阅读说明：本技术 氮化硼负载金属钌催化剂、制备方法及在制亚胺中的应用 (Boron nitride loaded metal ruthenium catalyst, preparation method and application in imine preparation ) 是由 徐杰 高鸣霞 马继平 高进 范晓萌 苗虹 于 2020-05-25 设计创作，主要内容包括：本申请公开了一种氮化硼负载金属钌催化剂、制备方法及在制亚胺中的应用。所述氮化硼为二维层状结构,所述金属钌负载在所述氮化硼的二维平面上。该催化剂循环使用六次后仍能保持较高催化活性,产物的GC收率均保持在95％以上。(The application discloses a boron nitride loaded metal ruthenium catalyst, a preparation method and application in imine preparation. The boron nitride is of a two-dimensional layered structure, and the metal ruthenium is loaded on a two-dimensional plane of the boron nitride. The catalyst can still maintain higher catalytic activity after being recycled for six times, and the GC yield of the product is kept above 95%.)

1. A boron nitride supported metallic ruthenium catalyst, wherein the boron nitride is hexagonal boron nitride with a two-dimensional layered structure, and the metallic ruthenium is supported on a two-dimensional plane of the boron nitride.

2. The catalyst according to claim 1, wherein the loading amount of the metallic ruthenium in the catalyst is 0.1-10%, wherein the metallic ruthenium is calculated by the mass of the ruthenium element, and the mass of the catalyst is calculated by the mass of the boron nitride.

3. A process for preparing a catalyst according to claim 1 or 2, characterized in that it comprises at least the following steps:

adding a reducing agent into an aqueous dispersion containing a ruthenium source, boron nitride and a complexing agent for reaction to obtain the boron nitride supported metal ruthenium catalyst.

4. The production method according to claim 3, wherein the ruthenium source is a halide or a chlororuthenate of metallic ruthenium;

the halide of the metal ruthenium is at least one of ruthenium trichloride and ruthenium iodide;

the chlorine ruthenate is selected from at least one of chlorine ruthenate ammonium and chlorine ruthenate potassium;

preferably, the complexing agent is a compound containing at least two effective functional groups, and the effective functional groups are at least one of amine groups, hydroxyl groups and carboxyl groups;

preferably, the compound having at least two effective functional groups is selected from at least one of ethylene glycol, ethylenediamine, ethanolamine, butanediamine, proline, lysine, glycine, aspartic acid, serine, arginine, histidine, tyrosine;

preferably, the reducing agent is selected from at least one of sodium borohydride, potassium borohydride and formaldehyde;

preferably, the mass of the ruthenium source is 0.1-10% of the mass of the boron nitride, wherein the mass of the ruthenium source is calculated by the mass of the ruthenium element, and the mass of the boron nitride is calculated by the mass of the boron nitride;

preferably, the molar ratio of the complexing agent to the ruthenium source is 1-50: 1, wherein the complexing agent is calculated by the molar amount of the complexing agent, and the ruthenium source is calculated by the molar amount of the ruthenium element;

preferably, the molar ratio of the reducing agent to the ruthenium source is 5-80: 1, wherein the reducing agent is calculated by the molar amount of the reducing agent, and the ruthenium source is calculated by the molar amount of the ruthenium element;

preferably, the mass ratio of water to boron nitride in the aqueous dispersion is 10-400: 1.

5. The preparation method according to claim 3, wherein the reaction is carried out under the following specific conditions:

under the condition of stirring;

the stirring speed is 200-1000 rpm;

the stirring time is 0.5-12 h.

6. The preparation method according to claim 3, wherein the boron nitride supported metal ruthenium catalyst is obtained by standing, washing, drying and reducing after the reaction is finished.

7. The preparation method according to claim 6, wherein the standing time is 6-48 h.

8. A process for the reductive amination of aldehydes to produce imines comprising:

introducing hydrogen into a mixed solution containing an aldehyde compound, ammonia water and a catalyst to carry out reductive amination reaction to obtain imine;

wherein the catalyst is at least one of the boron nitride supported metallic ruthenium catalyst according to claim 1 or 2 and the boron nitride supported metallic ruthenium catalyst prepared by the preparation method according to any one of claims 3 to 7.

9. The method according to claim 8, wherein the molar amount of the metal ruthenium in the catalyst in the mixed solution is 0.2-20% of the molar amount of the aldehyde compound;

the molar ratio of the ammonia water to the aldehyde compound is 1-15: 1, wherein the molar amount of the ammonia water is calculated by the molar amount of ammonium ions, and the molar amount of the aldehyde compound is calculated by the molar amount of aldehyde groups.

10. The method of claim 8, wherein the specific conditions of the reductive amination reaction comprise:

the hydrogen partial pressure is 0.1-4.0 MPa;

the reaction temperature is 50-150 ℃;

the reaction time is 0.5-36 h;

preferably, the solvent is selected from at least one of acetonitrile, methanol, ethanol, isopropanol, tetrahydrofuran, dichloromethane, toluene and diethyl ether.

Technical Field

The application relates to a boron nitride supported metal ruthenium catalyst, a preparation method thereof and application thereof in imine preparation by aldehyde reductive amination, belonging to the technical field of chemical synthesis.

Background

Unlike conventional oxides, boron nitride is a non-oxide compound composed of boron and nitrogen elements in a hexagonal structure. Boron nitride has excellent physicochemical properties such as non-toxicity, chemical and thermal stability (Nano lett.2013,13, 550-. In addition, as a layered two-dimensional material with a structure similar to graphite, boron nitride can provide a two-dimensional platform to support metal nanoparticles and provide high-activity sites for the surfaces of the nanoparticles, thereby improving the catalytic performance of the catalyst. Ruthenium metal shows very unique catalytic activity for many reactions. For example, it functions as the main catalyst in hydrogenation reactions, removal of organic contaminants and synthesis of low aromatic content diesel fuels (mater. chem. phys.2008,108, 369-374). Hydrogenation using metallic ruthenium catalysts is one of the most important processes in the chemical industry.

Traditional supported catalysts can adjust catalytic performance through the synergistic effect between the carrier and the carrier metal phase, and different surfaces with different physicochemical properties on the carrier often cause uneven distribution and reactivity of the metal-carrier interface, thereby having certain challenge on control of the obtained catalytic selectivity.

Currently, boron nitride supported metal catalysts are typically prepared by an isovolumetric impregnation method. In the catalyst prepared by the method, metal is mainly concentrated on the side surface of the two-dimensional structure of boron nitride, and the stability and the selectivity in the imine preparation by aldehyde reductive amination are poor.

Disclosure of Invention

According to the first aspect of the application, a boron nitride supported metal ruthenium catalyst is provided, the boron nitride is hexagonal boron nitride with a two-dimensional layered structure, the metal ruthenium is supported on a two-dimensional plane of the boron nitride, the catalyst can still maintain high catalytic activity after being recycled for six times, and the GC (gas chromatography) yield of the product is kept above 95%.

Optionally, the loading amount of the metallic ruthenium in the catalyst is 0.1-10%, wherein the metallic ruthenium is calculated by the mass of the ruthenium element, and the catalyst is calculated by the mass of the catalyst.

In a second aspect of the present application, a method for preparing the above catalyst is provided, which at least comprises the following steps:

adding a reducing agent into an aqueous dispersion containing a ruthenium source, boron nitride and a complexing agent for reaction to obtain the boron nitride supported metal ruthenium catalyst.

Optionally, the ruthenium source is a halide or a chlororuthenate of metallic ruthenium;

optionally, the halide of metallic ruthenium is selected from at least one of ruthenium trichloride and ruthenium iodide;

optionally, the chlororuthenate is selected from at least one of ammonium chlororuthenate and potassium chlororuthenate.

Optionally, the complexing agent is a compound containing at least two effective functional groups, and the effective functional groups are at least one of amine groups, hydroxyl groups and carboxyl groups;

optionally, the compound having at least two effective functional groups is selected from at least one of ethylene glycol, ethylenediamine, ethanolamine, butanediamine, proline, lysine, glycine, aspartic acid, serine, arginine, histidine, and tyrosine. Preferably, the compound having at least two effective functional groups is selected from at least one of ethanolamine, proline, lysine, histidine, tyrosine, most preferably proline, lysine.

Optionally, the reducing agent is selected from at least one of sodium borohydride, potassium borohydride and formaldehyde.

Optionally, the mass of the ruthenium source is 0.1-10% of the mass of the boron nitride, wherein the mass of the ruthenium source is calculated by the mass of the ruthenium element, and the mass of the boron nitride is calculated by the mass of the boron nitride.

Preferably, the mass of the ruthenium source is 0.5-8% of the mass of the boron nitride.

More preferably, the mass of the ruthenium source is 1 to 5% of the mass of the boron nitride.

Optionally, the mass of the ruthenium source is selected from 0.5 wt%, 0.8 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt% of the upper limit of the percentage of the mass of the boron nitride; the lower limit is selected from 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt% or 9 wt%.

Optionally, the molar ratio of the complexing agent to the ruthenium source is 1-50: 1, wherein the complexing agent is calculated by the molar amount of the complexing agent, and the ruthenium source is calculated by the molar amount of the ruthenium element.

Preferably, the molar ratio of the complexing agent to the ruthenium source is 2-30: 1.

More preferably, the molar ratio of the complexing agent to the ruthenium source is 3-25: 1.

Optionally, the upper limit of the molar ratio of the complexing agent to the ruthenium source is selected from 2, 2.5, 3,5, 10, 20, 25, 30, 35, 40, or 50; the lower limit is selected from 1, 2, 2.5, 3,5, 10, 20, 25, 30, 35 or 40.

Optionally, the molar ratio of the reducing agent to the ruthenium source is 5-80: 1, wherein the reducing agent is calculated by the molar amount of the reducing agent, and the ruthenium source is calculated by the molar amount of the ruthenium element.

Preferably, the molar ratio of the reducing agent to the ruthenium source is 10-50: 1.

Optionally, the upper limit of the molar ratio of the reducing agent to the ruthenium source is selected from 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, or 80; the lower limit is selected from 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or 60.

Optionally, the mass ratio of water to boron nitride in the aqueous dispersion is 10-400: 1.

Preferably, the mass ratio of water to boron nitride in the aqueous dispersion is 50-300: 1.

More preferably, the mass ratio of water to boron nitride in the aqueous dispersion is 90-200: 1.

Optionally, the upper limit of the mass ratio of water to boron nitride in the aqueous dispersion is selected from 30, 50, 60, 90, 150, 180, 200, 250, 300, 350 or 400; the lower limit is selected from 10, 30, 50, 60, 90, 150, 180, 200, 250, 300, or 350.

Optionally, the reaction, specific conditions include:

under the condition of stirring;

the stirring speed is 200-1000 rpm;

the stirring time is 0.5-12 h.

Preferably, the stirring speed is 300-600 rpm, the stirring time is 1-6 h, and more preferably, the stirring time is 1-3 h.

Optionally, the upper stirring speed limit is selected from 300rpm, 400rpm, 450rpm, 500rpm, 550rpm, 600rpm, 700rpm, 800rpm, 900rpm, or 1000 rpm; the lower limit is selected from 200rpm, 300rpm, 400rpm, 450rpm, 500rpm, 550rpm, 600rpm, 700rpm, 800rpm or 900 rpm.

Optionally, the upper stirring time limit is selected from 1h, 2h, 2.5h, 3h, 3.5h, 4h, 5h, 6h, 8h, 9h, or 12 h; the lower limit is selected from 0.5h, 1h, 2h, 2.5h, 3h, 3.5h, 4h, 5h, 6h, 8h or 9 h.

Optionally, after the reaction is finished, standing, washing, drying and reducing to obtain the boron nitride supported metal ruthenium catalyst.

Optionally, the standing time is 6-48 h.

Preferably, the standing time is 8-36 h.

More preferably, the standing time is 10-24 h.

Optionally, the upper limit of the standing time is selected from 7h, 8h, 9h, 10h, 12h, 16h, 18h, 24h, 36h or 48 h; the lower limit is selected from 6h, 7h, 8h, 9h, 10h, 12h, 16h, 18h, 24h or 36 h.

Optionally, the washing detergent comprises water and an organic solvent;

the organic solvent comprises at least one of ethanol, methanol, ethyl acetate, acetonitrile, 1, 4-dioxane and acetone.

Optionally, the specific conditions of the drying include: the drying mode is vacuum drying, and the drying temperature is 25-100 ℃, preferably 25-80 ℃, and more preferably 35-60 ℃; the drying time is 2-12 h, preferably 3-8 h;

optionally, the upper drying temperature limit is selected from 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃,55 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃ or 100 ℃; the lower limit is selected from 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 60 deg.C, 70 deg.C, 80 deg.C or 90 deg.C.

Optionally, the upper drying time limit is selected from 2.5h, 3h, 4h, 4.5h, 5h, 6h, 7h, 8h, 9h, 10h, or 12 h; the lower limit is selected from 2h, 2.5h, 3h, 4h, 4.5h, 5h, 6h, 7h, 8h, 9h or 10 h.

The specific conditions for the reduction include:

the reaction atmosphere is hydrogen atmosphere;

the reduction temperature is 150-450 ℃;

the reduction time is 1-4 h.

In a specific embodiment, the metal ruthenium salt, the boron nitride and the complexing agent are added into excessive water, mixed and stirred, kept stand, washed, finally dried in vacuum, and reduced by hydrogen to obtain the metal ruthenium catalyst loaded on the surface of the boron nitride. The method has mild conditions, easy operation of the process and environmental protection; the prepared boron nitride loaded metal ruthenium catalyst can be used for preparing imine by aldehyde compounds through a reductive amination process in the presence of hydrogen and a small amount of ammonia water at high selectivity, and has wide application prospects.

In a third aspect of the present application, there is provided a process for the reductive amination of an aldehyde to produce an imine, comprising:

introducing hydrogen into a mixed solution containing an aldehyde compound, ammonia water and a catalyst to carry out reductive amination reaction to obtain imine;

wherein the catalyst is at least one of the boron nitride supported metallic ruthenium catalyst and the boron nitride supported metallic ruthenium catalyst prepared by the preparation method.

Optionally, the molar weight of the metal ruthenium in the catalyst in the mixed solution is 0.2-20% of the molar weight of the aldehyde compound;

optionally, the percentage upper limit of the molar amount of the metal ruthenium in the catalyst in the mixed solution to the molar amount of the aldehyde-based compound is selected from 1%, 4%, 5%, 8%, 10%, 14%, 15%, 16%, 20%; the lower limit is selected from 0.2%, 1%, 4%, 5%, 8%, 10%, 14%, 15%, 16%.

The molar ratio of the ammonia water to the aldehyde compound is 1-15: 1, preferably 1-5: 1, wherein the molar amount of the ammonia water is calculated by the molar amount of ammonium ions, and the molar amount of the aldehyde compound is calculated by the molar amount of aldehyde groups.

Optionally, the upper limit of the molar ratio of the ammonia water to the aldehyde-based compound is selected from 2, 3, 4, 5, 6, 8,10, 11, 12, 14, 15; the lower limit is selected from 1, 2, 3, 4, 5, 6, 8,10, 11, 12, 14.

Alternatively, specific conditions of the reductive amination reaction include:

the hydrogen partial pressure is 0.1-4.0 MPa;

the reaction temperature is 50-150 ℃;

the reaction time is 0.5-36 h.

Preferably, the specific conditions of the reductive amination reaction include:

the hydrogen partial pressure is 1-2 MPa;

the reaction temperature is 50-120 ℃;

the reaction time is 1-24 h.

Alternatively, the upper limit of the hydrogen partial pressure is selected from 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa, 3.0MPa, 4.0 MPa; the lower limit of the hydrogen partial pressure is selected from 0.1MPa, 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa and 3.0 MPa.

The upper limit of the reaction temperature is selected from 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃ and 150 ℃; the lower limit of the reaction temperature is selected from 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ and 120 ℃.

The upper limit of the reaction time is selected from 1h, 2h, 3h, 4h, 5h, 12h, 24h and 36 h; the lower limit of the reaction time is selected from 0.5h, 1h, 2h, 3h, 4h, 5h, 12h and 24 h.

Optionally, the mixed solution further contains a solvent selected from at least one of acetonitrile, methanol, ethanol, isopropanol, tetrahydrofuran, dichloromethane, toluene, and diethyl ether.

In one embodiment, an aldehyde compound, a catalyst, ammonia water and a solvent are added into a reaction kettle, wherein the molar ratio of the aldehyde compound to the aldehyde compound is 1-15, the mixture is heated to 50-150 ℃, the hydrogen partial pressure is 0.1-4.0 MPa, the reaction time is 0.5-36 h, and the aldehyde compound is reductively aminated into imine.

As a specific embodiment, the reductive amination of aldehydes in the present application is represented by formula 1:

wherein R can be selected from aromatic or aliphatic groups. The aromatic group is a group formed by an aromatic compound with one H atom missing, and the aliphatic group is a group formed by an aliphatic compound with one H atom missing.

Optionally, the reductive amination substrate is an aldehyde-based compound selected from at least one of benzaldehyde, furfural, p-nitrobenzaldehyde, p-chlorobenzaldehyde, p-bromobenzaldehyde, 5-hydroxymethylfurfural, 5-methylfurfural, p-methoxybenzaldehyde, phenylpropylaldehyde, 4-pyridinecarboxaldehyde, 3-pyridinecarboxaldehyde, p-methylbenzaldehyde.

Alternatively, the reductive amination product is a secondary aldimine.

Optionally, the drying and reducing comprises calcining at high temperature under hydrogen atmosphere and naturally cooling to obtain the catalyst required by reductive amination.

The application discloses a preparation method of boron nitride loaded metal ruthenium and application of the boron nitride loaded metal ruthenium in preparation of imine through aldehyde reductive amination. The method comprises the steps of preparing a boron nitride supported metal ruthenium catalyst, and applying the boron nitride supported metal ruthenium catalyst to the reductive amination of aldehyde to prepare imine with high selectivity. The method has mild conditions, easy operation of the process and environmental protection; the prepared boron nitride loaded metal ruthenium catalyst can be used for preparing imine by aldehyde compounds through a reductive amination process in the presence of hydrogen and a small amount of ammonia water at high selectivity, and has wide application prospects.

In one embodiment, the catalyst is recycled by cooling naturally after the reaction is finished, centrifuging, washing with an organic solvent, and finally separating to obtain the catalyst.

The beneficial effects that this application can produce include:

1) the method comprises the steps of mixing a complexing agent and a ruthenium source, enabling the ruthenium source to be uniformly attached to a two-dimensional surface of boron nitride, and enabling metal ruthenium to be uniformly loaded on the two-dimensional surface of boron nitride after reduction by adding a reducing agent, so that metal ruthenium is uniformly dispersed, and the selectivity of imine is improved.

2) The catalyst has the advantages of mild preparation conditions, easy operation of the preparation process and environmental friendliness.

3) After the catalyst is recycled for six times, the catalyst still can keep good stability, and the GC yield of the product is kept above 95%.

Drawings

FIG. 1 is an electron micrograph of a boron nitride-supported ruthenium catalyst provided in example 1, wherein FIG. 1a is an HADF-STEM diagram, and FIG. 1b is a TEM diagram.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

The substrate conversion and the product GC yield in the examples were calculated according to the following formulas, respectively.

Example 1

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein: the ruthenium source is ruthenium iodide, the mass of the ruthenium source is 4% of that of boron nitride, the complexing agent is lysine, the molar ratio of the complexing agent to the ruthenium source is 25, and the mass of water is 90 times that of boron nitride;

(2) adding sodium borohydride (the molar ratio of the sodium borohydride to the ruthenium source is 10) into the dispersion liquid, stirring for 2 hours at 400rpm, standing for 12 hours at room temperature, washing with water and ethanol, carrying out suction filtration, carrying out vacuum drying on the solid obtained by suction filtration for 5 hours at 50 ℃ to obtain a boron nitride plane-loaded metal ruthenium catalyst precursor, and calcining and reducing for 3 hours at 250 ℃ in a hydrogen atmosphere to obtain the boron nitride plane-loaded metal ruthenium catalyst (hereinafter referred to as ruthenium-based catalyst).

The application of the catalyst of boron nitride plane load metal ruthenium in preparing imine by aldehyde reductive amination comprises the following steps:

adding benzaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and ethanol into a 15mL reaction kettle, and closing the kettle, wherein the dosage of the benzaldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 10% of that of the benzaldehyde, the molar ratio of the ammonia water to the benzaldehyde is 5, and the dosage of the ethanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 1.5MPa hydrogen, heating to 100 ℃, and reacting for 2h at the temperature. After the reaction, the reaction mixture was naturally cooled to room temperature, and the catalyst was removed by centrifugation. 1mL of internal standard mesitylene was added, and samples were taken and analyzed by gas chromatography. The conversion of benzaldehyde was 99%, and the GC yield of the secondary aldimine 1 (formula 2) was 98%.

Example 2

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 10% of that of the boron nitride, the complexing agent is ethanolamine, the molar ratio of the complexing agent to the ruthenium source is 1, and the mass of the water is 200 times that of the boron nitride;

(2) adding potassium borohydride with the molar ratio of 50 to the ruthenium source into the dispersion, stirring at 600rpm for 0.5h, standing at room temperature for 6h, washing with water and methanol, performing suction filtration, and performing vacuum drying on the solid obtained by suction filtration at 25 ℃ for 8h to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 2h at 250 ℃ in a hydrogen atmosphere to obtain the boron nitride plane-loaded metal ruthenium catalyst.

The application of the catalyst of boron nitride plane load metal ruthenium in preparing imine by aldehyde reductive amination comprises the following steps:

adding furfural, a ruthenium-based catalyst, ammonia water (25 wt%) and diethyl ether into a 15mL reaction kettle, and closing the kettle, wherein the use amount of the furfural is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 20% of the molar weight of the furfural, the molar ratio of the ammonia water to the furfural is 10, and the use amount of the diethyl ether is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 1.0MPa hydrogen, heating to 50 deg.C, and reacting at the temperature for 36 h. After the reaction, according to the method described in example 1, cooling and sampling analysis, the conversion rate of furfural was 99%, and the GC yield of secondary aldimine 2 (formula 3) was 97%.

Example 3

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is potassium chlororuthenate, the mass of the ruthenium source is 10% of that of the boron nitride, the complexing agent is glycine, the molar ratio of the complexing agent to the ruthenium source is 30, and the mass of the water is 50 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 40 to the ruthenium source into the dispersion, stirring at 300rpm for 6 hours, standing at room temperature for 24 hours, washing with water and ethyl acetate, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 60 ℃ for 2 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 1.5h at 300 ℃ in a hydrogen atmosphere to obtain the boron nitride plane-loaded metallic ruthenium catalyst.

Adding p-nitrobenzaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and isopropanol into a 15mL reaction kettle, and closing the kettle, wherein the dosage of the p-nitrobenzaldehyde is 1mmol, the molar weight of the ruthenium in the ruthenium-based catalyst is 14% of that of the p-nitrobenzaldehyde, the molar ratio of the ammonia water to the p-nitrobenzaldehyde is 2, and the dosage of the isopropanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 4.0MPa hydrogen, heating to 150 ℃, and reacting for 3h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of p-nitrobenzaldehyde was 99%, and the GC yield of the secondary aldimine 3 (formula 4) was 98%.

Example 4

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ammonium chlororuthenate, the mass of the ruthenium source is 8% of that of the boron nitride, the complexing agent is ethylene glycol, the molar ratio of the complexing agent to the ruthenium source is 50, and the mass of the water is 400 times that of the boron nitride;

(2) adding formaldehyde with the molar ratio of 20 to the ruthenium source into the dispersion, stirring at 500rpm for 3h, standing at room temperature for 48h, washing with water and acetonitrile, performing suction filtration, and performing vacuum drying on the solid obtained by the suction filtration at 80 ℃ for 3h to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 1h at 450 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding p-chlorobenzaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and toluene into a 15mL reaction kettle, and closing the kettle, wherein the dosage of the p-chlorobenzaldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 0.2% of the molar weight of the p-chlorobenzaldehyde, the molar ratio of the ammonia water to the p-chlorobenzaldehyde is 4, and the dosage of the toluene is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 2.0MPa hydrogen, heating to 150 ℃, and reacting for 1h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of p-chlorobenzaldehyde was 99%, and the GC yield of secondary aldimine 4 (formula 5) was 96%.

Example 5

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium iodide, the mass of the ruthenium source is 0.1% of that of the boron nitride, the complexing agent is ethylenediamine, the molar ratio of the complexing agent to the ruthenium source is 2, and the mass of the water is 10 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 30 to the ruthenium source into the dispersion, stirring at 1000rpm for 1h, standing at room temperature for 8h, washing with water and 1, 4-dioxane, performing suction filtration, and performing vacuum drying on the solid obtained by suction filtration at 100 ℃ for 10h to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 4h at 150 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding p-bromobenzaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and dichloromethane into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the p-bromobenzaldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 4% of the molar weight of the p-bromobenzaldehyde, the molar ratio of the ammonia water to the p-bromobenzaldehyde is 3, and the using amount of the dichloromethane is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 0.1MPa hydrogen, heating to 120 ℃, and reacting for 36h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of p-bromobenzaldehyde was 99%, and the GC yield of secondary aldimine 5 (formula 6) was 98%.

Example 6

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 0.5% of that of the boron nitride, the complexing agent is aspartic acid, the molar ratio of the complexing agent to the ruthenium source is 3, and the mass of the water is 300 times that of the boron nitride;

(2) adding potassium borohydride with the molar ratio of 25 to the ruthenium source into the dispersion, stirring at 200rpm for 12 hours, standing at room temperature for 36 hours, washing with water and acetone, performing suction filtration, and performing vacuum drying on the solid obtained by the suction filtration at 35 ℃ for 12 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 1h at 400 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding 5-hydroxymethylfurfural, a ruthenium-based catalyst, ammonia water (25 wt%) and tetrahydrofuran into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the 5-hydroxymethylfurfural is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 1% of that of the 5-hydroxymethylfurfural, the molar ratio of the ammonia water to the 5-hydroxymethylfurfural is 1, and the using amount of the tetrahydrofuran is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 2.0MPa hydrogen, heating to 80 ℃, and reacting for 24h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of 5-hydroxymethylfurfural was 99%, and the GC yield of the secondary aldimine 6 (formula 7) was 95%.

Example 7

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium iodide, the mass of the ruthenium source is 1% of that of the boron nitride, the complexing agent is proline, the molar ratio of the complexing agent to the ruthenium source is 10, and the mass of the water is 250 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 35 to the ruthenium source into the dispersion, stirring at 200rpm for 5 hours, standing at room temperature for 10 hours, washing with water and ethanol, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 45 ℃ for 6 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 3h at 250 ℃ in hydrogen atmosphere to obtain the catalyst of the metal ruthenium loaded on the boron nitride plane.

Adding 5-methylfurfural, a ruthenium-based catalyst, ammonia water (25 wt%) and isopropanol into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the 5-methylfurfural is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 5% of that of the 5-methylfurfural, the molar ratio of the ammonia water to the 5-methylfurfural is 6, and the using amount of the isopropanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 4.0MPa hydrogen, heating to 120 ℃, and reacting for 0.5h at the temperature. After the reaction was completed, the conversion of 5-methylfurfural was 99%, and the GC yield of the secondary aldimine 7 (formula 8) was 98%.

Example 8

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium iodide, the mass of the ruthenium source is 5% of that of the boron nitride, the complexing agent is histidine, the molar ratio of the complexing agent to the ruthenium source is 40, and the mass of the water is 350 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 45 to the ruthenium source into the dispersion, stirring at 700rpm for 4 hours, standing at room temperature for 16 hours, washing with water and methanol, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 70 ℃ for 7 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 3.5h at 200 ℃ in a hydrogen atmosphere to obtain the boron nitride plane-loaded metallic ruthenium catalyst.

Adding p-methoxybenzaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and methanol into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the p-methoxybenzaldehyde is 1mmol, the molar weight of the ruthenium in the ruthenium-based catalyst is 15% of the molar weight of the p-methoxybenzaldehyde, the molar ratio of the ammonia water to the p-methoxybenzaldehyde is 8, and the using amount of the methanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 3.0MPa hydrogen, heating to 90 ℃, and reacting for 5h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of p-methoxybenzaldehyde was 99%, and the GC yield of secondary aldimine 8 (formula 9) was 96%.

Example 9

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 6% of that of the boron nitride, the complexing agent is butanediamine, the molar ratio of the complexing agent to the ruthenium source is 35, and the mass of the water is 150 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 15 to the ruthenium source into the dispersion, stirring at 800rpm for 2.5 hours, standing at room temperature for 18 hours, washing with water and ethyl acetate, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 30 ℃ for 4 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 2h at 300 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding phenylpropyl aldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and ethanol into a 15mL reaction kettle, and closing the kettle, wherein the dosage of the phenylpropyl aldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 8% of that of the phenylpropyl aldehyde, the molar ratio of the ammonia water to the phenylpropyl aldehyde is 15, and the dosage of the ethanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 0.5MPa hydrogen, heating to 70 ℃, and reacting for 4h at the temperature. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of phenylpropylaldehyde was 99%, and the GC yield of secondary aldimine 9 (formula 10) was 97%.

Example 10

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 3% of that of the boron nitride, the complexing agent is tyrosine, the molar ratio of the complexing agent to the ruthenium source is 5, and the mass of the water is 30 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 5 to the ruthenium source into the dispersion, stirring at 900rpm for 3.5h, standing at room temperature for 7h, washing with water and ethanol, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 40 ℃ for 9h to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 2h at 200 ℃ in a hydrogen atmosphere to obtain the boron nitride plane-loaded metal ruthenium catalyst.

Adding 4-pyridylaldehyde, a ruthenium-based catalyst, ammonia water (25 wt%) and acetonitrile into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the 4-pyridylaldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 16% of that of the 4-pyridylaldehyde, the molar ratio of the ammonia water to the 4-pyridylaldehyde is 12, and the using amount of the acetonitrile is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 2.5MPa hydrogen, heating to 60 deg.C, and reacting at the temperature for 12 h. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of 4-pyridinecarboxaldehyde was 99%, and the GC yield of the secondary aldimine 10 (formula 11) was 98%.

Example 11

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 9% of that of the boron nitride, the complexing agent is arginine, the molar ratio of the complexing agent to the ruthenium source is 20, and the mass of the water is 60 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 80 to the ruthenium source into the dispersion, stirring at 450rpm for 8 hours, standing at room temperature for 9 hours, washing with water and acetone, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 90 ℃ for 2.5 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 4h at 150 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding 3-pyridylaldehyde, a ruthenium-based catalyst, 25 wt% of ammonia water and 5mL of methanol into a 15mL reaction kettle, and closing the kettle, wherein the using amount of the 3-pyridylaldehyde is 1mmol, the molar weight of ruthenium in the ruthenium-based catalyst is 20% of that of the 3-pyridylaldehyde, the molar ratio of the ammonia water to the 3-pyridylaldehyde is 14, and the using amount of the methanol is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 2.5MPa hydrogen, heating to 60 deg.C, and reacting at the temperature for 12 h. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of 3-pyridinecarboxaldehyde was 99%, and the GC yield of the secondary aldimine 11 (formula 12) was 95%.

Example 12

(1) Putting a ruthenium source, a complexing agent and boron nitride into water to obtain a dispersion liquid, wherein the ruthenium source is ruthenium trichloride, the mass of the ruthenium source is 0.8% of that of the boron nitride, the complexing agent is serine, the molar ratio of the complexing agent to the ruthenium source is 25, and the mass of the water is 180 times that of the boron nitride;

(2) and adding sodium borohydride with the molar ratio of 60 to the ruthenium source into the dispersion, stirring at 550rpm for 9 hours, standing at room temperature for 10 hours, washing with water and acetonitrile, carrying out suction filtration, and carrying out vacuum drying on the solid obtained by suction filtration at 55 ℃ for 4.5 hours to obtain the boron nitride plane-loaded metal ruthenium catalyst precursor. Calcining and reducing for 2h at 400 ℃ in a hydrogen atmosphere to obtain the boron nitride plane supported metal ruthenium catalyst.

Adding p-tolualdehyde, ruthenium-based catalyst, ammonia water (25 wt%) and acetonitrile into a 15mL reaction kettle, and closing the kettle, wherein the using amount of p-tolualdehyde is 1mmol, the molar amount of ruthenium in the ruthenium-based catalyst is 16% of the molar amount of p-tolualdehyde, the molar ratio of ammonia water to p-tolualdehyde is 11, and the using amount of acetonitrile is 5 mL; replacing the air in the kettle with hydrogen for 5 times, charging 2.0MPa hydrogen, heating to 70 deg.C, and reacting at the temperature for 24 h. After the reaction was completed, according to the method described in example 1, cooling and sampling analysis, the conversion of p-tolualdehyde was 99%, and the GC yield of secondary aldimine 12 (formula 13) was 98%.

Example 13

The catalyst preparation and reduction of the catalyst precursor and for the reductive amination of benzaldehyde were carried out according to the conditions of example 1, except that in example 1: after the reaction is finished, the catalyst is centrifugally separated, the ethanol solvent is used for continuously centrifugally washing the catalyst for 5 times, the benzaldehyde is recycled for reductive amination reaction again, the catalyst is recycled for six times, and the results are shown in the table I.

TABLE I, boron nitride plane load metal ruthenium catalyst reduction amination circulation use effect to benzaldehyde

As can be seen from the table I, the prepared boron nitride plane load metal ruthenium catalyst can still keep higher catalytic activity after being recycled for six times of reductive amination of benzaldehyde, and the GC yield of the secondary aldimine 1 (formula 2) is kept above 95%. The catalysts provided in the embodiments 2 to 12 can be recycled under the same conditions, and can maintain high catalytic activity, and the GC yield of the secondary aldimine after six times of recycling is maintained above 95%.

Fig. 1 is an electron micrograph of the catalyst provided in example 1, and it can be seen from the figure that metallic ruthenium is uniformly supported on the two-dimensional plane of the boron nitride. Other embodiments provide catalysts having the same or similar morphology.

Comparative example 1

Putting boron nitride into a ruthenium source water solution, soaking in an equal volume, drying, and roasting at 250 ℃ for 3h to obtain the catalyst, wherein: the ruthenium source is ruthenium iodide, and the mass of the ruthenium source is 4% of that of the boron nitride.

The application of the catalyst of boron nitride plane load metal ruthenium in preparing imine by aldehyde reductive amination comprises the following steps:

the procedure was followed as in example 1, except that the conversion of benzaldehyde was 99% and the GC yield of the secondary aldimine 1 (formula 2) was 22%.

When the boron nitride supported metal ruthenium catalyst is applied to the preparation of imine by aldehyde reductive amination, the substrate aldehyde conversion rate is over 99 percent; the GC yield of the product secondary aldimine is more than 95%.

The preparation method has mild conditions, easy operation of the process and environmental protection; the prepared boron nitride loaded metal ruthenium catalyst can be used for preparing imine by aldehyde compounds through a reductive amination process in the presence of hydrogen and a small amount of ammonia water at high selectivity, and has wide application prospects.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.