JP2662649B2 - Dehydration reaction method using ZSM-5 - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a dehydration reaction method which is important as a method for producing intermediates of various chemical raw materials.

[0002]

2. Description of the Related Art Conventionally, as a catalyst for a dehydration reaction of an organic compound in a liquid phase, inorganic acids such as water-soluble mineral acids and heteropoly acids have been used. However, these inorganic acids are
There are problems that the equipment is severely corroded and expensive materials must be used, and that the operation of separating the product from the aqueous acid solution is complicated. In order to solve these problems, a method using an ion-exchange resin has been proposed, but the ion-exchange resin has a problem in heat resistance and mechanical strength, and there is a problem that use conditions are extremely limited. .

On the other hand, in recent years, there has been reported an example of a dehydration reaction using formalin or alcohol as a raw material in a liquid phase using zeolite which is an inorganic solid acid having excellent heat resistance and mechanical strength as a solid acid as a catalyst. . For example, JP-A-58-
No. 162546 describes a method for synthesizing an acetal by dehydration condensation of formalin and alcohol using a crystalline aluminosilicate having a silica / alumina molar ratio of 10 or more. Further, Japanese Patent Application Laid-Open No. 58-203985 describes a method for synthesizing trioxane from formalin using a crystalline aluminosilicate having a silica / alumina molar ratio of 10 or more. This reaction is a trimerization reaction as shown below as a reaction formula,

Embedded image Although water is not involved, formaldehyde in the formalin aqueous solution actually exists as a polymethylene glycol type hydrate as described below, and this reaction can also be regarded as a dehydration reaction.

Embedded image

[0004] These reports include examples of various zeolites. Among them, zeolite Z synthesized in the presence of an organic cation such as tetrapropylammonium is mentioned.
SM-5 has been shown to exhibit excellent catalytic performance.
On the other hand, as a method for synthesizing zeolite ZSM-5, quaternary ammonium salts such as tetrapropylammonium, organic amines such as hexamethylenediamine, urea compounds such as 1,3-dimethylurea, and other alcohols and sulfur-containing compounds are often used. There has been proposed a method using an organic compound of the following type. In the method of synthesizing ZSM-5 using these organic compounds, the produced zeolites contain a large amount of organic compounds, and therefore must be removed by some method. Usually, as a method for removing these organic compounds, 4
A method of firing and removing in air at a high temperature of 00 ° C. or higher is used. As another method, a method of oxidizing and removing in a liquid phase using an oxidizing agent such as hydrogen peroxide has also been proposed (Japanese Patent Application Laid-Open No. H10-163,837). 57-135718).

On the other hand, in recent years, a method for synthesizing zeolite ZSM-5 from inorganic substances alone without using these organic substances has been proposed (JP-B-56-498515).
No., JP-A-56-37215, and JP-B-61-5924.
No. 6, JP-A-60-77123). Although these synthetic methods have an advantage in the production method that organic substances do not need to be removed, there are few examples of using them in the reaction as a catalyst, and a slight catalytic reforming in the gas phase disclosed in JP-A-56-37215. There is only an example of a reaction, and from this result, it is considered that there is no difference from ZSM-5 synthesized using ordinary organic substances. ZS synthesized without using these organic substances
There is no example of a dehydration reaction in the liquid phase using M-5.

[0006]

The present inventors have also conducted additional tests on the invention using zeolite as a catalyst, and confirmed that ZSM-5 shows excellent activity and selectivity among various zeolites. Was done. However,
It has been found that these activities and selectivities are still insufficient for industrial implementation. Therefore, when the dehydration reaction is carried out in a liquid phase of 200 ° C. or lower, a catalyst that gives high productivity is required.

[0007]

Means for Solving the Problems The present inventors, under the liquid phase,
As a result of intensive studies to find a catalyst having high activity and high selectivity when performing a dehydration reaction using at least one selected from formalin, carboxylic acid and alcohol at 200 ° C or lower, The zeolite ZSM-5 synthesized hydrothermally from only inorganic substances is significantly higher in activity than ZSM-5 synthesized using conventional organic substances, and
The inventors have found that they exhibit high selectivity, and have completed the present invention.

That is, the present invention provides an acid type zeolite Z
In performing a dehydration reaction using at least one selected from formalin, carboxylic acid, and alcohol in a liquid phase at a temperature of 200 ° C. or lower using an SM-5 catalyst, the zeolite ZSM-5 catalyst contains only inorganic substances. A zeolite ZSM-5, which is hydrothermally synthesized from ZSM-5.

Until now, zeolite ZSM has been used only with inorganic substances.
It has been known that the method of synthesizing -5 is excellent in economical efficiency in the zeolite synthesis process, but it is considered that the catalyst performance is the same as that of ZSM-5 synthesized using an organic substance. Was. In that respect, the dominant difference in the present reaction system is surprising which was not known before. why,
Although it is not clear whether there is a difference depending on the method of synthesizing ZSM-5, the following reasons can be considered.

ZS synthesized by a method using ordinary organic substances
M-5 is used to remove organic substances as described above.
Generally, it must be fired in air at a high temperature of 400 ° C. or higher. During this calcination, aluminum that forms the zeolite crystal lattice is desorbed from the lattice due to the water generated by the combustion of the organic matter. The acid sites, which are the active sites of the zeolite, are paired with the aluminum atoms of the lattice, and this dealumination phenomenon means that the acid sites of the zeolite are reduced. It is generally said that the dealumination phenomenon occurs from strong acid sites. Furthermore, aluminum desorbed from the lattice by dealumination is not completely removed from the crystal even by subsequent ion exchange treatment, etc.
Some may remain in the pores of the zeolite. As described above, calcination at high temperature involves the desorption of aluminum from the zeolite lattice, which causes a decrease in acid sites and inhibition of molecular diffusion by aluminum atoms remaining in the pores. It is thought that it decreases.

On the other hand, from the viewpoint of the reaction, in the gas phase reaction at a high temperature, the reaction rate is extremely high, so that the influence of the acid strength and the acid amount is not so large, and the diffusion of the molecules is also very fast. Therefore, while diffusion inhibition has little effect, it is considered that both influences are very large in a low-temperature liquid phase reaction. Further, as a method for removing organic substances from zeolite, ZSM- produced by the above-described liquid phase oxidation removal method using an oxidizing agent such as hydrogen peroxide is used.
Also in comparison with No. 5, ZSM-5 synthesized from only the inorganic substance used in the present invention shows a remarkable difference in activity and selectivity.

Regarding the cause, when the organic matter in the zeolite is removed by the liquid phase oxidation removal method, the vicinity of the surface of the crystal is easily removed, but the organic matter in the inside cannot be easily removed, and is substantially completely removed. It is difficult to remove. Therefore, it is considered that the activity of this reaction decreases due to a decrease in the amount of acid or diffusion inhibition by the remaining organic matter. The difference in selectivity besides the activity is considered to be due to the fact that the selectivity of zeolite is caused by a difference in diffusion rate.

As described above, Z synthesized only with inorganic substances
It is considered that SM-5 is excellent because it does not need to remove organic substances and thus does not undergo a change in the structure or acid point of zeolite generated at that time. As a method of hydrothermally synthesizing zeolite ZSM-5 used in the present invention from only inorganic substances, usually, a silica source, an alumina source, an alkali metal source, water, and an inorganic acid such as sulfuric acid or nitric acid used for zeolite synthesis are used. A method of preparing the composition to generate -5 and performing hydrothermal synthesis under a self-generated pressure in a temperature range of 120 to 200 ° C. At this time, a seed crystal or a seed slurry may be allowed to coexist so that impurities such as mordenite do not mix into the generated ZSM-5.

The zeolite ZSM-5 thus obtained is obtained.
Usually the cation is an alkali metal. Since ZSM-5 used as a catalyst in the present invention is in an acid form, it is necessary to convert the ZSM-5 thus obtained into an acid form by ion exchange. ZSM used in the present invention
The cation of -5 is not particularly limited as long as it can express acidity. For example, proton, alkaline earth metal, titanium group,
Examples include iron group, platinum group, and rare earth metals. Among them, proton is preferred. As a method for introducing these cations into ZSM-5, an ordinary ion exchange method in an aqueous solution of an inorganic acid or a metal salt can be used.

In the present invention, formalin, carboxylic acid,
Examples of the dehydration reaction using at least one selected from alcohols as a raw material include, for example, a synthesis reaction of acetal by dehydration condensation of formalin and alcohol, a synthesis reaction of trioxane from formalin, and a dehydration condensation of formalin and aromatic compound. Reaction, esterification reaction of carboxylic acid with alcohol and the like. Among these, an acetal synthesis reaction and a trioxane synthesis reaction are preferable. Further, in the synthesis reaction of acetal, a synthesis reaction of methylal from formalin and methanol is preferable.

The reaction temperature in the present invention is 200 ° C. or less. When the reaction temperature exceeds 200 ° C., dealumination from the zeolite lattice is likely to occur due to coexisting water, and the activity is undesirably reduced. Therefore, the reaction temperature is usually 30 to 200 ° C, preferably 50 to 200 ° C.
The temperature is 180 ° C, more preferably 80 to 150 ° C. The pressure in the present invention is not particularly limited as long as the pressure keeps the reaction system in a liquid phase, but the pressure is usually from normal pressure to 1 to 50 atm. The reaction system in the present invention may be any of a batch system, a flow system, a reactive distillation system, and the like.

[0017]

Embodiments of the present invention will be described below in detail. (Example 1) (I) Synthesis of ZSM-5 from inorganic substance only Qbrand silicate aqueous solution (Na ₂ O 8.9% by weight, SiO ₂ 2
8.9 wt%, H ₂ O 62.2 wt%) NaOH in 5.3 kg 26 g and H ₂ O 2
kg was added to obtain a homogeneous solution. This solution was charged into a stainless steel autoclave (volume: 50 liters), and while stirring, 0.4 kg of Al ₂ (SO ₄ ) ₃ · 18H ₂ O and 0.3 k of concentrated sulfuric acid were added to 15 kg of H ₂ O.
The aqueous solution in which g was dissolved was pumped in at room temperature over 1 hour. Thereafter, the temperature was increased to 180 ° C., and 250 rpm
Crystallization was performed for 10 hours under stirring conditions of m. Partial filtration,
After drying, as a result of X-ray diffraction analysis, ZS having a crystallinity of 60% was obtained.
It was found to be M-5.

Further, an aqueous solution of Qbrand silicate 5.7 k
g of NaOH and 2.2 kg of H ₂ O, and 10.5 kg of the 60% crystallinity slurry obtained above were charged into a stainless steel autoclave, and Al ₂ (SO ₄ ) ₃ · 18H was added to 16 kg of H 2 O. ₂ O
An aqueous solution of 0.42 kg and 0.3 kg of concentrated sulfuric acid dissolved in 250 rpm
While stirring at room temperature for 1 hour.
Thereafter, the temperature is increased to 150 ° C., and 3 rpm at 250 rpm.
Crystallization was performed for 0 hours. Take out the obtained slurry,
After filtration and washing with a centrifugal dehydrator, the crystals were washed with 1N nitric acid 20
Ion exchange was performed in a liter for 4 hours at room temperature. This slurry was filtered and washed with a centrifugal dehydrator, and then dried at 120 ° C. for 10 hours. X-ray diffraction analysis of the obtained crystal showed that the crystal was ZSM-5 having a crystallinity of 100%.
The SiO ₂ / Al ₂ O ₃ molar ratio determined by fluorescent X-ray analysis was 2
8, and the particles measured by a scanning electron microscope were 0.1 μm.
m or less primary particles aggregated to form columnar secondary particles of about 0.5 × 0.5 × 1 μm. Furthermore, this H-ZSM
-5 acid content was determined by liquid phase ion exchange-alkaline titration (Fift
h International Conference on Zeolite, 1980, P335), it was 1.05 mmol / g.

(II) Methylal synthesis reaction The H-ZSM-5 obtained in (I) is compression molded
Granules of up to 24 mesh were used as a catalyst for the methylal synthesis reaction. The reaction conditions are as follows. Reaction temperature: 60 ° C. Contact time: 60 seconds Reaction type: fixed bed liquid phase flow reaction Reactor: stainless steel reaction tube (inner diameter 10 mm)

The composition of the effluent for 2 to 3 hours after the start of the reaction was as follows. The conversion of CH ₂ O determined from this composition was 70%.

(Example 2) H-ZS obtained in Example 1
Using M-5 as a catalyst, a synthesis reaction of trioxane was performed under the following conditions. Catalyst: 1.0 g Initial charge: 100 g Reaction temperature: 100 ° C Reaction type: Reactive distillation method (simple distillation method)

After starting the reaction, the amount of distillate up to 1 hour is 20 g
The composition was as follows. CH ₂ O 40.4 wt% H ₂ O 41.0 〃 CH ₃ OH 3.6 〃 methyl ester 0.27 〃 methylal 2.1 〃 carboxylic acid 0.01 〃 trioxane 12.6 〃

(Example 3) H-ZS obtained in Example 1
Using M-5 as a catalyst, an esterification reaction of adipic acid with methanol was performed under the following conditions. Reaction raw material: adipic acid 83g methanol 65g catalyst: 20g Reaction temperature: 80 ° C Reactor: glass autoclave Stirring speed: 400rpm

As a result, the liquid composition one hour after the start of the reaction was as follows. Adipic acid 1.0% by weight of adipic acid monomethyl 15.3 〃 adipate methyl 55.3 〃 methanol 16.3 〃 H ₂ O 11.5 〃

(Example 4) H-ZS obtained in Example 1
Using M-5 as a catalyst, a synthesis reaction of bisphenol F from phenol and formalin was performed under the following conditions. Raw material for reaction: 100 g of phenol 50 g of 30% formalin Catalyst: 20 g Reaction temperature: 80 ° C. Reactor: autoclave made of glass As a result, one hour after the start of the reaction, bisphenol F
The yield based on CH ₂ O was 30%.

Comparative Example 1 (I) Synthesis of ZSM-5 Using Organic Substance To 150 g of an aqueous Qbrand silicate solution, 180 g of a 10% aqueous solution of tetrapropylammonium hydroxide was added, and further, aluminum nitrate [Al (NO ₃ ) _2. 9H ₂ O] 15 g and water 40 g
Stirred for 10 minutes. Thereafter, the solution was adjusted to pH 10 to 10.5 by dropwise addition of concentrated nitric acid with vigorous stirring to obtain a homogeneous gel. This gel was placed in a 1-liter autoclave equipped with a stirrer, and crystallized with stirring at 180 ° C. for 24 hours.
As a result, the obtained product was filtered and washed, and then washed at 120 ° C. for 1 hour.
It was dried for 0 hour and calcined at 500 ° C. for 5 hours in air to remove organic substances. Thereafter, the product was ion-exchanged in 1N nitric acid at room temperature for 5 hours, filtered, washed, and then washed at 120 ° C.
For 10 hours.

As a result, the obtained product was identified as ZSM-5 by X-ray diffraction analysis. The SiO ₂ / Al ₂ O ₃ molar ratio determined by fluorescent X-ray analysis was 27. According to the scanning electron microscope measurement, the crystal particles were formed by agglomeration of primary particles of 0.1 μm or less to form 0.2 to 0.4 μm. Of spherical secondary particles were formed. Further, the acidity of this H-ZSM-5 determined by liquid phase ion exchange-alkaline titration was 0.60 mmol / g.

(II) Synthesis reaction of methylal Using the H-ZSM-5 obtained in (I) as a catalyst, a synthesis reaction of methylal was carried out under the same conditions as in Example 1. As a result, the composition of the effluent for 2 to 3 hours after the start of the reaction was as follows. CH ₂ O 2.5% by weight CH ₃ OH 44.7 {methylal 6.3} H ₂ O 46.5} The conversion based on CH ₂ O obtained from this composition was 50%.

(Comparative Example 2) H-ZS obtained in Comparative Example 1
Using M-5 as a catalyst, a synthesis reaction of trioxane was performed under the same conditions as in Example 2. As a result, the amount of the effluent up to 1 hour after the start of the reaction was 18 g, and the composition was as follows. CH2O 45.7% by weight H2O 37.1 〃 CH3OH 3.1 methyl oxalate 1.1 〃methylal 1.5 〃carboxylic acid 1.0 〃trioxane 10.6 〃

(Comparative Example 3) (I) Liquid phase oxidation removal of organic substances from zeolite 100 g of unsintered ZSM-5 synthesized in Comparative Example 1 was put into 1 liter of 0.5N nitric acid to form a slurry, and further, 30% 100 cc of aqueous hydrogen peroxide was added dropwise over 1 hour while stirring at 70 ° C. This product was filtered and washed, and ion-exchanged with 1N nitric acid at room temperature for 4 hours.
Dried for 8 hours at ° C.

The result of X-ray diffraction analysis of the obtained product was as follows:
ZSM-5. In addition, it was determined by fluorescent X-ray analysis.
The SiO ₂ / Al ₂ O ₃ molar ratio was 28. From the measurement by the scanning electron microscope, the crystal particles were found to be agglomerated by primary particles of 0.1 μm or less.
It formed spherical secondary particles of 0.2 to 0.4 μm. Further, the acidity of this H-ZSM-5 determined by liquid phase ion exchange-alkaline titration was 0.3 mmol / g.

(II) Synthesis reaction of trioxane Using H-ZSM-5 obtained in (I) as a catalyst,
A synthesis reaction of trioxane was performed under the same conditions as in Example 2. As a result, the amount of effluent in the first hour after the start of the reaction was 17 g.
The composition was as follows. CH ₂ O 45.0% by weight H ₂ O 38.0 〃 CH ₃ OH 3.0 〃 methylate 1.2 〃 methylal 1.5 〃 carboxylic acid 0.9 0.9 trioxane 10.4 〃

[0033]

According to the present invention, a dehydration reaction involving formalin, carboxylic acid and alcohol can be efficiently carried out in a liquid phase at 200 ° C. or lower. This is extremely advantageous for industrial implementation.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C07C 37/20 9155-4H C07C 37/20 39/16 9155-4H 39/16 41/50 7419- 4H 41/50 43/30 7419-4H 43/30 67/08 67/08 69/44 69/44 C07D 323/06 C07D 323/06 // C07B 61/00 300 C07B 61/00 300

Claims (3)

(57) [Claims] 1. A dehydration reaction using at least one selected from formalin, carboxylic acid, and alcohol as a raw material using an acid-type zeolite ZSM-5 catalyst in a liquid phase at 200 ° C. or lower. The zeolite ZSM-5 in which the zeolite ZSM-5 catalyst is hydrothermally synthesized only from inorganic substances
5. A dehydration reaction method according to 5, wherein 2. The method according to claim 1, wherein the dehydration reaction is an acetal synthesis reaction from formalin and alcohol. 3. The method according to claim 1, wherein the dehydration reaction is a trioxane synthesis reaction from formalin.