阅读说明：本技术 甲酸水解制氢用高效纳米催化剂及其制备方法 (Efficient nano catalyst for hydrogen production by formic acid hydrolysis and preparation method thereof ) 是由 鄢俊敏 刘冬雪 康霞 张野 段焱鑫 姚佳欣 李弘睿 高蕊 俞珍 王达年 蒋青 于 2019-09-05 设计创作，主要内容包括：本发明涉及催化剂制备技术领域,具体地涉及一种甲酸水解制氢用高效纳米催化剂,该催化剂为通过在经过-NH<Sub>2</Sub>-N双官能团修饰的石墨烯载体NH<Sub>2</Sub>-N-rGO上掺杂金钯铱纳米粒子得到AuPdIr/NH<Sub>2</Sub>-N-rGO高效催化剂。通过一步快速还原法在室温下制得,合成时间短,操作简便,在没有任何添加剂存在的条件下仍然具有极高的催化活性,100％的甲酸转化率,100％的氢气选择性及较好的循环稳定性,且在0.75min内可以实现甲酸的完全分解。AuPdIr/NH<Sub>2</Sub>-N-rGO的初始TOF值为10224.9h<Sup>-1</Sup>,远高于目前已经报道的AuPd/NH<Sub>2</Sub>-N-rGO的TOF值为4639.2h<Sup>-1</Sup>。(The invention relates to the technical field of catalyst preparation, in particular to a high-efficiency nano catalyst for hydrogen production by formic acid hydrolysis, which is prepared by passing through-NH 2 -N bifunctional group modified graphene carrier NH 2 AuPdIr/NH obtained by doping gold-palladium-iridium nano particles on-N-rGO 2 -N-rGO high efficiency catalyst. By one-step rapid reductionThe method is prepared at room temperature, has short synthesis time and simple and convenient operation, still has extremely high catalytic activity, 100 percent formic acid conversion rate, 100 percent hydrogen selectivity and better circulation stability under the condition of no additive, and can realize the complete decomposition of the formic acid within 0.75 min. AuPdIr/NH 2 initial TOF value of-N-rGO 10224.9h ‑1 Is far higher than the AuPd/NH reported at present 2 TOF value of-N-rGO 4639.2h ‑1 。)

1. The high-efficiency catalyst for preparing hydrogen by hydrolyzing formic acid is characterized in that the high-efficiency catalyst is prepared by passing-NH₂-N bifunctional group modified graphene carrier NH₂AuPdIr/NH obtained by doping gold-palladium-iridium nano particles on-N-rGO₂-N-rGO high efficiency catalyst.

2. the preparation method of the high-efficiency catalyst for hydrogen production by formic acid hydrolysis, which is characterized by comprising the following steps:

(1) preparing graphene oxide GO in advance by adopting a Hummer's method, adding the prepared GO into a certain amount of water, and preparing a GO aqueous solution with the concentration of 1-5 mg/mL; carrying out ultrasonic treatment for 15-30 min to obtain a uniformly dispersed GO aqueous solution;

(2) Adding a proper amount of 3-aminopropyl-3-ethoxysilane APTS into the GO aqueous solution obtained in the step (1), continuing ultrasonic treatment for 5-15 min, and uniformly stirring to obtain a mixed solution A;

(3) PdCl with a molar ratio of 1:2₂Dissolving NaCl and NaCl in certain amount of distilled water, and stirring to obtain brown yellow Na₂PdCl₄An aqueous solution;

(4) the prepared Na₂PdCl₄Aqueous solution, HAuCl₄Aqueous solution and IrCl₃·xH₂Adding a proper amount of O aqueous solution into the mixed solution A in the step (2), and continuously stirring to obtain a mixed solution B;

(5) 30-100 mg of sodium borohydride NaBH₄Adding the reducing agent into the mixed solution B obtained in the step (4), and stirring and reducing to obtain a mixed solution C;

(6) At room temperature, stirring and reducing the mixed solution C in the step (5) in the air, centrifuging at 8000-10000 rpm for 3-5 min after bubbles completely disappear, and washing with water for 3-5 times to obtain the AuPdIr/NH₂-N-rGO high efficiency catalyst.

3. The method according to claim 2, wherein in the step (4), Na is added₂PdCl₄Aqueous solution, HAuCl₄Aqueous solution and IrCl₃·xH₂The concentration of the O aqueous solution was 0.02M.

4. the method according to claim 2, wherein in the step (4), the molar ratio of Pd (Au + Ir) is 1:1, wherein Au: the Ir molar ratio is 1-5: 1.

5. the method according to claim 4, wherein the optimal molar ratio of Au to Pd to Ir is 7:10: 3.

6. The preparation method according to claim 2, wherein the stirring reduction in the step (5) is performed at room temperature for 10-20 min.

7. The method according to claim 2, wherein the AuPdIr/NH used in step (6) is₂the-N-rGO high-efficiency catalyst is characterized in that AuPdIR nano particles are uniformly distributed in a-NH passing process₂-N bifunctional group modified graphene carrier NH₂-N-rGO.

8. The use of the high-efficiency catalyst for hydrogen production by formic acid hydrolysis according to claim 1,The method is characterized in that the concentration of a formic acid aqueous solution is 0.5-5M, and the AuPdIr/NH₂The mol ratio of the-N-rGO high-efficiency catalyst to the formic acid is 0.01-0.5.

9. the use according to claim 8, wherein said AuPdIr/NH is administered₂the-N-rGO high-efficiency catalyst is used for hydrogen production reaction by the decomposition of aqueous solution of formic acid at room temperature; when AuPdIr/NH₂when the actual dosage of the-N-rGO high-efficiency catalyst is 0.06mmol, 245mL of gas is generated within 0.75min, the gas is a 1:1 mixed gas of hydrogen and carbon dioxide generated by the formic acid dehydrogenation reaction, the formic acid conversion rate is 100%, and the hydrogen selectivity is 100%.

Technical Field

The invention relates to the technical field of catalyst preparation, in particular to a high-efficiency nano catalyst for hydrogen production by formic acid hydrolysis and a preparation method thereof.

Background

hydrogen is considered to be a very potential energy carrier for transportation/mobile applications, playing an important role in the sustainable development of future renewable energy technologies. However, the very low critical point and the very low density of hydrogen make the efficient storage of hydrogen difficult to break through, which causes great inconvenience to the application of hydrogen-based fuel cells, so that the search for alternative materials is the focus of current research. Chemical hydrogen storage materials are currently gaining wide attention due to various advantageous properties at room temperature, such as formic acid. Formic acid (HC00H, FA) is the main product of biological process, is nontoxic, has extremely high stability at room temperature, has 4.4% of hydrogen content, and has various advantages, so that the formic acid can be used as a safe and convenient hydrogen carrier in a portable fuel cell. Formic acid can decompose along the hydrolysis pathway to produce hydrogen and carbon dioxide under the action of a suitable catalyst, but formic acid can also decompose along an undesirable dehydration pathway to produce carbon monoxide. It is well known that carbon monoxide poisons catalysts in fuel cells, resulting in a reduction or even loss of activity. Therefore, the formic acid decomposition reaction should be used to suppress the generation of carbon monoxide, for example, the components of the catalyst, the pH of the solution, and the reaction temperature should be adjusted. Recently, the development of selective decomposition of formic acid has been advanced, and particularly, the development of a catalyst has been studied more. For example, the metal complex heterogeneous catalyst has been applied to the hydrolysis reaction of formic acid under ambient conditions and shows a higher activity. Heterogeneous catalysts are widely used due to their advantages of easy control, convenient extraction, easy recovery, etc. Therefore, the search for heterogeneous catalysts with high activity and high selectivity in the hydrolysis of formic acid at room temperature is the focus of the research. The fine-sized metal particles have a unique catalytic activity compared to the bulk material because the small particles have a large specific surface area and a large number of active atoms at the edges and corners, and thus the fine-sized metal particles have raised a huge research heat surge in the field of catalysts. However, smaller particle sizes tend to agglomerate, especially at the nanometer level, due to surface energy considerations. The agglomeration has a great influence on the activity of the catalyst, and the activity cannot be fully expressed to show low activity. To avoid this problem, a variety of support materials are applied to the preparation of metal nanoparticle catalysts as substrates, promoting uniform distribution of small particles on their surface, thereby avoiding agglomeration. The graphene single-layer carbon material has great research attention due to the advantages of high conductivity, huge specific surface area, unique graphitized substrate structure, low preparation cost and the like. Due to these advantages of graphene, various nanomaterials based thereon have been applied to various fields such as sensors, electronics, electrochemical energy storage, high-efficiency catalysts, and the like. In the research in the field of catalysts, the interaction between graphene and metal nanoparticles plays an important role in improving the activity of the catalyst. Thus, graphene is a very promising substrate for many applications.

The subject group submits an invention patent application with the application number of 201810620905.2 to the national patent office in 2018 in the 6 th month, the invention name is a functionalized graphene supported gold-palladium nano catalyst and a preparation method and application thereof, and a simple and effective method is expected to be found for synthesizing a high-efficiency and good-dispersibility metal alloy nano catalyst to improve the efficiency of the formic acid dehydrogenation reaction, however, the catalyst prepared by the method still has an increased space for evaluation on the catalytic efficiency.

Disclosure of Invention

The invention provides a high-efficiency nano catalyst for hydrogen production by formic acid hydrolysis and a preparation method thereof, aiming at improving the catalytic efficiency of the catalyst, and can completely solve the technical problems.

The technical scheme for solving the technical problems is as follows:

The invention designs a high-efficiency catalyst for hydrogen production by formic acid hydrolysis, namely, the high-efficiency catalyst is prepared by passing through-NH₂-N bifunctional group modified graphene carrier NH₂AuPdIr/NH obtained by doping gold-palladium-iridium nano particles on-N-rGO₂-N-rGO high efficiency catalyst.

The preparation method of the high-efficiency catalyst for hydrogen production by formic acid hydrolysis comprises the following steps:

(1) preparing graphene oxide GO in advance by adopting a Hummer's method, adding the prepared GO into a certain amount of water, and preparing a GO aqueous solution with the concentration of 1-5 mg/mL; carrying out ultrasonic treatment for 15-30 min to obtain a uniformly dispersed GO aqueous solution;

(2) Adding a proper amount of 3-aminopropyl-3-ethoxysilane APTS into the GO aqueous solution obtained in the step (1), continuing ultrasonic treatment for 5-15 min, and uniformly stirring to obtain a mixed solution A;

(3) PdCl with a molar ratio of 1:2₂Dissolving NaCl and NaCl in certain amount of distilled water, and stirring to obtain brown yellow Na₂PdCl₄An aqueous solution;

(4) The prepared Na₂PdCl₄Aqueous solution, HAuCl₄Aqueous solution and IrCl₃·xH₂O water solution, taking a proper amount to be added into the step (2)continuously stirring the mixed solution A to obtain a mixed solution B; said Na₂PdCl₄Aqueous solution, HAuCl₄Aqueous solution and IrCl₃·xH₂The concentration of the O aqueous solution is 0.02M;

the molar ratio of Pd (Au + Ir) is 1:1, wherein Au: the Ir molar ratio is 1-5: 1. the optimal molar ratio of Au to Pd to Ir is 7:10: 3.

(5) 30-100 mg of sodium borohydride NaBH₄adding the reducing agent into the mixed solution B obtained in the step (4), and stirring and reducing to obtain a mixed solution C; the stirring reduction is carried out at room temperature, and the reduction time is 10-20 min.

(6) At room temperature, stirring and reducing the mixed solution C in the step (5) in the air, centrifuging at 8000-10000 rpm for 3-5 min after bubbles completely disappear, and washing with water for 3-5 times to obtain the AuPdIr/NH₂-N-rGO high efficiency catalyst; the AuPdIr/NH₂the-N-rGO high-efficiency catalyst is characterized in that AuPdIR nano particles are uniformly distributed in a-NH passing process₂-N bifunctional group modified graphene carrier NH₂-N-rGO.

the application of the high-efficiency catalyst for hydrogen production by formic acid hydrolysis has the concentration of 0.5-5M of formic acid aqueous solution, and the AuPdIr/NH₂The mol ratio of the-N-rGO high-efficiency catalyst to the formic acid is 0.01-0.5.

Further, the AuPdIr/NH₂the-N-rGO high-efficiency catalyst is used for hydrogen production reaction by the decomposition of aqueous solution of formic acid at room temperature; when AuPdIr/NH₂When the actual dosage of the-N-rGO high-efficiency catalyst is 0.06mmol, 245mL of gas is generated within 0.75min, the gas is a 1:1 mixed gas of hydrogen and carbon dioxide generated by the formic acid dehydrogenation reaction, the formic acid conversion rate is 100%, and the hydrogen selectivity is 100%.

The invention has the beneficial effects that:

The invention synthesizes AuPdIr/NH by a one-step rapid reduction method₂the-N-rGO high-efficiency catalyst can be prepared at room temperature, has short synthesis time and simple and convenient operation, and can obviously improve the NH content of AuPdIr nanoparticles₂-dispersibility on N-rGO substrates, and reduction of particle size of metals; combining the AuPdIr-NH₂the-N-rGO high-efficiency catalyst is used for catalyzing the formic acid aqueous solution to decompose and produce hydrogen at room temperature, has extremely high catalytic activity, 100 percent of formic acid conversion rate, 100 percent of hydrogen selectivity and better circulation stability under the condition of no additive, and can realize the complete decomposition of formic acid within 0.75 min. AuPdIr/NH₂initial TOF value of-N-rGO 10224.9h^-1Is far higher than the AuPd/NH reported at present₂N-rGO (conversion 100%, TOF 4639.2 h)^-1)、PdAu-MnO_x/N-SiO₂(conversion 92%, TOF 785h^-1) Ag @ Pd (conversion 41%, TOF 13.1 h)^-1) And the like. AuPdIr/NH₂the performance of-N-rGO catalysts can even be compared to the performance of many homogeneous catalysts at higher reaction temperatures, e.g. RuBr₃PPh (45% conversion, TOF 3630 h)^-1)，Ru(H)₂(meso-P4) (98% conversion, TOF 870h^-1)、RuCl₃(conversion 91%, TOF 150h^-1) And the like. By passing through-NH₂the-N bifunctional modified graphene is used as a substrate, so that the agglomeration of ultrafine AuPdIr nanoparticles is effectively inhibited, the activity of the catalyst can be obviously improved, and the catalyst has a good application prospect.

drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a Transmission Electron Microscope (TEM) and particle size distribution chart of example 1;

FIG. 2 is a Raman spectrum of example 1;

FIG. 3 is an X-ray diffraction (XRD) pattern of example 1;

FIG. 4a is a time-course plot of the catalytic formic acid decomposition at room temperature for the catalyst prepared in example 1;

FIG. 4b is a gas chromatogram of the catalyst prepared in example 1 catalyzing the decomposition of formic acid to produce gas;

FIG. 5 is a Transmission Electron Microscope (TEM) image of example 2;

FIG. 6 is a Raman spectrum of example 2;

FIG. 7 is an X-ray diffraction (XRD) pattern of example 2;

FIG. 8a is a time-course plot of the catalytic formic acid decomposition at room temperature for the catalyst prepared in example 2;

FIG. 8b is a gas chromatogram of the catalyst prepared in example 2 catalyzing the decomposition of formic acid to produce gas;

FIG. 9 is a Transmission Electron Microscope (TEM) image of example 3;

FIG. 10 is a Raman spectrum of example 3;

FIG. 11 is an X-ray diffraction (XRD) pattern of example 3;

FIG. 12a is a time-course plot of the catalytic formic acid decomposition at room temperature for the catalyst prepared in example 3;

FIG. 12b is a gas chromatogram of the catalyst prepared in example 3 catalyzing the decomposition of formic acid to produce gas;

FIG. 13 is a Transmission Electron Microscope (TEM) image of example 4;

FIG. 14 is a Raman spectrum of example 4;

FIG. 15 is an X-ray diffraction (XRD) pattern of example 4;

FIG. 16a is a time-course plot of the catalytic formic acid decomposition at room temperature for the catalyst prepared in example 4;

FIG. 16b is a gas chromatogram of the catalyst prepared in example 4 catalyzing the decomposition of formic acid to produce gas;

FIG. 17 is a Transmission Electron Microscope (TEM) image of example 5;

FIG. 18 is a Raman spectrum of example 5;

FIG. 19 is an X-ray diffraction (XRD) pattern of example 5;

FIG. 20a is a time-course plot of the catalytic formic acid decomposition at room temperature for the catalyst prepared in example 5;

FIG. 20b is a gas chromatogram of the catalyst prepared in example 5 catalyzing the decomposition of formic acid to produce gas;

FIG. 21 is a Transmission Electron Microscope (TEM) view of a comparative example;

FIG. 22a is a Raman spectrum of a comparative example;

FIG. 22b is an X-ray diffraction (XRD) pattern of comparative example 1;

FIG. 23a is a time-course plot of the catalytic formic acid decomposition at room temperature for a catalyst prepared in a comparative example;

FIG. 23b is a gas chromatogram of a catalyst prepared in comparative example catalyzing the decomposition of formic acid to produce gas.

Detailed Description

Graphene Oxide (GO) is prepared in advance by a Hummer's method, in order to facilitate transverse comparison of various performance parameters of products, the concentrations of graphene oxide adopted in examples 1-5 are all 1.5mg/mL, and in order to expand the protection range of the invention, the concentrations of GO and sodium borohydride NaBH are changed under the same conditions in examples 6-7₄The high-efficiency nano catalyst with the technical effect can be obtained by adding the amount of the catalyst.

wherein, Na₂PdCl₄aqueous solution, HAuCl₄aqueous solution and IrCl₃·xH₂The concentration of the O aqueous solution is 0.02M; stirring reduction is carried out at room temperature, and the reduction time is 10-20 min. AuPdIr/NH₂the-N-rGO high-efficiency catalyst is characterized in that AuPdIR nano particles are uniformly distributed in a-NH passing process₂-N bifunctional group modified graphene carrier NH₂-N-rGO.

When the catalyst is used for hydrogen production by formic acid hydrolysis, the concentration of the formic acid aqueous solution is 0.5-5M, and AuPdIr/NH₂The mol ratio of the-N-rGO high-efficiency catalyst to the formic acid is 0.01-0.5.