CN113145114A

CN113145114A - Supported noble metal boride catalyst and preparation method and application thereof

Info

Publication number: CN113145114A
Application number: CN202110444506.1A
Authority: CN
Inventors: 王平; 丘玉萍
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-04-23
Filing date: 2021-04-23
Publication date: 2021-07-23
Anticipated expiration: 2041-04-23
Also published as: CN113145114B

Abstract

The invention discloses a supported noble metal boride catalyst, and a preparation method and application thereof. The catalyst comprises an active metal phase and an oxide matrix phase, wherein the active metal phase is dispersed and distributed on the surface of the oxide matrix phase in a nanoparticle form, and the active metal phase is boride of one or more noble metals. The development of efficient catalyst design concept and controllable synthesis method is to advance N₂H₄·H₂The key problem to be solved urgently in the practical process of the O-controllable hydrogen production technology. The invention provides a synthesis method of a high-performance noble metal boride catalyst, which has the advantages of easily obtained raw materials, simple and convenient operation and convenient mass production. The prepared catalyst is applied to N for the first time₂H₄·H₂The O catalytic decomposition hydrogen production system has high characteristic performance and rich active sites,can catalyze N efficiently and stably at the condition of near room temperature₂H₄·H₂And O is decomposed to produce hydrogen, and the activity of the O is at the top level of the catalyst reported at present.

Description

Supported noble metal boride catalyst and preparation method and application thereof

Technical Field

The invention belongs to the field of hydrogen production technology and materials, and particularly relates to a supported noble metal boride catalyst, and a preparation method and application thereof.

Background

Hydrogen energy is used as a clean and efficient secondary energy source, and is expected to solve global problems of energy crisis, environmental pollution and the like for human beings. But the large-scale application of hydrogen energy needs to solve the scientific/technical challenges of hydrogen production, hydrogen storage and hydrogen utilization, wherein the hydrogen storage link is the most prominent. Therefore, the development of hydrogen storage materials and hydrogen production technology has great significance for realizing sustainable development. Research by global scholars for decades shows that the working environment of the reversible hydrogen storage material can not or simultaneously meet the application requirements of vehicle-mounted fuel cells. In view of the current research situation, since 2000 years ago, various researchers of various countries have been dedicated to the research on the hydrogen-releasing controllable technology of chemical hydrogen storage materials, and thus the research heat of the chemical hydrogen storage materials is brought forward. Wherein hydrazine hydrate (N)₂H₄·H₂O) as a novel chemical hydride not only has the integrated characteristic of typical hydrogen storage/production, but also has the outstanding advantages of high hydrogen storage density (8 wt%), low price (2$/L), good chemical stability, no solid by-product generated in hydrogen production reaction and the like, and the application potential in the aspect of vehicle-mounted/portable hydrogen sources is the best.

Development of N₂H₄·H₂The key point of the O controllable hydrogen production technology lies in the development of a catalyst with high activity, high hydrogen production selectivity and good stability. Earlier researches show that single metal Ir, Ru and Ni are the three metals of N₂H₄·H₂The O decomposition reaction shows different catalytic properties. Wherein, the noble metals Ir and Ru have high catalytic activity, but the hydrogen production selectivity is too low; although the transition metal Ni shows higher hydrogen production selectivity, the catalytic activity of the transition metal Ni is far lower than that of noble metals Ir and Ru. In recent years, various researchers comprehensively use modification strategies such as alloying, structural nanocrystallization, introduction of basic oxide carriers and the like, so that the activity and hydrogen production selectivity of the catalyst are greatly improved on the whole, wherein the development of a series of binary alloy catalysts formed by non-noble metal Ni and noble metals such as Pt, Ir, Rh and the like is particularly rapid. However, representative Ni-Pt alloy catalysts can catalyze N100% selectively at near room temperature₂H₄·H₂O decomposes to produce hydrogen, but its catalytic activity is (2194 h)^-1) But far lower than single metal Ir (nearly 8000 h)^-1) And the practical requirements of the hydrogen production system can not be met. In the scientific research practice aiming at turning back the situation, research objects aiming at developing high-performance Ni-based binary alloy catalysts are still used, but in contrast, the comprehensive catalytic performance of the Ir-based catalyst is obviously more practical through mainly investigating the comprehensive catalytic performance of the Ir-based catalyst by breaking through the research strategies of conventional element selection and widening component exploration space.

At present, the noble metal boride has wide application prospects in the fields of catalysis, flame retardants and the like. The ceramic material is mainly prepared by adopting an arc melting or high-temperature sintering method, and needs The strict condition of a vacuum sealed quartz boat (The crystal chemistry of platinum metal borides). The method not only consumes a large amount of energy and cannot be produced in batches, but also has no safety. In view of the above, there is a strong need for a simple method for producing a noble metal boride in large quantities.

Disclosure of Invention

The invention aims to provide a method suitable for N₂H₄·H₂A supported noble metal boride catalyst for O catalytic decomposition reaction and a preparation method thereof. The method has the advantages of easily obtained raw materials, simple and convenient operation and convenient mass production, and the prepared catalyst has high intrinsic catalytic performance and rich active sites and can efficiently and stably catalyze N under alkaline conditions₂H₄·H₂The O decomposition hydrogen production reaction has comprehensive catalytic performance at the top level at present.

A supported noble metal boride catalyst, a preparation method and application thereof. The catalyst consists of an active metal phase and an oxide matrix phase, wherein the active metal phase is dispersed and distributed on the surface of the oxide matrix phase in a fine nano-particle form; meanwhile, the oxide matrix has strong interaction with the active metal phase. The preparation method of the catalyst is NaBH₄A chemical reduction method is combined with a two-step reduction heat treatment method, and firstly, a salt water solution containing a metal precursor is used as an initial raw material, and NaBH is utilized₄An alkali liquor is used as a reducing agent to grow an active metal phase (active metal ions and NaBH) on the surface of a carrier material (hydroxide or oxide generated by the reaction of carrier metal salt and an alkali precipitator)₄Oxidation-reduction reaction generation takes placeMetal phase) and then the interaction between the metal and the carrier is strengthened by regulating and controlling the reducing heat treatment condition.

The purpose of the invention is realized by the following technical scheme:

a supported noble metal boride catalyst, the catalyst comprising an active metal phase and an oxide matrix phase, the active metal phase being dispersed and distributed on the surface of the oxide matrix phase in the form of nanoparticles, the active metal phase being a boride of one or more noble metals.

Preferably, the active metal phase is boride of Ir, Ru, Pt and Pd, binary noble metal boride of Ir-Ru, Ir-Pt, Ru-Pt, Ir-Pd, Pt-Pd and Ru-Pd, and ternary noble metal boride of Ir-Pt-Pd, Ir-Ru-Pt, Ir-Ru-Pd and Ru-Pt-Pd. Further preferably, the active metal phase is Ir-Ru-B.

Preferably, the size of the active metal phase nano particles is 1-2 nanometers;

preferably, the oxide matrix has a strong interaction with the active metal.

Preferably, the oxide matrix is present in the form of a nanocrystal;

preferably, the oxide matrix phase is a monometallic oxide containing multiple valence states. More preferably, the oxide matrix phase is CeO₂、MnO₂、TiO₂Or La₂O₃. More preferably CeO₂。

The preparation method of the supported noble metal boride catalyst comprises the following steps:

(1) the aqueous solution containing noble metal salt and carrier precursor salt is solution A, and NaBH containing precipitant₄The water solution is solution B, the solution B is poured into the solution A under the condition of stirring at room temperature, and the precipitate is collected after the reaction;

(2) and (2) washing and drying the precipitate in the step (1), and performing heat treatment in a reducing gas atmosphere to obtain the supported noble metal boride catalyst.

Preferably, the carrier precursor salt comprises a nitrate, chloride, carbonate, acetate, halide of a carrier metal comprising: ce. Mn, La, Ti; more preferably a nitrate;

preferably, the noble metal salt comprises a halide chloride, nitrate, sulfate, complex of a noble metal, the noble metal comprising: ir, Pt, Pd, Ru; more preferably chloride;

preferably, the precipitant comprises sodium hydroxide, sodium carbonate, tetramethylammonium hydroxide, urea. More preferably sodium hydroxide.

Preferably, the solution B is poured into the solution A at the rate of 0.5-2 mL/min; more preferably at a rate of 1 mL/min.

Preferably, the concentration of the noble metal salt in the solution A in the step (1) is 0.01-0.04M; carrier precursor salt 0.1-0.4M;

preferably, the concentration of the precipitator in the solution B is 0.1-0.3M;

preferably, the temperature of the reaction is 25-35 ℃; the reaction time is 6-12 hours.

Preferably, NaBH in the solution B₄The concentration is 0.05-0.2M;

preferably, the volume ratio of the solution A to the solution B is 0.5-1.5: 1;

preferably, the reducing atmosphere in the step (2) is hydrogen;

preferably, the temperature of the heat treatment is 300-700 ℃; the heat treatment time is 1-2 hours.

The supported noble metal boride catalyst is applied to the decomposition of hydrazine hydrate to prepare hydrogen.

The design principle of the invention is as follows:

for N₂H₄·H₂The catalyst for producing hydrogen by catalytic decomposition of O has three factors influencing the apparent catalytic performance: intrinsic properties, number of active sites and mass transfer capacity. For decades, research has shown that noble metal Ir is a highly efficient catalyst for N₂H₄·H₂In order to improve the hydrogen production selectivity of the catalyst for producing ammonia by decomposing O, an empirical trial method is generally adopted to introduce an alloy element transition metal and an alkaline oxide carrier, so that the hydrogen production selectivity is greatly improved, but the ultrahigh activity of the catalyst is usually sacrificed. To ensure high activity and simultaneously ensure higher activityThe hydrogen production selectivity needs to be expanded, the exploration range of active component elements needs to be expanded, and the hydrogen production selectivity is not limited to conventional elements (such as Ni and Co). The catalyst provided by the invention is innovative in element selection and preparation method. The catalyst is applied to N for the first time₂H₄·H₂O is catalytically decomposed to produce hydrogen, and the excellent comprehensive catalytic performance is shown; in addition, the traditional preparation method of the noble metal boride usually adopts a high-temperature and severe working environment, and the catalyst provided by the invention also provides simple NaBH₄The reduction method is realized. Firstly, the prepared saline solution containing noble metal and carrier precursor is used as solution A, and NaBH containing alkali is added₄The aqueous solution is solution B, the solution B is quickly poured into the solution A under the condition of stirring at room temperature, and the carrier and the precipitator react to form oxide in the process; and NaBH₄The B element is introduced while the B element and the noble metal precursor salt are subjected to an oxidation reduction method to form the noble metal boride. Finally, the surface of the oxide matrix is loaded with the precious metal boride which is finely dispersed and distributed; and then, the interaction between the metal and the carrier is strengthened under the condition of high-temperature heat treatment by utilizing the multivariable valence state characteristic of the carrier oxide, and a regulation space is provided for the electronic structure on the surface of the active metal phase. In summary, the present invention provides N₂H₄·H₂The catalyst for preparing hydrogen by catalytic decomposition of O has high characteristic performance and rich active sites.

The invention has the advantages and beneficial effects that:

(1) the invention provides a novel preparation method of a supported noble metal boride catalyst suitable for preparing hydrogen by decomposing hydrazine hydrate. The method is different from the traditional method in that the method is simple and easy to implement, is rapid and can be produced in large scale. Binding of NaBH₄The supported noble metal boride is synthesized by a reduction and precipitation method in one step by using NaBH₄The strong reduction action of the method can quickly reduce fine and dispersed noble metal boride nano particles, and is beneficial to improving the utilization efficiency of active sites; in addition, on the basis of synthesizing the prepared supported noble metal boride material, the strong interaction between the active metal phase and the matrix oxide is enhanced by regulating and controlling the heat treatment condition, so that the intrinsic property of the catalyst is further improvedAnd (4) performance.

(2) The novel preparation method of the supported noble metal boride catalyst suitable for preparing hydrogen by decomposing hydrazine hydrate, provided by the invention, has the advantages of easily available raw materials, simple process, convenience for mass production and no pollution in the whole process.

(3) The invention provides ultra-high activity N₂H₄·H₂The catalyst for producing hydrogen by catalytic decomposition of O can efficiently catalyze N under alkaline conditions₂H₄·H₂O decomposes to produce hydrogen, and has excellent durability, and the comprehensive catalytic performance is in the current top level.

Drawings

FIG. 1a is a sample Ir in the heated state from example 1₇₀Ru₃₀-B/CeO₂The insert is selected area electron diffraction.

FIG. 1b is a sample Ir in the heated state from example 1₇₀Ru₃₀-B/CeO₂AC HAADF-STEM photograph of (1).

FIG. 1c shows a sample Ir in the heated state from example 1₇₀Ru₃₀-B/CeO₂And its corresponding element distribution map at atomic resolution.

FIG. 2 is the unloaded Ir of example 1₇₀Ru₃₀B samples and series Ir₇₀Ru₃₀-B/CeO₂XRD pattern of the sample.

FIG. 3a is Ir of example 1₇₀Ru₃₀-B/CeO₂XPS results of samples: b1 s.

FIG. 3b is Ir from example 1₇₀Ru₃₀-B/CeO₂Sample and reference Ir/CeO₂And Ru/CeO₂XPS results of (a): ir 4 f.

FIG. 3c is Ir from example 1₇₀Ru₃₀-B/CeO₂Sample and reference Ir/CeO₂And Ru/CeO₂XPS results of (a): ru 3 d.

FIG. 4 shows the unloaded Ir of example 1₇₀Ru₃₀XPS results for B and reference metals Ir, Ru and boron powders: ir 4f, Ru 3d and B1 s.

FIG. 5a shows the unloaded Ir of example 1₇₀Ru₃₀-B and Ir in the heated state₇₀Ru₃₀-B/CeO₂XPS results of samples: ir 4 f.

FIG. 5b shows the unloaded Ir of example 1₇₀Ru₃₀-B and Ir in the heated state₇₀Ru₃₀-B/CeO₂XPS results of samples: ru 3 d.

FIG. 6 shows Ir as prepared and as heated in example 1₇₀Ru₃₀-B/CeO₂Sample catalysis N₂H₄·H₂O decomposition kinetics curve.

FIG. 7a is Ir as heated for the reference sample of example 1₇₀Ru₃₀/CeO₂Cycle kinetics profile of the catalyst (coprecipitation-reduction heat treatment process).

FIG. 7b shows Ir as heated for example 1₇₀Ru₃₀-B/CeO₂The cyclic kinetic curve of (c).

FIG. 8 shows heated Ir as in example 1₇₀Ru₃₀-B/CeO₂The phase and microstructure of the catalyst after cycle test are characterized. (a) HAADF-STEM picture, and the inset is SAED picture; (b) HRTEM; (c) XRD pattern.

FIG. 9 shows heated Ir as in example 1₇₀Ru₃₀-B/CeO₂And Ir₇₀Ru₃₀/CeO₂TPD-MS result chart of catalyst.

FIG. 10 shows a sample Ir in a heated state in example 2₇₀Pt₃₀-B/CeO₂The HRTEM photograph of (A).

FIG. 11 shows heated Ir as in example 2₇₀Pt₃₀-B/CeO₂XRD pattern of the sample.

FIGS. 12a-c are non-load Ir as in example 2₇₀Pt₃₀XPS results plot of B sample: ir 4f (B), Pt 4f (c) and B1s (a).

FIG. 13 shows heated Ir as in example 2₇₀Pt₃₀-B/CeO₂With Ir-B/CeO₂Sample catalysis N₂H₄·H₂O decomposition kinetics curve.

FIG. 14 shows a sample Ir in a heated state in example 3₇₀Rh₃₀-B/CeO₂And Ir-B/CeO₂Sample catalysis N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production.

FIG. 15 shows a sample Ir in a heated state in example 4₇₀Au₃₀-B/CeO₂And Ir-B/CeO₂Sample catalysis N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production.

Detailed Description

The present invention is specifically described below with reference to examples, but the embodiments and the scope of the present invention are not limited to the following examples.

In a specific embodiment of the invention, the noble metal precursor salt, the precipitant, and the support material are selected according to the design of the catalyst composition. Generating a matrix oxide by utilizing chemical reduction and precipitation reaction in one step, simultaneously loading fine and dispersedly distributed metal nano particles on the surface of the oxide, and fully cleaning the prepared sample and then carrying out vacuum drying at room temperature; and (3) heating the prepared sample at a high temperature (300-700 ℃) in a reducing atmosphere, carrying out constant temperature treatment for a set time, and cooling to room temperature to obtain the target catalyst.

The present invention is described in detail below with reference to specific examples.

Example 1

Ir₇₀Ru₃₀-B/CeO₂Synthesis, structure and catalytic performance of catalyst

Catalyst preparation

The prepared load type Ir-Ru-B/CeO is obtained by adopting a co-reduction method₂Catalyst with Ir/Ru molar ratio of 7/3, (Ir + Ru) and CeO₂The molar ratio was fixed at 1/10. The specific experimental steps are as follows: 0.07mmol H was added to a 100mL round bottom flask in sequence₂IrCl₆、0.03mol RuCl₃、1mmol Ce(NO₃)₃·6H₂O and 10mL H₂O, under the condition of magnetic stirring at room temperature, quickly adding 10mL of 0.1mol/L NaBH₄And 0.3mol/L NaOH for 12 hours, then carrying out centrifugal separation, washing the collected precipitate with water and alcohol, and carrying out vacuum drying at room temperature for 12 hours to prepare a preparation-state sample. The as-prepared sample was then placed in H₂Heating to 600 ℃ in atmosphere at a heating rate of 10 DEG CAnd/min, cooling to room temperature after 1 hour of constant temperature treatment to prepare the target catalyst (heated sample).

Unloaded Ir₇₀Ru₃₀-B sample preparation: only differs from the above-mentioned preparation method in that Ce (NO) is not added₃)₃·6H₂O, the others are the same.

Ir₇₀Ru₃₀/CeO₂Preparation of the catalyst: and (3) combining coprecipitation and heat treatment to prepare a reference sample. Specifically, first, solution A (0.07mmol H) was freshly prepared₂IrCl₆+0.03mol H₂PtCl₆+1mmol Ce(NO₃)₃·6H₂O+10mL H₂O) and B solution (3mmol NaOH +10mL H₂And O), then quickly pouring the solution B into the solution A, reacting for 6 hours, centrifugally drying the reaction solution, and drying in vacuum for 12 hours to obtain a prepared sample. The as-prepared sample was then placed in H₂Heating to 500 ℃ in the atmosphere, heating at a rate of 10 ℃/min, carrying out constant temperature treatment for 1 hour, and cooling to room temperature to obtain a reference sample.

Ir/CeO₂And Ru/CeO₂The preparation of (1): with reference sample Ir₇₀Ru₃₀/CeO₂The preparation method is similar, except that the noble metal precursor salt is the same as the others

Characterization of phase/structure/elemental chemistry of the catalyst:

transmission electron microscopy (fig. 1a) found: heated specimen Ir₇₀Ru₃₀-B/CeO₂A large number of fine and dispersed nano particles are distributed on the substrate, and the particle size is about 1-2 nm; selective area electron diffraction in the inset confirms nanocrystalline CeO₂Presence of a phase. The high resolution transmission electron microscopy (FIG. 1b) further confirmed the CeO₂The formation of phase, and in addition, the Ir-Ru alloy with the size of about 1-2 nanometers is also found. From the EDS element distribution results (FIG. 1c), Ir was confirmed₇₀Ru₃₀-B/CeO₂The Ir-Ru in the sample is alloyed, and further characterization is required with respect to the form of B present and its manner of incorporation with the metals Ir and Ru.

XRD analysis (FIG. 2) shows that samples Ir are in the as-prepared and heated states₇₀Ru₃₀-B/CeO₂Only CeO was detected₂Diffraction peaks of the phase. To exclude the matrix CeO₂Of unsupported Ir synthesized by a similar method₇₀Ru₃₀XRD of the-B sample confirmed the formation of Ir-Ru alloy.

According to X-ray photoelectron spectroscopy (FIGS. 3a-c), preparative Ir was revealed₇₀Ru₃₀-B/CeO₂Ir of the sample⁰And Ru⁰All negative shifts occurred relative to the standard sample, whereas B only shows the oxidation state signal; to further exclude the matrix CeO₂For non-loaded Ir₇₀Ru₃₀XPS analysis of the B sample (FIG. 4), indicating an unloaded Ir₇₀Ru₃₀Formation of Ir-Ru-B alloy in the-B sample, which indirectly confirms Ir₇₀Ru₃₀-B/CeO₂Ir-Ru-B in the sample is alloyed. In addition, the XPS results of the as-prepared and as-heated samples were carefully compared (FIGS. 5a and 5b) to show that the matrix CeO was induced under heating₂The electrons of (a) are transferred to the active metal, confirming that there is a strong interaction between the metal and the matrix.

N₂H₄·H₂O catalytic decomposition hydrogen production performance test

FIG. 6 shows a sample Ir in the heated state₇₀Ru₃₀-B/CeO₂Catalysis of N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production. The test result shows that: the heated sample shows ultrahigh catalytic activity, and the reaction rate of the sample reaches 11510h under the conditions of 50 ℃ and 2M NaOH^-1The catalytic activity is at the level of the peak of the catalysts reported so far.

FIGS. 7a and 7b show the heated samples Ir₇₀Ru₃₀-B/CeO₂And a reference sample Ir₇₀Ru₃₀/CeO₂According to the durability test result of the catalyst (prepared by adopting a coprecipitation-heat treatment method), after 10 cycles, the activity of the catalyst is still maintained at 18%, while the activity of the catalyst shows obvious activity attenuation (attenuation amplitude is 70%), and the activity retention rate difference indicates that the target catalyst has good stability.

FIG. 8 shows the heating stateSample Ir₇₀Ru₃₀-B/CeO₂The phase/microstructure result of the catalyst after 10 times of cycle tests shows that the morphology and the phase structure of the catalyst are not obviously changed, which indicates that the catalyst has good structural stability.

To further explore the heated sample Ir₇₀Ru₃₀-B/CeO₂The catalyst maintains good stability, and the adsorption product on the surface of the sample is analyzed by utilizing a temperature programmed desorption-mass spectrometry (TPD-MS) technology and is combined with a reference sample Ir₇₀Ru₃₀/CeO₂The results of the catalysts were compared. The results are shown in FIG. 9, which indicates that the reason for the above-mentioned catalyst deactivation is mainly due to the fact that the N-containing intermediate product is adsorbed too strongly, while the B doping is effective in reducing N₂H₄The adsorption strength of the decomposition intermediate or final product with the catalyst surface, resulting in Ir₇₀Ru₃₀-B/CeO₂The stability of the catalyst is clearly superior to the latter.

Example 2

Ir₇₀Pt₃₀-B/CeO₂Synthesis, structure and catalytic performance of catalyst

Preparing a catalyst: first, a solution A (0.07mmol H) was freshly prepared₂IrCl₆+0.03mol H₂PtCl₆+1mmol Ce(NO₃)₃·6H₂O+10mL H₂O) and B solution (1mmol NaBH)₄+3mmol NaOH+10mL H₂And O), then quickly pouring the solution B into the solution A, reacting for 6 hours, centrifugally drying the reaction solution, and drying in vacuum for 12 hours to obtain a prepared sample. The as-prepared sample was then placed in H₂Heating to 500 ℃ in the atmosphere, heating at a rate of 10 ℃/min for 1 hour, and cooling to room temperature to obtain a heated sample.

Unloaded Ir₇₀Pt₃₀-B sample preparation: only differs from the above-mentioned preparation method in that Ce (NO) is not added₃)₃·6H₂O, the others are the same.

Ir-B/CeO₂Preparation of the catalyst: and Ir₇₀Pt₃₀-B/CeO₂The synthesis of the catalyst is similar, differing onlyIn the noble metal precursor salt.

Phase/structure characterization of the catalyst:

the high resolution transmission electron microscope (FIG. 10) shows that the phase composition of the target sample is CeO₂And an Ir-Pt alloy phase, wherein the alloy nanoparticles have a size of about 1 to 2 nanometers.

XRD analysis (fig. 11) showed that: ir₇₀Pt₃₀-B/CeO₂Sample only detected CeO₂Diffraction peaks of the phase.

XPS technique (FIGS. 12a-c) gives the unloaded Ir₇₀Pt₃₀Results of Ir 4f, Pt 4f and B1s spectra for the B sample, indicating unsupported Ir₇₀Pt₃₀Ir-Pt-B alloying in the B sample.

N₂H₄·H₂Testing the performance of O catalytic decomposition hydrogen production:

FIG. 13 shows a sample Ir in a heated state₇₀Pt₃₀-B/CeO₂And Ir-B/CeO₂Sample catalysis N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production. The test result shows that: the activity of the heated sample under the conditions of 50 ℃ and 2M NaOH is 429h^-1) The hydrogen production selectivity is 30 percent, which shows that different alloy components are paired with N₂H₄·H₂The performance of the O catalytic decomposition hydrogen production has obvious influence.

Example 3

Ir₇₀Rh₃₀-B/CeO₂Synthesis and catalytic performance of catalyst

Preparing a catalyst: first, a solution A (0.07mmol H) was freshly prepared₂IrCl₆+0.03mol RhCl₃+1mmol Ce(NO₃)₃·6H₂O+10mL H₂O) and B solution (1mmol NaBH)₄+3mmol NaOH+10mL H₂And O), then quickly pouring the solution B into the solution A, reacting for 6 hours, centrifugally drying the reaction solution, and drying in vacuum for 12 hours to obtain a prepared sample. The as-prepared sample was then placed in H₂Heating to 500 ℃ in the atmosphere, heating at a rate of 10 ℃/min for 1 hour, and cooling to room temperature to obtain a heated sample.

Ir-B/CeO₂Preparation of the catalyst: and Ir₇₀Rh₃₀-B/CeO₂The synthesis of the catalyst is similar, differing only in the noble metal precursor salt.

FIG. 14 shows a sample Ir in a heated state₇₀Rh₃₀-B/CeO₂And Ir-B/CeO₂Sample catalysis N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production. The test result shows that: the activity of the heated sample is 502h under the conditions of 50 ℃ and 2M NaOH^-1) The hydrogen production selectivity is 39 percent, which shows that different alloy components are paired with N₂H₄·H₂The performance of the O catalytic decomposition hydrogen production has obvious influence.

Example 4

Ir₇₀Au₃₀-B/CeO₂Synthesis and catalytic performance of catalyst

Preparing a catalyst: first, a solution A (0.07mmol H) was freshly prepared₂IrCl₆+0.03mol Au Cl₃+1mmol Ce(NO₃)₃·6H₂O+10mL H₂O) and B solution (1mmol NaBH)₄+3mmol NaOH+10mL H₂And O), then quickly pouring the solution B into the solution A, reacting for 6 hours, centrifugally drying the reaction solution, and drying in vacuum for 12 hours to obtain a prepared sample. The as-prepared sample was then placed in H₂Heating to 500 ℃ in the atmosphere, heating at a rate of 10 ℃/min for 1 hour, and cooling to room temperature to obtain a heated sample.

Ir-B/CeO₂Preparation of the catalyst: and Ir₇₀Au₃₀-B/CeO₂The synthesis of the catalyst is similar, differing only in the noble metal precursor salt.

FIG. 15 shows a sample Ir in a heated state₇₀Au₃₀-B/CeO₂And Ir-B/CeO₂Sample catalysis N₂H₄·H₂Kinetic performance curve of O decomposition hydrogen production. The test result shows that: heating ofThe sample in the state shows the activity of 583h under the conditions of 50 ℃ and 2M NaOH^-1) The hydrogen production selectivity is 27 percent, which shows that different alloy components are paired with N₂H₄·H₂The performance of the O catalytic decomposition hydrogen production has obvious influence.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The supported noble metal boride catalyst is characterized by comprising an active metal phase and an oxide matrix phase, wherein the active metal phase is dispersed and distributed on the surface of the oxide matrix phase in a nanoparticle form, and the active metal phase is one or more noble metal borides.

2. The supported noble metal boride catalyst of claim 1 wherein the active metal phase is a boride of Ir, Ru, Pt, Pd, a binary noble metal boride of Ir-Ru, Ir-Pt, Ru-Pt, Ir-Pd, Pt-Pd, Ru-Pd, a ternary noble metal boride of Ir-Pt-Pd, Ir-Ru-Pt, Ir-Ru-Pd, Ru-Pt-Pd.

3. The supported noble metal boride catalyst of claim 1 wherein the active metal phase nanoparticles are 1 to 2 nanometers in size; the oxide matrix has a strong interaction with the active metal.

4. The supported noble metal boride catalyst of claim 1 wherein the oxide matrix is present in the form of a nanocrystal; the oxide matrix phase is a single-element metal oxide containing multiple valence states.

5. The supported noble metal boride catalyst of claim 4 characterized in thatThen, the oxide matrix phase is CeO₂、MnO₂、TiO₂Or La₂O₃。

6. A process for the preparation of a supported noble metal boride catalyst according to any one of claims 1 to 5, characterized in that it comprises the steps of:

7. The method of claim 6, wherein the carrier precursor salt comprises a nitrate, chloride, carbonate, acetate, halide, of a carrier metal comprising: ce. Mn, La, Ti; the noble metal salt comprises halogen chloride, nitrate, sulfate and complex of noble metal, and the noble metal comprises: ir, Pt, Pd, Ru; the precipitant comprises sodium hydroxide, sodium carbonate, tetramethyl ammonium hydroxide and urea.

8. The preparation method according to claim 6, wherein the concentration of the noble metal salt in the solution A in the step (1) is 0.01 to 0.04M, and the concentration of the carrier precursor salt is 0.1 to 0.4M; the concentration of the precipitator in the solution B is 0.1-0.3M; the reaction temperature is 25-35 ℃; the reaction time is 6-12 hours.

9. The method according to claim 6, wherein the reducing atmosphere in the step (2) is hydrogen; the temperature of the heat treatment is 300-700 ℃; the heat treatment time is 1-2 hours.

10. Use of a supported noble metal boride catalyst according to any one of claims 1 to 5 in the decomposition of hydrazine hydrate to produce hydrogen.