Method for efficiently synthesizing primary amines

Abstract

The present disclosure provides a method for efficiently synthesizing primary amines, the method comprising: using carbonyl compounds or alcohol compounds as reaction substrates, using liquid ammonia or an alcohol solution of ammonia as a nitrogen source, and using hydrogen as a hydrogen source, and reacting in a reaction medium under the catalysis of a cobalt-based catalyst to obtain primary amines. The method has high catalytic activity, can realize the reductive amination of carbonyl compounds and the hydrogen amination of alcohol compounds under low temperature and short time conditions, obtains primary amines with high yield, and has a wide range of applicable substrates. The obtained primary amines can be used as raw materials for the production of polymers, drugs, dyes and surfactants, and have high added value; secondly, the cobalt-based catalyst has magnetism, which is convenient for the separation and recycling of the catalyst, and has good industrial application prospects; thirdly, the cobalt-based catalyst has low cost, which can effectively reduce the cost of industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial synthesis, and in particular to a method for efficiently synthesizing primary amines. Background Art

[0002] Currently, the general industrial routes for the synthesis of primary amines are direct amination of alkyl halides or epoxides with ammonia, and hydrogenation of nitriles or amides; however, these processes are usually costly due to the lack of organic raw materials with special functional groups and are prone to produce a large amount of waste.

[0003] The preferred routes for synthesizing primary amines are direct amination of alcohol compounds and reductive amination of aldehydes and ketones. The direct amination of alcohol compounds involves dehydrogenation of alcohols and is a rate-determining step, which usually requires a relatively high reaction temperature (160-250°C). Although reductive amination of aldehydes and ketones can be achieved under mild conditions (70-150°C) by catalytic reduction of aldehydes and ketones with ammonia and hydrogen, the reaction substrate selection range is narrow and difficult to obtain. In addition, the synthesis of primary amines also faces the problems of high catalyst preparation cost and low selectivity, and the catalyst and product are difficult to separate and recycle, which does not have the potential for industrialization, affecting the progress of industrialization.

[0004] Therefore, there is an urgent need for a method for synthesizing primary amines with high yield, low cost and industrial potential. Summary of the invention

[0005] In view of this, the purpose of the present disclosure is to provide a method for efficiently synthesizing primary amines.

[0006] Based on the above purpose, the present disclosure provides a method for efficiently synthesizing primary amines, which comprises using a carbonyl compound or an alcohol compound as a reaction substrate, liquid ammonia or an alcohol solution of ammonia as a nitrogen source, and hydrogen as a hydrogen source, and reacting in a reaction medium under the catalysis of a cobalt-based catalyst to obtain a primary amine.

[0007] In some embodiments, the carbonyl compound includes aliphatic aldehydes and ketones and aromatic aldehydes and ketones;

[0008] And / or, the alcohol compound includes aliphatic alcohol and aromatic alcohol;

[0009] and / or, the alcoholic ammonia solution comprises at least one of ammonia methanol, ammonia ethanol and ammonia isopropanol;

[0010] And / or, the reaction medium comprises an organic solvent, and the organic solvent comprises at least one of methanol, ethanol, isopropanol, ethylene glycol dimethyl ether, tetrahydrofuran, toluene and p-xylene. Preferably, the reaction medium is methanol and p-xylene.

[0011] In some embodiments, the mass ratio of the reaction substrate to the cobalt-based catalyst is 1:(0.01-2);

[0012] And / or, the mass ratio of the reaction substrate to the reaction medium is 1:(1-60), preferably 1:(1-30);

[0013] and / or, the concentration of the alcoholic ammonia solution is 2M to 7M;

[0014] and / or, the pressure of the liquid ammonia after gasification is 0.1 to 1 MPa, preferably 0.3 to 0.8 MPa;

[0015] And / or, the pressure of the hydrogen is 0.5 to 5 MPa, preferably 0.5 to 2 MPa;

[0016] and / or, the reaction temperature is 70 to 200° C., preferably 70 to 150° C.;

[0017] And / or, the reaction time is 0.5 to 25 hours, preferably 2 to 24 hours.

[0018] In some embodiments, the cobalt-based catalyst comprises a core-shell Co@CoO catalyst, wherein the core of the core-shell Co@CoO catalyst is cobalt and the shell is cobaltous oxide containing oxygen vacancies.

[0019] In some embodiments, the method for preparing the core-shell Co@CoO catalyst includes preparing a precursor, and then optionally reducing the precursor to obtain the core-shell Co@CoO catalyst;

[0020] Preferably, the volume fraction of hydrogen in the reducing gas is 5 to 30%, more preferably 5 to 15%;

[0021] and / or, the flow rate of the reducing gas is 10 to 100 ml / min, preferably 10 to 40 ml / min;

[0022] and / or, the reduction temperature is 100 to 400° C., preferably 200 to 350° C.;

[0023] And / or, the reduction time is 1 to 6 hours, preferably 1 to 3 hours.

[0024] In some embodiments, the method for preparing the precursor comprises preparing a precipitate by a precipitation method using a cobalt source and a precipitant, and then optionally calcining the precipitate to obtain the precursor;

[0025] Preferably, the cobalt source comprises at least one of a salt, an ester and a complex containing the cobalt element, and more preferably the cobalt source is selected from at least one of cobalt nitrate, cobalt acetate, cobalt carbonyl and cobalt chloride;

[0026] and / or, the precipitating agent comprises at least one of an amide, a base and a salt capable of co-precipitating with the cobalt source, preferably the precipitating agent is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate and urea;

[0027] And / or, the calcination temperature is 400-450°C.

[0028] In some embodiments, the method for preparing the precursor includes preparing the precursor by high-temperature thermal decomposition of a cobalt source;

[0029] Preferably, the cobalt source comprises at least one of a salt, an ester and a complex containing the cobalt element, and more preferably the cobalt source is selected from at least one of cobalt nitrate and cobalt acetate;

[0030] And / or, the conditions of the high temperature thermal decomposition method include: the calcination temperature is 300-600°C, preferably 400-550°C.

[0031] In some embodiments, the cobalt-based catalyst comprises a supported cobalt-based catalyst, and the carrier of the supported cobalt-based catalyst comprises at least one of a metal oxide, SiO2 and activated carbon;

[0032] Preferably, the metal oxide includes at least one of Group IIIA metal oxides, Group IIA metal oxides, Group IVB metal oxides, lanthanide metal oxides and Group VIB metal oxides, and more preferably, the metal oxide is selected from at least one of Al2O3, MgO, MgAl2O4, TiO2, ZrO2, CeO2 and MoO3.

[0033] In some embodiments, the method for preparing the supported cobalt-based catalyst includes preparing a precursor, and then optionally reducing the precursor to obtain the supported cobalt-based catalyst;

[0034] Preferably, the volume fraction of hydrogen in the reducing gas is 5 to 30%, more preferably 5 to 15%;

[0035] and / or, the flow rate of the reducing gas is 10 to 100 ml / min, preferably 10 to 40 ml / min;

[0036] and / or, the reduction temperature is 100 to 400° C., preferably 200 to 350° C.;

[0037] And / or, the reduction time is 1 to 6 hours, preferably 1 to 3 hours.

[0038] In some embodiments, the method for preparing the precursor comprises co-precipitating a cobalt source and a carrier precursor to obtain a precipitate, and then optionally calcining the precipitate to obtain the precursor;

[0039] Preferably, the cobalt source comprises at least one of a salt, an ester and a complex containing the cobalt element, and more preferably the cobalt source is selected from cobalt chloride;

[0040] and / or, the carrier precursor comprises at least one of a salt of a Group IIIA metal, a salt of a Group IIA metal, a salt of a Group IVB metal, a salt of a lanthanide metal, and a salt of a Group VIB metal;

[0041] And / or, the calcination temperature is 350-450°C.

[0042] In some embodiments, the method for preparing the precursor comprises obtaining a carrier, then loading a cobalt source on the carrier by an equal volume impregnation method, an excess impregnation method, or a precipitation deposition method, and finally optionally calcining;

[0043] Preferably, the cobalt source comprises at least one of a salt, an ester and a complex containing the cobalt element, and more preferably the cobalt source is selected from cobalt chloride;

[0044] And / or, the calcination temperature is 350-450°C.

[0045] As can be seen from the above, the present disclosure provides a method for efficiently synthesizing primary amines, which uses carbonyl compounds or alcohol compounds as reaction substrates, liquid ammonia or an alcohol solution of ammonia as a nitrogen source, and hydrogen as a hydrogen source, and reacts in a reaction medium under the catalysis of a cobalt-based catalyst to obtain primary amines; the method has high catalytic activity, can achieve reductive amination of carbonyl compounds and hydrogen amination of alcohol compounds under low temperature and short time conditions, to obtain high-yield primary amines, and has a wide range of applicable substrates. The obtained primary amines can be used as raw materials for the production of polymers, drugs, dyes and surfactants, and have high added value; secondly, the cobalt-based catalyst has magnetism, which is convenient for the separation and recycling of the catalyst, and has good industrial application prospects; thirdly, the cobalt-based catalyst has low cost, which can effectively reduce the cost of industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the present disclosure or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 The XRD pattern of the core-shell Co@CoO catalyst provided in the embodiment of the present disclosure;

[0048] Figure 2 TEM image of the active phase of the core-shell Co@CoO catalyst provided in the embodiments of the present disclosure. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0050] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure should have the common meanings understood by persons having ordinary skills in the field to which the present disclosure belongs.

[0051] Nitrogen-containing compounds, especially primary amines, are one of the most important intermediates in the chemical industry and are widely used in the synthesis of polymers, drugs, agrochemicals, dyes and surfactants. Currently, the general industrial route for the synthesis of primary amines is the direct amination of alkyl halides or epoxides with ammonia, and the hydrogenation of nitriles or amides; however, these processes are usually costly due to the lack of organic raw materials with special functional groups and the easy generation of large amounts of waste.

[0052] The preferred routes for synthesizing primary amines are direct amination of alcohol compounds and reductive amination of aldehydes and ketones. The direct amination of alcohol compounds generally does not require consumption of an external hydrogen source, and water is the main byproduct, which is green and environmentally friendly. However, the process involves dehydrogenation of alcohols and is a rate-determining step, which usually requires a higher reaction temperature (160-250°C). Although the reductive amination of aldehydes and ketones can be achieved under mild conditions (70-150°C) by catalytic reduction amination of aldehydes and ketones with ammonia and hydrogen, the reaction substrate selection range is narrow and difficult to obtain.

[0053] In addition, the synthesis of primary amines also faces the problems of high catalyst preparation cost and low selectivity, and the catalyst and product are difficult to separate and recycle, and have no industrial potential, which affects the progress of industrialization. Therefore, there is an urgent need to develop an efficient catalytic system to obtain primary amines in high yield under low temperature and short time conditions, and to produce primary amines sustainably. There is also an urgent need for a primary amine synthesis method with high yield, low cost and industrial potential.

[0054] In order to solve the above problems, the present disclosure provides a method for efficiently synthesizing primary amines, which comprises using a carbonyl compound or an alcohol compound as a reaction substrate, liquid ammonia or an alcohol solution of ammonia as a nitrogen source, and hydrogen as a hydrogen source, and reacting in a reaction medium under the catalysis of a cobalt-based catalyst to obtain a primary amine.

[0055] In the present disclosure, the carbonyl compound refers to a compound containing a carbonyl group in its structure, such as an aldehyde carbonyl-containing compound or a ketone carbonyl-containing compound, etc., without specific limitation. The alcohol compound refers to a compound containing a hydroxyl group in its structure, such as a saturated aliphatic hydrocarbon hydroxyl-containing compound, an unsaturated aliphatic hydrocarbon hydroxyl-containing compound or an aromatic hydroxyl-containing compound, etc., without specific limitation. The alcohol solution of ammonia refers to a solution obtained by dissolving ammonia in alcohol, such as ammonia dissolved in methanol, ethanol, propanol or isopropanol, etc., without specific limitation.

[0056] In some possible embodiments, the carbonyl compound may include aliphatic aldehydes and ketones and aromatic aldehydes and ketones.

[0057] In the present disclosure, the aliphatic hydrocarbon aldehydes and ketones may include aliphatic hydrocarbon aldehydes and aliphatic hydrocarbon ketones, and the aliphatic hydrocarbon aldehydes refer to aldehyde compounds in which an aldehyde group is connected to an aliphatic hydrocarbon group or a hydrogen atom, and the aliphatic hydrocarbon aldehydes may include saturated aliphatic hydrocarbon aldehydes and unsaturated aliphatic hydrocarbon aldehydes, and the present disclosure has no restrictions on the number of carbon atoms, substituents and specific structures contained in the aliphatic hydrocarbon groups in the aliphatic hydrocarbon aldehydes. Aliphatic hydrocarbon ketones refer to compounds in which a carbonyl group is connected to two aliphatic hydrocarbon groups, and the aliphatic hydrocarbon ketones may include saturated aliphatic hydrocarbon ketones and unsaturated aliphatic hydrocarbon ketones, and the present disclosure has no restrictions on the number of carbon atoms, substituents and specific structures contained in the aliphatic hydrocarbon groups in the aliphatic hydrocarbon ketones. Preferably, the aliphatic hydrocarbon aldehydes and ketones may include at least one of acetone, propionaldehyde, butanone, butyraldehyde, 2-pentanone, valeraldehyde, 4-heptanone, octanal, 2-octanone and 5-nonanone.

[0058] The aromatic aldehydes and ketones may include aromatic aldehydes and aromatic copper, wherein the aromatic aldehydes refer to aldehyde compounds in which the carbonyl group is connected to an aromatic hydrocarbon group and hydrogen respectively, and the present disclosure does not have any restrictions on the number of carbon atoms, substituents and specific structures contained in the aromatic hydrocarbon group in the aromatic aldehyde. The aromatic ketones may include pure aromatic ketones and mixed aromatic ketones, wherein the pure aromatic ketones refer to compounds in which a carbonyl group is connected to two aromatic hydrocarbon groups, and the mixed aromatic ketones refer to compounds in which one single bond of the carbonyl group is connected to an aromatic hydrocarbon group and another single bond is connected to a non-aromatic hydrocarbon group, and the present disclosure does not have any restrictions on the number of carbon atoms, substituents and structures contained in the aromatic hydrocarbon group and the non-aromatic hydrocarbon group in the aromatic ketone. Preferably, the aromatic aldehydes and ketones may include at least one of benzaldehyde, phenylacetaldehyde, phenylpropionaldehyde, acetophenone, 4-chloroacetophenone 2-bromoacetophenone, 2-methoxypropiophenone, 2-naphthaldehyde, 4-hydroxyphenylacetophenone, 4-methoxybenzaldehyde and benzophenone.

[0059] In some possible embodiments, the alcohol compound may include aliphatic alcohol and aromatic alcohol.

[0060] In the present disclosure, the fatty alcohol refers to an alcohol compound in which a hydroxyl group is connected to an aliphatic hydrocarbon group, and the fatty alcohol may include a saturated fatty alcohol and an unsaturated fatty alcohol. The present disclosure has no restrictions on the number of carbon atoms, substituents and specific structures contained in the aliphatic hydrocarbon group in the fatty alcohol. The aromatic alcohol refers to a compound in which a hydroxyl group is connected to a carbon atom on a benzene ring branch in an aromatic hydrocarbon group. The present disclosure has no restrictions on the number of carbon atoms, substituents and specific structures contained in the aromatic hydrocarbon group in the aromatic alcohol. Preferably, the alcohol compound may include at least one of propanol, n-butanol, cyclopentanol, cyclohexanol, 1-octanol and benzyl alcohol.

[0061] In some possible embodiments, the alcoholic ammonia solution may include at least one of ammonia methanol, ammonia ethanol, and ammonia isopropanol.

[0062] In some possible embodiments, the reaction medium may include an organic solvent, and the organic solvent may include at least one of methanol, ethanol, isopropanol, ethylene glycol dimethyl ether, tetrahydrofuran, toluene and p-xylene. Preferably, the reaction medium is methanol and p-xylene.

[0063] In some possible embodiments, the mass ratio of the reaction substrate to the cobalt-based catalyst may be 1:(0.01-2).

[0064] The reaction substrates described in the present disclosure include carbonyl compounds and alcohol compounds; the "mass ratio of the reaction substrate to the cobalt-based catalyst" refers to the ratio of the mass of the reaction substrate to the mass of the cobalt-based catalyst, and the ratio can be 1:(0.01-2), for example, 1:0.01, 1:0.1, 1:0.5, 1:1, 1:1.5 or 1:2, etc., without specific limitation.

[0065] In some possible embodiments, the mass ratio of the reaction substrate to the reaction medium may be 1:(1-60), preferably 1:(1-30).

[0066] The "mass ratio of the reaction substrate to the reaction medium" in the present disclosure refers to the ratio of the mass of the reaction substrate to the mass of the reaction medium, and the ratio may be 1:(1-60), preferably 1:(1-30), for example, 1:5, 1:10, 1:15, 1:20 or 1:25, etc., without specific limitation.

[0067] In some possible embodiments, the concentration of the alcoholic ammonia solution may be 2M to 7M.

[0068] The concentration of the alcohol solution of ammonia described in the present disclosure refers to the molar concentration of ammonia in alcohol, which may be 2M to 7M, for example, 2M, 3M, 4M, 5M, 6M or 7M, etc., without specific limitation.

[0069] In some possible implementation schemes, the pressure of the liquid ammonia after gasification is 0.1-1 MPa, preferably 0.3-0.8 MPa.

[0070] The pressure of liquid ammonia after gasification described in the present disclosure refers to the pressure after liquid ammonia is gasified into ammonia gas, which can be 0.1-1 MPa, preferably 0.3-0.8 MPa, for example, 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa or 1 MPa, etc., without specific limitation.

[0071] In some possible implementations, the pressure of the hydrogen may be 0.5 to 5 MPa, preferably 0.5 to 2 MPa.

[0072] In some possible embodiments, the reaction temperature may be 70 to 200°C, preferably 70 to 150°C.

[0073] The reaction temperature described in the present disclosure refers to the temperature required for generating primary amines from reaction substrates, which can be 70 to 200°C, preferably 70 to 150°C, for example, 70°C, 100°C, 130°C, 150°C, 170°C or 200°C, etc., without specific limitation. The cobalt-based catalyst provided in the present disclosure has high catalytic activity, and can catalyze the reductive amination of carbonyl compounds and the hydrogen amination of ketone compounds at low temperatures, thereby saving energy and improving synthesis efficiency.

[0074] In some possible embodiments, the reaction time may be 0.5 to 25 hours, preferably 2 to 24 hours.

[0075] The reaction time described in the present disclosure refers to the time required for the reaction substrate to generate a primary amine, which can be 0.5 to 25 hours, preferably 2 to 24 hours, for example, 0.5 hours, 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, 24 hours or 25 hours, etc., without specific limitation. The cobalt-based catalyst provided in the present disclosure has high catalytic activity, and can catalyze the reductive amination of carbonyl compounds and the hydrogen amination of ketone compounds in a short time, thereby shortening the reaction time and improving the synthesis efficiency.

[0076] In some possible embodiments, a batch reaction process or a continuous reaction process can be used to synthesize primary amines. The reactor used in the batch reaction process can include a batch reactor, a fluidized bed and a slurry bed. The reactor used in the continuous reaction process can include a fixed bed and a moving bed.

[0077] The process provided in the present disclosure for preparing primary amines in a batch reactor using a carbonyl compound as a reaction substrate can be: preparing a prescribed amount of a carbonyl compound, a cobalt-based catalyst and a reaction medium, adding the carbonyl compound, the cobalt-based catalyst and the reaction medium into a batch reactor, and reacting for 0.5 to 5 hours under the conditions of an ammonia partial pressure of 0.3 to 0.8 MPa, a hydrogen pressure of 1 to 4 MPa and a reaction temperature of 70 to 150°C.

[0078] The process for preparing primary amines in a batch reactor using alcohol compounds as reaction substrates provided in the present disclosure can be: preparing a prescribed amount of alcohol compounds, a cobalt-based catalyst and a reaction medium, adding the alcohol compounds, the cobalt-based catalyst and the reaction medium into a batch reactor, and reacting for 15 to 25 hours under the conditions of an ammonia partial pressure of 0.3 to 0.8 MPa, a hydrogen pressure of 0.2 to 0.8 MPa and a reaction temperature of 160 to 200°C.

[0079] The present disclosure also provides a method for determining the conversion rate and yield when synthesizing primary amines. The determination method can be: performing qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A) on the reaction product, using an HP-5 chromatographic column, and the programmed temperature conditions of the chromatographic column are: maintaining at 50°C for 10 minutes, increasing the temperature to 250°C at a rate of 10°C / min, and maintaining at 250°C for 5 minutes.

[0080] In some possible embodiments, the cobalt-based catalyst includes a core-shell Co@CoO catalyst, wherein the core of the core-shell Co@CoO catalyst is cobalt and the shell is cobaltous oxide containing oxygen vacancies.

[0081] Figure 1 The XRD spectrum of the core-shell Co@CoO catalyst provided in the present disclosure is obtained by XRD diffractometer to obtain the crystal phase information of the core-shell Co@CoO catalyst. The diffraction peak of metal Co can be clearly identified in the figure, and Figure 1 The diffraction peak of CoO was also found, indicating that the core-shell Co@CoO catalyst prepared in the present invention contains both metallic Co phase and CoO phase.

[0082] Figure 2 This is a TEM image of the active phase of the core-shell Co@CoO catalyst provided by the present disclosure, and the morphology information of the core-shell Co@CoO catalyst is obtained by transmission electron microscopy. The core-shell structure of the core-shell Co@CoO catalyst can be clearly seen in the figure. The outer layer is the lattice fringes of CoO, and the inner layer is the lattice fringes of metal Co, indicating that the core-shell Co@CoO catalyst prepared by the present disclosure is a core-shell structure with CoO as the outer layer and Co as the inner layer.

[0083] The active phase of the core-shell Co@CoO catalyst described in the present disclosure is cobaltous oxide. It has been found that the main by-products of the amination reaction are diamine compounds generated by hydrogenation of the intermediate product Schiff base, and coupling compounds generated by the substrate aldol condensation. Usually in the process of generating by-products, the hydrogenation catalytic active center of the Schiff base is the metal center, and hydrogen is dissociated at the metal center and then undergoes a hydrogenation reaction; the substrate aldol condensation product is mainly carried out under the acidic center. Since the nucleophilicity of the primary amine generated first in the amination process is much higher than that of ammonia, the generation of Schiff base cannot be avoided, and conventional supported catalysts cannot inhibit the hydrogenation of Schiff base, resulting in poor reaction selectivity; and in the presence of ammonia, the active center on the catalyst surface is easily covered, resulting in poor reaction activity. The rate-determining step of the hydrogenation of alcohol compounds is the first step of the dehydrogenation process. Due to the presence of ammonia, the rate of dehydrogenation is greatly affected.

[0084] The present invention introduces cobaltous oxide active sites containing rich oxygen vacancies into a cobalt-based catalyst. Hydrogen dissociation can occur on the surface of the cobaltous oxide, and the catalyst has strong hydrogenation activity. Meanwhile, the cobaltous oxide on the surface can effectively inhibit the hydrogenation of the intermediate Schiff base. The cobalt-based catalyst has fewer surface acidic sites, which inhibits the aldol condensation side reaction of the carbonyl compound and improves the selectivity of the target product, the primary amine. Meanwhile, the cobaltous oxide on the surface of the cobalt-based catalyst of the present invention has a certain dehydrogenation ability, and can still dehydrogenate alcohol compounds in the presence of ammonia, and carry out subsequent amination reaction. Moreover, the cobaltous oxide on the surface can also inhibit the hydrogenation of the intermediate Schiff base and improve the yield of the primary amine.

[0085] In some possible embodiments, the method for preparing the core-shell Co@CoO catalyst includes preparing a precipitate from a cobalt source and a precipitant by a precipitation method, then optionally calcining the precipitate to obtain the precursor, and then optionally reducing the precursor to obtain the core-shell Co@CoO catalyst.

[0086] The precipitation method described in the present disclosure has the conventional interpretation in the art and can be carried out according to the existing precipitation method in the art, as long as the cobalt source and the precipitant can be co-precipitated to obtain a precipitate, which will not be described in detail here.

[0087] Preferably, the amount of the cobalt source used is such that the content of the active component in the prepared core-shell type Co@CoO catalyst meets the required corresponding content.

[0088] Preferably, the present disclosure has no limitation on the specific type of the cobalt source, as long as the core-shell Co@CoO catalyst can be prepared by the above method; more preferably, the cobalt source may include at least one of a salt, an ester and a complex containing the cobalt element, the salt may include at least one of a nitrate, an acetate and a chloride, and the complex may be any existing complex containing the cobalt element, which will not be repeated here; further preferably, the cobalt source may be selected from at least one of cobalt nitrate, cobalt acetate, cobalt carbonyl and cobalt chloride.

[0089] Preferably, the present disclosure has no limitation on the specific type of the precipitant, as long as it can be co-precipitated with the cobalt source; more preferably, the precipitant may include at least one of an amide, a base and a salt that can be co-precipitated with the cobalt source; further preferably, the precipitant may be selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate and urea.

[0090] Preferably, the calcination temperature may be 400-450° C.; for example, it may be 400° C., 420° C. or 450° C., etc., without specific limitation.

[0091] Preferably, the volume fraction of hydrogen in the reducing gas may be 5 to 30%, preferably 5 to 15%.

[0092] In the present disclosure, reducing gas refers to the gas used to reduce the precursor, and the reducing gas is a mixed gas of hydrogen and argon. The volume fraction of hydrogen refers to the volume percentage of hydrogen in the mixed gas, which can be 5-30%, preferably 5-15%. For example, it can be 5%, 10%, 15%, 20%, 25% or 30%, etc., without specific limitation.

[0093] Preferably, the flow rate of the reducing gas can be 10 to 100 ml / min, more preferably 10 to 40 ml / min; for example, it can be 10 ml / min, 30 ml / min, 40 ml / min, 60 ml / min, 80 ml / min or 100 ml / min, etc., without specific limitation.

[0094] Preferably, the reduction temperature may be 100 to 400°C, more preferably 200 to 350°C.

[0095] In the present disclosure, reduction temperature refers to the temperature when the precursor is reduced by reducing gas, which can be 100-400°C, preferably 200-350°C, for example, 100°C, 200°C, 225°C, 250°C, 275°C, 300°C, 350°C or 400°C, etc., without specific limitation.

[0096] Preferably, the reduction time may be 1 to 6 hours, more preferably 1 to 3 hours.

[0097] In the present disclosure, reduction time refers to the time for reducing the precursor using a reducing gas, and the time may be 1 to 6 hours, preferably 1 to 3 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, etc., without specific limitation.

[0098] The method for preparing a core-shell Co@CoO catalyst by a precipitation method provided in the present disclosure may include: co-precipitating a cobalt source and a precipitant by a precipitation method to obtain a precipitate, calcining the precipitate at 400-450° C. to obtain a precursor, and reducing the precursor in a reducing gas with a flow rate of 10-100 ml / min and a volume fraction of hydrogen of 5-30% for 1-6 hours to obtain a core-shell Co@CoO catalyst.

[0099] In some possible embodiments, the method for preparing the core-shell Co@CoO catalyst may include preparing the precursor by a high-temperature thermal decomposition method, and then optionally reducing the precursor to obtain the core-shell Co@CoO catalyst.

[0100] The high-temperature thermal decomposition method described in the present disclosure has the conventional interpretation in the art and can be carried out according to the existing high-temperature thermal decomposition method in the art, as long as the precursor can be prepared, and will not be described in detail here.

[0101] Preferably, the amount of the cobalt source used is such that the content of the active component in the prepared core-shell type Co@CoO catalyst meets the required corresponding content.

[0102] Preferably, the present disclosure has no limitation on the specific type of the cobalt source, as long as the core-shell Co@CoO catalyst can be prepared by the above method; more preferably, the cobalt source may include at least one of a salt, an ester and a complex containing the cobalt element, the salt may include at least one of a nitrate, an acetate and a chloride, and the complex may be any existing complex containing the cobalt element, which will not be described in detail here; further preferably, the cobalt source may be selected from at least one of cobalt nitrate and cobalt acetate.

[0103] Preferably, the conditions of the high temperature thermal decomposition method include: the calcination temperature can be 300-600°C, more preferably 400-550°C; for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C, etc., without specific limitation.

[0104] Preferably, the volume fraction of hydrogen in the reducing gas may be 5-30%, more preferably 5-15%; for example, it may be 5%, 8%, 10%, 12%, 15%, 20%, 25% or 30%, etc., without specific limitation.

[0105] Preferably, the flow rate of the reducing gas may be 10 to 100 ml / min, more preferably 10 to 40 ml / min; for example, it may be 10 ml / min, 30 ml / min, 40 ml / min, 50 ml / min, 60 ml / min, 80 ml / min or 100 ml / min, etc., without limitation.

[0106] Preferably, the reduction temperature may be 100-400°C, more preferably 200-350°C; for example, it may be 100°C, 150°C, 200°C, 225°C, 250°C, 275°C, 300°C, 350°C, 375°C or 400°C, etc., without specific limitation.

[0107] Preferably, the reduction time may be 1 to 6 hours, more preferably 1 to 3 hours; for example, it may be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, etc., without specific limitation.

[0108] The method for preparing a core-shell Co@CoO catalyst by high-temperature thermal decomposition provided by the present disclosure may include: calcining a cobalt source at 300-600° C. to obtain a precursor, reducing the precursor in a reducing gas with a flow rate of 10-100 ml / min and a hydrogen volume fraction of 5-30% for 1-6 hours to obtain a core-shell Co@CoO catalyst.

[0109] In some possible embodiments, the cobalt-based catalyst may include a supported cobalt-based catalyst; the present disclosure has no limitation on the specific type of the carrier, as long as it can support a cobalt source; preferably, the carrier of the supported cobalt-based catalyst may include at least one of metal oxides, SiO2 and activated carbon.

[0110] The present disclosure has no limitation on the specific type of metal oxide, as long as it can load the cobalt source; preferably, the metal oxide may include at least one of Group IIIA metal oxides, Group IIA metal oxides, Group IVB metal oxides, lanthanide metal oxides and Group VIB metal oxides, and more preferably, the metal oxide is selected from at least one of Al2O3, MgO, MgAl2O4, TiO2, ZrO2, CeO2 and MoO3.

[0111] In some possible embodiments, the method for preparing the supported cobalt-based catalyst may include co-precipitating a cobalt source and a carrier precursor to obtain a precipitate, then optionally calcining the precipitate to obtain the precursor, and finally optionally reducing the precursor to obtain the supported cobalt-based catalyst.

[0112] The co-precipitation described in the present disclosure has the conventional interpretation in the art and can be carried out according to the existing co-precipitation method in the art, as long as the cobalt source can be introduced into the carrier, which will not be described in detail here.

[0113] Preferably, the amount of the cobalt source used is such that the content of the active component in the prepared supported cobalt-based catalyst meets the required corresponding content.

[0114] The present disclosure has no limitation on the specific type of the cobalt source, as long as the supported cobalt-based catalyst can be prepared by the above method; preferably, the cobalt source may include at least one of a salt, an ester and a complex containing the cobalt element, the salt may include at least one of a nitrate, an acetate and a chloride, the complex may be any existing complex containing the cobalt element, which will not be described in detail here; more preferably, the cobalt source may be selected from cobalt chloride.

[0115] Preferably, the carrier precursor includes at least one of a salt of a Group IIIA metal, a salt of a Group IIA metal, a salt of a Group IVB metal, a salt of a lanthanide metal, and a salt of a Group VIB metal.

[0116] The present disclosure has no limitation on the specific type of carrier precursor, as long as a carrier-loaded cobalt source can be prepared; preferably, the carrier precursor may include at least one of salts of Group IIIA metals, salts of Group IIA metals, salts of Group IVB metals, salts of lanthanide metals and salts of Group VIB metals, and the salt may be at least one of nitrates, phosphates, sulfates and carbonates, etc.; more preferably, the carrier precursor is selected from magnesium nitrate, aluminum nitrate or cerium nitrate.

[0117] Preferably, the calcination temperature may be 350-450°C; for example, it may be 350°C, 380°C, 400°C, 420°C or 450°C, etc., without specific limitation.

[0118] Preferably, the volume fraction of hydrogen in the reducing gas may be 5-30%, preferably 5-15%; for example, it may be 5%, 10%, 15%, 20%, 25% and 30%, etc., without specific limitation.

[0119] Preferably, the flow rate of the reducing gas may be 10 to 100 ml / min, preferably 10 to 40 ml / min; for example, it may be 10 ml / min, 20 ml / min, 40 ml / min, 60 ml / min or 80 ml / min, etc., without specific limitation.

[0120] Preferably, the reduction temperature may be 100-400°C, preferably 200-350°C; for example, it may be 100°C, 200°C, 250°C, 275°C, 300°C, 350°C or 400°C, etc., without specific limitation.

[0121] Preferably, the reduction time may be 1 to 6 hours, preferably 1 to 3 hours; for example, it may be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, etc., without specific limitation.

[0122] In some possible embodiments, the method for preparing the supported cobalt-based catalyst may include preparing a carrier, then loading a cobalt source on the carrier by an equal volume impregnation method, an excess impregnation method, or a precipitation deposition method, and optionally calcining to obtain a precursor, and finally optionally reducing the precursor to obtain the supported cobalt-based catalyst.

[0123] The equal volume impregnation method, excess impregnation method or precipitation deposition method described in the present disclosure has the conventional meaning in the art and can be carried out according to the existing equal volume impregnation method, excess impregnation method or precipitation deposition method in the art, as long as the cobalt source and the carrier can be impregnated, which will not be repeated here.

[0124] Preferably, the amount of the cobalt source used is such that the content of the active component in the prepared supported cobalt-based catalyst meets the required corresponding content.

[0125] The present disclosure has no limitation on the type of the cobalt source, as long as the supported cobalt-based catalyst can be obtained by the above method; preferably, the cobalt source may include at least one of a salt, an ester and a complex containing the cobalt element, and more preferably, the cobalt source may be selected from cobalt chloride.

[0126] Preferably, the calcination temperature may be 350-450°C, for example, 350°C, 380°C, 400°C, 410°C, 420°C or 450°C, etc., without specific limitation.

[0127] Preferably, the volume fraction of hydrogen in the reducing gas may be 5-30%, preferably 5-15%; for example, it may be 5%, 10%, 15%, 20%, 27% and 30%, etc., without specific limitation.

[0128] Preferably, the flow rate of the reducing gas may be 10 to 100 ml / min, preferably 10 to 40 ml / min; for example, it may be 10 ml / min, 20 ml / min, 30 ml / min, 40 ml / min, 60 ml / min or 100 ml / min, etc., without specific limitation.

[0129] Preferably, the reduction temperature may be 100-400°C, preferably 200-350°C; for example, it may be 100°C, 200°C, 225°C, 250°C, 275°C, 300°C, 350°C or 400°C, etc., without specific limitation.

[0130] Preferably, the reduction time may be 1 to 6 hours, preferably 1 to 3 hours; for example, it may be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, etc., without specific limitation.

[0131] The method for efficiently synthesizing primary amines provided by the present disclosure has high catalytic activity, can realize the reductive amination of carbonyl compounds and the hydrogen amination of alcohol compounds under low temperature and short time conditions, obtain primary amines with high yield, and has a wide range of applicable substrates. The obtained primary amines can be used as raw materials for the production of polymers, drugs, dyes and surfactants, and have high added value; secondly, the cobalt-based catalyst has magnetism, which is convenient for the separation and recycling of the catalyst, and has good industrial application prospects; thirdly, the cobalt-based catalyst has low cost, which can effectively reduce the cost of industrialization.

[0132] The present disclosure will be described in detail below through examples.

[0133] In the following examples, the process of preparing primary amine by reductive amination with aldehydes and ketones as reaction substrates and using a batch reactor under the action of a cobalt-based catalyst comprises: adding 0.18 g of reaction substrate, 0.02 g of cobalt-based catalyst and 5 mL of reaction medium into a 50 mL batch reactor, reacting for 0.5 to 5 hours under the conditions of 0.3 to 0.8 MPa of ammonia partial pressure, 1 to 4 MPa of hydrogen partial pressure and 70° C. to 150° C. The reaction product is subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A), using an HP-5 chromatographic column, and the programmed temperature conditions of the chromatographic column are: maintaining at 50° C. for 10 mins, heating to 250° C. at a heating rate of 10° C. / min, and maintaining at 250° C. for 5 mins.

[0134] In the following examples, alcohol compounds are used as reaction substrates, and a batch reactor is used. The process of preparing primary amines by hydrogen amination under the action of a cobalt-based catalyst includes: adding 0.18 g of reaction substrate, 0.04 g of catalyst and 5 mL of reaction medium into a 50 mL batch reactor, and reacting for 15 to 25 hours under the conditions of an ammonia partial pressure of 0.3 to 0.8 MPa, a hydrogen partial pressure of 0.2 to 0.8 MPa, and a temperature of 160 to 200° C. The reaction product is subjected to qualitative analysis by gas chromatography-mass spectrometry (GC-MS Agilent 7890A-5975C) and quantitative analysis by gas chromatography (GC Agilent 7890A), using an HP-5 chromatographic column, and the programmed temperature conditions of the chromatographic column are: maintaining 50° C. for 10 mins, heating to 250° C. at a heating rate of 10° C. / min, and maintaining at 250° C. for 5 mins.

[0135] In the following examples, the process of preparing a core-shell Co@CoO catalyst by precipitation method includes: dissolving 60mmol of cobalt source in 200ml of deionized water as solution A; dissolving 69mmol of precipitant in 200ml of deionized water as solution B. In a 65℃ water bath, slowly drip solution B into solution A while stirring vigorously until the pH of the mixed solution is 9, and then stop dripping solution B. Continue stirring in a 65℃ water bath for 1h, and then stand at room temperature for 12h. Filter, wash with deionized water several times, put in a 100℃ oven to dry overnight, grind, and calcine in a 450℃ muffle furnace for 4h to obtain a precursor Co3O4; then reduce the precursor Co3O4 at a temperature of 225℃ to 400℃, using a reducing gas with a volume fraction of H2 of 5-10% and a flow rate of 10-40ml / mim for 1-3h to obtain.

[0136] Examples 1-7

[0137] In Examples 1-7, when the core-shell Co@CoO catalyst is prepared by precipitation method, the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, and the reduction temperature is 300°C. The difference between Examples 1-7 is that the volume fraction of hydrogen in the reducing gas used, the flow rate of the reducing gas, and the reduction time are different.

[0138] In Examples 1-7, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a core-shell Co@CoO catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 1.

[0139] Table 1

[0140]

[0141] Embodiment 8-13

[0142] In Example 8-13, when the core-shell type Co@CoO catalyst is prepared by precipitation method: the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2h. The difference between Examples 8-13 is that the reduction temperature used is different. Specifically, the reduction temperatures of Examples 8-13 are 225°C, 250°C, 275°C, 300°C, 350°C, and 400°C, respectively, and the obtained core-shell type Co@CoO catalysts are Co@CoO-P-225, Co@CoO-P-250, Co@CoO-P-275, Co@CoO-P-300, Co@CoO-P-350, and Co@CoO-P-400, respectively.

[0143] In Examples 8-13, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a core-shell Co@CoO catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 2.

[0144] Table 2

[0145]

[0146]

[0147] *P represents a cobalt-based catalyst prepared by a precipitation method.

[0148] Examples 14-18

[0149] In Examples 14-18, when a core-shell Co@CoO catalyst is prepared by a high-temperature thermal decomposition method: 5 g of cobalt nitrate is used as a cobalt source, and high-temperature calcination is carried out in a muffle furnace at 500°C for 5 hours to obtain a precursor Co3O4; when reducing the precursor Co3O4 in Examples 14-18, the volume fraction of hydrogen in the reducing gas used is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h. The difference between Examples 14-18 is that the reduction temperature used is different. Specifically, the reduction temperatures of Examples 14-18 are 225°C, 250°C, 275°C, 300°C, 350°C, and 400°C, respectively, and the obtained core-shell Co@CoO catalysts are Co@CoO-P-225, Co@CoO-P-250, Co@CoO-P-275, Co@CoO-P-300, Co@CoO-P-350, and Co@CoO-P-400, respectively.

[0150] In Examples 14-18, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a core-shell Co@CoO catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 3.

[0151] Table 3

[0152]

[0153] *D indicates a cobalt-based catalyst prepared by high-temperature thermal decomposition method.

[0154] The results in Table 3 show that the cobalt-based catalysts prepared by high-temperature thermal decomposition method all have high catalytic activity.

[0155] Examples 19-21

[0156] In Examples 19-21, when the core-shell type Co@CoO catalyst is prepared by precipitation method: the precipitant is sodium carbonate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 hours. The difference between Examples 19-21 is that different cobalt sources are used. Specifically, the cobalt sources used in Examples 19-21 are cobalt acetate, cobalt chloride and cobalt carbonyl, respectively.

[0157] In Examples 19-21, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a core-shell Co@CoO catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 4.

[0158] Table 4

[0159]

[0160] The results in Table 4 show that the cobalt-based catalysts prepared using a variety of cobalt sources all have high catalytic activity.

[0161] Examples 22-26

[0162] In Examples 22-26, when the core-shell Co@CoO catalyst is prepared by precipitation method: the cobalt source is cobalt nitrate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h. The difference between Examples 22-26 is that different precipitants are used. Specifically, the precipitants of Examples 22-26 are sodium hydroxide, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and urea, respectively.

[0163] In Examples 22-26, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a core-shell Co@CoO catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 5.

[0164] Table 5

[0165]

[0166] The results in Table 5 show that the cobalt-based catalysts prepared using a variety of precipitants all have high catalytic activity.

[0167] Examples 27-35

[0168] When preparing the supported cobalt-based catalyst in Examples 27-35: the cobalt chloride solution is impregnated on the carrier by an equal volume impregnation method, and the loading amount is 10%, wherein the loading amount of 10% means that the mass percentage of cobalt in the total amount of the supported cobalt-based catalyst is 10%. After drying in a 100°C oven for 12 hours, the catalyst precursor is placed in a nitrogen atmosphere for high-temperature treatment. The specific process is: 1g of the precursor is heated from room temperature to 450°C in a quartz tube for 2 hours, maintained for 4 hours, and automatically cooled; the cooled catalyst is then reduced in a H2 / Ar atmosphere with a H2 volume fraction of 10%. The specific process is: 1g of the precursor is heated from room temperature to 250°C in a quartz tube for 1 hour, maintained for 2 hours, and the gas flow rate is 60mL / min; the difference between Examples 27-35 lies in the different carriers used. Specifically, the carriers used in Examples 27-35 are Al2O3, MgO, MgAl2O4, TiO2, ZrO2, CeO2, MoO3, SiO2, and activated carbon, respectively.

[0169] In Examples 27-35, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of a supported cobalt-based catalyst, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90° C., the reaction time is 4 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 6.

[0170] Table 6

[0171]

[0172]

[0173] The results in Table 6 show that the supported cobalt-based catalysts prepared using a variety of carriers also have high catalytic activity.

[0174] Examples 36-59

[0175] When preparing the core-shell Co@CoO catalyst in Examples 36-59: the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h.

[0176] In Examples 36-59, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of Co@CoO-P-300, and a batch reactor is used to obtain the reaction product cyclopentylamine; the difference between Examples 36-59 is that the reaction medium, ammonia partial pressure, hydrogen partial pressure, reaction temperature and reaction time are different. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 7.

[0177] Table 7

[0178]

[0179]

[0180] The results in Table 7 show that the cobalt-based catalyst disclosed in the present invention can catalyze the synthesis of primary amines from reaction substrates under conditions of lower temperature, shorter time, multiple reaction media, and lower ammonia partial pressure and hydrogen partial pressure, thereby improving the reaction substrate conversion rate and product yield.

[0181] Examples 60-84

[0182] The difference between Examples 60-84 is that different methods are used to prepare the cobalt-based catalysts.

[0183] In Examples 60-84, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is cyclopentanone, the reaction medium is methanol, and the feed space velocity of cyclopentanone is 10-50 h -1 , the catalyst dosage is 0.05g, the hydrogen flow rate is 20-50mL / h, the hydrogen partial pressure is 0.5-2MPa, the ammonia flow rate is 20-40ml / h, the ammonia partial pressure is 0.3-0.6MPa, the temperature is 50°C-200°C, and a continuous fixed bed is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 8.

[0184] Table 8

[0185]

[0186]

[0187] The results in Table 8 show that the cobalt-based catalysts prepared by different methods can all catalyze the synthesis of primary amines from carbonyl compounds.

[0188] Examples 85-102

[0189] The difference between Examples 85-102 is that different methods are used to prepare the cobalt-based catalysts.

[0190] In Examples 85-102, when a cobalt-based catalyst is used to catalyze the preparation of primary amines, the reaction substrate is 0.18 g of cyclopentanol, the catalyst dosage is 0.04 g, the reaction medium is 5 ml of p-xylene, the ammonia partial pressure is 0.6 MPa, the hydrogen partial pressure is 0.2 MPa, the reaction temperature is 180° C., the reaction time is 24 h, and a batch reactor is used to obtain the reaction product cyclopentylamine. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 9.

[0191] Table 9

[0192]

[0193]

[0194] The results in Table 9 show that the cobalt-based catalysts prepared by different methods can all catalyze the synthesis of primary amines from alcohol compounds.

[0195] Examples 103-122

[0196] When preparing the core-shell Co@CoO catalyst in Examples 103-122: the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h.

[0197] In Example 103-122, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the catalyst is 0.02g of Co@CoO-P-300, the reaction medium is 5ml of methanol, the ammonia partial pressure is 0.3MPa, the hydrogen partial pressure is 2MPa, the reaction temperature is 100°C, the reaction time is 4h, and an intermittent reactor is used; the difference between Example 103-111 is that the reaction substrates are different, specifically, the reaction substrates of Example 103-111 are acetone, propionaldehyde, butanone, butyraldehyde, 2-pentanone, valeraldehyde, 4-heptanone, octanal, 2-octanone, 5-nonanone, benzaldehyde, phenylacetaldehyde, phenylpropionaldehyde, acetophenone, 4-chloroacetophenone 2-bromoacetophenone, 2-methoxyphenylacetophenone, 2-naphthaldehyde, 4-hydroxyphenylacetophenone, 4-methoxybenzaldehyde, and benzophenone. The conversion rate of the reaction substrate and the yield of the reaction product in each example were determined, and the results are shown in Table 10.

[0198] Table 10

[0199]

[0200]

[0201] The results in Table 10 indicate that the cobalt-based catalyst disclosed in the present invention can catalyze the synthesis of primary amines from aliphatic aldehydes and ketones and aromatic aldehydes and ketones, has a wide range of applicable substrates, and increases the pathways for the synthesis of primary amines.

[0202] Examples 123-128

[0203] When preparing the core-shell Co@CoO catalyst in Examples 123-128: the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h.

[0204] In Examples 123-128, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the catalyst is 0.04 g of Co@CoO-P-300, the reaction medium is 5 ml of p-xylene, the ammonia partial pressure is 0.6 MPa, the hydrogen partial pressure is 0.2 MPa, the reaction temperature is 180°C, the reaction time is 24 h, and an intermittent reactor is used; the difference between Examples 123-128 is that the reaction substrates are different, specifically, the reaction substrates of Examples 123-128 are propanol, n-butanol, cyclopentanol, cyclohexanol, 1-octanol, and benzyl alcohol, respectively. The conversion rate of the reaction substrate and the yield of the reaction product in each example were measured, and the results are shown in Table 11.

[0205] Table 11

[0206]

[0207] The results in Table 11 indicate that the cobalt-based catalyst in the present disclosure is capable of catalyzing the synthesis of primary amines from aliphatic alcohols and aromatic alcohols, has a wide range of applicable substrates, and increases the pathways for the synthesis of primary amines.

[0208] Examples 129-153

[0209] When preparing the core-shell Co@CoO catalyst in Examples 129-153: the cobalt source is cobalt nitrate, the precipitant is sodium carbonate, the calcination temperature is 450°C, the reduction temperature is 300°C, the volume fraction of hydrogen in the reducing gas is 10%, the flow rate of the reducing gas is 30 ml / min, and the reduction time is 2 h.

[0210] In Examples 129-153, when a cobalt-based catalyst is used to catalyze the preparation of primary amines: the reaction substrate is 0.18 g of cyclopentanone, the catalyst is 0.02 g of Co@CoO-P-300, the reaction medium is 5 ml of methanol, the ammonia partial pressure is 0.3 MPa, the hydrogen partial pressure is 2 MPa, the reaction temperature is 90°C, the reaction time is 2 h, and an intermittent reactor is used to obtain the reaction product cyclopentylamine; the core-shell Co@CoO catalyst in Examples 129-153 is recycled. Specifically, after the reaction in the previous experiment, the catalyst is repeatedly washed three times with methanol, dried in an oven at 60°C, and repeatedly put into the next experiment. The conversion rate of the reaction substrate and the yield of the reaction product in each example were determined, and the results are shown in Table 12.

[0211] Table 12

[0212]

[0213]

[0214] The results in Table 12 show that the cobalt-based catalyst has magnetic properties, which facilitates the separation and recycling of the catalyst and has good prospects for industrial application.

[0215] Comparative Examples 1-6

[0216] The catalyst used in Comparative Examples 1-6 is a copper-based catalyst, and the methods for preparing the copper-based catalyst in Comparative Examples 1-6 are respectively the same as the methods for preparing the cobalt-based catalyst in Examples 8-13. The process of preparing primary amines using the copper-based catalyst in Comparative Examples 1-6 is the same as the process of preparing primary amines using the cobalt-based catalyst in Examples 8-13. The conversion rate of the reaction substrate and the yield of the reaction product in Comparative Examples 1-6 were measured, and the results are shown in Table 13.

[0217] Table 13

[0218]

[0219] By comparing Examples 8-13 and Comparative Examples 1-6, it can be seen that the cobalt-based catalyst has higher catalytic activity, selectivity and stability.

[0220] Comparative Examples 7-8

[0221] The difference between Comparative Examples 7-8 and Examples 8-13 is only the reduction temperature, which is 90° C. for Comparative Example 7 and 410° C. for Comparative Example 8. The conversion rate of the reaction substrate and the yield of the reaction product in Comparative Examples 7-8 were measured, and the results are shown in Table 14.

[0222] Table 14

[0223]

[0224] By comparing Examples 8-13 and Comparative Examples 7-8, it can be seen that when the reduction temperature is 100-400° C. during the preparation of the cobalt-based catalyst, the prepared cobalt-based catalyst has a higher catalytic activity.

[0225] Comparative Examples 9-10

[0226] The difference between Comparative Examples 9-10 and Example 36 is only the reaction temperature, which is 65° C. for Comparative Example 9 and 210° C. for Comparative Example 10. The conversion rate of the reaction substrate and the yield of the reaction product in Comparative Examples 9-10 were measured, and the results are shown in Table 15.

[0227] Table 15

[0228]

[0229] By comparing Example 36 and Comparative Examples 9-10, it can be seen that when a cobalt-based catalyst is used to catalyze the reaction of synthesizing primary amines, the catalytic effect is better when the reaction temperature is greater than or equal to 70°C, but the catalytic effect does not improve significantly after the reaction temperature is higher than 200°C. Based on industrial cost considerations, when the reaction temperature is controlled at 70-200°C, it can have better catalytic activity and save industrial costs.

[0230] The method for efficiently synthesizing primary amines provided by the present disclosure has high catalytic activity, can realize the reductive amination of carbonyl compounds and the hydrogen amination of alcohol compounds under low temperature and short time conditions, obtain primary amines with high yield, and has a wide range of applicable substrates. The obtained primary amines can be used as raw materials for the production of polymers, drugs, dyes and surfactants, and have high added value; secondly, the cobalt-based catalyst has magnetism, which is convenient for the separation and recycling of the catalyst, and has good industrial application prospects; thirdly, the cobalt-based catalyst has low cost, which can effectively reduce the cost of industrialization.

[0231] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present disclosure as described above, which are not provided in detail for the sake of simplicity.

[0232] The embodiments of the present disclosure are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for efficiently synthesizing primary amines, the method comprising: using a carbonyl compound or an alcohol compound as a reaction substrate, liquid ammonia or an alcohol solution of ammonia as a nitrogen source, and hydrogen as a hydrogen source, and reacting in a reaction medium under the catalysis of a cobalt-based catalyst to obtain a primary amine; in, The cobalt-based catalyst includes a core-shell Co@CoO catalyst, wherein the core of the core-shell Co@CoO catalyst is cobalt and the shell is cobaltous oxide containing oxygen vacancies; The mass ratio of the reaction substrate to the cobalt-based catalyst is 1:(0.01-2); The mass ratio of the reaction substrate to the reaction medium is 1:(1-60).

2. The method according to claim 1, wherein: The carbonyl compound is an aliphatic hydrocarbon aldehyde or ketone or an aromatic aldehyde or ketone; And / or, the alcohol compound is a fatty alcohol or an aromatic alcohol; And / or, the alcohol solution of ammonia is selected from at least one of ammonia methanol, ammonia ethanol and ammonia isopropanol; And / or, the reaction medium is selected from an organic solvent, and the organic solvent is selected from at least one of methanol, ethanol, isopropanol, ethylene glycol dimethyl ether, tetrahydrofuran, toluene and p-xylene.

3. The method according to claim 1, wherein: The mass ratio of the reaction substrate to the reaction medium is 1:(1-30); and / or, the concentration of the alcoholic ammonia solution is 2M to 7M; And / or, the pressure of the liquid ammonia after gasification is 0.1-1 MPa; And / or, the pressure of the hydrogen is 0.5-5 MPa; And / or, the reaction temperature is 70-200°C; And / or, the reaction time is 0.5 to 25 hours.

4. The method according to claim 1, wherein: The method for preparing the core-shell Co@CoO catalyst comprises preparing a precursor, and then optionally reducing the precursor to obtain the core-shell Co@CoO catalyst; the volume fraction of hydrogen in the reducing gas is 5 to 30%, and / or, the flow rate of the reducing gas is 10 to 100 ml / min; and / or, the reduction temperature is 100 to 400° C.; And / or, the reduction time is 1 to 6 hours.

5. The method according to claim 4, The volume fraction of hydrogen in the reducing gas is 5 to 15%; and / or, the flow rate of the reducing gas is 10-40 ml / min; and / or, the reduction temperature is 200 to 350° C.; And / or, the reduction time is 1 to 3 hours.

6. The method according to claim 5, wherein: The method for preparing the precursor comprises preparing a precipitate by a precipitation method using a cobalt source and a precipitant, and then optionally calcining the precipitate to obtain the precursor; The cobalt source is selected from at least one of a salt, an ester and a complex containing the cobalt element; and / or, the precipitating agent is selected from at least one of an amide, a base and a salt capable of co-precipitating with the cobalt source; And / or, the calcination temperature is 400-450°C.

7. The method according to claim 5, wherein: The method for preparing the precursor comprises preparing the precursor by using a high temperature thermal decomposition method on a cobalt source; The cobalt source is selected from at least one of a salt, an ester and a complex containing the cobalt element; And / or, the conditions of the high temperature thermal decomposition method include: the calcination temperature is 300-600°C.

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