Method for preparing 1, 3-cyclohexanedimethylamine through one-step hydrogenation of isophthalonitrile

Abstract

The invention discloses a method for preparing 1, 3-cyclohexanedimethylamine through one-step hydrogenation of isophthalonitrile. The invention aims to develop a strategy for synthesizing 1, 3-cyclohexanedimethylamine by using a novel, simple and efficient heterogeneous metal cobalt catalyst to catalyze and reduce 1, 3-isophthalonitrile. The reaction system is composed of 1, 3-isophthalonitrile, a heterogeneous cobalt catalyst, a solvent and hydrogen; the reaction temperature is 80-160 DEG C, the reaction pressure is 1-10 MPa, the molar ratio of hydrogen to isophthalonitrile is 10-200, and the weight ratio of isophthalonitrile to catalyst to solvent is 1: 0.3: 9. Isophthalonitrile can be converted into 1, 3-cyclohexanedimethylamine with high activity and high selectivity in a fixed bed reactor under the action of a catalyst. The catalyst has the advantages of simple preparation, good cycling stability, high yield and the like. The process aims to improve the yield and the product purity of the 1, 3-cyclohexanedimethylamine, reduce the energy consumption in the production process of the 1, 3-cyclohexanedimethylamine, and realize the breakthrough of the production technology of the 1, 3-cyclohexanedimethylamine.

Description

Technical Field

[0001] The present invention relates to a catalyst for preparing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile, a preparation method and an application thereof, and belongs to the field of hydrogenation catalysts. A multiphase single-atom cobalt catalyst (Co / CeO2-S) prepared by an impregnation method has suitable pores, and under the condition of no additive addition, combined with a unique catalyst preparation process, the catalyst has the characteristics of high activity, difficult pore blockage, long service life, etc. The isophthalonitrile conversion rate reaches 99.5%, and the 1,3-cyclohexyldimethylamine selectivity reaches 92.4%. At the same time, the catalyst preparation method has a simple process and low cost, and is suitable for industrial production. Technical Background

[0002] As important fine chemical and organic chemical intermediates, alicyclic amine compounds are widely used in rubber additives, plastic processing textiles, pharmaceuticals, anti-corrosion, papermaking and food additives. In addition, alicyclic amines can also be used as raw materials for the synthesis of isocyanates. Since alicyclic isocyanates do not contain benzene rings in their molecules, they are particularly stable to light and can therefore be used to prepare polyurethane products with excellent yellowing resistance. With the increase in the variety of polyurethane products and the improvement of their quality requirements, the demand for alicyclic isocyanates is also increasing. Therefore, the development of efficient alicyclic amine production processes is of great value.

[0003] 1,3-cyclohexanedimethylamine is an important alicyclic amine product, also known as 1,3-diaminomethylcyclohexane or 1,3-bis(aminomethyl)cyclohexane, and its English name is 1,3-cyclohexanebis(methylamine). 1,3-cyclohexanedimethylamine is the most commonly used amine curing agent because of its low unsaturation, low viscosity, high reactivity, strong chemical resistance, and good curing effect. Especially after m-phenylenediamine was listed as a toxic chemical, 1,3-BAC, as its substitute, is also rapidly increasing in demand in the field of epoxy resins. At the same time, as an important fine chemical and organic chemical intermediate, 1,3-cyclohexanedimethylamine can be widely used in the synthesis of polyurethane intermediates, composite materials, and stone materials.

[0004] 1,3-cyclohexylenediamine is prepared by hydrogenating meta-phenylenediamine, or by directly hydrogenating isophthalonitrile. In the process of direct hydrogenation of isophthalonitrile, an intermediate step of hydrogenation to generate imine is experienced, and the reaction activity of imine is very high, and it is easy to further react with reaction intermediates and products, and generate a variety of high-boiling by-products through condensation, aminolysis, cross-linking and other reactions. Therefore, the yield of 1,3-cyclohexylenediamine by direct hydrogenation of isophthalonitrile is low. The catalyst for catalytic hydrogenation of isophthalonitrile is mainly precious metal Raney Ru and the like. Among them, USP 6,045,920, 6,215,030 and 6,245,920 disclose patents for converting isophthalonitrile into 1,3-cyclohexylenediamine using Raney Ru as a hydrogenation catalyst, but the yield is only 58%. Japanese Patent 42-26783 discloses the hydrogenation of m-phenylenediamine to 1,3-cyclohexylenediamine using Ru as a catalyst and water or aqueous organic acid as a solvent, but the selectivity of the target product is low. Japanese Patent 51-7659 reports that m-phenylenediamine can be highly selectively converted to cyclohexylenediamine under Ru catalyst and ammonia conditions. Japanese Patent 61-13461 discloses a patent for the hydrogenation of m-phenylenediamine to cyclohexylenediamine in the presence of Ru catalyst and alkali metal or alkaline earth metal aqueous solution, and the yield is high. USP 5,741,928 reports that in the presence of organic amines, m-phenylenediamine is highly selectively converted to 1,3-cyclohexylenediamine under the action of Ru / A12O3 catalyst.

[0005] Based on the results and deficiencies of the above related patents, we invented a new type of multiphase single-atom cobalt-based catalyst (Co / CeO2-S) for catalyzing the one-step hydrogenation of isophthalonitrile to synthesize 1,3-cyclohexyldimethylamine. The catalyst has the advantages of simple preparation, good cycle stability, and high yield. The process goal is to improve the yield and product purity of 1,3-cyclohexyldimethylamine, reduce the energy consumption of the 1,3-cyclohexyldimethylamine production process, and achieve a breakthrough in the production technology of 1,3-cyclohexyldimethylamine. Summary of the invention

[0006] The invention provides a novel multiphase single-atom cobalt-based catalyst (Co / CeO2-S) for catalyzing a method for synthesizing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile.

[0007] According to the present invention, a method for preparing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile is characterized in that the reaction system consists of 1,3-isophthalonitrile, a heterogeneous single-atom cobalt catalyst, a solvent, and hydrogen, the main product is 1,3-cyclohexyldimethylamine, and the reaction conditions are:

[0008] The reaction temperature is 80-160° C., the reaction pressure is 1-10 MPa, hydrogen / isophthalonitrile=0.001 (molar ratio), isophthalonitrile / catalyst / solvent=1:0.3:9 (weight ratio).

[0009] According to the present invention, the method for synthesizing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile uses isophthalonitrile as a raw material, tert-butyl alcohol as a solvent, and a hydrogen atmosphere. Under the action of a multiphase single-atom cobalt-based catalyst (Co / CeO2-S), the selectivity of 1,3-cyclohexyldimethylamine can reach 92.4%.

[0010] According to the present invention, the method for preparing the supported multi-phase single-atom cobalt catalyst is characterized in that the catalyst is prepared by impregnating a cerium dioxide (CeO2) carrier in a corresponding metal salt solution.

[0011] 1) Preparation of CeO2-S carrier: 5.0 g of Ce(NO3)3·6H2O was dissolved in 100 mL of deionized water, and the solution was adjusted to pH = 11.0 by adding NH4OH (3.4 M) under magnetic stirring at room temperature. The resulting gel mixture was washed with purified water, dried in an oven at 100° C. for 12 hours, and then calcined in a muffle furnace at 500° C. for 4 hours to obtain the CeO2-S carrier for use.

[0012] 2) Preparation of Co / CeO2-S (0.1wt% Co): 0.0013g CoCl2·6H2O and 0.5g CeO2-S were dispersed in 20mL of deionized water and magnetically stirred for 24h. The water was then evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 300°C, 400°C and 500°C under a flowing 10% H2 / N2 atmosphere. For other cobalt single atom catalysts, the preparation method was similar to that of the Co / CeO2-S catalyst, except that CeO2-S was replaced by the corresponding carrier.

[0013] The present invention develops a supported multiphase single-atom cobalt catalyst, which has the advantages of simple preparation, good cycle stability, no significant decrease in activity after more than 8 cycles, and high yield.

[0014] The catalyst can control the morphology of the carrier by changing the preparation method of cerium dioxide (CeO2) to prepare a series of carriers with different morphologies.

[0015] Among them, the cerium dioxide carrier with different morphologies may be one or more of CeO2-S, CeO2-P, CeO2-R, and CeO2-O.

[0016] The catalyst can be used to prepare other types of catalysts by replacing the cerium dioxide (CeO2) carrier;

[0017] Among them, the carrier may be one or more of TiO2, CeO2, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3, SiO2, and activated carbon.

[0018] The different types of metals loaded on the catalyst may affect the final catalytic performance;

[0019] Among them, the loaded metal may be one or more of Co, Mn, Ni, Ru, Pt, Fe, Pd, and Au.

[0020] According to the present invention, the reaction temperature of the method is 80-160°C, preferably 100-150°C, and most preferably 120-140°C.

[0021] According to the present invention, the reaction pressure of the method described is 1-10 MPa, preferably the reaction pressure is 3.0-8.0 MPa, and most preferably 4.0-6.0 MPa.

[0022] According to the present invention, in the method described, the molar ratio of H2 / m-xylylenediamine is 10-200, preferably 12-180, and most preferably 18-150.

[0023] According to the present invention, in the method described, isophthalonitrile / catalyst / solvent = 1:0.05-1.2:1-20 (weight ratio), preferably 1:0.2-0.9:5-12, and most preferably 1:0.1-0.5:5-12.

[0024] The catalytic performance of the present invention is related to the amount of the catalyst used. A too low amount will affect the activity of the catalytic reaction, and a too high amount will increase the cost of the catalyst; therefore, an appropriate amount needs to be selected. In order to ensure the activity of the catalyst while reducing the cost of the catalyst, the mass ratio of the catalyst to the substrate used is in the range of 0.05 to 1.2, and the preferred mass ratio is in the range of 0.2 to 0.9.

[0025] The reaction solvent is any one or more of toluene, acetonitrile, tert-amyl alcohol, tert-butanol, n-butanol, isopropanol, 1,2-dichloroethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), n-heptane, and tetrahydrofuran, and n-butanol is most preferred.

[0026] This system is a heterogeneous catalytic system. The heterogeneous single-atom cobalt-based catalyst (Co / CeO2-S) can be recycled for more than 8 cycles without a significant decrease in activity.

[0027] The substrate was enlarged 10 times (10 mmol) and the catalyst was enlarged 5 times. Under standard conditions, the reaction lasted 8 hours and the selectivity of 1,3-cyclohexanedimethylamine could reach 90.1%. The results of the enlarged experiment proved the potential application value of the reaction system.

[0028] The present invention develops a novel, simple and efficient strategy for catalytic reduction of 1,3-isophthalonitrile to synthesize 1,3-cyclohexanedimethylamine using a heterogeneous metal cobalt catalyst. The reaction system consists of 1,3-isophthalonitrile, a heterogeneous cobalt catalyst, a solvent and hydrogen; the reaction temperature is 80-160°C, the reaction pressure is 1-10MPa, hydrogen / isophthalonitrile=10-200 (molar ratio), isophthalonitrile / catalyst / solvent=1:0.3:9 (weight ratio). Isophthalonitrile can be converted into 1,3-cyclohexanedimethylamine with high activity and selectivity under the action of a catalyst in a fixed bed reactor. The catalyst has the advantages of simple preparation, good cycle stability and high yield. The process goal is to improve the yield and product purity of 1,3-cyclohexanedimethylamine, reduce the energy consumption of the production process of 1,3-cyclohexanedimethylamine, and achieve a breakthrough in the production technology of 1,3-cyclohexanedimethylamine.

[0029] This method has high catalytic oxidation efficiency, good selectivity, and high product yield. It not only greatly improves the atomic utilization rate, but is also economical and environmentally friendly, and has good application prospects.

[0030] Compared with the prior art, the present invention has the following advantages and effects:

[0031] (1) The multiphase single-atom metal catalyst used in the present invention has a simple metal composition, good fluidization, strong water resistance, wear resistance, and strong cycle stability, and has great industrial application value.

[0032] (2) Compared with the existing technology, the inventive route has the advantages of mild reaction conditions (reaction temperature) and simple operation (reaction time).

[0033] (3) The liquid phase heterogeneous catalytic one-step hydrogenation reduction process route of the present invention starts from isophthalonitrile as raw material, has low cost, and the selectivity of 1,3-cyclohexanedimethylamine can reach 92.4%. The route is simple, green and pollution-free, and has a better prospect for industrial production. DETAILED DESCRIPTION

[0034] The following examples will help to understand the present invention, but the present invention is not limited thereto.

[0035] Example 1

[0036] Preparation of CeO2-S (Sheets) carrier:

[0037] 10.0 g of Ce(NH4)2(NO3)6 was placed in a crucible and then calcined at 650°C in a muffle furnace for 2 hours to obtain a carrier CeO2-S for use.

[0038] Example 2

[0039] Preparation of CeO2-P (Polyhedrons) carrier:

[0040] 5.0 g of Ce(NO3)3·6H2O was dissolved in 100 mL of deionized water, and the solution was adjusted to pH = 11.0 by adding NH4OH (3.4 M) under magnetic stirring at room temperature. The resulting gel mixture was washed with purified water, dried in an oven at 100°C for 12 hours, and then calcined in a muffle furnace at 500°C for 4 hours to obtain the carrier CeO2-P for use.

[0041] Example 3

[0042] Preparation of CeO2-R (Rods) carrier:

[0043] 0.868 g of Ce(NO3)3·6H2O was dissolved in 5 mL of deionized water. After that, 15 g of NaOH was dissolved in 35 mL of deionized water and added dropwise to the above cerium nitrate aqueous solution. After stirring at room temperature for 30 minutes, the suspension was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel high-pressure crystallization reactor and kept at 100 ° C for 24 hours. The product was then centrifuged and washed three times with ethanol and water respectively, and then dried in an oven at 60 ° C to finally obtain CeO2-R powder for use.

[0044] Example 4

[0045] Preparation of CeO2-O (Octahedrons) carrier:

[0046] 0.87 g of Ce(NO3)3·6H2O and 0.0076 g of Na3PO4 were dissolved in 80 mL of distilled water. After stirring at room temperature for 0.5 h, the mixed solution was transferred to a polytetrafluoroethylene-lined stainless steel high-pressure crystallization reactor and heated at 170 ° C for 10 h. The precipitate was then washed three times with distilled water and ethanol respectively, then dried at 60 ° C for 12 h, and then calcined at 350 ° C in a muffle furnace for 3 h to finally obtain CeO2-O powder for use.

[0047] Example 5

[0048] Preparation of single-atom Co / CeO2-S (0.1wt% Co, the loading amount of Co on the carrier CeO2-S is 0.1wt%):

[0049] 0.00202 g CoCl2·6H2O and 0.5 g CeO2-S were dispersed in 20 mL of deionized water and stirred for 24 hours. The water was then evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 300°C, 400°C and 500°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain Co / CeO2-S-300, Co / CeO2-S-400 and Co / CeO2-S-500, respectively.

[0050] For other cobalt single-atom catalysts (Co / CeO2-P-400, Co / CeO2-R-400, Co / CeO2-O-400, Co / ZrO2-400, Co / Nb2O5-400, Co / Ta2O5-400, Co / MgO-400, Co / Al2O3-400 or Co / SiO2-400), the preparation method is the same as that of the above-mentioned Co / CeO2-S-400 catalyst, the difference being that CeO2-S is replaced by an equal mass of the corresponding carrier (CeO2-P, CeO2-R, CeO2-O, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3 or SiO2).

[0051] Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectron spectroscopy) and DFT theoretical calculation, it was found that the cobalt in the catalyst was dispersed on the carrier in the form of single atoms.

[0052] Preparation of single-atom Ru / CeO2-S (0.1wt%Ru, the loading amount of Ru on the carrier CeO2-S is 0.1wt%):

[0053] 0.00103g RuCl3·3H2O and 0.5g CeO2-S were dispersed in 20mL of deionized water and stirred for 24 hours. Then the water was evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 300°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain a single-atom Ru / CeO2-S (0.1wt% Ru) catalyst. Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectron spectroscopy) and DFT theoretical calculation methods, it was found that the cobalt in the catalyst was dispersed on the carrier in the form of single atoms.

[0054] Example 7

[0055] Preparation of single-atom Pd / CeO2-S (0.1wt% Pd, the loading amount of Pd on the carrier CeO2-S is 0.1wt%):

[0056] 0.00083g PdCl2 and 0.5g CeO2-S were dispersed in 20mL of deionized water and stirred for 24 hours. Then the water was evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 200°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain a single-atom Pd / CeO2-S (0.1wt% Pd) catalyst. Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectron spectroscopy) and DFT theoretical calculation methods, the cobalt in the catalyst was dispersed on the carrier in the form of single atoms. Example 8

[0057] Preparation of single-atom Pt / CeO2-S (0.1wt% Pt, the loading amount of Pt on the carrier CeO2-S is 0.1wt%):

[0058] 0.00109g H2PtCl6·6H2O and 0.5g CeO2-S were dispersed in 20mL of deionized water and stirred for 24 hours. Then the water was evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 300°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain a single-atom Pt / CeO2-S (0.1wt% Pt) catalyst. Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectron spectroscopy) and DFT theoretical calculation methods, it was found that the cobalt in the catalyst was dispersed on the carrier in the form of single atoms.

[0059] Example 9

[0060] Preparation of single-atom Ni / CeO2-S (0.1wt% Ni, the loading amount of Ni on the carrier CeO2-S is 0.1wt%):

[0061] 0.00126g NiCl2·6H2O and 0.5g CeO2-S were dispersed in 20mL of deionized water and stirred for 24 hours. Then the water was evaporated at 60°C under vacuum. The obtained solid was calcined and reduced at 450°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain a single-atom Ni / CeO2-S (0.1wt% Ni) catalyst. Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectron spectroscopy) and DFT theoretical calculation methods, the cobalt in the catalyst was dispersed on the carrier in the form of single atoms. Example 10

[0062] Preparation of single-atom Ni / C (5wt% Ni, Ni loading on carrier C is 5wt%):

[0063] First, the metal precursor nickel chloride 0.0629g NiCl2·6H2O was dissolved in 20mL deionized water and then immersed in 0.5g carbon support. Then, the water was removed using a rotary evaporator at 60°C. Finally, the obtained solid was calcined at 450°C for 2 hours under a flowing volume concentration of 10% H2 / N2 atmosphere to obtain a single-atom Ni / C (5wt% Ni) catalyst. Through HAADF-STEM, XAS (X-ray absorption spectroscopy), XPS (X-ray photoelectronspectroscopy) and DFT theoretical calculation methods, it was found that the cobalt in the catalyst was dispersed on the support in the form of single atoms.

[0064] Embodiment 11

[0065] Isophthalonitrile (1 mmol), catalyst (40 mg) and tert-butyl alcohol (2 mL) were added into a 10 mL reaction tube in sequence, and then the reaction tube was placed in a high-pressure reactor and sealed (sealed). Hydrogen was filled in for replacement three times to check for leaks, and then 5 MPa H2 was filled in. The reaction was placed in a 130°C oil bath and stirred at 550 r / min for 6 hours. After the reaction was completed, the reactor was naturally cooled to room temperature, the gas was slowly released and the pressure was reduced, 20 mg of naphthalene was added as an internal standard, and then 2 mL of acetonitrile was added for dilution. The reaction was stirred, ultrasonicated, mixed evenly, and centrifuged. The supernatant was taken for GC / GC-MS analysis.

[0066] Embodiment 12-44

[0067] Except for one or more of the catalyst support type and the single atom type (the catalyst prepared above), the reaction temperature or the solvent type, the catalyst activity evaluation is the same as that of Example 11. The reaction conditions and catalytic reaction results are shown in Table 1.

[0068] It can be seen from Table 1 that: 1) The hydrogenation reduction temperature of the single-atom cobalt catalyst may have a certain effect on the activity of the catalyst (Examples 13-15); Different choices of catalyst carriers may lead to different final catalytic performance, among which CeO2-S-400 has the highest catalytic activity when used as a carrier (Examples 16-24); 3) Different single-atom metal elements may lead to different catalytic activities, among which the catalytic activity is highest when the Co element is a single atom and the loading amount is 0.1wt% (Examples 25-29); 4) Different reaction temperatures may lead to different final yields of 1,3-cyclohexanedimethylamine, among which the reaction result is best when the reaction temperature is 130°C (Examples 14, 30-34); 5) Different solvent types may lead to different final reaction results, among which n-butanol has the best reaction effect as a solvent (Examples 14, 35-44).

[0069] In short, factors such as the type of catalyst, the morphology of the catalyst carrier, the type of carrier, the type of monatomic metal, the catalyst calcination temperature, the reaction temperature, the type of solvent, etc. will affect the efficiency of the one-step hydrogenation of isophthalonitrile to 1,3-cyclohexyldimethylamine.

[0070]

[0071] Table 1 Condition screening for one-step hydrogenation of isophthalonitrile to 1,3-cyclohexanedimethylamine

[0072]

[0073]

[0074] It can be seen from the above embodiments that the multiphase single-atom cobalt Co catalyst used in the present invention has a simple metal composition, is novel, has strong water resistance, is wear-resistant, has strong cycle stability, and has great industrial application value.

[0075] The method for synthesizing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile of the present invention has the advantages of novel and reliable process, low cost, low pollution, recoverable catalyst, high product quality and high yield, and is the focus of the current development of 1,3-cyclohexyldimethylamine production process in my country. The yield of 1,3-cyclohexyldimethylamine can reach 92.4%, the route is simple, green and pollution-free, and has the prospect of industrial production.

Claims

1. A method for preparing 1,3-cyclohexyldimethylamine by one-step hydrogenation of isophthalonitrile, characterized in that: In a solvent, over a heterogeneous single-atom catalyst, 1,3-isophthalonitrile is hydrogenated to produce 1,3-cyclohexanedimethylamine, and the reaction conditions are: The reaction temperature is 80-160°C, preferably 100-150°C, and most preferably 120-140°C; The reaction pressure is 1-10 MPa, preferably 3.0-8.0 MPa, and most preferably 4.0-6.0 MPa; Hydrogen:isophthalonitrile = 10-200 (molar ratio), preferably 12-180, most preferably 18-150; Isophthalonitrile: catalyst: solvent = 1: 0.05-1.2: 1-20 (weight ratio), preferably 1: 0.2-0.9: 5-12, most preferably 1: 0.1-0.5: 5-12, and most preferably 1: 0.3: 9 (weight ratio).

2. The method according to claim 1, characterized in that: Heterogeneous single-atom catalysts are supported catalysts. The carrier may be one or more of TiO2, CeO2, ZrO2, Nb2O5, Ta2O5, MgO, Al2O3, SiO2, and activated carbon; The active metal supported by the carrier is one or more of Co, Mn, Ni, Ru, Pt, Fe, Pd, and Au; it is dispersed on the carrier in the form of single atoms; The mass loading amount of the active metal on the carrier is 0.001 to 0.5 of the mass of the carrier, preferably 0.01 to 0.25, and most preferably 0.016 to 0.

12.

3. The method according to claim 1 or 2, characterized in that: The multiphase single-atom catalyst is a supported catalyst, the support is CeO2, and the active metal supported by the support is Co, which is dispersed on the support in the form of single atoms; The mass loading amount of the active metal on the carrier is 0.001 to 0.5 of the mass of the carrier, preferably 0.01 to 0.25, and most preferably 0.016 to 0.

12.

4. The method according to claim 3, characterized in that: The CeO2 carrier is one or more of CeO2-S, CeO2-P, CeO2-R, and CeO2-O; The specific preparation process is: Preparation of CeO2-S (Sheets) carrier: calcine Ce(NH4)2(NO3)6 at 600-700°C for 2-6 hours to obtain CeO2-S carrier; Or, preparation of carrier CeO2-P (Polyhedrons): dissolve 1-10 g of Ce(NO3)3·6H2O in 50-200 mL of water, and adjust the solution to pH=10-12 by adding NH4OH (2-5 M) under stirring at room temperature; wash the obtained gel mixture with water, dry it in an oven at 80-120° C. for 8-12 hours, and then calcine it at 400-600° C. for 4-6 hours to obtain carrier CeO2-P; Or, preparation of carrier CeO2-R (Rods): dissolve 0.5-1.2g of Ce(NO3)3·6H2O in 5-10mL of water; then, dissolve 10-20g of NaOH in 30-40mL of deionized water and add dropwise to the above cerium nitrate aqueous solution; after stirring at room temperature for 30-60 minutes, transfer the suspension to a 80-120mL crystallization kettle and keep it at 100-120°C for 12-24 hours; then centrifuge the product and wash it three times with ethanol and water respectively, and then dry it in an oven at 60-80°C to finally obtain CeO2-R; Or, preparation of carrier CeO2-O (Octahedrons): dissolve 1-2g of Ce(NO3)3·6H2O and 0.005-0.01g of Na3PO4 in 50-120mL of water; after stirring at room temperature for 0.5-1 hour, transfer the mixed solution to a crystallization kettle and heat it at 150-180°C for 10-12h; then wash the precipitate with distilled water and ethanol three times respectively, then dry it at 60-80°C for 12-16 hours, and then calcine it at 300-400°C in a muffle furnace for 3-5 hours to finally obtain CeO2-O.

5. The method according to claim 3 or 4, characterized in that: The supported multiphase single-atom cobalt catalyst is prepared by impregnating a cerium dioxide (CeO2) carrier in a corresponding metal salt solution; specifically: Preparation of Co / CeO2: 0.00202 g C℃l2·6H2O and 0.5 g CeO2 were dispersed in 20 mL of deionized water and magnetically stirred for 24 hours; then the water was evaporated at 60℃ under vacuum; the obtained solid was calcined and reduced at 300℃~500℃ for 2 hours under a flowing 10% volume content H2 / N2 atmosphere; The mass ratio of C℃l2·6H2O to the carrier is 0.001-0.02, preferably 0.002-0.01, and most preferably 0.003-0.

005.

6. The method according to claim 1, characterized in that: The catalytic performance is related to the amount of catalyst used. Too low an amount will affect the activity of the catalytic reaction, while too high an amount will increase the cost of the catalyst. Therefore, it is necessary to select an appropriate amount. In order to ensure the activity of the catalyst while reducing the cost of the catalyst, the mass ratio of the catalyst to the substrate used is in the range of 0.05 to 1.2, and the preferred mass ratio is in the range of 0.2 to 0.

9.

7. The method according to claim 1, characterized in that: The reaction solvent is any one or more of toluene, acetonitrile, tert-amyl alcohol, tert-butanol, n-butanol, isopropanol, 1,2-dichloroethane, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), n-heptane, and tetrahydrofuran, and n-butanol is most preferred.

8. According to any one of claims 1 to 7, the reaction process of catalyzing the one-step hydrogenation of isophthalonitrile to synthesize 1,3-cyclohexanedimethylamine is as follows: Add isophthalonitrile (0.5-2 mmol), catalyst (20-80 mg, preferably 30-50 mg), and tert-butyl alcohol (1-5 mL, preferably 1-2 mL) into a sealed high-pressure reactor, fill with 4-5 MPa H2, place in an oil bath at 110-160°C (preferably 120-150°C), stir and react for 2-16 h (preferably 4-12 h) to obtain the target product.

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