JPH0718262A - Method for separating quinoline compound - Google Patents

Abstract

PURPOSE:To prevent the occurrence of emulsion and efficiently separate quinoline compds. from a tar oil fraction by removing toluene-insols. from the fraction and extracting it with an aq. acid soln. CONSTITUTION:A tar oil fraction contg. quinoline compds. and toluene-insols. is distilled to reduce the content of toluene insols. to 50ppm or lower. The fraction is then mixed with an aq. acid soln. with a concn. of 20-50wt.% in such an amt. that the concn. of a free acid in an aq. phase after extraction is 15wt.% or lower at from room temp. to 100 deg.C and then left standing to cause phase separation into an aq. soln. phase contg. quinoline compds. dissolved and a tar oil fraction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for separating quinolines from a tar oil fraction.

[0002]

2. Description of the Related Art The tar oil fraction obtained by distilling coal tar contains taric acids and tar bases, and is separated by alkali extraction and acid extraction. ing. Of the tar bases, quinolines mainly have a boiling point range of 200 to
Although it is contained in the middle oil fraction at about 260 ° C, this fraction contains a large amount of naphthalene compounds. Therefore, in addition to the purpose of recovering quinoline compounds, separation of quinoline compounds is also performed for the purpose of purifying naphthalene compounds. Is done. An example of base recovery from tar middle oil is "Aromatic and Tar Industry Handbook".
(The Japan Aromatic Industry Association, published in December 1978)
As shown in P91, in this example, 25% sulfuric acid is used for extraction in two steps. By the way, in this acid extraction, when a high-concentration aqueous acid solution is used or a large amount of acid is used, other useful components such as indol contained in this fraction are polymerized, and the recovery thereof is performed. It has been found that the rate drops. However, when an aqueous solution having a low acid concentration is used or the amount of acid used is reduced, the specific gravity of the aqueous solution phase is lowered, and there is a problem that phase separation after extraction is not successful. This problem becomes more serious as more emulsions are generated.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to efficiently separate quinolines from a tar oil fraction containing quinolines.

[0004]

[Means for Solving the Problems] The inventors of the present invention have made various studies in order to solve the above-mentioned problems. As a result, the occurrence of emulsion has a great relation with the difficulty of phase separation, and if the occurrence of emulsion can be suppressed, For example, it has been found that phase separation can be performed relatively easily even when the specific gravity of the acid aqueous solution phase is small. The inventors have found that the generation of emulsion is related to the toluene-insoluble matter in the tar oil fraction, and that the generation of emulsion can be suppressed by removing this in advance, and the present invention has been reached.

That is, according to the present invention, when the quinolines are extracted and separated from the tar oil fraction containing the quinolines and the toluene insolubles using an aqueous acid solution, the toluene insolubles are removed in advance and then the extraction and separation are performed. It is a characteristic method for separating quinolines.

The tar oil fraction containing quinolines is a fraction of about 200 to 260 ° C. in the cotterle fraction, but the present invention is not limited to this, and quinoline and methyl are not limited thereto. Any tar oil fraction containing at least one quinoline such as quinoline, isoquinoline and methylisoquinoline may be used,
It is desirable that the fraction distilled from the coltal is further subjected to operations such as distillation, extraction and storage. Then, this fraction contains a toluene insoluble matter. The toluene-insoluble component has a quinoline-soluble component (β-resin) and a quinoline-insoluble component (α-resin), but since this fraction is a distillate, α-resin is included as However, the amount is extremely small. Therefore, the substantial amount of toluene-insoluble matter is β-resin. According to some examples measured by us, it is about 10 ppm for α-resin versus about 300 ppm for β-resin. This toluene-insoluble content is close to that of a resin, and is considered to be included in the pitch as a residue when distilled, and is not considered to be distilled as a fraction. Surprisingly, it is a trace amount or a small amount, It was found that the tar oil fraction containing this was large. Although the mechanism by which toluene-insoluble matter is generated has not been confirmed, even if it is not contained in the fraction immediately after distilling from the coal, further operations such as distillation, extraction, storage and transportation are carried out. It is considered that during the process of receiving, a heavy substance is generated to generate a toluene insoluble matter. To confirm this, the present inventors conducted the following experiment. That is, from a tar oil fraction containing a large amount of naphthalene, about 220 to 250 ° C. containing the remaining methylnaphthalene, quinoline and the like after distilling and separating naphthalene.
The tar oil fraction (toluene insoluble content 0.100%) was heated at 200 ° C., 300 ° C., and 400 ° C. and the toluene insoluble content after 2 hours was examined. .128% and 0.140%, respectively, and it was confirmed that the temperature and time were one of the factors.

In the present invention, the toluene insolubles are removed from the tar oil fraction before the quinolines are extracted with the aqueous acid solution. It is desirable that the removal be performed to 0 as much as possible, but it is preferable that the removal be performed at 50 ppm or less, preferably 10 ppm or less, and more preferably 1 ppm or less. An almost linear relationship was observed between the amount of toluene insolubles and the amount of emulsion generated. Even if the amount is very small, a small amount of emulsion is generated, but phase separation does not cause great difficulty. If the amount is not more than the above amount, there is no practical problem.

There is no limitation on the method of removing the toluene insoluble matter, but the method of removing by distillation is advantageous. In this case,
The rutile oil fraction is distilled, most of it is distilled off, and the toluene insoluble fraction is left as a distillation residue. The fraction distilled here contains substantially no toluene insoluble matter, and is used for the next extraction separation.

As the acid aqueous solution used for extraction, a sulfuric acid aqueous solution is advantageous because it has a large specific gravity and relatively weak corrosiveness, and its concentration is about 20 to 50% (weight%, the same applies hereinafter). desirable. If the concentration is too high, deterioration such as polymerization of other useful components such as indol occurs, and if it is too low, the difference in specific gravity from the oil phase is small and phase separation becomes difficult. The amount of the aqueous acid solution used is more than an amount sufficient to neutralize the bases such as quinoline, but the free acid concentration in the aqueous phase after extraction is 15
% Or less, preferably about 2 to 10%. If it is used too much, the quality of other useful components such as indole is deteriorated by polymerization, and if it is too little, phase separation becomes difficult or quinoline separation becomes insufficient.

The extraction can be carried out by bringing the tall oil fraction and the aqueous acid solution into contact with each other with a mixer or the like, then allowing them to stand still and performing phase separation. The extraction temperature is in the range of normal temperature to about 100 ° C. Since the aqueous phase dissolves quinolines, it undergoes metathesis with a base such as ammonia to liberate quinolines, and then this is separated and purified by distillation or the like to obtain quinolines and the like. Since the oil phase contains hydrocarbons such as naphthalene and methylnaphthalene and indol, it is separated and purified by distillation or the like. In this case, when the quinolines and the oil phase are used as they are as a mixture such as for a solvent, separation and purification are not particularly necessary.

[0011]

Most of the toluene-insoluble matter contained in the tar oil fraction is quinoline-soluble matter.
It is also soluble in the oil fraction. When this is extracted with an aqueous acid solution, quinoline disappears from the oil phase and free quinoline also disappears from the aqueous phase, so the toluene insoluble matter that had been dissolved up to now precipitates, and this forms an emulsion with the aqueous acid solution. It is considered that oil and water further entered the emulsion, and the emulsion phase became large, which hindered phase separation. It is considered that by removing the toluene insoluble matter in advance, the original was cut off, the generation of emulsion was prevented, and the phase separation was successful.

[0012]

【Example】

Example 1 Mainly composed of naphthalene and methylnaphthalene, indole is 4.0%, quinoline is 9.7%, and toluene-insoluble matter is 3%.
About 220 including 30ppm (QI content 10ppm or less)
A tar oil fraction mainly containing a fraction at 250 ° C. was sent to a distillation column to distill 97% and leave 3% as a residue. No toluene-insoluble matter was found in the distilled fraction.
25 ml of a 30% strength aqueous sulfuric acid solution was added to 100 ml of this fraction.
After adding ml and stirring to bring them into sufficient contact, they were placed in a graduated cylinder and allowed to stand, and the separation state between the aqueous phase and the oil phase was observed. After standing for a period of time, no emulsion phase was observed and it was confirmed that the phases were clearly separated. The free acid concentration in this case is 10%.

Comparative Example 1 The same experiment as in Example 1 was carried out except that the tar oil fraction was distilled and the toluene insoluble matter was not removed.
As a result, the emulsion phase is 50 ml between the oil phase and the water phase.
It was happening.

Test Example When anthracene oil was heated to 300 ° C., about 7% of toluene-insoluble matter was produced. The toluene-insoluble matter was collected as in Example 1.
Was dissolved in a fraction containing no toluene-insoluble matter obtained by the above distillation, and the relationship between the amount of emulsion generated and the amount of toluene-insoluble matter mixed was investigated. The fraction was 80 ml, the 30% sulfuric acid aqueous solution was 20 ml (free acid concentration after extraction was about 10%), contacted in the same manner as in Example 1, then allowed to stand, and the amount of the emulsion phase was measured. It was the next result. Toluene insoluble content mixed amount Emulsion phase 0 ppm 0 ml 60 3 90 4 135 6 275 19 428 30 638 48

[0015]

According to the separation method of the present invention, the generation of an emulsion phase can be prevented, so that oil-water separation can be easily performed. Also, the emulsion phase had to be incinerated only, but not only can most of it be recovered as useful components, but the incineration cost can be greatly reduced. Furthermore, since phase separation is facilitated, restrictions on the concentration and amount of the acid aqueous solution used for extraction are relaxed, and extraction conditions that consider not only quinolines but also other useful components such as indoles. It is also possible to adopt.

Claims (2)

[Claims] 1. To extract and separate quinolines from a tar oil fraction containing quinolines and toluene insolubles using an aqueous acid solution, first remove toluene insolubles and then extract and separate using an aqueous acid solution. A method for separating quinolines, which is characterized in that 2. The method for separating quinolines according to claim 1, wherein the toluene insoluble matter is removed by distillation.