Precious metal supported amorphous metal oxide catalytic material, and preparation method and application thereof

Abstract

The application relates to the field of photocatalytic conversion, and discloses a noble metal-loaded amorphous metal oxide catalytic material and a preparation method and application thereof. The catalytic material comprises a group VIII amorphous metal oxide and ruthenium; the group VIII amorphous metal oxide is at least one selected from amorphous nickel oxide, amorphous cobalt oxide and amorphous iron oxide; and the content of the ruthenium is 0.1-6.5% in mass based on the total amount of the catalytic material in terms of elements. The catalytic material provided by the application simultaneously contains noble metal and amorphous metal oxide, the rich coordination unsaturated structure of which can provide surface reaction active sites and improve reaction efficiency.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic conversion, specifically to a noble metal-supported amorphous metal oxide catalytic material, its preparation method, and its application. Background Technology

[0002] Research on long-distance hydrogen transportation is being conducted both domestically and internationally. Currently, the three most widely studied methods for long-distance hydrogen transportation internationally are pipeline hydrogen transport, liquid hydrogen storage and transportation, and chemical storage and transportation. Among these, the media used for chemical hydrogen storage and transportation mainly include organic liquids, ammonia, and methanol. According to a report by the International Energy Agency, using ammonia as a hydrogen storage medium has a significantly lower overall cost than using liquid hydrogen and organic liquid hydrogen carriers.

[0003] In the ammonia storage and transportation industry chain, ammonia synthesis and transportation technologies are relatively mature. Therefore, developing efficient ammonia decomposition technology is key to realizing the "hydrogen-ammonia-hydrogen" hydrogen storage and transportation process. Thermodynamic calculations show that the equilibrium conversion rate of ammonia decomposition can reach 99% at atmospheric pressure and 400℃. However, the high activation energy and slow kinetics of ammonia decomposition limit its practical application. Developing efficient ammonia decomposition catalysts is crucial for the industrialization of hydrogen production from ammonia decomposition. Currently, commonly used catalytic conversion pathways mainly include thermocatalysis, photocatalysis, and electrocatalysis. Traditional thermocatalytic methods have high energy consumption, which is not conducive to large-scale applications. Utilizing solar energy to assist catalytic processes to produce hydrogen is expected to reduce dependence on fossil fuels. However, conventional semiconductor materials can only utilize ultraviolet light and a small portion of visible light, resulting in limited solar energy utilization efficiency. Amorphous semiconductor materials, due to their unique band-tailed absorption, can effectively capture near-infrared sunlight. Simultaneously, their rich coordination-unsaturated structures provide surface reactive sites, further improving reaction efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of low ammonia decomposition conversion rate in the prior art, and to provide a noble metal supported amorphous metal oxide catalytic material, its preparation method and application. The catalytic material contains both noble metal and amorphous metal oxide, and its rich coordination unsaturated structure can provide surface reaction active sites to improve reaction efficiency.

[0005] To achieve the above objectives, the first aspect of the present invention provides a noble metal supported amorphous metal oxide catalytic material, wherein the catalytic material comprises a group VIII amorphous metal oxide and ruthenium; the group VIII amorphous metal oxide is selected from at least one of amorphous nickel oxide, amorphous cobalt oxide, and amorphous iron oxide; based on the total amount of the catalytic material, the ruthenium content is 0.1-6.5% by mass.

[0006] Preferably, the mass ratio of the amorphous cobalt oxide to the sum of the amorphous nickel oxide and the amorphous iron oxide is 1-5:1, more preferably 1.2-3:1.

[0007] Preferably, the catalytic material contains oxygen vacancies.

[0008] Preferably, the oxygen defect content in the catalytic material is 2-10%, more preferably 4-6%.

[0009] A second aspect of this invention provides a method for preparing a noble metal-supported amorphous metal oxide catalytic material, wherein the method includes the following steps:

[0010] S1. An alcoholic solution A containing a Group VIII metal precursor is reacted with a carbonate solution B to obtain the reaction product.

[0011] S2. In the presence of a reducing agent, the alcohol solution C containing the reaction product of step S1 is reduced with the ruthenium precursor, and then dried to obtain the noble metal catalyst.

[0012] The Group VIII metal is selected from at least one of iron, cobalt, and nickel;

[0013] The amount of the ruthenium precursor used is such that, based on the total amount of the catalytic material, the ruthenium content in the prepared noble metal catalytic material is 0.1-6.5% by mass (based on the total amount of the catalytic material).

[0014] The conditions for the contact reaction in step S1 and the reduction reaction in step S2 are independent of each other: temperature of 5-40℃ and time of 0.5-24h.

[0015] The third aspect of this invention provides a noble metal-supported amorphous metal oxide catalytic material prepared by the preparation method described in the second aspect.

[0016] The fourth aspect of this invention provides the application of the noble metal-supported amorphous metal oxide catalytic material described in the first or third aspect in the photocatalytic ammonia decomposition to produce hydrogen.

[0017] The catalytic material provided by this invention introduces amorphous metal oxides, which have abundant coordination unsaturated structures. This facilitates the provision of more growth sites for noble metals and promotes their dispersion. At the same time, it promotes the adsorption and activation of reactant molecules, thereby improving the ammonia decomposition activity.

[0018] The method provided by this invention prepares amorphous photocatalytic materials using a room-temperature liquid-phase synthesis method. The materials can effectively capture near-infrared sunlight by utilizing their unique tailed absorption, and their rich coordination unsaturated structure can provide surface reactive sites, further improving the reaction efficiency.

[0019] The method provided by this invention has a simple preparation process, good repeatability, and is easy to scale up for production. Attached Figure Description

[0020] Figure 1 This is the X-ray diffraction pattern of the catalytic material in Example 1 of this invention;

[0021] Figure 2 This is the absorbance curve of the catalytic material in Example 1 of the present invention. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of the present invention provides a noble metal supported amorphous metal oxide catalytic material, wherein the catalytic material comprises a group VIII amorphous metal oxide and ruthenium; the group VIII amorphous metal oxide is selected from at least one of amorphous nickel oxide, amorphous cobalt oxide and amorphous iron oxide; based on the total amount of the catalytic material, the content of ruthenium is 0.1-6.5% by mass.

[0024] In this invention, preferably, based on the total amount of catalytic material, the ruthenium content is 2-5% by mass (elementally).

[0025] In this invention, preferably, the Group VIII amorphous metal oxide is amorphous nickel oxide, amorphous cobalt oxide, or amorphous iron oxide. The advantage of this preferred embodiment is that it utilizes the rich interfaces of different metal oxides to provide more surface active centers, while simultaneously optimizing the activation ability of the metal centers for ammonia molecules, thereby improving reactivity.

[0026] In this invention, preferably, the mass ratio of the sum of amorphous cobalt oxide, amorphous nickel oxide, and amorphous iron oxide is 1-5:1, more preferably 1.2-3:1. Specifically, the mass ratio of the sum of amorphous cobalt oxide, amorphous nickel oxide, and amorphous iron oxide refers to the ratio of the content of amorphous cobalt oxide to (the content of amorphous nickel oxide + the content of amorphous iron oxide). In this invention, the combination of amorphous cobalt oxide, amorphous nickel oxide, and amorphous iron oxide has the advantages of strong synergistic effect between metal oxides, optimal matching degree, and highest defect concentration. When the content of the sum of amorphous cobalt oxide, amorphous nickel oxide, and amorphous iron oxide is higher than the above range, elemental segregation defects are prone to occur; when the content of the sum of amorphous cobalt oxide, amorphous nickel oxide, and amorphous iron oxide is lower than the above range, defect formation is not conducive.

[0027] In this invention, preferably, based on the total amount of Group VIII amorphous metal oxides, the content of amorphous cobalt oxide is 50-80% by mass, the content of amorphous nickel oxide is 7.5-25% by mass, and the content of amorphous iron oxide is 7.5-25% by mass.

[0028] In this invention, the content of each component in the catalytic material is calculated and measured by the amount of feed. Co is calculated as CoO, Fe as Fe2O3, Ni as NiO, and Ru as an element.

[0029] The catalytic material provided in this invention has an excellent specific surface area, enabling it to provide photocatalytic performance. Preferably, the specific surface area of ​​the catalytic material is 200-800 cm². 2 / g, preferably 600-800cm 2 / g.

[0030] In this invention, the specific surface area of ​​the catalytic material is measured by BET nitrogen isothermal adsorption-desorption curve.

[0031] In this invention, it should be noted that the amorphous metal oxide refers to the state in which the atoms of a solid material are arranged with short-range order and long-range disorder.

[0032] In this invention, preferably, the catalytic material does not exhibit characteristic diffraction peaks in the 10º-90º region of the X-ray diffraction pattern, and the catalytic material exhibits amorphous morphological characteristic diffraction peaks in the 30º-40º region of the X-ray diffraction pattern. In this invention, the amorphous morphological characteristic diffraction peaks have the conventional definition of amorphous structural materials in the art, such as... Figure 1 As shown, the catalytic material provided by the present invention exhibits amorphous packaged diffraction peaks known as "bun peaks" in the range of 30º-40º. "Bun peaks" have the conventional definition in the art, and the appearance of amorphous packaged characteristic diffraction peaks indicates that the catalytic material contains an amorphous structure.

[0033] In this invention, preferably, the amorphous metal oxide contains oxygen vacancies. Oxygen vacancies can act as electron donors, increasing the local electron concentration around the active site, and can also act as active sites, promoting the adsorption and activation of the reactant NH3 molecules.

[0034] In this invention, oxygen defects in the catalytic material refer to oxygen content in the catalytic material being less than its theoretical stoichiometric content. Oxygen defects are measured by X-ray photoelectron spectroscopy analysis. The specific test conditions are: using high-resolution O1s spectrum peak fitting to determine lattice oxygen and defect oxygen signals, thereby calculating the molar percentage of oxygen defects as: defect oxygen / (defect oxygen + lattice oxygen) × 100%.

[0035] In this invention, preferably, the oxygen defect content in the catalytic material is 2-10%, more preferably 4-6%. The advantage of this preferred embodiment is that the catalytic material has a preferred electron concentration and a large number of surface active sites. When the oxygen defect content is outside this range, too few oxygen defects result in a limited number of active sites, while too high an oxygen defect concentration affects lattice stability, leading to decreased material stability and reduced reactivity.

[0036] In this invention, preferably, the catalytic material exhibits photocatalytic activity in the visible and near-infrared light range of 500-1000 nm, meaning that the catalytic material has band-tailed absorption in a long wavelength range. This indicates that the catalytic material has light absorption capacity and catalytic activity in the visible and near-infrared light range of 500-1000 nm. In this invention, band-tailed absorption has the conventional definition in the art; the wider the visible and near-infrared light range, the better the catalytic performance of the catalytic material. In this invention, the band-tailed absorption is measured using a UV-Vis spectrophotometer. The specific test conditions are: using an integrating sphere to test the absorbance of the solid powder sample.

[0037] A second aspect of this invention provides a method for preparing a noble metal-supported catalytic material, wherein the method includes the following steps:

[0038] S1. The dispersion A containing the Group VIII metal precursor and the first alcohol is reacted with a precipitant to obtain a solid reaction product.

[0039] S2. In the presence of a reducing agent, a dispersion B containing the solid reaction product of step S1 and the second alcohol is reduced with a ruthenium precursor and then dried to obtain a noble metal supported amorphous metal oxide catalytic material.

[0040] The Group VIII metal is selected from at least one of iron, cobalt, and nickel;

[0041] The amount of the ruthenium precursor used is such that, based on the total amount of the catalytic material, the ruthenium content in the prepared noble metal-supported amorphous metal oxide catalytic material is 0.1-6.5% by mass (based on the total amount of the catalytic material).

[0042] The conditions for the contact reaction in step S1 include: a temperature of 5-40℃ and a time of 0.5-24h.

[0043] The method provided by this invention uses a room-temperature liquid-phase synthesis method to prepare catalytic materials without high-temperature conditions. The preparation method is simple, has good reproducibility, and the composition and structure of the catalyst are relatively easy to control. In addition, it has low energy consumption and is beneficial to industrial production. At the same time, the introduction of a Group VIII metal and the noble metal ruthenium increases the active sites and improves the activity of the catalytic material.

[0044] In this invention, preferably, the amount of the ruthenium precursor is such that, based on the total amount of the catalytic material, the ruthenium content in the obtained noble metal supported amorphous metal oxide catalytic material is 2-5% by mass.

[0045] In this invention, preferably, in step S1, the Group VIII metal is iron, cobalt, or nickel. This invention improves reaction efficiency by selecting a Group VIII metal in combination with the noble metal ruthenium and introducing a non-noble metal to increase active sites.

[0046] In this invention, there is no particular limitation on the type of Group VIII metal precursor. Preferably, in step S1, the Group VIII metal precursor is selected from soluble compounds of various metals, and more preferably at least one of nitrates, chlorides, and sulfates, such as cobalt nitrate, basic cobalt carbonate, ferric nitrate, ferric chloride, nickel nitrate, etc.

[0047] In this invention, by controlling the mass ratio of the cobalt precursor to the sum of the nickel and iron precursors, the components in the prepared catalytic material synergistically improve the catalytic performance. Preferably, the mass ratio of the cobalt precursor (calculated as oxide) to the sum of the nickel and iron precursors (calculated as oxides) is 1-5:1, more preferably 1.2-3:1.

[0048] In this invention, preferably, the dispersion A is prepared by dispersing a Group VIII metal precursor in a first alcohol. By dispersing the Group VIII metal precursor in the first alcohol, hydrolysis of the Group VIII metal precursor is avoided, ensuring the smooth progress of subsequent reactions.

[0049] In this invention, the type of the first alcohol is not particularly limited, as long as it can facilitate the dispersion of Group VIII metal precursors and prevent the hydrolysis of Group VIII metal precursors. Preferably, the first alcohol is a monohydric alcohol and / or a polyhydric alcohol, and more preferably, it is selected from at least one of methanol, ethanol, and ethylene glycol. In this invention, the polyhydric alcohol refers to an alcohol containing two or more hydroxyl groups, and the specific type is not particularly limited.

[0050] In this invention, there is no particular limitation on the amount of the Group VIII metal precursor and the first alcohol. Preferably, the mass ratio of the Group VIII metal precursor to the first alcohol is 1:1-10, more preferably 1:1-5.

[0051] In this invention, there is no particular limitation on the type of precipitant. Preferably, the precipitant is a carbonate and / or bicarbonate, and more preferably selected from at least one of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate, sodium bicarbonate, and ammonium bicarbonate.

[0052] In this invention, preferably, step S1 includes: adding a dispersion C containing a precipitant to a dispersion A containing a Group VIII metal precursor and a first alcohol under stirring conditions to carry out a contact reaction. In this invention, there are no limitations on the stirring method or specific conditions.

[0053] In this invention, preferably, the dispersion C containing the precipitant is prepared by dispersing the precipitant in a solvent. In this invention, the type of solvent is not particularly limited, as long as it facilitates the dispersion of the precipitant; for example, water. Those skilled in the art can choose according to actual needs. In this invention, the amount of precipitant and solvent is not particularly limited; preferably, the mass ratio of precipitant to water is 1:0.5-3.

[0054] In this invention, the growth of amorphous materials is controlled by regulating the addition rate of dispersion C to improve catalytic performance. Preferably, the addition rate of dispersion C containing the precipitant is 0.5-2.5 mL / min relative to 10 mL of dispersion A containing a Group VIII metal precursor and a first alcohol. This preferred embodiment is advantageous for promoting uniform growth and mixing of the amorphous material.

[0055] In this invention, the range of suitable amounts of precipitant is relatively wide. Preferably, in step S1, the mass ratio of the Group VIII metal precursor to the precipitant is 1:0.5-3.

[0056] In this invention, preferably, in step S1, the contact reaction conditions include: a temperature of 20-40°C and a time of 0.5-10 hours. The advantage of this preferred embodiment is that it controls the growth rate of amorphous oxides and improves ammonia decomposition activity.

[0057] In this invention, preferably, step S1 further includes solid-liquid separation of the contact reaction product to obtain the solid reaction product of step S1. This invention does not particularly limit the solid-liquid separation method, and those skilled in the art can choose according to actual needs.

[0058] In this invention, preferably, in step S2, the dispersion B containing the solid reaction product of step S1 and the second alcohol is prepared by dispersing the solid reaction product of step S1 in the second alcohol.

[0059] In this invention, there is no particular limitation on the type of the second alcohol; it can be the same as or different from the type of the first alcohol, but it is preferred to be the same.

[0060] In this invention, there is no particular limitation on the amount of the solid reaction product and the second alcohol used in step S1 in step S2. Preferably, in step S2, the mass ratio of the solid reaction product and the second alcohol in step S1 is 1:4-15.

[0061] In this invention, there is no particular limitation on the type of ruthenium precursor. Preferably, in step S2, the ruthenium precursor is selected from soluble compounds of ruthenium, and is preferably at least one of ruthenium trichloride, ruthenium nitrate, ruthenium sulfate, ruthenium acetylacetonate, bis(pentamethylcyclopentene)ruthenium, and ruthenium dicene,(1,5-cyclooctadiene)chloride.

[0062] In this invention, there is no particular limitation on the type of reducing agent; both strong and weak reducing agents conventionally defined in the art are applicable, with strong reducing agents being preferred. Preferably, in step S2, the reducing agent is sodium borohydride and / or potassium borohydride, more preferably sodium borohydride.

[0063] In this invention, there is no particular limitation on the amount of reducing agent used. Preferably, in step S2, the mass ratio of the Ru precursor to the reducing agent in step S1 is 1:0.1-0.5.

[0064] In this invention, preferably, step S2 includes: adding the ruthenium precursor to a dispersion B containing the solid reaction product of step S1 and the second alcohol under stirring conditions, and then adding a reducing agent to carry out a reduction reaction. In this invention, the specific method and conditions of stirring are not particularly limited. It is understood that the reduction reaction in step S2 includes a reaction section and a reduction section. The reaction section refers to adding the ruthenium precursor to the dispersion B containing the solid reaction product of step S1 and the second alcohol to react, and the reduction section refers to the reduction after adding the reducing agent. In this invention, the conditions of the reduction reaction include the reaction conditions of the reaction section and the reduction section.

[0065] In this invention, the range of selection for reduction conditions is relatively wide. Preferably, in step S2, the conditions for the reduction reaction include: a temperature of 0-30℃ and a time of 1-8h; more preferably, in step S2, the conditions for the reduction reaction include: a temperature of 10-15℃ and a time of 2-6h. It should be noted that in this invention, the reduction temperature refers to both the reaction section temperature and the reduction section temperature. Furthermore, the reaction section temperature and the reduction section temperature can be the same or different, but are preferably the same. The reduction time refers to the sum of the reaction section time and the reduction section time. The reaction section time and the reduction section time can be the same or different, but are preferably different. This invention does not impose any particular limitation on the reaction section time and the reduction section time.

[0066] In this invention, preferably, step S2 further includes solid-liquid separation of the reduction reaction product to obtain a noble metal-supported amorphous metal oxide catalytic material. This invention does not particularly limit the solid-liquid separation method, and those skilled in the art can choose according to actual needs.

[0067] In this invention, the drying conditions in step S2 are not particularly limited. Preferably, in step S2, the drying conditions include: a temperature of 40-70°C and a time of 12-24 hours.

[0068] According to a specific embodiment of the present invention, the method for the noble metal-supported amorphous metal oxide catalytic material includes the following steps: S1, dispersing a Group VIII metal precursor in a first alcohol to obtain dispersion A, dispersing a precipitant in a solvent (preferably water) to obtain dispersion C containing the precipitant, then reacting dispersion A and dispersion C containing the precipitant in a contact reaction and centrifuging to obtain a solid reaction product; S2, dispersing the solid reaction product obtained in step S1 in a second alcohol to obtain dispersion B, adding a ruthenium precursor to dispersion B and stirring, then adding a reducing agent to carry out a reduction reaction to obtain a reduction reaction product, and finally washing, centrifuging and drying the reduction reaction product to obtain the noble metal-supported amorphous metal oxide catalytic material.

[0069] The third aspect of this invention provides a noble metal-supported amorphous metal oxide catalytic material prepared by the preparation method described in the second aspect.

[0070] The fourth aspect of this invention provides the application of the noble metal-supported amorphous metal oxide catalytic material described in the first or third aspect in the photocatalytic ammonia decomposition to produce hydrogen.

[0071] In this invention, preferably, the photocatalytic ammonia decomposition to hydrogen production reaction includes: photocatalytically decomposing ammonia (preferably ammonia water) to hydrogen production reaction in the presence of visible light irradiation and the catalytic material described in the first or third aspect.

[0072] In this invention, preferably, the conditions for the photocatalytic ammonia decomposition to hydrogen production reaction include: a reaction temperature of 0-70℃, and a catalyst dosage of 0.05-1g relative to 0.01mol of ammonia.

[0073] The present invention will be described in detail below through embodiments. Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.

[0074] Example 1

[0075] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. Then, 0.2 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst. Figure 1 As shown, noble metal-supported amorphous oxide catalytic materials in the range of 10–90 o No corresponding metal diffraction characteristic peaks appeared within the range of 30–40. o The presence of broadened amorphous characteristic diffraction peaks indicates that the catalytic material of Example 1 has an amorphous structure. Figure 2 It can be seen that the catalytic material responds well to near-infrared sunlight.

[0076] Example 2

[0077] 23.3 g of cobalt nitrate hexahydrate, 7.6 g of ferric nitrate nonahydrate, and 9.7 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 60 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.5 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 0.54 g of ruthenium trichloride was added at a constant temperature of 15 °C, and the mixture was stirred for 4 hours. Then, 0.2 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0078] Example 3

[0079] 31.1 g of cobalt nitrate hexahydrate, 5.0 g of ferric nitrate nonahydrate, and 3.9 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C. The addition rate of dispersion C was 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.16 g of sodium borohydride was quickly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0080] Example 4

[0081] 19.4 g of cobalt nitrate hexahydrate, 12.6 g of ferric nitrate nonahydrate, and 9.7 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.4 g of sodium borohydride was quickly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0082] Example 5

[0083] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C. The addition rate of dispersion C was 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 0.06 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. Then, 0.03 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0084] Example 6

[0085] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 80 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 50 mL of anhydrous ethanol to obtain dispersion B. 1.35 g of ruthenium trichloride was added at a constant temperature of 15 °C, and the mixture was stirred for 3 hours. Then, 0.4 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0086] Example 7

[0087] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 0.5 °C, and the mixture was stirred for 3 hours. 0.2 g of sodium borohydride was quickly added, and the mixture was stirred for 1 hour. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0088] Example 8

[0089] 38.9 g of cobalt nitrate hexahydrate precursor was weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A; 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.2 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0090] Example 9

[0091] 50.5 g of ferric nitrate nonahydrate precursor was weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A; 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.2 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0092] Comparative Example 1

[0093] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C. The addition rate of dispersion C was 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain the solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.2 g of sodium borohydride was quickly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours. It was then calcined in a muffle furnace at 500 °C for 2 hours to obtain Comparative Example 1 (crystalline sample).

[0094] Comparative Example 2

[0095] 23.3 g of cobalt nitrate hexahydrate, 10.1 g of ferric nitrate nonahydrate, and 7.8 g of nickel nitrate hexahydrate were weighed and dispersed in 80 mL of anhydrous ethanol to obtain dispersion A. 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 80 °C. The addition rate of dispersion C was 1.2 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 8 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. 0.2 g of sodium borohydride was quickly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0096] Comparative Example 3

[0097] 50.0 g of manganese nitrate precursor was weighed and dispersed in 100 mL of anhydrous ethanol to obtain dispersion A; 50 g of sodium carbonate was weighed and dispersed in 30 mL of water to obtain dispersion C. Dispersion C was slowly added to dispersion A at a constant temperature of 40 °C, with an addition rate of 1.0 mL / min relative to 10 mL of dispersion A. After stirring thoroughly for 6 hours, the mixture was centrifuged to obtain a solid reaction product. 8 g of the solid reaction product was dispersed in 60 mL of anhydrous ethanol to obtain dispersion B. 1.0 g of ruthenium trichloride was added at a constant temperature of 10 °C, and the mixture was stirred for 3 hours. Then, 0.2 g of sodium borohydride was rapidly added, and the mixture was stirred for 2 hours. The resulting solid was washed with water, centrifuged, and dried at 60 °C for 12 hours to obtain the noble metal-supported amorphous oxide catalyst.

[0098] The composition of the catalytic materials in the above embodiments and comparative examples is shown in Table 1, and the property parameters are shown in Table 2.

[0099] Table 1

[0100] Catalytic material composition Example 1 60wt%CoO-20wt%Fe2O3-20wt%NiO / 4.6wt%Ru Example 2 60wt%CoO-15wt%Fe2O3-25wt%NiO / 2.6wt%Ru Example 3 80wt%CoO-10wt%Fe2O3-10wt%NiO / 4.6wt%Ru Example 4 50wt%CoO-25wt%Fe2O3-25wt%NiO / 4.7wt%Ru Example 5 60wt%CoO-20wt%Fe2O3-20wt%NiO / 0.3wt%Ru Example 6 60wt%CoO-20wt%Fe2O3-20wt%NiO / 6.2wt%Ru Example 7 60wt%CoO-20wt%Fe2O3-20wt%NiO / 4.6wt%Ru Example 8 100wt%CoO / 4.6wt%Ru Example 9 100wt%Fe2O3 / 4.6wt%Ru Comparative Example 1 60wt%CoO-20wt%Fe2O3-20wt%NiO / 4.6wt%Ru Comparative Example 2 60wt%CoO-20wt%Fe2O3-20wt%NiO / 4.6wt%Ru Comparative Example 3 100wt%M2O3 / 4.6wt%Ru

[0101] Table 2

[0102]

[0103] Photocatalytic ammonia decomposition hydrogen production activity test

[0104] The noble metal-supported amorphous oxide catalysts described in the above examples and comparative examples were subjected to photocatalytic ammonia decomposition for hydrogen production under simulated sunlight and long wavelengths greater than 600 nm. Activity was tested using an online vacuum photocatalytic reactor with a 300W xenon lamp as the light source. The reaction conditions were: 0.1 g catalyst, 100 mL of 0.1 mol / L ammonia solution, and a reaction temperature of 5 °C. Samples were taken every hour after the reaction started to calculate the average reaction rate over 6 hours. The products were analyzed using chromatography equipped with a flame ionization detector and a thermal conductivity detector, and quantification was performed using a pre-determined standard curve. The reaction products were N2, H2, and a small amount of O2 from the water decomposition side reaction. The reaction results are shown in Table 3.

[0105] Table 3

[0106]

[0107] As can be seen from Table 3 above, the amorphous materials provided by this invention all exhibit excellent photocatalytic ammonia decomposition performance, and also demonstrate good performance under long-wavelength light irradiation greater than 600 nm, indicating that they can better utilize broad-spectrum solar energy. However, the crystalline sample of Comparative Example 1, obtained after high-temperature calcination, is not a semiconductor material and does not possess photocatalytic ability. Compared with Example 1, the contact reaction temperature of Comparative Example 2 is too high, causing the partial disappearance of the amorphous structure of the catalytic material and a decrease in photoresponse ability. Comparative Example 3 demonstrates that only the preferred metal oxide of this invention possesses good photocatalytic ammonia decomposition performance.

[0108] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A noble metal-supported amorphous metal oxide catalytic material for photocatalytic ammonia decomposition to produce hydrogen, characterized in that, The catalytic material comprises Group VIII amorphous metal oxides and ruthenium; the Group VIII amorphous metal oxides are amorphous nickel oxide, amorphous cobalt oxide, and amorphous iron oxide; based on the total amount of the catalytic material, the ruthenium content is 2-5% by mass (elementally). The mass ratio of the amorphous cobalt oxide to the sum of the amorphous nickel oxide and the amorphous iron oxide is 1.2-3:1; Based on the total amount of Group VIII amorphous metal oxides, the content of amorphous cobalt oxide is 50-80% by mass, the content of amorphous nickel oxide is 7.5-25% by mass, and the content of amorphous iron oxide is 7.5-25% by mass. The catalytic material contains oxygen vacancies; the oxygen vacancies content in the catalytic material is 2-10%. The preparation method of the catalytic material includes the following steps: S1. The dispersion A containing the Group VIII metal precursor and the first alcohol is reacted with a precipitant to obtain a solid reaction product. S2. In the presence of a reducing agent, a dispersion B containing the solid reaction product of step S1 and the second alcohol is reduced with a ruthenium precursor and then dried to obtain a noble metal supported amorphous metal oxide catalytic material. The conditions for the contact reaction in step S1 include: a temperature of 5-40℃ and a time of 0.5-24h; In step S2, the conditions for the reduction reaction include: a temperature of 0-30℃ and a time of 1-8h.

2. The catalytic material according to claim 1, wherein, The specific surface area of ​​the catalytic material is 200-800 cm². 2 / g.

3. The catalytic material according to claim 2, wherein, The specific surface area of ​​the catalytic material is 600-800 cm². 2 / g.

4. The catalytic material according to claim 1, wherein, The catalytic material does not exhibit characteristic diffraction peaks in the 10º-90º range of the X-ray diffraction pattern, but exhibits amorphous characteristic diffraction peaks in the 30º-40º range of the X-ray diffraction pattern.

5. The catalytic material according to claim 1, wherein, The oxygen defect content in the catalytic material is 4-6%.

6. A method for preparing a noble metal-supported amorphous metal oxide catalytic material for photocatalytic ammonia decomposition to hydrogen production, wherein, The method includes the following steps: S1. The dispersion A containing the Group VIII metal precursor and the first alcohol is reacted with a precipitant to obtain a solid reaction product. S2. In the presence of a reducing agent, a dispersion B containing the solid reaction product of step S1 and the second alcohol is reduced with a ruthenium precursor and then dried to obtain a noble metal supported amorphous metal oxide catalytic material. The Group VIII metals are iron, cobalt, and nickel; The amount of the ruthenium precursor used is such that, based on the total amount of the catalytic material, the ruthenium content in the prepared noble metal-supported amorphous metal oxide catalytic material is 2-5% by mass (based on the total amount of the catalytic material). The conditions for the contact reaction in step S1 include: a temperature of 5-40℃ and a time of 0.5-24h; The mass ratio of cobalt precursor (calculated as oxide) to the sum of nickel precursor (calculated as oxide) and iron precursor (calculated as oxide) is 1.2-3:1; Based on the total amount of Group VIII amorphous metal oxides, the content of amorphous cobalt oxide is 50-80% by mass, the content of amorphous nickel oxide is 7.5-25% by mass, and the content of amorphous iron oxide is 7.5-25% by mass. The catalytic material contains oxygen vacancies; the oxygen vacancies content in the catalytic material is 2-10%. In step S2, the conditions for the reduction reaction include: a temperature of 0-30℃ and a time of 1-8h.

7. The method according to claim 6, wherein, In step S1, the Group VIII metal precursor is selected from soluble compounds of various metals.

8. The method according to claim 7, wherein, In step S1, the Group VIII metal precursor is selected from at least one of the nitrate, chloride and sulfate salts of each metal.

9. The method according to claim 6, wherein, In step S1, the first alcohol is a monohydric alcohol and / or a polyhydric alcohol.

10. The method according to claim 9, wherein, In step S1, the first alcohol is at least one of methanol, ethanol, and ethylene glycol.

11. The method according to claim 6, wherein, In step S1, the mass ratio of the group VIII metal precursor to the first alcohol is 1:1-10.

12. The method according to claim 11, wherein, In step S1, the mass ratio of the group VIII metal precursor to the first alcohol is 1:1-5.

13. The method according to any one of claims 6-12, wherein, In step S1, the precipitant is a carbonate and / or a bicarbonate.

14. The method according to claim 13, wherein, In step S1, the precipitant is at least one of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate, sodium bicarbonate, and ammonium bicarbonate.

15. The method according to any one of claims 6-12, wherein, Step S1 includes: under stirring conditions, adding the dispersion C containing the precipitant to the dispersion A containing the Group VIII metal precursor and the first alcohol to carry out a contact reaction.

16. The method according to claim 15, wherein, The dispersion C containing the precipitant is prepared by dispersing the precipitant in a solvent.

17. The method according to claim 15, wherein, The addition rate of dispersion C containing precipitant was 0.5-2.5 mL / min, relative to 10 mL of dispersion A containing group VIII metal precursor and first alcohol.

18. The method according to any one of claims 6-12, wherein, In step S1, the mass ratio of the Group VIII metal precursor to the precipitant is 1:0.5-3.

19. The method according to any one of claims 6-12, wherein, In step S1, the conditions for the contact reaction include: a temperature of 20-40℃ and a time of 0.5-10h.

20. The method according to any one of claims 6-12, wherein, In step S2, the dispersion B containing the solid reaction product of step S1 and the second alcohol is prepared by dispersing the solid reaction product of step S1 in the second alcohol.

21. The method according to claim 20, wherein, In step S2, the mass ratio of the solid reaction product in step S1 to the second alcohol is 1:4-15.

22. The method according to any one of claims 6-12, wherein, In step S2, the ruthenium precursor is selected from ruthenium-soluble compounds.

23. The method according to claim 22, wherein, In step S2, the ruthenium precursor is at least one of ruthenium trichloride, ruthenium nitrate, ruthenium sulfate, ruthenium acetylacetonate, bis(pentamethylcyclopentene)ruthenium, and ruthenium dicene,(1,5-cyclooctadiene)chloride.

24. The method according to any one of claims 6-12, wherein, In step S2, the reducing agent is sodium borohydride and / or potassium borohydride.

25. The method according to any one of claims 6-12, wherein, In step S2, the mass ratio of the ruthenium precursor to the reducing agent in step S1 is 1:0.1-0.

5.

26. The method according to any one of claims 6-12, wherein, Step S2 includes: adding the ruthenium precursor to a dispersion B containing the solid reaction product of step S1 and the second alcohol under stirring conditions, and then adding a reducing agent to carry out a reduction reaction.

27. The method according to any one of claims 6-12, wherein, In step S2, the conditions for the reduction reaction include: a temperature of 0-30℃ and a time of 1-8h.

28. The method according to claim 27, wherein, In step S2, the conditions for the reduction reaction include: a temperature of 10-15℃ and a time of 2-6h.

29. The method according to any one of claims 6-12, wherein, In step S2, the drying conditions include a temperature of 40-70°C and a time of 12-24 hours.

30. A noble metal-supported amorphous metal oxide catalytic material for photocatalytic ammonia decomposition to hydrogen production, prepared by the method according to any one of claims 6-29.

31. The application of the noble metal-supported amorphous metal oxide catalytic material for photocatalytic ammonia decomposition to hydrogen production as described in any one of claims 1-5 and 30 in the photocatalytic ammonia decomposition to hydrogen production reaction.

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