A single-atom ruthenium supported bimetallic oxide approach and its application in catalytic oxidation of chlorinated vocs (cvocs)

Abstract

This invention discloses a scheme for a single-atom ruthenium-supported bimetallic oxide and its application in the catalytic oxidation of chlorine-containing VOCs (CVOCs), relating to the field of chemical catalyst synthesis and application technology. The catalyst is Ru / zNbyMnO. x The Mn and Nb bimetallic oxide was synthesized by co-precipitation. The doping of metallic Nb improves the acidity of the catalyst, enhancing its adsorption of CVOCs and desorption of Cl-containing species. Furthermore, Nb incorporates into MnO. x Within the crystal lattice, altering the local coordination environment of Mn-O induces MnO x Lattice distortion occurs, forming Mn-O-Nb covalent bonds and a discontinuous solid solution, resulting in a large number of highly coordinated unsaturated oxygen vacancies exposed on the surface. At the same time, the polarized Mn-O bonds are prone to oxygen exchange, easily breaking and recombinizing. After Ru is loaded, Ru can easily connect to the bridging oxygen to form Ru-O-Mn bridging bonds, allowing Ru to exist in a stable single-atom form. This enhances the metal-support interaction between Ru and the support, thereby improving the catalytic oxidation ability of trichloroethylene.

Description

Technical Field

[0001] This invention relates to the field of chemical catalyst synthesis and application technology, specifically to a scheme for a single-atom ruthenium-supported bimetallic oxide and its application in the catalytic oxidation of chlorine-containing VOCs (CVOCs). Background Technology

[0002] Among VOCs, chlorinated volatile organic compounds (CVOCs) are of particular concern. This is mainly due to the widespread use of chlorinated chemicals in modern industrial production, which, limited by current technological levels, results in the emission of large amounts of CVOCs in the production chain. Compared to other pollutants, CVOCs are characterized by stronger chemical stability, higher toxicity, and greater difficulty in biodegradation. For these pollutants (represented by trichloroethylene TCE), catalytic oxidation methods, with highly efficient catalysts at their core, are widely recognized as promising end-of-pipe treatment methods due to their significant advantages such as low operating temperature, low energy consumption, high removal efficiency, and no secondary pollution.

[0003] The design and development of catalysts are key to this technological breakthrough. Currently, single-atom catalysts (SACs) have become a research hotspot in this field due to their excellent catalytic activity; among them, ruthenium (Ru)-based catalysts stand out for their unique redox properties, excellent resistance to chlorine poisoning, and low-temperature catalytic activity. Ru species can rapidly convert adsorbed chlorine species into Cl2 throughout the Deacon process, effectively preventing chlorine poisoning and enhancing selectivity. Currently, SACs exhibit outstanding performance in many catalytic reactions due to their extremely high atom utilization efficiency and catalytic performance. By strengthening the interaction between the metal and the support, monodisperse and stable anchoring of Ru atoms can be achieved, thus reaching atomic-level dispersion. However, how to achieve the controllable synthesis of noble metal single-atom catalysts remains a challenge that urgently needs to be solved. Summary of the Invention

[0004] This invention provides a method for preparing a single-atom noble metal Ru catalyst and its application in the catalytic oxidation of chlorinated volatile organic compounds (CVOCs), solving a key problem in the catalytic oxidation of CVOCs. The invention provides an Nb-doped Mn-based material (zNbyMnOx) as a support for the CVOC catalyst, and then loads Ru ions onto zNbyMnOx in single-atom form via an impregnation method. x A single-atom catalyst, Ru / zNbyMnOx, is formed on the support. This is in contrast to Mn-based materials without Nb doping (MnO). x When loaded with the same mass fraction of Ru species, Ru exists in the form of RuO2 nanoparticles.

[0005] The difference in the speciation of Ru species in the two catalysts significantly affected their catalytic oxidation activity and stability for CVOCs. Using TCE as the target pollutant, short-time heating activity tests were used to evaluate their performance. The results showed that Ru / zNbyMnyO exists in the form of single Ru atoms. z Its catalytic performance is better than that of Ru / MnO x Highly dispersed Ru species not only provide more catalytic active sites, significantly improving the catalytic oxidation activity of TCE, but also increase the number of acid sites on the catalyst surface, thereby effectively promoting the dissociation, desorption, and deep mineralization of TCE.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a catalyst for the catalytic oxidation reaction of CVOCs (trichloroethylene), the catalyst comprising: a bimetallic oxide zNbyMnO x and bimetallic oxides Ru / zNbyMnO x The catalyst was prepared by a co-precipitation method, including the following steps: (1) Bimetallic oxide zNbyMnO x Method: S1: Weigh different masses of ammonium niobate oxalate hydrate (C4H4NNbO9·xH2O) and manganese nitrate solution (Mn(NO3)2, 50wt%) and disperse them in 150 mL of deionized water, stirring and dispersing for 1 h; S2: Ammonia water (NH3·H2O, 25 wt%) is dissolved in water and added dropwise to the solution obtained in step (1). The solution is stirred until pH=9-10 and then left to stand for 3 h. S3: Filter, wash, and dry the suspension after the above reaction overnight, then calcine it in a muffle furnace for 3 hours to obtain the desired support zNbyMnO. x .

[0007] (2) Bimetallic oxide Ru / zNbyMnO x Method: A1: The prepared support zNbyMnO x Disperse the mixture in deionized water and stir for 1 hour. A2: Add RuCl3 solution to the above suspension and stir for 2 h; A3: Filter, wash, and dry the suspension after the above reaction overnight, then calcine in a muffle furnace for 3 h to obtain the bimetallic oxide Ru / zNbyMnO. x .

[0008] Preferably, the zNbyMnO x In the catalyst: z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:100.

[0009] Preferably, in step S1, the ammonium niobate oxalate hydrate is 3.636 g, 0.727 g, 0.363 g, 0.242 g, and 0.182 g, corresponding to 21.474 g of manganese nitrate solution; 3.63 6g of ammonium oxalate hydrate yielded Nb5MnO x ; 0.727 g of ammonium oxalate hydrate yielded Nb25MnO. x ; 0.363 g of ammonium niobate oxalate hydrate yielded Nb50MnO x ; 0.242 g of ammonium niobate oxalate hydrate yielded Nb75MnO x ; 0.182 g of ammonium niobate oxalate hydrate yielded Nb100MnO x .

[0010] Preferably, in step S2, the amount of ammonia is 15 mL and the amount of water is 30 mL.

[0011] Preferably, the drying temperature in step S3 is 80 ℃ and the calcination temperature in the muffle furnace is 500 ℃.

[0012] Preferably, 0.5 g of zNbyMnO is used in step A1. x Disperse in 50 mL of deionized water.

[0013] Preferably, the RuCl3 solution in step A2 has a mass fraction of 0.5 wt%-3 wt%.

[0014] Preferably, the drying temperature in step A3 is 80 ℃, and the calcination temperature in the muffle furnace is 350 ℃.

[0015] This invention also provides a catalyst prepared according to the method, wherein the catalyst is zNbyMnO. x Where z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:100; The catalyst is Ru / zNbyMnO x Where z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:100.

[0016] Finally, this invention provides an application of a catalyst, using a bimetallic oxide support zNbyMnO. x Ruthenium-supported bimetallic oxide Ru / zNbyMnO xApplication in the catalytic oxidation of CVOCs (trichloroethylene).

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The Mn and Nb bimetallic oxide synthesized by coprecipitation method has the following effects: the doping of metal Nb increases the acidity of the catalyst, thereby enhancing the adsorption of CVOCs and the desorption of Cl-containing species; on the other hand, Nb enters MnO x Within the crystal lattice, altering the local coordination environment of Mn-O induces MnO x Lattice distortion occurs, forming Mn-O-Nb covalent bonds and a discontinuous solid solution, resulting in a large number of highly coordinated unsaturated oxygen vacancies exposed on the surface. At the same time, the polarized Mn-O bonds are prone to oxygen exchange, easily breaking and recombinizing. After Ru is loaded, Ru can easily connect to the bridging oxygen to form Ru-O-Mn bridging bonds, allowing Ru to exist in a stable single-atom form. This enhances the metal-support interaction (SMSI) between Ru and the support, thereby improving the catalyst's ability to catalyze the oxidation of trichloroethylene. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope.

[0019] Figure 1 These are the X-ray diffraction (XRD) patterns of the catalysts synthesized in Examples 1, 2, 4 and 5 of this invention. Figure 2 These are high-magnification transmission electron microscope (TEM) images of the catalysts synthesized in Examples 4 and 5 of this invention. Figure 3 These are aberration-corrected high-angle annular dark-field scanning transmission microscope (AC-HAADF-STEM) images of the catalyst synthesized in Example 4 of this invention; Figure 4 These are XPS spectra of the catalysts synthesized in Examples 1, 2, 4 and 5 of this invention, wherein (a) is the O 1s spectrum and (b) is the Ru spectrum; Figure 5 These are the trichloroethylene conversion and CO2 mineralization curves of the catalysts synthesized in Examples 1, 2, 3, 4, 5 and 6 of this invention, wherein the initial concentration of trichloroethylene is 1000 ppm and the space velocity is 18000 mL / (gh). Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0021] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the embodiments.

[0023] A bimetallic oxide catalyst zNbyMnO x The catalyst is zNbyMnO x Where z and y represent the molar ratio of Mn to Nb, ranging from 1:5 to 1:100. The precursors of Nb and Mn are dissolved in water to form a homogeneous solution. Ammonia is added dropwise to the mixed solution, allowing it to precipitate, stand, filter, wash, dry, and calcine to obtain a composite bimetallic oxide.

[0024] A ruthenium-supported bimetallic oxide catalyst Ru / zNbyMnO x The catalyst is Ru / zNbyMnO x Where z and y represent the molar ratio of Mn to Nb, ranging from 1:5 to 1:100. The mass fraction of the noble metal Ru is 0.5 wt% to 3 wt%. RuCl3 is added to zNbyMnO in solution form. x In the dispersed solution, Ru 3+ It binds to Mn-O bonds in the form of single atoms to form Ru-O-Mn bonds, thus loading zNbyMnO x surface.

[0025] Preparation of bimetallic oxides zNbyMnO by coprecipitation method x Using ammonium niobate oxalate hydrate (C4H4NNbO9·xH2O) and manganese nitrate aqueous solution (Mn(NO3)2, 50wt%) as precursors for Mn and Nb respectively, the structure of the Mn / Nb bimetallic oxide was optimized by adjusting the ratio of Mn to Nb in the catalyst. Nb gradually entered the MnOx lattice, thereby altering the local coordination environment of Mn-O and inducing MnO... xLattice distortion occurs, forming Mn-O-Nb covalent bonds and creating a discontinuous solid solution, resulting in a large number of highly coordinated unsaturated oxygen vacancies being exposed on the surface.

[0026] Preparation of bimetallic oxides zNbyMnO by coprecipitation method x Ammonium niobate oxalate hydrate (C4H4NNbO9·xH2O) and manganese nitrate aqueous solution (Mn(NO3)2, 50wt%) were used as precursors for Mn and Nb, respectively. By adjusting the ratio of Mn to Nb in the catalyst, Nb gradually entered MnO. x Within the crystal lattice, this alters the local coordination environment of Mn-O, inducing MnO x Lattice distortion occurs, forming Mn-O-Nb covalent bonds and a discontinuous solid solution, resulting in a large number of highly coordinated unsaturated oxygen vacancies exposed on the surface. At the same time, the polarized Mn-O bonds are prone to oxygen exchange, easily breaking and recombinizing. After Ru is loaded, Ru can easily connect to the bridging oxygen to form Ru-O-Mn bridging bonds, allowing Ru to exist in a stable single-atom form and enhancing the metal-support interaction (SMSI) between Ru and the support.

[0027] (1) First, take different masses of ammonium oxalate hydrate (C4H4NNbO9·xH2O, purchased from Shanghai Dibai Biotechnology Co., Ltd.) (3.636 g, 0.727 g, 0.363 g, 0.242 g, 0.182 g) and mix with 150 mL of deionized water. Stir vigorously for 30 min, then add 21.474 g of manganese nitrate solution (Mn(NO3)2, 50 wt%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and stir until a homogeneous solution is formed. Add ammonia water (NH3·H2O, 25 wt%, purchased from Tianjin Tianli Chemical Reagent Co., Ltd.) to adjust the pH to 9-10, continue stirring for 3 h, let stand for 3 h, filter the precipitate and wash repeatedly until neutral, put it in an 80℃ forced-air oven to dry overnight, then put it in a muffle furnace and heat to 500℃ (heating rate of 5℃ / min) and hold for 3 h. Finally, the obtained solid powder is recorded as zNbyMnO x .

[0028] The preferred option is Nb5MnO. x The amount of ammonium niobate oxalate hydrate added was 0.0012 mol (3.636 g), and the amount of manganese nitrate solution added was 0.06 mol (21.47 mL).

[0029] (2) Mix 0.06 mol (21.474 g) of manganese nitrate solution (Mn(NO3)2, 50 wt%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) with 150 mL of deionized water, stir for 30 min, add ammonia water (NH3·H2O, 25%, purchased from Tianjin Tianli Chemical Reagent Co., Ltd.) to adjust the pH to 9-10, continue stirring for 3 h, let stand for 3 h, filter the precipitate and wash repeatedly until neutral, put it in an 80 ℃ forced-air oven to dry overnight, then put it in a muffle furnace and heat it to 500 ℃ (heating rate of 5 ℃ / min) and keep it for 3 h. Finally, the obtained solid powder is recorded as MnO. x .

[0030] (3) The solid powder Nb5MnO synthesized in step (1) x Take 0.5 g, disperse it in 50 mL of deionized water, stir for 1 h, add 5.14 mL (2 mg / mL) of prepared ruthenium chloride solution (RuCl3), soak and stir for 2 h, filter the precipitate and wash it, put it in a forced-air drying oven at 80 ℃ overnight, calcine it in a muffle furnace at 350 ℃ for 3 h (heating rate of 3.5 ℃ / min), and finally record the obtained solid powder as Ru / Nb5MnO x .

[0031] (4) The solid powder MnO synthesized in step (2) x Take 0.5 g, disperse it in 50 mL of deionized water, stir for 1 h, add 5.14 mL (2 mg / mL) of prepared ruthenium chloride (RuCl3) solution, soak and stir for 2 h, filter the precipitate and wash it, place it in a forced-air drying oven at 80 ℃ overnight, calcine it in a muffle furnace at 350 ℃ for 3 h (heating rate of 3.5 ℃ / min), and finally record the obtained solid powder as Ru / MnO. x . Example 1:

[0032] Preparation of Nb5MnO xCarrier: First, 0.012 mol (3.636 g) ammonium oxalate hydrate (purchased from Shanghai Dibai Biotechnology Co., Ltd.) was mixed with 150 mL of deionized water and stirred vigorously for 30 min. Then, 0.06 mol (21.474 g) manganese nitrate solution (50% aqueous solution, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) was added and stirred until a homogeneous solution was formed. Ammonia water (25%, purchased from Tianjin Tianli Chemical Reagent Co., Ltd.) was added to adjust the pH to 9-10. Stirring was continued for 3 h, and the mixture was allowed to stand for 3 h. The precipitate was filtered and repeatedly washed until neutral. It was then dried overnight in an 80 ℃ oven. Finally, it was heated in a muffle furnace to 500 ℃ (heating rate of 5 ℃ / min) and held for 3 h. The resulting solid powder was designated as Nb5MnO. x Example 2:

[0033] Preparation of Mn Ox Carrier: 0.06 mol (21.474 g) of manganese nitrate solution (50% aqueous solution, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 150 mL of deionized water were mixed and stirred for 30 min. Ammonia water (25%, purchased from Tianjin Tianli Chemical Reagent Co., Ltd.) was added to adjust the pH to 9-10. Stirring was continued for 3 h, and the mixture was allowed to stand for 3 h. The precipitate was filtered and repeatedly washed until neutral. It was then dried overnight in an 80 ℃ oven. The precipitate was then heated to 500 ℃ (heating rate of 5 ℃ / min) in a muffle furnace and held for 3 h. The resulting solid powder was designated as MnO. x . Example 3:

[0034] Preparation of NbO x Carrier: 0.012 mol (3.636 g) of ammonium oxalate hydrate (purchased from Shanghai Dibai Biotechnology Co., Ltd.) was mixed with 150 mL of deionized water and stirred for 30 min. Ammonia water (25%, purchased from Tianjin Tianli Chemical Reagent Co., Ltd.) was added to adjust the pH to 9-10, and stirring was continued for 3 h. After standing for 3 h, the precipitate was filtered and repeatedly washed until neutral. It was then dried overnight in an 80 ℃ oven. Finally, it was heated to 500 ℃ (heating rate of 5 ℃ / min) in a muffle furnace and held for 3 h. The resulting solid powder was designated as NbO. x . Example 4:

[0035] Preparation of Ru / Nb5MnO x Catalyst: The solid powder Nb5MnO synthesized in step (1) xTake 0.5 g, disperse it in 50 mL of deionized water, stir for 1 h, add 5.14 mL (2 mg / mL) of prepared ruthenium chloride solution, soak and stir for 2 h, filter the precipitate and wash it, put it in a forced-air drying oven at 80 ℃ overnight, calcine it in a muffle furnace at 350 ℃ for 3 h (heating rate of 3.5 ℃ / min), and finally record the obtained solid powder as Ru / Nb5MnO x . Example 5:

[0036] Preparation of Ru / MnO x Catalyst: The solid powder MnO synthesized in step (2) x Take 0.5 g, disperse it in 50 mL of deionized water, stir for 1 h, add 5.14 mL (2 mg / mL) of prepared ruthenium chloride solution, soak and stir for 2 h, filter the precipitate and wash it, put it in a forced-air drying oven at 80 ℃ overnight, calcine it in a muffle furnace at 350 ℃ for 3 h (heating rate of 3.5 ℃ / min), and finally record the obtained solid powder as Ru / MnO. x . Example 6:

[0037] Preparation of Ru / NbO x Catalyst: The solid NbO powder synthesized in step (2) x Take 0.5 g, disperse it in 50 mL of deionized water, stir for 1 h, add 5.14 mL (2 mg / mL) of prepared ruthenium chloride solution, soak and stir for 2 h, filter the precipitate and wash it, put it in a forced-air drying oven at 80 ℃ overnight, calcine it in a muffle furnace at 350 ℃ for 3 h (heating rate of 3.5 ℃ / min), and finally denote the obtained solid powder as Ru / NbO. x . Example 7:

[0038] The activity and stability of the catalyst were assessed using a fixed-bed reactor connected to a gas chromatograph equipped with two FID detectors and a nickel conversion furnace. 200 mg of sample (40-60 mesh) was placed in an 8 mm inner diameter quartz tube, and the catalyst was stabilized before and after using quartz sand and quartz wool. The gas flowed from the top to the bottom of the quartz tube, and the temperature of the catalyst bed was measured by thermocouples inserted into the quartz tube from the top. Trichloroethylene gas was obtained by the volatilization of liquid trichloroethylene, with the volatilization rate regulated by a cooling circulation system. The concentration and space velocity of trichloroethylene were adjusted by the air flow rate. The initial trichloroethylene concentration was 1000 ppm, the total flow rate was 62 mL / min, and the space velocity was 18000 mL / (gh). The trichloroethylene concentration was measured using an FID detector, and CO2 was detected using an FID detector in conjunction with the nickel conversion furnace.

[0039] Figure 1 These are the XRD patterns of the catalysts synthesized in Examples 1, 2, 4, and 5. The figures show that the crystal structures of the four materials are consistent with Mn₂O₃. Compared to pure MnO₂… x Catalyst, Nb5MnO x and Ru / Nb5MnO x MnO x The weakening of the diffraction peak intensity indicates that Nb doping weakens the MnO. x Lattice distortion occurred, forming a Nb5MnOx solid solution. x The support exhibits a distinct Nb₂O₅ characteristic diffraction peak at 2θ = 36.17°. This peak disappears after Ru loading, indicating that the introduction of Ru triggers the MnO₂ diffraction. x The crystal reconstruction of the matrix, mediated by oxygen vacancies, not only formed a Ru-O-Mn structure but also promoted the redispersion of the residual Nb₂O₅ phase, thus achieving phase reorganization of the catalyst. Furthermore, the Ru / MnO₂... x The absence of diffraction peaks for RuO2 is likely due to the high dispersion of Ru species.

[0040] Figure 2 The Ru / Nb5MnOx and Ru / MnO prepared in Examples 4 and 5 x High-magnification transmission electron microscopy (HR-TEM) images of the catalyst; from Figure 2 (a)-(e) show that Ru / Nb5MnO x and Ru / MnO x It exhibits an irregular sheet-like structure, Ru / Nb5MnO x The grain size should be smaller than that of Ru / MnO. x This indicates that the addition of Nb weakens the Mn-O bond, which is consistent with the XRD results; Furthermore, in Ru / Nb5MnO x No RuO2 phase was observed on the catalyst surface, while the MnO phase was not. x Nanoscale Ru species could be observed on the surface, indicating that the addition of Nb promoted Ru dispersion; from Figure 2 (e) The RuO2 (111) and (222) crystal planes can be seen, indicating that Ru / MnO x The Ru species on the catalyst surface is RuO2.

[0041] Figure 3 This is an aberration-corrected high-angle annular dark-field scanning transmission microscope (AC-HAADF-STEM) image of the catalyst synthesized in Example 4. The image shows that Ru is uniformly anchored in Nb5MnO in an atomically dispersed state. x The surface evidence confirms that Nb doping facilitates the single-atom dispersion of Ru.

[0042] Figure 4 (a) is the XPS spectrum of the O 1s orbitals of the catalysts synthesized in Examples 1, 2, 4 and 5. The peak located at 529.6-530.0 eV is the characteristic peak of lattice oxygen (denoted as O). α） The peak located at 530.5-531.3 eV represents chemisorbed oxygen (denoted as O). β） The peak located at 533.0-534.0 eV belongs to surface-adsorbed O2 or oxygen-containing groups (denoted as O). γ） Multiple studies have shown that adsorbed oxygen has high mobility and is deeply involved in the redox cycle of pollutants, and the content of adsorbed oxygen on the catalyst surface is closely related to the concentration of oxygen vacancies on the catalyst surface. As can be seen from the figure, compared to MnO... x Nb5MnO x The chemical adsorption of oxygen is significantly increased, and the content of adsorbed oxygen on the catalyst surface is closely related to the concentration of oxygen vacancies on the catalyst surface. After Nb doping, Nb enters MnO x The internal structure of the crystal lattice promotes the migration of lattice oxygen, creating more oxygen vacancies and promoting the formation of chemisorbed oxygen. Figure 4 (b) is the catalyst Ru 3d synthesized in Examples 4 and 5. 5 / 2 The XPS plot of the orbital shows peaks centered at 281.6 and 280.5 eV, representing Ru, respectively. 4+ and Ru 0 We can see Ru / Nb5MnO x Ru on the surface exists Ru 4+ and Ru 0 , while Ru / MnO x Only Ru exists 4+ The characteristic peaks indicate that the addition of Nb promotes the reaction between Ru and Nb5MnO. x Electron transfer between carriers allows Ru species to gain more electrons and exist with a zero valence.

[0043] Figure 5 These are the trichloroethylene conversion and CO2 mineralization rate curves for the catalysts synthesized in Examples 1, 2, 3, 4, 5, and 6. The graphs show that MnO... x NbO x Nb5MnO x The support exhibits poor activity; after loading 1 wt% Ru species, the resulting catalyst, Ru / MnO, shows poor performance. x Ru / NbO x and Ru / Nb5MnO x The conversion rate of trichloroethylene and the CO2 mineralization rate were both improved, indicating that Ru species are the active sites of the catalyst; in addition, NbO xThe near-absence of activity indicates that Nb doping only alters the structure and physicochemical properties of the original support; similar to MnO... x In comparison, Nb5MnO x T 90 The temperature dropped by 30°C, which is due to the Nb doping in MnO. x Lattice distortion occurred, resulting in more defects and oxygen vacancies; after Ru loading, Ru / Nb5MnO x T 90 Compared to Ru / MnOx, the temperature was reduced by 22℃. These results indicate that Nb doping only alters the MnO content. x The structure and physicochemical properties of the support make it easier to capture Ru atoms, thereby forming atomically dispersed noble metal supported catalysts, which can increase the number of active sites and catalyst activity.

[0044] The embodiments described above are merely preferred embodiments of the present invention, and not an exhaustive list of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a catalyst for the catalytic oxidation reaction of CVOCs (trichloroethylene), characterized in that, The catalyst includes: bimetallic oxides zNbyMnO x and bimetallic oxides Ru / zNbyMnO x The catalyst was prepared by a co-precipitation method, including the following steps: (1) Bimetallic oxide zNbyMnO x Method: S1: Weigh different masses of ammonium niobate oxalate hydrate (C4H4NNbO9·xH2O) and manganese nitrate solution (Mn(NO3)2, 50wt%) and disperse them in 150 mL of deionized water, stirring and dispersing for 1 h; S2: Ammonia water (NH3·H2O, 25 wt%) is dissolved in water and added dropwise to the solution obtained in step (1). The solution is stirred until pH=9-10 and then left to stand for 3 h. S3: Filter, wash, and dry the suspension after the above reaction overnight, then calcine it in a muffle furnace for 3 hours to obtain the desired support zNbyMnO. x . (2) Bimetallic oxide Ru / zNbyMnO x Method: A1: The prepared support zNbyMnO x Disperse the mixture in deionized water and stir for 1 hour. A2: Add RuCl3 solution to the above suspension and stir for 2 h; A3: Filter, wash, and dry the suspension after the above reaction overnight, then calcine in a muffle furnace for 3 h to obtain the bimetallic oxide Ru / zNbyMnO. x .

2. The preparation method according to claim 1, characterized in that, The zNbyMnO x In the catalyst: z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:

100.

3. The method according to claim 1, characterized in that, In step S1, the ammonium niobate oxalate hydrate is 3.636 g, 0.727 g, 0.363 g, 0.242 g, and 0.182 g, corresponding to 21.474 g of manganese nitrate solution; (1) 3.63 6g of ammonium niobate oxalate hydrate yields Nb5MnO x ; (2) 0.727 g of ammonium niobate oxalate hydrate yielded Nb25MnO x ; (3) 0.363 g of ammonium niobate oxalate hydrate yielded Nb50MnO x ; (4) 0.242 g of ammonium niobate oxalate hydrate yielded Nb75MnO x ; (5) 0.182 g of ammonium niobate oxalate hydrate yielded Nb100MnO x .

4. The preparation method according to claim 1, characterized in that, In step S2, the amount of ammonia is 15 mL and the amount of water is 30 mL.

5. The preparation method according to claim 1, characterized in that, In step S3, the drying temperature is 80 ℃ and the calcination temperature in the muffle furnace is 500 ℃.

6. The preparation method according to claim 1, characterized in that, In step A1, 0.5 g of zNbyMnO is used. x Disperse in 50 mL of deionized water.

7. The preparation method according to claim 1, characterized in that, The RuCl3 solution in step A2 has a mass fraction of 0.5 wt%-3 wt%.

8. The preparation method according to claim 1, characterized in that, In step A3, the drying temperature is 80 ℃ and the calcination temperature in the muffle furnace is 350 ℃.

9. A catalyst prepared by the method according to any one of claims 1-8, characterized in that, The catalyst is zNbyMnO x Where z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:100; The catalyst is Ru / zNbyMnO x Where z and y represent the molar ratio of Mn to Nb, which ranges from 1:5 to 1:

100.

10. An application of the catalyst according to claim 9, characterized in that, Bimetallic oxide support zNbyMnO x Ruthenium-supported bimetallic oxide Ru / zNbyMnO x Application in the catalytic oxidation of CVOCs (trichloroethylene).

Images