JPH09208502A - Selective production of p-xylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain p-xylene which is useful as a raw material for polyester selectively in a higher concentration than that at the thermodynamic equilibrium with side reactions reduced. SOLUTION: PARA-xylene is amylbenzenelene is produced by alkylation of benzene or toluene obtained as by-products in reformation, thermal cracking and hydrocracking of petroleum with ethylene or methanol in the presence of a catalyst. As a catalyst to be used in this alkylation, a crystalline silicate having the following chemical composition is preferably cited: aR2 ObmoAl2 o3 ySiO2 (R is an alkali metal ion, H; M is one or more kinds of alkaline earth metal ions; 0.7<a<1.2; b>0; y>30) and the lattice spacing shown in the figure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester of benzene or toluene obtained as a by-product of petroleum reforming, thermal decomposition, hydrocracking and the like, which is alkylated with ethylene or methanol using a crystalline silicate as a catalyst. The present invention relates to a method for selectively producing p-xylene, which is important as a starting material, at a high concentration above thermodynamic equilibrium.

[0002]

2. Description of the Related Art Conventionally, in the case of a reaction for synthesizing xylene from toluene and methanol by alkylation, Friedel.
Crafts catalysts are used. However, since the reaction takes place on the catalyst surface, in addition to xylene, aromatic hydrocarbons of about C _{6 to} C ₁₀ and alkanes and alkenes are produced as side reactions, and also in C ₈ aromatics, P-xylene and o-xylene. , M-xylene three isomers and ethylbenzene are formed, which form thermodynamic equilibrium,
It is known to have a fixed composition. For example, 327
The composition of three isomers of xylene at ° C is p-xylene: 23.8%, m-xylene: 53.2%, o-xylene: 23.0%.

Currently, p-xylene is separated by distilling or deep-separating these side reaction products, but the separation device is complicated and expensive. Especially in the case of distillation,
Since the boiling points of the C ₈ aromatic isomers are close to each other, it is difficult to control the conditions, and the costs associated with the equipment and the operation are large.
Further, the demand for p-xylene is expanding, and since it will greatly affect the industrial value in the future, it is desired to reduce the cost of p-xylene.

[0004]

In view of the above-mentioned state of the art, the present invention provides a method for selectively obtaining p-xylene having a thermodynamic equilibrium composition or more.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems of the prior art, and is a catalyst containing an alkaline earth metal in a crystalline silicate having a specific composition and crystal structure. However, the present inventors have completed the present invention by finding that there are few side reactions in the alkylation reaction of benzene or toluene, and in particular that p-xylene is selectively produced at a ratio higher than the thermodynamic equilibrium composition.

That is, according to the present invention, in a method for producing p-xylene by alkylating benzene or toluene with ethylene or methanol, the molar ratio of oxides is aR ₂ O.bMO.Al ₂ O ₃
· YSiO ₂ (wherein, R: alkali metal ion, hydrogen ion, M: one or more alkaline earth metal ions, 0.7
<A <1.2, b> 0, y> 30),
In addition, a crystalline silicate having a lattice spacing shown in Table 1 below is used as a catalyst, which is a method for selectively producing p-xylene. When carrying out the present invention, the above-mentioned catalyst may be used in the form of granules or pellets, or may be used in the form of a monolith.

[0007]

[Table 1] VS: Very strong M: Intermediate S: Strong W: Weak

(Action) Regarding the action of the catalyst used in the present invention, the benzene ring (molecular diameter: about 0.55 nm) enters the pores of the crystalline silicate having a diameter of about 0.6 nm,
Alkylation occurs at the acid sites in the pores, but p is because the benzene ring is sterically constrained in the pores of the crystalline silicate.
-It is considered that xylene is selectively produced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the catalyst used in the present invention will be described in detail. The crystalline silicate used in the present invention forms a reaction mixture containing a source of silica, a source of alkaline earth metal, a source of alumina, a source of alkali, water and an organic nitrogen compound, which is used to form a crystalline silicate. It is synthesized by heating for the time and temperature.

The silica source can be any silica source commonly used in the synthesis of zeolites, such as solid silica powder, colloidal silica, or silicates such as water glass. Is used. As the alkaline earth element, sulfates or nitrates of magnesium, calcium and barium are used.
The most suitable source of alumina is sodium aluminate, but compounds such as chlorides, nitrates, sulfates, oxides or hydroxides are used. The source of alkali is hydroxide of alkali metal such as sodium or aluminate,
A compound with silicic acid is used. Examples of the organic nitrogen-containing compound, which is one of the raw materials for hydrothermal synthesis of crystalline silicate, include primary amines such as n-propramine, secondary amines such as dipropylamine, and tertiary amines such as tripropylamine. A quaternary ammonium salt such as tetrapropylammonium salt is used.

The crystalline silicate used in the present invention is synthesized by heating the above raw material mixture at a temperature and for a time sufficient for producing the crystalline silicate, and the hydrothermal synthesis temperature is 80 to 300 ° C., preferably 130. To 200 ° C., and the hydrothermal synthesis time is 0.5 to 14 days, preferably 1 to 10 days. The pressure is not particularly limited, but it is preferable to carry out the operation under its own pressure. The crystalline silicate used in the present invention is a regular porous crystalline substance having a certain crystal structure, and generally exhibits the X-ray diffraction pattern shown in Table 1 above.

The crystalline silicate obtained by the above hydrothermal synthesis is an alkali metal ion such as Na ⁺ , (C ₃ H ₇ )
_It contains organic nitrogen-containing compound ions such as ₄ N ⁺ . In order to replace a part or all of these ions with hydrogen ions, 2 in the range of 400 to 700 ° C. in air.
After removing the organic compound by baking for 48 hours, it may be directly immersed in a strong acid such as hydrochloric acid to form the H type. The catalyst used in the present invention can be obtained by the above method.

[0013]

EXAMPLES Hereinafter, the effects of the present invention will be clarified by giving examples and comparative examples of the present invention.

Example 1 The crystalline silicate used in the present invention was synthesized as an example by the following method. 198
140g of water glass (Na ₂ O ・ 3.4SiO)
₂ · 24H ₂ O) was dissolved to form solution A. Then 3
10.8 g in a mixture of 16 g water and 11.8 g sulfuric acid
Aluminum sulphate of {Al ₂ (SO ₄ ) ₃・ 16H
₂ O} and 0.43 g of calcium sulfate (CaSO _4.
2H ₂ O) was dissolved to form solution B. The acid is to neutralize excess alkali present to bring the reaction mixture composition to the required Na ₂ O / SiO ₂ range.

Solution B was mixed with solution A by stirring (30 minutes).
Between) and 12.7 g of tetrapropylammonium broth
After adding romide, 1 liter Teflon lined
In a stainless steel autoclave at 180 ° C for 2 days
Reacted while stirring. Filter the cooled solids and wash thoroughly
After cleaning, dried at 120 ° C for 12 hours to contain calcium
A crystalline silicate was obtained. The crystal grain size of this product is 5μ
m and the composition excluding organic compounds is 0.8 Na
_TwoO ・ 0.67CaO ・ Al_TwoO_Three・ 40 SiO _TwoIn
Si / Al ratio: 80, Si / Ca ratio: about 60
Was.

The crystalline silicate synthesized as described above was immersed in 1N hydrochloric acid, treated at 80 ° C. for 3 days, and sodium ions were replaced by hydrogen ions by the above-mentioned conventional method (hydrogen ion substitution amount: about 70). %). This was washed and filtered, dried at 120 ° C. for 12 hours, further baked at 550 ° C. for 5 hours, and compression-molded and brought into contact with a mixed solution of methanol and toluene under the reaction conditions shown below, and the results shown in Table 2 were obtained. Obtained.

[0017]

[Table 2] * P-xylene selectivity (%) = p-xylene fraction produced / total xylene fraction produced x 100

When a crystalline silicate containing calcium as shown in Table 2 is used as a catalyst, the temperature is 300 to 600 ° C.
Within the range, the selectivity of p-xylene was 40% or more, which was higher than the thermodynamic equilibrium composition.

[0019] Make a solution C (Example 2) was dissolved water 81g of water glass of _{120g (Na 2 O · 3.4SiO 2} · 24H 2 O). Next, 0.78 g of aluminum sulfate {Al was added to a mixture of 142 g of water and 6.4 g of sulfuric acid.
₂ (SO ₄ ) ₃ · 16H ₂ O} and 3.06 g of barium sulfate (BaSO ₄ ) were dissolved to form a solution D. Then, the solution D was mixed with the solution C by stirring (20 minutes), and 7.
After adding 0 g of n-propylamine, 200 in a 1 liter Teflon lined stainless steel autoclave.
The reaction was carried out at ℃ for 2 days with vigorous stirring. The cooled solid content was filtered, thoroughly washed, and then dried at 110 ° C. for 12 hours to obtain a barium-containing crystalline silicate. The composition of this crystalline silicate is 1.2Na ₂ O.5.3BaO.
Al ₂ O ₃ · 160SiO ₂ , Si / Al ratio: 3
20, Si / Ba ratio: about 30, and the crystal grain size was 5 μm.

The crystalline silicate synthesized as described above was immersed in 1N hydrochloric acid and treated at 80 ° C. for 3 days to replace sodium ion with hydrogen ion (hydrogen ion substitution amount:
About 80%). This is washed and filtered, dried, and further 550
Calcination at 5 ° C. for 5 hours and compression molding were carried out by bringing benzene into contact with a fixed proportion of ethylene under the reaction conditions shown below to obtain the results shown in Table 3 below.

[0021]

[Table 3] * P-xylene selectivity (%) = p-xylene fraction produced / total xylene fraction produced x 100

Comparative Example 81 g of water glass (Na ₂ O.3.4SiO ₂ .24H ₂ O) was dissolved in 120 g of water to prepare a solution C. Next, 3.1 g of aluminum sulfate {Al was added to a mixture of 150 g of water and 5.2 g of sulfuric acid.
₂ (SO ₄ ) ₃ · 16H ₂ O} was dissolved to prepare a solution D. Solution D is then stirred into solution C (20 minutes),
After adding an additional 7.8 g of n-propylamine, 200 in an 11 Teflon lined stainless steel autoclave.
The reaction was carried out at ℃ for 2 days with vigorous stirring. The cooled solid content was filtered, thoroughly washed, and then dried at 110 ° C. for 12 hours to obtain a barium-containing crystalline silicate. The composition of this crystalline silicate is 1.2 Na ₂ O · Al ₂ O ₃ · 4.
The SiO ₂ content was 0 SiO ₂ , the Si / Al ratio was 80, and the crystal grain size was 0.7 μm.

The crystalline silicate synthesized as described above was immersed in 1N hydrochloric acid and treated at 80 ° C. for 3 days to replace sodium ion with hydrogen ion (hydrogen ion substitution amount:
About 70%). This is washed and filtered, dried, and further 550
The mixture was calcined at 5 ° C. for 5 hours and compression molded to synthesize a crystalline silicate catalyst containing no alkaline earth metal. The catalyst was tested for the reaction between benzene and ethylene and the reaction between toluene and methanol under the reaction conditions shown below, and the results shown in Tables 4 and 5 below were obtained.

[0024]

[Table 4]

[0025]

[Table 5]

From the above results, when the crystalline silicate catalyst containing no alkaline earth metal is used, the p-xylene selectivity is near the thermodynamic equilibrium composition.

[0027]

As described above, in the reaction of benzene and ethylene or toluene and methanol, the conventional thermodynamic equilibrium composition was added to the crystalline silicate of the present invention with an alkaline earth metal, as shown in the examples. By using the contained catalyst, it became possible to obtain p-xylene having a thermodynamic equilibrium composition or more.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yukio Tanaka 4-6-22 Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Inside Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory

Claims (1)

[Claims] 1. A method for producing p-xylene by alkylating benzene or toluene with ethylene or methanol, wherein the molar ratio of oxides is aR ₂ O.bMO.Al ₂ O ₃ .ySiO ₂ ( In the formula, R: alkali metal ion, hydrogen ion, M: one or more alkaline earth metal ions, 0.7 <a <1.2, b
> 0, y> 30) and a crystalline silicate having a lattice spacing shown in Table 1 described in detail herein is used as a catalyst for the selective production of p-xylene.