JP2003096033A - Isomerization method of xylidine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide useful zeolite as a xylidine-isomerizing catalyst which can efficiently isomerize xylidine with less formation of unfavorable impurities by a side reaction. SOLUTION: Xylidine is contacted with a catalyst containing zeolite whose main cavity entrance comprises a 14-membered oxygen ring. The zeolite whose main cavity entrance comprises a 14-membered oxygen ring is preferably a CFI-type zeolite, and the zeolite comprising a 14-membered oxygen ring (preferably CFI-type zeolite) is preferably an acid-type zeolite. Xylidine can efficiently be isomerized with less formation of the unfavorable impurities by the side reaction by using the catalyst containing such zeolite.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for isomerizing xylidine. In particular, each of the six xylidine isomers may be individually isolated from one or more of the undesired isomers, or any mixture of all six of the xylidine isomers, especially those that are economically unsatisfactory to the desired isomer. It relates to a method of manufacturing from a mixture containing in concentration.

[0002]

2. Description of the Related Art Generally, xylidine is industrially produced by nitrating and reducing xylene. This nitration of xylene is a reaction having a strong orientation, and the type of isomer obtained is governed by the type of xylene isomer used as a raw material and this orientation. That is, by nitration or reduction of ortho-xylene, 2,3-xylidine and 3,4-xylidine are obtained.
4-Xylidine and 2,6-Xylidine are obtained, and 2,5-Xylidine is obtained from para-xylene. However, 3,5-xylidine cannot be obtained by nitration or reduction of xylene. Conventionally, 3,5-xylidine is obtained by reaction of 3,5-xylenol with ammonia at high temperature and high pressure. Thus, it is not possible to obtain all of the isomers by nitration and reduction of xylene which is an industrial method for producing xylidine. In addition, the demand ratio of each isomer of xylidine is often different from the production ratio of each isomer obtained by nitration and reduction. Therefore,
If isomers with low demand can be isomerized and converted into isomers with high demand, it will lead to effective utilization of xylidine. Thus, the isomerization method of xylidine has important technical significance.

In order to utilize each isomer of xylidine as its simple substance, it is necessary to separate it. It is economically extremely important to increase the concentration of the target isomer again by the isomerization reaction of the remaining xylidine isomer obtained by separating and removing the target xylidine isomer. Then, the target xylidine isomer is separated and removed again, and this cycle is repeated.

As a method for carrying out such an isomerization reaction, US Pat. No. 4,593,124 discloses a method using HZSM-5 which is a pentasil type zeolite. 3-,
Unable to produce 2,6- and 3,5-xylidine and U.S. Pat. No. 4,795,833 discloses a process with omega, beta and L zeolites, but demethylation occurs, Because of problems such as low yield of xylidine, none of them is preferable as an industrial isomerization method.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention As a result of intensive investigations, the present inventors have solved the drawbacks of the conventional method and established an industrially superior method for efficiently isomerizing xylidine by a simple process. The inventors have found that a zeolite having a 14-membered oxygen ring at the entrance of the main cavity such as CFI-type zeolite exhibits excellent catalytic performance in this reaction, and arrived at the present invention.

[0006]

That is, the present invention is a method for isomerizing xylidine, which comprises contacting xylidine with a catalyst containing a zeolite having a 14-membered oxygen ring at the inlet of the main cavity. Good The details will be described below.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a method for isomerizing xylidine using a catalyst containing a zeolite having a 14-membered oxygen ring at the inlet of a main cavity. As the zeolite in which the inlet of the main cavity is composed of a 14-membered oxygen ring, a CFI-type zeolite is preferable, and a catalyst composition containing the CFI-type zeolite is preferably made into an acid type before being used for a xylidine isomerization reaction. The details will be described below.

In the present invention, a zeolite having a 14-membered oxygen ring at the inlet of the main cavity is used, but a CFI-type zeolite is preferred. The CFI-type zeolite was first synthesized by Yoshikawa and Davis, and had a crystal structure by Wagner et al. It is a zeolite having a crystal structure similar to that of the elucidated CIT-5 zeolite. International Zeolite Association Structural Section
(Structure Commission) gives the zeolite of which the structure is determined to the code of three letters of the alphabet, and the zeolites having the same topology are collectively referred to by these three letters.
The code CFI is given to the structure of CIT-5. Therefore, it is common to call a zeolite having a structure similar to CIT-5 a CFI-type zeolite.

The simplest method for investigating whether zeolite has a CFI type structure is powder X-ray diffraction. When powder X-ray diffraction is performed, it can be determined whether or not there is a peak at the position shown in Table 1 or Table 2. Table 1 shows
The peak positions generally found in the powder X-ray diffraction pattern of uncalcined CFI-type zeolite are shown. Table 2 shows the peak positions generally found in the powder X-ray diffraction pattern of the CFI-type zeolite after firing to remove the organic substances in the pores.

[0010]

[0011] Here, the zeolite is a silicate-based crystalline microporous substance, and is a crystalline aluminosilicate, a crystalline metallosilicate, or a crystalline metalloaluminosilicate having a CIT-5 (CFI) structure. The term "metallosilicate" or "metalloaluminosilicate" as used herein refers to aluminosilicate in which a part or all of aluminum is substituted with a metal other than aluminum such as gallium, iron, titanium, boron, cobalt, and chromium.
Here, elements other than silicon and oxygen that constitute the structural skeleton, such as aluminum, gallium, iron, titanium, boron, cobalt, and chromium, are defined as hetero elements. The type of heteroatom is not particularly limited, but is preferably aluminum, gallium, iron, titanium, boron, cobalt, or chromium, and particularly preferably aluminum,
Of gallium and boron, aluminum is particularly preferable because it has the strongest acid strength as a catalyst.

The method of synthesizing CFI-type zeolite is known in the following documents. (Reference 1) WO99 / 08961, (Reference 2) Chemical Communication 2179 pages (1997), (Reference 3) Journal of Physical Chemistry Bee 102 volumes 7139 pages (1998), (Reference 4) Journal of Catalysis 182 volumes 463 pages. (1999), (Reference 5) Catalyst 41, page 380 (1999) Also, the molar ratio of silicon / heteroatoms constituting such zeolite is preferably 5 to 45. More preferably, it is 7 to 40. If the silicon / heteroatom molar ratio is less than 5 or more than 45, the catalytic activity decreases. The silicon / heteroatom molar ratio is determined by atomic absorption spectrometry,
X-ray fluorescence method, inductively coupled high frequency plasma emission spectroscopy (IC
P method) and the like. Further, this molar ratio is not the molar ratio in the raw material used for the synthesis, but the atomic composition of the actually produced CFI-type zeolite.

The method using CFI-type zeolite as a catalyst is
Known methods can be used. Here, the most general method will be described. As the catalyst, zeolite is usually molded and used. The molded body may be one obtained by solidifying only zeolite, or one formed by granulating with a binder such as alumina or clay. The granulation can be performed, for example, by kneading with a binder such as alumina sol, extruding with an extruder, and rolling with a marumerizer.

The catalyst containing CFI type zeolite removes the water of crystallization in the zeolite and the organic substances used in the synthesis in advance before it is usually used. Usually, most of the water of crystallization and the organic substances used during the synthesis can be removed by heating at 200 to 650 ° C.

It is preferable that the CFI-type zeolite contained in the molded body of the present invention is in the acid form. In the case of the acid form or the form of hydrogen ion precursor ammonium ion or organic cation before molding, it is not always necessary to perform a new treatment to form the acid form, but alkali metal ions, alkaline earth metal ions, etc. When it contains, an ion exchange treatment is carried out to convert it into an acid form. Ion exchange treatment, after removing the organic matter in the zeolite pores, when directly acidified with an aqueous solution of an inorganic acid, an organic acid or the like, and ammonium ion is introduced by ion exchange with an aqueous solution of ammonium chloride, ammonium nitrate, Then, there is a method of converting into hydrogen ions by firing to form an acid form.

The catalyst may contain a metal in a portion other than zeolite, for example, in a binder portion. For example, when used as an acid catalyst, a noble metal is supported on the catalyst to prolong the catalyst life. It is preferable to react in the presence of hydrogen. The reason is not clear, but the supply of protons to the catalyst is facilitated and coking is suppressed. The precious metal to be carried is not particularly limited,
Rhenium is the most preferred metal. It is considered that the reason is that the hydrocracking activity is low.

When CFI-type zeolite is used as a catalyst, the molar ratio of silicon / heteroatoms cannot be determined by elemental analysis depending on the binder, but the molar ratio of silicon / heteroatoms can be determined by ²⁹ Si-NMR.

The xylidine isomerization reaction of the present invention can be carried out according to various conventionally known isomerization operations, and good results can be obtained in both gas phase reaction and liquid phase reaction. As the isomerization reaction method, any of fixed bed, moving bed and fluidized bed methods may be used, but the fixed bed flow reaction method is particularly preferable from the viewpoint of easy operation. Reaction temperature is 200 to 5
The temperature is 50 ° C, preferably 250 to 500 ° C. The reaction pressure is not particularly limited, but in the case of liquid phase reaction,
It goes without saying that the reaction pressure must be set to keep the reaction system in the liquid state. Also, during the isomerization reaction,
Coexistence of hydrogen, an aromatic compound, or polymethylaniline different from xylidine is often effective in reducing side reactions and extending catalyst life. Weight space velocity (W
HSV) is 0.05 to 30 hr-1, preferably 0.1.
To 20 Hr-1.

The xylidine isomers thus obtained by isomerization are separated by adsorption separation and / or distillation.

These isomers are used as intermediates for medicines, agricultural chemicals, dyes and pigments.

[0021]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 (Synthesis of CIT-5) Ludox HS-30 (manufactured by DuPont) as a silica source, aluminum nitrate nonahydrate (Nacalai Tesque) as an aluminum source, and anhydrous lithium hydroxide as a lithium source. (Kishida Chemistry) and methylsparteinium hydroxide (hereinafter abbreviated as ROH) as an organic cation source were used to prepare a mixture having the following composition.

SiO ₂ : 0.1LiOH: 0.4ROH: 0.02Al (NO ₃ ) ₃ : 50H ₂ O
(Molar ratio).

Specifically, 171.3 g of distilled water was added to 1.
After dissolving 65g of anhydrous lithium hydroxide, ROH
124.4 g of a ROH aqueous solution having a concentration of 2.219 mmol / g was added and stirred for 10 minutes. Then, with stirring, a solution prepared by dissolving 5.19 g of aluminum nitrate nonahydrate in 300 g of distilled water was added and stirred for 30 minutes. Furthermore, Ludox HS-3
138.3 g of 0 was added and stirred for 3 hours. The reaction mixture was placed in a 1000 ml autoclave and sealed, and then reacted at 175 ° C. for 14 days while stirring at 300 rpm.

After completion of the reaction, washing with distilled water 5 times and filtration were repeated, and the product was dried at about 120 ° C. overnight. The product obtained was CIT-5 having the X-ray diffraction pattern shown in Table 1.
The condition of X-ray diffraction is that the X-ray source is Cu / 40 kV / 30 m.
At A, the scan speed was 3 degrees / minute. The silica / alumina molar ratio of this zeolite was 86 as a result of composition analysis by fluorescent X-ray.

Reference Example 2 (Synthesis of Pentacyl-Type Zeolite) Solid caustic soda (NaOH content 96.0 wt%, H ₂
O content 4.0 wt%, Katayama Chemical Co., Ltd. 7.3 g, tartaric acid powder (tartaric acid content 99.7 wt%, H ₂ O content 0.3 w
t%, Katayama Chemical Co., Ltd.) 10.2 grams was dissolved in 583.8 grams water. Sodium aluminate solution (Al ₂
O ₃ content 18.5 wt%, NaOH content 26.1 wt
%, H ₂ O 55.4 wt%, Sumitomo Chemical Co., Ltd. 35.4 g to make a uniform solution. Hydrous silicic acid powder (SiO2 content 91.6 wt%, Al ₂ O ₃ content 0.3
31.5% by weight, NaOH content 0.27% by weight, Nipseal VN-3, Nippon Silica) 111.5 g were gradually added with stirring to prepare a uniform aqueous slurry reaction mixture. The composition ratio (molar ratio) of this reaction mixture was as follows.

SiO ₂ / Al ₂ O ₃ 25 H ₂ O / SiO ₂ 20 OH ⁻ / SiO ₂ 0.164 A / Al ₂ O ₃ 1.0 A: The tartrate reaction mixture was placed in a 1000 ml autoclave and sealed. Then, the mixture was reacted at 160 ° C. for 72 hours while stirring at 250 rpm.

After completion of the reaction, washing with distilled water 5 times and filtration were repeated, and the product was dried at about 120 ° C. overnight. The product obtained was a pentasil-type zeolite having the X-ray diffraction pattern shown in Table 3. The silica / alumina molar ratio of this zeolite was 21.9 as a result of compositional analysis.

[0029]

[Table 3]

Reference Example 3 (Synthesis of Beta-type Zeolite) Sodium aluminate solution (Al ₂ O ₃ content 19.5 wt%,
NaOH content 20.2 wt%, H ₂ O 60.3 wt%,
Sumitomo Chemical Co., Ltd. 33.6 g, tetraethylammonium hydroxide (hereinafter referred to as "TEAOH") (T
192.4 g of EAOH content 20 wt%, H ₂ O content 80 wt%, Sanyo Kasei) was added to 508 g of distilled water,
A homogeneous solution was obtained. Hydrous silicic acid (SiO2
Content 91.6 wt%, Al ₂ O ₃ content 0.33 wt%, N
111.5 g of aOH content of 0.27 wt%, Nipseal VN-3, Nippon Silica) was gradually added with stirring to prepare a uniform slurry-like aqueous reaction mixture. The composition ratio (molar ratio) of this reaction mixture was as follows.

SiO ₂ / Al ₂ O ₃ 25 OH ⁻ / SiO ₂ 0.30 Q / (Q + Na) 0.544 (where Q is TEAOH) H ₂ O / OH ^- 80 The reaction mixture was placed in a 1000 ml autoclave. The mixture was placed and sealed, and then reacted at 160 ° C. for 11 days while stirring at 250 rpm.

After completion of the reaction, washing with distilled water 5 times and filtration were repeated, and the product was dried at about 120 ° C. overnight. The product obtained was a beta-type zeolite having the X-ray diffraction pattern shown in Table 4. The silica / alumina molar ratio of this zeolite was 21.2.

[0033]

[Table 4]

Reference Example 4 (Preparation of Catalyst Composition A) 15 grams of CIT-5 powder obtained in Reference Example 1 (absolute dry basis)
Alumina sol as a binder (Al ₂ O ₃ content 10w
t%, colloidal alumina 200, Nissan Chemical Co., Ltd. 12 grams, alumina gel (Al ₂ O ₃ content 70 wt%, Catalog)
1.5 g of loidAP (C-10), catalysis) was added and kneaded. During kneading, an appropriate amount of distilled water was added while checking the kneading state to form a paste-like mixture. This was made into a noodle-shaped molded body through a screen having 0.8 mmφ holes. After drying at 120 ℃ overnight, 540 ℃
It was baked for 2 hours.

12.5 g of the fired compact was taken, and 1
80 to 8 with 0 wt% ammonium chloride aqueous solution
Ion exchange treatment was performed at 5 ° C. for 1 hour. After repeating this ion exchange treatment 5 times, it was washed 5 times with distilled water. 120
It was dried overnight at 0 ° C. to obtain an ammonium ion exchange type molded body. Then, it was calcined at 550 ° C. for 2 hours to convert ammonium ions into hydrogen ions to obtain a catalyst composition A containing acid type CIT-5.

Reference Example 5 (Preparation of Comparative Catalyst Composition B) The pentasil-type zeolite powder obtained in Reference Example 2 was prepared in the same manner as the catalyst composition A of Example 2, and the catalyst composition B was prepared.
Got

Reference Example 6 (Preparation of Comparative Catalyst Composition C) The beta-type zeolite powder obtained in Reference Example 3 was used in Example 2
A catalyst composition C was obtained in the same manner as in the catalyst composition A.

Example 1 (Xylidine isomerization reaction) Table 5 shows the results of the xylidine isomerization reaction test conducted on catalysts A to C.

[0039]

[Table 5]

From Table 5, it can be seen that by using the catalyst composition A containing the acid type CIT-5, all xylidine isomers can be produced and demethylation is suppressed and the xylidine yield is high. .

[0041]

EFFECT OF THE INVENTION By using a catalyst composition containing CFI type zeolite, xylidine can be efficiently isomerized.

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Claims (3)

[Claims] 1. A process for isomerizing xylidine, which comprises contacting xylidine with a catalyst containing a zeolite having a 14-membered oxygen ring at the inlet of the main cavity. 2. The method for isomerizing xylidine according to claim 1, wherein the zeolite having a 14-membered oxygen ring at the inlet of the main cavity is a CFI type zeolite. 3. The method for isomerizing xylidine according to claim 2, wherein the CFI-type zeolite is an acid type.