A Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis and its application in the catalytic combustion of chlorine-containing volatile organic compounds (CVOCs).

Abstract

The application relates to a Ru-W-CeO2 catalyst prepared by a one-step flame spray pyrolysis method and application of the catalyst in catalytic combustion of chlorine-containing volatile organic compounds (CVOCs), wherein the catalyst comprises the following components and weight percentage contents (calculated based on the weight of a CeO2 carrier): Ru: 0.3%-1.5%, and W: 1.0%-9.0%. The application utilizes a flame spray pyrolysis technology to precisely control the grain size of the CeO2 carrier, and constructs a catalyst structure which is superfine-grained and rich in surface defects; meanwhile, in-situ co-doping of Ru, W and CeO2 is realized by a one-step method, and the components are uniformly dispersed. The obtained catalyst has excellent low-temperature activity and outstanding thermal stability in catalytic combustion of chlorine-containing volatile organic compounds.

Description

Technical Field

[0001] This invention relates to a Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis and its application in the catalytic combustion of chlorine-containing volatile organic compounds (CVOCs), belonging to the field of air pollution control. Background Technology

[0002] Chlorine-containing volatile organic compounds (CVOCs) mainly originate from industries such as petrochemicals, pharmaceuticals, and waste incineration. Typical pollutants include vinyl chloride (VC), dichloroethane (DCE), and chlorobenzene (CB). These substances are chemically stable, highly toxic, and easily transform into highly toxic substances such as dioxins in the environment, posing a serious threat to the ecosystem and human health. Catalytic combustion can completely mineralize CVOCs into CO2, H2O, and HCl at relatively low temperatures, offering advantages such as low energy consumption and minimal secondary pollution, making it one of the mainstream end-of-pipe treatment technologies. CeO2, due to its unique Ce... 3+ / Ce 4+ Reversible redox pairs possess excellent oxygen storage and release capabilities and redox performance, making them widely used in the catalytic combustion of CVOCs. This capability of CeO2 is significantly influenced by its particle size; smaller CeO2 particles typically exhibit higher oxygen activity (Angew. Chem. Int. Ed., 2004, 43, 2538-2540). However, CVOC catalytic combustion is a strongly exothermic reaction, and in actual operation, the bed temperature can instantly spike to over 500 °C. Small-sized CeO2 particles with high activity also have high surface energy, making them highly susceptible to particle sintering, leading to a sharp decline in catalytic performance. Studies have shown that the introduction of noble metals (such as Ru) can effectively inhibit the aggregation of CeO2 at high temperatures and improve the thermal stability of the catalyst (J. Catal., 2022, 411, 122-134). Simultaneously, during the catalytic combustion of CVOCs, Ru species can promote the removal of chlorine species through the Deacon reaction, inhibiting chlorine poisoning of the catalyst. However, the Deacon reaction typically requires relatively high temperatures (>250 °C) to proceed effectively. Therefore, to further improve the desorption efficiency of chlorine species below 250 °C, acidic promoters (such as W, Nb, etc.) are often introduced to utilize their synergistic effect to promote the low-temperature removal of chlorine species and improve the low-temperature performance of the catalyst. However, the binding ability of such acidic promoters on the CeO2 surface is usually stronger than that of Ru species, leading to competition for site placement and resulting in large-sized RuO2. x Particle formation weakens RuO xThe strong interaction between Ru and CeO2 (Environ. Sci. Technol., 2024, 58, 20300-20312). This phenomenon leads to Ru species being unable to effectively bind to CeO2 particles when the catalyst bed experiences runaway temperatures, thereby triggering RuO2 degradation. x The significant aggregation of CeO2 particles greatly weakens the catalyst's resistance to thermal shock. This demonstrates that the introduction of acidic additives often leads to a "seesaw effect" between low-temperature activity and thermal shock resistance. Therefore, the key to overcoming this "seesaw effect" lies in mitigating the competitive precipitation effect between acidic additives and precious metal species, and strengthening the synergistic effect among the components. Theoretically, co-precipitation can achieve synchronous and uniform distribution of multiple components, thereby suppressing the competitive precipitation of acidic components and Ru species. However, in conventional co-precipitation processes, the pH (<1) required for complete precipitation of acidic additives differs significantly from the pH (>7) required for complete precipitation of other metal components such as Ce ions, making it difficult to achieve efficient synchronous co-precipitation of all components in practical operation. In summary, there is an urgent need to develop novel synthetic strategies to precisely control the microstructure of catalysts at the atomic / nanoscale, fundamentally resolving the contradiction between low-temperature activity and high-temperature stability in acid-modified Ru-CeO2 systems, and achieving a synergistic improvement in both. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis and its application in the catalytic combustion of chlorine-containing volatile organic compounds (CVOCs). The Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to the present invention comprises the following components and weight percentages (based on the weight of CeO2 support): Ru: 0.3%~1.5%, W: 1.0%~9.0%. This invention also provides a method for preparing a Ru-W-CeO2 catalyst by flame spray pyrolysis in one step, comprising the following steps: Ruthenium, tungsten, and cerium precursors were dissolved in a mixed solvent of glacial acetic acid and 2-ethylhexanoic acid, and stirred in a water bath at 50–70 °C for 3–6 hours to prepare a solution with a Ce concentration of 0.05–0.5 mol·L⁻¹. -1The precursor solution was then injected into a burner via a syringe at a constant flow rate of 1.0–15.0 ml / min. The solution was atomized with the assistance of oxygen (partial pressure 100–180 kPa) as the dispersion gas and burned in a flame maintained at a hydrogen flow rate of 3.0–4.0 L / min and an air flow rate of 15–17 L / min. The product was quenched and collected through a glass fiber filter membrane. The collected powder was calcined in air at 300–450 °C for 2–4 hours to obtain the catalyst product. The present invention also provides an application of the Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis, wherein the catalyst is used for the catalytic combustion of chlorinated volatile organic compounds (CVOCs), wherein the chlorinated volatile organic compounds are vinyl chloride (VC) or dichloroethane (DCE). Furthermore, the catalytic combustion reaction conditions are as follows: when applied to the catalytic combustion of vinyl chloride (VC), the concentration of vinyl chloride (VC) is 1000 ppm, and the reaction space velocity is 30,000 mL·g. -1 ·h -1 When applied to the catalytic combustion of dichloroethane (DCE), the concentration of DCE is 1000 ppm and the reaction space velocity is 30,000 mL·g. -1 ·h -1 . This invention employs flame spray pyrolysis technology to prepare Ru-W-CeO2 catalysts. An ultra-high temperature flame (>2000 °C) drives the precursor solution to instantaneously vaporize, combust, and nucleate, followed by a cooling rate as high as 10⁻⁶ during millisecond-level gas transport. 5 ~10 6 Ultra-fast quenching at K / s. This extreme non-equilibrium thermodynamic process can not only achieve instantaneous "freezing" of grain growth, thereby accurately obtaining nano-CeO2 with extremely small grain size, but also completely preserve the abundant lattice defects formed at high temperature (such as high-density oxygen vacancies, lattice distortion and unsaturated coordination sites) in the CeO2 nanolattice, providing a large number of active sites for catalytic combustion reaction. More importantly, this invention employs a flame spray pyrolysis method to synthesize Ru-W-CeO2 catalyst in one step, fundamentally overcoming the limitations of the co-precipitation method due to the influence of W. 6+ (Complete precipitation pH < 1), Ru 3+ (Complete precipitation pH>7) and Ce 3+The precipitation windows (pH>9 for complete precipitation) vary significantly, making it difficult to achieve uniform and efficient co-precipitation of multiple components. In this one-step method, Ru, W, and Ce precursors achieve instantaneous uniform mixing and co-pyrolysis at the atomic / molecular scale in the gas phase, followed by co-nucleation and self-assembly processes, allowing W and Ru species to be embedded in situ and uniformly within the CeO2 lattice. This avoids the crowding-out effect of acidic W species on Ru species caused by preferential occupancy during stepwise impregnation, achieving spatial interweaving and balanced distribution of Ru and W species at the atomic scale. This structural advantage enables the Ru-W-CeO2 catalyst prepared by flame spray pyrolysis in one step to maintain extremely strong anti-sintering ability even when facing sudden ultra-high temperature (>500 ℃) thermal shocks during long-term industrial operation, thus breaking the "seesaw effect" between low-temperature activity and thermal stability. Compared with the prior art, the present invention has the following beneficial effects: (1) By utilizing the non-equilibrium ultra-fast cooling characteristics of flame spray pyrolysis technology, the grain size of CeO2 is precisely controlled, and the abundant intrinsic defects generated at high temperature are "frozen" in the lattice, thus preparing Ru-W-CeO2 catalyst with extremely small grains and abundant active sites. (2) In-situ co-doping of Ru and W species in CeO2 lattice was achieved by flame spray pyrolysis in one step, which effectively suppressed the surface migration and aggregation of W and Ru species and the sintering of CeO2 support under high temperature oxidizing atmosphere, and achieved synergistic improvement of low temperature activity and high temperature stability. Attached Figure Description Figure 1 The effect of preparation method on catalyst activity; Figure 2 The effect of preparation method on the high-temperature stability of catalyst; Figure 3 The effect of precursor liquid flow rate on the catalytic combustion performance of vinyl chloride (VC); Figure 4 XRD patterns of Ru-W-CeO2 catalysts prepared for different precursor liquid flow rates; Figure 5 The effect of Ru loading on the catalytic activity of Ru-W-CeO2 catalyst for vinyl chloride (VC); Figure 6 The effect of W loading on the catalytic activity of Ru-W-CeO2 catalyst for vinyl chloride (VC); Figure 7 The effect of the order of introduction of W species on the catalytic combustion performance of vinyl chloride (VC); Figure 8 The effect of the introduction order of W species on the catalytic combustion performance of dichloroethane (DCE); Figure 9The graph shows the vinyl chloride (VC) cycle test results for the Ru-W-CeO2 catalyst. Figure 10 The graph shows the thermal shock resistance test results of the Ru-W-CeO2 catalyst in a vinyl chloride (VC) atmosphere. Figure 11 The effect of water introduction on the activity of Ru-W-CeO2 catalyst; Figure 12 This is a graph showing the water stability test results for the Ru-W-CeO2 catalyst. Detailed Implementation The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Comparative Example 1 Preparation of CP-1.0 wt.%Ru-1.0 wt.%W-CeO2 catalyst: 10.0 g of cerium ammonium nitrate and 7.5 g of sodium hydroxide were dissolved in 25 mL and 50 mL of deionized water, respectively. After stirring for 30 minutes, cerium ammonium nitrate solution and sodium hydroxide solution were obtained. Subsequently, 3.2 g of nitrosylruthenium nitrate solution (0.98 wt.%) and 0.045 g of ammonium tungstate precursor were added to the cerium ammonium nitrate solution, and after stirring for 30 minutes, a mixed precursor solution was obtained. Then, under stirring conditions, the prepared sodium hydroxide solution was quickly poured into the mixed solution, and after stirring for 2 hours, it was allowed to stand at room temperature for 48 hours. After aging, the solid product was separated by filtration, and then the obtained solid product was washed alternately with deionized water and anhydrous ethanol. The washed solid was dried in an oven at 80 °C for 16 hours, and then calcined in air at 450 °C for 3 hours to obtain the desired catalyst product, denoted as CP-1.0 wt.%Ru-1.0 wt.%W-CeO2. Comparative Example 2 Preparation of CP-1.0 wt.%Ru-CeO2 catalyst: No ammonium tungstate precursor was added; all other steps were the same as in Comparative Example 1. The resulting catalyst is denoted as CP-1.0 wt.%Ru-CeO2. Comparative Example 3 Preparation of 1.0 wt.% Ru-CeO2 catalyst: 4.76 g of cerium acetate and 0.27 g of ruthenium nitrite (9.51 wt.%) were dissolved in 160 mL of a mixed solvent consisting of glacial acetic acid and 2-ethylhexanoic acid in a volume ratio of 1:1. The mixture was stirred in a water bath at 60 °C for 5 hours to obtain a Ce concentration of 0.1 mol·L⁻¹. -1The precursor solution was injected into the burner via a syringe at a constant flow rate of 2.5 mL / min. It was atomized with the assistance of oxygen (partial pressure 150 kPa) as the dispersion gas and burned in a flame maintained at a hydrogen flow rate of 3.3 L / min and an air flow rate of 16.7 L / min. The product was quenched and collected through a glass fiber filter membrane. The collected powder was calcined at 400 °C for 2 hours in air to obtain the desired catalyst product, denoted as 1.0 wt.% Ru-CeO2. Comparative Example 4 Preparation of 1.0 wt.%Ru / 1.0 wt.%W-CeO2 catalyst: The precursor salt was replaced with 0.036 g ammonium tungstate and 4.76 g cerium acetate, with the remainder the same as in Comparative Example 3. The resulting catalyst was named W-CeO2. 1.19 g of W-CeO2 support was placed in 0.458 g of deionized water and stirred for 1 hour. 0.13 g of ruthenium nitrite nitrate solution (9.51 wt.%) was added, and the mixture was stirred for 30 minutes. After standing at room temperature for 6 hours, it was dried at 80 °C for 16 hours and finally calcined in air at 400 °C for 3 hours to obtain the desired catalyst product, denoted as 1.0 wt.%Ru / 1.0 wt.%W-CeO2. Comparative Example 5 Preparation of 1.0 wt.%W / 1.0 wt.%Ru-CeO2 catalyst: 0.93 g of the Ru-CeO2 catalyst prepared in Comparative Example 3 and 0.013 g of ammonium tungstate were dissolved in 0.32 g of deionized water. After stirring for 30 minutes, the mixture was allowed to stand at room temperature for 6 hours, then dried at 80 °C for 16 hours, and finally calcined in air at 450 °C for 3 hours to obtain the desired catalyst product, denoted as 1.0 wt.%W / 1.0 wt.%Ru-CeO2. Comparative Example 6 The catalyst in Comparative Example 1 was calcined in air at 700 °C for 2 hours, and the resulting catalyst was denoted as CP-1.0 wt.%Ru-1.0 wt.%W-CeO2-HT. Comparative Example 7 The catalysts prepared in Comparative Examples 3 to 5 were calcined in air at 700 °C for 2 hours, and the resulting catalysts were denoted as 1.0 wt.%Ru-CeO2-HT, 1.0 wt.%Ru / 1.0 wt.%W-CeO2-HT, and 1.0 wt.%W / 1.0 wt.%Ru-CeO2-HT, respectively. Example 1 Preparation of 1.0 wt.%Ru-1.0 wt.%W-CeO2 catalyst: 4.76 g of cerium acetate, 0.038 g of ammonium tungstate, and 0.27 g of ruthenium nitrite (9.51 wt.%) were dissolved in 160 mL of a mixed solvent consisting of glacial acetic acid and 2-ethylhexyl in a volume ratio of 1:1. The solution was stirred in a water bath at 60 °C for 5 hours to obtain a Ce concentration of 0.1 mol·L⁻¹. -1 The precursor solution was injected into the burner via a syringe at a constant flow rate of 2.5 mL / min. Atomization was performed with the assistance of oxygen (partial pressure 150 kPa) as the dispersion gas, and combustion was carried out in a flame maintained at a hydrogen flow rate of 3.3 L / min and an air flow rate of 16.7 L / min. The product was quenched and collected through a glass fiber filter membrane. The collected powder was calcined at 400 °C for 2 hours in air to obtain the desired catalyst product, denoted as 1.0 wt.%Ru-1.0 wt.%W-CeO2. Example 2 The flow rates of the precursor solution were varied to 1.0 mL / min, 2.5 mL / min, 5.0 mL / min, 10.0 mL / min, and 15 mL / min, with the rest remaining the same as in Example 1. The resulting catalyst was denoted as x-1.0 wt.%Ru-1.0 wt.%W-CeO2 (where x = 1.0, 2.5, 5.0, 10.0, and 15.0). Example 3 The loading of Ru was changed to 0.3 wt.%, 0.5 wt.%, 0.8 wt.%, 1.0 wt.% and 1.5 wt.%, respectively, with the rest being the same as in Example 1. The resulting catalyst was denoted as yRu-1.0 wt.%W-CeO2 (where y = 0.3, 0.5, 0.8, 1.0, 1.5 wt.%). Example 4 The loading of W was varied to 1.0 wt.%, 2.0 wt.%, 3.0 wt.%, 4.0 wt.%, 5.0 wt.%, 6.0 wt.%, 7.0 wt.%, 8.0 wt.%, and 9.0 wt.%, with the remainder the same as in Example 1. The resulting catalyst was denoted as 1.0 wt.%Ru-zW-CeO2 (where z = 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0 wt.%). Example 5 The catalyst from Example 1 was calcined in air at 700 °C for 2 hours, and the resulting catalyst was denoted as 1.0 wt.%Ru-1.0 wt.%W-CeO2-HT. (I) Evaluation of catalytic activity 1.1 Catalytic Combustion Activity of Vinyl Chloride (VC) The evaluation conditions for the catalytic combustion performance of vinyl chloride (VC) were as follows: 0.12 g of the catalysts prepared in Examples 1-5 and Comparative Examples 1-7 were placed in a quartz tube fixed-bed reactor, with air as the oxidant, at a vinyl chloride (VC) concentration of 1000 ppm and a reaction space velocity of 30000 mL·g. -1 ·h -1 The catalytic combustion reaction of vinyl chloride (VC) was carried out under certain conditions, and the reaction tail gas was detected by capillary gas chromatography. Figure 1 The effect of preparation method on catalyst activity was investigated. Results showed that, compared with the conventional co-precipitation method, the catalyst prepared by flame spray pyrolysis exhibited significant advantages and better catalytic activity in the catalytic combustion of vinyl chloride (VC). Figure 2 The effect of preparation method on the high-temperature stability of the catalyst was investigated. The results showed that, compared with the CP-Ru-W-CeO2 catalyst prepared by co-precipitation method, the Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis method exhibits both excellent low-temperature activity and outstanding thermal stability in the catalytic combustion of vinyl chloride (VC). Figure 3 The effect of precursor solution flow rate on the catalytic activity of the catalyst was investigated. The results showed that the catalyst activity remained essentially unchanged when the precursor solution flow rate increased from 1.0 mL / min to 2.5 mL / min. Further increasing the precursor solution flow rate significantly reduced the catalytic activity. A feed flow rate of 2.5 mL / min can maintain high catalyst activity while also ensuring efficient preparation. Figure 4 The XRD patterns of Ru-W-CeO2 catalysts prepared at different precursor liquid flow rates are shown. The results indicate that when Ru-W-CeO2 catalysts are prepared in one step using flame spray pyrolysis, the grain size of the CeO2 support significantly increases with increasing precursor liquid flow rate. Specifically, when the precursor liquid flow rate is controlled at 2.5 mL / min, the CeO2 grain size of the obtained catalyst is only 5.4 nm. This ultrafine grain structure helps to improve the oxygen activity of the catalyst, enabling it to exhibit excellent catalytic activity in catalytic combustion reactions. Figure 5 The effect of Ru content on the catalytic activity of Ru-W-CeO2 catalysts was investigated. The results showed that the activity order of catalysts with different Ru contents for the catalytic combustion of vinyl chloride was 1.5 wt.%Ru ≈ 1.0 wt.%Ru > 0.8 wt.%Ru > 0.5 wt.%Ru > 0.3 wt.%Ru. Among them, the Ru-W-CeO2 catalyst with a Ru content of 1.0 wt.% exhibited both high activity and a relatively low amount of precious metal. Figure 6The effect of W content on the catalytic activity of the Ru-W-CeO2 catalyst was investigated. The results showed that the introduction of only 1.0 wt.% W could significantly improve the low-temperature activity of the catalyst. Figure 7 The effect of the introduction order of W species on the catalytic combustion performance of vinyl chloride (VC) was investigated. The results showed that the introduction order of W species significantly affected the activity and thermal stability of the catalyst in the catalytic combustion reaction of VC. Among them, the Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis exhibited excellent low-temperature activity and high-temperature stability, achieving 90% VC conversion at a relatively low temperature (226 °C) even after aging at 700 °C. Figure 9 The results show the cycling test results of the Ru-W-CeO2 catalyst. The results indicate that as the number of catalytic combustion reactions of vinyl chloride increases, the activity curves of the catalyst almost overlap, demonstrating that the catalyst possesses excellent cycling stability. 1.2 Catalytic Combustion Activity of Dichloroethane (DCE) The evaluation conditions for the catalytic combustion performance of dichloroethane (DCE) were as follows: 0.12 g of the catalysts prepared in Examples 1, 5, and Comparative Examples 3-5 were placed in a quartz tube fixed-bed reactor, respectively, with air as the oxidant, at a dichloroethane (DCE) concentration of 1000 ppm and a reaction space velocity of 30000 mL·g. -1 ·h -1 The dichloroethane (DCE) catalytic combustion reaction was carried out under certain conditions, and the reaction tail gas was detected by capillary gas chromatography. Figure 8 The effect of the introduction sequence of W species on the catalytic combustion performance of dichloroethane (DCE) was investigated. The results showed that the Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis exhibited the best activity in the catalytic combustion of DCE, achieving 90% conversion of DCE at 289 °C. More importantly, after aging at 700 °C, the catalyst maintained excellent DCE catalytic activity, still achieving 90% conversion of DCE at a relatively low temperature (296 °C). (II) Evaluation of thermal shock resistance (in-situ atmosphere) 0.12 g of the Ru-W-CeO2 catalyst prepared in Example 1 was placed in a quartz tube fixed-bed reactor, with air as the oxidant, a vinyl chloride concentration of 1000 ppm, and a reaction space velocity of 30000 mL·g. -1 ·h -1 The specific testing procedure is as follows: the catalyst is first rapidly heated to 300 ℃ and kept at that temperature for 12 hours, then rapidly heated to 500 ℃ and kept at that temperature for 12 hours, and finally cooled to 300 ℃ and kept at that temperature for 12 hours. Figure 10 The results show the thermal shock resistance of the Ru-W-CeO2 catalyst in a vinyl chloride (VC) atmosphere. The results indicate that the Ru-W-CeO2 catalyst, prepared in one step via flame spray pyrolysis, exhibits excellent thermal shock resistance. After undergoing the aforementioned 36-hour test involving both high and low temperature shocks, the vinyl chloride (VC) conversion remained at 100%, and the concentration of polychlorinated byproducts was 0 ppm. (III) Evaluation of water resistance performance 3.1 Water-based activity Add 5 vol.% H2O to the reaction atmosphere to investigate the effect of water introduction on catalyst activity. The rest of the process is the same as performance evaluation (I). Figure 11 The results show the water-addition activity test results of the Ru-W-CeO2 catalyst. The results indicate that the introduction of 5 vol.% H2O did not cause any change in the catalytic combustion activity of vinyl chloride (VC), and the two curves basically overlapped, indicating that the catalyst has excellent water resistance. 3.2 In-situ water resistance stability 0.12 g of the catalysts prepared in Examples 1 and 5 were respectively placed in quartz tube fixed-bed reactors, with air as the oxidant, vinyl chloride concentration of 1000 ppm, and reaction space velocity of 30000 mL·g. -1 ·h -1 and their respective T 90 Under the reaction temperature conditions, a drying-wetting (5 vol.% H2O)-drying cycle test was conducted for 1160 minutes. Figure 12 The results show the water stability test results of Ru-W-CeO2 and Ru-W-CeO2-HT catalysts. The results indicate that the fresh Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis and the Ru-W-CeO2-HT catalyst aged at high temperature did not undergo deactivation throughout the test, confirming that the catalyst has excellent water stability. In summary, the synthesis strategy of Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis in this invention exhibits significant structural advantages. This strategy successfully constructs an ultrafine CeO2 grain structure, significantly increasing the surface active site exposure density and enhancing its intrinsic oxygen activity, resulting in excellent low-temperature activity, cycle stability, and water resistance in the catalytic combustion of chlorinated volatile organic compounds (CVOCs). Simultaneously, this strategy overcomes the limitations of traditional processes, achieving highly uniform doping of Ru and W species within the CeO2 lattice. This unique microstructural advantage allows the catalyst to maintain its stable microstructure even under thermal shock conditions such as bed runaway. Therefore, the catalyst of this invention possesses both excellent low-temperature activity and outstanding high-temperature stability, breaking the technical bottleneck of the incompatibility between these two properties in traditional acid-modified catalysts, and has broad application prospects.

Claims

1. A Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis, characterized in that, The catalyst comprises the following components and their weight percentage content (based on the weight of CeO2 support): Ru: 0.3%~1.5%, W：1.0%~9.0%。。 2. A Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to claim 1, characterized in that, Includes the following steps: Ruthenium, tungsten, and cerium precursors were dissolved in a mixed solvent of glacial acetic acid and 2-ethylhexanoic acid and stirred in a water bath at 50–70 °C for 3–6 hours to prepare a precursor solution with a Ce concentration of 0.05–0.5 mol / L. The precursor solution was then injected into a burner via a syringe at a constant flow rate of 1.0–15.0 ml / min and atomized with the assistance of oxygen (partial pressure 100–180 kPa) as the dispersion gas. Combustion was carried out in a flame maintained at a hydrogen flow rate of 3.0–4.0 L / min and an air flow rate of 15–17 L / min. The product was quenched and collected through a glass fiber filter membrane. The collected powder was calcined in air at 300–450 °C for 2–4 hours to obtain the catalyst product.

3. The Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to claim 2, characterized in that, The ruthenium precursors include ruthenium chloride, ruthenium nitrite, or ruthenium acetylacetone.

4. The Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to claim 2, characterized in that, The tungsten precursors include tungsten hexachloride or ammonium tungstate.

5. The Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to claim 2, characterized in that, The cerium precursors mentioned include cerium acetate or cerium nitrate.

6. The Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to claim 2, characterized in that, The volume ratio of glacial acetic acid to 2-ethylhexanoic acid is 1:2, 1:1, or 2:

1.

7. The application of the Ru-W-CeO2 catalyst prepared in one step by flame spray pyrolysis according to any one of claims 1-6, characterized in that, The catalyst is used for the catalytic combustion of chlorinated volatile organic compounds (CVOCs), wherein the chlorinated volatile organic compounds are vinyl chloride (VC) or dichloroethane (DCE).

8. The application according to claim 7, characterized in that, The reaction conditions for the catalytic combustion are as follows: when applied to the catalytic combustion of vinyl chloride (VC), the concentration of vinyl chloride (VC) is 1000 ppm, and the reaction space velocity is 30,000 mL·g. -1 ·h -1 When applied to the catalytic combustion of dichloroethane (DCE), the concentration of DCE is 1000 ppm and the reaction space velocity is 30,000 mL·g. -1 ·h -1 .

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