A heterogeneous catalyst, its preparation method and application in selective n-methylation of primary amines with carbon dioxide

Abstract

The application provides a kind of heterogeneous catalyst and its preparation method and application in catalyzing primary amine and carbon dioxide selective N-methylation reaction, it is related to catalyst technical field.The heterogeneous catalyst provided by the application includes carrier and metal active component supported on the carrier, the carrier is alumina, and the metal active component is Cu nanoparticle or AgCu single-atom alloy.The heterogeneous catalyst provided by the application can catalyze primary amine and carbon dioxide selective N-methylation reaction, and the selectivity of N-methylation is significantly different, N-monomethylated amine or N,N-dimethylated amine can be obtained with high selectivity;when the metal active component is Cu nanoparticle, the corresponding catalyst can achieve more than 97% N-monomethylated amine selectivity, and when the metal active component is AgCu single-atom alloy, the corresponding catalyst can achieve more than 95% N,N-dimethylated amine selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a heterogeneous catalyst, its preparation method, and its application in the selective N-methylation reaction of primary amines with carbon dioxide. Background Technology

[0002] CO2, as a green, non-toxic, inexpensive, abundant, and renewable C1 feedstock, can be used to synthesize high-value-added chemicals through chemical methods, achieving CO2 fixation and utilization. For example, CO2 can be catalytically hydrogenated to formic acid, methanol, and low-carbon olefins. It can also be used as a formylation and alkylation reagent, combining with amines to catalytically convert them into N-formamides and N-methylamines. Among these, N-methylaniline and N,N-dimethylaniline, obtained by combining CO2 with aniline, are important intermediates in organic synthesis and are widely used in the synthesis of dyes, pharmaceuticals, pesticides, rubber, and fragrances.

[0003] Heterogeneous catalysts are widely used in the chemical and chemical engineering fields, including bulk chemicals and fine chemicals, due to their advantages such as easy separation and reusability. In recent years, researchers have conducted in-depth studies on the selective N-methylation of aniline in heterogeneous catalysis. Existing research indicates that Pt-MoO... x Catalysts such as TiO2, Au / Al2O3, and PdGa / TiO2 have been shown to be effective for the N-methylation reaction of primary amines with CO2. However, due to problems such as excessive hydrogenation of N-methylamines, the selectivity of these catalysts for N-monomethylamines and N,N-dimethylamines is not significant, and therefore, it is not possible to obtain N-monomethylamine products or N,N-dimethylamine products with high selectivity. Summary of the Invention

[0004] In view of this, the present invention aims to provide a heterogeneous catalyst, its preparation method, and its application in the selective N-methylation reaction of primary amines with carbon dioxide. The heterogeneous catalyst provided by the present invention can catalyze the selective N-methylation reaction of primary amines with carbon dioxide, yielding N-monomethylated amines or N,N-dimethylated amines with high selectivity.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a multiphase catalyst comprising a support and a metal active component supported on the support, wherein the support is alumina and the metal active component is Cu nanoparticles or AgCu single-atom alloy.

[0007] Preferably, when the active metal component is Cu nanoparticles, the mass of the Cu nanoparticles is 5-12% of the carrier mass; when the active metal component is an AgCu single-atom alloy, the mass of Ag and the mass of Cu in the single-atom alloy are 0.03-0.3% and 5-12% of the carrier mass, respectively.

[0008] This invention provides a method for preparing the heterogeneous catalyst described in the above technical solution, comprising the following steps:

[0009] An alumina support is impregnated in an aqueous solution of a metal salt, and the alumina support impregnated with the metal salt is then dried, calcined, and reduced sequentially to obtain the multiphase catalyst; the metal salt in the aqueous solution is a copper salt or a mixed metal salt of copper salt and silver nitrate.

[0010] Preferably, the impregnation temperature is room temperature, the impregnation time is 8 to 16 hours, and the impregnation is carried out under stirring conditions.

[0011] Preferably, the calcination temperature is 500–800°C, the time is 2–6 hours, and the heating rate to the calcination temperature is 2–10°C / min.

[0012] Preferably, the reduction is carried out under the condition of introducing a reducing gas, which is a mixture of hydrogen and argon, wherein the volume percentage of hydrogen in the reducing gas is 5-100%; the flow rate of the reducing gas is 5-20 mL / min; the reduction temperature is 500-800℃, the time is 2-6 h, and the heating rate to the reduction temperature is 2-10℃ / min.

[0013] This invention provides the application of the heterogeneous catalyst described in the above technical solutions or the heterogeneous catalyst prepared by the above technical solutions in the selective N-methylation reaction of primary amines with carbon dioxide; the primary amine includes one or more of aniline, aniline derivatives, benzylamine, benzylamine derivatives, phenethylamine, phenethylamine derivatives, benzenesulfonamide, benzenesulfonamide derivatives, phenylamide, phenylamide derivatives, aliphatic amines, aliphatic amine derivatives, cyclic amines, and cyclic amine derivatives; the N-methylation reaction is carried out under the condition of hydrogen gas introduction.

[0014] Preferably, the aliphatic amine has 2 to 20 carbon atoms; the cycloamine has 3 to 6 carbon atoms; and the aniline derivative, benzylamine derivative, phenethylamine derivative, benzenesulfonamide derivative, and phenylamide derivative each have the structures shown in formulas a to e:

[0015]

[0016]

[0017] In the structures shown in formulas a to e, R is selected from one or more of the following: alkyl group with 1 to 12 carbon atoms, cycloalkyl group with 3 to 12 carbon atoms, heterocycloalkyl group with 3 to 12 carbon atoms, aryl group with 6 to 20 carbon atoms, heteroaryl group with 5 to 20 carbon atoms, alkoxy group with 1 to 12 carbon atoms, cycloalkoxy group with 3 to 12 carbon atoms, phenoxy group, halogen, trifluoromethyl group, hydroxyl group, amino group, ester group and peptide bond.

[0018] Preferably, the volume ratio of carbon dioxide to hydrogen is 1:1.5 to 1:13, and the total gas pressure of the N-methylation reaction is 3 to 10 MPa; the solvent used in the N-methylation reaction is an alkane with 6 to 10 carbon atoms, a cycloalkane with 6 to 10 carbon atoms, an aromatic hydrocarbon with 6 to 9 carbon atoms, a heterocyclic hydrocarbon with 4 to 10 carbon atoms, a chloroalkane with 6 to 10 carbon atoms, an alcohol solvent with 1 to 9 carbon atoms, an ester solvent with 2 to 10 carbon atoms, an ether solvent with 2 to 8 carbon atoms, acetone, or water.

[0019] Preferably, when the metal active component in the heterogeneous catalyst is Cu nanoparticles, the temperature of the N-methylation reaction is 130–200°C and the time is 12–72 h; when the metal active component in the heterogeneous catalyst is AgCu single-atom alloy, the temperature of the N-methylation reaction is 160–200°C and the time is 12–72 h.

[0020] This invention provides a heterogeneous catalyst comprising a support and a metallic active component loaded on the support. The support is alumina, and the metallic active component is Cu nanoparticles (the corresponding catalyst is denoted as Cu / Al2O3) or AgCu single-atom alloy (the corresponding catalyst is denoted as AgCu / Al2O3). In this invention, the Cu / Al2O3 catalyst itself can selectively yield N-methylamine; in the AgCu / Al2O3 catalyst, due to Ag doping, a single-atom alloy is formed, altering the electronic environment around Cu. This affects the activation ability of H2 and the adsorption / desorption ability of methylamine on the Cu or AgCu surface during the reaction. Therefore, under the same conditions, the selective N-methylation reaction of amine with carbon dioxide is more likely to occur on the AgCu surface, which also makes it easier for methylamine to be further hydrogenated to N,N-dimethylamine. Therefore, the heterogeneous catalyst provided by this invention catalyzes the selective N-methylation reaction of primary amines with carbon dioxide, exhibiting significant differences in N-methylation selectivity. Under the same reaction conditions, it can highly selectively yield different methylation products, namely N-monomethylated amines or N,N-dimethylated amines. Furthermore, the heterogeneous catalyst provided by this invention has high catalytic activity and good reaction selectivity for the N-methylation reaction of primary amines with carbon dioxide. The heterogeneous catalyst also has good stability, can be reused, and is easy to separate.

[0021] The results of the examples show that, when the heterogeneous catalyst provided by this invention catalyzes the selective N-methylation reaction of primary amines with carbon dioxide at a reaction temperature of 175°C, a reaction time of 27 h, and a CO2 partial pressure to H2 partial pressure ratio of 2:5, the conversion rate of primary amines reaches over 98%. The Cu / Al2O3 catalyst can achieve a selectivity of over 97% for N-monomethylated amines, and the AgCu / Al2O3 catalyst can achieve a selectivity of over 95% for N,N-dimethylated amines. This invention achieves the goal of preparing catalysts using the same preparation method, and obtaining catalysts with high selectivity to different methylation products (i.e., N-monomethylated amines or N,N-dimethylated amines) under the same reaction conditions. Attached Figure Description

[0022] Figure 1 These are the XRD patterns of the catalysts prepared in Examples 1 and 6;

[0023] Figure 2 These are XPS plots of Cu 2p for the catalysts prepared in Examples 1 and 6;

[0024] Figure 3 XPS plots of Ag 2p catalysts prepared in Comparative Example 3 and Example 1;

[0025] Figure 4 TEM image of the catalyst prepared in Example 6;

[0026] Figure 5 This is a TEM image of the catalyst prepared in Example 1;

[0027] Figure 6 This is an AC-TEM image of the catalyst prepared in Example 1. Detailed Implementation

[0028] This invention provides a multiphase catalyst, comprising a support and a metallic active component loaded on the support, wherein the support is alumina, and the metallic active component is Cu nanoparticles or an AgCu single-atom alloy. In this invention, when the metallic active component is Cu nanoparticles, the mass of the Cu nanoparticles is preferably 5-12% of the mass of the support, more preferably 8-10%. In this invention, when the metallic active component is an AgCu single-atom alloy, the mass of Ag and the mass of Cu in the single-atom alloy are preferably 0.03-0.3% and 5-12% of the mass of the support, more preferably 0.05-0.1% and 8-10%, and even more preferably 0.05% and 10%, respectively; in the AgCu single-atom alloy, Ag is doped in the Cu lattice in a single-atom form to form a single-atom alloy. The heterogeneous catalyst provided by this invention can catalyze the selective N-methylation reaction of primary amines with carbon dioxide, exhibiting significant differences in N-methylation selectivity and highly selectively yielding N-monomethylated amines or N,N-dimethylated amines. Furthermore, the heterogeneous catalyst provided by this invention demonstrates high catalytic activity, high reaction conversion rate, and high Ag utilization rate in the N-methylation reaction of amines with carbon dioxide. The heterogeneous catalyst also exhibits good stability and can be reused. This invention provides a novel catalytic scheme for the activation and conversion of CO2 and its efficient selective methylation with primary amines, providing technical guidance for the development of green processes for the selective methylation of primary amines.

[0029] This invention provides a method for preparing the heterogeneous catalyst described in the above technical solution, comprising the following steps:

[0030] An alumina support is impregnated in an aqueous solution of a metal salt, and the alumina support impregnated with the metal salt is then dried, calcined, and reduced sequentially to obtain the multiphase catalyst; the metal salt in the aqueous solution is a copper salt or a mixed metal salt of copper salt and silver nitrate.

[0031] In this invention, the alumina support is preferably one or more of α-alumina, β-alumina, and γ-alumina, and the particle size of the alumina support is preferably 40-200 mesh. In this invention, the copper salt is preferably one or more of copper sulfate, copper nitrate, copper chloride, and copper acetate; the metal salt aqueous solution is preferably obtained by dissolving the metal salt in deionized water. In this invention, the impregnation is preferably equal-volume impregnation, which can be performed according to equal-volume impregnation methods well known to those skilled in the art; the concentration of the metal salt in the metal salt aqueous solution can be calculated based on the Cu and Ag content in the heterogeneous catalyst. In this invention, when preparing the AgCu / Al2O3 catalyst, if the mass of Ag is greater than 0.3% of the support mass or the mass of Cu is not in the range of 5-12% of the support mass, only Ag clusters or nanoparticles combined with Cu nanoparticles are obtained, which is a non-single-atom alloy catalyst and cannot achieve a high-selectivity catalytic effect for obtaining N,N-dimethylamine. In this invention, the immersion temperature is preferably room temperature, the immersion time is preferably 8 to 16 hours, more preferably 12 hours, and the immersion is preferably carried out under slow stirring conditions.

[0032] In this invention, the drying temperature is preferably 80-120°C, more preferably 100°C, and the drying time is preferably 6-12 hours, more preferably 12 hours; the drying is preferably carried out in a forced-air drying oven.

[0033] In this invention, the calcination temperature is preferably 500–800°C, more preferably 500–600°C, and even more preferably 600°C; the calcination time is preferably 2–6 hours, more preferably 3–5 hours; and the heating rate to the calcination temperature is preferably 2–10°C / min, more preferably 5–8°C / min. The calcination is preferably carried out in a muffle furnace, but can also be carried out in an air atmosphere. During the calcination process, the metal salt supported on the alumina carrier is converted into the corresponding metal oxide (copper oxide or copper oxide + silver oxide). Simultaneously, calcination increases the bonding force between the metal and the carrier, making it less likely for the metal to detach from the carrier surface. After calcination, the resulting material is preferably ground into powder.

[0034] In this invention, the reduction is preferably carried out under the condition of introducing a reducing gas, which is preferably a mixture of hydrogen and argon. The volume percentage of hydrogen in the reducing gas is preferably 5-100%, more preferably 10-100%, and even more preferably 100%, i.e., pure hydrogen. The flow rate of the reducing gas is preferably 5-20 mL / min, more preferably 10-15 mL / min. In this invention, the reduction temperature is preferably 500-800°C, more preferably 500-600°C, and the time is preferably 2-6 h, more preferably 3-5 h. The heating rate to the reduction temperature is preferably 2-10°C / min, more preferably 5-8°C / min. In this invention, the reduction is preferably carried out in a reduction furnace. During the reduction process, when the metal oxide loaded on the support is copper oxide, it is reduced to copper under high temperature and a hydrogen atmosphere. When the metal oxides loaded on the support are copper oxide and silver oxide, they are reduced to their respective metallic states under high temperature and a hydrogen atmosphere. Simultaneously, due to the high temperature, the metallic Cu and Ag alloy, forming an AgCu single-atom alloy. After the reduction, the mixture is naturally cooled to room temperature.

[0035] The preparation method provided by this invention is simple, easy to operate, low in cost, and easy to scale up for production.

[0036] This invention provides the application of the heterogeneous catalyst described in the above technical solutions or the heterogeneous catalyst prepared by the above technical solutions in the selective N-methylation reaction of primary amines with carbon dioxide. In this invention, the primary amine includes one or more of aniline, aniline derivatives, benzylamine, benzylamine derivatives, phenethylamine, phenethylamine derivatives, benzenesulfonamide, benzenesulfonamide derivatives, phenylamide, phenylamide derivatives, aliphatic amines, aliphatic amine derivatives, cyclic amines, and cyclic amine derivatives. In this invention, the aniline derivatives, benzylamine derivatives, phenethylamine derivatives, benzenesulfonamide derivatives, and phenylamide derivatives preferably have structures shown in formulas a to e, respectively.

[0037]

[0038] In the structures shown in formulas a to e, R is preferably selected from one or more of the following: alkyl group with 1 to 12 carbon atoms, cycloalkyl group with 3 to 12 carbon atoms, heterocycloalkyl group with 3 to 12 carbon atoms, aryl group with 6 to 20 carbon atoms, heteroaryl group with 5 to 20 carbon atoms, alkoxy group with 1 to 12 carbon atoms, cycloalkoxy group with 3 to 12 carbon atoms, phenoxy group, halogen, trifluoromethyl group, hydroxyl group, amino group, ester group and peptide bond.

[0039] In this invention, the aliphatic amine preferably has 2 to 20 carbon atoms, and the cycloamine preferably has 3 to 6 carbon atoms. The structures of the aliphatic amine and the cycloamine are shown in formula f and formula g, respectively.

[0040]

[0041] In this invention, the fatty amine derivative is preferably a fatty amine containing alkoxy, phenoxy, halogen, hydroxy, amino, or other groups, and the cyclic amine derivative is preferably a cyclic amine containing alkyl, alkoxy, halogen, hydroxy, amino, or other groups.

[0042] In this embodiment of the invention, a primary amine with the following structure is used as an example for illustration:

[0043]

[0044] In this invention, the preferred ratio of the heterogeneous catalyst to the primary amine is 30–100 mg: 0.3–1.0 mmol, more preferably 50 mg: 0.5 mmol. In this invention, the N-methylation reaction is carried out under hydrogen gas conditions; the preferred volume ratio of carbon dioxide to hydrogen is 1:1.5–1:13, more preferably 1:1.5–1:6, and even more preferably 1:2.5; the preferred total gas pressure for the N-methylation reaction is 3–10 MPa, more preferably 5–7 MPa. In this invention, the N-

[0045] The solvent used in the methylation reaction is preferably an alkane with 6 to 10 carbon atoms, a cycloalkane with 6 to 10 carbon atoms, an aromatic hydrocarbon with 6 to 9 carbon atoms, a heterocyclic hydrocarbon with 4 to 10 carbon atoms, a chloroalkane with 6 to 10 carbon atoms, an alcohol solvent with 1 to 9 carbon atoms, an ester solvent with 2 to 10 carbon atoms, an ether solvent with 2 to 8 carbon atoms, acetone, or water, more preferably an alkane with 6 to 10 carbon atoms, and even more preferably n-octane; the present invention does not have special requirements on the amount of the solvent used, as long as it can ensure the smooth progress of the reaction. In this invention, when the metal active component in the heterogeneous catalyst is Cu nanoparticles, the temperature of the N-methylation reaction is preferably 130–200°C, more preferably 150–180°C, further preferably 170–180°C, and most preferably 175°C; the time is preferably 12–72 h, more preferably 24–30 h, and more preferably 24–27 h. When the metal active component in the heterogeneous catalyst is AgCu single-atom alloy, the temperature of the N-methylation reaction is preferably 160–200°C, more preferably 170–200°C, further preferably 170–180°C, and most preferably 175°C; the time is preferably 12–72 h, more preferably 24–30 h, and more preferably 24–27 h.

[0046] In this invention, the preferred specific operation of the N-methylation reaction is as follows: the heterogeneous catalyst, primary amine and solvent are added to the reaction vessel, the reaction vessel is sealed and the air in the system is replaced with pure hydrogen, and then carbon dioxide and hydrogen are introduced to meet the total gas pressure; the N-methylation reaction is carried out by heating.

[0047] In the N-methylation reaction, the primary amine undergoes a methylation reaction with carbon dioxide and hydrogen, where a methyl group replaces one or two hydrogen atoms on the primary amine to form an N-monomethylated amine or an N,N-dimethylated amine. Taking aniline and its derivatives as examples of primary amines, the methylation reaction is shown in Formula A. The heterogeneous catalyst provided by this invention catalyzes the N-methylation reaction of primary amines with carbon dioxide, exhibiting significant differences in N-methylation selectivity, and can highly selectively yield N-monomethylated amines or N,N-dimethylated amines. When the metal active component is Cu nanoparticles, the corresponding heterogeneous catalyst can achieve an N-monomethylated amine selectivity of over 97%, and when the metal active component is an AgCu single-atom alloy, the corresponding heterogeneous catalyst achieves an N,N-dimethylated amine selectivity of over 95%, thus enabling highly selective yielding of N-monomethylated amines or N,N-dimethylated amines.

[0048]

[0049] This invention achieves the goal of preparing catalysts using the same preparation method, and obtaining different methylation products (i.e., N-monomethylamines or N,N-dimethylamines) under the same reaction conditions.

[0050] The following examples illustrate the heterogeneous catalysts provided by this invention, their preparation methods, and their application in the selective N-methylation reaction of primary amines with carbon dioxide. However, these examples should not be construed as limiting the scope of protection of this invention.

[0051] Example 1

[0052] Weigh 0.754 g Cu(NO3)2·3H2O and 0.0016 g AgNO3 and dissolve them in 2 mL of deionized water, then sonicate for 10 min. Add 2.00 g γ-alumina support to the above solution, stir at room temperature for 12 h, and then dry in a 100 °C oven for 12 h. Place the dried solid in a muffle furnace at 600 °C and calcine in air for 3 h at a heating rate of 5 °C / min. Grind the calcined solid into powder and reduce it in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere with a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported AgCu catalyst is obtained, denoted as AgCu / Al2O3-1.

[0053] Example 2

[0054] Weigh 0.603 g Cu(NO3)2·3H2O and 0.0016 g AgNO3 and dissolve them in 2 mL of deionized water, then sonicate for 10 min. Add 2.00 g γ-alumina support to the above solution, stir at room temperature for 12 h, and then dry in a 100 °C oven for 12 h. Place the dried solid in a muffle furnace at 600 °C and calcine in air for 3 h at a heating rate of 5 °C / min. Grind the calcined solid into powder and reduce it in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere with a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported AgCu catalyst is obtained, denoted as AgCu / Al2O3-2.

[0055] Example 3

[0056] Weigh 0.603 g Cu(NO3)2·3H2O and 0.0096 g AgNO3 and dissolve them in 2 mL of deionized water, then sonicate for 10 min. Add 2.00 g γ-alumina support to the above solution, stir at room temperature for 12 h, and then dry in a 100 °C oven for 12 h. Place the dried solid in a muffle furnace at 600 °C and calcine it in air for 3 h at a heating rate of 5 °C / min. Grind the calcined solid into powder and reduce it in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere at a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported AgCu catalyst is obtained, denoted as AgCu / Al2O3-3.

[0057] Example 4

[0058] Weigh 0.754 g Cu(NO3)2·3H2O and 0.0032 g AgNO3 and dissolve them in 2 mL of deionized water, then sonicate for 10 min. Add 2.00 g γ-alumina support to the above solution, stir at room temperature for 12 h, and then dry in a 100 °C oven for 12 h. Place the dried solid in a muffle furnace at 600 °C and calcine it in air for 3 h at a heating rate of 5 °C / min. Grind the calcined solid into powder and reduce it in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere with a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported AgCu catalyst is obtained, denoted as AgCu / Al2O3-4.

[0059] Example 5

[0060] Weigh 0.754 g Cu(NO3)2·3H2O and 0.0096 g AgNO3 and dissolve them in 2 mL of deionized water, then sonicate for 10 min. Add 2.00 g γ-alumina support to the above solution, stir at room temperature for 12 h, and then dry in a 100 °C oven for 12 h. Place the dried solid in a muffle furnace at 600 °C and calcine in air for 3 h at a heating rate of 5 °C / min. Grind the calcined solid into powder and reduce it in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere with a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported AgCu catalyst is obtained, denoted as AgCu / Al2O3-5.

[0061] Application Example 1

[0062] The catalysts prepared in Examples 1-5 were used for the selective N-methylation reaction of aniline with CO2 to illustrate the effect of the copper-silver ratio on the reaction activity and selectivity of this type of catalyst in the selective N-methylation of aniline with CO2.

[0063] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a mixed gas of CO2 and H2 at a total pressure of 7 MPa, where the partial pressure of CO2 was 1 MPa and the partial pressure of H2 was 6 MPa. The temperature was then raised to 180 °C and the reaction was carried out for 24 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed by an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as the internal standard. The reaction data for different catalysts are shown in Table 1.

[0064] Table 1. Effect of copper to silver ratio on the selective N-methylation reaction of aniline with CO2 in Examples 1-5

[0065]

[0066] As shown in Table 1, in the application of the alumina-supported single-atom alloy catalyst provided by this invention to regulate the selective N-methylation reaction of aniline with CO2, the Ag / Cu mass ratio has a significant impact on the reaction activity and selectivity. In this reaction, Ag / Cu catalysts with different mass ratios predominantly exhibit selectivity for N,N-dimethylaniline. Comparison revealed that among catalysts with different Ag / Cu ratios, the AgCu / Al2O3-1 catalyst involved in Example 1 exhibits the best activity and selectivity for N,N-dimethylaniline.

[0067] Application Example 2

[0068] The catalyst AgCu / Al2O3-1 prepared in Example 1 was used for the selective N-methylation reaction of aniline with CO2. The reaction was carried out at different temperatures to illustrate the effect of temperature on the reaction activity and selectivity of the catalyst in the selective N-methylation of aniline with CO2.

[0069] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a mixed gas of CO2 and H2 at a total pressure of 7 MPa, where the partial pressure of CO2 was 1 MPa and the partial pressure of H2 was 6 MPa. The mixture was then heated to different temperatures and reacted for 24 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as an internal standard. The reaction data for different catalysts are shown in Table 2.

[0070] Table 2 Effect of temperature on the selective N-methylation reaction of aniline with CO2

[0071]

[0072] As shown in Table 2, in the application of the alumina-supported single-atom alloy catalyst provided by the present invention to regulate the selective N-methylation reaction of aniline with CO2, the conversion is almost complete at a reaction temperature of 180℃, and the selectivity for N,N-dimethylaniline is also high. Further increasing the temperature has an adverse effect on the selectivity.

[0073] Application Example 3

[0074] The catalyst AgCu / Al2O3-1 prepared in Example 1 was used for the selective N-methylation reaction of aniline with CO2. The reaction was carried out under different partial pressures of CO2 and H2 to illustrate the effect of the partial pressures of CO2 and H2 on the reaction activity and selectivity of this type of catalyst in the selective N-methylation of aniline with CO2.

[0075] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged three times with pure hydrogen. A mixture of CO2 and H2 gas at a total pressure of 7 MPa was then introduced, with CO2 and H2 partial pressures varying in proportion. The mixture was then heated to 180 °C and reacted for 24 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity were determined using a standard curve method, with biphenyl as an internal standard. The reaction data of the catalyst under different CO2 and H2 partial pressures are shown in Table 3.

[0076] Table 3. Effect of CO2 / H2 partial pressure ratio on the selective N-methylation reaction of aniline with CO2.

[0077]

[0078] As shown in Table 3, in the application of the alumina-supported single-atom alloy catalyst provided by the present invention to regulate the selective N-methylation reaction of aniline with CO2, the partial pressure of CO2 and the partial pressure of H2 have a significant impact on the activity and selectivity of the reaction. When the partial pressure of CO2 and the partial pressure of H2 are 2:5, AgCu / Al2O3-1 has the highest selectivity for N,N-dimethylaniline.

[0079] Based on the above examples, it can be concluded that the optimal catalyst for the selective preparation of N,N-dimethylaniline from aniline and CO2 is AgCu / Al2O3-1 catalyst, and the optimal reaction conditions are: reaction temperature of 180℃, reaction time of 24h, CO2 partial pressure to H2 partial pressure ratio of 2:5, aniline conversion rate of 99% and N,N-dimethylaniline selectivity of 82%.

[0080] The following examples were conducted to test the catalytic activity and selectivity of Cu / Al2O3 and Ag / Al2O3 catalysts of the same type prepared using the same method for the selective N-methylation reaction of aniline with CO2.

[0081] Example 6

[0082] 0.754 g of Cu(NO3)2·3H2O was weighed and dissolved in 2 mL of deionized water and sonicated for 10 min. 2.00 g of γ-alumina support was added to the above solution and stirred at room temperature for 12 h. Then, it was dried in a 100 °C oven for 12 h. The dried solid was calcined in air in a muffle furnace at 600 °C for 3 h at a heating rate of 5 °C / min. The calcined solid was ground into powder and reduced in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere at a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported Cu catalyst was obtained, denoted as Cu / Al2O3-1.

[0083] Comparative Example 1

[0084] 0.754 g Cu(NO3)2·3H2O and 14.705 g Al(NO3)3·9H2O were weighed and dissolved in 600 mL of deionized water and sonicated for 10 min. Then, 150 mL of a solution containing 10.338 g anhydrous Na2CO3 was added to the above solution using a constant pressure funnel, and the mixture was stirred at room temperature for 5 h. The solution was then dried in a 100 °C forced-air oven for 12 h. The dried solid was then calcined in air in a muffle furnace at 450 °C for 3 h at a heating rate of 5 °C / min. The calcined solid was then ground into powder and reduced in a conventional reduction furnace at 450 °C for 3 h in an H2 atmosphere at a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, an alumina-supported Cu catalyst was obtained, denoted as CuAlOx-Comparative 1.

[0085] Comparative Example 2

[0086] 0.754 g of Cu(NO3)2·3H2O was weighed and dissolved in 2 mL of deionized water and sonicated for 10 min. 2.00 g of γ-alumina support was added to the above solution and stirred at room temperature for 12 h. Then, it was dried in a 100 °C oven for 12 h. The dried solid was calcined in air in a muffle furnace at 450 °C for 3 h at a heating rate of 5 °C / min. The calcined solid was ground into powder and reduced in a conventional reduction furnace at 450 °C for 3 h in an H2 atmosphere at a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported Cu catalyst was obtained, denoted as Cu / Al2O3-Comparative 2.

[0087] Comparative Example 3

[0088] 0.0016 g AgNO3 was dissolved in 2 mL of deionized water and sonicated for 10 min. 2.00 g γ-alumina support was added to the above solution and stirred at room temperature for 12 h. Then, it was dried in a 100 °C oven for 12 h. The dried solid was calcined in air in a muffle furnace at 600 °C for 3 h at a heating rate of 5 °C / min. The calcined solid was ground into powder and reduced in a conventional reduction furnace at 600 °C for 3 h in a pure H2 atmosphere at a hydrogen flow rate of 10 mL / min and a heating rate of 5 °C / min. After natural cooling, the alumina-supported Ag catalyst was obtained, denoted as Ag / Al2O3-Comparative 3.

[0089] Application Example 4

[0090] The catalysts prepared in Example 6 and Comparative Examples 1-3 were used for the selective N-methylation reaction of aniline with CO2 to illustrate the differences in the catalytic effects of the four catalysts in the selective N-methylation of aniline with CO2.

[0091] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a mixed gas of CO2 and H2 at a total pressure of 7 MPa, where the partial pressure of CO2 was 2 MPa and the partial pressure of H2 was 5 MPa. The temperature was then raised to 150 °C and the reaction was carried out for 24 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed by an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as the internal standard. The reaction data for different catalysts are shown in Table 4.

[0092] Table 4. Results of the catalysts synthesized in Example 6 and Comparative Examples 1-3 in the selective N-methylation reaction of aniline with CO2.

[0093]

[0094] Table 4 shows that the main product of the Cu / Al2O3-1 catalyst is N-methylaniline, while the main product of the Cu / Al2O3-Comparative 2 catalyst prepared by the same method but with lower calcination and reduction temperatures is N-formylaniline. This indicates that the calcination and reduction temperatures have a significant impact on the catalytic performance during catalyst preparation. The CuAlOx-Comparative 1 catalyst prepared by the co-precipitation method does not show clear product selectivity, indicating that the catalyst preparation method is directly related to its performance. The Ag / Al2O3-Comparative 3 catalyst prepared using the same method has no activity for this reaction.

[0095] Application Example 5

[0096] The catalyst Cu / Al2O3-1 prepared in Example 6 and the catalyst AgCu / Al2O3-1 prepared in Example 1 were used for the selective N-methylation reaction of aniline with CO2. The catalytic performance of the above catalysts was tested by fine-tuning the reaction temperature and reaction time to illustrate the effect of the two types of catalysts on the activity and selectivity in the selective N-methylation reaction of aniline with CO2.

[0097] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a CO2 and H2 mixture at a total pressure of 7 MPa, with a CO2 partial pressure to H2 partial pressure ratio of 2:5. The mixture was then heated to a certain temperature and reacted for a specified time. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as an internal standard. Reaction data for different catalysts are shown in Table 5.

[0098] Table 5 Effect of temperature on the selective N-methylation reaction of aniline with CO2

[0099]

[0100] As shown in Table 5, in the application of the catalyst provided by this invention to regulate the selective N-methylation reaction of aniline with CO2, based on the aforementioned examples, by fine-tuning the reaction conditions, it is possible to achieve selective N,N-methylaniline and N-methylaniline products respectively using AgCu / Al2O3-1 and Cu / Al2O3-1 catalysts prepared by the same method. The optimized reaction conditions are: reaction temperature of 175℃, reaction time of 27h, CO2 partial pressure to H2 partial pressure ratio of 2:5, aniline conversion rate of over 98%, AgCu / Al2O3-1 catalyst selectivity for N,N-dimethylaniline of 95%, and Cu / Al2O3-1 catalyst selectivity for N-methylaniline of 97%.

[0101] The catalysts involved in Examples 1-6 and Comparative Examples 1-3 are summarized in Table 6:

[0102] Table 6. Preparation conditions of catalysts in Examples 1-6 and Comparative Examples 1-3

[0103]

[0104]

[0105] Figure 1 These are the XRD patterns of the AgCu / Al2O3-1 catalyst prepared in Example 1 and the Cu / Al2O3-1 catalyst prepared in Example 6. Figure 1 In this context, i represents Al₂O₃, ii represents Ag / Al₂O₃, iii represents Cu / Al₂O₃-1, iv represents Cu / Al₂O₃-1-used, v represents AgCu / Al₂O₃-1, and ui represents AgCu / Al₂O₃-1-used. In iv and ui, "used" indicates the catalyst obtained after the reaction, i.e., the catalyst after use. Figure 1 It can be seen that Cu / Al₂O₃⁻¹ and AgCu / Al₂O₃⁻¹ prepared using the same method have similar crystal structures, both exhibiting Cu nanoparticles as a whole. No Ag diffraction peaks were observed in AgCu / Al₂O₃⁻¹, indicating that Ag has poor crystallinity or is in a highly dispersed state. Furthermore, a comparison before and after catalyst use revealed no significant changes in the crystal structure of either catalyst, demonstrating the stability of the catalyst structure.

[0106] Figure 2These are XPS images of Cu 2p for the AgCu / Al2O3-1 catalyst prepared in Example 1 and the Cu / Al2O3-1 catalyst prepared in Example 6. Figure 2 In the diagram, i represents Cu / Al₂O₃⁻¹, and ii represents AgCu / Al₂O₃⁻¹. (The rest of the text appears to be a garbled string of characters and symbols.) Figure 2 It can be seen that in the Cu / Al2O3-1 and AgCu / Al2O3-1 catalysts, the valence state of Cu on the surface is mainly a mixture of 0 and +2 valences, with the +2 valence primarily due to the oxidation of Cu in air. It is noteworthy that, compared to Cu / Al2O3-1, the binding energy of Cu 2p in the AgCu / Al2O3-1 single-atom alloy catalyst shifts to a lower field direction by 0.12 eV, indicating that Cu is in an electron-rich state. These excess electrons may originate from the doped Ag metal.

[0107] Figure 3 The above are XPS images of the Ag / Al2O3-1 catalyst prepared in Comparative Example 3 and the AgCu / Al2O3-1 catalyst Ag2p prepared in Example 1. Figure 3 In the diagram, i represents Ag / Al₂O₃⁻¹, and ii represents AgCu / Al₂O₃⁻¹. (The remaining text appears to be a fragment and doesn't translate directly.) Figure 3 It can be seen that in the AgCu / Al2O3-1 catalyst, the Cu surface is mainly in the 0 valence state. It is noteworthy that, compared to Ag / Al2O3-1, the Ag 2p binding energy in the AgCu / Al2O3-1 single-atom alloy catalyst shifts to a higher field direction by 0.5 eV, indicating that Ag is in an electron-deficient state. Combined with the XPS results of Cu2p, it can be inferred that there is an interaction between Ag and Cu, with electrons flowing from Ag to Cu, leading to an increase in the Ag binding energy and a decrease in the Cu binding energy.

[0108] Figure 4 This is a TEM image of the Cu / Al₂O₃⁻¹ catalyst prepared in Example 6. Figure 4 It can be seen that Cu / Al2O3-1 mainly consists of Cu nanoparticles, and the lattice spacing of the main exposed crystal planes is 0.210 nm, which belongs to Cu(111). This result is consistent with the XRD results.

[0109] Figure 5 This is a TEM image of the AgCu / Al2O3-1 catalyst corresponding to Example 1. (From...) Figure 5 It can be seen that AgCu / Al2O3-1 also consists of Cu nanoparticles, and the lattice spacing of its main exposed crystal planes is 0.213 nm, which can still be attributed to Cu(111). This also shows that Ag doping caused lattice expansion, a result that is consistent with the XRD results.

[0110] Figure 6This is an AC-TEM image of the AgCu / Al₂O₃⁻¹ catalyst prepared in Example 1. Figure 6 It can be seen that Ag is mainly doped into the Cu(111) lattice in the form of single atoms, which causes lattice expansion and forms a single-atom alloy.

[0111] Application Example 6

[0112] The AgCu / Al2O3-1 catalyst prepared in Example 1 was used for the selective N-methylation reaction of different types of primary amines with CO2 to illustrate the effect of AgCu / Al2O3-1 catalyst on activity and selectivity in the selective N-methylation reaction of different types of primary amines with CO2.

[0113] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of a primary amine compound and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a CO2 and H2 mixture at a total pressure of 7 MPa, with a CO2 partial pressure to H2 partial pressure ratio of 2:5. The mixture was then heated to 175 °C and reacted for 30 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as an internal standard. The reaction data of the catalyst for different types of primary amines are shown in Table 7.

[0114] Table 7 Results of the selective N-methylation reaction of different types of primary amines with CO2 catalyzed by AgCu / Al2O3-1.

[0115]

[0116] As shown in Table 7, in the application of the catalyst provided by this invention to regulate the selective N-methylation reaction of primary amines with CO2, the AgCu / Al2O3-1 catalyst can achieve a conversion rate of over 99% for primary amine compounds with different substituents undergoing N-methylation with CO2, and the selectivity of the corresponding N,N-dimethylaniline product is between 86% and 97%. Due to the influence of substituents and the relatively short reaction time, some substrates are not completely converted into the corresponding N,N-dimethylaniline products.

[0117] Application Example 7

[0118] The Cu / Al2O3-1 catalyst prepared in Example 6 was used for the selective N-methylation reaction of different types of primary amines with CO2 to illustrate the effect of Cu / Al2O3-1 catalyst on activity and selectivity in the selective N-methylation reaction of different types of primary amines with CO2.

[0119] 50 mg of the catalyst prepared above was added to a 100 mL reactor, along with 0.5 mmol of a primary amine compound and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a CO2 and H2 mixture at a total pressure of 7 MPa, with a CO2 partial pressure to H2 partial pressure ratio of 2:5. The mixture was then heated to 175 °C and reacted for 30 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as an internal standard. Reaction data for different catalysts are shown in Table 8.

[0120] Table 8 Results of the selective N-methylation reaction of different types of primary amines with CO2 catalyzed by Cu / Al2O3-1

[0121]

[0122] As shown in Table 8, in the application of the catalyst provided by this invention for the selective N-methylation reaction of primary amines with CO2, the Cu / Al2O3-1 catalyst can achieve a conversion rate of over 99% for primary amine compounds with different substituents undergoing N-methylation reaction with CO2, and the selectivity of N-methylaniline is between 91% and 97%.

[0123] Application Example 8

[0124] Taking the catalyst AgCu / Al2O3-1 prepared in Example 1 as an example, the reusability of the catalyst in the selective N-methylation reaction of aniline and CO2 is explained.

[0125] 50 mg of the AgCu / Al2O3-1 catalyst prepared in Example 1 was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by the introduction of a CO2 and H2 mixture at a total pressure of 7 MPa, with a CO2 partial pressure to H2 partial pressure ratio of 2:5. The mixture was then heated to 175 °C and reacted for 27 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed using an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as the internal standard. Reaction data for catalyst reuse are shown in Table 9.

[0126] Table 9. Reusability of the catalyst in Example 1 during the selective N-methylation reaction of aniline with CO2.

[0127]

[0128] As can be seen from Table 9, the AgCu / Al2O3-1 catalyst prepared in this invention can be reused, and in repeated use, it still has catalytic activity and N,N-dimethylaniline selectivity comparable to that when it was first used.

[0129] Application Example 9

[0130] Taking the catalyst Cu / Al2O3-1 prepared in Example 6 as an example, the reusability of the catalyst in the selective N-methylation reaction of aniline and CO2 is explained.

[0131] 50 mg of the Cu / Al₂O₃⁻¹ catalyst prepared in Example 6 was added to a 100 mL reactor, along with 0.5 mmol of aniline and 3 mL of n-octane. After sealing, the system was purged with pure hydrogen three times, followed by a CO₂ and H₂ mixture at a total pressure of 7 MPa, with a CO₂ partial pressure to H₂ partial pressure ratio of 2:5. The mixture was then heated to 175 °C and reacted for 27 h. After stopping the reaction and cooling to room temperature, the reaction solution was analyzed by an HP-7890N gas chromatograph equipped with an HP-5 capillary column and an FID detector. The conversion and selectivity of the reaction were determined using a standard curve method, with biphenyl as the internal standard. Reaction data for catalyst reuse are shown in Table 10.

[0132] Table 10. Reusability of Cu / Al2O3-1 catalyst in Example 13 for the selective N-methylation reaction of aniline with CO2

[0133]

[0134] As can be seen from Table 10, the Cu / Al2O3-1 catalyst prepared by this invention can be reused, and in repeated use, it still has catalytic activity and N-methylaniline selectivity comparable to that when it was first used.

[0135] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heterogeneous catalyst for the selective N-methylation reaction of primary amines with carbon dioxide, characterized in that, The invention includes a carrier and a metallic active component loaded on the carrier. The carrier is alumina, and the metallic active component is an AgCu single-atom alloy. The mass of Ag and the mass of Cu in the single-atom alloy are 0.03~0.3% and 5~12% of the mass of the carrier, respectively. The preparation method of the heterogeneous catalyst includes the following steps: An alumina support is impregnated in an aqueous solution of a metal salt, and the alumina support impregnated with the metal salt is subsequently dried, calcined, and reduced to obtain the multiphase catalyst; the metal salt in the aqueous solution is a mixed metal salt of copper salt and silver nitrate; the calcination temperature is 600~800℃.

2. The method for preparing the heterogeneous catalyst according to claim 1, characterized in that, Includes the following steps: An alumina support is impregnated in an aqueous solution of a metal salt, and the alumina support impregnated with the metal salt is subsequently dried, calcined, and reduced to obtain the multiphase catalyst; the metal salt in the aqueous solution is a mixed metal salt of copper salt and silver nitrate; the calcination temperature is 600~800℃.

3. The preparation method according to claim 2, characterized in that, The impregnation temperature is room temperature, the impregnation time is 8-16 hours, and the impregnation is carried out under stirring conditions.

4. The preparation method according to claim 2, characterized in that, The calcination time is 2-6 hours, and the heating rate to the calcination temperature is 2-10℃ / min.

5. The preparation method according to claim 2, characterized in that, The reduction is carried out under the condition of introducing a reducing gas, which is a mixture of hydrogen and argon, wherein the volume percentage of hydrogen in the reducing gas is 5-100%; the flow rate of the reducing gas is 5-20 mL / min; the reduction temperature is 500-800℃, the time is 2-6 h, and the heating rate to the reduction temperature is 2-10℃ / min.

6. The application of the heterogeneous catalyst according to claim 1 or the heterogeneous catalyst prepared by any one of claims 2 to 5 in the selective N-methylation reaction of primary amines with carbon dioxide; wherein the primary amine includes one or more of aniline, aniline derivatives, benzylamine, benzylamine derivatives, phenethylamine, phenethylamine derivatives, benzenesulfonamide, benzenesulfonamide derivatives, phenylamide, phenylamide derivatives, aliphatic amines, aliphatic amine derivatives, cyclic amines, and cyclic amine derivatives; wherein the N-methylation reaction is carried out under the condition of hydrogen gas introduction.

7. The application according to claim 6, characterized in that, The aliphatic amine has 2 to 20 carbon atoms; the cycloamine has 3 to 6 carbon atoms; the aniline derivative, benzylamine derivative, phenethylamine derivative, benzenesulfonamide derivative, and phenylamide derivative each have the structures shown in formulas a to e: In the structures shown in formulas a to e, R is selected from one or more of the following: alkyl with 1 to 12 carbon atoms, cycloalkyl with 3 to 12 carbon atoms, heterocycloalkyl with 3 to 12 carbon atoms, aryl with 6 to 20 carbon atoms, heteroaryl with 5 to 20 carbon atoms, alkoxy with 1 to 12 carbon atoms, cycloalkoxy with 3 to 12 carbon atoms, phenoxy, halogen, trifluoromethyl, hydroxyl, amino, and ester.

8. The application according to claim 6 or 7, characterized in that, The volume ratio of carbon dioxide to hydrogen is 1:1.5 to 1:13, and the total gas pressure of the N-methylation reaction is 3 to 10 MPa. The solvent used in the N-methylation reaction is an alkane with 6 to 10 carbon atoms, a cycloalkane with 6 to 10 carbon atoms, an aromatic hydrocarbon with 6 to 9 carbon atoms, a heterocyclic hydrocarbon with 4 to 10 carbon atoms, a chloroalkane with 6 to 10 carbon atoms, an alcohol solvent with 1 to 9 carbon atoms, an ester solvent with 2 to 10 carbon atoms, an ether solvent with 2 to 8 carbon atoms, acetone, or water.

9. The application according to claim 6 or 7, characterized in that, The N-methylation reaction is carried out at a temperature of 160~200℃ for a time of 12~72h.

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