JP2823431B2 - Epichlorohydrin decolorization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the decolorization of colored epichlorohydrin. More specifically, industrially manufactured epichlorohydrin products include:
Alternatively, epichlorohydrin is decolorized by adding hydrogen peroxide to epichlorohydrin in the production process.

[0002]

BACKGROUND OF THE INVENTION Generally, epichlorohydrin is produced by dehydrochlorinating dichloropropyl alcohol with calcium hydroxide. Specifically, an aqueous solution of 3 to 6% of dichloropropyl alcohol and milk of lime 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, first, water and impurities having a lower boiling point than epichlorohydrin are removed in a low-boiling distillation column, and epilorohydrin is extracted in the next product distillation column. For impurities having a higher boiling point than epichlorohydrid obtained from the product distillation column, epichlorohydrone in the high-boiling substance is recovered by the next distillation column.

At this time, chlorinated hydrocarbons such as propane trichloride contained as impurities cause a reaction such as dehydrochlorination by a reboiler of a distillation column, and water accompanying epichlorohydrin is converted into impurities. Reaction may cause coloring of the process liquid. As a result, even the epichlorohydrin of the product is colored, the chromaticity of the product standard exceeds the specification, and the product cannot be taken out.

[0004] Conventionally, as a method for decolorizing colored epichlorohydrin, for example, an adsorption method using activated carbon, activated alumina, or the like, and a distillation method for precision distillation again are known.

[0005] However, these methods not only require new equipment, but also have a problem of environmental pollution in the regeneration or disposal of the adsorbent containing organic substances in the adsorption method, and a large amount of energy is required in the distillation method. Therefore, both are not practical.

[0006]

The present inventors have conducted intensive studies to solve these problems, and as a result, it has been found that by adding hydrogen peroxide to colored epichlorohydrin, the color can be easily decolorized. 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.

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

That is, the colored epichlorohydrin 4
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 × VA A ₁ : Absorbance before addition A ₂ : Absorbance after addition V: Addition amount (vol%) in terms of 100% of hydrogen peroxide Therefore, in the case of a normal product epichlorohydrin A
Hydrogen peroxide may be added so that ₂ becomes 0.02 or less. The hydrogen peroxide is generally added in the form of an aqueous solution, and usually about 30% is used.

In addition, the addition of hydrogen peroxide in the present invention is not only applied to industrially produced epichlorohydrin products, but also to places where epichlorohydrin is highly colored in the production process, that is, A reflux liquid of a low boiling distillation column may be used.

The features of the present invention include the following.

1) There is no need to newly install large-scale equipment such as a tower and a tank.

2) Even if a trace amount of excess hydrogen peroxide remains, it only changes to water and does not become an impurity which has other adverse effects.

3) The operation is very simple.

Hereinafter, the present invention will be described specifically 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% aqueous hydrogen peroxide solution was added. Epichlorohydrin 4 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. The absorbance at 420 nm of epichlorohydrin after the addition 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. The absorbance at 420 nm of epichlorohydrin after the addition was 0.02, and the solution was no longer colored.

Example 4 In a process for producing epichlorohydrin, the amount of hydrogen peroxide added to the reflux of the low-boiling distillation column was changed. The absorbance at 420 nm of the obtained epichlorohydrin was investigated.

The results shown in Table 1 were obtained.

[0021]

[Table 1]

Claims (1)

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