Preparation method and application of a heterogeneous formic acid hydrogen production ruthenium catalyst

Abstract

The present invention relates to the technical field of catalysts, and discloses a preparation method and application of a heterogeneous formic acid hydrogen production ruthenium catalyst, the method comprising the following steps: (1) adding phosphatidylcholine to an ethanol solution of urea and stirring, then dripping an ammonium molybdate solution while stirring to obtain a mixed solution; (2) immersing acid-modified biomass charcoal in the mixed solution, heating it at the same time, filtering, separating, and drying it to obtain a modified biomass carrier; (3) immersing the modified biomass carrier in a hydrochloric acid solution of ruthenium chloride, ultrasonically treating it at the same time, filtering, separating, and drying it, and roasting it in two stages under an inert gas atmosphere to obtain a ruthenium catalyst. The ruthenium catalyst in the present invention uses the modified biomass charcoal as a carrier, and uses ruthenium, molybdenum, and g-C 3 N 4 It is the main catalytic component, and the synergistically doped nitrogen and phosphorus elements are synergistic catalytic components, which can achieve a more efficient catalytic formic acid hydrogen production effect and is beneficial to subsequent operations and repeated recycling.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a preparation method and application of a heterogeneous formic acid hydrogen production ruthenium catalyst. Background Art

[0002] Among the several development directions of the hydrogen production industry, formic acid has a wide range of applications as a safe, green and pollution-free raw material. A formic acid molecule only decomposes to produce one molecule of hydrogen and one molecule of carbon dioxide. The carbon dioxide can be reused, while the hydrogen is relatively pure. Among the many formic acid hydrogen production catalysts, iridium, ruthenium, palladium homogeneous compounds and their derived heterogeneous catalysts all have potential application value. Among them, ruthenium compounds have large reserves and are relatively cheap, making them the preferred catalyst precursors.

[0003] The carriers of heterogeneous catalysts mainly include industrially produced activated carbon, aluminum oxide, titanium oxide, etc., which often cause energy and environmental problems during their production process. Biomass resources are distributed all over the world and are easy to access. If they can be utilized, they will have good prospects for production and environmental protection. Biochar is a carbon-rich porous material produced by the pyrolysis of biomass under oxygen-deficient and high-temperature conditions. It can be used as a better heterogeneous catalyst carrier by utilizing its large specific surface area and pore structure. However, biochar is hydrophobic and has poor dispersibility in water, which leads to poor loading effect of metal catalytic active centers. In addition, biochar that has not been activated and modified has fewer surface functional groups, which is not conducive to being used as a catalyst carrier. Therefore, it is necessary to add a modifier to the carrier of biomass conversion to adjust the properties so that it is more suitable as a heterogeneous catalyst carrier. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a preparation method and application of a heterogeneous formic acid hydrogen production ruthenium catalyst, by modifying biomass carbon while loading ruthenium, molybdenum, gC 3 N 4 As the main catalytic component, the nitrogen and phosphorus elements are synergistically doped to achieve a more efficient catalytic formic acid hydrogen production effect, and it is beneficial for subsequent operations and repeated recycling.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a heterogeneous formic acid hydrogen production ruthenium catalyst, comprising the following steps:

[0007] (1) adding phosphatidylcholine to an ethanol solution of urea and stirring, and then dropping an ammonium molybdate solution while stirring to obtain a mixed solution; in the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1-1.2%, 1.5-2% and 1-1.2%, respectively;

[0008] (2) immersing the acid-modified biomass charcoal in the mixed solution, heating it, filtering it, separating it, and drying it to obtain a modified biomass carrier;

[0009] (3) Immersing the modified biomass carrier in a hydrochloric acid solution of ruthenium chloride, ultrasonically treating it, filtering, separating, and drying it, and calcining it in two stages at 500-600° C. and 700-750° C. in an inert gas atmosphere to obtain a ruthenium catalyst.

[0010] The ruthenium catalyst in the present invention is a heterogeneous catalyst with modified biomass carbon as a carrier, which is mainly composed of ruthenium, molybdenum and gC 3 N 4 It is the main catalytic component, and the synergistically doped nitrogen and phosphorus elements are synergistic catalytic components, which can achieve a more efficient catalytic formic acid hydrogen production effect and is beneficial to subsequent operations and repeated recycling.

[0011] Urea can be treated at high temperature to obtain an ordered carbon structure gC 3 N 4 , which has a certain catalytic effect. Phosphatidylcholine is an amphiphilic molecule with both hydrophilic and hydrophobic groups, and carries both positive and negative heterogeneous charges. Therefore, the addition of phosphatidylcholine helps the combination between urea and ammonium molybdate, and forms a mixed solution similar to micelles in the aqueous solution. The acid-modified biochar is immersed in the mixed solution. After the acid modification of the biochar, the pore structure and the proportion of oxygen-containing functional groups in the biochar are increased, which can provide more loading sites for the micelles. The urea and ammonium molybdate in the micelles can be better combined on the biochar carrier, and because the hydrophobicity of the acid-modified biochar has not been greatly improved, the loading of micelles on the surface of the biochar can make it more hydrophilic, and then the loading and binding effect of ruthenium chloride on the surface of the biochar carrier is better. Afterwards, it is roasted in an inert gas atmosphere. The two-stage roasting can make the roasting more complete, especially the high-temperature roasting in the latter stage can also promote the generation of some active catalytic components of molybdenum nitride, further improving the catalytic effect of formic acid hydrogen production.

[0012] Preferably, in step (1), the mass concentration of urea in the ethanol solution of urea is 4-5%, the mass percentage of ethanol and water in the ethanol solution is 70-80%:20-30%; and the mass concentration of ammonium molybdate in the ammonium molybdate solution is 1.5-2%.

[0013] Preferably, in step (2), the mass ratio of the acid-modified biochar to the mixed solution is 1:10; and the heating treatment is performed at 30-40° C. for 3-5 hours.

[0014] Preferably, in step (2), the preparation of the acid-modified biochar comprises the following steps: adding the biochar to an acid solution, ultrasonically treating the biochar at 70-80° C. for 1-2 h, filtering and separating the biochar, washing the biochar to neutrality, and then drying the biochar to obtain the acid-modified biochar.

[0015] Preferably, the raw material of the biochar is one of cotton, wheat straw and coconut shell; the biochar is granular biochar.

[0016] Preferably, the ratio of the added amount of the biochar to the acid solution is 1 g:10 mL; and the mass concentration of the acid solution is 20-25%.

[0017] Preferably, the acid solution is an aqueous solution of one or more of sulfuric acid, nitric acid, phosphoric acid, acetic acid and formic acid.

[0018] Preferably, in step (3), the inert gas is nitrogen or argon; the calcination is first calcined at 500-600°C for 2-3h, then calcined at 700-750°C for 1-2h, and the heating rate is 3-5°C / min.

[0019] Preferably, in step (3), the mass ratio of the modified biomass carrier to the hydrochloric acid solution of ruthenium chloride is 1:10-12; and the time of the ultrasonic treatment is 1-2 hours.

[0020] Preferably, in step (3), the mass ratio of ruthenium chloride to hydrochloric acid solution in the ruthenium chloride hydrochloric acid solution is 0.3:10; and the mass concentration of the hydrochloric acid solution is 10-15%.

[0021] In a second aspect, the present invention provides an application of a ruthenium catalyst prepared by the above preparation method in a formic acid hydrogen production reaction, comprising the following steps: a formic acid solution is reacted in the presence of a ruthenium catalyst at a reaction temperature of 50-100°C to generate hydrogen.

[0022] Preferably, the ratio of the added amount of formic acid to the ruthenium catalyst is 10 mL: 0.8-2 g.

[0023] Preferably, the formic acid solution is a mixed solution of formic acid and water or other organic solvents miscible with formic acid.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) Ruthenium catalyst is a heterogeneous catalyst with modified biomass carbon as carrier, which is mainly composed of ruthenium, molybdenum and gC 3 N 4 It is the main catalytic component, and the synergistically doped nitrogen and phosphorus elements are synergistic catalytic components, which can achieve a more efficient catalytic formic acid hydrogen production effect and is beneficial to subsequent operations and repeated recycling.

[0026] (2) Urea can be treated at high temperature to obtain an ordered carbon structure gC 3 N 4 , which has a certain catalytic effect. After acid modification, the pore structure and the proportion of oxygen-containing functional groups in the biochar are increased, and more catalytic loading sites can be provided.

[0027] (3) The addition of phosphatidylcholine helps the binding between urea and ammonium molybdate and forms a micelle-like mixed solution in the aqueous solution. The micelles can better bind to the biochar carrier and make the biochar surface more hydrophilic, thereby improving the loading and binding effect of ruthenium chloride on the surface of the biochar carrier. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0029] Example 1

[0030] The preparation of the heterogeneous formic acid hydrogen production ruthenium catalyst comprises the following steps:

[0031] (1) Add 1.7 g of urea to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 55.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.77%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.7% and 1%, respectively.

[0032] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0033] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour. After the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 2 hours and then at 700°C for 1 hour in a nitrogen atmosphere, with a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0034] Example 2

[0035] The preparation of the heterogeneous formic acid hydrogen production ruthenium catalyst comprises the following steps:

[0036] (1) Add 1.7 g of urea to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 55.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.77%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.7% and 1%, respectively.

[0037] (2) Add 10g of biochar (wheat straw) to 100mL of 20% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 70℃ for 1h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0038] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour. After the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 2 hours and then at 700°C for 1 hour in a nitrogen atmosphere, with a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0039] Example 3

[0040] The preparation of the heterogeneous formic acid hydrogen production ruthenium catalyst comprises the following steps:

[0041] (1) Add 2 g of urea to 35 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 5%; add 1.2 g of ammonium molybdate to 60.6 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.94%. Add 1.2 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1.2%, 2% and 1.2%, respectively.

[0042] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 30℃, and treat for 5h; after treatment, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0043] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the biomass carrier in the hydrochloric acid solution of 12 g of ruthenium chloride and treat it ultrasonically for 2 h. After the treatment, filter and separate, dry at 60 ° C, and then calcine at 500 ° C for 3 h and then at 700 ° C for 2 h in a nitrogen atmosphere, with a heating rate of 3 ° C / min, and then cool down to obtain a ruthenium catalyst.

[0044] Example 4

[0045] The preparation of the heterogeneous formic acid hydrogen production ruthenium catalyst comprises the following steps:

[0046] (1) Add 1.5 g of urea to 36 g of ethanol-water solution (the mass percentage of ethanol and water is 70%:30%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 60.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.63%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.5% and 1%, respectively.

[0047] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0048] (3) Add 5 g of ruthenium chloride to 100 g of a 10% hydrochloric acid solution to obtain a ruthenium chloride hydrochloric acid solution. Immerse 1 g of the biomass carrier in the 12 g ruthenium chloride hydrochloric acid solution and ultrasonically treat for 2 h. After the treatment, filter and separate, dry at 60 ° C, and then calcine at 500 ° C for 2 h and then at 700 ° C for 2 h in a nitrogen atmosphere, with a heating rate of 3 ° C / min, and then cool down to obtain a ruthenium catalyst.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that phosphatidylcholine and ammonium molybdate are not added, and segmented roasting is not performed.

[0051] (1) 1.7 g of urea was added to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water was 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%, i.e., a mixed solution.

[0052] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0053] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour; after the treatment, filter and separate, dry at 60°C, and then calcine at 500°C for 5 hours under a nitrogen atmosphere at a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that no phosphatidylcholine is added.

[0056] (1) Add 1.7 g of urea to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 56.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.74%. Add the ammonium molybdate solution to the ethanol solution of urea and stir evenly, then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of urea and ammonium molybdate are 1.7% and 1%, respectively.

[0057] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0058] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour. After the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 2 hours and then at 700°C for 1 hour in a nitrogen atmosphere, with a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0059] Comparative Example 3

[0060] The difference from Example 1 is that no ammonium molybdate solution is added.

[0061] (1) Add 1.7 g of urea to 97.3 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 1.72%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly to obtain a mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine and urea are 1% and 1.7%, respectively.

[0062] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0063] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour; after the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 4 hours in a nitrogen atmosphere at a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0064] Comparative Example 4

[0065] The difference from Example 1 is that the amount of urea added to the mixed solution is too small.

[0066] (1) Add 1.2 g of urea to 28.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 68 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.45%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.2% and 1%, respectively.

[0067] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0068] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour. After the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 2 hours and then at 700°C for 1 hour in a nitrogen atmosphere, with a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0069] Comparative Example 5

[0070] The difference from Example 1 is that the biochar is not acid-modified.

[0071] (1) Add 1.7 g of urea to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 55.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.77%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.7% and 1%, respectively.

[0072] (2) Immerse 1 g of biochar (wheat straw) in 10 g of the mixed solution, heat it to 40 °C, and treat it for 3 h. After the treatment, filter and separate it, and dry it at 60 °C to obtain a modified biomass carrier.

[0073] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour. After the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 2 hours and then at 700°C for 1 hour in a nitrogen atmosphere, with a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0074] Comparative Example 6

[0075] The difference from Example 1 is that no two-stage roasting is performed in step (3).

[0076] (1) Add 1.7 g of urea to 40.8 g of ethanol-water solution (the mass percentage of ethanol and water is 80%:20%) to obtain an ethanol solution of urea with a mass concentration of 4%; add 1 g of ammonium molybdate to 55.5 g of water to obtain an ammonium molybdate solution with a mass concentration of 1.77%. Add 1 g of phosphatidylcholine to the ethanol solution of urea and stir evenly, then add the ammonium molybdate solution dropwise while stirring, and then shake for 1 hour to obtain a uniform mixed solution. In the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1%, 1.7% and 1%, respectively.

[0077] (2) Add 10g of biochar (wheat straw) to 100mL of 25% mass concentration acid solution (sulfuric acid solution), ultrasonically treat at 80℃ for 2h, filter and separate, alternately wash with deionized water and alkaline solution until the solution is neutral, then filter and separate, and dry to obtain acid-modified biochar. Immerse 1g of acid-modified biochar in 10g of the mixed solution, heat to 40℃, and treat for 3h; after the treatment is completed, filter and separate, and dry at 60℃ to obtain a modified biomass carrier.

[0078] (3) Add 5 g of ruthenium chloride to 100 g of a hydrochloric acid solution with a mass concentration of 10% to obtain a hydrochloric acid solution of ruthenium chloride. Immerse 1 g of the modified biomass carrier in the hydrochloric acid solution of 10 g of ruthenium chloride and treat it ultrasonically for 1 hour; after the treatment, filter and separate, dry at 60°C, and then calcine at 600°C for 4 hours under a nitrogen atmosphere at a heating rate of 3°C / min, and then cool down to obtain a ruthenium catalyst.

[0079] Application of the ruthenium catalyst prepared in Examples 1-4 and Comparative Examples 1-6 in the formic acid hydrogen production reaction: 10 mL formic acid, 10 mL water, 0.1 g triethylamine were mixed, 1 g of ruthenium catalyst was added, stirred evenly, heated to 60 ° C for reaction, the gas was collected and analyzed, and the initial TON value (first four minutes) was recorded. The reaction solution was filtered to obtain the ruthenium catalyst, which was washed and dried, and the formic acid hydrogen production reaction was carried out again. After repeated use 10 times, the gas was collected and analyzed, and the initial TON value (first four minutes) was recorded. The gas produced in Examples 1-4 was hydrogen and carbon dioxide, and no carbon monoxide was detected.

[0080] Table 1

[0081]

[0082] As shown in Table 1, the ruthenium catalyst of the present invention is a heterogeneous catalyst with modified biochar as a carrier, which synergizes active catalytic components to achieve a more efficient catalytic formic acid hydrogen production effect, and is conducive to subsequent operation and repeated recycling. It can still maintain a high catalytic activity after 10 repeated uses.

[0083] Comparative Examples 1-4 show that the addition of phosphatidylcholine contributes to the combination between urea and ammonium molybdate, the structural stability of the catalyst is higher, and the load has more active catalytic components, which can synergistically obtain a more efficient catalytic formic acid hydrogen production effect, and the raw material components and the amount added will have a greater impact on the catalytic effect. Comparative Example 5 shows that the biochar increases the pore structure and oxygen-containing functional group ratio of the biochar after acid modification, and can provide more catalytic loading sites, while the catalyst prepared by using biochar that has not been acid-modified has a greatly reduced catalytic effect. Comparative Example 6 shows that the two-stage roasting treatment can make the roasting more sufficient, obtain a more stable catalyst structure, and can also promote the generation of part of the molybdenum nitride active catalytic components, and the catalytic activity after repeated use is better maintained, further improving the catalytic effect of formic acid hydrogen production.

[0084] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a heterogeneous formic acid hydrogen production ruthenium catalyst, characterized in that: The steps include: (1) adding phosphatidylcholine to an ethanol solution of urea and stirring, and then dropping an ammonium molybdate solution while stirring to obtain a mixed solution; in the mixed solution, the mass concentrations of phosphatidylcholine, urea and ammonium molybdate are 1-1.2%, 1.5-2% and 1-1.2%, respectively; (2) immersing the acid-modified biomass charcoal in the mixed solution, heating it, filtering it, separating it, and drying it to obtain a modified biomass carrier; (3) Immersing the modified biomass carrier in a ruthenium chloride hydrochloric acid solution, wherein the mass ratio of the modified biomass carrier to the ruthenium chloride hydrochloric acid solution is 1:10-12, and the mass ratio of ruthenium chloride to the hydrochloric acid solution in the ruthenium chloride hydrochloric acid solution is 0.5:10, simultaneously subjecting the carrier to ultrasonic treatment, filtering, separating, and drying, and calcining the carrier in two stages at 500-600°C and 700-750°C in an inert gas atmosphere to obtain a ruthenium catalyst.

2. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 1, characterized in that: In step (1), the mass concentration of urea in the urea ethanol solution is 4-5%, the mass percentage of ethanol and water in the ethanol solution is 70-80%:20-30%; the mass concentration of ammonium molybdate in the ammonium molybdate solution is 1.5-2%.

3. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 1 or 2, characterized in that: In step (2), the mass ratio of the acid-modified biochar to the mixed solution is 1:10; and the heating treatment is performed at 30-40° C. for 3-5 hours.

4. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 1, characterized in that: In step (3), the calcination is firstly calcined at 500-600°C for 2-3h, and then calcined at 700-750°C for 1-2h, with a heating rate of 3-5°C / min.

5. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 1 or 4, characterized in that: In step (3), the mass concentration of the hydrochloric acid solution is 10-15%.

6. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 1, characterized in that: In step (2), the preparation of the acid-modified biochar comprises the following steps: adding the biochar to an acid solution, ultrasonically treating the biochar at 70-80° C. for 1-2 h, filtering and separating the biochar, washing the biochar to neutrality, and then drying the biochar to obtain the acid-modified biochar.

7. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 6, characterized in that: The raw material of the biochar is one of cotton, wheat straw and coconut shell.

8. The method for preparing the heterogeneous formic acid hydrogen production ruthenium catalyst according to claim 6 or 7, characterized in that: The ratio of the added amount of the biochar to the acid solution is 1 g:10 mL; the mass concentration of the acid solution is 20-25%.

9. Use of a ruthenium catalyst prepared by the preparation method according to any one of claims 1 to 8 in a formic acid hydrogen production reaction, characterized in that: The method comprises the following steps: formic acid solution is reacted in the presence of a ruthenium catalyst at a reaction temperature of 50-100° C. to generate hydrogen.

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