JPH0363535B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for catalytic isomerization of dimethylnaphthalene. In particular, the present invention relates to a catalytic isomerization process suitable for producing 2,6-isomers from dimethylnaphthalene isomer mixtures. There are 10 isomers of dimethylnaphthalene, but these isomers can be classified into the following four groups, and isomerization is easy within each group, but isomerization beyond the group is easy. isomerization is difficult. (1) 1,5-, 1,6-, 2,6-isomer (2) 1,8-, 1,7-, 2,7-isomer (3) 1,4-, 1,3- , 2,3-isomer (4) 1,2-isomer One of the main uses of dimethylnaphthalene is the production of naphthalenedicarboxylic acid, and the 2,6-isomer is particularly preferred for this use. ing. On the other hand, the dimethylnaphthalene fraction separated from the recycled oil of the FCC process, which is one of the industrial sources of dimethylnaphthalene, is a mixture of various isomers. Therefore, in order to obtain a large amount of the 2,6-isomer, it is necessary to isomerize the other isomers to the 2,6-isomer. However, although there are many known examples of isomerization between isomers within the above-mentioned set, little is known about isomerization that goes beyond the set. For example, it has been proposed to isomerize dimethylnaphthalene using mordenite, a type of zeolite, as a catalyst (see Japanese Patent Publication No. 55-47020), but this catalyst is unsuitable for isomerization across groups. The present invention is based on the finding that a zeolite whose main cavity has a 10-membered oxygen ring at its entrance has a greater isomerization ability than that of dimethylnaphthalene. That is, the present invention is characterized in that, in the catalytic isomerization method of dimethylnaphthalene, a zeolite whose main cavity entrance has a 10-membered oxygen ring is used as a catalyst. To explain the present invention in detail, the dimethylnaphthalene used as a raw material for isomerization in the method of the present invention includes synthetic dimethylnaphthalene obtained by methylating naphthalene or methylnaphthalene, and synthetic dimethylnaphthalene obtained by cracking petroleum fractions by various methods. A dimethylnaphthalene fraction separated by distillation from the resulting cracking oil is used. Preferably, the dimethylnaphthalene fraction separated by distillation from the recycled oil of the above-mentioned FCC process is used. Further, the residue obtained after separating the desired isomer from the isomerized products of these dimethylnaphthalene fractions is also used as a raw material for the method of the present invention. Since the catalyst used in the method of the present invention has a large isomerizability beyond the above-mentioned group, the present invention allows the ratio of the group to which 2,6-isomers belong to reach a thermodynamic equilibrium composition under the isomerization reaction conditions. It is advantageously applied to the isomerization of dimethylnaphthalene which is not Among them,
It applies particularly advantageously to dimethylnaphthalene, in which the proportion of the 1,8-, 1,7- and 2,7-isomer sets is greater than the thermodynamic equilibrium composition. The catalyst used in the method of the present invention is a zeolite whose main cavity has a 10-membered oxygen ring at the entrance. Such zeolites are well known, and representative ones include zeolites such as ZSM-5, 8, and 11 published by Mobil Corporation. This type of zeolite usually has a pentasil structure and its silica/alumina molar ratio is usually 12 or more. Zeolites generally have a skeletal structure composed of silica-alumina, but there are also zeolites in which iron, chromium, and other metals form part of the skeletal structure, that is, they are included as non-exchangeable metals. Although any zeolite can be used in the method of the present invention, aluminosilicate whose skeleton is composed of silica-alumina is usually used. These zeolites are used in the reaction in their acid form. As is well known, acid type zeolites have polyvalent cations such as protons and rare earth ions as cations. It is usually used in the reaction as hydrogen-type zeolite. Note that zeolite may be used as it is, or may be molded together with silica, alumina, silica-alumina, or other auxiliary agents. The zeolite used as a catalyst in the method of the present invention, whose main cavity has a 10-membered oxygen ring at the entrance, has an acid content that differs depending on the manufacturing conditions. According to the studies of the present inventors, it is determined by the gaseous base adsorption method described later.
There is a correlation between the amount of acid at 300°C and the ability to isomerize across groups of isomers, and generally, the greater the amount of acid, the greater the ability to isomerize across groups. In order to industrially perform isomerization of more than one set of isomers, it is advantageous to use an acid with an amount of 0.1 mmol/g or more, and in particular an acid with an amount of 0.45 mmol/g or more. It has been found preferable to use The isomerization of dimethylnaphthalene according to the method of the present invention is usually carried out using a fixed bed reactor, but it can also be carried out using a fluidized bed, a moving bed, or the like. The temperature of the isomerization reaction is usually 100 to 550°C, preferably 300 to 450°C, and the pressure is usually 0.1 to 100 atm, preferably normal pressure. Dimethylnaphthalene is brought into contact with the catalyst alone or diluted with a gas such as hydrogen, nitrogen, carbon dioxide, or steam. When using a fixed bed reactor, the liquid hourly space velocity of dimethylnaphthalene is usually 0.01 to 100 hr ^-1 , preferably 0.1
~5hr ^-1 . According to the method of the present invention, 1,5-, 1,6-,
2,6-isomers can be easily produced from isomers other than 2,6-isomers. Further, since the catalyst used in the method of the present invention has very little carbon precipitation and low demethylation activity, it is possible to efficiently convert the raw material dimethylnaphthalene to the 2,6-isomer. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. In the present invention, the amount of acid at 300°C determined by the gaseous base adsorption method shall be measured by the following method. Measuring device: TGA type thermal analysis device manufactured by Shimadzu Corporation with a standard ammonia gas inlet tube attached (see Figure 1) Measuring method (a) Inject helium gas at normal pressure into the device at 50 ml/min. Flow at a flow rate of This helium continues to flow until the measurement is completed. (b) Load the sample into the device. (c) Raise the temperature inside the apparatus to 500°C, maintain it for 2 hours, and measure the weight of the sample (W ₁ g). (d) Start flowing standard ammonia gas (helium gas containing 10% (by volume) ammonia) into the device at a flow rate of 50 ml/min. Ammonia is adsorbed to the sample and the weight of the sample begins to increase. (e) After confirming that the weight of the sample has reached a certain value, lower the temperature inside the device to 300℃, and maintain the temperature inside the device at 300℃ from then on until the end of the measurement. (f) Once it is confirmed that the weight of the sample has reached a certain value, stop the supply of standard ammonia gas. Ammonia adsorbed on the sample begins to be desorbed, and the weight of the sample begins to decrease. (g) When the weight of the sample reaches a certain value, measure its weight (W ₂ g). Acid amount at 300°C = (W ₂ - W ₁ ) x 1000/17 x W ₁ (mmol/g) In addition, the conversion rate and selectivity in the examples are as follows:
It was calculated using the following formula based on the following components detected by gas chromatography. Detected components: naphthalene, α and β-methylnaphthalene, α and β-methylnaphthalene,
Each isomer of dimethylnaphthalene, conversion rate (%) = total gas chromatography detection components (
mol) - Recovered raw material (mol) / Total gas chromatography detection components (mol) Selectivity (%) = Each detection component (mol) / Total gas chromatography detection components (mol) - Recovered raw material (mol) x 100 Example 1 (i) Synthesis of zeolite In a stainless steel pressure vessel with an internal volume of 100, 32.471 kg of colloidal silica (silica content 20.4% by weight),
18.8 kg of water and 7.228 kg of diglycolamine were added and stirred. A solution of 499.3 g of sodium aluminate (content: 90.3% by weight) and 726 g of sodium hydroxide dissolved in 10 kg of water was added to this, and after sealing, the container was heated to 160° C. for 3 days with stirring. The obtained product was washed with about 100 Kg of water and dried at 130°C. The product obtained has a silica/alumina ratio of 27
The diffraction pattern obtained by powder X-ray diffraction analysis is similar to that described in Example 1 of JP-A-56-92114, indicating that the entrance of the main cavity is a pentasil-type zeolite consisting of a 10-membered oxygen ring. confirmed. (ii) Conversion to acid type zeolite 36 g of the above zeolite was charged into an aqueous solution in which 53.3 g of ammonium chloride was dissolved in 200 ml of water, and the mixture was refluxed for 2 hours. After that, the same refluxing operation was repeated two more times. Then, it was washed with demineralized water until chlorine ions were removed (chlorine ions were detected using a 0.1N silver nitrate aqueous solution). Thereafter, it was dried at 130°C, molded using a powder tablet molding machine, and crushed to size 24 to 42 meshes. This was heated and calcined in air at 500°C for 3 hours to obtain an acid type zeolite. (iii) Isomerization reaction 1.5 ml of the acid type zeolite obtained above was filled into a Pyrex glass reactor with an inner diameter of 10 mm. This was placed in an electric furnace and heated to 350°C.
A 2,6-dimethylnaphthalene solution (10% by weight) diluted in benzene and hydrogen were introduced into the solution under normal pressure at flow rates of 3.12 ml/hr and 1/hr (NTP), respectively, to cause an isomerization reaction. Gas flowing out of the reactor was collected in a cold trap. The reaction product liquid collected 1 hour after the start of the reaction was analyzed by gas chromatography. The results obtained are shown in Table-1. Note that after the reaction, no carbon precipitated on the zeolite was observed. Example 2 Silica gel (manufactured by Fuji Davison Chemical Co., Ltd.; Special Silicagel) was placed in a Pyrex glass beaker.
Grade 923) 22.9g and 2.36g of tetrapropylammonium hydroxy ((CH ₃ CH ₂ CH ₂ ) ₄ NOH)
120 ml of a normal aqueous solution was charged and heated to 80°C. Add to this sodium aluminate (content 90% by weight)
A solution of 2.384 g dissolved in 63 ml of water was added. The beaker was placed in a pressure vessel with an internal volume of 1, the pressure vessel was sealed, and then heated to 150°C for 6 days. After filtering the product and washing with demineralized water in step 1,
It was dried at 130°C for 2 days. The obtained product had a silica/alumina ratio of 19, and the diffraction pattern by powder X-ray diffraction was similar to that described in Example 1 of Japanese Patent Publication No. 10064/1983, and the entrance of the main cavity was oxygen 10.
It was confirmed that it was ZSM-5, a zeolite consisting of member rings. This zeolite was converted into an acid form in the same manner as in Example 1, and dimethylnaphthalene was isomerized. The results are shown in Table-1. Example 3 In a Pyrex glass beaker, 108 g of water glass (JIS No. 3 product) and octamethylene diamine were added.
21.04g, aluminum sulfate (Al ₂ (SO ₄ ) ₃ .
3.723 g of 18HH ₂ O) and 292.32 g of water were placed in a pressure vessel with an internal volume of 1. The pressure vessel was then sealed and heated to 160°C for 3 days. 1 product
After washing with salt-rich water, it was dried at 130°C for 2 days. The resulting product had a silica/alumina ratio of 37;
The diffraction pattern obtained by powder X-ray diffraction is
The pattern was almost the same as that described in Example 1 of Publication No. 23280, and the entrance of the main cavity was confirmed to be ZSM-11, a zeolite consisting of a 10-membered oxygen ring. This zeolite was converted into an acid form in the same manner as in Example 1, and dimethylnaphthalene was isomerized. The results are shown in Table-1. In addition, after the reaction was completed, almost no carbon was observed deposited on the zeolite. Example 4 218 g of colloidal silica (silica content: 20% by weight), 137.5 g of water, and 31.8 g of diglycolamine were placed in a Pyrex glass beaker and stirred. To this, add 1.89 g of sodium aluminate (content 90% by weight) and sodium hydroxide to 50 g of water.
A solution containing 6.82 g was added and stirred for 30 minutes. The thus obtained gel-like mixture with a silica/alumina ratio of 70 was placed in a beaker with an internal volume of 1
The mixture was placed in a pressure vessel, the pressure vessel was sealed, and the mixture was heated to 160°C for 3 days. The product was washed with 1 portion of demineralized water and then dried at 130° C. for 2 days. The resulting product had a silica/alumina ratio of 40;
The diffraction pattern obtained by X-ray powder diffraction was published in Japanese Patent Application Laid-open No. 1983-
It was confirmed that it was the same as that described in Example 1 of Publication No. 92114, and that the entrance of the main cavity was a pentasil type zeolite consisting of a 10-membered oxygen ring. This zeolite was converted into an acid form in the same manner as in Example 1, and dimethylnaphthalene was isomerized. The results are shown in Table-1. Comparative Example 1 Dimethylnaphthalene was isomerized in the same manner as in Example 1, except that synthetic mordenite (trade name: Zeolon 100H, manufactured by Norton Co., Ltd.) was used. The results are shown in Table-1. Incidentally, after the reaction was completed, a large amount of carbon was observed to be deposited on the zeolite. Comparative Example 2 The synthesized mordenite of Comparative Example 1 was placed in a 6N aqueous hydrochloric acid solution and heated under reflux for 6 hours. After cooling,
After washing with water until no chlorine ions were detected, it was dried at 130°C. After molding using a powder tablet molding machine, it was crushed and sized into 24 to 42 meshes. This was heated and calcined in air at 500°C for 3 hours to obtain a catalyst. Using this catalyst, dimethylnaphthalene was isomerized in the same manner as in Example 1. Table 1 shows the results.
Shown below. Incidentally, after the reaction was completed, a large amount of carbon was observed to be deposited on the zeolite.

[Table] As is clear from Table 1, the zeolite whose main cavity has a 10-membered oxygen ring at the entrance has superior isomerization ability beyond the set of dimethylnaphthalene isomers rather than demethylation activity. Also, among this type of zeolite, those with an acid content of more than 0.45 mmol/g have a high yield of isomers (=conversion rate x selectivity) that exceeds the set, and are particularly preferred catalysts. I understand. Examples 5 and 6 1.5 ml of acid type zeolite prepared in Example 1,
It was packed into a Pyrex glass reactor with an inner diameter of 10 mm. This was placed in an electric furnace and heated to 350°C. A dimethylnaphthalene solution (5% by weight) dissolved in benzene and hydrogen were added to this under normal pressure.
Introduced at a flow rate of 3.12 ml/hr, 1/hr (NTP),
An isomerization reaction was carried out. Gas flowing out of the reactor was collected in a cold trap. From the start of the reaction
The reaction product liquid collected for 30 minutes was analyzed by gas chromatography. The results are shown in Table-2.

[Table] Examples 7 to 8 After molding the dried zeolite after ammonium ion exchange prepared in Example 1 with a tablet molding machine,
It was crushed and sized into 10 to 14 pieces. 500 of this
It was heated and calcined in air at ℃ for 3 hours to obtain acid type zeolite. This zeolite was packed into a Pyrex glass reactor with an inner diameter of 25 mm. This was charged into an electric furnace and heated to 350℃, and molten 2,6-dimethylnaphthalene and hydrogen were added to it under normal pressure.
Introduced at a flow rate of 0.848g/hr, 1.8/hr (NTP),
An isomerization reaction was carried out. Gas flowing out of the reactor was collected in a cold trap. The reaction product liquid collected 1 hour after the start of the reaction was analyzed by gas chromatography. The results are shown in Table-3.

【table】 [Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a measuring device for the gaseous base adsorption method on zeolite. 1... Helium cylinder, 2... Standard ammonia gas cylinder, 3... Neild valve, 4... Pressure reducing valve, 5...
Rotameter, 6... Heating furnace, 7... Sample, 8... Balance weight, 9... Control mechanism, 10... Recorder.

Claims (1)

[Scope of Claims] 1. A method for catalytic isomerization of dimethylnaphthalene, characterized in that a zeolite whose main cavity entrance has a 10-membered oxygen ring is used as a catalyst. 2. The method according to claim 1, wherein the zeolite is an acid type aluminosilicate. 3 Zeolite has a silica/alumina molar ratio of 12
3. The method according to claim 1 or 2, wherein the method is of a pentasil type. 4. The catalyst according to any one of claims 1 to 3, characterized in that the catalyst is a zeolite having an acid content of 0.1 mmol/g or more at 300°C determined by a gaseous base adsorption method. Method. 5. The catalyst according to any one of claims 1 to 3, characterized in that the catalyst is a zeolite having an acid content of 0.45 mmol/g or more at 300°C determined by a gaseous base adsorption method. Method. 6. A patent claim characterized in that dimethylnaphthalene is isomerized in which the total amount of 1,5-, 1,6- and 2,6-dimethylnaphthalene has not reached a thermodynamic equilibrium composition under isomerization conditions. range 1
The method according to any one of Items 1 to 5. 7 The total amount of 1,5-, 1,6- and 2,6-dimethylnaphthalene has not reached the thermodynamic equilibrium composition under isomerization conditions, and 1,7-, 1,
Claims 1 to 5 are characterized in that dimethylnaphthalene is isomerized in which the total amount of 8- and 2,7-dimethylnaphthalene is greater than the thermodynamic equilibrium composition under isomerization conditions. Any method described.