Supported low-temperature ammoxidation reaction catalyst, preparation method and application

Abstract

The invention relates to a supported low-temperature ammoxidation reaction catalyst, a preparation method and application, the catalyst is composed of an active component and a carrier, the active component is precious metal Pt, and the carrier is W-XC72; xC72 and tungsten chloride are mixed and hydrolyzed to generate W-XC72, sodium borohydride is used as a reducing agent, a precursor of Pt is reduced under intense stirring at room temperature, and the Pt / W-XC72 catalyst is synthesized. The prepared catalyst carrier has a large specific surface area, metal particles on the surface of the catalyst carrier are evenly distributed, the active metal and the carrier have strong electron interaction, the surface and interface properties between the active metal and the carrier are changed by regulating and controlling the electronic structure of the active metal, the adsorption energy of reaction intermediates is optimized, and the catalytic activity of the catalyst is improved. Therefore, the activity of the catalyst in ammoxidation reaction is effectively improved. The catalyst has a wide prospect in low-temperature ammonia fuel cells.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a supported low-temperature ammoxidation reaction catalyst containing metals W and Pt, and a preparation method and application thereof. Background Art

[0002] Due to the massive increase in environmentally friendly energy, H2 has attracted attention as a product that releases pure H2O; however, in practical applications, H2 as a clean energy has two key problems, namely difficult storage conditions and high transportation costs. In particular, hydrogen-containing organic and inorganic compounds and carbon-containing organic matter, such as methanol and ethanol, have been studied as liquid fuels for direct fuel cells due to their easy storage; however, as the main liquid fuels, methanol and ethanol will produce additional carbon dioxide emissions during the power generation process, and there is also a carbon emission problem in the process of converting them into electrochemical energy; in order to achieve the "dual carbon" goals, while reducing fuel storage and transportation costs, adapting to international energy policies, and achieving zero carbon emissions, direct ammonia fuel cells with NH3 as input have attracted widespread attention from researchers; compared with the hydrogen oxidation reaction of hydrogen fuel cells, the anode ammonia electrochemical oxidation reaction (AOR) process is complex and kinetically slow, and the reaction faces higher starting potentials, catalysts are prone to rapid deactivation, and peak currents are low; developing stable and active Catalysts with high energy density will be beneficial to the development of direct ammonia fuel cells. Currently, commonly used AOR catalysts include precious metal catalysts represented by Pt-based catalysts and non-precious metal catalysts represented by Ni, Cu, etc. The structural characteristics of these catalysts directly affect the catalytic performance of AOR. According to the Sabatier principle, the active metals should follow the order of *MN bond strength Ru>Rh>Pd>Ir>Pt, Au, Ag, Cu. Among them, the Pt-N bond has a relatively moderate binding energy, which gives Pt good ammonia oxidation activity. Therefore, Pt-based catalysts are the most common precious metal catalysts used for AOR. However, low reserves and high prices limit their large-scale application. How to improve the atomic utilization and unit activity of Pt is the focus of research on Pt-based catalysts.

[0003] Chen et al. rationally designed a W / WO2 metal heterojunction material on a nickel foam substrate, and the synergistic catalytic effect can effectively improve the activity of hydrogen production by alkaline water electrolysis; (Nat Commun. 2023, 14, 5363.) Li et al. synthesized tungsten doping to make the catalyst material W0.03Fe0.2Ni(OH)2LDH exhibit excellent electrochemical oxygen evolution (OER) and hydrogen evolution (HER) performance; (Chinese Journal of Inorganic Chemistry. 2020, 36(8): 1492-1498); However, these studies have not applied transition metal catalysts to ammonia electrocatalytic oxidation; and no performance breakthrough has been achieved for ammonia oxidation anode catalysts.

[0004] Chinese patent CN118904384A discloses a low-temperature ammonia oxidation catalyst and a preparation method thereof;

[0005] The catalyst is obtained by adding the molecular sieve material of the upper SCR coating to the bottom precious metal coating, coating the mixed coating on a silicate mineral carrier, and drying and calcining. The diffusion resistance can be reduced, the low-temperature NH3 oxidation activity can be increased, the generation of byproducts NOx and N2O can be reduced, and the true activity of the precious metal coating can be reflected. In the process of ammonia electrocatalytic oxidation, especially in the application of ammonia fuel cells, the Pt atom utilization rate and unit activity of the catalyst are not high, and the catalytic effect is not good. Moreover, the preparation process involves the preparation and coating of two layers of coating, the process is complicated, the manufacturing cost is high and the error rate is high. Summary of the invention

[0006] In view of the defects of platinum-based catalysts in the prior art, such as low platinum reserves, high prices, low utilization rate of platinum metal atoms and low unit activity, low catalytic efficiency in the process of ammonia electrocatalytic oxidation, and complex preparation process, a supported low-temperature ammonia oxidation reaction catalyst suitable for direct ammonia fuel cells, which is low in price, simple in preparation method, has good catalytic activity and catalytic stability, a preparation method and application thereof are provided.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a preparation method of a supported low-temperature ammoxidation reaction catalyst, comprising the following steps: step 1: adding a carbon carrier to 100-150 ml of ethanol or 40 ml of isopropanol and performing ultrasonic dispersion; obtaining a mixed solution; step 2: adding tungsten chloride to the mixed solution prepared in step 1 and continuing ultrasonic dispersion; stirring continuously for more than 20 minutes after dispersion; step 3: adding 1-2 ml of deionized water dropwise during the stirring process of step 2; continuing stirring for 20 minutes and then transferring to an oil bath pot, After condensing and refluxing at 80°C for 4 hours, the mixture is dried to obtain a precursor powder; step 4: heating the dried precursor powder at a heating rate of 2 to 3°C per minute in a methane atmosphere, and then calcining to obtain a tungsten metal carrier; step 5: firstly mixing the tungsten metal carrier with isopropanol and deionized water and performing ultrasonic dispersion, then adding chloroplatinic acid solution to continue ultrasonic dispersion, then stirring the solution and dropping a mixed solution containing sodium borohydride and sodium hydroxide, stirring for 4 to 5 hours, filtering and washing, and finally vacuum drying to obtain a supported low-temperature ammoxidation reaction catalyst.

[0008] Furthermore, in step 1, the carbon carrier is mixed with 100-150 ml of ethanol or 40 ml of isopropanol and deionized water, and then ultrasonically dispersed to obtain a mixed solution.

[0009] Furthermore, in step five, 0.1 M, 50 mL of sodium hydroxide solution is prepared, and sodium borohydride and sodium hydroxide are mixed to obtain a mixed solution containing sodium borohydride and sodium hydroxide.

[0010] Furthermore, in step 2, the tungsten chloride is tungsten tetrachloride, and the content of tungsten element in the tungsten chloride is 10-20%.

[0011] Furthermore, in step 4, the dried precursor powder is heated to 700-800° C. in a methane atmosphere, and then calcined at 700-800° C. for 1-3 hours to obtain a tungsten metal carrier.

[0012] Furthermore, in step five, the loading amount of platinum metal in the aluminum platinum acid solution is 20%.

[0013] Furthermore, in step five, vacuum drying is performed at 60-80° C. for 12 to 24 hours.

[0014] A supported low-temperature ammonia oxidation reaction catalyst comprises an active component and a composite carrier, wherein the composite carrier is a mixture of tungsten metal and a carbon carrier, and the active component is metal platinum; the mass fraction of the metal platinum is 10-30%.

[0015] A supported low-temperature ammonia oxidation reaction catalyst is used in an ammonia fuel cell.

[0016] The present invention discloses a supported low-temperature ammonia oxidation reaction catalyst, a preparation method and an application thereof. The catalyst carrier has a large specific surface area, and metal particles on its surface are evenly distributed. The active metal and the carrier have a strong electronic interaction. The electronic structure of the active metal is regulated, the surface and interface properties between the active metal and the carrier are changed, and the adsorption energy of the reaction intermediates is optimized, thereby effectively improving the activity of the catalyst in the ammonia oxidation reaction. The W-XC72 carrier is used, and the metal is then loaded by a simple impregnation liquid phase reduction method. The operation is convenient, and no pollution is caused to the environment, and no harmful substances are generated. The prepared Pt / W-XC72 supported catalyst is applied to electrocatalytic ammonia oxidation, has a lower ammonia oxidation starting potential and a catalytic performance better than that of the Pt / XC72 catalyst. The catalyst has broad prospects in ammonia fuel cells, especially low-temperature ammonia fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1Comparison of XRD patterns of XC72 and W-XC72 composite supports;

[0019] Figure 2 CV curve of the Pt / XC72 catalyst prepared in Example 1 in 1M KOH+0.1M NH3 solution;

[0020] Figure 3 CV curve of the Pt / W-XC72 (10%) catalyst prepared in Example 2 in 1M KOH+0.1M NH3 solution;

[0021] Figure 4 CV curve of the Pt / W-XC72 (20%) catalyst prepared in Example 3 in 1M KOH+0.1M NH3 solution;

[0022] Figure 5 Scanning electron microscope and EDX element distribution images of the Pt / XC72 catalyst prepared in Example 1;

[0023] Figure 6 Scanning electron microscope and EDX element distribution images of the Pt / W-XC72 (10%) catalyst prepared in Example 2. DETAILED DESCRIPTION

[0024] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0025] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0026] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0027] Hereinafter, the embodiments of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0028] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0030] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0031] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0032] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0033] The terms "above" and "below" used in this application include the number, for example, "one or more" means one or more, and "one or more of A and B" means "A", "B" or "A and B".

[0034] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, the preparation method of a supported low-temperature ammoxidation reaction catalyst according to the present invention comprises the following steps:

[0037] Step 1: Add the carbon carrier into 100-150 ml of ethanol or 40 ml of isopropanol and disperse by ultrasonication to obtain a mixed solution;

[0038] Step 2: Add tungsten chloride to the mixed solution prepared in step 1 and continue to disperse by ultrasonication; continue stirring for more than 20 minutes after dispersion;

[0039] Step 3: During the stirring process of step 2, 1 to 2 ml of deionized water is added dropwise; stirring is continued for 20 minutes, and then the mixture is transferred to an oil bath, and condensed and refluxed at 80° C. for 4 hours, and then dried; a precursor powder is obtained;

[0040] Step 4: heating the dried precursor powder at a heating rate of 2 to 3° C. per minute in a methane atmosphere, and then calcining to obtain a tungsten metal carrier;

[0041] Step 5: First, mix the tungsten metal carrier with isopropanol and deionized water and perform ultrasonic dispersion, then add chloroplatinic acid solution and continue ultrasonic dispersion, then stir the solution and drop a mixed solution containing sodium borohydride and sodium hydroxide, stir for 4 to 5 hours, filter and wash, and finally vacuum dry to obtain a supported low-temperature ammoxidation reaction catalyst.

[0042] In step 1, the carbon carrier is Vulcan XC72; the Vulcan XC72 carrier is placed in a beaker, a certain volume of deionized water is added, and then 100-150 ml of ethanol or 40 ml of isopropanol is added; a mixed solution is obtained by ultrasonic dispersion; in step 2, tungsten chloride, such as tungsten tetrachloride, is added to the mixed solution prepared in step 1 and ultrasonic dispersion is continued, and after dispersion, it is vigorously stirred for more than 20 minutes; in step 3, 1-2 ml of deionized water is slowly added dropwise during the vigorous stirring process; after the addition, stirring is continued for 20 minutes, and the stirred solution is transferred to a round-bottom flask, and then transferred to an oil bath pot; after condensing and refluxing at 80° C. for 4 hours, the precursor powder is obtained by suction filtration, washing and drying; in step 5, the tungsten metal carrier is first placed in a beaker, and then isopropanol and deionized water are added to mix, and the mixture is mixed. Then ultrasonic dispersion is performed, and then chloroplatinic acid solution is added to the mixed solution and ultrasonic dispersion is continued; at the same time, a sodium hydroxide solution with a certain molar concentration is prepared, sodium borohydride is mixed with the prepared sodium hydroxide to obtain a mixed solution, and then a mixed solution containing 20 to 40 mg of sodium borohydride and the prepared sodium hydroxide is added; wherein the sodium borohydride can reduce the platinum metal in the added platinum chloride solution, which is beneficial to the loading of the platinum metal on the subsequent carrier; under vigorous stirring, the catalyst precursor solution is slowly dripped with the mixed solution containing sodium borohydride and sodium hydroxide, and after all the dripping is completed, it is sealed with a plastic wrap, and stirring is continued for 4 to 5 hours until the reaction is complete, and it is filtered (until the filtrate does not contain chloride ions), washed and vacuum dried to obtain a supported low-temperature ammoxidation reaction catalyst.

[0043] Example 1

[0044] Step 1: Place 80 mg of Vulcan XC72 carrier in a 300 mL beaker, add 40 mL of deionized water and 40 mL of isopropanol; ultrasonically disperse for 30 minutes to obtain a mixed solution;

[0045] Step 2: Add 1.06 mL of chloroplatinic acid solution with a platinum metal loading of 20% to the mixed solution prepared in step 1 and continue ultrasonic dispersion; continue stirring for 20 minutes after dispersion; prepare 50 mL of 0.1 mol NaOH solution at the same time, and then weigh 40 mg of NaBH4 and dissolve it in the NaOH solution;

[0046] Step 3: Stir the solution and drop a mixed solution containing sodium borohydride and sodium hydroxide, stir for 4.5 hours, filter and wash, and finally vacuum dry at 70° C. for 12 hours to obtain a supported low-temperature ammoxidation reaction catalyst Pt / XC72.

[0047] Example 2

[0048] Preparation of precursor:

[0049] Step 1: Place 450 mg of Vulcan XC72 carrier in a 250 mL beaker, add 120 mL of ethanol, and disperse by ultrasonic for 30 minutes to obtain a mixed solution;

[0050] Step 2: Add 88.57 mg of tungsten tetrachloride (wherein the tungsten content is 10%) to the mixed solution prepared in step 1 and continue to disperse by ultrasonication; continue to stir for 20 minutes after dispersion;

[0051] Step 3: During the stirring process of step 2, 1.5 ml of deionized water was added dropwise; the mixture was stirred for 20 minutes and then transferred to an oil bath, condensed and refluxed at 80°C for 4 hours, and then filtered and dried to obtain a precursor powder;

[0052] Step 4: The dried precursor powder was heated to 750° C. at a heating rate of 3° C. per minute under a methane atmosphere, and then calcined at 750° C. for 2 hours to obtain a W-XC72 (10%) carrier;

[0053] Preparation of catalyst:

[0054] Step 1: Place 80 mg of W-XC72 (10%) carrier in a 300 mL beaker, add 40 mL of deionized water and 40 mL of isopropanol; ultrasonically disperse for 30 minutes to obtain a mixed solution;

[0055] Step 2: Add 1.06 mL of chloroplatinic acid solution with a platinum metal loading of 20% to the mixed solution prepared in step 1 and continue ultrasonic dispersion; continue stirring for 20 minutes after dispersion; and simultaneously prepare 50 mL of 0.1 mol NaOH solution, and then weigh 50 mg of NaBH4 and dissolve it in the NaOH solution;

[0056] Step 3: Stir the solution and add a mixed solution containing sodium borohydride and sodium hydroxide. After all the addition is completed, seal it with plastic wrap, stir it for 5 hours, filter and wash it, and finally vacuum dry it at 60°C for 12 hours to obtain a supported low-temperature ammoxidation reaction catalyst Pt / W-XC72 (10%).

[0057] Example 3

[0058] Preparation of precursor:

[0059] Step 1: Place 400 mg of Vulcan XC72 carrier in a 250 mL beaker, add 150 mL of ethanol, and disperse by ultrasonic for 30 minutes to obtain a mixed solution;

[0060] Step 2: Add 177.14 mg of tungsten tetrachloride (wherein the tungsten content is 20%) to the mixed solution prepared in step 1 and continue to disperse by ultrasonication; continue to stir for 20 minutes after dispersion;

[0061] Step 3: During the stirring process of step 2, 2 ml of deionized water was added dropwise; the mixture was stirred for 20 minutes and then transferred to an oil bath pot, condensed and refluxed at 80°C for 4.5 hours, and then filtered and dried to obtain a precursor powder;

[0062] Step 4: heating the dried precursor powder to 750° C. at a heating rate of 2° C. per minute under a methane atmosphere, and then calcining at 750° C. for 2 hours to obtain a W-XC72 (20%) carrier;

[0063] Preparation of catalyst:

[0064] Step 1: Place 80 mg of W-XC72 (20%) carrier in a 300 mL beaker, add 45 mL of deionized water and 45 mL of isopropanol; ultrasonically disperse for 30 minutes to obtain a mixed solution;

[0065] Step 2: Add 1.35 mL of chloroplatinic acid solution with a platinum metal loading of 20% to the mixed solution prepared in step 1 and continue ultrasonic dispersion; continue stirring for 20 minutes after dispersion; prepare 50 mL of 0.1 mol NaOH solution at the same time, and then weigh 45 mg of NaBH4 and dissolve it in the NaOH solution;

[0066] Step 3: Stir the solution and add a mixed solution containing sodium borohydride and sodium hydroxide. After all the addition is completed, seal it with plastic wrap, stir it for 4 hours, filter and wash it, and finally vacuum dry it at 80°C for 7 hours to obtain a supported low-temperature ammoxidation reaction catalyst Pt / W-XC72 (20%).

[0067] The present application also discloses a metal catalyst of a supported low-temperature ammonia oxidation catalyst prepared by the above-mentioned embodiment, with a metal-carrier surface active site construction, including an active component and a composite carrier, wherein the composite carrier is a mixture of tungsten metal and a carbon carrier, such as W-XC72; the active component is metal platinum; and the metal Pt content is 10 to 30 wt.% in terms of mass fraction.

[0068] The present application also discloses an application of a metal catalyst of a supported low-temperature ammonia oxidation catalyst prepared by the above-mentioned embodiment, such as application in electrocatalytic oxidation of ammonia. More specifically, the metal catalyst of the supported low-temperature ammonia oxidation catalyst is suitable for low-temperature ammonia fuel cells.

[0069] The electrochemical test method of the catalyst prepared in the following examples in an alkaline solution is as follows:

[0070] Weigh 2-4 mg of the catalyst prepared in this embodiment, and put isopropanol and Nafion solution in a 1:1 ratio into a 5 mL injection bottle, ultrasonically disperse the solution to obtain a slurry, transfer a certain amount of the solution and slowly drip it onto the glassy carbon electrode, control the metal content loaded on the glassy carbon electrode to be 4 μg, dry it normally at room temperature, and then perform an electrochemical test; the electrochemical test uses a five-mouth electrolytic cell, pour about 50-70 mL of electrolyte (at the edge of the five-mouth electrolytic cell), place a glassy carbon working electrode in the center of the electrolytic cell (placed above the solution surface), and place a graphite rod counter electrode, a reference electrode Luggin capillary (Hg / HgO), an air inlet pipe and an air outlet device at the four sides; before the test, Ar gas is passed through the upper port of the air inlet pipe to remove dissolved oxygen. During the test, switch the air inlet pipe to the lower port for continuous ventilation (to avoid gas interference and be in an Ar gas atmosphere), and place the working electrode at a suitable depth below the liquid surface.

[0071] In an Ar-saturated 1M KOH solution, scan 15 to 20 times at a speed of 100mV / s to activate the catalyst. Set a certain range of voltage, scan speed, and scan number of circles to clean and activate the electrode surface. If the curves overlap, the activation is successful. Then switch to an Ar-saturated 1M KOH+0.1M NH3 alkaline solution for testing, and maintain the reduction potential (-0.85V vs.Hg / HgO) for at least 100s to restore the catalyst. Then test the CV curve at 5mV / s, 3 to 4 circles, as a basis for testing catalyst performance.

[0072] The physical structure characterization test method of the catalyst prepared in the following examples in alkaline solution is as follows:

[0073] The powder X-ray diffractometer (XRD) uses the X'Pert3 Powder instrument of PANalytical Company in the Netherlands, with a Cu target Kα radiation source with a laser incident wavelength of 0.15406nm, an operating voltage of 45kV, and a current of 40mA. The results are analyzed by HighScore Plus to obtain the composition and crystal structure information of the sample, and the test range is: 2θ = 10 ~ 90°.

[0074] Field emission scanning electron microscope (SEM), using Hitachi's S-4800 field emission scanning electron microscope to observe the morphology, structure and size of the catalyst surface. The samples to be tested need to be dried before testing, and the carrier and catalyst samples with poor conductivity are sprayed with gold before testing. The test working voltage is 5kV and the current is 7μA.

[0075] The XRD patterns of the carriers prepared in Examples 1, 2 and 3 are as follows: Figure 1 , where the XRD spectra of the carriers in Example 2 and Example 3 are consistent; XC72 is mainly composed of a peak package at about 25.8°. There are 4 characteristic diffraction peaks, at 40.42°, 58.36°, 73.33° and 86.91°, respectively, which belong to the metal W species, indicating the successful preparation of metal W.

[0076] Catalyst activity Figure 2-4 As shown, the activities of Pt / XC72, Pt / W-XC72 (10%) and Pt / W-XC72 (20%) are 36, 133 and 58A g-1Pt, respectively. By comparison, it can be found that Pt / W-XC72 (10%) has the best peak current density and the highest performance, indicating that metal W as a carrier can effectively improve the performance.

[0077] like Figure 3 and Figure 4 By comparing the electrochemical activities of Pt / W-XC72 (10%) and Pt / W-XC72 (20%), it can be found that the W content also has an impact on the performance.

[0078] Catalyst morphology and structural information such as Figure 5 and Figure 6 , it can be seen that Pt is successfully reduced and loaded onto the carrier and is evenly distributed on the carrier.

[0079] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. However, the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a supported low-temperature ammoxidation catalyst, characterized in that: The following steps are involved: Step 1: Add the carbon support into 100-150 ml of ethanol or 40 ml of isopropanol and disperse by ultrasonication; A mixed solution is obtained; Step 2: Add tungsten chloride to the mixed solution prepared in step 1 and continue ultrasonic dispersion; continue stirring for more than 20 minutes after dispersion; Step 3: During the stirring process of step 2, 1 to 2 ml of deionized water is added dropwise; stirring is continued for 20 minutes, and then the mixture is transferred to an oil bath, and condensed and refluxed at 80° C. for 4 hours, and then dried; a precursor powder is obtained; Step 4: heating the dried precursor powder at a heating rate of 2 to 3° C. per minute in a methane atmosphere, and then calcining to obtain a tungsten metal carrier; Step 5: First, mix the tungsten metal carrier with isopropanol and deionized water and perform ultrasonic dispersion, then add chloroplatinic acid solution and continue ultrasonic dispersion, then stir the solution and drop a mixed solution containing sodium borohydride and sodium hydroxide, stir for 4 to 5 hours, filter and wash, and finally vacuum dry to obtain a supported low-temperature ammoxidation reaction catalyst.

2. The method for preparing a supported low-temperature ammoxidation catalyst according to claim 1, characterized in that: In step 1, the carbon carrier is mixed with 100-150 ml of ethanol or 40 ml of isopropanol and deionized water, and then ultrasonically dispersed to obtain a mixed solution.

3. The method for preparing a supported low-temperature ammoxidation reaction catalyst according to claim 1, characterized in that: In step five, 0.1 M, 50 mL of sodium hydroxide solution is prepared, sodium borohydride and sodium hydroxide are mixed to obtain a mixed solution containing sodium borohydride and sodium hydroxide; the mass range of the mixed solution containing sodium borohydride and sodium hydroxide is 20 to 40 mg.

4. The method for preparing a supported low-temperature ammoxidation catalyst according to claim 1, characterized in that: In step 2, the tungsten chloride is tungsten tetrachloride, and the content of tungsten element in the tungsten chloride is 10-20%.

5. The method for preparing a supported low-temperature ammoxidation catalyst according to claim 1, characterized in that: In step 4, the dried precursor powder is heated to 700-800° C. in a methane atmosphere, and then calcined at 700-800° C. for 1-3 hours to obtain a tungsten metal carrier.

6. The method for preparing a supported low-temperature ammoxidation catalyst according to claim 1, characterized in that: In step 5, the loading amount of platinum metal in the aluminoplatinic acid solution is 20%.

7. The method for preparing a supported low-temperature ammoxidation catalyst according to claim 1, characterized in that: In step five, vacuum drying is performed at 60-80° C. for 12 to 24 hours.

8. A supported low-temperature ammoxidation reaction catalyst prepared by the method for preparing a supported low-temperature ammoxidation reaction catalyst according to any one of claims 1 to 7, characterized in that The invention comprises an active component and a composite carrier. The composite carrier is a mixture of tungsten metal and a carbon carrier. The active component is metal platinum. The mass fraction of the metal platinum is 10-30%.

9. A supported low-temperature ammoxidation reaction catalyst prepared by the method for preparing a supported low-temperature ammoxidation reaction catalyst according to any one of claims 1 to 7, characterized in that :The supported low-temperature ammonia oxidation reaction catalyst is applied to ammonia fuel cells.

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