JP2767997B2 - Method for producing dimethylnaphthalene isomer mixture with increased 2,6-dimethylnaphthalene concentration - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a dimethylnaphthalene isomer mixture, and more particularly, to a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is increased. And a method for producing the same.

(Prior Art) Dimethylnaphthalene, for example, 2,6-dimethylnaphthalene, is used as a raw material such as polyethylene naphthalate (PEN) having high heat resistance and gas barrier properties, and a raw material containing a dimethylnaphthalene isomer mixture as a main component. Separated from oil.

Dimethylnaphthalene is a compound in which two methyl groups are bonded to a naphthalene skeleton, and has various isomers.
Therefore, the concentration of individual isomers was low, and the effective use of the isomer mixture after separation of the required isomers was necessary. For example, the thermodynamic equilibrium concentration of 2,6-dimethylnaphthalene in the total dimethyl form is about 14%, and the raffinate after separation is effectively used to increase the 2,6-dimethyl form concentration. A conversion reaction, such as isomerization or transalkylation, was required.

Such isomerization or transalkylation reaction relates to the transfer of a substituted alkyl group in one molecule or the transfer of a substituted alkyl group between two kinds of molecules, and is usually performed by using various solid acid catalysts such as aluminosilicate and zeolite. (See, for example, Kozo Tanabe et al., “New Solid Acids and Base
s ", Kodansha-Elsevier, 1989) or a Lewis acid catalyst comprising a metal halide such as aluminum chloride in a gaseous or liquid phase under a hydrogen atmosphere. In particular, 2,6-dimethylnaphthalene is obtained. As the method, for example, JP-A-62-187416, JP-A-63-135341, JP-A-63-187341
146834, JP-A-63-150233, JP-A-63-275528 and the like.

The method for producing a dimethylnaphthalene isomer mixture includes, in addition to the above-mentioned methods, a disproportionation reaction from monomethylnaphthalene, trimethylnaphthalene, etc., methanol of naphthalene and / or monomethylnaphthalene, methyl chloride, methyl formate, formaldehyde or methylal. And a transalkylation reaction of naphthalene and / or monomethylnaphthalene with methylbenzenes such as toluene and xylene. As these methods, a method using a mordenite having pores structurally in one-dimensional direction as a catalyst (for example, Japanese Patent Publication No.
37415, JP-B-47-37416, etc.), a method using a faujasite-type zeolite as a catalyst (for example, JP-A-63-14737,
JP-A-63-14738, JP-A-63-14739, JP-A-63-8344
Etc.), a method using a pentasil type zeolite having a 10-membered oxygen ring as a catalyst (for example, JP-A-59-88433,
JP-A-60-69042, JP-A-60-45536 and the like are known.

(Problems to be Solved by the Invention) However, the method (1) has a drawback that coke precipitation is severe due to the strong acid strength of the catalyst used, and pore blocking due to the structure is liable to occur, and the reaction activity is rapidly reduced. there were. Further, the faujasite-type zeolite used in the above method also has a drawback that clogging occurs due to coke precipitation inside the pores, and as a result, the reaction activity is sharply reduced. In the further method, excellent reaction activity is exhibited due to the specific acid strength. However, in the case of isomerization reaction between dimethylnaphthalene, coke is generated more than in the xylene formation reaction, and it is difficult to avoid a decrease in activity over time. Met. Further, in these methods, it is possible to frequently carry out regeneration treatment in order to avoid a decrease in reaction activity and maintain the activity, but there is a disadvantage that the operation cycle becomes short and the industrial efficiency decreases. .

(Means for Solving the Problems) The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, the diethylnaphthalene isomer having a 2,6-dimethylnaphthalene concentration lower than the thermodynamic equilibrium concentration. By reacting the mixture in the presence of a specific catalyst, 2,6
-It has been found that a dimethylnaphthalene isomer mixture in which the concentration of dimethylnaphthalene has been increased can be stably obtained over a long period of time, and that the amount of lower olefins in the by-product gas generated from the reaction system is extremely small, and reached the present invention. did.

That is, an object of the present invention is to react a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is smaller than the thermodynamic equilibrium concentration in the presence of a solid acid catalyst, thereby obtaining the concentration of 2,6-dimethylnaphthalene. a method for producing the dimethylnaphthalene isomer mixture having an increased, as a solid acid catalyst, the general formula M _{2 / m} O below an oxide molar _{ratio: xAl 2 O 3: yNiO:} zSiO 2: nH 2 O ( wherein , M represents at least one alkali metal or alkaline earth metal having a valence m, m is 1-2, x
Is 0 to 1, y is 0.01 to 10, z is 2 to 100, and n is 1
Represents ~ 20. This is easily achieved by a method for producing a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is increased, characterized by using the crystalline nickel-containing metallosilicate represented by the formula (1).

 Hereinafter, the present invention will be described in detail.

The dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene in the present invention is smaller than the thermodynamic equilibrium concentration is 2,6-dimethylnaphthalene and its positional isomer, that is, 2,7-dimethylnaphthalene, 3-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,8-dimethylnaphthalene, 1,7-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1.5-dimethylnaphthalene, 1,4-dimethylnaphthalene, and 1,2- A mixture of isomers containing at least one of the nine dimethylnaphthalenes, wherein the concentration of 2,6-dimethylnaphthalene in all isomers is lower than the thermodynamic equilibrium concentration of the isomers.

The isomer mixture can be obtained from an aromatic hydrocarbon feedstock containing a dimethylnaphthalene isomer mixture by a known method, for example, column chromatography using a specific adsorbent and a desorbing agent, and further separation and crystallization. It can be easily obtained by a method for separating 2,6-dimethylnaphthalene (Japanese Patent Laid-Open No. 1-168628), which is combined with precipitation and separation. More specifically, it is preferable that the concentration of 2,6-dimethylnaphthalene in all isomers of dimethylnaphthalene is about 0.1 to 10%, preferably about 0.2 to 5%.

Further, in this isomer mixture, naphthalene, methylnaphthalene, ethylnaphthalene, methylethylnaphthalene, trimethyltephthalene, tetramethylnaphthalene,
It may contain other aromatic hydrocarbons such as biphenyl, methyl biphenyl, etc., but these are usually 50% or less, preferably 10% or less of the whole.

In the present invention, starting from such a mixture of isomers, 2,6-
This is to obtain a dimethylnaphthalene isomer mixture in which the concentration of dimethylnaphthalene is increased. Here, increasing the concentration of 2,6-dimethylnaphthalene means that the concentration of 2,6-dimethylnaphthalene in the isomer mixture as a starting material is higher than, for example, near or above the thermodynamic equilibrium concentration. Specifically, it means that the concentration of 2,6-dimethylnaphthalene in all the isomers of dimethylnaphthalene is about 10 to 20%.

In the present invention, the following oxide molar ratio as solid acid catalyst used to obtain such a 2,6-dimethylnaphthalene dimethylnaphthalene isomer mixture having an increased concentration of the general formula _{M 2 / m O: xAl 2} O ₃ : yNiO: zSiO ₂ : nH ₂ O (wherein M represents at least one alkali metal or alkaline earth metal having a valence of m, and m is 1 to
2, x is 0-1, y is 0.01-10, z is 2-100,
n represents 1 to 20. The crystalline nickel-containing metallosilicate represented by) is used. Here, the crystalline nickel-containing metallosilicate contains nickel, and at least a part or all of the nickel may be at a tetrahedral substitution position forming a zeolite skeleton, or at least one kind having a valence m. It may exist in a form ion-exchanged with an alkali metal or an alkaline earth metal M or in a supported state. Preferably, the tetrahedral substitution position forming the zeolite skeleton is better.

Further, the crystalline nickel-containing metallosilicate of the present invention has a molar ratio of SiO ₂ / Al ₂ O ₃ , that is, z / x ≧ 3, preferably z / x ≧ 5, and SiO ₂ / NiO I.e., z / y
≦ 5000, preferably z / y ≦ 2000. And such metallosilicate is structurally mordenite,
Faujasite, Omega, Beta, ZSM-5, ZSM-8
Type, a structure such as ZSM-11 type, but more preferably Z
Those having an SM-5 type structure are preferred. That is, as the crystalline nickel-containing metallosilicate of the present invention, ZSM-
Having an X-ray diffraction pattern of type 5 zeolite, and silicon,
Crystalline nickel-containing metallosilicates having a crystallographic skeleton containing nickel and aluminum or silicon and nickel are most preferred.

Such crystalline nickel-containing metallosilicates are described, for example, in JP-A-61-64333 or "Catalyst" Vol. 28, No. 2, p.
(1986) and the like.

Examples of the nickel salt to be used include nickel nitrate and nickel sulfate. In addition, as a method of containing nickel, a method of impregnating these nickel salts or an ion-exchange method of ion-exchanging nickel can be used to contain nickel, in addition to a hydrothermal synthesis method. Furthermore, if necessary, molybdenum, tungsten, vanadium, iron,
Elements such as bismuth, copper or cobalt may be added to the catalyst of the present invention in the form of sulfide or oxide. The addition amount of such a compound may be about 0.5 to 20% by weight. The catalyst used in the present invention is converted into H-type (proton) by a conventional ion exchange and calcining method, and used as a catalyst.

The crystalline nickel-containing metallosilicate obtained in this manner contains a binder such as boehmite, alumina, kaolin or silica in an amount of usually 5 to 50% by weight, preferably 10 to 50% by weight.
About 30% by weight is mixed and granulated by extrusion molding method, etc.
It may be used in the form of pellets, spheres, etc., in which case the particle size is not particularly limited, but is usually about 0.5 to 5 mm, and the surface area of the catalyst is generally in the range of 200 to 700 m ² / g. It is better to select and use. In addition, such a binding nickel-containing metallosilicate catalyst maintains high activity for a long time, but can be regenerated after the reaction by oxidation treatment with an oxygen-containing gas or hydrogenation treatment with a hydrogen-containing gas.

In the present invention, such a crystalline nickel-containing metallosilicate is used as a catalyst, and the concentration of 2,6-dimethylnaphthalene described above is 2,6-dimethylnaphthalene from a mixture of dimethylnaphthalene isomers smaller than the thermodynamic equilibrium concentration. A dimethylnaphthalene isomer mixture with an increased concentration is obtained, but in such a reaction zone, conversion reactions such as the above-mentioned isomerization reaction, disproportionation reaction, alkylation reaction or transalkylation reaction occur in a complicated manner, and the reaction is terminated. At this point, a dimethylnaphthalene isomer mixture having an increased concentration of 2,6-dimethylnaphthalene is obtained.

The conditions for the reaction are not particularly limited as the reaction temperature, and may be generally selected from the range of 200 to 500 ° C, preferably 250 to 450 ° C. The reaction can be carried out under normal pressure or under pressure, and can be carried out in either a liquid phase or a gas phase. The reaction method may be either a batch method or a continuous method. In the reaction atmosphere, the catalytic activity is likely to be degraded in the absence of hydrogen. Therefore, the presence of hydrogen gas is preferable from the viewpoint of maintaining the catalytic activity.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

The product was analyzed by gas chromatography, and the coke amount was analyzed by a combustion method.

Example 1 Aluminum sulfate hydrous salt (manufactured by Wako Pure Chemical Industries, Ltd.) 15.3
g, 12.7 g of nickel sulfate (manufactured by Wako Pure Chemical Industries, Ltd.), 24.8 g of sulfuric acid (manufactured by Kokusan Chemical Co., Ltd.), 23.0 g of tetrapropylammonium bromide (TPABr) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 240 g of water.
A solution dissolved in 1 g was designated as solution A, and a mixture of 275.5 g of water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.) and 180.7 g of water was designated as solution B. Further, sodium chloride (manufactured by Kishida Chemical Co., Ltd.) 105.3 g
g, sulfuric acid 11.4 g, tetrapropylammonium bromide 8.
Solution C was obtained by dissolving 60 g of sodium hydroxide (95% purity of Junsei Chemical Co., Ltd.) in 416.6 g of water.

Solution A and solution C were added to solution B with stirring, and the resulting gel was stirred for 30 minutes thereafter. Next, leave for 30 minutes,
After cooling, the mixture was charged into a 2 liter autoclave, and the temperature was raised from room temperature to 156 ° C. in 1.5 hours with stirring and then 216 ° C. in 3 hours and 10 minutes.
Up to a constant speed. After cooling, the slurry is filtered,
After washing with water, the solid was further sufficiently washed with warm water to obtain 79.3 g of a nickel-containing aluminosilicate powder. The filterability was extremely good, and adhesion to the inner wall of the autoclave was hardly observed. The ratio of SiO ₂ / Al ₂ O ₃ after synthesis is 52, the ratio of SiO ₂ / NiO ₂ is 29, and the charge ratio (SiO ₂ / Al ₂ O ₃ = 55, SiO ₂ / NiO ₂ = 28)
And matched. Furthermore, X-ray diffraction showed a pattern similar to pure ZSM-5, and no peak derived from NiO was detected.

The resulting nickel-containing aluminosilicate is 1.25M
Using ammonium nitrate at a concentration of 1/10 (g / m
l), ion exchange treatment was performed by diffraction at 100 ° C. for 2 hours. This process was repeated twice later. After ion exchange treatment,
Washed with warm water and dried at 120 ° C. overnight. Next, it was calcined at 540 ° C. for 5 hours under air flow. The obtained H-type nickel-containing aluminosilicate has a SiO ₂ / Al ₂ O ₃ ratio of 52, SiO ₂ / NiO
_{The two} ratio was 38. This was tablet-molded, adjusted to 10 to 20 mesh, and used as a catalyst for the reaction.

2.56 g of the above catalyst was placed in a glass reaction tube having an inner diameter of 20 mm, and kept at 400 ° C. under a hydrogen stream. The reaction was carried out under normal pressure at a hydrogen flow rate of 3.6 l / hr and a raw material flow rate of 6 g / hr for 8 hours. The starting material used was a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene was reduced to 2.8% of all dimethylnaphthalene isomers by chromatographic separation.

One hour after the start of the reaction, all the dimethylnaphthalene isomers
When the concentration of 2.6-dimethylnaphthalene was used as the initial activity value, the decrease rate to the activity value after 8 hours was 9.1%.
Met. Table 2 shows the composition of the by-product gas at this time. Further, the amount of coke accumulated on the catalyst after the reaction was measured and was found to be 0.9% with respect to the amount of the catalyst.

Comparative Example 1 Synthesis was performed in exactly the same manner as in Example 1 except that nickel sulfate was not used. The charging ratio at this time was SiO ₂ / Al
_{The 2} O ₃ ratio was 55 and that of the product was 50. In X-ray diffraction,
A pure ZSM-5 pattern was shown. Next, the synthetic product was subjected to ion exchange treatment and reaction in exactly the same manner as in Example 1.

One hour after the start of the reaction, all the dimethylnaphthalene isomers
When the concentration of 2,6-dimethylnaphthalene was used as the initial activity value, the reduction rate to the activity value after 8 hours was 19.5%.
Met. The total amount of by-product gas at this time was determined in Example 1.
And the composition is as shown in Table 2.

Further, when the amount of coke accumulated on the catalyst was measured,
It was 2.5% based on the catalyst amount.

Example 2 Na type ZSN-5 (manufactured by Nippon Mobile Catalyst Co., Ltd., SiO ₂
/ Al ₂ O ₃ molar ratio 70) 33 g together with 52.8 g of ammonium nitrate and 330 ml of an aqueous solution prepared by dissolving 96.0 g of nickel nitrate hexahydrate in 1 were placed in a four-necked round-bottomed flask and subjected to ion exchange while stirring at 100 ° C. for 2 hours. . This ion exchange treatment was performed two more times.

Next, the resultant was washed with warm water, dried at 120 ° C. for 24 hours, and then calcined at 540 ° C. for 5 hours in an air stream to obtain nickel-containing H-type ZSM-5. This was tableted, crushed to 10 to 20 mesh, and used as a catalyst. 2.24 g of the catalyst was placed in a glass reaction tube having an inner diameter of 20 mm, and a hydrogen flow rate of 3.6 l / hr under normal pressure, 400
The reaction was carried out at a temperature of 6.0 ° C. and a raw material flow rate of 6.0 g / hr. The dimethylnaphthalene isomer mixture used in Example 1 was used as a raw material. The reaction results are shown in Tables 1 and 2.

Comparative Example 2 15.6 g of ammonium nitrate was added in the ion exchange treatment.
Ion exchange and reaction were carried out in exactly the same manner as in Example 2 except that a solution dissolved in water was used. The results are shown in Tables 1 and 2.

The isomerization activity was as follows: Ni-containing H-type ZSM-5 (Ni / H
It can be seen that the activity is low both in the initial stage and after 10 hours, despite the fact that there are about twice as many active points as the protons as compared to the ratio of 0.5).

(Effect) According to the present invention, a specific crystalline nickel-containing metallosilicate is used as a catalyst to stably obtain a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is increased over a long period of time. be able to.

Further, the amount of highly reactive lower olefins in the by-product gas generated from the reaction system is extremely small, and when the reaction is performed in the presence of hydrogen gas, the hydrogen gas can be easily recycled.

 From the above points, the industrial utility value is extremely high.

Claims (6)

(57) [Claims] A dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is smaller than the thermodynamic equilibrium concentration is reacted in the presence of a solid acid catalyst to obtain 2,6-dimethylnaphthalene.
A method for producing the dimethylnaphthalene isomer mixture having an increased concentration of dimethyl naphthalene as a solid acid catalyst, the general formula M _{2 / m} O below an oxide molar _{ratio: xAl 2 O 3: yNiO:} zSiO 2: nH 2 O (wherein M represents at least one alkali metal or alkaline earth metal having a valence m, m is 1-2, x
Is 0 to 1, y is 0.01 to 10, z is 2 to 100, and n is 1
Represents ~ 20. A method for producing a dimethylnaphthalene isomer mixture in which the concentration of 2,6-dimethylnaphthalene is increased, comprising using the crystalline nickel-containing metallosilicate represented by the formula (1). 2. The method according to claim 1, wherein the crystalline nickel-containing metallosilicate has part or all of the nickel contained in the metallosilicate at tetrahedral substitution positions. 3. The method according to claim 1, wherein the crystalline nickel-containing metallosilicate has a molar ratio of z / x ≧ 3. 4. The method according to claim 1, wherein the crystalline nickel-containing metallosilicate has a molar ratio z / y ≧ 5000. 5. The method according to claim 1, wherein the nickel in the crystalline nickel-containing metallosilicate is present in an ion-exchanged form with at least one alkali metal or alkaline earth metal M having a valence m. The described method. 6. The method according to claim 1, wherein the nickel in the crystalline nickel-containing metallosilicate is present in a supported state.