JPS62228031A - Method for converting aromatic hydrocarbon - Google Patents

Abstract

PURPOSE:To isomerize xylene and to convert ethylbenzene to other hydrocarbons, by bringing ethylbenzene-containing xylenes into contact with a catalyst containing a specific crystalline aluminosilicate and rhenium in the presence of hydrogen. CONSTITUTION:In isomerizing xylenes into para-xylene and converting ethylbenzene into other aromatic compounds (benzene) by bringing ethylbenzene- containing xylenes into a catalyst in the presence of hydrogen, a catalyst containing a crystalline aluminosilicate obtained from an aqueous reaction mixture containing a silica source, an alumina source, an alkali source and an aliphatic carboxylic acid or a derivative thereof (shown as SiO2, Al2O3, OH<-> and A, respectively) in a composition ratio in the table and rhenium is used as the catalyst and the reaction is carried out at 350-550 deg.C at atmospheric pressure - 50kg/cm<2>G. The preferable hydrogen concentration is in a molar ratio (H2/F) of hydrogen and fed raw material of 3-30.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention involves contacting xylenes containing ethylbenzene with a specific catalyst in the gas phase in the presence of hydrogen to The invention relates to the conversion of ethylbenzene into other aromatic hydrocarbons.

<Prior Art> Among xylene mixtures, currently industrially important ones are disa-xylene and ortho-xylene. Demand for paraxylene has been increasing significantly as a raw material for synthetic fiber polyester. It is expected that this trend will continue in the future. Ortho-xylene is used as a substitute for phthalate ester, a plasticizer for polyvinyl chloride. However, at present, ortho-xylene is less important than para-xylene. On the other hand, there are currently very few industrial uses for meta-xylene. For this reason, it is industrially important to convert meta-xylene and ortho-xylene to para-xylene.

Since the boiling points of xylene mixtures are close, especially since the boiling points of xylene and meta-xylene are very close, it is economically disadvantageous to separate the xylene by distillation.

Therefore, industrial separation of paraxylene has been carried out by cryogenic separation that takes advantage of the difference in melting points. In the case of the cryogenic separation method, there is a limit to the recovery rate of distal xylene per pass due to the eutectic point, which is at most (60%)/(1 pass). As a result, after recovering the rosexylene, it was found that Roughine!
The concentration of baraxylene in the fluid is quite high.

On the other hand, recently special public service No. 49-17246.49-28181
．． 50-105/'1.7.50-11343.51-
As shown in the specification of No. 46093, adsorption separation method was developed as a new separation technique. In this adsorption separation method,
Theoretically, 100% recovery of baraxylene can be achieved per pass. That is, the concentration of paraxylene in the raffinate fluid after adsorption separation is extremely low and theoretically becomes zero.

Ortho-xylene has so far been generally separated by precision distillation methods.

In this way, the remaining raffinate fluid from which para-xylene and ortho-xylene have been separated is sent to an isomerization step, where meta-xylene and 7/or A-rusoxylene are isomerized to a para-xylene concentration close to the thermodynamic equilibrium composition. ,
It is then mixed with fresh feedstock and sent to a separation step, and the cycle is repeated. In such a combination process, when the remaining raffinate fluid from which varaxylene has been separated by cryogenic separation is supplied to the isomerization process, the concentration of varaxylene in the raffinate fluid is relatively high as described above. However, in the case of the raffinate fluid separated by the paraxylene adsorption separation method, the concentration of paraxylene is extremely low. Therefore, the reaction in the isomerization step is required to be more severe in the latter case.

In general, the xylene raw materials used industrially are reformed xylene obtained by improving Buchsa, followed by aromatic extraction and fractional distillation, or by aromatic extraction and fractional distillation of cracked gasoline, which is a by-product from the thermal decomposition of naphtha. This is a cracked oil-based xylene obtained by fractional distillation. A particularly characteristic feature of cracked oil-based xylene is that the concentration of ethylbenzene is more than twice as high as that of reformed oil-based xylene. An example of its typical composition is shown in Table 1.

Table 1 Composition of xylene Generally, a considerable amount of ethylbenzene is present in xylene mixtures, but if ethylbenzene is not removed by some means, ethylbenzene will increase as it is recycled through the separation and isomerization steps. accumulate,
This leads to an undesirable situation in which the agricultural industry (in other words, agricultural production) increases.

Therefore, it is currently the case that modified oil-based xylene with a low concentration of ethylbenzene is preferably used as a fresh feedstock, or in any case, it is necessary to reduce the concentration of ethylbenzene. , several methods have been industrially implemented and several methods have been proposed. There are two main ways to do this: one is to separate ethylbenzene as it is, and the other is to separate ethylbenzene as it is.
The first method is to convert it into other useful compounds by reaction.

Distillation is a method for classifying ethylbenzene. In the case of this method, since the boiling point difference between xylenes and xylenes is small, it is necessary to use ultra-precision distillation, which requires a huge industrial investment in equipment and also has high operating costs, making it an economically disadvantageous method. .

Furthermore, recently, as shown in JP-A-52-10223, there have been proposals to decompose ethylbenzene by adsorption separation, but the separation performance thereof is not fully satisfactory.

There are several other methods for removing ethylbenzene and converting it to other useful components. The most typical method is 49-47
733.51-15044.51-36253, JP-A-5416390, etc., this is a method of converting ethylbenpine into xylene. However, this method requires that the catalyst contain platinum, which is an extremely expensive noble metal.

Furthermore, in order to convert ethylbenzene into xylene, the intervention of non-aromatic components such as pnotene and paraffin is necessary due to the reaction mechanism, and the concentration of these components in the product ranges from several % to 10-odd %. It covers a range of.

In general, the conversion rate of ethylbenzene is determined by thermodynamic equilibrium (Table 2
), so there are some drawbacks such as limitations.

Table 2 Equilibrium composition (%) of xylene nt: 1 body Recently, a method of converting ethylbenzene to xylene using a mechanism different from the method using platinum has been proposed.
It is disclosed in the specification of No. 11658. In this way [j
, 75M-5 type, 75M-12 type, and ZSM-21 type zeolites 1 to 1 are used, but this method has the drawback that xylene isomerization is slow. In particular, in order to isomerize a raffinate fluid in which xylenes with a low content of para-xylene, such as para-xylene, are adsorbed and separated, it is necessary to highly isomerize not only meta-xylene but also ortho-xylene to para-xylene.

This is a fatal flaw in isomerizing xylenes with such a low content of paraxylene.

In addition, methods for converting ethylbenzene into other components other than xylene have recently been developed in Japanese Patent Publication No. 53-41657 and Japanese Patent Publication No. 52-1999.
This is proposed in the specification of No. 148028 and the like. This method isomerizes xylene and simultaneously converts ethylbenzene into benzene and diethylbenzene through a disproportionation reaction.
The idea is to separate it by taking advantage of the large boiling point difference between it and xylene. Benzene obtained by this method is in great demand as a phase raw material for synthetic fiber nylon.
There is little demand for diethylbenzene, and it is economically disadvantageous because it needs to be converted into other useful compounds.

-O- <Problems to be Solved by the Invention> The purpose of the present invention is to deethylate ethylbenzene to benzene, simultaneously highly isomerize xylene, and improve the selectivity of the reaction, thereby converting aromatic The present invention provides a method for converting hydrocarbons.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a crystalline product obtained by reacting an aqueous reaction mixture consisting of a silica source, an alumina source, an alkali source, and an aliphatic carboxylic acid or a salt thereof. To aluminosilicate 1: and catalyst containing rhenium,
Contacting xylenes containing ethylbenzene in the presence of hydrogen
This is a way to tighten it.

The crystalline aluminosilicate used in the present invention can be synthesized as follows. Silica source, alumina source, alkali source and aliphatic carboxylic acid or its salt (Si
The aqueous reaction mixture consisting of O, Al2O3, OH- and A) expressed in molar ratio has the following composition range (more preferred range): SiO/Al2O35-500 5-2001-12
0/S i O2s~500 10~500H/Si
OO, 01~1.0 0.02~0.8A/Al203
20.1 to 200 and 0.5 to 100 and reacting until crystals are formed.

As the silica source, for example, silica sol, silica gel, silica eroglu, silica hydrogel, silicic acid, silicate ester, sodium silicate, etc. are used.

As the alumina source, sodium aluminate, aluminum sulfate, aluminum nitrate, alumina sol, alumina gel, activated alumina, comma-alumina, alpha alumina, etc. are used.

As the alkali source, caustic soda, caustic potash, etc. are used, and caustic soda is preferred. These alkali sources are added so that OH- is present in the system preferably in the above composition.

The aliphatic carboxylic acid or its salt has 1 to 1 carbon atoms.
12, preferably 3 to 6, specifically monobasic oxycarboxylic acids such as glycolic acid, lactic acid, hydroacrylic acid, oxyacetic acid or salts thereof, dibasic and polybasic oxycarboxylic acids. Tal 1 ~ Ronic acid, malic acid, tartaric acid, citric acid or their salts, -base carboxylic acids such as formic acid, acetic acid, propionic acid, l! !
acids, valeric acid, acrylic acid, chloric acid, methacrylic acid or their salts, dibasic and polybasic carboxylic acids,
For example, oxalic acid, malonic acid, uccinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid or salts thereof are used. As the salt, a water-soluble 1/1 salt is preferred. These aliphatic carboxylic acids or salts thereof may be used alone or in combination of two or more.

The aqueous reaction mixture thus prepared is made into a slurry as homogeneous as possible and crystallized in a closed container, such as an autoclave made of iron, stainless steel, or lined with Teflon. The reaction conditions for crystallization include a reaction temperature of 80-250'C, preferably 100-250'C.
On'C, and the reaction temperature is 5 hours to 30 days, preferably tJ, 10 hours to 10 days.

During crystallization, the reaction mixture is preferably kept in a homogeneous state by stirring continuously or periodically.

After cooling, the crystallized reaction product is taken out from the closed container, washed with water, passed through the mouth, and dried if necessary. A typical X-ray diffraction pattern of the crystalline aluminosilicate+ synthesized in this manner is shown in Table 3.

Measurement of the X-ray diffraction pattern was carried out according to a conventional method. That is, X-ray irradiation is performed using a Geiger counter spectrometer equipped with a recording device to obtain a diffraction pattern. From this diffraction pattern, the relative intensity is 100 I/I
Q (IQ i3i strongest line) and lattice spacing d
(unit angstrom △) is found.

Table 3 X-ray diffraction pattern 11.2 ±0.2 VSlo, 1 ±0
．． 2 3 9.8 ±0.2 M 6.37±0.1 W 6.00-1-0.1 W5.71±0
．． 1 W 5.58±0.1 W 4.37±0.08 W 4.27±0.08 W 3.86±0.08 VS 3.82±0.08 VS 3.75±0.08 8 3.72±0.08 3 3.66±0.05 M 3.00±0.05 M 2.00±0.05 W However, the relative strength (100I/To) is VS-Very strong, S -Strong, M-Intermediate strength, W-Weak.

The crystalline aluminosilicate 1 synthesized in this manner does not have solid acidity as it is. When used in the conversion reaction of aromatic hydrocarbons, it is necessary to apply a solid acid to crystalline ↑1 aluminosilicate (=I-'H to make it into acid form.Acid form of crystalline aluminosilicate is well-known. J: Sea urchin crystalline aluminosilicate has polyvalent cations of divalent or higher valence such as hydrogen ions, ammonium ions, or rare earth ions as cations, and these usually have crystalline aluminosilicate containing monovalent alkali metal ions such as sodium. It is obtained by ion-exchanging at least a portion of the alkali metal ions of the aluminosilicate with hydrogen ions, ammonium cations or polyvalent cations. Such ion-exchange treatment is often referred to as ion-exchange treatment.

In the present invention, ion exchange treatment is preferred in which hydrogen ions and/or hydrogen ion precursors are introduced into the crystalline aluminosilicate by treatment with a solution containing an acid and/or an ammonium salt compound.

Ion exchange treatment is generally performed in an aqueous solution.

The acids that can be used are inorganic acids or organic acids.
Inorganic acids are more common. Examples of the inorganic acid include hydrochloric acid, nitric acid, phosphoric acid, carbonic acid, etc., but of course other acids may be used as long as they contain hydrogen ions. When using an inorganic acid, it is not preferable to treat it with a solution of too high a concentration because the crystal structure will be destroyed. The concentration of the acid preferably used varies greatly depending on the type of acid, so it is difficult to define it unambiguously, and when using it, sufficient care must be taken to avoid destruction of the crystal structure.

As ammonium salt compounds, inorganic ammonium salts such as ammonium nitrate, ammonium chloride, ft1m ammonium, ammonium carbonate, aqueous ammonia, etc., or ammonium salts of organic acids such as ammonium formate, ammonium acetate, ammonium citrate, etc. can be used as well. More preferred are inorganic ammonium salts.

The concentration of ammonium salt used is preferably 0.0
A 5 to 4 normal solution is used, more preferably about 0.1 to 2 normal. As a method for ion exchange treatment of crystalline aluminosilicate with an acid and/or ammonium salt solution, either a hatch method or a flow method is preferably used.

When processing in batch mode, solid-liquidization is carried out at a rate of about 1ρ/Kg, where the crystalline aluminosilicate can sufficiently contact the liquid.
The above is preferable. A treatment time of about 0°1 to 72 hours is sufficient, preferably about 0°5 to 24 hours.

The treatment temperature may be below the boiling point, but it is preferable to heat it to promote the ion exchange rate. In the case of flow treatment, a fixed bed method, a fluidized bed method, etc. can be used, but it is necessary to take measures to prevent uneven flow of the fluid or non-uniform ion exchange treatment.

The ion exchange treated crystalline aluminosilicate is then washed with water. As the washing liquid, preferably distilled water is used, and the washing may be performed by either a patch type or a flow type.

In this way, hydrogen ions and/or ammonium ions, which are hydrogen ion precursors, are introduced into the crystalline aluminosilicate to impart solid acidity. Hydrogen ions and/or cations other than their precursors may be present in the crystalline aluminosilicate, and there are no particular limitations on the type and size thereof.

The apparatus that can be used for the reaction according to the present invention may be either a fixed bed or a fluidized bed, but the fixed bed type is preferably used because the apparatus is simpler and the operation is easier. In the case of a fixed bed system, the smaller the catalyst particle size is, the more preferable it is from the point of view of the catalyst effectiveness coefficient, but if the particle size becomes too small, pressure loss increases, which is not preferable. Therefore, there is a preferable range for the catalyst particle size. Preferably used particle size is 0.05-1
0M, more preferably 0.1 to 2#.

The synthesized crystalline aluminosilicate is usually in a powder state. Therefore, in order to obtain a catalyst having such a preferable range, it is necessary to mold the catalyst.

Examples of the molding method include compression molding, extrusion molding, and the like. Particularly in the case of extrusion molding, it is preferable to use a binder to improve moldability or to impart strength to the molded product.

Of course, it goes without saying that there is no need to use a binder if it can be sufficiently molded without a binder.

Examples of binders include kaolin, bentonite,
Examples include naturally occurring clays such as Montmorillonite 1~, and synthetic products such as silica gel, alumina sol, and alumina gel. The amount of binder added is 70% by weight or less,
Preferably it is 20% by weight or less. Such molding may be performed before ion exchange treatment of the crystalline aluminosilicate, or ion exchange may be performed after molding.

In order to further improve the selectivity of the reaction according to the present invention,
Add rhenium to the catalyst.

Examples of the method for adding rhenium include a kneading method, an impregnation method, and a method of physically mixing powders together, but the method is not necessarily limited to these methods. However, since the more uniformly these components are dispersed throughout the catalyst, the better the activity and selectivity, the kneading method or impregnation method, which provides good dispersibility, is preferred.

Examples of rhenium that can be used include rhenium oxide, perrhenic acid, ammonium perrhenate, and rhenium sulfide. The amount of rhenium that can be expected to be effective is 0.005% by weight or more in elemental form based on the weight of the entire catalyst. However, if the amount added is too large, side reactions such as hydrogenolysis reactions will occur, so it should be less than 3 weight, preferably 0.
．． It needs to be 5% by weight or less.

The catalyst prepared as described above is dried prior to use and subsequently calcined. Drying is carried out at 50 to 250'C for 0.1 hour or more, preferably 0.5 to 18 hours. Firing is 300-70
0.1 hour or more at 0'C, preferably 400-600
'C for 0.5 to 24 hours. By the way, ammonium ions introduced in the ion exchange process are converted into hydrogen ions through such calcination, and hydrogen ions are also converted into de-cadionized forms as the calcination temperature is increased. Catalysts in various forms can also be used satisfactorily.

The catalyst prepared as described above is used under the following reaction conditions: the reaction operating temperature is 300 to 600'C, preferably 350 to 550'C.
It is. Reaction operating pressure ranges from atmospheric pressure to 100Kg/cmG
, preferably 50'J/ciG from atmospheric pressure. Time factor W/F (
9-at, W/g-mol co-feed material) (W: catalyst weight, F: mole feed material per hour) is 0.1 to 200.
Preferably it is 1-100. Hydrogen in the reaction system is essential. If the hydrogen concentration is too low, the dealkylation reaction of ethylbenzene will not proceed sufficiently, and furthermore, the deposition of carbonaceous components on the catalyst will cause the activity to deteriorate over time. On the other hand, excessively high hydrogen concentration increases the hydrogenolysis reaction, which is not preferable. Therefore, there is a preferable range for hydrogen concentration. The hydrogen concentration is 1 to 50, preferably 3 to 30, expressed as the molar ratio (+-(2/F)) between hydrogen and feedstock in the reaction system.

A xylene mixture containing ethylbenzene is used as the feedstock, but there is no particular restriction on the concentration of ethylbenzene in the xylene mixture. The concentration of para-xylene added to the xylene mixture is below the thermodynamic equilibrium concentration, but even if it contains para-xylene at the thermodynamic equilibrium concentration, it is used as a feedstock for the purpose of reducing the ethylbenzene concentration. Of course, it is also possible to use it as one form of use of the present invention. Even if the feedstock contains other aromatic components such as benzene, toluene, trimethylbenzene, ethyltoluene, diethylbenzene, ethylxylene, etc., there is no problem as long as the concentration is within a low range. Hereinafter, the present invention will be explained with reference to examples.

Example> Synthesis example Solid caustic soda (Nail-197, 0% by weight, H2
O3,0% by weight)14. ．． 7 grams and 10.5 grams of tartaric acid were dissolved in 350.7 grams of water.

Add to this solution a sodium aluminate solution (AI20319.5).
Weight%, Na1l-126, 1% by weight, 1-12054
．． 4% by weight) 5.2/l gram to form a homogeneous solution. Silicic acid commercially available as white carbon (Si0290.9% by weight, H2O12
0.1 wt%) powder, 66 O grams, was gradually added with stirring to prepare a homogeneous slurry aqueous reaction mixture.

The composition ratio (molar ratio) of this reaction mixture was as follows.

5i02/Al2O3100 To1 0 /5i02
200H/S: 02 0.2'1 Δ /A12037 This mixture was placed in a 500 d capacity O-1 crepe and sealed. Thereafter, the mixture was heated to 160'C without stirring and crystallized for 72 hours. After the crystallization was completed, the product was cooled, and then taken out from the autoclave, washed with distilled water until the pH became almost neutral, filtered, and dried overnight at 110'C.

The resulting product was analyzed with a zeolite having the X-ray diffraction pattern shown in Table 3.

Comparative Example Zeolite 1 to powder synthesized in Synthesis Example was heated to 80 to 90'C with a 0.187N ammonium chloride aqueous solution at a solid-liquid ratio of 5 (Q/Kg>), and ionized in batch for 30 minutes. Replaced it.Afterwards, rinsed thoroughly with steam water and '110'
It was dried overnight at C. This dealkalized zeolite
- Powder is mixed with alumina sol as a binder.
A1203) was added in an amount of 15% by weight in terms of A1203) and thoroughly kneaded.

After kneading, it was formed into particles with a size of 10 to 24 meshes (JIS sieve), dried at 110'C overnight, and then heated to 500°C.
'C in the presence of air for 2 hours. This catalyst is 11
Abbreviated as AIT. Table 4 shows the results of evaluating the catalytic activity using a feedstock consisting of ethylbenzene and xylene.

A perrhenic acid aqueous solution was added to zeolite 1~powder which was dealkalized in the same manner as in Examples and Comparative Examples.
．． 1% by weight was added thereto, and 15% by weight of alumina sol (calculated as alumina (A1203)) was added thereto as a binder and thoroughly kneaded. After kneading, it was molded into particles with a size of 10 to 24 meshes, dried at 110°C overnight, and then heated in air for 50°C.
It was fired for 12 hours at 0'C. This catalyst is abbreviated as 118T1. Catalytic activity is shown in Table 4.

The following margin <Effects of the Invention> The present invention deethylates ethylbenzene to benzene by contacting xylenes containing ethylbenzene with a catalyst containing specific crystalline aluminosilicate and rhenium. can be isomerized to a high degree, and the selectivity of the reaction can be improved.

Patent application Daitoshi Co., Ltd. 26-1

Claims (1)

[Claims] The silica source, alumina source, alkali source, and aliphatic carboxylic acid or its derivative are expressed in molar ratios: SiO_2/Al_2O_35-500 H_2O/SiO_25-100 OH^-/SiO_20.01-1.0 Ethylbenzene was added to a catalyst containing crystalline aluminosilicate and rhenium obtained by reacting an aqueous reaction mixture having a composition ratio of A/Al_2O_30.1 to 200 (where A is an aliphatic carboxylic acid or its salt) in the presence of hydrogen. 1. A method for converting aromatic hydrocarbons, which comprises bringing xylenes containing xylenes into contact with each other.