TW201321345A - Method of separating cyclohexene oxide and n-pentanol - Google Patents

Abstract

A method of separating cyclohexene oxide and n-pentanol comprises adding a specific solvent to a mixture solution containing the cyclohexene oxide and the n-pentanol so as to change the relative volatility of the cyclohexene oxide and the n-pentanol, followed by distilling the mixture solution to separate the cyclohexene oxide and the n-pentanol. The separation method of this invention is simple and can recycle the cyclohexene oxide and the n-pentanol at the same time, and the recycled cyclohexene oxide has a high purity.

Description

Method for separating epoxy cyclohexane and n-pentanol

The present invention relates to a method for separating epoxycyclohexane and n-pentanol, in particular, relating to a method for separating epoxy cyclohexane by changing the relative volatility of epoxycyclohexane and n-pentanol. The method of n-pentanol.

Cyclohexanone, an important raw material for the manufacture of caprolactam (CPL), is also an important source of synthetic chemical products such as nylon 6, and therefore plays an important role in the modern organic chemical industry. A common industrial process is to use cyclohexane as a raw material, and to carry out a series of reactions such as oxidation, neutralization, decomposition, etc., and then purify to obtain cyclohexanone. However, in the process of oxidizing cyclohexane to produce cyclohexanone, there are many kinds of by-products, and the low-boiling substance distilled at the top of the column is called a light oil. Light oil has more than ten kinds of ingredients, complex composition and difficult to separate. This incidental economic effect is very low, so it used to be burned as a fuel. However, light oils contain high-priced raw materials such as epoxycyclohexane and n-pentanol, which have economic recovery value. However, under normal pressure, epoxycyclohexane is close to the boiling point of n-pentanol and cannot be separated by general distillation or rectification.

At present, Japanese Patent No. 50095248 discloses a method for purifying epoxy cyclohexane by first distilling off a light component of a solution under reduced pressure, and then reacting an aldehyde and a ketone into a high-boiling substance by an alkaline reagent, and finally A cyclohexane having a purity of 94.7 wt% was obtained by distillation. Chinese Patent No. 101225077A discloses a ring opening reaction process for recovering epoxy cyclohexane from light oil by subjecting a light oil containing an epoxycyclohexane component to a ring opening reaction with hydrogen chloride to form a ring Oxycyclohexane is converted into high-boiling 2-chlorocyclohexanol, and a high boiling point of 2 chlorocyclohexanol is obtained by rectification, and then 2-chlorocyclohexanol is subjected to ring closure reaction with a base. Rectification gives epoxycyclohexane. Chinese Patent No. 1331077 discloses a method for separating and recovering epoxycyclohexane from a by-product of oxidation of cyclohexane, which is a reaction of a light oil solution containing epoxycyclohexane directly with a halogenated hydrogen. A high-boiling 2-halocyclohexanol is produced, and the 2-halogenated cyclohexanol collected and separated is subjected to a cyclization reaction with an alkaline solution, followed by distillation to obtain epoxycyclohexane. Chinese Patent No. 1106784 discloses a method for recovering epoxycyclohexane by using azeotropic distillation to remove alcohols and other impurities to recover epoxycyclohexane. Chinese Patent No. 1 295 068 A discloses a method for the de-alcoholization of epoxy cyclohexane by reacting epoxycyclohexane with an alcohol impurity under basic conditions to form a high-boiling cyclohexanediol ether, after which The mixture is subjected to filtration neutralization, and an epoxycyclohexane having a low content of an alcohol impurity can be obtained by distillation. Chinese Patent No. 1454893 discloses a method for purifying epoxy cyclohexane by using a hydroxylamine salt or a saturated aqueous solution of sodium hydrogen sulfite or an aqueous solution of hydrogen peroxide to remove aldehydes and ketones, and finally adding benzene or a benzene homologous substance. The alcohol impurities were removed by boiling, and finally 98% by weight of epoxycyclohexane was obtained.

However, most of the above separation or purification methods use a reaction to remove other impurities such as alcohols, aldehydes, ketones, etc., and the recovery method can only recover epoxycyclohexane, and cannot simultaneously recover n-pentanol, and the reaction method is used. Recovery of epoxy cyclohexane, the overall process is more complicated. Further, by reacting epoxycyclohexane with an alcohol to improve the purity of the recovery, it is possible not only to recover the alcohol but also to reduce the recovery of the epoxycyclohexane.

Therefore, how to effectively recover the epoxycyclohexane and the alcohol in a simple separation method, and the recovered epoxycyclohexane has high purity and high recovery rate, which is currently a problem to be solved.

For the purpose of achieving the above and other objects, the present invention provides a method for separating epoxycyclohexane and n-pentanol, comprising the steps of: adjusting epoxycyclohexane in a mixture containing epoxycyclohexane and n-pentanol; The relative volatility of n-pentanol; and the distillation of the adjusted relative volatility to separate epoxycyclohexane and n-pentanol.

Since epoxycyclohexane and n-pentanol have boiling points close to each other under normal pressure, it is generally difficult to separate epoxycyclohexane from n-pentanol by distillation. For the purpose of the present invention, the present invention adjusts the relative volatility by adding at least one compound selected from the group consisting of a guanamine compound, a hydroxyl group-containing compound, an anthraquinone compound, and anisole, thereby separating Epoxy cyclohexane and n-pentanol.

The separation method of the invention is simple, and the epoxycyclohexane and n-pentanol can be recovered simultaneously, and the recovered epoxycyclohexane has high purity and high recovery rate, and can be recycled.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention from the disclosure. The present invention may be embodied or applied by other different embodiments, and the various details of the present invention may be variously modified and changed without departing from the spirit and scope of the invention.

The process of preparing cyclohexanone by cyclohexane oxidation produces by-product light oil. Most of the conventional techniques use the reaction to remove aldehydes and ketone impurities, and then distillate to obtain epoxycyclohexane and n-pentanol. Share.

The present invention provides a separation method capable of simultaneously recovering epoxycyclohexane and n-pentanol. The separation method of the present invention can be used for the process of oxidizing cyclohexane to prepare cyclohexanone, and in the light oil produced, that is, the aldehyde and ketone impurities are removed by using a conventional technique, and the obtained epoxy hexane is obtained. In the mixture of pentanol, at least one compound selected from the group consisting of a guanamine compound, a hydroxyl group-containing compound, an anthracene compound, and anisole is added to adjust the epoxy when the mixture reaches a gas-liquid equilibrium state. The relative volatility of cyclohexane and n-pentanol, in addition, the molar ratio of epoxycyclohexane to n-pentanol in the mixture is usually from 4 to 11.5 before adjusting the relative volatility. Next, the mixed liquid of the adjusted relative volatility is distilled to separate epoxycyclohexane and n-pentanol.

In the present invention, the compound to be added may be at least one compound of a group consisting of a guanamine compound, a hydroxyl group-containing compound, an anthraquinone compound, and anisole, as long as the compound is not adversely affected by the reaction. Usually, the compound used is in a liquid state to facilitate adjustment of relative volatility. For example, the compound includes a guanamine solvent, an anthraquinone solvent or an alcohol solvent, and one, two or more of the above may be used in an appropriate ratio. a mixture of such compounds. Further, the added compound may not be azeotroped with epoxycyclohexane and/or n-pentanol, and the compound may generally be selected to have a boiling point not exceeding the boiling point of the epoxycyclohexane or higher than the boiling point of n-pentanol.

In the present invention, the guanamine compound includes N,N-dimethylformamide, dimethyl acetamide, 1-methyl-2-pyrrolidone ( 1-methyl-2-pyrrolidone) and 2-pyrrolidone. The quinone compounds include dimethyl hydrazine, diethyl hydrazine and dipropylene hydrazine. The hydroxyl-containing compound includes cyclohexanol, ethylene glycol, propylene glycol, anisole, 1,4-butanediol, and glycol. (glycerol).

Usually, the compound is added such that the relative volatility of the epoxycyclohexane to n-pentanol is about 1.3 to 3.2, and the temperature of the epoxycyclohexane and n-pentanol in the gas-liquid equilibrium state is between 130 and 180. °C.

When the distillation is carried out, the distillation pressure is 1 atm, and the distillation temperature is generally carried out at a temperature of about 125 to 130 °C. More specifically, when the distillation column is distilled, the distillation column has a reflux ratio of 2 to 6, and the feed temperature is about 125 ° C, and the outlet temperature is about 129 to 130 ° C.

Moreover, the operations applicable to the method of the present invention can be performed on a batch operating system or can be performed in a continuous operating system.

The separation method of the present invention is simple, and epoxycyclohexane and n-pentanol can be simultaneously separated, and epoxycyclohexane having a purity of 98% by weight or more can be obtained with high recovery.

The features and effects of the present invention are further illustrated by the following specific examples, but are not intended to limit the scope of the invention.

The embodiment of the present invention is shown below, but the present invention is not limited to these embodiments. The invention analyzes the composition of the gas phase and the liquid phase of the solution during gas-liquid equilibrium by using a gas chromatograph, and calculates the relative volatility of the epoxycyclohexane and n-pentanol by the following equation:

Relative volatility: α ₁₂ = (y1/x1) / (y2/x2);

After gas-liquid equilibrium, x1 represents the epoxy cyclohexane molar fraction in the liquid phase, x2 represents the n-pentanol molar fraction in the liquid phase, y1 represents the epoxy cyclohexane molar fraction in the gas phase, and y2 Indicates the n-pentanol molar fraction of the gas phase.

Example 1

A mixture of epoxycyclohexane and n-pentanol (92/8 mol/mol) was taken, and N,N-dimethylformamide was added to the mixture. The gas-liquid equilibrium tester (Fischer, model: Labodest VLE 602) is used to control the heating temperature and the reflux rate to be stable under normal pressure, and the composition of the gas phase and the liquid phase of the solution is analyzed during gas-liquid equilibrium to obtain the temperature at the time of gas-liquid equilibrium. It was 139.1 ° C and the relative volatility of epoxycyclohexane and n-pentanol was calculated to be 3.01.

Examples 2 to 11

The operation mode of Example 1 was repeated, and different compounds were respectively added according to the following Table 1. When the heating temperature and the reflux rate control were stabilized, the gas phase and the liquid phase composition of the solution were analyzed by gas chromatography. And the results are shown in Table 1.

Example 12

A mixture of epoxycyclohexane and n-pentanol was separated in an experimental distillation apparatus having a diameter of 3 cm and a length of 90 cm and filled with a 3 x 3 mm stainless steel θ mesh ring. The operating conditions of the separation method are as follows: the distillation pressure is 1 atm, and the compound used to adjust the relative volatility is 1-methyl-2-pyrrolidone (NMP), the feed flow rate is 2.0 ml/min, and the feed temperature is At 125 ° C, the reflux ratio of the distillation column was 4, and the distillation outlet temperature was 129 to 130 °C. When the reaction system reached equilibrium, the upper layer discharge component was analyzed by a gas chromatograph. As a result, the purity of the epoxycyclohexane was 98% by weight or more, and the bottom solution was n-pentanol and 1-methyl-2. a mixed solution of pyrrolidone. In addition, from the gas-liquid equilibrium (VLE) data plot of n-pentanol and 1-methyl-2-pyrrolidone (NMP), it is confirmed that the relative volatility of n-pentanol and 1-methyl-2-pyrrolidone is greater than 1.3, can also effectively separate n-pentanol and NMP.

Comparative example 1

The mixture of epoxycyclohexane and n-pentanol was taken under normal pressure according to the procedure described in Example 1, and the heating temperature and the reflux rate were controlled by a gas-liquid equilibrium analyzer (Fischer, model: Labodest VLE 602). The composition of the gas phase and the liquid phase of the solution was analyzed during gas-liquid equilibrium, and the temperature at the gas-liquid equilibrium was 129.9 ° C. It was found that it was difficult to separate the epoxycyclohexane from n-pentanol, and the epoxycyclohexane was calculated. The relative volatility of pentanol was 1.07.

From the above results, it is shown that the separation method of the present invention can facilitate the separation of the epoxycyclohexane and n-pentanol by adding a specific compound to change the relative volatility of the epoxycyclohexane and n-pentanol. Therefore, the separation method of the invention is simple, and the epoxycyclohexane and n-pentanol can be recovered simultaneously, and the recovered epoxy cyclohexane has a purity of more than 98% by weight, and has high epoxycyclohexane recovery rate. The advantages.

The above-described embodiments are merely illustrative of the principles of the invention and its effects, and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be as set forth in the scope of the claims described below.

Claims (11)

A method for separating epoxycyclohexane and n-pentanol, comprising the steps of: adjusting a relative volatility of epoxycyclohexane and n-pentanol in a mixture containing epoxycyclohexane and n-pentanol; and distilling The mixture of relative volatility was adjusted to separate epoxycyclohexane and n-pentanol. The method for separating epoxycyclohexane and n-pentanol according to claim 1 is to adjust the relative volatility of epoxycyclohexane and n-pentanol when the mixture reaches a gas-liquid equilibrium state. The method for separating epoxycyclohexane and n-pentanol according to claim 1, wherein at least a group selected from the group consisting of a guanamine compound, a hydroxyl group-containing compound, an anthraquinone compound, and anisole is added. A compound to adjust the relative volatility. The method for separating epoxycyclohexane and n-pentanol according to claim 3, wherein the guanamine compound comprises N,N-dimethylformamide, dimethylacetamide, 1 -methyl-2-pyrrolidone and 2-pyrrolidone. The method for separating epoxycyclohexane and n-pentanol according to claim 3, wherein the fluorene compound comprises dimethyl hydrazine, diethyl hydrazine and dipropylene arsenide. The method for separating epoxycyclohexane and n-pentanol according to claim 3, wherein the hydroxyl group-containing compound comprises cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, and glycol . The method for separating epoxycyclohexane and n-pentanol according to the third aspect of the invention, wherein the relative volatility of the epoxycyclohexane and n-pentanol is greater than or equal to 1.3. The method for separating epoxycyclohexane and n-pentanol according to claim 1, wherein the molar ratio of epoxycyclohexane to n-pentanol in the mixture is adjusted before the relative volatility is adjusted. 4 to 11.5. The method for separating epoxycyclohexane and n-pentanol according to claim 1, wherein the mixed liquid is a light oil produced by cyclohexanone. The method for separating epoxycyclohexane and n-pentanol according to claim 1, wherein the method is carried out by a batch operating system. A method of separating epoxycyclohexane and n-pentanol as described in claim 1, wherein the method is carried out in a continuous operating system.