Method for synthesizing n-octylamine from n-caprylic alcohol
The toxicity and selectivity problems of traditional fatty amine synthesis methods are solved through the alumina-supported nickel-copper catalyst modified by chromium-zinc-modified alumina solution in the amination reaction of n-octanol, ammonia and hydrogen, and achieved efficient and environmentally friendly n-octanol synthesis.
Patent Information
- Application Number
- CN202510436162.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-08
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, the fatty amine synthesis method has the problems of using toxic reagents, generating toxic wastes and low selectivity, and the catalyst for synthesis of amines of low-grade fatty alcohols is difficult to apply on a large scale.
Alumina-supported nickel-copper catalyst modified with chromium zinc was used to aminize n-octanol with ammonia and hydrogen at 180-200°C. By controlling the conditions such as ammonia alcohol ratio, hydrogen alcohol ratio, reaction space speed and pressure, the high conversion rate and selective synthesis of n-octanol was achieved.
It achieves high conversion and selective synthesis of n-octanol. The catalyst is easy to separate, has good stability, is environmentally friendly and economical, and is suitable for chemical production.
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Figure CN120289301A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical synthesis, and specifically relates to a method for synthesizing n-octylamine from n-octanol. Background Art
[0002] Aliphatic amines are a very important class of chemical raw materials and are widely used as important intermediates in various fields of industrial production. The chemical properties of aliphatic amines are relatively active and can react with a variety of compounds to form a series of different products. Among them, primary amines can be used as mineral flotation agents, demulsifiers and emulsifiers, and have important applications in the petrochemical industry and mining, so they have attracted much attention. However, in traditional methods for synthesizing aliphatic amines, the raw materials for synthesizing chain aliphatic amines mainly include nitriles, carboxylic acids, α-olefins, aldehydes, ketones, etc. The synthesis method mainly uses the ammonia (amine) solution method, which mostly uses toxic reagents or produces a large amount of toxic waste, and the selectivity is not high.
[0003] Recently, a series of catalysts have also been proposed for the alcohol amination reaction. Among them, using low-valent metal catalysts (Cu, Ni) to catalyze the amination reaction of lower aliphatic alcohols is the current research goal. However, in the related technical means for synthesizing corresponding amines with alcohols as substrates, generally lower aliphatic alcohols with three carbons or organic compounds containing hydroxyl groups and other functional groups are used, and the catalyst needs to be doped with a variety of precious metal active components. These limiting conditions make it difficult to carry out large-scale applications of the technology for synthesizing amines from alcohols in chemical production. Summary of the Invention
[0004] In view of the above problems, the present application provides a method for synthesizing n-octylamine from n-octanol. The reaction process of this method is simple and the conditions are mild, and it can achieve a high conversion rate and selectivity of n-octanol.
[0005] An embodiment of the present application provides a method for synthesizing n-octylamine from n-octanol, including the following steps: passing a mixed gas of gaseous n-octanol, ammonia, and hydrogen through a nickel-copper catalyst supported on chromium-zinc modified alumina, and carrying out an amination reaction at 180-200 °C to obtain n-octylamine. Among them, calculated by mass percentage, the nickel-copper catalyst supported on chromium-zinc modified alumina includes 62-83 wt% of aluminum oxide, 15-30 wt% of nickel, 1-5 wt% of copper, 1-2 wt% of chromium, and 0.1-0.5 wt% of zinc.
[0006] In some embodiments, the molar ratio of ammonia to n-octanol is 8-21:1, and the molar ratio of hydrogen to n-octanol is 4-6:1.
[0007] In some embodiments, the mass space velocity of n-octanol is 1-4 h ～1 , and the pressure of the reaction system is 0.1-0.5 Mpa.
[0008] In some embodiments, the molar ratio of ammonia to n-octanol is 16 to 21:1, and the molar ratio of hydrogen to n-octanol is 6:1.
[0009] In some embodiments, the method for preparing the chromium-zinc modified alumina-supported nickel-copper catalyst comprises the following steps: impregnating an alumina support into a mixed solution containing metal nickel, copper, chromium, and zinc precursors by the equal-volume impregnation method, stirring for 20 to 40 min, aging at room temperature for 16 to 24 h, drying at 100 to 110 °C, and then calcining to obtain the chromium-zinc modified alumina-supported nickel-copper catalyst.
[0010] In some embodiments, the alumina support is γ-Al2O3, and the metal nickel, copper, chromium, and zinc precursors include nickel nitrate hexahydrate, copper nitrate trihydrate, chromium nitrate nonahydrate, and zinc nitrate hexahydrate.
[0011] In some embodiments, before the impregnation operation of the alumina support, the alumina support is calcined, controlling the heating rate to 2 °C / min and heating to 500 °C for calcination for 4 h.
[0012] In some embodiments, the calcination includes: placing the catalyst obtained after drying in a crucible, and calcining in a muffle furnace at 500 °C for 2 - 5 h to obtain the chromium-zinc modified alumina-supported nickel-copper catalyst.
[0013] In some embodiments, after obtaining the chromium-zinc modified alumina-supported nickel-copper catalyst through calcination, the chromium-zinc modified alumina-supported nickel-copper catalyst is further reduced, and the reduction conditions include: reducing the chromium-zinc modified alumina-supported nickel-copper catalyst under a mixed gas of hydrogen and nitrogen, with a hydrogen flow rate of 20 ml / min and a nitrogen flow rate of 40 ml / min; the reduction temperature is 200 - 500 °C, the heating rate during reduction is 2 °C / min, and the reduction time is 3 - 10 h.
[0014] As can be seen from the above technical solutions, the present application provides a method for synthesizing n-octylamine from n-octanol. The reaction process of this method is simple, the conditions are mild, the prepared chromium-zinc modified alumina-supported nickel-copper catalyst is easy to separate, using hydrogen as the hydrogen source and ammonia as the ammonia source, and catalytic amination of n-octanol selectively prepares primary amines. The chromium-zinc modified alumina-supported nickel-copper catalyst provided by the present application has a high reduction degree, a good dispersion degree of the active metal nickel component, a small degree of nickel agglomeration, and an appropriate interaction between the metal nickel and the support; the added zinc and chromium will cause a barrier effect near the active sites on the catalyst surface, so that the active components will not sinter together after the reaction, thereby improving the stability of the catalyst, making the catalyst have a high level of n-octanol conversion rate and n-octylamine selectivity at atmospheric pressure and a reaction temperature of 180 - 200 °C, and having broad application prospects. Description of the Drawings
[0015] To more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.
[0016] Figure 1 The scanning electron microscope photograph of the chromium-zinc modified alumina supported nickel-copper catalyst prepared in Example 1 is shown. Detailed implementation manners
[0017] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms without departing from the core spirit of the present application, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present application more thorough and comprehensive.
[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0019] The embodiment of the present application provides a method for synthesizing n-octylamine from n-octanol, including the following steps: passing a mixed gas of gaseous n-octanol, ammonia, and hydrogen through a chromium-zinc modified alumina supported nickel-copper catalyst, and performing an amination reaction at 180-200 °C to obtain n-octylamine. Among them, by mass percentage, the chromium-zinc modified alumina supported nickel-copper catalyst includes 62-83 wt% of aluminum oxide, 15-30 wt% of nickel, 1-5 wt% of copper, 1-2 wt% of chromium, and 0.1-0.5 wt% of zinc.
[0020] In the method for synthesizing n-octylamine from n-octanol provided by the embodiment of the present application, since the chromium-zinc modified alumina supported nickel-copper catalyst can form more interfaces between Ni and the carrier and adjust the formation of an appropriate interaction between nickel and the alumina carrier, it can achieve a higher conversion rate of n-octanol and a higher selectivity for n-octylamine.
[0021] In some embodiments, the molar ratio of ammonia to n-octanol is 8-21:1, and the molar ratio of hydrogen to n-octanol is 4-6:1.
[0022] In some embodiments, the mass space velocity of n-octanol is 1-4 h ～1 , and the pressure of the reaction system is 0.1-0.5 Mpa.
[0023] In some embodiments, the molar ratio of ammonia to n-octanol is 16-21:1, and the molar ratio of hydrogen to n-octanol is 6:1.
[0024] Through a large number of experiments, the inventors found that by strictly controlling conditions such as the ammonia-to-alcohol ratio, hydrogen-to-alcohol ratio, mass space velocity of the reaction raw material (n-octanol), and the reaction system pressure during the reaction of synthesizing n-octylamine from n-octanol, the conversion rate of n-octanol and the selectivity of n-octylamine can be further improved.
[0025] In the method for synthesizing n-octylamine from n-octanol provided in the embodiments of the present application, in a reaction atmosphere with an ammonia-to-alcohol ratio of 12:1 and a hydrogen-to-alcohol ratio of 5:1, at a reaction space velocity of 1.9 h -1 and a reaction temperature of 200 °C, both the conversion rate and selectivity are greater than 85%, far superior to traditional nickel-based catalysts, showing excellent activity, good system stability, simple preparation, environmental protection and economy, and the catalyst is easy to separate from the system and can still maintain high activity after being recycled multiple times.
[0026] In some embodiments, the preparation method of the chromium-zinc modified alumina-supported nickel-copper catalyst includes the following steps: impregnating an alumina carrier into a mixed solution containing metal nickel, copper, chromium, and zinc precursors by the equal-volume impregnation method, stirring for 20-40 min, aging at room temperature for 16-24 h, drying at 100-110 °C, and then calcining to obtain the chromium-zinc modified alumina-supported nickel-copper catalyst.
[0027] In the chromium-zinc modified alumina-supported nickel-copper catalyst prepared by the catalyst preparation method provided in the embodiments of the present application, the nickel nanoparticles have uniform particle sizes and high dispersion, the specific surface area of the catalyst is large, the reducibility is good, and the degree of agglomeration is low. Compared with the nickel-based catalyst obtained by the traditional impregnation method, it is more conducive to the dispersion of Ni species and improves the reaction activity of the catalyst in the amination of n-octanol; at the same time, the preparation process of this catalyst is simple, the cost is low, and the catalyst evaluation is applied to a continuous-phase reactor. Therefore, the use of this method and catalyst has broad application prospects.
[0028] In the embodiments of the present application, the mesh number of the chromium-zinc modified alumina-supported nickel-copper catalyst can be 40-60 mesh.
[0029] In some embodiments, the alumina carrier is γ-Al2O3, and the metal nickel, copper, chromium, and zinc precursors include nickel nitrate hexahydrate, copper nitrate trihydrate, chromium nitrate nonahydrate, and zinc nitrate hexahydrate.
[0030] In some embodiments, before the impregnation operation of the alumina carrier, the alumina carrier is calcined, controlling the heating rate to be 2 °C / min and heating to 500 °C for calcination for 4 h.
[0031] In some embodiments, the calcination includes: placing the catalyst obtained after drying in a crucible, and calcining it in a muffle furnace at 500 °C for 2 - 5 h to obtain a chromium-zinc modified alumina-supported nickel-copper catalyst.
[0032] In some embodiments, after obtaining the chromium-zinc modified alumina-supported nickel-copper catalyst through calcination, the chromium-zinc modified alumina-supported nickel-copper catalyst is further reduced. The reduction conditions include: reducing the chromium-zinc modified alumina-supported nickel-copper catalyst under a mixed gas of hydrogen and nitrogen, with a hydrogen flow rate of 20 ml / min and a nitrogen flow rate of 40 ml / min; the reduction temperature is 200 - 500 °C, the heating rate during reduction is 2 °C / min, and the reduction time is 3 - 10 h.
[0033] The following are specific preparation examples related to the above content of the present disclosure. It should be clear that the following examples are only for illustrating the method for synthesizing n-octylamine from n-octanol disclosed above, and the specific implementation methods and parameters used are only one or several of the many processes and methods that conform to the above. Those skilled in the art can use other parameters to prepare n-octylamine according to the method described in this application without departing from the core spirit disclosed in the application.
[0034] Example 1
[0035] Place the activated alumina support in a crucible, heat it to 500 °C at a rate of 2 °C / min in a muffle furnace, and hold for 4 h. After calcination, take it out and seal it to obtain a pretreated support. Among them, the catalyst utilizes the advantages of γ-Al2O3 (≤20 nm) providing a large specific surface area and appropriate density and strength of surface acid-base sites, and uses it as a support to load nickel, copper, chromium, and zinc to obtain the catalyst.
[0036] Dissolve 9.909 g of nickel nitrate hexahydrate, 0.6206 g of copper nitrate trihydrate, 0.6219 g of cadmium nitrate nonahydrate and 0.1840 g of zinc nitrate hexahydrate in 8.48 ml of deionized water, and stir for 30 minutes at room temperature to obtain a mixed solution; place 8 g of pretreated support in a 40 ml beaker, add the mixed solution dropwise to the beaker and stir. When the addition of the mixed solution is complete, continue stirring for 30 minutes. After stirring, seal the suspension at room temperature and let it age for 24 h; place the suspension in an oven and dry it at 110 °C for 12 h. Place it in a crucible and heat it in a muffle furnace from room temperature to 550 °C at a rate of 2 °C / min, and hold for 2 h to obtain a chromium and zinc modified alumina supported nickel and copper catalyst (the loading amount of metallic nickel is 20 wt%). After obtaining the chromium and zinc modified alumina supported nickel and copper catalyst by calcination, further reduce the chromium and zinc modified alumina supported nickel and copper catalyst. The reduction conditions include: reducing the chromium and zinc modified alumina supported nickel and copper catalyst under a mixed gas of hydrogen and nitrogen, with a hydrogen flow rate of 20 ml / min and a nitrogen flow rate of 40 ml / min; the reduction temperature is 300 °C, the heating rate during reduction is 2 °C / min, and the reduction time is 3 - 10 h.
[0037] Figure 1 Figure 4 shows the scanning electron microscope photograph of the chromium and zinc modified alumina supported nickel and copper catalyst prepared in the example. As Figure 1 shown, on the surface of the chromium and zinc modified alumina supported nickel and copper catalyst, the particle size of the metal nanoparticles is uniform and the dispersion is high.
[0038] Under the reaction conditions of a hydrogen to alcohol ratio of 5:1, an ammonia to alcohol ratio of 16:1, and atmospheric pressure, the reaction space velocity of the catalyst in this example is 1.9 h -1 , the reaction temperature is 200 °C, and the amination of n-octanol is realized. Among them, the catalyst evaluation device is a fixed bed catalytic reaction tube, the inner diameter of the tubular reactor is 8 mm, and the length is 36 cm. A thermocouple sleeve is placed inside the quartz tube, and the temperature measuring thermocouple is placed in the middle of the catalyst bed to measure the actual reaction temperature. Load 2.0 g of the catalyst with a particle size of 40 - 60 mesh in the middle of the reaction tube, and fix its position at both ends with quartz wool. The flow rates of the raw materials ammonia and hydrogen are controlled by mass flow meters and then introduced into the reaction tube, the raw material n-octanol is introduced into the reaction system by a pump, and the reaction products at the outlet of the reaction tube pass through a cold trap and a collection tank, and liquid samples are taken. The products are calibrated by the modified area normalization method and detected by a gas chromatograph.
[0039] In the reaction process of synthesizing n-octylamine from n-octanol in this example, the conversion rate of n-octanol is 88%, and the selectivity of n-octylamine is 95%.
[0040] Example 2
[0041] Place the activated alumina support in a crucible, heat it in a muffle furnace to 500 °C at a rate of 2 °C / min, and hold for 4 h. After calcination, take it out and seal it to obtain a pretreated support. Among them, the catalyst utilizes the advantages of γ-Al2O3 (≤20 nm) providing a large specific surface area and appropriate density and strength of surface acid-base sites, and uses it as a support to load nickel, copper, chromium, and zinc to obtain the catalyst.
[0042] Dissolve 9.909 g of nickel nitrate hexahydrate, 0.6206 g of copper nitrate trihydrate, 0.6219 g of cadmium nitrate nonahydrate, and 0.1840 g of zinc nitrate hexahydrate in 8.48 ml of deionized water, and stir at room temperature for 30 minutes to obtain a mixed solution; place 8 g of the pretreated support in a 40 ml beaker. Drop the mixed solution into the beaker and stir. When the dropping of the mixed solution is completed, keep stirring for 30 minutes; after stirring, seal the suspension at room temperature and let it stand for 24 h; place the suspension in an oven and dry it at 110 °C for 12 h. Place it in a crucible, heat it in a muffle furnace to 500 °C at a rate of 2 °C / min, and hold for 2 h to obtain a chromium-zinc modified alumina supported nickel-copper catalyst (the loading amount of metallic nickel is 20 wt%). After obtaining the chromium-zinc modified alumina supported nickel-copper catalyst through calcination, reduce the chromium-zinc modified alumina supported nickel-copper catalyst. The reduction conditions include: reducing the chromium-zinc modified alumina supported nickel-copper catalyst under a mixed gas of hydrogen and nitrogen, with a hydrogen flow rate of 20 ml / min and a nitrogen flow rate of 40 ml / min; the reduction temperature is 300 °C, the heating rate during reduction is 2 °C / min, and the reduction time is 3 - 10 h.
[0043] Under the reaction conditions of a hydrogen-to-alcohol ratio of 6:1, an ammonia-to-alcohol ratio of 21:1, and normal pressure, the reaction space velocity of the catalyst is 1.9 h -1 ⁻¹, the reaction temperature is 200 °C, and the amination of n-octanol is realized. Among them, the catalyst evaluation device is a fixed-bed catalytic reaction tube. The inner diameter of the tubular reactor is 8 mm and the length is 36 cm. Place a thermocouple sleeve inside the quartz tube, and place the temperature-measuring thermocouple in the middle of the catalyst bed to measure the actual reaction temperature. Load 2.0 g of the catalyst with a particle size of 40 - 60 mesh in the middle of the reaction tube, and fix its position at both ends with quartz wool. The flow rates of the raw materials ammonia and hydrogen are controlled by mass flow meters and then introduced into the reaction tube. The raw material n-octanol is introduced into the reaction system through a pump. The reaction products at the outlet of the reaction tube pass through a cold trap and a collection tank, and liquid samples are taken. The products are calibrated by the modified area normalization method and detected by a gas chromatograph.
[0044] In the reaction process of synthesizing n-octylamine from n-octanol in this example, the conversion rate of n-octanol is 99%, and the selectivity of n-octylamine is 99%.
[0045] Comparative Example 1
[0046] 5.8836 g of nickel nitrate hexahydrate was dissolved in 5.035 ml of deionized water, and stirred at room temperature for 30 minutes to obtain a mixed solution; 4.75 g of pretreated carrier was placed in a 40 ml beaker. The mixed solution was added dropwise to the beaker and stirred. After the addition of the mixed solution was completed, stirring was continued for 30 minutes. After stirring, the suspension was sealed at room temperature and aged for 24 h. The suspension was placed in an oven and dried at 110 °C for 12 h. Then it was placed in a crucible and heated to 550 °C at a rate of 2 °C / min in a muffle furnace and held for 2 h to obtain an alumina-supported nickel metal catalyst (the loading amount of metallic nickel was 20 wt%). After obtaining the alumina-supported nickel metal catalyst through calcination, the alumina-supported nickel metal catalyst was further reduced. The reduction conditions included: reducing the alumina-supported nickel metal catalyst under a mixed gas of hydrogen and nitrogen, with a hydrogen flow rate of 20 ml / min and a nitrogen flow rate of 40 ml / min; the reduction temperature was 300 °C, the heating rate during reduction was 2 °C / min, and the reduction time was 3 - 10 h.
[0047] Under the reaction conditions of a hydrogen-to-alcohol ratio of 5:1, an ammonia-to-alcohol ratio of 8:1, and atmospheric pressure, the reaction space velocity of the catalyst prepared in this comparative example was 1.9 h -1 , the reaction temperature was 200 °C, and the amination of n-octanol was achieved. Among them, the catalyst evaluation device was a fixed-bed catalytic reaction tube. The inner diameter of the tubular reactor was 8 mm and the length was 36 cm. A thermocouple sleeve was placed inside the quartz tube, and the temperature-measuring thermocouple was placed in the middle of the catalyst bed to measure the actual reaction temperature. 2.0 g of the catalyst with a particle size of 40 - 60 mesh was loaded in the middle of the reaction tube, and its position was fixed at both ends with quartz sand. The flow rates of the raw materials ammonia and hydrogen were controlled by mass flow meters and then introduced into the reaction tube. The raw material n-octanol was introduced into the reaction system through a pump. The reaction products at the outlet of the reaction tube passed through a cold trap and a collection tank, and liquid samples were taken. The products were calibrated by the modified area normalization method and detected by a gas chromatograph.
[0048] In the reaction process of synthesizing n-octylamine from n-octanol in this comparative example, the conversion rate of n-octanol was 85%, and the selectivity of n-octylamine was 92%.
[0049] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded in this application.
[0050] The above-described embodiments merely represent several embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning, or limited experiments based on the technical solutions provided by the present invention are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims, and the specification and drawings can be used to explain the content of the claims.
Claims
1. A method for synthesizing n-octylamine from n-octanol, characterized in that, Comprising the following steps: A mixed gas of gaseous n-octanol, ammonia, and hydrogen is passed through a nickel-copper catalyst supported on chromium-zinc modified alumina, and an amination reaction is carried out at 180 - 200 °C to obtain n-octylamine. Among them, calculated by mass percentage, the nickel-copper catalyst supported on chromium-zinc modified alumina comprises 62 - 83 wt% of aluminum trioxide, 15 - 30 wt% of nickel, 1 - 5 wt% of copper, 1 - 2 wt% of chromium, and 0.1 - 0.5 wt% of zinc.
2. The method for synthesizing n-octylamine from n-octanol according to claim 1, characterized in that, The molar ratio of ammonia to n-octanol is 8 - 21:1, and the molar ratio of hydrogen to n-octanol is 4 - 6:
1.
3. The method for synthesizing n-octylamine from n-octanol as claimed in claim 1, wherein, The mass space velocity of n-octanol is 1-4 h ～1 , and the pressure of the reaction system is 0.1-0.5 Mpa.
4. The method for synthesizing n-octylamine from n-octanol according to claim 1, characterized in that, The molar ratio of ammonia to n-octanol is 16 - 21:1, and the molar ratio of hydrogen to n-octanol is 6:
1.
5. The method for synthesizing n-octylamine from n-octanol according to claim 1, characterized in that, The preparation method of the nickel-copper catalyst supported on chromium-zinc modified alumina comprises the following steps: The alumina support is impregnated into a mixed solution containing metal nickel, copper, chromium, and zinc precursors by the equal-volume impregnation method, stirred for 20 - 40 min, aged at room temperature for 16 - 24 h, dried at 100 - 110 °C, and then calcined to obtain the nickel-copper catalyst supported on chromium-zinc modified alumina.
6. The method for synthesizing n-octylamine from n-octanol as claimed in claim 5, wherein The alumina support is γ-Al2O3, and the metal nickel, copper, chromium, and zinc precursors include nickel nitrate hexahydrate, copper nitrate trihydrate, chromium nitrate nonahydrate, and zinc nitrate hexahydrate.
7. The method for synthesizing n-octylamine from n-octanol according to claim 5, characterized in that, Before the impregnation operation on the alumina support, the alumina support is calcined, controlling the heating rate at 2 °C / min, heating to 500 °C and calcining for 4 h.
8. The method for synthesizing n-octylamine from n-octanol according to claim 5, characterized in that, The calcination includes: The catalyst obtained after drying is placed in a crucible and calcined in a muffle furnace at 500 °C for 2 - 5 h to obtain the nickel-copper catalyst supported on chromium-zinc modified alumina.
9. The method for synthesizing n-octylamine from n-octanol according to claim 5, characterized in that, After obtaining the nickel-copper catalyst supported on chromium-zinc modified alumina through calcination, the nickel-copper catalyst supported on chromium-zinc modified alumina is further reduced. The reduction conditions include: The nickel-copper catalyst supported on chromium-zinc modified alumina is placed under a mixed gas of hydrogen and nitrogen for reduction, the hydrogen flow rate is 20 ml / min, and the nitrogen flow rate is 40 ml / min; the reduction temperature is 200 - 500 °C, the heating rate during reduction is 2 °C / min, and the reduction time is 3 - 10 h.