A precious metal catalyst with mixed valence and a preparation method and application thereof

Abstract

The application provides a noble metal catalyst with mixed valence, which comprises a carrier, noble metal and optional active metal. The content of noble metal in the catalyst is 0.01-20% of the total weight of the carrier, and the valence of the noble metal includes three or more than three of zero valence, one valence, two valence, three valence and four valence in X-ray photoelectron spectroscopy analysis. The application can accurately obtain the valence characteristics and corresponding content proportion of the noble metal on the catalyst surface, and further obtain the influence law of the valence characteristics and corresponding content proportion of the noble metal on the catalyst performance. In addition, the content of the noble metal with different valence on the catalyst surface can be controlled by changing the type, proportion and preparation conditions of the carrier, the additive and the modifier, so that the reaction performance of the catalyst is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and particularly relates to a noble metal catalyst with mixed valence states and a preparation method and application thereof. BACKGROUND

[0002] Supported noble metal catalysts (such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold) are a very important class of catalytic materials in catalytic technology, and are widely used in petrochemical industry, energy utilization and environmental protection and other fields. Studies have shown that the valence state and content of noble metal active centers present on the surface of the carrier have a direct impact on the adsorption, dissociation and other characteristics of the reactant molecules, thereby determining the activity, selectivity and stability of the catalyst.

[0003] Chinese patent CN101862653A discloses an ethyne selective hydrogenation catalyst and a preparation method thereof. The catalyst precursor loaded with a palladium component is ionizing radiation reduced to obtain a catalyst with uniform particle size and elemental active component, which has higher activity and selectivity compared with the catalyst prepared by conventional methods. Chinese patent CN113941325A discloses a noble metal catalyst with specific valence states and a preparation method thereof. Different crystal plane carriers are prepared by a hydrothermal method, and then the noble metal is highly dispersed on the carriers with specific crystal planes by an adsorption method to obtain a noble metal catalyst with uniform positive valence state or uniform zero valence state active component. CN112138652A discloses a preparation method of a single-atom palladium catalyst. Metal palladium salt and titanium dioxide are uniformly dispersed on the surface of graphene oxide; then the mixture is irradiated under stirring, and after washing and freeze-drying, a single-atom palladium catalyst with adjustable Pd 0 / Pd 2+ ratio is obtained.

[0004] The valence of the surface noble metal in the supported noble metal catalyst plays a key role in the performance of the catalyst. Many reactions only exhibit high activity and selectivity to noble metals with specific proportion range and valence state. However, the above studies do not make a detailed division of the distribution and proportion of different valence states of noble metals, but simply classify them as metallic state and oxidized state. The discussion on the relationship and change rule between valence state and performance is also relatively general and vague. This actually easily deviates from or even deviates from the true situation, making it difficult to optimize the preparation method and control the performance of the catalyst in the right direction. Therefore, it is necessary to accurately analyze the valence state and corresponding content of the noble metal on the surface of the catalyst, and to provide a supported noble metal catalyst with specific valence state and proportion range and reaction performance. SUMMARY

[0005] In view of the current technical status, the inventors have found through in-depth research on the deep influence of the active center state of the supported noble metal catalyst on the catalytic performance that the X-ray photoelectron spectroscopy analysis results can clearly reveal the chemical environment of the noble metal on the catalyst surface, thereby better screening the catalyst with excellent performance.

[0006] One of the purposes of the present application is to provide a noble metal catalyst with mixed valence states, comprising a carrier and a noble metal and an optional active metal-supporting metal supported on the surface of the carrier, wherein the valence state of the noble metal comprises three or more of zero valence, monovalence, divalence, trivalence and tetravalence.

[0007] The noble metal catalyst with mixed valence states provided by the present application uses an X-ray electron spectrometer to test the valence state of the noble metal supported on the surface of the carrier, and the obtained X-ray electron spectrogram shows that the noble metal on the surface of the carrier at least comprises three valence states, which are three or more of zero valence, monovalence, divalence, trivalence and tetravalence. Preferably, the valence state of the noble metal comprises zero valence, optionally monovalence, divalence, trivalence and optionally tetravalence.

[0008] According to the embodiments of the present application, the content of the noble metal in zero valence, monovalence, divalence, trivalence and tetravalence is 18-40%, 0-35%, 22-45%, 8-35% and 0-35%, respectively, based on 100% of the total weight of the noble metal, for example, the content of the noble metal in zero valence can be any value or a range between any two values in the range of 18%, 20%, 25%, 30%, 35% and 40%, the content of the noble metal in monovalence can be any value or a range between any two values in the range of 0, 1%, 5%, 10%, 15%, 20%, 25%, 30% and 35%, the content of the noble metal in divalence can be any value or a range between any two values in the range of 22%, 25%, 30%, 35%, 40% and 45%, the content of the noble metal in trivalence can be any value or a range between any two values in the range of 8%, 10%, 15%, 20%, 25%, 30% and 35%, and the content of the noble metal in tetravalence can be any value or a range between any two values in the range of 0, 5%, 10%, 15%, 20%, 25%, 30% and 35%; preferably, the content of the noble metal in zero valence, monovalence, divalence, trivalence and tetravalence is 20-35%, 0-30%, 26-42%, 10-30% and 5-35%, respectively, based on 100% of the total weight of the noble metal.

[0009] According to the embodiments of the present application, the noble metal catalyst with mixed valence states comprises:

[0010] The noble metal is selected from at least one of ruthenium, rhodium, palladium, osmium, iridium and platinum, and is preferably selected from at least one of palladium, platinum and iridium;

[0011] The active metal promoter is selected from at least one of tin, lead, gallium, indium, cerium, iron, tungsten, gold, silver, copper, cobalt;

[0012] The carrier is selected from at least one of titanium oxide, cerium oxide, aluminum oxide, magnesium oxide, calcium oxide, graphene, molecular sieve, preferably at least one of aluminum oxide, cerium oxide, titanium oxide, graphene; the shape of the carrier is not particularly limited, and a carrier component in a commonly used shape in the art can be used, for example, it can be a tooth ball shape, a spherical shape, a columnar shape, a sheet shape, etc.

[0013] The specific surface area of the carrier is 0.1-500 m 2 / g, for example, the specific surface area of the carrier can be 0.1 m 2 / g, 1 m 2 / g, 5 m 2 / g, 10 m 2 / g, 50 m 2 / g, 100 m 2 / g, 150 m 2 / g, 200 m 2 / g, 250 m 2 / g, 300 m 2 / g, 450 m 2 / g, 500 m 2 / g; preferably, the specific surface area of the carrier is 1-200 m 2 / g.

[0014] According to the embodiment of the present application, in the noble metal catalyst with mixed valence state:

[0015] The noble metal is 0.01-20% of the total weight of the carrier, for example, it can be any value selected from the group consisting of 0.01%, 0.03%, 0.05%, 1%, 5%, 10%, 15%, 20% or a range between any two values of the above; preferably, the noble metal is 0.03-5% of the total weight of the carrier;

[0016] The active metal promoter is selected from at least one of tin, lead, gallium, indium, cerium, iron, tungsten, gold, silver, copper, cobalt;

[0017] The second object of the present application is to provide a preparation method of the noble metal catalyst with mixed valence state, comprising: (1) loading a solution containing noble metal compound and active metal compound on the surface of a carrier; (2) drying and calcining to obtain the noble metal catalyst with mixed valence state.

[0018] According to the embodiment of the present application, in step (1) of the preparation method, the loading method is spraying or dipping, one-step or multi-step loading. The spraying and dipping methods can be realized by using the common operation method in the art. One-step loading means loading the mixed solution of noble metal compound and active metal compound on the surface of the carrier by spraying or dipping. Multi-step loading means loading the solution of noble metal compound on the surface of the carrier first, then loading the solution of active metal compound, or loading the solution of active metal compound on the surface of the carrier first, then loading the solution of noble metal compound, or loading the mixed solution of one or more active metal compounds on the surface of the carrier first, then loading the mixed solution of noble metal compound and optional active metal compound. In the actual preparation process, the loading method can be adjusted according to the actual needs.

[0019] According to the embodiment of the present application, a modifier is added to the solution in step (1). Preferably, the modifier is selected from at least one of alkali compounds, preferably at least one of potassium bicarbonate, sodium carbonate, barium hydroxide, ammonia, and ethylenediamine. The amount of the modifier added is 0.01-40% of the total weight of the carrier, for example, any of 0.01%, 0.05%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or a range between any two of the above values. Preferably, the amount of the modifier added is 0.05-20% of the total weight of the carrier.

[0020] The noble metal compound is selected from at least one of soluble noble metal salts, preferably at least one of soluble noble metal chlorides, nitrates, sulfates, acetates, and metal organic compounds.

[0021] The active metal compound is selected from at least one of soluble active metal salts, preferably at least one of soluble active metal chlorides, nitrates, sulfates, acetates, and metal organic compounds.

[0022] The solvent in the solution is selected from at least one of water, alcohol, ether, and acid, preferably at least one of water, methanol, ethanol, isopropyl alcohol, butyl ether, n-pentyl ether, and acetic acid.

[0023] The content of the noble metal in the solution is 0.01-1000 mg / mL, for example, any value among 0.01 mg / mL, 0.05 mg / mL, 1 mg / mL, 10 mg / mL, 50 mg / mL, 100 mg / mL, 200 mg / mL, 500 mg / mL, 800 mg / mL, 1000 mg / mL or a range between any two of the above values; preferably, the content of the noble metal in the solution is 0.05-200 mg / mL.

[0024] The content of the noble metal in the solution is 0.01-1000 mg / mL, for example, any value among 0.01 mg / mL, 0.05 mg / mL, 1 mg / mL, 10 mg / mL, 50 mg / mL, 100 mg / mL, 200 mg / mL, 500 mg / mL, 800 mg / mL, 1000 mg / mL or a range between any two of the above values; preferably, the content of the noble metal in the solution is 0.05-200 mg / mL.

[0025] According to the embodiments of the present application, in the preparation method:

[0026] The drying condition is 60-200 ℃ for 2-24 h, preferably 80-120 ℃ for 4-16 h;

[0027] The calcination condition is 150-900 ℃ for 4-18 h, and the calcination atmosphere is at least one selected from air, helium, argon, nitrogen, hydrogen and carbon monoxide; preferably, the calcination condition is 300-500 ℃ for 6-12 h, and the calcination atmosphere is at least one selected from air, argon, nitrogen, hydrogen and carbon monoxide.

[0028] The third object of the present application is to provide the use of the noble metal catalyst with mixed valence state or the noble metal catalyst with mixed valence state prepared by the above method in hydrogenation reaction.

[0029] The noble metal catalyst with mixed valence state has higher catalytic activity, can better promote the hydrogenation reaction, improve the conversion rate of the reaction, and can inhibit the generation of byproduct, and can also adjust the distribution of noble metal valence state to achieve the purpose of precise control of the reaction according to the actual needs. For example, for Pd supported molecular sieve catalyst used for purifying indoor formaldehyde, compared with high valence state Pd 2+ , metal state Pd 0 is more conducive to the activity of oxygen and the conversion of intermediate product formate, while inhibiting the generation of byproduct carbonate; and for Pd / CeO2 catalyst used for CO oxidation, only Pd 4+For example, only catalysts with a certain valence state of noble metal can exhibit high reactivity at low temperature; for another example, the main side reaction of chloronitrobenzene hydrogenation is the cleavage of carbon-chlorine bond, which is extremely sensitive to the valence state and coordination of metal (Pt) center, and needs to be precisely regulated to achieve the desired catalytic effect.

[0030] Compared with the prior art, the present application has the beneficial effect that:

[0031] 1、The supported noble metal catalyst and X-ray photoelectron spectroscopy feature of the present application can obtain the valence state of noble metal on the catalyst surface in detail, determine the valence state type and content of noble metal on the surface, and ensure that the catalyst has specific catalytic performance.

[0032] 2、The supported noble metal catalyst and preparation method of the present application can realize precise regulation of the valence state of noble metal on the catalyst surface by changing the type and synthesis conditions of the additive, carrier and modifier, combined with X-ray photoelectron spectroscopy analysis, to achieve the purpose of improving the performance of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst A1.

[0034] Figure 2 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst A2.

[0035] Figure 3 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst A3.

[0036] Figure 4 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst A4.

[0037] Figure 5 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst A5.

[0038] Figure 6 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst B1.

[0039] Figure 7 X-ray photoelectron spectrogram of the surface noble metal Pd of catalyst B2. DETAILED DESCRIPTION

[0040] The present application will be described in detail below with specific examples, and it is necessary to point out that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application, and some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still fall within the protection scope of the present application.

[0041] The testing instruments and conditions used in this embodiment are as follows:

[0042] Valence state of precious metals: obtained using X-ray photoelectron spectroscopy (ESCALAB 250).

[0043] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0044] Example 1

[0045] Immerse 300g of a substance with a specific surface area of ​​120m² in 200ml of an aqueous solution containing 3g of potassium bicarbonate. 2 / g of toothed spherical alumina support was dried at 100℃ for 8h and calcined at 350℃ in air atmosphere for 8h to obtain modified Al2O3 support; then it was impregnated in 200ml of palladium chloride aqueous solution containing 0.15g of palladium, dried at 100℃ for 8h and calcined at 500℃ for 8h to obtain catalyst A1.

[0046] Example 2

[0047] A 150 ml aqueous solution containing 3 g potassium hydroxide, 0.16 g palladium chloride, and 0.33 g silver nitrate was used as an aqueous solution impregnation method on 300 g of material with a specific surface area of ​​15 m². 2 / g of toothed spherical alumina support was dried at 100℃ for 12h and calcined at 400℃ in a mixed atmosphere of hydrogen and argon (volume ratio 1:4) for 10h to obtain catalyst A2.

[0048] Example 3

[0049] A 50ml ethanol solution of cobalt acetate containing 1.0g of cobalt was sprayed onto 500g of a material with a specific surface area of ​​80m². 2 / g of spherical titanium dioxide support was dried at 100℃ and calcined at 550℃ to obtain cobalt-modified titanium dioxide support; then, 200ml of an aqueous solution of palladium acetate containing 2.5g sodium hydroxide and 0.225g palladium was impregnated in the cobalt-modified titanium dioxide support, dried at 100℃ for 5h, and calcined at 550℃ under nitrogen atmosphere for 10h to obtain catalyst A3.

[0050] Example 4

[0051] 180 ml of a palladium sulfate aqueous solution containing 0.11 g palladium was sprayed onto 200 g of a material with a specific surface area of ​​50 m². 2 / g of columnar cerium oxide support was dried at 150℃ to obtain a palladium / cerium oxide intermediate; then, 180ml of an aqueous solution of indium sulfate containing 2.5g sodium hydroxide and 0.18g indium was impregnated in the palladium / cerium oxide intermediate, dried at 150℃ for 6h, and calcined at 600℃ in a carbon monoxide atmosphere for 10h to obtain catalyst A4.

[0052] Example 5

[0053] A solution of chloroauric acid containing 0.2 g of gold in 210 ml of isopropyl alcohol was sprayed onto 400 g of a cylindrical alumina support having a specific surface area of 30 m 2 / g, dried at 120°C and calcined at 900°C to obtain a gold-modified alumina support; a solution of palladium nitrate containing 0.25 g of palladium, gallium nitrate containing 0.1 g of gallium in 120 ml of water was impregnated onto the gold-modified alumina support, and a solution of barium hydroxide containing 1.5 g of barium was sprayed thereon, dried at 100°C for 6 h and calcined at 400°C in air for 8 h to obtain catalyst A5.

[0054] Comparative Example 1

[0055] A solution of palladium chloride containing 0.15 g of palladium in 150 ml of water was impregnated onto 300 g of a denticular-spherical alumina support having a specific surface area of 120 m 2 / g, dried at 230°C for 8 h and calcined at 1000°C in air for 8 h to obtain catalyst B1.

[0056] Comparative Example 2

[0057] A solution of palladium chloride containing 0.16 g of palladium and silver nitrate containing 0.33 g of silver in 150 ml of water was impregnated onto 300 g of a denticular-spherical alumina support having a specific surface area of 15 m 2 / g, dried at 100°C for 12 h and calcined at 400°C in a mixed gas of hydrogen and argon (volume ratio 1:4) for 10 h to obtain catalyst B2.

[0058] X-ray photoelectron spectroscopy test

[0059] The catalysts of the examples and comparative examples were characterized by X-ray photoelectron spectroscopy using an X-ray photoelectron spectrometer (ESCALAB 250). A sample surface flake of about 30 mg was fixed on a sample table with conductive glue and placed in a sample chamber which was vacuumed to an air pressure of 10 -6 Pa, and specific analysis points were determined for fine scanning analysis of the Pd element. The obtained spectral data were then charge-corrected using the binding energy (284.8 eV) of organic contamination C1s as a reference, and Shirley Method background removal was used, and then Pd 3d spectral data were peak-fitted. The peak-fitting rules were: (1) the 3d 5 / 2 peak center ranges corresponding to zero-valence, divalent, trivalent and quadrivalent Pd were set to 335.40-335.90 eV, 336.10-336.55 eV, 336.80-337.40 eV and 337.70-338.20 eV, respectively, and (2) the peak center of 3d 3 / 2 was set to be in its corresponding 3d 5 / 2(3) 3d 5 / 2 and 3d 3 / 2 Peak area ratio is 3:2; (4) half-width range is set to 0.5eV-2.5eV, (5) Lorentz / Gaussian mixed ratio is set to 20%-35%, and asymmetric tailing mixed ratio, height and tail index are set to 100%, 0% and 0 respectively. The measured results are shown in Table 1.

[0060] Table 1. Catalyst surface different valence content results

[0061]

[0062] From Table 1, it can be seen that the zero-valent and divalent Pd content of the catalysts A1-A5 prepared in the embodiments of the present application are higher than those of the catalysts B1 and B2, while the sum of the trivalent and tetravalent Pd content is lower than that of the catalysts B1 and B2. This indicates that the catalysts B1 and B2 have more high-valence Pd on the surface, and the interaction between this type of Pd and the carrier is stronger, and it is more difficult to be reduced to elemental state or even low-valent state.

[0063] Catalyst performance evaluation

[0064] Taking carbon fraction as an example, the catalytic performance of the catalysts obtained in Examples 1-5 and Comparative Examples 1-2 was evaluated.

[0065] 200ml of the catalysts of the examples and comparative examples were loaded into a stainless steel pipe reactor, and after replacement with nitrogen, carbon fraction raw material was introduced into the reactor, and the composition (molar fraction) of the reaction raw material was: hydrogen 11.42%, methane 0.82%, ethane 11.01%, ethylene 60.79%, propane 0.86%, propylene 14.09%, propyne 0.36%, allene 0.29%, acetylene 0.36%, carbon monoxide 650ppm. The reaction pressure was 2MPa, the reactor inlet temperature was 55-85℃, the space velocity was 25000h -1 The calculation method of the conversion rate and selectivity of carbon fraction hydrogenation reaction of each catalyst was:

[0066]

[0067]

[0068] The catalytic reaction evaluation results of the catalysts of Examples 1-5 and Comparative Examples 1-2 are shown in Table 2.

[0069] Table 2. Carbon fraction hydrogenation reaction evaluation results

[0070] Catalyst Exit acetylene Inlet temperature Selectivity A1 Less than 10 ppm 75℃ 57％ A2 Less than 10 ppm 71℃ 52％ A3 Less than 10 ppm 74℃ 64％ A4 Less than 10 ppm 69℃ 61％ A5 Less than 10 ppm 66℃ 68％ B1 Less than 10 ppm 83℃ 32％ B2 Less than 10 ppm 78℃ 40％

[0071] As can be seen from Table 2, in the reaction of carbon dihydrogen to ethylene, the selectivity of the catalysts A1-A5 of the present application to ethylene is higher and the required inlet temperature is lower than that of the comparative catalysts, while the outlet acetylene is less than 10 ppm. In combination with the results of Table 1, it can be seen that the main reason for the performance of the catalysts A1-A5 being superior to that of B1 and B2 is that the number of Pd in low valence state on the surface of the catalysts A1-A5 is more (the exposed active sites are also more). In addition, the performance of the catalysts of different examples also has obvious differences. This shows that the performance of the catalysts can be directionally regulated by changing the valence state of the noble metal on the surface, and different auxiliary metals and preparation methods can also significantly change the catalytic performance. The differences in the micro properties of the catalysts can be clearly distinguished by X-ray photoelectron spectroscopy technology, and the optimized preparation of the catalysts can be guided.

Claims

1. A noble metal catalyst having mixed valence states, comprising a support and a noble metal and optionally a co-active metal supported on the surface of the support, wherein, The valence state of the precious metal includes three or more of zero, mono, di, tri, and tetravalent; based on the total weight of the precious metal as 100%, the contents of the zero-valent, monovalent, divalent, trivalent, and tetravalent precious metals are 18-40%, 0-35%, 22-45%, 20-35%, and 0-35%, respectively; the precious metal is selected from at least one of ruthenium, rhodium, palladium, osmium, iridium, and platinum; the carrier is selected from at least one of titanium oxide, cerium oxide, aluminum oxide, magnesium oxide, calcium oxide, graphene, and molecular sieve; and the auxiliary active metal is selected from at least one of tin, lead, gallium, indium, cerium, iron, tungsten, gold, silver, copper, and cobalt.

2. The noble metal catalyst according to claim 1, characterized in that, Based on the total weight of precious metals as 100%, the contents of zero-valent, monovalent, divalent, trivalent, and tetravalent precious metals are 20-35%, 0-30%, 26-42%, 20-30%, and 5-35%, respectively.

3. The noble metal catalyst according to claim 1, characterized in that, The precious metal is selected from at least one of palladium, platinum, and iridium; and / or, The carrier is selected from at least one of alumina, cerium oxide, titanium oxide, and graphene; and / or, The specific surface area of ​​the carrier is 0.1~500m². 2 / g.

4. The noble metal catalyst according to claim 3, characterized in that, The specific surface area of ​​the carrier is 1~200m². 2 / g.

5. The noble metal catalyst according to claim 1, characterized in that, The precious metal constitutes 0.01% to 20% of the total weight of the carrier by mass percentage; and / or, The active metal, by mass percentage, accounts for 0-40% of the total weight of the carrier.

6. The noble metal catalyst according to claim 5, characterized in that, The precious metal constitutes 0.03-5% of the total weight of the carrier by mass percentage; and / or, The active metal, by mass percentage, accounts for 0-30% of the total weight of the carrier.

7. A method for preparing a noble metal catalyst having a mixed valence state as described in any one of claims 1 to 6, comprising: (1) A solution containing a noble metal compound and a co-active metal compound is loaded onto the surface of a support, and a modifier is added to the solution. The modifier is selected from at least one of potassium bicarbonate, sodium carbonate, barium hydroxide, ammonia, and ethylenediamine; (2) After drying and calcination, the noble metal catalyst with mixed valence states is obtained.

8. The preparation method according to claim 7, wherein in step (1): The loading method is spraying or dipping, one-step or multi-step loading; and / or, The noble metal compound is selected from soluble noble metal salts; and / or, The co-active metal compound is selected from soluble co-active metal salts; and / or, The solvent in the solution is selected from at least one of water, alcohol, ether, and acid; and / or, The noble metal content in the solution is 0.01~1000 mg / mL; and / or, The content of the co-active metal in the solution is 0.01~1000 mg / mL.

9. The preparation method according to claim 8, wherein in step (1): The solvent in the solution is selected from at least one of water, methanol, ethanol, isopropanol, butyl ether, n-pentyl ether, acetic acid, and oxalic acid; and / or, The noble metal content in the solution is 0.05~200 mg / mL; and / or, The content of the co-active metal in the solution is 0.05~200 mg / mL.

10. The preparation method according to claim 8, characterized in that, The modifier, by weight percentage, is added in an amount of 0.01 to 40% of the total weight of the carrier; and / or, The noble metal compound is selected from at least one of the following: chlorides, nitrates, sulfates, acetates, and organometallic compounds of soluble noble metals; and / or, The co-activating metal compound is selected from at least one of the following: chlorides, nitrates, sulfates, acetates, and organometallic compounds of soluble co-activating metals.

11. The preparation method according to claim 10, characterized in that, The amount of the modifier added, by weight percentage, is 0.05 to 20% of the total weight of the carrier.

12. The preparation method according to claim 7, characterized in that, The drying conditions are: drying at 60~200℃ for 2~24 hours; and / or, The calcination conditions are: calcination at 150~900℃ for 4~18h, and the calcination atmosphere is selected from at least one of air, helium, argon, nitrogen, hydrogen, and carbon monoxide.

13. The preparation method according to claim 12, characterized in that, The drying conditions are: drying at 80~120℃ for 4~16 hours; and / or, The calcination conditions are: calcination at 300~600℃ for 6~12h, and the calcination atmosphere is selected from at least one of air, argon, nitrogen, hydrogen, and carbon monoxide.

14. The application of a noble metal catalyst having a mixed valence state as described in any one of claims 1 to 6, or a noble metal catalyst having a mixed valence state obtained by the preparation method described in any one of claims 7 to 13, in a hydrogenation reaction.

Images