JPH0656710A - Method for isomerizing xylene - Google Patents

Abstract

PURPOSE:To efficiently deethylate and decompose ethylbenzene(EB) while suppressing the side reaction. CONSTITUTION:The method for efficiently deethylating a xylene isomerization mixture containing EB in an 8C aromatic while suppressing the loss of xylene in the presence of a catalyst composed of an alkaline earth metal cation- containing crystalline aluminosilicate supporting silicon oxide and a refractory inorganic oxide supporting platinum and tin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improvement in the xylene isomerization process. More specifically, the present invention relates to the loss of xylenes from ethylbenzene in a hydrocarbon feedstock comprising a major amount of xylene isomer mixture and ethylbenzene. The present invention relates to an industrially advantageous method for isomerizing xylene by efficiently decomposing and removing the above.

[0002]

BACKGROUND OF THE INVENTION The demand for xylenes, especially paraxylene, has increased in proportion to the demand for polyester fibers and films. A typical method for producing para-xylene is a step of separating para-xylene from a hydrocarbon mixture raw material by a crystallization method or an adsorption method for a C8 aromatic hydrocarbon mixture raw material, and a residual hydrocarbon mixture containing meta-xylene and / or A step of contacting a catalyst for isomerization of oxoxylene to para-xylene to convert xylenes in the residual hydrocarbon mixture into a xylene isomerization mixture having a nearly thermodynamic composition, and the isomer mixture. It consists of a step of recycling to the separation step.

In the above-mentioned method for producing para-xylene, the composition of the xylene isomer mixture in the isomerization reaction product is brought as close as possible to the thermodynamic equilibrium composition, and disproportionation / hydrogenation accompanied by loss of xylenes. Suppressing side reactions such as decomposition reactions, converting ethylbenzene, which is difficult to separate by normal distillation operation due to its similar boiling point to xylenes, to a light component or heavy component that can be easily separated by distillation, etc. There is a demand, and it is industrially very important to meet these demands in order to enhance the efficiency of the isomerization reaction and reduce the cost of the paraxylene production process.

There have been many proposals for isomerization methods of xylenes, many of which are methods using a crystalline aluminosilicate-containing catalyst, and improvement, development and isomerization of catalysts relating to these methods have been proposed. Research has focused on improving conditions and many proposals have been made.

In particular, in the case of isomerizing a xylene isomer mixture containing ethylbenzene, it is desirable to deethylate ethylbenzene together with the isomerization reaction of xylenes, and some methods therefor have been proposed. For example, the above-mentioned method is described in U.S. Pat. Nos. 4,098,836, 4,163,028 and 4,152,363.
It is described in the specification etc.

However, in the method proposed hitherto,
In addition to the main reaction of xylene isomerization and ethylbenzene deethylation reaction, benzene ring hydrogenation, xylene disproportionation,
The loss of xylenes is inevitable.

[0007] For example, in the above three US patents, ZSM modified with a platinum group metal such as nickel or platinum.
A method of isomerizing a xylene isomer mixture containing ethylbenzene using a series of zeolites is disclosed.

ZSM-type zeolite catalyst modified with nickel (having a Ni content of 2% by weight or less)
In such a case, under so-called severe reaction conditions in which the conversion of ethylbenzene is high, the demethylation reaction of xylene is promoted and xylene loss increases. For this reason, it has been industrially considered advantageous to use a ZSM-type zeolite catalyst modified with a platinum group metal which is less likely to undergo demethylation reaction. However, for example, a platinum-modified ZSM-type zeolite has excellent isomerization characteristics of xylenes and excellent ability to selectively deethylate ethyl groups of ethylbenzene, while platinum itself has a benzene ring structure. Has a high hydrogenation activity, and the hydrogenation reaction occurs remarkably as the temperature decreases from thermodynamic equilibrium, which increases the production of naphthenes. As a result, xylene loss increases, so it was necessary to industrially use the platinum-modified ZSM-type zeolite catalyst at a high temperature of 800 ° F (427 ° C) or higher. Further, the temperature required for the isomerization reaction depends on the space velocity, but is generally about 300 to 320 ° C.
Is sufficient, and isomerization is not improved at higher temperatures, rather, unfavorable reactions such as disproportionation and transalkylation are promoted and xylene loss is increased.

Therefore, a new and improved method for isomerizing xylene which does not have the above-mentioned drawbacks found when isomerizing using a platinum-containing ZSM type zeolite catalyst, that is, platinum is included. While maintaining the excellent xylene isomerization and selective deethylation ability of the ZSM-based zeolite catalyst, the disadvantages of this catalyst such as hydrogenation reaction of benzene ring, disproportionation reaction of xylene, xylene and ethylbenzene Many studies have been conducted on an improved platinum zeolite-based catalyst in which the ability to accelerate the transalkylation reaction of (1) was significantly suppressed, and several inventions have been proposed.

For example, in JP-A-56-147636 and JP-A-3-14613, benzene ring hydrogenation reaction activity of platinum, xylene disproportionation of crystalline aluminosilicate, and transalkylation activity of xylene and ethylbenzene are described. It has been disclosed that addition of a second metal component other than platinum is effective in suppressing the above, and there are a wide variety of effective metals.

The inventors of the present invention have already disclosed in Japanese Patent Laid-Open No. 2-9103.
No. 1 discloses a catalyst composition comprising a pentasil-type crystalline aluminosilicate in which at least 50% of cation sites are occupied by alkaline earth metal cations, a refractory inorganic oxide supporting platinum, tin and hydrochloric acid, and indium. Is proposed.

Further, Japanese Patent Application Laid-Open No. 58-157729 discloses a ZSM having a crystal size of 1 μm or more in which an alkaline earth metal ion is introduced as a crystalline aluminosilicate zeolite.
It has been proposed that type-5 zeolite is effective.

In all of these methods, (a) the activity for the isomerization reaction of xylene is excellent, (b) the ethylbenzene is efficiently deethylated, and (c) the undesirable side reaction (of the benzene ring). Although it is an excellent method in that it almost satisfies all of the three conditions (hydrolysis, demethylation, disproportionation, transalkylation, etc.), condition (c) has a level of undesirable side reaction. It cannot be ignored.

[0014]

OBJECTS OF THE INVENTION Therefore, the inventors of the present invention further studied an ethylbenzene decomposition catalyst for efficiently deethylating ethylbenzene while suppressing various undesirable side reactions as much as possible among the above three conditions. It has come. According to the research conducted by the present inventors, it is extremely difficult to suppress an undesirable side reaction while maintaining the same xylene isomerization activity and ethylbenzene decomposition activity as those of the above-mentioned conventional techniques, but it is preferable that the ethylbenzene decomposition activity is preferable. The present invention has been made by discovering that it is possible to bring two contradictory conditions, that is, an adverse side reaction, to a level that can satisfy both of them.

[0015]

According to the present invention, however, a hydrocarbon feedstock consisting of a major amount of a xylene isomer mixture and ethylbenzene is subjected to a xylene isomerization reaction, and a specific xylene isomer is produced from the resulting isomerization reaction mixture. In a continuous xylene isomerization process comprising isolating the body and recycling the remaining hydrocarbon mixture to the xylene isomerization reaction, wherein the hydrocarbon feedstock or xylene isomerization mixture comprises:
(A) A pentasil-type crystalline aluminosilicate zeolite supporting silicon oxide, having a silica / alumina (molar ratio) of at least 10 and having at least 10% of its cation sites occupied by metal cations selected from alkaline earth metals. And (b) platinum and tin-supported refractory amorphous inorganic oxide in the presence of a catalyst to decompose ethylbenzene in the hydrocarbon feedstock or in the xylene isomerization reaction mixture. A featured xylene isomerization process is provided.

The present invention will be described.

The hydrocarbon feedstock which can be used in the process of the present invention is mainly composed of a mixture of xylene isomers and ethylbenzene, and in addition, a small amount of non-aromatic hydrocarbons, benzene, toluene and cumene, ethyltoluenes, It contains C9 + aromatic hydrocarbons such as trimethylbenzenes.

One of the hydrocarbon feedstocks is so-called C
8 aromatic hydrocarbon fractions, industrially, catalytic reforming oil,
It is produced by separating an aromatic hydrocarbon component from a raw oil such as a pyrolysis oil by solvent extraction by a method such as a sulfolane method, a UDEX method or an arosolvan method, and then distilling the extracted separated liquid. . This mixture is typically 15-25 wt% ethylbenzene, 1 part para-xylene.
5 to 25% by weight, 30 to 60% by weight of metaxylene and 15 to 25% by weight of orthoxylene.

In recent years, various attempts have been made to improve the recovery of aromatic hydrocarbons such as benzene, toluene and xylene in the reforming of petroleum naphtha, and the naphtha reforming oil is subjected to the solvent extraction step as described above. Instead, a method of obtaining a C8 aromatic hydrocarbon mixture having a content of non-aromatic hydrocarbons that can be used for the production of xylene by only a distillation treatment has been proposed (Japanese Patent Publication No. 57-47231).

The C8 aromatic hydrocarbon mixture obtained by such a method is also one of the hydrocarbon feedstocks used in the present invention, and it contains a small amount of non-aromatic hydrocarbons.

In the present invention, the above C8 aromatic hydrocarbon mixture, and / or the residue after isolating a specific xylene isomer from this mixture and / or the residue is subjected to a xylene isomerization reaction. The latter reaction product is used as the hydrocarbon feedstock. The composition of this hydrocarbon feedstock is the composition and method of manufacture of the C8 aromatic hydrocarbon mixture,
It cannot be specified exactly because it depends on the separation method of the specific xylene isomers, the performance of the isomerization reaction adopted, and the like. However, in order to achieve the object of the present invention, namely the efficient decomposition of ethylbenzene, ethylbenzene is added to these feeds on a weight basis.
It is preferable that the content is up to 30%. Aromatic hydrocarbons other than C8 and non-aromatic hydrocarbons contained in a small amount in the feedstock have no effect on the present invention. Rather, this non-aromatic hydrocarbon is efficiently decomposed in the present invention.

The present invention is to treat the above-mentioned hydrocarbon feedstock in the presence of an ethylbenzene decomposition catalyst having the above-mentioned specific composition to decompose ethylbenzene in the hydrocarbon feedstock.

Further, as the zeolite used in the present invention, the following series of known zeolites are known in the present invention (the names of the references disclosing the composition, characteristics, production method and the like of the zeolite are described in parentheses), that is, Zeolite ZSM-5 (Japanese Patent Publication No. 46-10064) ZSM-11 (Japanese Patent Publication No. 53-23280) ZSM-12 (Japanese Patent Publication No. 52-16079) ZSM-34 (Japanese Patent Publication No. 53-58499) At least 10%, preferably 20% or more of the cation / anion sites of the zeolite selected from the series of ZSM-48 (Japanese Patent Publication No. 55-149119) are at least one metal selected from alkaline earth metals. 0.01 to 20% by weight of acid, occupied by cations, based on the weight of the zeolite Zeolite silicon is carried is used.

Among the above zeolites, ZSM-5 zeolite is particularly preferable in the present invention. Examples of the metal cation include beryllium, calcium, magnesium, strontium, barium, and the like.
The strontium cation is preferred. At the cation site of the zeolite, only one of these metal ions may be present, or two or more of them may coexist.

It should be noted that protons can usually be present in the unoccupied cation sites of the zeolite.

Zeolites in which at least 10% of such cation sites are occupied by alkaline earth metals are, for example, zeolites prepared as described in the above-mentioned literature by methods known per se [eg J. ． Catal
yst. 46, 100-108 (1977), J. Ca
Talyst, 43, 292-303 (1976)], and can be easily produced by subjecting it to an ion exchange treatment using an alkaline earth metal cation.

In the present invention, silicon oxide is further added to the crystalline aluminosilicate containing the alkaline earth cation in an amount of 0.01 to 20 based on the weight of the zeolite.
What is supported by weight% is used.

In order to support silicon oxide on the alkaline earth metal aluminosilicate zeolite, a conventional modification method may be used. A crystalline aluminosilicate may be coated with a silicon compound (eg, silicates such as methyl silicate and ethyl silicate). The solution may be impregnated, filtered or the solvent may be evaporated, dried and then fired in an oxygen atmosphere. Further, in the present invention, silicon oxide can be supported by carrying out the catalyst of the crystalline aluminosilicate zeolite and the silicon compound in the gas phase (that is, bringing the silicon compound into vapor form and bringing it into contact with the crystalline aluminosilicate).

The crystalline aluminosilicate prepared as described above and containing an alkaline earth metal cation on which silicon oxide is supported is used as one of the catalyst components in the present invention.

On the other hand, in the refractory amorphous inorganic oxide supporting platinum and tin used in combination with the above zeolite, the refractory amorphous inorganic oxide used as a carrier is not particularly limited, Those used as the catalyst carrier can be used, and examples thereof include silica, alumina, silica-alumina, kaolin, silica-magnesia, zeolite, zirconia, magnesia and the like. Among them, γ-alumina is preferable from the viewpoint of the specific surface area of the carrier.

The amount of platinum supported on such a carrier is from the viewpoint of suppressing the nuclear hydrogenation or ring decomposition reaction of xylenes in the hydrocarbon feedstock as much as possible and promoting the reaction as much as possible. Generally 0.005, based on the weight of
-5.0 wt%, preferably 0.01-2.0 wt%,
More preferably, it is within the range of 0.1 to 1.0% by weight.

It is presumed that the function of platinum supported on the refractory inorganic oxide is to significantly promote the deethylation reaction of ethylbenzenes as a concerted effect due to the combination with the zeolite.

On the other hand, the function of tin supported on the carrier moderately suppresses the hydrogen dissociative adsorption capacity of coexisting platinum, and as a result, the nuclear hydrogenation and ring decomposition reaction of xylenes in the hydrocarbon feedstock is significantly reduced. On the other hand, it is considered that the deethylation reaction of ethylbenzene is allowed to proceed sufficiently. Thus, the amount of tin carried on the carrier is generally 0.1 / 1 to 1 in terms of tin / platinum atomic ratio from the viewpoint of vapor.
It is in the range of 0/1, preferably 0.3 / 1 to 7/1, and more preferably 0.5 / 1 to 5/1.

In the preparation of the platinum-tin-supported inorganic oxide as described above, either a method of sequentially supporting the support components or a method of simultaneously supporting the support components can be used. For example, a platinum compound or a tin compound is contained. After impregnating the refractory inorganic oxide with the uniform solution, the solvent may be removed and dried.

As the platinum compound, for example, chloroplatinic acid, platinum tetraamine complex, and as the tin compound, stannous chloride,
Soluble salts such as tin sulfate and tetraalkylammonium chlorostannate are preferably used, and water, diluted hydrochloric acid, methanol, acetone and the like are preferably used as a solvent for dissolving them.

The above-mentioned catalyst composition used in the method of the present invention is formed into a catalyst shape such as pellets and tablets by uniformly mixing the respective catalyst components in the state of use and then pressing.

At this time, the weight ratio of the two components to be mixed can be widely varied, but generally, a platinum- and tin-supporting refractory amorphous inorganic oxide / silicon oxide-supporting alkaline earth metal cation-containing crystalline aluminosilicate zeolite is used. It is preferably in the range of 0.05 to 5 in terms of the weight ratio.

According to the method of the present invention, the specific composite catalyst composition described above is brought into contact with a hydrocarbon feedstock to selectively deethylate ethylbenzene in the catalyst feedstock.

The reaction is usually preferably carried out in the gas phase in the presence of hydrogen. At this time, the reaction temperature is generally 250.
To 500 ° C., preferably 270 to 480 ° C., and particularly preferably 280 to 450 ° C.

Further, the feed rate of the raw materials is generally 1 to 50.
It is advantageous to feed at a weight unit hourly space velocity (WHSV) in the range 0, preferably 2 to 100, more preferably 3 to 50.

On the other hand, the partial pressure of hydrogen is not strictly limited and can be changed according to the temperature to be used, WHSV, etc., but is generally 0.1 to 25 kg / cm ² , preferably 0.5 to. 20 kg / cm ² , more preferably 0.
It is convenient to choose from within the range of 8 to 15 kg / cm ² .

It is appropriate that the hydrogen is supplied in such a ratio that the hydrogen / hydrocarbon raw material molar ratio is generally in the range of 0.1 to 15, preferably 1 to 10. .

The above-described deethylation decomposition reaction of ethylbenzene may be performed on the hydrocarbon feedstock before being subjected to the xylene isomerization reaction, or after the xylene isomerization reaction is performed, the isomerization reaction is performed. It can also be carried out on the isomerization reaction mixture before the isolation of a particular xylene isomer, for example para-xylene, from the mixture. As a specific method thereof, for example, before or after the xylene isomerization reactor,
An ethylbenzene decomposition reactor filled with a composite catalyst can be provided in series with the xylene isomerization reactor.

In the method of the present invention, the xylene isomerization reaction can be carried out by a method known per se by using the above-mentioned catalyst. For example, it can be performed by the method described below.

(1) JP-A-50-53336 discloses a catalyst containing ZSM-5, ZSM-12 or ZSM-21 zeolite in a gas phase of 500 to 1000 °.
A method of contacting with a mixture of aromatic compounds containing ethylbenzene and xylenes at a temperature of F is disclosed.

(2) Japanese Patent Application Laid-Open No. 56-158150 discloses ZSM-5, ZSM-11, ZSM-containing noble metal.
A catalyst composition containing a zeolite selected from 12, ZSM-23, ZSM-35, ZSM-38, and / or ZSM-48 is used to obtain a temperature of 260 to 538 ° C. (preferably 42 ° C.).
7-482 ° C.), 50-1000 psig (preferably 100-400 psig) pressure, and 1-50 (preferably 5-15) weight hourly space velocity contacting the xylene-containing feedstock to isomerize xylenes. A method is disclosed.

(3) Japanese Patent Application Laid-Open No. 56-147636 discloses platinum and a second metal (preferably tin, barium,
ZSM-5, ZSM-1 containing a metal selected from the group consisting of titanium, indium, cadmium, and lead)
Using a catalyst composition containing a zeolite selected from the group consisting of 1, ZSM-12, ZSM-35 and ZSM-38, a temperature of 250 to 450 ° C., 0 to 25 kg / cm
A method of contacting a xylene isomer mixture at a hydrogen partial pressure of ² G and a weight hourly space velocity of 1 to 500 is disclosed.

(4) JP-A-58-210856 discloses a catalyst containing a crystalline aluminosilicate ion-exchanged with at least one selected from the group consisting of beryllium, strontium and barium, and modified with platinum. A method for isomerizing xylenes using the composition is disclosed.

In the method of the present invention, the isomerization reaction of xylene can be advantageously carried out by any of the above known methods.

As a method for isolating a specific xylene isomer, such as paraxylene, from the reaction mixture after the xylene isomerization reaction, a method known per se can be used. For example, Crystallization Method (Oil & Gas Jour
nal-Sept., 15,1975, p201-202; Hydrocarbon Processing,
Nov.1985, p175) or Adsorption Method (Ind.En
g.Chem.Prod.Rcedev., 18 (4) 263-268 (1979), Hydrocarbon
Processing, Nov., 1985, p175) and the like.

[0051]

INDUSTRIAL APPLICABILITY According to the above method of the present invention, the residue and / or the residue after isolating a specific xylene isomer from the C8 aromatic hydrocarbon mixture part and / or mixture are subjected to a xylene isomerization reaction. The ethylbenzene contained in the reaction product after being attached is industrially produced by efficiently deethylenyzing while suppressing side reactions such as a proximity reaction involving the loss of xylenes and a hydrogenolysis reaction. An advantageous xylene isomerization process is provided.

[0052]

EXAMPLES Next, the present invention will be described more specifically with reference to examples.

[0053]

Reference Example 1 (Synthesis of NH ₄ ⁺ type ZSM-5) US Patent
Zeolite ZSM-5 was synthesized according to the method disclosed in 3,965,207. Upon synthesis, water glass as a silica source, aluminum sulfate as an alumina source,
Using tri-m-propylamine and n-pyropyrbromide as the organic nitrogen cation source, methylethyl kent was further added, and the mixture was reacted in an autoclave under predetermined conditions. The product was filtered, washed thoroughly with water, and then dried overnight in an electric dryer at 100 ° C. As a result of X-ray diffraction, the product was identified as ZSM-5. As a result of chemical analysis, the product had a silica / alumina (molar ratio) of 70.

Then, the cation of the obtained zeolite
The site was converted from sodium ion to ammonium ion. That is, 10 ml of 10% ammonium chloride aqueous solution per 1 g of zeolite was used and treated for 16 hours under reflux. This operation was repeated twice. Then, it was filtered, washed with water, and treated at 100 ° C. for 16 hours. By performing this operation, ammonium type zeolite ZSM-5 was obtained.

[0055]

Example 1 (1) Synthesis of strontium-type ZSM-5 10 g of strontium sulfate hydrate was dissolved in 100 ml of water, and 10 g of the ammonium-type zeolite ZSM-5 obtained in Reference Example 1 was added to this aqueous solution and refluxed. After keeping it under all night, it was filtered and washed thoroughly with water. Further, it was dried in an electric dryer at 100 ° C. for 16 hours. As a result of chemical analysis, the dry powder contained 1.43% of strontium. Therefore, in this product, 70% of the cation sites based on alumina are occupied by strontium.

(2) Synthesis of silicon oxide-supported strontium type zeolite-5 5.0 g of the strontium type ZSM-5 powder obtained in the above (1) was filled in a reaction bed of a fixed pressure fixed bed flow system and charged under a nitrogen stream of 400 The temperature was raised to ° C. Then, nitrogen gas passed through ethyl silicate was supplied at a rate of 100 ml / min for 96 hours. After the supply of the nitrogen gas containing ethyl silicate was stopped, the temperature of the reaction tube was raised to 500 ° C. under a nitrogen stream and then kept for 24 hours under an air stream. The powder was taken out from the atmospheric pressure fixed bed flow type reaction tube and the weight was measured to find 5.6 g. By this operation, strontium type zeolite ZSM-5 carrying 12% by weight of silicon oxide was prepared.

(3) Preparation of alumina supporting platinum and tin 1.00 g of commercially available chloroplatinic acid hexahydrate was dissolved in 50 ml of water. 50 ml of 86.4 mg of stannous chloride dihydrate
Precisely weigh in a round-bottomed flask and add 2 ml of hydrochloric acid and 1
It was dissolved in 5 ml of water, and 1.33 ml of the above chloroplatinic acid aqueous solution was further added. 5 g of γ-alumina gel (ACP-1: manufactured by Catalyst Kasei Co., Ltd.) was added to the dark reddish orange aqueous solution, and the mixture was kept at 50 ° C. for 5 hours while stirring. Then 10
Alumina containing 0.2% platinum and 0.9% tin was prepared by drying in an electric dryer at 0 ° C for 16 hours.

(4) Preparation of Ethylbenzene Decomposition Catalyst To the silicon oxide-supporting strontium-type zeolite ZSM-5 obtained in (2), an equal weight of the platinum- and tin-supporting alumina obtained in (3) was added and sufficiently mixed. Molded to ~ 20 mesh size. This composition is referred to as catalyst A.

[0059]

Reference Example 2 (Preparation of xylene isomerization catalyst) JP-A-58
-Pt / Ba-ZSM-according to the catalyst No. D-2 described in Table 3 of Example 4 described in JP-A-210856.
5 was prepared.

23.6 g of barium chloride was dissolved in 200 ml of water, and 10 g of the barium chloride obtained in Reference Example 1 of the present specification was dissolved therein.
NH ₄ ⁺ ZSM-5 was added. Ion exchange was performed under reflux for 6 hours. This operation was repeated once more, then filtered and washed thoroughly with water. Then, it is dried in an electric dryer at 200 ° C. for 8 hours, and further baked in an electric muffle furnace at 450 ° C. for 8 hours to be B
a-ZSM-5 was obtained.

1.0 g of commercially available chloroplatinic acid hexahydrate was added to 5
It was dissolved in 0 ml of water. Water 2 to 0.68 ml of the above aqueous solution
0 ml was added, and 5 g of Ba-ZSM-5 was suspended therein. After holding at 70 ° C for 6 hours, the solvent was distilled off at 40 ° C using a rotary evaporator. Pt / Ba-ZSM-5 was obtained by using an electric dryer, drying at 200 ° C. for 8 hours, and further firing in an electric muffle furnace at 400 ° C. for 8 hours while circulating air. This product had a platinum content of 0.1% by weight and a barium content of 1.1% by weight.

An equal amount of γ-alumina (manufactured by Wako Pure Chemical Industries, Ltd.) was added to this catalyst composition and mixed well, and then molded into a 10 to 20 mesh. This composition is referred to as catalyst B.

[0063]

Example 2 2.0 g of the catalysts A and B in the form of pellets prepared in Example 1 and Reference Example 2 were filled in a flow type fixed bed reactor. After raising the temperature under a nitrogen stream until it reached 400 ° C, it was replaced with a hydrogen stream at 400 ° C, and 2
Reduction of platinum was carried out by holding for a time. Then a hydrocarbon mixture consisting of a major amount of the xylene isomer mixture and ethylbenzene was fed. Reaction temperature is 380-42
Change the range of 0 ℃, the raw material supply amount is 20g / h (WHS
V value 10 HR ⁻¹ ), hydrogen / raw material mixture molar ratio was 2, and reaction pressure was 120 psia. The product liquid at each reaction temperature was collected and analyzed by gas chromatography.

[0064]

Example 3 Pelletized catalyst prepared in Reference Example 2.
0 g was charged into a flow type fixed bed flow reactor. Then, the pellet-shaped catalyst A2.0 prepared in Example 1 was used as the catalyst B.
The top of the. As in Example 1, the platinum in the catalysts A and B was reduced and then the reaction was carried out. The reaction temperature is 380 ° C,
The raw material feed rate was 20 g / hr (WHSV value 5 HR ^-1 ), the hydrogen / raw material mixture molar ratio was 2, and the reaction pressure was 120 psia. The product liquid was collected and analyzed by gas chromatography.

The results of Examples 2 and 3 are shown in Table 1.

The results in Table 1 show that the catalyst A of the present invention decomposes ethylbenzene more efficiently at a lower temperature while suppressing the loss of xylene as compared with the existing xylene isomerization catalyst B, and the catalyst A of the present invention and the existing xylene. It is shown that the combination with the isomerization catalyst B can efficiently decompose ethylbenzene while further suppressing xylene loss, and further efficiently carry out the xylene isomerization reaction.

The characteristic values in the table are defined by the following equations.

[0068]

[Equation 1]

[0069]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Namamame 77 Kitayoshida-cho, Matsuyama-shi, Ehime Prefecture Teijin Limited Matsuyama Office

Claims (8)

[Claims] 1. A hydrocarbon feedstock comprising a major amount of a xylene isomer mixture and ethylbenzene is subjected to a xylene isomerization reaction, a specific xylene isomer is isolated from the resulting isomerization reaction mixture, and the remaining hydrocarbon A continuous xylene isomerization process comprising recycling the mixture to the xylene isomerization reaction, wherein the hydrocarbon feedstock or xylene isomerization mixture is (a) silicon oxide loaded silica / alumina (molar ratio). ) Is at least 10 and at least 10% of its cation sites are occupied by a metal cation selected from alkaline earth metals, and (b) a refractory amorphous form carrying platinum and tin. Treated in the presence of a catalyst consisting of an inorganic oxide, in the hydrocarbon feed or in the xylene isomerization reaction mixture Isomerization process of xylene, characterized in that allowed to decompose ethylbenzene in. 2. The method for isomerizing xylene according to claim 1, wherein the crystalline aluminosilicate zeolite is ZSM-5. 3. The method for isomerizing xylene according to claim 1, wherein the alkaline earth metal is strontium. 4. A crystalline aluminosilicate zeolite in an amount of 0.01 to 20% by weight based on the weight of the zeolite.
The method for isomerizing xylene according to claim 1, wherein the catalyst having silicon oxide supported therein is used. 5. The method for isomerizing xylene according to claim 1, wherein the refractory amorphous inorganic oxide is γ-alumina. 6. The isomerization of xylene according to claim 1, wherein a catalyst in which 0.005 to 5% by weight of platinum is supported on the refractory inorganic oxide, based on the weight of the inorganic oxide, is used. Method. 7. The isomerization of xylene according to claim 1, wherein a catalyst in which a refractory inorganic oxide is loaded with 0.1 / 1 to 10/1 tin in terms of tin / platinum atomic ratio is used. Method. 8. The method for isomerizing xylene according to claim 1, wherein the weight ratio of platinum- and tin-supported refractory amorphous inorganic oxide / zeolite is in the range of 0.05 to 5.