JP6450503B1 - Method for producing tar acid - Google Patents

Abstract

To provide a method for producing tar acid that can more easily reduce the content of a basic substance contained in tar acid. In step A, alkali is added to carboru oil and / or naphthalene oil obtained by distillation of coal tar to convert tar acid contained in the carboru oil and / or naphthalene oil into a tartrate; Step B for obtaining a mixture by adding tar acid containing a basic substance to the obtained tar acid salt, and step for obtaining crude tar acid by adding an acid to the mixture obtained in Step B A method for producing tar acid, which comprises C and step D to obtain tar acid by distilling the crude tar acid obtained in step C.

Description

  The present invention relates to a method for producing tar acid.

  Tar oil (coal acid) is contained in the light oil obtained by distilling coal tar generated when carbonizing carbon. Conventionally, as a method of producing tar acid from coal tar, among the fractionated oils obtained by distillation of coal tar, an alkaline aqueous solution is added to carbol oil or naphthalene oil containing a large amount of tar acid, and tar acid is then added. Extracted and recovered as an alkali salt in the aqueous layer, decomposed the recovered alkali salt of tar acid with carbon dioxide or sulfuric acid to obtain crude tar acid, and then purified and distilled the crude tar acid to obtain phenol, cresol, xylenol, etc. There is known a method for obtaining a tar acid containing as a main component.

  Tar acids are used as raw materials for optical resins, cosmetics, agricultural chemicals, etc., but tar acids derived from coal tar contain basic substances (tar bases) such as aniline, pyridine, picoline, lutidine, and quinoline. These need to be removed. Among tar acids distributed in the market, relatively cheap tar acids tend to have a high content of basic substances, and a method for easily removing the basic substances is required.

  As a technique for reducing the content of a basic substance contained in tar acid, Patent Document 1 discloses a method (activated carbon method) in which nitrogen compounds and sulfur compounds are removed by adsorption using activated carbon. Patent Document 2 discloses a method (sulfuric acid addition method) in which sulfuric acid is added to tar acid that is a raw material for distillation in the distillation step of crude tar acid or purified tar acid. In Patent Document 3, as a technique for removing nitrogen compounds contained in cresols, cresols are treated with an aqueous solution of a basic compound and then separated, and the obtained cresols are further added with an aqueous solution of an acidic compound. A method (pickling method) for treating and then separating liquids is disclosed.

  Among the above methods, the activated carbon method and the pickling method require special equipment, so the sulfuric acid addition method is widely used. The sulfuric acid addition method is a method for removing impurities in tar acid by adding sulfuric acid into a distillation kettle and distilling in a distillation step for producing purified tar acid from crude tar acid or a distillation step for purified tar acid. Although it is a purification method, when the concentration of the basic substance in the distillation raw material increases, the concentration of the basic substance in the final product tends to increase. In order to reduce the concentration of basic substances in the final product, it is necessary to increase the amount of sulfuric acid added to the distillation kettle, but hot sulfuric acid is highly corrosive. And the risk of corroding the distillation tower.

JP-A-9-53080 Japanese Patent Laid-Open No. 7-41768 JP-A-4-210659

  An object of this invention is to provide the manufacturing method of tar acid which can reduce more easily the content of the basic substance contained in tar acid.

The present invention has the following aspects.
[1] A step A in which alkali is added to carbol oil and / or naphthalene oil obtained by distilling coal tar, so that tar acid contained in the carbol oil and / or naphthalene oil is converted into a tar salt, A tartaric acid containing a basic substance is added to the tar acid salt obtained in the step A to obtain a mixture, and an acid is added to the mixture obtained in the step B to obtain a crude taric acid. A process for producing a tar acid comprising: a process C for obtaining a tar acid; and a process D for distilling the crude tar acid obtained in the process C to obtain a tar acid.

According to the method for producing tar acid of the present invention, the content of the basic substance contained in tar acid can be more easily reduced.
According to the method for producing tar acid of the present invention, it is not necessary to provide special equipment required when using the activated carbon method or the pickling method, and the basic substance can be easily used by using existing tar acid production equipment. The content of can be reduced. Further, in the tar acid production facility, it is not necessary to perform treatment using excess sulfuric acid at a high temperature, and the risk of corroding the facility is reduced.

FIG. 1 is a schematic view showing a flow of one embodiment of the method for producing tar acid of the present invention. FIG. 2 is a graph showing the relationship between the addition ratio of the basic substance-containing tar acid investigated in the Examples and the base concentration in the m, p-cresol product.

  Hereinafter, an embodiment of the method for producing tar acid of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

(Production method of tar acid)
FIG. 1 is a schematic view showing a flow of one embodiment of the method for producing tar acid of the present invention. In the method for producing tar acid of the present invention, alkali is added to carbol oil and / or naphthalene oil obtained by distilling coal tar, and tar acid contained in the carbol oil and / or naphthalene oil is converted to tarate. Step A, and adding the tar acid containing a basic substance to the tartrate obtained in Step A to obtain a mixture, and adding the acid to the mixture obtained in Step B And a step C to obtain a crude tar acid and a step D to obtain the tar acid by distilling the crude tar acid obtained in the step C.

<Process A>
Carbol oil and / or naphthalene oil may be obtained by distillation of coal tar. For example, as shown in FIG. 1, coal tar is inserted into a dehydration tower, dehydrated, and then dehydrated and inserted into an atmospheric distillation tower to perform distillation. A fraction is obtained. At this time, the carbol oil is obtained as a fraction of about 170 to 200 ° C, and the naphthalene oil is obtained as a fraction of about 200 to 250 ° C. A large amount of tar acid is contained in the carbol oil and naphthalene oil. In the present specification, the temperature of the fraction, boiling point and the like means a temperature at normal pressure unless otherwise specified.

  In step A, an alkali is added to the carbol oil and / or naphthalene oil obtained as described above, so that the tar acid contained in the carbol oil and / or naphthalene oil is converted into a tar acid salt.

  Examples of the alkali include lithium hydroxide, sodium hydroxide (NaOH), potassium hydroxide (KOH), and cesium hydroxide. An alkali may be used individually by 1 type and may be used in combination of 2 or more type. Preferred alkalis are sodium hydroxide and potassium hydroxide.

  In the step A, preferably, an aqueous alkaline solution is added to carboruyl oil and / or naphthalene oil, and the tar acid contained in the carboru oil and / or naphthalene oil is added to the tar acid salt (alkali acid alkali salt). ) As an alkaline aqueous solution. That is, in the extraction tank, a separation process is performed to separate the aqueous layer containing the tar salt and the oil layer from which the tar acid has been removed (deoxidized). And after the said separation process, the water layer containing a tartrate is collect | recovered.

  In addition, in the manufacturing method of the tar acid of this invention, any one of carboru oil and naphthalene oil may be used, and both carboru oil and naphthalene oil may be used.

  The alkaline aqueous solution is preferably a caustic soda aqueous solution. Although the density | concentration of the said alkaline aqueous solution is adjusted suitably, as an example, it is about 10-12 mass%.

<Process B>
In step B, tar acid containing a basic substance (hereinafter also simply referred to as “basic substance-containing tar acid”) is added to the tartrate obtained in step A (aqueous layer containing tartrate). As a result, a mixture containing the tar acid salt and the basic substance-containing tar acid is obtained.

  The basic substance-containing tar acid is a tar acid having a high content of basic substances (tar bases) such as aniline, pyridine, picoline, lutidine, quinoline, etc., and is obtained by, for example, crude tar acid or purifying and distilling it. This tar acid is a tar acid in which the content of the basic substance is not sufficiently reduced with respect to the target specification.

  In one embodiment of the method for producing tar acid of the present invention, the basic substance is at least one selected from the group consisting of aniline, pyridine, picoline, lutidine and quinoline.

  As an example, the basic substance-containing tar acid contains 2000 ppm by mass or more or 2100 ppm by mass or more of a basic substance. Further, the upper limit of the content of the basic substance in the basic substance-containing tar acid is not particularly limited, but as an example, the basic substance-containing tar acid is 4000 mass ppm or less, 3000 mass ppm or less, or 2700 mass ppm or less. Contains basic substances.

  In one Embodiment of the manufacturing method of the tar acid of this invention, the quantity of the basic substance which the said tar acid containing the basic substance contains is 2000-4000 mass ppm.

  The addition amount of the basic substance-containing tar acid in step B is appropriately adjusted according to the desired amount of tar acid treated. According to the production method of the present invention, even if the amount of the basic substance-containing tar acid added in Step B is increased, the concentration (base concentration) of the basic substance in the tar acid product can be reduced. For example, the addition amount of the basic substance-containing tar acid can be 5% by mass or more, 10% by mass or more, and 15% by mass or more with respect to the mass of the tartrate salt. It is good also as 20 mass% or more. Moreover, although the upper limit of the addition amount of a basic substance containing tar acid is not specifically limited, For example, it is 30 mass% or less, 25 mass% or less, or 20 mass% or less with respect to the mass of tartrate.

  In one Embodiment of the manufacturing method of the tar acid of this invention, in the said process B, the ratio of the mass of the tar acid containing the said basic substance with respect to the mass of the said tarate is 5-30 mass%. In another embodiment, in the step B, the ratio of the mass of the tar acid containing the basic substance to the mass of the tartrate is 10 to 25 mass%.

  In one embodiment, the mixture containing the tarrate and the basic substance-containing tar acid is charged into a mixing tank and mixed.

<Process C>
In Step C, an acid is added to the mixture obtained in Step B to obtain a crude tar acid.
Examples of the acid include carbon dioxide gas and / or sulfuric acid, and sulfuric acid is preferable. In one embodiment of Step C, the mixture is contacted with the acid in an unheated state. The temperature of the mixture at the time of making a mixture contact with an acid is 55-80 degreeC as an example.

  In this step C, it is considered that a treatment for pickling the basic substance-containing tar acid is performed together with a reaction to decompose the tar acid salt with an acid to obtain a crude tar acid. Therefore, by passing through Step C, the basic substance can be removed from the basic substance-containing tar acid, and the content of the basic substance can be reduced. Furthermore, the effect of pickling can be further enhanced by using sulfuric acid as the acid.

  In one embodiment of the step C, after obtaining the crude tar acid in the acid decomposition tank by the above reaction, a step of standing and separating to remove the acid (sulfuric acid) may be optionally included.

<Process D>
In Step D, the crude tar acid obtained in Step C is distilled to obtain tar acid.
This process D is not specifically limited, For example, it can implement similarly to the conventional method. For example, crude tar acid is continuously distilled to produce various tar acids (phenol, o-cresol, m, p-cresol, xylenol, etc.) by distillation. At this time, prior to the continuous distillation, the crude tar acid may be subjected to a dehydration treatment and a pitch removal treatment.

  In one embodiment of the method for producing tar acid of the present invention, the tar acid obtained in Step D is at least one selected from the group consisting of phenol, o-cresol, m, p-cresol and xylenol.

  The tar acid obtained in the step D may be used as it is according to product specifications, or may be further subjected to batch distillation to obtain a product.

  According to the method for producing tar acid of the present invention, it is possible to produce tar acid with a reduced basic substance content more easily by effectively utilizing existing tar acid production equipment. In addition, it is not necessary to perform treatment using excess sulfuric acid at a high temperature, and the risk of causing corrosion or the like in equipment can be reduced.

Example 1
The tar acid was manufactured according to the flow shown in FIG. 1, and the effect of the present invention was verified by examining the content of the base (tar base) contained in the m, p-cresol product.

  First, an aqueous solution of caustic soda is added to carbol oil and naphthalene oil obtained by distillation of coal tar, and tar acid contained in carbol oil and naphthalene oil is converted into a tar salt and recovered in an aqueous layer (step A). ).

  Next, a basic substance-containing tar acid was added to the tarate obtained in Step A to obtain a mixture (Step B). The base concentration in the basic substance-containing tar acid was about 2100 to 2700 mass ppm. The basic substance contained in the basic substance-containing tar acid was aniline, pyridine, quinoline or the like.

Sulfuric acid was added to the mixture obtained in Step B to decompose the tar acid salt to obtain a crude tar acid. The temperature of the mixture when the mixture was contacted with sulfuric acid was 65 ° C.
(Process C)
Thereafter, the crude tar acid obtained in Step C was distilled using a continuous distillation facility to obtain tar acid (phenol, o-cresol, m, p-cresol, xylenol) (Step D).

  The m, p-cresol was further distilled in a batch distillation facility with 1 equivalent of sulfuric acid added to the base to obtain an m, p-cresol product having a purity of 99.0% by mass or more. Then, the base concentration in the m, p-cresol product was measured.

  The above steps were repeated with the basic substance-containing tar acid addition ratio (addition amount (mass%) of basic substance-containing tar acid to the mass of tartrate) changed in step B.

(Comparative Example 1)
An m, p-cresol product was produced in the same manner as in Example 1 except that the basic substance-containing tar acid was added to the crude tar acid without performing Step B.

  That is, in Comparative Example 1, a caustic soda aqueous solution was added to carbol oil and naphthalene oil obtained by distilling coal tar, and tar acid contained in carbol oil and naphthalene oil was converted to tarate and recovered in an aqueous layer. Then, sulfuric acid was added to the tar acid salt to obtain a crude tar acid, and then a basic substance-containing tar acid was added to the crude tar acid. Thereafter, a mixture containing the crude tar acid and the basic substance-containing tar acid is distilled using a continuous distillation facility to obtain tar acid (phenol, o-cresol, m, p-cresol, xylenol), and the m, p- Cresol was further distilled with a batch distillation equipment to obtain an m, p-cresol product having a purity of 99.0% or more. Then, the base concentration in the m, p-cresol product was measured.

  In FIG. 2, the result of investigating the relationship between the addition ratio of the basic substance containing tar acid in Example 1 and Comparative Example 1 and the base concentration in the m, p-cresol product is shown.

  The base concentration in the m, p-cresol product is desirably 30 ppm by mass or less. However, in the production method of Comparative Example 1, when the addition ratio of the basic substance-containing tar acid is about 10% by mass, m, The base concentration in the p-cresol product exceeded 30 mass ppm. On the other hand, in the manufacturing method of Example 1 to which the present invention is applied, the base concentration in the m, p-cresol product is 15 mass ppm or less even when the addition ratio of the basic substance-containing tar acid is 20 mass% or more. Could be maintained.

  From the above results, it can be seen that the content of the basic substance contained in tar acid can be more easily reduced by applying the method for producing tar acid of the present invention.

Claims (3)

To the carboru oil and / or naphthalene oil obtained by distillation of coal tar , an alkali that is one or more selected from lithium hydroxide, sodium hydroxide, potassium hydroxide and cesium hydroxide is added, A step A for converting a tar acid contained in the carbol oil and / or naphthalene oil into a tar salt;
A step of adding a tar acid containing at least one basic substance selected from the group consisting of aniline, pyridine, picoline, lutidine and quinoline to the tar acid salt obtained in the step A to obtain a mixture B and
Step C to obtain a crude tar acid by adding an acid to the mixture obtained in Step B,
A step D for obtaining the tar acid by distilling the crude tar acid obtained in the step C;
The manufacturing method of the tar acid which has this. Wherein in step B, to the mass of the tar acid salt, the ratio of the mass of the tar acid containing the basic substance, from 5 to 30 wt%, the production method of the tar acid according to claim 1. The manufacturing method of the tar acid of Claim 1 or 2 whose quantity of the basic substance which the tar acid containing the said basic substance contains is 2000-4000 mass ppm.

Images