CN117776926A

CN117776926A - Recycling method for residue of rectifying still

Info

Publication number: CN117776926A
Application number: CN202311653775.4A
Authority: CN
Inventors: 梅学赓; 刘鑫; 郭昊天; 丁克鸿; 王根林; 王刚; 王鑫宇
Original assignee: Jiangsu Yangnong Chemical Group Co Ltd
Current assignee: Jiangsu Yangnong Chemical Group Co Ltd
Priority date: 2023-12-04
Filing date: 2023-12-04
Publication date: 2024-03-29

Abstract

A recycling method of residue in a rectifying still. There is provided a process for preparing pentylamine, the process comprising the steps of: (1) Adding water into the residue of a rectifying kettle obtained in the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime, and heating and dissolving to obtain a homogeneous solution; (2) And (3) under the hydrogen atmosphere, the homogeneous solution obtained in the step (1) enters a fixed bed reactor filled with a catalyst to react to obtain the pentylamine.

Description

Recycling method for residue of rectifying still

Technical Field

The application relates to the technical field of petrochemical industry, in particular to a recycling method for rectifying still residues in caprolactam preparation by gas phase rearrangement.

Background

Caprolactam is an important organic chemical raw material and is mainly used for producing nylon 6 engineering plastics and nylon 6 fibers. At present, 90% of the production processes in the industrial production of caprolactam are all subjected to Beckmann rearrangement of cyclohexanone oxime. There are two main processes for the preparation of caprolactam from cyclohexanone oxime: a liquid phase beckmann rearrangement and a gaseous phase beckmann rearrangement. There are a number of disadvantages to liquid phase rearrangement compared to gas phase rearrangement: firstly, liquid ammonia with higher economic value is consumed, and a large amount of low-value ammonium sulfate is produced as a byproduct; secondly, the problems of equipment corrosion and environmental pollution exist. The gas phase rearrangement uses high silicon molecular sieve or solid acid as catalyst, and does not produce by-product ammonium sulfate, so that it solves the problems of equipment corrosion and environmental pollution, etc. existing in the traditional process, and is a green and environment-friendly new process.

However, due to the high temperature of the vapor phase beckmann rearrangement reaction, many side reactions (e.g., alcoholysis, polymerization, etc.) tend to occur, and a wide variety of by-products are produced. The caprolactam is used as a monomer of synthetic fibers and engineering plastics, and the product quality requirement on the caprolactam in the organic chemical production is very strict, so that the caprolactam obtained by the vapor phase rearrangement of cyclohexanone oxime needs further refining treatment. In the processes of de-duplication, rectification and refining of caprolactam, a kettle often contains some caprolactam oligomers, and finally residues, solid wastes, pollutes the environment and reduces the production efficiency. In order to improve the economy of the gas phase rearrangement reaction, the method is particularly important for further recycling and recovering caprolactam from the kettle residue of caprolactam heavy removal and rectification.

The traditional treatment method of the residue of the rectifying still is incineration or environmental protection biochemical treatment. Not only generates a large amount of CO during incineration ₂ And can generate a large amount of NO _X The tail gas treatment load and the emission concentration of the incinerator are increased, and polycaprolactam also easily forms bonding residues in the incinerator, so that the treatment difficulty of the residue of the rectifying still is increased. By the environment-friendly biochemical treatment, the cost of the biochemical treatment is high due to the fact that organic impurities which are difficult to degrade and biochemically are more.

Chinese patent publication No. CN 106146374B discloses a method for recycling a gas phase rearrangement product of cyclohexanone oxime to fractionate a heavy residual liquid, which comprises dissolving the gas phase rearrangement product of cyclohexanone oxime in a solvent, crystallizing and distilling to obtain caprolactam. However, the process only extracts caprolactam in heavy residual liquid, and the caprolactam oligomer is not treated, so that the caprolactam recovery rate is lower, and the waste liquid discharge is inevitably increased due to the use of an organic solvent.

CN114516838A discloses a method for recycling residue of rectifying still, which obtains caprolactam product by hydrolysis method. The method can effectively degrade caprolactam oligomer in the residue of the rectifying still, thereby improving the recovery rate of caprolactam.

Pentylamine is an important chemical raw material, is widely applied to antioxidants, emulsifying agents, pesticides, rubber chemicals, flotation agents and the like, is used for synthesizing high-value medicaments, and has the advantage of high economic value. At present, the industrial production of the pentylamine is carried out by using a valeronitrile method, the existing valeronitrile method needs to realize hydrogenation reduction under the environment of high-pressure hydrogen to produce the pentylamine, but about 30 percent of dipentamine and tripentamine in the product need to be separated from the dipentamine and the tripentamine by rectification, so that the pentylamine with higher purity is obtained. The reaction conditions in the process of preparing the pentylamine need high pressure, which is unfavorable for safe production, and the reaction yield is low, the production cost is high, and more byproducts of the dipentylamine and the tripentylamine are produced.

Thus, there remains a need in the art for a new method for recycling the residue of a rectifying still in the preparation of caprolactam by gas phase rearrangement which allows for the direct formation of pentylamine in high yields and at low cost.

Disclosure of Invention

The invention aims to provide a method for recycling rectifying still residues in caprolactam preparation by gas phase rearrangement, which can directly form pentylamine with high yield and low cost.

The inventor of the application finds that the rectifying still residue obtained in the process of preparing caprolactam by cyclohexanone oxime gas-phase Beckmann rearrangement can generate directly to form pentylamine by hydrolysis and hydrogen decarboxylation through a great deal of researches.

In one aspect, the present application provides a method for preparing pentylamine, the method comprising the steps of:

(1) Adding water into the residue of a rectifying kettle obtained in the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime, and heating and dissolving to obtain a homogeneous solution;

(2) And (3) under the hydrogen atmosphere, the homogeneous solution obtained in the step (1) enters a fixed bed reactor filled with a catalyst to react to obtain the pentylamine.

In another aspect, the present application provides a pentylamine product prepared by the methods of the present application.

Drawings

FIG. 1 depicts the gas chromatograms of pentylamine obtained in examples 7-10.

FIG. 2 depicts the gas chromatograms of pentylamine obtained in examples 11-22.

FIG. 3 depicts the gas chromatograms of pentylamine obtained in examples 23-32.

Detailed Description

The "ranges" disclosed herein are defined as lower and upper limits, with the given ranges being defined by selecting a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular ranges. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

In this application, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new solutions, unless specifically stated otherwise.

In the present application, all technical features mentioned herein as well as preferred features may be combined with each other to form new solutions, if not specifically stated.

In the present application, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

In the present application, references herein to "comprising" and "including" mean open, and may be closed, unless otherwise specified. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

In the description herein, unless otherwise indicated, "above" and "below" are intended to include the present number, and "one or more" means two or more.

In the description herein, unless otherwise indicated, the term "or" is inclusive. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

In this context, unless otherwise specified, the percentages (%) or parts refer to weight percentages or parts by weight relative to the composition.

In this context, the sum of the contents of the individual components in the composition is 100%, if not stated to the contrary.

In this context, the sum of the parts of the components in the composition may be 100 parts by weight, if not stated to the contrary.

In this context, unless otherwise indicated, "a combination thereof" means a multicomponent mixture of the elements, e.g., two, three, four, and up to the maximum possible multicomponent mixture.

The term "a" as used in this specification means "at least one" unless specifically indicated.

In this context, unless otherwise indicated, each reaction is carried out at ambient temperature and pressure.

In the application, the "rectifying still residue obtained in the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime" refers to a residue generated in the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime, and specifically is a residue formed at the bottom of the rectifying still when a crude caprolactam product obtained by vapor phase rearrangement of cyclohexanone oxime is subjected to weight removal and rectification treatment. Thus, the term "rectifying still residue" and "rectifying still residue" obtained in the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime "in this application have the same meaning, and are derived from the process of preparing caprolactam by the vapor phase Beckmann rearrangement of cyclohexanone oxime. For example, the "rectifying still residue" in this application comes from the Yannong group.

In step (1) of the process of the present application, the water may be water commonly used in the art, including, but not limited to, deionized water and distilled water.

In step (1) of the method of the present application, the weight ratio of the rectifying still residue to water may be 1:0.1-5, e.g. 1:0.3-5. In order to better hydrolyze caprolactam oligomer in the residue of the rectifying still, the weight ratio of the residue of the rectifying still to water is preferably 1 or less: 1, for example 1:1-5, preferably 1:1-3, more preferably 1:1-2.

In step (1) of the process of the present application, the heating temperature may be from 30 to 150 ℃, for example from 40 to 120 ℃, preferably from 50 to 90 ℃, more preferably from 60 to 80 ℃.

In step (1) of the process of the present application, the time of the dissolution by heating may be from 0.5 to 24 hours, for example from 1 to 20 hours, preferably from 1 to 10 hours, preferably from 4 to 8 hours.

In step (1) of the process of the present application, the heating and dissolving may be performed under the application of physical action to accelerate the hydrolysis of the caprolactam oligomer. The physical action includes, but is not limited to, stirring, sonication, shaking, or a combination thereof.

In general, step (1) of the process of the present application may form a homogeneous solution, mainly because caprolactam oligomer is hydrolyzed under heating to form aminocaproic acid. The main component in the homogeneous solution is therefore aminocaproic acid, i.e. the hydrolysis product of caprolactam.

In step (1) of the process of the present application, the homogeneous solution represents a homogeneous solution in which no macroscopic solid impurities are present. In one example of the present application, the solid impurities in the homogeneous solution may be further removed by filtration.

In step (2) of the process of the present application, the catalyst may be one or more combinations of modified beta molecular sieves, modified Y-type molecular sieves, or modified ZSM-5 molecular sieves.

In one example of the present application, the modified molecular sieve (e.g., modified beta molecular sieve, modified Y-type molecular sieve, or modified ZSM-5 molecular sieve) is a molecular sieve catalyst (e.g., beta molecular sieve, Y-type molecular sieve, or ZSM-5 molecular sieve) loaded with one or more metals selected from Mn, sc, ni, fe, zn, pt, pd, rh, mo, ti, cr, co, cu, ga, V, ru. In order to obtain a higher pentylamine yield, the metal is preferably Ni, mo or a combination thereof, more preferably a combination of Ni and Mo.

In step (2) of the process of the present application, the hydrogen atmosphere means that hydrogen is introduced into a fixed bed reactor filled with a catalyst. The hydrogen may be commercially available hydrogen or hydrogen that is a byproduct of petrochemical processes.

In step (2) of the process of the present application, the mass space velocity of the homogeneous solution added to the fixed bed reactor may be from 0.01 to 1h, based on the weight of the rectifying still residue ^-1 For example 0.01-0.5h ^-1 . For better pentylamine yields, the mass space velocity is preferably 0.05-0.1h ^-1 。

In step (2) of the process of the present application, the reaction temperature in the fixed bed reactor may be from 200 to 900 ℃, for example from 300 to 800 ℃, preferably from 400 to 600 ℃.

In step (2) of the process of the present application, the pressure in the fixed bed reactor may be from 0.01 to 5MPa, for example from 0.05 to 3MPa, preferably from 0.1 to 2MPa, more preferably from 0.3 to 0.8MPa.

In step (2) of the method of the present application, the mass ratio of hydrogen to homogeneous solution may be 0.01 to 1:1, for example 0.01-0.5:1, preferably 0.01 to 0.2:1. in order to obtain better pentylamine yields, the hydrogen gas and homogeneous solution mass ratio is preferably 0.02-0.1:1.

compared with the prior art, the invention has the following advantages:

(1) The caprolactam rectifying still residue is converted into the pentylamine by one step through the high-temperature hydrolysis decarboxylation process, so that the process is simple, the conversion efficiency is high, and the industrialization is easy;

(2) The residue of the low-value caprolactam rectifying still is converted into high-purity high-value pentylamine, so that the cost is further reduced and the economic benefit is improved.

(3) The process realizes the recycling utilization of caprolactam rectifying still residues, reduces the processing capacity of the traditional incineration, landfill and other processes, reduces the resource waste and environmental pollution, and accords with the principle of green chemical process.

The following examples illustrate the invention in more detail, but do not limit the invention further, unless otherwise stated, wherein "%" is "% by mass".

The dissolution ratio R of the residual oligomers in the rectifying still in Table 1 _d The calculation formula of the ratio of the mass of the oligomer dissolved in the deionized water to the residual mass of the initial feeding rectifying kettle is as follows:

wherein m is _{Initially, the method comprises} For the initial mass of the residue of the rectifying still before dissolution, m _{The remainder is} The residual mass of the kettle after dissolution.

Total yield Y of the target product pentylamine in tables 2 to 4 _{Pentylamine (Pentam)} The ratio of the mass of the target product pentylamine to the residual mass of the initial feeding rectifying kettle is obtained by post-treatment rectification, and the calculation formula is as follows:

wherein m is _{Pentylamine (Pentam)} For post-treatment rectification to obtain the quality of the target product pentylamine, m _{Initially, the method comprises} Is the residual mass of the rectifying still for initial feeding.

Examples 1 to 6:

100g of residue (Yannong group) of the rectifying still and deionized water with different weights are put into a reaction kettle, stirred and dissolved for different time under different time conditions, and filtered by filter paper to obtain homogeneous solution. The number average molecular weight of the polycaprolactam of the oligomer in the homogeneous phase solution is 237-1409 by a liquid chromatography and mass spectrometry combined test (LCMS), and the dissolution proportion of the residual oligomer in the rectifying still in the obtained homogeneous phase solution is shown in the table 1.

TABLE 1 dissolution ratio of residual oligomers in rectifying still

Examples 7 to 10:

20g of Ni/Mo/ZSM-5 molecular sieve purchased from Nanka catalyst plant was charged into a fixed bed reactor having a bed length of 50cm and a bed diameter of 0.6 cm. The homogeneous solution obtained in example 5 was then subjected to a mass space velocity of the homogeneous solution of 0.1h ^-1 Introducing into a fixed bed reactor, and introducing hydrogen with different mass ratio from the homogeneous solution into the fixed bed reactor for reaction, wherein the fixed bed reaction temperature is 500 ℃, the reaction pressure is 0.5MPa, and the reaction is carried outThe total yield of pentylamine obtained by rectifying the reaction solution is shown in Table 2. The gas chromatography of pentylamine is shown in FIG. 1.

TABLE 2

	Hydrogen to homogeneous solution mass ratio	Total yield of pentylamine/%
			Example 7	0.01:1	65.34
Example 8	0.02:1	78.62
			Example 9	0.1:1	79.89
Example 10	0.2:1	63.37

Examples 11 to 22:

maintaining the mass ratio of hydrogen to homogeneous solution to be 0.1, loading 20g of different catalysts into a fixed bed reactor with the bed length of 50cm and the bed diameter of 0.6cm, and feeding the homogeneous solution obtained in the example 5 into the fixed bed reactor for reaction at the mass space velocity of 0.1h < -1 >, wherein the fixed bed reaction temperature is 500 ℃, the reaction pressure is 0.5MPa, and the total yield of pentylamine is obtained by post-rectifying the reaction liquid, wherein the specific reference is shown in Table 3. The gas chromatography of pentylamine is shown in FIG. 2.

TABLE 3 Total yield of pentylamine for different catalyst types

Sample name	Catalyst type	Total yield of pentylamine/%
			Example 11	Ni/ZSM-5 molecular sieve	77.34
Example 12	Ni/Mo/ZSM-5 molecular sieve	80.62
			Example 13	Ni/Ru/ZSM-5 molecular sieve	75.89
Example 14	Ni/Rh/Pt/ZSM-5 molecular sieve	78.37
			Example 15	Cr/beta molecular sieve	75.36
Example 16	Cr/Rh/beta molecular sieve	77.96
			Example 17	Cr/Pd/beta molecular sieve	78.36
Example 18	Cr/Ru/Pt/beta molecular sieve	71.15
			Example 19	Fe/Y molecular sieve	75.65
Example 20	Fe/Ru/Y molecular sieve	77.16
			Example 21	Fe/Pd/Y molecular sieve	75.64
Example 22	Fe/Rh/Pt/Y molecular sieve	73.37

Examples 23 to 32:

maintaining the mass ratio of the hydrogen to the homogeneous solution to be 0.1, and filling 20g of Ni/Mo/ZSM-5 molecular sieve catalyst into a tubular fixed bed reactor with the bed length of 50cm and the bed diameter of 0.6 cm. The homogeneous solution obtained in example 5 is fed into a fixed bed reactor at different mass airspeed to react at different temperatures and different pressures, and the total yield of pentylamine obtained by rectifying the reaction solution is shown in Table 4. The gas chromatography of pentylamine is shown in FIG. 3.

TABLE 4 Total yield of pentylamine under different reaction conditions

Comparative example 1:

this comparative example provides a method for recycling bottoms from the gas phase rearrangement of caprolactam production which differs from example 8 in that the fixed bed system is not fed with hydrogen and the overall pentylamine yield is 49.56%.

The present invention is not limited to the embodiments of the present invention.

Specific examples are set forth herein to illustrate the structure and embodiments of the present invention, and the above examples are only for aiding in the understanding of the core concept of the present invention. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims

1. A process for preparing pentylamine, the process comprising the steps of:

2. The method of claim 1, wherein the weight ratio of the rectifying still residue to water is 1:0.1-5, e.g. 1:0.3-5; preferably, the weight ratio of the residue of the rectifying still to water is 1 or less: 1, for example 1:1-5, preferably 1:1-3, more preferably 1:1-2.

3. A method according to claim 1, wherein the heating temperature is 30-150 ℃, such as 40-120 ℃, preferably 50-90 ℃, more preferably 60-80 ℃.

4. The method of claim 1, wherein the catalyst is one or more of a modified beta molecular sieve, a modified Y-type molecular sieve, or a modified ZSM-5 molecular sieve; preferably, the modified molecular sieve (e.g., modified beta molecular sieve, modified Y-type molecular sieve, or modified ZSM-5 molecular sieve) is a molecular sieve catalyst (e.g., beta molecular sieve, Y-type molecular sieve, or ZSM-5 molecular sieve) loaded with one or more metals selected from Mn, sc, ni, fe, zn, pt, pd, rh, mo, ti, cr, co, cu, ga, V, ru; preferably, the metal is preferably Ni, mo or a combination thereof, more preferably a combination of Ni and Mo.

5. The method of claim 1, wherein the hydrogen atmosphere represents the introduction of hydrogen into a fixed bed reactor packed with catalyst.

6. The process of claim 1, wherein the homogeneous solution is fed to the fixed bed reactor at a mass space velocity of from 0.01 to 1h based on the weight of the rectifying still residue ^-1 For example 0.01-0.5h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the Preferably, the mass space velocity is preferably 0.05 to 0.1h ^-1 。

7. The method according to claim 1, wherein the reaction temperature in the fixed bed reactor may be 200-900 ℃, such as 300-800 ℃, preferably 400-600 ℃.

8. The process according to claim 1, wherein the pressure in the fixed bed reactor may be in the range of 0.01-5MPa, such as 0.05-3MPa, preferably 0.1-2MPa, more preferably 0.3-0.8MPa.

9. The method of claim 1, wherein the mass ratio of hydrogen to homogeneous solution is 0.01-1:1, for example 0.01-0.5:1, preferably 0.01 to 0.2:1, a step of; preferably, the mass ratio of the hydrogen to the homogeneous solution is 0.02-0.1:1.

10. a pentylamine product prepared by the method of any one of claims 1-9.