JPH0564954B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is applicable to the field of producing 1,4-dioxane from dihydric alcohols having an oxyethylene group as a basic unit. The present invention relates to a method capable of producing 1,4-dioxane in high yield, with easy separation from products, and repeated use of a catalyst.

[Prior art and its problems] Conventionally, methods for producing 1,4-dioxane include, for example, a method in which polyethylene glycol such as diethylene glycol is brought into contact with a sulfuric acid catalyst;
A method is known in which ethylene oxide is cyclized and dimerized using an acid catalyst such as sulfuric acid or boron trifluoride.

However, when mineral acids such as sulfuric acid or halogen acids are used as catalysts, they have a strong corrosive effect on equipment, so there is a problem in that the equipment needs to be made of expensive metal materials. If the catalyst is mixed into the reaction system, the catalytic action is reduced, and there are also problems in post-processing such as regenerating the catalyst and disposing of the used catalyst.

As a method to solve these problems, JP-A-49-95981 discloses a method for producing 1,4-dioxane from diethylene glycol at a temperature of 140 to 170°C using an acidic ion exchange resin as a catalyst. Disclosed.

However, the acidic ion exchange resin used in this method generally tends to deoxidize sulfonic acid groups at temperatures above 120°C, impairing the catalytic effect, so it is difficult to react by adjusting the reaction temperature. It has serious disadvantages in that it is difficult to maintain a sufficiently high speed and it is also difficult to regenerate a deactivated catalyst.

Furthermore, as a method for solving the above-mentioned drawbacks, JP-A-52-83472 discloses a method for producing 1,4-dioxane from dihydric alcohols using an inorganic solid acid as a catalyst.

However, in this method, the inorganic solid acids used as catalysts include so-called non-crystalline solid acid catalysts such as silica alumina and alumina boria, so-called zeolite solid acids such as mordenite-H type solid acids and X type zeolites, and natural clays. The disadvantage is that the yield of 1,4-dioxane is around 70%, which is still not sufficient.

The present invention has been made based on the above circumstances.

That is, an object of the present invention is to solve the above-mentioned problems, eliminate problems such as corrosion of equipment and catalyst post-treatment, facilitate regeneration of the catalyst, and improve the yield of 1,4-dioxane, which is the target product. The object of the present invention is to provide an industrially advantageous method for producing 1,4-dioxane from dihydric alcohols using a novel catalyst with a sufficiently high yield.

In order to achieve the above-mentioned object, the present inventors have made extensive studies, and as a result, the above-mentioned object has been achieved by using a crystalline metal silicate containing a specific metal element in a specific composition ratio as a catalyst. We have discovered that this is possible, and have arrived at the present invention.

[Means for solving the above problems] The gist of the present invention for solving the above problems is as follows:
Constructed with oxyethylene group as the basic unit 2
Hydrolic alcohols are heated to a reaction temperature of 100 to 500℃,
1, characterized in that it is brought into contact with a crystalline metal silicate in which the molar ratio (SiO ₂ /M ₂ O ₃ ) of silicon oxide (SiO ₂ ) and trivalent metal oxide is within the range of 12 to 3000. , 4-dioxane.

The dihydric alcohols composed of oxyethylene groups as basic units in the present invention have the general formula:
A compound represented by HO-(CH ₂ CH ₂ O-)H (n is an integer of 1 or more), specifically ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and average Polyethylene glycol with a molecular weight of 238 or more. These dihydric alcohols can be used alone or as a mixture. Of these, ethylene glycol, diethylene glycol and triethylene glycol are most preferred.

The crystalline metal silicate used as a catalyst in the present _invention has _a general formula of _{M2O3.XSiO2.mH2O .}
(mH ₂ O is crystalline water, part of which is used as H+, m varies depending on the type of M, the valence of X, etc.) and silicon oxide. M is composed of Al, Ga, B,
One or more metal elements selected from Fe, In, La, Sc, Y, Cr, and Ti, and
X, that is, the molar ratio (SiO ₂ /M ₂ O ₃ ) is 12 to
3000, preferably in the range of 40 to 3000, and is a crystalline metal silicate having a cation exchange ability. If the molar ratio (SiO ₂ /M ₂ O ₃ ) is less than 12, the yield of 1,4-dioxane may be low, which is undesirable. On the other hand, if it exceeds 3000, the conversion of the raw material dihydric alcohol is This is not preferable because the rate will be low. Among these, zeolites having a main cavity of a 10-membered oxygen ring, particularly crystalline metal silicates belonging to metal silicates having a pentasil type structure, are preferred. As such a crystalline metal silicate, for example, M is
Regarding the case of Al, ZSM-
5. Described in Japanese Patent Application Laid-Open No. 47-25097
There are ZSM-8 and ZSM-11 described in Japanese Patent Publication No. 53-23280. Others, JP-A-52-
ZSM-35 described in Publication No. 139029 etc.
A crystalline aluminosilicate such as ZSM-21 described in publications such as US Pat. No. 4,001,346 and having a SiO ₂ /M ₂ O ₃ ratio of 12 or more can also be used.

Also, as an example where M is B, it is described in JP-A-53-55500 or JP-A-55-7598.
There are crystalline borosilicates having a ZSM-5 type structure or a ZSM-11 type structure. As an example where M is Fe, see Journal of Catalysis, Vol. 35, pp. 256-272 (1974), JP-A No. 127898-1974, or JP-A No. 127898/1973.
There are crystalline iron silicates such as ferrierite described in No.-85415. An example where M is Ga is ZSM-5 described in Reference Example 3 below.
There are crystalline gallosilicates, such as gallosilicate, which have a type structure. M is In, La, Sc, Y,
Examples of Cr and Ti include crystalline metals having a structure in which trivalent Al incorporated in the skeleton of the crystalline aluminosilicate is replaced with trivalent In, La, Sc, Y, and Cr, respectively. There are silicates.

Among these, M in the general formula is Al, Ga,
B is preferred, and Al and Ga are particularly preferred.

The crystalline metal silicate used in the method of the present invention can be prepared by a known method.

For example, a method for synthesizing a pentasil type crystalline metal silicate represented by the ZSM-5 type zeolite is as follows: in the presence or absence of a _C2 to _C5 tetraalkylammonium halide or other amines. Silicic acid or its condensates, such as colloidal silica or water glass, as a silica source, or silicates, as a metal oxide (M ₂ O ₃ ) source, e.g. aluminum sulfate, gallium nitrate, boric acid, ferric sulfate. It is known that it can be prepared by hydrothermal synthesis using a mixture mainly consisting of sulfates, nitrates, or oxyacids of the metal element M such as chromium sulfate and sodium aluminate.

Also known is a method in which an alkali metal hydroxide such as sodium or an alkali metal compound such as a halide is allowed to coexist during the hydrothermal synthesis.

The crystalline metal silicates obtained by these methods are generally not of the H+ type, and H+ is replaced with quaternary ammonium ions and/or alkali metal ions such as Na+.
It is preferable to change this to the H+ type. This conversion can be easily accomplished by known methods.

For example, it is known that converting a quaternary ammonium ion to H+ can be achieved by firing it in air at a temperature of about 500 to 600°C; on the other hand, replacing an alkali metal ion such as Na+ with H+ For example, an alkali metal salt type crystalline metal silicate is treated with an aqueous solution of an ammonium salt such as ammonium nitrate or ammonium chloride to obtain an ammonium salt type crystalline metal silicate, and then calcined in air at 300 to 600°C. , a method of obtaining H+ type crystalline metal silicate is often used.

In addition to these methods, a method of directly treating with dilute acid such as dilute hydrochloric acid can also be used.

Various methods other than these are known as methods for synthesizing crystalline metal silicates.

The crystalline metal silicate used as a catalyst in the method of the invention can be synthesized by any of these methods, and the invention is not limited to the use of a catalyst by a particular method of preparation.

In addition, in the present invention, the crystalline metal silicate is
Although the H+ type is preferable, unless the purpose of the present invention is hindered, some or all of the H+ in the catalyst may be in the form of other cations such as magnesium ions,
Calcium ions, lanthanum ions, etc. may be substituted.

The solid catalyst in the present invention may be in any shape such as powder, granules, strips, spheres, or pellets.

In the present invention, when zeolite is watertightly synthesized by blending an organic compound such as a quaternary amine, in order to improve the catalytic activity, it is necessary to synthesize the zeolite in a stream of air and/or an inert gas such as nitrogen before the reaction. Preferably, the crystalline metal silicate is fired.

In this case, the firing conditions vary depending on the type of crystalline metal silicate, the degree of residual quaternary ammonium ion and structural water, etc., but usually 400 to 600
℃, preferably at a temperature of 450 to 550℃ for 1 hour or more,
Organic compounds in the zeolite are preferably removed by heating for 3 hours or more.

In the present invention, when bringing the dihydric alcohol as a reaction raw material into contact with the crystalline metal silicate as a catalyst, it is usually preferable to bring the dihydric alcohol into contact in a liquid phase.

As the reaction method, any method such as a flow method or a batch method may be used.

In the method for producing 1,4-dioxane according to the present invention, the contact between the dihydric alcohol and the catalyst is carried out at a temperature of 100 to 500°C, preferably 150 to 350°C, most preferably 200 to 250°C. The lower the temperature, the slower the reaction rate, which is disadvantageous, and the higher the temperature, the more likely decomposition reactions of reaction materials and products occur.

The time required for the reaction varies depending on the reaction temperature, type of catalyst, etc., but it is usually 1 to 48 hours in the case of a batch method, preferably 5 to 24 hours, and 5 to 24 hours in the case of a flow method. , operate at LHSV corresponding to the reaction time of the batch method.

This reaction does not particularly need to be carried out in the presence of a solvent, but can be carried out in the presence of an inert hydrocarbon or a solvent that does not adversely affect this reaction.

In either case, the reaction can be carried out under autogenous pressure or pressure at the reaction temperature, and in the case of a batch process, the reaction may be carried out while distilling off the product 1,4-dioxane. It is valid.

The amount of crystalline metal silicate used as a catalyst in the present invention varies depending on the type of catalyst, the type of dihydric alcohol as a reaction raw material, and other reaction conditions. Usually 0.1 to 30% by weight, preferably 1
~10% by weight.

After the reaction is completed, the catalyst can be separated and removed by a solid-liquid separation operation, and then 1,4-dioxane can be isolated and purified by distillation, but in the batch method, the catalyst is usually separated and removed by a solid-liquid separation operation. There is no need to remove the produced 1,4-dioxane, and the produced 1,4-dioxane is distilled out of the system together with the produced water. In addition, in the flow method, if the catalyst is a fixed bed, there is no need for solid-liquid separation operation. Unreacted dihydric alcohols recovered by the distillation operation can be reused as starting materials.

In the present invention, the crystalline metal silicate used as a catalyst can be effectively used as a catalyst repeatedly until it is destroyed and lost by appropriately performing a calcination operation to remove coke.

[Effects of the Invention] According to the present invention, the following effects can be achieved.

(1) In the present invention, when producing 1,4-dioxane from dihydric alcohols, a specific crystalline product having a limited molar ratio and consisting of a silicon oxide and a trivalent metal oxide is used. According to the invention, since a metal silicate catalyst is used,
Conventional silica alumina, mordenite-H,X
1,4-dioxane can be obtained in a higher yield than when using type zeolite etc.
The present invention has significant industrial advantages.

(2) The method of the present invention is extremely advantageous in practice compared to conventional mineral acids such as sulfuric acid, halogen acids, etc., since the crystalline metal silicate catalyst does not have a corrosive effect on metals.

(3) In the method of the present invention, the crystalline metal silicate catalyst has high thermal stability and can be used at relatively high temperatures. Therefore, the reaction rate can be kept sufficiently high and the activity can be maintained. It lasts for a long time and can be effectively used as a catalyst many times by further firing, reducing the manufacturing cost per catalyst compared to conventional acid catalysts and ion exchange resin catalysts. This is extremely advantageous industrially.

[Example] Next, Examples, Reference Examples, and Comparative Examples of the present invention will be shown.

(Reference Example 1; Preparation of crystalline aluminosilicate ()) 7.5 g of aluminum sulfate was dissolved in 250 ml of water,
Further, 17.6 g of concentrated sulfuric acid and 26.3 g of tetra n-propylammonium bromide were dissolved in this to prepare liquid A, and water glass [J sodium silicate 3
No.: Nihon Kagaku Kogyo Co., Ltd.] 211.0 g was dissolved in 250 ml of water to obtain liquid B, and 79.0 g of sodium chloride was further dissolved in 122 ml of water to form liquid C.

Next, the above solutions A and B were simultaneously added dropwise to solution C at room temperature for 10 minutes. The resulting mixture was placed in an autoclave and heat-treated at 170°C for 20 hours. After cooling, the contents were filtered and washed with water at 120℃.
and dried for 12 hours. X-ray diffraction analysis of the product confirmed that it was ZSM-5. The obtained ZSM-5 was calcined at 550°C for 6 hours to obtain 56.5 g of sodium type ZSM-5. This sodium form ZSM-5 was added to a 1N ammonium nitrate aqueous solution weighing 5 times its weight, and the mixture was refluxed for 8 hours. Thereafter, the mixture was cooled and left to stand, and the supernatant was removed by decantation. Furthermore, after repeating the reflux and dencation operations three times, the contents were filtered and washed with water, dried at 120°C for 12 hours, and ammonium-type ZSM
-5 was obtained. The SiO ₂ /Al ₂ O ₃ ratio of this product was 90 (molar ratio). This ammonium type ZSM-5 was calcined in air at 550°C for 5 hours to obtain H type ZSM-5, that is, crystalline aluminosilicate ().

(Reference Example 2; Preparation of crystalline aluminosilicate ()) In the preparation of crystalline aluminosilicate () described in Reference Example 1, the amount of aluminum sulfate was changed from 7.5 g to 15 g, and the other preparation conditions were completely changed. Crystalline aluminosilicate () was prepared in the same manner. SiO ₂ /Al ₂ O ₃ of this = 45
(molar ratio).

(Reference Example 3; Preparation of crystalline gallosilicate) 2.34 g of gallium nitrate, 4.42 g of concentrated sulfuric acid, and 6.58 g of tetra-n-propylammonium bromide
Solution A, which is obtained by dissolving 52.78 g of water glass [J Sodium Silicate No. 3; manufactured by Nihon Kagaku Kogyo Co., Ltd.] in 62 ml of water, was added to the water.
62 ml of dissolved solution B and sodium chloride
Solution C was prepared by dissolving 19.75 g in 30 ml of water.
Solutions A and B were then added dropwise to solution C at the same time. Put the resulting mixture into an autoclave,
The reaction was carried out at a reaction temperature of 170°C for 24 hours. After cooling, the contents of the autoclave were filtered and washed with water and incubated at 120°C for 12
After drying for an hour, it was further calcined at 600°C for 6 hours to obtain 9.6 g of sodium type crystalline gallosilicate.

Next, the obtained gallosilicate was added to 5 times the weight of 1N ammonium nitrate solution, heated at 80° C. for 8 hours, cooled, and filtered. Furthermore, after repeating the heating and filtration operation three times, the solid material was washed with water and
After drying at ℃ for 16 hours, the composition ratio of SiO ₂ and Ga ₂ O ₃ of ammonium type crystalline gallosilicate is SiO ₂ /Ga ₂ O ₃
=75.5 (molar ratio). Moreover, this gallosilicate was found to have a ZSM-5 structure by X-ray diffraction. This ammonium type crystalline gallosilicate was calcined in air at 550°C for 4 hours to obtain H type crystalline gallosilicate.

(Example 1) Diethylene glycol was added to a three-necked flask equipped with a distillation device capable of distilling the product.
50.0g and 1.0g of the crystalline aluminosilicate () prepared in Reference Example 1 were added, the reaction temperature was kept at 200°C, and stirring was continued for 10 hours. The total amount of product distilled during this period was 47.2 g. The product was analyzed by gas chromatography, and 1,4-dioxane was obtained with a yield of 92%.
By-products were acetaldehyde and ethylene glycol (1% each).

(Example 2) 50.0 g of diethylene glycol was further added to the reaction residue of Example 1, and stirring was continued for 12 hours in the same reaction apparatus while maintaining the reaction temperature at 200°C. The total amount of product distilled during this period was 48.5 g. As a result of gas chromatography analysis, the yield of 1.4-dioxane was 95
It was %.

(Example 3) In Example 1, ethylene glycol was used instead of diethylene glycol, and the stirring time was 20
The same procedure was carried out except that the time was changed. The amount of product distilled out was 46.2 g, and the yield of 1,4-dioxane at this time was 90%. 2% of the raw material ethylene glycol was recovered in the product distillate.

(Example 4) The reaction was carried out in the same manner as in Example 1 except that triethylene glycol was used instead of diethylene glycol. The total distilled amount of product was 48.9 g, and the yield of 1,4-dioxane was 86%.

(Example 5) The reaction was carried out in the same manner as in Example 1 except that the crystalline gallosilicate prepared in Reference Example 3 was used instead of the crystalline aluminosilicate ().
The total distilled amount of product was 46.1 g, and the yield of 1,4-dioxane was 90%.

(Example 6) In Example 1, the reaction was carried out in the same manner as in Example 1, except that the crystalline aluminosilicate () of Reference Example 2 was used instead of the crystalline aluminosilicate () of Reference Example 1. Ta. The total distillate amount of product was 46.8 g, and the yield of 1,4-dioxane was
It was 87%.

(Comparative Example 1) In Example 1, synthetic mordenite (Toyo Soda TSZ-600) SiO ₂ /Al ₂ O ₃ = 10 (molar ratio) was used instead of the crystalline aluminosilicate ( ) of Reference Example 1.
The reaction was carried out in the same manner as in Example 1 using . The total distilled amount of product was 35.4 g, and the yield of 1,4-dioxane was 58%.

Claims (1)

[Claims] 1. A dihydric alcohol composed of an oxyethylene group as a basic unit is reacted with silicon oxide (SiO ₂ ) and a trivalent metal oxide at a reaction temperature of 100 to 500°C. 1. A method for producing 1,4-dioxane, which comprises bringing it into contact with a crystalline metal silicate having a molar ratio (SiO ₂ /M ₂ O ₃ ) in the range of 12 to 3000. 2. 1 according to claim 1, wherein the dihydric alcohol is at least one selected from the group consisting of ethylene glycol, diethylene glycol, and triethylene glycol.
Method for producing 4-dioxane. 3. The method for producing 1,4-dioxane according to claim 1 or 2, wherein the crystalline metal silicate is a zeolite having a main cavity of 10-membered oxygen rings. 4. The crystalline metal silicate is a crystalline aluminosilicate having a ZSM-5 type or ZSM-11 type structure, a crystalline gallosilicate having a ZSM-5 type or ZSM-11 type structure, and a ZSM
Claims 1 and 2 are at least one selected from the group consisting of crystalline borosilicate having -5 type or ZSM-11 type structure.
The method for producing 1,4-dioxane according to item 1 or 3.