JPS63264537A - Selective separation of 2,6-dichlorotoluene - Google Patents

Abstract

PURPOSE:To selectively separate the titled substance useful as an intermediate for agriculatural chemicals, pharmaceuticals, dyes, etc., in high purity as a non-adsorbed component, by using an AlPO4-11 molecular sieve as an adsorbent and contacting a mixture of dichlorotoluene isomers with the adsorbent. CONSTITUTION:The titled substance can be selectively separated as a non- adsorbed component by carrying out adsorptive separation of a dichlorotoluene isomer mixture using an AlPO4-11 molecular sieve as an adsorbent. The AlPO4-11 molecular sieve is a crystalline aluminophosphate-type molecular sieve of formula (R is organic templete agent; x is 0-3 y is 0-500 is preferably used in the form of pellets of 0.1-10mm diameter. It is necessary to remove the crystallization water by heating the molecular sieve at 200-600 deg.C before using as an adsorbent. Other isomers separated as a firmly adsorbed components can be also effectively utilized.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an adsorbent for a method for selectively adsorption-separating 2,6-DCT with high purity from a dichlorotoluene (hereinafter abbreviated as DCT) isomer mixture. Regarding the provision of

2.6-DCT is an important synthetic intermediate for pharmaceuticals, pharmaceuticals, dyes, etc.

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

For this reason, it is industrially produced by dichlorination of p-)luenesulfonic acid followed by desulfonation.

In addition, a method for adsorption and separation of a DCT isomer mixture using a faujasite type zeolite is disclosed in U.S. Pat.
It is disclosed in No. 2.

(The problem that the invention is trying to solve)However, p
-) High purity 2.6- in the method from luenesulfonic acid
DCT is difficult to obtain and is not an economical method.

In addition, the latter adsorption separation technology using zeolite separates and recovers 2.6-DCT as an extract component from a DCT isomer mixture, but its adsorption power to faujasite-type zeolite is not satisfactory;
Although it is virtually impossible to separate and recover high-purity 2.6-DCT, it has drawbacks such as the fact that it cannot be separated and recovered unless it is adsorbed and separated in the presence of a benzene substituted compound.

AtPO4-11! Molecular sieves are known as isomerization or disproportionation catalysts, and examples of their use in adsorption separation include those applied to the separation of aliphatic hydrocarbons. There are no known examples.

(Means for Solving the Problem) In view of the current situation, the present inventors have conducted extensive research into a method for effectively adsorbing and separating and recovering highly pure 2.6-DCT from a mixture of DCT isomers. As a result, we have completed the present invention by discovering a specific adsorbent that can selectively separate 2.6-DCT as a non-adsorbed component.

That is, the present invention is a method for adsorbing and separating a DCT isomer mixture using a molecular sieve-based adsorbent, in which an AAPO, -11 type molecular sieve is used as an adsorbent, and a 2.6-D CT t- This is a selective separation method for 2,6-DCT, which is characterized by selectively separating non-adsorbed components.

ktPo4-11 type Molecuie used in the present invention? -While SEEP has 1,2,4-position trisubstituted benzenes as a strongly adsorbed component, 1,2,3-position trisubstituted benzenes such as 2,6-DCT, which is the object of the present invention, are strongly adsorbed components. is an adsorbent with a very specific property of not adsorbing.

The DCT isomer mixture used in the present invention is 2,3-DCT (containing 8 to 12%) obtained by chlorinating toluene, 2
．． 4-DCT (20-35%), 2,5-DCT (
25-55%), 2.6-DCT (5-25%), and 3.4-DCT (5-12%)
mixture of isomers, or. -2,5-DCT (5-20%) obtained by nuclear chlorination of chlorotoluene, 2.4-D
CT (10-25%), 2.5-DCT (3o-7
0%) and 2.6-DCT (5-30%).

The present invention preferably further rectifies the DCT isomer mixture to obtain 2,4-12.5- and 2.6-
- A fraction containing a component consisting of DCT and a boiling point of approximately 208°C
2,5- and/or 3°4-DC'r at ~209°C
This is a particularly effective method when separating and recovering 2.6-DCT from an isomer mixture fraction using an off-site DC that has been rectified into a fraction consisting of 2.6-DCT.

The PO4-11 type molecular sieve used in the present invention is a crystalline aluminophosphate type molecular sieve represented by the following general formula.

xR@Bu, .(1±α2)P2O,"i/H20 In the formula, R represents an organic template agent, 2 is within the range of 0 to 3, and V has a value of 0 to 500.

In addition, it is necessary to remove the water of crystallization in advance from baits that use molecular sheep as an adsorbent.

Usually, the water of crystallization content can be reduced at 100°C or higher, and most of the water of crystallization can be removed preferably by heating at 200 to 600°C.

The shape of the molecular sheep used in the present invention may be powder, crushed blocks, or a molded product obtained by compression molding, extrusion molding, marmerizer molding, or the like. Furthermore, it is also possible to add a binder such as alumina sol or bentonite if necessary during molding.

In the case of small-scale production, it is possible to use powder, but in order to avoid pressure loss, a pellet-shaped molded product with a diameter of 11 to 10 g is preferably used industrially.

The shape can be freely selected depending on the device.

The manufacturing method of AAPO,-11 and its composition are described in JP-A-57-77015, and the crystal structure is disclosed in J, Am,
Chem, 8oc, + Vol. 104, pp. 1146-1147
(1982), it is synthesized using an organic amine, and has a characteristic pore size (L of 61 nm) and a crystal structure of 10 or distorted 12 ring members.

The method of the present invention may be carried out by a patch method using a known fixed bed method or by a continuous method as a separation technique, but for small-scale applications, the patch method is preferable because the equipment is simple and continuous feeding is required. It is also advantageous because it is easy.

The separation technology of the present invention is basically carried out using one or more adsorption chambers filled with an adsorbent, and a cycle of adsorption, washing, desorption, and regeneration of the adsorbent.

That is, a DCT isomer mixture containing 2t6-DCT, which is the target substance to be separated, and at least one DCT isomer other than 2.5-DCT, is mixed with AtPO, -11 in an adsorption chamber.
By contacting with a type adsorbent, the target 21tS-D CT can be made into a non-adsorbed component, and other components can be strongly adsorbed and selectively separated.

The adsorption conditions of the present invention range from room temperature to about 400°C, preferably at 1
The temperature ranges from 50°C to 250°C.

The adsorption operation pressure ranges from atmospheric pressure to about 506/m, preferably from atmospheric pressure to about 30 (-), and pressures higher than about 50 (-) are not preferred because the cost increases.

In addition, DCT contains substances that do not have a negative effect on adsorption and desorption during adsorption.
It may also be added to the isomer mixture as a diluting solvent.

The method of desorption of the strongly adsorbed DCT isomer after adsorption separation of the present invention is not particularly limited, and includes (1) temperature difference desorption, (2) pressure desorption, (3) inert gas desorption, (4) water vapor desorption, (5
) A substitution/desorption method using a third component, or a combination of these methods can be considered.

The adsorption separation ability of the DCT isomer mixture of the AtPO4-11 type molecular sieve used in the present invention is, for example, 2.4
When a mixture consisting of -12,5- and 2.6-D CT is adsorbed and separated using AAPO4-11, 2.4-
DCT and 2.5-DCT are adsorbed and the desired 216
- DCT is not adsorbed but separated.

In other words, since the adsorption capacity of 2,4- and 2,5-D CT is extremely large, 2,6-D CT in the non-adsorbed liquid
The concentration changes ideally as shown in the breakthrough curve in Figure 1.

Therefore, the adsorption separation ability of human APO,-11 is 2,6-DCT in terms of purity up to the breakthrough point per 1f of molecular sheep.
It can be expressed in flow rate (% by weight).

Separation capacity ffl (wtl) person tPo, -11 amount (
? ) A: Total effluent volume up to breakthrough point B: Average 2.6-DCT iA degree (wtl) of effluent (
Examples) The present invention will be explained below with reference to Examples.

Reference Example 1 According to the method of Example 32 of JP-A-57-77015, the oxide molar ratio was α19 Pr2NH: 1.00At2
0°: AtPO, -11 type molecular sieve powder having a composition consisting of CL98P2O1:α48H,0 was obtained.

This was calcined at 500° C. for 5 hours and subjected to adsorption separation.

Obtained nine tPo4-11 type molecular sieve X-
The line analysis results are shown in JP-A No. 57-77015, soft AtP.
The results were consistent with those of O, -11.

Next, 70 parts by weight of this molecular sheep powder and bentonite [Tenryu 35 manufactured by Kanto Bentonite Mining Co., Ltd.
Sodium carboxymethyl cellulose (Tokyo Kasei Kogyo Co., Ltd. formula n = 500) per 0 parts by weight
[12 parts by weight and 100 parts by weight of water were added and mixed for about 1 hour using a stirrer.

After mixing, this mixture was put into an extruder (L5jm
The pellets were molded into pellets with a diameter of 100.degree. C., dried at 150.degree. C. for 5 hours, and then calcined at 500.degree. C. for 5 hours to obtain molded adsorbent products.

Example 1 Adsorbent molded product La6r of Reference Example 1 (Including AtPO, -11
A glass column with an inner diameter of 12 mm and a length of 29 cm was packed with DCT isomer mixture at a flow rate of 30 gI.
α05wj/at 200℃ under helium flow of t/mln
It was introduced at a rate of min.

The composition of the DCT isomer introduced at this time was 2.4-/
2,5-/2.6-DC'I'=22/42/3
The ratio was 6wt.

As a result of gas chromatography analysis of the composition of the non-adsorbed liquid flowing out from the column outlet, it was found that the original 2.6-DC
The T concentration was 100%, and the 2,6-DCTa degree gradually decreased, and after 25 minutes, the composition of the non-adsorbed liquid became the same as that of the introduced liquid, and a breakthrough was reached.

The total amount of non-adsorbed liquid flowing out until breakthrough was 0.8 f.

The DCT average composition of this total outflow is 2.4-/2.5-/2.6-DCT=6.6/1
2.6/8α8wt ratio.

Therefore, the amount of 2+6-D CT separation capacity is 5. Owt%
Met.

Comparative Examples 1 to 5 Adsorption operations were performed using the same apparatus and method as in Example 1, using the same DCT isomer mixed acid composition and changing the type of adsorbent.

The adsorbents used were Na-X type (Molecular Sieve 13X manufactured by Union Showa Co., Ltd.), Na-A type (Molecular Sieve 4A manufactured by Union Showa Co., Ltd.), Ni-L type (TSZ-500KOA manufactured by Toyo Soda Kogyo Co., Ltd.), and zeolite. were molded in the same manner as in Reference Example 1 and filled into each 212 glass column.

The DCT average composition of the non-adsorbed liquid that flowed out before breakthrough is shown in the table below.

Example 2 The adsorption temperature was changed using the same apparatus and method as in Example 1, and the 2.6-DCT separation force capacity was determined.

The results are shown in the table below.

Examples 3 to 4 Adsorption operations were carried out using the same apparatus and method as in Example 1 while changing the ratio of the introduced DCT isomer mixture.

The table below shows the composition of the introduced liquid and the average composition of the non-adsorbed liquid that flowed out before breakthrough.

(Effects of the Invention) Thus, according to the method of the present invention, not only can highly purified 2.6-DCT be selectively obtained from a DCT isomer mixture, but also other DCT isomers separated as strongly adsorbed components can be obtained. Each can be used effectively. In addition, in the adsorption separation of aromatic compounds, zeolite is not used (that is, it does not contain Si02 tetrahedron as an essential component).
It is noteworthy that the adsorption effect is equivalent to or higher than that of zeolite.

[Brief explanation of the drawing]

Figure 1 shows the amount of 2.6-DCT effluent until the AtPO, -11 type molecular sieve breaks through when a DCT isomer mixture is adsorbed and separated using an AtPO, -11 type molecular sieve. This is the breakthrough curve.

Claims (1)

[Claims] A method for adsorbing and separating a mixture of dichlorotoluene isomers, characterized in that an AlPO_4-11 type molecular sieve is used as an adsorbent, and 2,6-dichlorotoluene is selectively separated as a non-adsorbed component. Selective separation method for 6-dichlorotoluene.