Supported high-entropy metal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a supported high-entropy metal catalyst as well as a preparation method and application thereof. The supported high-entropy metal catalyst comprises a carrier and an active metal component supported on the carrier, the active metal component at least contains Cu, and simultaneously contains a combination of at least four of Fe, Ni, Co, Mn, Ru, Pt and Pd; in the active metal component, the molar weight of each metal element is 5-50% of the total molar weight of the active metal component; in the supported high-entropy metal catalyst, the mass of the active metal component accounts for 5-30% of the total mass of the supported high-entropy metal catalyst. According to the supported high-entropy metal catalyst provided by the invention, due to the combination of various elements, the system entropy is increased, and the metal activity and selectivity are modulated through the interaction of electrons among metals, so that the supported high-entropy metal catalyst has excellent reaction activity, stability and heat absorption acting performance in a multi-component alcohol-water reforming reaction.

Description

Technical Field

[0001] The present invention relates to the field of catalytic technology, and more specifically, to a supported high-entropy metal catalyst and a preparation method and application thereof. Background Art

[0002] High-speed aircraft have become the key to international strategic games with their advantages of rapid response, rapid strike, and easy penetration. When an aircraft flies at high speed, the temperature of its outer wall and nearby areas rises rapidly due to shock wave compression, viscous friction, etc. In order to ensure that the internal components work normally within the allowable temperature range and maintain their aerodynamic shape, effective structural thermal protection design must be carried out. Thermal protection technology can be mainly divided into passive and active thermal protection technology. Passive thermal protection using thermal protection materials for insulation or ablative materials for phase change heat absorption is the most widely used aerodynamic heat treatment measure. This type of thermal protection technology has a relatively simple structure, but the preparation process is complex and the cost is high. When the ablative heat protection system is flying at high speed, the material will gradually be ablated as the temperature rises, which can easily change the overall aerodynamic shape and cause accidents. At the same time, due to the weak heat absorption capacity of the passive thermal protection system, the thickness and weight of the required materials in long-flight applications are large, which seriously compresses the payload of the aircraft. Relatively speaking, active thermal protection uses cooling fluids to remove or block heat from the structure through various cooling forms. Compared with passive thermal protection, active thermal protection has the advantages of strong cooling capacity, long-term heating with high-density heat flow, and closed-loop temperature control. Active thermal protection technology is mainly divided into two categories, namely sweat cooling and convection cooling. The commonly used cooling fluid for sweat cooling is water. It borrows the way of sweating heat dissipation of organisms, uses the latent heat of vaporization of water to absorb heat and form a thermal insulation barrier, but the system reliability is poor. Convection cooling is often used in aerospace vehicles or aviation vehicles. Generally, circulating liquid hydrocarbon fuels are used as coolants, and the heat of the structure surface is removed by the physical heat capacity of the fuel. Due to the limitation of fuel coking, this heat absorption mode is only applicable to supersonic flight at speeds below Mach 5. In recent years, with the further improvement of the performance of high-speed aircraft, especially the development of long-endurance high-speed aircraft, its aerodynamic thermal environment has become more complex and harsh. It can be seen that it is of great significance to develop an efficient and reliable method to absorb the aerodynamic heat of high-speed aircraft.

[0003] In view of the above difficulties, based on experimental and theoretical research, it is found that when a mixed solution of alcohol and water is used as a cooling medium for an active thermal protection system, it can absorb a large amount of aerodynamic heat through a physical vaporization reaction. In particular, when a suitable catalyst is contained in the system, it can catalyze a strongly endothermic reforming reaction of alcohol and water. Taking ethanol and water solution as an example, after vaporization, a reforming reaction can generate hydrogen and carbon monoxide (Equation 1), and the gas volume increases three times, and the heat absorbed per mole of fluid reaches 256.8kJ. When the aerodynamic heat temperature reaches 600℃, the heat absorption of pure water is only 3.6MJ / Kg, while the total amount of physical and chemical heat absorption of a mixed solution of ethanol and water under the same conditions can reach more than 6.2MJ / Kg. In addition, the small molecular gases (such as hydrogen and carbon monoxide) produced can be used to do external work. Therefore, based on this green working medium, not only can the heat absorption capacity of the system be improved, but also aerodynamic heat can be converted into chemical energy to realize waste heat utilization, thereby reducing the thickness of the aircraft insulation layer, increasing the system payload, and improving the maneuverability of the aircraft.

[0004] At present, a large number of catalysts for alcohol-water reactions have been reported (Industrial & Engineering Chemistry Research 2021, 60, 89; Chemical Engineering Journal, 2006, 117, 39). However, they are mainly limited to the field of hydrogen production, such as methanol steam reforming to produce hydrogen (Equation 2) and ethanol steam reforming to produce hydrogen (Equation 3). In order to increase the hydrogen production, a large amount of water is added to the raw materials to enhance the water vapor shift reaction (Equation 4; exothermic), resulting in the chemical reaction not only having a lower heat absorption capacity than ethanol reforming to produce synthesis gas (Equation 1) and methanol decomposition reaction (Equation 5), but also a decrease in the gas volume expansion effect, resulting in a decrease in the system's work capacity. In addition, the traditional reforming hydrogen production reaction (reaction of volume increase) is generally carried out at atmospheric pressure to increase the reaction rate and promote hydrogen generation. For the heat-to-work conversion system, in order to improve the work effect, the chemical reaction must be carried out under high pressure conditions (the higher the pressure, the greater the ability to do external work). In the reforming reaction products, H2 / CO or H2 / CO2 coexist in large quantities, and under high pressure conditions, a volume reduction and highly exothermic methanation reaction is prone to occur (Equations 6 and 7), thereby reducing the system's heat absorption and work efficiency.

[0005] In addition to the difference in reaction conditions, previous studies have found that when the type of alcohol is changed, the requirements for the catalyst will also change significantly. For example, for methanol steam reforming reaction (Nature Catalysis, 2022, 5, 99), the main active components of its industrial application catalyst are Cu / Zn / Al, and the working temperature is mainly between 180-300°C; while for ethanol water reforming catalysts, literature research mainly focuses on Ni-based catalysts (Renewable and Sustainable Energy Reviews, 2023, 175, 113184), and due to the high stability of CC bonds, the reaction temperature is generally between 350-600°C. For heat-to-work conversion systems, in order to broaden their effective working temperature range, the required alcohol-water working fluid is often a multi-component composite system, such as promoting the absorption of low-temperature aerodynamic heat through low-carbon alcohol-water reforming in the working fluid, and improving the total heat absorption capacity of the endothermic working fluid through multi-carbon alcohol-water reforming. Traditional reforming catalysts for hydrogen production from two-component alcohol-water systems (methanol / water, ethanol / water) can no longer meet the requirements of heat-to-work conversion systems based on multi-component alcohol-water systems (such as a four-component system of methanol / ethanol / isopropanol / water). In addition, the active components of the catalysts studied in the prior art are mainly single metals (such as Cu and Ni), which are very easy to sinter and grow under high temperature conditions, while bimetallic catalysts often cause metal segregation and even phase separation after long-term reaction, which reduces the performance of the catalyst. Therefore, it is urgent to develop a new type of heat-to-work conversion catalyst suitable for multi-component alcohol-water systems and with excellent reactivity and selectivity.

[0006] Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a supported high-entropy metal catalyst and its preparation method and application. The supported high-entropy metal catalyst provided by the present invention can be used in the heat-to-work conversion system of a high-speed aircraft, and can efficiently catalyze the endothermic chemical reforming reaction of a multi-component alcohol and water system, thereby absorbing "harmful" aerodynamic heat and generating high-temperature and high-pressure small molecule gases (hydrogen, carbon monoxide, etc.) for doing work to generate thrust, thereby realizing aerodynamic thermal management and heat-to-work conversion of high-speed aircraft.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] A supported high-entropy metal catalyst comprises a carrier and an active metal component supported on the carrier; the carrier comprises one or more of alumina, modified alumina, cerium oxide, zinc oxide, zirconium oxide and ZSM-5 molecular sieve; the active metal component is a combination containing at least Cu and at least four of Fe, Ni, Co, Mn, Ru, Pt and Pd; in the active metal component, the molar amount of each metal element is 5% to 50% of the total molar amount of the active metal component, preferably 5% to 35%; in the supported high-entropy metal catalyst, the mass of the active metal component accounts for 5% to 30% of the total mass of the supported high-entropy metal catalyst.

[0010] Optionally, the mass percentage of the noble metal in the active metal component is ≤80%.

[0011] Optionally, the active metal component is a combination containing at least Cu and at least two of Ru, Pt, and Pd and at least two of Fe, Ni, Co, and Mn.

[0012] Optionally, the active metal component is a combination containing at least Cu, Ru, Pt, Pd, and at least one of Fe, Ni, Co, and Mn.

[0013] Optionally, the active metal components include Cu, Ru, Pt, Pd, and Ni; among the Cu, Ru, Pt, Pd, and Ni, the molar ratio or atomic percentage of the Cu element in the active metal is 20% to 60%, and the molar ratio or atomic percentage of the remaining metal elements in the active metal is 10% to 50%.

[0014] The present invention also discloses a method for preparing the supported high entropy metal catalyst as described above, comprising the following steps:

[0015] (1) dissolving an active metal component precursor in water, adding a combustion agent and mixing to obtain a mixed solution;

[0016] (2) adding the carrier to the mixed solution, stirring evenly, heating at 60° C. to 80° C. to evaporate the solvent, and obtaining a precursor;

[0017] (3) The precursor is quickly placed in a muffle furnace preheated to 400°C to 500°C, and the powder is quickly heated to a set temperature within 0s to 10s under an air atmosphere, and the combustion agent undergoes a self-combustion reaction, and the temperature is kept for 10min to 120min. After cooling to room temperature, the powder is taken out of the furnace, and the obtained powder is quickly placed in a tubular furnace preheated to 400°C to 600°C, and the precursor is quickly heated to a set temperature within 0s to 10s under a hydrogen atmosphere, and reduced for 30min to 120min, cooled to room temperature, and then kept in an O2 / N2 mixed atmosphere for 2h to obtain the supported high entropy metal catalyst.

[0018] Optionally, in step (1), the combustion agent includes one or more of glycine, glycerol, citric acid and ethylene glycol; the active metal component precursor is a soluble salt or acid of the active metal component; and the molar ratio of the combustion agent to the total metal ions is 1:1 to 5:1.

[0019] Optionally, in step (3), the preheating temperature of the tube furnace is 500°C to 600°C; the reduction time is 60min to 90min; and the volume fraction of O2 in the O2 / N2 mixed atmosphere is 0.5% to 5%, preferably 0.5% to 1%.

[0020] The present invention also discloses an application of the supported high entropy metal catalyst as described above, or the supported high entropy metal catalyst prepared by the preparation method as described above, in catalyzing an alcohol-water reforming reaction to produce synthesis gas, wherein the application is used in a high-speed aircraft heat-to-power conversion system; in the high-speed aircraft heat-to-power conversion system, the supported high entropy metal catalyst is used to catalyze an endothermic chemical reforming reaction of multi-component alcohol-water, while generating high-pressure fuel gas small molecules to perform work and generate thrust.

[0021] Optionally, the alcohol aqueous solution includes an aqueous solution containing at least one of methanol, ethanol, ethylene glycol, isopropanol and n-propanol.

[0022] Optionally, the temperature of the alcohol-water reforming reaction is 200°C to 800°C, preferably 300°C to 600°C; the reaction pressure of the alcohol-water reforming reaction is 5 bar to 20 bar, preferably 5 bar to 10 bar.

[0023] Optionally, the alcohol aqueous solution includes an aqueous solution containing at least two of methanol, ethanol, ethylene glycol and isopropanol; the mass content of a single alcohol component in the alcohol aqueous solution is ≥10%, and the total mass fraction of alcohol in the alcohol aqueous solution is 20% to 70%.

[0024] Optionally, the high-speed aircraft heat-to-work conversion system includes: a distributed liquid cooling plate 1, a first solenoid valve 2, a heat-to-work conversion plate 3, a gas-liquid storage tank 4, a second solenoid valve 5, a thrust engine 6, a third solenoid valve 7, an oxygen supplementation system 8, and a fourth solenoid valve 9; the heat-to-work conversion plate 3 is a flat plate structure, loaded with a loaded high-entropy metal catalyst as described above, or a loaded high-entropy metal catalyst prepared by the above-mentioned preparation method; the distributed liquid cooling plate 1 is connected to the inlet of the heat-to-work conversion plate 3 through the first solenoid valve 2, the outlet of the heat-to-work conversion plate 3 is connected to the inlet of the gas-liquid storage tank 4, the first outlet of the gas-liquid storage tank 4 is connected to the inlet of the thrust engine 6 through the second solenoid valve 5, the second outlet of the gas-liquid storage tank 4 is connected to the inlet of the distributed liquid cooling plate 1 through the third solenoid valve 7, and the inlet of the oxygen supplementation system 8 is connected to the inlet of the thrust engine 6 through the fourth solenoid valve 9.

[0025] Optionally, the method for using the high-speed aircraft heat-to-work conversion system includes: the liquid cooling medium in the distributed liquid cooling plate 1 is heated and vaporized by aerodynamic heat or heat dissipation of the carrier, and then enters the heat-to-work conversion plate 3 through the first solenoid valve 2; under the action of high-temperature aerodynamic heat and the loaded high-entropy metal catalyst, the vaporized liquid cooling medium undergoes a chemical endothermic reaction and produces high-pressure gas small molecules; the high-pressure gas small molecules and unreacted liquid cooling medium enter the gas-liquid storage tank 4 through a pipeline; the high-pressure gas small molecules can be discharged through the first outlet of the gas-liquid storage tank 4 through the second solenoid valve 5 and the thrust engine 6, and then perform work to generate thrust; the oxygen supplement module 8 mixes the oxidizing atmosphere and the discharged high-pressure gas small molecules through the fourth solenoid valve 9, thereby realizing dual-component work and increasing the system thrust; the unreacted liquid cooling medium can be passed through the second outlet of the gas-liquid storage tank 4 through the third solenoid valve 7 into the distributed liquid cooling plate 1 for recycling.

[0026] Implementing the embodiments of the present invention will have the following beneficial effects:

[0027] 1. Compared with the supported metal catalysts of one, two or three components, the active component in the supported high entropy metal catalyst provided by the present invention contains Cu, and also contains Fe, Ni, Co, Mn, Ru, Pt and Pd, including both non-precious metals and precious metals. Due to the combination of multiple elements, the entropy of the system increases, and the metal activity and selectivity are modulated by the electronic interaction between the metals. Therefore, in the multi-component alcohol-water reforming reaction, it has better reaction activity, stability and endothermic work performance than the supported metal catalysts of one, two or three components.

[0028] 2. The supported high-entropy metal catalyst provided by the present invention is a combination of multiple elements, and the synergistic effect between the active metal components is maximized by regulating the ratio between the elements. At the same time, it cooperates with the carrier. The produced catalyst can efficiently catalyze the alcohol-water reaction to generate synthesis gas, improve the activity and selectivity of the alcohol-water reaction, and thus better meet the demand for endothermic performance in practical applications of high-speed aircraft.

[0029] 3. Compared with the traditional passive insulation method, the heat-to-work conversion system based on this patented catalyst is an active thermal protection technology, which has the advantages of strong cooling capacity, ability to withstand long-term heating with high-density heat flow, and realization of closed-loop temperature control.

[0030] 4. Compared with the active heat insulation method of water sweating, the heat-to-work conversion system based on the catalyst of this patent absorbs heat by coupling physical and chemical reactions. The theoretical maximum heat absorption capacity of the system is more than doubled (>6MJ / kg) compared with the heat absorption of water sweating (~3MJ / kg), which effectively enhances the heat absorption performance of the system and can generate thrust to do work. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is a comparison chart of the heat absorption capacity of methanol and the heat absorption performance of water according to an embodiment of the present invention.

[0032] Figure 2 This is a comparison chart of the ethanol steam reforming endothermic performance and water endothermic performance of an embodiment of the present invention.

[0033] Figure 3 This is a comparison chart of the heat absorption performance of isopropanol steam reforming and water in an embodiment of the present invention.

[0034] Figure 4 This is a graph showing the change in the components of the equilibrium products of methanol decomposition at a pressure of 2 MPa with temperature.

[0035] Figure 5 Schematic diagram of a high-speed aircraft heat-to-power conversion system according to an embodiment of the present invention.

[0036] Among them, 1. distributed liquid cooling plate, 2. first solenoid valve, 3. heat-to-work conversion plate, 4. gas-liquid storage tank, 5. second solenoid valve, 6. thrust engine, 7. third solenoid valve, 8. oxygen supplementation system, 9. fourth solenoid valve. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0038] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0039] Working fluid heat sink test method:

[0040] The current heating reaction is used to evaluate the heat sink of the working fluid, and the energy conservation method is used to calculate the heat sink of the endothermic process.

[0041] Q sink =Q in -Q loss (Equation 8)

[0042] ΔH sink =Q sink / m feed (Equation 9)

[0043] Q sink is the heat absorption power of the working fluid (kW), Q in is the input power (kW) on the reactor during steady-state operation, Q loss is the heat dissipation power of the reactor and electrodes (kW), ΔH sink is the total heat sink generated by the heat absorbing medium (MJ kg -1 ), m feed is the feed mass rate of the endothermic medium (g·s -1 ).

[0044] Example 1

[0045] The maximum theoretical heat sink of methanol was studied by thermodynamic calculation, where the initial temperature of methanol was room temperature (25°C) and the heat absorbed by its complete decomposition into H2 and CO (Equation 2) at different temperatures was as follows: Figure 1 shown.

[0046] Example 2

[0047] Calculate the maximum theoretical heat sink of an ethanol / water solution, where the molar ratio of ethanol to water is 1:1 and the initial temperature is room temperature (25°C). The heat absorbed by the solution at different temperatures for complete decomposition into H2 and CO (Equation 3) is as follows: Figure 2 shown.

[0048] Example 3

[0049] The maximum theoretical heat sink of an isopropanol / water solution, where the molar ratio of isopropanol to water is 1:2 and the initial temperature is room temperature (25°C), is calculated as follows: Figure 3 shown.

[0050] Example 4

[0051] Through thermodynamic calculation, the product components of methanol decomposition reaction at different temperatures when the reaction pressure is 2Mpa are studied. Figure 4 shown.

[0052] From the above calculation results, it can be seen that the methanol decomposition reaction is relatively active. At about 200°C, its theoretical maximum heat sink (decomposition to produce H2 and CO) can exceed the physical heat absorption of water. For ethanol and isopropanol, the theoretical maximum heat sink is equivalent to the physical heat absorption of water at about 250°C and 300°C respectively. In addition, for the three alcohols, their theoretical maximum heat sink increases linearly with temperature after 450°C, indicating that their theoretical conversion rates all reach 100%. However, from the maximum heat sink value, it can be seen that with the increase of the number of carbon atoms, the maximum heat sink value increases significantly. At 500°C, the methanol decomposition heat sink is 5.4MJ / kg, the ethanol / water maximum heat sink is 6.6MJ / kg, and the isopropanol / water maximum heat sink is 7.0MJ / kg. It can be seen that in order to make the endothermic working fluid present a larger heat sink in a wider temperature range, its formula needs to be optimized. In addition, when the reaction pressure is high (2MPa), it can be seen from the equilibrium components of methanol decomposition that its low-temperature products are mainly CH4, H2O and CO2. Only when the temperature is high (>500℃) can H2 and CO be produced. Therefore, regulating the reaction path through catalysts is the key to improving the chemical endothermic capacity of alcohol-water working fluids.

[0053] Example 5

[0054] Preparation of CuFeNiCoMn / Al2O3 catalyst with an active metal mass fraction of 20%:

[0055] First, copper nitrate, iron nitrate, nickel nitrate, cobalt nitrate and manganese nitrate are used as metal precursors, dissolved in deionized water, and a solution with a total metal ion concentration of 0.1 mol / L is prepared, wherein the molar ratio of Cu:Fe:Ni:Co:Mn metals is 1:1:1:1:1, that is, the concentration of the five metal ions is 0.02 mol / L. Then, glycine is added to the solution to obtain a metal ion precursor solution, wherein the molar ratio of glycine to total metal ions is 1:1, that is, the concentration of glycine in the solution is 0.1 mol / L. Weigh 8 g of Al2O3 carrier, then add 34.2 mL of a solution containing metal ions (wherein the total mass of metal is 2 g) to the carrier, place the above suspension in a 60°C water bath, and stir thoroughly until the solution is completely evaporated to obtain a catalyst precursor. Then, the above-mentioned split is placed in a muffle furnace preheated to 500°C, and calcined in an air atmosphere for 30 minutes. Then, the obtained powder is placed in a hydrogen atmosphere tubular furnace preheated to 500°C, reduced for 60 minutes, heating is stopped, and naturally cooled to room temperature; the hydrogen atmosphere of the tubular furnace is replaced with an O2 / N2 mixed gas, wherein the volume fraction of O2 in the mixed gas is 0.5%, and maintained for 2 hours to obtain a loaded high entropy metal catalyst.

[0056] Example 6

[0057] The only difference between this embodiment and embodiment 5 is that the carriers are Al2O3-Si, ZrO2, ZnO, CeO2, and ZSM-5 molecular sieve (H type, Si / Al=15), respectively.

[0058] According to the preparation method of Example 5, CuFeNiCoMn / Al2O3-Si, CuFeNiCoMn / ZrO2, CuFeNiCoMn / ZnO, CuFeNiCoMn / CeO2, and CuFeNiCoMn / ZSM-5 of this example were prepared respectively.

[0059] Example 7

[0060] A CuNiRuPtPd / Al2O3 catalyst with an active metal loading of 20% was prepared.

[0061] The preparation method of this embodiment is different from that of Example 5 only in that the metal components in the metal ion solution are changed to Cu, Ni, Ru, Pt, and Pd, wherein the metal precursors of Cu and Ni are copper nitrate and nickel nitrate, respectively, the precursor of Ru is ruthenium chloride, the precursor of Pt is chloroplatinic acid, and the precursor of Pd is palladium chloride, wherein the molar ratio of Cu:Ni:Ru:Pt:Pd metal is 1:1:1:1:1:1.

[0062] According to the preparation method of Example 5, CuNiRuPtPd / Al2O3 of this example was prepared.

[0063] Example 8

[0064] The only difference between this embodiment and embodiment 7 is that the catalyst of this embodiment is a CuNiRuPtPd / Al2O3 catalyst with an active metal loading of 5%.

[0065] Example 9

[0066] The only difference between this embodiment and embodiment 7 is that the catalyst of this embodiment is a CuNiRuPtPd / Al2O3 catalyst with an active metal loading of 30%.

[0067] Example 10

[0068] The only difference between this embodiment and Embodiment 7 is that: the Cu:Ni:Ru:Pt:Pt in the metal ion precursor solution is changed to 4:1:1:1:1, that is, the molar fraction of Cu ions in the total active metals is 50%; according to the difference in atomic mass, before mixing the catalyst carrier and the metal ion solution, the volume of the metal ion solution is adjusted, and the mass fraction of the total active metals in the catalyst is 20%. The CuNiRuPtPd / Al2O3-50 with an active metal loading of 20% in this embodiment is prepared according to the preparation method of Embodiment 8.

[0069] Embodiment 11

[0070] The only difference between this embodiment and Embodiment 7 is that: the Cu:Ni:Ru:Pt:Pd in ​​the metal ion precursor solution is changed to 0.44:1:1:1:1, that is, the molar fraction of Cu ions in the total active metals is 10%; according to the difference in atomic mass, before mixing the catalyst carrier and the metal ion solution, the volume of the metal ion solution is adjusted, and the mass fraction of the total active metals in the catalyst is 20%. According to the preparation method of Embodiment 8, CuNiRuPtPd / Al2O3-10 with an active metal loading of 10% is prepared in this embodiment.

[0071] Comparative Example 1

[0072] NiRuPtPd / Al2O3 with an active metal loading of 20% was prepared.

[0073] The only difference between this comparative example and Example 7 is that the metal ion precursor solution does not contain Cu ions, and the molar ratio of Ni:Ru:Pt:Pt is 1:1:1:1; based on the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution, and the mass fraction of the total active metal in the catalyst is 20%, thereby obtaining NiRuPtPd / Al2O3 with an active metal loading of 20% in this comparative example.

[0074] Comparative Example 2

[0075] A Cu / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0076] The only difference between this comparative example and Example 5 is that there are only Cu ions in the metal ion precursor solution, wherein the molar concentration of Cu is 0.2 mol / L. Based on the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution, and the mass fraction of the total active metal Cu in the catalyst is 20%. The catalyst obtained in this comparative example is named Cu / Al2O3.

[0077] Comparative Example 3

[0078] A CuNi / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0079] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu and Ni ions, and their molar concentrations are both 0.1 mol / L. Based on the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metals Cu and Ni in the catalyst is 20%. The catalyst obtained in this comparative example is named CuNi / Al2O3.

[0080] Comparative Example 4

[0081] A CuFe / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0082] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu and Fe ions, and their molar concentrations are both 0.1 mol / L. Based on the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metals Cu and Fe in the catalyst is 20%. The catalyst obtained in this comparative example is named CuFe / Al2O3.

[0083] Comparative Example 5

[0084] A CuCo / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0085] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu and Co ions, and their molar concentrations are both 0.1 mol / L. Based on the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metals Cu and Co in the catalyst is 20%. The catalyst obtained in this comparative example is named CuFe / Al2O3.

[0086] Comparative Example 6

[0087] A CuNiRu / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0088] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu, Ni and Ru ions in a molar ratio of 1:1:1. According to the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metal in the catalyst is 20%. The catalyst obtained in this comparative example is named CuNiRu / Al2O3.

[0089] Comparative Example 7

[0090] A CuNiPd / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0091] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu, Ni and Pd ions in a molar ratio of 1:1:1. According to the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metal in the catalyst is 20%. The catalyst obtained in this comparative example is named CuNiPd / Al2O3.

[0092] Comparative Example 8

[0093] A CuNiPt / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0094] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu, Ni and Pt ions in a molar ratio of 1:1:1. According to the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution. The mass fraction of the total active metal in the catalyst is 20%. The catalyst obtained in this comparative example is named CuNiPt / Al2O3.

[0095] Comparative Example 9

[0096] A CuNiRuPt / Al2O3 catalyst with an active metal mass fraction of 20% was prepared.

[0097] The only difference between this comparative example and Example 5 is that the metal ion precursor solution contains only Cu, Ni, Ru and Pt ions, and the molar ratio thereof is 1:1:1:1. According to the difference in atomic mass, the volume of the metal ion solution is adjusted before mixing the catalyst carrier and the metal ion solution, and the mass fraction of the total active metal in the catalyst is 20%. The catalyst obtained in this comparative example is named CuNiRuPt / Al2O3.

[0098] Comparative Example 10

[0099] The only difference between this comparative example and Example 7 is that the Cu:Ni:Ru:Pt:Pd in ​​the metal ion precursor solution is changed to 0.21:1:1:1:1, that is, the molar fraction of Cu ions in the total active metals is 5%; according to the difference in atomic mass, before mixing the catalyst carrier and the metal ion solution, the volume of the metal ion solution is adjusted, and the mass fraction of the total active metals in the catalyst is 20%. According to the preparation method of Example 8, CuNiRuPtPd / Al2O3-5 with an active metal loading of 10% is prepared in this example.

[0100] Comparative Example 11

[0101] The only difference between this comparative example and Example 7 is that the Cu:Ni:Ru:Pt:Pd in ​​the metal ion precursor solution is changed to 1:1:1:1:0.1, that is, the molar fraction of Pd ions in the total active metals is 2.4%; according to the difference in atomic mass, before the catalyst carrier and the metal ion solution are mixed, the volume of the metal ion solution is adjusted, and the mass fraction of the total active metals in the catalyst is 20%. The CuNiRuPtPd catalyst with an active metal loading of 20% in this example is prepared according to the preparation method of Example 8. 2.4 / Al2O3.

[0102] Comparative Example 12

[0103] The only difference between this comparative example and Example 7 is that the active metals only contain Cu, Pt, and Pd, and the molar ratio of Cu:Pt:Pd is changed to 1:1:1; according to the difference in atomic mass, before mixing the catalyst carrier and the metal ion solution, the volume of the metal ion solution is adjusted, and the mass fraction of the total active metal in the catalyst is 20%. The CuPtPd / Al2O3 with an active metal loading of 20% in this comparative example is prepared according to the preparation method of Example 8.

[0104] Example 12

[0105] Figure 5 The schematic diagram of the high-speed aircraft heat-to-work conversion system of the embodiment of the present invention is shown, and the high-speed aircraft heat-to-work conversion system comprises: a distributed liquid cooling plate 1, a first solenoid valve 2, a heat-to-work conversion plate 3, a gas-liquid storage tank 4, a second solenoid valve 5, a thrust engine 6, a third solenoid valve 7, an oxygen supplementation system 8, and a fourth solenoid valve 9; the heat-to-work conversion plate 3 is a flat plate structure, and is loaded with the catalyst as described above; the distributed liquid cooling plate 1 is connected to the inlet of the heat-to-work conversion plate 3 through the first solenoid valve 2, the outlet of the heat-to-work conversion plate 3 is connected to the inlet of the gas-liquid storage tank 4, the first outlet of the gas-liquid storage tank 4 is connected to the inlet of the thrust engine 6 through the second solenoid valve 5, the second outlet of the gas-liquid storage tank 4 is connected to the inlet of the distributed liquid cooling plate 1 through the third solenoid valve 7, and the inlet of the oxygen supplementation system 8 is connected to the inlet of the thrust engine 6 through the fourth solenoid valve 9.

[0106] The method for using the high-speed aircraft heat-to-work conversion system of the present embodiment includes: the liquid cooling medium in the distributed liquid cooling plate 1 is heated and vaporized by aerodynamic heat or heat dissipated by the carrier, and then enters the heat-to-work conversion plate 3 through the first solenoid valve 2. Under the action of high-temperature aerodynamic heat and a catalyst, the vaporized liquid cooling medium undergoes a chemical endothermic reaction and produces high-pressure gas small molecules. The high-pressure gas small molecules and the unreacted liquid cooling medium enter the gas-liquid storage tank 4 through a pipeline. The high-pressure gas small molecules can be discharged through the first outlet of the gas-liquid storage tank 4 through the second solenoid valve 5 and the thrust engine 6, and then work to generate thrust. The oxygen supplementation module 8 mixes the oxidizing atmosphere and the discharged high-pressure gas small molecules through the fourth solenoid valve 9 to achieve dual-component work and improve the system thrust. The unreacted liquid cooling medium can be passed through the second outlet of the gas-liquid storage tank 4 through the third solenoid valve 7 into the distributed liquid cooling plate 1 for recycling.

[0107] Embodiment 13

[0108] This embodiment uses the high-speed aircraft heat-to-power conversion system of Example 12 for simulation, with an ethanol / water mixed solution as the endothermic working fluid, a molar ratio of ethanol to water of 1:1.5 (ethanol mass fraction of 63%), an initial solution temperature of 25°C, a flow rate of 30 g / min, and the catalysts prepared in Examples 5-11 and Comparative Examples 1-8 as reforming catalysts. The endothermic performance of the system is tested, the catalytic decomposition catalyst is 10 g, the reaction temperature is controlled by modulating the current and the heating power, and is set to 200°C, 300°C, 500°C, 600°C and 800°C, respectively, and the reaction pressure is set to 1.0 MPa.

[0109] Embodiment 14

[0110] This embodiment uses the high-speed aircraft heat-to-work conversion system of Embodiment 12 for simulation, the endothermic working fluid is a mixed solution of water / ethanol / isopropanol / methanol, and the corresponding mass fractions are 30%, 40%, 20% and 10%, respectively. The initial temperature of the solution is 25°C, the flow rate is 30g / min, the catalyst is CuNiRuPtPd / Al2O3, and the catalyst mass is 10g. The temperature after the reaction is controlled by adjusting the heating power and is set to 200°C, 300°C, 500°C, 600°C and 800°C, respectively. The reaction pressure is set to 1.0MPa, and the heat absorption of the endothermic working fluid is measured.

[0111] Table 1 Comparison of heat absorption performance of alcohol and water catalyzed by different catalysts

[0112]

[0113]

[0114] According to the results in Table 1, the change of catalyst will significantly affect the heat sink of the working fluid, that is, the heat absorption of the heat-to-work conversion system is closely related to the selection of catalyst components and the ratio between the components. The specific analysis is as follows:

[0115] According to the results of Example 5 and Example 7, when the same carrier (Al2O3) and ethanol-water working fluid are used, the heat absorption performance of CuNiRuPtPd / Al2O3 in Example 7 is better than that of CuFeNiCoMn / Al2O3 in Example 5, indicating that compared with the CuFeNiCoMn / Al2O3 non-precious metal high entropy alloy in Example 5, the active components in the supported high entropy metal catalyst of Example 7 contain both non-precious metals and precious metals. Due to the combination of multiple elements, the entropy of the system increases, and thus in the multi-component alcohol-water reforming reaction, it has better reaction activity, stability and heat absorption performance, and can efficiently catalyze the alcohol-water reaction to generate synthesis gas, indicating that the selection of active metal components of the high entropy alloy will significantly adjust the reaction performance of the catalyst.

[0116] According to the results of Example 5, Example 7 and Comparative Examples 1-9 and Comparative Example 12, when the type of active metal is reduced, the endothermic performance decreases to varying degrees, indicating that the high entropy alloy can improve the activity and selectivity of the alcohol-water reaction, which once again verifies that the selection of the active metal component of the high entropy alloy will significantly adjust the catalyst reaction performance.

[0117] According to the results of Example 5 and Example 6, by comparing different catalyst carriers, it was found that Al2O3 and silicon-modified alumina (Al2O3-Si) have similar performances, and are superior to zirconium oxide (ZrO2), zinc oxide (ZnO), cerium oxide (CeO2), and molecular sieve (ZSM-5) carriers, indicating that the choice of high entropy alloy carrier will significantly adjust the catalyst reaction performance.

[0118] According to the results of Examples 7 to 9, by comparing the loading amounts of different active metal components, it is found that as the loading amount increases, the heat absorption performance also increases, especially when the metal loading amount is 20%, the effect is particularly improved.

[0119] According to the results of Example 7, Example 10-Example 11, and Comparative Example 10-Comparative Example 11, the endothermic performance of the system can be significantly improved by adjusting the ratio between the elements; however, when the Cu content in the catalyst is less than 10%, the low temperature performance of the catalyst decreases significantly, and when the content of one of the five active components is less than 5% (such as CuNiRuPtPd 2.4 / Al2O3 has a Pd content of only 2.4%, and the catalyst performance is basically consistent with that of CuNiRuPt / Al2O3, failing to reflect the excellent characteristics of high entropy catalysts.

[0120] According to the results of Example 14, when the alcohol-water component is adjusted from ethanol / water to a mixed solution of water / ethanol / isopropanol / methanol, a higher heat sink is exhibited in a wide temperature range of 200°C to 800°C, indicating that the high entropy alloy catalyst has excellent activity and selectivity for the multi-component alcohol-water reaction.

[0121] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A supported high entropy metal catalyst, characterized in that The supported high entropy metal catalyst comprises a carrier and an active metal component supported on the carrier; The carrier includes one or more of alumina, modified alumina, cerium oxide, zinc oxide, zirconium oxide and ZSM-5 molecular sieve; The active metal component is a combination containing at least Cu and at least four of Fe, Ni, Co, Mn, Ru, Pt, and Pd; In the active metal component, the molar amount of each metal element is 5% to 50% of the total molar amount of the active metal component; In the supported high entropy metal catalyst, the mass of the active metal component accounts for 5% to 30% of the total mass of the supported high entropy metal catalyst.

2. The supported high entropy metal catalyst according to claim 1, characterized in that The mass percentage of the noble metal in the active metal component is ≤80%.

3. The supported high entropy metal catalyst according to claim 2, characterized in that The active metal component is a combination of at least Cu and at least two of Ru, Pt, and Pd and at least two of Fe, Ni, Co, and Mn.

4. The supported high entropy metal catalyst according to claim 2, characterized in that The active metal component is a combination of at least Cu, Ru, Pt, Pd, and at least one of Fe, Ni, Co, and Mn.

5. The supported high entropy metal catalyst according to claim 4, characterized in that The active metal components include Cu, Ru, Pt, Pd, and Ni; Among the Cu, Ru, Pt, Pd and Ni, the molar ratio of Cu element in the active metal component is 20% to 60%, and the molar ratio or atomic percentage of the other metal elements in the active metal component is 10% to 50%.

6. A method for preparing a supported high entropy metal catalyst as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: (1) dissolving an active metal component precursor in water, adding a combustion agent and mixing to obtain a mixed solution; (2) adding the carrier to the mixed solution, stirring evenly, heating at 60° C. to 80° C. to evaporate the solvent, and obtaining a precursor; (3) The precursor is quickly placed in a muffle furnace preheated to 400°C to 500°C, and the powder is quickly heated to a set temperature within 0s to 10s under an air atmosphere, and the combustion agent undergoes a self-combustion reaction, and the temperature is kept for 10min to 120min. After cooling to room temperature, the powder is taken out of the furnace, and the obtained powder is quickly placed in a tubular furnace preheated to 400°C to 600°C, and the precursor is quickly heated to a set temperature within 0s to 10s under a hydrogen atmosphere, and reduced for 30min to 120min, cooled to room temperature, and then kept in an O2 / N2 mixed atmosphere for 2h to obtain the supported high entropy metal catalyst.

7. The preparation method according to claim 6, characterized in that: In step (1), the combustion agent includes one or more of glycine, glycerol, citric acid and ethylene glycol; the active metal component precursor is a soluble salt or acid of the active metal component; the molar ratio of the combustion agent to the total metal ions is 1:1 to 5:1; In step (3), the preheating temperature of the tubular furnace is 500°C to 600°C; the reduction time is 60min to 90min; and the volume fraction of O2 in the O2 / N2 mixed atmosphere is 0.5% to 5%.

8. Use of a supported high entropy metal catalyst as claimed in any one of claims 1 to 5, or a supported high entropy metal catalyst prepared by the preparation method as claimed in any one of claims 6 to 7 in catalyzing alcohol-water reforming reaction to produce synthesis gas, characterized in that: The application is used in a high-speed aircraft heat-to-work conversion system; In the high-speed aircraft heat-to-power conversion system, the supported high-entropy metal catalyst is used to catalyze the endothermic chemical reforming reaction of multi-component alcohol-water, while producing high-pressure fuel gas small molecules to perform work and generate thrust.

9. The use according to claim 8, characterized in that: The alcohol aqueous solution includes an aqueous solution containing at least one of methanol, ethanol, ethylene glycol, isopropanol and n-propanol; the temperature of the alcohol water reforming reaction is 200° C. to 800° C.; The reaction pressure of the alcohol-water reforming reaction is 5 bar to 20 bar.

10. The use according to claim 9, characterized in that: The alcohol aqueous solution includes an aqueous solution containing at least two of methanol, ethanol, ethylene glycol and isopropanol; The mass content of the single alcohol component in the alcohol aqueous solution is ≥10%, and the total mass fraction of alcohol in the alcohol aqueous solution is 20% to 70%; The temperature of the alcohol-water reforming reaction is 300°C to 600°C; The reaction pressure of the alcohol-water reforming reaction is 5 bar to 10 bar.

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