Process for the amination of 1,6-hexanediol to 1,6-hexanediamine

Abstract

The application relates to the technical field of organic amine preparation, and discloses a method for preparing 1,6-hexanediamine by aminating 1,6-hexanediol. The method effectively improves the overall conversion rate of the raw material 1,6-hexanediol by optimizing the distribution of the circulating material, and avoids the further reaction of the target product and the intermediate product to generate amine with twelve or even eighteen carbon atoms, so that the selectivity of the hexanediamine and the conversion rate of the 1,6-hexanediol are further improved compared with the traditional method of mixing the circulating material and the 1,6-hexanediol together and feeding into a trickle bed reactor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic amine preparation, in particular to a method for preparing 1,6-hexanediamine by aminating 1,6-hexanediol. BACKGROUND

[0002] Amines are very important industrial organic compounds, widely used in various fields, such as solvents, pharmaceutical intermediates, resin raw materials, fabric additives, pesticides, rubber stabilizers, etchants, and also used for cleaning and plastic processing. Among them, diamines are important monomers of materials, for example, hexanediamine is an important monomer of nylon 66, nylon 6T, nylon 610 and nylon 612.

[0003] Hexanediamine is usually prepared by hydrogenation of adiponitrile in industry, but the preparation technology of adiponitrile has high threshold, and the preparation method includes butadiene hydrocyanation, propylene nitrile electrolytic dimerization and high-temperature ammoniation dehydration of adipic acid. Butadiene hydrocyanation is the mainstream route in industry, but butadiene hydrocyanation not only has high catalyst technology content, but also has the problems of difficult catalyst recovery and use of toxic raw material hydrocyanic acid.

[0004] In order to solve the above problems, researchers have developed various synthesis routes of hexanediamine, among which the hydrogenation amination reaction of 1,6-hexanediol to obtain hexanediamine is a scheme with better conversion rate and selectivity. However, the current method for preparing hexanediamine by hydrogenation amination of 1,6-hexanediol still has the problems that the intermediate product cannot be completely converted into hexanediamine in one step, and there is a balance component of hexanediamine, cyclohexylideneimine, so that the conversion rate of 1,6-hexanediol and the selectivity of hexanediamine still have a large space for improvement. For example, 1,6-hexanediamine and the intermediate product cyclohexylideneimine are in a kind of equilibrium reaction state, resulting in a part of the intermediate product cannot be completely converted into the target product. For another example, 6-aminohexanol and the intermediate product cyclohexylideneimine, 6-aminohexanol may further undergo amination reaction in the reaction process to generate secondary amine or tertiary amine with twelve or even eighteen carbon atoms, resulting in the selectivity of the target product in the final product being reduced. SUMMARY

[0005] The purpose of the present application is to overcome the problems of insufficient conversion rate and selectivity of 1,6-hexanediol in the preparation of 1,6-hexanediamine by hydrogenation amination, and to provide a method for preparing 1,6-hexanediamine by aminating 1,6-hexanediol. The method further improves the selectivity of hexanediamine and the conversion rate of 1,6-hexanediol by optimizing the distribution of the action of each catalyst bed.

[0006] In order to achieve the above purpose, the present application provides a method for preparing 1,6-hexanediamine by aminating 1,6-hexanediol, which comprises:

[0007] (1) subjecting 1,6-hexanediol to a preliminary amination reaction with ammonia and hydrogen and optionally a solvent, controlling the conversion rate of 1,6-hexanediol in the preliminary amination reaction to be no more than 85%, and obtaining a preliminary amination reaction product;

[0008] (2) subjecting the preliminary amination reaction product obtained in step (1) to a continued amination reaction, in which process the material containing cyclohexylamine and the optional material containing 6-amino-1-hexanol are introduced separately or together into the preliminary amination reaction product obtained in step (1) and subjected to a continued amination reaction separately or together.

[0009] By means of the technical solution described above, the present application can at least achieve the following beneficial effects:

[0010] The method provided by the present application effectively improves the overall conversion rate of the raw material 1,6-hexanediol by continuing the reaction after distributing the raw material 1,6-hexanediol and the intermediate product generated during the reaction in a specific manner, while avoiding the further reaction of the target product with the intermediate product to generate amine with twelve or even eighteen carbon atoms, so that the selectivity and yield of the target product hexamethylenediamine are improved. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a structural schematic diagram of a trickle bed reactor used in the method provided by the present application.

[0012] Figure 2 is a structural schematic diagram of a distributor in the trickle bed reactor preferably adopted by the present application.

[0013] REFERENCE SIGNS

[0014] Figure 1 In the figure, 1 is a cylinder; 2 is a feed inlet; 3 is a distributor; 4 is a (first) distributor; 5 is a first catalyst bed layer; 6 is a catalyst support plate (of the first catalyst bed layer); 7 is a first interlayer feed inlet; 8 is a second catalyst bed layer; 9 is a second interlayer feed inlet; 10 is a third catalyst bed layer; 11 is a discharge outlet,

[0015] Figure 2 In the figure, 4-1 is a distribution plate; 4-2 is a downcomer; 4-3 is a cover plate; 4-4 is a dispersion pipe; and 4-5 is a dispersion plate. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to sub-ranges falling within the specified range. In this context, a sub-range can be independently selected from the stated range.

[0017] In the present invention, "hexanediol" is a short name of "1,6-hexanediol" and has the same meaning, which can be used interchangeably; "hexanediamine" is a short name of "1,6-hexanediamine" and has the same meaning, which can be used interchangeably; "6-aminohexanol" or "aminohexanol" is a short name of "6-amino-1-hexanol" and has the same meaning, which can be used interchangeably; "cyclohexylideneimine" has the same meaning as "hexamethyleneimine", which can be used interchangeably.

[0018] In the present invention, "optional" means that a component can be selected to contain or not to contain, or an operation can be selected to be performed or not to be performed. Those skilled in the art can select whether to use the "optional" components or operations in the present invention according to the actual situation, such as production condition limitation, raw material selection, production target requirement, etc.

[0019] The inventors of the present invention found through a large number of experiments that 1,6-hexanediol and ammonia undergo catalytic amination reaction to first generate 6-aminohexanol, and further amination to generate 1,6-hexanediamine. 6-aminohexanol or 1,6-hexanediamine can undergo cyclization reaction to generate cyclohexylideneimine (also known as hexamethyleneimine), and 1,6-hexanediamine and cyclohexylideneimine can be converted to each other.

[0020] The inventors also found that there is a certain correlation between the conversion rate of 1,6-hexanediol and the selectivity of 6-aminohexanol. When the conversion rate of 1,6-hexanediol reaches 70%, the selectivity of 6-aminohexanol is more than 95%; when the conversion rate of 1,6-hexanediol reaches 75%, the selectivity of 6-aminohexanol is more than 90%; when the conversion rate of 1,6-hexanediol reaches 85%, the selectivity of 6-aminohexanol is as high as 85%. That is, 85% of 6-aminohexanol in the converted 1,6-hexanediol has not yet reacted further, and further increasing the conversion rate of 1,6-hexanediol gradually converts 6-aminohexanol into 1,6-hexanediamine and cyclohexylideneimine. A large number of studies have also found that it is inevitable to separate 6-aminohexanol and cyclohexylideneimine respectively during the catalytic reaction process and recycle them back to the reactor.

[0021] In the prior art, 6-aminohexanol and cyclohexylamine are usually returned to the reactor together with 1,6-hexanediol, which dilutes 1,6-hexanediol and reduces its conversion rate. Moreover, cyclohexylamine enters the reactor too early, which increases the chance of reaction with 1,6-hexanediol or 6-aminohexanol to form a twelve-carbon amine, thus reducing the selectivity of the target product, hexamethylenediamine.

[0022] The inventors have further found that by using a reactor with multiple catalyst beds or connecting multiple reactors in series and reasonably distributing the materials in the reaction process, the roles and divisions of the catalyst beds in the reactor or the reactors connected in series can be fully defined, which can effectively improve the conversion rate of the raw material and the selectivity of hexamethylenediamine. For example, feeding the material containing 6-aminohexanol and the material containing cyclohexylamine from the interlayer between adjacent catalyst beds can make 1,6-hexanediol react faster and better in the upper catalyst bed to form 6-aminohexanol. At this time, feeding the material containing 6-aminohexanol can make it further aminate to form hexamethylenediamine, and feeding the material containing cyclohexylamine can inhibit the conversion of hexamethylenediamine or 6-aminohexanol to cyclohexylamine, while reducing the amount of twelve-carbon amine.

[0023] Based on this, the present application provides a method for preparing 1,6-hexanediamine by aminating 1,6-hexanediol, which comprises:

[0024] (1) subjecting 1,6-hexanediol to a preliminary amination reaction with ammonia and hydrogen and optionally a solvent, and controlling the conversion rate of 1,6-hexanediol in the preliminary amination reaction to be not more than 85%, to obtain a preliminary amination reaction product;

[0025] (2) subjecting the preliminary amination reaction product obtained in step (1) to a continued amination reaction, and in this process, feeding the material containing cyclohexylamine and the optional material containing 6-aminohexanol separately or together into the continued amination reaction with the preliminary amination reaction product obtained in step (1) separately or together.

[0026] In the present application, the "preliminary amination reaction" refers to a process in which the raw materials 1,6-hexanediol, ammonia and hydrogen are reacted, and the conversion rate of hexanediol is not more than 85%, and the product usually contains 6-aminohexanol and unreacted hexanediol, and may also contain part of the cyclohexylideneimine (usually about 30% by weight) and part of the hexamethylenediamine, and a small amount of amine byproducts with twelve carbon atoms. The "continued amination reaction" refers to a process in which the product of the preliminary amination reaction is flowed into the next reaction unit (for example, into the next reactor bed or into the next reactor in series) to continue the amination reaction to obtain more hexamethylenediamine, and in this process, the material containing cyclohexylideneimine, aminohexanol and other components separated from the subsequent rectification unit (these materials can be collectively referred to as "recycle material") is introduced, which on the one hand improves the utilization rate of raw materials and avoids waste, and on the other hand improves the selectivity of the target product hexamethylenediamine.

[0027] In the present application, since 1,6-hexanediol is a solid crystal at room temperature, it is not convenient to be directly added to the reactor (usually a trickle bed reactor) for reaction, so it is usually dissolved in a certain solvent (at a certain temperature) to prepare a hexanediol liquid material, and then introduced into the reactor. Therefore, the solvent in the present application refers to an organic reagent capable of dissolving 1,6-hexanediol, such as ether compounds such as dioxane, dioxolane, tetrahydrofuran, etc. When preparing the hexanediol material with the solvent, it can also be heated according to the actual situation. Alternatively, the solvent can not be used, and 1,6-hexanediol can be directly heated to prepare a liquid material and introduced into the reactor.

[0028] In the present application, there is no particular limitation on the way to control the conversion rate of 1,6-hexanediol in the preliminary amination reaction, and any way that can achieve this purpose can be applied to the present application. For example, the position of the recycle material feed port can be selected according to the conversion of hexanediol, or the amount of catalyst loaded in the first catalyst bed can be adjusted to make the conversion rate of hexanediol in the preliminary amination reaction in the first catalyst bed meet the above requirements.

[0029] In the method provided by the present application, by controlling the conversion rate of hexanediol in the preliminary amination reaction and reasonably distributing the reaction material for continued reaction, the raw material conversion rate and target product selectivity for preparing hexamethylenediamine from hexanediol are effectively improved. Any reaction method that can achieve such material distribution can be applied to the present application. For example, according to the actual production situation, a reactor with multiple catalyst beds can be selected, and the material can be distributed to different beds for reaction according to the method of the present application, or multiple reactors can be used, and then the material can be distributed to different reactors for reaction according to the method of the present application.

[0030] According to a preferred embodiment of the present application, the method is carried out in a trickle bed reactor comprising two or more catalyst beds in series, wherein the preliminary amination reaction is carried out in the first catalyst bed and the continued amination reaction is carried out in the second and subsequent catalyst beds.

[0031] According to another preferred embodiment of the present application, the method is carried out in at least two trickle bed reactors in series, each comprising at least one catalyst bed, wherein the preliminary amination reaction is carried out in the first trickle bed reactor and the continued amination reaction is carried out in the second and subsequent trickle bed reactors.

[0032] According to a preferred embodiment of the present application, the conditions of the preliminary amination reaction and / or the continued amination reaction comprise: the reaction temperature of the catalyst bed is 150-220℃, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:10-50:0.2-2, based on all 1,6-hexanediol entering the reactor, the space velocity of 1,6-hexanediol is 0.1-0.4 g·mL -1 ·h -1 “g·mL -1 ·h -1 ” refers to the amount of 1,6-hexanediol (g) passing through a unit volume (mL) of catalyst per unit time (h).

[0033] The reaction temperature is one of the extremely important conditions for the method provided by the present application. If the reaction temperature is too low, the conversion of hexanediol is slow, and if the reaction temperature is too high, the probability of side reactions and conversion to amines with twelve carbon atoms increases. The inventors have found through a large number of experiments that carrying out the reaction under the above conditions can effectively improve the reaction efficiency while controlling the occurrence of side reactions and ensuring that the selectivity of the target product remains at a high level.

[0034] In the present application, the conditions of the preliminary amination reaction and the continued amination reaction (especially the reaction temperature) can be the same or different. In order to obtain higher conversion and selectivity of the target product, it is preferred that the conditions of the preliminary amination reaction and the continued amination reaction are different.

[0035] In order to convert as much 1,6-hexanediol and recycle material (i.e. material containing 6-amino-1-hexanol and material containing cyclohexylideneimine) as possible into target products or target intermediates, according to a preferred embodiment of the present application, the conditions of the preliminary amination reaction include: the reaction temperature of the catalyst bed is 170-210℃, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:10-50:0.2-1, based on all 1,6-hexanediol entering the reactor, and the space velocity of 1,6-hexanediol is 0.1-1.6 g·mL -1 ·h -1 .

[0036] According to a preferred embodiment of the present application, in the continued amination reaction, the reaction temperature of the catalyst bed is 150-190℃, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:25-50:0.2-1, based on all 1,6-hexanediol entering the reactor, and the mass ratio of 1,6-hexanediol to cyclohexylideneimine in the material introduced into the catalyst bed of the second stage and subsequent stages or the trickle bed reactor of the second and subsequent stages during the continued amination reaction is 1:0.2-0.6. Part of the cyclohexylideneimine is generated in the preliminary amination reaction, and the cyclohexylideneimine introduced into the catalyst bed of the second stage and subsequent stages or the trickle bed reactor of the second and subsequent stages here refers to only the part of the cyclohexylideneimine in the recycle material, not including the cyclohexylideneimine generated in the preliminary amination reaction.

[0037] Preferably, the reaction temperature of the continued amination reaction is 10-30℃ lower than that of the preliminary amination reaction, and the ammonia alcohol ratio is not lower than that of the preliminary amination reaction. The "ammonia alcohol ratio" refers to the molar ratio of ammonia to all 1,6-hexanediol entering the reactor in the reaction material.

[0038] Since in the method provided by the present application, the conversion rate of 1,6-hexanediol in the preliminary amination reaction is inversely related to the selectivity of hexamethylenediamine in the overall reaction to a certain extent, the higher the conversion rate of 1,6-hexanediol in the preliminary amination reaction, the more heavy products are generated. Therefore, in order to obtain higher selectivity of hexamethylenediamine and improve the yield of target products, according to a preferred embodiment of the present application, the conversion rate of 1,6-hexanediol in the preliminary amination reaction is controlled to be not more than 80%, preferably not more than 75%, and more preferably not more than 70%.

[0039] The processing mode and conditions in different steps of the method provided by the present application will be further described below by taking the case of using a trickle bed reactor with 2 or more catalyst beds in series, in which the preliminary amination reaction is carried out in the first stage catalyst bed and the continued amination reaction is carried out in the second stage and subsequent catalyst beds.

[0040] According to a preferred embodiment of the present application, the cyclohexylamine-containing material is from a subsequent rectification unit. Preferably, the content of cyclohexylamine is not less than 50% by weight. More preferably, it is 75-100% by weight.

[0041] According to a preferred embodiment of the present application, the 6-aminohexanol-containing material is from a subsequent rectification unit. Preferably, the content of 6-aminohexanol is not less than 30% by weight. More preferably, it is 50-90% by weight.

[0042] Since the 1,6-hexanediol is not completely consumed in the actual reaction process, in order to reduce the energy consumption of separation, the un-consumed 1,6-hexanediol is usually separated together with the aminohexanol in the rectification unit as a same fraction, forming a mixture material. Therefore, preferably, the 6-aminohexanol-containing material also contains 1,6-hexanediol. Preferably, the content of 1,6-hexanediol in the 6-aminohexanol-containing material is not more than 70% by weight. More preferably, it is 10-40% by weight.

[0043] In order to avoid too much 1,6-hexanediol being introduced into the continued amination reaction process with the 6-aminohexanol-containing material, which causes too much influence on the selectivity of the target product hexamethylenediamine. More preferably, the amount of the 6-aminohexanol-containing material introduced in the continued amination reaction process in step (2) is such that the 1,6-hexanediol introduced in step (1) accounts for 75-100% by weight of all the 1,6-hexanediol. When the 1,6-hexanediol introduced in step (1) accounts for 100% by weight of all the 1,6-hexanediol, it can be that no 6-aminohexanol-containing material is introduced in step (2), or the processing mode of the rectification unit is controlled so that the 6-aminohexanol is separated alone and then introduced into the continued amination reaction process.

[0044] More preferably, the mass ratio of the 6-amino-1-hexanol contained in the 6-amino-1-hexanol-containing material introduced in the continued amination reaction process in step (2) to all the 1,6-hexanediol is 0.2-0.6:1.

[0045] Since the reaction of 1,6-hexanediol with ammonia is an exothermic reaction, in order to make the catalyst play a better role, in the present application, it is preferred that the reaction raw materials, circulating materials and the like are preheated before being introduced into the trickle bed reactor. The preheating temperature can be slightly lower than the reaction temperature of the material entering the catalyst bed, so as to slightly reduce the reaction temperature to control the bed temperature within a more optimal reaction range.

[0046] It should be particularly noted that the term "preheating" in the present application means that the temperature of the material is controlled in a desired range before the material is introduced into the target catalyst bed, and the meaning thereof is not limited to the treatment of heating the material. When the temperature of the material itself is high and exceeds the desired temperature range, the "preheating treatment" in the present application can also include the meaning of cooling the material.

[0047] According to a preferred embodiment of the present application, the 1,6-hexanediol, ammonia and hydrogen and the optional solvent are preheated to 120-170°C before being introduced into the first catalyst bed to perform the preliminary amination reaction. Preferably, the preheating is to 140-170°C.

[0048] Since the reaction heat will increase the temperature of the bed, and the high temperature of the catalyst bed will lead to the occurrence of side reactions and affect the selectivity. In order to obtain higher selectivity of the target product, according to a preferred embodiment of the present application, the material containing cyclohexylideneimine and the optional material containing 6-aminohexanol are preheated to 150-170°C before being introduced into the second or subsequent catalyst bed to perform the continued amination reaction.

[0049] According to some preferred embodiments of the present application, the method comprises: introducing 1,6-hexanediol, ammonia and hydrogen and the optional solvent into a trickle bed reactor containing at least two catalyst beds, and performing the reaction according to the following steps, wherein each catalyst bed is loaded with an amination catalyst;

[0050] (1) introducing 1,6-hexanediol, ammonia and hydrogen and the optional solvent into the first catalyst bed to perform the preliminary amination reaction, controlling the conversion rate of 1,6-hexanediol in the preliminary amination reaction according to the foregoing requirements, and obtaining the preliminary amination reaction product;

[0051] (2) flowing the preliminary amination reaction product obtained in step (1) into the second catalyst bed, and introducing the material containing cyclohexylideneimine and the optional material containing 6-aminohexanol into the second catalyst bed to perform the continued amination reaction.

[0052] According to some preferred embodiments of the present application, the method comprises: introducing 1,6-hexanediol, ammonia and hydrogen and the optional solvent into a trickle bed reactor containing at least two catalyst beds, and performing the reaction according to the following steps, wherein each catalyst bed is loaded with an amination catalyst;

[0053] (1) introducing 1,6-hexanediol, ammonia and hydrogen and the optional solvent into the first catalyst bed to perform the preliminary amination reaction, controlling the conversion rate of 1,6-hexanediol in the preliminary amination reaction according to the foregoing requirements, and obtaining the preliminary amination reaction product;

[0054] (2) The primary amination reaction product obtained in step (1) is fed into a second catalyst bed, and the product obtained in the reaction is further fed into a third catalyst bed, in the process, the material containing 6-amino-1-hexanol and the material containing cyclohexylideneimine are introduced into the second and third catalyst beds respectively, and the amination reaction is continued.

[0055] In the above method, more catalyst beds can be set up according to the actual reaction conditions, and the products obtained in each step are mixed or introduced separately into the catalyst beds for amination reaction, so as to further improve the selectivity and yield of hexamethylenediamine.

[0056] According to a particularly preferred embodiment of the present application, the trickle bed reactor comprises more than 3 catalyst beds, and the method comprises:

[0057] (A) 1,6-hexanediol, ammonia and hydrogen, and optionally a solvent, are introduced into a first catalyst bed for primary amination reaction, and the conversion rate of 1,6-hexanediol in the primary amination reaction is controlled according to the above requirements, to obtain a primary amination reaction product;

[0058] (B) The primary amination reaction product obtained in step (A) and the material containing 6-amino-1-hexanol (from the subsequent rectification unit) are introduced separately or together into a second catalyst bed for first continued amination reaction, to obtain a first continued amination reaction product;

[0059] (C) The first continued amination reaction product obtained in step (B) and the material containing cyclohexylideneimine are introduced separately or together into a third catalyst bed for second continued amination reaction.

[0060] In the above method, the material containing 6-amino-1-hexanol separated from the subsequent rectification unit and the material containing cyclohexylideneimine are recycled back to the reactor for continued reaction, thereby further improving the utilization rate of hexanediol and the yield of hexamethylenediamine. In actual operation, three or more trickle bed reactors each comprising at least one catalyst bed can be connected in series, and the reaction is carried out in each reactor according to the above method, and the specific process is not described here.

[0061] In the above method, a fourth or even more catalyst beds can be set up according to the actual reaction conditions, and the products obtained in each step are mixed or introduced separately into the catalyst beds for amination reaction, so as to further improve the selectivity and yield of hexamethylenediamine.

[0062] In the present application, there is no particular limitation on the selection of the trickle bed reactor, as long as the catalyst beds (and the circulation material feed ports between the beds) therein can meet the needs of the method provided by the present application.

[0063] According to a preferred embodiment of the present application, wherein the reference Figure 1 The trickle bed reactor comprises a cylinder 1, and a feed inlet 2, a distributor 3, a distributor 4, a first catalyst bed 5, a second catalyst bed 8, a third catalyst bed 10 and a discharge outlet 11 arranged in the cylinder 1 in sequence from top to bottom, wherein each catalyst bed is supported by a catalyst support plate, a first interlayer feed inlet 7 for circulating material is arranged between the first catalyst bed and the second catalyst bed, a second interlayer feed inlet 9 for circulating material is arranged between the second catalyst bed and the third catalyst bed, and a second distributor and a third distributor are arranged below the first interlayer feed inlet 7 and the second interlayer feed inlet 9, respectively (between the interlayer feed inlet and the lower catalyst bed).

[0064] Preferably, the method provided by the present application comprises introducing the reaction raw materials into the above-mentioned trickle bed reactor for reaction, and the final product flows out of the discharge outlet 11, and the specific reaction process comprises:

[0065] (A) introducing 1,6-hexanediol, ammonia and hydrogen, and optionally a solvent from the feed inlet 2, after passing through the distributor 3 and the distributor 4, the materials are uniformly mixed and uniformly sprayed into the first catalyst bed 5 to perform a preliminary amination reaction, and the conversion rate of 1,6-hexanediol in the preliminary amination reaction is controlled according to the above requirements to obtain a material containing 6-aminohexanol;

[0066] (B) the material containing 6-aminohexanol obtained in step (A) passes through the first catalyst bed and enters the second catalyst bed 8 to perform a first continued amination reaction. In this process, the material containing 6-aminohexanol separated by the subsequent rectification unit is introduced through the first interlayer feed inlet 7, uniformly sprayed into the second catalyst bed 8 through the second distributor, and performs a first continued amination reaction with the material containing 6-aminohexanol obtained in step (A);

[0067] (C) introducing the material containing cyclohexylamine obtained in step (A) through the second interlayer feed inlet 9, uniformly spraying it into the third catalyst bed 10 through the third distributor, and performing a second continued amination reaction with the product of step (B) passing through the second catalyst bed.

[0068] The inventors of the present application have also found in research that, since the ammonia in the ammonia reaction condition adopted by the present application exists in a supercritical state, the gas phase load in the ebullated bed reactor is low. When the gas phase load is low, most of the gas is dissolved in the liquid, and there is little gaseous gas reactant left, so it is difficult to uniformly "spray" the liquid on the catalyst through the existing gas-liquid distributor, and the liquid will concentrate and drop below the liquid passage pipe, resulting in uneven distribution of the liquid on the catalyst, making it difficult to achieve optimal catalytic reaction effect, thereby causing the reaction effect to decrease more when the reaction scale is expanded. In order to achieve uniform mixing of the reactants and uniform distribution of the reactants on the cross section of the catalyst bed layer under the above working condition, so that the catalytic reaction effect of the catalyst is further improved when the reaction scale is large, according to a preferred embodiment of the present application, the distributor used in the ebullated bed reactor adopted in the method provided by the present application comprises, from top to bottom, a cover plate (4-3), a downcomer (4-2), a distribution plate (4-1), a dispersion pipe (4-4), and a dispersion plate (4-5), Figure 2

[0069] The cover plate is located above the downcomer, and a gap is left between the cover plate and the downcomer.

[0070] Optionally, holes and / or slits are formed in the side wall of the downcomer.

[0071] Holes are formed in the distribution plate and correspond one-to-one to the downcomers arranged on the distribution plate.

[0072] The dispersion pipe corresponds one-to-one to the downcomer downstream in the material flow direction and is arranged perpendicularly to the distribution plate, and holes and / or slits are formed in the upper end of the side wall of the dispersion pipe.

[0073] The dispersion plate is connected perpendicularly to the downstream end of the side wall of the dispersion pipe in the material flow direction, and holes and / or slits are formed in the dispersion plate.

[0074] Figure 2 The structure of the above-mentioned distributor is shown in the schematic view, and from the figure, it can be seen that the holes formed in the distribution plate 4-1 are the same as the bottom surface of the downcomer 4-2, so that the downcomer 4-2 is embedded into the distribution plate 4-1 from above (penetrating the distribution plate). The downcomer 4-2 can form a certain liquid level on the distribution plate 4-1 and maintain a certain liquid storage capacity, so that the material is uniformly mixed or layered more clearly, and the downcomer 4-2 is arranged in a penetrating embedded manner in the distribution plate, so that the material flowing into the downcomer can enter the dispersion pipe below through the distribution plate.

[0075] ​A cover plate 4-3 is arranged above the downcomer 4-2, which functions to avoid the material flowing down above directly entering the downcomer before mixing, further improving the uniformity of the material. A gap is left between the downcomer 4-2 and the cover plate 4-3 to allow gas or light fluid to enter the downcomer 4-2, and the holes and / or slits opened on the side wall of the downcomer 4-2 are used for liquid or heavy fluid to enter.

[0076] Below the distribution plate 4-1, a dispersion pipe 4-4 corresponding to the downcomer 4-2 is arranged, and the upper end of the dispersion pipe 4-4 is connected to the lower end of the distribution plate 4-1 (which can be connected together by welding, buckles, screws, etc., preferably buckles, which are convenient for disassembly and maintenance). The upper end of the dispersion pipe 4-4 (i.e. the end close to the distribution plate 4-1) is provided with holes and / or slits for material to flow out of the dispersion pipe when the load is large. The lower end of the dispersion pipe 4-4 is connected to the pipe wall perpendicularly, and the dispersion plate 4-5 provided with holes and / or slits is arranged at the lower end of the dispersion pipe 4-4.

[0077] The inventor of the present application found through a large number of studies that in the distributor with the above characteristics, the opening rate of the downcomer on the upper side of the distribution plate is low, leaving sufficient space for the material to flow and mix, and the coverage rate of the dispersion pipe on the lower side of the distribution plate is high, which, in combination with the dispersion plate arranged therein, can distribute the liquid-like material (such as supercritical fluid material, etc.) as evenly as possible on the cross section of the catalyst bed. When a trickle bed reactor containing the above-mentioned distributor is used to prepare hexanediamine according to the method provided by the present application, the problem of poor material distribution uniformity caused by the ammonia in the feed being in a supercritical fluid state under the reaction conditions can be effectively solved.

[0078] In the present application, the ammoniation catalyst loaded in each catalyst bed in the trickle bed reactor and the preparation method thereof are not particularly limited, and any ammoniation catalyst in the art that can be used for the ammoniation of 1,6-hexanediol to prepare hexanediamine can be applied to the present application. For example, the catalysts disclosed in CN202011187657.5, CN202011187667.9, CN202011188203.X, CN202011188652.4, CN202011192987.3, CN202011188178.5, CN202011192975.0, CN202011187666.4, CN202011188198.2, etc. (or the catalysts prepared by the method disclosed therein) can be selected, and the disclosure of these applications is incorporated herein in its entirety.

[0079] According to some preferred embodiments of the present application, wherein the ammoniation catalyst comprises a main active component, an auxiliary agent and a carrier, the main active component is selected from at least one of Ru, Co, Ni and Cu, the auxiliary agent is selected from at least one of elements of Groups IIA, IB, IIB, IIIB, IVB, VIB, VIIB, IVA, VA, VIA and VIIA, and the carrier is selected from a catalyst carrier mainly composed of at least one of alumina, silica and molecular sieve.

[0080] According to preferred embodiments of the present application, wherein the main active component is selected from at least one of Co, Ni and Cu, the auxiliary agent is selected from at least one of Mg, Ca, Ag, Zn, La, Ce, Ti, Zr, Mo, Cr, Mn, Re, Sn, P, S and F, and the carrier is a carrier mainly composed of alumina and / or silica (i.e. the carrier material can be only alumina and / or silica, or can contain a small amount of doping material on this basis).

[0081] More preferably, the auxiliary agent is selected from at least two of Mg, Ag, Zn, La, Mn, Re, P and S.

[0082] According to preferred embodiments of the present application, wherein the content of the main active component is 15-40% and the content of the auxiliary agent is 0.01-5% based on 100% of the mass of the ammoniation catalyst, and the balance is the carrier.

[0083] Further, the present application also provides the use of the above-mentioned method in improving the selectivity and / or yield of hexamethylene diamine in the reaction of hydrogenation-ammoniation of 1,6-hexanediol to 1,6-hexanediamine.

[0084] The present application will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the present application, and are not used to limit the present application.

[0085] In the following examples, the reagents used are commercially available products purchased from regular chemical suppliers, and the purity is analytical grade. Unless otherwise specified, the operation temperature is room temperature (25±5°C).

[0086] Example 1

[0087] A trickle-bed reactor with an inner diameter of 32 mm (the structure can be referred to as that of the reactor in Example 1 of CN 101 1 1 1 1 1 1 A) was used. Figure 1) two segments of catalyst bed, each segment filled with 150 mL of catalyst, and an inter-bed feed port and a distributor were arranged between the two segments of catalyst bed. The catalyst was an ammoniation catalyst with Co as the main active component, Mo, Cu and Zn as the auxiliary components, and Al2O3-SiO2 as the carrier, which was prepared according to the method of Example 1 in CN202011192975.0. Specifically, the content of Co was 37%, the content of Mo was 1%, the content of Cu was 2%, the content of Zn was 1.5%, and the balance was the carrier, based on 100% of the mass of the ammoniation catalyst. Hexanediol was mixed with dioxane at a mass ratio of 1:1 at room temperature, heated and dissolved to obtain a hexanediol material, and then the preparation of hexamethylenediamine was carried out according to the following method:

[0088] (1) The hexanediol material and liquid ammonia were respectively pumped into a preheater, and hydrogen was sent into the preheater through a gas mass flow meter. The flow rate of hexanediol was 100 g / h, the preheater preheated the materials to 160°C, and then the preheated materials were mixed and sent into the top feed port of the trickle bed reactor (structure reference Figure 1 ) from the top. The materials entered the reactor in turn through the distributor 3 and the distributor 4, and were uniformly distributed into the first segment of catalyst bed 5. The first segment of catalyst bed was maintained at a temperature of 170°C by an electric heating furnace, and the preliminary ammoniation reaction was carried out under a pressure of 11 MPa. The conversion rate of hexanediol in the preliminary ammoniation reaction was about 69%, and the preliminary ammoniation reaction product was obtained and continued to flow into the second segment of catalyst bed.

[0089] (2) The materials containing 6-aminohexanol (containing 6-aminohexanol and a small amount of hexanediol) and the materials containing cyclohexylamine separated from the hexanediol ammoniation hexamethylenediamine rectification unit were introduced from the inter-bed feed port 7 between the first segment of catalyst bed and the second segment of catalyst bed, and were preheated to 150°C by a preheater before being introduced. The total flow rate was 84 g / h, of which the flow rate of hexanediol was 5 g / h, the flow rate of 6-aminohexanol was 35 g / h, and the flow rate of cyclohexylamine was 44 g / h. The introduced materials were uniformly dispersed into the second segment of catalyst bed 8 through the second distributor below the inter-bed feed port 7. The second segment of catalyst bed was maintained at a temperature of 160°C by an electric heating furnace, and the continued ammoniation reaction was carried out under a reaction pressure of 11 MPa.

[0090] The reaction was carried out under the above conditions, and the space velocity of hexanediol was 0.35 g·ml -1 ·h -1 , and the molar ratio of hexanediol:ammonia:hydrogen was 1:25:2, based on all the hexanediol entering the reactor. Finally, the product material obtained by the reaction flowed out through the material outlet 11.

[0091] Example 2

[0092] In a trickle bed reactor with an inner diameter of 32 mm, three catalyst beds were arranged, each of which was filled with 100 mL of catalyst (the same as in Example 1), and an interlayer feed port and a distributor were arranged between each two adjacent catalyst beds. Hexanediol was mixed with dioxane at a mass ratio of 1:1 at room temperature, heated and dissolved to obtain a hexanediol material, and then the preparation of hexamethylenediamine was carried out according to the following method:

[0093] (1) The hexanediol material and liquid ammonia were respectively pumped into a preheater, and hydrogen was sent into the preheater through a gas mass flow meter. The flow rate of hexanediol was 100 g / h, the preheater preheated the materials to 160°C, and then the preheated materials were mixed and sent into the trickle bed reactor from the top feed port 2 (structure reference Figure 1 ). After entering the reactor, the materials passed through the distributor 3 and the distributor 4 in turn and were uniformly distributed into the first catalyst bed 5. The first catalyst bed was maintained at a temperature of 190°C by an electric heating furnace, and the preliminary amination reaction was carried out under a pressure of 11 MPa. The conversion rate of hexanediol in the preliminary amination reaction process was controlled to be about 79%, and the preliminary amination reaction product was obtained and continuously flowed into the second catalyst bed.

[0094] (2) The material containing 6-aminohexanol separated from the hexanediol amination preparation of hexamethylenediamine rectification unit was introduced from the first interlayer feed port 7 between the first catalyst bed and the second catalyst bed by a pump, and was preheated to 160°C by a preheater before being introduced. The total flow rate was 40 g / h, of which the flow rate of hexanediol was 5 g / h and the flow rate of 6-aminohexanol was 35 g / h. The introduced material was uniformly dispersed into the second catalyst bed 8 through the second distributor below the first interlayer feed port 7. The second catalyst bed was maintained at a temperature of 170°C by an electric heating furnace, and the first continued amination reaction was carried out under a reaction pressure of 11 MPa.

[0095] (3) The material containing cyclohexylamine separated from the hexanediol amination preparation of hexamethylenediamine rectification unit was introduced into the reactor from the second interlayer feed port 9 between the second catalyst bed and the third catalyst bed by a pump, and the flow rate of cyclohexylamine was 44 g / h, which was preheated to 160°C by a preheater before being introduced. The introduced material was uniformly dispersed into the third catalyst bed 10 through the third distributor below the second interlayer feed port 9. The third catalyst bed was maintained at a temperature of 170°C by an electric heating furnace, and the second continued amination reaction was carried out under a reaction pressure of 11 MPa.

[0096] The reaction was carried out under the above conditions, and the space velocity of hexanediol was 0.35 g·ml -1 ·h -1The molar ratio of ethylene glycol:ammonia:hydrogen is 1:25:2. Finally, the product material obtained in the reaction is discharged through the material outlet 11.

[0097] Example 3

[0098] This example is used to illustrate the application effect of the method provided by the present application in a pilot level reaction.

[0099] A trickle bed reactor with an inner diameter of 600 mm is used for the reaction. The structure of the distributor used in the trickle bed reactor is shown in Figure 2 A downcomer 4-2 with an inner diameter of 30 mm, an outer diameter of 34 mm, and a height of 150 mm is arranged on the upper side of the distribution plate 4-1 with a thickness of 5 mm. The downcomer 4-2 is in an equilateral triangle distribution, and the opening rate on the distribution plate 4-1 is 30%. The downcomer 4-2 penetrates the distribution plate 4-1 and the lower end is flush with the bottom surface of the distribution plate 4-1. Two holes with a diameter of 10 mm are symmetrically arranged on the side wall of the downcomer 4-2, and the hole centers are 30 mm above the upper surface of the distribution plate 4-1. Then, 8 holes with a diameter of 5 mm are symmetrically staggered at equal intervals above the holes (4 holes on each side wall). A circular flat plate is arranged above the downcomer 4-2 as a cover plate 4-3, and the cover plate 4-3 and the downcomer 4-2 are connected by support columns and welded, and a gap with a height of 10 mm is left between the downcomer 4-2 and the cover plate 4-3. Square cross-section dispersion pipes 4-4 are arranged one-to-one corresponding to the downcomer 4-2 at the bottom surface of the distribution plate to make the material flowing out of the downcomer 4-2 enter the dispersion pipes 4-4, and the cross-sectional size of the dispersion pipes 4-4 makes the coverage rate on the distribution plate 4-1 80%. The dispersion pipes are connected with the distribution plate by buckling. Square dispersion plates 4-5 with the same cross-sectional area as the dispersion pipes are connected at the lower end of the dispersion pipes, and the dispersion plates are regularly and uniformly provided with elongated rectangular slits. The total area of the slits on each dispersion plate is 80% of the cross-sectional area of each downcomer. Horizontal slits (with an area of 20% of the slit area of the dispersion plate) are arranged at the top end of the dispersion pipes 4-4 (along the top end) at a distance of 0 mm from the bottom surface of the distribution plate for the material to flow out when the load is higher.

[0100] Two catalyst beds are arranged in the trickle bed reactor, each filled with 400 L of catalyst (the same as the catalyst in Example 1), and an interlayer feed port and an interlayer distributor (with the same structure as the above distributor) are arranged between the two catalyst beds.

[0101] The reaction was carried out in the same way as in Example 1, and the flow rate of the materials was enlarged in proportion to the reaction scale. In the reaction, the flow rate of the hexanediol fed into the trickle bed reactor in step (1) was 267 kg / h, and the total flow rate of the material containing 6-aminohexanol and the material containing cyclohexylideneimine in step (2) was 224 g / h, wherein the flow rate of the hexanediol was 13.3 kg / h, the flow rate of the 6-aminohexanol was 93.3 kg / h, and the flow rate of the cyclohexylideneimine was 117.3 kg / h. The materials were preheated at the temperature in Example 1 before being fed into the catalyst bed, and the reaction temperature and pressure of each catalyst bed were the same as in Example 1.

[0102] The reaction was carried out under the above conditions, and the space velocity of the hexanediol was 0.35 g-ml -1 ·h -1 , and the molar ratio of hexanediol:ammonia:hydrogen was 1:25:2.

[0103] Comparative Example 1

[0104] A trickle bed reactor with an inner diameter of 32 mm was filled with 300 mL of the catalyst (which was the same as in Example 1), and the catalyst was not segmented.

[0105] The raw materials were mixed in a ratio of hexanediol:aminohexanol:cyclohexylideneimine:dioxane = 105 g:35 g:44 g:100 g. The raw materials and liquid ammonia were fed into a preheater by pumps, and hydrogen was fed into the preheater by a gas mass flow meter. The total flow rate of the raw materials was controlled to be 284 g / h, and the flow rates of the liquid ammonia and hydrogen were controlled so that the molar ratio of hexanediol:ammonia:hydrogen was 1:25:2. The materials were preheated to 160°C, and then were introduced together from the top of the feed inlet 2 of the trickle bed reactor (the structure can be referred to Figure 1 , but only contains one catalyst bed), and the materials passed through the distributor 3 and the distributor 4 in turn after entering, and were uniformly distributed into the catalyst bed. The temperature of the catalyst bed was maintained at 170°C by an electric heating furnace. The amination reaction was carried out under a reaction pressure of 11 MPa. Finally, the product material obtained by the reaction flowed out through the material outlet 11.

[0106] Comparative Example 2

[0107] The method in Example 1 was used, except that the reaction temperature in step (1) was adjusted to 195°C so that the conversion rate of the hexanediol in the preliminary amination reaction process was about 90%. The remaining operations and conditions were the same as in Example 1.

[0108] Test Example 1

[0109] The products obtained in the above examples and comparative examples were sampled and analyzed by gas chromatography analysis method, and were calibrated by preparing a standard sample correction factor;

[0110] The conversion rate and selectivity are calculated according to the following formula based on the molar content of each component in the reaction solution.

[0111]

[0112]

[0113] The selectivity of cyclohexylamine is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of cyclohexylamine, the selectivity of aminohexanol is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of aminohexanol, and so on, and the selectivity of "amine and others" is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of amine dimer x 2, wherein the amine dimer refers to the dimer of 1,6-hexanediamine (bis(hexamethylene)triamine, also known as N-(6-aminohexyl)-1,6-hexanediamine) and the dimer of 1,6-hexanediamine and cyclohexylamine (N-(6-aminohexyl)cyclohexylamine). The results are shown in Table 1. 12 The selectivity of cyclohexylamine is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of cyclohexylamine, the selectivity of aminohexanol is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of aminohexanol, and so on, and the selectivity of "amine and others" is calculated by replacing the molecule in the above formula for the selectivity of hexamethylenediamine with the molar content of amine dimer x 2, wherein the amine dimer refers to the dimer of 1,6-hexanediamine (bis(hexamethylene)triamine, also known as N-(6-aminohexyl)-1,6-hexanediamine) and the dimer of 1,6-hexanediamine and cyclohexylamine (N-(6-aminohexyl)cyclohexylamine). The results are shown in Table 1.

[0114] Table 1

[0115]

[0116] As can be seen from Table 1, the method for preparing hexamethylenediamine by aminating hexylene glycol provided by the present application has a higher conversion rate and a more excellent selectivity of hexamethylenediamine than the conventional method (Comparative Example 1), and generates C 12 amine and others" is lower. This indicates that the method of the present application can make the catalyst fully play the role of alcohol amination in the upper catalyst bed, and then introduce the intermediate and equilibrium products between the catalyst beds, which can just promote the continuous amination of aminohexanol, and the equilibrium of cyclohexylamine is exerted in the right place. Moreover, as can be seen from the results of Example 3, by using the method provided by the present application in combination with the trickle bed reactor with a specific distributor, a higher conversion rate of hexylene glycol and selectivity of hexamethylenediamine can be achieved even after the scale of the reaction is expanded, which indicates that the method provided by the present application is also expected to improve the selectivity of hexamethylenediamine and the utilization rate of hexylene glycol raw materials in actual production, thereby improving the enterprise benefits.

[0117] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application and fall within the protection scope of the present application.

Claims

1. A process for the amination of 1,6-hexanediol to 1,6-hexanediamine, characterized in that, The method comprises: (1) subjecting 1,6-hexanediol to a preliminary amination reaction with ammonia and hydrogen and optionally a solvent, the conversion rate of 1,6-hexanediol in the preliminary amination reaction being controlled to be not more than 85%, to obtain a preliminary amination reaction product; (2) subjecting the preliminary amination reaction product obtained in step (1) to a continued amination reaction, in which process the material containing cyclohexylideneimine and the optional material containing 6-amino-1-hexanol are introduced separately or together into the preliminary amination reaction product obtained in step (1) to carry out the continued amination reaction separately or together.

2. The method of claim 1, wherein, The method uses a trickle bed reactor containing 2 or more catalyst beds connected in series to carry out the reaction, wherein the preliminary amination reaction is carried out in the first catalyst bed and the continued amination reaction is carried out in the second and subsequent catalyst beds, and each catalyst bed is provided with an amination catalyst; And / or, the method uses at least 2 trickle bed reactors connected in series to carry out the reaction, each of which contains at least one catalyst bed, wherein the preliminary amination reaction is carried out in the first trickle bed reactor and the continued amination reaction is carried out in the second and subsequent trickle bed reactors, and each trickle bed reactor is provided with an amination catalyst.

3. The method of claim 2, wherein, The conditions of the preliminary amination reaction and / or the continued amination reaction include: the reaction temperature of the catalyst bed is 150-220℃, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:10-50:0.2-2, calculated based on all the 1,6-hexanediol entering the reactor, the space velocity of 1,6-hexanediol is 0.1-0.4 g·mL -1 ·h -1 .

4. The method of claim 3, wherein, The conditions of the preliminary amination reaction and the continued amination reaction are the same or different.

5. The method of claim 3, wherein, The conditions of the preliminary amination reaction and the continued amination reaction are different.

6. The method of any one of claims 3-5, wherein, The conditions of the preliminary amination reaction include that the reaction temperature of the catalyst bed is 170-210°C, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:10-40:0.2-1 based on all the 1,6-hexanediol entering the reactor, and the space velocity of 1,6-hexanediol is 0.1-1.6 g·mL based on the volume of the catalyst used for the preliminary amination reaction. -1 ·h -1 ; And / or, the conditions of the continued amination reaction include that the reaction temperature of the catalyst bed is 150-190℃, the pressure is 7-20 MPa, the molar ratio of 1,6-hexanediol:ammonia:hydrogen is 1:25-50:0.2-1 based on all the 1,6-hexanediol entering the reactor, and the mass ratio of 1,6-hexanediol to cyclohexylideneimine in the material introduced into the second and subsequent catalyst beds or the second and subsequent trickle bed reactors during the continued amination reaction is 1:0.2-0.

6.

7. The method of claim 6, wherein, The reaction temperature of the continued amination reaction is 10-30℃ lower than that of the preliminary amination reaction, and the amine alcohol ratio is not lower than that of the preliminary amination reaction.

8. The method of claim 1, wherein, The conversion rate of 1,6-hexanediol in the preliminary amination reaction is controlled to be not more than 80%.

9. The method of claim 8, wherein, The conversion rate of 1,6-hexanediol in the preliminary amination reaction is controlled to be not more than 75%.

10. The method of claim 9, wherein, The conversion rate of 1,6-hexanediol in the preliminary amination reaction is controlled to be not more than 70%.

11. The method of claim 1, wherein, The material containing cyclohexylideneimine comes from a subsequent rectification unit; And / or, the material containing 6-amino-1-hexanol comes from a subsequent rectification unit.

12. The method of claim 11, wherein, The material containing cyclohexylideneimine comes from a subsequent rectification unit, and the content of cyclohexylideneimine is not less than 50% by weight; And / or, the material containing 6-amino-1-hexanol comes from a subsequent rectification unit, and the content of 6-amino-1-hexanol is not less than 30% by weight.

13. The method of claim 11 or 12, wherein, The material containing 6-amino-1-hexanol also contains 1,6-hexanediol.

14. The method of claim 13, wherein, The content of 1,6-hexanediol in the material containing 6-amino-1-hexanol is not more than 70% by weight.

15. The method of claim 13, wherein, The amount of the material containing 6-amino-1-hexanol introduced in the process of the continued amination reaction in step (2) is such that the 1,6-hexanediol introduced in step (1) accounts for 75-100% by weight of all 1,6-hexanediol.

16. The method of claim 13, wherein, The mass ratio of 6-amino-1-hexanol to all 1,6-hexanediol in the material containing 6-amino-1-hexanol introduced in the process of the continued amination reaction in step (2) is 0.2-0.6:

1.

17. The method of claim 2, wherein, The 1,6-hexanediol, ammonia and hydrogen, and optionally a solvent, are preheated to 120-170°C and then introduced into the first catalyst bed or the first trickle bed reactor to perform the preliminary amination reaction. The material containing cyclohexylamine and the optional material containing 6-amino-1-hexanol are preheated to 150-170°C and then introduced into the second or subsequent catalyst bed or the second or subsequent trickle bed reactor to perform the continued amination reaction.

18. The method of claim 1, wherein, The method is performed using a trickle bed reactor comprising three or more catalyst beds, and the method comprises: (A) introducing 1,6-hexanediol, ammonia and hydrogen, and optionally a solvent, into the first catalyst bed to perform the preliminary amination reaction and obtain a preliminary amination reaction product; (B) introducing the preliminary amination reaction product obtained in step (A) and a material containing 6-amino-1-hexanol into the second catalyst bed to perform the first continued amination reaction and obtain a first continued amination reaction product; (C) introducing the first continued amination reaction product obtained in step (B) and a material containing cyclohexylamine into the third catalyst bed to perform the second continued amination reaction. Alternatively, the method is performed using three or more trickle bed reactors connected in series, each of which contains at least one catalyst bed, and the method comprises: (A) introducing 1,6-hexanediol, ammonia and hydrogen, and optionally a solvent, into the first trickle bed reactor to perform the preliminary amination reaction and obtain a preliminary amination reaction product; (B) introducing the preliminary amination reaction product obtained in step (A) and a material containing 6-amino-1-hexanol into the second trickle bed reactor to perform the first continued amination reaction and obtain a first continued amination reaction product; (C) introducing the first continued amination reaction product obtained in step (B) and a material containing cyclohexylamine into the third trickle bed reactor to perform the second continued amination reaction.

19. The method of claim 2, wherein, The amination catalyst comprises a main active component, an auxiliary agent and a carrier, the main active component is selected from at least one of Ru, Co, Ni and Cu, the auxiliary agent is selected from at least one of elements of groups IIA, IB, IIB, IIIB, IVB, VIB, VIIB, IVA, VA, VIA and VIIA, and the carrier is selected from a catalyst carrier mainly comprising at least one of alumina, silica and molecular sieve.

20. The method of claim 19, wherein, The main active component is selected from at least one of Co, Ni and Cu, the auxiliary agent is selected from at least one element of Mg, Ca, Ag, Zn, La, Ce, Ti, Zr, Mo, Cr, Mn, Re, Sn, P, S and F, and the carrier is an alumina and / or silica-based carrier.

21. The method of claim 20, wherein, The auxiliary agent is selected from at least two elements of Mg, Ag, Zn, La, Mn, Re, P and S.

22. The method of any one of claims 19-21, wherein, The content of the main active component is 15-40%, the content of the auxiliary agent is 0.01-5%, and the balance is the carrier, based on 100% of the mass of the ammoniation catalyst.

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