CN112675873B

CN112675873B - Nano catalyst, preparation method and application thereof

Info

Publication number: CN112675873B
Application number: CN202011542333.9A
Authority: CN
Inventors: 鄢俊敏; 张野; 康霞; 高蕊; 刘冬雪; 段焱鑫; 姚佳欣
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2022-02-08
Anticipated expiration: 2040-12-23
Also published as: CN112675873A

Abstract

The invention relates to the technical field of catalytic material preparation, and particularly discloses a nano catalyst, and a preparation method and application thereof₂、RuCl₃、IrCl₃The method adopts a one-step rapid reduction method to synthesize the titanium dioxide loaded CoRuIr nano catalyst, can be completed at room temperature, has the advantages of short synthesis time, simple and convenient operation and the like, has extremely high catalytic activity and conversion rate when the synthesized nano catalyst is used for catalyzing hydrazine borane aqueous solution to decompose and prepare hydrogen, and has the TOF value as high as 8570h^‑1The catalyst is far higher than the noble metal catalyst reported at present, and solves the problems that the prior noble metal catalyst for preparing hydrogen by hydrolyzing hydrazine borane has low catalytic activity and can not realize large-scale application; the provided preparation method is simple and has wide market prospect.

Description

Nano catalyst, preparation method and application thereof

Technical Field

The invention relates to the technical field of catalytic material preparation, in particular to a nano catalyst and a preparation method and application thereof.

Background

With the increasing energy crisis problem and environmental pollution problem caused by fossil fuel consumption, the search for renewable green energy is urgent, and hydrogen energy is undoubtedly the most potential alternative energy. However, the safety and high efficiency of hydrogen energy are still the problems to be solved urgently at present, so the research and development of a safe and efficient hydrogen storage method is the current research focus.

Due to hydrazine borane (N)₂H₄BH₃HB) has a hydrogen content of up to 15.4 wt%, is a safe and stable solid at room temperature and is stable to store in aqueous solution, and thus is considered to be a promising chemical hydrogen storage material, making it possible to provide a safe and efficient method for storing hydrogen. Complete decomposition of hydrazine borane (N)₂H₄BH₃+3H₂O→B(OH)₃+N₂H₄+3H₂) Consisting of two parts, i.e. BH₃Hydrolysis of the group and N₂H₄Selective decomposition of the components. To maximize the efficiency of hydrazine borane as a hydrogen storage material, N must be avoided₂H₄Incomplete decomposition of (3N)₂H₄→4NH₃+N₂) This is closely related to the catalyst selected. Therefore, the development of a catalyst with simple and efficient synthesis method to further improve the hydrogen evolution kinetics performance and hydrogen selectivity of the hydrazine borane is the key to whether the hydrazine borane can be used as a hydrogen storage material.

At present, most of catalysts used for preparing hydrogen by hydrolyzing hydrazine borane in the prior art are noble metal catalysts. However, the above technical solutions have the following disadvantages: most of the existing catalysts for preparing hydrogen by hydrolyzing hydrazine borane are noble metal catalysts, although partial conversion rate can reach 100%, the problem of low catalytic activity exists, and the TOF (Turnover frequency, specifically the conversion number of a single active site in unit time) value can only reach 1000h^-1And the large-scale practical application of the noble metal-based catalyst is greatly limited.

Disclosure of Invention

The embodiment of the invention aims to provide a nano catalyst to solve the problems that the existing noble metal catalyst for preparing hydrogen by hydrolyzing hydrazine borane in the background art is low in catalytic activity and cannot be applied in a large scale.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

a nano-catalyst for preparing hydrogen by hydrolyzing hydrazine borane is prepared from titanium dioxide and CoCl₂、RuCl₃、IrCl₃The raw materials are prepared by adding water to prepare aqueous solution and then carrying out reduction reaction on sodium borohydride and sodium hydroxide. The nano catalyst has an amorphous structure/low-crystallinity structure, and the amorphous structure has more unsaturated sites and dangling bonds, so that the nano catalyst has better catalytic activity.

Another object of an embodiment of the present invention is to provide a method for preparing a nano catalyst, including the following steps:

with aqueous titanium dioxide solution, CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃The aqueous solution is taken as a raw material, and sodium hydroxide (NaOH) aqueous solution and sodium borohydride (NaBH) are added₄) And carrying out reduction reaction on the aqueous solution to obtain the nano catalyst.

As a further scheme of the invention: in the preparation method of the nano-catalyst, the temperature of the reduction reaction is room temperature, and the room temperature generally refers to 15 ℃ to 25 ℃, and preferably 25 ℃.

Another object of the embodiments of the present invention is to provide a nanocatalyst prepared by the above preparation method of a nanocatalyst.

Another purpose of the embodiment of the present invention is to provide an application of the above nano catalyst in catalyzing hydrolysis of hydrazine borane to produce hydrogen.

Compared with the prior art, the invention has the beneficial effects that:

the nano catalyst provided by the embodiment of the invention is prepared by mixing titanium dioxide and CoCl₂、RuCl₃、IrCl₃The method adopts a one-step rapid reduction method to synthesize the titanium dioxide loaded CoRuIr nano catalyst, can be completed at room temperature, has the advantages of short synthesis time, simple and convenient operation and the like, has extremely high catalytic activity and conversion rate when the synthesized nano catalyst is used for catalyzing hydrazine borane aqueous solution to decompose and prepare hydrogen, and has the TOF value as high as 8570h^-1The catalyst is far higher than the noble metal catalyst reported at present, and solves the problems that the prior noble metal catalyst for preparing hydrogen by hydrolyzing hydrazine borane has low catalytic activity and can not realize large-scale application; to provideThe preparation method is simple, and the prepared nano catalyst has an amorphous structure/low-crystallinity structure, and the amorphous structure has more unsaturated sites and dangling bonds, so that the catalyst has better catalytic activity and wide market prospect.

Drawings

Fig. 1 is a schematic flow chart of the preparation process of the titanium dioxide supported CoRuIr nanocatalyst provided by the invention.

FIG. 2 shows X-ray diffraction patterns of catalysts prepared in inventive example 1, comparative example 1 and comparative example 2.

FIG. 3 is an X-ray diffraction pattern of the catalyst prepared in example 1 of the present invention.

FIG. 4 is a transmission electron microscope image of the catalyst prepared in example 1 of the present invention.

FIG. 5 is a time-course graph of hydrazine borane decomposition catalyzed by catalysts prepared in example 1, comparative example 1 and comparative example 2 of the present invention at 323K.

FIG. 6 is a graph showing the cycle performance of the catalyst prepared in example 1 of the present invention for decomposition of hydrazine borane at 323K.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

The embodiment of the invention provides a nano catalyst, in particular to titanium dioxide (TiO)₂) The supported CoRuIr nano catalyst can be used for efficiently producing hydrogen by hydrazine borane hydrolysis, and is prepared from titanium dioxide and CoCl₂、RuCl₃、IrCl₃The raw materials are prepared by adding water to prepare aqueous solution and then carrying out reduction reaction on sodium borohydride and sodium hydroxide. The nano catalyst has an amorphous structure/low-crystallinity structure, and the amorphous structure has more unsaturated sites and dangling bonds, so that the nano catalyst has better catalytic activity.

In the embodiment of the invention, titanium dioxide and CoCl are added₂、RuCl₃、IrCl₃The method adopts a one-step rapid reduction method to synthesize the titanium dioxide loaded CoRuIr nano catalyst as a raw material, can be finished at room temperature, has the advantages of short synthesis time, simple and convenient operation and the like, and obviously improves the content of CoRuIr nano particles (NPs, Nanoparticles) in TiO₂Dispersibility on a nano sheet (Nanosheets) substrate and particle size reduction of CoRuIr nanoparticles; the synthesized nano catalyst is used for catalyzing hydrazine borane aqueous solution 323K to decompose and prepare hydrogen, has extremely high catalytic activity, 100 percent conversion rate, 100 percent hydrogen selectivity, better circulation stability and extremely high catalytic activity under the condition of no existence of any additive, can realize the complete decomposition of the hydrazine borane within 25 seconds, and has the TOF value as high as 8570h^-1Far higher than the noble metal catalyst reported at present, for example, NiCuMo (conversion rate 100%, TOF 108 h) reported at present^-1)，Ni@Rh₄Ni/Al₂O₃(conversion 95.7%, TOF 71.7 h)^-1) NiPt/rGO (conversion 100%, TOF 240 h)^-1)，Rh-MoO_x(conversion rate 100%, TOF 750h^-1)，NiIr/La₂O₂CO₃(conversion rate 100%, TOF 1250h^-1) NiPt/MIL-101/rGO (conversion 100%, TOF 960 h)^-1) And the like.

As another preferred embodiment of the present invention, the nano-catalyst is of an amorphous structure and/or a low crystallinity structure and is made of CoCl₂、RuCl₃、IrCl₃The converted CoRuIr nanoparticles are uniformly dispersed on the titanium dioxide carrier, and the size of the CoRuIr nanoparticles is about 1.0-3.8 nm.

Preferably, TiO₂As a support, the average size of the CoRuIr nanoparticles was 2.0 nm.

The embodiment of the invention also provides a preparation method of the nano catalyst, which comprises the following steps: with aqueous titanium dioxide solution, CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃Dissolving in waterThe solution is taken as a raw material, and sodium hydroxide (NaOH) aqueous solution and sodium borohydride (NaBH) are added₄) And carrying out reduction reaction on the aqueous solution to obtain the nano catalyst.

As another preferred embodiment of the present invention, the preparation method of the nano-catalyst comprises the steps of:

mixing titanium dioxide and CoCl₂、RuCl₃、IrCl₃Respectively adding water to prepare aqueous solution of titanium dioxide and CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃An aqueous solution;

adding CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃Adding the aqueous solution into a titanium dioxide aqueous solution, and uniformly mixing to obtain a mixed solution;

and respectively adding water into sodium hydroxide and sodium borohydride to prepare a sodium hydroxide aqueous solution and a sodium borohydride aqueous solution, mixing the sodium hydroxide aqueous solution and the sodium borohydride aqueous solution, adding the mixture into the mixed solution, and stirring to perform a reduction reaction to obtain the nano catalyst.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) to (B) is 5-7:1-3: 1-3.

Preferably, CoCl₂、RuCl₃、IrCl₃Is 6:2: 2.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.05-0.1 mmol: 0.125-0.75 mmol.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, the concentration of the titanium dioxide aqueous solution is 1-3mg/mL, and the dosage is 10-20mL, preferably, the concentration is 2mg/mL, and the dosage is 15 mL.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, the titanium dioxide aqueous solution is a titanium dioxide aqueous solution which is uniformly dispersed after being subjected to ultrasonic treatment for 15-120 min.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, the CoCl is₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃The concentrations of the aqueous solutions are 0.05-0.5mol/L respectively, and the dosage is 0.01-5 mL.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, the sodium hydroxide and the sodium borohydride are respectively added with water to prepare a sodium hydroxide aqueous solution and a sodium borohydride aqueous solution, specifically, 200-800mg of NaOH and 20-60mg of sodium borohydride are dissolved together in 1mL of water.

As another preferred embodiment of the present invention, in the preparation method of the nano-catalyst, the concentration of the sodium hydroxide aqueous solution is 0.05-0.5 mol/L.

As another preferred embodiment of the present invention, the temperature during the reduction reaction is room temperature, which is generally 15 ℃ to 25 ℃, preferably 25 ℃.

As another preferred embodiment of the present invention, the time of the reduction reaction is 5 to 15 min.

As another preferred embodiment of the present invention, the preparation method of the nano-catalyst comprises the following steps:

step one, preparing a titanium dioxide aqueous solution with the concentration of 1-3mg/mL, and obtaining a uniformly dispersed titanium dioxide aqueous solution after ultrasonic treatment;

step two, 0.01-5mL of CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃Adding the aqueous solution into the titanium dioxide aqueous solution obtained in the first step, and continuously stirring for 1-10min to obtain a mixed solution;

and step three, adding 0.01-5mL of mixed aqueous solution of NaOH and 20-60mg of sodium borohydride into the mixed solution obtained in the step two, and stirring for 5-15min to perform reduction reaction, thereby obtaining the titanium dioxide loaded CoRuIr nano catalyst.

The embodiment of the invention also provides the nano catalyst prepared by the preparation method of the nano catalyst.

The embodiment of the invention also provides application of the nano catalyst in catalyzing hydrolysis of hydrazine borane to prepare hydrogen.

As another preferred embodiment of the present invention, in the application of the nano-catalyst in catalyzing the hydrolysis of hydrazine borane to produce hydrogen, after dispersing in water and adjusting the pH to be alkaline, the nano-catalyst is added with hydrazine borane aqueous solution and hydrolysis hydrogen production reaction is performed in a temperature range of less than 353K, and the produced hydrogen is measured by a gas burette.

As another preferred embodiment of the present invention, the molar ratio of the nano catalyst to hydrazine borane is 0.001-0.5: 1.

as another preferred embodiment of the present invention, the pH adjustment to alkalinity is performed by using a pH adjuster, and existing products such as sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium citrate, potassium citrate, calcium sulfate, calcium lactate, calcium hydroxide, potassium hydroxide, etc. may be selected according to the needs, and the pH is not limited herein as long as the pH can be adjusted to alkalinity by adding a certain amount. Preferably, NaOH is added to adjust the pH to be alkaline, the concentration of the NaOH is 1-4mol/L, and the concentration of the hydrazine borane aqueous solution is 0.5-2 mol/L.

As another preferred embodiment of the present invention, the water may be any one selected from purified water, mineral water, distilled water, deionized water, and soft water, which is not limited herein and may be selected as needed. Deionized water is preferred.

The technical effect of the nanocatalyst of the present invention will be further described below by referring to specific examples.

Example 1

A nano catalyst, in particular to a titanium dioxide loaded CoRuIr nano catalyst, the preparation method of which is shown in figure 1, and the method specifically comprises the following steps:

step one, preparing 15mL of titanium dioxide aqueous solution with the concentration of 2mg/mL, specifically adding a proper amount of titanium dioxide into water, and performing ultrasonic treatment for 60min to obtain uniformly dispersed titanium dioxide aqueous solution;

step two, adding CoCl with the total amount of 0.1mmol₂、RuCl₃、IrCl₃(CoCl₂：RuCl₃：IrCl₃In a molar ratio of 6:2: 2) adding the titanium dioxide aqueous solution into the titanium dioxide aqueous solution obtained in the step one in the form of an aqueous solution, and continuously stirring for 10min to obtain a mixed solution;

and step three, dissolving 412mg of NaOH and 30mg of sodium borohydride together in 1mL of distilled water, then adding the solution into the mixed solution obtained in the step two, and stirring the solution at 25 ℃ for 15min to carry out reduction reaction, thereby obtaining the titanium dioxide loaded CoRuIr nano catalyst.

Example 2

A nanometer catalyst, in particular to a titanium dioxide loaded CoRuIr nanometer catalyst, the preparation method comprises the following steps:

step one, preparing 15mL of titanium dioxide aqueous solution with the concentration of 2mg/mL, specifically adding a proper amount of titanium dioxide into water, and performing ultrasonic treatment for 30min to obtain uniformly dispersed titanium dioxide aqueous solution;

step two, adding CoCl with the total amount of 0.05mmol₂、RuCl₃、IrCl₃(CoCl₂：RuCl₃：IrCl₃In a molar ratio of 6:2: 2) adding the titanium dioxide aqueous solution into the titanium dioxide aqueous solution obtained in the step one in the form of an aqueous solution, and continuously stirring for 10min to obtain a mixed solution;

and step three, dissolving 412mg of NaOH and 20mg of sodium borohydride in 1mL of distilled water, adding the solution into the mixed solution obtained in the step two, and stirring the solution at 25 ℃ for 15min to perform reduction reaction, thereby obtaining the titanium dioxide supported CoRuIr nano catalyst.

Example 3

step two, adding CoCl with the total amount of 0.05mmol₂、RuCl₃、IrCl₃(CoCl₂：RuCl₃：IrCl₃In a molar ratio of4: 3: 3) adding the titanium dioxide aqueous solution into the titanium dioxide aqueous solution obtained in the step one in the form of an aqueous solution, and continuously stirring for 10min to obtain a mixed solution;

and step three, dissolving 412mg of NaOH and 60mg of sodium borohydride in 1mL of distilled water, adding the solution into the mixed solution obtained in the step two, and stirring the solution at 25 ℃ for 15min to perform reduction reaction, thereby obtaining the titanium dioxide supported CoRuIr nano catalyst.

Example 4

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) was not less than 5:1:1, but the same as in example 1.

Example 5

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) to (B) was 5:3:3, and the same as in example 1.

Example 6

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) was not less than 7:1:1, but the same as in example 1.

Example 7

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) was not less than 7:3:3, but the same as in example 1.

Example 8

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) is 5-7:1-3:1-3, and the other steps are the same as in example 1.

Example 9

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) was not less than 7:2:1, but the same as in example 1.

Example 10

Compared with example 1, except that CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) to (B) was not less than 7:2:2, but the same as in example 1.

Example 11

Compared with example 1, except that CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.05 mmol: the same procedure as in example 1 was repeated except that the amount of the residue was 0.125 mmol.

Example 12

Compared with example 1, except that CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.1 mmol: the same procedure as in example 1 was repeated except that the amount of the residue was 0.75 mmol.

Example 13

Compared with example 1, except that CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.05 mmol: the same procedure as in example 1 was repeated except that the amount of the residue was 0.75 mmol.

Example 14

Compared with example 1, except that CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.1 mmol: the same procedure as in example 1 was repeated except that the amount of the residue was 0.125 mmol.

Example 15

The procedure of example 1 was repeated, except that the concentration of the aqueous titanium dioxide solution was 1mg/mL and the amount was 20mL, as compared with example 1.

Example 16

The procedure of example 1 was repeated, except that the concentration of the aqueous titanium dioxide solution was 3mg/mL and the amount was 10mL, as compared with example 1.

Example 17

The same procedure as in example 1 was repeated, except that the sonication time was 15 min.

Example 18

The same procedure as in example 1 was repeated, except that the sonication time was 120 min.

Example 19

The procedure was carried out in the same manner as in example 1 except that the temperature during the reduction reaction was 15 ℃ and the time for the reduction reaction was 15min, as compared with example 1.

Example 20

The procedure was repeated as in example 1 except that the temperature during the reduction reaction was 20 ℃ and the time during the reduction reaction was 5min, as compared with example 1.

Example 21

Example 22

Dispersing the titanium dioxide supported CoRuIr nano catalyst prepared in the example 1 into water, adding NaOH solution with the concentration of 2.5mol/L to adjust the pH of the solution to be alkaline, adding hydrazine borane aqueous solution with the concentration of 1.25mol/L, and adjusting the reaction temperature to be 323K, wherein the molar ratio of the titanium dioxide supported CoRuIr nano catalyst to the hydrazine borane is 0.25: 1, and measuring the generated hydrogen gas by a gas burette.

Example 23

Compared to example 22, except that the molar ratio of the titania supported CoRuIr nanocatalyst to hydrazine borane was 0.001: the procedure was repeated in the same manner as in example 22 except for 1.

Example 24

Compared to example 22, except that the molar ratio of titania supported CoRuIr nanocatalyst to hydrazine borane was 0.5: the procedure was repeated in the same manner as in example 22 except for 1.

Example 25

The reaction was carried out at 353K as compared with example 22, except that the reaction temperature was the same as in example 22.

Example 26

The reaction was carried out at 313K as in example 22, except that the reaction temperature was changed to 313K.

Comparative example 1

The total amount of CoCl was 0.1mmol₂、RuCl₃、IrCl₃(CoCl₂：RuCl₃：IrCl₃In a molar ratio of 6:2: 2) dissolving in 5mL of aqueous solution, and uniformly stirring to obtain a mixed solution; dissolving 412mg of NaOH and 60mg of sodium borohydride in 1mL of distilled water, adding the solution into the mixed solution at 25 ℃, uniformly stirring by magnetic force, and stirring until complete reduction, thus obtaining the CoRuIr catalyst.

Comparative example 2

The total amount of CoCl was 0.1mmol₂、RuCl₃、IrCl₃(CoCl₂：RuCl₃：IrCl₃In a molar ratio of 6:2: 2) dissolving in 20mg titanium dioxide aqueous solution (2mg/mL), and stirring to obtain mixed solution; 30mg of NaBH₄Dissolving the solution in 1mL of distilled water, adding the solution into the mixed solution at 25 ℃, uniformly stirring by magnetic force, and stirring until complete reduction, thus obtaining the titanium dioxide supported CoRuIr catalyst.

Performance testing

Firstly, the titanium dioxide supported CoRuIr nano catalyst prepared in the example 1, the CoRuIr catalyst prepared in the comparative example 1 and the titanium dioxide supported CoRuIr catalyst prepared in the comparative example 2 are respectively dried in vacuum and then are subjected to X-ray powder diffraction (XRD) characterization, the specific result refers to figure 2, and the X-ray powder diffraction (XRD) result shows that the titanium dioxide supported CoRuIr nano catalyst prepared in the example 1 has an amorphous/low-crystalline structure; the CoRuIr catalyst sample prepared in comparative example 1 also had an amorphous/low crystalline structure.

Secondly, the titanium dioxide supported CoRuIr nano catalyst prepared in the embodiment 1 is dried in vacuum, and then is subjected to X Photoelectron Spectroscopy (XPS) characterization, wherein the specific result refers to FIG. 3, and the X Photoelectron Spectroscopy (XPS) result shows that the titanium dioxide supported CoRuIr nano catalyst is successfully synthesized in the embodiment, and Co, Ru and Ir all have a metal state; in FIG. 3, the graph from left to right is the X photoelectron spectrum of Co, Ru and Ir.

Thirdly, the titanium dioxide supported CoRuIr nano catalyst prepared in example 1 is diluted, dropped on a carbon supporting film, dried and then subjected to Transmission Electron Microscope (TEM) characterization, and specific results refer to FIG. 4, and according to Transmission Electron Microscope (TEM) results in FIG. 4, the titanium dioxide supported CoRuIr nano catalyst prepared in example 1 has a small particle size (2.0 nm) and uniform dispersibility.

Application of titanium dioxide loaded CoRuIr nano catalyst for catalyzing hydrazine borane aqueous solution at working temperature of fuel cell<Hydrolysis hydrogen production reaction in a range of 353K, comprising the following specific steps: will be provided withThe titanium dioxide supported CoRuIr nanocatalyst prepared in the example 1, the CoRuIr catalyst in the comparative example 1 and the titanium dioxide supported CoRuIr catalyst in the comparative example 2 are respectively hydrolyzed to prepare hydrogen, specifically, the hydrogen is respectively dispersed in water, NaOH solution with the concentration of 1-4mol/L (10 mmol of NaOH in total) is added to adjust the pH of the solution to be alkaline, 2mL of hydrazine borane aqueous solution with the concentration of 0.5mol/L is added, the reaction temperature is adjusted to be 323K, and the generated hydrogen is measured through a gas burette. The hydrogen production amount (n) of the hydrogen production process by using the titanium dioxide supported CoRuIr nanocatalyst of the embodiment 1 to catalyze hydrazine borane aqueous solution_gas/n_HB) The graph with time (minutes) is shown in fig. 5, the hydrogen produced by the catalytic hydrolysis of hydrazine borane at the temperature of 323K can generate 6 equivalent of gas within 25 seconds, and the conversion rate reaches 100%. Hydrogen production amount (n) of hydrazine borane hydrogen production process catalyzed by CoRuIr catalyst in comparative example 1_gas/n_HB) The graph with time (min) is shown in fig. 5, the catalytic hydrolysis of hydrazine borane at room temperature to produce hydrogen can achieve 92% conversion in 10 min. Hydrogen production amount (n) of hydrazine borane hydrogen production process catalyzed by titanium dioxide supported CoRuIr catalyst in comparative example 2_gas/n_HB) The graph with time (minutes) is shown in fig. 5, and the hydrogen production by catalyzing the room-temperature hydrolysis of the hydrazine borane can realize the complete decomposition of the hydrazine borane within 55 seconds.

Fifthly, after the first round of decomposition reaction of the hydrazine borane catalyzed by the titanium dioxide supported CoRuIr nano catalyst is finished, adding an equivalent amount of hydrazine borane (0.5mol/L, 2mL) solution into the double-mouth flask through a constant pressure dropping funnel, and carrying out the same operation as the previous reaction. The same operation steps are repeated for four times at the water bath temperature of 323K, and the obtained cycle performance curve graph is shown in FIG. 6, the prepared titanium dioxide supported CoRuIr nano catalyst has good cycle stability for catalyzing the hydrazine borane dehydrogenation reaction, and after 5 circles of reaction, although the reaction time is slightly increased, the conversion rate is still 100%. Therefore, the titanium dioxide loaded CoRuIr nano catalyst still has extremely high catalytic activity, 100 percent conversion rate, 100 percent hydrogen selectivity, better cycle stability and extremely high catalytic activity under the condition of no additive, can realize the complete decomposition of hydrazine borane within 25 seconds, and the TOF value of the catalyst is as high as 8570h^-1。

It should be noted that, in the preparation method and application of the titanium dioxide supported CoRuIr nanocatalyst provided by the above embodiments of the present invention, an aqueous solution of titanium dioxide is prepared, and an aqueous solution of titanium dioxide which is uniformly dispersed is obtained after ultrasonic treatment; adding CoCl₂Aqueous solution, RuCl₃Aqueous solution, IrCl₃Adding the aqueous solution into the titanium dioxide aqueous solution, and continuously stirring to obtain a mixed solution; and adding the mixed aqueous solution of NaOH and 20-60mg of sodium borohydride into the mixed solution, and continuously stirring for 5-15min to perform reduction reaction, thereby obtaining the titanium dioxide supported CoRuIr nano catalyst. The invention adopts a one-step rapid reduction method to synthesize the titanium dioxide loaded CoRuIr nano catalyst, can be completed at room temperature, and has the advantages of short synthesis time, simple and convenient operation and the like; the synthesized nano catalyst is used for catalyzing hydrazine borane aqueous solution 323K to decompose and prepare hydrogen, and the catalyst still has 100% conversion rate, 100% hydrogen selectivity, better circulation stability and extremely high catalytic activity under the condition of no existence of any additive.

On the other hand, the existing noble metal catalyst for preparing hydrogen by hydrolyzing hydrazine borane has the problems of low catalytic activity and incapability of realizing large-scale application, and the preparation method is too complicated₂The dispersity on the nanosheet substrate and the particle size of the CoRuIr nanoparticles are reduced.

In general, the nano-catalyst synthesized by the invention has an amorphous/low-crystallinity structure, and the amorphous structure has more unsaturated sites and dangling bonds, so that the nano-catalyst has better catalytic activity. TiO 2₂The metal nanoparticles having an average size of 2.0nm and good dispersibility as a carrier are one of the reasons why the catalyst has high activity. And liftThe preparation method can be used as a simple synthesis method to synthesize the amorphous/low-crystallinity titanium dioxide supported CoRuIr nano catalyst, and the synthesized catalyst is applied to the hydrogen production reaction of hydrazine borane decomposition at the temperature of 323K, has good catalytic activity, and can further promote the application of hydrazine borane as a hydrogen storage material in actual life.

While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims

1. The preparation method of the nano catalyst is characterized in that the nano catalyst is titanium dioxide and CoCl₂、RuCl₃、IrCl₃The catalyst is prepared by adding water into raw materials to prepare an aqueous solution, and then performing reduction reaction on sodium borohydride and sodium hydroxide, wherein the morphology of the nano catalyst is that CoRuIr nano particles are uniformly dispersed on titanium dioxide, the size of the CoRuIr nano particles is 1.0-3.8nm, and the CoRuIr nano particles are prepared by CoCl₂、RuCl₃、IrCl₃The preparation method comprises the following steps:

and adding water into sodium hydroxide and sodium borohydride for mixing, adding the mixture into the mixed solution, and stirring the mixture for reduction reaction to obtain the nano catalyst.

2. The method of claim 1, wherein the method of preparing the nanocatalyst comprises CoCl₂、RuCl₃、IrCl₃The molar ratio of (A) to (B) is 5-7:1-3: 1-3.

3. The method of claim 1, wherein the method of preparing the nanocatalyst comprises CoCl₂、RuCl₃And IrCl₃The ratio of the total molar amount of (a) to the molar amount of titanium dioxide is 0.05-0.1 mmol: 0.125-0.75 mmol.

4. The method of preparing a nanocatalyst as set forth in claim 1, wherein the temperature of the reduction reaction is 15 ℃ to 25 ℃.

5. A nanocatalyst prepared by the method of claim 1.

6. The application of the nano-catalyst of claim 5 in catalyzing hydrolysis of hydrazine borane to produce hydrogen.

7. The application of the nano-catalyst in catalyzing the hydrolysis of hydrazine borane to produce hydrogen according to claim 6 is characterized in that the nano-catalyst is dispersed in water, the pH is adjusted to be alkaline, then hydrazine borane aqueous solution is added, and the hydrolysis hydrogen production reaction is carried out within the temperature range of less than 353K.

8. The application of the nano-catalyst in catalyzing the hydrolysis of hydrazine borane to prepare hydrogen according to claim 6, wherein the molar ratio of the nano-catalyst to the hydrazine borane is 0.001-0.5: 1.