JPS62149636A - Selective separation of dichlorotoluene - Google Patents

Abstract

PURPOSE:To readily improve the purity, by using mordenite type zeolite treated with an acid as an adsorbent in adsorbing and separating a dichlorotoluene isomeric mixture to obtain 2,6-dichlorotoluene which is a synthetic intermediate for agricultural chemicals, medicines, etc. CONSTITUTION:A dichlorotoluene isomeric mixture is subjected to adsorption and separation with mordenite type zeolite treated with an acid as an adsorbent, preferably by using a batchwise apparatus to selectively separate 2,6-di chlorotoluene as a nonadsorbed component. The mordenite zeolite to be used as the above-mentioned adsorbent is preferably a product of the AMAE Area, IWASE District, IWATE Prefecture and contains little impurities. The mordenite type zeolite is treated with the acid by a method for bringing into contact with an aqueous solution of a mineral acid, e.g. hydrochloric acid, etc., (the acid concentration is particularly preferably 0.5-5 N). The amount of the min eral acid to be used is 2-100ml, preferably 5-20ml, based on 1g zeolite to carry out the treatment. After the treatment with the acid, the zeolite is filtered, washed with water and heated to remove the water of crystallization for use.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to dichlorotoluene (hereinafter abbreviated as DCT)
A method for selectively adsorbing and separating 2,6-DCT with high purity from a mixture of isomers (relating to the provision of an adsorbent).

2.6-DCT is an important synthetic intermediate for agricultural chemicals, medicines, dyes, etc.

(Prior art) DCT isomer mixtures are synthesized by chlorination of toluene or monochlorotoluene, but since the boiling points of each isomer are very similar, it is very difficult to separate 2.6-DCT by rectification ( -It is difficult.

For this reason, industrially, it is produced by dichlorinating P-)luene sulfonic acid and then desulfonating it.

Furthermore, a method for adsorption and separation of a DCT isomer mixture using a faujasite type zeolite is disclosed in U.S. Pat.
No. 642 (=disclosed.

(Problems to be Solved by the Invention) However, in the method using P-)luenesulfonic acid, it is difficult to obtain highly pure 2,6-DCT and it is not an economical method. The latter adsorption separation technology using zeolite is
2,6-DCT is separated and recovered from the DCT isomer mixture as one extract, but the adsorption power to faujasite-type zeolite is not satisfactory, and high-purity 2,6-DCT is separated and recovered. It has drawbacks such as it is virtually impossible to separate or recover the adsorbed amount in the presence of the benzene-substituted compound.

The use of naturally produced zeolite, which is said to be buried in countless forests, is attracting worldwide attention, but it is well known that it has been used to separate gases such as nitrogen and oxygen as an adsorbent. However, there are no known examples of its use in adsorption separation of DCT isomers.

(Means for Solving the Problem) In view of the current situation, the present inventors have conducted intensive research on an industrially advantageous (double adsorption separation and recovery method) of highly pure 2.6-DCT from a DCT isomer mixture. As a result of repeated efforts, surprisingly, a specific adsorbent capable of selectively separating 2,6-DCT as a non-adsorbed component was discovered, and the present invention was completed.

That is, the present invention uses a zeolite adsorbent to
In a method for adsorbing and separating a T isomer mixture, acid-treated mordenite zeolite is used as an adsorbent, and 2
．． This is a method for selectively separating DCT, which is characterized by selectively separating 6-DCT as a non-adsorbed component.

The acid-treated mordenite type zeolite used in the present invention strongly adsorbs trisubstituted benzenes at the 1, 2, and =1 positions, whereas the 2,6-DCT, which is the object of the present invention,
Tri-substituted benzenes at the 1, 2.3-positions, whose representative components are 1, 2, 3-position trisubstituted benzenes, are adsorbents that have a very specific property of not adsorbing.

Therefore, by using the adsorbent of the present invention, it becomes possible to selectively (and efficiently separate) highly purified 2.6-DCT.

As the DCT isomer mixture used in the present invention, for example, 2,3-DCT (8
-12%), 2.4-DCT (20-35%),
2.5-DCT (25-55%), 2.6-DCT
(5-25%) and 3.4-DCT (5-12%
), or 2,3-DCT obtained by nuclear chlorination of O-chlorotoluene
(5-20%), 2.4-DCT (10-25%)
, 2.5-DCT (30-70%) and 2.6-D
CT (5-30%) may be mentioned as a mixture of DCT isomers with a neutral composition.

The present invention preferably further rectifies the DCT isomer mixture to obtain a fraction containing components consisting of 2.4-, 2.5- and 2.6-DCT with a boiling point of about 201°C and a fraction with a boiling point of about 20°C.
2.3- and/or 3.4-DCT at 8-209°C
This is a particularly effective method for separating and recovering 2,6-DCT from a fraction consisting of two crudely separated DCT isomer mixture fractions.

The mordenite-type zeolite used in the present invention includes synthetic mordenite containing mordenite as a main component and mordenite that is commonly naturally occurring. These are high-silica type zeolites represented by the following general formula, and the crystal structure is orthorhombic.

(Ca, K,..., Na2) [AdSis 0+
2 ] The composition ratio of the cations in the general formula 2.7H20 varies slightly depending on the region of production, and as is known, it can be easily exchanged with other cations.

Typical naturally occurring mordenite-type zeolites in Japan are produced in Tenei district, Iwase district, Fukushima prefecture, Yasukogashima district, Atami town, Adachi district, Fukushima prefecture, Iizaka district, Fukushima city, Fukushima prefecture, Omori town, Hiraka district, Akita prefecture, Sawaki district, Akita prefecture. Itado district, Minase Village, Ogatsu District, Miyagi Prefecture; Kawamoto District, Shiroishi City, Miyagi Prefecture.

Examples include Rikuzen Shirasawa district, Miyagi-machi, Miyagi-gun, Miyagi Prefecture, and Umaji district, Niman-cho, Shimane Prefecture. Naturally produced mordenite-type zeolite used in the present invention is not particularly limited in its production area, but among the above production areas, those produced in the Ten'ei area of Iwase District, Fukushima Prefecture, and the Rikuzen Shirasawa area of Miyagi Prefecture, which have few impurities such as clay, are particularly preferred. Preferably used.

These naturally produced mordenite-type zeolites and synthetic mordenite-type zeolites hardly achieve the effects of the present invention if they are used as they are, and it is necessary to perform an acid treatment operation as a pretreatment.

The acid treatment method is carried out by bringing the zeolite into contact with an aqueous mineral acid solution. The form of the zeolite to be treated can be either powder-like or block-like, but in order to increase the exchange rate, it is preferably used that has been pulverized into 10 to 100 menons.

There are no particular restrictions on the type of mineral acid used, but usually hydrochloric acid,
Nitric acid, hydrofluoric acid, hydrobromic acid, etc. are used, and hydrochloric acid, nitric acid, and hydrofluoric acid are particularly preferred.The concentration of the acid used is preferably 01 to 1o. , 2 (preferably 05 to 5).

The amount of mineral acid varies depending on the concentration of the mineral acid, but is usually 2 to 100 ml per gram of zeolite, preferably 5 to 20 ml. Further, this aqueous mineral acid solution may be treated as a single treatment solution, or may be divided into several parts for treatment. The method may be a nochi type or a continuous type.The temperature at this time is in the range of 0 to 100℃,
Varies depending on the type of mineral acid. For example, in the case of hydrofluoric acid, the temperature is preferably 0 to 50°C, and in the case of other mineral acids, the temperature is preferably 50 to 100°C.

The treatment time varies depending on the type of mineral acid, the amount, and the treatment temperature (2), but it is usually carried out for 0.5 to 48 hours.

After the acid treatment, it is necessary to filter the zeolite and wash it thoroughly with water. Furthermore, before using zeolite for adsorption separation, it is necessary to remove the water of crystallization in advance. Generally, the total water of crystallization can be reduced by heating at 100°C or higher, preferably by heating at 300 to 600°C (most of the water of crystallization can be removed).

It is not clear why the adsorption separation ability of DCT increases with acid treatment, but in the case of any mineral acid, the SiO□/k1203 ratio gradually increases as the acid concentration increases, and the hydrogen The proportion of ions also increases. This is one of the chemical components of zeolite.
Solica, which is a substance, hardly dissolves in acids, but the other chemical component, alumina, dissolves in acids (Si
It is presumed that the 02/A1203 ratio changes. In addition, acid treatment causes hydrogen ions to exchange with cations in the zeolite, resulting in a large number of hydrogen ions. It is thought that zeolites containing zeolites can be obtained.As a result of changes in the chemical composition of these zeolites (2), subtle changes in the zeolite pore size (2) occur,
It is thought that the effect was exhibited in the adsorption separation of DCT, which had little effect with untreated mordenite-type zeolite.

The acid-treated mordenite-type zeolite used in the present invention may be in the form of a powder, a crushed lump, or a molded product obtained by compression molding, extrusion molding, marmerizer molding, or the like. Also, alumina sol if necessary during molding.

It is also possible to add a binder such as solica or clay. On a small scale, it can be used in powder form; industrially, spherical molded products with a diameter of 0.1 to 10 mm are preferably used to avoid pressure loss. However, the shape of the device can be selected freely.

The adsorption separation method employed in the present invention may be either a batch method or a continuous method, but the batch method is preferably used because the apparatus is simpler and the operation is easier. This separation operation method is basically carried out as a cycle of adsorption, washing, adsorption, and regeneration as shown below, but the desorption methods include (but are not limited to) the following steam desorption, In addition, methods such as temperature difference desorption, pressure difference desorption, inert gas desorption, substitution desorption using a third component, or a combination of these methods may be employed.

(1) Adsorption step: The DCT isomer mixture as a raw material is brought into contact with an adsorbent, and the strongly adsorbed component 2.4-12.5-adsorption/
or 3.4- Adsorb DCT and remove 2 of the non-adsorbed components.
．． 6-DCT and/or 2.3-DCT can be selectively flushed out. For example, if the raw material is 2,4-12
．． When consisting of three components of 5- and 2.6-DCT,
High purity 2.6-DCT can be separated until the adsorbent is saturated (breakthrough) with strongly adsorbed components.

The adsorption step is carried out at room temperature to about 400°C, preferably from 150 to 25°C.
It operates at temperatures in the range of 0°C. A temperature of 400° C. or higher is undesirable because side reactions such as DCT disproportionation reaction occur.

The reaction pressure is about 50 Ky/i, preferably in the range of about 50 to 9/i from atmospheric pressure, preferably about 30 Ky/ad from atmospheric pressure.
A pressure higher than cn is not preferable because it increases the cost.

In addition, it may be added as a diluting solvent to the CT isomer mixture, which is a substance that does not have any effect during adsorption (double adsorption).

Any inert gas that can be used for cleaning the adsorbent may be any gas that does not participate in adsorption/desorption, but nitrogen,
Carbon dioxide, hydrogen, helium or lower hydrocarbon gases can be used, with nitrogen gas being particularly preferred.

(2) Cleaning process: By bringing an inert gas into contact with the adsorbent that has adsorbed strongly adsorbed components, the non-adsorbed components remaining between the adsorbents are removed with almost no desorption of the strongly adsorbed components. It can be pushed out. Since the concentration of non-adsorbed components contained in this effluent cannot reach the target (=), it is returned to the adsorption step (-) in (1).

The temperature for this washing operation is selected to be a temperature at which the adsorbent is not destroyed, but the same temperature as the adsorption conditions is usually preferred for industrial purposes.

The pressure can be selected in the range from reduced pressure to increased pressure, but preferably it is equal to or slightly higher than the adsorption conditions, and the pressure is carried out in the range from atmospheric pressure to 50 Kylad.

(3) Desorption step 2 The adsorbent saturated with strongly adsorbed components is desorbed by water vapor or a mixed gas of water vapor and inert gas.
2.4-12,5- and/or 3.4 of strongly adsorbed components
- DCT can be desorbed and flushed out with the water.

Although the water vapor used in the desorption step can be used alone, it is preferable to dilute it with an inert gas. i.e. 1
In order to shorten the time required for the subsequent regeneration and drying process of the adsorbent, it is preferable to use water vapor after diluting it with an inert gas to 5 to 50 mol %. The type of inert gas is preferably the same type as that used in the cleaning process.

The amount of water vapor is 05 to 30% relative to the amount of adsorbent used.
wt, %, preferably 1 to 10 wt0%.

The desorption temperature is 150-250℃, the same temperature condition as the adsorption process.
It is preferable to operate with A high temperature of 300° C. or higher in the presence of water vapor destroys the adsorbent, whereas a temperature of 100° C. or lower slows down the desorption rate, which is not preferable.

(4) Regeneration process: The adsorbent containing water is inert gas (=
Therefore, it is dried and regenerated.

When the strongly adsorbed component has finished flowing out from the desorption process, the introduction of water vapor into the adsorbent is stopped, and a dry inert gas is introduced to dry the adsorbent (-thus, it is regenerated and can be reused. There are no particular restrictions on the type of inert gas used, but
In terms of operation, it is preferable to use the same type as in the previous desorption step.

The regeneration temperature is selected within the range of 100' to 600°C, and industrially it is preferred to operate at 150° to 250°C.

The adsorption separation ability of the DCT isomer mixture of the acid-treated mordenite zeolite used in the method of the present invention is, for example, 2,
When a mixture of 4-12,5- and 2.6-DCT is adsorbed and separated using acid-treated mordenite zeolite, 2.4-DCT and 2,5-DCT are adsorbed, and the desired 2.6-DCT is adsorbed. DCT is not adsorbed but separated. That is, since the adsorption capacity of 2.4- and 2.5-DCT is large, the concentration of 2.6-DCT in the non-adsorbed liquid changes ideally as shown in the breakthrough curve of FIG.

Therefore, the adsorption separation ability of acid-treated mordenite-type zeolite is 2 in terms of chaos up to the breakthrough point per gram of zeolite.
．． It can be expressed as 6-DCT flux (wt, %).

A(g) x B (wt, %) 2.6, - DCT min)
Zeolite used: Suzume (, 9) Total effluent volume up to the breakthrough point (7) Industrial (=advantageous), as a result high purity 2.6-DCT can be obtained efficiently.

(Effects of the Invention) Thus, according to the method of the present invention, the DCT isomer mixture is adsorbed and separated using mordenite type zeolite, which is extremely inexpensive and easily available. - DCT can be obtained selectively.

Furthermore, acid-treated mordenite-type zeolite can be reused for a long period of time, and its industrial effects are extremely high.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Reference example 1 Journal of the Japan Society of Rock and Mineral Deposit Volume 74, pages 423-132 (
The zeolite was acid-treated according to the method described in (1979).

Mordenite-type zeolite from Tenei district, Iwase district, Fukushima prefecture (
20g of powder of Asahi Kasei Kogyo Co., Ltd., trade name: Moldenzeo) (hereinafter abbreviated as Moldenzeo) was dispersed in 200fnl of a 2N hydrochloric acid aqueous solution, and acid treatment was performed for 2 hours on a water bath at 97 to 98°C while stirring. Ta.

Next, after filtration, it was thoroughly washed with water and dried at 150°C for 5 hours.
Zeolite was calcined at 00° C. for 3 hours and treated with hydrochloric acid to obtain zeolite.

The chemical components of Mordenzeo used were as follows.

5in2: 72.60% MgO: 0.8
1% Az2o3: 12.90% Na2O:
0.65%Fe20s: 2.17%K
2O: 1.05% CaO: 2.5B% Reference Examples 2 to 5 The following acid-treated zeolites were obtained in the same manner as in Reference Example 1, except that the hydrochloric acid aqueous solution in Reference Example 1 was changed to the following mineral acid aqueous solution. .

The chemical composition of the mordenite type zeolite produced in Rikuzen Shirasawa district, Miyagi-machi, Miyagi-gun, Miyagi Prefecture used in Reference Example 5 was as follows.

5in2: 68.40% MgO: 0.
18%AJ20. : 12.17% Na2O
: 3.10% Fe2O3: 1.17%
K2O: 1.57%CaO: 1.44
% Examples 1 to 3 8.0 g of powdered mordenzeo treated with hydrochloric acid of Reference Example 1
was packed into a metal column with an inner diameter of 9.8 mm and a length of 16.3 mm, and the DCT isomer mixture was heated under a nitrogen pressure of 4 Kp/ci.
The composition of the ■π isomer mixture introduced at this time was 2.4-/2.5-/2.6-DCT=24.
The ratio was 1/43.7/32.2 wt.

As a result of analyzing the composition of the non-adsorbed liquid flowing out from the column outlet using a gas chromatograph, it was found that the original 2.6-DCT
The concentration was 100%, and the 2.6-DCT concentration gradually decreased, and after about 30 minutes (=the composition of the non-adsorbed liquid became the same as the composition of the introduced liquid and reached a breakthrough).

The total amount of non-adsorbed liquid effluent up to breakthrough was 0.229.

The DCT average composition of this total effluent is 2.4-/2,5-/2,6-DCT=13.6/
The ratio was 25.4/61.0 wt.

Therefore, the 2.6-DCT separation capacity is 1.68 wt,%
becomes.

Next, nitrogen gas was added at 3 Ky/d at the same temperature.
0 minutes, and the attached DCT isomer mixture was drained and washed. The amount of emissions is 1. It was II.

Furthermore, a mixed gas of water vapor (mole fraction 0.33) and nitrogen (mole fraction 0.67) was added to the same column at the same temperature (6K).
Under pressure of p/d, 60 fil! /min. The adsorbed 2,4-12.5-DCT was desorbed and flowed out together with water, and the outflow of DCT was completed after about 30 minutes.

The total amount of DCT effluent due to desorption is 0.29.9, and the DCT average composition of this total effluent is 2.4-/Z5-/2.6-DCT=31.8157.
The ratio was 8/10.4 wt.

Furthermore, at the same temperature and under a pressure of 6 K9/cd, nitrogen gas was introduced at a rate of 40 frLl/min for 2 hours to dry and regenerate the adsorbent.

After completion of the regeneration, the above-mentioned adsorption-washing-adsorption-regeneration steps were considered as one cycle, and a total of three cycles including this Example 1 were repeated. The results are shown in the table below. Furthermore, as a result of X-ray analysis of the crystallinity of the zeolite after repeating this cycle three times,
No destruction of crystal structure was observed.

Examples 4 to 7 Adsorption operations were performed using the same equipment and method as in Example 1, except that the hydrochloric acid-treated mordenzeo used in Example 1 was replaced with acid-treated naturally produced mordenite-type zeolite in Reference Examples 2 to 5. . The DCT average composition of the non-adsorbed liquid that flowed out before breakthrough is shown in the following table.

Comparative Examples 1 to 2 The hydrochloric acid-treated mordenzeo used in Example 1 was replaced with untreated naturally produced mordenite-type zeolite calcined at 500°C for 3 hours (the same equipment and method as in Example 1 except that the two were changed). A second adsorption operation was performed.

The DCT average composition of the non-adsorbed liquid that flowed out before breakthrough is shown in the table below (
As shown in Figure 2, the effect of adsorption separation of 2.6-DCT is that the 2.6-DCT composition of the introduced raw material DCT isomer mixture is 32.2W.
t.

The duck content changed to about 37wt0% (not too much, which was bad).

Examples 6 to 7 The same apparatus and method as in Example 1 were used (the adsorption operation was carried out by changing the adsorption temperature). (8) Monochlorotoluene and toluene by-products were contained.

Examples 8 to 11 (Apparatus and method similar to Example 1) Adsorption operation was performed by changing the ratio of the introduced DCT heterogeneous mixture. The composition of the introduced liquid and the average composition of the non-adsorbed liquid that flowed out before breakthrough are shown in the table below.

Reference Examples 6 to 9 Reference Example 10 Molden Zeo was manufactured by Two-Tone in the United States (product name:
In place of the synthetic mordenite type zeolite manufactured by Zeolon 900 Na) and Toyo Soda Kogyo Co., Ltd. (trade name: TSZ-62ONAA), synthetic zeolites of Tables 6 to 90 of Reference Examples treated with various mineral acids in the same manner as Reference Example 1 were used. Obtained.

Examples 12 to 14 The hydrochloric acid-treated Mordenzeo used in Example 1 was used in Reference Examples 6 to 14.
The adsorption operation was carried out using the same apparatus and method as in Example 1, except that step 9 was replaced with acid-treated synthetic mordenite-type zeolite. The DCT average composition of the non-adsorbed liquid that flowed out before breakthrough is shown in the following table.

Comparative Examples 3 to 4 The adsorption operation was carried out using the same equipment and method as in Example 1, except that the hydrochloric acid-treated mordenzeo used in Example 1 was replaced with untreated synthetic mordenite-type zeolite calcined at 500°C for 3 hours. went. The average DCT composition of the non-adsorbed liquid that flowed out before breakthrough is shown in the following table (2), but the adsorption separation effect of 2.6-DCT is similar to that of untreated naturally produced mordenite-type zeolite, and the DCT isomer of the introduced raw material is 2.6 of the mixture
The DCT composition changed only from 32.2 wt.% to about 38 wt.%, which was poor.

Examples 16 to 19 Example 1 was carried out by replacing the hydrochloric acid-treated mordenzeo used in Example 1 with the synthetic mordenite-type zeolite treated with acid in Reference Example 6, and further changing the ratio of the introduced DCT isomer mixture.
The same apparatus and method (adsorption operation was performed from the second stage).The composition of the introduced liquid and the average composition of the non-adsorbed liquid that flowed out before breakthrough are shown in Table C below.

[Brief explanation of drawings]

Figure 1 shows the breakthrough curve of the adsorbent using a 2.6-DCT effluent stream until the adsorbent breaks through when a DCT isomer mixture is adsorbed and separated using acid-treated naturally produced mordenite-type zeolite. . (Al indicates the adsorption process, (Bl cleaning process, (C) desorption process, and (DJ indicates the adsorption separation process in which one cycle is the regeneration process.) Figure 1 Outflow C1C process λ amount

Claims (1)

[Claims] In a method of adsorbing and separating a dichlorotoluene isomer mixture using a zeolite-based adsorbent, acid-treated mordenite-type zeolite is used as the adsorbent, and 2,6-dichlorotoluene is selectively separated as a non-adsorbed component. Characteristic selective separation method of dichlorotoluene.