JPS60255739A - Production of 1,2,4,5-tetramethylbenzene - Google Patents

Abstract

PURPOSE:To obtain the titled compound economically, by using fine particle of crystalline aluminosilicate having specific silica/alumina ratio as a catalyst in the vapor-phase methylation of xylene and/or 1,2,4-trimethylbenzene with methanol. CONSTITUTION:Xylene and/or 1,2,4-trimethylbenzene is methylated with methanol in vapor phase to obtain 1,2,4,5-tetramethylbenzene useful as an intermediate of pyromellitic acid (a raw material of polyimide resin). In the above process, crystalline alumino-silicate fine powder having a silica/alumina ratio of >=20, preferably >=30 and an average particle diameter of <=1mum, preferably <=0.5mum, e.g. ZSM-5, ZSM-11, ZSM-12, etc., especially ZSM-5, is used as the catalyst. The objective compound can be produced in high selectivity suppressing the deactivation of the catalyst.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to the use of 1,2,4,5, which is useful as an intermediate raw material for pyromellitic acid, which is a raw material for polyimide resin, which is a heat-resistant plastic and is a heat-resistant resin. -Regarding the production method of tetramethylbenzene, xylene and/or 1.2.4-
When trimethylbenzene is gas-phase methylated using methanol, a fine particulate crystalline aluminosilicate with a silica/alumina molar ratio of 20 or more is used as a catalyst. This is a book about manufacturing methods.

(Prior art) Currently, methods for producing 1,2,4,5-tetramethylbenzene include methods of direct concentration and crystallization separation from catalytic reformed oil, methods of disproportionation of trimethylbenzene, Alternatively, a method of total methylation of trimethylbenzene is known.

Direct concentration and crystallization separation from catalytic reformed oil requires a large amount of cost and is not economical because the concentration of 1,2,4.5-tetramethylbenzene contained in the reformed oil is low.

Regarding the method of disproportionation of trimethylbenzene, a method using silica alumina, mordenite, or faujasite zeolite as a catalyst has been reported (
Special Publication No. 50-15778).

However, this method has the disadvantage that the disproportionation activity is low and the activity of the catalyst is significantly reduced.

Regarding the method of methylating trimethylbenzene, a liquid phase method using a Lewis acid catalyst such as aluminum chloride is generally known, but this method has problems of low activity and corrosion rings in the equipment.

On the other hand, for the method of methylating 1,2.4-)limethylbenzene with methanol in the gas phase, ZSM-5 or ZSM-5 treated with silicon tetrachloride as a catalyst was used.
A method using
No. 6, Proceedings of the 49th Spring Annual Meeting of the Chemical Society of Japan 2Q10, 59
0 (1984)).

(Problems to be solved by the invention) 1.2.4-) The conventional method of methylating remethylbenzene with methanol in the gas phase has been greatly improved in terms of activity selectivity compared to other conventional methods. However, the catalytic activity deteriorated quickly over time and was not satisfactory as an industrial production method.

(Means for Solving the Problem) As a result of intensive studies to solve the problem of the above-mentioned activity reduction, the present inventors found that using a particulate crystalline aluminosilicate with a silica/alumina molar ratio of 20 or more as a catalyst. , the decrease in activity is extremely small, and the selectivity is high.
．． It was discovered that 2,4,5-tetramethylbenzene can be produced, and the present invention was completed.

That is, the present invention provides xylene and /l 7tFi1
．． 2.4-) Particulate crystalline alumina with a silica/alumina molar ratio of 20 or more as a catalyst when producing 1,2,4.5-tetramethylbenzene by gas-phase methylation of remethylbenzene using methanol. The present invention relates to a method for producing 1,2,4,5-tetramethylbenzene characterized by using a silicate.

The crystalline aluminosilicate used in the present invention is a high silica one with a silica/alumina molar ratio of 20 or more, preferably 30 or more. Examples of these crystalline aluminosilicates include those developed by Mopil Oil Co., Ltd.*z
SM-5 (%Gan Sho 57-228283)%ZSM-
11 (% Kaiyaku No. 54-52699), ZSM-12 (%
158118), and ZSM-5 is particularly preferred.

Furthermore, the crystalline aluminosilicate used in the present invention needs to be in the form of fine particles. The term "fine particles" as used herein refers to particles whose primary particles have an average particle diameter of 1 μm or less, preferably 0.5 μm or less, as observed by an electron microscope.

When the particle size is larger than 1 μm, the activity of the catalyst is greatly reduced. For example, when the reaction is carried out in a fixed bed, the activity is reduced to about half in a few hours. On the other hand, when fine particles with a particle size of 1 μm or less, especially 0.5 μm or less are used, the activity hardly decreases for several tens of hours. This fact is a surprising and hitherto unexpected finding.

Although the reason why fine particulate crystalline aluminosilicate exhibits less decrease in activity is unknown, it is thought to be as follows. The 1,2,4,5-tetramethylbenzene used in the present invention has a large molecular diameter and is easily generated at acid sites inside and outside the narrow pores of crystalline aluminosilicate. When the crystals become fine particles, the ratio of acid sites outside the pores to the total acid sites increases, which is thought to extend the catalyst life. For comparison, Table 1 shows the ratio of porous acid sites to the total acid sites of H-ZSM-5 with an average particle size of 1 μm or less and larger than that.

However, the measurement is pyridine (total acid points) 4 at 500CK.
-The amount of irreversible adsorption of methylquinoline (porous acid sites) was claimed.

Table 1 The particulate crystalline aluminosilicate according to the present invention is
Usually, the ratio of porous acid sites to total acid sites is 0.07 or more, preferably 0.1 or more.

As a method for producing such fine-particle crystalline aluminosilicate, for example, a method of crystallization at a relatively low temperature of 100 to 120 C and under high speed stirring is used.

In addition, the crystalline aluminosilicate used in the present invention is used as a catalyst after ion exchange with various cations, but preferred are protons, group (a) on the periodic table,
Metal ions of Group B, Group II, and rare earth metals are preferred, and protons are particularly preferred.

Xylene and/or 1,2,4-) in the present invention
! J-me? Rubenzene/methanol molar ratio a o, o 1
-100, preferably 0.1-10. In addition, even if these raw materials are introduced as is, nitrogen,
Although it may be introduced after being diluted with hydrogen, it is preferable to dilute with hydrogen.

The reaction temperature in this FIAK is 200 to 5 oaC.

Preferably, the temperature range is 250 to 400C.

The present invention is carried out under normal pressure or increased pressure, and the reaction method is preferably a flow reaction method using a fixed bed, a fluidized bed, or the like.

(Effect of the invention) As is clear from the examples and comparative examples described later, the present invention 8A
With K-twist, the decrease in catalyst activity is very small and 1,2,4,5-tetramethylbenzene can be produced with high selectivity.

(Example) Example 1 To Q brand silicate aqueous solution (EiiO,: 29.9% by weight) 150F was added 120F of a 10% by weight tetrabulbyl ammonium hydroxide aqueous solution, and further aluminum sulfate [M4(son)s] was added.・113H10) 4F and water 40
2 was added and stirred for 10 minutes. Thereafter, 20% by weight of sulfuric acid was added dropwise to the solution while stirring the solution to adjust the p) to 111 to obtain a homogeneous gel. This glue was placed in a 1 ton autoclave equipped with a stirrer and crystallized at 110C for 5 days with stirring at a rotational speed of 200 rpm.

The obtained product was filtered, washed, dried at 120C for 5 hours, and then calcined in air for 8 hours at 120C, and subjected to X-ray diffraction analysis. As a result, this product was identified as ZSM-5.

Furthermore, this crystal was added to 6D with 1N ammonium chloride aqueous solution.
C. After ion exchange for 24 hours, filter, wash, dry,
It was fired at 500C for 5 hours to form a proton type.

I request a fluorescent X-ray analysis of this crystal./Al4
The molar ratio Fi was 70. Further, the average particle diameter of the primary particles observed with a scanning electron microscope was 0.08 μm.

Using this particulate H-28M-5i catalyst, a gas phase methylation reaction from meta-xylene and methanol was carried out under the following reaction conditions.

Meta-xylene/methanol/at molar ratio = -1/1/
1,5WH8V (meta-xylene/methanol standard)
= 5,4hr-'Reaction temperature:! +00tl:'% Pressure 6 to 9/cI1 Results from 1 to 20 hours after the start of the reaction are shown in Table 2.

Table 2 X xylene conversion rate...00 from m-mexine
Conversion rate to isomerization to -2p- is not included.

Example 2 The same fine particle form as used in Example 1) [-Z 8 M-
A gas phase methylation reaction from 1,2,4-trimethylbenzene and methanol was carried out using No. 5 under the following conditions.

1.2.4-trimethylbenzene/methanol/If,
= 1/2/4WH8V (1,2,4-)limethylbenzene + methanol standard) = 35 hr-' Reaction temperature: zaoC, pressure 10 kg/al After the start of the reaction, the results from 1 to 20 hours are shown in Table 3. .

Table 5 Does not include the conversion rate to isomerization.

Example 5 10% by weight tetrapropylammonium hydroxide aqueous solution 1502 was added to 200y of Q ground silicate aqueous solution, and further aluminum sulfate CA4(SO2)s・18H,O
) 10 f and water 502 were added and stirred for 10 minutes. Furthermore, 20% by weight sulfuric acid was added dropwise to this solution, and I) H1
A homogeneous gel was obtained by adjusting 0.5Vc@. This gel was placed in a 1 ton autoclave equipped with a stirrer and heated at 120C for 7 days.
Crystallization was carried out while stirring at a rotational speed of 100 rpm.

The obtained product was filtered, washed, dried at 120 C for 6 hours, and then calcined in air at 5 oaC for 8 hours and subjected to X-ray diffraction analysis. As a result, this product was identified as ZSM-5.

Furthermore, 60
C. After ion exchange for 24 hours, filter, wash, dry,
It was fired at 500C for 5 hours to form a proton type.

Fluorescent X-ray analysis of this product requested SiO,/A14
0. The molar ratio was 65. Further, the average particle diameter of primary particles observed using a scanning electron microscope was 0.3 μm.

Using this particulate H-ZSM-5 as a catalyst, a gas phase methylation reaction from meta-xylene and methanol was carried out under the following reaction conditions.

Metaxylene // methanol / horse = 1 / 2 / 2
WH8V (metaxylene + methanol standard) -5hr
-'Reaction temperature: 330C5 pressure 4 kg/cd Table 4 shows the reaction temperature for 1 to 20 hours after the start of the reaction.

Table 4 Comparative Example The same gel as in Example 1 was placed in a 1 ton autoclave equipped with a stirrer and crystallized at 180 C for 30 hours with stirring at a rotation speed of 15 rpm.

The obtained product was filtered, washed, dried at 120C for 5 hours, then calcined in air at 500G for 8 hours, and subjected to X-ray diffraction analysis. As a result, this product was identified as ZSM-5.

Furthermore, this was subjected to ion exchange in the same manner as in Example 1 to obtain a proton type.

Fluorescent X-ray analysis of this product revealed that s r O,/A!
40. The molar ratio was 65. Further, the average particle diameter of the primary particles observed using a scanning electron microscope was 3 μm.

Using this H-ZSM-5 as a catalyst, a gas phase methylation reaction from meta-xylene and methanol was carried out under the same conditions as in Example 1.

Table 5 shows the results from 1 to 20 hours after the start of the reaction.

Table 5

Claims (2)

[Claims] (1) Xylene and 1,2,4-)limethylbenzene are methylated in the gas phase using methanol.
, 1 when producing 2,4.5-tetramethylbenzene.
1. A method for producing 1,2,4.5-tetramethylbenzene, characterized in that a particulate crystalline aluminosilicate having a silica/alumina molar ratio of 20 or more is used as a catalyst. (2) The method according to claim 1, wherein the crystalline aluminosilicate is ZSM-5.