Preparation of titanium nitride sea urchin sphere supported platinum catalyst and application of titanium nitride sea urchin sphere supported platinum catalyst in ammoxidation reaction

Abstract

The invention relates to the field of food preservation, and discloses preparation of a titanium nitride sea urchin sphere supported platinum catalyst and application of the titanium nitride sea urchin sphere supported platinum catalyst in ammoxidation reaction, and the preparation method comprises the following steps: (1) dissolving a titanium source and urea in a solvent, stirring, performing ultrasonic treatment, then putting into a polytetrafluoroethylene reaction kettle, then putting into a drying oven, and performing hydrothermal reaction; after the reaction is completed, cooling to room temperature, and washing, centrifuging and drying the obtained substance to obtain a precursor; (2) the prepared precursor is subjected to heat treatment in a nitriding gas atmosphere, and the titanium nitride sea urchin spheres are obtained.The controllable sea urchin sphere morphology enables the titanium nitride sea urchin spheres to have wide application prospects, after platinum is loaded, the titanium nitride sea urchin spheres show high catalytic activity, stability and electrical conductivity in ammoxidation reaction, and the titanium nitride sea urchin spheres have good application prospects. The method is especially suitable for ammoxidation reaction in an alkaline medium, and can provide feasible guidance for development of an efficient platinum-based electrochemical catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of electrocatalysis, and more specifically to the preparation of a titanium nitride sea urchin ball-loaded platinum catalyst and its application in an ammonia oxidation reaction. Background Art

[0002] Ammonia is considered to be a promising hydrogen storage and transportation carrier due to its high hydrogen content (17.7 wt%), easy liquefaction and low flammability. Therefore, the ammonia oxidation reaction (AOR) has also received extensive attention. It participates in many important electrochemical processes, such as water electrolyzers and fuel cells, and plays a key role in the green energy economy.

[0003] Research has found that Pt not only has a moderate binding capacity for nitrogen, but also has excellent dehydrogenation kinetics, so it is considered the most active metal in electrocatalytic AOR. However, the scarcity and high price of Pt make it difficult to apply it on a large scale, so improving the performance of Pt-based catalysts and reducing the amount of Pt has always been the main goal of research.

[0004] Among the numerous studies, supported metal catalysts are a prominent example. Unlike single metal catalysts, supported metal catalysts can greatly reduce the amount of precious metals used. The unique interaction between metal and carrier and the various geometric, coordination, electronic and synergistic effects that may be produced also play an important role in the electrocatalytic process. Specifically, interface engineering can regulate the electronic structure of metal atoms on the interface and further affect the adsorption / desorption behavior of reactants and intermediates, thereby affecting the overall reaction kinetics of the catalyst. Therefore, designing nanostructured metal nitrides with customized morphology has been proven to be an effective strategy to solve these problems. To this end, we proposed the preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reactions. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and to provide a preparation method of a titanium nitride sea urchin ball-loaded platinum catalyst and its application in an ammonia oxidation reaction, which has relatively excellent catalytic activity, stability and conductivity.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions: comprising the following steps:

[0007] (1) dissolving the titanium source and urea in a solvent, stirring, ultrasonicating, and then placing in a polytetrafluoroethylene reactor, and then placing in an oven for hydrothermal reaction; after the reaction is completed, cooling to room temperature, washing, centrifuging, and drying the obtained substance to obtain a precursor;

[0008] (2) heat-treating the precursor prepared above in a nitriding gas atmosphere to obtain titanium nitride sea urchin balls;

[0009] (3) The titanium nitride prepared above is loaded with metal platinum using a platinum source, dissolved in a solvent, stirred with ultrasound, placed in a polytetrafluoroethylene reactor, and then placed in an oven for hydrothermal reaction to obtain platinum-loaded titanium nitride.

[0010] Furthermore, the titanium source is potassium titanium oxalate.

[0011] Furthermore, the solvent is water and diethylene glycol.

[0012] Furthermore, the stirring and ultrasonic time is 30 minutes.

[0013] Furthermore, the hydrothermal reaction temperature is 180-200° C. and the time can be 10-15 hours.

[0014] Furthermore, the platinum source is chloroplatinic acid.

[0015] Preferably, the metal platinum is loaded by a hydrothermal method.

[0016] Preferably, the platinum loading is 4-8%.

[0017] Furthermore, the content of ammonia in the nitriding atmosphere is 100%.

[0018] Preferably, the calcination temperature is 750-1000°C.

[0019] Preferably, the calcination time is 1-3 hours.

[0020] Furthermore, the prepared titanium nitride sea urchin ball is a platinum-loaded catalyst.

[0021] Furthermore, the titanium nitride sea urchin ball loaded with platinum catalyst is used in electrocatalytic ammonia oxidation reaction.

[0022] Furthermore, the electrocatalytic ammonia oxidation reaction is an ammonia oxidation reaction in an alkaline medium using 1M KOH as an electrolyte.

[0023] According to the above scheme,

[0024] Compared with the prior art, the beneficial effects are as follows:

[0025] The controllable sea urchin ball morphology of the present invention gives it a relatively broad application prospect. After loading platinum, it exhibits high catalytic activity, stability and conductivity in the ammonia oxidation reaction, and is particularly suitable for the ammonia oxidation reaction in alkaline media, which can provide practical guidance for the development of efficient platinum-based electrochemical catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the X-ray diffraction pattern of the present invention;

[0027] Figure 2 It is a schematic diagram of a scanning electron microscope image of the present invention;

[0028] Figure 3 AOR curve schematic diagram of the present invention under different electrolytes of 1M KOH and 0.1M NH3·H2O;

[0029] Figure 4 AOR curves of Pt / TiN, Pt / TiO2 and Pt / C obtained in the present invention are shown in FIG.

[0030] Figure 5 AOR curve schematic diagram of the present invention under different NH3·H2O concentrations;

[0031] Figure 6 Schematic diagram of the AOR curve under different KOH concentrations of the present invention;

[0032] Figure 7 This is a current-time schematic diagram of the present invention at 655 mV overpotential and different NH3·H2O concentrations;

[0033] Figure 8 Schematic diagram showing the comparison of the AOR catalytic activity of Pt / TiN of the present invention before and after 100 cycles of CV. DETAILED DESCRIPTION

[0034] The invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments. The following embodiments are merely illustrative and are not intended to limit the scope of protection of the present invention.

[0035] refer to Figure 1-Figure 8 As shown, a preparation method of a titanium nitride sea urchin ball-supported platinum catalyst and its application in an ammonia oxidation reaction comprises the following steps:

[0036] (1) dissolving the titanium source and urea in a solvent, stirring, ultrasonicating, and then placing in a polytetrafluoroethylene reactor, and then placing in an oven for hydrothermal reaction; after the reaction is completed, cooling to room temperature, washing, centrifuging, and drying the obtained substance to obtain a precursor;

[0037] (2) heat-treating the precursor prepared above in a nitriding gas atmosphere to obtain titanium nitride sea urchin balls;

[0038] (3) The titanium nitride prepared above is loaded with metal platinum using a platinum source, dissolved in a solvent, stirred with ultrasound, placed in a polytetrafluoroethylene reactor, and then placed in an oven for hydrothermal reaction to obtain platinum-loaded titanium nitride.

[0039] Among them; the titanium source is potassium titanium oxalate, the solvent is water and diethylene glycol, stirring, the ultrasonic time is 30 minutes, the hydrothermal reaction temperature is 180-200°C, the time can be 10-15 hours, the platinum source is chloroplatinic acid, the metal platinum loading adopts the hydrothermal method, the platinum loading amount is 4-8%, the ammonia content in the nitriding atmosphere is 100%, the calcination temperature is 750-1000°C, and the calcination time is 1-3 hours.

[0040] In which: step (1) potassium titanium oxalate and urea are dissolved in water for hydrothermal reaction to generate a titanium dioxide precursor; in step (2) based on the precursor, heat treatment is performed under an ammonia atmosphere to obtain a titanium nitride precursor; and in step (3) a platinum source and titanium nitride are dissolved in water and ethylene glycol to load platinum.

[0041] Among them; the titanium nitride sea urchin ball loaded with platinum catalyst prepared according to the above-mentioned preparation method is used in the electrocatalytic ammonia oxidation reaction, and the electrocatalytic ammonia oxidation reaction is an ammonia oxidation reaction in an alkaline medium with 1M KOH and 0.1M NH3·H2O as electrolyte.

[0042] Example 1

[0043] Preparation of titanium nitride sea urchin balls loaded with platinum catalyst:

[0044] (1) Dissolve 350 mg of potassium titanium oxalate and 1 g of uric acid in 30 ml of diethylene glycol and 10 ml of water, stir, and ultrasonicate for 30 min. Then transfer the solution to a polytetrafluoroethylene reactor and place it in an oven for hydrothermal reaction. Set the reaction temperature to 180 ° C and the reaction time to 12 h. After cooling to room temperature, wash with deionized water and ethanol for more than 3 times, place the washed sample in a vacuum oven and place it for 12 h. Finally, obtain the precursor.

[0045] (2) 70 mg of the above-prepared precursor was calcined at 900° C. for 2 h in an ammonia atmosphere (ammonia content: 100%) to obtain titanium nitride sea urchin balls, denoted as TiN.

[0046] (3) Dissolve 20 mg of the titanium nitride precursor prepared above into 15 ml of water and 15 ml of ethylene glycol, then add chloroplatinic acid to the solution, stir, and ultrasonicate for 30 minutes. Then transfer the solution to a polytetrafluoroethylene reactor, put it into an oven, and perform a hydrothermal reaction. Set the reaction temperature to 180°C and the reaction time to 2 hours. After cooling to room temperature, wash with deionized water and ethanol for more than 3 times. Put the washed sample into a vacuum oven and leave it for 12 hours. Finally, the titanium nitride sea urchin ball loaded with platinum is obtained, which is recorded as Pt / T i N. The platinum loading is 6%.

[0047] The structure of the Pt / TiN sample prepared in Example 1 was characterized. Figure 1 .

[0048] Figure 1 All the diffraction peaks that appeared in the MgO2O3 solution corresponded to the diffraction peaks of pure TiN. After adding platinum, peaks related to platinum appeared, which showed that platinum was successfully loaded on titanium nitride. Figure 2 It shows that the Pt / T i N sample has a sea urchin ball structure morphology.

[0049] Example 2

[0050] Study on the application of the Pt / TiN sample prepared in Example 1 as a catalyst in electrocatalytic ammonia oxidation:

[0051] AOR electrocatalytic test was carried out on an electrochemical workstation using a standard three-electrode system, with 1 M KOH solution containing 0.1 M NH3·H2O as the electrolyte, a platinum carbon electrode modified with Pt / T i N as the working electrode (5 mg of the Pt / T i N sample prepared in Example 1 was dispersed in 1000 μL ethanol containing 40 uL 5 wt% Nafion and ultrasonicated for 1 h to prepare the ink; then 10 μL of the ink was dropped onto the polished platinum carbon electrode to obtain the working electrode), a platinum wire as the counter electrode, and a Hg / HgO electrode as the reference electrode.

[0052] At the same time, a control example was set up in which commercial Pt / C was used as a catalyst to replace Pt / T i N to prepare a working electrode. The Pt content in the Pt / C was 20%, and the other conditions were the same as above.

[0053] like Figure 3 and Figure 4 As shown in the figure, the AOR curves under different electrolytes of 1 M KOH and 0.1 M NH3·H2O as well as the catalytic activities of different catalysts in the AOR process show that the AOR catalytic activity of Pt / TiN in alkaline medium is significantly better than that of Pt / C.

[0054] from Figure 5 and Figure 6 As shown, the AOR curves under different NH3·H2O concentrations and different KOH concentrations respectively;

[0055] from Figure 7 It can be seen that Pt / T i N is stable in alkaline medium.

[0056] from Figure 8 It can be seen that the AOR catalytic activity of Pt / TiN in alkaline medium is higher than that of Pt / C even after 100 cycles of CV.

[0057] In summary, the AOR catalytic activity of the Pt / T i N prepared in the present invention is better than that of the commercial Pt / C catalyst in alkaline medium and has good stability.

[0058] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A preparation method of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction, characterized in that: The following steps are involved: (1) dissolving the titanium source and urea in a solvent, stirring, ultrasonicating, and then placing in a polytetrafluoroethylene reactor, and then placing in an oven for hydrothermal reaction; after the reaction is completed, cooling to room temperature, washing, centrifuging, and drying the obtained substance to obtain a precursor; (2) heat-treating the precursor prepared above in a nitriding gas atmosphere to obtain titanium nitride sea urchin balls; (3) The titanium nitride prepared above is loaded with metal platinum using a platinum source, dissolved in a solvent, stirred with ultrasound, placed in a polytetrafluoroethylene reactor, and then placed in an oven for hydrothermal reaction to obtain platinum-loaded titanium nitride.

2. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The titanium source is potassium titanium oxalate.

3. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The solvents are water and diethylene glycol.

4. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The stirring and ultrasonic time is 30 min.

5. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The hydrothermal reaction temperature is 180-200° C. and the reaction time can be 10-15 hours.

6. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The platinum source is chloroplatinic acid, the metal platinum is loaded by a hydrothermal method, and the loading amount of the platinum is 4-8%.

7. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The ammonia content in the nitriding atmosphere is 100%, the calcination temperature is 750-1000° C., and the calcination time is 1-3 hours.

8. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 1, characterized in that: The prepared titanium nitride sea urchin ball is a platinum-loaded catalyst.

9. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 8, characterized in that: The titanium nitride sea urchin ball supports the platinum catalyst for use in an electrocatalytic ammonia oxidation reaction.

10. The preparation of a titanium nitride sea urchin ball-supported platinum catalyst and its application in ammonia oxidation reaction according to claim 9, characterized in that: The electrocatalytic ammonia oxidation reaction is an ammonia oxidation reaction in an alkaline medium using 1M KOH as an electrolyte.

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