JPH0375536B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing xylene, and more particularly to a method for producing xylene from toluene or benzene with high selectivity by using a specific fluorinated aluminosilicate as a catalyst. Conventionally, xylene has been produced by methylating toluene or benzene, and crystalline aluminosilicates such as ZSM-5 and ZSM-11 are known as catalysts used in this process (Japanese Patent Application Laid-Open No. 1979-1999). Publication No. 57688 and Publication No. 52-120292, etc.). However, when crystalline aluminosilicate such as ZSM-5 is used directly as a catalyst to carry out the methylation reaction of toluene, disproportionation reactions are likely to occur, resulting in a decrease in xylene selectivity. Ta. In addition, the catalyst life could not be said to be sufficient as a practical catalyst. Therefore, the present inventors have conducted extensive research in order to overcome the drawbacks of the above-mentioned conventional techniques and to develop a method that can produce xylene with high selectivity and maintain high catalytic activity for a long time. . As a result, it was discovered that xylene can be efficiently produced from toluene and benzene by using fluorine-treated specific crystalline aluminosilicate such as ZSM-5 and ZSM-11 as a catalyst.This led to the completion of the present invention. I've reached it. That is, in the present invention, when producing xylene by methylating toluene or benzene with a methylating agent in the presence of a catalyst, an aluminosilicate having a silica/alumina molar ratio of 12 or more and a control index of 1 to 12 is treated with fluorine. The present invention provides a method for producing xylene, characterized in that a fluorinated aluminosilicate obtained by the above method is used as a catalyst. The aluminosilicate used in the present invention has a silica/alumina molar ratio of 12 or more, preferably 20 to
400 and a control index of 1 to 12, preferably 5 to 10. Here, the silica/alumina molar ratio is measured by conventional analytical methods, but the control index is determined by J.CATAL. 67 ,
218 (1981). This control index serves as a standard for determining whether the target aluminosilicate has the necessary characteristics to control the entry of molecules with a cross section larger than that of n-paraffin. n- on the aluminosilicate sample under atmospheric pressure.
It is simply determined by successively passing an equal weight mixture of hexane and 3-methylpentane.
This procedure is as described in J.CATAL. 67 , 218 (1981). According to the procedure described herein, the control index is defined as follows. Control index = log ₁₀ (proportion of residual n-hexane)/l
og ₁₀ (proportion of remaining 3-methylpentane) The aluminosilicate used in the present invention must have a control index in the range of 1 to 12, as described above. If the control index is less than 1, the pore diameter becomes too large and trimethylbenzene is produced, resulting in a decrease in xylene selectivity. On the other hand, if it exceeds 12, the pore diameter becomes too small and the methylation reaction of toluene and benzene will not proceed. The aluminosilicate used in the present invention is not particularly limited and may include various aluminosilicates as long as they have the silica/alumina molar ratio and control index within the ranges described above, but specifically ZSM -5,
ZSM-11, ZSM-12, ZSM-23, ZSM-35,
Representative examples include ZSM-38 and ZSM-48. In the present invention, a fluorinated aluminosilicate obtained by subjecting such aluminosilicate to fluorine treatment is used as a catalyst. This fluorine treatment is
This can be carried out by various methods, and in short, any treatment may be used as long as fluorine is introduced into the aluminosilicate to form a fluorinated aluminosilicate. Specifically, aluminosilicate is contacted with an organic fluorine compound such as chlorofluorocarbon gas at 400 to 600°C, or contacted with hydrofluoric acid, sodium fluoride, boron trifluoride, monofluoroacetic acid, etc. in the liquid phase. There are ways to do this. There are various kinds of fluorocarbon gases, including fluorocarbon-11 (CFCl ₃ ), fluorocarbon-12 (CF ₂ Cl ₂ ), fluorocarbon-13 (CF ₃ Cl), fluorocarbon-21 (CHFCl ₂ ), and fluorocarbon-22 (fluorocarbon-22). CHF ₂ Cl), Freon-23 (CHF ₃ ), Freon-113 (CF ₂ ClCFCl ₂ ), Freon-114 (CF ₂ ClCF ₂ Cl), and the like. In the present invention, the fluorinated aluminosilicate thus obtained is used as a catalyst, but if the aluminosilicate is used as a catalyst as it is without fluorine treatment, the methylation reaction of toluene or benzene will be carried out. The selectivity of xylene is not sufficiently high, and the catalyst life is also short, making it impractical. The above-mentioned fluorinated aluminosilicate is used as a catalyst for the methylation reaction, either as it is or after being molded with a suitable binder such as alumina and then calcined at 550 to 1000°C. 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 for example, methanol,
Examples include dimethyl ether, methyl chloride, methyl bromide, and methanol is particularly 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 1:10 to 1:1. The molar ratio is 20:1, preferably 1:2 to 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. If we show the general conditions,
Reaction temperature: 200 to 650°C, preferably 400 to 600°C, reaction pressure: normal pressure to 10 Kg/cm ² G, weight hourly space velocity (WHSV): 0.1 to 20 hr ^-1 , preferably 0.5 to 10 hr ^-1
It is. According to the method of the present invention as described above, xylene can be obtained with high selectivity and yield, and at the same time, the catalyst life is extremely long, so that xylene can be obtained while maintaining high catalytic activity for a long period of time. Continuous operation is possible. Therefore, the method of the present invention is extremely advantageous and has high utility value as an industrial method for producing xylene. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 (1) Preparation of catalyst Dissolve 7.5 g of aluminum sulfate in 250 ml of water,
Furthermore, 17.6 g of concentrated sulfuric acid and 26.3 g of Tetra n-propylammonium bromide were dissolved in this to make liquid A, and water glass (J sodium silicate 3
211.0 g of Nippon Kagaku Kogyo Co., Ltd.) was dissolved in 250 ml of water to obtain Solution B, and 79.0 g of sodium chloride was further dissolved in 122 ml of water to obtain Solution C. Next, the above solutions A and B were simultaneously added dropwise to solution C over 10 minutes at room temperature. The resulting mixture was placed in an autoclave and heat-treated at 170°C for 20 hours. After cooling, the contents were filtered, washed with water, and heated to 120°C.
Let dry for 12 hours. X-ray diffraction analysis of the product confirmed that it was ZSM-5. The obtained ZSM-5 was calcined at 550°C for 6 hours to obtain 56.5 g of sodium type ZSM-5. This sodium form ZSM-5 was added to a 1N ammonium nitrate aqueous solution weighing 5 times its weight, and the mixture was refluxed for 8 hours. Thereafter, the mixture was cooled and allowed to stand, and the supernatant was removed by decantation. Furthermore, after repeating the reflux and decantation operations three times, the contents were filtered and washed with water, dried at 120℃ for 12 hours, and ammonium-type ZSM
-5 was obtained. This ammonium type ZSM-5 is 600
The composition of the product fired at °C is Si/Al = 90 (molar ratio),
The control index (CI value) was 8. Next, the alumina content of this ammonium type ZSM-5 after firing was
Alumina sol was added as a binder to give a concentration of 20% by weight, and the pellets were formed into pellets, dried at 120°C for 16 hours, and then fired at 550°C for 6 hours. 6.5 g of the obtained pellets were filled into a reaction tube, and fluorine treatment was carried out by supplying fluorine-114 (1,1,2,2-tetrafluoro-1,2-dichloroethane) at 70 ml/min for 1 hour at 550°C. A catalyst was obtained. (2) Methylation of toluene 2 g of the catalyst obtained in (1) above was packed into an atmospheric fixed bed flow reaction tube, and the raw material charging ratio (molar ratio) was set toluene:methanol = 4:1 at 600°C. The reaction was carried out with the WHSV of the raw material = 9 hr ^-1 . The reaction results are shown in Table 1. Example 2 (1) Preparation of catalyst Dissolve 7.5 g of aluminum sulfate in 250 ml of water,
Further, 17.6 g of concentrated sulfuric acid and 31.3 g of tetra-n-butylammonium bromide were dissolved to prepare a solution A, and 211.0 g of water glass (same as in Example 1) was dissolved in 250 ml of water to obtain a solution B. Then,
Solutions A and B were simultaneously dropped into 122 ml of water at room temperature for 10 minutes. Put the resulting mixture into an autoclave,
Heat treatment was performed at 170°C for 20 hours. After cooling, the contents were filtered, washed with water, and dried at 120°C for 12 hours.
As a result of X-ray diffraction analysis of the product, it was confirmed that it was ZSM-11. This ZSM-11 was baked at 550℃ for 6 hours, and 57.7g of sodium type ZSM-11 was obtained.
Obtained. Furthermore, sodium form ZSM-11 was added to a 1N aqueous ammonium nitrate solution of 5 times its weight and refluxed for 8 hours. Thereafter, the mixture was cooled and allowed to stand, and the supernatant was removed by decantation. After repeating the reflux/decantation operation three times, the contents were filtered, washed with water, and dried at 120°C for 12 hours to obtain ammonium type ZSM-11. This ammonium type
The composition of ZSM-11 fired at 600℃ is Si/Al.
=90 (molar ratio), control index (CI value) =8.
Next, alumina sol was added as a binder to the obtained ammonium type ZSM-11 so that the alumina content after firing was 20% by weight, and the mixture was molded at 120°C.
After drying for 16 hours, it was fired at 550°C for 6 hours. Fill a reaction tube with 6.5 g of the obtained calcined pellets and heat at 500°C.
In this step, fluorine treatment was carried out by supplying Freon-13 (trifluorochloromethane) at a rate of 70 ml/min for 1 hour to obtain a catalyst. (2) Methylation of toluene In Example 1 (2), the reaction was carried out in the same manner as in Example 1 (2) except that the catalyst obtained in (1) above was used. The reaction results are shown in Table 1. Comparative Example (1) Preparation of Catalyst A catalyst was prepared in the same manner as in Example 1(1) except that the fluorine treatment with Freon-114 was not performed in Example 1(1). (2) Methylation of toluene In Example 1 (2), the reaction was carried out in the same manner as in Example 1 (2) except that the catalyst obtained in (1) above was used. The reaction results are shown in Table 1.

[Table] Example 3 (1) Preparation of catalyst Ammonium type ZSM- obtained in Example 1 (1)
5 10g of powder in 100c.c. of water with 0.5g of hydrofluoric acid (46%)
was added to the solution in which the mixture was dissolved, and heated and stirred at 80°C for 6 hours. After cooling, filtration, and repeated washing with water,
It was dried at 120°C overnight and then fired at 550°C for 6 hours. Next, alumina sol was added as a binder and molded so that the alumina content after firing was 20% by weight, and after drying at 120°C overnight, it was fired at 550°C for 6 hours. (2) Methylation of toluene In Example 1 (2), the reaction was carried out in the same manner as in Example 1 (2) except that the catalyst obtained in (1) above was used. The reaction results are shown in Table 2.

[Table] Reference example 6g of ZSM-5 (H type) zeolite was brought into contact with aluminum chloride vapor at 250℃ for 2 hours, then heat treated at 600℃ for 1.5 hours in a nitrogen atmosphere, and then calcined in air at 600℃ for 1 hour. Post-molded. Using this catalyst [A] and the catalyst of Example 1, a toluene methylation reaction was carried out under the same conditions as in Example 1, and the effects were compared. The results are shown in Table 3.

【table】

[Table] As is clear from the table, when catalyst [A] was used, the toluene conversion rate decreased significantly as the reaction time progressed, whereas when the catalyst of Example 1 was used, this phenomenon did not occur. It is possible to efficiently produce the desired xylene without causing any

Claims (1)

[Claims] 1. In producing xylene by methylating toluene or benzene with a methylating agent in the presence of a catalyst, an aluminosilicate having a silica/alumina molar ratio of 12 or more and a control index of 1 to 12 is mixed with fluorine. A method for producing xylene, characterized in that a fluorinated aluminosilicate obtained by the treatment is used as a catalyst. 2. The method according to claim 1, wherein the fluorine treatment is performed using chlorofluorocarbon gas, hydrofluoric acid, sodium fluoride, boron trifluoride, or monofluoroacetic acid.