JPS58210857A - Catalyst composition and isomerizing method of xylenes - Google Patents

Abstract

PURPOSE:To isomerize xylenes in a high isomerization yield, by bringing a raw material mixture contg. xylene isomer into vapor contact with a Pd modified catalyst compsn. contg. crystalline alumina silicate zeolite subjected to ion exchanging with alkaline earth metals. CONSTITUTION:The crystalline alumino silicate zeolite expressed by the formula I (the formula is expressed in the form of oxide in an anhydrous state. M; >=1 kind of cations of alkaline earth metals, N; >=1 kind of cations of valancy (n) except alkaline earth metals, x; 0.1-1, y; 15-200) and Pd of the under-mentioned amt. are used as the essential active components of this catalyst compsn.: The amt. coresponding to 0.1-1,000 R expressed by the formula II (m1, m2, m3, m4 are respectively the mol. wts. of MO, N2/NO, Al2O3, SiO2, m; the atomic weight of Pd, W; weight % of Pd based on the weight of the above-described zeolite). This catalyst compsn. is formulated to provide 0.1-0.9 1, 3, 5-trimethyl benzene adsorptivity and >=60 ethyl benzene/xylene reaction selectivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel crystalline aluminosilicate zeolite-containing catalyst composition and a method for isomerizing xylenes using the same as a catalyst. More specifically, the present invention provides a novel catalyst composition containing a crystalline aluminosilicate zeolite ion-exchanged with at least one alkaline earth metal and modified with palladium, and a catalyst composition using the same for the isomerization of xylenes. This invention relates to a method for isomerizing xylenes used as a catalyst in this process.

In this specification, unless otherwise specified, crystalline aluminosilicate zeolite will be abbreviated as p and simply referred to as "zeolite."

Both natural and synthetic zeolites contain Na+K or hydrogen ions! ! Contains cations, 5 as king
It has a three-dimensional network structure composed of i04 and AlO4, and has an S1 atom and AI! What is an atom? ! ! It is characterized by a highly ordered tetrahedral structure cross-linked through elementary atoms. This zeolite has many pores of uniform size. It is used as a molecular node, and is also used in bed desks as a catalytic acid Fi support in various fields of chemical synthesis.

In particular, synthetic zeolite L is extremely homogeneous, has high purity, and has excellent properties. Therefore, many synthetic zeolites and methods for producing the same have been proposed.

For example, if the molar ratio of 8 i02/A/203 is at least 10
The so-called zeolites with high silica content have high stability and unique acidity, and are suitable for selective adsorption, cracking, and hydrocracking, for example.

It has high activity as a catalyst for hydrocarbon conversion such as isomerization and alkylation. Many zeolites with a high silica content have been proposed, mainly 28M zeolites.

In particular, research has focused on the improvement and development of zeolite-containing catalysts used in xylenes isomerization methods, as well as improvements in isomerization conditions, and many proposals have been made in this regard.

Namely, methods include methods of changing the shape and structure of the zeolite catalyst itself; methods of modifying the zeolite catalyst by subjecting it to physical treatment, such as heat treatment; methods of chemically modifying the zeolite catalyst by adding various components to it; A lot of research has been done. For example, a method for treating Y-type zeolite with heated steam to improve catalyst activity and stabilization (U.S. Pat. No. 388
7630), offretite (0ffretite)
) to improve the decomposition activity of ethylbenzene by supporting MoO2 (see US Pat. No. 3,848,009).

SI02/A/2011 Method for reducing and stabilizing the activity of zeolite as 201500 or more (% opening 56
43219), a method of weakening the acidic point of the catalyst by continuously introducing basic nitrogen into the feed (Japanese Patent Laid-Open No. 5
4-19921).

However, some of the xylene isomerization catalysts proposed so far have (a) excellent activity for xylene isomerization reactions and (b) undesirable side reactions (e.g. nuclear hydrogenation of benzene rings, hydrogenolysis). Most catalysts have been found that fully satisfy the two conflicting conditions (a) and (b): extremely low catalytic reactions (demethylation, demethylation, especially disproportionation, transalkylation reactions, etc.). I can't.

In particular, when isomerizing a xylene isomer mixture containing ethylbenzene, it is desirable to de-ethylate ethylbenzene together with the isomerization reaction of xylenes, and several methods have been proposed for this purpose. For example, the above-described method is disclosed in US Pat. No. 4,098,836 and US Pat.
However, in the conventionally proposed method, in addition to the main reactions of xylene isomerization and ethylbenzene deethylation reaction, the benzene ring is hydrogenated.

Undesirable side reactions such as disproportionation of xylene and transalkylation of xylenes and ethylbenzene occur, and losses of xylenes are unavoidable.

For example, the three US patents described above disclose a method for isomerizing a xylene isomer mixture containing ethylbenzene using a ZSM series zeolite modified with nickel or a platinum group metal such as platinum or palladium. There is.

However, in the case of ZSM-12 zeolite catalyst modified with nickel (Ni content of 2% by weight or more),
Under so-called severe reaction conditions where the conversion rate of ethylbenzene is high, the demethylation reaction of xylene is promoted and xylene loss increases.

Therefore, it has been considered advantageous industrially to use a ZSM-W zeolite catalyst modified with a platinum group metal that causes less demethylation reaction. However, for example, ZSM-type zeolite modified with palladium has excellent isomerization properties for xylenes and also has an excellent ability to selectively deethylate the ethyl group of ethylbenzene, but on the other hand,
Palladium itself has benzene ring hydrogenation activity, and the hydrogenation reaction is more likely to occur as the temperature decreases from thermodynamic equilibrium, thereby increasing the production of naphthenes. As a result, xylene loss will increase, so
ZSM-type zeolite catalysts modified with palladium must be used industrially at high temperatures. Furthermore, the temperature required for the isomerization reaction depends on the space velocity, but generally a temperature of about 300 to 340°C is sufficient; higher temperatures do not improve isomerization, but instead induce intermolecular rearrangements in which xylene is returned. This significantly accelerates undesirable reactions such as disproportionation, trans, alkylation, etc., and increases xylene loss.

In order to avoid such undesirable reactions as much as possible, we raised the space velocity based on the zeolite catalyst, raised the optimum temperature for isomerization higher than that in conventional methods, and suppressed xylene loss caused by disproportionation. A method has also been proposed in which deethylation is promoted while
(see issue).

However, this method has a major industrial disadvantage in that it is difficult to maintain the isomerization rate at a high level, and the catalyst activity deteriorates significantly due to the high temperature and high space velocity.

Therefore, the main purpose of the invention is to develop a new and improved xylene isomerization method that does not have the above-mentioned drawbacks that occur when xylenes are isomerized using a ZSM-based zeolite catalyst containing radium. The objective is to provide a method for

Another object of the present invention is that Z8 containing palladium
While maintaining the excellent xylene isomerization ability and selective deethylation ability of the M-based zeolite catalyst, the intermolecular rearrangement reaction of methyl groups, which is the drawback of this catalyst, i.e., xylene disproportionation reaction. Another object of the present invention is to provide a new and improved palladium-containing ZSM-based zeolite catalyst composition in which the transalkylation reaction between xylene and ethylbenzene is significantly suppressed.

Other objects and advantages of the present invention will become apparent from the detailed description provided below.

In order to achieve these objectives, the present inventors conducted intensive research on the characteristics of zeolite catalysts and their improvement, and as a result, they incorporated at least one kind of alkaline earth metal into crystalline aluminosilicate zeolite using an ion exchange method.
Furthermore, the inventors have discovered that a catalyst composition in which palladium is added to the zeolite-containing catalyst composition is extremely effective, leading to the present invention.

That is, according to the present invention, (1) Represented by the general formula (+)? Crystalline aluminosilicate zeolite and the following formula (If) R-□×-・・・・・・・・・(II)
Contains palladium as the main active ingredient in an amount corresponding to R expressed as 0.1 to 1000, (2) 1,
3.5-1 Remethylbenzene adsorption rate (RA) is 0.1~
(3) (Ethylbenzene/xylene) reaction selectivity (
RB) of at least 60; and contacting the catalyst composition in the gas phase with a raw material mixture containing xylene isomers, at least one of which has a thermodynamic equilibrium concentration or less. A characterized method for isomerizing xylenes is provided.

The present invention will be explained in more detail below.

The novel catalyst composition of the present invention is such that a part or most of all cation sites of the crystalline aluminosilicate zeolite contained therein are occupied by at least one alkaline earth metal, and the alkaline earth metal It is characterized by containing an amount of palladium within a certain range relative to the amount of palladium.

That is, the catalyst composition of the present invention includes (a) a zeolite into which alkaline earth metal cations are introduced into the cation sites;
(b) contains radium and (c) a carrier in an amount within a certain range relative to the amount of cations of the alkaline earth metal.

The crystalline aluminosilicate zeolite that serves as the catalyst used in the present invention mainly contains hydrogen ions or hydrogen ion precursors such as ammonium ions at the cation site, and has a silica/alumina molar ratio of 15 to 20.
0, preferably 30 to 100, is used. That is, in the present invention, a so-called high-silica-containing zeolite, which has a relatively high silica content compared to aluminum, is used as a catalyst paste. Many zeolites have been proposed that have a relatively high silica content compared to alumina, and the silica/alumina molar ratio is 2000.
Even among high-silica-containing zeolites with extremely high silica contents, the 7 lyca/alumina ratio is relatively low, and therefore, the zeolite is characterized in that it uses a zeolite with a relatively high acid activity derived from the alumina component.

In the present invention, any known high silica-containing zeolite can be used as long as the silica/alumina molar ratio falls within the above range.

Representative examples of crystalline aluminosilicate, ie, zeolite, as a catalyst paste that can be used in the present invention include:
For example, Mobil Oil Corporation (Mobi
l Oil 0orporation, New York
k.

Various 28M-based zeolites developed by N., Y., USA) and Imperial Chemical Industries (I.
imperial chemical industry
Ltd., Zeta-based zeolite developed in England,
Alternatively, the present inventors discovered and already proposed TP-1 zeolite as a high silica zeolite (% opening 54-
137500), among which the former Z
SM-based zeolites are preferred.

Examples of ZSM-based zeolites include ZSM-5 (see US Pat. No. 3,702,886), ZSM-11
(See U.S. Pat. No. 3,709,979), ZSM
-12 (see US Pat. No. 3,832,449).

ZSM-35 (see US Pat. No. 401,624.5).

ZSM-38 (see US Pat. No. 4,046,859), etc. Zeta-based zeolites include Zeta 1 (see Japanese Patent Application Laid-Open No. 51-67299), Zeta 3 (see Japanese Patent Application Laid-Open No. 51-67298). ).

Among the above-mentioned zeolites, ZSM-5, ZSM-11, ZSM-12゜ZS are used as catalyst pastes in the present invention.
M-35 and ZSM-38 are preferred, and it has been found that particularly excellent effects can be achieved when ZSM-5 type zeolite is used.

These zeolites are generally available in a form containing an alkali metal at the cation site immediately after their synthesis. In the present invention, by ion-exchanging such zeolite by a conventional method, a part or most of the cation sites are occupied by cations of at least 41 types of metals selected from the group of alkaline earth metals. , the remaining cation sites are occupied by at least one cation selected from hydrogen ions, ammonium ions as hydrogen precursors, and metal cations other than alkaline earth metals, and the composition is oxidized in an anhydrous state. The above general formula (+) expressed in the form of a thing
It is indicated by.

In the above formula (H, X is an indicator of the amount of at least 1 m of metal cations selected from alkaline earth metals bound to the zeolite, and (1-x)l'j is the alkaline earth metal At least one indicator excluding

Zeolite, which is a crystalline aluminosilicate, is generally made up of a combination of silica tetrahedron and alumina tetrahedron, and the charge of this alumina tetrahedron is 1. It is thought that it has a neutralized structure due to its presence. Therefore, theoretically, the amount of cations is equimolar to that of alumina, and the above formula (D) represents such a state.

However, in reality, zeolite in its synthesized state usually contains cation precursors that cannot be removed by normal washing, and analytical data of synthesized zeolite indicates that the amount of cations is In many cases, the amount exceeds the equimolar amount of alumina. However, such an excess of cationic precursor (eg, organic ammonium compound, etc.) is typically used during the preparation of the catalyst composition, e.g. m under high temperature above 'O
It can be substantially removed from the crystal structure of the zeolite by exposure to a cumulative atmosphere.

Thus, the zeolite in the catalyst composition of the present invention is
It means that the amount of cations is substantially equimolar to that of alumina, and the above formula (ri) represents such a state.

In the present invention, beryllium, magnesium, calcium, strontium and barium are preferred as alkaline earth metals introduced into cation sites by ion exchange.

The amount of the alkaline earth metal introduced into the cation site by ion exchange is such that X in the above formula (+) is from 0.1 to
1, preferably 0.3 to 0.
It is desirable that it be in the range of 8.

If the value of X is even smaller than 0.1, the effect of the present invention described later cannot be obtained, and if the value of Mukuro X exceeds 0.8,
There is a tendency that the xylene isomerization reaction, which is the main reaction in the present invention, can also be suppressed.

Further, y, which is an index of violet containing violet, is preferably in the range of 15 to 200, preferably 30 to 100, in order to achieve the effects of the present invention.

Further, as N in the above formula (+), a hydrogen ion relative is particularly suitable as an ion in which an ammonium ion, which is a hydrogen ion precursor, exhibits monoisomerization activity.

Thus, the catalyst composition of the present invention uses a zeolite represented by the above formula (1) that has been ion-exchanged with at least one alkaline earth metal as one component at an exchange rate within a certain range. However, as another important component, with respect to the amount of at least one alkaline earth metal contained in the zeolite,
It contains palladium in an amount corresponding to R represented by the formula (L') from 0.1 to 1000.

Conventionally, a ZSM type zeolite catalyst #l modified only with palladium has been proposed.

However, although this catalyst has an excellent ability to isomerize xylenes and selectively deethylate the ethyl group of ethylbenzene, palladium itself has no hydrogenation activity toward the benzene ring. Moreover, due to thermodynamic equilibrium, the hydrogenation reaction occurs more easily as the temperature decreases, which leads to an increase in the production of 7T/s and a loss of xylenes. . Therefore, industrial use of ZSM type zeolite modified only with palladium requires a reaction under high temperature conditions, and although the formation of naphthenes can be suppressed under such severe conditions, xylene is involved. The disproportionation and transalkyl reactions will be significantly accelerated, and the loss of xylenes will increase even in low-temperature reactions.

Therefore, in the catalyst composition of the present invention, a part or most of the cation sites in the zeolite are occupied by cations of at least one kind of alkaline earth metal, and as a result, the hydrogenation reaction to benzene rings is inhibited. Even when the reaction temperature is raised in order to suppress the reaction, the undesirable reaction such as the intermolecular rearrangement reaction of methyl groups as described above is suppressed to an extremely low level (!-).

In the present invention, the preferable amount of palladium contained in the skeleton catalyst composition can be determined based on the correlation with ion exchange i(χ) by at least one alkaline earth metal of the zeolite component. For the purpose of non-invention, the amount of palladium in the catalyst composition may be an amount sufficient to sufficiently promote the deethyl reaction.

However, the ion exchange rate (,
), it is preferable to select low-temperature reaction conditions in order to suppress the disproportionation reaction and transalkyl reaction involving xylene; quantity is required. or,
When the ion exchange rate (X) is high, it is preferable to select reaction conditions at higher temperatures in order to maintain isomerization activity, etc. At that time, it is preferable to select reaction conditions at higher temperatures, suppressing the deposition of carbonaceous substances on the catalyst and increasing the reaction rate. For the purpose of long-term stabilization, a slightly higher concentration of palladium is desired.

Thus, the preferable amount of radium in the nuclear catalyst composition is correlated with the amount of alkaline earth metal introduced into the cation site of the zeolite.
．． It is selected in the range of 1 to 1000, preferably in the range of 1 to 200. A smaller R of the catalyst composition than 0.1 indicates a high radium content, which may result in excessively harsh reaction conditions being required to completely suppress the hydrogenation reaction. Become. On the other hand, when R exceeds 1000, the palladium content decreases, which tends to reduce the deethyl activity, which is an important characteristic of the catalyst composition.

Such catalyst composition further comprises: 1,3.5-)')
It is characterized by the characteristic values of methylbenzene adsorption (RA) and U (ethylbenzene/xylene) reaction selectivity (RB).

That is, the 1.3.5-)IJ methylbenzene adsorption rate ()LA) of the catalyst composition is measured by the method described below, and in the catalyst composition of the present invention, it is 0.1 to 0.
It is preferably in the range of 9.

This adsorption rate (RA) is 1.3.5-tIJ after a certain period of time.
It is determined by measuring the amount of methylbenzene adsorbed, and the larger this value is, the faster the molecular diffusion rate into the pores is. In the present invention, it is preferable that the adsorption rate (R, +u is infertile to some extent,
An extremely small RA tends to suppress the diffusion of any molecules, so it is considered that RA=0.2-09 is a more preferable range.

Also (ethylbenzene/xylene) reaction selectivity (RB)
is measured by the method described below, and represents the ratio of the reaction activities of ethylbenzene and xylene in the pores of the catalyst composition, and is the ratio of the reaction activities of ethylbenzene and xylene in the pores of the catalyst composition, and is
For type ZSM-5, it is usually 10 to 15, and for a catalyst composition containing palladium in addition to the zeolite, the b5o is high, but for the catalyst composition used in the invention, the RB is At least 60. Preferably, it is 80, and it is shown that RB is preferably within this range in the xylene isomerization reaction of a raw material composition containing ethylbenzene.

Next, the above-mentioned 1.3.5-)limethylbenzene adsorption rate (RA) which represents the characteristics of the catalyst composition in this @Shizu
and (ethylbenzene/xylene) reaction selectivity (RB)
The measurement method will be explained in detail.

a) 1,3.5) Limethylbenzene adsorption rate (R
Measurement method of A) The RA is expressed as the ratio of the 1.3.5-IJ methylbenzene adsorption amount of the catalyst composition to the 1.3.5-IJ methylbenzene adsorption amount after one adsorption time of the reference zeolite. defined.

The standard zeolite used is the so-called H-type ZSM-5 in which 90% or more, preferably 95% or more of the cation sites based on alumina are occupied by protons. The adsorption amount of 1.3.5-)limethylbenzene per unit weight of zeolite for the reference zeolite or the catalyst composition is determined by measuring a certain amount of the zeolite or catalyst composition calcined at 450°C for 8 hours in an electric furnace. Weigh, then 2
The weighed zeolite or catalyst composition is held in a saturated gas atmosphere of methylbenzene at 5°C and 30±5°C for a period of less than 20 minutes; -) the zeolite or catalyst composition in the absence of remethylbenzene at 25 °C and 30 °C for 511 h.
9, it is weighed after being held for the same time as above, and the measurement can be made from the difference in weight before and after adsorption. From the adsorption amount Cvc, ) of the reference zeolite and the adsorption amount (■, ) of the catalyst composition, RA is obtained as Vs/v (, ) determined in this manner.

Here, if the adsorption time is longer than 20 minutes, the types of cations present in the zeolite structure.

Regardless of the amount, 1,3,5-IJ methylbenzene is sufficiently diffused, and in some cases, no significant difference in adsorption amount is observed between H-type Z8M-5 and the catalyst composition. That is, it appears that the type or amount of cation controls the rate of diffusion of adsorbed molecules into the pores. Therefore, R
In measuring A, the adsorption time is preferably as short as 20 minutes, and more preferably as short as 10 minutes.

b) (ethylbenzene/xylene) reaction selectivity (RB)
Measuring method B: A catalyst composition containing 50% by weight of γ-alumina and molded into 10 to 20 mesh pellets is calcined in an electric furnace at 450°C for 8 hours, and then its constant weight is fixed. A bed reactor was filled with an aromatic hydrocarbon composition of ethylbenzene/xylene = zs/ss (weight ratio) under -atmosphere conditions at WH8V = 4 HR-'' (
hydrogen/the hydrocarbon=
It is measured by flowing 1/1 hydrogen.

The catalyst bed temperature is adjusted so that the ethylbenzene conversion rate, which will be described later, is 30%. The R13 can be calculated as the ratio of the ethylbenzene conversion to the xylene conversion.

W) ISV, ethylbenzene conversion rate.

Xylene conversion, rate and BBt are values defined by the linear equation.

Ethylbenzene conversion (IJ (%) = xylene conversion rate (%) = RB - ethylbenzene conversion rate / xylene conversion iE) Thus, in the present invention, ion exchange is carried out using at least one alkaline earth metal at a certain range of exchange rates. zeolite and palladium in the range as described above;
Catalyst compositions characterized by A and rtB are used, and as will be described later, this enables the intermolecular rearrangement reaction of methyl groups, which is a side reaction in the isomerization reaction of xylenes, that is, the disproportionation reaction of silene and While exhibiting the effect of suppressing the transalkyl reaction between xylene and ethylbenzene, it promptly promotes the isomerization reaction of xylene and the deethylation reaction of ethylbenzene without substantially causing a hydrogenation reaction.

That is, by performing ion exchange with at least 19 alkaline earth metals, the pore diameter of the pores in the zeolite is reduced to l1.
1#! By optimizing the acid strength of the active site, the isomerization reaction of xylenes can be sufficiently achieved.
On the other hand, the present invention has revealed that it is possible to selectively promote the deethyl reaction by suppressing the intermolecular rearrangement reaction of methyl groups and further optimizing the amount of radium. .

The catalyst composition of the present invention contains synthetic or natural refractory inorganic oxides commonly used as binders for zeolite catalysts, such as silica, alumina, silica-alumina, kaolin, and silica-magnesia. Good too. The content of zeolite as a catalytically active component in the catalyst composition is generally 1 to 99% by weight, preferably 0 to 90% by weight, based on the weight of the catalyst composition. The catalyst composition may also contain other components within a range that does not substantially affect its reaction characteristics.

As described above, the catalyst composition of the present invention comprises a crystalline aluminosilicate zeolite represented by the above formula (1) whose cation sites are ion-exchanged with cations of at least one alkaline earth metal at a high exchange rate. , the cation and R represented by the above formula (II) = 0.1 to 100
It contains an amount of palladium with a relationship of 0, has excellent xylenes isomerization ability, has ethylbenzene deethylation ability, and suppresses intermolecular rearrangement reaction of methyl groups in xylenes. Has excellent properties.

For ease of understanding, the catalyst composition of the present invention can be roughly divided into the following (1) to ( +ii). Of course, the catalyst composition of the present invention may be prepared by any method other than these methods or by partial modification thereof.

(1) The raw material zeolite is made to contain at least 11 m of dialkaline earth metal by ion exchange and calcination in a conventional manner, and then palladium is supported in a conventional manner, and then the above-mentioned binder is used. A method of molding using conventional methods.

(11) A method in which raw zeolite is made to contain at least one alkaline earth metal through ion exchange and calcination, and then molded together with a binder to support palladium.

(iii) A method in which raw material zeolite is molded together with a binder, and then impregnated with at least one alkaline earth metal by ion exchange and calcination, and then palladium is supported.

The cations contained in the above-mentioned cation sites of the raw material zeolite used in the methods (1) to (iii) above may be an alkali metal derived from the synthetic raw material, or a chain acid which is a proton source after synthesis. Alternatively, hydrogen ions or ammonium ions introduced by ion exchange using an ammonium compound such as ammonium chloride as an ammonium ion source may be used.

In order to cause the cation sites of such raw material zeolite to contain cations of at least one kind of alkaline earth metal, it is carried out according to a known method.

That is, this can be carried out by contacting the zeolite with a water bath solution containing chlorides, nitrates, etc., containing ions of the metal to be exchanged.

The amount of salt used at this time can be arbitrarily selected, but it is preferably in the range of 1 to 100 equivalents, particularly 10 to 50 equivalents, based on the alumina in the zeolite. A range of from 5 to 10% by weight is preferred, especially from 5 to 10% by weight. In the case of a batch method, this contact operation is repeated several times depending on the desired amount of metal ions introduced into the cation site, but there is no problem in using a flow method.

Although ion exchange proceeds at room temperature, it is also possible to increase the temperature to increase the exchange rate, and such temperature is usually 50°C.
A range of 95°C to 95°C is preferred.

Furthermore, when it is intended to introduce both cations of two or more alkaline earth metals, the order of exchange may be arbitrary, or a mixed solution may be used.

Various compounds can be used as alkaline earth metal compounds to be subjected to ion exchange, and nitrates and carbonates will be shown in this example.

Chlorides, perchlorates and other inorganic salts are preferably used. It is also possible to use organic salts such as acetate, but nitrate salt and chloride vlJ are particularly preferred.

In addition, before performing such ion exchange, the raw material zeolite is heated in advance at a temperature of 100 to 700°C, preferably 200 to 600°C.
It is also possible to heat the catalyst at a temperature of 1 to 50 hours under an oxygen atmosphere, such as air, or an inert gas atmosphere, such as #'i nitrogen, to obtain a superior catalyst, which is generally preferred.

The zeolite ion-exchanged with at least one alkaline earth metal as described above is heated at a temperature of 100 to 700°C, preferably 200 to 600°C, in an oxygen atmosphere such as air, or an inert gas such as nitrogen. Approximately 1 under atmosphere
After heat treatment for ~16 hours, it is modified with radium.

Of course, the ion-exchanged zeolite as described above in (1) to (button) may be in the form of a powder or may be molded together with a binder.

Such modification of zeolite with palladium can be carried out by a method known as a metal ion exchange method or a supporting method with respect to a normal zeolite.

For example, the contact treatment may be carried out with a water-soluble or water-insoluble medium containing a dissolved zeolite-depleted palladium compound containing a cation of at least one of the alkaline earth metals. Such palladium compounds include halides, WR compounds, sulfide 1w1 base salts, complex compounds, and the like. For example, zeolite is impregnated with an aqueous solution of a water-soluble palladium compound (e.g. palladium chloride),
Palladium may be supported on zeolite by evaporating all of the water on the ridges, and palladium compounds having ion exchange ability such as palladium amine complexes,
Palladium may be ion-exchanged by immersing a zeolite in an aqueous solution and filtering it to thoroughly wash the zeolite.

The zeolite that has been modified with palladium is 1
The heat treatment can be carried out at a temperature of 00 to 700°C, preferably 200 to 600°C, in an oxygen-containing atmosphere such as air, or in an inert gas atmosphere such as nitrogen, for about 1 to about 16 hours; preferable.

When the zeolite thus obtained is ion-exchanged with at least one alkaline earth metal and modified with palladium, it is molded into various shapes as desired, such as pellets or tablets, as desired. It can be subjected to the reaction of the invention. When molding the zeolite, the above-mentioned refractory inorganic oxide is used.

Upon use, the catalyst composition thus prepared is heated to 200 to 600
0° C., preferably 250 to 550° C., but this reduction treatment is usually preferably carried out after charging the reactor. A method for isomerizing xylenes according to the present invention, which is characterized by bringing into contact a raw material mixture containing xylene isomers having a concentration equal to or lower than the dynamic equilibrium concentration, will be described.

The catalyst composition of the present invention described above is extremely excellent as an isomerization catalyst for xylenes. The aromatic hydrocarbon raw material used in this case is a raw material mixture having at least one xylene isomer having a thermodynamic equilibrium concentration or less. As is well known, xylene has three isomers: ortho-, meta-, and para-isomers.If a mixture of these three isomers in any proportion is used in an isomerization reaction, It is known that when the ratio of the three isomers reaches a certain value, an equilibrium state is reached, and isomerization apparently does not proceed any further. The composition of the xylene isomer mixture in this equilibrium state is called the "thermodynamic equilibrium composition", and this thermodynamic equilibrium composition differs slightly depending on the temperature. For example, the xylene isomer mixture at the following temperature The equilibrium composition of is as follows.

[1] In the case of a mixed part of only three xylene isomers [427°C]; p-xylene 23.4% by weight.

m-xylene 52.1% by weight 0-xylene 245% by weight (II) In the case of a xylene isomer mixture containing ethylbenzene [427°C]; ethylbenzene 8.3% by weight p-xylene 21.5% by weight, m-xylene 47 .8 Graded Thyro-xylene 22.4 * it % Therefore, in this specification, "a mixture containing xylene isomers, at least one of which has a concentration below the thermodynamic equilibrium concentration" refers to three isomers of xylene. A mixture of xylene isomers in which the concentration of at least 1 m of the isomers deviates from the concentration at thermodynamic equilibrium composition.

The aromatic hydrocarbon feedstock used as starting material in the process of the present invention may consist of a xylene isomer mixture and other aromatic hydrocarbons flJ, t. ethylbenzene,
benzene, toluene.

A mixture of ethyltoluene, trimethylbenzene, diethylbenzene, ethylxylene, tetramethylbenzene, etc. may be used. In the latter case the xylene isomer mixture is
Based on the weight of the aromatic hydrocarbon feedstock, generally 30
% by weight, preferably 50% by weight or more. In the method of the present invention, the raw material mixture that can be particularly advantageously used is a 08 aromatic hydrocarbon distillate obtained from reforming, pyrolysis, or hydrocracking of petroleum. In addition to the xylene isomer mixture, the fractions with and also contain ethylbenzene with the same number of carbon atoms. In the present invention, A also provides a C8 aromatic hydrocarbon fraction in which the xylene isomer mixture and ethylbenzene together account for at least 80% by weight, preferably 90% by weight or more, based on the weight of the fraction. Very advantageous results are obtained when used.

The above-mentioned isomerization of the aromatic hydrocarbon raw material can be carried out under per se known xylene/lene isomerization reaction conditions if the specific catalyst is used and the sand is removed. However,
The reaction temperature is generally 280-500°C, preferably 300°C.
~450°C, and the reaction pressure is generally from normal pressure to 30°C/cd, preferably from normal pressure to 25°C/cd.
It can be freely selected within the range of 6/IvI.

In carrying out the isomerization method of the present invention, the feed ratio of the raw material mixture can vary widely depending on the type of hydrocarbon raw material and/or catalyst used, but generally about 0.1 to about 200,
It is advantageous to feed at a weight unit hourly space velocity in the range, preferably from 0.1 to 50.

Further, the isomerization of the present invention is more preferably carried out in the presence of hydrogen. The hydrogen supply ratio at that time can be varied widely depending on the type of raw material mixture and/or catalyst composition used, but it is generally 1 to 30, preferably 1, expressed as a molar ratio of hydrogen/raw material mixture. It is appropriate to supply the amount within the range of 20 to 20.

In addition, when carrying out the isomerization reaction of the present invention, prior to the reaction or when the activity falls below a certain level after carrying out the isomerization reaction, by carrying out the commonly known chlorination treatment of zeolite. , the initial activity of the catalyst can be increased, or the activity after regeneration, especially the isomerization activity of ethylbenzene, can be returned to a high level. In addition, such chlorination treatment can be carried out on the catalyst composition of the present invention at the time of catalyst preparation by introducing chlorine into the catalyst. This can also be done by incorporating a chlorine compound as a component of the mixture.

xy L/y using the catalyst composition of the present invention described above
According to the isomerization method of @, it is possible to achieve various excellent advantages as described below in comparison with conventional similar techniques, and the contribution to industry is extremely large.

That is, according to the method of the present invention, the intermolecular rearrangement reaction of the methyl groups of xylenes, that is, the disproportionation reaction of xylene and the transalkyl reaction between xylene and ethylbenzene, are suppressed, so the loss of quinlene is greatly reduced and the xylene loss is suppressed. The isomerization yield is improved.

Further, according to the method of the present invention, the deethylation reaction of ethylbenzene is promoted, and as a result, the transalkylation reaction between ethyl/xeno and xylene is suppressed, thereby improving the isomerization yield of xylene.

Further, according to the method of the present invention, undesirable side reactions such as the demethylation reaction of xylenes and the hydrogenation reaction of benzenes are suppressed, and the isomerization yield of xylene is improved.

EXAMPLES Hereinafter, the present invention will be briefly described with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 (a) Preparation of H-ZSM-5 Zeolite ZSM-5 was synthesized according to the method fully disclosed in US Pat. No. 3,965,207. During the synthesis, tri-n-propylamine and n-propylbroyide were added as organic nitrogen cation sources. The compound was identified as ZSM-5 from the X@ diffraction pattern. Obtained 28M
-5 was filtered, thoroughly washed with water, and heated to 100°C in an electric dryer.
It was dried for 8 hours at 200'C, then for 16 hours at 200'C, and further calcined at 450C for 16 hours under air flow in an electric Matsufuru furnace. Thereafter, 250 g of the sample was subjected to ion exchange with 1.51 g of a 5 wt. ammonium chloride aqueous solution at 80 DEG C. for 24 hours. This operation was repeated two more times.

After that, it was thoroughly washed with water and dried at 100℃ for 8 hours in an electric dryer.
Next, it was dried at 200° C. for 16 hours, and then fired in an electric Matsufuru furnace at 450° C. for 16 hours under air circulation to obtain H green type Z8M-5. The sodium content of this product was 0.05% by weight, and the silica/alumina molar ratio was 71 (hereinafter referred to as zeolite A-1).

(b) Preparation of Be 28M5 Zeolite A calcined at 450'O for 8 hours under air flow
-1109 to beryllium nitrate trihydrate 7.59 to 100d
Ion exchange was performed for 6 hours under reflux in an aqueous solution in which the sample was dissolved in water. This operation was repeated 1& more. After that, Be-28M5 was obtained by washing with water under light and drying at 200° C. for 8 hours in an electric dryer. This thing IJ
IJum containing 1Lao, ts weight percent and Be
/A/2 = 0, 79 (hereinafter this will be referred to as zeolite B-1).

(e) Mg-28M 5 (under D-prepared air flow 4
Zeolite A-1109, which had been calcined at 50° C. for 8 hours, was ion-exchanged for 6 hours under reflux in an aqueous solution prepared by dissolving 29 g of magnesium nitrate/6 water in 100° C. water.

This operation was roughly repeated twice. After washing, rinse thoroughly with water,
Mg was removed by drying at 200 °C for 8 hours in an electric dryer and further calcining at 450 °C for 8 hours in an electric Matsufuru furnace.
-ZSMS was obtained.

The magnesium content of this product is 0.18% by weight, Mg/k12=0, 32T6 (
This is hereinafter referred to as zeolite (!-1).

(d) Preparation of Oa-28M5 Oa-28M was prepared by the same method as in (b) above, except that an aqueous solution of calcium nitrate tetrahydrate 272 was dissolved in 100+d water and the number of ion exchanges was 5 times.
I got 5 i. Calcium content of this substance i; i0.7
9 weight percent acid Oa /A12 = 0, 89
(hereinafter referred to as zeolite D-1).

(e) Preparation of i9r-28MS Aqueous solution of strotium nitrate 21.291 and 200-WL in water.
Sr-28M5 was obtained by the same method as in (b) above, except that Sr-28M5 was used.

The strontium content of this product was 1.06 weight percent, j) 8r/A/1 = 0, 57 (hereinafter referred to as zeolite E-1).

(f) Preparation of Ba ZSM5 Ba-ZSMS was obtained by the same method as in (b) above, except that an aqueous solution in which 23.6 F of barium chloride was dissolved in 200 g of water was used. The barium content of this product is ri1.14% by weight.Ba/A/2
= 0,39 (hereinafter referred to as zeolite F-
1).

ω Pd/H-ZSMS, Pd/Bp-78MS
, Pd/Mg-ZSMS.

Pd/Ca-2BM S, Pd/Sr-ZSM
Preparation of S and Pd/Ba-ZSMS Haladium chloride 922111P1 was dissolved in 8 salt $2sd and water 10sIt, and then water was added to make the total amount 50-. Add 20 - of water to 1.35 - of this aqueous solution, and then add 5 -
9 Zeolite) Suspension of A-1? I set it. Then 6 at 70℃
After holding for a period of time, the solvent was distilled off at 40°C under reduced pressure using a rotary evaporator, and the temperature was 200°C during electrical drying.
Dry for 8 hours, then dry in an electric Matsufuru oven under air circulation for 4
Pd/'H-28 by firing at 50℃ for 8 hours
I got Ms. The palladium content of this material was 0.3% by weight (hereinafter referred to as zeolite A-2
).

Zeolite B-1, O-1, D-1, B-1 and F-1
Pd/Be 2 under the same conditions as above using
8M 5 , Pd/Mg 28M S , Pd1
0a-ZSM S, Pd/! Sr-ZSM 5 and Pd/Ba-28M S were prepared (hereinafter referred to as zeolite B-2, zeolite O-2, zeolite D-2).
, zeolite E-2 and zeolite F-2). These R values are 6.4°2.6, 7.2, and 4, respectively.
,6,3.1.

Example 2 Regarding the catalyst composition obtained in Example 1, the 1,3.5-trimethylbenzene adsorption rate (A), which represents the characteristics of the catalyst composition of the present invention, was measured. That is, zeolite which is the catalyst composition of the present invention) B-2, 0-2゜D-2, B-2 and F
-2, zeolite A-2 as a comparative example, and zeolite A-1 (H-zSMs) as a reference were calcined in an electric Matsufuru furnace at 450 °C for 8 hours. did. The zeolite was then heated at 25°C in a desiccator containing 1.3.5-)limethylbenzene.
1.3.5-trimethylbenzene was adsorbed by standing for 10 minutes under a reduced pressure of 30±5 mH9. Thereafter, the 1,3,5-trimethylbenzene in the desiccator was removed, and the mixture was kept in the desiccator under the same conditions and for the same time as above, and then weighed to measure the adsorption of 9 -1v per unit weight of zeolite. The adsorption rate (RA) is the adsorption i of the catalyst @adsorption amount Vo of the reference zeolite A-1.
It can be determined by the ratio of 1 Vs, that is, the following formula: %, and the results are shown in Table 1.

B-2,0 which is the catalyst composition of the present invention from the fruit of Table-1
The RA of -2, D-2, E-2 and F-2 is smaller than that of comparative example A-2, and the larger the cation, the more R
It can be seen that Ald becomes smaller.

Table 1 Example 3 Regarding the catalyst composition obtained in Example 1, the (ethylbenzene/xylene) reaction selectivity (Re), which represents the characteristics of the catalyst composition of the present invention, was measured. That is, the zeolite B-2,0-2,D-2,E of Example 1 which is the catalyst composition of the present invention
-2 and F-2 and zeolite hA-2 as a comparative example, each containing 50% by weight and 11% of γ-alumina.
Molded into a mesh beret. The pellets were calcined in an electric furnace at 450°O for 8 hours, and 32 was charged into a flow-through normal pressure fixed bed reaction tube.The catalyst bed temperature was set at 400°O, and hydrogen was passed through at a rate of 100Nt/- for 2 hours. By doing so, the platinum contained in the catalyst was reduced. In addition, 12 t (WH8V = 4 Hr-) of an aromatic hydrocarbon composition of ethylbenzene/xylene = 15/85 (weight ratio) under normal pressure
) and hydrogen at a molar ratio of 171 (molar ratio) of water/hydrocarbon were supplied. The temperature of the catalyst bed was adjusted so that the ethylbenzene conversion rate was 30% as described above. After analyzing the product composition at the mouth for 5 hours after the start of the feed, the ethylbenzene conversion "4" (BEIDrSA) as described above was determined.
・Calculate the xylene conversion ″$ (XYLO8S) and calculate R
B=(ethylbenzene/xylene) reaction selectivity (8n) t-measured as defined by BBpr machine PeYfitS. The results are summarized in Table-2.

From the results in Table 2, the catalyst composition of the present invention B-2,0
It can be seen that the RB of -2, D-2, E-2 and F-2 is significantly higher than that of A-2, and this tendency becomes more pronounced as the cation becomes larger.

Table 2 Example 4 An isomerization reaction of a mixed xylene raw material was carried out using zeolites B-2 and D-2, which are uninvented catalyst compositions of the catalyst composition obtained in Example 1.

As in Example 3, alumina gel for chromatography (γ-alumina;
300 mesh) 7 was mixed thoroughly at a weight ratio of 1/1, and molded into a size of 10 to 20 mesh. The obtained molded product was fired in an electric Matsufuru furnace at 450° C. in an air atmosphere for 8 hours, and then packed into a flow-through pressurized fixed bed reactor. .

Thereafter, a reduction treatment was performed at 400"C in a hydrogen stream for 2 hours, and then a xylene isomerization reaction was carried out using the mixed xylene having the composition shown in Table 3 as a raw material.Reaction conditions:
The product composition is shown in Table 3.

The various rates and abbreviations used in the table have the following meanings.

Deethylation rate (%) - Aromatic nucleus loss rate (%) [PX]p: 7 xylene 3 isomer concentration in the eaten solution <weight i%) [PX)p; xylene 3 in the product solution Paraxylene concentration 1f (11%) in the isomer [:PX3E; Equilibrium concentration of paraxylene in the xylene isomer at the reaction temperature (
weight%) [:HB]p: EB bath concentration in feed liquid weight%) (
EB:]P; EB# degree (weight %) in product liquid CX
:]p; Xylene isomerization catalyst in feed liquid (wt%) [Xjp: Concentration of cylene 3 isomer in product liquid (wt%) From the results in Table 3, D-2, E-2, F-2d It is found that it is an excellent xylene isomerization catalyst with high isomerization activity, extremely low xylene loss rate, and fair deethyl removal activity.

Table 3 ■ Written amendment to the procedure June IF, 1982, Director General of the Patent Office 2 Name of the invention Catalyst composition and method for isomerizing xylenes 3 Relationship with the person making the amendment Case To apply for a patent Chiyoda, Tokyo Teijin Yuka Co., Ltd. 2-1-1, Uchisaiwai-cho, Tokyo (7726), 2-1-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo (Iino Building)
Patent Attorney Jun Hiroshi Maeda Contact Information (506) 4481 5. Corrections are required.

(2) "Collateral" on page 6, line 7 of the specification is corrected to "carrier."

(3) Correct "x-mi" in line 1 of page 13 to "x1."00W, t4) Adjust line 7 of page 29 iij 7? )
v Correct section J.

(5) "1 isomerization activity" in the bottom two lines of page 4o is corrected to "deethylization activity."

(6) “Platinum” on page 49, line 13, “t palladium”
I am corrected.

Claim 1 (1) General formula (I) xMO・(1-X)N40AttOs-78iOt
,...(Crystalline aluminosilicate zeolite represented by II and the following formula mark) 1" is palladium in an amount corresponding to R expressed in the crystalline aluminosilicate zeolite 1 from 0.1 to 1000. (2) 1,3.5-trimethylbenzene adsorption rate (R
Catalytic composition characterized in that A) is in the range from 0.1 to 0.9 and <3) the (ethylbenzene/xylene) reaction 14 selectivity (RB) is at least 60.

2. The catalyst composition according to item 1, wherein y in the crystalline aluminosilicate zeolite is 30 to 100.

3. The catalyst composition according to item 1, wherein X in the crystalline aluminosilicate zeolite is 0.3 to 0.8.

4. The catalyst composition according to item 1, which contains palladium in which R represented by the formula (It) corresponds to 1 to 200.

5. The crystalline aluminosilicate zeolite is modified from at least one zeolite selected from the group consisting of zeolite Z8M-5, zeolite ZSM-11° zeolite ZSM-12, zeolite Z8M-35, and zeolite ZBM-38. A catalyst composition according to claim 1.

6. (1) General formula (I) xMO・(1-X)NLOAttOs-7SiOt
H) Contains as a main active ingredient a crystalline aluminosilicate zeolite represented by HH' (1) and palladium in an amount such that R represented by the following formula 〇) corresponds to 0.1 to 1000, (2) 1 , 3.5-) Limethylbenzene adsorption rate (
RA) is in the range of 0.1 to 0.9, and (3) (ethylbenzene/xylene) reaction selectivity (
A method for isomerizing xylenes, which comprises contacting a catalyst composition having a RB) of at least 60 with a raw material mixture containing at least one xylene isomer having a thermodynamic equilibrium concentration or less in a gas phase. .

7. The method for isomerizing xylenes according to item 6, wherein the raw material mixture contains ethylbenzene.

8. The method for isomerizing xylenes according to item 6, wherein the contact is carried out in the presence of hydrogen.

Claims (1)

[Claims] 1. (1) Crystalline aluminosilicate zeolite represented by the general formula (1) % formula % (1) and B5 represented by the following formula (II) correspond to o, i ~ 1000 (211,3,5-) remethylbenzene adsorption rate (RA
) is in the range of 0.1 to 0.9, and (3) (ethyl pentene/xylene) reaction selectivity (FLB) is at least 60. 2 y in the crystalline aluminosilicate zeolite
3. The catalyst composition according to claim 1, wherein 3 X in the crystalline aluminosilicate zeolite
2. The catalyst composition according to claim 1, wherein is from 0.3 to 0.08. Table 1. The catalyst composition according to item 1, which contains palladium in which R represented by the formula (II) corresponds to 1 to 2001C. & Crystalline aluminosilicate zeolite modified from at least one zeolite selected from the group consisting of caseolite Z8M-6, zeolite ZSM-11, zeolite Z8M-12, zeolite Z8M-35, and zeolite Z8M-38. 2. The catalyst composition according to claim 1, which is 6(1) General formula (I) xMO・(1-x)NJIO・Human110B・yS r
01 ------- Crystalline aluminosilicate zeolite expressed by (summer) and palladium in an amount compatible with R expressed by the following formula (1) % formula % () 0.1-1000 as the main activity Contained as a component, @) 1.3.5-trimetherpe/zene adsorption rate (RA
) is in the range of 0.1 to 0.9). (3) (Ethylbenzene/xylene) reaction selectivity (
A method for isomerizing xylenes, which comprises contacting a catalyst composition having R3B) of at least 60 in a gas phase with a raw material mixture containing xylene isomers, at least one of which has a concentration below the thermodynamic equilibrium concentration. 7. The method for isomerizing xylenes according to item 6, wherein the raw material mixture contains ethylbenzene. 8. The method for isomerizing xylenes according to item 6, wherein the contact is carried out in the presence of hydrogen.