JPS6019728A - Preparation of xylene - Google Patents

Abstract

PURPOSE:To improve conversion ratio of raw material, and to obtain xylene selectively, by using a crystalline borosilicate containing fluorine, methylating toluene or benzene. CONSTITUTION:An aqueous medium is added to a silica source, a boron source, and a crystallizing agent, which are subjected to hydrothermal reaction to give crystalline boro silicate, which is reacted with chlorine to give crystalline borosilicate containing fluorine. Toluene or benzene or a mixture of them is methylated with a methylating agent such as methanol, etc. by the use of the crystalline borosilicate containing fluorine as a catalyst, to give xylens. EFFECT:The catalyst has long catalytic life, and continuous operation can be carried out with keeping high catalytic activity for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing xylenes, and more specifically, to produce xylenes from toluene or benzene with high selectivity by using fluorine-containing crystalline borosilicate as a catalyst. Regarding the method.

A variety of methods have been known to produce industrially extremely useful intermediates by methylation of toluene or benzene. A method using crystalline borosilicate (Japanese Unexamined Patent Publication No. 55-55500) has been reported.

However, the method using crystalline aluminosilicate has the problem that the selectivity of xylene decreases because the disproportionation reaction occurs simultaneously with the methylation reaction, and the method using crystalline borosilicate has the problem that the methylation agent is not effectively used in the methylation reaction, and a large amount of byproducts are produced due to side reactions other than the methylation reaction.

Therefore, the present inventors have conducted extensive research in order to develop a method that can overcome the drawbacks of the above-mentioned conventional techniques and produce xylenes with high selectivity. As a result, the inventors discovered that by using crystalline borosilicate containing fluorine as a catalyst, the selectivity of xylenes and the conversion rate of raw materials toluene and benzene were improved, and the present invention was completed. . That is, the present invention provides a method for producing xylenes, which is characterized by using crystalline borosilicate containing potassium and fluorine as a catalyst, in which xylenes are produced by methylating toluene or benzene in the presence of a catalyst. It provides:

The catalyst used in the method of the present invention is, as mentioned above, a fluorine-containing crystalline borosilicate, which is generally obtained by subjecting crystalline borosilicate to a fluorination treatment. Here, various types of crystalline borosilicate can be used, for example, JP-A-53-55500, JP-A-55-7598, JP-A-56-84315, JP-A-57- 12
Examples include crystalline borosilicate described in JP-A-5817, JP-A-57-129820, and the like. There are various methods for preparing these crystalline borosilicic acids, but generally they can be prepared by adding various silica sources, boron sources, and crystallizing agents to an aqueous medium and subjecting them to a hydrothermal reaction. .

For example, ammonium type crystalline borosilicate is prepared as follows. That is, first, an aqueous solution (solution A) containing boric acid, concentrated sulfuric acid, and tetrapropylammonium bromidera,
An aqueous solution of water glass (solution B) and an aqueous sodium chloride solution (solution C) consisting of silicon oxide, sodium oxide, and water are respectively prepared, and solutions A and B are added dropwise to solution C, and the pH of the mixture is adjusted as necessary. Adjust [7. Heat this in an autoclave. Thereafter, crystalline borosilicate (IJum) is obtained through the processes of cooling, washing, drying and firing. Further, the obtained crystalline sodium borosilicate is treated with an aqueous ammonium nitrate solution to obtain ammonium type borosilicate. The borosilicate obtained by this process is a powder, but it can also be molded by adding a binder such as alumina sol to it.

If the crystalline borosilicate obtained by the above method is used as a catalyst as it is, the selectivity for xylenes will not be sufficient and high catalytic activity cannot be maintained for a long period of time during the reaction.

Therefore, in the method of the present invention, such a crystalline borosilicate is subjected to a fluorination treatment to obtain a fluorine-containing crystalline borosilicate as a catalyst. This fluorination treatment can be carried out by various methods, and in short, any treatment that introduces fluorine into the crystalline borosilicate to produce a fluorine-containing crystalline borosilicate is sufficient. Specifically, crystalline borosilicate is contacted with an organic fluorine compound such as fluorocarbon gas at 400 to 600°C, or treated with a liquid such as hydrofluoric acid, sodium fluoride, boron trifluoride, or monofluoroacetic acid. A possible method is to perform contact treatment with a phase. There are various types of chlorofluorocarbon gases, including fluorocarbon-11 (0704).

Freon-12 ('7zOt2), Freon-1! l (
OF, Ot).

Freon-21 (OHF (14), Freon-22 (OHI)
P20t).

Freon-25 (OF horse), Freon 115 (OHF2 (
tOIPO4).

Examples include Freon-114 (ay2otay, at). Alternatively, when preparing crystalline borosilicate, a fluorine source can be added together with a silica source, a boron source, etc. at the stage of the hydrothermal reaction, so that the crystalline borosilicate contains fluorine. In this case, the fluorine source is preferably a liquid one such as hydrofluoric acid or sodium fluoride.

The fluorine-containing crystalline borosilicate obtained by the above treatment is molded as it is or with the addition of a suitable binder such as alumina, and then calcined at 550 to 1000°C. Used as a catalyst in manufacturing reactions. The raw material compound used in this methylation reaction is toluene, benzene, or a mixture thereof, while the methylating agent is not particularly limited, but includes, for example, methanol, dimethyl ether, methyl chloride, methyl bromide, etc. In particular, methanol is preferred. The amount of the methylating agent to be used may be determined as appropriate depending on the type of raw material compound or reaction conditions, but usually the ratio of the raw material compounds, such as toluene or benzene, to the methylating agent is set to 1? ID~20:1 (molar ratio), preferably 1:2
~5:1 (molar ratio).

The method of the present invention may be carried out using toluene or benzene as a raw material, an appropriate methylating agent, and the above-mentioned catalyst, and other conditions are not particularly limited. General conditions are: reaction temperature 550-650°C;
Preferably 400 to 600°C, reaction pressure normal pressure to 10 kg
/aiG1 Weight space velocity (WH8T) 0.1~20
hr-', preferably 0.5 to 10 hr-'.

According to the method of the present invention as described above, there are fewer side reactions such as suppression of decomposition of the methylating agent, and as a result, the conversion rate of toluene and the selectivity of xylene are improved. At the same time, since the catalyst has a very long life, continuous operation can be performed while maintaining high catalyst activity for a long period of time.

Therefore, the method of the present invention is extremely advantageous as an industrial method for producing xylene and has high utility value.

Next, the present invention will be explained more clearly with reference to Examples and Comparative Examples.

Example 1 (1) Preparation of catalyst Boric acid o, 2qf, m sulfuric acid 3.9t and tetra-n-propylammonium (promylammonium)'5.81c water 55m/
Solution A1 was prepared by adding 46.9 f of water glass (J Sodium Silicate No. 3, Nippon Kagaku Kogyo ■) to 55 ml of water, and Solution C by dissolving 17.47 ml of sodium chloride in 27 ml of water. . Solutions A and B were then added dropwise to solution C simultaneously. The obtained solution was placed in an autoclave and heated at a reaction temperature of 170°C for 20 hours.

After cooling, the contents were filtered, washed with water, dried at 120° C. for 12 hours, and then calcined at 550° C. for 6 hours to obtain 1 μm of sodium-type crystalline 1111 silicic acid 1147. This one is also X! [i1 diffraction revealed that it had a ZSM-5 type structure.

Next, the obtained borosilicate was added to a 1N aqueous ammonium nitrate solution in a 5-fold heavy lid, and the mixture was heated under reflux for 8 hours and the solid matter was sieved. Further reflux the solid.

After repeating the filtration operation three times, it was washed with water and heated at 120℃ for 12 hours.
Ammonium-type crystalline borosilicate was obtained by drying for 1 hour. Next, alumina sol was added to this borosilicate so that the alumina content after firing was 201, and the molding L7. A molded product of silicic acid was obtained.

Next, the obtained molded product 21 was filled into a reaction tube and heated to 500
Hold at ℃ [7, 1.1.2.2-tetrafluoro-1
, 2-dichloroethane (Freon-114) was supplied at a rate of 70 d/min for 5 hours to carry out a fluorination treatment to obtain crystalline borosilicate containing fluorine.

(2) Methylation reaction of toluene A normal-pressure fixed-bed flow reaction tube was filled with the fluorine-containing crystalline borosilicate 21 obtained in (1) above as a catalyst, and the reaction temperature was 600°C and WH8'V9. .2 hr-”.

Feed ratio of toluene and methanol to 4:1 (%le ratio)
The reaction was carried out as follows. The reaction results are shown in Table 1.

Comparative Example 1 Tl) Preparation of Catalyst A molded product of proton-type crystalline borosilicate was obtained in the same manner as in Example 1 (1) except that the fluorination treatment was not performed in Example 1 (1).

(2) Toluene methylation reaction “Toluene methylation reaction was carried out in the same manner as in Example 1 (2) except that the molded product obtained in (1) above was used as a catalyst in Example 1 (2). A chemical reaction was carried out.

The reaction results are shown in Table 1.

Table 1 Carbon monoxide, hydrogen, and methane are the main components resulting from the decomposition of methanol Example 2 (11 Catalyst 1iJ41 boric acid 0.299.fi Sulfuric acid 5.99- was added to water 25111 Solution A and water glass ( Solution B was prepared by adding J Sodium Silicate No. 3 (manufactured by Nippon Kagaku Kogyo ■) 16.9i to 21 - of water.Next, solutions A and B were simultaneously mixed with 11 of water.
11, and further added 85 ml of methanol.

The resulting mixture was placed in an autoclave at a temperature of 170°C.
A heat treatment was performed for 20 hours. After cooling, the contents were filtered, washed with water, dried at 120"C for 12 hours, and further heated for 5
After firing at 50°C for 6 hours, the sodium type crystals were obtained as 4.1η of Sney type 1 (Japanese Patent Application No. 16395/1982).
It was found that it has a structure.

Next, the obtained borosilicate was added to a 5 times heavier 1N aqueous hydrochloric acid solution, heated at 70°C for 8 hours, cooled and filtered. The obtained solid substance was further heated and filtered five times under the same conditions, washed with water, and incubated at 120°C for 1 hour.
After drying for 2 hours, proton type crystalline borosilicate was obtained. Next, alumina sol was added to this borosilicate so that the alumina base after firing was 20% by weight, and the mixture was molded, dried for 12 hours, and further fired at 550°C for 6 hours to obtain a molded product of proton-type crystalline borosilicate. I got it. Next, this molded product 21 was filled into a reaction tube, kept at 500°C, and 1.1.2.2-tetrafluoro-1,2-dichloroethane (Freon-114
) is supplied at 70 d/min for 3 hours for fluorination treatment to produce crystalline borosilicate containing fluorine? %Ta.

(2) Methylation reaction of toluene A normal-pressure fixed-bed flow reaction tube was filled with the fluorine-containing crystalline borosilicate 21 obtained in (1) above as a catalyst, and the reaction temperature was 600 "C% wasv2 hr-' The reaction was carried out at a feed ratio of 4:1 (mole ratio) of toluene and methanol.The reaction results are shown in Table 2.

Comparison row 2 (1) Made of catalyst il, i A molded product of proton-type crystalline borosilicate was obtained in the same manner as in Example 20) except that the fluorination treatment was not performed in Example 2 (1). .

(2) Toluene methylation reaction Example 2 (2) Smell -Execution p142 (21
The methylation reaction of toluene was carried out in the same manner.

The reaction results are shown in Table 2.

Table 2

Claims (1)

[Claims] (11) A method for producing xylenes, which is characterized by using fluorine-containing crystalline borosilicate as a catalyst in producing xylenes by methylating toluene or benzene in the presence of a catalyst.