CN114805025A - Separation and purification method of cyclohexanol and butyl cyclohexyl ether - Google Patents

Abstract

The invention provides a method for separating and purifying cyclohexanol and butyl cyclohexyl ether. The purity of the butyl cyclohexyl ether and cyclohexanol obtained by the method is greater than 99.5 wt %. The extractant in the method is a high-boiling compound extractant, and the alkyl imidazole ionic liquid is a strong polar solvent, which can significantly increase the relative volatility between cyclohexanol and butylcyclohexyl ether; the heterocyclic ring containing N or S The compound can play a role in adjusting the viscosity of the composite system, and at the same time has good solubility, which can ensure that the extractant and cyclohexanol are in a homogeneous state, thereby ensuring the separation efficiency of the rectification process and avoiding the mutual solubility of ionic liquid and alcohol. The rectification separation efficiency is low due to the difference in degree, and at the same time, it can solve the problem of increased system operation material consumption and energy consumption and shortened dehydrogenation catalyst life caused by the continuous accumulation of the by-product butyl cyclohexyl ether in the cyclohexanone recycling material during the production process of cyclohexanone. And other issues.

Description

A kind of separation and purification method of cyclohexanol and butyl cyclohexyl ether

technical field

The invention relates to the technical field of separation and purification, in particular to a separation and purification method of cyclohexanol and butylcyclohexyl ether.

Background technique

Cyclohexanone is an important chemical raw material for preparing nylon intermediates such as caprolactam and adipic acid. It is also widely used in organic solvents, synthetic rubber and industrial coatings.

At present, there are three main production processes of cyclohexanone at home and abroad: one is the hydrogenation of phenol; the second is the hydrogenation of benzene; the third is the liquid-phase air oxidation of cyclohexane. Among them, the liquid-phase air oxidation of cyclohexane is a widely used process for preparing cyclohexanone at present. The process is carried out in two steps, the first step is oxidation reaction, and the second step is decomposition reaction. No catalyst is used in the oxidation reaction, cyclohexanone and cyclohexanol are used as initiators, and cyclohexane is oxidized with air or oxygen to cyclohexyl hydroperoxide, cyclohexanol, cyclohexanone, and monocarboxylic acids below C6 , Dicarboxylic acids below C6 and some other by-products. Cobalt acetate is used as a catalyst in the decomposition reaction process, and cyclohexyl hydroperoxide is decomposed into cyclohexanol and cyclohexanone under low temperature and alkaline conditions, and the decomposed reaction products are subjected to rectification and separation, and finally high-purity cyclohexanone is obtained. product and crude cyclohexanol. Crude cyclohexanol is converted into cyclohexanone by dehydrogenation reaction as a recycle material, and the reaction product is combined with the main reaction product and then purified and separated, and finally mainly cyclohexanone product is obtained.

In the process of preparing cyclohexanone by liquid-phase air oxidation of cyclohexane, the conversion rate of cyclohexanone oxidation process is generally 3%-5%, and the total selectivity of cyclohexanol and cyclohexanone is about 80%. The ratio of cyclohexanol is about 1:1, and by-products will be generated at the same time, among which butyl cyclohexyl ether is one of the by-products. The difference between the boiling point of butyl cyclohexyl ether and the boiling point of cyclohexanol is very small, and the conventional separation process cannot achieve effective separation of butyl cyclohexyl ether and cyclohexanol, which means that butyl cyclohexyl ether will always circulate with cyclohexanol in the system, and It accumulates continuously in the system, and the concentration keeps increasing. In the current production, when the concentration of butyl cyclohexyl ether in the cyclohexanol circulating material is greater than 10%, the device needs to be shut down and the cyclohexanol material in the system is thrown out, which will not only affect the production, reduce the economic benefits of the device, but also reduce the Lifetime of cyclohexanol dehydrogenation catalysts.

Based on this, Patent 201911418141.4 discloses a separation process for extractive distillation and separation of cyclohexanol and butyl cyclohexyl ether. The main problem is that the performance of alcohol solvents is unstable, and there is high temperature polymerization phenomenon, which cannot meet the long-term operation requirements of industrial devices; at the same time, the polarity of the above-mentioned solvent molecules is weak, which has little effect on the relative volatility of cyclohexanol and butylcyclohexyl ether. The separation effect of cyclohexanol and butyl cyclohexyl ether is not good and the separation energy consumption is large. The purity of the separated butyl cyclohexyl ether can only reach about 97%, and the purity of cyclohexanol can only reach 99.3%, which limits the application range of the product and occasion. In addition, the above-mentioned solvent has a relatively low boiling point, and there are problems such as difficult separation in the solvent regeneration process and high energy consumption for regeneration.

SUMMARY OF THE INVENTION

The invention provides a separation and purification method of cyclohexanol and butyl cyclohexyl ether, so as to solve the problems that the butyl cyclohexyl ether accumulates continuously during the production process of cyclohexanone, which leads to the increase of material consumption and energy consumption of the operation system and the shortened life of the dehydrogenation catalyst.

The present invention provides a kind of separation and purification method of cyclohexanol and butyl cyclohexyl ether, the method comprises:

S01: the crude cyclohexanol in the liquid phase and the extractant in the liquid phase enter the first separation section of the separation and purification tower, and then return to the first separation section and the The second separation section of the separation and purification column; wherein, the first separation section is parallel to the second separation section, and is located above the common stripping section.

The device used in the method for separating and purifying cyclohexanol and butyl cyclohexyl ether provided by the present invention can be a double rectifying tower, or a separating and purifying tower with an upper partition plate can be used. For the convenience of description, a separation and purification tower is used for specific description in the present invention. In the present invention, the top of the separation and purification column is provided with a partition plate, which is placed vertically and extends along the axis of the column body of the separation and purification column. Thereby, the upper part of the interior of the separation and purification column is isolated into the first separation section and the second separation section of the separation and purification column, and the first separation section and the second separation section are parallel. Below the first separation section and the second separation section is a common stripping section, that is, the separator divides the interior of the separation and purification column into three spaces. In the present invention, the packing height of the first separation section is equivalent to 20-50 theoretical trays, the packing height of the second separation section is equivalent to 10-30 theoretical trays, and the packing height of the common stripping section is equivalent to 20-30 theoretical trays. 40 theoretical plates. The separation and purification tower in the present invention adopts negative pressure operation, and the operating pressure is 5-25kPa.

The crude cyclohexanol in the liquid phase and the extractant in the liquid phase produced in the cyclohexanone production device enter the first separation section of the separation and purification tower, and the feed position of the extractant is higher than the feed position of the crude cyclohexanol. The crude cyclohexanol includes cyclohexanone, cyclohexanol, and butylcyclohexyl ether. The crude cyclohexanol in the liquid phase and the extractant in the liquid phase are heated into the gas phase through the common stripping section of the separation and purification tower, and then the gas phase rising from the common stripping section is returned to the first separation section and the second separation section.

In the present invention, a high-boiling compound extractant is selected as the extractant, and the compound extractant includes an ionic liquid, a heterocyclic compound solvent containing N or S. Wherein, the ionic liquid includes an alkyl imidazole ionic liquid, specifically, the alkyl imidazole ionic liquid includes 1-butyl-3-methylimidazolium chloride (chemical formula: [BMIm]Cl) or 1-butyl -3-Methylimidazolium fluoroborate (chemical formula: [BMIm]BF4); Heterocyclic compounds containing N or S Solvents include nitrogen methyl pyrrolidone or nitrogen formyl morpholine. Alkyl imidazole ionic liquids belong to strong polar solvents, which have strong intermolecular forces with cyclohexanol, but small intermolecular forces with butylcyclohexyl ether, which has a smaller molecular polarity, which can significantly increase Relative volatility between cyclohexanol and butyl cyclohexyl ether; heterocyclic compounds containing N or S can adjust the viscosity of the composite system, and have good solubility, which can ensure that the extractant and cyclohexanol are homogeneous state, so as to ensure the separation efficiency of the rectification process and avoid the problem of low rectification separation efficiency caused by the poor mutual solubility of ionic liquid and alcohol.

Further, the proportion of the ionic liquid in the present invention is 40-90 wt %, and the proportion of the heterocyclic compound solvent containing N or S is 10-60 wt %. More preferably, the proportion of the ionic liquid is 60-80 wt %, and the proportion of the heterocyclic compound solvent containing N or S is 20-40 wt %.

S02: butyl cyclohexyl ether is obtained at the top of the first separation section, part of the butyl cyclohexyl ether is extracted, and the other part is refluxed to the top of the first separation section.

After the rising gas phase in the common stripping section is returned to the first separation section, the gas phase is in countercurrent contact with crude cyclohexanol, and mass transfer and heat transfer reaction occurs, so that cyclohexanol and butylcyclohexyl ether are effectively separated. Thus, high-purity gas-phase butyl cyclohexyl ether is obtained at the top of the column of the first separation section, and the purity of the butyl cyclohexyl ether is greater than 99 wt %. The gas-phase butyl cyclohexyl ether obtained at the top of the first separation section is subjected to condenser condensation treatment, and the obtained part of the liquid phase butyl cyclohexyl ether is extracted as a product, and another part of the liquid phase butyl cyclohexyl ether is refluxed to the top of the first separation section as a reflux liquid .

In the present invention, in order to effectively separate cyclohexanol and butylcyclohexyl ether, the column top temperature of the first separation section is 100-140° C., the reflux ratio is 5-20, and the operating pressure is 5-25kPa.

S03: cyclohexanol is obtained from the top of the second separation section, a part of the cyclohexanol is extracted, and the other part is refluxed to the top of the second separation section.

After the rising gas phase in the common stripping section is returned to the second separation section, the gas phase is in countercurrent contact with crude cyclohexanol, and mass transfer and heat transfer reaction occurs, so that cyclohexanol and butyl cyclohexyl ether are effectively separated. Thus, high-purity cyclohexanol is obtained at the top of the second separation section, and the purity of cyclohexanol is greater than 99 wt%. The gas-phase cyclohexanol obtained at the top of the second separation section is subjected to condensation treatment with a condenser, and a part of the obtained liquid-phase cyclohexanol is extracted as a product, and another part of the liquid-phase cyclohexanol is refluxed to the column top of the second separation section as a reflux liquid .

In the present invention, in order to effectively separate cyclohexanol and butyl cyclohexyl ether, the top temperature of the second separation section is 100-140° C., and the reflux ratio is 3-10.

S04: A regenerated extractant is obtained at the bottom of the common stripping section, and the regenerated extractant enters the first separation section after being condensed.

Liquid-phase butyl cyclohexyl ether from the reflux of the first separation section, liquid-phase cyclohexanol from the reflux of the second separation section, crude cyclohexanol of the liquid-phase produced in the cyclohexanone production device, liquid-phase extraction agent and other liquids The phase liquid is in countercurrent contact with the rising gas-phase crude cyclohexanol and the extraction agent at the bottom of the common stripping section, and a mass transfer and heat transfer process occurs. Since the boiling points of each component of the composite extractant are higher than those of cyclohexanol and butylcyclohexyl ether, the extraction and regeneration process is simple in the process of countercurrent contact, which can be achieved with fewer theoretical plates. At the same time, the crude cyclohexanol and the extractant in the liquid phase are changed into the gas phase due to heating and then re-enter the first separation section and the second separation section. Thus, the bottom of the common stripping section obtains a regenerated extractant, and the purity of the regenerated extractant is greater than 99.9 wt%. The regenerated extractant is condensed and then enters the first separation section for recycling.

In the present invention, in order to effectively separate cyclohexanol and butyl cyclohexyl ether, the bottom temperature of the common stripping section is 200-280°C.

The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

The invention provides a method for separating and purifying cyclohexanol and butyl cyclohexyl ether. The purity of butyl cyclohexyl ether and cyclohexanol obtained by the method can reach 99.5 wt % and 99.9 wt % respectively, and the product purity is much better than that of the patent CN113117361A. Achievable product purity. The extractant in the method provided by the invention is a high-boiling compound extractant, and the alkyl imidazole ionic liquid belongs to a strong polar solvent, and has a strong intermolecular force with the cyclohexanol molecule, and is more polar than the molecule. Small butyl cyclohexyl ether has less intermolecular force, which can significantly increase the relative volatility between cyclohexanol and butyl cyclohexyl ether; heterocyclic compounds containing N or S can play a role in adjusting the viscosity of the composite system, and have good It can ensure that the extractant and cyclohexanol are in a homogeneous state, thereby ensuring the separation efficiency of the rectification process, avoiding the low rectification separation efficiency caused by the poor mutual solubility of ionic liquid and alcohol, and can solve the problem of cyclohexanol. In the production process of hexanone, the by-product butyl cyclohexyl ether in the cyclohexanol recycle material keeps accumulating, which leads to problems such as increased energy consumption of system operation material and shortened life of dehydrogenation catalyst.

Combining the molecular properties and solubility properties of cyclohexanol, the invention overcomes the deficiency of a single solvent through compounding between different solvents, the separation effect is greatly improved, the efficient separation of cyclohexanol and butyl cyclohexyl ether can be realized, and high-purity cyclohexyl ether is obtained. The products of cyclohexanol and butylcyclohexyl ether, and the extractant of the invention have the advantages of wide source, cheap and easy to obtain, stable performance, can run stably for a long period, and meet the requirements of industrial application.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the accompanying drawings that need to be used in the embodiments will be briefly introduced below. Other drawings can also be obtained from these drawings.

Fig. 1 is the process flow diagram of the separation and purification of cyclohexanol and butylcyclohexyl ether provided in the embodiment of the present invention.

Detailed ways

The separation and purification method of cyclohexanol and butyl cyclohexyl ether provided by the present invention comprises:

S01: the crude cyclohexanol of the liquid phase produced in the cyclohexanone production device enters the first separation section of the separation and purification tower with the feed flow rate of 1000kg/h and the extraction agent of the liquid phase, and the feed position of the extraction agent is higher than Feed position for crude cyclohexanol. The composition of the crude cyclohexanol includes 0.3 wt % of cyclohexanone, 90.1 wt % of cyclohexanol and 9.6 wt % of butylcyclohexyl ether. The crude cyclohexanol in the liquid phase and the extractant in the liquid phase are heated into the gas phase through the common stripping section of the separation and purification tower, and then the gas phase rising from the common stripping section is returned to the first separation section and the second separation section.

S02: After the rising gas phase in the common stripping section is returned to the first separation section, the gas phase is in countercurrent contact with crude cyclohexanol, and mass transfer and heat transfer reaction occurs, so that cyclohexanol and butyl cyclohexyl ether are effectively separated. Thus, high-purity gas-phase butyl cyclohexyl ether is obtained at the top of the column of the first separation section, and the purity of the butyl cyclohexyl ether is greater than 99.5 wt %. The gas-phase butyl cyclohexyl ether obtained at the top of the first separation section is subjected to condenser condensation treatment, and the obtained part of the liquid phase butyl cyclohexyl ether is extracted as a product, and another part of the liquid phase butyl cyclohexyl ether is refluxed to the top of the first separation section as a reflux liquid .

S03: After the rising gas phase in the common stripping section is returned to the second separation section, the gas phase is in countercurrent contact with crude cyclohexanol, and mass transfer and heat transfer reaction occurs, so that cyclohexanol and butyl cyclohexyl ether are effectively separated. Thus, high-purity cyclohexanol is obtained at the top of the second separation section, and the purity of cyclohexanol is greater than 99.9 wt%. The gas-phase cyclohexanol obtained at the top of the second separation section is subjected to condensation treatment with a condenser, and a part of the obtained liquid-phase cyclohexanol is extracted as a product, and another part of the liquid-phase cyclohexanol is refluxed to the column top of the second separation section as a reflux liquid .

S04: liquid-phase butyl cyclohexyl ether from the reflux of the first separation section, liquid-phase cyclohexanol from the reflux of the second separation section, crude cyclohexanol of the liquid-phase produced from the cyclohexanone production device, and extraction agent of the liquid-phase The liquid-phase liquid is in countercurrent contact with the rising gas-phase crude cyclohexanol and the extraction agent at the bottom of the common stripping section, and a mass transfer and heat transfer process occurs. Since the boiling points of each component of the composite extractant are higher than those of cyclohexanol and butylcyclohexyl ether, the extraction and regeneration process is simple in the process of countercurrent contact, which can be achieved with fewer theoretical plates. At the same time, the crude cyclohexanol and the extractant in the liquid phase are changed into the gas phase due to heating and then re-enter the first separation section and the second separation section.

For the convenience of comparing the purity of cyclohexanol, the purity of butyl cyclohexyl ether and the purity of the regeneration extractant after the separation under different process conditions, the following is specified in the form of a table, wherein, the feed flow of crude cyclohexanol is 1000kg/h, The composition of crude cyclohexanol was 90.1 wt % of cyclohexanol, 0.3 wt % of cyclohexanone, and 9.6 wt % of butylcyclohexyl ether. Please refer to Table 1 for specific values.

In addition, in order to realize that the separation and purification method of cyclohexanol and butylcyclohexyl ether provided by the present invention has outstanding effect compared with the existing method, the present invention is also formed by combining octanol, 1,3 butanediol and triglyme Take the extractant as an example to compare and form a comparative example, wherein the mass ratio of octanol, 1,3 butanediol and triglyme is 1:2:1. When this comparative example carries out the technological method of separating cyclohexanol and butyl cyclohexyl ether, except the selection of extraction agent is different, the rest of the technological conditions are the same as in Example 4, and the purity of the obtained butyl cyclohexyl ether and cyclohexanol are as follows: Refer to Table 1.

Table 1: Purity of cyclohexanol, butyl cyclohexyl ether and regenerative extractant after separation under different process conditions

It can be seen from Table 1 that under the same conditions of feed flow, when the extractant is only a single component, the purity of butylcyclohexyl ether is only 85.8wt%, the purity of cyclohexanol is 97.99wt%, and the purity of the regeneration extractant is only 85.8wt%. When the extractant is a composite extractant, the purity of butyl cyclohexyl ether can reach 99.6wt%, the purity of cyclohexanol is 99.91wt%, and the purity of the regeneration extractant is 99.93wt%. From this, it can be shown that the composite extractant can significantly improve the separation ability of butylcyclohexyl ether and cyclohexanol.

Under the condition of the same type of extractant feed, the purity of butyl cyclohexyl ether and the purity of cyclohexanol were gradually improved with the increase of feed flow rate. In addition, for the composite extractant, under the conditions of the same extractant feed type and feed flow rate, the purity of butyl cyclohexyl ether and cyclohexanol is the highest when the proportion of [BMIm]Cl + nitrogen methyl pyrrolidone is 7:3. .

It can be seen from Example 4 and Comparative Examples that, under the same process conditions, when using the existing extractant to select octanol, 1,3 butanediol and triglyme to combine, the cyclohexanol product purity obtained by separation Only 97.3%, the purity of butyl cyclohexyl ether is only 96.6%, and when using the extractant of the present invention for selecting [BMIm]Cl+ nitrogen methyl pyrrolidone, the cyclohexanol product purity obtained by separation is 99.91%, and the purity of butyl cyclohexyl ether is 99.6% %, significantly higher than the combined form of the extractant composed of octanol and the like.

Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. The present invention is intended to cover any variations, uses or adaptations of the present invention which follow the general principles of the present invention and include common knowledge or conventional techniques in the technical field not disclosed by the present invention . The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

It should be understood that relational terms such as "first" and "second" etc. are used only to distinguish one entity or operation from another entity or operation and do not necessarily require or imply that such entities or operations are the same. any such actual relationship or sequence exists. The present invention is not limited to the precise structures described above and illustrated in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims (10)

1. A method for separating and purifying cyclohexanol and butyl cyclohexyl ether is characterized by comprising the following steps:

feeding the liquid-phase crude cyclohexanol and the liquid-phase extracting agent into a first separation section of a separation and purification tower, heating the liquid-phase crude cyclohexanol and the liquid-phase extracting agent into a gas phase through a common stripping section of the separation and purification tower, and returning the gas phase to the first separation section and a second separation section of the separation and purification tower; wherein the first separation section is parallel to the second separation section and above the common stripping section;

butyl cyclohexyl ether is obtained at the top of the first separation section, part of the butyl cyclohexyl ether is extracted, and the other part of the butyl cyclohexyl ether refluxes to the top of the first separation section;

cyclohexanol is obtained at the top of the second separation section, part of the cyclohexanol is extracted, and the other part of the cyclohexanol reflows to the top of the second separation section;

and the regenerated extracting agent is obtained at the bottom of the common stripping section and enters the first separation section after being condensed.

2. The method for separating and purifying cyclohexanol and butylcyclohexyl ether as claimed in claim 1, wherein the extractant comprises ionic liquid, N-or S-containing heterocyclic compound solvent.

3. The method for separating and purifying cyclohexanol and butylcyclohexyl ether according to claim 2, wherein the ratio of the ionic liquid is 40 to 90 wt%, and the ratio of the N-or S-containing heterocyclic compound solvent is 10 to 60 wt%.

4. The method for separating and purifying cyclohexanol and butylcyclohexyl ether according to claim 2, wherein the ionic liquid comprises an alkyl imidazole ionic liquid.

5. The method for separating and purifying cyclohexanol and butylcyclohexyl ether according to claim 4, wherein the alkyl imidazole ionic liquid comprises 1-butyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium fluoroborate.

6. The method for separating and purifying cyclohexanol and butylcyclohexyl ether according to claim 2, wherein the N-or S-containing heterocyclic compound solvent includes nitrogen methyl pyrrolidone, nitrogen methyl morpholine.

7. The separation and purification method of cyclohexanol and butylcyclohexyl ether according to claim 1, wherein the packing height of the first separation section is 20 to 50 theoretical plates, the packing height of the second separation section is 10 to 30 theoretical plates, and the packing height of the common stripping section is 20 to 40 theoretical plates.

8. The method for separating and purifying cyclohexanol and butylcyclohexyl ether as claimed in claim 1, wherein the overhead temperature of the first separation section is 100-140 ℃ and the reflux ratio is 5-20.

9. The method for separating and purifying cyclohexanol and butylcyclohexyl ether as claimed in claim 1, wherein the overhead temperature of the second separation section is 100-140 ℃ and the reflux ratio is 3-10.

10. The method for separating and purifying cyclohexanol and butylcyclohexyl ether as claimed in claim 1, wherein the bottom temperature of the common stripping section is 200-280 ℃.

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