JPH01211536A - Isomerization of diethylbenzene - Google Patents

Abstract

PURPOSE:To obtain p-diethylbenzene at a relatively low temperature with little formation of by-products, by using a pentasil-group zeolite having a specific composition reusable as a catalyst and contacting the zeolite with diethylbenzene, thereby isomerizing the diethylbenzene. CONSTITUTION:A mixture of diethylbenzene isomers is made to contact with a crystalline aluminosilicate zeolite which is a pentasil-group zeolite having a composition of formula (M is cation; n is its atomic valence; at least 1/2 equivalent of M is type H and x is <=40) preferably at 150-280 deg.C to effect the isomerization of diethylbenzene and increase the concentration of p- diethylbenzene. The zeolite used as a catalyst has industrial advantage because it can be regenerated by a simple calcination and is semipermanently usable.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for isomerizing diethylbenzene.

<Prior Art> A mixture of diethylbenzene isomers can be obtained by distilling and separating by-products during the production of ethylbenzene, or by converting them into diethylbenzene by contacting them with ethylene under conditions for converting ethylbenzene. These diethylbenzene isomer mixtures are provided in thermodynamic equilibrium composition.

Therefore, in order to obtain the desired diethylbenzene isomer in high yield from a mixture of these diethylbenzene isomers, it is inevitable to carry out an isomerization reaction of diethylbenzene.

Generally, the isomerization reaction of alkylbenzene is carried out by a gas phase method because high temperature is kinetically advantageous (for example, Japanese Patent Publications No. 10066/1982, No. 44-14101, No. 45-21930, No. 46- In the gas phase isomerization reaction of dialkylbenzene, side reactions such as decomposition reaction and disproportionation reaction often occur, resulting in a decrease in the recovery rate of the target diethylbenzene isomer. do. In addition, the gas phase isomerization reaction has the disadvantage that coke tends to accumulate on the catalyst and the catalyst life is short.

Therefore, a method of isomerizing diethylbenzene in the liquid phase was investigated, and para-diethylbenzene was selectively adsorbed and separated from the diethylbenzene isomer mixture. JP-A-53-141 proposes a method for producing high-purity para-diethylbenzene by isomerizing it in the liquid phase as a catalyst, increasing the concentration of para-diethylbenzene, and selectively adsorbing and separating it again.
Publication No. 221).

<Problem to be solved by the invention> However, in the liquid phase isomerization reaction of dialkylbenzene using mordenite as a catalyst, it is difficult to adjust the acidic site,
It is necessary to support weak water components such as T, Ag, Cu, and Cr, introduce hydrogen gas, and use a diluent such as toluene in combination.

On the other hand, the high-silica 23M-5 type zeolite catalyst is generally recommended as a useful catalyst, but when applied to the isomerization of diethylbenzene, the initial activity is low and it cannot be converted to the para form unless the temperature is relatively high. There are drawbacks. The requirement for high temperatures is not only disadvantageous in terms of thermal energy, but also means an increase in undesirable by-products due to decomposition reactions, disproportionation reactions, and the like.

Therefore, it does not require operations such as adjusting the acidic point, supporting weak water components, introducing hydrogen gas, or using a diluent such as toluene, and is advantageous in terms of thermal energy, has a long catalyst life, and has stable isomerization. A catalyst that can contribute to the chemical reaction is desired.

Means for Solving the Problems> The present inventors focused on the catalytic activity of pentasil group I type zeolite in a relatively low temperature liquid phase reaction, and focused on the 5i02/A1203 molar ratio constituting the zeolite. As a result of intensive studies, it was surprisingly found that the zeolite has 5i
It has been found that the initial activity of diethylbenzene isomerization is high in a region where the 02/Aβ203 molar ratio is relatively low.

In particular, in the isomerization of diethylbenzene, we have discovered a catalyst that exhibits a much higher conversion rate than H-type mordenite, is relatively low-temperature, and produces less olefin by-products, which is an energy advantage. The invention has been completed.

That is, the present invention provides a method for isomerizing diethylbenzene by bringing diethylbenzene into contact with a crystalline aluminosilicate zeolite, wherein the zeolite has the following formula (
It is a pentasil group zeolite having the composition shown in I), (0,9±0.2 > M 2 /n: A 1
203...■:χ5i02:yH20 (here, M represents a cation, and n represents its valence, 0
At least 1/2 equivalent of M is of type 1 and χ is 4
0 or less) is the isomerization method of diethylbenzene.

In the method of the present invention, it is important to use a pentasil group zeolite having the composition represented by the above formula (I).

The zeolite used in the method of the present invention is a pentasil group zeolite whose main cavity entrance consists of a 10-membered oxygen ring.

As a specific example, for example, U.S. Patent No. 3.894.10
The composition and manufacturing method are described in the specification of No. 4, and also in Natu
re 20130 March 437 (197
Pentasil group ZS whose crystal structure is described in 8)
M-5 type zeolite, pentasil group ZSM-8 type zeolite described in British Patent No. 1,334.245, pentasil group ZSM-35 type zeolite described in Japanese Patent Publication No. 53-23280, Unexamined Japanese Patent Publication 1973
Examples thereof include the pentasil group zeolite Zeta 3 described in Japanese Patent Application Laid-open No. 58-91032, and the pentasil group 'rZ-01 type zeolite described in Japanese Patent Application Laid-open No. 58-91032.

It is important that the zeolite used in the present invention has a 5102/Al2O3 molar ratio of 40 or less. In other words, since the zeolite used in the present invention functions as a solid acid catalyst, if the 5102/Aj203 ratio is too high, the isomerization activity will be reduced. This is not preferable because the acid points are reduced. 5102/AJ!
When using a high-silica zeolite with a 203 molar ratio of more than 40 as a catalyst, sufficient catalytic activity cannot be achieved unless the isomerization reaction is performed at a relatively high temperature. This produces undesirable by-products and is also disadvantageous in terms of thermal energy. 5
The tO2/A203 molar ratio is preferably 18 or more; if the 3102/1J203 molar ratio is 18 or less, mordenite type or analcyme may be produced as a by-product during zeolite synthesis.

The presence of small amounts of these substances will not seriously impede the catalyst activity, but the presence of large amounts may cause problems such as a decrease in catalyst activity, a deterioration in the quality of ethylbenzene due to an increase in decomposition activity, and a reduction in catalyst valve life due to coking. give. 5i02/
The Aj203 molar ratio needs to be 40 or less, more preferably a lower molar ratio in the range of 18 to 30.

In the method of the present invention, the zeolite used is one in which 1/2 equivalent or more of the replaceable cations are of the If type. As is well known, H-type zeolite is obtained by exchanging a part of zeolite containing monovalent alkali metal ions with protons, or by ion-exchanging with ammonium cations which are converted into protons by calcination, and then calcination. It will be done. The exchange of cations in zeolite can be carried out by a known ion exchange method. For example, it can be easily exchanged by treating zeolite with an aqueous solution of an organic acid or ammonium salt. In the case of zeolite containing organic nitrogen-containing cations, it can be made into H-type zeolite by calcination, but if necessary, the alkali metal ions present in the zeolite can be further removed by 10 tons or ammonium by a known ion exchange method. It is possible to exchange with cations. The cations of the zeolite are influenced by the number of acid sites, but it is desirable that at least 1/2 equivalent or more, preferably 0.8 equivalent % or more, be of the H type.

The shape of the zeolite used in the present invention may be powdered or lumpy, but in order to avoid pressure loss industrially, 0.1 to 10-
A spherical molded article is preferably used. The shape can be freely selected depending on the device. Furthermore, it is also possible to add a binder such as alumina sol or clay if necessary during molding. The conversion to H-type may be performed either before or after molding.

In the isomerization reaction of diethylbenzene, the isomer mixture of diethylbenzene is usually heated at 100 to 350°C, preferably 1
The reaction, which can be carried out by contacting with the zeolite at a temperature of 50 to 280°C, can proceed in the liquid phase.

Therefore, the reaction pressure is preferably higher than the pressure at which the reaction solution can exist in a liquid phase under the reaction conditions used.

Reaction time factor W/F (ir, cat.

hr/g, IQ l supply liquid) (W: weight of contact a,
F: molar supply amount per hour) is usually 10 to 300
and preferably 30 to 200.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 5, Comparative Example 1 According to Example 1 of JP-A-58-91032, 310
2/AJ1203 molar ratio 19.22.26.36.40
and 50 zeolites were synthesized. This zeolite was treated in a batchwise manner three times at a solid-liquid ratio of 5 (ml/g) at 80°C for 1 hour with an aqueous solution containing 10 wt% ammonium chloride. Thereafter, water washing was performed 10 times at a pure water solid-liquid ratio of 5 at 80°C. After this process, 12
Dry at 0℃ overnight, bake at 500℃ for 3 hours, and obtain 810
Six types of catalysts having different 2/AJ203 molar ratios as shown in Table 2 were obtained. A feed liquid having the composition shown in Table 1 was subjected to an isomerization reaction using each of these catalysts, and the isomerization reaction was carried out under the reaction conditions shown in Table 2. As a result, a reaction mixture having the composition shown in Table 2 was obtained.

Examples 6-7, Comparative Examples 2-3 Zeolite catalysts synthesized according to Japanese Patent Publication No. 56-49850 were used. Since this zeolite contains organic nitrogen-containing cations in addition to sodium ions, it was calcined in advance at 550°C for 4 hours to partially form H-type, and then treated with ammonium chloride as in Examples 1 to 6. A catalyst was prepared by the same procedure, and an isomerization reaction was carried out in the same manner.

The results are shown in Table 2.

Examples 8-9 Unsubstituted Na cations of zeolite were ion-exchanged in a batch manner at 80°C for 1 hour at a solid-liquid ratio of 5 with an aqueous solution containing ammonium chloride corresponding to the amount of protons shown in Table 2 and the remaining equivalent being sodium nitrate. The catalyst was prepared by performing the same water washing and subsequent operations as in Examples 1 to 6, and the liquid phase isomerization reaction was carried out in the same manner.

The results are shown in Table 2.

Table 1 C9: Hydrocarbon having 9 or less carbon atoms P-DEB: Para-diethylbenzene m-DE
B: Meta-diethylbenzene o-DEB: Ortho-diethylbenzene C11: Hydrocarbon component having 11 or more carbon atoms Elementary value: Number of mg of bromine consumed per 100 g of sample Example 10 Completion example of JP-A-58-9103 specification 1, 810
A zeolite with a 2/AJI203 molar ratio of 21 was synthesized and molded into 10 to 16 meshes. This zeolite was treated in the same manner as in Examples 1 to 6 to obtain a catalyst. Table 3 shows the results of continuous operation of the liquid phase isomerization reaction of diethylbenzene for two months using this catalyst.

Note that the feed liquid composition is the same as in solid line examples 1 to 6.

Table 3 Comparative Examples 4 to 9 Using each of the catalysts shown in Table 4, the feed liquid having the composition shown in Table 1 was subjected to an isomerization reaction, and the isomerization reaction was performed under the reaction conditions shown in Table 2.

The results are shown in Table 4.

<Effects of the Invention> Thus, according to the method of the present invention, the concentration of para-diethylbenzene can be increased by subjecting a diethylbenzene isomer mixture that is poor in para-isomers to a liquid-phase isomerization reaction at a relatively low temperature and with little generation of by-products. , can contribute to the production of useful para-diethylbenzene. The zeolite catalyst can be regenerated by simple calcination and can be reused semi-permanently, making it extremely effective for industrial purposes.

Claims (1)

[Claims] A method for isomerizing diethylbenzene by bringing diethylbenzene into contact with a crystalline aluminosilicate zeolite, wherein the zeolite is a pentasil group zeolite (0.9±0) having a composition represented by the following formula (I). .2) M_2_/_n: Al_2O_3:
_xSiO_2:_yH_2O...(I) (Here, M represents a cation, and n represents its valence. At least 1/2 equivalent or more of M is H type, and x is 40 or less.) A method for isomerizing diethylbenzene, characterized by the following.