KR20040078804A - Separation Method of Normal Pentanol and Cyclopentanol Mixtures Through Distllation - Google Patents

Abstract

PURPOSE: A method for separating n-pentanol and cyclopentanol by extraction distillation is provided, to easily separate n-pentanol and cyclopentanol which have similar boiling point from their mixture. CONSTITUTION: The method comprises the steps of supplying a mixture of n-pentanol and cyclopentanol in a distillation tower and supplying ethylene glycol as an extracting agent in the upper part of a distillation tower, to collect n-pentanol from the top of the tower and cyclopentanol and ethylene glycol from the bottom of the tower. Preferably the cyclopentanol and ethylene glycol from the bottom of the tower is separated by distillation and the isolated ethylene glycol is recirculated. Preferably at least one among the number of distillation plates, the reflux ratio or the amount of ethylene glycol is increased to increase the purity of a final product.

Description

Separation Method of Normal Pentanol and Cyclopentanol Mixtures Through Distllation

In a general distillation process, raw materials are supplied to the tower, and some of the effluent discharged to the tower is vaporized to be returned to the tower, and the rest is recovered to the bottom of the column. It is refluxed and the remainder recovered to the top product.

However, as in the present invention, normal pentanol and cyclopentanol have a difference in boiling point at normal pressure of 2 ° C. (normal pentanol boiling point: 138 ° C., cyclopentanol boiling point: 140.2 ° C.), and a relative volatility of 1, which is close to 1. Normal pentanol and cyclopentanol could not be separated from normal pentanol and cyclopentanol mixtures, respectively.

Accordingly, an object of the present invention is to provide a method for effectively separating normal pentanol and cyclopentanol from a mixture of normal pentanol and cyclopentanol which is difficult to separate by a general distillation method as described above.

1 is a schematic diagram of an extractive distillation apparatus for separating a pentanol mixture of the present invention.

FIG. 2 is an xy diagram showing that the relative volatility of normal pentanol is increased when ethylene glycol, an extractant designed in the present invention, is mixed in a weight ratio of 1 to 1 in a mixture of normal pentanol and cyclopentanol (solid line is relative Calculated when the volatility is 1.4).

FIG. 3 is an xy diagram showing that the relative volatility of normal pentanol is increased when ethylene glycol, an extractant designed in the present invention, is mixed in a weight ratio of normalpentanol and cyclopentanol in a ratio of 2 to 1 (solid line is relative Calculated value with volatility of 1.8).

<Explanation of symbols for the main parts of the drawings>

1: distillation column, 2: reboiler

3: condenser, 4: ethylene glycol supply

5: Supply raw materials (mixture of normal pentanol and cyclopentanol)

6: separated normal pentanol product

7: Isolated Cyclopentanol and Ethylene Glycol Mixture

The present invention relates to a method for separating normal pentanol and cyclopentanol from a similar boiling point mixture of normal pentanol and cyclopentanol, and particularly, ethylene glycol having an extractant function at the top of a distillation column, When added at the same weight as the cyclopentanol mixture, the relative volatility becomes about 1.4, and when the ethylene glycol and the pentanol mixture are mixed in a weight ratio of 2 to 1, the relative volatility increases to about 1.8 at normal pressure to normal pentane. The present invention relates to a method for separating normal pentanol and cyclopentanol by extractive distillation, which is characterized by easily separating ol and cyclopentanol.

The configuration and operation thereof will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of an extractive distillation apparatus for separating a pentanol mixture of the present invention.

In Figure 1, a raw material "normal pentanol and cyclopentanol mixture" (hereinafter referred to as pentanol mixture) is supplied to the extraction distillation column (1). The raw material descends by increasing force to the bottom of the tower. Ethylene glycol (4), which is an extractant, is fed to the top of the tower. Ethylene glycol has a higher boiling point than normal pentanol and cyclopentanol, so that the ethylene glycol is present in the liquid phase and descends to the bottom of the tower together with cyclopentanol. Heat is supplied to the reboiler 2 to vaporize a portion of the liquid effluent of the tower to reflux to the tower and recover the remainder to the bottom product 7. Steam exiting the top of the tower is condensed in the condenser 3 to return some to the tower and recover the remainder to the top product 6. At this time, the normal pentanol is concentrated in the column top and the cyclopentanol is concentrated in the column bottom by the action of the extractant present in the column. The bottom product (7) can be recovered through secondary distillation to recover cyclopentanol and ethylene glycol as an extractant can be circulated to the extraction distillation column.

2 shows the molar fraction of liquid normal pentanol (x-axis) except ethylene glycol and gaseous normal pentanol water when the pentanol mixture and ethylene glycol were mixed in a one-to-one weight ratio at normal pressure. The fraction (y-axis) is shown. The solid line in FIG. 2 shows that the relative volatility of normal pentanol was calculated as 1.4.

Shown in FIG. 3 is similar to that shown in FIG. 2, when the weight ratio of pentanol mixture and ethylene glycol is mixed in a one-to-two ratio. In FIG. 3, the solid line shows that the relative volatilities of normal pentanol were calculated to be 1.8. If ethylene glycol is not present, the relative volatility of normal pentanol is known to be about 1.1. As shown in FIG. 2 and FIG. 3, when ethylene glycol is mixed, the relative volatility of normal pentanol is greatly increased. I can see that.

In order to produce high-purity normalpentanol and cyclopentane from the pentanol mixture 5 of the present invention as in the conventional extraction distillation process, the number of effective distillation stages in the distillation column is increased, or the reflux ratio of the column top is increased, Alternatively, a method of increasing the purity of the product by increasing the flow rate compared to the raw material of the ethylene glycol supplied to the upper end of the tower may be presented, but belongs to the same technology category.

<Example 1>

Extraction distillation tower used in the practice of the present invention as shown in Figure 1 is the inner diameter of the center: 6cm, the height of 70cm from the bottom of the tower to the raw material supply position, the height of 70cm between the raw material supply position and the extractant supply position, supplying the extractant A height of 30 cm from the top of the tower to the top of the tower was used, and a 6 mm Pall ring was used. The pentaneol mixture (5, normal pentanol 75 wt%, cyclopentanol 25 wt%) was supplied at 100 cm 3 / min and ethylene glycol (4) was supplied at 100 cm 3 / min. Steam was supplied to the reboiler (2, heat transfer area: 0.3 m 2), and cooling water was supplied to the condenser (3, heat transfer area: 0.3 m 2).

As a result of operating the extraction distillation column with the reflux ratio of the column top as 4.0, 94.1 wt% of normal pentanol (6) was recovered as the column top, and a mixture of ethylene glycol and cyclopentanol (7) was recovered at the bottom.

The purity of cyclopentanol excluding ethylene glycol in the bottom product was 91.2 wt%.

When the reflux ratio of the column top was 5.0 and the remaining operation method was the same as the above, the concentration of normal pentanol was 95.3 wt% and the concentration of cyclopentanol except ethylene glycol was 92.4 wt%.

<Example 2>

In the same apparatus as in Example 1, raw materials (5, 75 wt% normal pentanol and 25 wt% cyclopentanol) were supplied at 80 cm 3 / min, and the feed flow rate of ethylene glycol as an extractant was 120 cm 3 / min, and the reflux ratio of the top was When operating at 4.0, the concentration of normal pentanol recovered to the top was 96.3 wt% and the concentration of cyclopentanol except ethylene glycol was 92.5 wt% in the bottom product.

When the extractive distillation process using ethylene glycol is applied in order to separate normal pentanol and cyclopentanol mixtures, which are similar boiling point mixtures, the pentanol mixture can be easily separated. The relative volatilization under normal pressure of normal pentanol and cyclopentanol mixture without ethylene glycol is about 1.1, whereas when ethylene glycol is added at the same weight as the mixture of normal pentanol and cyclopentanol, When the pentanol mixture and ethylene glycol are mixed in a weight ratio of 1 to 2, the relative volatilities increase to about 1.8 at normal pressure, so that normal pentanol and cyclopentanol can be easily separated.

Claims (3)

Supplying a mixture of normal pentanol and cyclopentanol to the distillation column, and supplying ethylene glycol as an extractant to the upper end of the distillation column, recovering normal pentanol to the top and recovering cyclopentanol and ethylene glycol at the bottom Method for separating normal pentanol and cyclopentanol by extractive distillation characterized in that. The method of claim 1, wherein the mixture of cyclopentanol and ethylene glycol discharged to the bottom of the extraction distillation process is separated by distillation to recover cyclopentanol, and ethylene glycol is recycled. Method for separating normal pentanol and cyclopentanol. The method for separating normal pentanol and cyclopentanol by extractive distillation according to claim 1, wherein the purity of the product is increased by increasing at least one of the distillation stage or the reflux ratio or the amount of ethylene glycol supplied.