JPH0616653A - Method for decoloring epichlorohydrin - Google Patents

Abstract

PURPOSE:To decolor colored epichlorohydrin industrially produced. CONSTITUTION:A product of epichlorohydrin industrially produced or epichlorohydrin in a production process is decolored by adding hydrogen peroxide thereto. Absorbance in 420nm wavelength of the colored epichlorohydrin is measured using 1cm cell and decoloring is carried out by adding an aqueous solution of hydrogen peroxide according to the following formula: A2=A1-0.32XV [A1 is absorbance before addition; A2 is absorbance after addition; V is addition amount (vol%) expressed in terms of 100% hydrogen peroxide]. consequently, in the case of an ordinary product of epichlorophdrin, hydrogen peroxide is added so that the A2 becomes <=0.02. Furthermore, the hydrogen peroxide is generally added as an aqueous solution, usually about 30% aqueous solution.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the decolorization of colored epichlorohydrin. More specifically, for the industrially manufactured epichlorohydrin product,
Alternatively, it is a method of decolorizing epichlorohydrin by adding hydrogen peroxide to epichlorohydrin in the manufacturing process.

[0002]

2. Description of the Related Art Epichlorohydrin is generally produced by dehydrochlorinating dichloropropyl alcohol with calcium hydroxide. Specifically, an aqueous solution of 3 to 6% dichloropropyl alcohol and lime milk are put into a reactor, and epichlorohydrin containing saturated water is taken out in a so-called saponification reactor in which epichlorohydrin is stripped by steam. Next, in such an epichlorohydrin purification step, impurities having a lower boiling point than water and epichlorohydrin are first removed in a low boiling distillation column, and epilorohydrin is taken out in a subsequent product distillation column. For impurities having a boiling point higher than that of epichlorohydri obtained from the product distillation column, epichlorohydrone in the high-boiling substance is recovered in the next distillation column.

At this time, chlorinated hydrocarbons such as propane trichloride contained as impurities cause reactions such as dehydrochlorination by the reboiler of the distillation column, and water entrained in epichlorohydrin becomes impurities. It may react to cause coloration of the process liquid. As a result, even the epichlorohydrin of the product is colored, the chromaticity of the product standard exceeds the specifications, and the product cannot be taken out.

Conventionally, as a method for decolorizing colored epichlorohydrin, an adsorption method using, for example, activated carbon or activated alumina, or a distillation method in which precision distillation is performed again is known.

However, these methods not only require new equipment, but the adsorption method has a problem of environmental pollution in regenerating or discarding the adsorbent containing an organic substance, and the distillation method requires a large amount of energy. Therefore, neither is practical.

[0006]

[Means for Solving the Problems] Therefore, as a result of diligent studies to solve these problems, the present inventors have found that hydrogen peroxide can be easily decolorized by adding hydrogen peroxide to colored epichlorohydrin. I found that. That is, the present invention is a method for decolorizing epichlorohydrin, which comprises treating industrially produced epichlorohydrin by contacting it with hydrogen peroxide.

Further, in the present invention, it was found that the amount of hydrogen peroxide added and the degree of decolorization are in a proportional relationship.

That is, 4 of colored epichlorohydrin
The absorbance at 20 nm is measured with a 1 cm cell, and an aqueous solution of hydrogen peroxide is added according to the following formula to decolorize.

A ₂ = A ₁ -0.32 × V A ₁ : Absorbance before addition A ₂ : Absorbance after addition V: Addition amount (vol%) in terms of 100% hydrogen peroxide Therefore, in the case of ordinary product epiclohydrin For A
Hydrogen peroxide may be added so that ₂ becomes 0.02 or less. Hydrogen peroxide is generally added as an aqueous solution, and about 30% is usually used.

The addition of hydrogen peroxide in the present invention is not limited to the industrially manufactured epichlorohydrin product, but also to a portion of epichlorohydrin having a large coloration in the manufacturing process, that is, The reflux liquid of the low boiling distillation column may be used.

The features of the present invention are as follows.

1) It is not necessary to newly install a large-scale device such as a tower or a tank.

2) Even if a slight amount of excess hydrogen peroxide remains, it only changes to water and does not become an impurity that adversely affects the other.

3) The operation is very simple.

Hereinafter, the present invention will be specifically described with reference to examples.

[0016]

【Example】

Example 1 To 100 ml of epichlorohydrin having an absorbance of 0.18 at 420 nm in a 1 cm cell, 2 ml of a 30% hydrogen peroxide aqueous solution was added. 4 of epichlorohydrin after addition
The absorbance at 20 nm was 0.01 and the solution was no longer colored.

Example 2 0.3 ml of a 30% aqueous hydrogen peroxide solution was added to 100 ml of epichlorohydrin having an absorbance of 0.05 at 420 nm in a 1 cm cell. After the addition, the absorbance of epichlorohydrin at 420 nm was 0.02, and the solution was no longer colored.

Example 3 0.1 ml of a 30% aqueous hydrogen peroxide solution was added to 100 ml of epichlorohydrin having an absorbance of 0.03 at 420 nm in a 1 cm cell. After the addition, the absorbance of epichlorohydrin at 420 nm was 0.02, and the solution was no longer colored.

Example 4 The process was carried out by changing the amount of hydrogen peroxide added to the reflux liquid of the low boiling distillation column in the epichlorohydrin production process. The absorbance at 420 nm was investigated for the obtained epichlorohydrin.

The results shown in Table 1 were obtained.

[0021]

[Table 1]

Claims (1)

[Claims] 1. A method for decolorizing epichlorohydrin, which comprises treating industrially produced epichlorohydrin by contacting it with hydrogen peroxide.