical High-Pressure Ultrasonic Spray Load Section The composite titanium carrier dry powder is placed in a closed mixer equipped with agitating blades. The strong shear stirring of the closed mixer is activated, and the rotation speed is set to 100-300 r / min to maintain a uniformly dispersed fluidized state of the carrier dry powder within the mixer. While maintaining stirring, the active impregnation liquid is atomized and sprayed into the composite titanium carrier dry powder using a high-pressure ultrasonic spray device for equal-volume impregnation, matching the spray rate of the active impregnation liquid to prevent localized over-wetting and agglomeration of the powder. The core parameters for this step are defined as follows: The ultrasonic frequency is 40-100kHz, which eliminates the surface tension of the impregnation liquid through ultrasonic cavitation effect and prevents droplets from accumulating at the pores of the carrier. The liquid supply pressure is 0.3-1.0 MPa. This high-pressure environment ensures that the droplets have sufficient impact kinetic energy to overcome the exhaust resistance of the deep pores of the carrier and achieve deep penetration.

[0013] The spray rate is 5-20 mL / min, and after the spraying is completed, the product is sealed and aged at 40-60℃ for 12-24 h to achieve spontaneous and uniform diffusion of the components by utilizing capillary force.

[0014] S4 Microwave Rotary Fluidized Drying and Curing Section The aged material was transferred to a microwave rotary fluidized bed drying chamber, and the electromagnetic field was turned on with a frequency of 2450±50MHz and a power density of 5-25kW / m³. 3 Drying is carried out under the following conditions: the bed rotation speed is 10-30 r / min, and the fluidization air velocity is controlled at 0.5-1.5 m / s.

[0015] This step utilizes the selective heating properties of microwaves to rapidly migrate and instantly vaporize moisture from the inside out. The drying time is controlled between 5 and 20 minutes until the material moisture content is ≤3 wt%. This effectively locks the spatial position of active components and inhibits the thermal migration and aggregation of metal ions during conventional drying processes.

[0016] S5 Programmable Temperature Rising Roasting Section The dried granules are placed in a calcination furnace. A segmented temperature program is used: first, the temperature is increased to 250-300℃ at a rate of 2-10℃ / min and held for 1-2 hours to carbonize and remove organic components; then, the temperature is increased to 450-600℃ at the same rate and statically calcined in air for 4-8 hours. Finally, the furnace is allowed to cool naturally to room temperature to obtain the finished catalyst.

[0017] The catalyst exhibits a wide active temperature range, with a denitrification efficiency consistently above 90% within the range of 155℃ to 490℃, and the active components are uniformly dispersed on the support surface.

[0018] The raw material information used in this invention is as follows: the metatitanic acid slurry is selected from industrial-grade metatitanic acid from Longbai Group, with a solid content of 90wt%-95wt% based on TiO2, an average particle size D50 of 0.8-1.2μm, and a density of 3.9-4.2g / cm³. 3 The iron content is ≤100ppm. The tetraethyl orthosilicate is selected from Sinopharm Group analytical grade, with a purity ≥99.0%, SiO2 content of 28.4wt%, and density of 0.933g / cm³. 3 The refractive index nD20 is 1.382-1.384, and the CAS number is 78-10-4. Aluminum isopropoxide is selected from Saan Chemicals, with a purity ≥99.7%, Al2O3 content ≥25.0wt%, melting point 118-120℃, and CAS number 555-31-7. Polyetheramine is selected from Huntsman's Jeffamine D-2000, with a number-average molecular weight Mn of 2000-2200 Da, amine value of 1.0-1.1 meq / g, kinematic viscosity (25℃) of 242-250 cSt, and CAS number 9046-10-0. 1-Butyl-3-methylimidazolium tetrafluoroborate is selected from the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, with a purity ≥99%, moisture content ≤500ppm, dynamic viscosity (25℃) of 90-110 mPa·s, and CAS number 174501-65-6. The purity of methanesulfonic acid is ≥99.0%, and its density is 1.48 g / cm³. 3The metal precursor has a melting point of 20℃ and CAS number 75-75-2. The ammonium metavanadate has a purity ≥99.5% and a V₂O₅ content ≥77.5% and CAS number 7803-55-6. The cerium nitrate hexahydrate has a purity ≥99.9% and a CeO₂ content ≥39.0% and CAS number 10294-41-4. The niobium oxalate content is 17.5-19.0 wt% and CAS number 21348-59-4. The zirconium nitrate pentahydrate has a purity ≥99.9% and a ZrO₂ content ≥35.0% and CAS number 13746-89-9. The modifying agents are selected from ammonium paratungstate (CAS number 14311-52-5), ammonium molybdate (CAS number 12054-85-2), and sodium antimonate (CAS number 15432-85-6), all of analytical grade purity.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By introducing a methanesulfonic acid complex system and ionic liquid induction during the impregnation stage, the chemical compatibility of multi-metal precursors on the surface of composite titanium carrier is improved. Furthermore, by controlling the feeding process of multi-metals and adjusting the pH to low, local hydrolysis and precipitation of high-valence metal ions are avoided, the self-aggregation of active components during the loading process is inhibited, and multi-metals such as vanadium, cerium, niobium, and zirconium are dispersed in the micropores of the carrier.

[0020] 2. Microwave rotary fluidized bed drying is used instead of traditional static oven drying, and in-situ solidification of the active precursor is completed in a short time, thereby blocking the enrichment effect of metal ions carried by solvent migration to the outer surface of the carrier. Furthermore, high-shear fluidized bed stirring combined with ultrasonic spray loading solves the problem of local powder agglomeration during impregnation, ensuring material uniformity during industrial scale-up.

[0021] 3. In-situ hydrolysis modification of titanate slurry was carried out by tetraethyl orthosilicate and aluminum isopropoxide. The instantaneous burst hydrolysis of aluminum isopropoxide was suppressed by the coordination space protection of acetylacetone. A silicon-aluminum oxide protective layer with a specific pore structure was constructed on the surface of the support, which optimized the adsorption orientation of reactant molecules on the catalyst surface. Attached Figure Description

[0022] Figure 1 This is a comparison image of the transmission electron microscope (TEM) morphology of Embodiment 7 of the present invention; Figure 2 The X-ray diffraction (XRD) patterns of Example 7 and Comparative Example 4 of this invention are shown below. Figure 3 The X-ray photoelectron spectroscopy (XPS) spectra of Example 7 and Comparative Example 4 of this invention are shown below. Figure 4 The nitrogen adsorption-desorption isotherms of Example 7 and Comparative Example 4 of this invention are shown. Figure 5 The diagram shows the BJH aperture distribution curves of Embodiment 7 and Comparative Example 4 of the present invention. Figure 6 The results are the low-temperature denitrification activity test results of Examples 1-2, 4-6, 9, Comparative Examples 1-3 and Comparative Example 5 of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Please refer to... Figures 1 to 6 This invention provides a highly dispersed denitrification catalyst with a broadened active temperature range and its preparation process. The technical solution is as follows: Example 1

[0024] At 25℃, 1000g of metatitanic acid slurry (with a solid content of 92wt% based on TiO2, which translates to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a molar ratio of titanium to silicon and aluminum of 100:5:2 (i.e., 0.575 mol of elemental silicon and 0.230 mol of elemental aluminum are required), 119.8 g of tetraethyl orthosilicate (0.575 mol) and 47.0 g of aluminum isopropoxide (0.230 mol) were weighed. To inhibit the hydrolysis of aluminum isopropoxide, 46.1 g of acetylacetone (with a molar ratio of 2:1 to aluminum isopropoxide) was weighed and dissolved in 150 mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:3. This mixture was slowly added dropwise to the metatitanic acid suspension at a rate of 5 mL / min. Then, 30 g of polyetheramine was added, and the mixture was stirred continuously at 300 r / min for 5 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0025] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 3.5 MPa and the inlet air temperature controlled at 250°C and the outlet air temperature at 110°C for drying, to obtain composite titanium carrier dry powder.

[0026] The multi-metal active impregnation solution was then prepared according to the following steps: First, 11.5 g of ammonium metavanadate was weighed and dissolved in 300 mL of 18 wt% methanesulfonic acid aqueous solution under heating at 65 °C. The solution was magnetically stirred for 30 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 35 °C. The remaining 200 mL of methanesulfonic acid aqueous solution, containing 14.2 g of niobium oxalate, 20.3 g of cerium nitrate hexahydrate, 12.8 g of zirconium nitrate pentahydrate, and 8.5 g of ammonium paratungstate, was then slowly added dropwise. After the addition was complete, 7.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 2.0 using 8% (w / w) dilute ammonia solution. At this point, the solution was clear, with no gelling or precipitation observed. Ammonium paratungstate was used as a modifying agent.

[0027] 1000g of the composite titanium carrier dry powder was placed in a closed mixer, and strong shear stirring was started. The stirring speed was controlled at 200r / min to ensure that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 55kHz, and the feeding pressure was maintained at 0.4MPa. Based on a carrier pore volume of 0.5mL / g, 1000g of composite titanium carrier dry powder was sprayed with 500mL of active impregnation solution at a spraying rate of 10mL / min. The powder remained fluidized throughout, without localized agglomeration or mud formation. The mixture was stirred and aged for 10 hours. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 10kW / m³. 3 The material was dried in an electromagnetic field environment for 15 minutes. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 250°C at 2°C / min and held for 2 hours to carbonize and remove the organic components. Then, the temperature was increased to 500°C at 5°C / min and statically roasted in air for 5 hours. After natural cooling, the finished product was obtained.

[0028] Example 2

[0029] At 25℃, 1000g of metatitanic acid slurry (containing 92wt% solids as TiO2, equivalent to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a titanium to silicon to aluminum molar ratio of 100:8:3 (requiring 0.920 mol of elemental silicon and 0.345 mol of elemental aluminum), 191.7g of tetraethyl orthosilicate (0.920 mol) and 70.5g of aluminum isopropoxide (0.345 mol) were weighed. To inhibit the hydrolysis of aluminum isopropoxide, 51.8g of acetylacetone (with a molar ratio of 1.5:1 to aluminum isopropoxide) was further weighed and dissolved in 250mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:3.5. The mixture was slowly added dropwise to the metatitanic acid suspension at a rate of 8 mL / min, followed by the addition of 25 g of polyetheramine. The mixture was stirred continuously at 400 r / min for 6 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0030] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 3.0 MPa and the inlet air temperature controlled at 240°C and the outlet air temperature at 115°C for drying, to obtain composite titanium carrier dry powder.

[0031] The multi-metal active impregnation solution was then prepared according to the following procedure: First, 13.8 g of ammonium metavanadate was weighed and dissolved in 320 mL of a 15 wt% methanesulfonic acid aqueous solution under heating at 70 °C. The solution was magnetically stirred for 35 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 35 °C. The remaining 180 mL of methanesulfonic acid aqueous solution, containing 16.5 g of niobium oxalate, 23.1 g of cerium nitrate hexahydrate, 15.2 g of zirconium nitrate pentahydrate, and 9.8 g of ammonium paratungstate, was then slowly added dropwise. After the addition was complete, 6.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 1.8 using 6% (w / w) dilute ammonia solution. At this point, the solution was clear, and no gelling or precipitation was observed.

[0032] 1000g of the composite titanium carrier dry powder was placed in a sealed mixer, and strong shear stirring was started, with the stirring paddle speed controlled at 150r / min, so that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the above-mentioned transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 60kHz, the feeding pressure was maintained at 0.5MPa, and the spraying rate was 12mL / min. After spraying, the material was sealed and aged at 50℃ for 12h. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 12kW / m³.3 The material was dried in an electromagnetic field for 12 minutes until the moisture content was ≤3wt%. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 300℃ at 4℃ / min and held for 1 hour to carbonize and remove organic components. Then, the temperature was increased to 520℃ at a rate of 4℃ / min and statically roasted in air for 6 hours. After natural cooling, the finished product was obtained.

[0033] Example 3

[0034] At 25℃, 1000g of metatitanic acid slurry (containing 92wt% solids as TiO2, equivalent to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a titanium to silicon to aluminum molar ratio of 100:10:4 (requiring 1.150 mol of elemental silicon and 0.460 mol of elemental aluminum), 239.6g of tetraethyl orthosilicate (1.150 mol) and 94.0g of aluminum isopropoxide (0.460 mol) were weighed. To inhibit the hydrolysis of aluminum isopropoxide, 92.1g of acetylacetone (with a molar ratio of 2:1 to aluminum isopropoxide) was further weighed and dissolved in 300mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:3.2. The mixture was slowly added dropwise to the metatitanic acid suspension at a rate of 10 mL / min, followed by the addition of 35 g of polyetheramine. The mixture was stirred continuously at 450 r / min for 4 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0035] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 3.2 MPa and the inlet air temperature controlled at 260°C and the outlet air temperature at 110°C for drying, to obtain composite titanium carrier dry powder.

[0036] The multi-metal active impregnation solution was then prepared according to the following procedure: First, 12.5 g of ammonium metavanadate was weighed and dissolved in 300 mL of a 20 wt% methanesulfonic acid aqueous solution under heating at 60 °C. The solution was magnetically stirred for 40 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 38 °C. The remaining 200 mL of methanesulfonic acid aqueous solution, containing 15.0 g of niobium oxalate, 21.5 g of cerium nitrate hexahydrate, 14.0 g of zirconium nitrate pentahydrate, and 11.2 g of ammonium heptamolybdate, was then slowly added dropwise. After the addition was complete, 8.0 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 2.2 using 7% (w / w) dilute ammonia solution. At this point, the solution was clear, and no gelling or precipitation was observed.

[0037] 1000g of the composite titanium carrier dry powder was placed in a sealed mixer, and strong shear stirring was started, with the stirring paddle speed controlled at 250r / min, so that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the above-mentioned transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 70kHz, the feeding pressure was maintained at 0.6MPa, and the spraying rate was 15mL / min. After spraying, the material was sealed and aged at 55℃ for 14h. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 15kW / m³. 3 The material was dried in an electromagnetic field for 10 minutes until the moisture content was ≤3wt%. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 270℃ at 4℃ / min and held for 1.5h to carbonize and remove organic components. Then, the temperature was increased to 540℃ at a rate of 5℃ / min and statically roasted in air for 5h. After natural cooling, the finished product was obtained.

[0038] Example 4

[0039] At 25℃, 1000g of metatitanic acid slurry (with a solid content of 92wt% based on TiO2, which translates to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a titanium to silicon to aluminum molar ratio of 100:12:5 (i.e., requiring 1.380 mol of elemental silicon and 0.575 mol of elemental aluminum), 287.5 g of tetraethyl orthosilicate (1.380 mol) and 117.5 g of aluminum isopropoxide (0.575 mol) were weighed. To suppress the hydrolysis of aluminum isopropoxide, 69.1 g of acetylacetone (with a molar ratio of 1.2:1 to aluminum isopropoxide) was further weighed and dissolved in 350 mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:2.8. This mixture was slowly added dropwise to a metatitanic acid suspension at a rate of 12 mL / min, followed by the addition of 40 g of polyetheramine. The mixture was stirred continuously at 500 r / min for 7 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0040] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 2.8 MPa and the inlet air temperature controlled at 230°C and the outlet air temperature at 105°C for drying, to obtain composite titanium carrier dry powder.

[0041] The multi-metal active impregnation solution was then prepared according to the following procedure: First, 15.2 g of ammonium metavanadate was weighed and dissolved in 350 mL of a 25 wt% methanesulfonic acid aqueous solution under heating at 75 °C. The solution was magnetically stirred for 45 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 36 °C. The remaining 150 mL of methanesulfonic acid aqueous solution, containing 18.2 g of niobium oxalate, 25.4 g of cerium nitrate hexahydrate, 17.1 g of zirconium nitrate pentahydrate, and 12.5 g of ammonium heptamolybdate, was then slowly added dropwise. After the addition was complete, 9.2 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 1.6 using 9% (w / w) dilute ammonia solution. At this point, the solution was clear, and no gelling or precipitation was observed.

[0042] 1000g of the composite titanium carrier dry powder was placed in a sealed mixer, and strong shear stirring was started, with the stirring paddle speed controlled at 180r / min, so that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the above-mentioned transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 80kHz, the feeding pressure was maintained at 0.7MPa, and the spraying rate was 8mL / min. After spraying, the material was sealed and aged at 45℃ for 18h. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 18kW / m³. 3 The material was dried in an electromagnetic field for 15 minutes until the moisture content was ≤3wt%. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 250℃ at 2℃ / min and held for 2 hours to carbonize and remove organic components. Then, the temperature was increased to 550℃ at a rate of 3℃ / min and statically roasted in air for 4 hours. After natural cooling, the finished product was obtained.

[0043] Example 5

[0044] At 25℃, 1000g of metatitanic acid slurry (containing 92wt% solids as TiO2, equivalent to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a titanium to silicon to aluminum molar ratio of 100:6:2.5 (requiring 0.690 mol of elemental silicon and 0.288 mol of elemental aluminum), 143.7g of tetraethyl orthosilicate (0.690 mol) and 58.8g of aluminum isopropoxide (0.288 mol) were weighed. To inhibit the hydrolysis of aluminum isopropoxide, 57.7g of acetylacetone (with a molar ratio of 2:1 to aluminum isopropoxide) was further weighed and dissolved in 200mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:3.3. The mixture was slowly added dropwise to the metatitanic acid suspension at a rate of 6 mL / min, followed by the addition of 28 g of polyetheramine. The mixture was stirred continuously at 350 r / min for 5.5 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0045] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 3.5 MPa and the inlet air temperature controlled at 250°C and the outlet air temperature at 112°C for drying, to obtain composite titanium carrier dry powder.

[0046] The multi-metal active impregnation solution was then prepared according to the following procedure: First, 10.8 g of ammonium metavanadate was weighed and dissolved in 280 mL of 18 wt% methanesulfonic acid aqueous solution under heating at 68 °C. The solution was magnetically stirred for 30 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 34 °C. The remaining 220 mL of methanesulfonic acid aqueous solution, containing 13.1 g of niobium oxalate, 19.2 g of cerium nitrate hexahydrate, 11.9 g of zirconium nitrate pentahydrate, and 7.6 g of ammonium paratungstate, was then slowly added dropwise. After the addition was complete, 5.8 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 2.4 using 10% (w / w) dilute ammonia solution. At this point, the solution was clear, and no gelling or precipitation was observed.

[0047] 1000g of the composite titanium carrier dry powder was placed in a sealed mixer, and strong shear stirring was started, with the stirring paddle speed controlled at 220r / min, so that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the above-mentioned transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 50kHz, the feeding pressure was maintained at 0.4MPa, and the spraying rate was 11mL / min. After spraying, the material was sealed and aged at 50℃ for 16h. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 8kW / m³.3 The material was dried in an electromagnetic field for 18 minutes until the moisture content was ≤3wt%. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 300℃ at 3℃ / min and held for 1 hour to carbonize and remove organic components. Then, the temperature was increased to 510℃ at a rate of 4℃ / min and statically roasted in air for 7 hours. After natural cooling, the finished product was obtained.

[0048] Example 6

[0049] At 25℃, 1000g of metatitanic acid slurry (with a solid content of 92wt% based on TiO2, which translates to 920g of TiO2, or 11.5 mol) was mixed with 700mL of deionized water and stirred at 50Hz and 500rpm to form a suspension. Based on a titanium to silicon to aluminum molar ratio of 100:14:6 (i.e., requiring 1.610 mol of elemental silicon and 0.690 mol of elemental aluminum), 335.4 g of tetraethyl orthosilicate (1.610 mol) and 141.0 g of aluminum isopropoxide (0.690 mol) were weighed out. To inhibit the hydrolysis of aluminum isopropoxide, 110.5 g of acetylacetone (with a molar ratio of 1.6:1 to aluminum isopropoxide) was further weighed out and dissolved in 400 mL of anhydrous ethanol to prepare a mixture. At this point, the volume ratio of the metal precursor to ethanol was 1:2.6. This mixture was slowly added dropwise to a metatitanic acid suspension at a rate of 14 mL / min, followed by the addition of 45 g of polyetheramine. The mixture was stirred continuously at 550 r / min for 8 h to induce in-situ hydrolysis and condensation of the molecular precursor on the metatitanic acid surface.

[0050] The resulting mixed slurry was fed into a pressure spray dryer, with the atomization pressure set at 3.8 MPa and the inlet air temperature controlled at 270°C and the outlet air temperature at 100°C for drying, to obtain composite titanium carrier dry powder.

[0051] The multi-metal active impregnation solution was then prepared according to the following procedure: First, 16.5 g of ammonium metavanadate was weighed and dissolved in 380 mL of a 30 wt% methanesulfonic acid aqueous solution under heating at 80 °C. The solution was magnetically stirred for 50 min to ensure complete complexation and stability. Heating was then stopped, and the solution was allowed to cool to 39 °C. The remaining 120 mL of methanesulfonic acid aqueous solution, containing 20.1 g of niobium oxalate, 28.3 g of cerium nitrate hexahydrate, 19.5 g of zirconium nitrate pentahydrate, and 14.2 g of ammonium heptamolybdate, was then slowly added dropwise. After the addition was complete, 11.0 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added to the system. While maintaining stirring, the pH of the solution was adjusted to 1.5 using 5% (w / w) dilute ammonia solution. At this point, the solution was clear, and no gelling or precipitation was observed.

[0052] 1000g of the composite titanium carrier dry powder was placed in a sealed mixer, and strong shear stirring was started, with the stirring paddle speed controlled at 300r / min, so that the carrier powder was uniformly dispersed in a fluidized state within the mixer. 500mL of the above-mentioned transparent active impregnation solution was atomized and sprayed into the carrier using an ultrasonic spraying device for equal-volume impregnation. The ultrasonic frequency was controlled at 90kHz, the feeding pressure was maintained at 0.8MPa, and the spraying rate was 6mL / min. After spraying, the material was sealed and aged at 60℃ for 20h. The aged material was then fed into a microwave rotary fluidized bed drying chamber at a frequency of 2450MHz and a power density of 22kW / m³. 3 The material was dried in an electromagnetic field environment for 8 minutes until the moisture content was ≤3wt%. Finally, the dried material was placed in a programmable temperature controlled roasting furnace. First, the temperature was increased to 280℃ at 5℃ / min and held for 1.5h to carbonize and remove organic components. Then, the temperature was increased to 580℃ at a rate of 6℃ / min and statically roasted in air for 5h. After natural cooling, the finished product was obtained.

[0053] Example 7

[0054] The basic preparation steps of this embodiment are the same as those of Example 1, except that the amount of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid added in the active impregnation solution preparation stage is adjusted to 8.0 g, accounting for 1.32% of the total mass of the active impregnation solution; and the sealing and aging time at 50°C is extended to 24 h after the physical high-pressure ultrasonic spray loading is completed. The remaining composite carrier modification, controlled feeding, pH adjustment with dilute ammonia, stirring fluidized impregnation, microwave drying, and calcination processes are consistent with those of Example 1.

[0055] Microscopic morphology observation of the finished product; Figure 1 The active component in Example 7 is shown to be distributed as fine and uniform black dots on the surface of the carrier, with no obvious lattice stripes, proving that good dispersion has been achieved. Figure 2 The XRD pattern further confirms this: it only shows broad, blunt peaks of the support TiO2, without characteristic peaks of the active component, indicating that it is in an amorphous dispersion state. Figure 3 XPS spectra of the active metal energy levels were displayed. By performing peak fitting on the spectra, it can be seen that the binding energy of the active component in Example 7 has undergone a significant positive shift relative to the standard phase value, indicating that there is a strong electronic interaction between the well-dispersed metal phase and the modified support. This interaction is the root cause of the catalyst's excellent low-temperature activity.

[0056] Example 8

[0057] The basic preparation steps in this embodiment are the same as in Example 1, except that: in the active impregnation solution preparation section, the amount of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid added is adjusted to 10.0 g, and in the microwave curing and drying section, the electromagnetic field frequency is controlled at 2450 MHz and the power density is 20 kW / m². 3 Under these conditions, the mixture was rapidly dried by fluidization for 8 minutes. All other steps remained the same as in Example 1.

[0058] Example 9

[0059] The basic preparation steps in this embodiment are the same as in Example 1, except that in the final programmed temperature rise calcination stage, the temperature is first controlled to rise to 500°C at a fast flow rate of 12°C / min for isothermal calcination. All other steps remain the same as in Example 1.

[0060] Comparative Example 1 At 25℃, weigh 1000g of commercially available samples with a specific surface area of ​​150-200m². 2 Using ordinary spherical activated alumina as a carrier, the silicon-aluminum modification step was skipped. A multi-metal active impregnation solution was prepared: 11.5 g ammonium metavanadate, 20.3 g cerium nitrate hexahydrate, 14.2 g niobium oxalate, and 12.8 g zirconium nitrate pentahydrate were weighed and dissolved in 500 mL of 18 wt% methanesulfonic acid aqueous solution. The pH was adjusted to 2.0 using 10% dilute ammonia, and 7.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added. The alumina carrier was placed in a closed mixer, and the powder was fluidized by controlling the strong shear stirring speed at 200 r / min. An equal volume of the impregnation solution was sprayed into 500 mL using a high-pressure ultrasonic sprayer with a frequency of 55 kHz and a feeding pressure of 0.4 MPa, controlling the spray rate at 10 mL / min. The mixture was stirred and aged for 10 h. The aged material was then fed into a microwave rotary fluidized bed dryer and dried for 15 min, finally calcined at 500 °C for 5 h at a rate of 5 °C / min.

[0061] Comparative Example 2 In preparing the active impregnation solution, the 18wt% methanesulfonic acid aqueous solution in Example 1 was replaced with a dilute nitric acid aqueous solution of the same pH value. Specifically, the same amount of metal salt components as in Example 1 were weighed and dissolved in 500 mL of dilute nitric acid using a controlled-order feeding method with ammonium metavanadate, niobium oxalate, cerium nitrate, zirconium nitrate, and additives. The pH was adjusted to 2.0 using 10% dilute ammonia, and 7.5 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added. Except for the change in the solvent system of the impregnation solution, the preparation of the composite titanium carrier, the high-shear fluidized ultrasonic spraying process, the microwave drying, and the final calcination process remained consistent with Example 1.

[0062] Comparative Example 3 Except for the omission of 7.5g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid when preparing the multi-metal active impregnation solution, the other carrier modification, controlled feeding, low pH dilute ammonia water system, high shear fluidized ultrasonic spray, microwave drying and final calcination processes are consistent with those in Example 1; at the same time, deionized water is used to make up the corresponding mass.

[0063] Comparative Example 4 The drying step following fluidized spray impregnation and aging in Example 1 was replaced. Specifically, the wet material after aging for 10 hours was not microwave-dried, but instead placed directly in a conventional constant temperature forced-air drying oven and statically dried at 110°C for 12 hours. The remaining steps of carrier modification, impregnation solution preparation, fluidized ultrasonic spraying, and calcination were consistent with those in Example 1.

[0064] The adsorption performance of the catalyst was tested. Figure 4 The N2 adsorption-desorption isotherm curves in Example 7 show a typical type IV isotherm and a significant H2 hysteresis loop, indicating that it maintains a good mesoporous structure. Figure 5 The BJH pore size distribution curves show that the pore size of Example 7 is concentrated in the range of 8-12 nm, with narrow and high peaks; while the pore volume of Comparative Example 4 is significantly reduced and the peaks are diffuse, indicating that the migration of components during the conventional drying process leads to severe pore blockage, which also structurally explains the poor sulfur and water resistance of Comparative Example 4.

[0065] Comparative Example 5 This comparative example aims to eliminate variables related to the synergistic effects of multi-metal (cerium, niobium, zirconium) chemistry, demonstrating its irreplaceable role in wide-temperature-range catalysis, rather than comparing the process itself. The preparation steps, except for the use of only 11.5g ammonium metavanadate and 28.6g ammonium paratungstate dissolved in 500mL of 18wt% methanesulfonic acid aqueous solution during impregnation using a controlled-order feeding method, without adding cerium nitrate, niobium oxalate, or zirconium nitrate components, were consistent with Example 1 in all aspects, including carrier modification, pH adjustment with dilute ammonia, and subsequent fluidized bed stirring, ultrasonic spraying, and microwave drying. The missing substances were replenished using an equal mass of deionized water.

[0066] Comparative Example 6 This comparative example uses a conventional process with traditional commercial catalysts as a creative control group for the entire process. The specific steps are as follows: 1000g of unmodified commercial titanium dioxide powder was directly selected as the carrier, skipping the S1 in-situ silicon-aluminum modification and acetylacetone protection process. When preparing the impregnation solution, the methanesulfonic acid system and ionic liquids were abandoned, and a traditional inorganic oxalic acid system was used instead: 11.5g of ammonium metavanadate and 28.6g of ammonium paratungstate were weighed and dissolved in 500mL of deionized water, and 45g of oxalic acid was added as a complexing agent. The solution was stirred and dissolved at 70℃. The pH of the system was adjusted to 3.0 by direct back-titration with 25% concentrated ammonia solution. At this point, slight turbidity appeared in some areas of the solution due to excessive alkalinity.

[0067] During the loading stage, the titanium dioxide support powder was placed in a conventional kneading pan, and the aforementioned oxalate impregnation solution was poured in directly for conventional impregnation without high-pressure ultrasonic spraying or high-shear fluidized stirring. After impregnation, the material was allowed to stand at room temperature for 10 hours. Subsequently, the wet material was not microwave-dried, but was directly placed in a conventional constant-temperature forced-air drying oven and statically dried at 110°C for 12 hours. The dried material was then placed directly in a muffle furnace and statically calcined at 500°C for 5 hours at a rate of 10°C / min, followed by natural cooling to obtain the finished control catalyst.

[0068] After the preparation of each catalyst group, their basic catalytic performance was systematically evaluated using a simulated flue gas reaction device. Test Example 1 investigated the denitrification efficiency and high-temperature selectivity of the catalyst under different temperature gradients, aiming to define its active temperature range. Referring to GB / T 31587-2015 "Honeycomb Flue Gas Denitrification Catalysts" and making adjustments, the powdered catalyst was pressed into tablets and crushed to 40-60 mesh as experimental samples. A fixed-bed quartz tube reactor (10 mm inner diameter) was used. 0.5 g of catalyst particles were physically diluted and mixed with 2.5 g of quartz sand of the same mesh size, and then filled into the middle of the quartz tube. Both ends of the catalyst layer were sealed and fixed with acid-washed high-purity quartz fiber cotton to prevent displacement or porosity fluctuations of the catalyst under high-speed gas flow. A K-type thermocouple was installed inside the quartz tube, with the thermocouple tip tightly attached to the center of the catalyst bed to ensure real-time and accurate temperature measurement.

[0069] The simulated flue gas composition was NO 500 ppm, NH3 500 ppm - ammonia nitrogen ratio 1.0, O2 5 vol%, N2 as balance gas, and the space velocity (GHSV) was set to 50,000 h⁻¹. -1 The reactor was heated from 100℃ to 550℃ at a rate of 5℃ / min. After stabilizing at each set temperature for 30 minutes, the concentrations of NO, NO2, NH3, and N2O in the inlet and outlet flue gas were monitored in real time using a multi-component infrared flue gas analyzer. The low-temperature denitrification activity (η160), the activity temperature window (ΔT), and the high-temperature selectivity (S) were evaluated. NH3 The tests were conducted. The final test results are summarized in Table 1 and... Figure 6 middle.

[0070] Table 1. Test results of catalytic activity and active temperature window

[0071] The test results above show that Examples 1-2, 4-6, and 9 all exhibited a wide active temperature range, mainly due to the complexation effect of the methanesulfonic acid system on the multi-metal components and the synergistic effect of the multi-metals. Example 4 enhanced the low-temperature reaction rate by increasing the loading amount; Example 5 enhanced the strong interaction between the active component and the support by increasing the calcination temperature, significantly improving the high-temperature selectivity. Comparative Example 1 lacked the silicon-alumina modification process, resulting in a lack of microporous anchoring points on the support surface. The interaction between the ordinary alumina support and the active component was weak, the active sites were sparsely distributed and easily sintered by heat, causing a significant shift in the low-temperature ignition temperature. Comparative Example 2's inorganic strong acid system lacked the steric hindrance effect of the large molecules of methanesulfonic acid. Due to differences in solubility, the various metal precursors competed for adsorption in the impregnation solution, disrupting the uniformity of the active centers and leading to a narrowing of the active temperature range. Comparative Example 3 lacks the 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. As a structure-directing agent, the electrostatic stabilizing effect of the ionic liquid is crucial in the atomization and spraying stage of the impregnation solution. Without this component, precursor droplets physically accumulate on the support surface, leading to increased side reactions and deteriorated selectivity in the high-temperature region. Comparative Example 5 lacks the cerium, niobium, and zirconium modification components, relying solely on the vanadium-tungsten system. Due to the lack of the redox cycling capability of the cerium component and the surface acidity compensation of niobium and zirconium, the catalyst cannot maintain a high conversion rate over an ultrawide temperature range, especially at high temperatures where NH3 escapes. Comparative Example 6 was prepared using existing conventional techniques. Experimental data show that Comparative Example 6 exhibits poor low-temperature activity and a severely narrowed temperature range. This indicates that only under the premise of strictly synergistic in-situ protection of the silicon-aluminum support, controlled feeding, low-pH stable complexation, high-shear fluidized ultrasonic spraying, and microwave instantaneous in-situ curing and drying, can the present invention generate strong chemical synergy among the components, endowing the catalyst with high dispersion and an ultrawide service temperature window.

[0072] After clarifying the activity characteristics of the catalyst, in order to further verify the structural stability and long-term service capability of the highly dispersed system under complex industrial conditions, Test Example 2 was used to investigate the activity retention rate of the catalyst in sulfur-containing and water-containing environments and to evaluate the dispersion.

[0073] The main tests focused on the sulfur and water resistance and microstructural stability of Examples 1, 3, 7-8, and Comparative Example 4. Referring to the corresponding national standard for Example 1, the catalyst's mid-temperature active point of 280℃ was selected for isothermal stability testing. Poisoning agent introduction: Based on the standard simulated flue gas composition, an additional 100 ppm of SO2 was introduced via MFC. Simultaneously, deionized water was injected into the preheating vaporization chamber using a micro-injection pump. After vaporization, it entered the reactor with the flue gas, ensuring a water vapor content of 10 vol% in the mixed gas. The system was run continuously for 100 hours, with the catalyst loading amount consistent with Example 1. The system was run continuously for 100 hours under sulfur and water-containing conditions, with NOx conversion recorded every hour. The difference in conversion rate between the start and end times of the 100-hour run was calculated to determine the activity decay rate.

[0074] The average particle size was calculated using transmission electron microscopy (TEM) combined with XRD diffraction peak broadening. The tested catalyst sample was ultrasonically dispersed in ethanol and then dropped onto a coated copper grid. At least 100 active component particles were randomly selected, and their average diameter was calculated. XRD testing was performed using an X-ray diffractometer with a scanning range of 2θ = 10°–80°. The average grain size was calculated based on the strongest diffraction characteristic peaks of the active components (such as V₂O₅ or CeO₂), and the results were compared and verified with the TEM statistical results.

[0075] The dispersion (D) test method employed H2-programmed temperature reduction (H2-TPR) combined with CO pulsed chemisorption. 100 mg of catalyst sample was placed in a U-shaped quartz reaction tube and pretreated at 300 °C for 1 h under a nitrogen atmosphere to remove surface-adsorbed moisture and impurities. After cooling to room temperature, a helium-gas mixture containing 5% CO was introduced for pulsed adsorption experiments. The dispersion (D) of the active component was defined as the percentage of active metal atoms exposed on the catalyst surface to the total number of metal atoms in the catalyst. Based on the saturated adsorption capacity of CO and the stoichiometric ratio of the active metals, the dispersion was calculated. A higher dispersion value, approaching 100%, indicates good dispersion of active sites. The final test results are shown in Table 2.

[0076] Table 2. Results of sulfur resistance, water resistance, and microstructural stability tests

[0077] The average particle size of the example groups remained below 1.5 nm, demonstrating that microwave rotary fluidized drying can achieve rapid in-situ solidification of components and prevent component migration. The high dispersibility of the examples is mainly due to the dual confinement effect of the methanesulfonic acid complex system and the 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. The methanesulfonic acid aqueous solution and the ionic liquid together improve the acid stability and dispersion stability of the impregnation solution; the dispersibility of Example 7 reached the highest value, indicating that the matching of long-term aging and fluidized ultrasonic spraying enabled the active components to achieve maximum uniform spreading on the silica-alumina microporous sites on the surface of the composite titanium carrier.

[0078] In contrast, Comparative Example 4 used conventional oven drying. During the prolonged conventional heating process, the heat flow direction and solvent gradient caused active metal ions to migrate with the solvent to the outer surface of the support, resulting in severe phase separation and the formation of large-particle oxide crystals. This agglomeration significantly reduced the active specific surface area. Furthermore, under conditions containing SO2 and H2O, the large-particle active sites were more easily poisoned by ammonium sulfate, leading to a surge in the activity decay rate after 100 hours. Additionally, the dispersion decreased significantly, and there were significant thermal and moisture evaporation gradients within the material. The migration of active metal salts with the solvent to the outer surface of the support resulted in a large amount of disordered self-agglomeration, causing the metal particles to transform into a bulk state. A large amount of active metal remained inside the agglomerates rather than exposed on the surface, leading to a sharp decrease in CO chemisorption.

[0079] The activity scan of Test Example 1 shows that the catalyst successfully overcomes the limitations of traditional catalysts, such as slow ignition in the low-temperature region and poor selectivity in the high-temperature region, through the electronic synergistic effect of the composite titanium support and the multi-metal active components, achieving stable denitrification in an ultra-wide temperature range of 160℃ to 480℃. The stability characterization of Test Example 2 further confirms that the preparation process based on high-pressure ultrasonic spray impregnation and microwave rotary fluidized drying can firmly anchor the active metal phase in the microporous structure of the support, maintaining a highly dispersed state, thereby effectively blocking the aggregation path of active sites under thermal load and chemical poisoning. The experimental data fully demonstrate that only under the premise of strictly synergistic modification of the composite support, the methanesulfonic acid complexation system, ionic liquid induction, and drying and calcination processes can the catalyst be endowed with low particle size of active components and good sulfur and water resistance, providing reliable support for solving the ultra-low emission requirements of industrial flue gas under large fluctuations in operating conditions.

[0080] 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 preparation process for a highly dispersed denitration catalyst with a broadened active temperature range, characterized in that, The preparation process is as follows: a vanadium source precursor is dissolved in a methanesulfonic acid aqueous solution to obtain a vanadium source solution; precursors of cerium source, niobium source and zirconium source and the remaining methanesulfonic acid aqueous solution are added to the vanadium source solution, and an ionic liquid is added to obtain an active impregnation solution; Based on the mass of the composite titanium carrier dry powder as 100%, the loading amounts of vanadium, cerium, niobium, and zirconium metal elements in the active impregnation solution are 0.45%-0.75%, 0.25%-0.42%, 0.60%-0.95%, and 0.25%-0.45%, respectively; the preparation process includes atomizing and spraying the active impregnation solution into the composite titanium carrier for impregnation; The composite titanium carrier is obtained by introducing silicon and aluminum precursors into a metatitanic acid suspension, performing in-situ hydrolysis and condensation reaction, and then drying.

2. The preparation process of the highly dispersed denitration catalyst with a broadened active temperature range according to claim 1, characterized in that, The mass percentage concentration of metatitanic acid slurry in the suspension is 20%-45%; the silicon source precursor, the aluminum source precursor, and acetylacetone are dissolved in anhydrous ethanol to prepare a mixture; the mixture is added dropwise to the suspension, and the dropwise addition rate is controlled at 3-15 mL / min, with the molar ratio of acetylacetone to the aluminum source precursor being 1-2:1; 1%-5% of polyetheramine is added according to the total mass of the slurry, and the in-situ hydrolysis and polycondensation are carried out by stirring.

3. The preparation process of the highly dispersed denitration catalyst with a broadened active temperature range according to claim 2, characterized in that, The silicon source precursor is tetraethyl orthosilicate, and the aluminum source precursor is aluminum isopropoxide; the molar ratio of the silicon source precursor, the aluminum source precursor and TiO2 in metatitanic acid is (0.05-0.15):(0.02-0.08):

1.

4. The preparation process of the highly dispersed denitration catalyst with a broadened active temperature range according to claim 1, characterized in that, The active impregnation solution also contains a modifying agent selected from salt solutions of tungsten, molybdenum, or antimony.

5. The preparation process of the highly dispersed denitrification catalyst with a broadened active temperature range according to claim 4, characterized in that, The vanadium source in the precursor is ammonium metavanadate, the cerium source is cerium nitrate, the niobium source is niobium oxalate, and the zirconium source is zirconium nitrate. The ammonium metavanadate, cerium nitrate, niobium oxalate, and zirconium nitrate are dissolved in an aqueous methanesulfonic acid solution, and the pH of the solution is adjusted to 1.5-2.5 using 5%-10% by mass of dilute ammonia or dilute methanesulfonic acid solution. The ammonium metavanadate is dissolved in 56%-76% of the aqueous methanesulfonic acid solution by volume, and the cerium nitrate, niobium oxalate, zirconium nitrate, and the remaining 24%-44% of the aqueous methanesulfonic acid solution are added. The ionic liquid is selected from one or more of imidazole, pyridine, or quaternary ammonium salt ionic liquids.

6. The preparation process of the highly dispersed denitration catalyst with a broadened active temperature range according to claim 1, characterized in that, The active impregnation liquid is atomized and sprayed into the composite titanium carrier dry powder under the conditions of ultrasonic frequency of 40-100kHz and feeding pressure of 0.3-1.0MPa; the impregnation liquid is atomized and sprayed into the composite titanium carrier dry powder by equal volume impregnation and sealed aging.

7. A highly dispersed denitration catalyst with a broadened active temperature range prepared according to the process described in claim 1, characterized in that, It includes a composite titanium carrier and a multi-metal active component loaded on the composite titanium carrier.

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