JPH0446933B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a halogenated benzene derivative by adsorption separation. <Prior Art> Typical halogenated benzene derivatives include dichlorobenzene, chlorotoluene, dichlorotoluene, dichlorocumene, and the like. These are important as synthetic intermediates for agricultural chemicals and medicines. Halogenated benzene derivatives are generally obtained as an isomer mixture by halogenation of benzene, alkylbenzene, or halogenated alkylbenzene, and are produced by separating the desired isomer from this isomer mixture. Isomers can be separated by distillation, crystallization, adsorption, etc. However, because the difference in boiling point and freezing point is generally small, it is often difficult to apply conventional distillation separation methods and crystallization separation methods. On the other hand, in recent years, a method of isomerizing dialkylbenzene represented by xylene using a catalyst (USP 4409413, etc.) and a method of adsorbing and separating a dialkylbenzene isomer mixture using a zeolite adsorbent (Japanese Patent Publication No. 15681/1983, Japanese Patent Publication No. 15681/1986)
38202, etc.) were developed. According to these methods, the desired isomer can be separated with considerably high purity. Furthermore, by passing the remaining components after separation to the isomerization step, isomerizing them, and then separating the desired isomer again in the adsorption separation step, it is possible to ultimately produce only the desired isomer. <Problems to be Solved by the Invention> However, when the above-mentioned production method using isomerization and adsorption separation is applied to the production of halogenated benzene derivatives, the zeolite adsorbent gradually deteriorates, resulting in a decrease in productivity. . <Means and effects for solving the problem> As a result of intensive studies on the causes of deterioration of zeolite adsorbents, the present inventors found that trace amounts of hydrogen halide contained in the raw materials and produced as a by-product during the reaction, as well as trace amounts of It was discovered that moisture is the cause of deterioration.
Furthermore, the present inventors have found that the more strongly a zeolite adsorbs water, such as a phosiasite-type zeolite, the greater the degree of deterioration of the adsorbent. Moreover, it has been found that when water and hydrogen halide coexist in high concentrations in the adsorption raw material, the zeolite adsorbent is destroyed and the adsorption capacity is significantly reduced. The present inventors have also discovered that by removing these to a substantially negligible extent, deterioration of the adsorbent can be significantly suppressed. One object of the present invention is to prevent deterioration of the zeolite adsorbent when a mixture of isomers of a halogenated benzene derivative containing hydrogen halide is brought into contact with a zeolite adsorbent to selectively separate the desired isomer. The object of the present invention is to provide a method that allows industrial separation for a long period of time without reducing productivity. Another object of the present invention is to provide a method for separating a desired isomer with high purity by contacting a mixture of isomers of a halogenated benzene derivative containing hydrogen halide with a zeolite adsorbent. These objectives are to subject the isomer mixture of halogenated benzene derivatives containing hydrogen halide generated in the isomerization process of halogenated benzene derivatives to distillation treatment or dispersion treatment to halogenate the isomer mixture without separating the isomer mixture. Production of a halogenated benzene derivative, which comprises removing hydrogen halide from a benzene derivative isomer mixture and then contacting it with a zeolite adsorbent to selectively separate the target isomer of the halogenated benzene derivative. achieved by law. For example, the halogenated benzene derivative used as a raw material in the present invention has the following general formula () (In the formula, X ¹ represents a halogen atom, X ² and X ³ each represent a halogen atom or a hydrogen atom, and R represents a lower alkyl group or a halogen atom). Here, R is a lower alkyl group, and represents an alkyl group having 1 to 4 carbon atoms. Specific examples of R include methyl group, ethyl group, n
-propyl group, iso-propyl group, n-butyl group,
Examples include sec-butyl group and tert-butyl group. Further, when X ¹ , X ² , X ³ or R represents a halogen atom, the types of halogen atoms may be the same or different. Specifically, the halogen atom is a chlorine atom, a bromine atom, an iodine atom, etc., and preferably a chlorine atom or a bromine atom. Specific examples of halogenated benzene derivatives include dichlorobenzene, chlorotoluene, dichlorotoluene, trichlorobenzene, trichlorotoluene, tetrachlorobenzene, dibromobenzene,
Bromotoluene, dibromotoluene, dichlorobromobenzene, tribromobenzene, dibromochlorobenzene, chlorcumene, dichlorocumene,
Examples include trichlorcumene, dibromcumene, and bromcumene. Among these, especially dichlorobenzene, chlorotoluene, dichlorotoluene,
Dichlorocumene can be preferably used. These halogenated benzene derivatives are supplied as a mixture of isomers. The isomer mixture of halogenated benzene derivatives used as a raw material in the present invention is produced by an isomerization reaction of benzene, alkylbenzene, or halogenated alkylbenzene, and contains a trace amount of hydrogen halide produced as a by-product during the reaction. . Further, such isomer mixtures of halogenated benzene derivatives usually originally contain a trace amount of water. The halogenation reaction or isomerization reaction can be carried out by a conventional method. For example, the isomerization reaction can be carried out by bringing an isomer mixture raw material of a halogenated benzene derivative into contact with a catalyst. Here, aluminum chloride or zeolite can be used as the catalyst, and specific examples of the zeolite catalyst include phodiasite-type zeolite, pentasil-type zeolite, mordenite-type zeolite, and the like. When a zeolite catalyst is used in the isomerization reaction, for example,
The isomerization reaction can be carried out according to Publication No. 144330. That is, the weight hourly space velocity (WHSV) at a reaction temperature of 200-550℃, preferably 250-500℃
The conditions are 0.05 to 30 Hr ^-1 , preferably 0.1 to 20 Hr ^-1 , and any of gas phase reaction, liquid phase reaction, fixed bed, moving bed, and fluidized bed methods can be used. In the present invention, it is important to remove hydrogen halide by subjecting the isomer mixture of halogenated benzene derivatives containing hydrogen halide to distillation treatment or diffusion treatment. In the absorption method using an alkaline aqueous solution, which is a general method for removing hydrogen halides, contact between the isomer mixture of the halogenated benzene derivative and water is unavoidable, so a small amount of water is dissolved in the isomer mixture of the halogenated benzene derivative. This is not preferable because it causes deterioration of the zeolite adsorbent used in the next step. By performing distillation treatment or diffusion treatment, it is possible to remove hydrogen halide while avoiding contact with moisture. The isomer mixture of halogenated benzene derivatives to be subjected to distillation treatment or dispersion treatment is not particularly limited, and may be, for example, the reaction mixture as it is, or an extract, distillate, etc. from the isomerization reaction mixture. Good too. In the present invention, the diffusion treatment refers to removing volatile components from the reaction solution by blowing an inert gas such as nitrogen into a raw material containing hydrogen halide. Further, the distillation treatment refers to distillation performed by a conventional method. The distillation treatment or the dispersion treatment can be carried out in either a plate column or a packed column. The operating pressure may be normal pressure, reduced pressure, or increased pressure. In distillation treatment or diffusion treatment, the hydrogen halide concentration in the reaction solution is usually
Continue until the concentration is 10ppm or less, preferably 1ppm or less. In the present invention, water present in the raw material can be simultaneously removed by distillation treatment or diffusion treatment, and deterioration of the zeolite adsorbent can be prevented. The distillation treatment or the dispersion treatment is carried out until the concentration of water in the reaction solution is usually 10 ppm or less, preferably 1 ppm or less. In addition, when side reactions such as disproportionation, demethylation, and dehalogenation reactions occur during the isomerization reaction of halogenated benzene derivatives, demethylated and/or dehalogenated low-boiling components may be produced as byproducts. generate. For example, in the isomerization product of chlorotoluene, trace amounts of toluene and chlorobenzene are produced as by-products. Although such low-boiling components often do not deteriorate the zeolite adsorbent,
If high purity of the product is required, removal of low boiling components is necessary. By carrying out distillation treatment or diffusion treatment, low-boiling components can also be removed at the same time. If the specific volatility of the low-boiling component is low, a multi-stage distillation device or a diffusion device may be used. After the distillation treatment or the diffusion treatment, the isomer mixture of the halogenated benzene derivative is supplied to an adsorption separation step. In the adsorption separation step, target isomers of the halogenated benzene derivative are selectively separated. Zeolite can be used as an adsorbent. Zeolite adsorbents are not particularly limited, but those that are significantly degraded by hydrogen halides and moisture show particularly good results in the action of the present invention. Specifically, for example, phosiasite type zeolites such as X type and Y type, ZSM-5
The effect of the present invention is remarkable when pentasil type zeolite, mordenite type zeolite, L type zeolite, beta type zeolite, etc. are used. As the desorbent, aromatic compounds such as toluene and xylene can be used. Conventional methods and conditions can be used for adsorption and desorption.
For example, adsorption and desorption can be carried out by the method disclosed in Japanese Patent Publication No. 63-24981. The isomer mixture after the target substance has been adsorbed is subjected to an isomerization reaction again, and the concentration of the target isomer can be increased to an equilibrium ratio. Through such recycling, the desired product can be industrially advantageously produced. <Example> Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Sodium silicate 135g, Al ₂ (SO ₄ ) ₃・18H ₂ O 8.6g,
15 g n-propylamine, 11.2 g H ₂ SO ₄ and water
An aqueous mixture consisting of 400 g was kept at 155° C. for 72 hours for crystallization to synthesize zeolite ZSM-5 powder with a SiO ₂ /Al ₂ O ₃ ratio of 45.5 mol/mol. this
ZSM-5 powder was ion-exchanged five times using a 10wt% ammonium chloride aqueous solution (solid-liquid ratio 2.0/Kg, at about 90℃), thoroughly washed with water, dried at 120℃ for 15 hours, and then air-exchanged at 600℃ for 2 hours. Baked inside to produce acid form
A ZSM-5 catalyst was obtained. Using the obtained acid type ZSM-5 catalyst, an isomerization reaction of o-dichlorobenzene was carried out in the liquid phase using a fixed bed flow reactor to obtain a dichlorobenzene isomer mixture containing hydrogen chloride. . O used for reaction
- Dichlorobenzene was previously dehydrated using a molecular sieve. The isomerization reaction conditions are shown below. WHSV = 4.5Hr ^-1 Reaction temperature = 300℃ Reaction pressure = 30Kg/cm ² -G The composition of the isomer mixture after the reaction is o-dichlorobenzene: m-dichlorobenzene: p-dichlorobenzene = 58: 27:15, and the hydrogen chloride concentration is
The concentration was 120ppm, and the water was 10ppm. The concentration of chlorobenzene, a by-product, was 0.09 wt%. The resulting reaction mixture was distilled at a pressure of 200 mmHg for about 30 minutes to remove hydrogen chloride and water from the reaction mixture. Hydrogen chloride in the reaction mixture after distillation is
1ppm, water was 6ppm, and low boiling components were 0.01wt%. m-dichlorobenzene was adsorbed and separated from this isomer mixture using a simulated moving bed apparatus shown in FIG. FIG. 1 will be briefly explained. Adsorption chambers 1 to 12 with an internal volume of approximately 13ml are filled with _0.75LiO2 .
It was filled with an X-type zeolite adsorbent substituted with Li represented by 0.25Na ₂ O.Al _{2 O} 3.2.5SiO ₂ . line 1
Toluene, which is a desorbent, is supplied from line 15 at a rate of 300 ml/Hr, and the above isomer mixture is supplied from line 15 at a rate of 17 ml/Hr.
Supplied in Hr. An extract stream was removed from line 14 at 74 ml/hr, a roughinate stream was removed from line 16 at 29 ml/hr, and the remaining fluid was removed from line 17. Further, the flow of fluid between the adsorption chambers 1 and 12 is closed by a valve 18. At this time, adsorption chamber 1 was moved to 12, 11 to 10, 8 to 7, and 5 to 4 simultaneously at approximately 150 second intervals (the other adsorption chambers were also moved upward by one adsorption chamber at the same time). . The adsorption temperature was 130°C. Two hours after the start of operation, the purity of m-dichlorobenzene in the dichlorobenzene mixture contained in the raffinate stream was 99.5%, and the recovery of m-dichlorobenzene was 70%. Furthermore, the raffinate stream and the extract stream were each stored, and their compositions were analyzed after 100 hours. The purity of m-dichlorobenzene in the dichlorobenzene mixture in the raffinate stream was 99.5%, and the recovery rate was 68%. Example 2 Instead of distilling the reaction mixture in Example 1, _N2 gas was added at a rate of about 11/min for about 1 hour at room temperature and normal pressure.
Example 1 except hydrogen chloride and water were diffused and removed by bubbling through the reaction mixture.
The isomerization reaction and adsorption separation were carried out in the same manner as above. Hydrogen chloride in the reaction mixture after dissipation is 8 ppm,
The water content was 7 ppm, and the low boiling point component was 0.08 wt%. The purity of m-dichlorobenzene in the roughinate stream 2 hours after the start of adsorption separation was 99.6%,
The recovery rate of m-dichlorobenzene was 68%.
Furthermore, after 48 hours, the purity of m-dichlorobenzene in the raffinate stream was 99.6%, and the recovery rate was 67%.
It was %. Comparative Example 1 The isomerization reaction and adsorption separation were carried out in the same manner as in Example 1, except that the reaction mixture was not distilled and was directly supplied to the adsorption separation step. Hydrogen chloride in the reaction mixture is 120 ppm, water is
The content of low-boiling components was 10 ppm and 0.09 wt%. The purity of m-dichlorobenzene in the raffinate stream 2 hours after the start of adsorption separation was 99.5%, and the recovery rate was 99.5%.
It was 68%. After a further 48 hours, the purity of m-dichlorobenzene in the raffinate stream was 91.3%, and the recovery rate was 60%. Example 3 In Example 1, 2,5-dichlorotoluene was used instead of o-dichlorobenzene, and X-type zeolite substituted with Ag was substituted with X-type zeolite substituted with Li.
The isomerization reaction, distillation treatment, and adsorption separation were carried out in the same manner as in Example 1 except that type zeolite was used, and 2,6-dichlorotoluene was separated. The results are shown in Table 1. The results obtained without distillation treatment are also shown in Table 1 as Comparative Example 2. Example 4 Example 1 except that 2,4-dichlorocumene was used instead of o-dichlorobenzene in Example 1, and Y-type zeolite substituted with K was used instead of X-type zeolite substituted with Li. Perform the isomerization reaction, distillation treatment, and adsorption separation in the same manner as
3,5-dichlorocumene was separated. Table 1 shows the results.
Shown below. In addition, the results without distillation treatment are shown in Comparative Example 3.
Also shown in Table 1.

[Table] <Effects of the Invention> According to the present invention, it is possible to prevent the deterioration of the zeolite adsorbent, to make it possible to separate the desired isomer industrially for a long period of time without reducing productivity, and to obtain the desired isomer with high purity. can be separated by

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing continuous adsorption separation of dichlorobenzene isomers using a simulated moving bed in Example 1.

Claims (1)

[Claims] 1 The isomer mixture of the halogenated benzene derivative containing hydrogen halide produced in the isomerization process of the halogenated benzene derivative is subjected to distillation treatment or diffusion treatment to obtain the halogenated benzene derivative without separating the isomer mixture. 1. A method for producing a halogenated benzene derivative, which comprises removing hydrogen halide from an isomer mixture and then contacting the mixture with a zeolite adsorbent to selectively separate target isomers of the halogenated benzene derivative.