Titanium nitride-based rhodium-palladium catalyst as well as preparation method and application thereof

Abstract

The invention provides a titanium nitride-based rhodium-palladium catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The titanium nitride-based rhodium-palladium catalyst comprises a titanium nitride nano-carrier and a rhodium-palladium alloy nano-cluster loaded on the surface of the titanium nitride nano-carrier.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a titanium nitride-based rhodium-palladium catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Fluorinated organic compounds (FOCs) have been widely used in many key fields such as the manufacture of daily consumer goods, pharmaceutical synthesis, and semiconductor processes due to their excellent chemical and thermal stabilities. However, with the large-scale production and use of FOCs, they inevitably enter various environmental media and organisms through direct and indirect pathways such as direct emissions during the production process or the transformation of precursors in the environment. Since FOCs have the characteristics of bioaccumulation, they can cause significant embryotoxicity and immunosuppressive effects on organisms, posing a potential threat to ecological security. The environmental pollution problems caused thereby have become a global environmental challenge. Therefore, the research and development of ecological risk control and treatment technologies for FOCs have become the core topics of concern in the international environmental scientific community.

[0003] At present, the cleavage of the carbon-fluorine bond (C-F) is the key to treating fluorinated organic compounds (FOCs), which can reduce the degradation difficulty and biological toxicity of FOCs. However, the bond dissociation energy of the C-F bond is as high as 485 kJ / mol, making the cleavage of the C-F bond require harsh conditions such as high temperature and high pressure. How to achieve the cleavage of the C-F bond under mild conditions remains a technical problem.

[0004] Existing research methods for C-F bond cleavage have their respective limitations. The photocatalytic method is pollution-free but has low quantum efficiency and slow treatment; the electrocatalytic method is efficient but has high energy consumption and high cost; the biodegradation method has no chemical pollution, but has a long treatment time and high environmental requirements; the adsorbent method can quickly intercept pollutants, but has problems such as easy pollution, difficult regeneration, and poor adsorption of low-concentration FOCs.

[0005] The hydrogenation reduction method can defluorinate under mild conditions by using active hydrogen to attack the C-F bond, becoming an ideal solution, with the advantages of breaking the C-F bond and regulating the selectivity of products. However, this technology has bottlenecks such as high catalyst cost, insufficient activity, and difficulty in balancing stability and the selectivity of high-value-added products, and there is a lack of application research in actual polluted water environments, and the actual defluorination effect is not yet clear. Summary of the Invention

[0006] In view of the above technical problems, the present invention provides a titanium nitride-based rhodium-palladium catalyst, a preparation method thereof, and an application thereof, in order to at least partially solve the above technical problems. The specific technical solutions provided by the present invention are as follows.

[0007] As a first aspect of the present invention, there is provided a titanium nitride-based rhodium-palladium catalyst, comprising: a titanium nitride nanocarrier, and rhodium-palladium alloy nanoclusters loaded on the surface of the titanium nitride nanocarrier.

[0008] As a second aspect of the present invention, a method for preparing a titanium nitride-based rhodium-palladium catalyst is provided, comprising: adding titanium tetrachloride to an organic solvent and mixing evenly, then introducing ammonia gas for a complexation reaction to obtain a Ti(NH3)4Cl4 complex powder; heating the complex powder in an ammonia atmosphere for a nitridation reaction to obtain titanium nitride nanoparticles; adding a mixed solution containing Rh 3+ salt and Pd 2+ salt to the dispersion of titanium nitride nanoparticles, mixing evenly, and then adding a reducing agent for a reduction reaction to obtain a titanium nitride-based rhodium-palladium catalyst.

[0009] As a third aspect of the present invention, an application of the titanium nitride-based rhodium-palladium catalyst as described above in treating halogenated organic pollutants is provided.

[0010] Based on the above technical solutions, the titanium nitride-based rhodium-palladium catalyst, its preparation method and application provided by the present invention have at least one of the following beneficial effects.

[0011] (1) In the embodiments of the present invention, in the titanium nitride-based rhodium-palladium catalyst (hereinafter referred to as the catalyst) provided by the present invention, the titanium nitride nano-carrier has a large specific surface area and good chemical stability, which can provide rich and stable loading sites for the rhodium-palladium alloy nano-clusters, ensure the uniform dispersion of the active components, and avoid agglomeration and deactivation. Relying on the unique synergistic effect, the rhodium-palladium alloy nano-clusters can greatly reduce the reaction activation energy required for the cleavage of carbon-halogen bonds, and can drive the hydrogenation reduction reaction of halogenated organic pollutants to proceed efficiently under mild conditions, significantly improving the reaction rate. At the same time, the strong interaction formed between the rhodium-palladium alloy nano-clusters and the titanium nitride nano-carrier shows high selectivity for high-value products such as cyclohexanone, avoids the generation of unnecessary by-products, and improves the product yield and purity.

[0012] (2) In the embodiments of the present invention, the preparation method of the titanium nitride-based rhodium-palladium catalyst provided by the present invention ensures excellent performance of the catalyst through step-by-step synthesis. First, a Ti(NH3)4Cl4 complex powder is formed through a complexation reaction, and this complexation process effectively regulates the existence form of the titanium source, laying a foundation for subsequent reactions. Then, the complex powder is heated and nitrided in an ammonia atmosphere to obtain titanium nitride nanoparticles with uniform particle size and stable structure. Its large specific surface area and rich surface active sites provide good conditions for the loading of active components. Finally, through the action of a reducing agent, rhodium and palladium ions are synchronously reduced to alloy nano-clusters and uniformly loaded on the surface of the titanium nitride nanoparticles. During this process, the precise control of the reduction conditions promotes the formation of a strong interaction between the rhodium-palladium alloy nano-clusters and the titanium nitride nanoparticles, not only improving the density and dispersion of the active sites of the catalyst, but also enhancing its structural stability, making the prepared catalyst exhibit high catalytic performance and good cycle stability in catalytic reactions.

[0013] (3) In the embodiments of the present invention, the titanium nitride nanocarrier firmly supports the rhodium-palladium alloy nanoclusters, ensuring that the active sites are highly dispersed and stable, and avoiding the loss and agglomeration of the active components. The rhodium-palladium alloy nanoclusters have excellent catalytic activity, greatly reducing the carbon-halogen bond breaking energy, and rapidly converting halogenated organic pollutants under mild conditions. This catalyst has good universality, can be directed to generate harmless or high-value-added products, and reduce side reactions. In practical applications, its strong interaction with pollutants ensures high-efficiency reactions, and it still maintains high activity and stable performance after multiple cycles, improving the treatment efficiency and reducing costs, providing strong support for pollutant treatment and the green development of the industry. Description of the Drawings

[0014] Figure 1 Rh prepared in Example 1 of the present invention 3 / 5 Pd 2 / 5 Transmission electron microscope image of the Rh

[0015] Figure 2 Rh prepared in Example 1 of the present invention 3 / 5 Pd 2 / 5 Lattice spacing of the Rh

[0016] Figure 3 Transmission electron microscope image of the RhPd / TiN catalyst prepared in the embodiments of the present invention; wherein, a is the transmission electron microscope image of the metal-loaded area; b is the enlarged image of area A in a; c is the transmission electron microscope image of the carrier area; d is the enlarged image of area B in c; 3 / 5Pd 2 / 5 / TiN-0.05wt% transmission electron microscope image; b is Rh 3 / 5 Pd 2 / 5 / TiN-0.1wt% transmission electron microscope image; c is Rh 3 / 5 Pd 2 / 5 / TiN-0.2wt% transmission electron microscope image; d is Rh 3 / 5 Pd 2 / 5 / TiN-0.5wt% transmission electron microscope image; e is Rh 3 / 5 Pd 2 / 5 / TiN-1.0wt% transmission electron microscope image; f is Rh 3 / 5 Pd 2 / 5 / TiN-2.0wt% transmission electron microscope image;

[0017] Figure 4 Rh prepared in Example 1 of the present invention 3 / 5 Pd 2 / 5Spherical aberration electron microscopy images and elemental distribution maps of the Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt% catalyst; b is the spherical aberration electron microscopy image of Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt%; c is the elemental distribution map of rhodium in Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt%; d is the elemental distribution map of palladium in Rh 3 / 5Pd 2 / 5 / TiN-0.2 wt%; e is the elemental distribution map of titanium in Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt%; f is the elemental distribution map of non-metallic nitrogen in Rh

[0018] Figure 5 Catalytic efficiency diagrams of rhodium-palladium nitride-based catalysts with different Rh / Pd molar ratios at a loading rate of 0.5 wt% in Application Example 1 of the present invention; where a is the concentration conversion diagram of reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram;

[0019] Figure 6 Catalytic efficiency diagrams of rhodium-palladium nitride-based catalysts with different Rh and Pd loadings at an Rh / Pd molar ratio of 3:2 in Application Example 2 of the present invention; where a is the concentration conversion diagram of reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram;

[0020] Figure 7 Material balance diagram of the material treated by rhodium-palladium nitride-based catalysts with different Rh and Pd loadings at an Rh / Pd molar ratio of 3:2 in Application Example 2 of the present invention;

[0021] Figure 8 Catalytic efficiency diagrams of the Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt% catalyst in five consecutive catalytic experiments; where a is the concentration conversion diagram of reactant 4-FP; b is the 4-FP conversion rate diagram; c is the reaction rate constant diagram;

[0022] Figure 9 Catalytic efficiency diagrams of the Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt% reactor during the continuous treatment of 500 BV of halogen-containing wastewater; diagram of the change in material composition;

[0023] Figure 10 Catalytic efficiency diagrams of the Rh 3 / 5 Pd 2 / 5Catalytic efficiency diagram of the / TiN-0.2wt% reactor in the process of treating halogen-containing wastewater; among them, a is the conversion diagram of different halogenated organic compound concentrations; b is the first-order kinetic data; c is the reaction rate constant diagram;

[0024] Figure 11 For Rh in Application Example 3 of the present invention 3 / 5 Pd 2 / 5 Diagram of the change in the number of halogenated organic compound species before and after the / TiN-0.2wt% reactor continuously treats 500BV of pharmaceutical wastewater;

[0025] Figure 12 For Rh in Application Example 3 of the present invention 3 / 5 Pd 2 / 5 Diagram of the change in the concentration of halogenated organic compounds before and after the / TiN-0.2wt% reactor continuously treats 500BV of pharmaceutical wastewater;

[0026] Figure 13 Catalytic efficiency diagram of the catalysts prepared using different carriers in Application Example 4 of the present invention; among them, a is the conversion diagram of the concentration of reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram;

[0027] Figure 14 Material balance diagram of the materials treated by the catalysts prepared using different carriers in Application Example 4 of the present invention;

[0028] Figure 15 Catalytic efficiency diagram of the catalysts prepared by different growth methods in Application Example 5 of the present invention; among them, a is the conversion diagram of the concentration of reactant 4-FP; b is the reaction rate constant diagram. Detailed implementation manners

[0029] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0030] In view of the bottlenecks of the existing hydrogenation reduction method, such as high catalyst cost, insufficient activity, difficulty in balancing stability and selectivity of high-value-added products, and the lack of application research in actual polluted water environments with unclear actual defluorination effects, the present invention provides a titanium nitride-based rhodium-palladium catalyst, its preparation method, and application. By adopting a simple and green co-reduction process of mixed precursors and precisely controlling reaction parameters, the rhodium and palladium active components are highly dispersed on the titanium nitride nanocarrier, resulting in a highly active and selective nanocatalyst. It can achieve efficient cleavage and hydrogenation reduction of C-F bonds through the specific interaction between active sites and C-F bonds under mild conditions such as normal temperature and pressure. By optimizing the catalyst composition and structure, the selectivity for high-value-added product cyclohexanone is significantly improved, and side reactions are reduced. At the same time, a simulated industrial sewage treatment platform is built to study its treatment efficiency for actual fluorinated organic pollutants, providing technical and theoretical support for the engineering application of industrial wastewater catalytic purification.

[0031] Specifically, as the first aspect of the present invention, a titanium nitride-based rhodium-palladium catalyst is provided, including: a titanium nitride nanocarrier, and rhodium-palladium alloy nanoclusters loaded on the surface of the titanium nitride nanocarrier.

[0032] In the embodiments of the present invention, in the titanium nitride-based rhodium-palladium catalyst provided by the present invention, the titanium nitride nanocarrier has a large specific surface area and good chemical stability, which can provide rich and stable loading sites for the rhodium-palladium alloy nanoclusters, ensure the uniform dispersion of the active components, and avoid agglomeration and inactivation. The rhodium-palladium alloy nanoclusters can significantly reduce the reaction activation energy required for carbon-halogen bond cleavage by virtue of their unique synergistic effect, and can drive the hydrogenation reduction reaction of halogenated organic pollutants to proceed efficiently under mild conditions, significantly improving the reaction rate. At the same time, the strong interaction formed between the rhodium-palladium alloy nanoclusters and the titanium nitride nanocarrier shows high selectivity for high-value-added products such as cyclohexanone, avoiding the generation of unnecessary by-products, and improving the product yield and purity.

[0033] According to the embodiments of the present invention, the particle size of the titanium nitride nanocarrier is 50-100 nm; the particle size of the rhodium-palladium alloy nanoclusters is 1-3 nm. The loading amount of the rhodium-palladium alloy nanoclusters on the surface of the titanium nitride nanocarrier is 0.05-2 wt%. The molar ratio of metallic rhodium to metallic palladium in the rhodium-palladium alloy nanoclusters is 1:0.5-16.

[0034] In the embodiments of the present invention, the carrier, active components, and their ratios are precisely controlled to achieve synergistic optimization of performance. The titanium nitride nanocarrier provides stable anchoring sites for the rhodium-palladium alloy nanoclusters, ensuring the dispersion of the active components. The strong interaction between the rhodium-palladium alloy nanoclusters and the carrier improves the adsorption and activation efficiency of pollutants. The loading amount is reasonably regulated to ensure active sites and maintain the stability of the system. The specific rhodium-palladium molar ratio exerts the synergistic effect of bimetals, optimizes the reaction path, and enables the catalyst to balance catalytic efficiency and product selectivity when treating halogenated organic pollutants.

[0035] As a second aspect of the present invention, a method for preparing a titanium nitride-based rhodium-palladium catalyst is provided, including: adding titanium tetrachloride to an organic solvent and mixing evenly, then introducing ammonia gas for a complexation reaction to obtain Ti(NH3)4Cl4 complex powder; placing the complex powder in an ammonia atmosphere and heating it for a nitridation reaction to obtain titanium nitride nanoparticles; adding a mixed solution containing Rh 3+ salt and Pd 2+ salt to the dispersion of titanium nitride nanoparticles, mixing evenly, and then adding a reducing agent for a reduction reaction to obtain a titanium nitride-based rhodium-palladium catalyst.

[0036] In an embodiment of the present invention, the method for preparing the titanium nitride-based rhodium-palladium catalyst provided by the present invention ensures excellent performance of the catalyst through step-by-step synthesis. First, Ti(NH3)4Cl4 complex powder is formed through a complexation reaction. This complexation process effectively regulates the existence form of the titanium source and lays a foundation for subsequent reactions. Then, the complex powder is heated and nitrided in an ammonia atmosphere to obtain titanium nitride nanoparticles with uniform particle size and stable structure. Their large specific surface area and abundant surface active sites provide good conditions for the loading of active components. Finally, through the action of a reducing agent, rhodium and palladium ions are simultaneously reduced to alloy nanoclusters and uniformly loaded on the surface of titanium nitride nanoparticles. During this process, precise control of the reduction conditions promotes the formation of strong interactions between the rhodium-palladium alloy nanoclusters and titanium nitride nanoparticles, not only improving the density and dispersion of the active sites of the catalyst, but also enhancing its structural stability, making the prepared catalyst exhibit high catalytic performance and good cyclic stability in catalytic reactions.

[0037] According to an embodiment of the present invention, the organic solvent includes any one of methanol, ethanol, isopropanol, N,N-dimethylformamide (DMF), and acetone. The volume ratio of titanium tetrachloride to the organic solvent is 1:25 to 35.

[0038] In an embodiment of the present invention, the selected organic solvent has good miscibility with titanium tetrachloride, can fully disperse the reactants, provide a homogeneous and stable environment for the complexation reaction, and promote the uniform formation of Ti(NH3)4Cl4 complex. Precise control of the volume ratio of titanium tetrachloride to the organic solvent can adjust the viscosity of the system and the concentration of the reactants, avoiding the formation of agglomerated products or a decrease in reaction efficiency. This ratio keeps the system with appropriate fluidity and mass transfer efficiency, ensuring the full and orderly progress of the complexation reaction and providing conditions for preparing titanium nitride nanocarriers with uniform particle size and stable performance.

[0039] According to an embodiment of the present invention, the Rh 3+ salt includes rhodium trichloride. The Pd 2+ salt includes any one of tetrachloropalladic acid and sodium tetrachloropalladate.

[0040] In the embodiments of the present invention, rhodium trichloride is selected as the Rh 3+ salt, and tetrachloropalladic acid and sodium tetrachloropalladate are selected as the Pd 2+ salts. These salts have good solubility and ion release properties in the reaction system, can stably provide Rh 3+ and Pd 2+ ions, and are uniformly dispersed in the titanium nitride nanoparticle dispersion. Their chemical properties are stable, ensuring that the metal ions remain free before reduction and are synchronously and efficiently reduced when contacting with the reducing agent, avoiding the preferential reduction or agglomeration of a single metal, and achieving the uniform loading of rhodium-palladium alloy nanoclusters on the surface of the support, thereby enhancing the stability of the catalyst active sites.

[0041] In the embodiments of the present invention, the mixed solution containing the Rh 3+ salt and the Pd 2+ salt is prepared by mixing the solution containing the Rh 3+ salt and the solution containing the Pd 2+ salt in proportion. The concentration of the solution containing the Rh 3+ salt is 1 - 10 mmol / L, and the concentration of the solution containing the Pd 2+ salt is 1 - 10 mmol / L. The molar ratio of the Rh 3+ salt to the Pd 2+ salt in the mixed solution is 1:0.5 - 16. The total mass of metallic rhodium and metallic palladium in the mixed solution containing the Rh 3+ salt and the Pd 2+ salt is 0.05 - 2% of the mass of the titanium nitride nanoparticles in the titanium nitride nanoparticle dispersion.

[0042] According to the embodiments of the present invention, the reducing agent includes any one of ascorbic acid, potassium borohydride, sodium borohydride, and sodium bicarbonate. The total molar ratio of the reducing agent to the Rh 3+ salt and the Pd 2+ salt is 60 - 120:1.

[0043] In the embodiments of the present invention, the selected reducing agent has good water solubility and reduction activity, can quickly dissolve in the reaction system, and is uniformly dispersed in the solution containing the Rh 3+ salt and the Pd 2+ salt. By precisely controlling the addition amount of the reducing agent, the metal ions can be fully reduced, avoiding incomplete reduction of the metal ions due to insufficient reducing agent, or waste and impurity generation due to excessive amount. The reducing agent can promote the synchronous and efficient reduction of rhodium and palladium ions into alloy nanoclusters, ensure their uniform loading on the surface of the titanium nitride nanosupport, enhance the number and stability of the catalyst active sites, and achieve the efficient conversion of halogenated organic pollutants.

[0044] In an embodiment of the present invention, to accurately control the reaction process, a reducing agent can be dissolved in water to prepare a reducing agent solution. By controlling the concentration of the reducing agent solution within 60 - 120 mmol / L, it can not only keep the reducing agent in the reaction system with good dispersibility and activity, avoiding overly violent and uncontrollable reactions caused by too high a concentration, but also prevent slow reaction rate and insufficient efficiency due to too low a concentration, thereby providing suitable reaction conditions for the subsequent reduction reaction and ensuring the stable preparation and performance optimization of the titanium nitride-based rhodium-palladium catalyst.

[0045] According to the embodiment of the present invention, the temperature of the complexation reaction is 20 - 30 °C, and the time of the complexation reaction is 10 - 30 min. Ammonia gas is continuously introduced during the complexation reaction, and the inlet gas flow rate of ammonia is 20 - 30 sccm. The temperature of the nitridation reaction is 750 - 850 °C, and the time of the nitridation reaction is 2 - 3 h. Ammonia gas is continuously introduced during the nitridation reaction, and the inlet gas flow rate of ammonia is 30 - 50 sccm. The temperature of the reduction reaction is 0 - 5 °C, and the time of the reduction reaction is 0.5 - 1 h.

[0046] In the embodiment of the present invention, by accurately controlling the temperature, time, and ammonia gas flow rate parameters in each reaction stage, the stability of the catalyst preparation process and the product performance are ensured. The complexation reaction is carried out at 20 - 30 °C for 10 - 30 min, combined with an ammonia gas flow rate of 20 - 30 sccm, which can make titanium tetrachloride and ammonia gas fully contact and uniformly form Ti(NH3)4Cl4 complex, avoiding local overheating or incomplete reaction. The nitridation reaction is carried out at 750 - 850 °C for 2 - 3 h, and nitrogen source is continuously supplied at an ammonia gas flow rate of 30 - 50 sccm to promote the complete nitridation of the complex and form a titanium nitride nanocarrier with good crystallinity and stable structure. The reduction reaction is carried out in a low-temperature environment of 0 - 5 °C for 0.5 - 1 h, effectively inhibiting the agglomeration of rhodium-palladium alloy nanoclusters and enabling them to be uniformly loaded on the surface of the carrier, providing an active material with excellent performance for catalyzing the conversion of halogenated organic pollutants.

[0047] As the third aspect of the present invention, an application of the titanium nitride-based rhodium-palladium catalyst as described above in treating halogenated organic pollutants is provided. Among them, the halogenated organic pollutants include any one of organic fluorine compounds, organic chlorine compounds, organic bromine compounds, and organic iodine compounds.

[0048] In the embodiments of the present invention, the titanium nitride nanocarrier stably supports the rhodium-palladium alloy nanoclusters, ensuring that the active sites are highly dispersed and stable, and avoiding the loss and agglomeration of the active components. The rhodium-palladium alloy nanoclusters have excellent catalytic activity, greatly reducing the carbon-halogen bond breaking energy and rapidly converting halogenated organic pollutants under mild conditions. This catalyst has good universality, can be used to directly produce harmless or high-value-added products, and reduce side reactions. In practical applications, its strong interaction with pollutants ensures high-efficiency reactions, and it still maintains high activity and stable performance after multiple cycles, improving the treatment efficiency and reducing costs, providing strong support for pollutant treatment and the green development of the industry.

[0049] The present invention will be further described below through examples and related test experiments. In the following detailed description, for the sake of explanation, many specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments can also be implemented without these specific details. Moreover, without conflict, the details in the following embodiments can be combined arbitrarily into other feasible embodiments. All instruments, consumables, reagents, etc. in the following examples can be obtained from commercial sources without special instructions.

[0050] Example 1

[0051] In this Example 1, titanium nitride-based rhodium-palladium catalysts with different Rh and Pd loadings and different Rh and Pd molar ratios were prepared, and the preparation method is described as follows.

[0052] First, synthesize the carrier titanium nitride (TiN) nanoparticles. Measure 30 mL of ethanol in a conical flask, and gradually add 1 mL of titanium tetrachloride (TiCl4). Stir magnetically at a speed of 600 rpm for 30 min. After the solution is completely stirred evenly, introduce ammonia gas (NH3) with a flow rate of 30 sccm and a reaction time of 30 min. During this period, a white complex precipitate is formed. After the reaction ends, centrifuge to collect the complex precipitate at a speed of 3000 rpm, and place the centrifugally collected complex precipitate in a vacuum drying oven at 85 °C for 12 h. Grind the dried solid material with an agate mortar into fine particles for full conversion during the later nitridation process. Place the ground material in a tubular furnace and nitridate it at 800 °C for 2 h in an NH3 atmosphere, with an NH3 flow rate of 50 sccm and a heating rate of 5 °C / min. After the nitridation ends, introduce argon gas to cool it down to room temperature to obtain a black powder-like solid, which is the titanium nitride (TiN) nanoparticles.

[0053] Next, a rhodium-palladium / titanium nitride catalyst (denoted as RhPd / TiN) was synthesized. RhPd / TiN catalysts with different Rh and Pd loadings (0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%) and different Rh and Pd molar ratios (1:16, 1:10, 1:8, 1:5, 1:2, 1:1, 3:2, 2:1) were prepared according to research needs. Taking the preparation of a rhodium-palladium / titanium nitride catalyst with 0.2 wt% Rh 3 / 5 Pd 2 / 5 / TiN as an example: First, 120 μL of a 5 mmol / L sodium tetrachloropalladate (NaPdCl4) solution and 80 μL of a 5 mmol / L rhodium(III) chloride (RhCl3) solution were mixed evenly to form a Rh(III)+Pd(II) mixed precursor solution. Then, 50 mg of TiN nanoparticles were added to 20 mL of ultrapure water, and ultrasonic treatment was carried out for 30 min to uniformly disperse TiN in the water. After the ultrasonic treatment, the dispersion was placed in an ice bath and stirred at a high speed of 800 rpm, and the mixed precursor solution was added to the dispersion and stirred evenly. Subsequently, a freshly prepared aqueous potassium borohydride (KBH4) solution (5 mL, 1.7 mg·mL -1 −1) was quickly dropped into the dispersion and stirred for 1 h. Centrifugation was carried out at a speed of 5000 rpm, and it was washed twice with ultrapure water to remove impurities, obtaining a black solid sample, which was the 0.2 wt% Rh 3 / 5 Pd 2 / 5 / TiN catalyst (denoted as Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt%). Finally, the obtained Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt% was vacuum-dried overnight at 85 °C and stored for subsequent experiments. RhPd / TiN catalysts with different Rh and Pd loadings and different Rh and Pd molar ratios were obtained by controlling the addition amounts of the NaPdCl4 solution and the RhCl3 solution.

[0054] Figure 1 Figure 3 / 5 Pd 2 / 5 / TiN-1.0 wt% catalyst prepared in Example 1 of the present invention; among them, a is the transmission electron microscope image of the metal-loaded area; b is the enlarged image of area A in a; c is the transmission electron microscope image of the carrier area; d is the enlarged image of area B in c.

[0055] From Figure 1 it can be seen that Figure 1In the supported metal regions shown in Figures 1-a and 1-b, the distribution of rhodium-palladium alloy nanoclusters on the TiN support is clearly distinguishable. After magnification, Figure 1 Figure 1-b can precisely present the morphological details and particle size of the nanoclusters, reflecting their good dispersion on the support surface, which lays the foundation for providing rich and stable active sites for the catalyst. Figure 1 In the support regions of Figures 1-c and 1-d, after magnification, the lattice fringes are regular, indicating that the TiN support has good crystallinity and a stable structure. The two together show that the Rh 3 / 5 Pd 2 / 5 / TiN-1.0wt% catalyst prepared in Example 1 of the present invention has an excellent microstructure, providing a structural guarantee for its high performance in catalytic reactions.

[0056] Figure 2 Figure 2 is the lattice spacing diagram of the Rh 3 / 5 Pd 2 / 5 / TiN-1.0wt% catalyst prepared in Example 1 of the present invention; among them, a is the lattice spacing diagram of the supported metal region; b is the lattice spacing diagram of the support region.

[0057] From Figure 2 Figure 2-a, it can be seen that the lattice spacing of the rhodium-palladium alloy nanoclusters shows a specific numerical distribution. These values correspond to the crystal structure characteristics of the alloy, reflecting its atomic arrangement and crystal plane spacing, indicating that the supported metal region has a definite crystal structure, providing a stable active center for the catalytic reaction. From Figure 2 Figure 2-b, it can be seen that the lattice spacing of the TiN support also has corresponding characteristics, forming a contrast with the supported metal region, indicating that the TiN support itself has a complete and stable structure and can provide reliable support for the supported metal. The two together show that the Rh 3 / 5 Pd 2 / 5 / TiN-1.0wt% catalyst prepared in Example 1 of the present invention has good stability and order in structure, providing a structural basis for its catalytic performance.

[0058] Figure 3 Figure 3 is the transmission electron microscope image of the RhPd / TiN catalyst prepared in the examples of the present invention; among them, a is the transmission electron microscope image of Rh 3 / 5Pd 2 / 5 / TiN-0.05wt%; b is the transmission electron microscope image of Rh 3 / 5 Pd 2 / 5 / TiN-0.1wt%; c is the transmission electron microscope image of Rh 3 / 5 Pd 2 / 5 / TiN-0.2wt%; d is the transmission electron microscope image of Rh 3 / 5 Pd 2 / 5 / TiN-0.5wt%; e is Rh3 / 5 Pd 2 / 5 TEM image of Pd / TiN - 1.0 wt%; f is Rh 3 / 5 Pd 2 / 5 TEM image of Pd / TiN - 2.0 wt%.

[0059] From Figure 3 it can be seen that as the loading amount gradually increases from 0.05 wt% to 2.0 wt%, the distribution and aggregation state of rhodium - palladium alloy nanoclusters in the catalyst on the TiN support change. At low loading amounts, the nanoclusters are relatively evenly dispersed; after the loading amount increases, the nanoclusters aggregate to a certain extent, but overall, they still maintain a certain degree of dispersion on the surface of the support. At the same time, the morphology of the support TiN remains basically stable, indicating that the catalysts with different loading amounts prepared in the present invention have controllability in microstructure, providing an intuitive structural basis for studying the relationship between the loading amount and catalytic performance.

[0060] Figure 4 The Cs - TEM image and elemental distribution map of the Rh 3 / 5 Pd 2 / 5 / TiN - 0.2 wt% catalyst prepared in Example 1 of the present invention; where a is Rh 3 / 5 Pd 2 / 5 Cs - TEM image of Pd / TiN - 0.2 wt%; b is Rh 3 / 5 Pd 2 / 5 Elemental distribution map of metallic rhodium in Pd / TiN - 0.2 wt%; c is Rh 3 / 5 Pd 2 / 5 Elemental distribution map of metallic palladium in Pd / TiN - 0.2 wt%; d is Rh 3 / 5Pd 2 / 5 Elemental distribution map of metallic titanium in Pd / TiN - 0.2 wt%; e is Rh 3 / 5 Pd 2 / 5 Elemental distribution map of non - metallic nitrogen in Pd / TiN - 0.2 wt%.

[0061] From Figure 4 it can be seen that through the Cs - TEM image and elemental distribution map, the microstructure and elemental distribution of the Rh 3 / 5 Pd 2 / 5 / TiN - 0.2 wt% catalyst prepared in Example 1 of the present invention can be clearly understood. Figure 4 -a presents the high - resolution microstructure of the catalyst, showing atomic - level structural details. Figure 4 -b to Figure 4-e respectively show the elemental distributions of metallic rhodium, palladium, metallic titanium, and non-metallic nitrogen. It can be seen that rhodium and palladium elements exhibit specific distributions in the catalyst, indicating the existence and distribution state of rhodium-palladium alloy nanoclusters; the distributions of titanium and nitrogen elements reflect the structural integrity of the TiN support, and the elemental distributions are relatively uniform, indicating that the catalyst has good compositional homogeneity and structural stability at the atomic scale, providing a structural guarantee for its catalytic performance.

[0062] Application Example 1

[0063] In this Application Example 1, the catalytic performances of different catalysts with a fixed loading of 0.5 wt% and different Rh / Pd molar ratios in Example 1 were tested, including catalysts with Rh / Pd molar ratios of 1:16, 1:10, 1:8, 1:5, 1:2, 1:1, 3:2, 2:1, as well as single-metal loaded catalysts Pd / TiN-0.5 wt% and Rh / TiN-0.5 wt%.

[0064] The experimental method for catalytic hydrodefluorination is as follows: Add 1 mL of an aqueous solution of 4-fluorophenol (denoted as 4-FP) with a concentration of 30 mmol / L to 27 mL of ultrapure water as the reaction model pollutant, add 1 mL of an aqueous solution of NaOH with a concentration of 45 mmol / L to adjust the pH of the system to be within the range of 8 - 9, and place it on a magnetic stirring table and continuously stir at a speed of 450 rpm. At the same time, turn on the hydrogen generator, as the hydrogen (H2) source for the catalytic reaction, and introduce it into the above solution so that 100 mL·min -1 of H2 can be continuously and stably produced. After the H2 production is stable, add 1 mL of the catalyst (the total molar concentration of Rh and Pd is 0.6 mmol, and at this time, the molar ratio of the reactant 4-FP to the bimetallic Rh and Pd in the system is 50:1), and at the same time start the catalytic reaction. Filter and sample at regular intervals using a syringe and a filter head with a pore size of 0.22 μm, and obtain the peak areas of the reactant 4-FP and the product phenol after the catalytic reaction through HPLC analysis. Determine their specific contents according to the standard curves of 4-FP and phenol plotted, so as to analyze the conversion rate of 4-FP, reaction kinetics, material balance, etc.

[0065] Figure 5 This is the catalytic efficiency diagram of different rhodium-palladium catalysts based on titanium nitride with a loading rate of 0.5 wt% in Application Example 1 of the present invention; among them, a is the concentration conversion diagram of the reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram.

[0066] From Figure 5It can be seen that for single-metal-loaded catalysts, Rh / TiN-0.5wt% and Pd / TiN-0.5wt% have almost no catalytic activity, indicating that simply loading a single metal Rh or metal Pd cannot catalyze the cleavage and hydrogenation of the C-F bond in 4-FP, and it is still very difficult to achieve C-F bond hydrogenation and defluorination under mild environmental conditions. However, after loading two metals on the surface of the carrier TiN simultaneously, the catalytic hydrogenation and defluorination efficiency of 4-FP is significantly improved. When the Rh / Pd molar ratio increases to 3:2, the catalytic activity of Rh 3 / 5 Pd 2 / 5 / TiN-0.5wt% reaches the most satisfactory level, and 100% conversion of 4-FP can be achieved within 30 min, completing the cleavage and hydrogenation of all C-F bonds. At the same time, reaction kinetics analysis shows that the calculated rate constant of the catalyst Rh 3 / 5 Pd 2 / 5 / TiN-0.5wt% increases to the maximum value of 0.24 min -1 −1, presenting the best catalytic activity. Based on the above tests, it can be determined that under the condition of a loading amount of 0.5wt%, the RhPd / TiN catalyst with an Rh / Pd molar ratio of 3:2 has the most efficient catalytic hydrogenation and defluorination ability.

[0067] Application Example 2

[0068] On the basis of Application Example 1, in this Application Example 2, the catalytic performance of the catalysts with a fixed Rh / Pd molar ratio of 3:2 and different Rh and Pd loading amounts in Example 1 was tested, including catalysts with Rh and Pd loading amounts of 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, 1wt%, and 2wt%. The tests were carried out according to the method described in Application Example 1.

[0069] Figure 6 This is the catalytic efficiency diagram of rhodium-palladium catalysts based on titanium nitride with different Rh and Pd loading amounts when the Rh / Pd molar ratio is 3:2 in Application Example 2 of the present invention; among them, a is the concentration conversion diagram of the reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram.

[0070] Figure 6 It shows that according to the concentration change of 4-FP, it can be seen that the catalytic activity of the catalyst Rh 3 / 5 Pd 2 / 5 / TiN changes significantly with the increase of the loading amount. The catalytic efficiency of the catalyst Rh 3 / 5 Pd 2 / 5 / TiN-0.05wt% is extremely weak at the lowest loading amount of 0.05wt%, and the catalytic efficiency increases rapidly with the gradual increase of the loading amount. When the loading amount is increased to 0.2wt%, the catalyst Rh 3 / 5 Pd 2 / 5 / TiN-0.2 wt% exhibits the maximum catalytic efficiency. Continuing to increase the loading amount, the catalytic efficiency of the catalyst gradually weakens, indicating that too large Rh and Pd loading amounts do not provide more active sites and are not helpful for improving the catalytic activity. First-order reaction kinetics analysis shows that when the loading amount is 0.05 wt%, the calculated kinetic constant is the smallest, only 0.0018 min -1 . When the loading amount increases to 0.1 wt%, the calculated kinetic constant increases by about 3.2 times, to 0.058 min -1 . When the loading amount increases to 0.2 wt%, the calculated kinetic constant rapidly increases to reach the maximum value of 0.26 min -1 , which is 144.4 times larger than the catalyst with the lowest loading amount, showing the highest catalytic reaction efficiency. Further increasing the loading amount, in the process of increasing the loading amount from 0.5 wt% to 2 wt%, the calculated rate constant of the catalytic reaction shows a monotonically decreasing trend.

[0071] Furthermore, the liquid samples collected during the reaction process are extracted with dichloromethane, and analyzed by gas chromatography-mass spectrometry GC / Q-TOF to obtain the peak areas of the products cyclohexanone and cyclohexanol after the catalytic reaction. According to the standard curves of cyclohexanone and cyclohexanol drawn, their specific contents are determined, so as to analyze the selectivity of cyclohexanone and cyclohexanol, material balance, etc.

[0072] Figure 7 This is the material balance diagram of the rhodium-palladium catalyst based on titanium nitride with different Rh and Pd loadings when the Rh / Pd molar ratio is 3:2 in Application Example 2 of the present invention.

[0073] In Figure 7 , the products of the RhPd / TiN catalyst at each loading amount are analyzed. It can be seen that when the loading amount increases from 0.05 wt% to 0.2 wt%, the product of the RhPd / TiN catalyst for the defluorination hydrogenation of 4-FP is only cyclohexanone, and the selectivity for cyclohexanone is as high as 100%. Continuing to increase the loading amount, the catalytic products include not only cyclohexanone and unreacted phenol, but also deeply hydrogenated cyclohexanol. Through the above research, it is found that the low-loading catalyst has ultra-high selectivity for cyclohexanone, and the selectivity of the high-loading catalyst for cyclohexanone will decrease.

[0074] The stability of the catalyst is also an important index for evaluating the performance of the catalyst. For the stability of the catalyst RhPd / TiN, the present invention uses the results of five consecutive catalytic hydrogenation defluorination experiments to measure, and the same experimental methods and operating conditions as those in the above catalytic hydrogenation defluorination research are used. By obtaining the catalytic experimental results after each cycle, the conversion rate of 4-FP and the reaction rate constant are calculated to evaluate the catalytic efficiency of the catalyst. And by observing the change of the catalytic efficiency of the catalyst, the dynamic behavior of the catalyst RhPd / TiN during the reaction process can also be revealed.

[0075] Figure 8 For the Rh in Application Example 2 of the present invention 3 / 5 Pd 2 / 5 Catalytic efficiency graph of the RhPd / TiN-0.2wt% catalyst in five cyclic catalytic experiments; wherein, a is the concentration conversion graph of reactant 4-FP; b is the conversion rate graph of 4-FP; c is the reaction rate constant graph.

[0076] From Figure 8 It can be seen that the RhPd / TiN catalyst still maintains high catalytic activity and efficiency in the five cyclic catalytic experiments. Despite being recycled five times, the defluorination and hydrogenation conversion rate of the RhPd / TiN catalyst for 4-FP is still as high as over 99% within 25 min. Thus, it can be seen that the RhPd / TiN catalyst still maintains a relatively high reaction rate and has high stability after being recycled five times. However, from the perspective of the rate constant, the rate constant of the RhPd / TiN catalyst shows a gradually decreasing trend during the five cycles, and the rate constant in the fifth catalytic reaction is only 48% of that in the first catalytic reaction. This may be due to the occurrence of carbon deposition during the continuous cyclic reaction, that is, the intermediate product phenol generated during the catalytic defluorination and hydrogenation of 4-FP will undergo further deep hydrogenation, which requires occupying the active sites of the catalyst. This will not only change the catalytic environment but also reduce the catalytic activity of the catalyst, thereby reducing the rate constant of the catalytic reaction.

[0077] Application Example 3

[0078] In this Application Example 3, two actual sewage treatment simulation reactors for natural sewage and industrial sewage were built using the RhPd / TiN catalyst to evaluate the catalytic performance of the RhPd / TiN catalyst when put into actual application. The operation steps are as described below.

[0079] (1) Weigh 200 mg of the synthesized RhPd / TiN catalyst (the RhPd / TiN-0.2wt% with the best catalytic performance tested in Application Example 2) 3 / 5Pd 2 / 5 and 15 g of quartz sand with a particle size of 110 - 160 mesh, and place them in an agate mortar and grind for 20 min to fully mix the solid mixture evenly. A state where the color is consistent and there are no obvious particles separated is considered to be evenly mixed.

[0080] (2) First, weigh 2 g of quartz sand with a particle size of 26 - 40 mesh at the bottom of a customized quartz tube, then put in 2 g of quartz sand with a particle size of 110 - 160 mesh, and then put in the evenly mixed RhPd / TiN mixture to complete the filling of the RhPd / TiN actual sewage simulation reaction column.

[0081] (3) The filled RhPd / TiN actual sewage simulation reaction column is fixed on an iron frame, and a peristaltic pump, a vacuum pump, a hydrogen generator, an injection bottle and a water outlet bottle are connected to realize the construction of the RhPd / TiN actual sewage simulation reactor.

[0082] After completing the construction of the RhPd / TiN actual sewage simulation reactor, two water bodies, river water and pharmaceutical wastewater, were selected as simulated natural sewage and industrial sewage, respectively, and the RhPd / TiN actual sewage simulation reactor was operated.

[0083] The operation of natural sewage is as follows: first, the water sample is treated. The river water of Qinghe River in Beijing is selected and the collected river water is simply filtered with a 0.22μm filter membrane to remove large impurities and microorganisms in the river water; then a simulated polluted river water sample is prepared. First, 897.6mL of the treated river water sample is taken into a sampling bottle, and 600μL of 30mmol / L 4-FP solution, 600μL of 30mmol / L 4-chlorophenol (4-CP) solution, and 600μL of 3 0mmol / L 4-bromophenol (4-BP) solution and 600μL 30mmol / L 4-iodophenol (4-IP) solution were mixed evenly under ultrasound to prepare a mixed water sample of 4-FP, 4-CP, 4-BP and 4-IP with a concentration of 0.02mmol / L as simulated natural sewage; ultrapure water was injected into the filled dry reaction column until the filler was filled, and the ultrapure water in the filler completely flowed out to the outlet level below. The volume of the outflowing water was calculated as the column volume of the reaction column. (BV); turn on the peristaltic pump, add the river water sample in the water inlet bottle into the reaction column, adjust the flow rate parameters, turn on the hydrogen generator and the vacuum pump, control the flow rate of the water sample into the reactor to be the same as the outflow rate, maintain the stable operation of the reactor, and sample 10mL into the sample bottle every 50BV; use a syringe to take 1mL of the sample, filter it through a 0.22μm filter membrane, and inject it into the injection vial, and use high performance liquid chromatography (HPLC) to determine the conversion amount of the halogenated compound in the treated water sample and the generation amount of the product phenol; similarly, take the The filtered water sample was used for determining the amount of metal dissolved from the catalyst during operation by inductively coupled plasma mass spectrometry (ICP-MS) to determine the stability of the catalyst and the reactor. 1 mL of the water sample was filtered through a 0.22 μm filter membrane, a certain amount of dichloromethane was added, and the sample was vortexed for 1 min to fully extract the product to be tested in the water sample into the dichloromethane. The amount of cyclohexanone and cyclohexanol produced in the treated water sample was determined by gas chromatography-mass spectrometry (GC / Q-TOF) to evaluate the treatment capacity of the reactor and the reaction effect of the catalyst.

[0084] Figure 9 Rh in Application Example 3 of the present invention 3 / 5 Pd 2 / 5Material composition change diagram during the continuous treatment of 500 BV of halogen-containing wastewater in the Rh

[0085] It can be seen from Figure 9 the figure that when the reaction column runs continuously for 150 BV, all halogenated phenols in the sewage, including the reaction intermediate phenol, can be completely converted, and at the same time, a high selectivity for cyclohexanone is maintained, reflecting excellent catalytic activity. When the operation reaches 150 BV, the catalytic activity of the reaction column slightly decreases. At this time, 0.015 mmol of the intermediate product phenol is not completely converted, but still maintains a 100% conversion rate for the four halogenated phenols. As the running time of the reactor increases and the reaction volume increases to 200 BV, about 5% of 4-FP has not been converted, but it always maintains high stability and selectivity for the final product cyclohexanone. When the reaction volume increases to 450 BV, the removal rates of the reaction column for 4-FP and 4-CP drop to 78.4% and 87.6%, respectively. During the process of the reactor treating 500 BV of sewage, the activity of the catalyst shows a certain degree of decline, and the treatment capacity for 4-FP decreases by 21.6%. Generally speaking, the reactor maintains a stable operation trend throughout the operation process, and shows high catalytic activity for halogenated organic compounds and high selectivity for the high-value-added product cyclohexanone.

[0086] Figure 10 Pd / TiN-0.2wt% reactor in Application Example 3 of the present invention 3 / 5 Pd 2 / 5 Catalytic efficiency diagram during the treatment of halogen-containing wastewater by the RhPd / TiN-0.2wt% reactor; where a is the conversion diagram of different halogenated organic compound concentrations; b is the first-order kinetic data; c is the reaction rate constant diagram.

[0087] It can be seen from Figure 10 the figure that the hydrodehalogenation (HDH) activities of the RhPd / TiN catalyst for different halogenated phenols show significant differences. In this comparative test, considering the low bond energies of carbon-chlorine (C-Cl), carbon-bromine (C-Br), and carbon-iodine (C-I) bonds, the ratio of the catalyst to the reactant was reduced from 1:50 to 1:200. According to the data shown in the above charts, the first to complete all conversions is 4-BP, and the complete cleavage and hydrogenation of C-Br can be achieved in 9 minutes. Followed by 4-IP, and 100% conversion of the C-I bond is achieved after 12 minutes of reaction. 4-CP completes the conversion of the C-Cl bond within 30 minutes of reaction. Finally, it is 4-FP, and the conversion rate of 4-FP drops to 64% after 60 minutes of reaction. According to the conversion data of halogenated phenols, it is determined that this hydrodehalogenation reaction conforms to the first-order reaction kinetics. Therefore, a first-order reaction kinetics fitting is carried out on it to calculate the calculated rate constant of the catalytic reaction, and the results are as shown in Figure 10-c as shown. Under this reaction condition, the slope of the kinetic curve for catalyzing the 4-FP reaction is the smallest, that is, the calculated kinetic constant is the smallest, only 0.018 min -1 . The calculated kinetic constant for catalyzing 4-CP is increased by about 10 times compared with 4-FP, reaching 0.18 min -1 . When catalyzing 4-BP, the calculated rate constant of the catalytic reaction is further increased, reaching 0.43 min -1 . When catalyzing 4-IP, the calculated rate constant of the reaction is decreased to 0.35 min -1 .

[0088] The operation for industrial sewage is as follows: First, perform the pretreatment of the water sample. This industrial sewage is taken from a domestic pharmaceutical factory. The collected pharmaceutical wastewater is filtered with a 0.22 μm filter membrane to remove large impurities and organic matters in the river water. Then, turn on the peristaltic pump, add the river water sample in the water inlet bottle to the reaction column, adjust the flow rate parameters, turn on the hydrogen generator and the vacuum pump, control the flow rate of the water sample flowing into the reactor to be the same as the outflow rate, maintain the stable operation of the reactor, and take 50 mL samples every 100 BV and put them into the sample bottles. Take 30 mL of the treated water sample, filter it with a 0.45 μm filter membrane, extract it with an activated solid-phase extraction column, and then elute it with methanol. Freeze-dry the methanol eluate for 24 h, add 1 mL of methanol to redissolve it, and determine the types and quantities of halogenated organic compounds contained in the water sample by Fourier transform ion cyclotron resonance mass spectrometry FT-ICR MS. Take 5 mL of the treated water sample, filter it with a 0.22 μm filter membrane, and determine the concentration of halogenated organic compounds contained in the water sample by ICP-MS to evaluate the treatment effect of the reactor on the pharmaceutical wastewater.

[0089] Figure 11 This is the graph of the change in the number of halogenated organic compound species before and after the Rh 3 / 5 Pd 2 / 5 / TiN-0.2wt% reactor continuously treats 500 BV of pharmaceutical wastewater in Application Example 3 of the present invention; Figure 12 This is the graph of the change in the concentration of halogenated organic compounds before and after the Rh 3 / 5 Pd 2 / 5 / TiN-0.2wt% reactor continuously treats 500 BV of pharmaceutical wastewater in Application Example 3 of the present invention.

[0090] From Figures 11 - 12It can be seen that FT-ICR-MS tests were conducted on the number of species of halogenated organic compounds in the effluent before the reaction and when treating 100 BV, 200 BV, 300 BV, 400 BV, and 500 BV volumes. 358 species of organofluorine compounds, 229 species of organochlorides, 61 species of organobromides, and 90 species of organoiodides were detected in the original pharmaceutical wastewater. When continuously treating 100 BV of the water sample, the effluent after the reaction treatment contained only 29 species of organofluorine compounds, 38 species of organochlorides, 1 species of organobromide, and 5 species of organoiodides. The RhPd / TiN reactor has a high catalytic dehalogenation ability for 91.9% of organofluorine compounds, 83.4% of organochlorides, 98.4% of organobromides, and 94.4% of organoiodides. As the treated water volume increases, the reaction continues until 500 BV of pharmaceutical wastewater is continuously treated. It can be observed that the treatment of the types of halogenated organic compounds by the reactor gradually stabilizes, and the quantity removal rate of halogenated organic compounds in this system remains at 76% - 98.4%. GC / Q-TOF analysis shows that the selectivity of the RhPd / TiN reactor for cyclohexanone is always higher than 80%, and it maintains a treatment efficiency of more than 80% for the number of species of halogenated organic compounds.

[0091] ICP-MS was used to test the concentration of halogenated organic compounds in the samples before and after treating 500 BV of pharmaceutical wastewater. The total contents of organofluorine, chlorine, bromine, and iodine in the original pharmaceutical wastewater reached 9000 μg / L, 6920 μg / L, 1390 μg / L, and 2176 μg / L respectively. During the continuous treatment of 500 BV of wastewater, the concentration conversion efficiencies of the RhPd / TiN reaction column for organofluorine, chlorine, bromine, and iodine were stably maintained at 88%, 90.5%, 95.8%, and 95.7% respectively. In addition, the organofluorine, chlorine, bromine, and iodine in the effluent all meet the national industrial water pollutant discharge standards, fully demonstrating that the RhPd / TiN catalyst has excellent catalytic performance under environmental relevant conditions and highlighting its engineering application potential in the actual water treatment environment.

[0092] Application Example 4

[0093] In Application Example 4 of the present invention, to further verify the high catalytic performance characteristics of the RhPd / TiN catalyst, five materials commonly used as catalyst supports in research were selected, including titanium dioxide (TiO2), silicon dioxide (SiO2), silicon nitride (SiN), aluminum oxide (SiO2), and graphene (C). A batch of catalysts with the same synthesis parameters (loading of 0.2 wt% and Rh / Pd molar ratio of 3:2) but different supports were prepared as the catalyst for the experimental control group, namely RhPd / TiO2, RhPd / SiO2, RhPd / SiN, RhPd / Al2O3, and RhPd / C. The catalytic performance test was carried out under exactly the same conditions and operations as in Application Example 1, and the concentration change of 4-FP and the results of the first-order reaction kinetics simulation test were obtained.

[0094] Figure 13 It is the catalytic efficiency diagram of the catalysts prepared with different supports in Application Example 4 of the present invention; among them, a is the concentration conversion diagram of the reactant 4-FP; b is the first-order reaction kinetics diagram; c is the reaction rate constant diagram.

[0095] From Figure 13 it can be seen that the RhPd / TiN catalyst exhibits the most satisfactory catalytic activity. Among the control materials, the catalytic activity of RhPd / C is the weakest, and the conversion rate of 4-FP within 60 min of the reaction is only 6.2%. Followed by RhPd / SiN and RhPd / Al2O3, the conversion rates of 4-FP within 60 min of the reaction are 89.2% and 92.3% respectively. RhPd / TiO2 and RhPd / SiO2 have prominent catalytic activities among the control materials and can complete the hydrodefluorination conversion of 4-FP in 30 min and 45 min respectively, but their catalytic activities are still not sufficient to compare with RhPd / TiN. The concentration change of 4-FP converted by all the control group catalysts was subjected to a first-order reaction kinetics simulation to calculate the kinetic curves and reaction constants of each reaction process. RhPd / TiN has the highest calculated reaction constant among all the catalysts, showing excellent catalytic performance for the hydrodefluorination reaction. Even RhPd / TiO2 prepared from TiO2, which has attracted much attention in the field of nanocatalysis, its calculated reaction constant is only 50% of that of RhPd / TiN, which is 0.014 min -1 . And the calculated reaction rate constants of RhPd / SiO2, RhPd / SiN, RhPd / Al2O3, and RhPd / C are only 0.12 min -1 , 0.039 min -1 , 0.044 min -1 and 0.0032 min -1This result further proves that the catalyst RhPd / TiN, which is designed to support Rh and Pd on TiN and optimized with a loading amount of 0.2 wt% and an Rh / Pd molar ratio of 3:2, has outstanding catalytic performance in the dehydrofluorination hydrogenation of C-F bonds.

[0096] In addition, to systematically investigate the influence of the support effect on the catalytic system, GC / Q-TOF product analysis was also carried out for the blank control group catalysts RhPd / TiO2, RhPd / SiO2, RhPd / SiN, RhPd / Al2O3, and RhPd / C. The product distribution characteristics of the catalysts with different supports showed significant differences.

[0097] Figure 14 This is the material balance diagram of the materials treated with the catalysts prepared using different supports in Application Example 4 of the present invention.

[0098] From Figure 14 it can be seen that for the catalysts RhPd / TiO2 and RhPd / SiO2, although they showed relatively high activity among the control group catalysts, after analyzing their reaction products, it was found that the selectivities of the catalysts RhPd / TiO2 and RhPd / SiO2 for cyclohexanone were only 82.5% and 78.2% respectively. The activities of RhPd / SiN and RhPd / Al2O3 in catalyzing C-F bonds are relatively weak, and their conversion ability for the primary product phenol after the dehydrofluorination hydrogenation of 4-FP is insufficient, and the selectivity for the deep hydrogenation product cyclohexanone is not high. For the catalyst RhPd / C, the product of the deep hydrogenation of the primary product phenol is only cyclohexanone, and the selectivity for cyclohexanone is 100%, but its activity in catalyzing C-F dehydrofluorination hydrogenation is very weak, and only 6.2% of 4-FP can be converted after reacting for 60 min. Therefore, based on the above research, the catalyst RhPd / TiN not only has high efficiency in the dehydrofluorination hydrogenation of 4-FP, but also has the characteristic of ultra-high selectivity for cyclohexanone.

[0099] Application Example 5

[0100] In this Application Example 5, RhPd / TiN prepared by different growth methods was used as a comparison material, specifically including: adding Rh 3+ salt during the synthesis of carbon nitride nanoparticles, and then loading metal palladium (denoted as Rh+Pd / TiN Pd ); and adding Pd 2+ salt during the synthesis of carbon nitride nanoparticles, and then loading metal rhodium (denoted as Pd+Rh / TiN Rh ). The catalytic performance test was carried out under exactly the same conditions and operations as in Application Example 1, and the obtained 4-FP concentration change and the first-order reaction kinetic simulation test results were obtained.

[0101] Figure 15Catalytic efficiency diagrams of catalysts prepared by different growth methods in Application Example 5 of the present invention; among them, a is the concentration conversion diagram of reactant 4-FP; b is the reaction rate constant diagram.

[0102] From Figure 15 It can be seen that different from the RhPd / TiN catalyst prepared by the mixed growth method of the invention, the bimetallic catalysts Rh+Pd / TiN Pd and Pd+Rh / TiN Rh constructed by different metal deposition sequences show significantly different catalytic activities in the catalytic reaction of 4-FP. Among them, the first-order reaction rate constant of Pd+Rh / TiN Rh is only 0.068 min -1 , while the activity of Rh+Pd / TiN Pd reaches 0.19 min -1 , about 2.8 times that of the former. However, the catalytic efficiencies of both are lower than those of the bimetallic catalyst RhPd / TiN prepared by mixed growth, which once again shows that the RhPd / TiN catalyst prepared by this method has outstanding catalytic performance.

[0103] In summary, the RhPd / TiN catalyst provided by the present invention has a simple synthesis step, can be rapidly synthesized under normal temperature and pressure, with mild and green conditions, and can be mass-produced in the laboratory. It has a bimetallic supported structure, and the surface Rh-Pd bimetallic active sites are in the form of sub-nanometer clusters. With the synergistic effect of the bimetallic and the carrier, the catalytic performance is improved, the amount of precious metals used is reduced, and the cost is saved. This catalyst has ultra-high hydrodefluorination ability, can directionally convert halogenated phenols into high-value cyclohexanone. Compared with the control materials, it has the highest catalytic activity, can completely break and hydrogenate the C-F bond within 20 minutes. Product analysis shows that it can rapidly hydrogenate the C-F bond to form phenol and deeply hydrogenate and directionally convert all of them into cyclohexanone, with the highest selectivity for cyclohexanone. Based on the simulated industrial sewage treatment reactor constructed with it, the conversion efficiency of organic halogen pollutants reaches 88%-95.7%, and the selectivity for cyclohexanone exceeds 80%. Moreover, the catalyst is stable and efficient under continuous operation of 500 BV, having the potential for wastewater treatment applications and laying a technical foundation for large-scale applications.

[0104] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A titanium nitride-based rhodium palladium catalyst, characterized in that, Comprising: A titanium nitride nanocarrier, and rhodium-palladium alloy nanoclusters loaded on the surface of the titanium nitride nanocarrier.

2. The catalyst according to claim 1, characterized in that, The particle size of the titanium nitride nanocarrier is 50 - 100 nm; The particle size of the rhodium-palladium alloy nanoclusters is 1 - 3 nm.

3. The catalyst according to claim 1, characterized in that, The loading amount of the rhodium-palladium alloy nanoclusters on the surface of the titanium nitride nanocarrier is 0.05 - 2 wt%.

4. The catalyst according to claim 3, characterized in that The molar ratio of metallic rhodium to metallic palladium in the rhodium-palladium alloy nanoclusters is 1:0.5 - 16.

5. A method for preparing a titanium nitride-based rhodium-palladium catalyst according to any one of claims 1-4, characterized in that, Comprising: Adding titanium tetrachloride into an organic solvent and mixing evenly, then introducing ammonia gas for a complexation reaction to obtain a Ti(NH3)4Cl4 complex powder; Placing the complex powder in an ammonia gas atmosphere and heating for a nitridation reaction to obtain titanium nitride nanoparticles; Will contain Rh 3+ Salt and Pd 2+ The mixed salt solution is added to the dispersion of the titanium nitride nanoparticles and mixed evenly, and then a reducing agent is added to carry out a reduction reaction to obtain a titanium nitride-based rhodium palladium catalyst.

6. The preparation method according to claim 5, wherein, The organic solvent includes any one of methanol, ethanol, isopropanol, N,N-dimethylformamide, and acetone; The volume ratio of the titanium tetrachloride to the organic solvent is 1:25 - 35.

7. The preparation method according to claim 5, characterized in that, The Rh 3+ salt includes rhodium trichloride; The Pd 2+ salt includes any one of tetrachloropalladic acid and sodium tetrachloropalladate.

8. The preparation method according to claim 5, characterized in that, The reducing agent includes any one of ascorbic acid, potassium borohydride, sodium borohydride, and sodium bicarbonate; The reducing agent and Rh 3+ salt and Pd 2+ The total molar ratio of the salt is 60 to 120:

1.

9. The preparation method according to claim 5, characterized in that, The temperature of the complexation reaction is 20 - 30 °C, and the time of the complexation reaction is 10 - 30 min; During the complexation reaction, ammonia gas is continuously introduced, and the inlet flow rate of ammonia gas is 20 - 30 sccm; The temperature of the nitridation reaction is 750 - 850 °C, and the time of the nitridation reaction is 2 - 3 h; During the nitridation reaction, ammonia gas is continuously introduced, and the inlet flow rate of ammonia gas is 30 - 50 sccm; The temperature of the reduction reaction is 0 - 5 °C, and the time of the reduction reaction is 0.5 - 1 h.

10. Use of a titanium nitride-based rhodium-palladium catalyst as described in any one of claims 1 - 4 in treating halogenated organic pollutants.

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