A diatomic catalyst for hydrogen production from formic acid, its preparation method and application

Abstract

The present invention discloses a diatomic catalyst for hydrogen production from formic acid, its preparation method, and application. The method first forms a precursor from a metal salt and a nitrogen and carbon source, and then pyrolyzes the precursor at high temperature using magnesium hydroxide and ZnCo-ZIF as templates to obtain an atomically dispersed dibase metal catalyst. The atomically dispersed dibase metal catalyst of the present invention has a formic acid hydrogen production performance of 2.9L gmetal at 98°C using PC as a solvent. ‑1 h ‑1 ~77.7L gmetal ‑1 h ‑1 , 5 to 40 times higher than commercial 5% Pd / C. More importantly, the catalyst maintained its initial activity after five cycles and a 72-hour long-term test, with Co and Cu loss rates of 7.4% and 3.8%, respectively. Compared to precious metal catalysts, this catalyst not only efficiently catalyzes formic acid to produce hydrogen, but also significantly reduces costs. It can be used to store and transport hydrogen using existing fuel infrastructure, establishing a formic acid-based hydrogen supply chain.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts for producing hydrogen from formic acid, and more particularly to an atomically dispersed bi-base metal catalyst for efficiently catalyzing formic acid to produce hydrogen and a preparation method thereof. Background Art

[0002] Hydrogen is currently considered one of the most important energy carriers of the future, enabling a more sustainable and efficient modern energy system. As a solution, liquid organic hydrogen carriers (LOHCs) have been considered because they can store and transport hydrogen using existing fuel infrastructure. However, the dehydrogenation step requires high temperatures and possible hydrogen purification, which limits the overall efficiency of the hydrogen storage process. Compared with traditional LOHCs, formic acid (FA) has a comparable mass / volume hydrogen capacity (4.4 wt% and 53 g·L -1 ), in the presence of a suitable catalyst, reversible hydrogen storage reactions can be easily carried out. Therefore, it is necessary to use catalytic reactions to lower the reaction temperature and improve selectivity, and the development of catalysts is urgently needed.

[0003] In the carbon-neutral hydrogen cycle system based on formic acid, green hydrogen produced by renewable energy is combined with carbon dioxide produced by traditional fossil energy to produce formic acid. Formic acid is stored and transported through existing fuel infrastructure, and hydrogen energy is finally utilized through formic acid to produce hydrogen. The generated carbon dioxide is returned to the circulation system through carbon capture technology, and no additional carbon dioxide is produced. "Ionic polymer microspheres loaded with palladium catalyze the decomposition of formic acid to produce hydrogen" was disclosed in the 11th issue of Chemical Bulletin in 2020. The authors are Shao Shouyan, Zhu Guisheng, Huang Zhijun, Wang Zhonghua, and Yan Fengwen. The article discloses that palladium nanoparticles loaded with dendritic ionic polymer microspheres are used to catalyze the decomposition of formic acid to produce hydrogen, and explores the effects of formic acid concentration and reaction temperature on the hydrogen production rate. The resulting catalyst has high activity and is reusable. However, the current formic acid hydrogen production catalysts are mainly precious metal catalysts, and the scarcity of precious metals leads to high application costs, which limits their development.

[0004] In heterogeneous cobalt-based catalysts used in formic acid hydrogen production, their overall activity and stability, especially in acidic media, are very poor. Therefore, it is very necessary to develop heterogeneous low-cost metal catalysts with high activity, high selectivity and high stability. Summary of the Invention

[0005] The present invention aims to solve the problems of precious metal scarcity and poor stability of heterogeneous cobalt-based catalysts in the prior art. To this end, the present invention provides an atomically dispersed bi-base metal catalyst that efficiently catalyzes formic acid to produce hydrogen. In the preparation method of the present invention, a magnesium hydroxide template method can be used to introduce metals such as Co, Cu, and Ni in a targeted manner. The prepared atomically dispersed bi-base metal catalyst has a mass activity of 22.9 to 77.7 L gmetal formic acid production at 75°C to 98°C with PC as the solvent. -1 h -1 , 12 to 40 times higher than commercial 5% Pd / C, while also exhibiting excellent selectivity and stability. The catalyst of this invention exhibits excellent hydrogen production from formic acid decomposition, operates in a mild reaction environment, and its synthesis method is adaptable to a variety of bimetallic compositions, minimizing loss of active components. This technology addresses the issue of high costs, and the resulting catalyst exhibits high activity and excellent stability in acidic media, making it suitable for large-scale hydrogen storage and controlled release.

[0006] In the process of preparing the diatomic catalyst for producing hydrogen from formic acid of the present invention, the pyrolysis sacrificial template includes magnesium hydroxide and ZnCo-ZIF, the bimetallic includes CoFe, CoCu, CoNi, CoMn, etc., and the catalyst support is a nitrogen-carbon support.

[0007] The present invention provides a diatomic catalyst for producing hydrogen from formic acid and a preparation method thereof, which comprises the following steps:

[0008] Step 1, preparing a mixture by pyrolyzing the template;

[0009] First, a metal salt is added to a reaction vessel, followed by a ligand, and then anhydrous ethanol; after being uniformly stirred, the mixture is placed in an oil bath at 40° C. to 60° C.; after magnetic stirring for 10 to 50 minutes, a pyrolysis template material is added, and the mixture is magnetically stirred for 30 to 90 minutes and then allowed to stand to obtain a template mixture;

[0010] The magnetic stirring speed is 600r / min~1200r / min;

[0011] Dosage: 100g of pyrolysis template material requires 2.500g to 14.549g of metal salt, 3.366g to 15.000g of ligand, and 0.1L to 1L of anhydrous ethanol;

[0012] The metal salt includes one or a combination of two of cobalt acetate, copper acetate, ferrous acetate, nickel acetate, manganese acetate, cobalt chloride, copper chloride, ferrous chloride, nickel chloride, manganese chloride, cobalt nitrate, copper nitrate, nickel nitrate, and manganese nitrate;

[0013] The ligand includes one or a combination of two of 1,10-phenanthroline, imidazole compounds, oxalic acid, dicarboxylic acid and ethylenediamine;

[0014] Step 2, rotary evaporation to prepare a solid mixture;

[0015] Step 21, removing ethanol from the mixture by rotary evaporation at 50° C. to 70° C. to obtain a solid mixture;

[0016] The speed used in the rotary evaporation process is 50r / min to 150r / min;

[0017] Step 22, the mixture solid is placed in a vacuum of 1×10 4 Pa~2×10 4 After drying under Pa for 15 h to 24 h, a dry powder was obtained;

[0018] Step 3: high temperature pyrolysis powder making;

[0019] Step 31: The dried powder is placed in a ball mill and finely ground for 20 to 60 minutes to obtain a fine powder with a particle size of 23 to 38 microns.

[0020] The grinding media are steel balls with an average diameter of less than 6 mm, and the steel balls occupy 50% to 60% of the effective volume of the grinding container;

[0021] Step 32, calcining the fine powder at 500° C. to 900° C. for 100 min to 150 min under an Ar or N2 protective atmosphere, and cooling to obtain a pyrolysis powder;

[0022] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0023] Step 41, mechanically stirring the pyrolysis powder from step 3 in a 4 mol / L HNO3 solution for 15 to 36 hours to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixture;

[0024] Step 42, washing the pyrolysis mixture with deionized water three times and then with anhydrous ethanol three times to obtain a pyrolysis mixture;

[0025] Step 43: placing the pyrolysis mixture in a drying oven and drying it at 80° C. to 100° C. for 5 to 10 hours to obtain a diatomic catalyst for hydrogen production from formic acid.

[0026] Compared with existing formic acid hydrogen production catalysts, the atomically dispersed bibase metal catalyst of the present invention has the following beneficial effects:

[0027] ① The catalyst of the present invention is simple to prepare, low in cost, and easy to operate. A series of bimetallic site catalysts can be prepared and can be widely used in hydrogen production from formic acid.

[0028] ② The catalyst of the present invention exhibits excellent formic acid hydrogen production performance and is particularly suitable for acidic media.

[0029] ③ The catalyst of the present invention can retain most of the active components during multiple cycles and long-term reactions, and the catalyst is easy to recover. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a Raman spectrum of the catalyst of Example 1 prepared by the method of the present invention. The horizontal axis Raman shift represents the Raman shift, and the vertical axis Intensity represents the relative intensity.

[0031] Figure 2 This is the X-ray diffraction pattern of the catalyst of Example 1 prepared by the method of the present invention. The abscissa represents the diffraction angle, and the ordinate Intensity represents the relative intensity.

[0032] Figure 3 This is the XPS spectrum of the catalyst of Example 1 prepared by the method of the present invention. The horizontal axis "Binding energy" represents the binding energy, and the vertical axis "Intensity" represents the relative intensity.

[0033] Figure 4 This is the Co-K edge synchrotron radiation spectrum of the catalyst of Example 1 prepared by the method of the present invention. The abscissa "Energy" represents energy, and the ordinate "Intensity" represents relative intensity.

[0034] Figure 5 This is the Cu-K edge synchrotron radiation spectrum of the catalyst of Example 1 prepared by the method of the present invention. The abscissa "Energy" represents energy, and the ordinate "Intensity" represents relative intensity.

[0035] Figure 6 This is a comparison chart of the gas production of the single-atom catalyst and the catalyst of Example 1 of the present invention. The horizontal axis Time represents the reaction time, and the vertical axis represents the volume of gas produced.

[0036] Figure 7 This is a comparison of activation energies of a single-atom catalyst and the catalyst of Example 1 of the present invention. The horizontal axis 1000 / T represents 1000 / reaction temperature, and the vertical axis ln(Rate) represents the natural logarithm of the reaction rate.

[0037] Figure 8 This is a comparison chart of the activities of noble metals, single-atom catalysts, and the catalyst of Example 1 of the present invention. The horizontal axis "Catalysts" represents the type of catalyst, and the vertical axis "Mass activity" represents the mass activity.

[0038] Figure 9This is an activity diagram of the catalyst of Example 1 of the present invention after five reaction cycles. The horizontal axis "Reaction conditions" represents the reaction conditions, and the vertical axis "Mass activity" represents the mass activity.

[0039] Figure 10 This is a 72-hour long-term activity graph of the catalyst of Example 1 of the present invention. The horizontal axis "Time" represents the reaction time, and the vertical axis represents the volume of gas produced. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0041] The present invention provides a diatomic catalyst for producing hydrogen from formic acid and a preparation method thereof, comprising the following steps:

[0042] Step 1, preparing a mixture by pyrolyzing the template;

[0043] First, a metal salt is added to a reaction container, followed by a ligand, and then anhydrous ethanol; after being stirred evenly, the mixture is placed in an oil bath at 40° C. to 60° C.; after magnetic stirring for 10 to 50 minutes, a pyrolysis template material is added, and the mixture is allowed to stand after continuing magnetic stirring for 30 to 90 minutes to obtain a template mixture.

[0044] In the present invention, the magnetic stirring speed is adjusted to 600 r / min to 1200 r / min.

[0045] Dosage: 100 g of the pyrolysis template material requires 2.500 g to 14.549 g of metal salt, 3.366 g to 15.000 g of ligand, and 0.1 L to 1 L of anhydrous ethanol.

[0046] In the present invention, the metal salt includes one or a combination of two of cobalt acetate, copper acetate, ferrous acetate, nickel acetate, manganese acetate, cobalt chloride, copper chloride, ferrous chloride, nickel chloride, manganese chloride, cobalt nitrate, copper nitrate, nickel nitrate, and manganese nitrate.

[0047] In the present invention, the ligand includes one or a combination of two of 1,10-phenanthroline, an imidazole compound (such as 2-methylimidazole), oxalic acid, dicarboxylic acid and ethylenediamine.

[0048] The chemical formula of magnesium hydroxide is H2MgO2, and its molecular weight is 58.31.

[0049] Cobalt acetate is also known as cobalt acetate, preferably cobalt acetate tetrahydrate, chemical formula C4H 14 CoO8, molecular weight is 249.08.

[0050] Copper acetate is also called copper acetate, preferably copper acetate monohydrate, with a chemical formula of C4H8CuO5 and a molecular weight of 199.65.

[0051] Ferrous acetate is also called ferrous acetate, preferably ferrous acetate hydrate, with a chemical formula of C4H6O4Fe and a molecular weight of 173.93.

[0052] Nickel acetate is also known as nickel acetate, preferably nickel acetate (tetrahydrate), chemical formula C4H 14 NiO8, molecular weight is 248.84.

[0053] Manganese acetate is also known as manganese acetate, preferably manganese acetate tetrahydrate, chemical formula C4H 14 MnO8, molecular weight is 245.09.

[0054] Cobalt chloride, preferably cobalt chloride hydrate, chemical formula Cl2CoH 12 O6, molecular weight is 237.93.

[0055] Copper chloride, preferably copper (II) chloride dihydrate, chemical formula Cl2CuH4O2, molecular weight 170.48.

[0056] Ferrous chloride, preferably ferrous chloride tetrahydrate, has a chemical formula of Cl2FeH8O4 and a molecular weight of 198.81.

[0057] Nickel chloride, preferably nickel chloride hexahydrate, chemical formula Cl2H 12 NiO6, molecular weight is 237.69.

[0058] Manganese chloride, preferably manganese chloride tetrahydrate, has a chemical formula of Cl2H8MnO4 and a molecular weight of 197.91.

[0059] Cobalt nitrate, preferably cobalt nitrate hexahydrate, chemical formula CoH 12 N2O 12 , molecular weight is 291.03.

[0060] Copper nitrate, preferably copper nitrate hydrate, has a chemical formula of CuH6N2O9 and a molecular weight of 241.60.

[0061] Nickel nitrate, preferably nickel nitrate hydrate, chemical formula H 12 N2NiO 12 , molecular weight is 290.79.

[0062] Manganese nitrate, preferably manganese (II) nitrate tetrahydrate, chemical formula H8MnN2O 10 , molecular weight is 251.01.

[0063] Step 2, rotary evaporation to prepare a solid mixture;

[0064] Step 21, removing ethanol from the mixture by rotary evaporation at 50° C. to 70° C. to obtain a solid mixture.

[0065] In the present invention, the rotation speed adopted in the rotary evaporation process is 50 r / min to 150 r / min.

[0066] Step 22, the mixture solid is placed in a vacuum of 1×10 4 Pa~2×10 4 After drying under Pa for 15 to 24 hours, a dry powder was obtained.

[0067] Step 3: high temperature pyrolysis powder making;

[0068] Step 31: The dried powder is placed in a ball mill for fine grinding. The grinding time is 20 to 60 minutes to obtain a fine powder with a particle size of 23 to 38 microns.

[0069] In the present invention, the grinding media are steel balls with an average diameter of less than 6 mm, and the steel balls occupy 50% to 60% of the effective volume of the grinding container.

[0070] Step 32: calcining the fine powder at 500° C. to 900° C. for 100 min to 150 min under an Ar or N 2 protective atmosphere, and then cooling to obtain a pyrolysis powder.

[0071] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0072] Step 41: Mechanically stir the pyrolysis powder obtained in step 3 in a 4 mol / L HNO 3 solution for 15 to 36 hours to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0073] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0074] Step 43: placing the pyrolysis mixture in a drying oven and drying it at 80° C. to 100° C. for 5 to 10 hours to obtain a diatomic catalyst (or atomically dispersed dibase metal catalyst).

[0075] Hydrogen production performance test

[0076] The atomically dispersed bimetallic catalyst prepared by the method of the present invention is used in formic acid hydrogen production. 6ml to 10ml of PC (propylene carbonate) and 10mg to 50mg of atomically dispersed bimetallic catalyst (biatomic catalyst) are added to each 10mmol of formic acid solution to test formic acid hydrogen production activity. The reaction temperature is 75℃ to 98℃. At 98℃, with PC as the solvent, the formic acid hydrogen production performance reaches 2.9L gmetal -1 h-1 ~77.7L gmetal -1 h -1 , 5 to 40 times higher than commercial 5% Pd / C. More importantly, the catalyst maintained its initial activity after five cycles and a 72-hour long-term test, with Co and Cu loss rates of 7.4% and 3.8%, respectively. Compared to precious metal catalysts, this catalyst not only efficiently catalyzes formic acid to produce hydrogen, but also significantly reduces costs. It can be used to store and transport hydrogen using existing fuel infrastructure, establishing a formic acid-based hydrogen supply chain.

[0077] Example 1

[0078] Step 1, preparing a mixture using magnesium hydroxide as a template;

[0079] Cobalt acetate tetrahydrate and copper acetate monohydrate are first added to a reaction container, followed by 1,10-phenanthroline and then anhydrous ethanol; after being uniformly stirred, the mixture is placed in an oil bath at 60°C; magnesium hydroxide is added after magnetic stirring at a speed of 600 r / min for 30 minutes, and the mixture is magnetically stirred for 60 minutes before being allowed to stand to obtain a mixture with magnesium hydroxide as a template.

[0080] Dosage: 100 g of magnesium hydroxide requires 6.227 g of cobalt acetate tetrahydrate, 2.496 g of cobalt acetate monohydrate, 12.500 g of 1,10-phenanthroline and 1 L of anhydrous ethanol.

[0081] Step 2, rotary evaporation to prepare a solid mixture;

[0082] Step 21, removing ethanol from the mixture at 60° C. and a rotary evaporation speed of 80 r / min to obtain a mixture solid.

[0083] Step 22, the mixture solid is placed in a vacuum of 1×10 4 After drying at Pa for 24 h, dry powder was obtained.

[0084] Step 3: high temperature pyrolysis powder making;

[0085] Step 31: The dried powder is placed in a ball mill for fine grinding for 30 minutes to obtain a fine powder with an average particle size of 35 microns.

[0086] Step 32: calcining the fine powder at 700° C. for 120 min under a N 2 atmosphere and then cooling to obtain a pyrolysis powder.

[0087] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0088] In step 41, the pyrolysis powder obtained in step 3 is mechanically stirred in a 4 mol / L HNO 3 solution for 18 h to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0089] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0090] Step 43: placing the pyrolysis mixture in a drying oven and drying it at 100° C. for 7 hours to obtain an atomically dispersed bi-base metal catalyst.

[0091] The atomically dispersed bi-base metal catalyst prepared in Example 1 is recorded as Co / Cu-NC.

[0092] Hydrogen production performance test

[0093] The Co / Cu-NC prepared in Example 1 was used as a catalyst for hydrogen production from formic acid. 6 ml of PC and 30 mg of Co / Cu-NC were added to a 10 mmol formic acid solution to test the formic acid hydrogen production activity at a reaction temperature of 98°C.

[0094] The Co / Cu-NC prepared in Example 1 was tested by Raman spectroscopy. Figure 1 As shown in the Raman spectrum, the D band (1345 cm -1 ) and G band (1590cm -1 ) is 1.21, indicating that there are a large number of defects in the NC support. Figure 2 As shown in the figure, there is no diffraction peak of any crystalline metal species, indicating that all metal atoms are well dispersed. XPS and synchrotron radiation were used to characterize Co / Cu-NC: its XPS spectrum is shown in the figure. Figure 3 As shown, the presence of Co / Cu / N / C elements was observed, and the Co-K edge and Cu-K edge synchrotron radiation spectra were as follows Figure 4 and Figure 5 As shown, the data indicate that well-dispersed bimetallic single atoms are formed, and the active sites are found to be composed of double N-bridged CoN4 and CuN4 sites through spectrum analysis; Figure 6 and Figure 7 As shown in the figure, compared with the single-atom Co-NC catalyst, the Co / Cu-NC has much better performance in hydrogen production from formic acid, and the effect is significantly improved. Figure 8 As shown, Co / Cu-NC exhibits a mass activity of 77.7 L gmetal -1 h -1 The catalytic performance is far superior to that of precious metal Pd / C and Pt / C catalysts. Figure 9 and Figure 10The results showed that the catalyst exhibited excellent stability in 5 cycles and 72 hours of long-term testing. Single-atom Co-NC catalyst reference "Co-based Single Atom Site Catalysts with High Stability for Selective Dehydrogenation of Formic Acid" was published in "Angewandte Chemie International Edition" Volume 59, Issue 37, 2020, by Xiang Li and Matthias Beller. The article points out that metal-organic framework (MOF)-derived Co-NC single-atom catalysts are used for formic acid dehydrogenation and have higher activity, stronger acid resistance and better long-term stability than cobalt nanoparticle catalysts.

[0095] Table 1 Comparison of GC data of Example 1 with Co-NC, Cu-NC and NC

[0096] experiment <![CDATA[H2(Vol%)]]> <![CDATA[CO2(Vol%)]]> CO (Vol%) <![CDATA[H2 / CO2]]> Time(h) Example 1 52.8 47.1 0.07 1.07 1 Example 1 51.1 48.0 0.07 1.05 4 Example 1 51.5 48.4 0.07 1.06 72 Co-NC 50.7 48.9 0.09 1.03 1 Co-NC 51.4 48.2 0.1 1.06 4 Co-NC 50.2 49.7 0.1 1.01 72 Cu-NC 24.0 72.1 3.84 0.33 4 NC nd nd nd nd 4

[0097] Note: nd stands for no gas detected.

[0098] In the present invention, the same preparation process as in Example 1 was used, except that the amount of 1,10-phenanthroline added was changed from 12.5 g to 10 g, and hydrogen production from formic acid was also achieved. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 70.2 L g metal -1 h -1 , 37 times higher than commercial 5% Pd / C.

[0099] In the present invention, the same preparation process as in Example 1 was used, except that the amount of 1,10-phenanthroline added was changed from 12.5 g to 15 g, and hydrogen production from formic acid was also achieved. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 32.5 L g metal -1 h -1 , 17 times higher than commercial 5% Pd / C.

[0100] In the present invention, the same preparation process as in Example 1 is used, except that the molar ratio of cobalt and copper added is changed from 2:1 to 1:1, and hydrogen production from formic acid can also be achieved. At 98°C, PC is used as a solvent, and the formic acid hydrogen production performance reaches 56.7Lgmetal -1 h -1 , 29 times higher than commercial 5% Pd / C.

[0101] In the present invention, the same preparation process as in Example 1 is used, except that the molar ratio of cobalt and copper added is changed from 2:1 to 1:2, and hydrogen production from formic acid can also be achieved. At 98°C, PC is used as a solvent, and the formic acid hydrogen production performance reaches 11.0Lgmetal -1 h -1 , 6 times higher than commercial 5% Pd / C.

[0102] In the present invention, the same preparation process as in Example 1 is used, except that the molar ratio of cobalt and copper added is changed from 2:1 to 3:1, and hydrogen production from formic acid can also be achieved. At 98°C, PC is used as a solvent, and the formic acid hydrogen production performance reaches 45.2Lgmetal -1 h -1 , 23 times higher than commercial 5% Pd / C.

[0103] Example 2

[0104] Step 1, preparing a mixture using magnesium hydroxide as a template;

[0105] Cobalt acetate tetrahydrate and nickel nitrate hydrate are first added to a reaction container, followed by ethylenediamine and then anhydrous ethanol; after being uniformly stirred, the mixture is placed in an oil bath at 60°C; magnesium hydroxide is added after magnetic stirring at a speed of 800 r / min for 10 minutes, and the mixture is magnetically stirred for 60 minutes before being allowed to stand to obtain a mixture using magnesium hydroxide as a template.

[0106] Dosage: 100 g of magnesium hydroxide requires 6.227 g of cobalt acetate tetrahydrate, 3.635 g of nickel nitrate hexahydrate, 3.366 g of ethylenediamine and 0.2 L of anhydrous ethanol.

[0107] Step 2, rotary evaporation to prepare a solid mixture;

[0108] Step 21, removing ethanol from the mixture at 50° C. and a rotary evaporation speed of 50 r / min to obtain a mixture solid.

[0109] Step 22, the mixture solid is placed in a vacuum of 1.2×10 4 After drying at Pa for 18 h, a dry powder was obtained.

[0110] Step 3: high temperature pyrolysis powder making;

[0111] Step 31: The dried powder is placed in a ball mill for fine grinding for 20 minutes to obtain a fine powder with an average particle size of 25 microns.

[0112] Step 32: calcining the fine powder at 500° C. for 100 min under a N 2 atmosphere and cooling the fine powder to obtain a pyrolysis powder.

[0113] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0114] In step 41, the pyrolysis powder obtained in step 3 is mechanically stirred in a 4 mol / L HNO 3 solution for 16 h to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0115] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0116] Step 43: Place the pyrolysis mixture in a drying oven and dry it at 80° C. for 5 h to obtain an atomically dispersed bi-base metal catalyst, which is recorded as Co2 / Ni1-NC catalyst.

[0117] Hydrogen production performance test

[0118] The Co2 / Ni1-NC prepared in Example 2 was used as a catalyst. 6 ml of PC and 30 mg of catalyst were added to a 10 mmol formic acid solution to test the formic acid hydrogen production activity. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 2.9 L g metal -1 h -1 , twice as high as commercial 5% Pd / C.

[0119] Example 3

[0120] Step 1, preparing a mixture using magnesium hydroxide as a template;

[0121] Cobalt chloride hydrate and ferrous chloride tetrahydrate are first added to a reaction container, followed by 2-methylimidazole and 1,10-phenanthroline, and then anhydrous ethanol. After being stirred evenly, the mixture is placed in an oil bath at 50°C. Magnesium hydroxide is added after magnetic stirring at a speed of 800 r / min for 10 minutes, and the mixture is magnetically stirred for 60 minutes before being allowed to stand to obtain a mixture with magnesium hydroxide as a template.

[0122] Dosage: 100 g of magnesium hydroxide requires 5.948 g of cobalt chloride hydrate, 2.485 g of ferrous chloride tetrahydrate, 0.7345 g of 2-methylimidazole, 6.6105 g of 1,10-phenanthroline and 0.5 L of anhydrous ethanol.

[0123] Step 2, rotary evaporation to prepare a solid mixture;

[0124] Step 21, removing ethanol from the mixture at 70° C. and a rotary evaporation speed of 150 r / min to obtain a mixture solid.

[0125] Step 22, the mixture solid is placed in a vacuum of 2×10 4 After drying at Pa for 24 h, dry powder was obtained.

[0126] Step 3: high temperature pyrolysis powder making;

[0127] In step 31, the dried powder is put into a ball mill for fine grinding for 60 minutes to obtain a fine powder with an average particle size of 30 microns.

[0128] Step 32: calcining the fine powder at 700° C. for 150 min under a N 2 atmosphere and cooling the fine powder to obtain a pyrolysis powder.

[0129] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0130] In step 41, the pyrolysis powder obtained in step 3 is mechanically stirred in a 4 mol / L HNO 3 solution for 36 hours to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0131] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0132] Step 43, placing the pyrolysis mixture in a drying oven and drying it at 90°C for 10 hours to obtain an atomically dispersed bi-base metal catalyst, which is recorded as Co2 / Fe1-NC catalyst.

[0133] Hydrogen production performance test

[0134] The Co2 / Fe1-NC prepared in Example 3 was used as a catalyst. 6 ml of PC and 30 mg of catalyst were added to a 10 mmol formic acid solution to test the formic acid hydrogen production activity. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 17.0 L gmetal -1 h -1 , 9 times higher than commercial 5% Pd / C.

[0135] Example 4

[0136] Step 1, preparing a mixture using magnesium hydroxide as a template;

[0137] Cobalt nitrate hexahydrate and copper nitrate hydrate are first added to a reaction container, followed by oxalic acid and then anhydrous ethanol; after being uniformly stirred, the mixture is placed in an oil bath at 60°C; magnesium hydroxide is added after magnetic stirring at a speed of 800 r / min for 10 minutes, and the mixture is magnetically stirred for 60 minutes before being allowed to stand to obtain a mixture with magnesium hydroxide as a template.

[0138] Amount: 100g of magnesium hydroxide requires 7.276g of cobalt nitrate hexahydrate, 3.020g of copper nitrate hydrate, 7.060g of oxalic acid and 1L of anhydrous ethanol.

[0139] Step 2, rotary evaporation to prepare a solid mixture;

[0140] Step 21, removing ethanol from the mixture at 60° C. and a rotary evaporation speed of 100 r / min to obtain a solid mixture.

[0141] Step 22, the mixture solid is placed in a vacuum of 1×10 4 After drying at Pa for 20 h, dry powder was obtained.

[0142] Step 3: high temperature pyrolysis powder making;

[0143] In step 31, the dried powder is put into a ball mill for fine grinding for 20 minutes to obtain a fine powder with an average particle size of 30 microns.

[0144] Step 32: calcining the fine powder at 700° C. for 150 min under a N 2 atmosphere and cooling the fine powder to obtain a pyrolysis powder.

[0145] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0146] In step 41, the pyrolysis powder obtained in step 3 is mechanically stirred in a 4 mol / L HNO 3 solution for 18 h to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0147] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0148] Step 43: Place the pyrolysis mixture in a drying oven and dry it at 95° C. for 8 h to obtain an atomically dispersed bi-base metal catalyst, which is recorded as Co2 / Cu1-NC catalyst.

[0149] Hydrogen production performance test

[0150] The Co2 / Cu1-NC prepared in Example 4 was used as a catalyst. 6 ml of PC and 30 mg of catalyst were added to a 10 mmol formic acid solution to test the formic acid hydrogen production activity. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 35.4 L g metal -1 h -1 , 26 times higher than commercial 5% Pd / C.

[0151] Example 5

[0152] Step 1, preparing a mixture using ZnCo-ZIF as a template;

[0153] ZnCo-ZIF is first added to a reaction container, followed by anhydrous ethanol; after being stirred evenly, the mixture is placed in an oil bath at 60°C; manganese nitrate hexahydrate is added after magnetic stirring at a speed of 700 r / min for 10 minutes, and the mixture is magnetically stirred for 60 minutes before being allowed to stand to obtain a mixture with ZnCo-ZIF as a template.

[0154] Dosage: 100 g of ZnCo-ZIF requires 1.830 g of manganese chloride tetrahydrate, 5.000 g of 1,10-phenanthroline, and 1 L of anhydrous ethanol.

[0155] Step 2, rotary evaporation to prepare a solid mixture;

[0156] Step 21, removing ethanol from the mixture at 60° C. and a rotary evaporation speed of 100 r / min to obtain a solid mixture.

[0157] Step 22, the mixture solid is placed in a vacuum of 1×10 4 After drying at Pa for 20 h, dry powder was obtained.

[0158] Step 3: high temperature pyrolysis powder making;

[0159] In step 31, the dried powder is put into a ball mill for fine grinding for 20 minutes to obtain a fine powder with an average particle size of 36 microns.

[0160] Step 32: calcining the fine powder at 900° C. for 120 min under an Ar atmosphere and cooling the fine powder to obtain a pyrolysis powder.

[0161] Step 4, preparing an atomically dispersed bibase metal catalyst;

[0162] In step 41, the pyrolysis powder obtained in step 3 is mechanically stirred in a 4 mol / L HNO 3 solution for 18 h to remove the metal nanoparticles remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixed solution.

[0163] In step 42, the pyrolysis mixture is first washed three times with deionized water and then washed three times with anhydrous ethanol to obtain a pyrolysis mixture.

[0164] Step 43: Place the pyrolysis mixture in a drying oven and dry it at 95° C. for 8 hours to obtain an atomically dispersed bi-base metal catalyst, which is recorded as Co / Mn-NC catalyst.

[0165] Hydrogen production performance test

[0166] The Co / Mn-NC prepared in Example 4 was used as a catalyst. 6 ml of PC and 30 mg of catalyst were added to a 10 mmol formic acid solution to test the formic acid hydrogen production activity. At 98 ° C, PC was used as a solvent, and the formic acid hydrogen production performance reached 10.5 L g metal-1 h -1 , 5 times higher than commercial 5% Pd / C.

Claims

1. A method for preparing an atomically dispersed bi-base metal catalyst for hydrogen production from formic acid, characterized in that The preparation method comprises the following steps: Step 1, preparing a mixture by pyrolyzing the template; First, a metal salt is added to a reaction vessel, followed by a ligand, and then anhydrous ethanol; after being uniformly stirred, the mixture is placed in an oil bath at 40° C. to 60° C.; after magnetic stirring for 10 to 50 minutes, a pyrolysis template material is added, and the mixture is magnetically stirred for 30 to 90 minutes and then allowed to stand to obtain a template mixture; The magnetic stirring speed is 600r / min~1200r / min; Dosage: 100g of pyrolysis template material requires 2.500g to 14.549g of metal salt, 3.366g to 15.000g of ligand, and 0.1L to 1L of anhydrous ethanol; The metal salts include two of cobalt acetate, copper acetate, ferrous acetate, nickel acetate, manganese acetate, cobalt chloride, copper chloride, ferrous chloride, nickel chloride, manganese chloride, cobalt nitrate, copper nitrate, nickel nitrate, and manganese nitrate; The ligand includes one or a combination of two of 1,10-phenanthroline, imidazole compounds and ethylenediamine; The pyrolysis template material is magnesium hydroxide, and the metal is directionally introduced using the magnesium hydroxide template method; Step 2, rotary evaporation to prepare a solid mixture; Step 21, removing ethanol from the mixture by rotary evaporation at 50° C. to 70° C. to obtain a solid mixture; The speed used in the rotary evaporation process is 50r / min to 150r / min; Step 22, the mixture solid is placed in a vacuum of 1×10 4 Pa~2×10 4 After drying under Pa for 15 h to 24 h, a dry powder was obtained; Step 3: high temperature pyrolysis powder making; Step 31: The dried powder is placed in a ball mill and finely ground for 20 to 60 minutes to obtain a fine powder with a particle size of 23 to 38 microns. The grinding media are steel balls with an average diameter of less than 6 mm, and the steel balls occupy 50% to 60% of the effective volume of the grinding container; Step 32, calcining the fine powder at 500° C. to 900° C. for 100 min to 150 min under an Ar or N2 protective atmosphere, and cooling to obtain a pyrolysis powder; Step 4, preparing an atomically dispersed bibase metal catalyst; Step 41, mechanically stirring the pyrolysis powder from step 3 in a 4 mol / L HNO3 solution for 15 to 36 hours to remove the metal nanoparticles and magnesium oxide remaining on the surface of the pyrolysis powder, thereby obtaining a pyrolysis mixture; Step 42, washing the pyrolysis mixture with deionized water three times and then with anhydrous ethanol three times to obtain a pyrolysis mixture; Step 43: placing the pyrolysis mixture in a drying oven and drying it at 80° C. to 100° C. for 5 to 10 hours to obtain an atomically dispersed bi-base metal catalyst for hydrogen production from formic acid.

2. An atomically dispersed bibase metal catalyst prepared by the method according to claim 1.

3. The atomically dispersed bi-base metal catalyst according to claim 2, characterized in that The bibase metal includes CoFe, CoCu, CoNi or CoMn.

4. The atomically dispersed bi-base metal catalyst according to claim 3, characterized in that The bibase metal is CoCu.

5. Use of the atomically dispersed bibase metal catalyst according to claim 2 or 3 in hydrogen production from formic acid, characterized in that: To every 10 mmol of formic acid solution, 6 ml to 10 ml of propylene carbonate and 10 mg to 50 mg of the atomically dispersed bimetallic catalyst are added. The reaction temperature is 75°C to 98°C. The formic acid hydrogen production performance reaches 2.

9. ~77.7 .

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