JPH0748319A - Production of dialkyl carbonate - Google Patents

Abstract

PURPOSE:To provide a production method of a dialkyl carbonate in high conversion ratio in the presence of a catalyst of heterogeneous system maintaining high activity throughout the whole process irrespective of the number of carbons of an alcohol compound and reaction conditions such as reaction temperature by reacting the alcohol compound with a cyclic carbonate. CONSTITUTION:This production of a dialkyl carbonate is carried out by subjecting an alcohol compound and a cyclic carbonate to liquid-phase catalytic reaction in the presence of a zeolite having undergone ion exchange with an alkali metal ion and/or an alkaline earth metal ion at 20-200 deg.C. In the reaction, the reaction system retains a liquid phase at the reaction temperature and has usually 0-40kg/cm<2>G self pressure. A zeolite wherein the all ion exchange sites of the zeolite are occupied by one or more alkali metal or alkaline earth metal may be cited as the zeolite having undergone ion exchange. Especially an A type or X type zeolite wherein >=50% of the ion exchange sites is subjected to ion exchange with potassium (K) in alkali metals is preferable as the zeolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a dialkyl carbonate from an alcohol compound and a cyclic carbonate as raw materials in the presence of an ion-exchanged zeolite exchanged with an alkali metal ion and / or an alkaline earth metal ion. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a dialkyl carbonate from an alcohol and a cyclic carbonate, there is a method for producing dimethyl carbonate and ethylene glycol by reacting methanol and ethylene carbonate in the presence of a homogeneous or heterogeneous catalyst. Are known. In the above method, as a production method by a homogeneous catalytic reaction, a method using an amine such as triethylamine, an alkali metal such as sodium, an alkali metal compound such as sodium chloroacetate or sodium methylate or a thallium compound as a catalyst is known. ing. On the other hand, as a production method by a heterogeneous catalytic reaction, a method using an ion exchange resin as a catalyst has been conventionally proposed. For example,
In JP-A-64-31737, ion-exchange resins having various functional groups, amorphous silica impregnated with alkali and alkaline earth metal silicates, or ammonium-exchanged Y-type zeolite as a catalyst. A heterogeneous catalytic reaction method has been proposed. In the above-mentioned conventional reaction method using a catalyst, the reaction method using a heterogeneous catalyst is easier to separate the reaction mixture and the catalyst than the homogeneous catalyst reaction, and is industrially preferable.

[0003]

However, when the above-mentioned ion exchange resin or silica impregnated with alkali and alkaline earth metal silicates is used as a catalyst, the catalytic active sites are irregularly present. It becomes non-uniform, and it is considered difficult to improve the catalytic activity. That is, in the above ammonium-exchanged Y-type zeolite catalyst, the ammonia component is volatile, the active sites may become unstable, and the catalytic activity may be low. In fact, in the comparative example described later, at the reaction temperature of 50 ° C., the expression of the catalytic activity for the conversion reaction was not observed. Further, the ion exchange resin is inferior in organic solvent resistance as compared with the inorganic compound, and particularly, it is remarkable under heating. Furthermore, when used for a long period of time, the functional group which is the active site of the ion-exchange resin catalyst disappears due to elution and the like, so that the catalytic activity decreases, and eventually it permanently deteriorates.

Generally, in the catalytic reaction, when the catalytic activity is low or decreases, the yield of the target product is low,
Or, since it decreases, it is necessary to raise the reaction temperature to increase the reaction rate to increase the conversion rate and supplement the catalytic activity. However, since the ion exchange resin has low thermal stability, the maximum operating temperature cannot be increased, and even when the reaction temperature is raised, it is up to about 100 ° C. Further, in the ammonium-exchanged zeolite catalyst, the ammonium component is volatile as described above, so that the catalytic activity cannot be stably maintained. Therefore, when the ion-exchange resin and ammonium-exchanged zeolite are industrially used as catalysts, the catalytic reaction is complicated in operation and is not easy to control. Therefore, it is difficult to expect a significant improvement in productivity.

The present invention solves the above-mentioned drawbacks of conventional catalysts applied to a method for producing a dialkyl carbonate by reacting an alcohol compound with a cyclic carbonate, maintains high activity throughout the entire reaction process, and requires If 10
It is an object of the present invention to provide a heterogeneous catalyst which can be operated at a high temperature of 0 ° C. or higher to improve the reaction rate and which can be easily separated from the reaction mixture. At the same time, another object of the present invention is to provide a method for producing a dialkyl carbonate from an alcohol compound and a cyclic carbonate at a high conversion rate by using the above-mentioned catalyst.

[0006] In order to achieve the above-mentioned object, the present inventors have found that while the conventional ammonium-exchanged Y-type zeolite catalyst has the above-mentioned drawbacks, the constituent zeolite thereof is essentially heat-resistant and organic solvent-resistant. It has excellent properties and has a more uniform catalytic active point than ion-exchange resins, so it was reviewed. That is, zeolite can contain a cation in the condensed anion cavity of the three-dimensional skeleton structure of the aluminosilicate constituting the crystalline aluminosilicate, the anion and the cation are balanced, electrostatically Since it is stable, uniform active points can be formed. Furthermore, since zeolite has excellent heat resistance, the zeolite itself has durability even at high temperatures, can be used at high temperatures if necessary, and has excellent organic solvent resistance, and is desirable as a constituent component of a catalyst. Therefore, as a result of another intensive study on the zeolite catalyst,
The present invention has been reached.

[0007]

According to the present invention, an alcohol compound and a cyclic carbonate are reacted at a reaction temperature of 20 in the presence of an ion-exchanged zeolite ion-exchanged with an alkali metal ion and / or an alkaline earth metal ion.
Provided is a method for producing a dialkyl carbonate, which comprises performing a liquid phase reaction at ˜200 ° C. The liquid phase reaction in the present invention is one in which the reaction system maintains the liquid phase at the reaction temperature, that is, it is carried out at a pressure equal to or higher than the self-pressure generated in the reaction system at the reaction temperature, and usually 0 to 40 kg / cm ^2.
G. In the present invention, the ion-exchanged zeolite means a zeolite in which all ion-exchange sites of the zeolite are ion-exchanged with any desired alkali metal and / or alkaline earth metal cation. That is, it means that it is occupied by one or more alkali or alkaline earth metals. In particular, potassium (K) among alkali metals has 50 ion exchange sites.
% Or more ion-exchanged type A or type X zeolite is preferred. In this case, the ion exchange rate of K is 100%
In the case of less than, a zeolite in which the remaining ion exchange sites are ion-exchanged with other alkali metal and / or alkaline earth metal ions is preferable.

[0008]

The present invention is constituted as described above, and since the ion exchange zeolite catalyst used for the liquid phase catalytic reaction has a uniform catalytic activity site, a dialkyl carbonate can be obtained from an alcohol and a cyclic carbonate at a high conversion rate.
Further, the zeolite catalyst used in the present invention, the ion exchange sites are exchanged with alkali metal or alkaline earth metal ions, for example, the temperature and pressure at which the raw material alcohol such as methanol and diethyl carbonate and the cyclic carbonate can be reacted. It retains stable catalytic activity under the reaction conditions of. Further, in the present invention, preferably SiO ₂
A type zeolite having a molar ratio of / Al ₂ O ₃ of about 2 or an X type zeolite having a molar ratio of SiO ₂ / Al ₂ O ₃ of about 2.4 to 2.5 is used to form a cyclic carbonate. It can be obtained with a high conversion rate. This is because the A-type and X-type zeolites have a higher ion exchange capacity than ordinary ion exchange resins, have improved catalytic ability, and are more preferable as catalyst components.

According to the present invention, in a reaction in which an alcohol and a cyclic carbonate are catalytically reacted to convert into a dialkyl carbonate and an alkylene glycol, zeolite which is excellent in heat resistance temperature and organic solvent resistance and is inexpensive is used as a catalyst component for ion exchange. As compared with a typical catalyst ion exchange resin of the conventional method, the catalyst active sites can be present uniformly and the exchanged ions are non-volatile with alkali metal and / or alkaline earth metal. Because
Stable catalytic activity can be obtained even under reaction conditions of 100 ° C. or higher. That is, according to the method of the present invention, a stable and uniform catalytic activity can be maintained throughout the catalytic reaction between an alcohol and a cyclic carbonate, so that the dialkyl carbonate can be obtained at a high conversion and a high concentration.

The present invention will be described in detail below. The reaction between the alcohol and the cyclic carbonate in the present invention is known as described above. As the cyclic carbonate and alcohol as the reaction raw materials, general commercial products can be used. Usually, a commercially available product can be used as it is or after being dehydrated. The raw material cyclic carbonate of the present invention is not particularly limited, but is preferably a lower alkylene cyclic carbonate such as ethylene carbonate, propylene carbonate, butylene carbonate,
More preferably, ethylene carbonate or propylene carbonate can be used.

The raw material alcohol may be any alcohol that reacts with a cyclic carbonate to give a carbonate ester,
There is no particular limitation. Preferably, it is an aliphatic or aromatic alcohol having 1 to 10 carbon atoms, specifically, methanol, ethanol, n-propanol, iso-.
Propanol, n-butanol, iso-butanol,
Secondary butanol, tertiary butanol, allyl alcohol,
Pentanol, cyclohexanol, benzyl alcohol, 2-phenylethyl alcohol, 3-phenylpropyl alcohol, 2-methoxyethanol, etc. can be mentioned. Particularly, lower aliphatic alcohols are more preferable. Although not an alcohol, a phenolic compound can be used as a compound having an OH group and reacting with a cyclic carbonate to generate a carbonic acid ester.

The zeolite constituting the catalyst of the present invention may be either natural zeolite or synthetic zeolite,
Synthetic zeolites are generally preferred because of their homogeneity with a given quality. The zeolite of the present invention is usually SiO
_{The 2} / Al ₂ O ₃ molar ratio is 2 to 100, preferably 2 to 6, and more preferably 2 to 3. The average crystal diameter of the zeolite used in the present invention is preferably 50% by weight or more and about 30 μm or less, and more preferably about 10 μm.
m or less. Specific examples of the zeolite structure used in the present invention include LTA (A-type zeolite) and FAU.
(X type, Y type zeolite, etc.), LTL (L type zeolite, etc.), MOR (mordenite), MAZ (Ω type zeolite, etc.), FER (ferrierite), MFI (ZSM-
Zeolites having the crystal structure of 5) are preferred. Of these, LTA and FAU X-type structures are particularly preferable. In addition, these zeolite structures are the Structure Commission of the International Zeolite Association (The structure Comm
It belongs to the known zeolite crystal structure published by the ission of the International Zeolite Association.
(WM Meier, DH Olson)
Co-authored “Atlas of Zeolite Structure
Types (Atlas of Zeolite Structure Types) 198
(See 7 years)

In the catalytic reaction of the dialkyl carbonate of the present invention, the above-mentioned ion-exchange sites of each zeolite are alkali metals (Li, Na, K, Rb, Cs) belonging to the groups Ia and / or IIa of the periodic table of elements, and And / or in the presence of a catalyst composed of an alkali metal and / or an alkaline earth metal exchanged zeolite ion-exchanged with an alkaline earth metal (Be, Mg, Ca, Sr, Ba). The alkali metal and / or alkaline earth metal ion-exchanged zeolite catalyst of the present invention includes a desired alkali metal and / or alkaline earth metal cation (hereinafter simply referred to as cation such as alkali metal) during zeolite synthesis.
Include zeolites produced in such a form that occupies the ion-exchange site, for example, Na-exchanged A-type zeolite and Na-exchanged X-type zeolite in which the ion-exchange site is occupied by sodium. Further, it is possible to use ion-exchanged zeolite in which all or part of sodium occupying the ion-exchange sites of these Na-exchanged A-type zeolites is ion-exchanged with other alkali metal and / or alkaline earth metal, for example, potassium ion. it can.

Further, the alkali metal ion-exchanged zeolite catalyst of the present invention also includes the above-mentioned various zeolites which are subjected to an ion exchange treatment to introduce a desired cation such as an alkali metal into the ion exchange site.
In this case, as the alkali metal cation source for ion exchange, inorganic salts such as nitrates and chlorides, organic acid salts such as acetates and the like can be used. Furthermore, as the catalyst of the present invention, in addition to the alkali metal etc. cation at the ion exchange site of the cation exchange zeolite of the above alkali metal etc., a zeolite obtained by appropriately presenting a desired cation such as an alkali metal other than the ion exchange site is used. May be.
In this case, it can be prepared by further treating the above cation-exchanged zeolite such as alkali metal with an aqueous solution containing a cation such as alkali metal by an impregnation method or a spray method.

The form of use of the zeolite catalyst of the present invention is not particularly limited, and it can be usually used in the form of powder, granules, spheres, pellets, beads or the like. The above various molded bodies are clay minerals,
It can be obtained by adding a binder such as alumina and molding it into granules, spheres, pellets or the like by a method such as extrusion molding, spray drying, tablet molding, tumbling granulation or oil granulation.
In addition, a metal component such as tin, lead, zinc, or titanium as a catalyst auxiliary component can be supported on the zeolite catalyst by an ion exchange method or an impregnation method.

In the reaction of the present invention, the reactivity decreases as the carbon number of the raw material alcohol increases. Therefore, when an alcohol raw material having a large number of carbon atoms is used, it is necessary to operate at a higher temperature within the reaction temperature range described below in order to increase the reactivity, but the zeolite catalyst of the present invention is thermally stable as described above. Since it has high properties, a stable reaction operation can be obtained regardless of the carbon number of the raw material alcohol, and it is industrially suitable.
In contrast to this, the conventional ion-exchange resin catalyst has low thermal stability and causes a problem in industrial use depending on the number of alcohol carbon atoms, as described above. The catalyst of the present invention is heated and dried under a nitrogen gas or air atmosphere before being subjected to the reaction. The drying temperature may be in a temperature range where the zeolite crystal structure is not destroyed, and usually 200 to 60
0 ° C is preferred. Further, the catalyst whose activity has been lowered in the reaction can be reactivated by the same heat treatment.

The reaction mode of the present invention is not particularly limited. For example, a generally known reaction mode such as a flow system using a fluidized bed or a fixed bed or a stirring system can be adopted. With these reaction methods, the raw material alcohol and the cyclic carbonate can be converted in the presence of the above-mentioned cation-exchanged zeolite catalyst such as an alkali metal to obtain a dialkyl carbonate. Further, the method for producing a dialkyl carbonate of the present invention may be continuous or batchwise, and can be appropriately selected depending on the purpose together with the reaction form.

In the present invention, the reaction conditions are a reaction temperature of 20 to 200 ° C., preferably 50 to 180 ° C., and the reaction product, that is, the reaction system, maintains the liquid phase at the reaction temperature,
The reaction pressure may be equal to or higher than the self-pressure generated in the reaction system at the reaction temperature, and is usually 0 to 40 kg / cm.
² G, preferably 0 to 26 kg / cm ² G. Liquid hourly space velocity (LHSV) 0.1-1
It can be performed in the range of ⁰ hr ⁻¹ . Reaction temperature is 20 ℃
If it is less than the above range, the reaction rate decreases, which is not practical. Also, 2
When the temperature is higher than 00 ° C, thermal decomposition of the cyclic carbonate is promoted, which is not preferable. Further, the reaction pressure does not proceed even if the pressure is reduced, and even if the reaction pressure exceeds 40 kg / cm ² G, the further effect of accelerating the reaction cannot be obtained. If the LHSV in the distribution system is less than 0.1 hr ^-1 , it is not practical because a sufficient treatment amount cannot be obtained. On the other hand, if it exceeds 10 hr ^-1 , the conversion rate of the reaction is extremely low, which is inconvenient.
As described above, the reaction temperature and pressure of the present invention are selected so as to maintain the reaction system such as the reaction raw materials and reaction products in a liquid phase state, and the present invention is of an inert solvent such as benzene and toluene. It can be carried out in the presence.

In the present invention, the raw material alcohol and the cyclic carbonate are preferably supplied to the reaction zone under the above reaction conditions at an alcohol / cyclic carbonate molar ratio of about 2 to 20. If the molar ratio is less than about 2, the conversion becomes low, and if it is more than 20, the recovery of the raw material alcohol increases and the working efficiency decreases, which is not practical. In the present invention, the desired dialkyl carbonate can be produced together with the alkylene glycol by reacting the alcohol with the cyclic carbonate as described above. The resulting reaction product mixture is
Thereafter, by performing a predetermined purification treatment such as distillation, the reaction raw material and the reaction product can be separated, and further the product dialkyl carbonate and alkylene glycol can be separately obtained. Further, the unreacted raw material can be recovered and reused, and can be circulated and used in the raw material supply section in the continuous flow system.

[0020]

EXAMPLES The present invention will be described in more detail based on the following examples. However, the present invention is not limited to the following examples. In the following examples, the conversion rate is calculated by the following formula. Conversion rate (%) = dialkyl carbonate (mol) / raw material cyclic carbonate (mol) × 100 In this case, hydroxyalkylene alkyl carbonate is produced as a reaction intermediate, but it is further reacted with alcohol to form dialkyl carbonate. It was not included in the dialkyl carbonate content of the product.

Examples 1 to 3 A type zeolite having a commercially available SiO ₂ / Al ₂ O ₃ molar ratio of 2 was used as a catalyst, and potassium (K) and sodium (N
a) and powdered ion-exchanged A-type zeolite (manufactured by Union Carbide Co., each trade name: 3A powder, 4A powder, 5A powder) ion-exchanged with three kinds of alkali metal ions of calcium (Ca) It was used after being dried. Table 1
10 g of each dried catalyst was placed in a flask having a capacity of 300 ml equipped with a condenser and a stirrer.
And a raw material consisting of methanol and ethylene carbonate (mole ratio of methanol / ethylene carbonate = 4) 2
35 g was supplied, and the mixture was maintained at 50 ° C. and stirred. The reaction mixture was analyzed using a gas chromatograph. The results of gas chromatograph analysis of the reaction mixture after 5 hours of reaction are shown in Table 1.
It was shown to.

[0022]

[Table 1]

Example 4 Commercially available pelletized K-exchanged A-type zeolite (union
Carbide, product name: 3A pellet) is crushed to 1
What was sieved to 6 to 24 mesh was filled as a catalyst, and the reaction was carried out using a flow type fixed bed reactor. The reaction conditions are temperature: 90 ° C., pressure: 7 kg / cm ² , liquid hourly space velocity (LSVH): 1 hr ^-1 , catalyst amount: 10 ml, raw material:
A methanol / ethylene carbonate molar ratio of 4 was adopted. The reaction mixture was analyzed using a gas chromatograph as in Example 1. As a result, the raw material delivery 42
Conversion of ethylene carbonate at time 6.6
%, The concentration of dimethyl carbonate was 2.8% by weight, and the concentration of ethylene glycol was 1.9% by weight.

Example 5 Reaction temperature 120 ° C., pressure 10 kg / cm ² and LSVH
The reaction was performed in the same manner as in Example 4 except that 0.3 hr ^{−1 was used,} and the reaction mixture at the 50th hour after the raw material was fed was analyzed in the same manner by gas chromatography. As a result, the conversion rate of ethylene carbonate was 42.5%, the concentration of dimethyl carbonate was 18.0% by weight, and the concentration of ethylene glycol was 13.0.
% By weight.

Comparative Example 1 As a catalyst, Y having a SiO ₂ / Al ₂ O ₃ molar ratio of 4.8 was used.
Ammonium-exchanged Y-type zeolite ion-exchanged with ammonium ion (NH ₄ ⁺ ) of type-zeolite (Product name: S
K41, manufactured by Union Carbide)
Reaction was carried out in the same manner as in Example 1. As a result, the conversion rate of ethylene carbonate after 5 hours of reaction time was 0%, and formation of dimethyl carbonate was not confirmed.

Examples 6 to 10 Reactions were carried out in the same manner as in Examples except that the following catalysts were used. (Example 6): Na exchange Y-type zeolite (SiO ₂ / A
l ₂ O ₃ molar ratio = 4.6, trade name: SK-40, manufactured by Union Carbide Co.) (Example 7): Li-exchanged Y-type zeolite (SiO ₂ / A)
Tosoh Y-type zeolite having a molar ratio of l ₂ O _{3 of} 5.5 was used after Li ion exchange) (Example 8): K-exchanged X-type zeolite (SiO ₂ / Al ₂ O ₃ manufactured by Union Showa Co., Ltd.) X-type zeolite having a molar ratio of 2.4 was used after K ion exchange) (Example 9): K-exchanged L-type zeolite (SiO ₂ / Al)
₂ O ₃ molar ratio = 5.4, trade name SK-45, union
Carbite Co., Ltd.) (Example 10): Na-exchanged X-type zeolite (SiO ₂ /
Al ₂ O ₃ molar ratio = 2.4, trade name: 13X, manufactured by Union Showa Co.) The reaction mixture after 5 hours of reaction was analyzed by gas chromatography as in Example 1. The results are shown in Table 2.

[0027]

[Table 2]

Example 11 The same procedure as in Example 1 was repeated except that ethanol was used as a raw material alcohol, 250 g of a raw material consisting of ethanol and ethylene carbonate (molar ratio of ethanol / ethylene carbonate = 4) was used, and the reaction temperature was 70 ° C. The reaction was carried out in the same manner, and the reaction mixture at 5 hours after the reaction was similarly analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate into diethyl carbonate was 6.4%, the concentration of diethyl carbonate was 2.8% by weight, and the concentration of ethylene glycol was 1.5% by weight.

Example 12 Commercially available catalysts having a SiO ₂ / Al ₂ O ₃ molar ratio of 2 K
8 g of dried powder of exchanged A-type zeolite (trade name: 3A, manufactured by Union Showa Co., Ltd.) and 200 g of a raw material composed of n-propanol and ethylene carbonate (n-propanol / ethylene carbonate molar ratio = 4)
Was supplied to an autoclave equipped with a stirrer and having a capacity of 300 ml, and the reaction was carried out under the conditions of a temperature of 100 ° C., a pressure of 1.5 kg / cm ² G and a stirrer rotation speed of 800 rpm. The reaction mixture at 4 hours after the reaction was analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate into dipropylene carbonate was 2.0%.

Examples 13 to 15 As a catalyst, a Na-exchanged A-type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2 (trade name: 4A, manufactured by Union Showa Co.)
With potassium nitrate, and K ion is 5 as shown in Table 3.
After ion exchange of 0% or more, dry treatment is performed and K ion becomes 50
% Or more, the rest is ion-exchanged with Na ions K / N
An a-exchanged A-type zeolite was prepared. Catalytic reaction was carried out in the same manner as in Example 1 except that 10 g of each obtained zeolite powder catalyst was used as a catalyst and 250 g of a raw material (methanol / ethylene carbonate molar ratio = 4) consisting of methanol and ethylene carbonate was supplied. The reaction mixture after 5 hours of reaction was analyzed by gas chromatography. The results are shown in Table 3.

[0031]

[Table 3]

Example 16 The commercially available SiO ₂ / Al ₂ O ₃ K-exchanged A-type zeolite having a molar ratio of 2 used in Example 12 was further ion-exchanged with K ions to be used as a catalyst, and methanol / ethylene carbonate mol Except that the reaction raw material mixture having a ratio of 2 was 250 g, the reaction temperature was 100 ° C., and the pressure was 3.5 kg / cm ² G.
Reaction was carried out in the same manner as in Example 12. The reaction mixture at 4 hours after the reaction was analyzed by gas chromatography. as a result,
The conversion rate of ethylene carbonate was 35.7%, the concentration of dimethyl carbonate was 21.1% by weight, and the concentration of ethylene glycol was 13.8% by weight.

Example 17 A reaction was carried out in the same manner as in Example 16 except that 250 g of a reaction raw material mixture having a methanol / ethylene carbonate molar ratio of 8 was used. The reaction mixture at 2 hours after the reaction was analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate was 68.4%, and the concentration of dimethyl carbonate was 1
The concentration was 7.9% by weight, and the concentration of ethylene glycol was 13.5% by weight.

Example 18 250 g of a reaction raw material mixture having a methanol / ethylene carbonate molar ratio of 4 was used, the reaction temperature was 160 ° C., and the pressure was 1
The reaction was performed in the same manner as in Example 16 except that the amount was 3.5 kg / cm ² G. The reaction mixture at 2 hours after the reaction was analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate was 50.8%, and the concentration of dimethyl carbonate was 2%.
The concentration was 1.8% by weight and the concentration of ethylene glycol was 15.9% by weight.

Example 19 The Na-exchanged A-type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of 2 used as the catalyst in Example 13 was subjected to Rb ion exchange with rubidium acetate, dried and calcined at 450 ° C. R
A b / Na-exchanged A-type zeolite was obtained. Rb / N obtained
Using 10 g of a-exchanged A-type zeolite as a catalyst, 250 g of a raw material mixture having a molar ratio of methanol and ethylene carbonate of 4 was supplied to an autoclave having a capacity of 300 ml equipped with a stirrer, and the temperature was 100 ° C. and the pressure was 3.5 kg / c.
The reaction was carried out under the conditions of m ² G and a stirrer rotation speed of 800 rpm. The reaction mixture at 2 hours after the reaction was analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate was 42.0%, the concentration of dimethyl carbonate was 17.7% by weight, and the concentration of ethylene glycol was 12.2% by weight.

Example 20 Cs / N using cesium acetate instead of rubidium acetate
The reaction was carried out in exactly the same manner as in Example 19 except that a-exchanged A-type zeolite was prepared and used as a catalyst. The reaction mixture at 2 hours after the reaction was analyzed by gas chromatography. As a result, the conversion rate of ethylene carbonate was 37.7%, the concentration of dimethyl carbonate was 15.7% by weight, and the concentration of ethylene glycol was 10.8% by weight.

As is clear from the above Examples and Comparative Examples, in the reaction of ethylene carbonate, which is one kind of cyclic carbonate, with methanol, when the previously proposed ammonium-exchanged zeolite was used as a catalyst, the reaction temperature was 50 ° C. It can be seen that the reaction does not proceed. On the other hand, when the alkali metal and alkaline earth metal ion-exchanged zeolite of the present invention is used as a catalyst, the reaction with ethylene carbonate proceeds even at 50 ° C., although it varies depending on the kind of alcohol such as carbon number. Also, it can be seen that the ethylene carbonate conversion rate increases by increasing the reaction temperature. Furthermore, when an alkali metal or alkaline earth metal ion-exchanged zeolite is used as a catalyst, the ethylene carbonate conversion rate depends on the SiO ₂ / Al ₂ O ₃ molar ratio and the type of alkali metal or alkaline earth metal to be ion-exchanged. It can be seen that the catalyst activity changes and that the zeolite catalyst exchanged with K and / or Na ions of alkali metal using A-type zeolite has high catalytic activity.

[0038]

INDUSTRIAL APPLICABILITY The present invention uses an ion-exchanged zeolite, which has high heat resistance and high organic solvent resistance and is inexpensive, as a catalyst in the method of reacting an alcohol with a cyclic carbonate to convert it into a dialkyl carbonate and an alkylene glycol. The catalyst active sites can be made to exist uniformly, and since the alkali metal and / or alkaline earth metal is used as the ion exchange metal, the catalyst is non-volatile, and the catalyst activity is high even at reaction conditions, especially at a high temperature of 100 ° C. or higher. Stabilize. In particular, potassium (K) -substituted A type or X
When the type zeolite is used as a catalyst, the dialkyl carbonate can be obtained in a high concentration at a higher reaction conversion rate, which is industrially useful.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumiaki Tanaka, Inventor Fumiaki Tanaka, 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kako Construction Co., Ltd. Chome 12-1 Chiyoda Kako Construction Co., Ltd. (72) Inventor Susumu Yamamoto 2-12-1 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kako Construction Co., Ltd.

Claims (6)

[Claims] 1. A liquid phase reaction of an alcohol compound and a cyclic carbonate at a reaction temperature of 20 to 200 ° C. in the presence of an ion-exchanged zeolite ion-exchanged with an alkali metal ion and / or an alkaline earth metal ion. And a method for producing a dialkyl carbonate. 2. The SiO ₂ / Al ₂ O _{3 of the} zeolite
The method for producing a dialkyl carbonate according to claim 1, wherein the molar ratio is 2 to 6. 3. The method for producing a dialkyl carbonate according to claim 1, wherein the zeolite has an A structure or an X structure, and the SiO ₂ / Al ₂ O ₃ molar ratio is 2 to 3. 4. The method for producing a dialkyl carbonate according to claim 1, 2 or 3, wherein the molar ratio of the alcohol to the cyclic carbonate is 2 to 20. 5. The method for producing a dialkyl carbonate according to claim 1, wherein the reaction temperature is 100 ° C. or higher. 6. 50% or more of the ion exchange sites of the ion exchange zeolite are occupied by potassium ions, and the remaining ion exchange sites are occupied by other alkali metal ions and / or alkaline earth metal ions. The method for producing a dialkyl carbonate according to claim 1.