Preparation method for preparing imine through selective hydrogenation of nitrile compound

Abstract

The invention belongs to the technical field of selective catalytic hydrogenation, and provides a method for preparing imine through selective hydrogenation of nitrile compounds. The method for preparing imine through selective hydrogenation of the nitrile compound comprises the following steps: fully dissolving the nitrile compound in a solvent, uniformly mixing, adding a transition metal loaded M / SiC-Bx catalyst, fully mixing to form a suspension, then transferring the suspension into a reaction kettle, sealing, purging with hydrogen, maintaining the hydrogen pressure to be 0.1-5MPa, keeping the pressure of the hydrogen to be 0.1-5MPa, and carrying out vacuum drying to obtain the imine. Under the stirring condition, the temperature of the reaction system is kept at 30-150 DEG C, the reaction is carried out for 0.5-12 hours, the imine compound can be obtained, and x is any numerical value between 0.01 and 2. After the transition metal is loaded on the B-doped SiC, the surface of the SiC becomes rich in electrons, so that the capability of activating reaction substrates (nitrile compounds) and hydrogen overflow is obviously improved, and the activity of the catalyst is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of selective catalytic hydrogenation, and particularly relates to a method for preparing imines by selective hydrogenation of nitrile compounds. Background Art

[0002] Imines are important intermediates for the synthesis of natural products, bioactive molecules, multi-purpose ligands and drugs. At present, there are three main methods for the synthesis of imines: 1) condensation of primary amines with ketones or aldehydes; 2) self-oxidation of amines; 3) oxidative coupling of amines with alcohols. These methods have some obvious disadvantages, such as poor functional group tolerance, harsh reaction conditions, generation of some waste pollutants, poor catalyst repeatability, expensive reactants, etc. Compared with amines, the cost of nitrile as a raw material is significantly reduced. Moreover, the synthesis of amines by hydrogenation of nitrile is an efficient and environmentally friendly approach with very high atomic utilization. However, catalytic hydrogenation of nitrile is a complex reaction process, which usually produces a mixed product of primary amines, imines, secondary amines and tertiary amines. How to control the product selectivity is a major problem. The selectivity of the nitrile hydrogenation product depends largely on the catalyst used.

[0003] The efficiency of the catalyst selective hydrogenation of nitrile hydrogenation products needs to be improved. Summary of the invention

[0004] In order to solve the problem of low efficiency of catalyst selective hydrogenation of nitrile hydrogenation products in the prior art, the present invention provides a method for preparing imines by selective hydrogenation of nitrile compounds.

[0005] The method for preparing imines by selective hydrogenation of nitrile compounds comprises the following steps:

[0006] The nitrile compound is fully dissolved in the solvent and mixed evenly, and the transition metal-loaded M / SiC-B x The catalyst is fully mixed into a suspension, and then the suspension is transferred to a reactor and sealed. After purging with hydrogen, the hydrogen pressure is maintained between 0.1 MPa and 5 MPa. Under stirring conditions, the temperature of the reaction system is maintained at 30-150° C. The imine compound can be obtained by reacting for 0.5-12 hours, and the value of x can be any value between 0.01 and 2.

[0007] Furthermore, the solvent is selected from one of methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, cyclohexane, N,N-dimethylformamide and 1,4-dioxane.

[0008] Furthermore, the mass ratio of the nitrile compound to the solvent is (0.01-0.6):1.

[0009] Furthermore, the nitrile compound has a structural formula of R'-R-CN, wherein R' represents one of NO2, Cl, CHO, and CH3, and R represents one of Ar and Alkyl.

[0010] Furthermore, the pressurizing after purging with hydrogen includes purging the reactor with hydrogen three times and then maintaining the hydrogen pressure of the reactor at 0.1-2 MPa.

[0011] Furthermore, x is any value between 0.1 and 0.6.

[0012] Furthermore, M is a transition metal selected from Fe, Co and Ni.

[0013] Beneficial effects:

[0014] The present invention uses the selective catalytic hydrogenation reaction of nitrile compounds as a model reaction to explore the M / SiC-B x Hydrogenation performance of the catalyst. The present invention has found that after B-doped SiC is loaded with transition metals, the activity of catalyzing the hydrogenation of nitrile compounds is significantly increased. In-depth research has found that B doping replaces part of the Si atoms in the SiC lattice and produces C atom vacancies, resulting in an increase in the electron density of Si atoms adjacent to the vacancies. Since the SiC surface becomes electron-rich, the ability to activate the reaction substrate (nitrile compound) and hydrogen overflow is significantly improved, thereby improving the activity of the catalyst.

[0015] The present invention found that B doping can produce acidic sites on the SiC surface, which promotes the deamination condensation of imine and benzylamine in the process of catalytic selective hydrogenation of nitrile compounds, and significantly improves the selectivity of imine formation. x The catalyst still maintains high catalytic performance and shows good cycle stability. Catalyst carrier SiC-B x It is resistant to high temperatures and can be recycled during the catalyst recovery stage to reduce carbon dioxide emissions. The reaction process is green and environmentally friendly, low cost, simple operation, short reaction cycle, high product yield and low production cost and environmental pollution. It is an efficient, stable and environmentally friendly catalyst and catalytic method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of the preparation method of imines by selective hydrogenation of nitrile compounds. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings, but they should not be construed as limiting the applicable scope of the present invention.

[0018] See also Figure 1 The present invention provides a method for preparing imines by selective hydrogenation of nitrile compounds:

[0019] The nitrile compound is fully dissolved in the solvent and mixed evenly, and the transition metal-loaded M / SiC-B x The catalyst is fully mixed into a suspension, and then the suspension is transferred to a reactor and sealed. After purging with hydrogen, the hydrogen pressure is maintained between 0.1 MPa and 5 MPa. Under stirring conditions, the temperature of the reaction system is maintained at 30-150° C. and the reaction is carried out for 0.5-12 hours to obtain the imine compound.

[0020] The transition metal-loaded M / SiC-Bx catalyst involved in the present invention is prepared by the following method:

[0021] SiC-Bx is used as a catalyst carrier, and transition metal nanoparticles are loaded on the surface of the catalyst carrier by a liquid phase reduction method, thereby obtaining an M / SiC-Bx catalyst, wherein M is a transition metal, preferably one of Fe, Co and Ni, and x is any value between 0.01 and 2, preferably any value between 0.1 and 0.6.

[0022] In one embodiment, transition metal-supported M / SiC-B x The preparation method of the catalyst comprises the following steps:

[0023] The SiC-B x The transition metal compound is dispersed in water, mixed with PVP, and then transferred to a reactor and sealed. After purging with hydrogen, the hydrogen pressure is maintained between 0.1-5MPa. Under stirring conditions, the temperature of the reaction system is maintained at 30-150°C. The reaction is carried out for 0.5-12h to obtain M / SiC-B x catalyst.

[0024] Embodiment 1

[0025] Weigh 600 mg of PVP (polyvinyl pyrrolidone) and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0026] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 100 ° C, the reaction is carried out for 6 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed by a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 96.1%, and the selectivity of imine is 90.2%.

[0027] Embodiment 2

[0028] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B1, stir evenly in a magnetic stirrer, and add 4.2 mL of Ni(NO3)2·6H2O aqueous solution (30 mg / mL). Put it in a reactor. Fill the reactor with 2 MPa of hydrogen pressure and react at 150°C for 2 hours to obtain a metal nickel catalyst loaded with 5 wt% silicon carbide, in which the particle size of the nickel metal nanoparticles is 4 nm.

[0029] Take 100 mg of Ni / SiC-B1 catalyst that has been reduced in advance and put it into the lining of the reactor, and measure 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) and add them to the lining of the reactor. After the drugs are added, seal the reactor, ensure airtightness and fill it with 0.1 MPa of high-purity H2. Place the reactor in a heating device, set the stirring rate, reaction temperature, turn on the stirring and heating buttons, and react for 8 hours when the temperature reaches 120°C. Turn off heating and stirring after the reaction is completed. After cooling to room temperature, collect 2 mL of the reaction solution, remove the catalyst particles through a filter, and then perform gas phase analysis. The conversion rate of benzonitrile is 99.9%, and the selectivity of imine is 76.8%.

[0030] Embodiment 3

[0031] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.1 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0032] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.1The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 110 ° C, the reaction is carried out for 10 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 80.2%, and the selectivity of imine is 93.7%.

[0033] Embodiment 4

[0034] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.3 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0035] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.3 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 110 ° C, the reaction is carried out for 10 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 88.4%, and the selectivity of imine is 95.3%.

[0036] Embodiment 5

[0037] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B2, stir evenly in a magnetic stirrer, and add 4.2 mL of Ni(NO3)2·6H2O aqueous solution (30 mg / mL). Put it in a reactor. Fill the reactor with 2 MPa of hydrogen pressure and react at 150°C for 2 hours to obtain a metal nickel catalyst loaded with 5 wt% silicon carbide, in which the particle size of the nickel metal nanoparticles is 4 nm.

[0038] Take 100 mg of Ni / SiC-B2 catalyst that has been reduced in advance and put it into the lining of the reactor, and measure 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) and add them to the lining of the reactor. After the drugs are added, seal the reactor, ensure airtightness and fill it with 0.1 MPa of high-purity H2. Place the reactor in a heating device, set the stirring rate, reaction temperature, turn on the stirring and heating buttons, and react for 10 hours when the temperature reaches 150°C. Turn off heating and stirring after the reaction is completed. After cooling to room temperature, collect 2 mL of the reaction solution, remove the catalyst particles through a filter, and then perform gas phase analysis. The conversion rate of benzonitrile is 99.9%, and the selectivity of imine is 73.2%.

[0039] Embodiment 6

[0040] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0041] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 110 ° C, the reaction is carried out for 12 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 99.9%, and the selectivity of imine is 84.6%.

[0042] Embodiment 7

[0043] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0044] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 90 ° C, the reaction is carried out for 12 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 89.5%, and the selectivity of imine is 90.4%.

[0045] Embodiment 8

[0046] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0047] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 120 ° C, the reaction is carried out for 10 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 99.9%, and the selectivity of imine is 79.7%.

[0048] Embodiment 9

[0049] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 5wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0050] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of ethanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 100 ° C, the reaction is carried out for 6 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed by a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 100.0%, and the selectivity of imine is 78.5%.

[0051] Embodiment 10

[0052] Weigh 600 mg of PVP and dissolve it in 17.48 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 2.52mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 3wt% silicon carbide, wherein the nickel metal nanoparticles have a particle size of 4nm.

[0053] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 100 ° C, the reaction is carried out for 10 hours. After the reaction is completed, turn off the heating and stirring. After cooling to room temperature, collect 2 mL of the reaction solution, remove the catalyst particles through a filter, and then perform gas phase analysis. The conversion rate of benzonitrile is 88.5%, and the selectivity of imine is 96.5%.

[0054] Embodiment 11

[0055] Weigh 600 mg of PVP and dissolve it in 19 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 0.84mL of Ni(NO3)2·6H2O aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal nickel catalyst loaded with 1wt% silicon carbide, wherein the particle size of nickel metal nanoparticles is 4nm.

[0056] Take 100 mg of Ni / SiC-B that has been reduced in advance 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 150 ° C, the reaction is carried out for 10 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 85.6%, and the selectivity of imine is 99.6%.

[0057] Embodiment 12

[0058] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Fe(NO3)2(H2O)6 aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal iron catalyst loaded with 5wt% silicon carbide, in which the iron metal nanoparticles have a particle size of 4nm.

[0059] Take 100 mg of Fe / SiC-B 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 150 ° C, the reaction is carried out for 12 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed by a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 90.3%, and the selectivity of imine is 86.5%.

[0060] Embodiment 13

[0061] Weigh 600 mg of PVP and dissolve it in 18 mL of water. After it is fully dissolved, add 198 mg of SiC-B 0.5 , stir evenly in a magnetic stirrer, add 4.2mL of Co(NO3)2(H2O)6 aqueous solution (30mg / mL). Put it in a reactor. Fill the reactor with 2MPa of hydrogen pressure, react at 150℃ for 2h, and obtain a metal cobalt catalyst loaded with 5wt% silicon carbide, wherein the particle size of the cobalt metal nanoparticles is 4nm.

[0062] Take 100 mg of Co / SiC-B 0.5 The catalyst is placed in the reactor lining, and 10 mL of methanol solution and 0.1 mL of benzonitrile (1 mmol) are added to the reactor lining. After the drugs are added, the reactor is sealed, and 0.1 MPa of high-purity H2 is filled after ensuring airtightness. The reactor is placed in a heating device, the stirring rate and reaction temperature are set, and the stirring and heating buttons are turned on. When the temperature reaches 100 ° C, the reaction is carried out for 10 hours. After the reaction is completed, the heating and stirring are turned off. After cooling to room temperature, 2 mL of the reaction solution is collected, the catalyst particles are removed through a filter, and then gas phase analysis is performed. The conversion rate of benzonitrile is 89.7%, and the selectivity of imine is 91.2%.

[0063] Under the optimal reaction conditions (100°C, 0.1MPa high-purity H2, 10mL methanol, 0.1mL benzonitrile, 100mgM / SiC-B x catalyst) for M / SiC-B x The catalyst was tested for its recyclability, and the test results are shown in Table 1.

[0064] Loop 1 time Loop 2 times Loop 3 times Loop 4 times Loop 5 times Conversion rate (%) 96.1 95.6 94.3 93.8 93.2 Selectivity (%) 90.2 90 90.1 89.7 89.4

[0065] The method comprises the following steps: fully dissolving the nitrile compound in a solvent and mixing the mixture uniformly; adding a catalyst and mixing the mixture fully to form a suspension; then transferring the suspension to a reaction kettle and sealing the reaction kettle; purging the mixture with hydrogen and then reacting the mixture under stirring to obtain an imine compound; the conversion rate can reach 88-100% and the selectivity can reach 72-98%.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing imines by selective hydrogenation of nitrile compounds, characterized in that: The following steps are involved: The nitrile compound is fully dissolved in the solvent and mixed evenly, and the transition metal-loaded M / SiC-B x The catalyst is fully mixed into a suspension, and then the suspension is transferred to a reaction kettle and sealed. After purging with hydrogen, the hydrogen pressure is maintained between 0.1MPa and 5MPa. Under stirring conditions, the temperature of the reaction system is maintained at 30-150°C. The imine compound can be obtained by reacting for 0.5-12h, wherein x is any value between 0.01 and 2, and M is a transition metal.

2. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: The solvent is selected from one of methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, cyclohexane, N,N-dimethylformamide and 1,4-dioxane.

3. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: The mass ratio of the nitrile compound to the solvent is (0.01-0.6):

1.

4. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: The structural formula of the nitrile compound is R'-R-CN, wherein R' represents one of NO2, Cl, CHO, and CH3, and R represents one of Ar and Alkyl.

5. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: Furthermore, the pressurizing after purging with hydrogen includes purging the reactor with hydrogen three times and then maintaining the hydrogen pressure of the reactor at 0.1-2 MPa.

6. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: The value of x can be any value between 0.1 and 0.

6.

7. The method for preparing imines by selective hydrogenation of nitrile compounds as claimed in claim 1, characterized in that: M is a transition metal selected from Fe, Co and Ni.

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