Method for isomerizing halogenated ethylbenzene

Abstract: A method for efficiently isomerizing a halogenated ethylbenzene characterized by bringing the same into contact with an acidic zeolite containing at least one metal selected among metals of Groups 7 to 11.

Description: The present invention relates to a method for isomerizing a halogenated ethylbenzene. In more detail, the present invention relates to a method for isomerizing a halogenated ethylbenzene by bringing the same into contact with an acidic zeolite, for obtaining a desired isomer. Background Arts Halogenated ethylbenzenes are known as important intermediate products of agricultural chemicals, etc. Especially m-chloroethylbenzene (hereinafter chloroethylbenzene is abbreviated as CEB) or m-bromoethylbenzene (hereinafter bromoethylbenzene is abbreviated as BEB) is expected as a raw material of agricultural chemicals with specific bioactivity as an isomer different from p- and o-isomers. CEB or BEB is mainly produced by aromatic ring chlorination or bromination reaction of ethylbenzene but since the reaction is very strong in ortho-orientation and para-orientation, the m-isomer can be produced only in a small amount. Therefore, CEB and BEB isomerization methods have an important technical significance. Conventionally known isomerization reactions for these compounds include a method of using aluminum chloride, etc. as a catalyst disclosed in Olah. G. A. J. Org. CHEM. 27, 3464 (1962), a method of using HF-BF 3 as a catalyst disclosed in Japanese Patent Laid-Open (Kokai) 46-11809, etc. Furthermore, Idar A. Acta Chemica Scandinavica B39,437 (1985) describes a chloroethylbenzene isomerization reaction using a mordenite-type zeolite. Furthermore, methods for isomerizing a halogenated toluene using a zeolite as a catalyst are disclosed in Japanese Patent Laid-Open (Kokai) Nos. 57-40428, 85330, 163327 and 7-309792. However, in the isomerization reactions of halogenated ethylbenzenes, it has been difficult to efficiently isomerize using conventional catalysts such as aluminum chloride and HF-BF 3 since the disproportionation reaction accompanying the deethylation reaction or intermolecular migration of ethyl groups is likely to occur, unlike the isomerization reactions of halogenated toluenes. Furthermore, because of such problems as the enormous use of catalyst for isomerization, corrosion of reactor and environmental issue in the treatment of waste catalyst, the conventional methods are not efficient. The isomerization reaction using a mordenite catalyst is less in these problems, but has such a disadvantage that since the catalyst life is short, the zeolite must be regenerated after hundreds of hours. So, a method for more efficiently obtaining a desired halogenated ethylbenzene is strongly demanded. Disclosure of the Invention The inventors studied intensively to solve the problem, and as a result, found that a halogenated ethylbenzene can be isomerized by bringing the same into contact with an acidic zeolite containing at least one metal selected among metals of Groups 7 to 11. Thus, the present invention has been completed. The present invention relates to a method of isomerizing a halogenated ethylbenzene, comprising the step of bringing the halogenated ethylbenzene into contact, in the presence of hydrogen, with an acidic zeolite containing at least one metal selected among the metals of Groups 7 to 11 for isomerizing it. In the present invention, it is preferable that the acidic zeolite is a faujasite-type, beta-type, mordenite-type or pentasil-type zeolite. Furthermore, it is preferable that the halogen of the halogenated ethylbenzene is chlorine or bromine. The zeolite used in the halogenated ethylbenzene isomerization method of the present invention can be an acidic zeolite, and it is preferable that the acidic zeolite is a faujasite-type, beta-type, mordenite-type or pentasil-type zeolite. A mordenite-type zeolite and pentasil-type zeolite are more preferable. A method for synthesizing a faujasite-type zeolite is disclosed, for example, in Japanese Patent Publication (Tokko) No. 52-15400, etc. Methods for synthesizing a beta-type zeolite are disclosed, for example, in US Patent No. 3,308,069 and Japanese Patent Publication (Tokko) 7-223989. Methods for synthesizing a mordenite-type zeolite are disclosed, for example, in Japanese Patent Publication (Tokko) No. 47-46677, Japanese Patent Laid-Open (Kokai) No. 55-26529 and Japanese Patent Publication (Tokko) No. 3-31006 Methods for synthesizing a pentasil-type zeolite are disclosed, for example, in US Patent Nos. 3,702 886 and 4,511,547 and Japanese Patent Publication (Tokko) No. 60-35284. When any of said zeolites is used for the isomerization method of the present invention, it is usually preferable to use the zeolite as a formed product, though not limited to it. The forming method is not especially limited, and can be, for example, rolling method, extrusion method or compression method, etc. For forming, if necessary, a binder such as alumina sol or clay, etc. can be added. The formed zeolite is usually calcined at 300 to 700°C, to be activated for use as a catalyst. When any of the zeolites is used for the isomerization method of the present invention, it is used as an acidic zeolite. An acidic zeolite can be obtained, as is well known, by replacing the cations in a zeolite by hydrogen ions or divalent or higher valent cations. It is especially preferable that the cations are replaced by hydrogen ions, since the activity is high. For replacing the cations in a zeolite by hydrogen ions, usually the zeolite is ion-exchanged directly by an acid aqueous solution, or the metal cations are ion-exchanged by ammonium ions, being followed by burning. If the zeolite contains organic nitrogen-containing ions beforehand, the organic nitrogen-containing cations can be decomposed by burning for conversion into hydrogen ions, to obtain an acidic zeolite. The halogenated ethylbenzene used in the method for isomerizing a halogenated ethylbenzene of the present invention can have the substituting halogen position at the ortho (o-), meta (m-) or para (p-) position to the ethyl group. It is preferable that the halogen is chlorine or bromine, and two or more may also substitute. The raw material for isomerization of the present invention can be a single isomer or a mixture of isomers. The halogenated ethylbenzenes which can be used include, for example; o-chloroethylbenzene, m-chloroethylbenzene, p-chloroethylbenzene, o-bromoethylbenzene, m-bromoethylbenzene, p-bromoethylbenzene, 1,3-dichloro-4-ethylbenzene, 1,3-dichloro-5-ethylbenzene, 1-chloro-2,4-diethyibenzene, 1-chloro-3,5-diethylbenzene, etc. The isomerization reaction of the present invention can be effected by the flow method or batch method. The reaction is effected with heating. The reaction temperature is usually 100 to 500°C, preferably 150 to 400°C. The reaction pressure is not especially limited, and can be set at atmospheric pressure to any desired pressure. The weight hourly space velocity (WHSV) as the raw material supply velocity per catalyst weight in the reaction is usually 0.01 to 50 hr -1 preferably 0.1 to 10 hr -1 . In the reaction of the present invention, a halogenated benzene and/or benzene can exist as a diluent together with the raw halogenated ethylbenzene. The dilution ratio is usually 1/20 - 20/1 (wt/wt), preferably 1/5 - 5/1 (wt/wt) as a ratio by weight to the halogenated ethylbenzene. The reaction of the present invention is effected in the presence of hydrogen. The amount of hydrogen supplied is usually 0.01 to 40 mol%, preferably 1 to 25 mol% based on the amount of the halogenated ethylbenzene. The isomerization catalyst of the present invention must contain at least one metal selected from the metals of Groups 7 to 11. The metals which can be used here include silver and copper of Group 11, rhenium of Group 7 and iron, nickel, platinum, etc. of Groups 8 to 10. Especially preferable is silver or rhenium. Methods for introducing the metal include impregnation method, ion exchange method, kneading method, etc. The metal supply sources which can be used include hydrochlorides, nitrates, oxides, etc. The amount of the metal introduced is 0.01 wt% to 5.0 wt% as metal atoms based on the total amount of the catalyst in every case. A preferable range is 0.01 wt% to 1.0 wt%. The presence of the diluent and hydrogen and the introduction of a metal into the catalyst are effective for preventing the loss of the halogenated ethylbenzene by side reactions such as disproportionation reaction and the degradation of catalyst activity. Examples The present invention will be described below in more detail with reference to examples and comparative examples, which are not intended to restrict the scope of the invention. The synthesis of zeolites and preparation of isomerizing catalysts in the following examples and comparative examples are described below. Synthesis of zeolite: A resin beaker was charged with 232.6 g of ion exchange water, and . 0.67 g of sodium hydroxide was added for sufficient dissolution. Then, 26.9 g of tetraethylammonium hydroxide (content 20 wt%, H 2 O = 80 wt%) was added, and in succession, 10. 2 g of sodium aluminate (Al 2 O 3 = 18.76 wt%, Na 2 O = 19.71 wt%, H 2 O= 61.53 wt%) was added. The mixture was sufficiently stirred, and finally 33 g of silicic acid powder(SiO 2 = 89.33 wt%, Na 2 O = 0.31 wt%, Al 2 O 3 = 0.34wt%, H 2 O = 10.02 wt%) was added, to prepare a slurry. The slurry was supplied into a 500 cc stainless steel autoclave, and reaction was effected with sufficient stirring at 160°C for 7 days, to produce a zeolite. The zeolite was sufficiently washed with distilled water and dried at 120°C overnight, to obtain a mordenite-type zeolite with a SiO 2 /Al 2 O 3 molar ratio of 20. Preparation of catalyst: Catalyst 1: Alumina sol (Al 2 O 3 = 10 wt%) was added by 15 parts by weight as alumina to 100 parts by weight of the zeolite 1, and the mixture was formed, dried at 120°C overnight and calcined at 500°C for 2 hours. The formed zeolite was ion-treated using 10 wt% ammonium chloride aqueous solution (solid liquid ratio 2.0 l/kg) at 85°C for 1 hour five times and sufficiently washed with distilled water. The formed zeolite was immersed in a rhenium peroxide (Re 2 O 7 ) aqueous solution with a solid liquid ratio of 2.0 1/kg adjusted to be 0.1 wt% as rhenium metal content, at room temperature for 4 hours, filtered, dried at 120°C overnight, and calcined at 550°C for 2 hours in air, to obtain a rhenium carried acidic mordenite-type zeolite catalyst. Example 1 A 10 ml stainless steel autoclave was charged with 2 g of a CEB isomer mixture (o- : m- : p- = 49.2 : 2.7: 48.1 (wt%)), and 1.0 g of the catalyst 1 was added. At room temperature and atmospheric pressure, 20 ml of hydrogen was supplied, and reaction was effected at 270°C for 2 hours. The amount of hydrogen supplied corresponded to 5.6 mol% of the CEB isomer mixture. After completion of reaction, the reaction product was analyzed by gas chromatography. The results are shown in Table 1. Example 2 Reaction was effected as described in Example 1, except that 2.5 g of a mixture consisting of the CEB isomer mixture used in Example 1 and CB (CEB/CB = 4 (wt/wt)) was used. The results are shown in Table 1. Example 3 Reaction was effected as described in Example 1, except that 3 g of a mixture consisting of the CEB isomer mixture used in Example 1 and CB (CEB/CB=2 (wt/wt)) was used. The results are shown in Table 1. Example Raw Material CEB composition, % o- m- p- 1 CEB 29.8 49.4 20.7 2 CEB/CB=4 31.5 47.2 21.3 3 CEB/CB=2 32.6 45.8 21.6 Example 4 A fixed bed flow reactor was used for isomerization reaction using the catalyst 1, by supplying hydrogen to a mixture consisting of a CEB isomer mixture (o- : m- : p- = 59.0 : 5.6 : 35.4 (wt%)) by 5.6 mol% based on the amount of the CEB isomer mixture. The results are shown in Table 2. Example 5 Reaction was effected as described in Example 4 except that a mixture consisting of a CEB isomer mixture (o- : m- : p- = 59.0 : 5.6 : 35.4 (wt%)) and CB (CEB/CB = 2 (wt/wt)) was used. The results are shown in Table 2. Comparative Example 1 Reaction was effected as described in Example 5 except that hydrogen was not supplied. The results are shown in Table 2. It can be seen that if no hydrogen exists, the catalyst activity declines 6% about 200 hours later. Comparative Example 2 Reaction was effected as described in Example 4, except that the catalyst preparation omitted introduction of rhenium. The results are shown in Table 2. It can be seen that an acidic mordenite-type zeolite catalyst without containing any metal declines very greatly in catalyst activity even if hydrogen exists. Example m-CEB composition, % CEB recovery rate, % with m-CEB/CEB=48 wt% Reaction time, hr 10 100 200 4 48.7 48.5 48.2 97.0 5 50.1 49.7 49.4 99.0 Comparative Example 1 48.6 45.4 42.6 99.0 Comparative Example 2 50.3 45.3 43.1 96.0 Reaction conditions: WHSV (CEB) = 1.3 hr -1 , reaction temperature 245°C, reaction pressure 4 MPa.

Claims: A method for isomerizing a halogenated ethylbenzene, comprising the step of bringing the halogenated ethylbenzene into contact, in the presence of hydrogen, with an acidic zeolite containing at least one metal selected among metals of Groups 7 to 11, for isomerization. A method for isomerizing a halogenated ethylbenzene, according to claim 1, wherein the halogen is chlorine and/or bromine. A method for isomerizing a halogenated ethylbenzene, according to claim 1 or claim 2, wherein the acidic zeolite is a faujasite-type, beta-type, mordenite-type or pentasil-type zeolite. A method for isomerizing a halogenated ethylbenzene, according to any one of claims 1 through 3, wherein when the halogenated ethylbenzene is brought into contact with the acidic zeolite, a halogenated benzene and/or benzene exists together. A method for isomerizing a halogenated ethylbenzene, according to any one of claims 1 through 4, wherein the isomerization reaction temperature is 150 to 400°C.

Inventors: MINOMIYA EIICHI, MIYATA SATORU, MINOMIYA, EIICHI, MIYATA, SATORU
Applicants: TORAY INDUSTRIES, TORAY INDUSTRIES, INC.
Application year: 1997
Main classification: C07C25
IPC codes: B01J29, C07C17