Nitrogen full-flow amination process based on molybdenum-based materials

Abstract

This invention discloses a nitrogen-based, fully flowable amination method for molybdenum-based materials, comprising the following steps: S1, pretreating the molybdenum-based material in a reducing atmosphere; S2, subjecting the pretreated molybdenum-based material to high-temperature nitridation at a first temperature in a nitrogen-containing gas atmosphere to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride; S3, after lowering the ambient temperature to a second temperature, introducing alcohol vapor to contact the molybdenum nitride catalyst for an amination reaction to generate amine products; S4, continuously collecting the amine products using an acidic absorbent; S5, repeating steps S2-S4 to achieve continuous production. This invention uses molybdenum as the catalytic active center, first nitriding and cracking nitrogen gas at high temperature to generate active nitrogen species, which then react with alcohols to generate corresponding amine substances.

Description

Technical Field

[0001] This invention belongs to the field of synthetic process technology, specifically relating to a nitrogen-based full-flow amination method for molybdenum-based materials. Background Technology

[0002] Nitrogen, as a vital element, participates in all aspects of life. The largest natural nitrogen reserve exists in the atmosphere as nitrogen gas, and how to utilize nitrogen more efficiently has always been a core goal pursued by researchers. Currently, nitrogen utilization mainly relies on the Haber-Bosch process, which uses high temperature (400-500℃) and high pressure (15-25MPa) conditions, with the aid of a catalyst, to produce ammonia from nitrogen and hydrogen. Ammonia is then used as a raw material for large-scale downstream products. This indirect conversion pathway inevitably leads to a loss in element utilization. To address the dual needs of improving nitrogen utilization efficiency and sustainable chemical synthesis, the concept of direct nitrogen conversion has emerged as an advanced method.

[0003] Traditional strategies for directly converting nitrogen into nitrogen-containing chemicals (such as NC, NO, N-Si, NP compounds, etc.) typically rely on expensive and complex molecular catalysts and highly reactive alkali metals (such as K, Li, Na) as reducing agents. The high cost and environmental problems associated with these strategies hinder practical application. Furthermore, liquid-phase reaction systems complicate product separation due to solvent mixing, while the mass transfer limitations imposed by batch reactor configurations significantly reduce space-time yields. These combined challenges pose major obstacles to industrial applications, making current systems economically unsuitable for large-scale deployment.

[0004] Amines are important derivatives of ammonia and are widely used in pharmaceuticals, agriculture, dyeing, and sensing industries. Industrially, amine synthesis relies on ammonia as the primary nitrogen feedstock, where alcohols react with ammonia under continuous flow catalysis to produce the corresponding amines. However, ammonia-dependent processes have significant drawbacks: ammonia synthesis requires energy-intensive processes such as the Haber-Bosch process, as well as specialized storage and transportation infrastructure, and the construction of corrosion-resistant pipelines. This increases the cost of amine production and contradicts the principles of green chemistry.

[0005] CN117417257A discloses a method for catalytic hydrogenation to synthesize amine compounds, belonging to the field of organic synthesis technology. The method includes the following steps: mixing Raney nickel, a nitro compound, and a solvent, and reacting them under a hydrogen atmosphere to obtain the amine compound. However, while using Raney nickel as a catalyst is cheaper than precious metals, it requires a hydrogen atmosphere (pressure 0.1-4.0 MPa), posing risks to hydrogen storage and transportation safety and requiring pressure-resistant equipment. Furthermore, Raney nickel has a limited number of reuses (approximately 15 times), resulting in high long-term costs. Additionally, it relies solely on nitro compounds as raw materials, depending on the nitro reduction pathway, and cannot directly utilize nitrogen (a cheap nitrogen source) and alcohols (common chemical raw materials) to synthesize amines, limiting the availability of raw materials. Moreover, it does not involve the amination reaction of simple alcohols such as C1-C3 alcohols, making it less suitable for the synthesis of low-carbon amine compounds. Therefore, developing a process for the direct conversion of nitrogen to amines is crucial. Summary of the Invention

[0006] This invention aims to develop a nitrogen-based, fully flow-through amination method using molybdenum-based materials. This method avoids the use of liquid ammonia as a raw material in traditional processes, directly using inexpensive nitrogen for conversion. Furthermore, the catalyst used has a wide range of raw materials and strong applicability to alcohol substrates. To suit practical industrial production, this method enables continuous flow production.

[0007] The technical solution provided by this invention is as follows:

[0008] <First Aspect>

[0009] A nitrogen-based, fully flow-through amination method for molybdenum-based materials includes the following steps:

[0010] S1. Pretreatment of molybdenum-based materials in a reducing atmosphere;

[0011] S2. The pretreated molybdenum-based material is subjected to high-temperature nitriding treatment in a nitriding gas atmosphere at a first temperature to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride.

[0012] S3. After the ambient temperature is lowered to the second temperature, alcohol vapor is introduced to contact the molybdenum nitride catalyst to carry out an amination reaction and generate amine products.

[0013] S4. The amine products are continuously collected using an acidic absorption solution;

[0014] S5. Repeat steps S2-S4 to achieve continuous production.

[0015] The specific steps of S1 are as follows: molybdenum-based material is loaded into a reactor, a mixture of N2 and H2 gas (N2:H2 volume ratio is 1:(1-4)) is introduced, the total flow rate is 50-80 mL / min, the temperature is increased to 550-650℃ at 1-20℃ / min and held for 10-120 min to remove the oxide layer on the surface of the molybdenum-based material and expose the low-valence molybdenum.

[0016] The molybdenum-based material is selected from one or more of molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate.

[0017] In step S2, the high-temperature nitriding temperature is 400-700℃, the heating rate is 5-10℃ / min, and the holding time is 10-120min.

[0018] And / or, the nitriding gas comprises a mixture of N2 and H2. The N2:H2 volume ratio is 1:(1-4).

[0019] In S3, the second temperature (i.e., the amination reaction temperature) is 100-300℃ (preferably 250℃), and the pressure is 0.1-5MPa.

[0020] The amine compounds include at least one of ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, and tripropylamine.

[0021] The alcohol is a C1-C3 alcohol (the alcohol is methanol, ethanol or n-propanol, preferably methanol);

[0022] In S4, the acidic absorption solution is a 1-2 mmol / L dilute sulfuric acid solution.

[0023] <Second aspect>

[0024] A method for synthesizing amine compounds based on molybdenum-based materials includes the following steps:

[0025] 1) Pretreatment of molybdenum-based materials in a reducing atmosphere;

[0026] 2) The pretreated molybdenum-based material is subjected to high-temperature nitriding treatment in a nitriding gas atmosphere at a first temperature to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride.

[0027] 3) After the ambient temperature is lowered to the second temperature, alcohol vapor is introduced to contact the molybdenum nitride catalyst to carry out an amination reaction and generate amine products;

[0028] 4) The amine products are continuously collected using an acidic absorption solution;

[0029] Step 1) The specific steps are as follows: load the molybdenum-based material into the reactor, introduce a mixed gas of N2 and H2 (N2:H2 volume ratio is 1:(1-4)), the total flow rate is 50-80 mL / min, heat to 550-650℃ at 1-20℃ / min and hold for 10-120 min to remove the oxide layer on the surface of the molybdenum-based material and expose the low-valence molybdenum.

[0030] The molybdenum-based material includes one or more of the following: molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate.

[0031] In step 2), the high-temperature nitriding temperature is 400-700℃, the heating rate is 5-10℃ / min, and the holding time is 10-120min.

[0032] And / or, the nitriding gas comprises a mixture of N2 and H2. The N2:H2 volume ratio is 1:(1-4).

[0033] The second temperature (amination reaction) is 100-300℃ (preferably 250℃), and the pressure is 0.1-5MPa.

[0034] The amine compounds include at least one of ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, or tripropylamine.

[0035] The alcohol is a C1-C3 alcohol (the alcohol is methanol, ethanol or n-propanol, preferably methanol);

[0036] In step 3), the acidic absorption solution is a 1-2 mmol / L dilute sulfuric acid solution.

[0037] <Third aspect>

[0038] A method for preparing a molybdenum nitride catalyst includes the following steps:

[0039] A. Pretreatment of molybdenum-based materials in a reducing atmosphere;

[0040] B. The pretreated molybdenum-based material is subjected to high-temperature nitriding in a nitriding atmosphere to form a molybdenum nitride catalyst with a core-shell structure.

[0041] The molybdenum-based material includes one or more of the following: molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate.

[0042] The nitriding atmosphere comprises a mixture of N2 and H2. The volume ratio of N2 to H2 is 1:(1-4).

[0043] Step A specifically involves loading a molybdenum-based material into a reactor, introducing a mixture of N2 and H2 gas (N2:H2 volume ratio of 1:(1-4)), with a total flow rate of 50-80 mL / min, heating to 550-650℃ at 1-20℃ / min and holding at that temperature for 10-120 min to remove the oxide layer on the surface of the molybdenum-based material and expose low-valence molybdenum.

[0044] The nitriding atmosphere is nitrogen, ammonia, or a mixture thereof.

[0045] In this step, the nitriding treatment temperature is 400-700℃, the heating rate is 5-10℃ / min, and the holding time is 10-120min.

[0046] The molybdenum nitride catalyst has a core-shell structure, wherein the core is metallic molybdenum or low-valent molybdenum oxide, and the outer shell is molybdenum nitride (MoN). X ), where 0.2 < X < 0.4, and the particle size is 30-50 nm.

[0047] <Fourth Aspect>

[0048] A molybdenum nitride catalyst is prepared by the method described above.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] 1. To address the contradiction between the demanding nitrogen fixation conditions (requiring high temperatures) and the easy thermal decomposition of alcohols during the coupling process of ammonia synthesis with other reactions, a chemical chain cycle technology is innovatively introduced. Through a stepwise strategy of high-temperature nitrogen fixation and low-temperature amine production, the thermal decomposition of alcohol raw materials is effectively avoided while ensuring efficient nitrogen fixation, significantly improving the stability of the reaction system.

[0051] 2. This invention innovatively designs a core-shell catalyst with a molybdenum core and a molybdenum nitride shell. Through the electronic effects and geometric confinement of the core-shell interface, it achieves synergistic regulation of active site stability and reaction selectivity. This hierarchical structure not only endows the catalyst with structural rigidity during high-temperature nitrogen fixation, but also enhances the activation ability of nitrogen species through the lattice matching effect of the molybdenum nitride shell, while suppressing side reaction pathways. From the perspective of material design, it breaks through the technical bottleneck of rapid activity decay and poor selectivity of traditional catalysts in continuous amination processes, providing a new material basis and theoretical foundation for the efficient and continuous production of amine compounds.

[0052] 3. The catalyst has a simple and inexpensive composition, strong versatility, and is applicable to all molybdenum-containing materials. It consists of only molybdenum and nitrogen, and its preparation method is simple, convenient, and scientifically sound. It is suitable for molybdenum-based materials such as molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate, demonstrating extremely strong versatility. These molybdenum-based materials, especially the molybdenum oxide series, are widely available and inexpensive, offering a cost advantage.

[0053] 4. It has strong applicability to alcohols, such as methanol, ethanol, and n-propanol. Different amines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, and tripropylamine can be prepared according to requirements. The appropriate molybdenum-based catalyst and alcohol can be selected according to the desired product.

[0054] 5. All processes of this invention can be realized in a fixed-bed reactor in a fully flowable manner. By continuously switching the catalyst between high and low temperatures, continuous production is achieved, which is superior to intermittent production methods such as homogeneous catalysis, ball milling, and autoclave methods, and has a higher space-time yield. Existing technologies require the separation of ammonia gas through a synthetic ammonia process, which is an energy-intensive process. At the same time, the transportation of ammonia gas is characterized by high cost, high risk, and high pollution. This invention avoids the separation and transportation of ammonia gas and directly realizes the preparation of downstream products, which is energy-saving, environmentally friendly, cost-reducing, and efficiency-enhancing. Attached Figure Description

[0055] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0056] Figure 1 A schematic diagram comparing the existing industrial processes for preparing amines with the method presented in this invention;

[0057] Figure 2 This is a diagram illustrating the reaction steps for synthesizing amines in this invention;

[0058] Figure 3 The X-ray diffraction pattern of molybdenum powder after nitridation in Example 1;

[0059] Figure 4 This is a transmission electron microscope (TEM) image of molybdenum powder after nitridation in Example 1. Detailed Implementation

[0060] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0061] This invention provides a nitrogen-based, fully flow-through amination method for molybdenum-based materials, comprising the following steps:

[0062] S1. Pretreatment of molybdenum-based materials in a reducing atmosphere;

[0063] S2. The pretreated molybdenum-based material is subjected to high-temperature nitriding treatment in a nitriding gas atmosphere at a first temperature to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride.

[0064] S3. After the ambient temperature is lowered to the second temperature, alcohol vapor is introduced to contact the molybdenum nitride catalyst to carry out an amination reaction and generate amine products.

[0065] S4. The amine compounds are continuously collected using an acidic absorption solution;

[0066] S5. Repeat steps S2-S4 to achieve continuous production.

[0067] Figure 1 A schematic diagram comparing the existing industrial processes for preparing amines with the method presented in this invention.

[0068] Example 1

[0069] Weigh 500 mg of molybdenum powder and grind it in a mortar for 10 minutes. Load the molybdenum powder onto a quartz reactor, with the sample supported by quartz wool. Mount the quartz reactor on a fixed bed.

[0070] 1. Pretreatment stage: A mixture of nitrogen and hydrogen (N2:H2 = 1:3) is introduced at a total flow rate of 60 mL / min, and the temperature is increased to 550℃ at a rate of 10℃ / min. The temperature is held at 550℃ for 30 min to remove the surface oxide layer.

[0071] 2. Nitriding stage: Adjust the temperature to 400-700℃ at a rate of 5℃ / min for nitriding (500℃ is used in this example), hold for 30 minutes to complete the nitriding stage, and use the same atmosphere as in step 1.

[0072] Characterization of the nitrided sample revealed that it consisted of two phases, such as... Figure 3 As shown, the sample retains its main molybdenum structure, with an outer layer of molybdenum nitride, indicating a partially nitrided core-shell structure. The outer shell is encapsulated molybdenum nitride, while the inner layer remains metallic molybdenum. Figure 4 As shown, the particle size of the nitrided sample is approximately 30-50 nm.

[0073] 3. Amination stage: The temperature of the nitrided sample is reduced to 100-300℃, preferably 250℃, at a rate of 5℃ / min, and then methanol vapor (0.1MPa, 4mmol / h) is introduced. -1 ).

[0074] 4. Collect the exhaust gas at the tail gas outlet with a 1 mmol / L dilute sulfuric acid solution. The generated ammonia, monomethylamine, dimethylamine, and trimethylamine can all be collected to form ammonium sulfate, monomethylamine sulfate, dimethylamine sulfate, and trimethylamine sulfate salts.

[0075] The collected solution was sent to ion chromatography for detection to identify the products. Under the conditions of 250℃ and 0.1 MPa, the production rates of ammonia, monomethylamine, dimethylamine, and trimethylamine in the first ten minutes were 6.4 μmol / g / h, 4.3 μmol / g / h, 0.8 μmol / g / h, and 141.6 μmol / g / h, respectively. After 30 minutes, the reaction was basically complete, and the final yields of ammonia, monomethylamine, dimethylamine, and trimethylamine were 1.4 μmol / g, 1.8 μmol / g, 0.4 μmol / g, and 36.0 μmol / g, respectively, with an amine selectivity of 96.4%.

[0076] After the amination reaction is completed (repeat steps 2-4), the temperature is raised for nitridation, and then cooled for amination again to complete one cycle, continuously producing amines.

[0077] like Figure 2 The high-temperature nitriding and low-temperature amination shown are both carried out on a catalyst bed.

[0078] After five cycles (nitriding temperature of 500℃ and amination temperature of 250℃), the catalyst performance did not decrease significantly. XRD characterization showed that the catalyst phase composition remained unchanged before and after the reaction, still exhibiting a structure of molybdenum nitride coating on the molybdenum surface, demonstrating the stability of the catalyst and the practicality of the method.

[0079] Example 2

[0080] Example 2 is based on the method of Example 1, except that methanol is replaced with ethanol. The final yields of ammonia, monoethylamine, diethylamine and triethylamine are 4.8 μmol / g, 1.6 μmol / g, 3.4 μmol / g and 19.8 μmol / g, respectively, with an amine selectivity of 83.7%.

[0081] Example 3

[0082] Example 3 is based on the method of Example 1, except that methanol is replaced with n-propanol. The final yields of ammonia, monopropylamine, dipropylamine and tripropylamine are 4.8 μmol / g, 1.8 μmol / g, 3.1 μmol / g and 5.8 μmol / g, respectively, with an amine selectivity of 69.0%.

[0083] Example 4

[0084] Example 4 is based on the method of Example 1, but the molybdenum powder is replaced with molybdenum dioxide and the pre-activation temperature is adjusted to 650°C. The final yields of ammonia and trimethylamine are 3.4 μmol / g and 22.4 μmol / g, respectively, with an amine selectivity of 87.8%. Due to the low content, monomethylamine and dimethylamine products were not detected.

[0085] Example 5

[0086] Example 5 is based on the method of Example 1, but the molybdenum powder is replaced with molybdenum dioxide, the methanol is replaced with ethanol, and the pre-activation temperature is adjusted to 650℃. The final yields of ammonia, monoethylamine, diethylamine and triethylamine are 9.7 μmol / g, 4.4 μmol / g, 1.8 μmol / g and 9.1 μmol / g, respectively, and the amine selectivity is 61.2%.

[0087] Example 6

[0088] Example 6 is based on the method of Example 1, but the molybdenum powder is replaced with molybdenum dioxide, the methanol is replaced with n-propanol, and the pre-activation temperature is adjusted to 650℃. The final yields of ammonia, monopropylamine and tripropylamine are 4.6 μmol / g, 2.1 μmol / g and 0.9 μmol / g, respectively, with an amine selectivity of 39.5%. Due to the low content, dipropylamine product was not detected.

[0089] Example 7

[0090] Example 7 is based on the method of Example 1, but the molybdenum powder is replaced with molybdenum trioxide and the pre-activation temperature is adjusted to 650°C. The final yields of ammonia and trimethylamine are 7.4 μmol / g and 9.0 μmol / g, respectively, with an amine selectivity of 54.9%. Due to the low content, monomethylamine and dimethylamine products were not detected.

[0091] Example 8

[0092] Example 8 was based on the method of Example 1, but with molybdenum powder replaced by molybdenum trioxide, methanol replaced by ethanol, and the pre-activation temperature adjusted to 650°C. The final yields of ammonia, monoethylamine, and triethylamine were 6.2 μmol / g, 0.9 μmol / g, and 3.5 μmol / g, respectively, with an amine selectivity of 40.7%. Due to the low content, diethylamine was not detected.

[0093] Example 9

[0094] Example 9, based on the method of Example 1, replaced molybdenum powder with molybdenum trioxide, methanol with n-propanol, and adjusted the pre-activation temperature to 650°C. The final yields of ammonia, monopropylamine, and tripropylamine were 5.8 μmol / g, 1.1 μmol / g, and 11.8 μmol / g, respectively, with an amine selectivity of 68.9%. Due to the low content, dipropylamine was not detected.

[0095] Except for tripropylamine, which was detected by NMR because it was outside the detection range of ion chromatography, all other products were detected by ion chromatography.

[0096] Comparative Example 1

[0097] Comparative Example 1 (without nitriding step): Amination reaction was carried out directly using unnitrided molybdenum powder (500 mg), and other conditions were the same as in Example 1.

[0098] Result: No ammonia or amine products were detected.

[0099] Conclusion: The nitriding step is crucial for the formation of an active core-shell structure (Mo / MoN). X It is crucial that unnitrided molybdenum has no catalytic activity.

[0100] Comparative Example 2

[0101] Steps: The nitriding stage temperature is set to 300℃ (other conditions are the same as in Example 1).

[0102] Result: Insufficient nitriding degree (MoN) X (The shell layer is relatively thin). The final yields of ammonia and amine products were 4.7 μmol / g and 2.4 μmol / g, respectively, with an amine selectivity of 33.8%. Compared with Example 1, the yield and selectivity were significantly reduced.

[0103] Conclusion: Low-temperature nitriding leads to insufficient formation of the active phase, affecting CN coupling efficiency.

[0104] Comparative Example 3

[0105] Steps: The nitriding stage temperature is set to 800℃ (other conditions are the same as in Example 1).

[0106] Results: The final yields of ammonia and amine products were 1.4 μmol / g and 0.5 μmol / g, respectively, with an amine selectivity of 26.3%. Compared with Example 1, the yield and selectivity were significantly reduced.

[0107] Conclusion: Excessive temperature leads to over-nitriding and reduced formation of the active phase, therefore a suitable nitriding temperature is required.

[0108] Comparative Example 4

[0109] Step: The amination stage temperature is set to 80°C (other conditions are the same as in the example).

[0110] Result: No ammonia or amine products were detected.

[0111] Conclusion: Low temperature is insufficient to activate the reaction between methanol and surface nitrogen species.

[0112] Comparative Example 5

[0113] Procedure: The amination stage temperature was set to 400°C (other conditions were the same as in Example 1).

[0114] Results: The final ammonia concentration was 47.4 μmol / g, and no amine products were detected.

[0115] Conclusion: High temperature caused methanol to decompose, and no amines were detected.

[0116] Comparative Example 6

[0117] Procedure: Amination is carried out in a closed static reactor (without gas flow), with methanol vapor injected in one go.

[0118] Results: The product distribution trend was similar to that in Example 1 for the first 10 minutes, but the trimethylamine production stagnated after 15 minutes (only 13.9 μmol / g). The amine selectivity was 89.7%, which was also slightly lower than that in Example 1.

[0119] Conclusion: The flow system facilitates product desorption and mass transfer, avoids blockage of active sites, and is easy to operate, which is beneficial for subsequent separation.

[0120] This invention discloses a method for the direct, fully fluidized conversion of nitrogen gas into amines using molybdenum-based materials. Molybdenum serves as the catalytic active center, first undergoing high-temperature nitridation to crack nitrogen gas and generate active nitrogen species, which then react with alcohols to produce the corresponding amines. The catalysts used in this method are all commercially available molybdenum powder, molybdenum dioxide, and molybdenum trioxide, and the alcohols used are all common alcohols, such as methanol, ethanol, and propanol, demonstrating the method's versatility. The produced amines, such as methylamine, ethylamine, and propylamine, have high added value and are widely used in medicine, agriculture, dyeing, and sensing fields. Compared to the traditional process route that relies on liquid ammonia to prepare amines, the method of this invention has advantages such as lower cost, less pollution, and easier operation.

[0121] The innovative method data process route in this invention should be noted that the examples listed are only for demonstrating the effectiveness and universality of the route, and the scope of protection should not be limited to the content of the examples.

[0122] The process parameters of the method in this invention can be optimized by those skilled in the art within the scope of the claims, but this does not affect the substantive content of the invention.

[0123] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A nitrogen-based full-flow amination method for molybdenum-based materials, characterized in that, Includes the following steps: S1. Pretreatment of molybdenum-based materials in a reducing atmosphere; S2. The pretreated molybdenum-based material is subjected to high-temperature nitriding treatment in a nitriding gas atmosphere at a first temperature to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride. S3. After the ambient temperature is lowered to the second temperature, alcohol vapor is introduced to contact the molybdenum nitride catalyst to carry out an amination reaction and generate amine products. S4. The amine products are continuously collected using an acidic absorption solution; S5. Repeat steps S2-S4 to achieve continuous production.

2. The amination method according to claim 1, characterized in that, The specific steps of S1 are as follows: load the molybdenum-based material into the reactor, introduce a mixed gas of N2 and H2 at a total flow rate of 50-80 mL / min, heat the material to 550-650℃ at a rate of 1-20℃ / min and hold it for 10-120 min to remove the oxide layer on the surface of the molybdenum-based material.

3. The amination method according to claim 1, characterized in that, The molybdenum-based material is selected from one or more of molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate.

4. The amination method according to claim 1, characterized in that, In step S2, the high-temperature nitriding temperature is 400-700℃, the heating rate is 5-10℃ / min, and the holding time is 10-120min; And / or, the nitriding gas includes a mixture of N2 and H2.

5. The amination method according to claim 1, characterized in that, The amination reaction temperature is 100-300℃, and the pressure is 0.1-5MPa; And / or, the amine compound includes at least one of ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, and tripropylamine.

6. The amination method according to claim 1, characterized in that, The alcohols are C1-C3 alcohols.

7. A method for synthesizing amine compounds based on molybdenum-based materials, characterized in that, Includes the following steps: 1) Pretreatment of molybdenum-based materials in a reducing atmosphere; 2) The pretreated molybdenum-based material is subjected to high-temperature nitriding treatment in a nitriding gas atmosphere at a first temperature to form a molybdenum nitride catalyst with a core-shell structure, wherein the core layer is metallic molybdenum and the shell layer is molybdenum nitride. 3) After the ambient temperature is lowered to the second temperature, alcohol vapor is introduced to contact the molybdenum nitride catalyst to carry out an amination reaction and generate amine products; 4) The amine products are continuously collected using an acidic absorption solution.

8. The synthesis method according to claim 7, characterized in that, Step 1) The specific steps are as follows: load the molybdenum-based material into the reactor, introduce a mixed gas of N2 and H2 at a total flow rate of 50-80 mL / min, heat to 550-650℃ at a rate of 1-20℃ / min and hold for 10-120 min to remove the oxide layer on the surface of the molybdenum-based material and expose the low-valence molybdenum. And / or, the molybdenum-based material is selected from one or more of molybdenum powder, molybdenum dioxide, molybdenum trioxide, ammonium molybdate, molybdenum carbide, molybdenum nitride, molybdenum chloride, and molybdenum acetylacetonate; And / or, in step 2), the high-temperature nitriding temperature is 400-700℃, the heating rate is 5-10℃ / min, and the holding time is 10-120min.

9. A method for preparing a molybdenum nitride catalyst for amination reactions, characterized in that, Includes the following steps: A. Pretreatment of molybdenum-based materials in a reducing atmosphere; B. The pretreated molybdenum-based material is subjected to high-temperature nitriding in a nitriding atmosphere to form a molybdenum nitride catalyst with a core-shell structure.

10. A molybdenum nitride catalyst, characterized in that, It is prepared by the method described in claim 9.

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