JPH0717879A - Production of 2,6-dimethylnaphthalene - Google Patents

Abstract

PURPOSE:To obtain 2,6-dimethylnaphthalene in a high yield by using butadiene and p-xylene. CONSTITUTION:p-xylene and butadiene are made to react with each other in the presence of zeolite, silica-alumina and heteropolyacid and/or ion-exchange resin having acidic groups to obtain butenyl-p-xylene. The reactional product is subjected to dehydrocyclization to obtain 2,6-dimethylnaphthalene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention performs an alkenylation step of synthesizing butenylparaxylene from paraxylene and butadiene in the presence of a catalyst such as an acid type zeolite, and then dehydrocyclizing butenylparaxylene to give 2 , 6-Dimethylnaphthalene to produce 2,6-
The present invention relates to a method for industrially synthesizing dimethylnaphthalene. By oxidizing 2,6-dimethylnaphthalene, 2,6-naphthalenedicarboxylic acid can be obtained. 2,6-naphthalenedicarboxylic acid is industrially important as a raw material for engineering plastics. For example, a PEN resin obtained from 2,6-naphthalenedicarboxylic acid and ethylene glycol has excellent heat resistance and strength, and has many industrially important uses.

[0002]

2. Description of the Related Art As a method for obtaining 2,6-dimethylnaphthalene, there is a method of separating and purifying it from coal tar or FCC cycle oil, but the concentration of 2,6-dimethylnaphthalene is low and it can be separated from many isomers. In addition to being difficult, the yield is small, and there are many problems as a method for obtaining an industrially stable product. Further, as a method of synthetically obtaining 2,6-dimethylnaphthalene, for example, German Patent Publication-3334084 discloses a method of methylating naphthalene or methylnaphthalene to obtain 2,6-dimethylnaphthalene using a zeolite catalyst. . However, this method cannot always synthesize 2,6-dimethylnaphthalene with industrially satisfactory selectivity. JP-A-60-94926
The official gazette discloses a method of increasing the concentration of 2,6-dimethyl compound by isomerizing a dimethylnaphthalene mixture, but it has not been possible to selectively obtain only the 2,6 compound.

On the other hand, US Pat. No. 3,244,758 discloses a method of obtaining 2,6-dimethylnaphthalene through alkenylation of a methyl group of orthoxylene with butadiene, followed by cyclization, dehydrogenation and isomerization. However, this method is not an industrially advantageous method because the process is complicated and butadiene is polymerized. JP-A-4-95035 discloses a method of synthesizing 2,6-dimethylnaphthalene through acylation of toluene with butene and carbon monoxide, followed by hydrogenation and dehydrocyclization. This method is 2,6-
Although it is ambiguous in that the dimethyl compound is selectively obtained, it is not industrially advantageous in that the process is complicated and a corrosive substance such as hydrogen halide is used for the reaction, and the yield is not satisfactory.

[0004]

As described above, various methods have been proposed so far as a method for synthesizing 2,6-dimethylnaphthalene, but none of them is satisfactory from an industrial viewpoint. Therefore, an object of the present invention is to provide a method for producing 2,6-dimethylnaphthalene with industrially satisfactory results using raw materials that are industrially inexpensive and easily available.

[0005]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, butadiene and paraxylene were used as raw materials,
It has been found that a method of synthesizing butenylparaxylene and further synthesizing a target product, 2,6-dimethylnaphthalene, from this compound is extremely effective.

The present invention provides a method for producing 1,6-dimethylnaphthalene in the presence of cation exchange resin having zeolite, silica-alumina, heteropolyacid, and / or acidic group from paraxylene and butadiene. And an alkenylation step for synthesizing butenylparaxylene, followed by a dehydrocyclization step for synthesizing butenylparaxylene by dehydrocyclization to synthesize 2,6-dimethylnaphthalene. A method for producing 6-dimethylnaphthalene. "

[0007]

That is, the present invention provides a method for producing 2,6-dimethylnaphthalene, which is an alkenylation step of synthesizing butenylparaxylene from paraxylene and butadiene, and dehydrocyclization of butenylparaxylene to give 2,6-dimethylnaphthalene. The present invention provides the production of 2,6-dimethylnaphthalene, which is characterized by sequentially undergoing a reaction step consisting of a dehydrocyclization step for synthesizing. Furthermore, it was found that in the alkenylation step, butenyl paraxylene can be efficiently synthesized by carrying out the reaction in the presence of an acid type zeolite, silica-alumina, heteropolyacid, and / or ion exchange resin and a catalyst. From the raw material side, it is a raw material that can be industrially obtained in large quantities together with butadiene and paraxylene, and is an inexpensive raw material. On the other hand, when viewed from the product side, there are few dimethylnaphthalene isomers that can be produced when 2,6-dimethylnaphthalene is obtained by the method of the present invention.
Only 1,4-dimethylnaphthalene. And this one
Even when 4-dimethylnaphthalene is produced, 2,6-dimethylnaphthalene and 1,4-dimethylnaphthalene can be easily separated due to the large difference in melting points.
As described above, according to the method of the present invention, the drawbacks of the conventional method can be solved. Each step of the wood invention will be described in more detail below.

(1) Alkenylation step This is a step of alkenylating paraxylene with butadiene to synthesize butenylparaxylene. The reaction formula is as follows.

[0009]

[Chemical 1]

R: n-butenyl group

Generally, when an alkylation of an aromatic compound with an olefin is carried out under an oxidation catalyst, it is difficult to obtain the desired product because the secondary carbon of the olefin attacks the aromatic compound. When using diene,
The desired product can be selectively obtained. Acid type zeolite, silica-alumina, heteropolyacid, and / or ion exchange resin are used as the catalyst.

As the zeolite, X, Y, mordenite, β, L, Ω, ZSM-5 or the like can be used.
Since the active site of the alkenylation reaction is considered to be the acid site, some or all of the ion exchange points in the zeolite are H
It can be effectively used for the reaction by making it into a mold.
Generally, when a zeolite is ion-exchanged with a polyvalent cation, water dissociates due to an electrostatic field in the zeolite, and many acid sites are present in the polyvalent cation zeolite. The polyvalent cation exchange zeolite having such an acid point can be effectively used for the reaction. As the polyvalent cation species, alkaline earth, rare earth and the like can be easily used. On the other hand, the Si / Al ratio in the zeolite can be appropriately changed by a method such as dealumination in order to control the reaction activity. It is also possible to control the activity by exchanging part of the zeolite exchange points with an element such as an alkali metal that does not detect acidity.

As the silica-alumina, any composition exhibiting acidity can be used, but the alumina content of the commercially available synthetic silica-alumina is 28%.
This reaction can be carried out efficiently by using high alumina before and after and low alumina having an alumina content of around 14%. By exchanging a part of the acid points on the silica-alumina with an alkali metal or the like, the activity can be controlled appropriately.

As the heteropolyacid, phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, chelimolybdic acid or the like can be used. In addition, a heteropoly acid of Ge or B can be used as the central atom. The active site of alkenylation is expected to be an acid site, but the activity can be controlled and its thermal stability can be improved by exchanging a part of the cation for an alkali metal. The stability can also be increased by substituting a part of Mo and W of the coordination atom with V. It is also possible to use an acid salt of Al or a transition metal such as Cu, Ag, Ni or Zn.

This reaction is considered to be a reaction having an acidic site as an active site, and therefore a cation exchange resin having an acidic group can be used. A sulfone group, a carboxyl group, an acidic hydroxyl group or the like is used as the acidic group. Typical examples are polystyrene sulfonic acid type acidic cation exchange resins. As a form of the resin, a gel type, a porous type or the like having an arbitrary degree of crosslinking can be used. or,
Fluorine-based naphthion can also be used in this reaction.
The above ion exchange resins are commercially available under various product names,
For example, Amberlite, Amberlyst (Rohm Haas Co., Ltd.), Diaion (Mitsubishi Kasei Co., Ltd.) and the like can be mentioned, and any of them can be easily obtained.

The reaction temperature of this alkenylation reaction is usually 0.
C. to 600.degree. C., preferably 0.degree. C. to 500.degree. The reaction pressure can be any of reduced pressure, normal pressure and increased pressure. As the reaction system, any of batch system, flow system and semi-batch system can be used, and any of liquid phase reaction and gas phase reaction can be carried out.

(2) Dehydrogenative cyclization step By cyclodehydrogenating butenylparaxylene,
6-dimethylnaphthalene can be produced. The cyclization dehydrogenation reaction can be carried out by a gas phase catalytic reaction using a solid catalyst. Examples of the catalyst include Cr, Co, F
An oxide catalyst such as e or Ni, a composite oxide catalyst such as chromia alumina, a catalyst in which a Group VIII metal is supported on alumina, silica, activated carbon or the like can be used. The reaction temperature depends on the catalyst activity, but is generally in the range of 300 ° C to 800 ° C, preferably 400 ° C to 650 ° C. The reaction pressure is not particularly limited and may be normal pressure, increased pressure or reduced pressure. As the reaction type, a fixed bed flow type, a fluidized bed type, a moving bed type or the like can be used.

[0018]

【Example】

(Alkenylation Step) Example 1 A USY-type zeolite (S
10 g of iO ₂ / Al ₂ O ₃ = 6.1) was charged, and N
₂ below, warmed slowly to vigorously stirring 350 ° C., it was carried out for 2 hours pretreatment at that temperature. Then 110
While lowering the temperature to ℃ and continuing stirring, 100 m of P-xylene
1 was gradually added to the reactor. Next, N _{2 is changed} to butadiene (1
The reaction was started by switching to 0 ml / min). After 4 hours, the reactor was cooled and the reaction was completed. The butenyl para-xylene yield at this time was 16.3 on an aromatic basis.
%, And the selectivity was 98.5%.

Example 2 A reaction was carried out in the same manner as in Example 1 except that USY type zeolite having SiO ₂ / Al ₂ O ₃ = 14 was used. The butenyl paraxylene yield was 14.9% and the selectivity was 98.7%.

Example 3 The reaction was performed in the same manner as in Example 1 except that H-type mordenite (SiO ₂ / Al ₂ O ₃ = 20) was used. The butenyl paraxylene yield was 10.3% and the selectivity was 96.1%.

Example 4 The reaction was carried out in the same manner as in Example 1 except that HX type zeolite was used. The butenyl paraxylene yield was 18.8% and the selectivity was 93.6%.

Example 5 A reaction was carried out in the same manner as in Example 1 except that Hβ type zeolite (SiO ₂ / Al ₂ O ₃ = 28) was used. The butenyl paraxylene yield was 16.4% and the selectivity was 96.0%.

Example 6 A reaction was carried out in the same manner as in Example 1 except that HL type zeolite (SiO ₂ / Al ₂ O ₃ = 6) was used. The butenyl paraxylene yield was 18.5% and the selectivity was 91.2%.

Example 7 HZSM-5 type zeolite (SiO ₂ / Al ₂ O ₃ = 3)
The reaction was performed in the same manner as in Example 1 except that 5) was used. Butenyl paraxylene yield was 11.0%, selectivity was 98.
It was 1%.

Example 8 A reaction was carried out in the same manner as in Example 1 except that CeY type zeolite (SiO ₂ / Al ₂ O ₃ = 6) was used. The butenyl paraxylene yield was 21.7% and the selectivity was 91.3%.

Example 9 A 300 ml four-necked flask was charged with 10 g of silica and alumina (alumina content 28%), and the temperature was slowly raised to 350 ° C. under N ₂ with vigorous stirring, and the temperature was raised to 2
An hour pretreatment was performed. Then, 100 ml of P-xylene was gradually added to the reactor while the temperature was lowered to 110 ° C. and stirring was continued. Next, N ₂ was added to butadiene (50 ml / min)
The reaction was started by switching to. 4 hours later,
The reactor was left to cool and the reaction was completed. At this time, the butenyl paraxylene yield was 23.8% on an aromatic basis, and the selectivity was 89.
It was 6%.

Example 10 A reaction was carried out in the same manner as in Example 9 except that the reaction temperature was 20 ° C. The butenyl paraxylene yield was 18.4% and the selectivity was 90.9%.

Example 11 A reaction was carried out in the same manner as in Example 9 except that the flow rate of butadiene was 100 ml / min. The butenyl paraxylene yield was 18.0% and the selectivity was 96.7%.

Example 12 A reaction was carried out in the same manner as in Example 9 except that silica-alumina having an alumina content of 14% was used. The butenyl paraxylene yield was 16.7% and the selectivity was 92.5%.

Example 13 In a 300 ml four-necked flask, silicotungstic acid (H
10 g of ₃ SiW ₁₂ O ₄₀ ) was charged, and an exhaust treatment was performed at 100 ° C. for 2 hours. Then, 100 ml of P-xylene was gradually added to the reactor while maintaining the temperature at 110 ° C. and stirring. Next, the reaction was started by switching N ₂ to butadiene (20 ml / min). After 4 hours, the reactor was cooled and the reaction was completed. At this time, the yield of butenylparaxylene was 23.7% on an aromatic basis, and the selectivity was 86.5%.

Example 14 Phosphotungstic acid (H ₃ PW ₁₂ ) as a heteropoly acid
The reaction was performed in the same manner as in Example 13 except that O ₄₀ ) was used. The butenyl paraxylene yield was 25.1% and the selectivity was 86.3%.

Example 15 Phosphomolybdic acid (H ₃ PMo ₂ O as a heteropoly acid)
₄₀ ) was used, and the same experiment and reaction as in Example 13 were performed. The butenyl paraxylene yield at this time was 7.5.
%, The selectivity was 99.1%.

Example 16 Molybdenum silicic acid (H ₃ SiMo) was used as a heteropoly acid.
₁₂ O ₄₀ ), except that the same experiment as in Example 13 was used,
The reaction was carried out. At this time, the butenyl paraxylene yield was 14.5% and the selectivity was 88.9%.

Example 17 The same experiment and reaction as in Example 13 were carried out except that phosphomolybdic acid (H ₃ PVMo ₁₁ O ₄₀ ) in which a part of Mo was replaced with V was used as the heteropolyacid. At this time, the butenyl paraxylene yield was 11.7% and the selectivity was 89.7.
%Met.

Example 18 The same experiment and reaction as in Example 13 were carried out except that as the heteropolyacid, one in which a part of silicotungstic acid was cesium-exchanged (CsH ₂ SiMo ₁₂ O ₄₀ ) was used. At this time, the butenyl paraxylene yield was 16.5% and the selectivity was 88.8%.

Example 19 The same experiment and reaction as in Example 13 were carried out except that a silicotungstic acid partially silver-exchanged was used as the heteropolyacid. The butenyl paraxylene yield at this time was 2
The selectivity was 0.4% and the selectivity was 89.2%.

Example 20 A 300 ml four-necked flask was charged with 5 g of an ion exchange resin (Amberlyst 15) and 100 ml of P-xylene.
Was added to the reactor. The temperature was raised to 110 ° C., and then butadiene (50 ml / min) was introduced into the reactor to start the reaction. After 4 hours, the reactor was cooled and the reaction was completed. At this time, the yield of butenylparaxylene was 22.0% on the basis of aromatics, and the selectivity was 95.2%.

Example 21 A reaction was performed in the same manner as in Example 20 except that Amberlyst 31 was used as a catalyst after being treated with methanol. The butenyl paraxylene yield was 18.5% and the selectivity was 99.4%.

(Dehydrogenation cyclization step) Example 22 A reaction tube made of stainless steel having an inner diameter of 20 mm and a length of 500 mm was filled with 20 ml of Cr ₂ O ₃ -Al ₂ O ₃ catalyst, and the catalyst layer was heated to 500 ° C. In this catalyst layer, the butenyl paraxylene obtained in the above example was diluted to a concentration of 20% with a toluene solvent, vaporized at a flow rate of 20 ml / h (LHSV = 1) by a vaporizer, and then nitrogen gas was added at 3 liters / h. A reaction was sent with them. The reaction product 2 hours after the start of the reaction was analyzed by gas chromatography. The conversion of butenylparaxylene is 94%, and the selectivity of 2,6-dimethylnaphthalene is 32.
%Met.

[0040]

INDUSTRIAL APPLICABILITY The present invention has an effect of producing 2,6-dimethylnaphthalene in a high yield by using butadiene and paraxylene which are industrially easily available raw materials, with little by-products.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C07C 15/44 9280-4H // C07B 61/00 300

Claims (1)

[Claims] 1. A method for producing 2,6-dimethylnaphthalene, which comprises zeolite from paraxylene and butadiene,
Silica-alumina, heteropolyacid, and / or an alkenylation step of synthesizing butenylparaxylene in the presence of a cation exchange resin having an acidic group, followed by dehydrocyclization of butenylparaxylene to give 2,6-dimethylnaphthalene. A method for producing 2,6-dimethylnaphthalene, which comprises a reaction step including a dehydrocyclization step to be synthesized.