Instantaneous synthesis method of ammonia decomposition catalyst with high specific surface area

Abstract

The invention provides an instantaneous synthesis method of a noble metal / rare earth oxide composite material, which comprises the following steps: firstly, mixing rare earth soluble salt, noble metal soluble salt and a solvent, and standing to obtain a precursor solution; atomizing the precursor solution obtained in the previous step and carrier gas, feeding the atomized precursor solution and carrier gas into a high-temperature reaction device for reaction to form material powder with large specific surface area, and feeding the powder into an electrostatic powder collecting device under the action of the carrier gas to obtain the noble metal / rare earth oxide composite material. The invention provides an instantaneous synthesis method for an ammonia decomposition catalyst with a high specific surface area, and instantaneous synthesis of the ammonia decomposition catalyst is realized. According to the synthesis method provided by the invention, the ammonia decomposition catalyst with high specific surface area can be rapidly prepared, the requirement of the high-performance ammonia decomposition catalyst is met, the product purity is high, and the synthesis method is simple, mild in condition, high in synthesis efficiency and more suitable for popularization and application of industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by decomposing ammonia, and relates to a method for synthesizing a noble metal / rare earth oxide composite material, a synthesis system for instantaneously synthesizing a noble metal / rare earth oxide composite material and applications thereof, and in particular to a method for instantaneously synthesizing a high specific surface area ammonia decomposition catalyst and applications thereof. Background Art

[0002] The storage of hydrogen has always been a major challenge in the development and utilization of hydrogen energy. Efficient and safe hydrogen storage is essential for the application of hydrogen in various fields such as transportation, power generation and industry. One of the main difficulties lies in the low volumetric energy density of hydrogen at room temperature and pressure. The boiling point of hydrogen is very low, and high-pressure storage tanks or low temperatures are required to achieve sufficient storage density, which undoubtedly increases the complexity and cost of the hydrogen storage system. In addition, hydrogen storage in solid-state hydrogen storage materials usually has problems such as slow absorption and release kinetics, limited cycle stability, and high material costs. Due to the high pressure involved, compressed hydrogen storage also has safety issues. Hydrogen molecules are very small and can penetrate into many materials, so it is difficult to ensure a storage system that does not leak for a long time. Even a slight leak in a hydrogen storage tank can cause significant losses and pose a major safety hazard.

[0003] Ammonia is a promising liquid hydrogen storage carrier, and it has several obvious advantages as a hydrogen storage and transportation. First, the hydrogen content of ammonia is relatively high, about 17.6%. This means that a large amount of hydrogen can be stored and transported in the form of ammonia. In addition, compared to hydrogen, ammonia requires lower pressure and higher temperature to reach liquid state, making it easier to transport. It is also less flammable and explosive than hydrogen, which improves the safety of storage and transportation. Another key advantage is that ammonia has a ready-made production, storage and distribution infrastructure, the synthetic ammonia industry is mature, and existing facilities can be directly used for hydrogen-related applications.

[0004] Although ammonia has great potential as a hydrogen carrier, the process of ammonia decomposition to produce hydrogen is not without challenges. One of the main problems is the high energy demand of the ammonia decomposition reaction. The decomposition of ammonia into hydrogen and nitrogen is an endothermic process that usually requires high temperatures and a large amount of energy input, which not only increases operating costs, but also poses challenges in terms of energy efficiency and the integration of the process with other energy systems. Another issue is the catalytic performance of the materials used for ammonia decomposition. At present, amino catalyst materials are mainly synthesized by liquid phase methods, including hydrothermal synthesis, precipitation, sol-gel, microemulsion, etc. Among them, the hydrothermal method is a method for preparing materials in a sealed pressure vessel using water as a solvent, dissolving and recrystallizing powders. The product has high purity, small and uniform particle size, and light particle agglomeration, but it has high requirements for equipment and is difficult to industrialize. In addition, the experiment requires a high temperature and high pressure environment, with high safety risks. If it is not operated properly, it may cause equipment leakage, explosion and other safety accidents. The precipitation method is a method of preparing materials by adding a precipitant to a solution to precipitate the target substance. It is simple to operate and has low cost, but it is easy to agglomerate, has a wide particle size distribution, is difficult to filter and wash, and the precipitant is easy to remain, which will affect the performance of the product. The sol-gel method is a chemical method that uses metal organic matter or metal alkoxide as a precursor, mixes it with water to form a solution, and then hydrolyzes and condenses it to form a sol, then gelates it, and then dries and heat treats it to prepare various forms of materials. Its reaction temperature is low, and the synthesized material has good uniformity and high purity, but its reaction time is long and the drying shrinkage is large, which will affect the dimensional stability of the material. The microemulsion method is that the reactants are solubilized in the tiny space of the microemulsion, and react under certain conditions to form solid phase particles. Its reaction conditions are mild and the particle size is well controllable, but the yield is low, the cost is high, and the post-processing is complicated.

[0005] Therefore, how to find a more suitable method for preparing catalyst materials for ammonia decomposition and solve the above-mentioned technical problems existing in the prior art has become one of the focuses of widespread attention of many forward-looking technicians in the industry. Summary of the invention

[0006] In view of this, the present invention provides a method for synthesizing a precious metal / rare earth oxide composite material, a synthesis system for instantaneously synthesizing a precious metal / rare earth oxide composite material and its application, in particular, a method for instantaneously synthesizing a high specific surface area ammonia decomposition catalyst. The instantaneous synthesis method provided by the present invention uses a carrier gas to transport small droplets of atomized precursor solution into a tubular furnace, and adjusts the temperature of the tubular furnace to instantaneously synthesize the target product, which can prepare ammonia decomposition catalysts with high specific surface areas and meet the needs of high-performance ammonia decomposition catalysts. Moreover, the synthesis method is simple, the conditions are mild, and the synthesis efficiency is high, which is more suitable for the promotion and application of industrial production.

[0007] The present invention provides a method for synthesizing a noble metal / rare earth oxide composite material, comprising the following steps:

[0008] 1) mixing a rare earth soluble salt, a noble metal soluble salt and a solvent, and allowing the mixture to stand to obtain a precursor solution;

[0009] 2) The precursor solution obtained in the above step is subjected to carrier gas atomization treatment and then sent to a high-temperature reaction device for reaction to form material powder. After being transmitted by the carrier gas, the material powder enters an electrostatic powder collection device to obtain a precious metal / rare earth oxide composite material.

[0010] Preferably, the rare earth soluble salt comprises rare earth nitrate;

[0011] The rare earth element in the rare earth soluble salt includes cerium;

[0012] The noble metal soluble salt comprises a noble metal chloride;

[0013] The noble metal in the noble metal soluble salt includes ruthenium.

[0014] Preferably, the solvent comprises one or more of water, methanol and ethanol;

[0015] The rare earth soluble salt and the noble metal soluble salt are present in a molar ratio of (4-20):1, calculated on the basis of the rare earth element and the noble metal.

[0016] The mass ratio of the rare earth soluble salt to the solvent is (1-20):100.

[0017] Preferably, the mixing includes sufficient dissolution;

[0018] The aging time is greater than or equal to 30 minutes;

[0019] The carrier gas includes one or more of air, hydrogen-argon mixed gas, argon, nitrogen and ammonia.

[0020] Preferably, the pressure of the carrier gas is 0.01 to 0.5 MPa;

[0021] The flow ratio of the precursor solution to the carrier gas is 1:(740-1600);

[0022] The high temperature is 700-1000°C.

[0023] Preferably, the reaction is specifically an instantaneous reaction;

[0024] The electrostatic powder collection device includes a high-voltage electrostatic collection device;

[0025] The voltage of the high-voltage electrostatic collection device is -1 to -30 kV;

[0026] The obtained noble metal / rare earth oxide composite material is attached to the inner wall of the high-voltage electrostatic collection device.

[0027] Preferably, the noble metal / rare earth oxide composite material comprises a noble metal / rare earth oxide catalyst;

[0028] The noble metal / rare earth oxide composite material has the morphology of hollow spherical particles;

[0029] The noble metal / rare earth oxide composite material is specifically a composite material in which a noble metal is loaded on a rare earth oxide;

[0030] The catalyst is specifically an ammonia decomposition catalyst.

[0031] The present invention provides a synthesis system for instantaneously synthesizing a noble metal / rare earth oxide composite material, comprising:

[0032] Pressure drive device;

[0033] an atomizing device connected to the pressure driving device;

[0034] A high-temperature closed reaction device connected to the atomization device;

[0035] An electrostatic powder collection device connected to the closed reaction device.

[0036] Preferably, the pressure driving device is connected to a carrier gas source and a precursor solution source;

[0037] The outlet of the pressure driving device is connected to the inlet of the atomizing device;

[0038] The outlet of the atomizing device is connected to the inlet of the high-temperature closed reaction device;

[0039] The high temperature closed reaction device comprises a tubular furnace;

[0040] The outlet of the high temperature closed reaction device is connected to the inlet of the electrostatic powder collection device;

[0041] The electrostatic powder collection device includes a high-voltage electrostatic collection device;

[0042] The electrostatic powder collecting device is provided with an exhaust gas outlet which is connected to the exhaust gas treatment device.

[0043] The present invention also provides the use of the synthesis method or preparation method described in any one of the above technical solutions or the synthesis system described in any one of the above technical solutions in the preparation of catalysts.

[0044] The present invention provides a method for synthesizing a precious metal / rare earth oxide composite material, comprising the following steps: firstly, a rare earth soluble salt, a precious metal soluble salt and a solvent are mixed and allowed to stand to obtain a precursor solution; then, the precursor solution obtained in the above step and a carrier gas are atomized and sent to a high-temperature reaction device for reaction to form a material powder; and then, under the action of the carrier gas, the material powder enters an electrostatic powder collection device to obtain a precious metal / rare earth oxide composite material. Compared with the prior art, the present invention is aimed at the traditional ammonia decomposition catalyst synthesis method, which has the problems of long reaction time, easy agglomeration, poor product purity, high safety risk, etc.

[0045] The present invention creatively designs a synthesis method of a noble metal / rare earth oxide composite material using a specific synthesis route, which is an instantaneous synthesis method that can be used for a high specific surface area ammonia decomposition catalyst, thereby realizing rapid and continuous synthesis of the ammonia decomposition catalyst.

[0046] The synthetic route designed by the present invention uses a carrier gas to transport the prepared precursor solution into small droplets into a tube furnace, adjusts the temperature of the tube furnace, and under the action of high temperature, the solvent evaporates rapidly, the solute is rapidly pyrolyzed, and the material powder is instantly formed, that is, the target product of the precious metal / rare earth oxide composite material. The synthetic method provided by the present invention can prepare an ammonia decomposition catalyst with a high specific surface area, meet the requirements of a high-performance ammonia decomposition catalyst, the product has high purity, and the synthetic method is simple, the conditions are mild, and the synthetic efficiency is high, which is more suitable for the promotion and application of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a SEM electron microscope image of the cerium oxide-supported ruthenium-based catalyst prepared in the present invention;

[0048] Figure 2 The particle size distribution diagram of the cerium oxide supported ruthenium based catalyst prepared by the present invention;

[0049] Figure 3 The BET distribution diagram of the cerium oxide supported ruthenium based catalyst prepared in the present invention;

[0050] Figure 4 A schematic diagram of a spray pyrolysis instantaneous synthesis device for a noble metal / rare earth oxide composite material provided by the present invention;

[0051] Figure 5 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 900°C of the present invention;

[0052] Figure 6 This is a SEM image of the Ru / CeO2 catalyst synthesized at 900°C of the present invention;

[0053] Figure 7This is a graph of ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 900°C of the present invention;

[0054] Figure 8 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 700°C of the present invention;

[0055] Fig. 9 This is a SEM image of the Ru / CeO2 catalyst synthesized at 700°C of the present invention;

[0056] Fig.10 This is a graph of ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 700°C of the present invention;

[0057] Fig.11 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 800°C of the present invention;

[0058] Fig.12 This is a SEM image of the Ru / CeO2 catalyst synthesized at 800°C of the present invention;

[0059] Fig.13 This is a graph of ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 800°C of the present invention;

[0060] Fig.14 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 1000°C of the present invention;

[0061] Fig.15 This is a SEM image of the Ru / CeO2 catalyst synthesized at 1000°C of the present invention;

[0062] Fig.16 This is a graph of the ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 1000°C of the present invention. DETAILED DESCRIPTION

[0063] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0064] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0065] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure raw materials or raw materials of conventional purity used in the field of ammonia decomposition catalyst preparation.

[0066] The present invention provides a method for instantaneous synthesis of a noble metal / rare earth oxide composite material, comprising the following steps:

[0067] 1) mixing a rare earth soluble salt, a noble metal soluble salt and a solvent, and allowing the mixture to stand to obtain a precursor solution;

[0068] 2) The precursor solution obtained in the above step is subjected to carrier gas atomization treatment and then sent to a high-temperature reaction device for reaction to form material powder. After being transmitted by the carrier gas, the material powder enters an electrostatic powder collection device to obtain a precious metal / rare earth oxide composite material.

[0069] The present invention firstly mixes a rare earth soluble salt, a noble metal soluble salt and a solvent, and then allows the mixture to stand to obtain a precursor solution.

[0070] In the present invention, the rare earth soluble salt preferably includes rare earth nitrate.

[0071] In the present invention, the rare earth element in the rare earth soluble salt preferably includes cerium.

[0072] In the present invention, the noble metal soluble salt preferably comprises noble metal chloride.

[0073] In the present invention, the noble metal in the noble metal soluble salt preferably includes ruthenium.

[0074] In the present invention, the solvent preferably includes one or more of water, methanol and ethanol, more preferably water, methanol or ethanol.

[0075] In the present invention, the molar ratio of the rare earth soluble salt to the noble metal soluble salt, calculated on the basis of rare earth element and noble metal, is preferably (4-20):1, more preferably (7-17):1, and even more preferably (10-14):1.

[0076] In the present invention, the mass ratio of the rare earth soluble salt to the solvent is preferably (1-20):100, more preferably (5-16):100, and more preferably (9-12):100.

[0077] In the present invention, the mixing preferably includes sufficient dissolution.

[0078] In the present invention, the precursor solution obtained in the above steps is subjected to carrier gas atomization treatment and then sent to a high-temperature reaction device for reaction to form material powder. After being transmitted by the carrier gas, the material powder enters an electrostatic powder collection device to obtain a precious metal / rare earth oxide composite material.

[0079] In the present invention, the aging time is preferably greater than or equal to 30 min, more preferably greater than or equal to 35 min, and more preferably greater than or equal to 40 min.

[0080] In the present invention, the carrier gas preferably includes one or more of air, a hydrogen-argon mixture, argon, nitrogen and ammonia, and more preferably includes air, a hydrogen-argon mixture, argon, nitrogen or ammonia.

[0081] In the present invention, the pressure of the carrier gas is preferably 0.01 to 0.5 MPa, more preferably 0.1 to 0.4 MPa, and more preferably 0.2 to 0.3 MPa.

[0082] In the present invention, the flow ratio of the precursor solution to the carrier gas is preferably 1:(740-1600), more preferably 1:(900-1400), and more preferably 1:(1100-1200).

[0083] In the present invention, the high temperature is preferably 700 to 1000° C., more preferably 750 to 950° C., and more preferably 800 to 900° C. Specifically, the high temperature is the reaction temperature.

[0084] In the present invention, the reaction is preferably an instantaneous reaction.

[0085] In the present invention, the electrostatic powder collecting device comprises a high voltage electrostatic collecting device.

[0086] In the present invention, the voltage of the high-voltage electrostatic collection device is preferably -1 to -30 kV, more preferably -5 to -25 kV, and more preferably -10 to -20 kV.

[0087] In the present invention, the obtained noble metal / rare earth oxide composite material is preferably attached to the inner wall of a high-voltage electrostatic collection device.

[0088] In the present invention, the noble metal / rare earth oxide composite material preferably includes a noble metal / rare earth oxide catalyst.

[0089] In the present invention, the noble metal / rare earth oxide composite material preferably has the morphology of hollow spherical particles.

[0090] In the present invention, the noble metal / rare earth oxide composite material is preferably a composite material in which a noble metal is loaded on a rare earth oxide. Specifically, in the noble metal / rare earth oxide composite material, noble metal nanoparticles are loaded on rare earth oxide particles. The morphology of the noble metal / rare earth oxide composite material can be uniform spherical particles.

[0091] In the present invention, the catalyst is preferably an ammonia decomposition catalyst.

[0092] The present invention provides a synthesis system for instantaneously synthesizing a noble metal / rare earth oxide composite material, comprising:

[0093] Pressure drive device;

[0094] an atomizing device connected to the pressure driving device;

[0095] A high-temperature closed reaction device connected to the atomization device;

[0096] An electrostatic powder collection device connected to the closed reaction device.

[0097] In the present invention, the pressure driving device is preferably connected to a carrier gas source and a precursor solution source.

[0098] In the present invention, the outlet of the pressure-driven device is preferably connected to the inlet of the atomizing device.

[0099] In the present invention, the outlet of the atomization device is preferably connected to the inlet of the high-temperature closed reaction device.

[0100] In the present invention, the high temperature closed reaction device preferably includes a tubular furnace.

[0101] In the present invention, the outlet of the high-temperature closed reaction device is preferably connected to the inlet of the electrostatic powder collection device.

[0102] In the present invention, the electrostatic powder collection device preferably comprises a high voltage electrostatic collection device.

[0103] In the present invention, the electrostatic powder collection device is provided with an exhaust gas outlet, which is preferably connected to an exhaust gas treatment device.

[0104] The present invention provides the use of the synthesis method or preparation method described in any one of the above technical solutions or the synthesis system described in any one of the above technical solutions in the preparation of catalysts.

[0105] In the present invention, the catalyst is specifically an ammonia decomposition catalyst.

[0106] The present invention is to complete and refine the overall technical solution, better ensure the composition and structure of the precious metal / rare earth oxide composite material, and further improve the ammonia catalytic performance of the precious metal / rare earth oxide composite material. The instantaneous synthesis method of the precious metal / rare earth oxide composite material, the synthesis system of the instantaneous synthesis of the precious metal / rare earth oxide composite material and its application can specifically include the following contents:

[0107] The raw materials nitrate and chloride were dissolved in deionized water and aged for 12 hours;

[0108] The prepared precursor solution is delivered to the atomization device by using a peristaltic pump;

[0109] Use carrier gas to bring the atomized droplets into the tube furnace;

[0110] Under high temperature, the solvent evaporates quickly, the solute is rapidly pyrolyzed, and the material powder is formed instantly;

[0111] Under the synergistic effect of the carrier gas and the electrostatic powder collection device, the target powder will adhere to the inner wall of the collector;

[0112] The samples were taken out for XRD and SEM testing to characterize the phase composition and morphology of the materials.

[0113] See also Figure 1 , Figure 1 This is a SEM electron microscope image of the cerium oxide-supported ruthenium-based catalyst prepared in the present invention.

[0114] See also Figure 2 , Figure 2 This is a particle size distribution diagram of the cerium oxide-supported ruthenium-based catalyst prepared in the present invention.

[0115] Depend on Figure 2 It can be seen that the particle size distribution of the cerium oxide-supported ruthenium-based catalyst prepared in the present invention is uniform.

[0116] See also Figure 3 , Figure 3 This is the BET distribution diagram of the cerium oxide supported ruthenium based catalyst prepared in the present invention.

[0117] Depend on Figure 3 and Figure 2 From the nitrogen adsorption isotherm and pore size distribution diagram, it can be seen that the isothermal adsorption-desorption curve is type IV, the adsorption-desorption isotherms do not overlap, and there is a hysteresis loop in the higher pressure section, indicating that the carrier material has a mesoporous structure and the pore size is concentrated between 1 and 40 nm.

[0118] See also Figure 4 , Figure 4 Schematic diagram of the spray pyrolysis instantaneous synthesis device of the precious metal / rare earth oxide composite material provided by the present invention, wherein: 1. carrier gas system, 2. atomization device, 3. tubular furnace, 4. temperature sensor, 5. electrostatic powder collector, 6. tail gas treatment device.

[0119] The above content of the present invention provides a method for synthesizing a precious metal / rare earth oxide composite material, a synthesis system for instantaneously synthesizing a precious metal / rare earth oxide composite material, and its application. The method for synthesizing a precious metal / rare earth oxide composite material designed by the present invention using a specific synthesis route is an instantaneous synthesis method that can be used for a high specific surface area ammonia decomposition catalyst, and realizes the rapid and continuous synthesis of ammonia decomposition catalyst. The synthesis route designed by the present invention uses a carrier gas to transport the small droplets of the prepared precursor solution atomized into a tube furnace, adjusts the temperature of the tube furnace, and under the action of high temperature, the solvent evaporates rapidly, the solute is rapidly pyrolyzed, and the material powder is instantly formed, that is, the target product of the precious metal / rare earth oxide composite material. The synthesis method provided by the present invention can prepare ammonia decomposition catalysts with high specific surface area, meet the requirements of high-performance ammonia decomposition catalysts, have high product purity, and the synthesis method is simple, the conditions are mild, and the synthesis efficiency is high, which is more suitable for the promotion and application of industrial production.

[0120] In order to further illustrate the present invention, a method for synthesizing a precious metal / rare earth oxide composite material, a system for synthesizing a precious metal / rare earth oxide composite material instantaneously and its application are described in detail below in combination with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operation processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0121] Example 1

[0122] Preparation of cerium oxide supported ruthenium based catalyst:

[0123] 1) Weigh 5.263 g of Ce(NO3)3·6H2O and dissolve it in 100 mL of deionized water until it is fully dissolved. Then weigh 0.16 g of RuCl3·XH2O and transfer it to the Ce(NO3)3·6H2O solution, fully dissolve it and age it for 12 hours.

[0124] 2) The precursor solution prepared in step 1) is transported to the atomizing device by using a melt pump, and the carrier gas device is turned on at the same time. The carrier gas will generate a certain pressure in the atomizing device, so that the precursor solution is atomized, and the atomized droplets are transported to the tubular furnace;

[0125] 3) Adjust the temperature of the tube furnace to 900°C. Under the action of high temperature, the solvent evaporates rapidly, the solute is rapidly pyrolyzed, and the material powder is formed instantly;

[0126] 4) Turn on the high-voltage electrostatic collection device and pass a voltage of -15kV. The powder (positively charged) adheres to the inner wall of the collector under the synergistic effect of the carrier gas and the electrostatic powder collection device.

[0127] XRD test on the material, see Figure 5 , Figure 5 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 900°C of the present invention proves the successful synthesis of Ru / CeO2. The XRD spectrum shows no peaks of raw materials and intermediate products, and the crystallinity is good.

[0128] See also Figure 6 , Figure 6 This is a SEM image of the Ru / CeO2 catalyst synthesized at 900° C. The SEM image shows that the synthesized sample is uniform spherical particles without impurities and agglomeration.

[0129] Then, the ammonia conversion efficiency was tested by gas chromatography. 0.05g of the sample was placed in a quartz tube with an inner diameter of 4mm, and fixed on both sides with quartz wool. The test temperature range was between 450 and 600℃, and the measurement was performed every 50℃. The temperature was raised to 600℃ at a rate of 5℃ / min, and H2 was introduced at a rate of 30sccm. After 2 hours of reduction, NH3 was introduced at a rate of 10sccm for testing.

[0130] The conversion efficiency of ammonia is calculated according to the following formula:

[0131]

[0132] See also Figure 7 , Figure 7 This is a diagram of the ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 900°C of the present invention.

[0133] Ammonia conversion efficiency test results are as follows Figure 7 As shown, thanks to the uniform particle size and large specific surface area, this sample has an ammonia conversion efficiency of 55.5% at 450°C.

[0134] Example 2

[0135] The difference from Example 1 is that:

[0136] Step 3), change the temperature of the tube furnace to 700°C, the corresponding XRD spectrum is shown in Figure 8 , Figure 8 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 700° C. No raw material peak or intermediate product appears in the XRD spectrum, indicating that the Ru / CeO2 catalyst is successfully synthesized, but the intensity of the diffraction peak is relatively low.

[0137] See also Fig. 9 , Fig. 9This is a SEM image of the Ru / CeO2 catalyst synthesized at 700° C. The SEM image shows that the sample synthesized at 700° C. is a mixture of irregular flaky particles and spherical particles, which affects the conversion rate of ammonia.

[0138] See also Fig.10 , Fig.10 This is a diagram of the ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 700°C of the present invention.

[0139] Ammonia conversion efficiency test results are as follows Fig.10 As shown, the test process is consistent with the method of Example 1. Although this sample has the highest comparative area, it has a large number of irregular flaky particles. Under the same ammonia flow rate, ammonia will quickly pass through the sample surface, greatly reducing the time for reaction with the catalyst, resulting in a decomposition efficiency of only 28.35% at 450°C.

[0140] Example 3

[0141] The difference from Example 1 is that:

[0142] Step 3), change the temperature of the tube furnace to 800°C, the corresponding XRD spectrum is shown in Fig.11 , Fig.11 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 800° C. No raw material peak or intermediate product appears in the XRD spectrum, indicating that the Ru / CeO2 catalyst is successfully synthesized, but the intensity of the diffraction peak is relatively low.

[0143] See also Fig.12 , Fig.12 This is a SEM image of the Ru / CeO2 catalyst synthesized at 800° C. The SEM image shows that the sample synthesized at 800° C. is a sphere with a large particle size span, and there are a small amount of flaky particles, which causes the catalyst to be stacked more tightly during filling, and ammonia will pass through the catalyst quickly, shortening the reaction time with the catalyst and affecting the conversion efficiency of ammonia.

[0144] See also Fig.13 , Fig.13 This is a diagram of the ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 800°C of the present invention.

[0145] Ammonia conversion efficiency test results are as follows Fig.13 As shown, the conversion efficiency of ammonia is 37.7% at 450°C.

[0146] Example 4

[0147] The difference from Example 1 is that:

[0148] Step 3), change the temperature of the tube furnace to 1000°C, the corresponding XRD spectrum is shown in Fig.14 , Fig.14 The XRD diffraction pattern of the Ru / CeO2 catalyst synthesized at 1000° C. No raw material peak or intermediate product appears in the XRD spectrum, indicating that the Ru / CeO2 catalyst is successfully synthesized, the intensity of the diffraction peak is high, and the crystallinity is good.

[0149] See also Fig.15 , Fig.15 This is a SEM image of the Ru / CeO2 catalyst synthesized at 1000° C. However, the SEM image shows that the sample synthesized at 1000° C. is a sphere with a large particle size span and agglomerates, resulting in fewer reaction sites, which affects the conversion rate of ammonia.

[0150] See also Fig.16 , Fig.16 This is a graph of the ammonia decomposition conversion efficiency of the Ru / CeO2 catalyst synthesized at 1000°C of the present invention.

[0151] Ammonia conversion efficiency test results are as follows Fig.16 As shown, the test process is consistent with the method of Example 1, and the conversion efficiency of ammonia at 450° C. is 48.75%.

[0152] See Table 1, which shows the specific surface areas of samples at different synthesis temperatures in the embodiments of the present invention.

[0153] Table 1

[0154] Synthesis temperature (℃) 700 800 900 1000 <![CDATA[Specific surface area (m 2 / g)]]> 24.56 18.13 17.05 8.672

[0155] The instantaneous synthesis method and application of a high specific surface area ammonia decomposition catalyst provided by the present invention are introduced in detail above. The principle and implementation mode of the present invention are explained by using specific examples in this article. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the text of the claims, or if they include equivalent structural elements that are not substantially different from the text of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for synthesizing a precious metal / rare earth oxide composite material, characterized in that: The following steps are involved: 1) mixing a rare earth soluble salt, a noble metal soluble salt and a solvent, and allowing the mixture to stand to obtain a precursor solution; 2) The precursor solution obtained in the above step is subjected to carrier gas atomization treatment and then sent to a high-temperature reaction device for reaction to form material powder. After being transmitted by the carrier gas, the material powder enters an electrostatic powder collection device to obtain a precious metal / rare earth oxide composite material.

2. The synthesis method according to claim 1, characterized in that The rare earth soluble salts include rare earth nitrates; The rare earth element in the rare earth soluble salt includes cerium; The noble metal soluble salt comprises a noble metal chloride; The noble metal in the noble metal soluble salt includes ruthenium.

3. The synthesis method according to claim 1, characterized in that The solvent includes one or more of water, methanol and ethanol; The rare earth soluble salt and the noble metal soluble salt are present in a molar ratio of (4-20):1, calculated on the basis of the rare earth element and the noble metal. The mass ratio of the rare earth soluble salt to the solvent is (1-20):

100.

4. The synthesis method according to claim 1, characterized in that The mixing includes sufficient dissolution; The aging time is greater than or equal to 30 minutes; The carrier gas includes one or more of air, hydrogen-argon mixed gas, argon, nitrogen and ammonia.

5. The synthesis method according to claim 1, characterized in that The pressure of the carrier gas is 0.01-0.5 MPa; The flow ratio of the precursor solution to the carrier gas is 1:(740-1600); The high temperature is 700-1000°C.

6. The synthesis method according to claim 1, characterized in that The reaction is specifically an instantaneous reaction; The electrostatic powder collection device includes a high-voltage electrostatic collection device; The voltage of the high-voltage electrostatic collection device is -1 to -30 kV; The obtained noble metal / rare earth oxide composite material is attached to the inner wall of the high-voltage electrostatic collection device.

7. The synthesis method according to claim 1, characterized in that The noble metal / rare earth oxide composite material comprises a noble metal / rare earth oxide catalyst; The noble metal / rare earth oxide composite material has the morphology of hollow spherical particles; The noble metal / rare earth oxide composite material is specifically a composite material in which a noble metal is loaded on a rare earth oxide; The catalyst is specifically an ammonia decomposition catalyst.

8. A synthesis system for instantaneously synthesizing precious metal / rare earth oxide composite materials, characterized in that: include: Pressure drive device; an atomizing device connected to the pressure driving device; A high-temperature closed reaction device connected to the atomization device; An electrostatic powder collection device connected to the closed reaction device.

9. The synthesis system according to claim 8, characterized in that: The pressure driving device is connected to a carrier gas source and a precursor solution source; The outlet of the pressure driving device is connected to the inlet of the atomizing device; The outlet of the atomizing device is connected to the inlet of the high-temperature closed reaction device; The high temperature closed reaction device comprises a tubular furnace; The outlet of the high temperature closed reaction device is connected to the inlet of the electrostatic powder collection device; The electrostatic powder collection device includes a high-voltage electrostatic collection device; The electrostatic powder collecting device is provided with an exhaust gas outlet which is connected to the exhaust gas treatment device.

10. Use of the synthesis method according to any one of claims 1 to 7 or the synthesis system according to any one of claims 8 to 9 in the preparation of catalysts.

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