JPH0446932B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for separating a specific dichlorocumene isomer from a dichlorocumene isomer mixture. In particular, 3,5-dichlorocumene (hereinafter referred to as
3,5-DCC) is an important compound in synthetic chemistry and is useful as an intermediate raw material for agricultural chemicals, medicines, dyes, etc. <Prior Art> Dichlorocumene is obtained by alkylating dichlorobenzene with propylene or isopropyl halide in the presence of a catalyst. especially,
3,5-DCC is m-dichlorobenzene (hereinafter referred to as
2, obtained by alkylating m-DCB)
It is obtained by isomerizing 4-dichlorocumene (hereinafter abbreviated as 2,4-DCC) in the presence of a catalyst. The obtained dichlorocumene isomer mixture consists mainly of 2,4-DCC and 3,5-DCC in thermodynamic equilibrium, unreacted m-DCB, and 2,5-DCC as a by-product.
-Dichlorocumene (hereinafter abbreviated as 2,5-DCC)
and dichlorodiisopropylbenzene (hereinafter referred to as
DCDIPB) and a catalyst.
After the catalyst is separated and removed from the mixture containing the dichlorocumene isomer, unreacted m-DCB and high-boiling point DCDIPB are first removed by a distillation method.
Since the boiling point difference between dichlorocumene isomers is small, they cannot be separated by distillation as they are. Therefore, conventionally,
The dichlorocumene isomer mixture was further subjected to an alkylation reaction to selectively convert 2,4-DCC into DCDIPB.
3,5-DCC is separated and recovered by a distillation method using the boiling point difference with 3,5-DCC (USP 4104315). 3 obtained in this way,
5-DCC still contains a small amount of unreacted 2,4-
Since DCC and by-product 2,5-DCC are present, the product is further subjected to a bromination reaction, and 3,5-DCC is selectively brominated and separated and purified by distillation (USP 4087473).
In addition, the recovered unreacted m-DCB and dialkyl compound DCDIPB are supplied to the first stage alkylation step, and a transalkyl reaction is carried out to cause 2,
4-Convert to DCC and reuse (USP4329524). <Problem to be solved by the invention> However, as mentioned above, alkylation (the first
stage) → isomerization → decatalyst → distillation → alkylation (second stage)
Separation and purification methods that involve repeating reaction and distillation, such as stage) → distillation → bromination → distillation, are disadvantageous not only in terms of industrial equipment but also in terms of energy. In addition, repeated reactions resulted in an increase in undesirable by-products, leaving problems in terms of both cost and quality. The present inventors have made extensive studies to solve these problems all at once, and as a result, have arrived at the present invention. <Means for Solving the Problems> The gist of the present invention is that when 3,5-dichlorocumene is adsorbed and separated from a dichlorocumene isomer mixture, a silica/alumina molar ratio of 2 or more and a silica/alumina molar ratio of 0.6 to 1.0 nm is used as an adsorbent. This is a method for separating 3,5-dichlorocumene characterized by using a zeolite having a pore size and using one or more selected from the group consisting of halogenated alkylbenzenes and halogenated benzenes as a desorbent. The present invention will be explained in detail below. The dichlorocumene isomer mixture in the present invention usually refers to a dichlorocumene isomer mixture mainly containing 2,4-DCC, 2,5-DCC and 3,5-DCC, and further contains by-products.
Also included are dichlorocumene isomer mixtures, including DCDIPB. In the present invention, a zeolite having a silica/alumina molar ratio of 2 or more and a pore diameter of 0.6 to 1.0 nm is used. Zeolite is a crystal in which SiO ₄ tetrahedrons and AlO ₄ tetrahedra share oxygen and are bonded in a three-dimensional network, and cavities and pores of various shapes are formed depending on the way they are bonded. The entrance to this cavity is called a pore and has a uniform effective diameter. This pore size can be slightly changed depending on the crystal structure of the zeolite and the type of cation corresponding to the negative charge of AlO ₄ . The zeolite used in the present invention needs to have a pore diameter of 0.6 to 1.0 nm.
If the pore diameter is less than 0.6 or greater than 1.0, dichlorocumene isomer cannot be adsorbed and separated. In addition, the zeolite used in the present invention is silica/
It is necessary that the alumina molar ratio is 2 or more, preferably 2 to 30. If the silica/alumina molar ratio is less than 2, the dichlorocumene isomer cannot be separated by adsorption. The zeolite used in the present invention is not particularly limited as long as it has a silica/alumina molar ratio of 2 or more and a pore diameter of 0.6 to 1.0 nm, and is preferably a haujasite-type zeolite, an L-type zeolite, and a beta-type zeolite. A zeolite selected from , mordenite-type zeolite, pentasil-type zeolite, omega-type zeolite, and offretite-type zeolite is used. More preferably, a zeolite selected from faujasite type zeolite, L type zeolite and beta type zeolite is used. Houjasite type zeolite is a crystalline aluminosilicate represented by the following formula. (0.9±0.2) M _2/o O: Al ₂ O ₃ : xSiO ₂ : yH ₂ O (where M represents a proton, ammonium ion, or monovalent, divalent, or trivalent metal cation, and n represents the atom In addition, y varies depending on the degree of hydration.) Houjasite type zeolite represented by the above formula is classified into X type and Y type, and the X type has x = 2.5 ± 0.5.
The Y type is represented by x=3 to 8. In other words, type has a pore size of 0.6-0.9 nm. L-type zeolite is a crystalline aluminosilicate represented by the following formula. (1.0±0.1) M _2/o O: Al ₂ O ₃ : (5-8) SiO ₂ :yH ₂ O (here, M represents a proton, an ammonium ion, or a monovalent, divalent, or trivalent metal cation) , n represents its valence, and y varies depending on the degree of hydration.) That is, L-type zeolite has a silica/alumina molar ratio of 5 to 8 and typically has a pore size of 0.71 nm. , depending on the type of cation, 0.6
It has a pore size of ~0.9 nm. Beta-type zeolite is a crystalline aluminosilicate zeolite represented by the following formula in its usage form. M _2/o O: Al ₂ O ₃ : (5-100) SiO ₂ :yH ₂ O (where M is a proton, ammonium ion or 1
Indicates a valent, divalent or trivalent metal cation, n
represents its valence. Moreover, y varies depending on the degree of hydration. ) That is, beta-type zeolite has a silica/alumina molar ratio of 5 to 100 and a pore diameter of 0.6 to 1.0 nm depending on the type of cation. Preferable cations of the zeolite used in the present invention include one or two metal ions selected from Groups A, B, and A of the periodic table, ammonium ions, protons, etc.
It is a cation that is more than a species. Preferred specific examples of these cations include lithium, sodium, potassium, magnesium, calcium,
Examples include strontium, barium, copper, silver, gold, ammonium, and protons. The ion exchange method for these cations can be carried out by conventional methods, and usually the 1 to be added to the zeolite is
This is carried out by contacting the zeolite with an aqueous solution of a soluble salt of the species or cations, or by contacting the zeolite with an aqueous ammonium salt solution that protonates the zeolite by calcining it. The zeolite adsorbent used in the present invention can be produced by any method, and can be obtained, for example, by the method described in JP-A-53-28126, JP-B-36-3675, or US Pat. No. 3,308,069. The technique for adsorbing and separating the dichlorocumene isomer mixture using the method of the present invention can be a conventional method, which may be a so-called chromatographic separation method, or a continuous adsorption method using a simulated moving bed. A separation method may also be used. Continuous adsorption separation technology using a simulated moving bed is carried out by continuously cycling the following basic operations: adsorption operation, concentration operation, desorption operation, and desorbent recovery operation. (1) Adsorption operation: The dichlorocumene isomer mixture is brought into contact with a zeolite adsorbent, the strongly adsorbed components are selectively adsorbed, and the weakly adsorbed components are recovered together with the desorbent described later as a roughinate stream. (2) Concentration operation: The adsorbent that has selectively adsorbed the strongly adsorbed components is brought into contact with a portion of the extract, which will be described later, to drive out the weakly adsorbed components remaining on the adsorbent and concentrate the strongly adsorbed components. be done. (3) Desorption operation: The adsorbent containing concentrated strongly adsorbed components is brought into contact with a desorbent, the strongly adsorbed components are expelled from the adsorbent, and the adsorbent is recovered together with the desorbent as an extract stream. (4) Desorbent recovery operation: The adsorbent that has substantially adsorbed only the desorbent is brought into contact with a portion of the roughinate stream, and a portion of the desorbent contained in the adsorbent is recovered as a desorbent recovery stream. . FIG. 1 schematically shows the adsorption separation operation using the simulated moving bed described above. Adsorption chambers 1 to 4 filled with adsorbent are continuously circulated and connected. 5 to 9 are respectively a desorbent supply line, an extract extraction line, an isomer mixture supply line,
These are the roughinate extraction line and the desorbent recovery line. Further, the valve 10 is closed. In the arrangement of the adsorption chambers shown in FIG. 1, adsorption chamber 1 performs a desorption operation, adsorption chamber 2 performs a concentration operation, 3 performs an adsorption operation, and 4 performs a desorbent recovery operation. The adsorption chamber 1 is moved by one adsorption chamber in the clockwise direction in FIG. 1 at regular time intervals. Therefore, the next arrangement state of the adsorption chamber is, for example, 1.
has moved to 4, 4 to 3, 3 to 2, and 2 to 1. As the developing agent or desorbing agent used during separation, one or more selected from the group consisting of halogenated alkylbenzenes and halogenated benzenes are used. Specific examples include chlorotoluene, dichlorobenzene, and dichlorotoluene. These may be used alone or as a mixture of two or more. Further, the isomers may be used alone or as a mixture of any isomers. As for the operating conditions for adsorption separation, the temperature is from room temperature to 350°C, preferably 50 to 250°C, and the pressure is from atmospheric pressure to 50 kg/cm ² ·G, preferably from atmospheric pressure to 40 kg/cm ² ·G. be. The adsorption separation according to the invention may be carried out in the gas or liquid phase, but is preferably carried out in the liquid phase in order to lower the operating temperature and to suppress undesirable side reactions of the raw material feed or desorbent. <Example> Next, the method of the present invention will be explained by giving examples. In the examples, the desorption characteristics of a desorbent (hereinafter abbreviated as DES) are expressed by the adsorption selectivity (α) with respect to a specific dichlorocumene isomer that exhibits the maximum adsorption of the dichlorocumene isomer. αDES/DCC = [Weight fraction of DES component/Weight fraction of DCC component] S/[Weight fraction of DES component/Weight fraction of DCC component]
L where DES denotes the desorbent and DCC denotes dichlorocumene which gives the maximum adsorption strength between the dichlorocumene isomers. S represents an adsorption phase, and L represents a liquid phase in equilibrium with the adsorption phase. The value of the adsorption selectivity (αDES/DCC) is preferably close to 1. When it is significantly greater than 1, the desorption strength is large and impairs the adsorption of dichlorocumene to be adsorbed next time, and when it is significantly less than 1, it becomes difficult to sufficiently desorb the adsorbed dichlorocumene. Furthermore, in order to show how the used desorbent affects the adsorption activity between dichlorocumene isomers, the adsorption selectivity between dichlorocumene isomers was also evaluated at the same time. The adsorption selectivity (α) between dichlorocumene isomers is expressed by the following formula. αA/B=[Weight fraction of A component/Weight fraction of B component] S/[Weight fraction of A component/Weight fraction of B component] L
Here, A and B represent any one of dichlorocumene isomers, S represents an adsorption phase, and L represents a liquid phase in equilibrium with the adsorption phase. The above adsorption selectivity (αA/B)
When the value of is larger than 1, the A component is selectively adsorbed, and when it is smaller than 1, the B component is selectively adsorbed. The adsorption separation of A and B becomes easier as the value of the adsorption selectivity (αA/B) is larger than 1 or smaller than 1 and closer to 0. Examples 1 to 10 A granulated product of Na-Y type Houjasite type zeolite having a silica/alumina molar ratio of 4.8 and pores of 0.74 nm was mixed with 0.15 equivalents of ammonium nitrate.
Using an aqueous solution containing 0.18 equivalents of potassium nitrate,
Ion exchange at 90℃ for 2 hours at a solid-liquid ratio of 5 (ml/g),
Repeat this 10 times and use a zeolite adsorbent (hereinafter referred to as
0.15H-K-Y zeolite) was obtained. After ion exchange, the zeolite granules were washed 10 times with pure water at 90°C at a solid-liquid ratio of 5 (ml/g) and dried at 120°C overnight. The zeolite adsorbent thus prepared was calcined at 500° C. for 2 hours and used immediately before measuring the adsorption selectivity between dichlorocumene isomers. Adsorption selectivity of dichlorocumene isomer and desorbent,
In order to measure the adsorption selectivity of dichlorocumene isomer, an autoclave with an internal volume of 5 ml was filled with 2 g of the above zeolite adsorbent, each desorbent shown in Table 1, and 2.2 ml of the following dichlorocumene isomer mixture.
The mixture was left at 150° C. for 0.5 hour with occasional stirring. The composition of the charged desorbent and dichlorocumene isomer mixture was as follows. Each desorbent shown in Table 1 50 (weight ratio) 2,4-DCC 15 2,5-DCC 15 3,5-DCC 20 Furthermore, as a reference material in gas chromatography analysis, dichlorocumene isomer mixture
20wt% n-nonane was charged at the same time. Under the above conditions, n-nonane is a material that is virtually inert with respect to the adsorption properties of the zeolite. The composition of the liquid phase mixture after contact with the adsorbent was analyzed by gas chromatography, and the adsorption selectivity between the desorbent and dichlorocumene isomers and the adsorption selectivity between dichlorocumene isomers were determined. The results are shown in Table 1.

【table】

[Table] Comparative Examples 1 to 13 Adsorption separation was carried out in the same manner as in Example 1, except that the desorbent was changed as shown in Table 2, and the adsorption selectivity was measured. The results are shown in Table 2.

[Table] Example 11 A dichlorocumene isomer mixture having the composition shown below was adsorbed and separated using the simulated moving bed apparatus shown in FIG. 3,5-DCC 63.3% 2,4-DCC 35.6% 2,5-DCC 0.7% DCDIPB 0.4% Each adsorption chamber 1 to 4 having an internal volume of about 40 ml was filled with K-Y zeolite. A dichlorotoluene mixture with the following composition was added as a desorbent from line 5 at 422 ml/hr.
The dichlorocumene isomer mixture was supplied from line 7 at a rate of 12.6 ml/hr. 2,4-dichlorotoluene 34% 2,5-dichlorotoluene 63% 2,6-dichlorotoluene 2% 2,3-dichlorotoluene 1% Extract flow from line 6 to 61.7 ml/hr
Extract the rough inate flow from line 8 to 66.9
ml/hr and the remaining fluid was withdrawn through line 9. Further, the flow of fluid between the adsorption chambers 1 and 4 was closed by a valve 10. At this time, adsorption chamber 1 was moved to 4, 4 to 3, 3 to 2, and 2 to 1 at the same time at intervals of about 150 seconds. The adsorption temperature was 170°C and the pressure was 20Kg. 3,5- in the dichlorocumene isomer mixture contained in the extract stream thus obtained.
The purity of DCC was 99.8% and the recovery rate was 91.7%. <Effects of the Invention> According to the present invention, 3,5-dichlorocumene can be separated and recovered with high purity and efficiency from a dichlorocumene isomer mixture using a zeolite adsorbent, and the effect of contributing to industry is extremely high. .

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an adsorption separation operation using a simulated moving bed, which is an embodiment of the application of the adsorption separation method of the present invention.

Claims (1)

[Claims] 1. When adsorbing and separating 3,5-dichlorocumene from a dichlorocumene isomer mixture, the adsorbent has a silica/alumina molar ratio of 2 or more and 0.6.
Separation of 3,5-dichlorocumene characterized by using zeolite having a pore size of ~1.0 nm and using one or more selected from the group consisting of halogenated alkylbenzenes and halogenated benzenes as a desorbent. Law.