JPS6047096A - Batching-off of naphthalene and methylnaphthalene from crude methylnaphthalene oil - Google Patents

Abstract

PURPOSE:To batch off efficiently a naphthalene component useful for vermin expellant, etc. and a methylnaphthalene component useful as solvent, etc., by adding a gamma-lactone and a polyalkylene glycol to a crude methylnaphthalene oil to be subjected to fractional distillation. CONSTITUTION:A gamma-lactones (e.g. gamma-butyrolactone) and a polyalkylene glycol (e.g. diethylene glycol) are added to a crude methylnaphthalene oil in an amt. of 20-500wt%. In the 1st-step distillation, an azeotrope of gamma-lactone and naphthalene is batched off and water is added to it to recover naphthalene that crystallizes out, by centrifugal separation, etc. Bottom of the 1st-step distillation is subjected to 2nd-step distillation to batch off an azeotrope of polyalkylene glycol and naphthalene. The azetrope is left at rest for separation into two layers and the upper methylnaphthalene layer is taken out for recovery, while the lower polyalkylene glycol layer is circulated for reuse.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for distilling and fractionating a naphthalene fraction and a methylnaphthalene fraction from crude methylnaphthalene oil.

Naphthalene is a raw material for phthalic anhydride and a dye intermediate.

Methylnaphthalene is useful as an insecticide, fungicide, lubricant, etc., and is an important compound as a solvent, dye carrier, and heating medium raw material. Although these two substances differ depending on the fraction cut range, for example, as shown in Table 1, they are contained in large amounts in the soot-7talene distillation residual oil, which is one of the crude methylnaphthalene oils.

However, as shown in the same table, the naphthalene stillage residue contains not only naphthalene and methylnaphthalene, but also dimethylnaphthalene and various other organic compounds.
It is not easy to separate and recover them.

Table 2 shows the results of the distillation of the first 7 talen distilled by the present inventors using the distillation apparatus used in the examples described below.
This shows the results of distillation at a reflux ratio of 15:1, and as shown, both naphthalene and methylnaphthalene were distilled across multiple distillation cut sections, and their purity was extremely low. Therefore, such a separation method called rectification separation is inappropriate as a method for separating and recovering naphthalene and methylnaphthalene for the above-mentioned uses.

From the above viewpoint, the present invention provides a separation and recovery method (abbreviated as preparative separation) suitable for industrial production in place of precision distillation, in which crude methylnaphthalene oil as a raw material for distillation is
Lactones and polyalkylene glycols are added and subjected to a first distillation, γ-lactones and naphthalene azeotrope are distilled off, and the bottom oil is subjected to a second distillation,
This method is characterized by distilling off an azeotrope of polyalkylene glycols and methylnaphthalene, and completely separates naphthalene and methylnaphthalene from the crude methylnaphthalene.

Crude methylnaphthalene oil to which the method of the present invention can be applied is a distillate that is usually distilled at 200 to 300°C when coal tar or petroleum hydrocarbon oil is fractionated, and of course, the temperature at which it is cut is 9 The composition ratio varies slightly depending on the coal tar to be fractionated, the coal that is its raw material, its carbonization conditions, or the properties of the petroleum hydrocarbon oil.
It contains 5% or more naphthalene, 10% or more methylnaphthalene, dimethylnaphthalene, and various organic compounds.

In the method of the present invention, the reason why γ-lactones and polyalkylene glycols are added to crude methylnaphthalene oil as a raw material to be distilled is as follows.
・Lactones are low-boiling organic compounds such as sulfur-containing heterocyclic compounds such as na7dane and benzothiophene (
It forms an azeotrope with polyalkylene glycols, methylnaphthalene, etc., and polyalkylene glycols form an azeotrope with methylnaphthalene and some organic compounds (hereinafter referred to as methylnaphthalene). It forms azeotropes with organic compounds such as γ-lactones, nitrogen-containing heterocyclic compounds, oxygen-containing heterocyclic compounds, and bicyclic aromatic compounds such as 7-talene, dimethylnaphthalene, and biphenyl. This is to take advantage of the fact that there is a temperature range in which there is almost no azeotropy.

Such r-lactones are compounds represented by the general formula R-CH-CH2.CH2.C00, which has a 5-membered ring and contains an ester functional group -CO-O- in the ring, where: R is H or C1-1
2 alkyl groups can be numbered. Of course, as the number of carbon atoms in the alkyl group increases, that is, as the molecular weight increases, the solubility in crude methylnafculene oil decreases.
The azeotropic temperature of butyrolactone and naphthalene is 202 to 204°C under normal pressure.

In addition to diethylene glycol, the polyalkylene glycols used in the present invention include triethylene glycol, dipropylene glycol, and a mixture of diethylene glycol-dipropylene glycol. For example, the azeotropic temperature of diethylene glycol and methylnaphthalene is 224 to 226°C under normal pressure.

The amount of γ-lactones added to the raw material methylnaphthalene oil to be distilled is 0.2 to 5 times the weight of the oil, and the amount of polyalgylene glycols added is 0.2 to 5 times the weight of the oil. The reflux ratio in the operation is about 2 to 15 for both the first distillation column and the second distillation column, and these values are based on the experimental results carried out by the inventor.

In addition, the above-mentioned 7talene, methylnaphthalene, and methylnaphthalene fractions are used to refer to these distillates.
This is because some organic compounds such as benzothiophene are included.

In the method of the present invention, two distillation columns are used, the first column distills off the low ψ naphthalene fraction with an azeotropic temperature, and the second distillation column is applied to the residue. The purpose is to recover naphthalene and methylnaphthalene with higher purity.

In this way, two distillation columns are used to distill the two types of azeotropes mentioned above, so only γ-lactones are used as azeotropic solvents in the first distillation column. Furthermore, although it is a normal method to add only polyalkylene glycols to the second distillation column, the reason why both azeotropic solvents are added to the first column from the beginning is that both azeotropic solvents are added to the first column from the beginning. This is because the same effect can be obtained even when added in the tower or when added individually.

The method of the present invention can of course be carried out in a batch manner, but
The first distillation and the second distillation can be connected in series and carried out as a continuous series of steps. The explanation will be given below with reference to FIG. 1, which is a process diagram of an embodiment of such continuous distillation and fractionation. ``Gamma lactones (L) and polyalkylene glycols (M) are added to crude methylnaphthalene oil (K) as a raw material to be distilled in pipe (1) via pipe (2), and A mixture of γ-lactones and polyalkylene glycols circulating from a pipe (15) to be described later is combined and introduced into a first distillation column (3) where it is subjected to a first distillation.

From the top of the distillation column, γ-lactones and naphthalene azeotrope are distilled into pipe (4). According to experimental results, an appropriate reflux ratio is approximately 2 to 15.
It's between.

This r-lactone and naphthalene azeotrope is passed through the pipe (19
) is introduced into the mixing tank (20) and mixed with water added via the pipe (21) at 50 to 70°C.

The amount of water added is suitably 0.6 times or more the weight of the azeotrope.

The water mixture obtained in and \ is cooled while being transferred through the pipe (22), and naphthalene crystallizes, so it is transferred to the decanter type centrifuge (23) connected to the pipe (22). The crystals of 7talene containing some impurities are separated and recovered via line (24). Note that a cooling tank may be provided in place of the mixing tank (20), and naphthalene may be crystallized by cooling and separated and recovered.

In this case no addition of water is necessary.

The liquid phase separated by the separator (23) mainly consists of r-lactones and water originating from the pipe (21). This material passes through a pipe (25), joins with an aqueous polyalkylene glycol solution that is circulated through a pipe (18) to be described later, and passes through a pipe (29) to a dehydration tower (26).
to be introduced. Steam is blown into the column from a pipe (not shown) to perform topping, and the water distilled from this column passes through the pipe (27) and joins the water in the pipe (21) for circulation. do.

The mixture of γ-lactones and polyalkylene glycols containing some water is extracted from the bottom of the tower via a pipe (28) after topping, and is combined with the polyalkylene glycols in a pipe (15) to be described later. The bamboo leaves are recycled to the pipe (1).

Distillation separation between the azeotropic temperatures of the two types of azeotropes described above is performed, side-cut in the first distillation column, and distilled off via the pipe (5). Its composition is generally benzothiophene, r-lactones, etc. The bottom of the first distillation column (3) is a mixture of polyalkylene glycols, methylnaphthalene, and organic compounds that are not distilled out.

In this step, this product is led to a second distillation column (8) and subjected to a second distillation. In the second distillation column (8),
The azeotrope of polyalkylene glycols and methylnaphthalene is distilled off from the top of the column and recovered via pipe (9).

Based on the experimental facts of the present inventors, in this distillation,
It is not necessarily necessary to apply reflux l-1: However, depending on the composition of the residual oil to be distilled, it may be preferable to apply reflux. Even in that case, the reflux ratio is generally in the range of 2 to 15. In the figure, the reflux path indicates that the glycols and methylnaphthalene azeotrope are then introduced into a separation tank (13) and left in the tank at room temperature. After a while, the mixture separates into two layers: methylnaphthalene in the upper layer and polyalkylene glycol in the lower layer. Therefore, the upper layer of methylnaphthalene is recovered from the pipe (14). The polyalkylene glycols in the lower layer are passed through the pipe (15) from the bottom of the separation tank (13).
It is extracted through the pipe and circulated through the pipe (1).

The bottom of the second distillation column (8) is a mixture of dimethylnaphthalene, other high-boiling organic compounds, and polyalkylene glycols.

The residue is led from the bottom of the tower through a pipe (10) to a solvent recovery tank (16), where water is added.

Then, it separates into two layers: the lower layer of the aqueous polyalkylene glycol solution and the upper layer of the oil layer. Therefore, the lower polyalkylene glycol aqueous solution layer passes through the pipe (18), joins the aforementioned mixture of r-lactones and water in the pipe (25), and is introduced into the dehydration tower (26). After being topped with water, the polyalkylene glycols are
It will be circulated in old rivers along with gamma-lactones.

Since the upper oil phase is a mixture of dimethylnaphthalene and other high-boiling organic compounds, it passes through the pipe (17) and, if necessary, is subjected to recovery treatment outside the present invention.

Example 1 1st 'b (B) Listed crude methylnaphthalene M40
o part, 0.4[gamma butyrolactone of corporate bond and 0.
5 times the length of diethylene glycol, and the tower top temperature was 2.
A first distillation is carried out at a reflux ratio of 2 until the temperature reaches 0.4°C, and an azeotrope of r-butyrolactone and naphthalene is distilled from the top of the column.
Two parts of 24° were distilled off. In the azeotrope, naphthalene 6
It contained 3.8 parts. The distillation column used for this distillation was a Helivac packed column with an effective inner diameter of 30 mm and an effective length of 1200 mm.

After the first distillation is completed, 6.2 parts of the fraction with a column top temperature of 205 to 223°C are distilled out without reflux, and the column top temperature reaches 226°C as a second distillation. to,
Distilled at a reflux ratio of 2 to diethylene glycol and methylna 7
After 32 minutes, 286.5 parts of azeotrope was distilled out. This azeotrope contains 192°3 parts of methylnaphthalene, ψ
Ta. Table 3 summarizes the above-mentioned series of distillation results.

As can be seen from Table 3, methylnaphthalene in the crude methylnaphthalene oil is an azeotrope of 224-226
In fact, 91.2% of the distillate was distilled out at °C.
Moreover, its purity is a good result of 96.0%. Further, the entire amount of naphthalene in the raw material crude methylnaphthalene oil is distilled out as an azeotrope in the fraction below 204°C, and its purity reaches about 90%.

Approximately 80% of the benzothiophene in the crude methylnaphthalene oil is distilled into the azeotrope of γ-butyrolactone and naphthalene, and the remaining 20% is heated at 205 to 223°C.
It is distilled out in the distillate. The entire amount of quinoline, dimethylnaphthalene, etc. remains as a fraction of 227° C. or higher that remains in the pot.

Example 2 0,492 (i bt times as much diethylene glycol) and 0°10 times as much water (0°124 times the cap amount as the azeotropic solvent) were added, and distillation was carried out using the distillation column of Example 1. The first distillation was carried out until the top temperature reached 204°C and the reflux ratio was 2.0. From the top of the column, 210.2 parts of an azeotrope of r-butyrolactone and naphthalene containing water was distilled. was distilled off.Naphthalene in the azeotrope was 60 parts.

Distilling 6.8 parts of a middle distillate with a tower top temperature of 205 to 223°C from the bottom oil after the first distillation without applying reflux,
As a second continuous distillation, distillation was carried out without applying reflux up to 226°C, and 283.8 parts of diethylene glycol and methylnaphthalene azeotrope containing water were distilled off. The azeotrope with methylnaphthalene 192
．． It contained 6 parts.

The above series of distillation results are shown in Table 4. As shown in this table, methylnaphthalene is 224
In fact, 93.5% of the raw material oil was distilled out in the azeotrope at ~226°C, and its purity was a good result of 95.4%.

Note that water was added and distilled in this example because water was added in the mixing tank (20) or solvent recovery tank (16) in the process shown in Figure 1 described above, and some of that water was passed through the pipe. Road (1
5) and is circulated to the distillation column (3), so this case is assumed. Based on repeated experiments by the present inventors, the amount of water added to the mixture of γ-lactones and polyalkylene glycols up to about 12.5% by weight does not interfere with the implementation of the method of the present invention. do not have.

As described above in detail, and in particular, as is clear by comparing Tables 3 and 4 with Table 2, according to the method of the present invention, naphthalene and methylnaphthalene in the raw material crude methylnaphthalene oil are As an azeotrope of r-lactones and dialkylene glycols, it can be concentrated in specific distillates, and quinoline and dimethylnaphthalene can be concentrated in specific fractions.
Since 0% remains in the bottom of the second distillation, the valuable compounds in the crude methylnaphthalene oil can be separated and recovered very advantageously.

1st bale Table 2 Table 3 Table 4

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a distillation facility suitable for carrying out the method of the present invention. 3: First distillation column, 8: Second distillation column, 13: Separation tank, 16
: Collection tank, 20: Mixing tank, 23: Decanter type centrifuge, 26: Dehydration tower Applicant: Sumikin Chemical Co., Ltd. Agent, Patent Attorney Mibuya Doishima (and 1 other person) Figure 1 Procedure amendment band (voluntary) 1978 2015 Patent Application No. MET ρ, (/l, No. 2 Title of the invention Method for separating the 7-talene fraction and the methylnaphthalene fraction from crude methylnaphthalene oil glass 3 Line to be amended Relationship to the case Patent Applicant address
1850 Minato, Wakayama City, Wakayama Prefecture Name: Sumikin Chemical Co., Ltd. 4th Director: Address: 550 Telephone: (06) 538-086
7 No. 6 The number of inventions does not increase due to book revision 7 Target of amendment 1v 11th column 8 "Detailed explanation of the invention" Contents of amendment 1) "Double amount" on page 11, line 12 of the specification "Weight times"
Correct. 2) “°cJ to r (”C) J” in Table 3 on page 16 of the same
Also, "W%" is corrected to "r(W%)". 3) "°C" in Table 4 on page 17 of the same page is r (°C) J
Then, ifc "W%" is corrected to "r(W%)". Above 662

Claims (1)

[Claims] Before crude methylnaphthalene, add 0.2 to 5 times the weight of r.
Lactones and polyalkylene glycols are added and subjected to a first distillation to distill off the γ-lactones and 7-talene azeotrope, and the bottom oil is subjected to a second distillation. A method for fractionating crude methylnaphthalene pre-glass 7talene and methylnaphthalene, which is characterized by distilling off an azeotrope of polyalkylene glycols and methylnaphthalene.