Titanium nitride nickel-based palladium catalyst, its preparation method and application

Abstract

The application belongs to the technical field of catalysts, and provides a titanium nickel nitride-based palladium catalyst, a preparation method and application thereof. The method comprises the following steps: mixing titanium tetrachloride, nickel acetate tetrahydrate and ethanol under an ammonia atmosphere, and performing a reaction to obtain a complex powder; performing a nitriding reaction on the complex powder under an ammonia atmosphere to obtain titanium nickel nitride nanoparticles; mixing the titanium nickel nitride nanoparticles, a chloropalladic acid solution, water and a potassium borohydride solution, and performing a reaction to obtain the titanium nickel nitride-based palladium catalyst. The catalyst prepared by the application has a high specific surface area and is composed of two parts, namely a titanium nickel nitride nanoparticle carrier and a supported Pd nanocluster. Among them, nickel atoms are doped between the titanium nitride crystal lattices. The Pd nanocluster is supported on the surface of the TiNiN carrier, and by adjusting the loading amount of Pd atoms, efficient and high-selectivity catalysis of various environmental hydrogenation catalytic processes can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a titanium nitride nickel-based palladium catalyst and a preparation method and application thereof. BACKGROUND

[0002] In the actual environmental pollutant treatment process, a series of pollutants in the environmental treatment process are treated by a catalytic reduction process (such as catalytic hydrogenation dehalogenation of halogenated organic matter), which shows great prospects in treating environmental pollutants that cannot be treated by alternative oxidation processes (such as incineration) or environmental pollutants that have the potential to recover resources from waste. Since palladium has high activity in activating H2 or electro-reducing H2O to provide active H* species at room temperature, and has high stability in activating target chemical bonds such as C-X, C-O and N-O, palladium is the most active catalyst in the catalytic reduction process.

[0003] However, the instability and low intrinsic activity of palladium limit its wide application in the environmental field. Since the formation energy of palladium is large, which is-117.42 KJ / mol, it is easy to be oxidized to PdO and easily dissolved in the reaction medium, which makes it difficult for palladium to maintain long-term stability in the environmental catalytic process. At the same time, the intrinsic activity of palladium is not satisfactory, and the mass activity of palladium black is as low as 0.42 L·gPd -1 ·min -1 , which further reduces the practical applicability of palladium catalysts in the conversion of environmental pollutants.

[0004] In order to improve the practicability of Pd, various strategies have been proposed in existing research, including material innovation, design of new Pd-based reaction models and development of new reaction pathways. Among these strategies, the structure of Pd sites is adjusted by engineering the arrangement of surface Pd atoms, a small amount of noble metal atoms is doped into Pd, or a Pd coating layer is formed on the surface of other metal nanoparticles, which makes the Pd catalytic environmental improvement have a better material basis. Although the performance of the catalyst has been greatly improved in recent years, the core element is still an expensive metal such as Pd, Au, Ir and Ru. In addition, carbon black is still the most widely used electrocatalyst carrier; however, there are many reports that under relatively harsh operating conditions, the carbon carrier is corroded by electrochemical oxidation, which leads to the aggregation of noble metals and the separation of the carbon carrier, resulting in performance degradation. Therefore, it is of great significance to provide a high-efficiency, stable and low-cost cathode electrocatalyst. SUMMARY

[0005] The purpose of the present application is to overcome the problems existing in the prior art, and to provide a titanium nitride nickel-based palladium catalyst and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned object, the present application provides the following technical solutions.

[0007] The present application provides a preparation method of a titanium nickel nitride-based palladium catalyst, comprising the following steps:

[0008] (1) mixing titanium tetrachloride, nickel acetate tetrahydrate and ethanol under an ammonia atmosphere to obtain a complex powder;

[0009] (2) performing a nitriding reaction on the complex powder under an ammonia atmosphere to obtain titanium nickel nitride nanoparticles;

[0010] (3) mixing the titanium nickel nitride nanoparticles, a palladium chloride solution, water and a potassium borohydride solution to obtain the titanium nickel nitride-based palladium catalyst.

[0011] Preferably, the mass-volume ratio of the titanium tetrachloride, the nickel acetate tetrahydrate and the ethanol in step (1) is 0.5-1.5 mL: 0.08-0.16 g: 25-35 mL.

[0012] Preferably, the ammonia gas atmosphere in step (1) has an inlet rate of 25-35 sccm, the reaction has a temperature of 20-30℃, and the reaction has a time of 25-35 min.

[0013] Preferably, the ammonia gas atmosphere in step (2) has an inlet rate of 45-55 sccm, the nitriding reaction has a temperature of 750-850℃, and the nitriding reaction has a time of 2-3 h.

[0014] Preferably, the palladium chloride solution in step (3) has a concentration of 3-7 mmol / L, and the potassium borohydride solution has a concentration of 1.5-2 mg / mL.

[0015] Preferably, the mass-volume ratio of the titanium nickel nitride nanoparticles, the palladium chloride solution and the water in step (3) is 95-105 mg: 0.1-20 mL: 195-205 mL.

[0016] The volume ratio of the palladium chloride solution and the potassium borohydride solution is 1: 1.5-2.0.

[0017] Preferably, the reaction in step (3) has a temperature of 20-30℃, and the reaction has a time of 0.5-1 h.

[0018] The present application also provides a titanium nickel nitride-based palladium catalyst obtained by the preparation method.

[0019] The present application also provides an application of the titanium nickel nitride-based palladium catalyst in a catalytic reduction process for treating pollutants.

[0020] The present application has the following beneficial effects:

[0021] The application provides a preparation method of a titanium nickel nitride-based palladium catalyst, comprising the following steps: mixing titanium tetrachloride, nickel acetate tetrahydrate and ethanol under an ammonia atmosphere, and performing a reaction to obtain a complex powder; performing a nitriding reaction on the complex powder under an ammonia atmosphere to obtain titanium nickel nitride nanoparticles; mixing the titanium nickel nitride nanoparticles, a chloropalladic acid solution, water and a potassium borohydride solution, and performing a reaction to obtain the titanium nickel nitride-based palladium catalyst. The catalyst has a high specific surface area and is composed of two parts, namely a titanium nickel nitride nanoparticle carrier and a supported Pd nanocluster. Among them, nickel atoms are doped between the titanium nitride crystal lattices. The Pd nanocluster is supported on the surface of the TiNiN carrier, and by adjusting the loading amount of Pd atoms, the high efficiency and high selectivity of the catalyst for various environmental hydrogenation catalytic processes can be realized.

[0022] When the mass fraction of Pd is 0.5%, the catalytic activity of the Pd / TiNiN nanocatalyst for 4-chlorophenol reaches a similar level to that of Au@Pd nanowires (a layer of Pd monatomic layer is supported on the surface of gold particles), and the Pd / TiNiN nanocatalyst can be used as a superior substitute for a noble metal nanocatalyst carrier; when the mass fraction of Pd is adjusted to 0.05%, the catalytic activity and selectivity of the Pd / TiNiN catalyst for 4-nitrochlorobenzene are equivalent to those of Au@Pd nanowires. When the mass fraction of Pd reaches 0.5%, the Pd / TiNiN nanocatalyst can also realize efficient and selective hydrogenation of phenol, and can efficiently convert phenol into cyclohexanone, and the conversion selectivity is greater than 99.5%, which is much higher than that of the catalysts reported in the prior art.

[0023] The catalytic activity of the Pd / TiNiN nanocatalyst is only reduced by 28% after five repeated experiments, and the selectivity does not decrease obviously, which shows good activity and stability. Theoretical analysis shows that the promotion of TiNiN comes from the change of the d-band electronic state of Pd, which reduces the desorption energy of water on the Pd site to accommodate the reactants, and is also beneficial to the desorption and update of the reaction products on the Pd site.

[0024] The catalyst combines the advantages of high activity of Pd and low cost and high stability of TiNiN. Among transition metal nitrides, titanium nitride (TiN) can improve the dispersion of Pd and optimize the electronic state of Pd, and is a very promising Pd carrier, which can improve the performance of the catalyst in the key step of treating halogenated pollutants in wastewater, i.e., hydrogenation dehalogenation. The doping of Ni can further improve the performance of the Pd / TiNiN catalyst in hydrogenation dehalogenation, and the catalytic activity is similar to that of Au@Pd nanowires, which can be used as a substitute for a noble metal carrier in the future.

[0025] The nano catalyst is designed by using a second metal to dope titanium nitride to load Pd nano clusters for the first time, the nano catalyst has high catalytic activity and high selectivity in various environmental hydrogenation catalytic reactions, and can provide a new development idea for the development of the field of nano science and technology. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figures are characterization maps of Pd / TiNiN (mass fraction of palladium is 3%) and Pd / TiN (mass fraction of palladium is 3%) in Example 1; wherein a is a TEM characterization map of Pd / TiN (mass fraction of palladium is 3%), b is a SEM characterization map of Pd / TiN (mass fraction of palladium is 3%), c is a TEM characterization map of Pd / TiNiN (mass fraction of palladium is 3%), d is a SEM characterization map of Pd / TiNiN (mass fraction of palladium is 3%), e is a lattice spacing measurement characterization map of Pd nanoparticles in Pd / TiNiN material, and f is a lattice spacing measurement characterization map of TiNiN in Pd / TiNiN material;

[0027] Figure 2 The figures are TEM characterization maps of different catalysts in Example 1; wherein a is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 0.2%, b is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 0.5%, c is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 1%, d is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 3%, e is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 5%, f is a TEM characterization map of Pd / TiNiN with a mass fraction of palladium of 10%, g is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 0.2%, h is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 0.5%, i is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 1%, j is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 3%, k is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 5%, and l is a TEM characterization map of Pd / TiN with a mass fraction of palladium of 10%;

[0028] Figure 3EDS-MAPPING analysis chart of Pd / TiNiN with 0.2% mass fraction of palladium in Example 1; wherein, a is the EDS element characterization chart of Pd / TiNiN with 0.2% mass fraction of palladium, b is the HAADF / STEM characterization chart of Pd / TiNiN with 0.2% mass fraction of palladium, c is the EDS element mapping chart of Ni in Pd / TiNiN nanoparticles with 0.2% mass fraction of palladium, d is the EDS element mapping chart of N in Pd / TiNiN nanoparticles with 0.2% mass fraction of palladium, e is the EDS element mapping chart of Pd in Pd / TiNiN nanoparticles with 0.2% mass fraction of palladium, f is the EDS element mapping chart of Ti in Pd / TiNiN nanoparticles with 0.2% mass fraction of palladium;

[0029] Figure 4 XRD spectrum chart of TiN, Pd / TiN (10% mass fraction of palladium), TiNiN and Pd / TiNiN (10% mass fraction of palladium) in Example 1; (2θ (degree) - 2θ (°), Intensity / a.u. - intensity / a.u.);

[0030] Figure 5 Hydrodehalogenation performance test result chart of different catalysts in Example 1 (Reaction time (min) - reaction time (min), Conversion of 4-CP (%) - 4-CP conversion rate (%), Counterpart Pd catalyst - Pd catalyst comparison group); wherein, a is the conversion rate result chart of Pd / TiN catalyzed 4-CP hydrodehalogenation, b is the conversion rate result chart of Pd / TiNiN catalyzed 4-CP hydrodehalogenation, c is the conversion rate comparison result chart of Pd / TiNiN with 0.5% mass fraction of palladium, Pd / TiN with 0.5% mass fraction of palladium, and existing Pd / TiO2 with 0.5% mass fraction of palladium, PdNws, Pd / Al2O3 with 0.5% mass fraction of palladium, Au@Pd nanowire (5.0 nm), Au@Pd nanowire (13.0 nm) catalyzed 4-CP hydrodehalogenation, d is the kinetic curve chart of Pd / TiN catalyzed 4-CP hydrodehalogenation, e is the kinetic curve chart of Pd / TiNiN catalyzed 4-CP hydrodehalogenation, f is the kinetic curve comparison chart of Pd / TiNiN with 0.5% mass fraction of palladium, Pd / TiN with 0.5% mass fraction of palladium, and existing Pd / TiO2 with 0.5% mass fraction of palladium, PdNws, Pd / Al2O3 with 0.5% mass fraction of palladium, Au@Pd (5.0), Au@Pd (13.0) catalyzed 4-CP hydrodehalogenation, g is the comparison chart of first order rate constant of different catalysts;

[0031] Figure 6 The performance test results of phenol hydrogenation catalyzed by different catalysts in Example 1 are shown in the figure (Reaction time (min) - reaction time (min), Concentration (mmol / L) - reactant concentration (mmol / L), Distribution (%) - distribution (%)); wherein a is the conversion process figure of Pd / TiNiN with a mass fraction of 0.5% of palladium catalyzing phenol hydrogenation, b is the first order rate constant comparison figure of different catalysts catalyzing phenol hydrogenation, c is the product distribution figure of different catalysts catalyzing phenol hydrogenation;

[0032] Figure 7 The performance test results of 4-nitrochlorobenzene hydrogenation catalyzed by different catalysts in Example 1 are shown in the figure (Reaction time (min) - reaction time (min), Concentration (mmol / L) - reactant concentration (mmol / L), Distribution (%) - distribution (%)); wherein a is the conversion process figure of Pd / TiNiN with a mass fraction of 0.05% of palladium catalyzing 4-nitrochlorobenzene hydrogenation, b is the first order rate constant comparison figure of different catalysts catalyzing 4-nitrochlorobenzene hydrogenation, c is the product distribution figure of different catalysts catalyzing 4-nitrochlorobenzene hydrogenation;

[0033] Figure 8 The performance stability test figure of phenol hydrogenation catalyzed by Pd / TiNiN with a mass fraction of 0.5% of palladium in Example 1 is shown (Reaction time (min) - reaction time (min), Conversion of phenol (%) - conversion rate of phenol hydrogenation dehalogenation (%)); wherein a is the conversion rate result figure of Pd / TiNiN with a mass fraction of 0.5% of palladium catalyzing phenol hydrogenation dehalogenation repeated 5 times, b is the kinetic curve figure of Pd / TiNiN with a mass fraction of 0.5% of palladium catalyzing phenol hydrogenation dehalogenation repeated 5 times, c is the first order rate constant comparison figure of Pd / TiNiN with a mass fraction of 0.5% of palladium catalyzing phenol hydrogenation dehalogenation repeated 5 times. DETAILED DESCRIPTION

[0034] The present application provides a preparation method of titanium nickel-based palladium nitride catalyst, comprising the following steps:

[0035] (1) Under the atmosphere of ammonia, titanium tetrachloride, nickel acetate tetrahydrate and ethanol are mixed to obtain a complex powder by reaction;

[0036] (2) Under the atmosphere of ammonia, the complex powder is subjected to nitriding reaction to obtain titanium nickel nitride nanoparticles;

[0037] (3) mixing titanium nickel nitride nanoparticles, chloropalladic acid solution, water and potassium borohydride solution to obtain the titanium nickel nitride-based palladium catalyst.

[0038] In the present application, the mass-volume ratio of titanium tetrachloride, nickel acetate tetrahydrate and ethanol in step (1) is preferably 0.5-1.5 mL: 0.08-0.16 g: 25-35 mL, further preferably 0.7-1.3 mL: 0.1-0.15 g: 27-33 mL, and more preferably 0.8-1 mL: 0.12-0.13 g: 28-30 mL.

[0039] In the present application, step (1) is preferably mixing titanium tetrachloride, nickel acetate tetrahydrate and ethanol uniformly, then standing, and after standing, introducing ammonia gas under stirring to react.

[0040] In the present application, the standing time is preferably 1.5-2.5 h, further preferably 1.7-2.3 h, and more preferably 2-2.1 h; the stirring speed is preferably 1000-2000 r / min, further preferably 1500-1800 r / min, and more preferably 1600-1700 r / min; the ammonia gas atmosphere is preferably 25-35 sccm, further preferably 27-33 sccm, and more preferably 28-30 sccm; the reaction temperature is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-26℃; and the reaction time is preferably 25-35 min, further preferably 27-33 min, and more preferably 28-30 min.

[0041] In the present application, after step (1) is completed, the obtained precipitate is sequentially subjected to centrifugation, drying and grinding to obtain the complex powder.

[0042] In the present application, the centrifugation speed is preferably 4000-6000 r / min, further preferably 4400-5600 r / min, and more preferably 5000-5200 r / min; the centrifugation time is preferably 10-20 min, further preferably 12-18 min, and more preferably 15-16 min; the purpose of drying is to remove ethanol in the system; the drying temperature is preferably 80-90℃, further preferably 82-88℃, and more preferably 85-86℃; the drying vacuum degree is preferably -0.06 to -0.1 MPa, further preferably -0.07 to -0.09 MPa, and more preferably -0.075 to -0.08 MPa; and the drying time is preferably 10-15 h, further preferably 11-14 h, and more preferably 12-13 h.

[0043] In the present application, the feeding rate of the ammonia gas atmosphere in step (2) is preferably 45-55 sccm, further preferably 47-53 sccm, and more preferably 50-52 sccm; the nitriding reaction is preferably carried out in a tube furnace, the temperature of the nitriding reaction is preferably 750-850℃, further preferably 780-830℃, and more preferably 790-800℃; and the time of the nitriding reaction is preferably 2-3h, further preferably 2.2-2.8h, and more preferably 2.5-2.7h.

[0044] In the present application, after the nitriding reaction in step (2) is completed, argon is fed into the tube furnace, and the natural cooling is carried out to obtain the titanium nickel nitride nanoparticles.

[0045] In the present application, the target temperature of the natural cooling is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-26℃.

[0046] In the present application, the concentration of the chloropalladic acid solution in step (3) is preferably 3-7mmol / L, further preferably 4-6mmol / L, and more preferably 5-5.5mmol / L; and the concentration of the potassium borohydride solution is preferably 1.5-2mg / mL, further preferably 1.6-1.9mg / mL, and more preferably 1.7-1.8mg / mL.

[0047] In the present application, the mass-to-volume ratio of the titanium nickel nitride nanoparticles, the chloropalladic acid solution and water in step (3) is preferably 95-105mg:0.1-20mL:195-205mL, further preferably 98-103mg:0.5-15mL:197-203mL, and more preferably 100-101mg:3-10mL:199-200mL.

[0048] In the present application, the volume ratio of the chloropalladic acid solution to the potassium borohydride solution is preferably 1:1.5-2.0, further preferably 1:1.6-1.9, and more preferably 1:1.7-1.8.

[0049] In the present application, the mixing in step (3) is preferably that the titanium nickel nitride nanoparticles, the chloropalladic acid solution and water are first mixed to form a dispersion by ultrasonic treatment, and then the potassium borohydride solution is added dropwise into the dispersion under the conditions of ice-bath and stirring to carry out the reaction.

[0050] In the present application, the frequency of the ultrasonic is preferably 30-50 kHz, further preferably 35-45 kHz, and more preferably 37-40 kHz; the time of the ultrasonic is preferably 50-70 min, further preferably 55-65 min, and more preferably 60-63 min; the temperature of the ice bath is preferably -3-3℃, further preferably -2-2℃, and more preferably 0-1℃; the rotating speed of the stirring is preferably 1000-2000 r / min, further preferably 1500-1800 r / min, and more preferably 1600-1700 r / min; and the time of the stirring is preferably 25-35 min, further preferably 27-33 min, and more preferably 28-30 min.

[0051] In the present application, the temperature of the reaction in step (3) is preferably 20-30℃, further preferably 22-28℃, and more preferably 25-26℃; and the time of the reaction is preferably 0.5-1 h, further preferably 0.6-0.9 h, and more preferably 0.7-0.8 h.

[0052] In the present application, after the reaction in step (3) is completed, the obtained system is centrifuged to collect the composite material, and then the composite material is sequentially washed with water and dried to obtain the titanium nickel-based palladium nitride catalyst.

[0053] In the present application, the rotating speed of the centrifugation is preferably 4500-5500 r / min, further preferably 4700-5300 r / min, and more preferably 5000-5200 r / min; the time of the centrifugation is preferably 10-20 min, further preferably 12-18 min, and more preferably 14-16 min; the number of water washing is preferably ≥2 times, further preferably ≥3 times, and more preferably ≥4 times; the temperature of the drying is preferably 80-90℃, further preferably 82-88℃, and more preferably 85-86℃; the vacuum degree of the drying is preferably -0.06--0.1 MPa, further preferably -0.07--0.09 MPa, and more preferably -0.075--0.08 MPa; and the time of the drying is preferably 10-15 h, further preferably 11-14 h, and more preferably 12-13 h.

[0054] The present application also provides the titanium nickel-based palladium nitride catalyst prepared by the preparation method.

[0055] The present application also provides the application of the titanium nickel-based palladium nitride catalyst in the catalytic reduction process for treating pollutants.

[0056] The technical solutions provided by the present application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0057] Example 1

[0058] A mixture of 1 mL titanium tetrachloride, 0.119 g nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O) and 30 mL ethanol was stirred for 2 h, then ammonia was introduced (flow rate of 30 seem) at a stirring speed of 1600 r / min, and the reaction was carried out at 25°C for 30 min. After the reaction, the obtained precipitate was centrifuged at a speed of 5000 r / min for 15 min, then dried at a temperature of 85°C and a vacuum degree of -0.08 MPa for 12 h, and finally ground to obtain a complex powder. The complex powder was placed in a tube furnace, ammonia was introduced (flow rate of 50 seem), and the nitriding reaction was carried out at 800°C for 2.5 h. After the reaction, argon was introduced into the tube furnace, and the system was naturally cooled to 25°C to obtain titanium nickel nitride nanoparticles (labeled as TiNiN).

[0059] A mixture of 100 mg titanium nickel nitride nanoparticles, 6 mL palladium chloride acid solution with a concentration of 5 mmol / L and 200 mL water was ultrasonically dispersed at a frequency of 40 kHz for 60 min to form a dispersion, then stirred at 0°C in an ice bath and a stirring speed of 1600 r / min for 30 min. Then, 10 mL potassium borohydride solution with a concentration of 1.7 mg / mL was added dropwise into the dispersion, and the reaction was carried out at 25°C for 1 h after the addition was completed. The obtained system was centrifuged at a speed of 5000 r / min for 15 min, and the composite material was collected. The composite material was washed with water twice, and dried at a temperature of 85°C and a vacuum degree of -0.08 MPa for 12 h to obtain the titanium nickel nitride-based palladium catalyst (labeled as Pd / TiNiN). The mass fraction of palladium in the titanium nickel nitride-based palladium catalyst was 3%.

[0060] While the other conditions were controlled, the amounts of the palladium chloride acid solution and the potassium borohydride solution were changed to obtain titanium nickel nitride-based palladium catalysts with mass fractions of palladium of 0.05%, 0.1%, 0.2%, 0.5%, 1%, 5% and 10%, respectively. The specific amounts of the palladium chloride acid solution and the potassium borohydride solution in different titanium nickel nitride-based palladium catalysts are shown in Table 1.

[0061] Table 1 Specific amounts of palladium chloride acid solution and potassium borohydride solution in different titanium nickel nitride-based palladium catalysts

[0062] Mass fraction of palladium (%) Volume of chloropalladic acid solution (mL) Volume of potassium borohydride solution (mL) 0.05 0.1 0.18 0.1 0.2 0.32 0.2 0.4 0.68 0.5 1 1.8 1 2 3.5 5 10 17 10 20 34

[0063] The comparative example of the present embodiment is set, and other conditions are controlled to be unchanged, and no nickel acetate tetrahydrate is added to obtain titanium nitride nanoparticles (marked as TiN); correspondingly, the titanium nickel nitride nanoparticles are replaced by titanium nitride nanoparticles to obtain a palladium-based catalyst (marked as Pd / TiN), wherein the mass fraction of palladium is 0.05%, 0.1%, 0.2%, 0.5%, 1%, 3%, 5%, and 10% respectively.

[0064] The Pd / TiNiN (the mass fraction of palladium is 3%) and Pd / TiN (the mass fraction of palladium is 3%) obtained in the present embodiment are characterized to obtain the characterization graphs of the Pd / TiNiN (the mass fraction of palladium is 3%) and Pd / TiN (the mass fraction of palladium is 3%) in the present embodiment, as shown in Figure 1 Figure 1 In the figure, a is the TEM characterization graph of Pd / TiN (the mass fraction of palladium is 3%), b is the SEM characterization graph of Pd / TiN (the mass fraction of palladium is 3%), c is the TEM characterization graph of Pd / TiNiN (the mass fraction of palladium is 3%), d is the SEM characterization graph of Pd / TiNiN (the mass fraction of palladium is 3%), e is the lattice spacing measurement characterization graph of Pd nanoparticles in the Pd / TiNiN material, and f is the lattice spacing measurement characterization graph of TiNiN in the Pd / TiNiN material.

[0065] As can be seen from Figure 1 , the TiNiN and TiN carrier morphology is a porous sheet structure, and the Pd nanoparticles are uniformly distributed on the surface of the TiNiN and TiN carrier. The lattice spacing of the Pd nanoparticles is 0.234 nm, which is consistent with the lattice parameter of the Pd(111) crystal plane, indicating that the main exposed crystal plane of the Pd nanoparticles is the Pd(111) crystal plane. Related studies have shown that the Pd(111) crystal plane is the crystal plane with the highest hydrogenation dechlorination activity of Pd. Therefore, the Pd / TiNiN and Pd / TiN synthesized by this loading method have good catalytic activity in the hydrogenation dechlorination reaction process. In addition to the Pd lattice stripes, another obvious lattice can be observed, and the measured lattice spacing is 0.256 nm, which corresponds to the (111) plane of TiN (fcc), further proving that the TiN crystal phase is formed after high-temperature nitriding treatment. In summary, it can be preliminarily confirmed that the Pd nanoparticles are successfully loaded on the surface of the TiNiN and TiN carrier according to the expectation, the Pd nanoparticles have the Pd(111) crystal plane as the main exposed plane, and the Pd nanoparticles are uniformly distributed on the surface of the carrier.

[0066] The Pd / TiNiN with the mass fraction of palladium of 0.2%, 0.5%, 1%, 3%, 5%, and 10% and the Pd / TiN with the mass fraction of palladium of 0.2%, 0.5%, 1%, 3%, 5%, and 10% in the present embodiment are respectively subjected to TEM characterization to obtain the TEM characterization graphs of different catalysts in the present embodiment, as shown in​Figure 2 Figure 2 Figure 1 shows TEM images of Pd / TiNiN and Pd / TiN, wherein a is a TEM image of Pd / TiNiN with a mass fraction of 0.2% of palladium, b is a TEM image of Pd / TiNiN with a mass fraction of 0.5% of palladium, c is a TEM image of Pd / TiNiN with a mass fraction of 1% of palladium, d is a TEM image of Pd / TiNiN with a mass fraction of 3% of palladium, e is a TEM image of Pd / TiNiN with a mass fraction of 5% of palladium, f is a TEM image of Pd / TiNiN with a mass fraction of 10% of palladium, g is a TEM image of Pd / TiN with a mass fraction of 0.2% of palladium, h is a TEM image of Pd / TiN with a mass fraction of 0.5% of palladium, i is a TEM image of Pd / TiN with a mass fraction of 1% of palladium, j is a TEM image of Pd / TiN with a mass fraction of 3% of palladium, k is a TEM image of Pd / TiN with a mass fraction of 5% of palladium, and l is a TEM image of Pd / TiN with a mass fraction of 10% of palladium.

[0067] Figure 2 shows EDS-MAPPING images of Pd / TiNiN and Pd / TiN, wherein a is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, b is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, c is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, d is an EDS-MAPPING image of Pd / TiN with a mass fraction of 0.2% of palladium, e is an EDS-MAPPING image of Pd / TiN with a mass fraction of 0.2% of palladium, f is an EDS-MAPPING image of Pd / TiN with a mass fraction of 0.2% of palladium, g is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, h is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, i is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, j is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, k is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, and l is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium. Figure 2 As shown in Figure 2, the Pd nanoparticles are uniformly distributed on the carrier, further proving that the morphology of the carrier is a porous sheet structure. With the change of the mass fraction of palladium, the particle size of the Pd nanoparticles on the surface of the TiNiN and TiN carrier changes accordingly. When the mass fraction of palladium is 0.2%, the particle size of the Pd nanoparticles is relatively small, about 2 nm. When the mass fraction is increased to 3%, the particle size of the Pd nanoparticles on the surface of the carrier is significantly increased, about 5 nm. With the further increase of the mass fraction, the particle size of the Pd nanoparticles on the surface of the carrier does not appear to be significantly increased, but the distribution density on the carrier is significantly increased.

[0068] Figure 3 shows EDS-MAPPING images of Pd / TiNiN with a mass fraction of 0.2% of palladium, wherein a is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, b is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, c is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, d is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, e is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium, and f is an EDS-MAPPING image of Pd / TiNiN with a mass fraction of 0.2% of palladium. Figure 3 Figure 3 Figure 4 shows EDS-MAPPING images of Pd / TiNiN with a mass fraction of 0.2% of palladium, wherein a is an EDS element image of Pd / TiNiN with a mass fraction of 0.2% of palladium, b is an HAADF / STEM image of Pd / TiNiN with a mass fraction of 0.2% of palladium, c is an EDS element mapping image of Ni in Pd / TiNiN nanoparticles with a mass fraction of 0.2% of palladium, d is an EDS element mapping image of N in Pd / TiNiN nanoparticles with a mass fraction of 0.2% of palladium, e is an EDS element mapping image of Pd in Pd / TiNiN nanoparticles with a mass fraction of 0.2% of palladium, and f is an EDS element mapping image of Ti in Pd / TiNiN nanoparticles with a mass fraction of 0.2% of palladium.​​

[0069] As can be seen from Figure 3 , Ti, Ni and N are uniformly distributed on the support, and no Ni-rich region is observed, indicating that most of the added Ni has been doped into TiN. The signal of Pd component is continuously and uniformly distributed in the TiNiN support, indicating that Pd is uniformly loaded on the surface of TiNiN support, and TiNiN is a good support for fixing Pd.

[0070] The TiN, Pd / TiN (mass fraction of Pd is 10%), TiNiN and Pd / TiNiN (mass fraction of Pd is 10%) prepared in this example were subjected to X-ray diffraction analysis, and the XRD spectra of TiN, Pd / TiN (mass fraction of Pd is 10%), TiNiN and Pd / TiNiN (mass fraction of Pd is 10%) in this example were obtained, as shown in Figure 4 .

[0071] As can be seen from Figure 4 , after high-temperature nitriding treatment, the diffraction peaks of the nanoparticles show the characteristic peaks of face-centered cubic TiN phase (JCPDS 38-1420), and no other characteristic peaks are detected, indicating that all the complex precursors are converted into TiN nanostructures. For TiNiN nanoparticles, the diffraction peak positions are almost the same as those of TiN nanoparticles, indicating that Ni atoms enter the TiN lattice by replacing Ti atoms. However, a significant peak shift can be observed in the XRD spectrum of TiNiN. Since Ni (0.056 nm) has a smaller ionic radius than Ti (0.067 nm), lattice compression may occur. Notably, there are also characteristic peaks consistent with Ni phase (JCPDS 04-0850) in the diffraction peaks of TiNiN nanoparticles, indicating that the added Ni atoms do not completely participate in the TiN lattice, indicating that part of the added Ni is reduced to Ni (0) nanoparticles and exists on the surface of TiNiN nanoparticles. The loading process of Pd, including the reduction process of KBH4, has little effect on the XRD spectra of TiN and TiNiN, indicating good chemical stability of the support. When the mass fraction of Pd is high enough, for example, 3% or more, the XRD diffraction peaks of Pd (0) can also be clearly identified.

[0072] Single-layer Pd was loaded on the surface of 5.0 nm Au and 13.0 nm Au nanoparticles to synthesize Au@Pd (5 nm) and Au@Pd (13 nm).

[0073] The Pd / TiNiN with the mass fraction of palladium of 0.2%, 0.5%, 1%, 3%, 5%, 10% and the Pd / TiN with the mass fraction of palladium of 0.2%, 0.5%, 1%, 3%, 5%, 10% and other existing catalysts in the embodiment are respectively subjected to the 4-CP catalytic hydrogenation dehalogenation performance test, and a graph of the hydrogenation dehalogenation performance test results of different catalysts in the embodiment is obtained, as shown in Figure 5 In the graph, Figure 5 , a is a conversion rate result graph of Pd / TiN catalytic 4-CP hydrogenation dehalogenation, b is a conversion rate result graph of Pd / TiNiN catalytic 4-CP hydrogenation dehalogenation, c is a conversion rate comparison result graph of Pd / TiNiN with the mass fraction of palladium of 0.5%, Pd / TiN with the mass fraction of palladium of 0.5% and existing Pd / TiO2 with the mass fraction of palladium of 0.5%, PdNws, Pd / Al2O3 with the mass fraction of palladium of 0.5%, Au@Pd nanowire (5.0 nm) and Au@Pd nanowire (13.0 nm) catalytic 4-CP hydrogenation dehalogenation, d is a kinetic curve graph of Pd / TiN catalytic 4-CP hydrogenation dehalogenation, e is a kinetic curve graph of Pd / TiNiN catalytic 4-CP hydrogenation dehalogenation, f is a kinetic curve comparison graph of Pd / TiNiN with the mass fraction of palladium of 0.5%, Pd / TiN with the mass fraction of palladium of 0.5% and existing Pd / TiO2 with the mass fraction of palladium of 0.5%, PdNws, Pd / Al2O3 with the mass fraction of palladium of 0.5%, Au@Pd (5.0) and Au@Pd (13.0) catalytic 4-CP hydrogenation dehalogenation, and g is a comparison graph of the first order rate constant of different catalysts.

[0074] From Figure 5As can be seen from a ~ c, the catalytic performance of the synthesized Pd / TiNiN catalyst in the key step of C-Cl bond cleavage in the removal of chlorinated organic pollutants was preliminarily evaluated by the hydrogenation dehalogenation reaction (HDC) of 4-CP. The Pd / TiN and Pd / TiNiN catalysts with different Pd mass fractions all had catalytic activity in the reduction treatment of 4-CP, but the activity was related to the Pd mass fraction. The Pd / TiN with the lowest Pd mass fraction of 0.2% had a 4-CP conversion rate of 76.3% after 40 min. However, when the Pd mass fraction increased to 0.5%, the activity of the Pd sites was significantly improved, and the Pd / TiN had satisfactory activity, and 4-CP could be almost quantitatively converted into phenol within 20 min. When the Pd mass fraction increased to 1.0%, 3.0% and 5.0% respectively, the 4-CP conversion rate of the catalysts slightly decreased, and reached about 90% at the end of the reaction within 20 min. When the Pd mass fraction increased to 10%, the reduction rate of 4-CP further slowed down, and most of the 4-CP was removed (>95%) after about 40 min. With the change of the Pd carrier from TiN to TiNiN, the Ni doping further promoted the activity of Pd in the HDC process. The 4-CP conversion rate of all Pd / TiNiN catalysts was higher than that of the Pd / TiN catalyst with the same Pd loading, and the 4-CP conversion rate after 10 min was Pd / TiNiN(0.5%) > Pd / TiNiN(1.0%) ~ Pd / TiNiN(3.0%) ~ Pd / TiNiN(5.0%) > Pd / TiNiN(10.0%) > Pd / TiNiN(0.2%). Most notably, the Pd / TiNiN(0.5%) required only 10 min to completely reduce 4-CP, which was comparable to the reaction rate of the Au@Pd nanowire we synthesized before under the same reaction conditions, which indicated that the designed Pd catalyst by selecting the catalyst carrier was a very forward-looking thing, and the Pd / TiNiN at least had the potential to replace the high-activity high-cost Au@Pd in the environmental catalytic removal of halogenated pollutants.

[0075] From Figure 5It can also be obtained in d~g that Pd / TiN, Pd / TiNiN and Au@Pd nanowires exhibit high stability in the HDC reaction, and the entire reaction curve conforms to the first-order kinetic model. The rate constant of Pd / TiN is the same as the trend observed on the results graph of conversion rate, in turn Pd / TiN(0.5%)>Pd / TiN(1.0%)~Pd / TiN(3.0%)~Pd / TiN(5.0%)>Pd / TiN(10.0%)>Pd / TiN(0.2%), and the same is true for Pd / TiNiN. The rate constants of Pd / TiN(0.5%) and Pd / TiNiN(0.5%) are 0.24±0.02 and 0.45±0.03 min -1 , respectively. These values are close to the activities of Au@Pd(5.0nm) and Au@Pd(13.0nm), which are 0.46±0.01 and 0.21±0.03 min -1 , respectively. The activities of Pd / TiNiN(0.5%) and Au@Pd(5.0nm) are almost the same, which are about 15~30 times of the activities of PdNWs or Pd / TiO2 and Pd / Al2O3, fully proving that the promotion of TiN to Pd activity is good, and the doping of Ni in TiN can further improve the Pd activity. In addition, TiNiN has the same promotion effect as Au, but its price is reduced by more than 1000 times, which shows the possibility of improving the practicability of TiNiN supported Pd catalyst, which can be loaded into a water treatment column as a heterogeneous catalyst for actual industrial halogenated wastewater treatment process.

[0076] The performance test results of different catalysts in the catalytic hydrogenation of phenol in the present embodiment are obtained by performing performance tests of the catalytic hydrogenation of phenol on Pd / TiNiN with mass fractions of 0.2%, 0.5%, 1%, 3%, 5%, 10% of palladium and Pd / TiN with a mass fraction of 0.5% of palladium and other existing catalysts in the present embodiment, as shown in Figure 6 . Figure 6 In the figures, a is the conversion process graph of Pd / TiNiN with a mass fraction of 0.5% of palladium in the catalytic hydrogenation of phenol, b is the comparison graph of the first-order rate constant of different catalysts in the catalytic hydrogenation of phenol, and c is the product distribution graph of different catalysts in the catalytic hydrogenation of phenol.

[0077] From Figure 6As can be seen from the figure, all Pd / TiNiN catalysts have catalytic activity for phenol, and the catalytic activity varies with the mass fraction of Pd. The mass fraction of Pd is the lowest at 0.2%, and the conversion rate of phenol reaches 76.4% after 150 min. When the mass fraction of Pd increases to 0.5%, the activity of Pd sites is significantly improved, and Pd / TiNiN has satisfactory activity in the process, and phenol can be almost quantitatively converted into cyclohexanone within 150 min, and the conversion selectivity of cyclohexanone is greater than 99.9%. The conversion rates of phenol of all Pd / TiNiN catalysts after 150 min are Pd / TiNiN(0.5%) > Pd / TiNiN(1.0%) > Pd / TiNiN(3.0%) > Pd / TiNiN(5.0%) > Pd / TiNiN(10.0%) > Pd / TiNiN(0.2%) in turn. The generated product of the catalytic hydrogenation reaction of phenol on all Pd / TiNiN catalysts is cyclohexanone, and no cyclohexanol is generated. The catalytic hydrogenation reaction of phenol on Pd / TiNiN catalysts has high activity and high selectivity, and shows the potential of Pd / TiNiN catalysts for industrial organic wastewater treatment. In addition, the catalytic activity of Pd / TiN(0.5%) for the catalytic hydrogenation reaction of phenol is lower than that of Pd / TiNiN(0.5%), which indicates that the doping of Ni can significantly improve the reaction activity of Pd on the surface of the carrier. At the same time, the catalytic activity of Pd / TiN(0.5%) is much higher than that of Pd / TiO2(0.5%), Pd / C and Pd / Al2O3, which further indicates the superiority of the TiN catalyst carrier in improving the activity of Pd. The catalytic activity of Pd / TiNiN(0.5%) is about 20-100 times that of Pd / C or Pd / TiO2 and Pd / Al2O3. Pd / Al2O3 has no obvious activity for the catalytic conversion reaction of phenol hydrogenation. The selectivity of Pd / TiNiN(0.5%) and Pd / TiN(0.5%) in the reaction catalysis process is equivalent, and both can convert the reactants into cyclohexanone without generating cyclohexanol. However, Pd / C and Pd / TiO2(0.5%) have different proportions of cyclohexanol in the catalytic reaction products, and the selectivity of the reaction is lower than that of Pd / TiNiN(0.5%) and Pd / TiN(0.5%). This comparison shows that the TiN carrier plays a positive role in the selectivity of the product, which is beneficial to the generation of cyclohexanone in the catalytic hydrogenation reaction of phenol.

[0078] The Pd / TiNiN catalysts with the mass fraction of Pd being 0.05%, 0.1%, 0.2%, 0.5% and 1% and the Pd / TiN catalyst with the mass fraction of Pd being 0.05% and other existing catalysts in this embodiment were subjected to 4-nitrochlorobenzene catalytic hydrogenation performance test, and the performance test results of the different catalysts in this embodiment for the catalytic hydrogenation of 4-nitrochlorobenzene were obtained, as shown in Figure 7 ​Figure 7 Figure 2a is a conversion process diagram of Pd / TiNiN catalysis of 4-nitrochlorobenzene hydrogenation, Figure 2b is a comparison diagram of first order rate constant of different catalysts for catalytic hydrogenation of 4-nitrochlorobenzene, and Figure 2c is a product distribution diagram of different catalysts for catalytic hydrogenation of 4-nitrochlorobenzene.

[0079] From Figure 7 As can be seen from Figure 2a, all Pd / TiNiN catalysts have catalytic activity for 4-nitrochlorobenzene, and the catalytic activity varies with the mass fraction of Pd. When the mass fraction of Pd is 0.05%, the activity of Pd sites is significantly improved. In this process, Pd / TiNiN has satisfactory activity, and 4-nitrochlorobenzene can be almost quantitatively converted into 4-chloroaniline in 120 min, and the selectivity of 4-chloroaniline is as high as 98.8%. The conversion rates of all Pd / TiNiN catalysts for 4-nitrochlorobenzene after 150 min are Pd / TiNiN(0.05%) > Pd / TiNiN(0.1%) > Pd / TiNiN(0.2%) > Pd / TiNiN(0.5%) > Pd / TiNiN(1%). It can be observed from the comparison of experimental data that the optimal mass fraction of Pd on the surface of TiNiN is different in different hydrogenation catalytic processes of reactants. It can be inferred that the active Pd sites required for different catalytic hydrogenation reactions are different. It is worth noting that the composition of Pd sites on the surface of TiNiN can be controlled by controlling the mass fraction of Pd in the catalyst, so that Pd / TiNiN catalysts can be efficiently and selectively applied to various environmental catalytic hydrogenation reactions. Pd / TiNiN catalyst is a potential environmental organic wastewater treatment catalyst, and its high efficiency and high selectivity are expected to make it an extremely cost-effective industrial catalyst. In addition, the catalytic activity of Pd / TiNiN(0.05%) is slightly higher than that of Pd / TiN(0.05%), and both can remove 4-nitrochlorobenzene in 120 min, and the activity of the two catalysts is higher than that of Au@Pd(13 nm). This phenomenon shows that TiN can significantly improve the activity of Pd monatomic, and the activity improvement capability of TiN for surface Pd monatomic reaches or slightly exceeds the Au level, which is a choice for replacing Au as a nanocatalyst carrier in the future. The catalytic activity of Pd / TiNiN(0.05%) is about 3-10 times that of Pd / TiO2 and Pd / C or Pd / Al2O3. The catalytic selectivity of Pd / TiNiN(0.05%) and Pd / TiN(0.05%) is better than that of Au@Pd, and the selectivity of 4-chloroaniline is greater than 95%. The selectivity of Pd / TiNiN(0.05%) and Pd / TiN(0.05%) is much higher than that of Pd / TiO2(0.5%), Pd / C, and Pd / Al2O3.

[0080] The Pd / TiNiN with the mass fraction of 0.5% of palladium in the embodiment was subjected to the catalytic phenol hydrogenation performance test, and a performance stability test diagram of the Pd / TiNiN with the mass fraction of 0.5% of palladium in the embodiment for catalytic phenol hydrogenation was obtained, as shown in Figure 8 Fig. 1; wherein a is a conversion rate result diagram of the Pd / TiNiN with the mass fraction of 0.5% of palladium for catalytic phenol hydrogenation dehalogenation repeated for 5 times, b is a kinetic curve diagram of the Pd / TiNiN with the mass fraction of 0.5% of palladium for catalytic phenol hydrogenation dehalogenation repeated for 5 times, and c is a first-order rate constant comparison diagram of the Pd / TiNiN with the mass fraction of 0.5% of palladium for catalytic phenol hydrogenation dehalogenation repeated for 5 times.

[0081] It can be seen from Figure 8 that the catalytic activity of the Pd / TiNiN nano-catalyst is only reduced by 28% after repeated experiments for 5 times, and the selectivity does not decrease obviously, which shows good activity and stability. Theoretical analysis shows that the promotion of TiNiN comes from changing the d-band electronic state of Pd, which reduces the desorption energy of water on the Pd site to accommodate the reactants, and is also beneficial to the desorption and update of the reaction products on the Pd site.

[0082] Example 2

[0083] 0.7 mL of titanium tetrachloride, 0.1 g of nickel acetate tetrahydrate (Ni(CH3COO)2·4H2O), and 27 mL of ethanol were uniformly mixed, and then placed for 1.7 h. Then, ammonia gas was introduced (inlet rate of 25 sccm) under the condition that the stirring speed was 1800 r / min, and the reaction was carried out at 28℃ for 27 min. After the reaction was completed, the obtained precipitate was centrifuged at a speed of 5200 r / min for 12 min, and then dried at a temperature of 90℃ under a vacuum degree of -0.06 MPa for 10 h. Finally, the complex powder was obtained by grinding. The complex powder was placed in a tube furnace, ammonia gas was introduced (inlet rate of 47 sccm), and the nitriding reaction was carried out at 830℃ for 2.2 h. After the reaction was completed, argon gas was introduced into the tube furnace, and the temperature was naturally cooled to 30℃. Thus, titanium nickel nitride nanoparticles (labeled as TiNiN) were obtained.

[0084] The titanium nickel nitride nanoparticles, 0.1 mL of chloropalladic acid solution with a concentration of 4 mmol / L and 200 mL of water were mixed, and a dispersion was formed by ultrasonic treatment at a frequency of 50 kHz for 50 min, and then stirred at a stirring speed of 1500 r / min in an ice bath at 1 ℃ for 33 min. Then, 0.18 mL of potassium borohydride solution with a concentration of 1.6 mg / mL was added dropwise into the dispersion, and after the addition was completed, the resulting system was reacted at 28 ℃ for 0.7 h. The resulting system was centrifuged at a speed of 4500 r / min for 18 min, and the composite material was collected. Then, the composite material was washed with water for 3 times, and dried at a temperature of 90 ℃ and a vacuum degree of -0.06 MPa for 10 h to obtain the titanium nickel nitride-based palladium catalyst (labeled as Pd / TiNiN), wherein the mass fraction of palladium in the titanium nickel nitride-based palladium catalyst is 0.05%.

[0085] The titanium nickel nitride-based palladium catalyst obtained in the example can quantitatively convert 4-nitrochlorobenzene into 4-chloroaniline within 120 min, and the selectivity of 4-chloroaniline is as high as 98.8%.

[0086] Example 3

[0087] The titanium nickel nitride nanoparticles, 0.1 mL of chloropalladic acid solution with a concentration of 4 mmol / L and 200 mL of water were mixed, and a dispersion was formed by ultrasonic treatment at a frequency of 50 kHz for 50 min, and then stirred at a stirring speed of 1500 r / min in an ice bath at 1 ℃ for 33 min. Then, 0.18 mL of potassium borohydride solution with a concentration of 1.6 mg / mL was added dropwise into the dispersion, and after the addition was completed, the resulting system was reacted at 28 ℃ for 0.7 h. The resulting system was centrifuged at a speed of 4500 r / min for 18 min, and the composite material was collected. Then, the composite material was washed with water for 3 times, and dried at a temperature of 90 ℃ and a vacuum degree of -0.06 MPa for 10 h to obtain the titanium nickel nitride-based palladium catalyst (labeled as Pd / TiNiN), wherein the mass fraction of palladium in the titanium nickel nitride-based palladium catalyst is 0.05%.

[0088] 100 mg of titanium nickel nitride nanoparticles, 1 mL of a chloropalladic acid solution with a concentration of 6 mmol / L, and 200 mL of water are mixed, ultrasonic waves are applied at a frequency of 35 kHz for 65 min to form a dispersion, then 1.8 mL of a potassium borohydride solution with a concentration of 2 mg / mL is added dropwise to the dispersion under stirring at a stirring speed of 1000 r / min in an ice bath at -2 ℃, and after the addition is completed, the obtained system is reacted at 20 ℃ for 1 h, the obtained system is centrifuged at a speed of 5500 r / min for 10 min, and the composite material is collected; then the composite material is washed with water twice, and dried at a temperature of 80 ℃ and a vacuum degree of -0.07 MPa for 15 h to obtain the titanium nickel nitride-based palladium catalyst (labeled as Pd / TiNiN), wherein the mass fraction of palladium in the titanium nickel nitride-based palladium catalyst is 0.5%.

[0089] The titanium nickel nitride-based palladium catalyst obtained in the example can quantitatively convert phenol into cyclohexanone within 150 min, and the conversion selectivity of cyclohexanone is greater than 99.5%.

[0090] As can be seen from the above examples, the catalyst provided by the application has a high specific surface area and is composed of two parts, namely a titanium nickel nitride nanoparticle carrier and a supported Pd nanocluster. Among them, nickel atoms are doped between the titanium nitride crystal lattices. The Pd nanocluster is supported on the surface of the TiNiN carrier, and by adjusting the loading amount of Pd atoms, high-efficiency and high-selectivity catalysis of various environmental hydrogenation catalytic processes can be achieved.

[0091] When the mass fraction of Pd is 0.5%, the catalytic activity of the Pd / TiNiN nanocatalyst for 4-chlorophenol reaches a similar level to that of the Au@Pd nanowire, and can be used as a substitute for a noble metal nanocatalyst carrier; when the mass fraction of Pd is adjusted to 0.05%, the catalytic activity and selectivity of the Pd / TiNiN catalyst for 4-nitrochlorobenzene are similar to those of the Au@Pd nanowire. When the mass fraction of Pd reaches 0.5%, the Pd / TiNiN nanocatalyst can also achieve high-efficiency selective hydrogenation of phenol, and can make phenol be efficiently hydrogenated and converted into cyclohexanone, and the conversion selectivity is greater than 99.5%, which is much higher than that of the catalyst reported in the literature.

[0092] The catalyst of the application combines the advantages of high activity of Pd and low cost and high stability of TiNiN. Among transition metal nitrides, titanium nitride (TiN) can improve the dispersibility of Pd and optimize the electronic state of Pd, and is a very promising Pd carrier, which can improve the performance of Pd in the key step of treating halogenated pollutants in wastewater, i.e. hydrogenation dehalogenation process. The doping of Ni can further improve the performance of the Pd / TiNiN catalyst in hydrogenation dehalogenation, and the catalytic activity is similar to that of the Au@Pd nanowire, which can be used as a substitute for a noble metal carrier in the future.

[0093] The nano catalyst designed by the application is the first to use a second metal to dope titanium nitride loaded Pd nano clusters, and the nano catalyst has high catalytic activity and high selectivity in various environmental hydrogenation catalytic reactions, and can provide new ideas for the development of the subsequent nano science and technology field.

[0094] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. The application of a titanium nickel nitride-based palladium catalyst in the catalytic reduction process for treating pollutants, characterized in that, The preparation method of the titanium nitride nickel-based palladium catalyst includes the following steps: (1) Under an ammonia atmosphere, titanium tetrachloride, nickel acetate tetrahydrate and ethanol were mixed and reacted to obtain a complex powder; (2) Under an ammonia atmosphere, the complex powder was subjected to a nitriding reaction to obtain titanium nickel nitride nanoparticles; (3) Titanium nickel nitride nanoparticles, chloropalladic acid solution, water and potassium borohydride solution are mixed and reacted to obtain the titanium nickel nitride-based palladium catalyst. The mass-to-volume ratio of titanium tetrachloride, nickel acetate tetrahydrate, and ethanol in step (1) is 0.5~1.5mL: 0.08~0.16g: 25~35mL; The mass-to-volume ratio of the titanium nickel nitride nanoparticles, chloropalladium acid solution, and water in step (3) is 95~105mg: 0.1~20mL: 195~205mL; The catalytic reduction process specifically treats pollutants through 4-CP hydrogenation dehalogenation reaction, phenol hydrogenation catalytic reaction, or 4-nitrochlorobenzene hydrogenation conversion.

2. The application of the titanium nickel nitride-based palladium catalyst as described in claim 1 in the catalytic reduction process for treating pollutants, characterized in that, The ammonia atmosphere in step (1) has an inlet rate of 25-35 sccm, a reaction temperature of 20-30℃, and a reaction time of 25-35 min.

3. The application of the titanium nickel nitride-based palladium catalyst as described in claim 2 in the catalytic reduction process for treating pollutants, characterized in that, The ammonia atmosphere in step (2) has an inlet rate of 45-55 sccm, the nitriding reaction temperature is 750-850℃, and the nitriding reaction time is 2-3h.

4. The application of the titanium nickel nitride-based palladium catalyst as described in claim 3 in the catalytic reduction process for treating pollutants, characterized in that, The concentration of the chloropalladium acid solution in step (3) is 3~7 mmol / L, and the concentration of the potassium borohydride solution is 1.5~2 mg / mL.

5. The application of the titanium nickel nitride-based palladium catalyst as described in claim 4 in the catalytic reduction process for treating pollutants, characterized in that, The volume ratio of the chloropalladium acid solution and the potassium borohydride solution in step (3) is 1:1.5~2.

0.

6. The application of the titanium nickel nitride-based palladium catalyst as described in claim 5 in the catalytic reduction process for treating pollutants, characterized in that, The reaction temperature in step (3) is 20~30℃, and the reaction time is 0.5~1h.

Images