JPH0995481A - Recovery of indole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently absorb and separate indole from an indole-containing fraction. SOLUTION: In this method for recovering indole by an absorptive separation method from an indole-containing distilled fraction, absorptive separation is carried out using a K or Na-substituted faujasite zeolite as an absorbent and using acetates as a desorbing agent to recover the objective indole.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for recovering indole from an indole-containing fraction such as coal tar fraction by adsorption separation.

[0002]

2. Description of the Related Art A method for recovering indole from an indole-containing fraction such as a coal tar fraction by adsorption separation is disclosed in JP-B-60-21587 and 60-2158.
It is known from Japanese Patent Laid-Open No. 8 and Japanese Patent Laid-Open No. 1-157956. In these methods, faujasite zeolite and basic ion exchange resins have been proposed as adsorbents, and anisole, alcohols, etc. have been proposed as desorbents.

Although these methods are excellent in that indole, which is difficult to separate by distillation, can be efficiently separated, industrially, higher adsorption separation efficiency is desired. That is, it is desired that the adsorption capacity and the separability are excellent.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently separating and recovering indole from an indole-containing fraction.

[0005]

The present invention is a method for recovering indole from an indole-containing fraction by an adsorption separation method, in which K or Na-substituted faujasite zeolite is used as an adsorbent and acetic acid esters are used as a desorbent. It is a method for recovering indole which is characterized in that it is used for adsorption separation.

The indole-containing fraction is a fraction containing indole such as coal tar fraction, but is preferably a fraction whose indole concentration is increased to about 2 to 20% by weight by distillation or the like. For example, it is a fraction having a boiling point range of about 220 to 270 ° C., and may be washed with an acid or an alkali if necessary.

The adsorbent used in the present invention is K- or Na-substituted faujasite zeolite, specifically K
Examples thereof include substituted Y-type zeolite and Na-substituted Y-type zeolite. The substitution ratio of K or Na may be 50% or more, preferably 90% or more.

The desorbing agent used in the present invention is an acetic acid ester, and specific examples thereof include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate and the like.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention can be carried out by a known method, for example, a fixed bed, fluidized bed, moving bed or simulated moving bed system. Industrially, the simulated moving bed system is advantageous. The desorption conditions are usually 40 to 120 ° C, preferably 50 to 100 ° C,
The pressure is 1 to 20 atm. Further, it is advantageous that the developing agent is the same as the releasing agent.

[0010]

【Example】

Example 1 17 g of K-substituted Y-type zeolite (0.4 mmφ fine-grain product) which was previously calcined at 350 ° C. for 4 hours and cooled in a desiccator
Was packed in a steel pipe having a diameter of 8 mm and a length of 500 mm to form a column. The column temperature was maintained at 80 ° C, and butyl acetate was used as a developing agent from one end of the column with a metering pump at 5 ml / mi.
n. Was fed at the rate of. After confirming that the inside of the column was filled with butyl acetate, the supply of butyl acetate was stopped, and the indole-containing fraction A obtained from coal tar (2,3,5-triisopropylbenzene was used as an internal standard substance).
Wt%) from the one end of the column to 5 ml / min. Was fed at the rate of.

Composition of Indole-Containing Fraction A (% by Weight) Naphthalene 1.9 1-Methylnaphthalene (α-MN) 15.7 2-Methylnaphthalene (β-MN) 64.2 Quinoline 0.5 Indole 5.1 Biphenyl 2.2 Dimethylnaphthalene 2.0 Acenaphthene 0.1 Dibenzofuran 0.1 Others 8.2

At this time, the liquid flowing out from the other end was periodically analyzed. The result is shown in FIG. In FIG. 1, the horizontal axis represents the outflow time (min.), And the vertical axis represents the normalized concentration of each component.

After stopping the supply of the indole-containing fraction, butyl acetate as a desorbing agent was then added at 5 ml / min.
It was supplied at a rate of and desorption was performed for 40 minutes. At this time, the liquid flowing out from the other end was analyzed periodically to calculate the adsorption capacity of indole. The results are shown in Table 1.

Examples 2 and 3 and Comparative Examples 1 to 4 The same experiment as in Example 1 was carried out except that the solvent or column temperature of the adsorbent, the developing agent and the desorbent was changed. The results are shown in Table 1.

[0015]

[Table 1]

Example 4 In an experiment similar to that of Example 1, the column temperature was kept at 80 ° C., and butyl acetate as a developing agent and a desorbing agent was supplied from one end of the column at a constant rate of 5 ml / min. And the column was filled with butyl acetate. While passing butyl acetate, 1 ml of the indole-containing fraction A was measured and supplied. At this time, the liquid flowing out from the other end was periodically analyzed to obtain the outflow curve shown in FIG. In order to facilitate comparison, the curve is shown as a normalized concentration corrected with 1 as the highest concentration point at the time of outflow.

Comparative Example 5 The same experiment as in Example 4 was conducted except that the solvent used as the developing agent and the releasing agent was cyclohexanone. The outflow curve is shown in FIG. From these outflow curves, it is understood that the combination of KY and butyl acetate has a good separation condition, and when evaluated by the retention time, the indole and the other substances are most separated and the tailing of the indole is small.

[0018]

INDUSTRIAL APPLICABILITY The recovery method of the present invention can efficiently adsorb and separate indole from an indole-containing fraction.

[Brief description of drawings]

FIG. 1 shows the outflow time (mi) in Example 1.
n. 3) and the normalized concentration of each component.

FIG. 2 is a graph showing an outflow curve in Example 4.

FIG. 3 is a graph showing an outflow curve in Comparative Example 5.

Claims (1)

[Claims] 1. A method for recovering indole from an indole-containing fraction by an adsorption separation method, wherein K or Na-substituted faujasite zeolite is used as an adsorbent, and acetic acid esters are used as a desorbent. Characteristic indole collection method.