CN113145114B - Supported noble metal boride catalyst and preparation method and application thereof - Google Patents
Supported noble metal boride catalyst and preparation method and application thereof Download PDFInfo
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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 N 2 H 4 ·H 2 The 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 time 2 H 4 ·H 2 The O catalytic decomposition hydrogen production system has high characteristic performance and rich active sites, and can efficiently and stably catalyze N at the near room temperature 2 H 4 ·H 2 And O is decomposed to produce hydrogen, and the activity of the O is at the top level of the catalyst reported at present.
Description
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. Number of learners going through the worldDecades of research show 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) 2 H 4 ·H 2 O) 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 N 2 H 4 ·H 2 The 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 N 2 H 4 ·H 2 The 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 and introduction of basic oxide carriers to greatly improve the activity and hydrogen production selectivity of the catalyst on the whole, wherein the development of series binary alloy catalysts formed by non-noble metal Ni and noble metals such as Pt, Ir and Rh is particularly rapid. However, representative Ni-Pt alloy catalysts can catalyze N100% selectively at near room temperature 2 H 4 ·H 2 O 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 a large amount.
Disclosure of Invention
The invention aims to provide a method suitable for N 2 H 4 ·H 2 A 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 conditions 2 H 4 ·H 2 The 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 NaBH 4 A 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 utilized 4 An 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) 4 Redox occurs to generate a metal phase), and then interaction between the metal and the carrier is enhanced by regulating and controlling the reduction 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 precious metal boride of Ir-Ru, Ir-Pt, Ru-Pt, Ir-Pd, Pt-Pd and Ru-Pd, and ternary precious 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 CeO 2 、MnO 2 、TiO 2 Or La 2 O 3 . More preferably CeO 2 。
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 precipitant 4 The 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, tetramethyl ammonium hydroxide and 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 B 4 The 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 N 2 H 4 ·H 2 The 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 N 2 H 4 ·H 2 In 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. In order to ensure high hydrogen production selectivity while ensuring high activity, the exploration range of active component elements needs to be expanded, and the active component elements are 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 time 2 H 4 ·H 2 O 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 high-temperature and severe working environment, and the catalyst provided by the invention also providesProvides simple NaBH 4 The 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 added 4 The 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 NaBH 4 The 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 N 2 H 4 ·H 2 The 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 NaBH 4 The supported noble metal boride is synthesized by a reduction and precipitation method in one step by using NaBH 4 The 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 conditions, so that the intrinsic performance of the catalyst is further improved.
(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 N 2 H 4 ·H 2 The catalyst for preparing hydrogen by catalytic decomposition of O can efficiently catalyze N under alkaline conditions 2 H 4 ·H 2 O is decomposed to produce hydrogen,meanwhile, the catalyst 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 1 70 Ru 30 -B/CeO 2 The insert is selected area electron diffraction.
FIG. 1b is a sample Ir in the heated state from example 1 70 Ru 30 -B/CeO 2 AC HAADF-STEM photograph of (1).
FIG. 1c shows a sample Ir in the heated state from example 1 70 Ru 30 -B/CeO 2 And its corresponding element distribution map at atomic resolution.
FIG. 2 is an unloaded Ir as in example 1 70 Ru 30 B samples and series Ir 70 Ru 30 -B/CeO 2 XRD pattern of the sample.
FIG. 3a is Ir of example 1 70 Ru 30 -B/CeO 2 XPS results of samples: b1 s.
FIG. 3b is Ir from example 1 70 Ru 30 -B/CeO 2 Sample and reference Ir/CeO 2 And Ru/CeO 2 XPS results of (a): ir 4 f.
FIG. 3c is Ir from example 1 70 Ru 30 -B/CeO 2 Sample and reference Ir/CeO 2 And Ru/CeO 2 XPS results of (a): ru 3 d.
FIG. 4 shows the unloaded Ir of example 1 70 Ru 30 XPS 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 1 70 Ru 30 -B and Ir in the heated state 70 Ru 30 -B/CeO 2 XPS results of samples: ir 4 f.
FIG. 5b shows the unloaded Ir of example 1 70 Ru 30 -B and Ir in the heated state 70 Ru 30 -B/CeO 2 XPS results of samples: ru 3 d.
FIG. 6 shows Ir as prepared and as heated in example 1 70 Ru 30 -B/CeO 2 Sample catalysis N 2 H 4 ·H 2 O isA solution kinetic curve.
FIG. 7a is Ir as heated for the reference sample of example 1 70 Ru 30 /CeO 2 Cycle kinetics profile of the catalyst (coprecipitation-reduction heat treatment process).
FIG. 7b shows Ir as heated for example 1 70 Ru 30 -B/CeO 2 The cyclic kinetic curve of (c).
FIG. 8 shows heated Ir as in example 1 70 Ru 30 -B/CeO 2 And (3) characterizing the phase and microstructure of the catalyst after cycle testing. (a) HAADF-STEM picture, and the inset is SAED picture; (b) HRTEM; (c) XRD pattern.
FIG. 9 shows heated Ir as in example 1 70 Ru 30 -B/CeO 2 And Ir 70 Ru 30 /CeO 2 TPD-MS result chart of catalyst.
FIG. 10 shows a sample Ir in a heated state in example 2 70 Pt 30 -B/CeO 2 The HRTEM photograph of (A).
FIG. 11 is Ir in the heated state for example 2 70 Pt 30 -B/CeO 2 XRD pattern of the sample.
FIGS. 12a-c are non-load Ir as in example 2 70 Pt 30 XPS results plot of B sample: ir 4f (B), Pt 4f (c) and B1s (a).
FIG. 13 shows heated Ir as in example 2 70 Pt 30 -B/CeO 2 With Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 O decomposition kinetics curve.
FIG. 14 shows a sample Ir in a heated state in example 3 70 Rh 30 -B/CeO 2 And Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 Kinetic performance curve of O decomposition hydrogen production.
FIG. 15 shows a sample Ir in a heated state in example 4 70 Au 30 -B/CeO 2 And Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 Kinetic 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
Ir 70 Ru 30 -B/CeO 2 Synthesis, structure and catalytic performance of catalyst
Catalyst preparation
The prepared load type Ir-Ru-B/CeO is obtained by adopting a co-reduction method 2 Catalyst with Ir/Ru molar ratio of 7/3, (Ir + Ru) and CeO 2 The 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 sequence 2 IrCl 6 、0.03mol RuCl 3 、1mmol Ce(NO 3 ) 3 ·6H 2 O and 10mL H 2 O, under the condition of magnetic stirring at room temperature, quickly adding 10mL of 0.1mol/L NaBH 4 And 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 taken at H 2 Heating to 600 ℃ in the atmosphere, heating at the rate of 10 ℃/min, carrying out constant temperature treatment for 1 hour, and cooling to room temperature to obtain the target catalyst (heated sample).
Unloaded Ir 70 Ru 30 -B sample preparation: only differs from the above-mentioned preparation method in that Ce (NO) is not added 3 ) 3 ·6H 2 O, the others are the same.
Ir 70 Ru 30 /CeO 2 Preparation of the catalyst: the reference is prepared by combining coprecipitation and heat treatmentAnd (3) sampling. Specifically, first, solution A (0.07mmol H) was freshly prepared 2 IrCl 6 +0.03mol H 2 PtCl 6 +1mmol Ce(NO 3 ) 3 ·6H 2 O+10mL H 2 O) and B solution (3mmol NaOH +10mL H 2 And O), 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 taken at H 2 Heating 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/CeO 2 And Ru/CeO 2 The preparation of (1): with reference sample Ir 70 Ru 30 /CeO 2 The 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 Ir 70 Ru 30 -B/CeO 2 A 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 CeO 2 Presence of a phase. The high resolution transmission electron microscopy (FIG. 1b) further confirmed the CeO 2 The 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 confirmed 70 Ru 30 -B/CeO 2 The 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 states 70 Ru 30 -B/CeO 2 Only CeO was detected 2 Diffraction peaks of the phase. To exclude the matrix CeO 2 Of unsupported Ir synthesized by a similar method 70 Ru 30 XRD of the sample-B confirmed the formation of Ir-Ru alloy.
According to X-ray photoelectron spectroscopy (FIGS. 3a-c), preparative Ir was revealed 70 Ru 30 -B/CeO 2 Ir of the sample 0 And Ru 0 Are negatively shifted with respect to the standard sample, andb shows only the oxidation state signal; to further exclude the matrix CeO 2 For non-loaded Ir 70 Ru 30 XPS analysis of the B sample (FIG. 4), indicating an unloaded Ir 70 Ru 30 Formation of Ir-Ru-B alloy in the-B sample, which indirectly confirms Ir 70 Ru 30 -B/CeO 2 Ir-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 heating 2 The electrons of (a) are transferred to the active metal, confirming that there is a strong interaction between the metal and the matrix.
N 2 H 4 ·H 2 O catalytic decomposition hydrogen production performance test
FIG. 6 shows a sample Ir in the heated state 70 Ru 30 -B/CeO 2 Catalysis of N 2 H 4 ·H 2 Kinetic 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 -1 The catalytic activity is at the level of the peak of the catalysts reported so far.
FIGS. 7a and 7b show the heated samples Ir 70 Ru 30 -B/CeO 2 And a reference sample Ir 70 Ru 30 /CeO 2 According 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 a sample Ir in the heated state 70 Ru 30 -B/CeO 2 The 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 Ir 70 Ru 30 -B/CeO 2 The reason that the catalyst keeps good stability is realized by utilizing a temperature programming desorption-mass spectrometry (TPD-MS) technologyAnalyzing the adsorbed product on the surface of the sample and comparing with a reference sample Ir 70 Ru 30 /CeO 2 The results of the catalysts were compared. The results are shown in FIG. 9, which indicates that the above-mentioned catalyst deactivation is mainly due to the strong adsorption of the N-containing intermediate product, while the B doping is effective in reducing N 2 H 4 The adsorption strength of the decomposition intermediate or final product with the catalyst surface, resulting in Ir 70 Ru 30 -B/CeO 2 The stability of the catalyst is clearly superior to the latter.
Example 2
Ir 70 Pt 30 -B/CeO 2 Synthesis, structure and catalytic performance of catalyst
Preparing a catalyst: first, a solution A (0.07mmol H) was freshly prepared 2 IrCl 6 +0.03mol H 2 PtCl 6 +1mmol Ce(NO 3 ) 3 ·6H 2 O+10mL H 2 O) and B solution (1mmol NaBH) 4 +3mmol NaOH+10mL H 2 And 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 H 2 Heating 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 Ir 70 Pt 30 -B sample preparation: only differs from the above-mentioned preparation method in that Ce (NO) is not added 3 ) 3 ·6H 2 O, the others are the same.
Ir-B/CeO 2 Preparation of the catalyst: and Ir 70 Pt 30 -B/CeO 2 The synthesis of the catalyst is similar, differing only in 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 CeO 2 And an Ir-Pt alloy phase, wherein the alloy nanoparticles have a size of about 1 to 2 nm.
XRD analysis (fig. 11) showed that: ir 70 Pt 30 -B/CeO 2 Sample only detected CeO 2 Diffraction peaks of phase。
XPS technique (FIGS. 12a-c) gives the unloaded Ir 70 Pt 30 Results of Ir 4f, Pt 4f and B1s spectra for the B sample, indicating unsupported Ir 70 Pt 30 Ir-Pt-B alloying in the B sample.
N 2 H 4 ·H 2 Testing the performance of O catalytic decomposition hydrogen production:
FIG. 13 shows a sample Ir in a heated state 70 Pt 30 -B/CeO 2 And Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 Kinetic 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 N 2 H 4 ·H 2 The performance of the O catalytic decomposition hydrogen production has obvious influence.
Example 3
Ir 70 Rh 30 -B/CeO 2 Synthesis and catalytic performance of catalyst
Preparing a catalyst: first, solution A (0.07mmol H) was freshly prepared 2 IrCl 6 +0.03mol RhCl 3 +1mmol Ce(NO 3 ) 3 ·6H 2 O+10mL H 2 O) and B solution (1mmol NaBH) 4 +3mmol NaOH+10mL H 2 And O), then quickly pouring the solution B into the solution A, reacting for 6 hours, then 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 H 2 Heating 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/CeO 2 Preparation of the catalyst: and Ir 70 Rh 30 -B/CeO 2 The synthesis of the catalyst is similar, differing only in the noble metal precursor salt.
N 2 H 4 ·H 2 Testing the performance of O catalytic decomposition hydrogen production:
FIG. 14 shows a sample Ir in a heated state 70 Rh 30 -B/CeO 2 And Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 Kinetic 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 N 2 H 4 ·H 2 The performance of the O catalytic decomposition hydrogen production has obvious influence.
Example 4
Ir 70 Au 30 -B/CeO 2 Synthesis and catalytic performance of catalyst
Preparing a catalyst: first, a solution A (0.07mmol H) was freshly prepared 2 IrCl 6 +0.03mol Au Cl 3 +1mmol Ce(NO 3 ) 3 ·6H 2 O+10mL H 2 O) and B solution (1mmol NaBH) 4 +3mmol NaOH+10mL H 2 And 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 H 2 Heating 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/CeO 2 Preparation of the catalyst: and Ir 70 Au 30 -B/CeO 2 The synthesis of the catalyst is similar, differing only in the noble metal precursor salt.
N 2 H 4 ·H 2 Testing the performance of O catalytic decomposition hydrogen production:
FIG. 15 shows a sample Ir in a heated state 70 Au 30 -B/CeO 2 And Ir-B/CeO 2 Sample catalysis N 2 H 4 ·H 2 Kinetic performance curve of O decomposition hydrogen production. The test result shows that: the activity of the heated sample is 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 N 2 H 4 ·H 2 The 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 (5)
1. An application of a load-type noble metal boride catalyst in catalyzing hydrazine hydrate to decompose and prepare hydrogen under alkaline conditions is characterized in that,
the supported noble metal boride 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 a noble metal boride; the oxide matrix phase is CeO 2 、MnO 2 、TiO 2 Or La 2 O 3 ；
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 precipitant 4 The 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) 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;
the noble metal in the step (1) is Ir and Ru, the reaction temperature is 25-35 ℃, and the carrier metal comprises Ce, Mn, Ti or La;
the temperature of the heat treatment in the step (2) is 300-700 ℃.
2. The use of claim 1, wherein the carrier precursor salt comprises a nitrate, carbonate, acetate or halide of a carrier metal; the noble metal salt comprises a chloride, a nitrate, a sulfate or a complex of a noble metal; the precipitant comprises sodium hydroxide, sodium carbonate, tetramethylammonium hydroxide or urea.
3. The use according to claim 1, wherein the concentration of the noble metal salt in the solution A in the step (1) is 0.01-0.04M, and the concentration of the carrier precursor salt is 0.1-0.4M; the concentration of the precipitator in the solution B is 0.1-0.3M; the reaction time is 6-12 hours.
4. The use of claim 1, wherein the reducing gas of step (2) is hydrogen; the heat treatment time is 1-2 hours.
5. The use according to claim 1, wherein the active metal phase nanoparticles have a size of 1 to 2 nm; the oxide matrix phase has a strong interaction with the active metal phase.
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| CN101143319A (en) * | 2006-09-15 | 2008-03-19 | 中国科学院大连化学物理研究所 | A catalyst and its preparation and application in preparing hydrogen by borohydride hydrolysis |
| CN104888807A (en) * | 2015-04-24 | 2015-09-09 | 华南理工大学 | Regeneration method of NaBH4 hydrolysis hydrogen production catalyst |
| CN110586158A (en) * | 2019-09-09 | 2019-12-20 | 青岛科技大学 | PdB/NH2-N-rGO catalyst and preparation method and application thereof |
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| CN104888807A (en) * | 2015-04-24 | 2015-09-09 | 华南理工大学 | Regeneration method of NaBH4 hydrolysis hydrogen production catalyst |
| CN110586158A (en) * | 2019-09-09 | 2019-12-20 | 青岛科技大学 | PdB/NH2-N-rGO catalyst and preparation method and application thereof |
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