A catalyst for c2-c4 lower aliphatic amines, its preparation and use

Abstract

The application discloses a catalyst for C2-C4 low-grade aliphatic amine and a preparation method and application thereof, and particularly relates to the technical field of catalysts. The catalyst comprises 8-18% of NiO, 2-6% of MgO and 0.5-3% of ZnO in mass percentage, and a composite carrier formed by MCM-41 molecular sieve and macroporous silicon dioxide is used as the balance, wherein the mass ratio of the MCM-41 to the silicon dioxide is 4:0.1-2.0. The preparation method comprises the following steps: synthesizing MCM-41 powder through a template agent self-assembly, mixing the MCM-41 powder with a pore-forming agent and a binder to form a composite carrier, loading a nitrate solution of nickel, magnesium and zinc by using an equal-volume impregnation method, and obtaining the final catalyst through drying and calcination. The catalyst has extremely high catalytic activity and selectivity for the amination reaction of ethanol, isopropyl alcohol, n-propyl alcohol and n-butyl alcohol under mild reaction conditions.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and specifically to a catalyst for C2-C4 lower aliphatic amines, its preparation method, and its application. Background Technology

[0002] Lower aliphatic amines, such as ethylamine, propylamine, isopropylamine, and butylamine, are indispensable key intermediates in the fine chemical industry. Their applications are extremely wide-ranging, including the synthesis of antihistamines and other pharmaceuticals in the pharmaceutical industry, the preparation of herbicides and fungicides in the pesticide industry, the synthesis of quaternary ammonium salt surfactants in chemical production, and as additives in etching solutions in electronic chemicals. Currently, the main industrial route for large-scale production of these lower aliphatic amines is the catalytic amination of alcohols, where the corresponding alcohol reacts with ammonia in a hydrogen atmosphere under the action of a specific catalyst. This reaction process is generally considered to follow a three-step mechanism: first, the alcohol molecule dehydrogenates at the active site of the catalyst to form the corresponding aldehyde or ketone; subsequently, this carbonyl intermediate undergoes nucleophilic addition with ammonia and dehydration to form an imine; finally, the imine intermediate is hydrogenated in a hydrogen atmosphere to obtain the target amine product.

[0003] In this process, the performance of the catalyst is the core factor determining the efficiency, economy, and product quality of the entire reaction process. It directly affects the conversion rate of the raw materials, the selectivity of the target amine product, and the energy consumption and separation and purification costs. However, the various catalyst systems disclosed in the prior art all have limitations to varying degrees, which restricts the further optimization and industrial application of this process.

[0004] First, while some early catalyst systems avoided the use of precious metals, they generally suffered from the problem of balancing activity and selectivity. These catalysts often led to incomplete conversion of the starting alcohol or low selectivity for the target primary amine, resulting in complex reaction networks and the formation of a considerable proportion of secondary amines, tertiary amines, and oxygen-containing heterocyclic byproducts. The boiling points of these byproducts are close to those of the target amine, causing subsequent product separation and purification processes to be lengthy, significantly increasing energy consumption, and affecting the purity of the final product.

[0005] Secondly, to improve performance, some technical solutions introduce precious metals as active components. While these catalysts can exhibit certain activity under specific conditions, their high material costs severely weaken the economic competitiveness of the process, making them difficult to promote and apply in the production of bulk chemicals where cost is a primary concern. Furthermore, other catalyst systems rely on complex multi-component formulations or precisely structured supports, whose preparation processes are cumbersome, demanding, and lack reproducibility, resulting in poor batch-to-batch stability of catalyst performance. This also poses a significant challenge to industrial-scale production.

[0006] Furthermore, many reported catalysts require stringent reaction conditions to achieve high conversion rates, such as excessively high reaction temperatures or hydrogen pressures. While high temperatures increase reaction rates, they also exacerbate a series of side reactions, such as alcohol dehydration to ether formation, alcohol-aldehyde condensation, and deep alkylation of amines. This leads to increased byproduct content, accelerated catalyst deactivation due to carbon deposition, and higher demands on equipment materials.

[0007] Furthermore, although some studies have reported high alcohol conversion and amine yields under optimized conditions, there is a lack of sufficient disclosure and assessment of the types and amounts of key impurities generated in the reaction system. These uncontrolled impurities, such as alcohol etherification products, higher amines, and amide compounds, are also important indicators affecting product quality and the overall performance of the catalyst, and their presence may have adverse effects on downstream applications.

[0008] In summary, developing a catalyst that combines high activity, high primary amine selectivity, excellent stability, low manufacturing cost, mild adaptability to reaction conditions, and the ability to effectively suppress the formation of various byproducts, thereby simplifying subsequent separation processes and improving product quality, has become a key technical problem that those skilled in the art have long been committed to solving. Summary of the Invention

[0009] To overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a catalyst for C2-C4 lower fatty amines, its preparation method and application, which solves the problems of low conversion rate, low yield, many side reactions, difficulty in product separation and purification caused by reaction intermediates nitriles and high-boiling-point amine impurities, and the cracking of C2-C4 lower fatty alcohols to generate low-boiling-point alkanes.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A catalyst for C2-C4 lower aliphatic amines, specifically comprising the following components:

[0012] NiO: 8wt%~18wt%;

[0013] MgO: 2wt%~6wt%;

[0014] ZnO: 0.5wt%~3wt%;

[0015] Composite carrier: The remainder consists of MCM-41 molecular sieve and macroporous silica.

[0016] A catalyst for C2-C4 low-grade aliphatic amines, characterized in that, preferably, the mass ratio of MCM-41 molecular sieve to macroporous silica is 4:0.1-2.0.

[0017] A method for preparing a catalyst of C2-C4 lower aliphatic amines includes the following steps:

[0018] S1: Dissolve hexadecyltrimethylammonium bromide in deionized water at 35°C and stir continuously until the solution is clear. After the solution temperature drops to 25°C, add sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to adjust the pH of the solution. Place the resulting sol in an oven to dry for 24 hours, then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace to calcine to prepare MCM-41 powder.

[0019] S2: Mix the MCM-41 powder obtained in S1, macroporous silica powder as a pore-forming agent, and guar gum powder, add nitric acid solution as a binder, and knead, extrude, dry and calcine to obtain the shaped MCM-41 / macroporous silica composite carrier.

[0020] S3: Ni(NO3)2.6H2O, Mg(NO3)2.6H2O and Zn(NO3)2.6H2O are dissolved by water bath heating to obtain a mixed salt solution. Then, the mixed salt solution is impregnated into the MCM-41 support in equal volume. After impregnation, it is placed in an oven to dry and finally calcined to obtain the NiO / MgO / ZnO / MCM-41 catalyst.

[0021] Preferably, in S1, 80-120 parts by weight of hexadecyltrimethylammonium bromide are dissolved in deionized water, and then 400-450 parts by weight of sodium metasilicate nonahydrate are added and dissolved therein.

[0022] Preferably, in S1, the pH of the solution is rapidly adjusted to 10.5±0.1 using a 10% sulfuric acid solution to obtain a sol. Then, it is dried at 80±5℃ for 24 hours, washed, filtered, and air-dried naturally, and finally calcined at 550±50℃ for 5 hours.

[0023] Preferably, MCM-41 powder and macroporous silica powder prepared by S1 are added to S2 in a weight ratio of 4:0.1 to 2.0.

[0024] Preferably, guar gum powder accounting for 2% of the total mass of MCM-41 and macroporous silica is added. After mixing evenly, 50±5mL of 5% nitric acid solution is added, and finally the mixture is calcined at 350-550℃ for 2-8 hours.

[0025] Preferably, in step S3, Ni(NO3)2.6H2O, Mg(NO3)2.6H2O and Zn(NO3)2.6H2O are placed at 30-80°C to obtain a salt solution.

[0026] Preferably, after impregnation in S3, the catalyst is dried at 100-150℃ for 6-16 hours and then calcined at 450±100℃ for 2-8 hours to obtain the NiO / MgO / ZnO / MCM-41 catalyst.

[0027] Application of a catalyst for C2-C4 lower aliphatic amines:

[0028] The NiO / MgO / ZnO / MCM-41 catalyst converts ethanol, isopropanol, n-propanol, and n-butanol into ethylamine, isopropylamine, n-propylamine, and n-butylamine, respectively.

[0029] The technical effects and advantages of this invention regarding a catalyst for C2-C4 lower aliphatic amines, its preparation method, and its application are as follows:

[0030] 1. In this invention, the catalyst support is made of MCM-41 with a high specific surface area, which can make the active components highly dispersed on the support. The macroporous silica forms through channels, which enhances the mass transfer efficiency and improves the activity of the catalyst. The highly active catalyst can improve the conversion rate of fatty alcohols and increase the yield of fatty amines on the one hand, and reduce the reaction temperature and reduce the generation of impurities on the other hand.

[0031] 2. In this invention, the addition of MgO and ZnO forms a Ni-Mg-Zn ternary system. MgO enhances the reducibility and anti-carbon deposition ability of Ni through electronic effects; ZnO inhibits the sintering of Ni particles through geometric effects and selectively blocks side reaction pathways.

[0032] 3. In this invention, the addition of MgO and ZnO adjusts the acidity and alkalinity of the catalyst. With suitable catalyst acidity and alkalinity, the synergistic effect of the Ni-Mg-Zn ternary system reduces the occurrence of side reactions.

[0033] 4. In this invention, the catalyst support MCM-41 is a mesoporous material with a confinement effect. By using a suitable confinement material, the generation of impurities, especially macromolecular impurities, can be reduced.

[0034] 5. Under optimized reaction conditions, this invention achieves the following results in the ethanol amination reaction: ethanol conversion rate of 99.7%, ethylamine selectivity of 99.8%, and methane content of 0.05%; and butanol amination reaction: n-butanol conversion rate as high as 98.8%, n-butylamine selectivity of 97.9%, and the reaction products contain the following impurities: n-butyl ether content of 0.05%, N-isobutyl-N,N-di-n-butylamine content of 0.15%, and N-n-butylbutyramide content of 0.1%.

[0035] 6. The catalyst of this invention is suitable for various ammoniation reactions, especially for the preparation of C2-C4 low aliphatic amines. It has a wide range of applications and strong process compatibility. It is suitable for existing industrial equipment without complex modifications, which can improve production efficiency, reduce production costs, and save investment.

[0036] 7. The catalyst of this invention has high catalytic activity and selectivity, and the amount of intermediate products such as nitriles, higher aliphatic amines and alkanes generated is extremely small.

[0037] 8. In this invention, Ni is used as the main active component of the catalyst instead of precious metals, which reduces the cost of the catalyst. Attached Figure Description

[0038] Figure 1 This is a flowchart of a C2-C4 low-grade aliphatic amine catalyst and its preparation method proposed in this invention. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] Example 1

[0042] This embodiment provides a method for preparing a catalyst of C2-C4 lower aliphatic amines, the specific implementation steps of which include:

[0043] Experimental materials:

[0044] 100g hexadecyltrimethylammonium bromide, 440g sodium metasilicate nonahydrate, 10% sulfuric acid solution, 20g silica powder, 1.6g guar gum powder, 5% nitric acid solution, 66.17g Ni(NO3)2.6H2O, 19.10g Mg(NO3)2.6H2O, 5.48g Zn(NO3)2.6H2O.

[0045] Experimental objective:

[0046] Prepare NiO / MgO / ZnO / MCM-41 catalyst.

[0047] Experimental steps:

[0048] S1: Dissolve 100g of hexadecyltrimethylammonium bromide in 3700 mL of deionized water at 35℃ and stir continuously until the solution is clear. After the solution temperature drops to 25℃, add 440g of sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to quickly bring the pH of the solution to 10.5±0.1. Place the resulting sol in an oven at 80℃ and dry for 24 hours. Then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace at 550℃ for 5 hours to prepare MCM-41 powder.

[0049] S2: Take 40g of MCM-41 powder prepared in S1, add 20g of silica powder and 1.6g of guar gum powder, then add 50mL of 5% nitric acid, knead, extrude, dry, and then calcine at 450℃ for 4 hours to obtain the shaped MCM-41 carrier.

[0050] S3: In a water bath at 60℃, 66.17g Ni(NO3)2.6H2O, 19.10g Mg(NO3)2.6H2O and 5.48g Zn(NO3)2.6H2O were dissolved in 70mL of water to obtain a mixed salt solution. Then, an equal volume of the mixed salt solution was impregnated into 78.5g MCM-41 support. After impregnation, it was dried in an oven at 120℃ for 12h, and finally calcined at 450℃ for 4h to obtain the NiO / MgO / ZnO / MCM-41 catalyst.

[0051] Experimental results:

[0052] The prepared NiO / MgO / ZnO / MCM-41 catalyst exhibited excellent performance in the ethanol amination reaction; the reaction was successful at a reaction temperature of 170℃, a pressure of 0.8 MPa, an ethanol:ammonia:hydrogen molar ratio of 1:5:4, and an ethanol space velocity of 0.4 h⁻¹. -1 Under these conditions, the ethanol conversion rate was 99.7%, the total selectivity of ethylamine was 99.8%, and the methane content was 0.05%.

[0053] Example 2

[0054] This embodiment provides a method for preparing a catalyst of C2-C4 low-grade aliphatic amines, adjusting the use of raw materials in the impregnation and roasting step, and the specific implementation steps include:

[0055] Experimental materials:

[0056] 100g hexadecyltrimethylammonium bromide, 440g sodium metasilicate nonahydrate, 10% sulfuric acid solution, 20g silica powder, 1.6g guar gum powder, 5% nitric acid solution, 66.17g Ni(NO3)2.6H2O.

[0057] Experimental objective:

[0058] Prepare catalysts lacking Mg(NO3)2.6H2O and Zn(NO3)2.6H2O.

[0059] Experimental steps:

[0060] S1: Dissolve 100g of hexadecyltrimethylammonium bromide in 3700 mL of deionized water at 35℃ and stir continuously until the solution is clear. After the solution temperature drops to 25℃, add 440g of sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to quickly bring the pH of the solution to 10.5±0.1. Place the resulting sol in an oven at 80℃ and dry for 24 hours. Then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace at 550℃ for 5 hours to prepare MCM-41 powder.

[0061] S2: Take 80g of MCM-41 powder prepared in S1, add 20g of silica powder and 1.6g of guar gum powder, then add 50mL of 5% nitric acid, knead, extrude, dry, and then calcine at 450℃ for 4 hours to obtain the shaped MCM-41 carrier.

[0062] S3: In a water bath at 60℃, 66.17g of Ni(NO3)2.6H2O was dissolved in 70mL of water to obtain a mixed salt solution. Then, an equal volume of the mixed salt solution was impregnated into 83g of MCM-41 support. After impregnation, it was placed in an oven at 120℃ and dried for 12h. Finally, it was calcined at 450℃ for 4h to obtain the NiO / MCM-41 catalyst.

[0063] Experimental results:

[0064] The prepared NiO / MCM-41 catalyst, lacking Mg and Zn promoters, exhibits poor performance in the ethanol amination reaction; under the same reaction conditions (170℃, 0.8 MPa, ethanol:ammonia:hydrogen molar ratio 1:5:4, ethanol space velocity 0.4 h⁻¹), its performance is significantly lower. -1 The ethanol conversion rate was 92.7%, the total selectivity of ethylamine was 95.8%, and the methane content was 0.18%.

[0065] Example 3

[0066] This embodiment provides a method for preparing a catalyst for C2-C4 lower aliphatic amines, which prepares a catalyst without using MCM-41 powder. The specific implementation steps include:

[0067] Experimental materials:

[0068] 100g silica powder, 2g guar gum powder, 5% nitric acid solution, 66.17g Ni(NO3)2.6H2O, 19.10g Mg(NO3)2.6H2O, 5.48g Zn(NO3)2.6H2O.

[0069] Experimental objective:

[0070] Prepare a catalyst that does not contain MCM-41 powder.

[0071] Experimental steps:

[0072] S1: Take 100g of silica powder and 2g of guar gum powder, mix them evenly, add 50mL of 5% nitric acid solution, knead, extrude, dry, and then calcine at 450℃ for 4 hours to obtain the shaped silica carrier.

[0073] S2: In a water bath at 60℃, 66.17g Ni(NO3)2.6H2O, 19.10g Mg(NO3)2.6H2O and 5.48g Zn(NO3)2.6H2O were dissolved in 70mL of water to obtain a mixed salt solution. Then, an equal volume of the mixed salt solution was impregnated into 78.5g of silica support. After impregnation, it was placed in an oven at 120℃ and dried for 12h. Finally, it was calcined at 450℃ for 4h to obtain the NiO / MgO / ZnO / SiO2 catalyst.

[0074] Experimental results:

[0075] The prepared NiO / MgO / ZnO / SiO2 catalyst without the MCM-41 support exhibited the worst performance in the ethanol amination reaction; under the same reaction conditions (reaction temperature 170℃, pressure 0.8 MPa, ethanol:ammonia:hydrogen molar ratio 1:5:4, ethanol space velocity 0.4 h⁻¹), it was the worst performing catalyst. -1 The ethanol conversion rate was 85.7%, the total selectivity of ethylamine was 88.3%, and the methane content was 0.5%.

[0076] Example 4

[0077] This embodiment provides a method for preparing a catalyst of C2-C4 low-grade aliphatic amines. The method involves adjusting the amount of raw materials used in the impregnation and roasting step. Specific implementation steps include:

[0078] Experimental materials:

[0079] 100g hexadecyltrimethylammonium bromide, 440g sodium metasilicate nonahydrate, 10% sulfuric acid solution, 20g silica powder, 1.6g guar gum powder, 5% nitric acid solution, 42.82g Ni(NO3)2.6H2O, 38.22g Mg(NO3)2.6H2O, 2.20g Zn(NO3)2.6H2O.

[0080] Experimental objective:

[0081] Prepare NiO / MgO / ZnO / MCM-41 catalyst.

[0082] Experimental steps:

[0083] S1: Dissolve 100g of hexadecyltrimethylammonium bromide in 3700 mL of deionized water at 35℃ and stir continuously until the solution is clear. After the solution temperature drops to 25℃, add 440g of sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to quickly bring the pH of the solution to 10.5±0.1. Place the resulting sol in an oven at 80℃ and dry for 24 hours. Then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace at 550℃ for 5 hours to prepare MCM-41 powder.

[0084] S2: Take 40g of MCM-41 powder prepared in S1, add 20g of silica powder and 1.6g of guar gum powder, then add 50mL of 5% nitric acid, knead, extrude, dry, and then calcine at 450℃ for 4 hours to obtain the shaped MCM-41 carrier.

[0085] S3: In a water bath at 60℃, 42.82g Ni(NO3)2.6H2O, 38.22g Mg(NO3)2.6H2O and 2.20g Zn(NO3)2.6H2O were dissolved in 70mL of water to obtain a mixed salt solution. Then, an equal volume of the mixed salt solution was impregnated into 82.4g MCM-41 support. After impregnation, it was placed in an oven at 120℃ and dried for 12h. Finally, it was calcined at 450℃ for 4h to obtain NiO / MgO / ZnO / MCM-41 catalyst, which is designated as catalyst 1.

[0086] Experimental results:

[0087] The prepared catalyst 1, NiO / MgO / ZnO / MCM-41, with a composition of 11% NiO, 6% MgO, and 2.2% ZnO, exhibited good performance in the amination reaction of n-butanol. It performed well at a reaction temperature of 170℃, a pressure of 0.8 MPa, a molar ratio of n-butanol:ammonia:hydrogen of 1:5:4, and a n-butanol space velocity of 0.3 h⁻¹. -1Under the specified conditions, the conversion rate of n-butanol was 96.6%, the selectivity of n-butylamine was 95.73%, and the content of impurities in the reaction product was 0.01% for n-butyl ether, 0.13% for N-isobutyl-N,N-di-n-butylamine, and 0.1% for N-n-butylbutyramide.

[0088] Example 5

[0089] This embodiment provides a method for preparing a catalyst of C2-C4 low-grade aliphatic amines, further adjusting the amount of raw materials used in the impregnation and calcination step. The specific implementation steps include:

[0090] Experimental materials:

[0091] 100g hexadecyltrimethylammonium bromide, 440g sodium metasilicate nonahydrate, 10% sulfuric acid solution, 20g silica powder, 1.6g guar gum powder, 5% nitric acid solution, 54.49g Ni(NO3)2.6H2O, 14.64g Mg(NO3)2.6H2O, 9.14g Zn(NO3)2.6H2O.

[0092] Experimental objective:

[0093] Prepare NiO / MgO / ZnO / MCM-41 catalyst.

[0094] Experimental steps:

[0095] S1: Dissolve 100g of hexadecyltrimethylammonium bromide in 3700 mL of deionized water at 35℃ and stir continuously until the solution is clear. After the solution temperature drops to 25℃, add 440g of sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to quickly bring the pH of the solution to 10.5±0.1. Place the resulting sol in an oven at 80℃ and dry for 24 hours. Then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace at 550℃ for 5 hours to prepare MCM-41 powder.

[0096] S2: Take 40g of MCM-41 powder prepared in S1, add 20g of silica powder and 1.6g of guar gum powder, then add 50mL of 5% nitric acid, knead, extrude, dry, and then calcine at 450℃ for 4 hours to obtain the shaped MCM-41 carrier.

[0097] S3: In a water bath at 60℃, 54.49g Ni(NO3)2.6H2O, 14.64g Mg(NO3)2.6H2O and 9.14g Zn(NO3)2.6H2O were dissolved in 70mL of water to obtain a mixed salt solution. Then, an equal volume of the mixed salt solution was impregnated into 82.4g MCM-41 support. After impregnation, it was placed in an oven at 120℃ and dried for 12h. Finally, it was calcined at 450℃ for 4h to obtain NiO / MgO / ZnO / MCM-41 catalyst, denoted as catalyst 2.

[0098] Experimental results:

[0099] The prepared catalyst 2, NiO / MgO / ZnO / MCM-41, with a composition of 14% NiO, 2.3% MgO, and 2.5% ZnO, exhibited excellent performance in the amination reaction of n-butanol. It performed well under the following conditions: reaction temperature 170℃, pressure 0.8 MPa, n-butanol:ammonia:hydrogen molar ratio 1:5:4, and n-butanol space velocity 0.3 h⁻¹. -1 Under the specified conditions, the conversion rate of n-butanol was 98.5%, the selectivity of n-butylamine was 97.62%, and the impurity content of n-butyl ether in the reaction product was 0.03%, the content of N-isobutyl-N,N-di-n-butylamine was 0.2%, and the content of N-n-butylbutyramide was 0.1%.

[0100] Example 6

[0101] This embodiment provides an application of a catalyst for C2-C4 lower aliphatic amines, and the specific implementation steps include:

[0102] Experimental materials:

[0103] Nitrogen and hydrogen.

[0104] Experimental objective:

[0105] To convert alcohols into amines.

[0106] Experimental steps:

[0107] S1: The catalyst is placed in a tubular fixed-bed reactor, and a nitrogen and hydrogen mixed gas (V:V=2:3) space velocity is 200h / h. -1 Reduced at 400℃ for 6 hours;

[0108] S2: Switch the mixed gas to a mixture of hydrogen and ammonia (V:V = 1:2), then adjust the reaction temperature to 160-180℃ and the reaction pressure to 0.5-1.0MPa;

[0109] S3: Subsequently, C2-C4 lower fatty alcohols are introduced, with a feed composition of alcohol:ammonia:hydrogen molar ratio of 1:2-7:3-7, a pressure of 0.3-1.2 MPa, and an alcohol space velocity of 0.15 h⁻¹. -1 ~0.6h -1 The reaction solution was collected after cooling, and the content of each component was analyzed by gas chromatography.

[0110] Note:

[0111] Ethanol reaction conditions: reaction temperature 170℃, reaction pressure 0.8MPa, feed ratio of alcohol:ammonia:hydrogen 1:5:4, 0.4h. -1 airspeed;

[0112] Isopropanol reaction conditions: reaction temperature 155℃, reaction pressure 0.5MPa, feed alcohol:ammonia:hydrogen molar ratio 1:5:4, 0.3h. -1 airspeed;

[0113] n-Propanol reaction conditions: reaction temperature 170℃, reaction pressure 0.5MPa, feed alcohol:ammonia:hydrogen molar ratio 1:5:4, 0.2h. -1 airspeed;

[0114] n-Butanol reaction conditions: reaction temperature 170℃, reaction pressure 0.8MPa, feed alcohol:ammonia:hydrogen molar ratio 1:5:4, 0.3h. -1 airspeed.

[0115] Experimental results: See Table 1 for details.

[0116]

[0117] This embodiment tested the performance of various catalysts in different alcohol amination reactions, and the results are shown in the table. As can be seen from the table, the NiO / MgO / ZnO / MCM-41 catalyst showed high conversion and high selectivity in the amination reactions of ethanol, isopropanol, n-propanol and n-butanol, while the catalysts lacking promoters or using different supports had poor performance.

[0118] Example 7

[0119] This embodiment provides an application of a catalyst for C2-C4 lower aliphatic amines, employing different feed compositions and alcohol space velocities. Specific implementation steps include:

[0120] Experimental materials:

[0121] Nitrogen and hydrogen.

[0122] Experimental objective:

[0123] To convert n-butanol to n-butanamine, different feed compositions and n-butanol space velocities are used.

[0124] Experimental steps:

[0125] S1: The catalyst is placed in a tubular fixed-bed reactor, and a nitrogen and hydrogen mixed gas (V:V=2:3) space velocity is 200h / h. -1 Reduced at 400℃ for 6 hours;

[0126] S2: Switch the mixed gas to a mixture of hydrogen and ammonia (V:V=1:2), then adjust the reaction temperature to 170℃ and the reaction pressure to 0.8MPa;

[0127] S3: Subsequently, various alcohols are introduced, with a feed composition of alcohol:ammonia:hydrogen molar ratio of 1:6:3, and an alcohol space velocity of 0.3 h⁻¹. -1 The reaction solution was collected after cooling, and the content of each component was analyzed by gas chromatography.

[0128] Experimental results: See Table 2 for details.

[0129]

[0130] Tests were conducted using different feed compositions and n-butanol space velocities; the reaction conditions were: reaction temperature 170℃, pressure 0.8 MPa, n-butanol:ammonia:hydrogen molar ratio 1:6:3, and n-butanol space velocity 0.3 h⁻¹. -1 Under the specified conditions, the conversion rate of n-butanol was 99.0%, the selectivity of n-butylamine was 98.12%, and the impurity content in the reaction product was 0.05% n-butyl ether, 0.15% N-isobutyl-N,N-di-n-butylamine, and 0.17% N-n-butylbutyramide.

[0131] Example 1, using a standard NiO / MgO / ZnO / MCM-41 catalyst formulation, achieved a conversion rate of up to 99.7% and an ethylamine selectivity of 99.8% in the ethanol amination reaction, while effectively controlling the methane byproduct to an extremely low level of 0.05%. This result fully demonstrates the significant synergistic effect between the ternary active components composed of Ni, Mg, and Zn and the MCM-41 support with its high specific surface area and regular mesoporous structure. This not only optimizes the electronic and geometric structure of the active center at the atomic level but also achieves efficient mass transfer between reactants and products on a macroscopic level, laying a solid foundation for the high performance of the catalyst.

[0132] Example 2, as a comparative case, deliberately removed the two key promoters, Mg and Zn, to prepare a simplified catalyst containing only Ni. Under the same reaction conditions, its ethanol conversion rate decreased to 92.7%, the ethylamine selectivity also decreased to 95.8%, while the methane production increased to 0.18%. This result clearly reveals that MgO and ZnO are not dispensable components. MgO effectively regulates the reducibility of Ni through its electronic effect and significantly enhances the catalyst's resistance to carbon deposition. ZnO, on the other hand, isolates the Ni active sites through its geometric effect, effectively inhibiting the high-temperature sintering and excessive aggregation of Ni particles. Together, they selectively block the pathways leading to side reactions such as deep dehydrogenation and C / C bond breaking.

[0133] Example 3 further explored its effect by replacing the support, and prepared a catalyst using ordinary macroporous silica instead of MCM-41. This catalyst had the worst performance, with an ethanol conversion rate of only 85.7%, a selectivity of 88.3%, and a methane content as high as 0.5%. This strongly demonstrates the unique value of MCM-41 mesoporous molecular sieve: its uniform pore structure not only provides highly dispersed anchoring sites for active components, but also produces a significant confinement effect. On the one hand, it promotes the activation and conversion of reactants, and on the other hand, it spatially hinders the formation and accumulation of bulky by-products, thereby improving the efficiency of the main reaction while inhibiting the generation of impurities at the source.

[0134] Example 4 adjusted the ratio of active components to prepare a catalyst with 11% NiO, 6% MgO, and 2.2% ZnO. In the amination reaction of n-butanol, the conversion rate was 96.6% and the selectivity was 95.73%. This formulation showed the positive effect of high MgO content in enhancing the basicity of the catalyst and inhibiting the side reaction of alcohol dehydration to form ethers. However, due to the relatively reduced content of NiO active component, it was slightly insufficient in pursuing the ultimate conversion rate.

[0135] Example 5 employed another optimized formulation to prepare a catalyst with a NiO content as high as 14%, MgO 2.3%, and ZnO 2.5%. This catalyst achieved an excellent conversion rate of 98.5% and a selectivity of 97.62% in the amination of n-butanol, indicating that the high Ni content provided ample active centers for the reaction, while the moderate contents of MgO and ZnO continued to play key co-catalytic and stabilizing roles. This formulation achieved a better balance between activity and selectivity, demonstrating that the performance potential of the catalyst can be further explored by finely controlling the component ratios.

[0136] Example 6 systematically evaluated the performance of the optimal catalyst NiO / MgO / ZnO / MCM-41 in the amination reactions of four C2-C4 fatty alcohols: ethanol, isopropanol, n-propanol, and n-butanol. The results showed that the catalyst exhibited universally high activity and high selectivity for all substrates, fully demonstrating its wide applicability and robust catalytic performance, which can meet the needs of continuous and efficient synthesis of various low-grade fatty amines in industrial production.

[0137] Example 7 focuses on the in-depth optimization of process conditions, exploring the amination performance of n-butanol under a higher ammonia-to-methanol ratio of 1:6. Under these conditions, the n-butanol conversion rate was further increased to 99.0%, and the n-butylamine selectivity reached 98.12%. This shows that the catalyst of the present invention not only has superior performance, but also has good adaptability to reaction conditions. It can meet different production goals by adjusting process parameters, demonstrating strong process compatibility and optimization potential.

[0138] This invention relates to a catalyst for the synthesis of C2-C4 lower aliphatic amines, its preparation method, and its application. The catalyst uses NiO, MgO, and ZnO as active components, supported on a composite support composed of MCM-41 molecular sieve and macroporous silica, wherein the mass ratio of MCM-41 to silica is 4:0.1–2.0. The preparation process mainly includes three steps: first, MCM-41 powder is synthesized through self-assembly using a template agent; second, MCM-41 is mixed with a pore-forming agent and a binder to form a composite support; finally, a nickel, magnesium, and zinc nitrate solution is loaded using an equal-volume impregnation method, followed by drying and calcination to obtain the final catalyst. This catalyst exhibits excellent catalytic activity and selectivity for the amination reactions of ethanol, isopropanol, n-propanol, and n-butanol under mild reaction conditions, with conversion rates exceeding 99% and primary amine selectivity exceeding 97%. The introduction of MgO and ZnO enhances the dispersibility and anti-carbon deposition ability of Ni, while the mesoporous structure of the MCM-41 support promotes mass transfer efficiency and inhibits by-product formation. This catalyst uses non-precious metals as the main active component, is low-cost, has a simple preparation process, and is suitable for existing industrial equipment. It effectively solves problems such as low conversion rates, numerous side reactions, and difficult separation in the production of low-grade aliphatic amines, and has broad industrial application prospects.

[0139] A comprehensive comparison of all embodiments and comparative examples demonstrates that the catalyst system provided by this invention successfully integrates multiple technical elements: Example 1 showcases the superior overall performance of the system; Examples 2 and 3, from the opposite perspective, confirm the indispensable functions of the Mg / Zn promoter and the MCM-41 support; Examples 4 and 5 illustrate that the proportion of active components is adjustable, providing flexibility for achieving specific application goals; Example 6 demonstrates its wide range of applications; and Example 7 reveals its potential for further performance optimization. Therefore, this invention, through the ingenious design of Ni-Mg-Zn ternary active sites and the organic combination of the large-pore MCM-41 support, successfully develops a catalyst that combines high activity, high primary amine selectivity, excellent stability, low byproduct formation, and wide applicability, effectively solving the long-standing technical bottleneck in the existing C2-C4 low-grade aliphatic amine production process where conversion rate, selectivity, impurity control, and cost-effectiveness are difficult to balance.

[0140] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0141] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A catalyst for C2-C4 lower aliphatic amines, characterized in that, Specifically, it includes the following components: NiO: 8wt%~18wt%; MgO: 2wt%~6wt%; ZnO: 0.5wt%~3wt%; Composite carrier: The remainder consists of MCM-41 molecular sieve and macroporous silica.

2. The catalyst for C2-C4 lower aliphatic amines as described in claim 1, characterized in that, The mass ratio of MCM-41 molecular sieve to macroporous silica is 4:0.1 to 2.

0.

3. A method for preparing a catalyst of C2-C4 lower aliphatic amines, characterized in that, Includes the following steps: S1: Dissolve hexadecyltrimethylammonium bromide in deionized water at 35°C and stir continuously until the solution is clear. After the solution temperature drops to 25°C, add sodium metasilicate nonahydrate and stir continuously until completely dissolved. Then add 10% sulfuric acid solution to adjust the pH of the solution. Place the resulting sol in an oven to dry for 24 hours, then wash, filter, and air dry naturally. Finally, place it in a constant temperature calcination furnace to calcine to prepare MCM-41 powder. S2: Mix the MCM-41 powder obtained in S1, macroporous silica powder as a pore-forming agent, and guar gum powder, add nitric acid solution as a binder, and knead, extrude, dry and calcine to obtain the shaped MCM-41 / macroporous silica composite carrier. S3: Ni(NO3)2.6H2O, Mg(NO3)2.6H2O and Zn(NO3)2.6H2O are dissolved by water bath heating to obtain a mixed salt solution. Then, the mixed salt solution is impregnated into the MCM-41 support in equal volume. After impregnation, it is placed in an oven to dry and finally calcined to obtain the NiO / MgO / ZnO / MCM-41 catalyst.

4. The method for preparing a catalyst for C2-C4 lower aliphatic amines as described in claim 3, characterized in that, In S1, 80-120 parts by weight of hexadecyltrimethylammonium bromide are dissolved in deionized water, and then 400-450 parts by weight of sodium metasilicate nonahydrate are added and dissolved therein.

5. The method for preparing a C2-C4 lower aliphatic amine catalyst as described in claim 3, characterized in that, In S1, the pH of the solution was quickly adjusted to 10.5±0.1 using a 10% sulfuric acid solution to obtain a sol. The sol was then dried at 80±5℃ for 24 hours, washed, filtered, and air-dried naturally. Finally, it was calcined at 550±50℃ for 5 hours.

6. The method for preparing a C2-C4 lower aliphatic amine catalyst as described in claim 3, characterized in that, S2 contains MCM-41 powder and macroporous silica powder prepared by S1, in a weight ratio of 4:0.1 to 2.

0.

7. The method for preparing a C2-C4 lower aliphatic amine catalyst as described in claim 3, characterized in that, Add 2% of the total mass of MCM-41 and macroporous silica guar gum powder. After mixing evenly, add 50±5mL of 5% nitric acid solution. Finally, calcine the mixture at 350-550℃ for 2-8 hours.

8. The method for preparing a catalyst for C2-C4 lower aliphatic amines as described in claim 3, characterized in that, In S3, Ni(NO3)2.6H2O, Mg(NO3)2.6H2O and Zn(NO3)2.6H2O are placed at 30-80℃ to obtain a salt solution.

9. The method for preparing a catalyst for C2-C4 lower aliphatic amines as described in claim 3, characterized in that, After impregnation in S3, the catalyst is dried at 100-150℃ for 6-16 hours and then calcined at 450±100℃ for 2-8 hours to obtain the NiO / MgO / ZnO / MCM-41 catalyst.

10. The application of the catalyst of a C2-C4 lower aliphatic amine as described in claim 1 or 2, characterized in that, The NiO / MgO / ZnO / MCM-41 catalyst converts ethanol, isopropanol, n-propanol, and n-butanol into ethylamine, isopropylamine, n-propylamine, and n-butylamine, respectively.

Images