JP3451731B2 - Xylene isomerization catalyst and xylene isomerization method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention In the present invention, xylenes containing ethylbenzene are contacted with a specific catalyst in the gas phase in the presence of hydrogen to isomerize the xylenes and to convert ethylbenzene to other aromatic hydrocarbons. It is related to the conversion to.

[0002]

2. Description of the Prior Art Of the xylene mixtures, the currently industrially important ones are p-xylene and o-xylene. p-
As a raw material for synthetic fiber polyester, xylene has been significantly increased in demand so far. It is expected that the trend will not change in the future. O-xylene is used as a raw material for a plasticizer phthalate ester of polyvinyl chloride. However, at present, the demand for o-xylene is smaller than that for p-xylene. On the other hand, m-xylene has almost no industrial use. From this, it is industrially very important to convert o-xylene and m-xylene into p-xylene.

Since the boiling points of xylene mixtures are close to each other, especially the boiling points of p-xylene and m-xylene are very close, it is economically disadvantageous to separate p-xylene by a distillation method.

Therefore, industrial separation of p-xylene has been carried out by cryogenic separation utilizing the difference in melting points. In the case of the cryogenic separation method, the recovery rate of p-xylene per pass is limited due to the eutectic point, which is at most (60%) / pass. As a result, the p-xylene concentration in the raffinate fluid after recovering the p-xylene is fairly high.

On the other hand, Japanese Patent Publication No. 49-17246, 49-2
8181, 50-10547, 50-11343, 51
An adsorption separation method has been developed as a new separation technology as disclosed in Japanese Patent Publication No. 46093/460. In this adsorption separation method, 100% of p-xylene can be recovered per pass. That is, p- in the raffinate fluid after adsorption separation
The xylene concentration is extremely low and theoretically becomes zero.

So far, o-xylene has generally been separated by precision distillation.

The remaining raffinate fluid from which p-xylene and o-xylene have been separated in this way is sent to the isomerization step, and m-xylene and / or o-xylene have a p-xylene concentration close to the thermodynamic equilibrium composition. Is isomerized to
It is then mixed with fresh feedstock and sent to the separation process and the cycle is repeated. In such a combination process, when the remaining raffinate fluid obtained by separating p-xylene by cryogenic separation is fed to the isomerization step, the concentration of p-xylene in the raffinate fluid is relatively high as described above. , The raffinate fluid after separation by the p-xylene adsorption separation method has a very low p-xylene concentration. Therefore, the reaction in the isomerization step requires greater severity in the latter case.

[0008] In general, xylene raw materials that are industrially used are modified oil type xylene obtained by improving naphtha, and then aromatic extraction and fractional distillation, or a cracked gasoline produced as a by-product by the thermal decomposition of naphtha. It is a cracked oil-based xylene obtained by group extraction and fractional distillation. The characteristic feature of cracked oil type xylene is that the concentration of ethylbenzene is twice or more higher than that of the reformed oil type. The typical composition is shown in Table 1.

[0009]

[Table 1]

As described above, generally, a considerable amount of ethylbenzene is present in the xylene mixture, but if ethylbenzene is not removed by any means, ethylbenzene accumulates as the separation step and the isomerization step are recycled, This is an unfavorable situation in which the concentration increases. Under these circumstances, it is the current situation that reformed oil-based xylene is preferably used as a fresh feed material, but in any case, it is necessary to reduce the ethylbenzene concentration, and some methods are industrially used. Was carried out in
Several methods have also been proposed. The methods are roughly classified, one is a method of separating ethylbenzene as it is, and the other is a method of converting it into another useful compound by a reaction.

As a method for separating ethylbenzene, a distillation method can be mentioned. In the case of this method, since the boiling point difference with xylenes is small, it is necessary to use ultra-precision distillation, which requires an enormous industrial investment, and the operating cost is high.
This is an economically disadvantageous method. Furthermore, JP-A-52-102
As disclosed in Japanese Patent No. 23, etc., there is a proposal to separate ethylbenzene by an adsorption separation method, but the separation performance is not sufficiently satisfactory.

Other methods of removing ethylbenzene include several methods of converting it into other useful components. The most typical method is Japanese Patent Publication No. 49-4660.
6,49-47733,51-15044,51-36
253, JP-A-54-16390, a method of converting ethylbenzene into xylene. However, in this method, it is essential that the catalyst contains platinum, which is an extremely expensive noble metal.

Further, in order to convert ethylbenzene to xylene, intervening non-aromatic components such as naphthene and paraffin are required in the reaction mechanism, and the concentration existing in the product is in the range of several% to several tens%. It extends to.
Furthermore, since the conversion rate of ethylbenzene is controlled by thermodynamic equilibrium (Table 2), there are drawbacks such as its limit.

[0014]

[Table 2]

Further, a method of converting ethylbenzene to xylene by a mechanism different from the method of using platinum is disclosed in Japanese Patent Publication No. 53-41658. This method uses a catalyst containing ZSM-5, ZSM-12, ZSM-21 zeolite, but this method has a drawback that xylene is slowly isomerized. In particular, in order to isomerize a xylenes having a low p-xylene content, for example, a raffinate fluid obtained by adsorbing and separating p-xylene, it is necessary to highly isomerize m-xylene and also o-xylene to p-xylene. It is a fatal defect to isomerize such xylenes having a low p-xylene content.

A method of changing ethylbenzene to a component other than xylene has been proposed in Japanese Examined Patent Publication No. 53-41657 and Japanese Unexamined Patent Publication No. 52-148028. This method is to isomerize xylene and at the same time to convert ethylbenzene into benzene and diethylbenzene by a disproportionation reaction, and to separate them using a large boiling point difference with xylene. The benzene thus obtained is in great demand as a raw material for synthetic fiber nylon, but there is almost no demand for diethylbenzene, and it is economically disadvantageous because it needs to be converted into another useful compound.

[0017]

The object of the present invention is to convert an aromatic hydrocarbon by deethylating ethylbenzene to benzene and, at the same time, highly isomerizing xylene and improving the selectivity of the reaction. To provide a way to do.

[0018]

In order to achieve the above object, the present invention is a zeolite in which the size of the main cavity is a 10-membered oxygen ring and is larger than the pore inlet diameter of the zeolite.
Treated with a silane compound and / or titanium compound
Provide a silica layer and / or a titania layer on the outer surface.
And by having a pore inlet diameter that is smaller than said zeolite specific pore inlet diameter, and to include hydrogenated metal component co
In addition, the zeolite is silica sol, titania sol or
A zeolite magnitude of isomerization catalyst and the main cavity of xylenes and characterized by being molded by using a zirconia sol binder consisting of oxygen 10-membered ring, 該Ze
Silane compound larger than the pore entrance diameter of olite and /
Or treated with a titanium compound to form a silica layer on the outer surface and
/ Or by providing a titania layer , having a pore inlet diameter smaller than the pore inlet diameter peculiar to the zeolite,
In addition to containing the hydrogenated metal component , the zeolite is
Vine casol, titania sol or zirconia sol
There is provided a method for isomerizing xylenes, which comprises contacting a catalyst formed by using a catalyst in the presence of hydrogen with xylenes containing ethylbenzene having a p-xylene concentration lower than the equilibrium concentration.

The catalyst used in the present invention is a silica layer and / or
Alternatively, the size of the main cavity including the titania layer is 10
A zeolite containing a member ring, but the size of the main cavity of which is a 10-membered oxygen ring, is disclosed in, for example, US Pat.
true271, 30 March, 437 (197)
ZSM-5 whose crystal structure is described in 8), and ZSM- described in British Patent No. 1334243.
8, Z described in JP-B-53-23280
SM-11, ZSM-21 described in U.S. Pat. No. 4,001,346, ZSM-35 described in JP-A-53-144500, JP-A-51-6729.
Zeolite Zeta 1 described in JP-A No. 9 and Zeolite Zeta 3 described in JP-A No. 51-67298 can be used. The silica / alumina ratio is not particularly limited, but is preferably 35 or more.

The zeolite most preferably used in the present invention is synthesized by the method described in JP-B-61-8011. That is, an aqueous reaction mixture containing a silica source, an alumina source, an alkali source, and an aliphatic carboxylic acid or a salt thereof is used in the following composition range: more preferable range: SiO ₂ / Al ₂ O ₃ 5 to 500 5 to ₂₀₀ H ₂ O / SiO ₂ 5 _{^{~500 10~50 OH - / SiO 2 0.01~1.0}} 0.02~0.8 a / Al 2 O 3 were prepared to enter the 0.1-200 0.5-100, crystals It can be produced by reacting until produced. As the silica source, for example, silica sol, silica gel, silica yellow gel, silica hydrogel, silicic acid, silicic acid ester, sodium silicate or the like can be used.

As the alumina source, sodium aluminate,
Aluminum sulfate, aluminum nitrate, alumina sol,
Alumina gel, activated alumina, gamma alumina, alpha alumina, etc. are used. As the alkali source, caustic soda, caustic soda, etc. are used, but caustic soda is preferred. These alkali sources are OH in the system.
^- is preferably added as present in the composition.

The aliphatic carboxylic acid or its salt has 1 to 12 carbon atoms, preferably 3 to 6 carbon atoms, and more specifically glycolic acid which is a monobasic oxycarboxylic acid,
Lactic acid, hydroacrylic acid, oxybutyric acid or salts thereof, dibasic and polybasic oxycarboxylic acids tartronic acid, malic acid, tartaric acid, citric acid or salts thereof, monobasic carboxylic acids such as formic acid, acetic acid, propionic acid, Butyric acid, valeric acid, acrylic acid, crotonic acid, methacrylic acid or salts thereof, dibasic and polybasic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid or their Salt can be used. As the salt, a water-soluble salt is preferable.
These aliphatic carboxylic acids or salts thereof can be used alone or in admixture of two or more.

The thus-prepared aqueous reaction mixture is crystallized in the form of a slurry as uniform as possible in a closed vessel such as an iron, stainless steel or Teflon-lined autoclave. The reaction conditions for crystallization are not particularly limited, but the reaction temperature is preferably 80 to 250 ° C., more preferably 100 to 20.
The reaction time is 0 ° C. and the reaction time is preferably 5 hours to 30 days,
More preferably, it is 10 hours to 10 days. The reaction mixture is preferably stirred continuously or periodically during crystallization to maintain a uniform state. The crystallized reaction product is taken out from the closed container after cooling, washed with water,
Filter and dry if necessary. A typical X-ray diffraction pattern of the zeolite thus synthesized is shown in Table 3
Is the street.

The X-ray diffraction pattern was measured according to a usual method. That is, for the X-ray irradiation, a diffraction pattern is obtained with a K-α ray of copper using a Geiger equipped with a recording device and a counter spectroscope. From this diffraction pattern, a relative intensity of 10
0I / I ₀ (I ₀ is the strongest line) and the lattice spacing d
(Unit: nm) is calculated.

[0025]

[Table 3]

The synthesized zeolite is usually molded by extrusion after mixing with a binder. In the present invention, Rikazoru as a <br/> binder, it is important to use a titania sol or di <br/> Rukoniazoru. Especially, silica silica is most preferably used. The amount of binder added is 70% or less, preferably 40% or less. Besides binder, shea silica, zirconia or titania A powder
A purpose and improve moldability, as a good carrier for hydrogenation metals may be added. In addition to extrusion, such as this may be using a compression molding or the like.

The catalyst of the present invention has a main cavity size of oxygen 10
Consisting of a member ring, including a zeolite having a pore entrance diameter smaller than the pore entrance diameter peculiar to this zeolite,
Such a zeolite can be obtained by treating the above-mentioned zeolite or a molded product thereof with, for example, a silane compound and / or a titanium compound larger than the pore entrance diameter of zeolite and calcining. The silane compound and titanium compound used are preferably organic silane compounds and organic titanium compounds. As the organic silane compound and / or organic titanium compound used, a silane and / or titanium alkoxide compound is preferably used. For example, methoxysilane, ethoxysilane, propoxysilane, methoxytitanium, ethoxytitanium, propoxytitanium, isopropoxytitanium and the like can be used.

Various methods can be adopted as the processing method. It can be obtained by bringing the silane compound and / or the titanium compound into contact with zeolite dehydrated in the gas phase or the liquid phase. The method of contacting in the gas phase is, for example, that of Ito et al. (Journal of the Chemical Society of Japan, 1989,
(3), p420) can be adopted. Examples of the method of contacting in a liquid phase include a method of putting zeolite powder or a molded product in an organic solvent in which an organic silane compound and / or an organic titanium compound is dissolved, and stirring or allowing it to stand. The organic solvent used is not particularly limited, but alcohols, ketones and the like are preferably used. Among them, methanol, ethanol, propanol, isopropanol, butanol, acetylacetone, acetone and the like are preferably used. The contact temperature is preferably not higher than the boiling point of the solvent and not lower than the freezing point. It can be processed well near room temperature. The zeolite to be treated may be in the form of powder or a molded product. In any case, it is preferable to dehydrate before processing. Dehydration is performed, for example, by baking at a temperature of 350 ° C. or higher. The firing atmosphere is not particularly limited, but is usually performed in air, nitrogen, or vacuum. The catalyst treated with the organosilane compound and / or the organotitanium compound in the liquid phase is subjected to solid-liquid separation after the treatment, followed by drying and firing. For solid-liquid separation, filtration, decantation, centrifugation, etc. are usually adopted. The drying condition is not particularly limited, but it is performed, for example, at 50 to 200 ° C. in air, nitrogen, or vacuum. The firing is preferably performed in air at a temperature of 300 ° C. or higher. If there is a risk of explosion, a nitrogen atmosphere or vacuum conditions may be used during the temperature raising process. The silica layer and /
Alternatively, a titania layer can be provided.

The catalyst of the present invention is a zeolite having a main cavity containing a silica layer and / or a titania layer and having a 10-membered oxygen ring, and has a pore inlet diameter smaller than the pore inlet diameter peculiar to the zeolite. Must include a zeolite with.

Whether the pore inlet diameter of zeolite has become smaller than the pore inlet diameter peculiar to the zeolite can be confirmed by measuring the adsorption rate of ortho-xylene. It can be said that if the adsorption rate of ortho-xylene is slower than that of the original zeolite before the pore inlet diameter is made smaller, the pore inlet diameter becomes smaller. The adsorption rate of ortho-xylene is compared as follows. A zeolite containing a silica layer and / or a titania layer and the like that have been subjected to the same ion exchange treatment and a zeolite not containing a silica layer and / or a titania layer are prepared. The two zeolite types are the same. After compression molding each zeolite, 5
Baking at 00 ° C, crushing, sieving, 20 to 32
Use the mesh as a sample. This sample in vacuum 4
After pretreatment at 00 ° C., the sample is placed in an atmosphere having a vapor pressure of ice water of paraxylene or orthoxylene (0 to 2 ° C.), and the weight change of the sample is measured. At this time, the sample is kept at 120 ° C. First, the equilibrium adsorption amount of paraxylene is measured. The equilibrium adsorption amount of paraxylene can be measured in a relatively short time. Next, the time required to adsorb 30% ortho-xylene of the equilibrium adsorption amount of para-xylene is measured. If this time is longer than that of zeolite that does not include a silica layer and / or a titania layer, it can be said that the pore inlet diameter has decreased. This measurement is usually carried out only with zeolite, but it may also be carried out for those molded with a binder. When the treatment method of the catalyst is clear, the same treatment is applied only to the zeolite, and the molded body is also judged using the data.

Usually, in the isomerization of xylene, in order to isomerize ortho-xylene or meta-xylene having a large molecular diameter into para-xylene having a small molecular diameter, the pore inlet diameter is made small and ortho-xylene or meta-xylene is used as a zeolite pore. Making it difficult to enter is a disadvantage for the isomerization reaction. However, Japanese Patent Publication No. 62-56138 discloses a method in which a zeolite having a large crystallite size, that is, a zeolite in which ortho-xylene and meta-xylene are difficult to diffuse in the pores is used for isomerization of xylene. This favors the deethylation of ethylbenzene rather than the isomerization of xylene. However, since the entrance diameter of the pores is not controlled in this method, it is considered that a large amount of orthoxylene and metaxylene penetrate into the pores, and the diffusion of ethylbenzene in the pores is alienated. Therefore, sufficient ethylbenzene deethylation activity cannot be obtained. In the method of the present invention, since the ortho-xylene and the meta-xylene are prevented from entering the pores at the entrance to a certain extent, the concentration of ethylbenzene in the pores of the zeolite becomes high, and the diffusion of ethylbenzene in the pores is difficult to be excluded. Is special public Sho6
It is remarkably improved as compared with the method disclosed in JP-A 2-56138. Therefore, since the reaction temperature can be lowered, the catalyst life and the xylene recovery rate are remarkably improved.

In the catalyst of the present invention, ortho-xylene and meta-xylene hardly penetrate into the pores of the zeolite, so that the isomerization of ortho-xylene and meta-xylene to para-xylene is slightly suppressed. When it is desired to proceed with this isomerization, it is preferable to use it in combination with another zeolite whose pore inlet diameter is not reduced. The zeolite used in combination here is not particularly limited, but mordenite, MTW, and the above-mentioned zeolite in which the size of the main cavity is a 10-membered oxygen ring are preferably used. Among them, the most preferably used is a zeolite having a main cavity size of an oxygen 10-membered ring. The silica / alumina ratio is not particularly limited, but a ratio smaller than 35 is preferably used. The method of combination is not particularly limited, but it is preferable that the size of the main cavity including the silica layer and / or the titania layer is a zeolite having an oxygen 10-membered ring and is smaller than the pore inlet diameter peculiar to this zeolite. Silica / alumina after contacting a catalyst having a pore inlet diameter and containing a zeolite (A) containing a hydrogenated metal component with xylenes containing ethylbenzene having a p-xylene concentration lower than the equilibrium concentration in the presence of hydrogen This is a method in which the size of the main cavity having a ratio of less than 35 is brought into contact with a catalyst containing zeolite (B) consisting of a 10-membered oxygen ring. In this case, the abundance ratio of both zeolites is preferably determined by the balance of the activities of both catalysts. For example, when both zeolites are reacted in the same amount and the ethylbenzene conversion rate is insufficient, the amount of zeolite (A) may be increased relative to that of zeolite (B). Since the activities of zeolite (A) and zeolite (B) can be controlled by changing the respective preparation conditions, the optimum use amount ratio of zeolite cannot be determined unconditionally.

The catalyst used in the present invention does not have solid acidity only by molding or adding a silica layer or a titania layer. When used in the conversion reaction of aromatic hydrocarbons, it is necessary to impart solid acidity to the zeolite to give it an acid form. As is well known, the acid type zeolite has hydrogen ions or divalent or higher polyvalent cations such as rare earth ions and alkaline earth metal ions as cations in the zeolite, and these are usually sodium ions and the like. It can be obtained by ion-exchange of at least a part of the monovalent alkali metal ion of 1 with hydrogen ion, ammonium ion, or polyvalent cation, and then firing. Such a treatment is called an ion exchange treatment.

In the present invention, an ion exchange treatment is preferred in which treatment with a solution containing an acid and / or ammonium salt compound is carried out, and hydrogen ions and / or hydrogen ion precursors are introduced into the zeolite. The ion exchange treatment is generally performed with an aqueous solution. The acid that can be used is an inorganic acid or an organic acid, but the inorganic acid is more common. Examples of the inorganic acid include hydrochloric acid, nitric acid, phosphoric acid, carbonic acid and the like, but of course, any other acid may be used as long as it contains hydrogen ions. When an inorganic acid is used, it is not preferable to treat it with a solution having a too high concentration because the crystal structure is destroyed. The concentration of the acid used preferably varies greatly depending on the type of the acid, so it is difficult to determine uniquely, and it is necessary to pay sufficient attention so that the crystal structure will not be destroyed during use.

As the ammonium salt compound, inorganic ammonium salts such as ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium carbonate and aqueous ammonia, or ammonium salts of organic acids such as ammonium formate, ammonium acetate and ammonium citrate can also be used. Are more preferably inorganic ammonium salts. The concentration of the ammonium salt used is preferably a solution of 0.05 to 4 N, but more preferably about 0.1 to 2 N. As a method for ion-exchanging zeolite with an acid and / or ammonium salt solution, either a batch method or a flow method is preferably used. When the treatment is carried out in a batch system, the solid-liquid ratio is preferably at least enough to contact the liquid with the zeolite, preferably at least about 1 liter / kg. Processing time is 0.1 to 72
Time is sufficient, preferably 0.5 to 24 hours. The treatment temperature may be equal to or lower than the boiling point, but it is preferably heated to accelerate the ion exchange rate. When the treatment is carried out by the flow system, a fixed bed system, a fluidized bed system or the like can be used, but it is necessary to take care so that the fluid does not flow unevenly or the ion exchange treatment does not become non-uniform. The ion-exchanged zeolite is then washed with water.
Ion-exchanged water or distilled water is preferably used as the washing liquid, and the washing may be either batch type or flow type.

In this way, hydrogen ions and / or ammonium ions which are hydrogen ion precursors are introduced into the zeolite. Hydrogen zeolite is a zeolite in which the size of the main cavity including the silica layer and / or the titania layer is a 10-membered oxygen ring, and the pore inlet diameter is smaller than the pore inlet diameter peculiar to the zeolite. And / or cations other than hydrogen ion precursors may be present, barium ions and / or strontium ions being most preferably used as such cations. It is preferable that at least a part of cation sites other than hydrogen ions is exchanged with lithium ions in the zeolite in which the size of the main cavity does not include the silica layer and / or the titania layer and has a 10-membered oxygen ring.

The method for obtaining the zeolite in which the cation sites other than hydrogen ions are substantially exchanged with cations other than hydrogen ions is not particularly limited, but
For example, the above-mentioned hydrogen ion and / or
Alternatively, a method of performing an ion exchange treatment for introducing a cation other than hydrogen ions (for example, barium ion, lithium ion, strontium ion) at the same time as, or before or after the ion exchange treatment for introducing ammonium ion which is a hydrogen ion precursor. can give. The ion exchange treatment for introducing cations other than hydrogen ions (for example, barium ion, lithium ion, strontium ion) is generally performed in an aqueous solution. These cations are generally used in inorganic salts such as nitrates, chlorides, sulfates, acetates and the like.

It is essential that the catalyst of the present invention contains a hydrogenated metal component. The most preferably used hydrogenated metal component is rhenium. Examples of the method of adding these metals include a kneading method, an impregnation method, and a physical mixing method of powders. Rhenium can be used as rhenium oxide, perrhenic acid, ammonium perrhenate,
Examples thereof include rhenium sulfide. The amount by which rhenium can be expected to be added is 0.005% by weight or more in elemental form, based on the total weight of the catalyst. However, if the amount added is too large, side reactions such as hydrogenolysis reaction will occur at the same time.
It is preferably 1% by weight or less. This optimum value depends on the type of metal and reaction conditions.

The catalyst obtained by synthesizing zeolite, reducing the pore inlet diameter, performing ion exchange treatment, and adding a hydrogenated metal component as described above is subsequently dried and then calcined. Drying is performed at 50 to 250 ° C. for 0.1 hour or more, preferably 0.5 to 48 hours. Baking is 300-700 ° C
0.1 hour or more, preferably at 400 to 600 ° C. for 0.1 hour.
It is carried out for 5 to 24 hours. In addition, by such firing,
Ammonium ions introduced by the ion exchange treatment are converted to hydrogen ions, and hydrogen ions are further converted to the decation type when the calcination temperature is further raised, but it goes without saying that such a catalyst can also be used sufficiently. is there.

The catalyst prepared as described above is used under the following reaction conditions. That is, the reaction operating temperature is 3
The temperature is from 00 to 600 ° C, preferably from 350 to 550 ° C. The reaction operation pressure is from atmospheric pressure to 10 MPa, preferably from atmospheric pressure to 5 MPa. Time factor W / F (g-cat * hr / g-mol feedstock) which means contact time of reaction
(W: catalyst weight, F: mol feedstock per hour) is 0.1 to 200, preferably 1 to 100. Hydrogen in the reaction system is essential. If the hydrogen concentration is too low, the deethylation reaction of ethylbenzene will not proceed sufficiently, and further, the deposition of carbonaceous material on the catalyst will cause deterioration of the activity over time.
On the contrary, if the hydrogen concentration is too high, the hydrogenolysis reaction will increase, which is not preferable. The hydrogen concentration is 1 to 50 in terms of the molar ratio of hydrogen to the feedstock (hydrogen / F) in the reaction system. This optimum value depends on the type and amount of hydrogenated metal component.

A xylene mixture containing ethylbenzene is used as a feed material, but the concentration of ethylbenzene in the xylene mixture is not particularly limited. The para-xylene concentration in the xylene mixture is usually lower than the thermodynamic equilibrium concentration. The feedstock may contain other aromatic components such as benzene, toluene, trimethylbenzene, ethyltoluene, diethylbenzene, ethylxylene and the like. The present invention will be described below with reference to examples.

Example 1 A zeolite having a silica / alumina ratio of 50 was prepared by the method described in Example 1 of JP-A-59-62347.
The zeolite had an X-ray diffraction pattern as shown in Table 3.

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

Comparative Example 1 100 g of the zeolite produced in Example 1 on an absolute dry basis
Weigh, add 200 g of water, add 60 g of barium nitrate and 10 g of ammonium chloride, and add 80 g with occasional stirring.
Hold at 4 ° C for 4 hours. Then, it was sufficiently washed with warm water of 80 ° C., dried at 120 ° C. overnight and tableted. 550 after molding
Baked at ° C. This was crushed and sieved, and a 20-32 mesh sample was used as a sample for adsorption measurement. The sample for adsorption measurement was baked at 500 ° C. overnight, then allowed to cool in a desiccator, weighed quickly and filled in an adsorption measurement device.
While pulling a vacuum with a rotary pump in the measuring device, 40
Raise the temperature to 0 ° C and pull it with a diffusion pump at 400 ° C for 1
Held for hours. Then, the temperature of the measurement part was lowered to 120 ° C. and kept constant at 120 ° C. After that, the vacuum line was closed and exposed to ice water temperature (about 0 ° C.) of para-xylene vapor pressure. After 30 minutes, the paraxylene adsorption had almost reached equilibrium. The amount of adsorption at that time was 4.1 wt% with respect to the zeolite. When the adsorption rate of ortho-xylene was measured in the same manner as described above, it took 1700 minutes to adsorb 30% of the para-xylene equilibrium adsorption amount.

Example 2 The zeolite of the product of Example 1 was calcined at 500 ° C. for 1 hour, allowed to cool in a desiccator, weighed 100 g therein, and put in 500 g of ethanol and stirred. 20 g of tetraethyl orthosilicate was added, stirred for 1 hour, filtered, and dried at 120 ° C. overnight. After baking at 500 ° C., 100 g was weighed on an absolutely dry basis, 200 g of water was added, 60 g of barium nitrate and 10 g of ammonium chloride were added, and the mixture was kept at 80 ° C. for 4 hours with occasional stirring. Then, it was sufficiently washed with warm water of 80 ° C., dried at 120 ° C. overnight and tableted. After molding, it was baked at 520 ° C. This was crushed and sieved, and a 20-32 mesh sample was used as a sample for adsorption measurement. The adsorption measurement was performed by the same method as in Comparative Example 1. The para-xylene adsorption reached almost equilibrium in 30 minutes, and the adsorption amount was 4.1 wt% with respect to the zeolite. When the adsorption rate of ortho-xylene was measured in the same manner as described above, it took 4500 minutes to adsorb 30% of the equilibrium adsorption amount of para-xylene. It can be seen that the pore diameter of the zeolite treated with titanium is smaller than that of the original zeolite.

Example 3 The zeolite of the product of Example 1 was calcined at 500 ° C. for 1 hour, allowed to cool in a desiccator, weighed 100 g therein, and put in 500 g isopropanol and stirred. 12
0 g of tetraisopropoxy titanium was added, and the mixture was stirred for 1 hour, filtered, and dried at 120 ° C. overnight. After baking at 500 ° C., 100 g was weighed on an absolutely dry basis, 200 g of water was added, 60 g of barium nitrate and 10 g of ammonium chloride were added, and the mixture was kept at 80 ° C. for 4 hours with occasional stirring. Then, it was sufficiently washed with warm water of 80 ° C., dried at 120 ° C. overnight and tableted. After molding, it was baked at 520 ° C. This was crushed and sieved, and a 20-32 mesh sample was used as a sample for adsorption measurement. The adsorption measurement was performed by the same method as in Comparative Example 1. The para-xylene adsorption reached almost equilibrium in 30 minutes, and the adsorption amount was 4.1 wt% with respect to the zeolite. When the adsorption rate of ortho-xylene was measured in the same manner as described above, it was found that the adsorption rate of para-xylene was 50%.
It took 00 minutes. It can be seen that the pore diameter of the zeolite treated with titanium is smaller than that of the original zeolite.

[0054]

[0055]

[0056] it was extruded synthetic zeolites in Comparative Example 2 Example 1 mixed with alumina sol. Zeolite is the composition ratio on an absolutely dry basis.
Alumina = 25: 75. After drying overnight at 120 ° C and baking at 500 ° C for 2 hours
60% by weight of barium nitrate and 10% by weight of ammonium chloride were added to double the amount of water and the zeolite contained in the molded product, and the mixture was treated at 80 ° C. for 4 hours. After thoroughly washing with warm water of 80 ° C., 0.2 wt% of Re was loaded on the molded product, dried at 120 ° C. overnight, and baked at 520 ° C. for 1 hour. This catalyst is designated as A-1. Meanwhile, the set of reaction mixtures
The amount of raw material added is adjusted so that the composition becomes SiO ₂ / Al ₂ O ₃ 25 H ₂ O / SiO ₂ 20 OH − / SiO ₂ 0.17 A / Al ₂ O ₃ 2.5 (A is tartaric acid). Example except for
Zeolite was synthesized in the same manner as 1. Produced zeolite
The silica / alumina ratio was about 20. Shown in Table 3
An X-ray diffraction pattern was obtained. Pair with this zeolite
Then, the alumina is adjusted to 15% by weight as alumina.
And then extruded. Dry overnight at 120 ° C
After that, the molded product was baked at 500 ° C for 2 hours, and
Add 10 times by weight 10% by weight aqueous lithium nitrate solution, and add 1 at 80 ℃.
After repeating the time treatment 5 times, Zeo contained in the molded product
The weight of ammonium chloride and catalyst of 1% by weight to light
Two times the amount of water was added, and the mixture was treated at 80 ° C. for 4 hours. 80
After thoroughly washing with warm water at ℃, 0.2% of the molded product
After carrying a considerable amount of Re and drying at 120 ° C overnight, 520 ° C
It was baked in. This catalyst is designated as B-1. The catalyst A-1
And B-1 were packed in a flow reactor at a ratio of 7: 4.
The reaction was carried out under the following reaction conditions so that the feed was in contact with this catalyst first.

Reaction temperature 400 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 60%, PX / (PX + OX + M
X) = 23.5%, xylene (XY) recovery rate 99.2%
Met.

Comparative Example 3 The product zeolite of Example 1 was calcined at 500 ° C. for 1 hour.
And cool in a desiccator and weigh 100g in it
Then, the mixture was put into 500 g of ethanol and stirred. 20g te
Add traethyl orthosilicate, stir for 1 hour and filter.
And dried at 120 ° C. overnight. Baked at 500 ° C
Then, this zeolite was mixed with alumina sol and extruded. That is, on an absolutely dry basis, zeolite: alumina =
1 as alumina for a mixture with a composition ratio of 25:75
Alumina sol was added so as to be 5% by weight and molded. A molded product that was dried at 120 ° C overnight and then calcined at 500 ° C for 2 hours had twice the weight of the molded product and 60 wt% barium nitrate and 10 wt% ammonium chloride based on the zeolite contained in the molded product. Was added and treated at 80 ° C. for 4 hours. After thoroughly washing with warm water of 80 ° C., 0.2 wt% of Re was loaded on the molded product, dried at 120 ° C. overnight, and baked at 520 ° C. for 1 hour. This catalyst is designated as A-2.
It The catalyst A-2 and the catalyst B-1 prepared in Comparative Example 2 were packed in a flow reactor at a ratio of 7: 4. The reaction was carried out under the following reaction conditions so that the feed was in contact with this catalyst first.

Reaction temperature 375 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% Reaction results are EB conversion 60%, PX / (PX + OX + M
X) = 23.5%, xylene (XY) recovery rate 99.5%
Met.

[0060]

Example 4 In the preparation of the catalyst A-2 of Comparative Example 3, alumina was added to silica.
The mosquito, except for changing the A Ruminazoru silica sol by performing the preparation as in Comparative Example 3, to obtain a catalyst A-3. This catalyst
A-3 and the catalyst B-1 prepared in Comparative Example 2 in a ratio of 7: 4
The reaction was carried out under the same conditions as in Comparative Example 3 except that
It was The reaction results were 60% EB conversion, PX / (PX + OX
+ MX) = 23.5%, xylene (XY) recovery rate 99.
It was 8%.

The XY recovery rate was improved as compared with Comparative Example 3 .

Example 5 The product zeolite of Example 1 was calcined at 500 ° C. for 1 hour.
And cool in a desiccator and weigh 100g in it
Then, the mixture was put into 500 g of isopropanol and stirred. 12
Add 0 g of tetraisopropoxy titanium and stir for 1 hour.
After stirring, the mixture was filtered and dried overnight at 120 ° C. Firing at 500 ° C
After that, mix this zeolite with alumina sol and extrude
It was molded. That is, on a dry basis, zeolite: aluminum
Alumina is used for a mixture having a composition ratio of Na = 25: 75.
Alumina sol is added so that it will be 15% by weight.
did. After drying at 120 ° C overnight, baking at 500 ° C for 2 hours
Molded product contains twice as much water as molded product and molded product
60 wt% barium nitrate and 10 wt% of zeolite
Add 4% ammonium chloride and treat at 80 ℃ for 4 hours
did. After thoroughly washing with warm water at 80 ℃,
Supported by 0.2 wt% Re and dried at 120 ° C overnight.
After drying, it was baked at 520 ° C. for 1 hour. This catalyst is called A-4
To do. This catalyst A-4 and the catalyst B-1 prepared in Comparative Example 2
Was charged to the flow reactor at a ratio of 7: 4. The feed is
Under the following reaction conditions, make contact with this catalyst first.
The reaction was carried out.

The reaction results were 63% EB conversion and PX / (P
X + OX + MX) = 23.5% and the xylene (XY) recovery rate was 99.7%.

Example 6 A 50:50 mixture of the zeolite and silica synthesized in Example 1 was molded with silica sol (addition of 15 parts as silica), dried at 120 ° C. overnight, and calcined at 500 ° C. for 2 hours. The mixture was allowed to cool in a desiccator, weighed 115 g therein and put it in 200 g of ethanol. 5 g of tetraethyl orthosilicate was added, and the mixture was allowed to stand for 1 hour, decanted, and then impregnated with silica sol.
Dried overnight. After baking at 500 ° C, 11 on an absolutely dry basis
Weigh 5g, add 200g of water, barium nitrate 30
g, 22 g of ammonium chloride were added, and the mixture was kept at 80 ° C. for 4 hours with occasional stirring. Then, it was sufficiently washed with warm water of 80 ° C., 0.2% by weight of Re was loaded on the molded product, and baked at 520 ° C. for 1 hour. A-5 this catalyst
It The catalyst A-5 and the catalyst B-1 prepared in Comparative Example 2 were charged in a flow reactor at a ratio of 6: 4. The reaction was carried out under the following reaction conditions so that the feed was in contact with this catalyst first.

Reaction temperature 380 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Metaxylene (MX) 60%, Toluene (TL) 2% The reaction results were EB conversion 66%, PX / (PX + OX + M
X) = 23.5%, xylene (XY) recovery rate 99.7%
Met.

Example 7 A 50:50 mixture of zeolite and silica synthesized in Example 1 was molded with silica sol (15 parts by weight of silica was added), dried overnight at 120 ° C., and calcined at 500 ° C. for 2 hours. The mixture was allowed to cool in a desiccator, weighed 115 g therein and put it in 200 g of acetylacetone. After addition of 20 g of tetraethyl orthotitanate, the mixture was left standing for 1 hour, decanted, and then impregnated with silica sol.
Dry overnight at 0 ° C. After baking at 500 ° C. for 2 hours, 115 g was weighed on an absolutely dry basis, 200 g of water was added, 30 g of barium nitrate and 5 g of ammonium chloride were added, and the mixture was kept at 80 ° C. for 4 hours with occasional stirring. After that, it was thoroughly washed with warm water at 80 ° C, and loaded with Re in an amount of 0.2% by weight based on the molded product, dried at 120 ° C overnight, and then at 520 ° C for 1 hour.
Burned for hours. This catalyst is designated as A-6. This catalyst A-
6 and the catalyst B-1 prepared in Comparative Example 2 were charged in a flow reactor at a ratio of 6: 4. The reaction was carried out under the following reaction conditions so that the feed was in contact with this catalyst first.

Reaction temperature 380 ° C., W / F = 30 g · h /
mol, H ₂ /F=3.5 mol / mol, pressure 1MP
a, feed composition: ethylbenzene (EB) 8%, paraxylene (PX) 1%, orthoxylene (OX) 29%,
Meta-xylene (MX) 60%, Toluene (TL) 2% The reaction results were EB conversion 69%, PX / (PX + OX + M
X) = 23.5%, xylene (XY) recovery rate 99.6%
Met.

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

When the xylene containing ethylbenzene is isomerized by using the catalyst of the present invention, the dealkylation activity of ethylbenzene is improved and therefore the reaction temperature can be lowered, so that the xylene recovery can be achieved by suppressing the side reaction. It is possible to improve the efficiency and extend the life of the catalyst.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-6-116173 (JP, A) JP-A-6-56710 (JP, A) JP-A-62-128031 (JP, A) JP-A-62-162 169736 (JP, A) JP 61-69738 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 C07C 5/27 C07C 15/08 C07B 61/00

Claims (17)

(57) [Claims] 1. A zeolite having a 10-membered oxygen ring whose main cavity size is larger than the pore inlet diameter of the zeolite.
Treated with a fine silane compound and / or a titanium compound
A silica layer and / or a titania layer on the outer surface
By having a pore inlet diameter that is smaller than said zeolite specific pore inlet diameter, and to include hydrogenated metal component
Both, the zeolite is silica sol, titania sol or
Is a catalyst for isomerizing xylenes, which is obtained by molding using zirconia sol as a binder . 2. Zeolite with silica sol as a binder
The xylene isomerization catalyst according to claim 1, which is molded by using the catalyst. 3. A zeolite in which the size of the main cavity is a 10-membered oxygen ring is 1.12 ± 0.
02, 1.01 ± 0, 02, 0.386 ± 0.008,
0.372 ± 0.008 and 0.365 ± 0.008
The xylene isomerization catalyst according to claim 1 or 2, which has an X-ray diffraction pattern having a peak at the position. Wherein the silane compound and / or xylenes isomerization catalyst according to claim 1 or 2 titanium compound is characterized in that an organic silane compound and / or an organotitanium compound. 5. The xylene isomerization catalyst according to claim 4, wherein the organosilane and / or organotitanium is a silane and / or titanium alkoxide compound. 6. A cation of at least a part of zeolite
Sites are exchanged with hydrogen ions and alkaline earth metals
6. The method according to any one of claims 1 to 5, characterized in that
Isomerization catalyst of xylenes described. 7. The hydrogenated metal component is rhenium.
The xylene isomerization catalyst according to any one of claims 1 to 6, which is a characteristic of the catalyst. 8. The size of the main cavity is composed of a 10-membered oxygen ring.
Zeolite that is larger than the pore entrance diameter of the zeolite
Treated with a fine silane compound and / or a titanium compound
A silica layer and / or a titania layer on the outer surface
By,該Ze zeolite smaller than the specific pore inlet diameter
Has a reduced pore inlet diameter and contains a hydrogenated metal component
Both, the zeolite is silica sol, titania sol or
Is a texture formed by using zirconia sol as a binder.
In the presence of hydrogen, the medium has a p-xylene concentration lower than the equilibrium concentration.
Contact with xylenes containing ethylbenzene
A method for isomerizing xylenes, which comprises: 9. The catalyst zeolite is replaced with silica sol.
Claims characterized in that it is formed by using as an inder
8. The method for isomerizing xylenes according to item 8 . 10. The size of the main cavity of the catalyst is oxygen 10
Zeolite consisting of member rings is displayed in lattice spacing d (nm),
1.12 ± 0.02, 1.01 ± 0, 02, 0.386
± 0.008, 0.372 ± 0.008 and 0.36
X-ray diffraction pattern having a peak at 5 ± 0.008
The method for isomerizing xylenes according to claim 8 or 9, wherein 11. A silane compound used for the catalyst and
And / or the titanium compound is an organosilane compound and / or
Is an organotitanium compound.
Or the method for isomerizing xylenes according to Item 9 . 12. Organosilane and / or organotitanium
Is an alkoxide compound of silane and / or titanium
The method for isomerizing xylenes according to claim 11 , wherein: 13. At least one of the catalyst zeolites.
Part of the cation site is hydrogen ion and alkaline earth gold
Exchanged by genus, characterized in that they are exchanged.
The method for isomerizing xylenes according to any one of 1 . 14. A silica layer and / or a titania layer
Zeolite whose main cavity size contains a 10-membered oxygen ring
And smaller than the pore inlet diameter peculiar to the zeolite.
Having a fine pore inlet diameter and containing a hydrogenated metal,
The zeolite is silica sol, titania sol or zircon
A catalyst molded using Konia sol as a binder,
Ethyl alcohol whose p-xylene concentration is lower than the equilibrium concentration in the presence of hydrogen
After contacting xylenes containing rubenzene, silica
/ Alumina ratio is less than 35 and the size of the main cavity is
A special feature is to make contact with a zeolite consisting of a 10-membered oxygen ring.
The method for isomerizing xylenes according to claim 8, which is used as a characteristic . 15. A silica sol is used as the catalyst zeolite.
Claims characterized by being molded into a binder
Item 15. A method for isomerizing xylenes according to Item 14 . 16. A silica / alumina ratio of less than 35.
And the size of the main cavity is a 10-membered ring of oxygen
At least part of the cation sites of
15. It is replaced with lithium, and it is characterized by the above-mentioned.
The method for isomerizing xylenes according to 1. 17. The hydrogenated metal component is rhenium.
The key according to any one of claims 8 to 16, characterized in that
Method for isomerizing sirens .