JP6349787B2 - Method for producing carbonate ester - Google Patents

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. organism relates to the production how the carbonate and recycled back to the original wettable powder. In particular, as a wettable powder using 2-cyanopyridine, by-product is concerned the manufacture how the carbonate is a 2-picolinamide.

Carbonic acid ester is a general term for compounds in which one or two of hydrogen atoms of carbonic acid 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 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 a very useful compound such as an alkylating agent, a carbonylating agent, a solvent, etc., or as a raw material for a lithium ion battery electrolyte, a lubricant oil raw material, and a deoxidizer 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 is an environmentally friendly and superior method that can be expected to reduce carbon dioxide, which is expected to be reduced as a global warming gas, with little use or generation of corrosive substances such as hydrochloric acid. It is. However, as described in Patent Document 1, effective use of by-produced ethylene glycol is a major problem. Further, since it is difficult to safely transport ethylene, which is a raw material for ethylene oxide, and ethylene oxide, there is a restriction 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 carbon dioxide 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.

  In contrast, 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, 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 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) Research using 2,2-dimethoxypropane (Non-patent Document 5) has been reported. However, this method has a characteristic that the reaction proceeds as the reaction pressure increases, the reaction yield is very low at low pressure, and high productivity cannot be obtained unless the pressure is extremely high. 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 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.

  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, high pressures such as 300 atmospheres and 60 atmospheres as described in Non-Patent Documents 4 and 5 are unnecessary, and the reaction is promoted under a pressure close to normal pressure. The effect was found for the first time (see Patent Documents 3 and 4). 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. Further, benzamide itself, which is a main by-product, has been found to have many uses and has led to the invention.

WO2004 / 014840 Publication EP365,083 JP 2009-132673 A JP 2010-77113 A JP 2012-162523 A JP 2009-213975 A

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  The present inventor has further studied the types of wettable powder for further improvement in the production amount of carbonate ester. By using 2-cyanopyridine, compared with acetonitrile and benzonitrile, the production of carbonate ester is further improved. It was found that the amount and production rate were greatly improved, the reaction was likely to proceed under a relatively low pressure close to normal pressure, and the reaction rate was very fast (see Patent Document 5). However, the treatment method and utilization method of by-product 2-picolinamide have not been studied.

  Nitriles such as 2-cyanopyridine, which are wettable powders in the present invention, are generally used in many applications such as solvents, synthetic resins, dyes, and pharmaceutical intermediates. Among them, 2-cyanopyridine is a material used as a raw material for pharmaceuticals and agricultural chemicals, and is a material used as a starting material when synthesizing a pyridine and piperidine derivative at the 2-position.

  However, the use of 2-picolinamide produced by the reaction of 2-cyanopyridine with water is limited to some intermediates for medical and agricultural chemicals. Therefore, in the production of a carbonic acid ester using 2-cyanopyridine as a wettable powder, it is desirable to regenerate 2-picolinamide as a by-product into 2-cyanopyridine and reuse it. High (because it is considered difficult to recycle as a wettable product when a by-product is generated) and high in yield (if the yield is low, the amount of 2-picolinamide remaining increases and separation from 2-cyanopyridine) It became clear that it was a challenge to do (because of the increased throughput and higher load).

  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 necessary, and it is limited to acrylonitrile and benzonitrile (Non-patent Document 9).

  On the other hand, there is also nitrile synthesis by amide dehydration, and there are two reported cases of 2-picolinamide dehydration, both of which use homogeneous catalysts, so after purification after synthesis, separation of the catalyst, etc. The problem is that the process is complicated, a strong reagent (strong acid or strong base) is used, and a large amount of by-products are generated, so that the environmental load is large (Non-Patent Documents 10 and 11).

  Further, as a dehydration reaction of an amide using a heterogeneous catalyst, Patent Document 3 describes a catalyst for a dehydration reaction of a primary amide and a method for producing a nitrile using the same. The catalyst is a solid catalyst in which vanadium is supported on hydrotalcite, and it is said that the primary amide is also active as an aromatic amide such as benzamide, an amide having a heterocyclic ring, and an aliphatic amide, and 3-picolinamide, Although there is a description regarding 4-picolinamide, there is no description regarding 2-picolinamide. This is because the amide is generally more stable than the nitrile, and the dehydration reaction of the amide is slower, and the intramolecular between the hydrogen atom of the amide group and the nitrogen heteroatom in the picolinamide molecule. Although it causes hydrogen bonding, 2-picolinamide is thought to be because it has a particularly large intramolecular hydrogen bond, becomes a stable substance, and dehydration reaction does not proceed easily.

As described above, a monohydric alcohol and carbon dioxide are reacted in the presence of a solid catalyst to synthesize a carbonate ester in a high yield and regenerate from 2-picolinamide as a by-product to 2-cyanopyridine. There have been no reports on ester production methods and equipment.
Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to directly synthesize a carbonate ester by reacting alcohol and carbon dioxide in the presence of a solid catalyst and a wettable powder 2-cyanopyridine. The water produced is reacted with 2-cyanopyridine and removed from the reaction system to promote the formation of carbonate ester, while the 2-picolinamide produced as a by-product is separately subjected to a dehydration reaction to increase the selectivity. By regenerating to 2-cyanopyridine at high rate and reusing it as a wettable powder, the above reaction system as a whole is highly efficient, and outside the system, the environmental impact becomes only the product carbonate and by-product water. and to provide a small manufacturing how the carbonate.

  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 3, Patent Document 4). Furthermore, by using 2-cyanopyridine, compared with the case of acetonitrile or benzonitrile, the production amount and production rate of carbonate ester are greatly improved, and the reaction easily proceeds under a relatively low pressure close to normal pressure. And it discovered that reaction rate was very quick, and patent document 5 is carrying out patent publication. 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 to use 2-cyanopyridine, which is fast and has few excellent by-products, having excellent properties as a wettable powder in this production method.

  Thus, as a solid catalyst, attention was paid to the elements and composition constituting the catalyst, and as a result, a solid catalyst having an acid-base complex function having a relatively low acidity and a relatively high basicity was added to the wettable powder. When cyanopyridine is used, the reaction to produce 2-picolinamide by hydration reaction in the presence of a solid catalyst is promoted, and dehydration from the reaction system proceeds efficiently, and the reaction equilibrium is constrained even under relatively low pressure and mild conditions. It was found that the carbonate ester can be obtained in a high yield without undergoing the above.

Furthermore, it has been found that among such catalysts, an oxide composed of one or more of CeO ₂ , ZrO ₂ , CeO ₂ and ZrO ₂ is very effective.

  Next, in order to solve the problem that, when 2-cyanopyridine is used as a hydrating agent, 2-picolinamide as a by-product is difficult to effectively use because of limited use, The renaturation reaction to pyridine was studied earnestly.

  Conventionally, the dehydration reaction of 2-picolinamide has been carried out only with a homogeneous catalyst, but a heterogeneous catalyst that suppresses by-products and can be easily separated from raw materials and products existing in a liquid phase in the reaction system. It was investigated.

  First, when a dehydration reaction of 2-picolinamide was performed with a heterogeneous catalyst using vanadium, which is considered effective in the production of benzamide, it was found that 2-cyanopyridine was hardly produced as expected. It was.

  Therefore, the inventors have shown that since the pyridine ring in 2-picolinamide is weakly basic, if an acidic catalyst is used, the pyridine ring may be adsorbed and poisoned at the active site of the catalyst, causing a decrease in activity. Therefore, a catalyst using a basic metal as an active species was studied.

As a result, it has been found that the use of a catalyst in which an alkali metal having basic properties is supported on a catalyst carrier is highly active, leading to the invention.
The gist of the present invention is as follows.

(1) in the presence of one of CeO ₂ and ZrO ₂ or both of the solid catalyst and 2-cyanopyridine, to generate a carbonate and water by reacting monohydric alcohol and carbon dioxide, said 2 A first reaction step of generating 2-picolinamide by a hydration reaction between cyanopyridine and the generated water;
By separating the 2-picolinamide from the first reaction step, the 2-picolinamide is dehydrated by heating in the presence of an alkali metal-supported catalyst and in the presence of an organic solvent. A second reaction step for regenerating to 2-cyanopyridine,
The catalyst carrying an alkali metal in the second reaction step is a catalyst carrier obtained by calcining a catalyst carrier composed of one or more of SiO ₂ , CeO ₂ , and ZrO ₂ to remove moisture. Above, a catalyst carrying one or more alkali metal oxides,
A method for producing a carbonate, wherein 2-cyanopyridine regenerated in the second reaction step is used in the first reaction step.
(2) One or both of CeO ₂ and ZrO ₂ , a monohydric alcohol, carbon dioxide, and 2-cyanopyridine are mixed and reacted to produce a carbonate and 2-picolinamide. A first reaction step,
The carbonate ester, 2-picolinamide, unreacted 2-cyanopyridine, and the solid catalyst discharged from the first reaction step are subjected to solvent extraction with alkane and then subjected to solid-liquid separation to obtain a liquid phase carbonate ester, the reaction of 2-cyanopyridine, and the alkanes, a first separation step of separating the said solid catalyst and 2-picoline amide solid phase,
A second separation step of separating the liquid phase carbonate after solid-liquid separation in the first separation step, unreacted 2-cyanopyridine, and alkane, respectively;
The solid-phase solid catalyst and 2-picolinamide after the solid-liquid separation in the first separation step are extracted with a hydrophilic solvent and then solid-liquid separated, and the liquid-phase 2-picolinamide and the hydrophilic solvent are mixed with the solid phase. A third separation step of separating into a solid catalyst of
The 2-picolinamide separated in the third separation step is subjected to a dehydration reaction by heating in the presence of an alkali metal-supported catalyst and in the presence of an organic solvent to produce 2-cyanopyridine. Reaction process of
A catalyst supporting 2-cyanopyridine, unreacted 2-picolinamide, and alkali metal discharged from the second reaction step is filtered to separate a catalyst supporting a solid phase alkali metal. Separation process of
And a fifth separation step of separating 2-cyanopyridine, 2-picolinamide, an organic solvent, and water remaining after separation in the fourth separation step,
The method for producing a carbonate according to (1), wherein 2-cyanopyridine separated in the fifth separation step is used in the first reaction step.
(3) The method according to (2), further comprising a step of regenerating the solid catalyst separated in the third separation step, wherein the regenerated catalyst is used in the first reaction step. A method for producing carbonate ester.
(4) The method for producing a carbonate ester according to (2) or (3), wherein the alkane used in the solvent extraction is hexane.
(5) The method for producing a carbonate ester according to any one of (2) to (4), wherein the hydrophilic solvent is acetone.
(6) the catalyst support, characterized in that a SiO ₂ (1) ~ (5) method for producing a carbonic ester according to any one of.
( 7 ) The alkali metal oxide according to any one of (1) to ( 6 ), wherein the alkali metal oxide is one or more selected from the group consisting of K, Na, Rb, and Cs. A method for producing carbonate ester.
( 8 ) The method for producing a carbonate ester according to any one of (1) to ( 7 ), wherein the monohydric alcohol is methanol and dimethyl carbonate is produced as a carbonate ester.
( 9 ) 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.
( 10 ) The method for producing a carbonate ester according to any one of (1) to ( 9 ), wherein the organic solvent is mesitylene.
( 11 ) The method for producing a carbonate ester according to any one of (1) to ( 10 ), wherein a dehydrating agent is used in the second reaction step.
( 12 ) Unreacted monohydric alcohol remains in the first reaction step, and carbonate, 2-picolinamide, and unreacted one discharged from the first reaction step in the first separation step. The monohydric alcohol, unreacted 2-cyanopyridine, and the solid catalyst were subjected to solvent extraction with alkane and then solid-liquid separation to obtain a liquid phase carbonate ester, unreacted monohydric alcohol, unreacted 2-cyanopyridine, and The method for producing a carbonate ester according to any one of (2) to ( 11 ), wherein the alkane is separated into the solid catalyst and 2-picolinamide in solid phase.
( 13 ) In the first reaction step, methyl picolinate or methyl carbamate is produced as a by-product, and in the first separation step, a carbonate ester discharged from the first reaction step, 2-picolinamide, Unreacted 2-cyanopyridine, methyl picolinate, methyl carbamate, and the solid catalyst were subjected to solvent extraction with alkane and then separated into solid and liquid to obtain a liquid phase carbonate ester, unreacted 2-cyanopyridine, methyl picolinate. , Methyl carbamate, and alkane, and the solid catalyst and 2-picolinamide in solid phase are separated, and the method for producing a carbonate ester according to any one of (2) to ( 11 ).
( 14 ) In the first reaction step, unreacted monohydric alcohol remains, and methyl picolinate and methyl carbamate are generated as by-products, and in the first separation step, the first reaction step Of the carbonic acid ester, 2-picolinamide, unreacted monohydric alcohol, unreacted 2-cyanopyridine, methyl picolinate, methyl carbamate, and the solid catalyst discharged from the solvent after solid-liquid separation with alkane And separated into liquid phase carbonate ester, unreacted monohydric alcohol, unreacted 2-cyanopyridine, methyl picolinate, methyl carbamate, and alkane, and the solid catalyst and 2-picolinamide in solid phase. The method for producing a carbonate ester according to any one of (2) to ( 11 ), wherein:

  In the method and apparatus for producing a carbonate of the present invention, a monohydric alcohol and carbon dioxide are reacted in the presence of a solid catalyst and 2-cyanopyridine to produce a carbonate in a high yield, and 2-picoline produced as a by-product The amide can be regenerated to 2-cyanopyridine with high selectivity and high yield, and the regenerated 2-cyanopyridine can be reused for the production of carbonate. 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 an example of an apparatus for manufacturing a carbon ester. It is a chart which shows the state of each substance in each process of the manufacturing apparatus of FIG. It is another example of an apparatus for producing a carbon ester. It is a chart which shows the state of each substance in each process of the manufacturing apparatus 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.
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 either one or both of a solid catalyst of CeO ₂ and ZrO ₂ and 2-cyanopyridine. This produces a carbonate ester.

In this step, when monohydric alcohol and carbon dioxide are reacted, water is also generated in addition to the carbonic ester, but 2-picolinamide is generated by hydration reaction with the generated water due to the presence of 2-cyanopyridine. And it becomes possible to promote the production | generation of carbonate ester by removing or reducing the produced | generated water from a reaction system.

  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.

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. Further, CeO ₂ and ZrO ₂ solid solutions and composite oxides are basically based on a mixing ratio of CeO ₂ and ZrO ₂ of 50:50, but the mixing ratio can be changed as appropriate.

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 2-cyanopyridine, which are by-produced during the synthesis of the carbonate ester. Therefore, although both the carbonate ester synthesis reaction and the hydration reaction proceed on the surface of the catalyst, the hydration of 2-cyanopyridine is carried out even under low pressure conditions which are unfavorably balanced for the carbonate ester synthesis reaction. The reaction proceeds under catalysis, and the water generated as a by-product from the synthesis reaction of the carbonate ester is rapidly eliminated from the catalyst surface, so that the equilibrium of the synthesis reaction of the carbonate ester shifts to the production system and the reaction pressure is low. It is inferred that the carbonate ester synthesis reaction is allowed to have a high reaction rate without being subjected to equilibrium constraints even under mild conditions. Conversely, 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, so that the hydration reaction with 2-cyanopyridine is difficult to proceed. Therefore, it is considered that the carbonate ester can be produced only in a state close to the equilibrium constraint, and as a result, the productivity is not increased under high pressure.

If it explains from the viewpoint of reaction of 2-cyanopyridine regarding the said guess, 2-cyanopyridine will receive the catalytic action of the solid catalyst in this invention in a liquid phase, and a hydration reaction will be accelerated | stimulated on the surface. 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, it is presumed that the hydration reaction starts to occur under high pressure because the main reaction proceeds predominantly at high pressure.

As for the production method of the catalyst of the present invention, for example, first, in the case of CeO ₂ , cerium acetylacetonate hydrate, cerium hydroxide, cerium sulfate, cerium acetate, cerium nitrate, ammonium cerium nitrate, It can be prepared by firing various cerium compounds such as 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 dinitrate, zirconium sulfate and the like are mixed with air. 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 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.

Under the conditions where the conversion rate of monohydric alcohol is 100% and no by-products such as methyl picolinate and methyl carbamate are produced, after the reaction, carbonate ester as the main product, 2-picolinamide as the by-product, It becomes a solid catalyst such as 2-cyanopyridine and CeO _{2 in the} reaction. In order to separate them, first, a liquid component (carbonate ester, 2-cyanopyridine) is extracted in an extraction step using an organic solvent, and can be separated from a fixed component (2-picolinamide and a fixed catalyst) and 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. Next, the separated liquid component contains carbonate ester, 2-cyanopyridine, and an organic solvent. The melting point and boiling point of each substance are 4 ° C and 90 ° C (dimethyl carbonate). , −43 ° C. and 128 ° C. (diethyl carbonate), −41 ° C. and 167 ° C. (dipropyl carbonate), 25 ° C. or lower and 207 ° C. (dibutyl carbonate), etc., and 24 ° C. and 215 ° C. (2-cyanopyridine) , -95 ° C. 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. In addition, 2-picolinamide and solid catalyst separated as solid components can be separated from the solid catalyst and a filter by extracting only 2-picolinamide 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 2-picolinamide dissolved in the hydrophilic solvent can be separated by distillation, and the by-produced 2-picolinamide can be purified with high purity.

  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 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.

  In addition, 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 more, by-products such as methyl picolinate and methyl carbamate are formed. In the case where it has been formed, the melting point and boiling point are -97 ° C and 65 ° C (methanol), -114 ° C and 78 ° C (ethanol), -126 ° C and 97 ° C (1-propanol) for monohydric alcohols, respectively. ), −90 ° C. and 117 ° C. (1-butanol) and the like, and 103 ° C. and 233 ° C. (methyl picolinate), 52 ° C. and 177 ° C. (methyl carbamate). By gradually raising the temperature to about ℃, monohydric alcohol, organic solvent, carbonate, methyl carbamate, methyl picolinate, and 2-sia Can separate and pyridine, followed by cooling to 30 to 100 ° C., the solidified picolinate by the filter, it can be separated from 2-cyanopyridine.

  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.

Next, in the second reaction step of the present invention, 2-picolinamide produced as a by-product in the first reaction step is separated from the system after the carbonic acid ester formation reaction, and then 2-cyanopyridine is converted by dehydration reaction. To manufacture.
In the production of 2-cyanopyridine, 2-picolinamide is dehydrated in the presence of a catalyst supporting a basic metal oxide and an organic solvent to produce 2-cyanopyridine.

Here, as the catalyst used in the present invention, a catalyst in which an oxide of a basic alkali metal (K, Li, Na, Rb, Cs) is generally supported on a substance serving as a catalyst carrier can be used. As a result of examining various supports, it was found that particularly high performance was exhibited when a catalyst supported on SiO ₂ , CeO ₂ , ZrO ₂ , or CeO ₂ —ZrO ₂ was used.

This is because the pyridine ring in 2-picolinamide is weakly basic, so if an acidic catalyst is used, the pyridine ring may be adsorbed and poisoned at the active site of the catalyst, causing a decrease in activity. A metal having basic properties is preferable. In addition, as a result of intensive studies by the present inventors, it is particularly preferable to use a catalyst in which an alkali metal is supported on SiO ₂ in a highly dispersed state, and one or more alkali metals may be supported.

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.

On the other hand, 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 fired 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 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. 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 carrier 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 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.

An example of the method for producing the catalyst of the present invention is as follows. When the support is SiO ₂ , a commercially available powder or spherical SiO ₂ can be used, and 100 mesh (0.15 mm) is used so that the active metal can be uniformly supported. In order to adjust the particle size below and remove moisture, pre-baking is preferably performed in air at 700 ° C. 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 2-cyanopyridine produced is improved. Specifically, a surface area of 300 m ² / g or more is 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 preferable that the surface area of the catalyst after manufacture is 150 m ² / g or more. The active metal oxide can be supported by an impregnation method such as an incipient wetness method or an evaporation to dryness method.

  The metal salt used as a precursor should just be water-soluble, and if it is an alkali metal, various compounds, such as carbonate, hydrogencarbonate, chloride salt, nitrate, silicate, can be used, for example. The carrier can be used as a catalyst by impregnating a carrier with a basic metal precursor aqueous solution, followed by drying and firing. The firing temperature is preferably 400 to 600 ° C., although it depends on the precursor used.

  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.

  Next, the method for producing 2-cyanopyridine using the catalyst of the present invention is not particularly limited as a reaction mode, and is not limited to a batch reactor, a semi-batch reactor, a continuous tank reactor or a tube reactor. Any flow reactor may be used. Moreover, any of a fixed bed, a slurry bed, etc. can be applied to the catalyst.

  In the second reaction step of producing (regenerating) 2-cyanopyridine from 2-picolinamide produced as a by-product in the production method of the present invention, as well as the by-product water produced by the dehydration reaction, as in the step of producing the carbonate. It is desirable to carry out the reaction while removing it. For example, it is desirable to carry out the reaction while removing by-product water by installing a dehydrating agent such as reflux, distillation or zeolite in the system. As a result of intensive studies by the present inventor, using a Soxhlet extraction tube and a cooler, zeolite (molecular sieve) or calcium hydride is installed in the extraction tube as a dehydrating agent, and a catalyst, 2-picolinamide, organic in the reaction tube It is possible to improve the production amount of 2-cyanopyridine by adding a solvent and reacting under reflux. 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, mesitylene and the like, and mesitylene is particularly preferable.

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.

  In the dehydration reaction of 2-picolinamide, it is considered that picolinic acid and pyridine are by-produced by the decomposition of 2-picolinamide as described above. However, after the dehydration reaction using the catalyst of the present invention, Only a small amount of 2-picolinamide, 2-cyanopyridine as a product, water as a by-product, and an organic solvent are formed, and the above-mentioned by-products are hardly generated.

  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 110 ° C. (2-picolinamide), 24 ° C. (2-cyanopyridine), −45 ° C. (organic solvent such as mesitylene), and the boiling point is 143 ° C. (2-picolinamide), Since it is 212 ° C. (2-cyanopyridine), 100 ° C. (water), 165 ° C. (organic solvent, for example, mesitylene), the reaction phase is all liquid except for the solid catalyst, and is partially vaporized. 2-picolinamide, by-product water, and organic solvent are cooled by a cooler, and by-product water is adsorbed by a dehydrating agent, and 2-picolinamide and the organic solvent return to the reaction tube and contribute to the reaction again.

<Carbonate production equipment>
Next, the production apparatus for carbonate ester will be described in more detail with reference to specific examples. 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 by-products of methyl picolinate and methyl carbamate are not generated.

In the first reaction step, one or both of the solid catalyst (solid phase) of CeO ₂ and ZrO ₂ , monohydric alcohol 12 (liquid phase), 2-cyanopyridine 13 (liquid) Phase), and carbon dioxide (gas phase) is charged through the pressure 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. Moreover, although 2-cyanopyridine uses a new product at the start of the reaction, it is purified by unreacted 2-cyanopyridine 20 (liquid phase) purified in the first distillation column 3 and the third distillation column 9. 2-Cyanopyridine regenerated from picolinamide 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.

  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 2-cyanopyridine 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 2-picolinamide easily react with the monohydric alcohol, so the yield of the carbonate ester is low. Tend to be. 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, 2-cyanopyridine), it is desirable to set optimum conditions as appropriate. Since a preferable reaction temperature is 100 to 150 ° C., it is desirable to preheat the raw material (monohydric alcohol, 2-cyanopyridine) with steam or the like before the first reaction column.

  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 with 2-cyanopyridine 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 poor. Become. 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).

  The 2-cyanopyridine used for the hydration reaction is desirably 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. When it introduce | transduces in less than 0.1 time, since there is little 2-cyano pyridine which contributes to a hydration reaction, there exists a possibility that the yield of carbonate may worsen. 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, since the amount of monohydric alcohol and 2-cyanopyridine 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 2-cyanopyridine, optimal conditions are appropriately set. It is desirable.

  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 2-cyanopyridine (liquid phase) and 2-picolinamide (solid phase), solid catalyst (solid phase), and organic solvent (liquid phase). 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 2-cyanopyridine, and alkane. In the first distillation column 3, the boiling point of each substance is 90 ° C. (for example, in the case of dimethyl carbonate), 215 ° C. (2-cyanopyridine), and 69 ° C. (for example in the case of hexane). The product is separated into carbonate 19 as a product, unreacted 2-cyanopyridine 20, and alkane 16 used for extraction.

  On the other hand, the solid phase 18 separated in the first extraction tower 2 contains 2-picolinamide 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 2-picolinamide 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 2-picolinamide and a hydrophilic solvent is distilled in the second distillation column 5, and the boiling point of each substance is 143 ° C. (2-picolinamide) and 57 ° C. (for example, in the case of acetone). To be separated.

  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 2-picolinamide 23 (solid phase) purified in the second distillation column 5 is transferred to the second reaction column 7 for regeneration to 2-cyanopyridine, but in order to avoid clogging in the piping, the piping Is preferably heated to 103 ° C. or higher, which is the melting point, with low pressure steam or the like.

  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. After separation of the catalyst, the boiling points of the substances present in the system are different as described above. Therefore, by distilling in the third distillation column 9, 2-cyanopyridine, an organic solvent, 2-picolinamide, water The organic solvent 27 and 2-picolinamide 28 can be recycled for the dehydration reaction of 2-picolinamide. The purified 2-cyanopyridine 13 can be reused in a reaction for producing a carbonate ester.

In the second reaction step, 2-cyanopyridine is produced in the second reaction column 7 by the dehydration reaction of 2-picolinamide. The carbonate ester production apparatus is an apparatus for producing 2-cyanopyridine by dehydrating 2-picolinamide in the presence of a catalyst supporting a basic metal oxide 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. Although the temperature of the 2nd reaction column 7 can be changed according to the reaction form, in the case of reflux using a Soxhlet extraction tube and a cooler, it is preferable to heat the periphery of the reaction tube to 160 to 200 ° C. In the carbonate ester production apparatus, it is desirable to remove by-product water generated by the dehydration reaction. For example, reflux, distillation, dehydrating agents such as zeolite are installed in the system, and by-product water is removed. 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 is installed in the extraction tube as a dehydrating agent, and a catalyst, 2-picolinamide, organic in the reaction tube It is possible to improve the production amount of 2-cyanopyridine by adding a solvent and reacting under reflux. 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 110 ° C. (2-picolinamide), 24 ° C. (2-cyanopyridine), −45 ° C. (organic solvent such as mesitylene), and the boiling point is 143 ° C. (2-picolinamide), Since it is 212 ° C. (2-cyanopyridine), 100 ° C. (water), 165 ° C. (organic solvent, for example, mesitylene), the reaction phase is all liquid except for the solid catalyst, and is partially vaporized. 2-picolinamide, by-product water, and organic solvent are cooled by a cooler, and by-product water is adsorbed by a dehydrating agent, and 2-picolinamide 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 103 ° C. or higher, which is the melting point of 2-picolinamide, 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 distilling in the third distillation column 9, 2-cyanopyridine 13, organic solvent 27, 2-picoline The amide 28 and water 29 can be easily separated, and the organic solvent 27 and 2-picolinamide 28 can be returned to the previous stage of the third reaction column 7 and recycled. Further, the purified 2-cyanopyridine 13 can be reused in the first reaction tower 1 for producing a carbonate ester.

  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 where unreacted monohydric alcohol remains and byproducts of methyl picolinate 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 ester, unreacted 2-cyanopyridine, alkane, and monohydric alcohol. Contains methyl carbamate and methyl picolinate. The boiling point of each substance in the first distillation column 3 is 90 ° C. (for example, dimethyl carbonate), 215 ° C. (2-cyanopyridine), 69 ° C. (for example, hexane), 65 ° C. (for example, methanol), Utilizing the fact that it is 177 ° C (methyl carbamate) and 233 ° C (methyl picolinate), it was distilled by gradually increasing the temperature to about 180 ° C, and was used as a product, carbonate 19, The mixture is separated into a mixture 33 of alkane and unreacted monohydric alcohol 33 and methyl carbamate 32. In addition, after distillation, cooling to about 30 to 100 ° C. solidifies methyl picolinate having a melting point of 103 ° C., so that it can be solid-liquid separated with a filter or the like, and unreacted 2-cyanopyridine 20 Can be separated into methyl picolinate 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 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 stir bar, the above solid catalyst (1 mmol), methanol (100 mmol) and 2-cyanopyridine (2-CP, 50 mmol) were introduced into a 190 ml autoclave (reactor), and about 5 g of CO ₂ in the autoclave. After purging air three times, a predetermined amount of CO ₂ was introduced and pressurized. The autoclave was heated to 120 ° 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 120 ° 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 the methanol-based DMC yield was 58% at 1 MPa and 86% at 5 MPa. The amount of 2-picolinamide (2-PA) produced as a by-product was almost the same as DMC, and no other by-products were detected.

Here, the yield based on methanol (alcohol) was calculated by the following equation because the stoichiometric ratio was alcohol: carbonate = 2: 1.

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. Liquids, DMC, 2-CP, methanol, hexane, the solid, include 2-PA and CeO _2. The liquid component after solvent extraction with hexane can be separated into DMC, 2-CP, hexane and methanol by distillation that gradually increases the temperature to about 120 ° C., and DMC with a purity of 96% or more can be recovered. It was. In addition, 2-PA and CeO ₂ in the solid component are dissolved in 200 ml of acetone and then filtered through a filter to separate CeO ₂ , 2-PA and acetone, and 2-PA and acetone are separated by distillation. As a result, 2-PA having a purity of 97% or more was recovered.

Subsequently, the recovery from recovered 2-PA to 2-CP 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 carry the Na as the alkali metal, finally _Na 2 CO ₃ as Na amount of metal supported is 0.5 mmol / g (manufactured by Kanto Kagaku, special grade) was used to adjust the aqueous solution, SiO ₂ Impregnated. Thereafter, about 6 hours drying at 110 ° C., and calcined at 500 ° C. for about 3 hours _to obtain a Na ₂ O / SiO 2 catalyst. Therefore, a magnetic stir bar, the above catalyst (0.1 g), 2-PA produced as a byproduct of DMC generation, and mesitylene (20 ml) were introduced into a test tube, and molecular sieve 4A (pre-dried at 300 ° C. for 1 hour) was filled. A Soxhlet extractor and a Liebig condenser were connected, the temperature of the condenser 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. When 1-2 was performed, 2-CP produced | generated 26.6 and 37.8 mmol, respectively. In all experiments, water was the only byproduct, yield was 90%, and selectivity was 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 2-CP, water, unreacted 2-PA, and mesitylene. The liquid component is separated into 2-CP, water, unreacted 2-PA, and mesitylene by distillation that gradually raises the temperature to about 180 ° C., and 2-CP having a purity of 98% or more is recovered. I was able to. The separated unreacted 2-PA and mesitylene can be reused again in the 2-PA dehydration reaction.

  A second DMC formation reaction was performed using 2-CP regenerated in this manner. The reaction conditions were the same, and a small amount of new 2-CP was added to 2-CP that had been regenerated and 2-CP that had not been reacted in the first reaction so that the amount of 2-CP was 50 mmol. did. As a result, as in the first time, it was confirmed that DMC was obtained in a high yield, and the amount of 2-PA produced as a by-product was almost the same as DMC, and other by-products were not detected at all. There wasn't.

  From the above results, at the start of the reaction, 50 mmol of new 2-CP is required, but by regenerating from separated unreacted 2-CP and by-produced 2-PA to 2-CP for reuse. Conventionally, most of 2-CP necessary for generating DMC can be reduced. In addition, although 2-PA may be used as an intermediate for medicines and agrochemicals, the amount used is not so much, and it was possible to reduce more than 90% of the place where the disposal cost was high. Furthermore, when regenerating and distilling from 2-PA to 2-CP, the temperature is increased to about 180 ° C., so when reusing it for DMC production, this is supplied through a heated pipe. Heat can be used.

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

  From the results in Table 2, it was confirmed that diethyl carbonate (DEC) was obtained at a DEC yield of 50% at 1 MPa and 81% at 5 MPa, although not as high as DMC. The amount of 2-PA produced as a by-product was almost the same as 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. Liquids, DEC, 2-CP, ethanol, hexane, the solid, include 2-PA and CeO _2. The liquid component after solvent extraction with hexane can be separated into DEC, 2-CP, hexane, and ethanol by distillation that gradually increases the temperature to about 130 ° C., and DEC with a purity of 96% or more can be recovered. It was. In addition, 2-PA 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 2-PA and acetone are separated by distillation. As a result, 2-PA having a purity of 97% or more was recovered.

  Subsequently, regeneration from the recovered 2-PA to 2-CP was performed in the same manner as in Example 1. As a result, as shown in Table 2, test no. When 3-4 were performed, 2-CP produced | generated 21.8 and 39.1 mmol, respectively. In all experiments, the byproduct was only water, yield was 90% or more, and selectivity was 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 2-CP having a purity of 98% or more could be recovered.

  Using the 2-CP regenerated in this way, a second DEC generation reaction was performed. The reaction conditions were the same as in Example 1, and a small amount of new 2-CP was added to 2-CP obtained by regeneration with unreacted 2-CP so that the amount of 2-CP was 50 mmol. did. As a result, as in the first time, it was confirmed that DEC was obtained in a high yield, and the amount of 2-PA produced as a by-product was almost the same as DEC, and other by-products were not detected at all. There wasn't.

  Even when the monohydric alcohol is ethanol and the product is DEC, it is possible to reduce most of the 2-CP required to produce DEC and reduce 2-PA, which has been disposed of, by 90% or more. It has become possible. Furthermore, when regenerating and distilling from 2-PA to 2-CP, the temperature is raised to about 180 ° C., so when reusing it for DEC production, this is supplied through a heated pipe. Heat can be used.

(Example 3)
Example 1 was repeated 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 was confirmed that the DPC yield based on 1-propanol was 30.8% at 1 MPa and 45% at 5 MPa, although not as much as DMC in the case of dipropyl carbonate (DPC). . The amount of 2-PA 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. Liquids, DPC, 2-CP, 1-propanol, hexane, the solid, include 2-PA and CeO _2. The liquid component after solvent extraction with hexane is separated into DPC, 2-CP, hexane, and 1-propanol by distillation that gradually increases the temperature to about 170 ° C., and DPC with a purity of 96% or more is recovered. I was able to. In addition, 2-PA 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 2-PA and acetone are separated by distillation. As a result, 2-PA having a purity of 97% or more was recovered.
Subsequently, regeneration from the recovered 2-PA to 2-CP 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, 15.2 and 21.5 mmol of 2-CP were produced, respectively. In all experiments, the byproduct was only water, yield was 90% or more, and selectivity was 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 2-CP having a purity of 98% or more could be recovered.

  A second DPC generation reaction was performed using 2-CP regenerated in this manner. The reaction conditions were the same as in Example 1, and a small amount of new 2-CP was added to 2-CP obtained by regeneration with unreacted 2-CP so that the amount of 2-CP was 50 mmol. did. As a result, as in the first time, it was confirmed that DPC was obtained in a high yield, and the amount of 2-PA produced as a by-product was almost the same as DPC, and other by-products were not detected at all. There wasn't.

  Even in the case where the monohydric alcohol is 1-propanol and the product is DPC, it is possible to reduce most of 2-CP required for the production of DPC. More reductions were possible. Furthermore, when regenerating and distilling from 2-PA to 2-CP, the temperature is raised to about 180 ° C., so when reusing it for DPC production, this is supplied through a heated pipe. Heat can be used.

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 29.0% at 1 MPa and 40.6% at 5 MPa, although not as high as DMC in the case of dibutyl carbonate (DBC). It was done. The amount of 2-PA 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 includes DBC, 2-CP, 1-butanol, and hexane, and the solid includes 2-PA and CeO ₂ . The liquid component after solvent extraction with hexane first separates hexane and 1-butanol by distillation that gradually raises the temperature to about 120 ° C., and then cools to about 0 ° C. As a result, DBC having a purity of 96% or more was recovered. In addition, 2-PA 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 2-PA and acetone are each distilled. The 2-PA having a purity of 97% or more was recovered.

  Subsequently, regeneration from the recovered 2-PA to 2-CP 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, 14.1 and 20.3 mmol of 2-CP were produced, respectively. In all experiments, the byproduct was only water, yield was 90% or more, and selectivity was 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 2-CP having a purity of 98% or more could be recovered.

  A second DBC formation reaction was performed using 2-CP regenerated in this manner. The reaction conditions were the same as in Example 1, and a small amount of new 2-CP was added to 2-CP obtained by regeneration with unreacted 2-CP so that the amount of 2-CP was 50 mmol. did. As a result, as in the first time, it was confirmed that DBC was obtained in a high yield, and the amount of 2-PA produced as a by-product was almost the same as DBC, and other by-products were not detected at all. There wasn't.

  Even in the case where the monohydric alcohol is 1-butanol and the product is DBC, it is possible to reduce most of 2-CP required for the production of DBC in the past, and 90% of 2-PA, which has been disposed of, is discarded. More reductions were possible. Furthermore, when regenerating from 2-PA to 2-CP and distilling, the temperature is increased to about 180 ° C., so when reusing it for DBC production, it is supplied through a heated pipe. Heat can be used.

(Example 5)
In the catalyst preparation in the regeneration from the recovered 2-PA to 2-CP, the examples except that the alkali metal supported on the SiO ₂ carrier is K, Rb, Cs, and the reagent is a special grade manufactured by Kanto Chemical. No. 1 as well as NO. 9-14 tests were conducted.

  From the results of Table 5, it was found that when the alkali metal was K, Rb, or Cs, the yield was around 90% and the selectivity was 100%.

(Example 6)
In catalyst preparation in the regeneration from recovered 2-PA to 2-CP, Na ₂ CO ₃ (manufactured by Kanto Chemical Co., Ltd.) was made so that the total amount of Na metal loading and K metal loading was finally 0.5 mmol / g. , Special grade) and K ₂ CO ₃ (manufactured by Kanto Chemical Co., Ltd., special grade) were used to adjust the aqueous solution by changing the molar ratio 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 _{Na 2 O-K 2 O /} SiO 2 catalyst. NO. 2 is the same as in Example 1 except that a Na ₂ O—K ₂ O / SiO ₂ catalyst is used. 15-22 tests were conducted. As a result, as shown in Table 6, 2-CP was produced at any molar ratio, the byproduct was only water, the yield was around 90%, and the selectivity was 100%. From the above results, it was found that the amount of alkali metal used can be changed according to the market price.

(Example 7)
In the catalyst preparation in the regeneration from recovered 2-PA to 2-CP, NO is the same as in Example 1 except that the final amount of supported Na metal is as shown in Table 7 and the reaction pressure is only 1 MPa. . 15-22 tests were conducted. As a result, as shown in Table 7, it was found that the amount of Na supported was high at 0.1 to 1 mmol, and about 0.5 mmol was a suitable supported amount. On the other hand, it is confirmed that when the loading amount is too large, the activity is lowered. This is because the structure of the SiO ₂ carrier is changed due to the loading of a large amount of Na oxide, and the surface area is greatly reduced. It was assumed that the oxide was also a large aggregate.

In Examples 1 to 3, the Na ₂ O / SiO ₂ catalyst was used in the regeneration reaction from 2-PA to 2-CP, but any one of Na, K, Rb, and Cs was used as the alkali metal. A catalyst obtained by adjusting an aqueous solution so that the final or two types are 0.5 mmol / g is impregnated in SiO ₂ , dried at 110 ° C. for about 6 hours, and calcined at 500 ° C. for about 3 hours. Even if it used, the same effect was acquired. Also, the carrier in addition to SiO _2, even with _{CeO 2, ZrO 2, CeO 2} -ZrO 2, similar effects were obtained.

(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 in Table 8, when AN is used, the amount of DMC produced is about 1/10 lower than that of 2-CP, and the DMC yield based on methanol is 8.2% at 0.5 MPa. The best results indicate 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 distillation is performed by raising the temperature to about 70 ° C., a mixture of methanol and hexane and unreacted AN can be separated. 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 31-32 were 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, similarly to the first time, the amount of DMC produced was reduced to about 1/10 compared to the case of 2-CP, and the DMC yield based on methanol was the highest at 8.0% at 0.5 MPa. It became.

(Comparative Example 2)
Test NO. 2 was performed under the same conditions as in Example 1 except that the regeneration step from 2-PA to 2-CP and the separation step after the regeneration step were not performed. 34-35 was performed. As a result, DMC having a purity of 96% or more and 2-PA having a purity of 97% or more could be recovered. However, 2-PA had almost no use and was treated as industrial waste. In addition, the second DMC production reaction newly required at least 29.2 or 42.0 mmol of 2-CP, which led to an increase in raw material costs.

(Comparative Example 3)
In the regeneration reaction from the recovered 2-PA to 2-CP, SiO ₂ (size of 100 mesh or less and pre-calcined at 700 ° C. for about 1 hour as a catalyst (carried by Fuji Silysia, CARiACT, G-6, surface area: 535 m ² / g) was used, and the same procedure as in Example 1 was performed except that the reaction pressure was only 1 MPa. As a result, as shown in Table 10 (NO. 36), 2-CP produced only 0.05 mmol, and the activity was very low.

(Comparative Example 4)
In the regeneration reaction from recovered 2-PA to 2-CP, the same as in Example 1 except that 1 mmol of Na ₂ CO ₃ (manufactured by Kanto Chemical Co., Ltd.) is used as the catalyst and the reaction pressure is only 1 MPa. I made it. As a result, as shown in Table 10 (NO. 37), 2-CP was not produced at all.

(Comparative Example 5)
In the regeneration reaction from recovered 2-PA to 2-CP, the same as in Example 1 except that 1 mmol of K ₂ CO ₃ (manufactured by Kanto Chemical Co., Ltd., special grade) is used as the catalyst, and the reaction pressure is only 1 MPa. I made it. As a result, as shown in Table 10 (NO. 38), 2-CP was not produced at all.

(Comparative Example 6)
In the regeneration reaction from recovered 2-PA to 2-CP, the same procedure as in Example 1 was performed except that 1 mmol of Rb ₂ CO ₃ (manufactured by Kanto Chemical Co., Inc.) was used as the catalyst and the reaction pressure was only 1 MPa. . As a result, as shown in Table 10 (NO. 39), 2-CP was hardly generated.

(Comparative Example 7)
In the regeneration reaction from recovered 2-PA to 2-CP, the same as Example 1 except that only 1 mmol of Cs ₂ CO ₃ (manufactured by Kanto Chemical Co., 4N) was used as the catalyst, and the reaction pressure was only 1 MPa. I made it. As a result, as shown in Table 10 (NO. 40), 2-CP produced only 0.01 mmol and was very low in activity.
From the above results, it was found that a catalyst having an alkali metal oxide supported on a SiO ₂ carrier is effective for the regeneration from 2-PA to 2-CP.

(Comparative Example 8)
In the regeneration reaction from recovered 2-PA to 2-CP, an aqueous solution is prepared using CaCO ₃ (manufactured by Kanto Chemical Co., Ltd., special grade) so that the final amount of supported Ca metal is 0.5 mmol / g in catalyst preparation. Prepared 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 CaO / SiO ₂ catalyst. The same procedure as in Example 1 was performed except that a reaction pressure was set to 1 MPa only using a CaO / SiO ₂ catalyst. As a result, as shown in Table 11 (NO. 41), 2-CP produced only 0.11 mmol and was very low in activity.

(Comparative Example 9)
In the regeneration reaction from recovered 2-PA to 2-CP, an aqueous solution is prepared using BaCO ₃ (manufactured by Kanto Chemical Co., Ltd., special grade) so that the final amount of supported Ba metal is 0.5 mmol / g in the catalyst preparation. Prepared 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 BaO / SiO ₂ catalyst. The same procedure as in Example 1 was performed except that a BaO / SiO ₂ catalyst was used and the reaction pressure was only 1 MPa. As a result, as shown in Table 11 (NO. 42), 2-CP produced only 0.13 mmol, and the activity was very low.
From the above results, it can be confirmed that the catalyst supporting the alkaline earth metal oxide that is basic as well as the alkali metal oxide has low activity, and the catalyst supporting the alkali metal oxide on SiO ₂ is effective. I found out that

(Comparative Example 10)
In the regeneration reaction from recovered 2-PA to 2-CP, an aqueous solution was prepared using NH ₄ VO ₃ (manufactured by Sigma-Aldrich) so that the amount of V metal supported was finally 0.5 mmol / g in catalyst preparation. Was adjusted 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 V ₂ O 5 / SiO ₂ catalyst. The same procedure as in Example 1 was conducted except that a V ₂ O ₅ / SiO ₂ catalyst was used and the reaction pressure was only 1 MPa. As a result, as shown in Table 11 (NO. 43), 2-CP produced only 0.11 mmol, and the activity was very low at the same level as in the case of only SiO _{2 in} Comparative Example 2.

  From the above results, it was found that even when a V-type catalyst having high activity in the dehydration reaction of benzamide was used for the dehydration reaction of 2-picolinamide, the reaction hardly proceeded.

(Example 8)
In catalyst preparation by regeneration from recovered 2-PA to 2-CP, CeO ₂ (manufactured by 1st rare element, HS, surface area: 74 m ² / g) is sized to 100 mesh or less on the support, and about 500 ° C. The same procedure as in Example 1 was performed except that the pre-fired material was used for 3 hours, the metal supported on the carrier was Cs, and the reaction pressure was only 1 MPa. As a result, as shown in Table 12 (NO. 44), 11.2 mmol of 2-CP was generated. By-product was only water, yield was 38.0%, and selectivity was 100%.

Example 9
In catalyst preparation by regeneration from recovered 2-PA to 2-CP, ZrO ₂ (manufactured by 1st rare element, HS, surface area: 88 m ² / g) is sized to 100 mesh or less on the support, and about 500 ° C. The same procedure as in Example 1 was performed except that the pre-fired material was used for 3 hours, the metal supported on the carrier was Cs, and the reaction pressure was only 1 MPa. As a result, as shown in Table 12 (NO. 45), 10.5 mmol of 2-CP was produced. The byproduct was only water, yield was 35.6%, and selectivity was 100%.

(Example 10)
Since CeO ₂ —ZrO ₂ solid solution is used as a support in the catalyst preparation in the regeneration from recovered 2-PA to 2-CP, Ce (NO ₃ ) ₃ (manufactured by Kanto Chemical) and Zr (NO ₃ ) ₄ (Kanto) (Chemical) was dissolved in a solution of Ce at 20 atomic% to introduce an aqueous NaOH solution to form a precipitate. The precipitate was filtered and washed with water at 1000 ° C. in an air atmosphere for 3 hours. After firing, a powdered solid solution (surface area: 65 m ² / g) was obtained. This solid solution is sized to 100 mesh or less, pre-baked at 500 ° C. for about 3 hours, the metal supported on the carrier is Cs, and the reaction pressure is only 1 MPa, as in Example 1. did. As a result, as shown in Table 12 (NO. 46), 12.3 mmol of 2-CP was produced. By-product was only water, yield was 41.7%, and selectivity was 100%.

From the above results, it was found that it is effective to use CeO ₂ , ZrO ₂ , or CeO ₂ —ZrO ₂ as a support as a catalyst for regeneration and fixation from 2-PA to 2-CP.

(Example 11)
In the regeneration step from the recovered 2-PA to 2-CP, 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 13 (NO. 47), 9.5 mmol of 2-CP was generated. By-product was only water, yield was 32.2%, and selectivity was 100%.

From the above results, even when o-xylene is used as the organic solvent, as shown in Comparative Examples 3 to 10, only the SiO ₂ carrier, only the alkali metal (carbonate), alkaline earth metal-supported SiO ₂ catalyst, V system It was found that the reaction was higher in yield than the catalyst. Similar effects were obtained with m-xylene and p-xylene.

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 (14)

In the presence of one or both of the solid catalyst of CeO ₂ and ZrO ₂ and 2-cyanopyridine, a monohydric alcohol and carbon dioxide are reacted to form a carbonate and water, and the 2-cyanopyridine and A first reaction step of generating 2-picolinamide by a hydration reaction with the generated water;
By separating the 2-picolinamide from the first reaction step, the 2-picolinamide is dehydrated by heating in the presence of an alkali metal-supported catalyst and in the presence of an organic solvent. A second reaction step for regenerating to 2-cyanopyridine,
The catalyst carrying an alkali metal in the second reaction step is a catalyst carrier obtained by calcining a catalyst carrier composed of one or more of SiO ₂ , CeO ₂ , and ZrO ₂ to remove moisture. Above, a catalyst carrying one or more alkali metal oxides,
A method for producing a carbonate, wherein 2-cyanopyridine regenerated in the second reaction step is used in the first reaction step. And one or both of the solid catalyst of CeO ₂ and ZrO _2, and monohydric alcohol, and carbon dioxide are reacted by mixing the 2-cyanopyridine, first to produce the carbonic acid ester and 2-picoline amide Reaction process of
The carbonate ester, 2-picolinamide, unreacted 2-cyanopyridine, and the solid catalyst discharged from the first reaction step are subjected to solvent extraction with alkane and then subjected to solid-liquid separation to obtain a liquid phase carbonate ester, A first separation step of separating the 2-cyanopyridine and alkane of the reaction into the solid catalyst and 2-picolinamide in solid phase;
A second separation step of separating the liquid phase carbonate after solid-liquid separation in the first separation step, unreacted 2-cyanopyridine, and alkane, respectively;
The solid-phase solid catalyst and 2-picolinamide after the solid-liquid separation in the first separation step are extracted with a hydrophilic solvent and then solid-liquid separated, and the liquid-phase 2-picolinamide and the hydrophilic solvent are solidified. A third separation step for separating into a solid catalyst of the phase;
The 2-picolinamide separated in the third separation step is dehydrated by heating in the presence of an alkali metal-supported catalyst and in the presence of an organic solvent to produce 2-cyanopyridine. Reaction process of
A catalyst supporting 2-cyanopyridine, unreacted 2-picolinamide, and alkali metal discharged from the second reaction step is filtered to separate a catalyst supporting a solid phase alkali metal. Separation process of
And a fifth separation step of separating 2-cyanopyridine, 2-picolinamide, an organic solvent, and water remaining after separation in the fourth separation step,
The method for producing a carbonate ester according to claim 1, wherein 2-cyanopyridine separated in the fifth separation step is used in the first reaction step.   The carbonate ester according to claim 2, further comprising a step of regenerating the solid catalyst separated in the third separation step, wherein the regenerated catalyst is used in the first reaction step. Production method.   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. The catalyst support method of producing a carbonic ester according to claim 1, characterized in that the SiO _2. The said alkali metal oxide is 1 type, or 2 or more types chosen from the group of K, Na, Rb, Cs, The manufacturing method of the carbonate ester of any one of Claims 1-6 characterized by the above-mentioned. . The method for producing a carbonate ester according to any one of claims 1 to 7 , 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 organic solvent method of producing a carbonic ester according to any one of claims 1 to 9, characterized in that mesitylene. The method for producing a carbonate ester according to any one of claims 1 to 10 , wherein a dehydrating agent is used in the second reaction step. Unreacted monohydric alcohol remains in the first reaction step, and carbonate ester, 2-picolinamide, unreacted monohydric alcohol discharged from the first reaction step in the first separation step, Unreacted 2-cyanopyridine and the solid catalyst are subjected to solvent extraction with alkane and then separated into solid and liquid, a liquid phase carbonate ester, unreacted monohydric alcohol, unreacted 2-cyanopyridine, and alkane; claim 2-11 method for producing carbonic acid ester according to any one of and separating the said solid catalyst and 2-picoline amide of the solid phase. In the first reaction step, methyl picolinate and methyl carbamate are produced as by-products, and in the first separation step, carbonate, 2-picolinamide, unreacted and discharged from the first reaction step are generated. 2-Cyanopyridine, methyl picolinate, methyl carbamate, and the solid catalyst were subjected to solvent extraction with alkane and then separated into solid and liquid, and the liquid phase carbonate ester, unreacted 2-cyanopyridine, methyl picolinate, carbamate methyl, and alkanes and claim 2-11 method for producing carbonic acid ester according to any one of and separating the said solid catalyst and 2-picoline amide of the solid phase. In the first reaction step, unreacted monohydric alcohol remains, and methyl picolinate and methyl carbamate are generated as by-products, which are discharged from the first reaction step in the first separation step. Carbonic acid ester, 2-picolinamide, unreacted monohydric alcohol, unreacted 2-cyanopyridine, methyl picolinate, methyl carbamate, and the solid catalyst were subjected to solid-liquid separation after solvent extraction with alkane. Separating into carbonic acid ester of phase, unreacted monohydric alcohol, unreacted 2-cyanopyridine, methyl picolinate, methyl carbamate, and alkane and solid catalyst and 2-picolinamide in solid phase The method for producing a carbonate ester according to any one of claims 2 to 11 .

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