JP2016216363A - Method for producing carbonic acid ester and production device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing carbonic acid ester where monovalent alcohol and carbon dioxide are reacted in the presence of a solid catalyst and benzonitrile even if pressure lies in relatively low, mild reaction conditions to achieve the reaction of carboxylic acid ester at a high reaction speed and a high reaction rate, and further, by-produced benzamide is regenerated into benzonitrile and reutilized it, by-products are hardly generated other than water, and an environmental load is small.SOLUTION: There is provided a carbonic acid ester generation device containing: a first reaction step where monovalent alcohol and carbon dioxide are reacted in the presence of a solid catalyst and benzonitrile to generate carbonic acid ester and water and subsequently benzamide is generated by hydration reaction between the benzonitrile and the generated water; and a second reaction step where benzamide is separated from the first reaction step thereafter the benzamide is heated and is caused to dehydration reaction in the presence of a catalyst carried with a metal and also in the presence of an organic solvent so as to be regenerated into benzonitrile. The benzonitrile regenerated in the second reaction step is used in the first reaction step.SELECTED DRAWING: Figure 1

Description

  In the present invention, a carbonic acid ester is produced by reacting a monohydric alcohol and carbon dioxide in the presence of a solid catalyst and a wettable powder, and a by-product produced as a by-product by the reaction of water generated at that time with the wettable powder. The present invention relates to a method and an apparatus for producing a carbonate ester in which a living organism is returned to its original wettable powder and reused. In particular, the present invention relates to a method and an apparatus for producing a carbonic acid ester in which benzonitrile is used as a wettable powder and a by-product is benzamide.

Carbonic acid 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 represent a saturated hydrocarbon group, an unsaturated hydrocarbon group or an aromatic hydrocarbon group).

  Carbonate esters are used as additives for gasoline additives to improve octane number, diesel fuel additives for reducing particles in exhaust gas, etc., and also synthesize polycarbonate and urethane, resins and organic compounds such as 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 cyclic carbonate is synthesized by reacting carbon dioxide with a highly reactive ethylene oxide or the like, and further methanol. A method of obtaining dimethyl carbonate by reacting with benzene 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. It is a method. However, as described in Patent Document 1, effective utilization of by-produced ethylene glycol is a major issue, and since ethylene oxide as a raw material for ethylene oxide and safe transport of ethylene oxide are difficult, these ethylene There is also a restriction that a carbonate ester production process plant must be located adjacent to the 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 nitride and carbon monoxide in the presence of a Pd—Cu-based catalyst has been put into practical use. In this method, methyl nitride, which is a raw material, is supplied by reacting methanol and oxygen with nitric oxide produced as a by-product during the production of dimethyl carbonate, and the process is complicated. 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 (for example, Non-Patent Document 3). However, although this reaction is an equilibrium reaction, since the equilibrium is largely biased toward the raw material system, there was a major problem to be overcome that the methanol conversion rate remained at about 1% at most, and the reaction rate and productivity were low.

In order to solve the above-mentioned problems, an attempt has been made to remove the reaction restriction by removing water by-produced with carbonate (dimethyl carbonate) out of the system. For example, acetal as a wettable powder with a catalyst (Non-patent Document 4). , 2,2-dimethoxypropane (Non-patent Document 5) has been reported, but the reaction proceeds as the reaction pressure increases, and the reaction yield is very low at low pressure. Unless the pressure is high, 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 boosting 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 higher, and there was a problem that the energy efficiency was deteriorated as described above.

  The present inventors pay attention to a method of directly synthesizing a carbonate ester from monohydric alcohol and carbon dioxide using a heterogeneous catalyst in the production of carbonate ester, and remove water by-produced with the carbonate ester out of the system. By using acetonitrile and benzonitrile as a compatibilizer, it was found for the first time that the reaction is accelerated under a pressure close to normal pressure without requiring high pressure such as 30 or 60 atmospheres (see Patent Documents 4 and 5). . However, when acetonitrile is used as a wettable powder, by-products such as acetamide are produced, and their use is limited. By adopting benzonitrile as a wettable powder, it is the same as in the case of acetonitrile. In addition, it was found that the reaction proceeds more under the pressure of the reaction system close to normal pressure, and that there are few types of by-products.

International Publication No. 2004/014840 European Patent Application No. 365083 JP 2009-132673 A JP 2010-77113 A JP 2012-162523 A JP 2009-213975 A

Chemical engineering, 68 (1) (2004) 41 Catalyst, 36 (1994) 127 Catal. Lett., 58 (1999) Polyhedron, 19 (2000) 573 Appl. Catal. A Gen, 237 (2002) 103 Eco Industry, 6 (2001) 11 Catal. Lett., 112, (2006) 187 M.B.Smith, J.March, Adv.Org.Chem .: Reactions, Mechanism, and Structure 5th ed., John Wiley & Sons, New York, (2001) Misono Misasa, Saito Yasukazu, Catalytic Chemistry, Maruzen (1999) C.W.Kuo, et al., Chem. Commun., (2007) 301 S. Enthaler, Chem. Eur. J., 17 (2011) 9316

  The present inventor has further studied the types of wettable powder for further improvement in the production amount of carbonate ester. By using benzonitrile, the production amount and production rate of carbonate ester are reduced as compared with the case of acetonitrile. It was found that the reaction was greatly improved, the reaction was likely to proceed under a relatively low pressure close to normal pressure, and the reaction rate was very high (see Patent Document 4). However, the processing method and utilization method of by-product benzamide have not been studied.

  Nitriles such as benzonitrile as a wettable powder in the present invention are generally used in many applications such as solvents, synthetic resins, dyes, and pharmaceutical intermediates. Among them, benzonitrile is a substance used as a raw material for pharmaceuticals and agricultural chemicals, and is a substance used as a starting material when synthesizing various derivatives.

  However, the use of benzamide produced by the reaction of benzonitrile and water is limited to some medical and agrochemical intermediates. Therefore, in the production of carbonic acid esters using benzonitrile as a wettable powder, it is considered effective to regenerate the benzamide produced as a by-product into benzonitrile and reuse it. This regeneration reaction is highly selective (by-product). If this occurs, it may be difficult to reuse as a wettable powder), and the yield is high (if the yield is low, the residual amount of benzamide increases, the amount of separation treatment from benzonitrile increases, and the load increases. ) Turned out to be a challenge.

  In general, nucleophilic substitution reaction with inorganic cyanide is used as one of the methods for synthesizing nitriles, but there is a problem that toxic cyanide is used and halogen salts are by-produced (Non-patent Document 8). ).

  In addition, a gas phase reaction in which air is used as an oxidizing agent in the presence of ammonia using a Mo-Bi-based or Fe-Sn-based oxide catalyst in an ammoxidation method (SOHIO method) has been industrialized. A high reaction temperature of 400 ° C. or higher is required, and it is further limited to acrylonitrile and the like (Non-patent Document 9).

  On the other hand, there are nitrile syntheses by amide dehydration, and there are several reports of benzamide dehydration reactions, but since all use homogeneous catalysts, subsequent processes such as purification after synthesis and separation of the catalyst are complicated. Therefore, the use of a strong reagent (strong acid or strong base) and generation of a large amount of by-products cause a large environmental load (Non-Patent Documents 10 and 11).

  In addition, as a dehydration reaction of an amide using a heterogeneous catalyst, Patent Document 6 describes a catalyst for a dehydration reaction of a primary amide and a nitrile production method using the same. The catalyst is a solid catalyst with vanadium supported on hydrotalcite, and it is said that the primary amide is also active with aromatic amides such as benzamide, amides with heterocycles and aliphatic amides, but the reaction rate is slow. not enough. This is because the amide is generally more stable than the nitrile, and the dehydration reaction of the amide is slower, and the intramolecular hydrogen between the hydrogen atom of the amide group and the nitrogen heteroatom in the amide molecule. This is probably because amides have particularly large intramolecular hydrogen bonds, become stable substances, and are unlikely to undergo dehydration.

  As described above, a method for producing a carbonate ester, which comprises reacting a monohydric alcohol and carbon dioxide in the presence of a solid catalyst to synthesize a carbonate ester in a high yield and regenerate from the by-product benzamide to benzonitrile, and There have been no reports on devices.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to produce a carbonic acid ester directly by reacting alcohol and carbon dioxide in the presence of a solid catalyst and a hydrating agent benzonitrile. By reacting water with benzonitrile and removing it from the reaction system, the formation of carbonate ester is promoted. On the other hand, by-product benzamide is dehydrated to regenerate benzonitrile with high selectivity and high yield. Providing a method and an apparatus for producing a carbonate ester that is highly efficient as a whole of the above reaction system and has only a carbonate ester and by-product water as a product, and has only a small environmental impact, by reusing it as a compatibilizer. There is to do.

  The inventors of the present invention focused on a method of directly synthesizing carbonate ester from monohydric alcohol and carbon dioxide in the production of carbonate ester, and used acetonitrile, benzoate as a wettable powder to remove water produced as a byproduct together with carbonate ester out of the system. By using nitrile, high pressure such as 30 MPa (300 atm) or 6 MPa (60 atm) as described in Non-Patent Documents 4 and 5 is unnecessary, and the effect of promoting the reaction under a pressure close to normal pressure. For the first time and filed a patent application (Patent Document 4, Patent Document 5). Even when any wettable powder is used, a treatment method such as separation or reuse of by-product amide has not been studied, which is a problem.

  Based on the above knowledge, the present inventors proceeded with a study on a method for producing a carbonate ester including utilization of by-products, and the reaction was likely to proceed under a relatively low pressure close to normal pressure, and the reaction rate was very high. It was considered that benzonitrile having excellent characteristics as a wettable powder, which is fast and has few by-products, is used in this production method.

  Thus, 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.

Furthermore, among such catalysts, it has been found that either one of CeO ₂ and ZrO ₂ or both oxides are very effective (Patent Document 5).

  Next, based on these findings, the present inventors have found that when benzonitrile is used as a hydrating agent, benzamide produced as a by-product has a limited use and is difficult to effectively utilize. The regenerative reaction to was studied earnestly.

  Previously, benzamide dehydration reaction was carried out only with homogeneous catalysts, but we studied heterogeneous catalysts that suppress by-products and can be easily separated from raw materials and products that exist in the liquid phase in the reaction system. .

  The present inventors consider that a double bond between a metal and oxygen in a metal oxide is mainly effective as a dehydration reaction as a dehydration reaction of benzamide, and use a metal oxide having a double bond as an active species. The catalyst was studied.

  As a result, it has been found that when a catalyst in which a specific metal oxide having a double bond between metal and oxygen is supported on a catalyst carrier, high activity is obtained even under relatively mild conditions. I came to do it.

The gist of the present invention is as follows.
(1) A monohydric alcohol and carbon dioxide are reacted in the presence of either one of CeO ₂ and ZrO ₂ or both solid catalysts and benzonitrile to produce a carbonate and water, and the benzonitrile A first reaction step of generating benzamide by a hydration reaction between the water and the generated water;
After separating the benzamide from the first reaction step, the metal oxide of one or more metal species of molybdenum, tungsten, rhenium, vanadium, niobium is SiO ₂ , TiO ₂ , By dehydration reaction by heating in the presence of a catalyst supported on one or more of the catalyst supports of CeO ₂ , ZrO ₂ , Al ₂ O ₃ , and C and in the presence of an organic solvent , Having a second reaction step to regenerate to benzonitrile,
Benzonitrile regenerated in the second reaction step is used in the first reaction step. Also,

(2) Separation of the benzamide from the first reaction step is
The carbonate ester, benzamide, unreacted benzonitrile discharged from the first reaction step, and the solid catalyst are subjected to solvent extraction with alkane and then separated into solid and liquid, and the liquid phase carbonate ester, unreacted benzonitrile, And separating the alkane and the solid catalyst and benzamide in solid phase;
Separating the liquid phase carbonate after solid-liquid separation, unreacted benzonitrile, and alkane, respectively;
The solid catalyst and benzamide after the solid-liquid separation are extracted with a hydrophilic solvent, followed by solid-liquid separation, and separated into a liquid phase benzamide and a hydrophilic solvent and a solid phase solid catalyst.
Furthermore, after the second reaction step,
A step of filtering the catalyst in which the benzonitrile, unreacted benzamide, and metal oxide supported on the catalyst support are discharged from the process to separate the catalyst in which the solid phase metal oxide is supported on the catalyst support. When,
Separating each of the benzonitrile, benzamide, organic solvent, and water remaining after the separation,
The method for producing a carbonate ester according to (1), wherein the separated benzonitrile is used in the first reaction step. Also,

(3) The method for producing carbonate ester according to (2), further comprising a step of regenerating the separated solid catalyst, wherein the regenerated catalyst is used in the first reaction step. is there. Also,

(4) The method for producing a carbonate ester according to (2) or (3), wherein the alkane used in the solvent extraction is hexane. Also,

(5) The method for producing a carbonate ester according to any one of (2) to (4), wherein the hydrophilic solvent is acetone. Also,

(6) The catalyst carrying the alkali metal is any one of molybdenum, tungsten, rhenium, vanadium, and niobium on a catalyst carrier composed of one or more of SiO ₂ , TiO ₂ , CeO ₂ , and ZrO _2. The method for producing a carbonate ester according to any one of (1) to (5), wherein the catalyst is a catalyst supporting one or more metal oxides. Also,

(7) The method for producing a carbonate ester according to any one of (1) to (6), wherein the catalyst carrier is SiO ₂ . Also,

(8) The method for producing a carbonate ester according to any one of (1) to (7), wherein the metal oxide is molybdenum oxide. Also,

(9) The method for producing a carbonate ester according to any one of (1) to (8), wherein the monohydric alcohol is methanol and dimethyl carbonate is produced as a carbonate ester. Also,

(10) The method for producing a carbonate ester according to any one of (1) to (8), wherein the monohydric alcohol is ethanol and diethyl carbonate is produced as a carbonate ester. Also,

(11) The method for producing a carbonate ester according to any one of (1) to (10), wherein the organic solvent is mesitylene. Also,

(12) The method for producing a carbonate ester according to any one of (1) to (11), wherein a dehydrating agent is used in the second reaction step. Also,

(13) A carbonate ester production apparatus used in the production method according to any one of (1) to (12),
A means for pressurizing carbon dioxide; a means for mixing one of CeO ₂ and ZrO ₂ or both solid catalysts, monohydric alcohol, carbon dioxide and 2-cyanopyridine; and reacting; and CeO ₂ , ZrO ₂ And a monohydric alcohol and carbon dioxide in the presence of benzonitrile in the presence of one or two or more solid catalysts selected from the group consisting of CeO ₂ and ZrO ₂ compounds, and carbonate and water. A first reaction means for producing benzamide by a hydration reaction between the benzonitrile and the produced water;
Carbonate ester, benzamide, unreacted benzonitrile, and the solid catalyst discharged by the means are subjected to solvent extraction with alkane, followed by solid-liquid separation, and liquid phase carbonate ester, unreacted benzonitrile, and alkane, Means for separating the solid catalyst and benzamide in solid phase;
Means for separating the carbonate, unreacted benzonitrile, and alkane in the liquid phase after the solid-liquid separation;
The solid catalyst and benzamide after the solid-liquid separation are extracted with a hydrophilic solvent and then separated into solid and liquid, and separated into a liquid phase benzamide and a hydrophilic solvent and a solid phase solid catalyst,
The separated benzamide is a metal oxide of any one or more of molybdenum, tungsten, rhenium, vanadium, niobium, or a metal oxide of SiO ₂ , TiO ₂ , CeO ₂ , ZrO ₂ , Al ₂ O ₃ , A second reaction means for producing a benzonitrile by dehydration by heating in the presence of a catalyst supported on any one or two or more catalyst carriers of C and in the presence of an organic solvent;
Means for separating the catalyst in which the solid phase metal oxide is supported on the catalyst carrier by filtering the catalyst in which the benzonitrile, unreacted benzamide and metal oxide supported on the catalyst carrier are discharged by the means When,
And means for separating benzonitrile, benzamide, organic solvent, and water remaining after the separation,
An apparatus for producing a carbonic ester, comprising means for conveying the separated benzonitrile to the first reaction means.

  In the carbonate ester production method and apparatus of the present invention, a monohydric alcohol and carbon dioxide are reacted in the presence of a solid catalyst and benzonitrile to produce a carbonate ester in a high yield, and a high selectivity from a by-product benzamide is obtained. And can be regenerated to benzonitrile in high yield, and the regenerated benzonitrile can be reused in the production of carbonates. As a result, separation after the reaction is easy, and the only by-product is water, making it possible to produce a carbonate ester with high efficiency and low environmental impact.

It is a figure which shows typically the example of the manufacturing apparatus of the carbonate ester of this invention. It is a figure which shows the state of each substance in each process of the manufacturing apparatus of the carbonate ester of FIG. It is a figure which shows typically the other example of the manufacturing apparatus of the carbonate ester of this invention. It is a figure which shows the state of each substance in each process of the manufacturing apparatus of the carbonate ester of FIG.

<Method for producing carbonate ester>
Hereinafter, the production method of the present invention will be described in more detail with reference to specific examples.

[First reaction step]
The first reaction step in the method for producing a carbonate ester of the present invention involves directly reacting a monohydric alcohol and carbon dioxide in the presence of one or both of a solid catalyst of CeO ₂ and ZrO ₂ and benzonitrile to produce carbonic acid. An ester is produced.

In this step, when monohydric alcohol and carbon dioxide are reacted, water is produced in addition to the carbonate ester. However, the presence of benzonitrile produces benzamide by hydration reaction with the produced water. It becomes possible to promote the production | generation of carbonate ester by removing or reducing from a reaction system.

(Monohydric alcohol)
Here, as the monohydric alcohol, any alcohol selected from one or more of primary alcohol, secondary alcohol, and tertiary alcohol can be used, and methanol, ethanol, 1-propanol , 1-butanol, benzyl alcohol, and allyl alcohol are preferred because the yield of the product is high and the reaction rate is fast. At this time, the produced carbonates are dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dibenzyl carbonate, and diallyl carbonate, respectively.

(Carbonate production catalyst)
Moreover, either or both of the solid catalyst of CeO ₂ and ZrO _2, only CeO _2, only ZrO _2, a CeO ₂ and mixtures of ZrO _2, or CeO ₂ solid solution or a composite oxide of ZrO _2, in particular Only CeO ₂ is preferred. As for the CeO ₂ and ZrO ₂ solid solution or a composite oxide, the mixing ratio of CeO ₂ and ZrO ₂ (molar ratio) is not particularly limited, for example, 1: 99 to 99: can be a 1, For example, the molar ratio may be 50:50.

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, it is not preferable because a large amount of ether is synthesized rather than carbonate. In the moderate acid base complex function catalyst, RO-M on base point (M catalyst) alcohol dissociates adsorbed in the form of, RO-C (= O) with the CO ₂ -O ... M On the other hand, on the acid point, alcohol is adsorbed in the form of HO—R... M, and RO—C (═O) —OR is generated between both adsorbed species.

This solid catalyst also exhibits catalytic activity for the hydration reaction of water and benzonitrile by-produced during the synthesis of the carbonate ester. 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 the synthesis of the carbonic acid ester, 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 is increased, the surface of the solid catalyst is covered with CO ₂ , and the hydration reaction rate is reduced because it becomes difficult to be catalyzed by the hydration reaction with water molecules generated in the main reaction. Inferred. On the other hand, acetal and 2,2-dimethoxypropane described in Non-Patent Document 4 and Non-Patent Document 5 do not undergo any catalytic action in the liquid phase and cause a 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.

Further, with respect to the method for producing the catalyst of the present invention, the following examples are given. First, in the case of cerium oxide (CeO ₂ ), cerium acetylacetonate hydrate, cerium hydroxide, cerium sulfate, cerium acetate, cerium nitrate It can be prepared by firing various cerium compounds such as ammonium cerium nitrate, cerium carbonate, cerium oxalate, cerium perchlorate, cerium phosphate and cerium stearate in an air atmosphere. When cerium oxide as a reagent 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 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. When zirconium oxide as a reagent 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 such as a solid solution or composite oxide of CeO ₂ and ZrO ₂ , a base is added to a solution containing cerium and zirconium to form a hydroxide by coprecipitation, followed by filtration and washing with water. It can be prepared by drying and firing in an air atmosphere. Although the powder particles of CeO ₂ and ZrO ₂ can also be prepared by firing the physical mixture, the specific surface area of the final preparation is not high, preferably easily coprecipitation reaction proceeds more.

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 depending on the raw material, for example, 300 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. The impurities are preferably less than 1% by mass with respect to the catalyst.

  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. .

(carbon dioxide)
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.

(Solid-liquid separation)
Under the conditions where the conversion rate of monohydric alcohol is 100% and no by-products such as methyl benzoate and methyl carbamate are produced, the main product carbonate ester, by-product benzamide, unreacted It becomes a solid catalyst such as benzonitrile and CeO ₂ . In order to separate them, first, a liquid component (carbonate ester, benzonitrile) is extracted in an extraction step using an organic solvent, and can be separated from a solid component (benzamide and a fixed catalyst) with a filter. The organic solvent used here is preferably an alkane that can dissolve the carbonate, and more preferably hexane, octane, nonane, decane, and undecane.

(Separation of liquid components)
Next, the separated liquid component contains carbonic acid ester, benzonitrile, and organic solvent. The melting point and boiling point of each substance are 4 ° C and 90 ° C (dimethyl carbonate), -43 ℃ and 128 ℃ (diethyl carbonate), -41 ℃ and 167 ℃ (dipropyl carbonate), 25 ℃ or less and 207 ℃ (dibutyl carbonate), -13 ℃ and 188 ℃ (benzonitrile), -95 ℃ And 69 ° C. (for example, hexane), the carbonate ester can be separated by distillation, and the product carbonate ester can be recovered with high purity. In addition to distillation, it is also possible to filter and recover what is solidified by cooling stepwise to below the melting point.

(Separation of solid components)
The benzamide and the solid catalyst separated as solid components can be separated from the solid catalyst and the filter by extracting only benzamide with a hydrophilic solvent. The hydrophilic solvent used here is preferably acetone, ethanol, ether, or water in view of ease of handling and separation at a later stage. The benzamide dissolved in the hydrophilic solvent can be separated by distillation, and the by-product benzamide can be purified with high purity.
In addition to distillation, benzamide dissolved in a hydrophilic solvent can be recovered by cooling and solidifying the benzamide that has cooled to below the melting point and solidified with a liquid hydrophilic solvent.

(Regeneration treatment of the separated solid catalyst)
The separated solid catalyst is regenerated in the step of regenerating the catalyst and can be reused in the first reaction step. The catalyst regeneration step is a step of heating to burn off impurities and the like on the solid catalyst, and is preferably calcined at 400 to 700 ° C., more preferably 500 to 600 ° C. for about 3 hours. In order to prevent structural destruction of the solid catalyst due to rapid temperature rise, it is better to consider the drying step before firing, and it is preferable to dry at 110 ° C. for about 2 hours.

(Residual components)
Further, when unreacted monohydric alcohol remains, or the reaction temperature is as high as 130 ° C. or higher, or the reaction time is as long as 24 hours or longer, by-products such as methyl benzoate and methyl carbamate are formed. If produced, the melting point and boiling point of monohydric alcohol are -97 ° C and 65 ° C (methanol), -114 ° C and 78 ° C (ethanol), -126 ° C and 97 ° C (1-propanol), -90 ° C and 117 ° C (1-butanol), etc., and -15 ° C and 198 ° C (methyl benzoate), 52 ° C and 177 ° C (methyl carbamate). By stepping up to a certain extent, monohydric alcohol, organic solvent, carbonate and methyl carbamate can be separated from methyl benzoate and benzonitrile. The solidified methyl benzoate can be separated from benzonitrile by a filter by cooling and then cooling.
Since most of monohydric alcohols and organic solvents are organic solvents, they can be reused in the extraction process with organic solvents. However, it is preferable that there are few by-products because it is difficult for the processing step after separation to the outside of the system to occur.

[Second reaction step]
Next, in the second reaction step of the present invention, the benzamide produced as a by-product in the first reaction step is separated from the system after the carbonic acid ester formation reaction, and then benzonitrile is produced by a dehydration reaction.

In the production of benzonitrile, benzamide is produced by dehydrating benzamide in the presence of a catalyst supporting a basic metal oxide and an organic solvent.

(Benzonitrile production catalyst)
Here, the catalyst used in the present invention is generally a catalyst carrier made of an oxide (metal oxide) of a metal species (molybdenum, tungsten, rhenium, vanadium, niobium) having a double bond between metal and oxygen. Although a catalyst supported on a substance can be used, as a result of examining various supports, a catalyst composed of one or more of SiO ₂ , TiO ₂ , CeO ₂ , ZrO ₂ , Al ₂ O ₃ , and C is used. It has been found that high performance is exhibited when a catalyst supported on a carrier is used.

In particular, it is preferable to use any one or two or more catalyst carriers of SiO ₂ , TiO ₂ , CeO ₂ , and ZrO ₂ because higher performance is exhibited.

  This is because, in the reaction with benzamide, it is considered that the double bond portion between the metal and oxygen may be active, and thus a metal element having a double bond is preferable among the metal oxides.

Further, as a result of intensive studies by the present inventors, it is particularly preferable to use a catalyst in which molybdenum is supported on SiO ₂ in a highly dispersed state. Whether it is highly dispersed can be confirmed with an image of a transmission electron microscope (such as TEM).

Examples of the carrier production method used here are roughly divided into a dry method and a wet method as general production methods in the case of SiO ₂ . The dry method includes a combustion method, an arc method, etc., and the wet method includes a sedimentation method, a gel method, etc., and it is possible to manufacture a catalyst carrier by any of the manufacturing methods. Since it is technically and economically difficult to form, a gel method is preferred in which silica sol can be easily formed into a spherical shape by spraying in a gas medium or a liquid medium.

In the case of CeO _2, cerium acetylacetonate hydrate and cerium hydroxide, cerium sulfate, cerium acetate, cerium nitrate, cerium ammonium nitrate, cerium carbonate, cerium oxalate, perchlorate cerium, cerium phosphate, cerium stearate These various cerium compounds can be prepared by firing in an air atmosphere. When cerium oxide as a reagent 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 cerium is dissolved, filtering, drying, and baking.

In the case of ZrO ₂ , various zirconium compounds such as zirconium ethoxide, zirconium butoxide, zirconium carbonate, zirconium hydroxide, zirconium phosphate, zirconium acetate, zirconium chloride oxide, zirconium dinitrate, zirconium sulfate and the like are calcined in an air atmosphere. Can be prepared. When zirconium oxide as a reagent 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 TiO ₂ or Al ₂ O ₃ , it can be produced by a general method. C is mainly composed of carbon and may be in any form as long as it does not change during the reaction period. For example, activated carbon is preferable, but it is not limited thereto.

  In the case of a compound containing two or more metal species, a base is added to a solution containing two or more metal salts to form a hydroxide by coprecipitation, followed by filtration and washing in an air atmosphere. Can be prepared by drying and baking. Moreover, although it can prepare also by physically mixing and baking the powder of 2 or more types of oxides, since the homogeneity of the component of a final preparation does not become high, the coprecipitation method with which reaction progresses more is preferable.

For example, in the case of a compound of CeO ₂ and ZrO ₂ , a base is added to a solution containing cerium and zirconium to form a hydroxide by coprecipitation, followed by filtration and washing, followed by drying and firing in an air atmosphere. Can be prepared.

By such a method, a solid catalyst carrier made of a compound of cerium oxide and zirconium oxide such as CeO ₂ —ZrO ₂ can be obtained. In addition, including the case where a catalyst carrier made of cerium oxide or a catalyst carrier made of zirconium oxide is prepared, the firing temperature at the time of preparation of each of these catalyst carriers may be selected at a temperature at which the specific surface area of the final preparation is increased. Although it depends on the starting material, for example, 300 ° C. to 1100 ° C. is preferable. Further, the solid catalyst carrier according to the present invention may contain inevitable impurities that are mixed in the catalyst manufacturing process in addition to the above elements, but it is desirable that impurities are not mixed as much as possible.

  In the production method of the catalyst of the present invention, a metal oxide as an active species may be supported on a support by a known method. In addition to the precipitation loading method using a general solution, for example, it can be supported by an impregnation method such as an incipient wetness method or an evaporation to dryness method.

Preferred examples are given below. When the carrier is SiO ₂ , a commercially available powder or spherical SiO ₂ can be used, and pre-baking is performed to adjust the particle size to 100 mesh (0.15 mm) or less and to remove moisture so that the active metal can be uniformly supported. It is preferable to carry out at 700 degreeC in air for 1 hour. Moreover, although SiO ₂ has various properties, it is preferable that the surface area is large because the active metal can be highly dispersed and the amount of benzonitrile produced is improved. Specifically, a surface area of 300 m ² / g or more is more preferable. However, the surface area of the catalyst after preparation may be lower than the surface area of only SiO ₂ due to the interaction between SiO ₂ and the active metal. In that case, it is more preferable that the surface area of the catalyst after manufacture is 150 m ² / g or more.

  The metal salt that is the precursor of the metal oxide that becomes the active species only needs to have high solubility in various solvents. For example, carbonate, bicarbonate, chloride, nitrate, sulfate, silicate, acetate Various compounds such as can be used. After impregnating the precursor solution of the metal compound into the support, it can be used as a catalyst by drying and firing, and the firing temperature is preferably 400 to 600 ° C., although it depends on the precursor used.

  The amount of metal oxide supported may be set as appropriate. For example, the amount of metal oxide supported in terms of metal based on the total catalyst weight is about 0.1 to 1.5 mmol / g, particularly 0.1 to 1 mmol. / G, preferably about 0.2 to 0.8 mmol / g. When the loading amount is larger, the activity may be reduced due to the coarsening of the metal oxide. Moreover, what is necessary is just to set suitably about the usage-amount of the catalyst at the time of reaction.

  Further, the catalyst according to the present invention may contain inevitable impurities that are mixed in the catalyst manufacturing process in addition to the above-mentioned elements, but it is desirable that impurities are not mixed as much as possible.

  Here, the catalyst supported on the carrier of the present invention may be in the form of a powder or a molded body. In the case of a molded body, a spherical shape, a pellet shape, a cylinder shape, a ring shape, a wheel shape, a granule Any shape may be used.

(Organic solvent)
As the organic solvent used for the dehydration reaction, various substances having a boiling point of 130 ° C. or higher are preferably used. Among them, chlorobenzene, (o-, m-, p-) xylene, mesitylene, and the like are more preferably used, and particularly mesitylene. Is preferred.

(Reaction conditions)
In the method for producing benzonitrile using the catalyst of the present invention, the reaction conditions are preferably selected from the viewpoints of the dehydration reaction rate, the boiling point of the solvent, the amount of CO ₂ emitted during the reaction, and the economy. The reaction temperature can be 160 to 200 ° C., the reaction pressure is normal pressure, and the reaction time is about several hours to 24 hours, but is not particularly limited thereto.

(Reaction format)
Next, the method for producing benzonitrile using the catalyst of the present invention is not particularly limited as a reaction format, and is distributed as a batch reactor, a semi-batch reactor, a continuous tank reactor or a tubular reactor. Any of the type reactors may be used. Moreover, any of a fixed bed, a slurry bed, etc. can be applied to the catalyst.

(dehydration)
In the second reaction step of producing (regenerating) benzonitrile from the by-produced benzamide in the production method of the present invention, it is carried out while removing the by-product water produced by the dehydration reaction, as in the step of producing carbonate ester. For example, it is desirable to install a dehydrating agent such as zeolite in the system and perform the reaction while removing by-product water. As a result of intensive studies by the present inventor, using a Soxhlet extraction tube and a cooler, zeolite (molecular sieve) or calcium hydride was installed in the extraction tube as a dehydrating agent, and a catalyst, benzamide, and an organic solvent were placed in the reaction tube. By reacting with refluxing, it is possible to improve the amount of benzonitrile produced.

The type and shape of the molecular sieve used as the dehydrating agent are not particularly limited. For example, 3A, 4A, 5A, etc., which are generally highly water-absorbing, such as spherical or pellets are used. it can. Moreover, it is preferable to dry beforehand and it is preferable to dry at 300-500 degreeC for about 1 hour.

(Reaction product)
In the dehydration reaction of benzamide, benzoic acid may be produced as a by-product due to the decomposition of benzamide as described above. However, after the dehydration reaction using the catalyst of the present invention, a small amount of benzamide and product remained in the reaction product. There are only some benzonitriles, by-product water, and organic solvents, and these by-products are hardly produced. In the case of reflux using a Soxhlet extraction tube and a cooler, the reaction temperature is preferably a condition under which a dehydration reaction of benzamide is performed in a liquid phase. Considering the reaction efficiency, it is preferable that the temperature is higher under liquid phase conditions. When the reaction is performed under normal pressure, it is preferable to heat the periphery of the reaction tube to 160 to 200 ° C. The melting point of each substance in the reaction system of a typical example is 127 ° C. (benzamide), −13 ° C. (benzonitrile), −45 ° C. (organic solvent such as mesitylene), and the boiling point is 288 ° C. (benzamide), 188 Since it is ℃ (benzonitrile), 100 ℃ (water), 165 ℃ (organic solvent, for example, mesitylene), at the above temperature, the reaction phase is almost liquid except for the solid catalyst, The partially vaporized benzamide, by-product water, and organic solvent are cooled by a cooler, and the by-product water is adsorbed by the dehydrating agent, and the benzamide and the organic solvent return to the reaction tube and contribute to the reaction again.

[Reuse of benzonitrile]
The benzonitrile regenerated in the second reaction step can be reused in the first reaction step.

<Carbonate production equipment>
Next, a specific example is shown below and the example of the manufacturing apparatus and operation conditions (reaction conditions) used with the manufacturing method of the carbonate ester of this invention is demonstrated still in detail. FIG. 1 is an example of a suitable facility of the present invention. Moreover, the state of each substance in each process in this equipment in FIG. 1 is shown in FIG. This equipment can be used in the case of reaction conditions in which the conversion rate of monohydric alcohol is 100% and byproducts of methyl benzoate and methyl carbamate are not generated.

[First reaction step]
In the first reaction step, one or both of the solid catalyst (solid phase), monohydric alcohol 12 (liquid phase), and benzonitrile 13 (liquid phase) of CeO ₂ and ZrO ₂ are added to the first reaction column 1. Then, carbon dioxide (gas phase) is filled through the booster blower 10. As the solid catalyst, a solid catalyst 14 (solid phase) newly charged before the reaction or regenerated in the regeneration tower 6 can be used. Also, a new benzonitrile is used at the start of the reaction, but the unreacted benzonitrile 20 (liquid phase) purified in the first distillation column 3 and the benzamide regenerated from the benzamide purified in the third distillation column 9 are used. Nitriles can be reused.

Next, the carbon dioxide ester direct synthesis apparatus using the solid catalyst of either or both of CeO ₂ and ZrO ₂ of the present invention is a batch reactor, a semi-batch reactor, a continuous tank reactor, a tube type, or the like. Any flow reactor such as a reactor may be used.

(Reaction temperature)
The reaction temperature in the first reaction tower 1 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 tends to be low. When the reaction temperature exceeds 150 ° C., the reaction rate of each reaction increases, but decomposition and modification of the carbonate ester, and benzamide easily react with the monohydric alcohol, so that the yield of the carbonate ester tends to decrease. is there. More preferably, it is 100-150 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 appropriately set the optimum conditions. Since a preferable reaction temperature is 100 to 150 ° C., it is desirable to preheat the raw material (monohydric alcohol, benzonitrile) with steam or the like before the first reaction column.

(Reaction pressure)
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, and not only the equipment is complicated and expensive, but also the motive energy for reducing the pressure is required, resulting in poor energy efficiency. On the other hand, when the reaction pressure exceeds 5 MPa, the hydration reaction by benzonitrile is difficult to proceed and not only the yield of the carbonate ester is deteriorated, but also the kinetic energy necessary for pressurization is required and the energy efficiency is deteriorated. Further, from the viewpoint of increasing the yield of carbonate ester, the reaction pressure is more preferably 0.1 to 4 MPa (absolute pressure), and further preferably 0.2 to 2 MPa (absolute pressure).

(Dose of benzonitrile)
The benzonitrile used for the hydration reaction is preferably introduced into the reactor in advance at a rate of 0.1 to 1 times the volume of the starting alcohol prior to the reaction. If it is introduced at less than 0.1 times, the yield of the carbonate ester may be deteriorated because there is little benzonitrile contributing to the hydration reaction. On the other hand, when it is introduced more than 1 time, there is no particular problem because it can be easily separated from the product after the completion of the reaction and can be reused. 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.

(Reaction product separation)
The reaction liquid 15 after the reaction in the first reaction tower 1 is separated into a liquid phase and a solid phase in the first extraction tower 2. The substances contained in the reaction solution 15 are carbonate ester (liquid phase), unreacted benzonitrile (liquid phase), benzamide (solid phase), and solid catalyst (solid phase), and are extracted with an organic solvent (liquid phase). . Alkane is suitable for the organic solvent used here, and hexane, octane, nonane, decane, and undecane are preferable from the viewpoint of ease of separation by distillation in the subsequent stage. In order to reduce energy consumption, the extraction process in the first extraction column 2 is preferably performed at room temperature, but the temperature is lower than the boiling point of the organic solvent (for example, in the case of hexane, the boiling point is 69 ° C.). If it is heated to about 50 ° C., the extraction time can be shortened by heating.

  The extract 17 extracted in the first extraction tower 2 contains carbonate ester, unreacted benzonitrile, and alkane. In the first distillation column 3, the boiling point of each substance is 90 ° C. (for example, dimethyl carbonate), 188 ° C. (benzonitrile), 69 ° C. (for example, hexane). A carbonate ester 19, unreacted benzonitrile 20 and alkane 16 used for extraction are separated.

  On the other hand, the solid phase 18 separated in the first extraction tower 2 contains benzamide and a solid catalyst, and is separated in the second extraction tower 4. As the solvent used here, a hydrophilic solvent (liquid phase) capable of dissolving benzamide is suitable, and acetone, ethanol, ether, and water are preferable because they are easily separated by distillation at a later stage. The extraction step in the second extraction tower 4 is also preferably performed at room temperature for extraction in order to suppress energy consumption. However, the temperature is lower than the boiling point of the hydrophilic solvent (for example, in the case of acetone, the boiling point is 56.56). If it is 5 [deg.] C. and heated to about 40 [deg.] C.), the extraction time can be shortened by heating.

  The extract 21 containing benzamide and a hydrophilic solvent is distilled in the second distillation column 5, and the boiling point of each substance is separated into 127 ° C. (benzamide) and 57 ° C. (for example, in the case of acetone).

  Further, the solid catalyst 22 (solid phase) separated by the second extraction tower 4 can be regenerated by the catalyst regeneration tower 6 and returned to the first reaction tower 1. The catalyst regeneration is a step of heating to burn off impurities and the like on the solid catalyst, and calcination is performed at 400 to 700 ° C., preferably 500 to 600 ° C. for about 3 hours. In order to prevent structural destruction of the solid catalyst due to rapid temperature rise, it is better to consider the drying step before firing, and it is preferable to dry at 110 ° C. for about 2 hours.

  The benzamide 23 (solid phase) purified in the second distillation column 5 is transferred to the second reaction column 7 for regeneration to benzonitrile, but the piping is made of low-pressure steam or the like to prevent blockage in the piping. It is desirable to heat to a melting point of 127 ° C. or higher.

  The solution after the reaction can be recovered as a used catalyst 26 by separating only the solid catalyst by filtering with a filter in the catalyst separation device 8. At this time, it can be easily recovered by a solid-liquid separation method such as normal filtration. Since the boiling point of each substance present in the system is different as described above after the catalyst separation, it can be easily separated into benzonitrile, organic solvent, benzamide, and water by distillation. The organic solvent 27 and the benzamide 28 can be recycled for the dehydration reaction of benzamide. The purified benzonitrile 13 can be reused in a reaction for producing a carbonate ester.

[Second reaction step]
In the second reaction step, benzonitrile is generated in the second reaction column 7 by a dehydration reaction of benzamide. The production apparatus of the present invention is an apparatus for producing benzonitrile by dehydrating benzamide in the presence of a catalyst supporting a metal oxide having a double bond and an organic solvent. The reaction format is not particularly limited, and any of a batch reactor, a semi-batch reactor, a flow reactor such as a continuous tank reactor and a tubular reactor may be used. Moreover, any of a fixed bed, a slurry bed, etc. can be applied to the catalyst. The temperature of the second reaction column can be changed according to the reaction mode, but in the case of reflux using a Soxhlet extraction tube and a cooler, the periphery of the reaction tube is preferably heated to 160 to 200 ° C. In the production apparatus of the present invention, it is desirable to carry out while removing the by-product water produced by the dehydration reaction. For example, a dehydrating agent such as reflux, distillation or zeolite is installed in the system to remove the by-product water. It is desirable to carry out the reaction. As a result of intensive studies by the present inventor, using a Soxhlet extraction tube and a cooler, zeolite (molecular sieve) or calcium hydride was installed in the extraction tube as a dehydrating agent, and a catalyst, benzamide, and an organic solvent were placed in the reaction tube. By reacting with refluxing, it is possible to improve the amount of benzonitrile produced. The organic solvent is preferably a substance having a boiling point of 130 ° C. or higher, and examples thereof include chlorobenzene, (o-, m-, p-) xylene, and mesitylene.

  In the case of reflux using a Soxhlet extraction tube and a cooler, the periphery of the reaction tube is heated to 160 to 200 ° C. The melting point of each substance is 127 ° C. (benzamide), −13 ° C. (benzonitrile), −45 ° C. (organic solvent such as mesitylene), and the boiling point is 288 ° C. (benzamide), 188 ° C. (benzonitrile), Since the reaction phase is 100 ° C. (water) and 165 ° C. (organic solvent such as mesitylene), the reaction phase is all liquid except for the solid catalyst, and partially evaporated benzamide, by-product water, and organic solvent Cooled by a cooler, by-product water is adsorbed by a dehydrating agent, and benzamide and the organic solvent return to the reaction tube and contribute to the reaction again.

  The solution after the reaction is recovered as a used catalyst 26 by separating only the catalyst in the catalyst separation column 8 while being heated to 288 ° C. or higher, which is the melting point of benzamide, with low-pressure steam or the like. At this time, it can be easily recovered by a solid-liquid separation method such as normal filtration. After the catalyst separation, the boiling points of the respective substances present in the system are different as described above. Therefore, by distillation in the third distillation column 9, benzonitrile 13, organic solvent 27, benzamide 28, water 29 The organic solvent 27 and the benzamide 28 can be returned to the previous stage of the third reaction column 7 and recycled. Further, the purified benzonitrile 13 can be reused in the first reaction column 1 for producing a carbonate ester.

[Another Example of Carbonate Production Method and Apparatus]
FIG. 3 shows another example of the preferred equipment of the present invention, and FIG. 4 shows the state of each substance in each process in the equipment of FIG. This equipment can also be used in the case of reaction conditions in which unreacted monohydric alcohol remains and by-products of methyl benzoate and methyl carbamate are generated. The basic configuration is the same as in the case of FIG. 1 described above, but the extract 17 extracted in the first extraction tower 2 includes carbonate, unreacted benzonitrile, alkane, methyl carbamate and benzoic acid. Contains methyl acid. The boiling point of each substance in the first distillation column 3 is 90 ° C. (for example, dimethyl carbonate), 215 ° C. (benzonitrile), 69 ° C. (for example, hexane), 65 ° C. (for example, methanol), 177 ° C. (Methyl carbamate) 233 ° C. (methyl benzoate), which is distilled by gradually increasing the temperature up to about 180 ° C., and the product carbonate 19 and the alkane used for extraction The mixture is separated into a mixture 33 of unreacted monohydric alcohol and methyl carbamate 32. In addition, by cooling to about 30 to 100 ° C. after distillation, methyl benzoate having a melting point of 103 ° C. solidifies, so that it can be separated into solid and liquid with a filter or the like, and unreacted benzonitrile 20 and benzoate It can be separated into methyl acid 31. Moreover, since the mixture 33 of alkane and monohydric alcohol is mostly alkane, it can be reused as a solvent for extraction.

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

Example 1
Carbonate ester was produced using the production apparatus shown in FIG. CeO ₂ (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 stirrer, the solid catalyst (1 mmol), methanol (100 mmol) and benzonitrile (BN, 50 mmol) were introduced into a 190 ml autoclave (reactor), and the air in the autoclave was blown 3 times with about 5 g of CO _2. After purging, a predetermined amount of CO ₂ was introduced and pressurized. The autoclave was heated up to 150 ° C. with a band heater and a hot stirrer, and the time when the target temperature was reached was defined as the reaction start time. After reacting at 150 ° C. for 12 hours, the autoclave was cooled with water, and when cooled 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). Thus, test No. shown in Table 1 was changed by changing the amount of CO ₂ introduced and the reaction pressure. 1-2 experiments were performed.

  As a result, it was confirmed that the amount of dimethyl carbonate (DMC) produced was large even at 1 MPa under a relatively low pressure, and that the DMC yield based on methanol was 15% at 1 MPa and 8% at 5 MPa. The amount of by-product benzamide (BA) produced was almost the same as DMC, and no other by-products were detected.

Here, since the yield based on methanol (alcohol) is alcohol: carbonate = 2: 1 in terms of the stoichiometric ratio, it was calculated by the following equation.

Next, 200 ml of hexane was added to the solid-liquid coexisting substance after each test, and the mixture was stirred, extracted with a solvent, and filtered through a filter to separate a liquid and a solid. The liquid contains DMC, BN, methanol, and hexane, and the solid contains BA and CeO ₂ . The liquid component after solvent extraction with hexane was separated into DMC, BN, hexane and methanol by distillation that gradually increased the temperature to about 120 ° C., and DMC with a purity of 96% or more could be recovered. Further, BA and CeO ₂ in the fixed component are dissolved in 200 ml of acetone and then filtered through a filter to separate CeO ₂ , BA and acetone, and further, BA and acetone are separated by distillation, respectively, and purity is 97% or more. Of BA could be recovered.

Subsequently, regeneration from the recovered BA to BN will be described below. SiO ₂ (manufactured by Fuji Silysia, CARiACT, G-6, surface area: 535 m ² / g) serving as a carrier was sized to 100 mesh or less and pre-baked at 700 ° C. for about 1 hour. Thereafter, in order to support Mo as a metal, an aqueous solution is prepared using (NH ₄ ) ₆ Mo ₇ O ₂₄ (manufactured by Kanto Kagaku, special grade) so that the amount of Mo metal supported is finally 0.5 mmol / g. And impregnated with SiO ₂ . Thereafter, about 6 hours drying at 110 ° C., and calcined at 500 ° C. for about 3 _hours, to obtain a MoO 3 / SiO ₂ catalyst. So, a magnetic stir bar, the above catalyst (0.1 g), BA produced as a by-product of DMC generation, and mesitylene (20 ml) were introduced into a test tube, and Soxhlet extraction was packed with molecular sieve 4A (pre-dried at 300 ° C. for 1 hour). The temperature of the cooler was set to 10 ° C., and the magnetic stirrer was set to about 200 ° C. and 600 rpm. After purging the cooler, the Soxhlet extraction tube, and the test tube with Ar gas, the reaction start time was defined as the time when the solution started to evaporate, and the reaction was performed for 500 hours. After the reaction, the test tube (solution) was cooled to room temperature, 20 ml of ethanol and anthracene (0.1 g) as an internal standard substance were added to the reaction solution, a sample was taken, and GC-MS (gas chromatograph-mass spectrometer) Qualitative analysis and quantitative analysis by FID-GC. In this way, as shown in Table 1, test no. As a result of performing 1-2, BN produced 6.3 mmol and 3.5 mmol, respectively. In all experiments, water was the only byproduct, yield was about 90%, and selectivity was almost 100%.

  The solid-liquid coexisting substance after the test was filtered with a filter under heating at 120 ° C. to separate the liquid and the solid (catalyst). The liquid includes BN, water, unreacted BA, and mesitylene. This liquid component was separated into BN, water, unreacted BA, and mesitylene by distillation that gradually increased the temperature to about 180 ° C., and BN having a purity of 98% or more could be recovered. The separated unreacted BA and mesitylene can be recycled again for the dehydration reaction of BA.

  A second DMC production reaction was performed using the BN regenerated in this manner. The reaction conditions were the same, and a small amount of new BN was added to the BN obtained by regeneration and the unreacted BN in the first reaction so that the amount of BN was 50 mmol. As a result, as in the first time, it was confirmed that DMC was obtained in a high yield, and the amount of BA produced as a by-product was almost the same as DMC, and no other by-products were detected. .

  From the above results, 50 mmol of new BN is required at the start of the reaction. However, it is conventionally necessary to generate DMC by reusing and reusing separated unreacted BN and by-product BA to BN. Most BN can be reduced. In addition, BA may be used as an intermediate for medicines and agrochemicals, but the amount used is not so much, and it was possible to reduce more than 90% of the place where disposal costs were high. Furthermore, when regenerating and distilling from BA to BN, the temperature is increased to about 180 ° C., so this heat is used by supplying it through a heated pipe when reusing it for DMC production. be able to.

(Example 2)
Example 1 was repeated except that ethanol (100 mmol) was used as a monohydric alcohol.

  From the results of Table 2, it was confirmed that diethyl carbonate (DEC) was not as high as DMC, but the ethanol-based DEC yield was 13% at 1 MPa and 7% at 5 MPa. The amount of BA produced as a by-product was almost the same as that of DEC, and no other by-products were detected.

Next, as in Example 1, 200 ml of hexane was added to the solid-liquid coexisting substance after each test, and the mixture was stirred, extracted with a solvent, and filtered through a filter to separate a liquid and a solid. The liquid includes DEC, BN, ethanol, and hexane, and the solid includes BA and CeO ₂ . The liquid component after solvent extraction with hexane was separated into DEC, BN, hexane and ethanol by distillation that gradually increased the temperature to about 130 ° C., and DEC having a purity of 96% or more could be recovered. Further, BA and CeO ₂ in the fixed component are dissolved in 200 ml of acetone and then filtered through a filter to separate CeO ₂ , 2-PA and acetone, and further BA and acetone are separated by distillation, respectively. % Or more of BA could be recovered.
Subsequently, regeneration from the recovered BA to BN was performed in the same manner as in Example 1. As a result, as shown in Table 2, test no. When 3 to 4 were performed, BN produced 6.0 mmol and 3.2 mmol, respectively. In all experiments, the only by-product was water, yield was about 90% or more, and selectivity was almost 100%.

  As for the solid-liquid coexisting substance after the test, each liquid and solid was separated in the same manner as in Example 1, and BN having a purity of 98% or more could be recovered.

  Using the BN regenerated in this manner, a second DEC generation reaction was performed. The reaction conditions were the same as in Example 1, and a small amount of new BN was added to BN obtained by regeneration with unreacted BN so that the amount of BN was 50 mmol. As a result, as in the first time, it was confirmed that DEC was obtained in high yield, and the amount of BA produced as a by-product was almost the same as DEC, and no other by-products were detected. .

  Even when the monohydric alcohol is ethanol and the product is DEC, it has become possible to reduce most of the BN conventionally required for the production of DEC and to reduce the amount of BA that has been disposed of by more than 90%. . Furthermore, when regenerating and distilling from BA to BN, the temperature is raised to about 180 ° C., so this heat is used by supplying it through the insulated pipe when reusing it for DEC production. be able to.

Example 3
The same procedure as in Example 1 was performed except that 1-propanol (100 mmol) was used as a monohydric alcohol and the reaction was performed for 24 hours.

  From the results in Table 3, it is confirmed that the DPC yield based on 1-propanol is 12.4% at 1 MPa and 6.4% at 5 MPa, although not as much as DMC in the case of dipropyl carbonate (DPC). It was done. The amount of BA produced as a by-product was almost the same as DPC, and no other by-products were detected.

Next, as in Example 1, 200 ml of hexane was added to the solid-liquid coexisting substance after each test, and the mixture was stirred, extracted with a solvent, and filtered through a filter to separate a liquid and a solid. The liquid includes DPC, BN, 1-propanol, and hexane, and the solid includes BA and CeO ₂ . The liquid component after solvent extraction with hexane can be separated into DPC, BN, hexane, and 1-propanol by distillation that gradually increases the temperature to about 170 ° C., and DPC with a purity of 96% or more can be recovered. It was. Further, BA and CeO ₂ in the fixed component are dissolved in 200 ml of acetone and then filtered through a filter to separate CeO ₂ , BA and acetone, and further, BA and acetone are separated by distillation, respectively, and purity is 97% or more. Of BA could be recovered.

  Subsequently, regeneration from the recovered BA to BN was performed in the same manner as in Example 1. As a result, as shown in Table 3, the test No. When 5 to 6 were performed, BN produced 5.9 mmol and 2.8 mmol, respectively. In all experiments, the only by-product was water, yield was about 90% or more, and selectivity was almost 100%.

  As for the solid-liquid coexisting substance after the test, each liquid and solid was separated in the same manner as in Example 1, and BN having a purity of 98% or more could be recovered.

  A second DPC generation reaction was performed using the BN thus regenerated. The reaction conditions were the same as in Example 1, and a small amount of new BN was added to BN obtained by regeneration with unreacted BN so that the amount of BN was 50 mmol. As a result, as in the first time, it was confirmed that DPC was obtained in high yield, the amount of BA produced as a by-product was almost the same as DPC, and no other by-products were detected. .

  Even when the monohydric alcohol is 1-propanol and the product is DPC, it is possible to reduce most of the BN conventionally required for the production of DPC, and the amount of BA that has been disposed of can be reduced by more than 90%. became. Furthermore, when regenerating and distilling from BA to BN, the temperature is raised to about 180 ° C., so this heat is used by supplying it through a heated pipe when reusing it for DPC production. be able to.

Example 4
Example 1 was repeated except that 1-butanol (100 mmol) was used as a monohydric alcohol and the reaction was performed for 24 hours.

  From the results in Table 3, it is confirmed that the yield of DBC based on 1-butanol is 11.4% at 1 MPa and 5.8% at 5 MPa, although not as high as DMC in the case of dibutyl carbonate (DBC). It was done. The amount of BA produced as a by-product was almost the same as that of DBC, and no other by-products were detected.

Next, as in Example 1, 200 ml of hexane was added to the solid-liquid coexisting substance after each test, and the mixture was stirred, extracted with a solvent, and filtered through a filter to separate a liquid and a solid. The liquid contains DBC, BN, 1-butanol and hexane, and the solid contains BA and CeO ₂ . The liquid component after solvent extraction with hexane first separates hexane and 1-butanol by distillation that gradually increases the temperature to about 120 ° C., and then cools to about 0 ° C. to precipitate BN. It was possible to recover DBC having a purity of 96% or more. Further, BA and CeO ₂ in the fixed component are dissolved in 200 ml of acetone and then filtered through a filter to separate CeO ₂ , BA and acetone, and further, BA and acetone are separated by distillation, respectively, and purity is 97% or more. Of BA could be recovered.

  Subsequently, regeneration from the recovered BA to BN was performed in the same manner as in Example 1. As a result, as shown in Table 3, the test No. When 7 to 8 were performed, BN produced 5.5 mmol and 2.6 mmol, respectively. In all experiments, the only by-product was water, yield was about 90% or more, and selectivity was almost 100%.

  As for the solid-liquid coexisting substance after the test, each liquid and solid was separated in the same manner as in Example 1, and BN having a purity of 98% or more was recovered.

  A second DBC production reaction was performed using the BN thus regenerated. The reaction conditions were the same as in Example 1, and a small amount of new BN was added to BN obtained by regeneration with unreacted BN so that the amount of BN was 50 mmol. As a result, as in the first time, it was confirmed that DBC was obtained in a high yield, and the amount of BA produced as a by-product was almost the same as DBC, and no other by-products were detected. .

  Even in the case where the monohydric alcohol is 1-butanol and the product is DBC, it is possible to reduce most of the BN conventionally required for the production of DBC, and to reduce the amount of BA that has been disposed of by 90% or more. became. Furthermore, when regenerating and distilling from BA to BN, the temperature is increased to about 180 ° C., so this heat is used by supplying it through a heated pipe when reusing it for DBC production. be able to.

(Example 5)
In the catalyst preparation in the regeneration from the recovered BA to BN, the metal elements supported on the SiO ₂ carrier are V, Re, W, and Nb, and the reagent is also a special grade manufactured by Kanto Kagaku. Similarly, NO. 9 to 16 tests were conducted.

  From the results of Table 5, it was found that even when the metal elements were V, Re, W, and Nb, the yield was around 90% and the selectivity was almost 100%.

(Example 6)
In the catalyst preparation by regeneration from the recovered BA to BN, NO. Is the same as in Example 1 except that the final Mo loading is as shown in Table 6 and the reaction pressure is only 1 MPa. The test of 17-22 was done. As a result, as shown in Table 6, it was found that the Mo loading amount was high at 0.1 to −1 mmol, and about 0.6 mmol was a suitable loading amount. On the other hand, when the loading amount was excessively increased, the activity was relatively lowered. This is because the Mo oxide on the SiO ₂ carrier becomes a large aggregate because the Mo oxide is loaded in a large amount. Inferred.

In Examples 1 to ₃ , the MoO ₃ / SiO ₂ catalyst was used in the regeneration reaction from BA to BN, but any one or two of W, Re, V, and Nb were used as the metal element. Even after using a catalyst obtained by adjusting the aqueous solution so that the final concentration is 0.5 mmol / g, impregnating with SiO ₂ , drying at 110 ° C. for about 6 hours, and calcining at 500 ° C. for about 3 hours. The effect of was obtained. Also, the carrier in addition to SiO _2, even with _{CeO 2, ZrO 2, CeO 2} -ZrO 2, similar effects were obtained.

(Example 7)
In the regeneration process from the recovered BA to BN, the same procedure as in Example 1 was performed except that o-xylene (20 ml) was used instead of mesitylene as the organic solvent and the reaction pressure was only 1 MPa. As a result, as shown in Table 7 (NO.23), 3.2 mmol of BN was generated. By-product was only water, yield was 42.7%, and selectivity was almost 100%.

  From the above results, it was found that even when o-xylene was used as the organic solvent, the reaction was performed in a high yield. Similar effects were obtained with m-xylene and p-xylene.

(Comparative Example 1)
In the DMC production reaction, the same procedure as in Example 1 was carried out except that acetonitrile (AN, 300 mmol) was introduced as a wettable powder and allowed to react at 150 ° C. for 24 hours.

From the results shown in Table 8, when AN is used, the amount of DMC produced is about 1/10 lower than that of BN, and the DMC yield based on methanol is highest at 8.2% at 0.5 MPa. From this, it was found that the present invention is more efficient. The amount of by-product acetamide (AA) produced was almost the same as that of DMC, and no other by-products were detected.
Next, as in Example 1, 200 ml of hexane was added to the solid-liquid coexisting substance after each test, and the mixture was stirred, extracted with a solvent, and filtered through a filter to separate a liquid and a solid. The liquid contains DMC, unreacted AN, methanol, and hexane, and the solid contains AA and CeO ₂ . Since the liquid component after solvent extraction with hexane has a melting point and boiling point of AN of -45 ° C and 82 ° C, respectively, DMC and AN cannot be separated by distillation, so it is once cooled to -30 to 0 ° C. It is possible to separate the precipitated DMC. Thereafter, when the temperature is increased to about 70 ° C. and distillation is performed, a mixture of methanol and hexane can separate the unreacted AN, and the unreacted AN can be reused for the DMC formation reaction. Since the concentration of methanol contained in the mixture is high, it is difficult to reuse it as a solvent for extraction, and it is necessary to dispose of it. In addition, AA and CeO ₂ in the fixed component are dissolved in 100 ml of acetone and filtered through a filter to separate CeO ₂ , AA and acetone, and AA and acetone are separated by distillation heated to about 70 ° C. As a result, AA having a purity of 95% or more was recovered.

  Subsequently, regeneration from the collected AA to AN was performed in the same manner as in Example 1. As a result, as shown in Table 8, test no. When 24-25 was performed, there was almost no reaction. This is considered that since the solid catalyst is basic while AA is acidic, AA poisons the active sites on the solid catalyst and the reaction does not proceed.

  Therefore, since the AA produced as a by-product could not be dehydrated and the AN could not be regenerated, the second DMC formation reaction was performed by adding new AN to the unreacted AN so that the amount of AN was 300 mmol. The reaction was conducted in the same manner as in Example 1 except that the reaction was performed at 150 ° C. for 24 hours. As a result, as in the first time, the amount of DMC produced was reduced to about 1/10 compared to the case of BN, and the DMC yield based on methanol reached 1.7% at 0.5 MPa. It was.

(Comparative Example 2)
Except that the regeneration step from BA to BN (and the separation step after the regeneration step) is not performed, test NO. 26-27 was performed. As a result, DMC with a purity of 96% or more and BA with a purity of 97% or more could be recovered, but a large amount of by-produced BA had almost no use and was treated as industrial waste. In addition, at least 7.7 or 4.3 mmol of BN was newly required for the second DMC production reaction, which led to an increase in raw material costs.

(Comparative Example 3)
In the regeneration reaction from the recovered BA to BN, a catalyst as shown in Table 10 was prepared and used as the catalyst, and the same reaction as in Example 1 was performed except that the reaction pressure was only 1 MPa. As a result, as shown in Table 10 (NO. 28 to 29), the amount of BN produced was small and the activity was low.

1 first reaction tower, 2 first extraction tower, 3 first distillation tower, 4 second extraction tower, 5 second distillation tower, 6 catalyst regeneration tower, 7 second reaction tower, 8 catalyst separation tower, 9 third distillation Tower, 10 CO ₂ pressure blower, 11 CO ₂ , 12 monohydric alcohol, 13 2-cyanopyridine, 14 solid catalyst, 15 reaction solution, 16 alkane, 17, 21 extract, 18 solid phase material, 19 carbonate ester, 20 Unreacted 2-cyanopyridine, 22 used solid catalyst, 23 2-picolinamide, 24 hydrophilic solvent, 25 solid catalyst, 26 used solid catalyst, 27 organic solvent, 28 unreacted 2-picolinamide, 29 water, 30 Filtration tower, 31 methyl picolinate, 32 methyl carbamate, 33 alkane and unreacted monohydric alcohol

Claims (13)

In the presence of either one or both of CeO ₂ and ZrO ₂ and benzonitrile, a monohydric alcohol and carbon dioxide are reacted to produce a carbonate and water, and the benzonitrile and the production. A first reaction step of producing benzamide by hydration reaction with purified water;
After separating the benzamide from the first reaction step, the metal oxide of one or more metal species of molybdenum, tungsten, rhenium, vanadium, niobium is SiO ₂ , TiO ₂ , By dehydration reaction by heating in the presence of a catalyst supported on one or more of the catalyst supports of CeO ₂ , ZrO ₂ , Al ₂ O ₃ , and C and in the presence of an organic solvent , Having a second reaction step to regenerate to benzonitrile,
Benzonitrile regenerated in the second reaction step is used in the first reaction step. Separation of the benzamide from the first reaction step is
The carbonate ester, benzamide, unreacted benzonitrile discharged from the first reaction step, and the solid catalyst are subjected to solvent extraction with alkane and then separated into solid and liquid, and the liquid phase carbonate ester, unreacted benzonitrile, And separating the alkane and the solid catalyst and benzamide in solid phase;
Separating the carbonate, unreacted benzonitrile, and alkane in the liquid phase after the solid-liquid separation, and
The solid catalyst and benzamide after the solid-liquid separation are extracted with a hydrophilic solvent, followed by solid-liquid separation, and separated into a liquid phase benzamide and a hydrophilic solvent and a solid phase solid catalyst.
Furthermore, after the second reaction step,
A step of filtering the catalyst in which the benzonitrile, unreacted benzamide, and metal oxide supported on the catalyst support are discharged from the process to separate the catalyst in which the solid phase metal oxide is supported on the catalyst support. When,
Separating each of the benzonitrile, benzamide, organic solvent, and water remaining after the separation,
The method for producing a carbonate ester according to claim 1, wherein the separated benzonitrile is used in the first reaction step.   The method for producing a carbonate according to claim 2, further comprising a step of regenerating the separated solid catalyst, wherein the regenerated catalyst is used in the first reaction step.   The method for producing a carbonate ester according to claim 2 or 3, wherein the alkane used in the solvent extraction is hexane.   The method for producing a carbonate ester according to any one of claims 2 to 4, wherein the hydrophilic solvent is acetone. Catalyst support wherein the metal oxide is supported _is a SiO _2, TiO _2, any one of claims 1 to 5, characterized in that CeO 2, one of ZrO ₂ 1 or two or more The manufacturing method of carbonate ester of description. The method for producing a carbonate ester according to claim 6, wherein the catalyst carrier is SiO ₂ .   The said metal oxide is a molybdenum oxide, The manufacturing method of the carbonate ester of any one of Claims 1-7 characterized by the above-mentioned.   The method for producing a carbonate ester according to any one of claims 1 to 8, wherein the monohydric alcohol is methanol and dimethyl carbonate is produced as a carbonate ester.   The method for producing a carbonate ester according to any one of claims 1 to 8, wherein the monohydric alcohol is ethanol and diethyl carbonate is produced as a carbonate ester.   The said organic solvent is mesitylene, The manufacturing method of the carbonate ester of any one of Claims 1-10 characterized by the above-mentioned.   The method for producing a carbonate ester according to any one of claims 1 to 11, wherein a dehydrating agent is used in the second reaction step. It is a manufacturing apparatus of the carbonate ester used for the manufacturing method of any one of Claims 1-12,
Means for pressurizing carbon dioxide;
In the presence of either one or both of CeO ₂ and ZrO ₂ , and benzonitrile, a monohydric alcohol and carbon dioxide are reacted to form a carbonate and water, and the benzonitrile and the above A first reaction means for producing benzamide by a hydration reaction with the produced water;
Carbonate ester, benzamide, unreacted benzonitrile, and the solid catalyst discharged by the means are subjected to solvent extraction with alkane, followed by solid-liquid separation, and liquid phase carbonate ester, unreacted benzonitrile, and alkane, Means for separating the solid catalyst and benzamide in solid phase;
Means for separating the carbonate, unreacted benzonitrile, and alkane in the liquid phase after the solid-liquid separation;
The solid catalyst and benzamide after the solid-liquid separation are extracted with a hydrophilic solvent and then separated into solid and liquid, and separated into a liquid phase benzamide and a hydrophilic solvent and a solid phase solid catalyst,
The separated benzamide is a metal oxide of any one or more of molybdenum, tungsten, rhenium, vanadium, niobium, or a metal oxide of SiO ₂ , TiO ₂ , CeO ₂ , ZrO ₂ , Al ₂ O ₃ , A second reaction means for producing a benzonitrile by dehydration by heating in the presence of a catalyst supported on any one or two or more catalyst carriers of C and in the presence of an organic solvent;
A means for filtering the catalyst having the benzonitrile, unreacted benzamide, and metal oxide supported on the catalyst carrier discharged by the means, and separating the catalyst having the solid phase metal oxide supported thereon;
And means for separating benzonitrile, benzamide, organic solvent, and water remaining after the separation,
An apparatus for producing a carbonate ester, comprising means for conveying the separated benzonitrile to the first reaction means.

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