JPH10298117A - Selective alkylation of aromatic hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a selective alkylation method of an aromatic hydrocarbon capable of selectively producing p-xylene by suppressing generation of compounds other than p-xylene in alkylating benzene or toluene. SOLUTION: This alkylation reaction of an aromatic hydrocarbon is performed by supplying an alkylation agent at a plural number of sites along a transferring direction of an aromatic hydrocarbon 1 in a catalyst layer 2 to the aromatic hydrocarbon 1 passing through the catalyst layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a target compound such as p-xylene by reacting an inexpensive aromatic hydrocarbon such as benzene or toluene with an alkylating agent.

[0002]

2. Description of the Related Art Conventionally, when p-xylene is synthesized by reacting toluene with methanol as an alkylating agent, a Friedel-Crafts catalyst such as aluminum chloride has been used as a catalyst. However, since the activity of methanol is very high, the decomposition of methanol and the conversion reaction to hydrocarbon are likely to occur, and a large amount of by-products are generated. That is, as aromatic hydrocarbons having 8 carbon atoms, p-xylene, m-xylene, o-xylene and ethylbenzene 4
Species isomers are generated, and aromatic hydrocarbons having 6 to 10 carbon atoms, alkanes, alkenes, and carbon monoxide are generated. It is known that reaction products form a thermodynamic equilibrium and have a specific composition. For example, the proportion of p-xylene in the xylene formed is about 25 mol%.

[0003] On the other hand, even when p-xylene is synthesized by reacting benzene with ethylene as an alkylating agent, the activity of ethylene is extremely high, so that the polymerization of ethylene and the conversion reaction to hydrocarbon are likely to occur. As in the case of the reaction between toluene and methanol, a large amount of by-products are produced.

FIG. 2 shows a conventional process of reacting an aromatic hydrocarbon with an alkylating agent. In FIG. 2, the aromatic hydrocarbon (such as benzene) and the alkylating agent (such as ethylene) 4 are
Together, they are supplied to the upper part of the catalyst layer 5, react while moving in the catalyst layer 5, and are discharged from the lower part of the catalyst layer 5 as a product (mixture of p-xylene or the like) 6.

[0005]

According to the above-mentioned conventional reaction method, a large amount of by-products such as alkanes is produced. Further, the product obtained by the above conventional reaction method can be separated by an adsorption separation method to obtain p-xylene, but the separation apparatus used in the adsorption separation method is complicated and expensive. Furthermore, demand for p-xylene is expanding, and reduction in production cost is demanded. Therefore,
An object of the present invention is to selectively alkylate an aromatic hydrocarbon such as benzene while suppressing the generation of by-products,
-To provide a method for obtaining a target compound such as xylene in a high yield.

[0006]

The selective alkylation of an aromatic hydrocarbon according to the present invention is directed to a method for moving an aromatic hydrocarbon in a catalyst layer with respect to an aromatic hydrocarbon passing through the catalyst layer. (2) supplying an alkylating agent at a plurality of sites along (a) to cause the aromatic hydrocarbon to undergo an alkylation reaction. In the selective alkylation method of the present invention, benzene can be used as the aromatic hydrocarbon, and ethylene can be used as the alkylating agent. In this case, the main product is p-xylene (claim 2). In the selective alkylation method of the present invention, toluene can be used as an aromatic hydrocarbon and methanol can be used as an alkylating agent. In this case, the main product is p-
Xylene (claim 3).

[0007] In the selective alkylation process of the present invention, when the main product is p-xylene, the catalyst is listed in Table 2:

[Table 2] (VS: very strong, S: strong, M: intermediate, W: weak)
And aR ₂ O · bMO · (1
_{-B) Al 2 O 3 · ySiO} 2 ( wherein, R is an alkali metal ion or hydrogen ion, M is an alkaline earth metal ion or an iron ion, a, b, y, respectively,
0.6 <a <1.3, 0 ≦ b ≦ 1, y ≧ 18 are satisfied. ) Is added to the crystalline silicate having the chemical composition
Those supporting an alkaline earth metal oxide in an amount of up to 30% by weight are preferably used (claim 4).

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the aromatic hydrocarbon used in the present invention include benzene and toluene. As the alkylating agent, for example, when benzene is used as the aromatic hydrocarbon, ethylene is used, and when toluene is used as the aromatic hydrocarbon, methanol is used.

[0009] The alkylating agent is supplied at a plurality of sites along the moving direction of the aromatic hydrocarbon in the catalyst layer.
This will be described with reference to FIG. 1. The aromatic hydrocarbon 1 supplied from the upper portion of the catalyst layer shown in FIG. Discharged as 3. The alkylating agent has a plurality of sites a, b, and a along a moving direction of the aromatic hydrocarbon in the catalyst layer.
c, d... n. In this way, by supplying the alkylating agent at a plurality of sites, the molar ratio of the aromatic hydrocarbon / alkylating agent can be made higher than the stoichiometric ratio. Thereby, the polymerization of ethanol or the decomposition of methanol and the conversion reaction to hydrocarbon can be suppressed, and the generation of by-products such as alkanes can be suppressed.

In the selective alkylation method of the present invention,
The reaction temperature of the alkylation reaction is preferably from 250 to 650 ° C.
300-600 ° C, more preferably 400-500 ° C
° C. If the temperature is lower than 250 ° C., sufficient activation energy
Energy, so xylene is not produced.
Above 650 ° C, toluene, methanol
Disadvantage of the decomposition of ethylene, ethylene and benzene
is there. Reaction pressure is 0 to 50 kg / cm^TwoG, preferably
Is from 0 to 40 kg / cm^TwoG, more preferably 0-3
0kg / cm^TwoG. Reaction pressure is 50kg / cm ^Two
Above G, there is no problem in the reaction, but the plant efficiency
Is reduced.

The LHSV is 0.5 to 40 h ^-1 , preferably ¹ to 30 h ^-1 , more preferably 10 to 20 h ^-1 . When it is less than 0.5 h ⁻¹ , there is a disadvantage that decomposition or polymerization of ethylene or methanol is apt to occur.
If it exceeds ⁰ h ⁻¹ , there is a disadvantage that the reactivity decreases. The LHSV is calculated from the formula: LHSV (h ^-1 ) = feed amount (m ³ / hour) / catalyst amount (m ³ ). The molar ratio of the aromatic hydrocarbon / alkylating agent is 2-6.
0, preferably 3 to 50, more preferably 5 to 30. When the molar ratio is less than 2, there is a disadvantage that the alkylating agent is significantly decomposed, and when it exceeds 60, there is a disadvantage that xylene is hardly generated.

When the main product obtained by the selective alkylation method of the present invention is p-xylene, a preferred catalyst used is, for example, Table 3:

[Table 3] VS: very strong S: Strong M: Intermediate W: has a crystal lattice spacing shown in _{weak, aR 2 O · bMO · (} 1
_{-B) Al 2 O 3 · ySiO} 2 ( wherein, R is an alkali metal ion or hydrogen ion, M is an alkaline earth metal ion or an iron ion, a, b, y, respectively,
0.6 <a <1.3, 0 ≦ b ≦ 1, y ≧ 18 are satisfied. ) Is added to the crystalline silicate having the chemical composition
Carrying 30 to 30% by weight, preferably 1 to 20% by weight, more preferably 4 to 16% by weight (% by weight indicates a proportion of the total amount with the crystalline silicate) of the alkaline earth metal oxide Can be mentioned.

In the above formula, examples of the alkali metal ion represented by R include sodium and potassium, and preferably sodium. Examples of the alkaline earth metal ion represented by M include magnesium, calcium, barium and the like, and preferably magnesium. Examples of the alkaline earth metal oxide supported on the crystalline silicate include magnesium oxide, calcium oxide, barium oxide and the like, and preferably magnesium oxide.

The catalyst comprising the crystalline silicate or the like
It has pores with a diameter of about 6 ° which are equivalent in size to the molecule of p-xylene. By using this catalyst, p-xylene can be selectively produced at a concentration higher than the thermodynamic equilibrium composition. This catalyst may be used in the form of granules or pellets, or may be used in the form of a monolith.

[0015]

EXAMPLES Synthesis Example 1 The catalyst used in the present invention was synthesized as follows. 230
g of water, 240 g of water glass (Na ₂ O · 3.4Si
O ₂ · 24H ₂ O) was dissolved to prepare solution A. Next, 6.0 g of aluminum sulfate (Al ₂ (SO ₄ ) ₃ .1) was mixed in a mixture of 152 g of water and 126.9 g of hydrochloric acid.
7H ₂ O) and 11.2 g of sodium chloride were dissolved to prepare a solution B. The hydrochloric acid serves to adjust the ratio of Na ₂ O / SiO ₂ to a desired range by neutralizing the excess alkali present.

Next, the solution B is mixed with the solution A,
Minutes. Further, after 46 g of tetrapropylammonium bromide was added, the mixture was reacted at 180 ° C. for 3 days with vigorous stirring in a stainless steel autoclave lined with 1 liter of polytetrafluoroethylene. After filtering and washing the cooled solids, 1
After drying at 20 ° C. for 12 hours, a sodium-containing crystalline silicate was obtained. The crystal size of this crystalline silicate is 2
The composition excluding the organic compound is about 0 μm.
1Na ₂ O · Al ₂ O ₃ · 160SiO ₂ and Si
The / Al ratio was 80.

This crystalline silicate was immersed in 1N hydrochloric acid, treated at 80 ° C. for 3 days, and sodium ions were replaced by hydrogen ions by a conventional method. This was washed and filtered, dried at 120 ° C. for 12 hours, and further calcined at 500 ° C. for 5 hours to obtain a hydrogen-substituted crystalline silicate catalyst.
Further, 10 g of the hydrogen-substituted crystalline silicate was immersed in an aqueous solution in which 6.4 g of magnesium nitrate (Mg (NO ₃ ) ₂ .6H ₂ O) was dissolved in 100 g of water.
After drying at 120 ° C., it was further baked at 550 ° C. for 5 hours. As a result, a crystalline silicate supporting 10% by weight of magnesium oxide (MgO) was obtained.

Example 1 Benzene was passed through a catalyst layer (length: 20 cm) packed with a catalyst in which hydrogen-substituted crystalline silicate supported an oxide of an alkaline earth metal in an amount of 1 to 20% by weight, and ,
0 cm, 2 cm, 4 cm, 6 cm, from the upstream side of the catalyst layer,
Ethylene was supplied from a total of 10 alkylating agent supply ports at 8 cm,..., 18 cm. Table 4 shows the results.

[0019]

[Table 4]

The compositions of catalysts 1 to 4 in Table 4 are as follows. 1) Catalyst 1: a catalyst obtained by adding 10% by weight of MgO to the hydrogen-substituted crystalline silicate shown in Example 1; 2) Catalyst 2: 4% by weight of BaO to the hydrogen-substituted crystalline silicate shown in Example 1 added catalyst; 3) catalyst _{3: 1.2H 2 O · 0.5BaO ·} 0.5Al
₂ O ₃ · 20SiO catalyst 4 was added CaO of 1 wt% hydrogen substitution type crystalline silicate having a _second chemical composition) Catalyst _{4: 0.7H 2 O · 0.3Fe 2} O 3 · 0.7
Catalyst in which hydrogen-substituted crystalline silicate having a chemical composition of Al ₂ O ₃ .20 SiO ₂ is added with 20% by weight of BaO

The definitions of p-xylene selectivity and ethylene alkylation rate in Table 4 are as follows. 1) p-xylene selectivity (%) = amount of p-xylene formed (mol / h) / amount of xylene formed (mol / h) × 100; 2) Alkylation rate of ethylene (%) = used for alkylation Amount of ethylene (mol / h) / Amount of reacted ethylene (mol / h) × 100

Example 2 Toluene was passed through a catalyst layer (length: 20 cm) packed with a catalyst in which hydrogen-substituted crystalline silicate supported an oxide of an alkaline earth metal in an amount of 1 to 20% by weight, and ,
0 cm, 2 cm, 4 cm, 6 cm, from the upstream side of the catalyst layer,
Methanol was supplied from a total of 10 alkylating agent supply ports at 8 cm,..., 18 cm. Table 5 shows the results.

[0023]

[Table 5] Catalysts 1 to 4 in Table 5 are the same as Catalysts 1 to 4 in Table 4. The definitions of p-xylene selectivity and methanol alkylation rate in Table 5 are as follows. 1) p-xylene selectivity (%) = amount of p-xylene formed (mol / h) / amount of xylene formed (mol / h) × 100; 2) Alkylation rate (%) of methanol = used for alkylation Methanol amount (mol / h) / reacted methanol amount (mol / h) × 100

COMPARATIVE EXAMPLE 1 Table 6 shows the results of an alkylation reaction in which benzene and ethylene were simultaneously supplied to a Friedel-Crafts catalyst (aluminum chloride) catalyst layer.

[0025]

[Table 6]

Comparative Example 2 Table 7 shows the results of an alkylation reaction in which toluene and methanol were simultaneously supplied to a catalyst layer of a Friedel-Crafts catalyst (aluminum chloride).

[0027]

[Table 7]

[0028]

According to the alkylation method of the present invention, it is possible to suppress the formation of by-products such as alkanes in the alkylation of aromatic hydrocarbons such as benzene. In addition, by using benzene or toluene as a raw material for alkylation and using a catalyst having a specific composition, the generation of compounds other than p-xylene can be suppressed, and a high content ratio equal to or higher than the thermodynamic equilibrium composition Can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process for producing an alkylated aromatic hydrocarbon using the selective alkylation method of the present invention.

FIG. 2 is a diagram showing a process for producing an alkylated aromatic hydrocarbon when an aromatic hydrocarbon and an alkylating agent are simultaneously supplied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aromatic hydrocarbon 2 Catalyst layer 3 Product 4 Aromatic hydrocarbon and alkylating agent 5 Catalyst layer 6 Product a, b, c, d, n Alkylating agent supply site

Claims (5)

[Claims] An alkylating agent is supplied to an aromatic hydrocarbon passing through a catalyst layer at a plurality of positions in the catalyst layer along a moving direction of the aromatic hydrocarbon, and the aromatic hydrocarbon is supplied to the aromatic hydrocarbon. And a method for the selective alkylation of aromatic hydrocarbons. 2. The aromatic hydrocarbon is benzene,
The method for selective alkylation of an aromatic hydrocarbon according to claim 1, wherein the alkylating agent is ethylene, and a main product of the alkylation reaction is p-xylene. 3. The method according to claim 2, wherein the aromatic hydrocarbon is toluene,
The method for selective alkylation of an aromatic hydrocarbon according to claim 1, wherein the alkylating agent is methanol, and a main product of the alkylation reaction is p-xylene. 4. The catalyst as defined in Table 1: (VS: very strong, S: strong, M: intermediate, W: weak)
And aR ₂ O · bMO · (1
_{-B) Al 2 O 3 · ySiO} 2 ( wherein, R is an alkali metal ion or hydrogen ion, M is an alkaline earth metal ion or an iron ion, a, b, y, respectively,
0.6 <a <1.3, 0 ≦ b ≦ 1, y ≧ 18 are satisfied. ) Is added to the crystalline silicate having the chemical composition
The method for selectively alkylating aromatic hydrocarbons according to claim 2 or 3, wherein the method supports an alkaline earth metal oxide in an amount of 30 to 30% by weight. 5. The reaction temperature of the alkylation reaction is 250.
６650 ° C. and a reaction pressure of 0-50 kg / cm ² G
Wherein the LHSV is 0.5 to 40 h ^-1 and the molar ratio of aromatic hydrocarbon / alkylating agent is 2 to 60. Alkylation method.