JP5458352B2 - Method for producing carbonate ester - Google Patents

Description

  The present invention relates to a method for producing a carbonate ester by reacting a monohydric alcohol and carbon dioxide in the presence of a solid catalyst.

Carbonate ester is a general term for compounds in which one or two of hydrogen atoms of carbon dioxide CO (OH) ₂ is substituted with an alkyl group or an aryl group, and RO-C (= O) -OR '( R and R ′ each represents a saturated hydrocarbon group or an unsaturated hydrocarbon group).

  Carbonate esters are used as additives such as gasoline additives to improve octane number and diesel fuel additives to reduce particles in exhaust gas, as well as resins and organic compounds such as polycarbonate, urethane, pharmaceuticals and agricultural chemicals. It is an extremely useful compound such as an alkylating agent, a carbonylating agent, a solvent, or the like, or a lithium battery electrolyte, a lubricating oil raw material, or a raw material for an oxygen scavenger for rust prevention of boiler piping.

  As a conventional method for producing a carbonate ester, a method in which phosgene is directly reacted with an alcohol using a carbonyl source is the mainstream. This method uses phosgene, which is extremely harmful and highly corrosive, and therefore requires extreme care in handling such as transportation and storage, and it costs a great deal of money to maintain and maintain manufacturing facilities and ensure safety. It was. Moreover, when manufacturing by this method, halogens, such as chlorine, are contained in a raw material and a catalyst, The trace amount halogen which cannot be removed by a simple refinement | purification process is contained in the carbonate ester obtained. In applications for gasoline additives, light oil additives, and electronic materials, there are also concerns that cause corrosion, and therefore a thorough refining process to make trace amounts of halogens extremely small is essential. Furthermore, since phosgene, which is extremely harmful to the human body, has been used recently, administrative guidance has been tightened, such as the establishment of a new production facility for this production method is not permitted, and a new production method that does not use phosgene is strongly desired. It is rare.

  Under these circumstances, as described in Non-Patent Document 1, as a method for producing a carbonate ester without using phosgene, a carbonic acid ester is reacted with ethylene oxide to synthesize a cyclic carbonate, and further reacted with methanol to form dimethyl carbonate. A method for obtaining the above has been put into practical use. This method uses environmentally friendly corrosive substances such as hydrochloric acid, is rarely generated, and can be expected to have a reduction effect by incorporating carbon dioxide, which is required to be reduced as a global warming gas, into the skeleton. However, as described in Patent Document 1, effective utilization of by-produced ethylene glycol is a major problem, and ethylene, which is a raw material of ethylene oxide, and safe transport of ethylene oxide are difficult. Therefore, there is a limitation that a carbonate ester production process plant must be located adjacent to the ethylene and ethylene oxide production process plant.

Further, as described in Patent Document 2, a method for producing dimethyl carbonate by oxidizing methanol and carbon monoxide in a liquid phase in the presence of a cuprous chloride catalyst is also disclosed. However, in this method, carbon monoxide harmful to the human body is handled, and, as in the production method using phosgene, a halogen purification step from the obtained carbonic acid ester is essential by including halogen in the catalyst. Problems such as CO ₂ being generated as a by-product have been pointed out.

  Furthermore, as described in Non-Patent Document 2, a method for producing dimethyl carbonate from methyl nitrite and carbon monoxide in the presence of a Pd—Cu-based catalyst has been put into practical use. In this method, methyl nitrite, which is a raw material, is supplied by reacting methanol and oxygen with nitric oxide by-produced during the production of dimethyl carbonate. There are issues such as handling harmful carbon monoxide.

  On the other hand, attempts have been made to directly synthesize carbonate esters by reacting methanol and carbon dioxide in the presence of a solid catalyst (Non-patent Document 3). However, although this reaction is an equilibrium reaction, since the equilibrium is largely biased toward the raw material system, the methanol conversion rate remains at most about 1%, and there is a major problem to be overcome that the reaction rate and productivity are low.

In order to solve the problem, an attempt was made to remove the reaction restriction by removing water by-produced with carbonate ester (dimethyl carbonate) out of the system. For example, acetal (Non-patent Document 4) as a hydrating agent together with a catalyst, Although research using 2,2-dimethoxypropane (Non-Patent Document 5) has been reported, it has a characteristic that the reaction proceeds as the reaction pressure increases, and the reaction yield is very low at low pressure, and extremely high pressure. Otherwise, high productivity cannot be obtained. This is because the hydration reaction of acetal and 2,2-dimethoxypropane is expected to proceed without being catalyzed in the liquid phase, so the reaction rate of the direct synthesis reaction of dimethyl carbonate is not dependent on CO ₂ pressure. It is presumed to determine the overall reaction rate, but because the methanol conversion rate increases at high pressures of 300 atm (30 MPa) and 60 atm (6 MPa), respectively, the motive energy required for the pressurization is very large. There was a problem that energy efficiency became worse.

  In addition, research using molecular sieves (solid dehydrating agent) (Non-patent Document 6) has been reported, but it is a process that separates and circulates the reaction part (high pressure) and the dehydration part (normal pressure). There was a problem that consumption was large and a large amount of solid dehydrating agent was required.

Solid catalysts used for the direct synthesis reaction of carbonate ester have so far been tin compounds such as dimethoxydibutyltin, thallium compounds such as thallium methoxide, nickel compounds such as nickel acetate, vanadium pentoxide, potassium carbonate and other alkaline carbonates. Various compounds such as salts and Cu / SiO ₂ have been studied.

  On the other hand, as a reaction using acetonitrile as a wettable powder, research on a reaction system for directly synthesizing a cyclic carbonate (propylene carbonate) from propylene glycol and carbon dioxide as a dihydric alcohol in the presence of a solid catalyst has been reported ( Non-patent document 7). However, even in this reaction system, the influence of the reaction pressure is significant, and the reaction proceeds as the reaction pressure increases. The reaction yield is extremely low at low pressure, but the direct synthesis reaction of cyclic carbonate is balanced. In particular, it was confirmed that the yield increased at a particularly advantageous high pressure, and the reaction pressure was preferably 100 atm or more, and there was a problem that the energy efficiency was deteriorated as described above.

WO2004 / 014840 Publication EP365,083

Chemical Engineering, Vol. 68, No. 1, p. 41 (2004) Catalyst, vol.36, p.127 (1994) Catal. Lett., Vol.58 (1999) Polyhedron, vol.19, p.573 (2000) Appl. Catal. A Gen, vol.237, p.103 (2002) ECO INDUSTRY, vol.6, p.11 (2001) Catalysts Letters, vol.112, p.187 (2006)

  In view of the above-mentioned problems of the prior art, the present invention provides a high reaction rate even under mild reaction conditions where the pressure is relatively low when alcohol and carbon dioxide are reacted in the presence of a solid catalyst to directly synthesize carbonate esters. It is an object of the present invention to provide a method for producing a carbonic acid ester that makes it possible.

  The inventors of the present invention focused on a method of directly synthesizing a carbonate ester from a monohydric alcohol and carbon dioxide in the production of the carbonate ester, and acetonitrile is used as a wettable powder to remove water by-produced together with the carbonate ester out of the system. Thus, for the first time, the inventors have found the effect that the reaction is accelerated under a pressure close to normal pressure without requiring high pressure such as 300 atmospheric pressure and 60 atmospheric pressure as described in Non-Patent Documents 4 and 5, and Japanese Patent Application No. 2007-286439 Has applied for a patent. However, when acetonitrile is used as a wettable powder, by-products such as acetamide are formed and their use is also limited, so the present inventors have further advanced studies on the types of wettable powder. However, by adopting benzonitrile as a wettable powder, as in the case of acetonitrile, there is a phenomenon that the reaction proceeds more under the pressure of the reaction system close to normal pressure, and the types of by-products are also increased. Found less. Further, benzamide itself, which is a main by-product, has been found to have many uses, and has led to the invention.

  In addition, as a solid catalyst, the inventors have intensively studied focusing on the elements and composition constituting the catalyst. As a result, a solid catalyst having an acid-base complex function having a relatively low acidity and a relatively high basicity has Is used, the reaction to produce benzamide by hydration reaction in the presence of a solid catalyst is promoted, the dehydration from the reaction system proceeds efficiently, and the carbonic acid is not subject to reaction equilibrium constraints even under mild conditions of relatively low pressure. It has been found that the ester can be obtained in high yield. Further, among these, cerium oxide, zirconium oxide, and one or more oxides selected from the group consisting of compounds of cerium oxide and zirconium oxide were found to be very effective, leading to the present invention. .

The features of the present invention will be described below.
(1) in the presence of a solid catalyst and benzonitrile, a monohydric alcohol and carbon dioxide are reacted at a reaction pressure of 0.04～5MPa, method for producing a carbonic ester, which comprises producing a carbonic ester It is. Also,
(2) In the presence of a solid catalyst and benzonitrile, a monohydric alcohol and carbon dioxide are reacted at a reaction pressure of 0.04 to 5 MPa to produce a carbonate and water, and the benzonitrile and the production. A method for producing a carbonate ester, comprising generating benzamide by hydration reaction with water and removing or reducing the generated water from a reaction system to promote the production of the carbonate ester. Also,
(3) The solid catalyst is composed of one or more selected from the group consisting of cerium oxide, zirconium oxide, and a compound of cerium oxide and zirconium oxide. (1) or (2) It is a manufacturing method of the carbonate ester of description. Also,
(4) The method for producing a carbonate ester according to any one of (1) to (3), wherein the monohydric alcohol is methanol and dimethyl carbonate is produced as a carbonate ester. Also ,
(5 ) The method for producing a carbonate ester according to any one of (1) to (4), wherein the pressure during the reaction is 3 MPa or less. Also,
( 6 ) The method for producing a carbonate ester according to any one of (1) to (4), wherein the pressure during the reaction is 0.1 to 1 MPa.
(7) The method for producing a carbonate ester according to any one of (1) to (6), wherein a temperature during the reaction is 50 to 300 ° C.

  According to the present invention, a monohydric alcohol and carbon dioxide can be reacted under mild conditions at a relatively low pressure to obtain a carbonate ester with a high reaction rate.

Hereinafter, the present invention will be described in more detail with reference to specific examples.
In the method for producing a carbonate ester of the present invention, a carbonate ester is produced by directly reacting a monohydric alcohol and carbon dioxide in the presence of a solid catalyst and benzonitrile. As shown in the following reaction formula I (in the reaction formula I, the case where methanol is used as the monohydric alcohol will be described as an example), when the monohydric alcohol and carbon dioxide are reacted, water is generated in addition to the carbonate ester. The presence of the nitrile makes it possible to generate benzamide by hydration reaction with the generated water, and to remove or reduce the generated water from the reaction system, thereby promoting the formation of carbonate ester.

  Here, as a monohydric alcohol, the 1 type, or 2 or more types of alcohol chosen from the group which consists of a primary alcohol, a secondary alcohol, and a tertiary alcohol can be used.

The solid catalyst may be a conventionally studied catalyst such as a tin compound, a thallium compound, a nickel compound, a vanadium compound, Cu / SiO ₂ , or an alkali carbonate, and in particular, cerium oxide, zirconium oxide, and cerium oxide. What consists of 1 type, or 2 or more types selected from the group which consists of a compound with a zirconium oxide is suitable.

As a result of intensive studies by the present inventors, the catalyst used for the direct synthesis of carbonic acid ester is required to have an acid-base complex function, and in particular, has a property of relatively low acidity and relatively high basicity. Is preferred. If the acidity is too high, a large amount of ether is synthesized rather than carbonate, which is not preferable. In the moderate acid base complex function catalyst, ROM on basic point (M catalyst) alcohol dissociates adsorbed in the form of a RO-C (= O) -O ... M formed between the CO ₂ On the other hand, on the acidic point, alcohol is adsorbed in the form of HO—R...

Next, a measurement method relating to acidity and basicity of a relatively low acidity and a relatively high basicity desirable as a catalyst of the present reaction system will be described below. In general, the acidity is measured by exposing the target compound to NH ₃ atmosphere in the process of lowering the temperature at room temperature or after pretreatment to adsorb NH ₃ and then increasing the temperature called TPD (temperature controlled desorption) method at a constant rate. It can be measured by quantifying the amount of NH ₃ desorbed when heated. On the other hand, the basicity can be generally measured by using CO ₂ instead of NH ₃ used in the acidity measurement method and quantifying the amount of CO ₂ desorbed by TPD. As a compound having a relatively low acidity and a relatively high basicity that can be measured in this manner, solid catalysts of various metal salts such as tin oxide, titanium oxide, and nickel oxide are suitable. And those composed of one or more selected from the group consisting of cerium oxide, zirconium oxide, and a compound of cerium oxide and zirconium oxide, which are considered to have the most balanced basicity. .

Although the mechanism of this solid catalyst is not clear, it exhibits catalytic activity for the synthesis of carbonic acid ester by the reaction of monohydric alcohol and carbon dioxide, and hydrates water and benzonitrile by-produced during carbonic acid ester synthesis. It seems that it also shows catalytic activity. Therefore, although both carbonate synthesis reaction and hydration reaction proceed on the surface of this catalyst, the hydration reaction of benzonitrile does not occur even under low pressure conditions, which is unfavorably balanced for the synthesis reaction of carbonate ester. The reaction proceeds under catalysis, and water generated as a by-product in the synthesis reaction of the carbonate ester is quickly eliminated from the catalyst surface, so that the equilibrium of the synthesis reaction of the carbonate ester shifts to the production system, and the mild reaction pressure is low. It is presumed that the carbonic acid ester synthesis reaction enables a high reaction rate of the carbonic acid ester without being subjected to equilibrium constraints even under conditions. On the other hand, under high pressure, a large amount of CO ₂ molecules are adsorbed on the catalyst surface, making it difficult to contact with water molecules generated during carbonic acid ester synthesis, making it difficult for the hydration reaction with benzonitrile to proceed. Carbonic acid ester can only be produced under conditions close to equilibrium constraints, and as a result, it is considered that productivity does not increase under high pressure.

Regarding the above inference, from the viewpoint of the reaction of benzonitrile, benzonitrile is catalyzed by the solid catalyst in the present invention in the liquid phase, and the hydration reaction is promoted on the surface thereof. Therefore, when the pressure becomes high, the surface of the solid catalyst is covered with CO ₂ , and it becomes difficult to be catalyzed to the hydration reaction with the water molecules generated in the main reaction, so the hydration reaction rate decreases. Inferred. On the other hand, acetals and 2,2-dimethoxypropane described in Non-Patent Documents 4 and 5 do not undergo any catalytic action in the liquid phase, and cause hydration reaction with water molecules generated in the main reaction. Therefore, since the main reaction proceeds predominantly at high pressure, it is presumed that the hydration reaction begins to occur under high pressure.

As for the production method of the solid catalyst in the present invention, for example, first, in the case of cerium oxide (CeO ₂ ), cerium acetylacetonate hydrate, cerium hydroxide, cerium sulfate, cerium acetate, nitric acid It can be prepared by firing various cerium compounds such as cerium, ammonium nitrate, cerium carbonate, cerium oxalate, cerium perchlorate, cerium phosphate and cerium stearate in an air atmosphere. Moreover, when using cerium oxide of a commercially available reagent, it can be used as it is or by drying or baking in an air atmosphere. Furthermore, it can be used by precipitating from a solution in which cerium is dissolved, filtering, drying, and baking. On the other hand, in the case of zirconium oxide (ZrO ₂ ), various zirconium compounds such as zirconium ethoxide, zirconium butoxide, zirconium carbonate, zirconium hydroxide, zirconium phosphate, zirconium acetate, zirconium chloride oxide, zirconium oxide nitrate, zirconium sulfate, etc. It can be prepared by firing in an atmosphere. In addition, when a commercially available reagent, zirconium oxide, is used, it can be used as it is or by drying or baking in an air atmosphere. Furthermore, it can be used by precipitating from a solution in which zirconium is dissolved, filtering, drying and baking.

In the case of a compound of cerium oxide and zirconium oxide, a base is added to a solution containing cerium and zirconium to form a hydroxide by coprecipitation, followed by filtration and washing, and drying and firing in an air atmosphere Can be prepared. Moreover, although it can prepare also by physically mixing and baking the powder of cerium oxide and zirconium oxide, since the specific surface area of a final preparation does not become high, the coprecipitation method with which reaction progresses more is preferable. Specifically, a solid catalyst comprising a compound of cerium oxide and zirconium oxide such as CeO ₂ —ZrO ₂ can be obtained by these methods. In addition, including the case of preparing a catalyst made of cerium oxide or a catalyst made of zirconium oxide, it is preferable to select a temperature at which the specific surface area of the final preparation is increased as the firing temperature at the time of preparation of each catalyst. Although it depends on the raw material, for example, 300 ° C. to 1100 ° C. is preferable. Further, the solid catalyst according to the present invention may contain inevitable impurities mixed in the catalyst production process in addition to the above elements, but it is desirable that impurities are not mixed as much as possible.

  Here, the catalyst of the present invention may be in any form of powder or molded body, and in the case of a molded body, it may be any of spherical, pellet, cylinder, ring, wheel, granule, etc. .

  Moreover, the carbon dioxide used in the present invention is not limited to those prepared as industrial gases, but can also be used that separated and recovered from exhaust gases from factories, steel mills, power plants, etc. that manufacture each product.

  Next, the direct synthesis reaction of the carbonate ester using the solid catalyst of the present invention is not particularly limited with respect to the reactor and reaction form to be used, for example, a batch reactor, a semi-batch reactor, a continuous tank reactor, a tube Any flow reactor such as a type reactor may be used.

  The reaction temperature is preferably 50 to 300 ° C. When the reaction temperature is less than 50 ° C., the reaction rate is low, the carbonate ester synthesis reaction and the hydration reaction with benzonitrile hardly proceed, and the carbonate ester productivity is low. In addition, when the reaction temperature exceeds 300 ° C., the reaction rate of each reaction is increased, but the amide monomer obtained by the carbonate ester or hydration reaction is easily modified to other monomers or polymerized. The yield of carbonate ester is low. More preferably, it is 100-300 degreeC. However, since this temperature is considered to vary depending on the type and amount of the solid catalyst and the amount and ratio of the raw materials (monohydric alcohol and benzonitrile), it is desirable to set optimum conditions as appropriate.

  The reaction pressure is preferably 0.1 to 5 MPa (absolute pressure). When the reaction pressure is less than 0.1 MPa (absolute pressure), a pressure reducing device is required, which not only makes the equipment complicated and expensive, but also requires kinetic energy for reducing the pressure, resulting in poor energy efficiency. On the other hand, when the reaction pressure exceeds 5 MPa, the hydration reaction by benzonitrile does not proceed easily and the yield of the carbonate ester is deteriorated, and the kinetic energy necessary for pressurization is required, resulting in poor energy efficiency. Further, from the viewpoint of increasing the yield of carbonate ester, the reaction pressure is more preferably 0.1 to 3 MPa (absolute pressure), and further preferably 0.1 to 1 MPa (absolute pressure).

  Furthermore, in this hydration reaction with benzonitrile, benzamide is by-produced. Further, benzamide reacts with the raw material monohydric alcohol to produce a benzoic acid compound as a by-product. Benzamide is generally known to be frequently used for pharmaceutical applications such as nervous system agents and agrochemical applications such as herbicides. Among benzoic acid compounds, methyl benzoate, in particular, is used for fragrances and for preserving pharmaceuticals and cosmetics. Widely used in drug applications. In order to isolate the target carbonate ester from these, a distillation operation utilizing the difference in boiling points of the respective compounds is preferably used, but other methods may be used. Regarding the reaction time, it is desirable to set optimal conditions as appropriate.

  The benzonitrile used for the hydration reaction is desirably introduced into the reactor in advance before the reaction at 0.5 to 5 times the volume of the starting alcohol. When it is introduced at less than 0.5 times, the yield of carbonate ester may be deteriorated because the amount of benzonitrile contributing to the hydration reaction is small. On the other hand, if it is introduced more than 5 times, it will be difficult to separate the product carbonate ester from the large amount of benzonitrile that was not involved in the reaction after the completion of the reaction, or add more than necessary. Is not economical. Furthermore, the amount of monohydric alcohol and benzonitrile with respect to the solid catalyst is considered to vary depending on the type and amount of the solid catalyst, the type of monohydric alcohol and the ratio with benzonitrile, and therefore it is desirable to appropriately set optimum conditions.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Example 1)
Cerium oxide (manufactured by the first rare element: impurity concentration of 0.02% or less) was calcined at 873 K in an air atmosphere for 3 hours to obtain a powdered solid catalyst. Therefore, a magnetic stir bar, the above solid catalyst (1 mmol), methanol (100 mmol) and benzonitrile (100 mmol) were introduced into a 190 ml autoclave (reactor), and the air in the autoclave was purged three times with about 5 g of CO ₂ . Thereafter, CO ₂ was introduced so that the pressure shown in Table 1 was reached, the autoclave was heated to 423 K with a band heater and a hot stirrer, and the time when the target temperature was reached was defined as the reaction start time. Then, after reacting at 423 K for 2 hours, the autoclave was cooled with water, and after cooling to room temperature, the pressure was reduced and 2-propanol as an internal standard substance was added, and the product was collected and analyzed by GC (gas chromatography). In this way, experiments No. 1 to No. 7 shown in Table 1 were performed by changing the reaction pressure (introduction amount of CO ₂ ).

  From the above results, it was confirmed that a large amount of dimethyl carbonate (DMC) was produced under a relatively low pressure, and a high yield was obtained. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments No. 1-7.

(Example 2)
In the same manner as in Example 1 except that the amount of benzonitrile (BN) is as shown in Table 2 below, 40 mmol of CO ₂ was introduced so that the reaction pressure became 0.5 MPa, and then the reaction was performed at 423 K for 2 hours. went. The results are shown in Table 2.

  From the above results, it was confirmed that the production amount of dimethyl carbonate increased with the addition amount of benzonitrile, but the production amount of dimethyl carbonate decreased conversely when the addition amount of benzonitrile was 300 mmol or more. This is thought to be because the reaction did not proceed easily because the reaction raw material was diluted by adding too much benzonitrile. The amount of by-product benzamide produced is almost the same as that of DMC, and other by-products produced no more than 0.1-0.2 mmol methyl benzoate in Nos. 8, 10 and 12. It was.

Example 3
The reaction temperature is shown in Table 3 below. Each reaction was carried out in the same manner as in Example 1 except that methanol (100 mmol) and benzonitrile (200 mmol) were introduced, and 80 mmol of CO ₂ was introduced so that the reaction pressure became 1 MPa. The reaction was carried out at temperature for 12 hours. The results are shown in Table 3.

  From the above results, the reaction rate increased with increasing temperature under the present conditions, but the reaction rate decreased when exceeding 443K. Therefore, it was confirmed that the yield of dimethyl carbonate was obtained at the highest yield around 423K. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments Nos. 13-16.

Example 4
In the same manner as in Example 3, except that 0.05 g (0.3 mmol) of cerium oxide as a solid catalyst was used and the reaction time was as shown in Table 4 below, 80 mmol of CO ₂ was introduced so that the reaction pressure became 1 MPa. Then, the reaction was performed at 423K. The results are shown in Table 4.

  From the above results, it was confirmed that, under the present conditions, the amount of dimethyl carbonate produced increased with the reaction time, but became almost constant after 20 hours, and almost completed after 20 hours. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments of Nos. 17-22.

(Example 5)
In the same manner as in Example 3 except that 0.17 g (1 mmol) of cerium oxide as a solid catalyst was used and the reaction time was as shown in Table 5 below, 80 mmol of CO ₂ was introduced so that the reaction pressure became 1 MPa. Thereafter, the reaction was performed at 423K. The results are shown in Table 5.

  From the above results, it was suggested that the production amount of dimethyl carbonate continued to increase with the reaction time under this condition, and the reaction still progressed after 24 hours. The amount of benzamide produced as a by-product is almost the same as that of DMC, and other by-products produced methyl benzoate in a slight amount of about 0.1 to 0.2 mmol in No. 24-28. It was done.

Example 6
In the same manner as in Example 3 except that 0.51 g (3 mmol) of cerium oxide as a solid catalyst was used and the reaction time was as shown in Table 6 below, 80 mmol of CO ₂ was introduced so that the reaction pressure became 1 MPa. Thereafter, the reaction was performed at 423K. The results are shown in Table 6.

  From the above results, it was confirmed that, under these conditions, the amount of dimethyl carbonate produced increased with the reaction time, but became almost constant after 12 hours, and the reaction was almost completed after 12 hours. The amount of by-product benzamide produced is almost the same as that of DMC, and other by-products produced methyl benzoate in a very small amount of about 0.1 to 0.2 mmol in the experiments of No. 31 to 34. It was done.

(Example 7)
Experiments Nos. 35 to 44 shown in Table 7 were carried out in the same manner as in Example 1 except that 200 mmol of benzonitrile was used and the CO ₂ introduction amount and the reaction pressure were changed.

  From the above results, it was confirmed that a large amount of dimethyl carbonate (DMC) was produced under a relatively low pressure, and a high yield was obtained. The amount of by-product benzamide produced was almost the same as that of DMC, and other by-products were hardly detected in the experiments of Nos. 35 to 44.

(Example 8)
Using 0.17 g (1 mmol) of solid catalyst cerium oxide, methanol (200 mmol) and benzonitrile (400 mmol) were introduced, and 16 mmol of CO ₂ was introduced so that the reaction pressure became 0.2 MPa. The reaction was carried out at each reaction time as shown in Table 8. The results are shown in Table 8.

  From the above results, it was confirmed that, under these conditions, the amount of dimethyl carbonate produced increased with the reaction time, but became almost constant after 8 hours, and the reaction was almost completed after 8 hours. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the No. 45-50 experiments.

Example 9
The reaction was carried out at 423 K for each reaction time as shown in Table 9 below, except that 8 mmol of CO ₂ was introduced so that the reaction pressure became 0.1 MPa. The results are shown in Table 9.

From the above results, it was confirmed that, under these conditions, the amount of dimethyl carbonate produced increased with the reaction time, but became almost constant after 12 hours, and the reaction was almost completed after 12 hours. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments Nos. 51-56. In particular, it was found that the CO ₂ conversion rate determined from the amount of DMC produced after 24 hours had actually reached 70%.

Example 10
Table 1 shows the reaction pressure and the amount of CO ₂ using 1 mmol of a powdered solid catalyst obtained by calcining zirconium oxide (manufactured by Nacalai Tesque: impurity concentration 0.08% or less) at 673 K in an air atmosphere for 3 hours. The experiment was performed in the same manner as in Example 1 except that. In this case, the reaction was carried out at a reaction temperature of 443 K for 2 hours. The results are shown in Table 10.

  From the above results, it was confirmed that the lower the pressure, the greater the amount of DMC produced and the higher the yield. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments of Nos. 57-58.

Example 11
Sodium hydroxide was introduced into a solution in which cerium nitrate and zirconium nitrate were dissolved so that the cerium content was 20 atomic% to form a precipitate. The precipitate was filtered, washed with water, and then in an air atmosphere at 1273K. Calcination was performed for 3 hours to obtain a powdery solid catalyst. An experiment was conducted in the same manner as in Example 1 except that 1 mmol of this solid catalyst was used and the reaction pressure and CO ₂ amount were as shown in Table 11. In this case, the reaction was carried out at a reaction temperature of 443K for 2 hours. The results are shown in Table 11.

  From the above results, it was confirmed that the lower the pressure, the greater the amount of DMC produced and the higher the yield. The amount of by-product benzamide produced was almost the same as that of DMC, and no other by-products were detected in the experiments Nos. 59-60.

(Example 12)
In the same manner as in Example 8, except that 0.17 g (1 mmol) of the solid catalyst cerium oxide was used and ethanol (200 mmol) was used instead of methanol, the amount of CO ₂ was adjusted so that the reaction pressure became 0.2 MPa. After introducing 16 mmol, the reaction was carried out at 423 K for each reaction time as shown in Table 12 below. The results are shown in Table 12.

  From the above results, it was suggested that diethyl carbonate (DEC) becomes almost constant under the present conditions when the reaction time is 2 hours or more, and the reaction proceeds very quickly. The amount of by-product benzamide produced was almost the same as that of DEC, and other by-products were not detected at all in the experiments Nos. 61-66.

(Example 13)
Experiments were conducted in the same manner as in Example 1 except that propanol (100 mmol) was used instead of methanol and the reaction pressure and CO ₂ amount were as shown in Table 13. The results are shown in Table 13.

  From the above results, it was confirmed that the amount of dipropyl carbonate (DPC) produced was higher as the pressure was lower, but not as high as dimethyl carbonate and diethyl carbonate. The amount of by-product benzamide produced was almost the same as that of DPC, and no other by-products were detected in the experiments of Nos. 67-68.

(Example 14)
An experiment was conducted in the same manner as in Example 1 except that isopropanol (100 mmol) was used instead of methanol and the reaction pressure and the amount of CO ₂ were as shown in Table 14. The results are shown in Table 14.

  From the above results, although not as much as dimethyl carbonate, diethyl carbonate, and dipropyl carbonate, it was confirmed that the amount of diisopropyl carbonate (DIPC) produced was higher at lower pressures and could be obtained in higher yields. The amount of by-product benzamide produced was almost the same as that of DIPC, and no other by-products were detected in the experiments Nos. 69-70.

(Example 15)
Experiments were conducted in the same manner as in Example 1 except that t-butyl alcohol (100 mmol) was used instead of methanol and the reaction pressure and CO ₂ amount were as shown in Table 15. The results are shown in Table 15.

  From the above results, it was confirmed that the amount of ditertiary butyl carbonate (DTBC) produced was higher as the pressure was lower, but not as high as that of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and diisopropyl carbonate. The amount of by-product benzamide produced was almost the same as that of DTBC, and no other by-products were detected in the experiments of Nos. 71-72.

(Comparative Example 1)
An experiment was conducted in the same manner as in Example 1 except that 0.51 g (3 mmol) of cerium oxide as a solid catalyst was used, benzonitrile was not used, and the reaction pressure and CO ₂ amount were as shown in Table 16. The results are shown in Table 16.

  From the above results, when benzonitrile was not used, the amount produced was very small due to the equilibrium restriction of the dimethyl carbonate direct synthesis reaction.

(Comparative Example 2)
An experiment was conducted in the same manner as in Example 1 except that 30 mmol of 2,2-dimethoxypropane was used in place of benzonitrile and the reaction pressure and CO ₂ amount were as shown in Table 17. The results are shown in Table 17.

  From the above results, the amount of DMC produced was low at low pressure, but it showed high production at a high pressure of 10 MPa.

  In the above examples, carbonate ester, benzamide in the same amount as carbonate by-product, and some methyl benzoate, etc. were produced, but by distillation, the target product carbonate ester and by-product Benzamide, which can be used as a raw material for pharmaceuticals and agricultural chemicals, could be recovered independently.

Further, in the above examples, the solid catalyst is described as being limited to cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), and a compound of cerium oxide and zirconium oxide (CeO ₂ -ZrO ₂ ). In the present invention in which is added as a wettable powder, even in the case of other solid catalysts, particularly solid catalysts having an acid-base complex function having a relatively low acidity and a relatively high basicity, Carbonate can be produced efficiently.

Claims (7)

In the presence of a solid catalyst and benzonitrile, a monohydric alcohol and carbon dioxide are reacted at a reaction pressure of 0.04～5MPa, method for producing a carbonic ester, which comprises producing a carbonic ester. In the presence of a solid catalyst and benzonitrile, a monohydric alcohol and carbon dioxide are reacted at a reaction pressure of 0.04 to 5 MPa to produce a carbonate and water, and the benzonitrile and the produced water A method for producing a carbonate ester, wherein benzamide is produced by a hydration reaction of and the production of the carbonate ester is promoted by removing or reducing the produced water from the reaction system.   3. The carbonate ester according to claim 1, wherein the solid catalyst comprises one or more selected from the group consisting of cerium oxide, zirconium oxide, and a compound of cerium oxide and zirconium oxide. Production method.   The said monohydric alcohol is methanol, and dimethyl carbonate is manufactured as carbonate ester, The manufacturing method of the carbonate ester of any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a carbonate ester according to any one of claims 1 to 4, wherein a pressure during the reaction is 3 MPa or less.   The method for producing a carbonate ester according to any one of claims 1 to 4, wherein the pressure during the reaction is 0.1 to 1 MPa. The temperature during the reaction is 50 to 300 ° C, The method for producing a carbonate ester according to any one of claims 1 to 6.