Ru-Zr / CePO4 catalyst for inhibiting polychlorinated by-products as well as preparation method and application of Ru-Zr / CePO4 catalyst

Abstract

The invention belongs to the technical field of environmental catalytic materials, and particularly discloses a Ru-Zr / CePO4 catalyst for inhibiting polychlorinated by-products as well as a preparation method and application of the Ru-Zr / CePO4 catalyst. The catalyst comprises a CePO4 carrier and an active component loaded on the surface of the CePO4 carrier; the active component comprises a Zr species and a Ru species; the catalyst has a multi-phase interface structure, and comprises a Ru0 / CePO4 interface, a RuOx / CePOO interface, a ZrOx / CePO4 interface and a RuOx-ZrOx / CePO4 interface. An acid-base pair of CePO4 and a ZrOx / CePO4 interface promote dichloroethane adsorption dechlorination and rapid removal of HCl; the electron-rich Ru species and the RuOx-ZrOx interface enhance lattice oxygen migration and water activation, and the vinyl chloride intermediate is subjected to rapid low-temperature oxidation hydrolysis. Multi-interface cooperation blocks Cl2 circulation from the source and inhibits polychlorinated by-products. The T90 of the catalyst reaches 260 DEG C at 260 DEG C, the CO2 selectivity is close to a theoretical value, and the catalyst has excellent water resistance, chlorine poisoning resistance and long-term stability and is wide in application prospect.

Description

Technical Field

[0001] This invention relates to the field of environmental catalytic materials technology, specifically to a Ru-Zr / CePO4 catalyst for suppressing polychlorinated byproducts, its preparation method, and its application. Background Technology

[0002] Chlorinated volatile organic compounds (CVOCs), such as 1,2-dichloroethane and vinyl chloride, are typical toxic and harmful air pollutants, characterized by high toxicity, strong chemical stability, and potential carcinogenicity. They are widely used as industrial solvents, cleaning agents, and chemical intermediates, leading to serious environmental pollution problems. Among numerous treatment technologies, catalytic oxidation is considered one of the most promising technologies for CVOC removal due to its advantages such as low operating temperature, low energy consumption, and minimal secondary pollution. The core of this approach lies in developing high-performance catalysts.

[0003] Currently, catalysts used for the catalytic oxidation of CVOCs mainly include transition metal oxides and molecular sieves. Transition metal oxides with redox activity (such as CeO2, Co3O4, and MnO2) possess strong oxygen activation capabilities and high lattice oxygen mobility, promoting the deep oxidation of CVOCs. However, the Lewis acid sites and oxygen vacancies of these catalysts readily adsorb chlorine species during the reaction, leading to chlorine poisoning / deactivation. Furthermore, their high redox activity exacerbates the Deacon reaction, generating large amounts of Cl2. This Cl2 can act as a chlorinating agent, reacting with reaction intermediates (such as VC) at surface M–Cl or M–OCl sites through electrophilic addition or substitution reactions, thereby generating more toxic polychlorinated byproducts and causing secondary pollution.

[0004] On the other hand, acidic transition metal oxides (such as WO3) x MoO x VO x Although H-type zeolites possess abundant strong Lewis acid and Brønsted acid sites, which can effectively catalyze the dehydrochlorination of DCE to produce HCl and VC, thereby alleviating chlorine poisoning, their inherent weak redox properties severely hinder the deep oxidation of dechlorination intermediates such as VC, leading to the accumulation of these harmful intermediates in the reaction system and limiting their practical application.

[0005] Cerium phosphate, as a novel catalytic material, possesses a unique "acid-base pair" structure on its surface, composed of Ce... 3+ Lewis acid sites and PO4 3- Composition of nucleophilic basic sites. Ce 3+ The sites are responsible for adsorbing CVOC molecules and breaking C–Cl bonds, while PO4 3-The group promotes the desorption of HCl, effectively alleviating surface chlorine accumulation and poisoning. Meanwhile, CePO4 has a stable crystal structure with strong P–O bonds, maintaining structural integrity even under high temperature, chlorine-rich, and water vapor conditions, thus exhibiting long-lasting catalytic durability. However, similar to acidic oxides, CePO4's relatively weak redox ability limits its efficiency in deep oxidation of reaction intermediates (especially the dehydrochlorination product VC).

[0006] Therefore, how to construct a catalyst with both high efficiency in dechlorination and excellent deep oxidation activity based on CePO4 material, and fundamentally inhibit the generation of toxic byproducts, has become a key technical problem that urgently needs to be solved in the field of CVOCs catalytic purification. Summary of the Invention

[0007] To address the technical problem that existing catalysts cannot fundamentally suppress the formation of toxic byproducts, this invention provides a Ru-Zr / CePO4 catalyst for suppressing polychlorinated byproducts, its preparation method, and its application. The catalyst comprises a CePO4 support and an active component supported on the surface of the CePO4 support; the active component comprises Zr species and / or Ru species; the catalyst has a multiphase interface structure, including Ru... 0 / CePO4 interface, RuO x / CePO4 interface, ZrO x / CePO4 interface and RuO x -ZrO x / CePO4 interface, where x ≤ 2.

[0008] Furthermore, based on the mass of the CePO4 vector, the mass fraction of the Zr species is 5-20 wt% (preferably 15 wt%).

[0009] Furthermore, based on the mass of the CePO4 vector, the mass fraction of the Ru species is 0.5~2 wt% (preferably 1 wt%).

[0010] Furthermore, the CePO4 support has a hexagonal crystal structure; the Zr species are in the form of amorphous ZrO. x The Ru species are dispersed monolayer in the form of nanoclusters on the surface of the CePO4 support; the Ru species are partially expressed as single-crystal Ru with exposed {001} crystal planes. 0 It exists in the form of nanoclusters, partially doped with the amorphous ZrO. x A Ru-O-Zr bridging structure is formed in the matrix of nanoclusters.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned Ru-Zr / CePO4 composite catalyst, which employs a stepwise sequential impregnation method, specifically including the following steps: (1) Preparation of CePO4 support: The co-precipitation method is used to mix the aqueous solution of cerium source and the aqueous solution of phosphorus source, and after stirring, aging, washing and drying, the mixture is calcined in air at 350~600℃ for 2~4 hours to obtain CePO4 support; the cerium source is selected from at least one of cerium nitrate, cerium chloride or cerium sulfate, preferably cerium nitrate hexahydrate; the phosphorus source is selected from at least one of ammonium phosphate, sodium phosphate or diammonium hydrogen phosphate, preferably ammonium phosphate; the stirring time is 0.2~2 hours, the aging time is 10~24 hours; the washing is performed by alternating washing with deionized water and anhydrous ethanol 3~5 times; the drying temperature is 60~120℃, and the drying time is 10~15 hours; (2) Preparation of Zr / CePO4 precursor: The CePO4 support obtained in step (1) was impregnated in an aqueous solution containing a zirconium source using an equal-volume impregnation method. After drying at 60-100°C for 10-15 hours, it was calcined in air at 350-550°C for 2-4 hours to obtain the Zr / CePO4 precursor. The zirconium source was selected from at least one of zirconium oxynitrate, zirconium nitrate, or zirconium chloride, preferably zirconium oxynitrate. The Zr loading was 5-20 wt% based on the mass of the CePO4 support, preferably 15 wt%. (3) Preparation of Ru-Zr / CePO4 composite catalyst: The Zr / CePO4 precursor obtained in step (2) is impregnated in an aqueous solution containing a ruthenium source by an equal volume impregnation method. After drying at 60~100℃ for 10~15 hours, it is calcined in air at 350~550℃ for 2~4 hours to obtain the Ru-Zr / CePO4 composite catalyst. The ruthenium source is selected from at least one of ruthenium trichloride, ruthenium nitrate or ruthenium acetylacetonate, preferably ruthenium trichloride. The loading of Ru is 0.5~2wt% based on the mass of CePO4 support, preferably 1wt%.

[0012] Further, the stirring time in step (1) is preferably 0.5 hours, and the aging time is preferably 15 hours; the drying temperature in steps (1) to (3) is preferably 80°C, and the drying time is preferably 12 hours; the calcination temperature is preferably 450°C, and the calcination time is preferably 2 hours.

[0013] A third aspect of the present invention provides an application of the above-mentioned Ru-Zr / CePO4 composite catalyst in the catalytic combustion of chlorine-containing volatile organic compounds.

[0014] Furthermore, the chlorine-containing volatile organic compound is 1,2-dichloroethane.

[0015] Furthermore, the application includes suppressing the formation of vinyl chloride and polychlorinated byproducts during catalytic combustion.

[0016] Furthermore, the catalyst maintains excellent catalytic activity and stability even under harsh conditions such as aqueous atmospheres.

[0017] Compared with the prior art, the present invention has the following significant advantages: 1. This invention successfully constructed Ru on the surface of a CePO4 support using a stepwise equal-volume impregnation method. 0 / CePO4 interface, RuO x / CePO4 interface, ZrO x / CePO4 interface and RuO x -ZrO x / CePO4 and other multi-phase collaborative interfaces. This unique interface structure enables precise functional division of labor: ZrO x The / CePO4 interface is responsible for the initial activation and rapid dechlorination of DCE, RuO x The / CePO4 interface is responsible for the low-temperature deep oxidation of intermediates, Ru 0 The / CePO4 interface is responsible for the activation of oxygen molecules, RuO x -ZrO x The / CePO4 interface enhances lattice oxygen migration through a Ru-O-Zr bridging structure.

[0018] The catalyst of this invention exhibits excellent low-temperature catalytic activity (T 90 With a temperature of 260℃ and extremely high CO2 selectivity, it can completely inhibit the formation of highly toxic intermediate vinyl chloride (VC) and polychlorinated byproducts (such as TCA and PCE), solving the technical problem of secondary pollution caused by traditional catalysts.

[0019] The catalyst of this invention has excellent water resistance and stability. It not only does not deactivate under 3 vol% water vapor and long-term dry-wet alternation cycle, but the conversion rate even increases slightly, showing excellent performance recoverability and adaptability. It is suitable for complex industrial waste gas treatment conditions.

[0020] This invention, by precisely controlling the Ru loading (1 wt%) and Zr loading (15 wt%), ensures excellent redox performance while avoiding the generation of Cl2 due to the violent Deacon reaction caused by excessive Ru content, thus completely cutting off the formation pathway of polychlorinated byproducts.

[0021] The preparation method of the present invention is simple, controllable, and reproducible, and the catalyst obtained has extremely high potential for industrial application. Attached Figure Description

[0022] Figure 1 Activity plots and concentration-temperature curves of intermediate products for 1% Ru-x%Zr / CePO4 (x=5,10,15,20) catalysts.

[0023] Figure 2 Activity curves and concentration-temperature profiles of intermediate products for x% Ru-15% Zr / CePO4 catalysts (x=0.5, 0.75, 1, 2).

[0024] Figure 3 The activity curve of the 1%Ru-15%Zr / CePO4-CI catalyst obtained by the distribution impregnation method and the concentration-temperature curve of vinyl chloride (VC) are shown.

[0025] Figure 4 The activity and concentration-temperature curves of CePO4, 1%Ru / CePO4, 15%Zr / CePO4 and the optimal catalyst 1%Ru-15%Zr / CePO4 in this invention are shown.

[0026] Figure 5 The activity of CePO4, 1%Ru / CePO4, 15%Zr / CePO4 and the optimal catalyst 1Ru-15Zr / CePO4 and the concentration-temperature curves of VC were obtained under 3 vol% water vapor conditions.

[0027] Figure 6 The thermal / hydrothermal stability diagrams for CePO4, 1%Ru / CePO4, 15%Zr / CePO4, and the optimal catalyst 1%Ru-15%Zr / CePO4 of the present invention are shown.

[0028] Figure 7 The X-ray diffraction patterns of CePO4, 1%Ru / CePO4, 15%Zr / CePO4, and the optimal catalyst 1%Ru-15%Zr / CePO4 are shown in this paper.

[0029] Figure 8 The Raman spectra of CePO4, 1%Ru / CePO4, 15%Zr / CePO4 and the optimal catalyst 1%Ru-15%Zr / CePO4 are shown in this invention.

[0030] Figure 9 This is a high-angle annular dark-field scanning transmission electron microscope image of the optimal catalyst in Example 1 of the present invention, along with the corresponding elemental distribution map.

[0031] Figure 10 The X-ray photoelectron spectra of CePO4, 1%Ru / CePO4, 15%Zr / CePO4, and the optimal catalyst 1%Ru-15%Zr / CePO4 are for this invention.

[0032] Figure 11 This is the X-ray absorption spectrum of the optimal catalyst in Example 1 of the present invention.

[0033] Figure 12 Temperature-programmed reduction (H2-TPR) and oxygen desorption (O2-TPD) experiments were conducted for CePO4, 1%Ru / CePO4, 15%Zr / CePO4, and the optimal catalyst 1%Ru-15%Zr / CePO4, according to the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods described are conventional methods, and the reagents described are all available from publicly available commercial sources. I. Catalyst Preparation

[0035] The present invention discloses a multiphase interface synergistic Ru-Zr / CePO4 composite catalyst, the preparation process of which mainly includes the synthesis of CePO4 support and the stepwise loading of Zr and Ru species.

[0036] Parameter protection range description: Based on the carrier mass, the loading of active metal Ru is 0.5~2 wt% (preferably 1.0 wt%); the loading of auxiliary agent Zr is 5~20 wt% (preferably 15.0 wt%). The cerium source can be selected from soluble cerium salts such as cerium nitrate, cerium chloride, or cerium sulfate; the zirconium source can be selected from zirconium oxynitrate, zirconium nitrate, or zirconium chloride; the ruthenium source can be selected from ruthenium trichloride, ruthenium nitrate, or ruthenium acetylacetonate. Detailed description is provided below through specific examples.

[0037] Example 1: Preparation of a preferred composite catalyst (1% Ru–15% Zr / CePO4) (sequential impregnation method)

[0038] (1) Preparation of pure-phase CePO4 support: Accurately weigh 1.39 g of cerium nitrate (Ce(NO3)3·6H2O), dissolve it in 200 mL of deionized water, and stir magnetically until completely dissolved to obtain a colorless and transparent solution. Separately weigh 1.5 g of ammonium phosphate ((NH4)3PO4), dissolve it in 200 mL of deionized water. Under continuous stirring, slowly add the ammonium phosphate solution to the cerium nitrate solution, and a white precipitate will immediately form. Continue stirring vigorously for 0.2~2 h (preferably 0.5 h in this example), and then age it at room temperature for 10~24 h (preferably 15 h in this example). Discard the supernatant, centrifuge to collect the white precipitate, and wash it alternately with deionized water and anhydrous ethanol 3~5 times each. The washed precursor was dried in an oven at 60~120 ℃ (preferably 80 ℃ in this embodiment) for 10~15 h, ground into powder, and then calcined in a muffle furnace in static air at 350~600 ℃ (preferably 450 ℃ in this embodiment) for 2~4 h (preferably 2 h in this embodiment) to obtain a well-crystallized hexagonal CePO4 support.

[0039] (2) Preparation of 15% Zr / CePO4 intermediate: Accurately weigh 0.5 g of the CePO4 support obtained in step (1). Based on the preferred loading of 15 wt% (as a percentage of the mass of Zr element to the mass of the support), calculate and weigh the corresponding mass of the precursor zirconium oxynitrate (ZrO(NO3)2·2H2O, about 0.22 g), add an appropriate amount (about 0.4 mL, based on the pore volume of the support) of deionized water to fully dissolve it, and obtain an impregnation solution. The solution is uniformly loaded onto the CePO4 support using the equal volume impregnation method, and then dried at 60~100℃ (preferably 80 ℃) for 10~15 h (preferably 12 h) and calcined at 350~550 ℃ (preferably 450 ℃) for 2~4 h (preferably 2 h) to obtain the 15% Zr / CePO4 intermediate.

[0040] (3) Preparation of 1% Ru–15% Zr / CePO4 composite catalyst: Based on the mass of 0.5 g CePO4 support prepared in step (1), according to the preferred loading of 1 wt% (based on the mass of Ru elemental), weigh the corresponding mass of ruthenium trichloride (RuCl3·3H2O, about 0.0129 g) and add an appropriate amount (about 0.5 mL) of deionized water to fully dissolve it. Using the equal volume impregnation method, the ruthenium impregnation solution is added dropwise to all the 15% Zr / CePO4 intermediates obtained in step (2), and the mixture is gently stirred to ensure uniform wetting. Finally, the catalyst is dried at 60~100 ℃ (preferably 80 ℃) for 10~15 h (preferably 12 h) and calcined in static air at 350~550 ℃ (preferably 450 ℃) for 2~4 h (preferably 2 h) to obtain a composite catalyst with a multiphase synergistic interface, denoted as 1% Ru–15% Zr / CePO4.

[0041] Example 2: Preparation of 1% Ru–x% Zr / CePO4 catalysts with different Zr loadings (sequential impregnation method) To systematically study the effect of Zr loading on the performance of composite catalysts, the proportion of Zr in the support was adjusted in this embodiment. Specifically, the other steps in Example 1 were kept unchanged, except that the Zr loading in step (2) was adjusted to 5%, 10%, 15%, and 20%, respectively. The corresponding required mass of the precursor zirconium oxynitrate (ZrO(NO3)2·2H2O) was 0.073 g, 0.147 g, 0.220 g, and 0.293 g, respectively. The resulting series of catalysts were named 1% Ru–x% Zr / CePO4, where x represents 5, 10, 15, and 20, respectively.

[0042] Example 3: Preparation of Zr / CePO4 catalysts with different Ru loadings (x%) and Ru–15% (sequential impregnation method) Based on the screening results of Example 2, 15 wt% was determined to be the optimal Zr loading. To further investigate the effect of Ru species loading on the performance of the composite catalyst, this example loaded different contents of Ru onto the optimized 15% Zr / CePO4 support. Specifically, referring to step (3) of Example 1, only the Ru loading was changed, successively adjusted to 0.5%, 0.75%, 1.5%, and 2%, while the remaining preparation steps remained unchanged. The corresponding required precursor ruthenium trichloride (RuCl3·3H2O) masses were 0.0065 g, 0.0098 g, 0.0129 g, and 0.0259 g, respectively. The final catalyst was denoted as x% Ru–15% Zr / CePO4, where x was 0.5, 0.75, 1.5, and 2, respectively.

[0043] Comparative Example 1: Preparation of 1% Ru–15% Zr / CePO4-CI catalyst (co-impregnation method) To investigate the effect of impregnation order on catalyst performance, a comparative sample was prepared using a co-impregnation method. 0.5 g of the pure-phase CePO4 support prepared in Example 1 was accurately weighed. Based on the loading of 1 wt% Ru and 15 wt% Zr, 0.0129 g of ruthenium trichloride trihydrate and 0.22 g of zirconium oxynitrate dihydrate were weighed as precursors. Both were placed together in a container, and approximately 0.4 mL of deionized water (estimated based on the pore volume of the support) was added. The mixture was stirred until completely dissolved to obtain a mixed impregnation solution. This mixed impregnation solution was slowly and uniformly added dropwise to the CePO4 support in one go, and the container was gently shaken to ensure thorough wetting of the support. The mixture was then allowed to stand at room temperature for 2 h, and then transferred to an 80 ℃ oven for drying for 12 h. Finally, it was calcined at 450 ℃ in air for 2 h, and after natural cooling, the co-impregnated comparative catalyst was obtained, denoted as 1% Ru–15% Zr / CePO4-CI.

[0044] Comparative Example 2: Preparation of 1% Ru / CePO4 catalyst (Zr-free) Weigh 0.5 g of the CePO4 support obtained in Example 1. Using ruthenium trichloride trihydrate as a precursor, accurately weigh 0.0129 g of the precursor based on a 1 wt% Ru loading, and dissolve it completely in approximately 0.4 mL of deionized water to prepare an impregnation solution. Using the initial wet impregnation method, uniformly dropwise add the impregnation solution onto the CePO4 support and allow it to age at room temperature for 2 h. Subsequently, dry the sample at 80 ℃ for 12 h, and then calcine it at 450 ℃ for 2 h to obtain a zirconium-free comparative catalyst, 1% Ru / CePO4.

[0045] Comparative Example 3: Preparation of 1% Ru / ZrO2 catalyst (conventional support) First, a ZrO2 support was prepared: approximately 2.0 g of zirconium oxynitrate dihydrate was weighed and placed in a crucible. The crucible was heated to 500 °C at a rate of 5 °C / min under static air and calcined for 4 h. After cooling, the mixture was ground to obtain ZrO2 powder. Next, Ru was loaded: 0.5 g of the above ZrO2 support was weighed, and 0.0129 g of ruthenium trichloride trihydrate was accurately weighed according to a Ru loading of 1 wt%. Approximately 0.5 mL of deionized water was added to dissolve the ruthenium trihydrate, preparing an impregnation solution. This solution was added dropwise to the ZrO2 support and stirred to wet it. The solution was then dried at 80 °C for 12 h, and finally calcined in static air at a rate of 5 °C / min to 450 °C for 2 h to obtain a conventional support compared to a 1% Ru / ZrO2 catalyst. II. Structural Characterization and Catalytic Performance Evaluation of Catalysts

[0046] The catalytic oxidation performance of this invention was tested in a continuous flow fixed-bed quartz reactor. 200 mg (40–60 mesh) of catalyst from each example and comparative sample was accurately weighed and placed in the center of the reactor. The conventional reaction gas composition was: 1000 mg·m⁻³ 1,2-dichloroethane (DCE), 20 vol% O₂, with N₂ as the equilibrium gas, a total flow rate of 100 mL·min⁻¹, and a corresponding weight hourly space velocity (WHSV) of 30,000 mL·g⁻¹·h⁻¹. The reaction tail gas was analyzed using online gas chromatography to calculate the DCE conversion rate (expressed as T). 90 The concentrations of various chlorinated byproducts, including vinyl chloride (VC), dichloroethylene, trichloroethylene (TCE), trichloroethane (TCA), and tetrachloroethylene (PCE), were measured at the temperature at which the conversion rate reached 90%. To evaluate the catalyst's stability under actual operating conditions, hydrothermal stability tests (introducing 3.0 vol% steam) and wet-dry cycle tests (periodic switching between steam introduction and shutdown) were also conducted.

[0047] To reveal the source of the superior performance of the catalyst of the present invention, the most preferred Example 1 (1% Ru–15% Zr / CePO4 catalyst) was systematically characterized and compared with various comparative sample samples. The characterization results and catalytic performance evaluation results are as follows: Figure 1The catalytic performance of a series of catalysts (1% Ru–5% Zr / CePO4, 1% Ru–10% Zr / CePO4, 1% Ru–15% Zr / CePO4, and 1% Ru–20% Zr / CePO4) prepared with different Zr loadings (5%, 10%, 15%, and 20%) in Example 2 was investigated. The results showed that when the Zr loading was 15%, the catalyst exhibited the best DCE conversion activity and the lowest VC byproduct formation. x The species formed an ideal monolayer dispersion structure on the CePO4 surface.

[0048] Figure 2 The catalytic performance of a series of catalysts (0.5% Ru–15% Zr / CePO4, 0.75% Ru–15% Zr / CePO4, 1% Ru–15% Zr / CePO4, 1.5% Ru–15% Zr / CePO4, and 2% Ru–15% Zr / CePO4) prepared with different Ru loadings (0.5%, 0.75%, 1%, 1.5%, and 2%) in Example 3 was investigated. The results showed that when the Ru loading was 1%, the catalyst exhibited both excellent oxidation activity and the ability to suppress polychlorinated byproducts; excessively high Ru loading (e.g., 2%) triggered a violent Deacon reaction, leading to a surge in tetrachlorinated byproducts such as PCE.

[0049] Figure 3 The performance of the 1% Ru–15% Zr / CePO4 catalysts prepared by Example 1 (sequential impregnation method) and Comparative Example 1 (co-impregnation method) was compared. The results showed that the catalyst prepared by the sequential impregnation method was significantly superior to that prepared by the co-impregnation method in terms of DCE conversion, CO2 selectivity, and VC inhibition ability, confirming the key role of sequential impregnation in constructing an efficient synergistic interface structure.

[0050] Figure 4 This paper presents a comparison of the activities of the preferred embodiment 1 (1% Ru–15% Zr / CePO4), Comparative Example 2 (1% Ru / CePO4), Comparative Example 3 (1% Ru / ZrO2), and a pure CePO4 support with a 15% Zr / CePO4 intermediate. The catalyst of Example 1 exhibits excellent low-temperature catalytic activity (T0). 90 =260 ℃), significantly better than CePO4 (T 90 =344 ℃), 15% Zr / CePO4 (T 90 =271 ℃), Comparative Example 2 (T 90=312 °C) and comparative samples such as Comparative Example 3. Meanwhile, the catalyst of Example 1 showed excellent inhibition ability against highly toxic intermediate VC and polychlorinated byproducts (such as TCA and PCE), with VC almost completely eliminated and TCA / PCE concentrations below 0.5 ppm.

[0051] Figure 5 The effect of 3 vol% water vapor on the performance of catalysts in Example 1 (1% Ru–15% Zr / CePO4), Comparative Example 2 (1% Ru / CePO4), and Comparative Example 3 (1% Ru / ZrO2) was investigated. The results showed that the catalyst in Example 1 maintained excellent catalytic activity and by-product suppression ability under a water-containing atmosphere, exhibiting superior water stability, which was significantly better than that of the comparative samples.

[0052] Figure 6 The stability test results of the catalyst of this invention are presented. Among them, Figure 6 (ad) is in T 90 The DCE conversion and VC concentration of CePO4, 1% Ru / CePO4, 15% Zr / CePO4, and the optimal catalyst 1% Ru–15% Zr / CePO4 were compared with the operating time at the specified temperature. The results showed that the performance of pure CePO4 gradually decreased, while the VC production increased. The DCE conversion of 15% Zr / CePO4 decreased after 3 h, while the VC concentration increased. The Ru-containing catalysts (1% Ru / CePO4 and 1% Ru–15% Zr / CePO4) exhibited stable or even increased activity over time. The optimal catalyst, 1% Ru–15% Zr / CePO4, maintained a stable DCE conversion and a consistently low VC concentration within 18 h, demonstrating excellent long-term operational stability. Figure 6(eh) represents the results of a cyclical wet-dry test with periodic steam introduction and shutdown (reaction conditions: 250 ppm DCE + 20 vol% O2 + 3 vol% H2O, N2 as the equilibrium gas). During the three "H2O introduction" stages (3-6 h, 9-12 h, 16-18 h) and the "H2O shutdown" stage in between, pure CePO4 showed a decrease in DCE conversion during the water introduction stage and an increase in VC during the drying stage. 15% Zr / CePO4 recovered its baseline activity after cycling, but the initial wet-dry conversion process led to increased VC formation. 1% Ru / CePO4 showed decreased activity in the later water introduction stages, but exhibited lower VC formation in the subsequent drying stages. The optimal catalyst, 1% Ru–15% Zr / CePO4, maintained almost constant activity across the three water introduction stages, with a higher DCE conversion rate than the initial level and a continuously decreasing VC concentration in the subsequent drying stages, demonstrating excellent performance recoverability and adaptability. Comparative Example 2 (1% Ru / CePO4) and Comparative Example 3 (1% Ru / ZrO2) both showed varying degrees of performance degradation in the wet-dry cycle test, further highlighting the excellent water resistance and chlorine poisoning resistance of the catalyst of the present invention under the synergistic effect of multiphase interface.

[0053] Figure 7 XRD patterns showed that the CePO4 support of the catalyst in Example 1 maintained a complete hexagonal crystal structure. No obvious characteristic diffraction peaks of ZrO2 or RuO2 were detected after loading Zr and Ru, indicating that ZrO2... x Both the Ru species exist in a highly dispersed state.

[0054] Figure 8 Raman spectroscopy showed that the introduction of Zr in the catalyst of Example 1 enhanced the intensity of characteristic peaks related to oxygen vacancies on the CePO4 surface, and the loading of Ru caused the shift and broadening of specific Raman peaks, which is attributed to the formation of a unique Ru-O-Zr interface structure.

[0055] Figure 9 The image shows a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image and corresponding elemental distribution of the optimal catalyst in Example 1. The STEM image reveals a complex composite structure, with a well-crystallized hexagonal CePO4 support. The interplanar spacings are 0.611 nm, 0.445 nm, and 0.306 nm, corresponding to the (100), (101), and (200) crystal planes, respectively. Three different morphologies of active species can be observed on the CePO4 support surface: one is a large amorphous region, attributed to monolayer dispersed ZrO. x Species; secondly, the clearly visible metallic Ru 0Nanoclusters (particle size approximately 1-3 nm) with a lattice fringe spacing of 0.215 nm, corresponding to metallic Ru 0 The (002) crystal plane confirms that it exposes the {001} crystal plane; thirdly, in ZrO x RuO with a lattice spacing of 0.224 nm was identified in the vicinity of the region. x Nanoclusters, corresponding to the (200) crystal plane of RuO2, indicate the formation of RuO2. x -ZrO x Interface. Furthermore, amorphous ZrO x Local bright spots within the region suggest that Ru may be incorporated into ZrO. x The matrix indicates the presence of Ru-O-Zr bonds. Elemental surface scan analysis shows that Ce, O, P, and Zr are uniformly distributed, while Ru exhibits local enrichment (corresponding to Ru / RuO). x Nanoclusters) and widely dispersed (possibly atomically dispersed species or doped with ZrO) x The dual distribution pattern of Ru in ZrO2. The above results confirm that this invention successfully constructed ZrO2. x / CePO4、Ru 0 / CePO4、RuO x / CePO4 and RuO x -ZrO x Multiphase heterogeneous interfaces such as / CePO4 are intertwined and closely adjacent, forming the microstructural basis for the synergistic effect of catalysts.

[0056] Figure 10 XPS analysis revealed electronic effects on the surface of the catalyst in Example 1. Compared with Comparative Example 2 (1% Ru / CePO4) and Comparative Example 3 (1% Ru / ZrO2), the Ce 3d, P 2p, Zr 3d, and Ru 3p core energy levels of the catalyst in Example 1 all showed systematic shifts, confirming strong interfacial electronic effects. Electrons transferred from the CePO4 support to the Ru and Zr species, resulting in Ru exhibiting a mixed valence state (Ru... 0 With Ru 4 (⁺ / Ru³⁺), and significantly increased the ratio of adsorbed oxygen species and oxygen vacancies on the surface.

[0057] Figure 11 XAS at the atomic scale confirmed that the coordination environment of Ru in the catalyst of Example 1 was mainly Ru-O, accompanied by weak Ru-Ru scattering, confirming that Ru mainly exists in the oxidized state (RuO). x It exists in the form of Ru-O-Zr bridging, unlike in Comparative Example 3 where Ru mainly exists as Ru. 0 Or a coordination structure in which RuO2 crystal phase exists.

[0058] Figure 12The H2-TPR and O2-TPD results showed that the catalyst of Example 1 exhibited excellent low-temperature reduction ability and high-mobility lattice oxygen supply ability. Its reduction peak and oxygen desorption peak both shifted significantly to the low-temperature region, and the peak area was significantly larger than that of Comparative Example 2 and Comparative Example 3, indicating that the constructed multiphase interface significantly improved the redox cycle efficiency of the catalyst.

[0059] III. Structure-Property Relationship Analysis and Advantages of the Invention Based on the above structural characterization and catalytic performance evaluation results, the superior performance of the catalyst of this invention can be attributed to the following multiphase interface synergistic mechanism: based on Figure 1 and Figure 9 As a result, when the Zr loading is 15% (the optimal ratio in Example 2), ZrO x The species can form an ideal monolayer dispersion on the CePO4 surface, resulting in highly active ZrO. x / CePO4 interface (responsible for initial activation of DCE and rapid dechlorination to generate VC intermediate) and RuO x The / CePO4 interface (responsible for low-temperature deep oxidation) is spatially highly proximate to the DCE in ZrO. x After site-specific dechlorination to generate VC, the adjacent highly dispersed RuO x Clusters can utilize their highly mobile lattice oxygen ( Figure 12 (Confirmed by O2-TPD) immediately and completely oxidizes VC in situ, preventing VC from desorbing from the surface and achieving a highly efficient relay of "dechlorination-oxidation". Comparative Example 2 (1% Ru / CePO4), however, lacks ZrO. x The interface, after VC is generated, cannot be quickly captured and oxidized, resulting in a large amount of VC overflow.

[0060] based on Figure 2 As a result, this invention precisely controls the Ru loading at approximately 1 wt% (the optimal ratio in Example 3). This loading ensures both the ability of Ru species to activate molecular oxygen and avoids the violent Deacon reaction (HCl + O2 → Cl2 + H2O) caused by excessive Ru content (e.g., 2%). Excessive Cl2 directly leads to a surge in tetrachloro byproducts such as PCE. Figure 2 (f) In contrast, Comparative Example 3 (1% Ru / ZrO2) was prone to chlorine poisoning and polychlorinated byproduct formation even at a 1% Ru loading due to the lack of acid-base regulation from the CePO4 support. Therefore, the appropriate Ru loading and the synergistic effect of the CePO4 support completely interrupted the Cl2 cycle that leads to the formation of polychlorinated byproducts.

[0061] based on Figure 3 As a result, the sequential impregnation method (Example 1) can construct RuO more effectively than the co-impregnation method (Comparative Example 1).x -ZrO x The / CePO4 multiphase synergistic interface confirms the criticality of the preparation sequence in achieving the technical effects of this invention. In the co-impregnation method, the Ru and Zr precursors compete with each other during impregnation, making it impossible to form an ideal Ru anchorage to ZrO. x The interface structure above leads to a weakening of the synergistic effect.

[0062] based on Figure 5 and Figure 6 As a result, the catalyst in Example 1 not only remained undeactivated under 3 vol% water vapor and long-term wet-dry cycling, but its conversion rate even slightly increased, demonstrating excellent water resistance. Analysis suggests that the water vapor cycling induced the highly dispersed RuO2. x -ZrO x Beneficial interface reconstruction, in-situ generation of highly active RuO x The cluster achieved continuous regeneration of active sites by promoting a moderate Deacon reaction, thus maintaining perfect inhibition of toxic byproducts even under harsh humid conditions. In contrast, Comparative Examples 2 and 3 showed varying degrees of activity decrease and byproduct increase under aqueous conditions.

[0063] based on Figures 7 to 12 Structural characterization results, XRD ( Figure 7 This confirmed the presence of highly dispersed active species in the catalyst of Example 1; Raman ( Figure 8 ) and XPS ( Figure 10 This revealed oxygen vacancies and interfacial electronic effects, which were most significant in Example 1; STEM ( Figure 9 The XAS (X-ray Amplifier) ​​visually demonstrates the multiphase interface structure of the catalyst in Example 1; Figure 11 The atomic coordination environment of Ru-O-Zr was confirmed, which is a key structural feature that distinguishes the catalyst of Example 1 from the comparative example; H2-TPR and O2-TPD ( Figure 12 This confirms the excellent redox performance of the catalyst in Example 1, which is significantly better than that of Comparative Examples 2 and 3. These structural features collectively constitute the physicochemical basis for the excellent catalytic performance of the catalyst of the present invention.

[0064] In summary, this invention successfully constructed a multiphase synergistic interface on the CePO4 surface by optimizing preparation parameters (especially the sequential impregnation and the ratio of 1% Ru to 15% Zr). This catalyst completely solves the technical bottlenecks of traditional transition metal catalysts, which are prone to producing highly toxic polychlorinated byproducts and are susceptible to water / chlorine poisoning. Its overall performance is significantly better than that of conventional comparative catalysts (such as the 1% Ru / ZrO2 in Comparative Example 3), and it has extremely high potential for industrial application.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A Ru-Zr / CePO4 catalyst for suppressing polychlorinated byproducts, characterized in that, The catalyst comprises a CePO4 support and an active component supported on the surface of the CePO4 support; the active component comprises Zr species and / or Ru species; the catalyst has a multiphase interface structure, including Ru 0 / CePO4 interface, RuO x / CePO4 interface, ZrO x / CePO4 interface and RuO x -ZrO x / CePO4 interface.

2. The Ru-Zr / CePO4 catalyst according to claim 1, characterized in that, Based on the mass of the CePO4 vector, the Zr species has a mass fraction of 5-20 wt%, and the Ru species has a mass fraction of 0.5-2 wt%.

3. The Ru-Zr / CePO4 catalyst according to claim 2, characterized in that, The Zr species has a mass fraction of 15 wt%, and the Ru species has a mass fraction of 1 wt%.

4. The Ru-Zr / CePO4 catalyst according to claim 1, characterized in that, The CePO4 support has a hexagonal crystal structure; the Zr species are in the form of amorphous ZrO. x The Ru species are dispersed monolayer in the form of nanoclusters on the surface of a CePO4 support; the Ru species are partially expressed as single-crystal Ru with exposed {001} crystal planes. 0 It exists in the form of nanoclusters, partially doped with the amorphous ZrO. x A Ru-O-Zr bridging structure is formed in the matrix of nanoclusters.

5. A method for preparing the Ru-Zr / CePO4 catalyst according to any one of claims 1-4, characterized in that, The preparation method employs a stepwise sequential impregnation process, specifically including the following steps: (1) Preparation of CePO4 support: The cerium salt aqueous solution and the phosphate aqueous solution were mixed by coprecipitation method, and CePO4 support was obtained after stirring, aging, washing, drying and calcination. (2) Preparation of Zr / CePO4 precursor: The CePO4 support obtained in step (1) was impregnated in a zirconium-containing precursor solution by the equal volume impregnation method, and after drying and calcination, the Zr / CePO4 precursor was obtained. (3) Preparation of Ru-Zr / CePO4 composite catalyst: The Zr / CePO4 precursor obtained in step (2) was impregnated in a ruthenium-containing precursor solution by equal volume impregnation method, and after drying and calcination, the Ru-Zr / CePO4 composite catalyst was obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the cerium salt is cerium nitrate hexahydrate, the phosphate is ammonium phosphate; the stirring time is 0.2~2 h, the aging time is 10~24 h; the drying temperature is 60~120 ℃, and the calcination conditions are calcination at 350~600 ℃ in static air for 2~4 h.

7. The preparation method according to claim 5, characterized in that, In step (2), the zirconium-containing precursor solution is an aqueous solution of zirconium oxynitrate; the Zr loading is 5~20 wt% based on the mass of the CePO4 support; the drying temperature is 60~100℃ and the drying time is 10~15 h; the calcination conditions are calcination at 350~550℃ for 2~4 h in static air.

8. The preparation method according to claim 5, characterized in that, In step (3), the ruthenium-containing precursor solution is an aqueous solution of ruthenium trichloride; the Ru loading is 0.5~2 wt% based on the mass of the CePO4 support; the drying temperature is 60~100 ℃ and the drying time is 10~15 h; the calcination conditions are calcination at 350~550 ℃ for 2~4 h in static air.

9. The application of the Ru-Zr / CePO4 catalyst as described in any one of claims 1-4 in the catalytic combustion of chlorine-containing volatile organic compounds.

10. The application according to claim 9, characterized in that, The chlorine-containing volatile organic compound is 1,2-dichloroethane; the catalyst utilizes CePO4 and ZrO during the catalytic oxidation of 1,2-dichloroethane. x The acid-base sites at the / CePO4 interface promote the adsorption and dehydrochlorination of 1,2-dichloroethane, and utilize the RuO x -ZrO x The / CePO4 interface rapidly captures, hydrolyzes, and oxidizes vinyl chloride intermediates generated during dechlorination, thereby inhibiting the formation of vinyl chloride and polychlorinated byproducts.

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