Supported alloy catalysts based on the interaction between metal and support, and preparation methods and applications thereof

Abstract

The present invention discloses a supported alloy catalyst based on the interaction between a metal and a support, and a preparation method and application thereof. In the present invention, a metal A oxide support, an active metal precursor, and a metal A precursor are dispersed in water to obtain a dispersion liquid, and then an aqueous solution containing a precipitating agent is added, followed by heating and reacting, and then centrifugation or filtration, drying, and reduction heat treatment are carried out to obtain the supported alloy catalyst. The catalyst of the present invention includes an active metal phase and an oxide matrix phase, and the active metal phase is dispersed in the form of nanoparticles on the surface of the oxide matrix phase. The present invention provides a highly efficient and stable supported alloy catalyst prepared by a method based on modulating the interaction between a metal and a support. The method has easily available raw materials, simple operation, and is convenient for mass production. The prepared catalyst is applied to the N2H4·H2O catalytic decomposition hydrogen production system, has both rich active sites and good mass transfer characteristics, and can efficiently and stably catalyze the decomposition of N2H4·H2O to produce hydrogen under near room temperature conditions.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen production technology and materials, and particularly relates to a supported alloy catalyst based on the interaction between a metal and a carrier, and a preparation method and application thereof. Background Art

[0002] As a clean and efficient secondary energy source, hydrogen energy is expected to solve global problems such as energy crisis and environmental pollution for mankind. However, the large-scale application of hydrogen energy needs to solve the scientific / technical challenges faced in the hydrogen production, hydrogen storage, and hydrogen utilization links, among which the hydrogen storage link is the most prominent. Therefore, the development of hydrogen storage materials and hydrogen production technology is of great significance for achieving sustainable development. Decades of research by global scholars have shown that the working environment of reversible hydrogen storage materials cannot yet meet the requirements of on-vehicle fuel cell applications or cannot meet them simultaneously. In view of this research status, since around 2000, scholars from various countries have begun to focus on the research of controllable hydrogen release technology for chemical hydrogen storage materials, thus triggering a research boom in chemical hydrogen storage materials. Among them, hydrazine hydrate (N 2 H 4 ·H 2 O) as a new type of chemical hydride not only has the typical characteristics of integrated hydrogen storage / hydrogen production, but also has outstanding advantages such as a high hydrogen storage density (8 wt%), a low price (2 $ / L), good chemical stability, and no solid by-products generated in the hydrogen production reaction, and thus has the most promising application potential in on-vehicle / portable hydrogen sources.

[0003] The core key to developing the controllable hydrogen release technology of N 2 H 4 ·H 2 O lies in developing a catalyst with high activity, high hydrogen production selectivity, and good stability. Previous studies have found that the three single metals Ir, Ru, and Ni show different catalytic performances for the decomposition reaction of N 2 H 4 ·H 2 O. Among them, the noble metals Ir and Ru show high catalytic activity, but their hydrogen production selectivity is too low; although the transition metal Ni shows relatively high hydrogen production selectivity, its catalytic activity is much lower than that of the noble metals Ir and Ru. In recent years, scholars from various countries have comprehensively used modification strategies such as alloying, structural nanosizing, and introducing basic oxide carriers, and generally have greatly improved the catalyst activity and hydrogen production selectivity. However, the existing N 2 H 4 ·H 2The hydrazine decomposition hydrogen production catalyst still cannot meet the practical requirements, and the durability problem is the most prominent. According to literature reports, the activity of most Ni-based catalysts decays by as much as 30-60% in 10-cycle stability tests (Int.J Hydrogen Energy, 2017, 42:16355-16361). At present, scholars in various countries have not paid attention to this key problem, let alone a solution. In the early stage of the research group, through the study of the representative Ni-Pt / CeO 2 catalyst for catalytic N 2 H 4 ·H 2 decomposition hydrogen production, it was found that there are adsorbed N-containing species related to the degree of activity reduction on the surface of the used catalyst. The above results indicate that active site poisoning may be one of the main reasons for inactivation. One way to solve this problem is to reduce the binding affinity between the active site and the intermediate, thereby improving the availability of the catalytic reaction active site. However, the weak interaction between the active site and the adsorbate may lead to a decrease in the intrinsic reaction rate. How to improve the stability of the hydrazine decomposition hydrogen production catalyst and achieve the best balance between activity and stability is still a major problem that needs to be solved in the future research on hydrazine decomposition hydrogen production technology. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a supported alloy catalyst based on the interaction between metal and support for N 2 H 4 ·H 2 O decomposition reaction, its preparation method and application. Developing efficient and stable catalyst design concepts and controllable synthesis methods is a key problem that needs to be solved urgently in promoting the practical process of hydrazine (N 2 H 4 ·H 2 O) controllable hydrogen production technology. The method of the present invention has easily available raw materials, simple operation, is convenient for mass production, and the prepared catalyst has both rich active sites and good mass transfer characteristics, and can efficiently and stably catalyze N 2 H 4 ·H 2 O decomposition hydrogen production reaction under alkaline conditions.

[0005] The catalyst of the present invention is composed of an active metal phase and an oxide matrix phase. The active metal phase is dispersed on the surface of the oxide matrix phase in the form of fine nanoparticles; at the same time, the interaction between the oxide matrix and the active metal phase can be effectively modulated, thereby affecting the reaction activity, hydrogen production selectivity and stability of the target catalyst. The catalyst preparation method includes: first, a carrier material is prepared by a precipitation method, and then the target sample is synthesized by a two-step method combining precipitation-deposition and subsequent reduction heat treatment.

[0006] In some specific embodiments, specifically, first, an aqueous solution containing a carrier metal precursor salt is used as the starting material, and NaOH is used as an alkali promoter to precipitate CeO 2 nanorods; subsequently, in the operation of loading Ni-Pt alloy nanoparticles onto the surface of CeO 2 nanorods by the deposition-precipitation method, a small amount of Ce 3+ precursor salt is additionally introduced to form more Ni-Pt / CeO 2 phase interfaces, providing a structural basis for enhancing the interaction between Ni-Pt / CeO 2 interfaces.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A method for preparing a supported alloy catalyst based on the interaction between a metal and a carrier, comprising the following steps:

[0009] Disperse the A metal oxide carrier, the active metal precursor, and the A metal precursor in water to obtain a dispersion, then add an aqueous solution containing a precipitating agent, heat and react, and then perform centrifugation or filtration, drying, and reduction heat treatment to obtain a supported alloy catalyst based on the interaction between a metal and a carrier.

[0010] Preferably, the A metal precursor includes at least one of nitrates, carbonates, acetates, and halides of the A metal, and the A metal includes at least one of Ce, Mn, La, and Ti;

[0011] Preferably, the active metal precursor includes at least one of halides, nitrates, sulfates, and complexes of the active metal, and the active metal includes at least one of Ni, Co, Ir, Pt, Pd, and Ru;

[0012] Preferably, the precipitating agent includes at least one of sodium hydroxide, sodium carbonate, tetramethylammonium hydroxide, and urea.

[0013] Preferably, the concentration of the A metal oxide carrier in the dispersion is 0.1-4 mg / mL;

[0014] Preferably, the A metal oxide carrier is pre-ultrasonically treated in water; the ultrasonic time is 30-60 minutes;

[0015] Preferably, the morphology of the A metal oxide carrier is nanorods, nanosheets, or nanoflowers.

[0016] More preferably, the A metal oxide carrier is prepared by a precipitation method; specifically, the A metal precursor (soluble A metal compound, etc.) and the precipitating agent (NaOH, etc.) are mixed and hydrothermally reacted (maintained at 90-110 °C for 12-36 hours).

[0017] Preferably, the concentration of the active metal precursor in the dispersion liquid is 0.001 - 0.01 mol / L, and the concentration of the A metal precursor is 0.001 - 0.01 mol / L;

[0018] Preferably, the molar ratio of the active metal precursor to the A metal precursor is 0.1 - 10:1;

[0019] Preferably, the molar ratio of the precipitating agent to the total amount of the active metal precursor and the A metal precursor is 0.5 - 2:1.

[0020] Preferably, the concentration of the precipitating agent is 0.001 - 0.01 mol / L.

[0021] Preferably, the heating reaction is carried out under stirring; the rotation speed of the stirring is 10 - 50 r / min.

[0022] Preferably, the temperature of the reaction is 90 - 110 °C, and the time is 6 - 12 hours;

[0023] Preferably, the temperature of the drying is 40 - 70 °C, and the drying time is 6 - 12 hours.

[0024] Preferably, the atmosphere of the reduction heat treatment is hydrogen;

[0025] Preferably, the temperature of the reduction heat treatment is 250 - 500 °C; the time of the reduction heat treatment is 1 - 3 hours.

[0026] The supported alloy catalyst based on the interaction between metal and support prepared by the above preparation method, the catalyst includes an active metal phase and an oxide matrix phase, and the active metal phase is dispersed on the surface of the oxide matrix phase in the form of nanoparticles.

[0027] Preferably, the oxide matrix phase is a monometallic oxide containing variable valence states;

[0028] More preferably, the oxide matrix phase is CeO 2 , MnO 2 , TiO 2 or La 2 O 3 . More preferably, it is CeO 2 .

[0029] Preferably, the oxide matrix exists in the form of nanorods.

[0030] Preferably, the active metal phase is a plurality of metals composed of two or more components.

[0031] Further preferably, the active metal phase is a binary alloy of Ni-Co, Ni-Pt, Ni-Ir, Ni-Ru, Ni-Pd, Co-Pt, Co-Ir, Co-Ru, Co-Pd, or a ternary alloy of Ni-Co-Pt, Ni-Co-Ir, Ni-Co-Ru, Ni-Co-Pd; more preferably, the active metal phase is Ni-Pt.

[0032] Preferably, the size of the active metal phase nanoparticles is 1 to 2 nanometers.

[0033] Preferably, the oxide matrix has a strong interaction with the active metal.

[0034] The application of the above-mentioned supported alloy catalyst based on the interaction between metal and support in the decomposition of hydrazine hydrate to produce hydrogen.

[0035] The design principle of the present invention is:

[0036] Research shows that the deactivation of the catalyst for the catalytic decomposition of N 2 H 4 ·H 2 O to produce hydrogen is a complex phenomenon that may involve various reasons such as active site poisoning and changes in the catalyst phase structure. In addition, based on empirical knowledge, the stability of the catalyst is usually achieved at the expense of its intrinsic activity. However, domestic and foreign scholars have not yet carried out in-depth research on the key issues of catalyst deactivation. This research status will undoubtedly delay the R & D process of the controllable hydrogen production technology of hydrazine hydrate. Based on the above research status, starting from considering the stability of the catalyst, in the operation of loading Ni-Pt alloy nanoparticles onto the surface of CeO 2 nanorods by the deposition-precipitation method, a small amount of Ce 3+ precursor salt is additionally introduced to form more Ni-Pt / CeO 2 phase interfaces, providing a structural basis for enhancing the interaction between Ni-Pt / CeO 2 . The experimental results of the design show that the Ni 4 Pt / CeO 2 catalyst prepared by the improved method has an activity retention rate of 80% after 10 cycles of use, while the activity retention rate of the catalyst prepared by the traditional method is only 38% under the same test conditions. In summary, the N 2 H 4 ·H 2 O catalytic decomposition to hydrogen catalyst prepared by the present invention exhibits excellent comprehensive catalytic performance.

[0037] The advantages and beneficial effects of the present invention are as follows:

[0038] (1) The present invention provides a catalyst suitable for N 2 H 4 ·H2 A new method for preparing a supported alloy catalyst for hydrogen production by NH₃·H₂O decomposition. The key difference between this method and traditional methods lies in the additional introduction of a small amount of Ce during the precipitation-deposition process. 3+ The precursor salt can form more Ni-Pt / CeO 2 phase interfaces, providing a structural basis for enhancing the interaction between Ni-Pt / CeO 2 .

[0039] (2) The support material used in the present invention has a specific morphology (such as nanorods), with a rich number of active sites and good mass transfer characteristics.

[0040] (3) The new method for preparing a supported alloy catalyst for hydrogen production by NH₃·H₂O decomposition provided by the present invention has easily available raw materials, a simple process, is convenient for mass production, and is pollution-free throughout the process. 2 H 4 ·H 2 O

[0041] (4) The NH₃·H₂O catalytic decomposition hydrogen production catalyst provided by the present invention can selectively catalyze the decomposition of NH₃·H₂O to produce hydrogen under alkaline conditions and has excellent stability. 2 H 4 ·H 2 O 2 H 4 ·H 2 O BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 XRD patterns of the support precursor, Ni 4 Pt-DP, and Ni 4 Pt-MDP samples for Example 1.

[0043] Figure 2 TEM image of the support precursor for Example 1.

[0044] Figure 3 TEM images (a) and SAED pattern (b) of the Ni 4 Pt-MDP sample for Example 1.

[0045] Figure 4 HRTEM images (a) and HAADF image (b) and corresponding EDS line scans (1-3) of the Ni 4 Pt-MDP sample for Example 1.

[0046] Figure 5 Ni 4 Pt / CeO 2 -DP reference sample and different Ce 3+ / (Ni 2+ +Pt4+ ) Ni in molar ratio 4 Pt / CeO 2 H2-TPR curves of the Pt-MDP samples.

[0047] Figure 6 Commercial Ni powder of Example 1, Ni 4 Pt / CeO 2 -DP reference sample and Ni 4 XPS results of the Pt-MDP target sample: Ni 2p(a); and commercial Pt powder of Example 1, Ni 4 Pt / CeO 2 -DP reference sample and Ni 4 XPS results of the Pt-MDP target sample: Pt 4f(b).

[0048] Figure 7 Ni of Example 1 4 Pt / CeO 2 -DP reference sample and different Ce 3+ / (Ni 2+ +Pt 4+ ) Ni in molar ratio 4 Pt / CeO 2 -MDP samples catalyzing N 2 H 4 ·H 2 O decomposition kinetic curves.

[0049] Figure 8 Ni of Example 1 treated at different reduction temperatures 4 Pt-MDP samples catalyzing N 2 H 4 ·H 2 O decomposition kinetic curves.

[0050] Figure 9 Ni of Example 1 4 Pt / CeO 2 -DP reference sample (a) and Ni 4 Pt-MDP target sample (b) catalyzing N 2 H 4 ·H 2 O decomposition hydrogen production cyclic kinetic curves.

[0051] Figure 10 Ni of Example 1 4 Pt / CeO 2 -DP reference sample, Ni 4 TPD-MS results of the Pt-MDP target sample after use.

[0052] Figure 11 For Co of Example 2 4 Pt / CeO 2 -DP reference sample and Co 4 Pt-MDP target sample for catalytic decomposition of N 2 H 4 ·H 2 O to produce hydrogen cyclic kinetic curves.

[0053] Figure 12 For Ni of Example 3 10 Ir / La 2 O 3 -DP reference sample and Ni 10 Ir / La 2 O 3 -MDP target sample for catalytic decomposition of N 2 H 4 ·H 2 O to produce hydrogen cyclic kinetic curves.

[0054] Figure 13 For Co of Example 4 3 Ir 2 / La 2 O 3 -DP reference sample and Co 3 Ir 2 / La 2 O 3 -MDP target sample for catalytic decomposition of N 2 H 4 ·H 2 O to produce hydrogen cyclic kinetic curves. Detailed implementation manners

[0055] The present invention will be specifically described below in conjunction with embodiments, but the implementation manners and protection scope of the present invention are not limited to the following embodiments.

[0056] In the specific implementation manners of the present invention, the target sample is synthesized by a three-step method. First, a carrier precursor is synthesized using a precipitation method, and then an alloy oxide or hydroxide is loaded using an improved precipitation-deposition method. Finally, high-temperature heating (250 - 500 °C) is carried out in a reducing atmosphere, and after holding for a set time, it is cooled to room temperature to obtain the target catalyst.

[0057] The preparation method of the supported alloy catalyst of the present invention includes the following steps:

[0058] (1) A carrier with a specific morphology (such as nanorods, nanosheets or nanoflowers) is pre-synthesized, and then the carrier is dispersed in an aqueous solution and dispersed by ultrasonic wave combined with stirring to obtain a ready-to-use solution.

[0059] (2) Add a quantitative amount of the active metal precursor and the precursor containing the supported metal to step (1) and stir thoroughly. Subsequently, transfer the reaction flask to an oil bath and raise the temperature to a specific temperature, maintaining stirring during this process.

[0060] (3) Add the precipitating agent (such as sodium hydroxide, urea) dropwise to step (2) and continue the reaction for a period of time. Subsequently, cool to room temperature and remove impurities by centrifugation or filtration. The resulting precipitate is dried in an oven at a specific temperature.

[0061] (4) Subject the powder sample prepared in step (3) to reduction heat treatment to obtain the target catalyst.

[0062] Preferably, the precursor containing the supported metal includes nitrates, chlorides, carbonates, acetates, and halides of the supported metal, and the supported metal includes: Ce, Mn, La, Ti; more preferably nitrates;

[0063] Preferably, the active metal precursor includes halochlorides, nitrates, sulfates, and complexes of the active metal, and the active metal includes: Ni, Co, Ir, Pt, Pd, Ru; more preferably chlorides and nitrates;

[0064] Preferably, the precipitating agent includes sodium hydroxide, sodium carbonate, tetramethylammonium hydroxide, and urea. More preferably sodium hydroxide and urea.

[0065] Preferably, in step (1), the supported metal concentration is 0.1 - 4 mg / mL, the ultrasonic time is 30 - 60 minutes, and the stirring time is 30 - 60 minutes;

[0066] Preferably, in step (2), the metal precursor concentration is 0.001 - 0.01 mol / L, the supported metal precursor concentration is 0.001 - 0.01 mol / L, the temperature is 90 - 110 °C, and the rotation speed is 10 - 50 r / min;

[0067] Preferably, in step (3), the reaction time is 6 - 12 hours, the oven temperature is 40 - 70 °C, and the drying time is 6 - 12 hours;

[0068] Preferably, in step (4), the reducing atmosphere is hydrogen; the temperature of the heat treatment is 200 - 500 °C; the time of the heat treatment is 1 - 3 hours.

[0069] The present invention is described in detail below through specific examples.

[0070] Example 1

[0071] Ni 4 Pt / CeO 2 Synthesis, Structure and Catalytic Performance of the Catalyst

[0072] Catalyst Preparation

[0073] The preparation method of cerium oxide precursor nanorods is as follows: Dissolve 460 mmol of sodium hydroxide (NaOH, 96%) in 80 mL of deionized water to form a clear solution, and then add 20 mL of 0.2 mol / L cerium nitrate hexahydrate (Ce(NO 3 ) 3 ·6H 2 O, 99.5%) aqueous solution at a rate of 0.5 mL / min using a dual-channel syringe pump. Then heat the reaction mixture in an oil bath and maintain it at 100 °C for 24 hours, and then cool it to room temperature. Keep magnetic stirring throughout the synthesis process. Collect the obtained product with a centrifuge, wash it with deionized water until the pH value is neutral, and finally dry it overnight under normal pressure environment to obtain the CeO 2 nanorod carrier precursor.

[0074] Ni 4 Pt / CeO 2 -MDP catalyst is prepared by an improved method combining precipitation-deposition with heat treatment reduction. In a typical operation, add 10 mL of 0.2 mol / L urea ((NH 2 ) 2 CO, 99.5%) aqueous solution dropwise to 50 mL of an aqueous solution containing 1 mmol of pre-ultrasonicated CeO 2 nanorods, 0.04 mmol of nickel nitrate hexahydrate (Ni(NO 3 ) 2 ·6H 2 O, 98%), 0.01 mmol of chloroplatinic acid (H 2 PtCl 6 ·6H 2 O, Pt≥37.5%) and 0.025 mmol of Ce(NO 3 ) 3 ·6H 2 O, and then keep the mixture at 95 °C for 24 hours through an oil bath, and stir throughout the reaction process. Wash the collected sample 5 times with deionized water, and then dry it at 60 °C for 12 hours. The sample thus obtained is heat-treated at 300 °C for 1 hour in an H 2 atmosphere.

[0075] Prepare the reference sample Ni 4 Pt / CeO 2 -DP using a similar procedure, only without adding cerium nitrate in the deposition-precipitation step.

[0076] Prepare different Ce 3+ / (Ni 2+ +Pt 4+) Ni in molar ratio 4 Pt / CeO 2 -MDP samples, only changing the amount of Ce(NO 3 ) 3 ·6H 2 O in the above preparation method are 0.01 mmol, 0.05 mmol, and 0.10 mmol respectively.

[0077] Ni 4 Pt / CeO 2 -MDP samples with different heat treatment temperatures were prepared using a similar procedure, only changing the reduction heat treatment temperature in the above preparation method, which were 250 °C, 400 °C, and 500 °C respectively.

[0078] In addition, another reference sample Ni 4 Pt / CeO 2 (one pot DP) was prepared by the one-pot co-precipitation method. The steps are as follows: 4×10 -3 mol Ni(NO 3 ) 2 , 1×10 -3 mol H 2 PtCl 6 , 0.1 mol of Ce(NO 3 ) 3 and 60 mL of C 2 H 5 OH were successively added to a 100 mL round-bottom flask, stirred evenly, heated to 60 °C, and 20 mL of 2.2 mol / L TMAH C 2 H 5 OH solution was added dropwise, and the reaction was carried out for 2 h; the resulting suspension was transferred to a hydrothermal autoclave and reacted at 80 °C for another 12 h. The solution was centrifuged, and the collected precipitate was washed with water and alcohol completely and then dried in vacuum at room temperature for 12 h. The obtained solid powder was placed in a tubular muffle furnace and reduced at 300 °C for 1 h in a hydrogen atmosphere to obtain the reference sample Ni 4 Pt / CeO 2 (one pot DP).

[0079] Characterization of the phase / structure / element chemical state of the catalyst:

[0080] XRD analysis showed ( Figure 1 ) that the phase composition of the carrier precursor prepared by the precipitation method was a mixture of CeO 2 , Ce 2 O 3 and Ce(OH) 3 . The target Ni 4 Pt / CeO 2-MDP and reference Ni 4 Pt / CeO 2 -The XRD pattern of DP only shows the diffraction peaks of CeO 2 , and no Ni- or Pt-containing phases are found, indicating that Ni and Pt exist in amorphous or nanocrystalline forms.

[0081] The TEM results show ([[]] Figure 2 ) that the carrier precursor has a porous rod-like morphology, with a diameter of about 5 nm and a length of 30 - 50 nm. The nanopores are formed by the dehydration of Ce(OH) 3 .

[0082] Target sample Ni 4 Pt / CeO 2 -The microstructure of MDP shows ([[]] Figure 3 a) in that after loading the Ni-Pt alloy onto the ceria substrate, the morphology of the nanorods remains basically unchanged, but the nanorods become more porous, which is due to the complete dehydration of Ce(OH) 3 to form CeO 2 , consistent with the SAED results ([[]] Figure 3 b) in that).

[0083] HRTEM further observes the matrix CeO 2 phase ([[]] Figure 4 a) in that), and HAADF-STEM combined with EDS line scanning confirms that the Ni-Pt alloy particle size is about 1 - 2 nm ([[]] Figure 4 b) in that).

[0084] Ni 4 Pt / CeO 2 -The H 3+ / (Ni 2+ +Pt 4+ ) molar ratio of the reference sample of DP and Ni 4 Pt / CeO 2 -MDP samples shows ([[]] 2 ) that the additional introduction of Ce Figure 5 during the precipitation-deposition step will enhance the metal / support interaction. 3+

[0085] XPS ([[]] Figure 6 ) results further confirm that the target sample Ni 4 Pt / CeO 2 -MDP has a stronger metal / support interaction compared to the reference sample Ni 4 Pt / CeO 2 -DP.

[0086] N2 H 4 ·H 2 O catalytic decomposition hydrogen production performance test

[0087] Figure 7 Different Ce 3+ / (Ni 2+ +Pt 4+ ) molar ratio of Ni 4 Pt / CeO 2 -MDP sample and reference sample Ni 4 Pt / CeO 2 -DP catalytic N 2 H 4 ·H 2 The kinetic performance curve of hydrogen production by decomposition of O. The results show that the addition of C e3+ Salt can significantly increase N 2 H 4 ·H 2 O decomposition hydrogen production activity, while maintaining 100% hydrogen production selectivity. 3+ / (Ni 2+ +Pt 4+ ) molar ratio reaches the optimal value of 1:2, Ni 4 Pt / CeO 2 -MDP has a higher activity than Ni prepared by traditional DP method. 4 Pt / CeO 2 -DP catalyst is 2.3 times higher (515h -1 vs 224h -1 In order to confirm the advantages of the two-step method, the catalyst prepared by the two-step method was further compared with the sample prepared by the one-step method (Ni 4 Pt / CeO 2 The results showed that the sample prepared by the two-step method had a significant activity advantage. The possible reason was that the active sites of the catalyst prepared by the one-step method were easily shielded, resulting in low activity (156h -1 ).

[0088] Figure 8 The effect of heat treatment temperature on Ni 4 Pt / CeO 2 -MDP sample catalyzed N 2 H 4 ·H 2 The kinetic performance of hydrogen production by O decomposition was affected. When the heat treatment temperature was 300°C, the performance was optimal, and the reaction rate reached 515h at 50°C and 2M NaOH. -1 .

[0089] Figure 9 a andFigure 9 The b in 4 Pt / CeO 2 -DP and the target sample Ni 4 Pt / CeO 2 -MDP (the reduction heat treatment temperature is 300 °C, Ce 3+ / (Ni 2+ +Pt 4+ ) molar ratio 1:2) durability test results. After 10 cycles, the activity decay amplitude of the reference sample reached 62%, while that of the target sample only decayed by 20%. This difference in activity decay amplitude indicates that the target catalyst has good stability.

[0090] To further explore the reason why the target sample Ni 4 Pt / CeO 2 -MDP maintains good stability, the temperature-programmed desorption-mass spectrometry (abbreviated as TPD-MS) technique was used to analyze the adsorbed products on the surface of the target sample Ni 4 Pt / CeO 2 -MDP (the reduction heat treatment temperature is 300 °C, Ce 3+ / (Ni 2+ +Pt 4+ ) molar ratio 1:2), and the results were compared with those of the reference sample Ni 4 Pt / CeO 2 -DP. The results are as Figure 10 shown, indicating that the adsorption strength and adsorption amount of nitrogen-containing intermediate products on the surface of the reference sample Ni 4 Pt / CeO 2 -DP are higher than those of the target sample Ni 4 Pt / CeO 2 -MDP. Eventually, the stability of the Ni 4 Pt / CeO 2 -MDP catalyst is significantly better than that of Ni 4 Pt / CeO 2 -DP.

[0091] Example 2

[0092] Co 4 Pt / CeO 2 -MDP catalyst synthesis and catalytic performance

[0093] The preparation method of the cerium oxide precursor nanorods is the same as that in Example 1.

[0094] Co 4 Pt / CeO 2- The -MDP catalyst was prepared by an improved precipitation - deposition combined with heat treatment and reduction method. In a typical operation, 10 mL of 0.2 mol / L urea solution was dropped into 50 mL containing 1 mmol of pre - ultrasonicated CeO 2 nanorods, 0.04 mmol of cobalt nitrate, 0.01 mmol of chloroplatinic acid, and 0.025 mmol of cerium nitrate. Then the mixture was kept at 95 °C for 24 h by an oil bath. The collected sample was washed 5 times with deionized water and then dried at 60 °C for 12 h. The sample thus obtained was heat - treated at 300 °C for 1 h in an H 2 atmosphere.

[0095] A reference sample Co 4 Pt / CeO 2 -DP was prepared using a similar procedure, with the only difference being that cerium nitrate was not added in the deposition - precipitation step.

[0096] N 2 H 4 ·H 2 O catalytic decomposition for hydrogen production performance test:

[0097] Figure 11 The kinetic performance curves of the target sample Co 4 Pt / CeO 2 -MDP and the reference sample Co 4 Pt / CeO 2 -DP for catalytic N 2 H 4 ·H 2 O decomposition for hydrogen production are given. The test results show that the activity of the target sample at 50 °C and 2 M NaOH is 229 h -1 , and the hydrogen production selectivity is 100%, while the activity of the reference sample is 105 h -1 , and the hydrogen production selectivity is 100%. This indicates that the additional introduction of Ce 3+ in the precipitation - deposition step has a significant impact on the catalytic performance of N 2 H 4 ·H 2 O catalytic decomposition for hydrogen production.

[0098] Example 3

[0099] Ni 10 Ir / La 2 O 3 -MDP catalyst synthesis and catalytic performance

[0100] La 2 O 3The preparation method of the support is as follows: Dissolve 160 mmol of sodium hydroxide (NaOH, 96%) in 80 mL of deionized water to form a clear solution, and then add 20 mL of 0.2 mol / L lanthanum nitrate solution at a rate of 0.5 mL / min using a dual-channel syringe pump. Then heat the reaction mixture in an oil bath and maintain it at 80 °C for 24 hours, and then cool it to room temperature. Magnetic stirring is maintained throughout the synthesis. Collect the resulting product with a centrifuge, wash it with deionized water until the pH value is neutral, and finally dry it overnight under normal pressure to obtain La 2 O 3 support precursor.

[0101] Ni 10 Ir / La 2 O 3 -MDP catalyst was prepared by an improved method combining precipitation-deposition and heat treatment reduction. In a typical operation, 10 mL of 0.2 mol / L urea ((NH 2 ) 2 CO, 99.5%) solution was dropped into 50 mL containing 1 mmol of La 2 O 3 that had been pre-ultrasonicated, 0.01 mmol of nickel nitrate, 0.001 mmol of iridium chloride acid, and 0.025 mmol of lanthanum nitrate, and then the mixture was maintained at 95 °C for 24 hours through an oil bath. The collected sample was washed 5 times with deionized water and then dried at 60 °C for 12 hours. The sample thus obtained was heat-treated at 300 °C for 1 hour under H 2 atmosphere.

[0102] A reference sample Ni 10 Ir / La 2 O 3 -DP was prepared using a similar procedure, with the only difference being that lanthanum nitrate was not added in the deposition-precipitation step.

[0103] N 2 H 4 ·H 2 O catalytic decomposition hydrogen production performance test:

[0104] Figure 12 The target sample Ni 10 Ir / La 2 O 3 -MDP and the reference sample Ni 10 Ir / La 2 O 3 -DP catalyzing N 2 H 4 ·H 2Kinetic performance curve of hydrogen production by O decomposition. The test results show that the activity of the target sample under the conditions of 50 °C and 2 M NaOH is 139 h -1 and the hydrogen production selectivity is 100%, while the activity of the reference sample is 85 h -1 and the hydrogen production selectivity is 100%. It shows that the additional introduction of La in the precipitation-deposition step 3+ has a significant impact on the hydrogen production performance of N 2 H 4 ·H 2 O catalytic decomposition for hydrogen production.

[0105] Example 4

[0106] Co 3 Ir 2 / La 2 O 3 -DP reference sample synthesis and catalytic performance

[0107] La 2 O 3 The preparation method of the support is the same as that in Example 3.

[0108] Co 3 Ir 2 / La 2 O 3 -MDP catalyst was prepared by an improved method of precipitation-deposition combined with heat treatment reduction. In a typical operation, 10 mL of 0.2 mol / L urea ((NH 2 ) 2 CO, 99.5%) solution was dropped into 50 mL containing 1 mmol of pre-ultrasonicated La 2 O 3 , 0.06 mmol of cobalt nitrate, 0.04 mmol of chloroiridic acid and 0.025 mmol of lanthanum nitrate, and then the mixture was kept at 95 °C for 24 hours by an oil bath. The collected sample was washed 5 times with deionized water and then dried at 60 °C for 12 hours. The sample thus obtained was heat-treated at 300 °C for 1 hour in an H 2 atmosphere to obtain a La 2 O 3 support precursor.

[0109] A reference sample Co 3 Ir 2 / La 2 O 3 -DP was prepared using a similar procedure, except that lanthanum nitrate was not added in the deposition-precipitation step.

[0110] N 2 H 4 ·H 2 O catalytic decomposition for hydrogen production performance test:

[0111] Figure 13 The target sample Co is given 3 Ir 2 / La 2 O 3 -MDP and the reference sample Co 3 Ir 2 / La 2 O 3 -DP catalyze the decomposition kinetics performance curve of NH·H₂O to produce hydrogen. The test results show that: the activity of the target sample at 50 °C and 2 M NaOH is 335 h 2 H 4 ·H 2 O, and the hydrogen production selectivity is 100%, while the activity of the reference sample is 131 h -1 and the hydrogen production selectivity is 100%. It shows that the additional introduction of La in the precipitation-deposition step -1 has a significant impact on the hydrogen production performance of NH·H₂O catalyzed decomposition 3+ for N 2 H 4 ·H 2 O

[0112] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention

Claims

1. A preparation method of a supported alloy catalyst based on the interaction between metal and support, characterized in that, it includes the following steps: Disperse the A metal oxide support, the active metal precursor, and the A metal precursor into water to obtain a dispersion liquid, then add an aqueous solution containing a precipitant, heat and react, and then perform centrifugation or filtration, drying, and reduction heat treatment to obtain a supported alloy catalyst based on the interaction between metal and support. The A metal includes at least one of Ce, Mn, La, and Ti, and the active metal includes at least one of Ni, Co, Ir, Pt, Pd, and Ru.

2. The preparation method according to claim 1, characterized in that, the A metal precursor includes at least one of nitrate, carbonate, acetate, and halide of the A metal; the active metal precursor includes at least one of halide, nitrate, sulfate, and complex of the active metal; the precipitant includes at least one of sodium hydroxide, sodium carbonate, tetramethylammonium hydroxide, and urea.

3. The preparation method according to claim 1, characterized in that, the concentration of the A metal oxide support in the dispersion liquid is 0.1 - 4 mg / mL; the A metal oxide support is pre-ultrasonically treated in water; the time of the ultrasonic treatment is 30 - 60 minutes; the morphology of the A metal oxide support is nanorods, nanosheets, or nanoflowers.

4. The preparation method according to claim 1, characterized in that, the concentration of the active metal precursor in the dispersion liquid is 0.001 - 0.01 mol / L, and the concentration of the A metal precursor is 0.001 - 0.01 mol / L; the molar ratio of the active metal precursor to the A metal precursor is 0.1 - 10:1; the heating reaction is carried out under stirring; the rotation speed of the stirring is 10 - 50 r / min.

5. The preparation method according to claim 1, characterized in that, the temperature of the reaction is 90 - 110 °C, and the time is 6 - 12 hours; the temperature of the drying is 40 - 70 °C, and the time of the drying is 6 - 12 hours.

6. The preparation method according to claim 1, characterized in that, the atmosphere of the reduction heat treatment is hydrogen; the temperature of the reduction heat treatment is 250 - 500 °C; the time of the reduction heat treatment is 1 - 3 hours.

7. A supported alloy catalyst based on the interaction between metal and support prepared by the preparation method according to any one of claims 1 - 6, characterized in that, the catalyst includes an active metal phase and an oxide matrix phase, and the active metal phase is dispersed in the form of nanoparticles on the surface of the oxide matrix phase.

8. The supported alloy catalyst according to claim 7, characterized in that, The oxide matrix phase is a monometallic oxide containing a variable valence state, and the oxide matrix phase is CeO 2 , MnO 2 , TiO 2 or La 2 O 3 ; The active metal phase is a plurality of metals composed of two or more components.

9. The supported alloy catalyst according to claim 8, characterized in that, the active metal phase is a binary alloy of Ni - Co, Ni - Pt, Ni - Ir, Ni - Ru, Ni - Pd, Co - Pt, Co - Ir, Co - Ru, Co - Pd, or a ternary alloy of Ni - Co - Pt, Ni - Co - Ir, Ni - Co - Ru, Ni - Co - Pd; The size of the active metal phase nanoparticles is 1 to 2 nanometers.

10. Use of the supported alloy catalyst based on the interaction between metal and support according to any one of claims 7-9 in the decomposition of hydrazine hydrate to produce hydrogen.

Images