RU2804510C2 - Method for producing aromatic nitrile compound and method for producing carbonate ether - Google Patents

Abstract

FIELD: organic chemistry.

SUBSTANCE: group of inventions is related to a method for producing an aromatic nitrile compound, which is 2-cyanopyridine, 3-cyanopyridine or 4-cyanopyridine. The method involves contacting an amide compound of 2-picolinamide, 3-picolinamide or 4-picolinamide with an alkali metal catalyst in a gas phase in a dehydration reaction. The group of inventions is also related to a method for producing a carbonate ester, containing the first stage, including production of a carbonate ester and water by reaction of an alcohol with carbon dioxide in presence of an aromatic nitrile compound, and hydration of an aromatic nitrile compound with the resulting water to form an aromatic amide compound; and a second step of separating the aromatic amide compound from the reaction system of the first step and then regenerating the aromatic amide compound to obtain an aromatic nitrile compound through the dehydration process specified above. In this case, at least part of the aromatic nitrile compound regenerated in the second stage of the reaction is used in the first stage of the reaction.

EFFECT: improvement in the method for producing an aromatic nitrile compound by reducing the reaction steps and increasing the dehydration rate to reduce the duration of the process. Additionally, the present invention implements a method for efficiently producing a carbonate ester by using the above-mentioned method for producing an aromatic nitrile compound.

14 cl, 3 dwg, 2 tbl, 7 ex

Description

TECHNICAL FIELD

[0001]

The present invention relates to a method for producing an aromatic nitrile compound such as cyanopyridine, and to a method for producing a carbonate ester.

BACKGROUND OF THE ART

[0002]

"Carbonate ester" is the common name for a compound produced by replacing one or both of the two hydrogen atoms in carbonic acid CO(OH) ₂ with an alkyl group or aryl group, and it has the structure RO-C(=O)-OR' ( R and R' represent a saturated hydrocarbon group or an unsaturated hydrocarbon group).

[0003]

Carbonate ester is used as an additive, such as a gasoline additive to improve the octane number and a diesel additive to reduce the number of particles in the exhaust gas. The carbonate ester is also used, for example, as an alkylating agent, carbonylating agent, solvent or the like. for the synthesis of resins or organic compounds such as polycarbonate, urethane, pharmaceuticals, agricultural chemicals or the like, lithium ion cell electrolytic solution material, lubricating oil material or oxygen scavenger material for inhibiting the rusting of boiler pipes. Thus, carbonate ester is a very useful compound.

[0004]

As a conventional method for producing carbonate ester, the method generally used is to directly react phosgene, used as a carbonyl source, with an alcohol. Phosgene used in this method is very harmful and highly corrosive, and therefore requires extreme care when handling, for example during transportation or storage. Monitoring, managing and maintaining safety of phosgene production equipment is costly. In addition, when produced using this method, the starting materials and catalysts contain halogen, such as chlorine, and the resulting carbonate ester contains a trace amount of halogen that cannot be removed by a simple purification step. When carbonate ester is used as a gasoline additive, light oil additive, or electronic equipment material, the halogen may be undesirably corrosive. For this reason, a thorough purification step is necessary to reduce the trace amount of halogen present in the carbonate ester to extremely low trace levels. In addition, recently administrative agencies have introduced strict administrative regulations and do not allow the creation of new production facilities using this method, since this method uses phosgene, which is very harmful to the human body. Accordingly, a new method for producing carbonate ester that does not use phosgene is urgently needed.

[0005]

There is also a known method for the direct synthesis of carbonate ester from alcohol and carbon dioxide using a heterogeneous catalyst. In relation to this process, research has been carried out on the use of 2-cyanopyridine or benzonitrile as a wettable powder to significantly increase the yield and productivity in the production of carbonate ester, to allow the reaction to proceed easily at near normal pressure, and to increase the rate of reaction (see .Patent documents 1 and 2). However, there is a problem regarding the processing method or use of benzamide or the like generated as a by-product.

For example, the use of benzamide, formed by the reaction between benzonitrile and water, is limited to certain pharmaceutical and agrochemical intermediates. Thus, the use of benzamide is limited to some extent. Therefore, when producing a carbonate ester using benzonitrile as a wettable powder, it is desirable to regenerate the by-product benzamide to produce benzonitrile and reuse it. The current problem is to carry out the regeneration reaction with high selectivity (because it is believed that if a by-product is formed, then reuse of benzonitrile as a wettable powder is difficult) and with high yield (because if the yield is low, benzamide remains in large quantities, which increases the amount of work, namely the load, to separate benzamide and benzonitrile from each other).

[0006]

In view of the above-described problems relating to the regeneration of benzamide or the like. to produce benzonitrile or the like, there is a known method for performing the above-described regeneration without using a strong reagent while suppressing the formation of a by-product (Patent Document 3).

However, according to this method, it takes 400 hours to form nitrile by dehydration of the amide compound, and therefore cannot be balanced, namely, cannot be used in combination with the carbonate ester synthesis reaction, which only requires 24 hours. Another problem with this method is that steps of extraction, infiltration, etc. are required to separate the catalyst into solid and liquid phases, resulting in a complex process having many steps.

DOCUMENTS KNOWN FROM THE STATE OF THE ART

PATENT DOCUMENTS

[0007]

Patent Document 1: Japanese Patent Open Publication No. 2010-77113

Patent Document 2: Japanese Patent Open Publication No. 2012-162523

Patent Document 3: WO 2015/099053

BRIEF DESCRIPTION OF THE INVENTION

PROBLEMS SOLVED BY THE INVENTION

[0008]

In view of the above-described problems of the prior art, it is an object of the present invention to provide a process enabling a dehydration reaction in which the desired compound can be selectively obtained in high yield while suppressing the formation of by-products during the regeneration of an aromatic amide compound such as pyridine carboamide to obtain cyanopyridine, representing the corresponding aromatic nitrile compound. Another object of the present invention is to provide a method for producing an aromatic nitrile compound in which the number of dehydration reaction steps can be reduced and the reaction rate can be significantly increased to reduce the reaction time.

It is yet another object of the present invention to apply the above-described method for producing an aromatic nitrile compound to a method for producing a carbonate ester to realize a method for producing a carbonate ester efficiently.

TOOLS FOR SOLVING PROBLEMS

[0009]

To solve the above-described problems, the inventors of the present invention conducted research on a method for producing an aromatic nitrile compound such as cyanopyridine by dehydrating an aromatic amide compound. The present inventors have investigated the dehydration reaction conditions of an aromatic amide compound and implemented a dehydration reaction process in which by bringing the aromatic amide compound in the form of a gas or mist into contact with a catalyst in the gas phase for a short time, the reaction rate can be significantly increased to reduce the reaction time. , and furthermore, the desired compound can be selectively obtained in high yield while suppressing the formation of by-products.

[0010]

According to the present invention described above, the regeneration rate of an aromatic amide compound to produce an aromatic nitrile compound through a dehydration reaction can be increased, and the dehydration reaction and the synthesis rate of carbonate ester from CO ₂ and alcohol using an aromatic nitrile compound can be realized as a group of efficient industrial processes. The inventors of the present invention have also carried out studies on the application of the above-described solution to the carbonate ester production method. As a consequence, also in the carbonate ester production process in which the carbonate ester is synthesized directly from alcohol and carbon dioxide, it has been confirmed that advantages are achieved if the aromatic nitrile compound is effectively regenerated in a contact step in which the aromatic amide compound is in the form of a gas or mist brought into contact with the catalyst in the gas phase for a short time. The following describes the essence of the present invention.

[0011]

(1) A method for producing an aromatic nitrile compound, including a dehydration reaction in which the aromatic amide compound is dehydrated,

wherein the method includes a contact step for bringing the aromatic amide compound into contact with the catalyst in the gas phase during a dehydration reaction.

(2) The method for producing an aromatic nitrile compound according to item (1), wherein the catalyst includes an alkali metal.

(3) The method for producing an aromatic nitrile compound according to item (1) or (2), wherein the aromatic amide compound includes at least a heteroarylamide compound, wherein the aromatic nitrile compound includes at least a heteroarylnitrile compound.

(4) The method for producing an aromatic nitrile compound according to item (3), wherein the heteroarylamide compound includes 2-picolinamide, and the heteroarylnitrile compound includes 2-cyanopyridine.

(5) The method for producing an aromatic nitrile compound according to any one of paragraphs (1) to (4), in which, at the contact step, an inert gas and/or a solvent in a vapor state is additionally brought into contact with the catalyst.

(6) The method for producing an aromatic nitrile compound according to item (5), wherein the inert gas includes at least nitrogen gas.

(7) The method for producing an aromatic nitrile compound according to item (5) or (6), in which the boiling point of the solvent at normal pressure is from 20 to 300°C.

(8) The method for producing an aromatic nitrile compound according to any one of (5) to (7), wherein the solvent is compatible with the aromatic amide compound.

(9) The method for producing an aromatic nitrile compound according to any one of items (5) to (8), wherein the solvent includes a pyridine compound and/or a cyclic ketone.

(10) The method for producing an aromatic nitrile compound according to any one of items (1) to (9), wherein in the contact step, the temperature at which the aromatic amide compound is brought into contact with the catalyst in the gas phase is 170° C. or higher but lower 300°C.

(11) The method for producing an aromatic nitrile compound according to any one of items (1) to (10), wherein the duration of contacting the aromatic amide compound with the catalyst in the gas phase is 0.001 sec or more but less than 10 sec.

(12) A process for producing a carbonate ester, comprising:

a first reaction step including: a carbonate ester production reaction in which the alcohol is reacted with carbon dioxide in the presence of an aromatic nitrile compound to produce a carbonate ester and water, and a hydration reaction in which the aromatic nitrile compound is hydrated with the resulting water to obtain an aromatic amide compound; And

a second reaction step in which the aromatic amide compound is separated from the reaction system of the first reaction step and then the aromatic amide compound is regenerated to obtain an aromatic nitrile compound through a dehydration reaction for dehydrating the aromatic amide compound, wherein the dehydration reaction has a contact step for bringing the aromatic amide compound into contact with catalyst in the gas phase,

wherein at least a portion of the aromatic nitrile compound recovered in the second reaction step is used in the first reaction step.

(13) The carbonate ester production method of item (12), wherein in the second reaction step, an aromatic nitrile compound is produced from an aromatic amide compound according to the aromatic nitrile compound production method of any one of items (2) to (11) to regenerate the aromatic nitrile compound.

(14) The carbonate ester production method according to item (12) or (13), wherein a catalyst comprising cerium oxide is used in the carbonate ester production reaction.

(15) The method for producing a carbonate ester according to any one of items (12) to (14), wherein the alcohol includes an alcohol containing 1 to 6 carbon atoms.

ADVANTAGES OF THE INVENTION

[0012]

According to the present invention, the production (regeneration) of an aromatic nitrile compound such as cyanopyridine from an aromatic amide compound such as pyridine carboamide (picolinamide, nicotinamide, etc.) and benzamide can be effectively carried out. Particularly, in the dehydration reaction of an aromatic amide compound for the above-described regeneration, the formation of by-products can be suppressed, the desired compound can be selectively obtained in high yield, and the reaction rate can be improved. Thus, according to the present invention, the duration of the dehydration reaction for regenerating an aromatic nitrile compound can be significantly reduced compared with conventional methods. In addition, by using a gas-phase reaction, the size of the reaction vessel can be reduced to a greater extent compared with the amide compound dehydration step using a conventional liquid-phase reaction. Thus, according to the present invention, the step of regenerating the corresponding aromatic nitrile compound from the aromatic amide compound can be easily implemented in industry.

In addition, according to the present invention, by producing the aromatic nitrile compound as described above, a method for efficiently producing carbonate ester can also be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]

In fig. 1 shows an example of a device for producing carbonate ester.

In fig. 2 schematically shows a cyanopyridine production apparatus that was used in working examples in which cyanopyridine was produced under elevated or normal pressure.

In fig. 3 schematically shows the apparatus for producing cyanopyridine which was used in the working examples in which cyanopyridine was prepared under reduced pressure.

OPTIONS FOR IMPLEMENTATION OF THE INVENTION

[0014]

Preferred embodiments of the present invention are described in detail below.

[0015]

<1. Method for producing aromatic nitrile compound>

In the method for producing an aromatic nitrile compound according to the present invention, an aromatic amide compound such as a pyridine carboamide (2-pyridine carboamide, 3-pyridine carboamide or 4-pyridine carboamide) is dehydrated in the gas phase and converted to an aromatic nitrile compound such as cyanopyridine. Particularly, in the method for producing an aromatic nitrile compound according to the present invention, for example, a dehydration reaction is caused by a contact step in which the aromatic amide compound is brought into contact with a catalyst bearing a base metal oxide in a gas phase, thereby obtaining an aromatic nitrile compound.

[0016]

[0017]

(Reaction substrate)

Examples of the aromatic amide compound used in the method for producing the aromatic nitrile compound include amide compounds having an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring and an anthracene ring or a heteroaryl ring. Among these aromatic amide compounds, an aromatic amide compound having a heteroaryl ring, i.e., is preferably used. heteroarylamide compound, examples of the heteroarylamide compound include amide compounds having a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, a pyrazole ring, an oxazole ring or the like.

Preferred specific examples of the heteroarylamide compound include those having a pyridine ring, such as the above-described pyridinecarboamide (2-pyridinecarboamide, 3-pyridinecarboamide and 4-pyridinecarboamide).

The aromatic nitrile compound obtained by the production method of the present invention is a dehydration reaction product corresponding to the above-described aromatic amide compound, as is clear from the reaction formula described above. Accordingly, particular examples of the aromatic nitrile compound obtained in the production method according to the present invention include a heteroarylnitrile compound. Preferred particular examples of the heteroarylnitrile compound include those having a pyridine ring such as cyanopyridine (2-cyanopyridine, 3-cyanopyridine and 4-cyanopyridine).

[0018]

(Catalyst)

In this regard, the catalyst used in the above-described dehydration reaction according to the present invention preferably includes an alkali metal oxide (K, Li, Na, Rb, Cs). Particularly, as the catalyst used in the above-described reaction, a catalyst comprising an oxide of at least one of Na, K, Rb and Cs (cesium) is preferably used. In addition, a substance generally used as a catalyst support can be used as the support for the above-described catalyst, but as a result of research on various supports, it is preferable to include SiO ₂ or ZrO ₂ .

[0019]

An example of a method for producing a catalyst used in the dehydration reaction of the present invention is described below. In the case where the support is SiO ₂ , commercially available powder or spherical SiO ₂ can be used, and it is preferable to adjust the particle size to, for example, 4.0 mm or less, so that the active metal can be carried evenly, and perform pre-heat treatment in air at 700°C for 1 hour to remove moisture. There are SiO ₂ products with different characteristics, but the higher the specific surface area the better, since the active metal can be highly dispersed and the amount of aromatic nitrile compound produced increases. In particular, the specific surface area is preferably 300 m ² /g or more. However, the specific surface area of the catalyst after preparation may be reduced to be less than the specific surface area of SiO ₂ alone due to interaction between SiO ₂ and the active metal or the like. In this case, the specific surface area of the catalyst after production is preferably 150 m ² /g or more. The metal oxide serving as the active substance can be transferred according to an impregnation method such as a moisture-capacity impregnation method and an evaporation drying method.

[0020]

It is sufficient if the metal salt which is the catalyst precursor is water-soluble, and if it is an alkali metal, then various compounds such as carbonate, hydrogen carbonate, chloride salt, nitrate and silicate can be used. The support is impregnated with an aqueous solution of the base metal precursor, followed by drying and heat treatment, then the resulting product can be used as a catalyst. The heat treatment temperature varies depending on the precursor used, but is preferably from 400 to 600°C.

[0021]

Moreover, as the catalyst used in the present invention, a catalyst in which only one or more alkali metal oxides are carried on a support consisting of one or both of SiO ₂ and ZrO ₂ is preferred, however, in addition to the above-described elements, the catalyst may contain an unavoidable impurity , mixed during the process of preparing a catalyst or the like. However, it is advisable to suppress the admixture of impurities as much as possible.

[0022]

In this regard, the catalyst used in the present invention, in which the metal oxide serving as the active substance is carried on a carrier, can be either in the form of a powder or a molded body, wherein in the case of a molded body, it can be any of spherical type, pellet type, cylindrical type, ring type, disc type, granular type, etc. In addition, the catalyst can be fixed to a support structure, such as a honeycomb carrier, and used.

[0023]

The size of the support is not limited, however, when using a spherical support, the average diameter of the catalyst particles (support diameter) is preferably from 0.01 to 8.0 mm, more preferably from 0.03 to 6.0 mm, and even more preferably from 0.05 to 5.0 mm. By using a catalyst whose support diameter is relatively larger than the average diameter (support diameter) of the catalyst particles used in the liquid-phase reaction as described above, a flow path of the reaction support in the gas-phase reaction is provided, and a high space velocity can be achieved. It should be noted that when using a fluidized bed in a gas phase reaction, it is preferable to use a catalyst with a relatively small particle diameter so that the catalyst can be mixed with a small amount of the gas stream, and that when using a fixed bed in a gas phase reaction, a relatively large particle diameter or shape is preferred, so that the occurrence of pressure losses can be prevented as far as possible.

Media diameter, i.e. average catalyst particle diameter refers to the average particle diameter of the entire catalyst, including the catalyst component and support. The catalyst support diameter value is measured based on the screening method: Test screening - General requirements specified in JISZ8815 or the like.

[0024]

In addition, the transfer amount of the catalyst can be suitably set, however, based on the total mass of the catalyst, the metal conversion transfer amount of active species such as alkali metal oxide is preferably 0.05 to 2.0 mmol/g, more preferably from 0.10 to 1.5 mmol/g and even more preferably from 0.30 to 1.0 mmol/g. In addition, the amount of catalyst used during the reaction can also be suitably set.

[0025]

(Reaction system and reaction vessel)

In the method for producing an aromatic nitrile compound according to the present invention, it is preferable to use a gas-phase reaction in which the amide compound in the form of a gas or mist is passed through a catalyst bed along with an inert gas, and a fixed-bed or fluidized-bed gas-phase reaction apparatus may be applied to it. Thus, in the contact step in which the aromatic amide compound is brought into contact with the catalyst in the gas phase, it is preferable to use the aromatic amide compound in a completely vaporized state, but the aromatic amide compound in a state in which the mist is partially included in the gas can also be used.

[0026]

It is advantageous to carry out the process for producing an aromatic nitrile compound by removing the by-product water through a dehydration reaction. The inventors of the present invention have made careful studies and found that, for example, when an evaporation chamber is attached to the top of the reaction tube in which the catalyst is placed, an aromatic amide compound is introduced into the evaporation chamber, and the amide compound passes through the catalyst layer in the gas phase within a short time , the amount of aromatic nitrile compound produced can be increased and the formation of by-product can be suppressed.

[0027]

(Inert gas)

In the above-described dehydration reaction, it is preferable to bring an inert gas into contact with the catalyst together with an aromatic amide compound in the gas phase. Particular examples of the inert gas used in the dehydration reaction include nitrogen gas and inert gases such as helium and argon, and nitrogen gas is preferably used. Flow rate, etc. inert gas is described below.

[0028]

(Solvent)

In the above-described dehydration reaction, a solvent may be used. Particularly, in the step of evaporating a high melting point aromatic amide compound, by premixing the aromatic amide compound with a solvent compatible therewith and supplying the mixture, the problem of clogging due to precipitation of the aromatic amide compound can be prevented. That is, it is preferable to use a solvent compatible with the aromatic amide compound as the dehydration reaction target. The solvent compatible with the aromatic amide compound includes not only a solvent that can be mixed with the aromatic amide compound in any ratio, but also a solvent that can dissolve the target aromatic amide compound only to a predetermined degree of solubility, in an amount at which the aromatic amide compound the amide compound may be dissolved to a concentration equal to or less than the upper limit of the degree of solubility at a given temperature. In addition, it is also preferable to evaporate and use the solvent in the dehydration reaction (contact step). The boiling point of the solvent evaporated and used in the above-described dehydration reaction is preferably 20 to 300°C, more preferably 80 to 250°C, and even more preferably 110 to 200°C at normal pressure.

[0029]

Particular examples of the solvent used in the dehydration reaction include a pyridine compound, a ketone compound, an ether compound, an ester compound and an alcohol, and preferably a pyridine compound, a ketone compound, etc. are used.

Examples of pyridine compound, i.e. compounds having a pyridine skeleton serving as a solvent include 2-alkylpyridine, 3-alkylpyridine and 4-alkylpyridine such as 4-methylpyridine and pyridine. In particular, in a dehydration reaction in which pyridine may be formed as a by-product, using a pyridine compound as a solvent under predetermined preferred conditions does not require the step of removing pyridine as a major by-product.

Moreover, examples of the ketone compound serving as a solvent include a cyclic ketone compound such as cyclopentanone, cyclohexane and acetone.

[0030]

As the solvent for the dehydration reaction, it is preferable to use a solvent consisting of only one or more substances selected from the above-described compounds, but a mixed solvent further containing another compound can also be used.

[0031]

(Dehydration reaction conditions including contact step)

As described above, the method for producing an aromatic nitrile compound comprises a contact step for bringing the aromatic amide compound into contact with a catalyst in the gas phase during a dehydration reaction.

In the contact stage, the temperature at which the aromatic amide compound, etc. brought into contact with the catalyst, preferably is 170°C or higher, but below 300°C. The temperature is, for example, 180°C or higher but lower than 290°C, or 190°C or higher but lower than 280°C, more preferably 210°C or higher but lower than 280°C, and even more preferably 220°C or above but below 260°C. It is believed that the temperature at which the aromatic amide compound, etc. brought into contact with the catalyst is equal, for example, to the temperature inside the reaction tube (reaction vessel) to which the catalyst is attached.

In addition, the duration of bringing the aromatic amide compound into contact with the catalyst during the contact step and in the case where an inert gas, solvent, etc. included together with the aromatic amide compound, the duration of bringing the mixed gas of these gas compositions into contact with the catalyst is preferably 0.001 seconds or more, or 0.005 seconds or more, for example 0.01 seconds or more but less than 10 seconds. The above-described catalyst contact time is more preferably 0.1 sec or more but less than 5 sec, and even more preferably 0.5 sec or more but less than 2 sec.

It should be noted that the catalyst contact time is the average duration during which the aromatic amide compound gas or the above-described mixed gas passes through the catalyst bed, and it is calculated by the formula: Catalyst contact time (sec) = Height of the catalyst bed in the reactor (cm ) ÷ Linear gas velocity in the reactor (cm/sec).

[0032]

In the contacting step, the molar ratio between the flow rate of the aromatic amide compound and the flow rate of the gas composition is preferably 1:0 to 1:200, more preferably 1:1 to 1:100, and even more preferably 1:1 to 1:20.

The space velocity (SV) of the entire gas component in the contact step is preferably 1000 to 50,000 (hr ^-1 ), more preferably 1,500 to 30,000 (hr ^-1 ), and even more preferably 2,000 to 25,000 (hr ^-1 ). In addition, when performing the contact step under reduced pressure, the space velocity (SV) of the entire gas component is preferably from 1000 to 1000000 (hr ^-1 ), more preferably from 1500 to 700000 (hr ^-1 ), and even more preferably from 1900 to 504000 ( hour ^-1 ).

[0033]

Regarding the dehydration reaction conditions, the pressure may range from elevated pressure (eg, 506.5 (kPa)) to reduced pressure (eg, 0.1 (kPa)), but is not particularly limited.

For example, the reaction pressure is 303.9 to 0.7 (kPa), preferably 202.6 to 0.9 (kPa), and more preferably 101.3 to 1.0 (kPa).

[0034]

In addition, it is preferable to dehydrate the aromatic amide compound when it is in liquid form before evaporation. When using a molecular sieve as a dehydrating agent, its type and shape are not particularly limited, but for example, spherical or granular molecular sieves 3A, 4A, 5A, etc., generally having high water absorption capacity, can be used. For example, ZEOLUM manufactured by Tosoh Corporation can be suitably used.

[0035]

(Example of a byproduct in a dehydration reaction)

[0036]

It is believed that in the dehydration reaction of an aromatic amide compound, pyridine is produced by-product through an aromatic carboxylic acid due to the decomposition of the above-described aromatic amide compound. However, almost no by-product such as pyridine shown in the above formula is generated in the reaction solution after the dehydration reaction using the contact step of the present invention.

[0037]

<2. Method for producing carbonate ester using an aromatic nitrile compound>

By using a gas phase contact step to regenerate an aromatic amide compound to produce an aromatic nitrile compound through a dehydration reaction, the reaction rate was successfully increased to significantly reduce the reaction time. Thus, it was possible to achieve a balance between the rate of regeneration of the aromatic amide compound to produce the aromatic nitrile compound through a dehydration reaction and the rate of synthesis of the carbonate ester from CO ₂ and alcohol using the aromatic nitrile compound, and it became possible to implement these reactions in a series of industrial processes. Accordingly, by applying this discovery to a carbonate ester production method, the inventors of the present invention have successfully developed the carbonate ester production method described below.

[0038]

(First stage of reaction)

The first reaction step in the carbonate ester production method according to the present invention includes a reaction in which the alcohol is directly reacted with carbon dioxide in the presence of a solid catalyst containing, for example, CeO ₂ (cerium oxide), etc., and an aromatic nitrile compound to obtain carbonate ester (reaction to produce carbonate ester).

[0039]

At this stage, when the alcohol is reacted with carbon dioxide, water is also produced in addition to the carbonate ester and by the hydration reaction of the aromatic nitrile compound present in the reaction system and the resulting water, an aromatic amide compound is obtained, and the resulting water can be removed from the reaction system system or restored. By effectively removing water from the reaction system in this manner, the production of carbonate ester can be promoted. For example, as shown in the formula below.

[0040]

[0041]

(Alcohol)

In this regard, any alcohol selected from one or more of a primary alcohol, a secondary alcohol and a tertiary alcohol can be used as the alcohol. For example, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, allyl alcohol, 2-methyl-1-propanol, cyclohexanemethanol, benzyl alcohol, ethylene glycol, 1,2-propanediol and 1,3-propanediol are preferably used due to high product yield and high reaction rate. In these cases, the resulting carbonate esters are respectively dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonane carbonate, diallyl carbonate, di-2-methylpropyl carbonate, dicyclohexane methyl carbonate, dibenzyl carbonate, ethylene carbonate, 1,2-propylene carbonate and 1 ,3-propylene carbonate.

In addition, in the first reaction step, it is preferable to use an alcohol containing 1 to 6 carbon atoms, and more preferably, an alcohol containing 2 to 4 carbon atoms is used. Particularly, when using a carbonate ester obtained as a starting material for a diaryl carbonate, the number of carbon atoms in the alcohol is preferably set in the above-described range.

In addition, in the first reaction step, a monohydric alcohol or a dihydric alcohol is preferably used.

[0042]

(Catalyst for carbonate ester production)

In addition, in the first reaction step of producing a carbonate ester, it is preferable to use one or both of CeO ₂ and ZrO ₂ as a solid catalyst. For example, it is preferable to use only CeO ₂ , only ZrO ₂ , a mixture of CeO ₂ and ZrO ₂ , a solid solution or complex oxide of CeO ₂ and ZrO ₂ or the like, and it is particularly preferable to use only CeO ₂ . The mixing ratio of CeO ₂ and ZrO ₂ in the solid solution or its complex oxide is typically 50:50, but can be adjusted accordingly.

[0043]

In this regard, the catalyst used in the first stage of the reaction may be either in the form of a powder or a shaped body, and in case of a shaped body, it may be any of spherical type, pellet type, cylindrical type, ring type, disk type, granular type, etc. .d.

[0044]

(Carbon dioxide)

As the carbon dioxide used in the present invention, not only carbon dioxide obtained as an industrial gas, but also carbon dioxide separated and collected from the exhaust gases of various product manufacturing plants, iron and steel plants, power plants, etc. can be used.

[0045]

(Solvent for the carbonate ester reaction)

In the carbonate ester reaction, it is preferable to use a solvent having a higher boiling point than the boiling point of the amide compound being produced. More preferably, the solvent in the carbonate ester reaction contains at least one of dialkylbenzene, alkylnaphthalene and diphenylbenzene. Particular examples include Barrel Process Oil B28AN and Barrel Process Oil B30 (manufactured by Matsumura Oil Co., Ltd.), each of which contains components including dialkylbenzene, alkylnaphthalene, diphenylbenzene, etc.

[0046]

(Distillation separation)

After this reaction, the carbonate ester as the main product, the aromatic amide compound as a by-product, the unreacted aromatic nitrile compound, and the solid catalyst such as CeO ₂ are separated by distillation, thereby capturing these products.

[0047]

(Second stage of reaction)

Then, in the second reaction step of the present invention, the aromatic amide compound produced by-product in the first reaction step is preferably separated from the system obtained after the carbonate ester reaction, and then the aromatic nitrile compound is obtained through a dehydration reaction. The second reaction step corresponds to the above-described method for producing an aromatic nitrile compound. Specifically, in the second step of the carbonate ester production reaction, an aromatic nitrile compound is produced from an aromatic amide compound in accordance with the method described above in the section relating to a method for producing an aromatic nitrile compound, thereby regenerating the aromatic nitrile compound. Accordingly, a detailed description of the second reaction step will be omitted.

[0048]

(Reuse of aromatic nitrile compound)

The aromatic nitrile compound recovered in the second reaction step can be reused in the first reaction step (hydration reaction).

[0049]

According to the present invention, as described above, by carrying out the dehydration reaction of the aromatic amide compound in the gas phase, the aromatic nitrile compound can be efficiently recovered from the aromatic amide compound while suppressing the formation of by-product. In addition, by fixing the catalyst in the reaction tube, the need for a solid-liquid separation step of the catalyst is eliminated, and the aromatic nitrile compound can be easily captured. Thus, in the present invention, it is possible to selectively regenerate an aromatic nitrile compound from an aromatic amide compound and promote a series of reactions by separating the corresponding components only by distillation without separating the catalyst into solid and liquid phases. Accordingly, an efficient process can be implemented, described in detail below.

[0050]

<3. Device for producing carbonate ester>

Below, by way of a particular example, a device for producing the carbonate ester used in the present invention is described in detail. In fig. 1 shows an example of a preferred device.

[0051]

(First stage of reaction)

At the first stage of the reaction, the starting substances, i.e. alcohol (1-propanol (PrOH); liquid phase), 2-cyanopyridine (2-CP; liquid phase) and carbon dioxide (CO ₂ ; liquid phase, can be supplied through an auxiliary pump) are continuously fed into the intermediate tank 1 using pipeline 31 for supplying raw materials, CO2 pumping pipeline 15 from the top of the CO ₂ capture column (CO ₂ pumping pipeline on the top side of the CO ₂ capture column), liquid pumping pipeline 19 from the top of the carbonate ester capture column (liquid pumping pipeline on the top side of the carbonate ester recovery column) and a liquid transfer line 21 from the top of the amide separation column (liquid transfer line on the top side of the amide separation column). This mixed feed solution is circulated between a carbonate ester reactor 2 of a flow-through fixed-bed type in which a solid catalyst (solid phase) consisting of one or both of CeO ₂ and ZrO ₂ is attached to a support material (first reaction part) , and the intermediate container 1 through the first reaction solution circulation line 11 and the second reaction solution circulation line 12 using a pump (not shown), thereby allowing the synthesis of dipropyl carbonate (DPrC). The reaction solution containing DPrC is continuously withdrawn from the second reaction solution circulation line 12 in the same amount as the amount of raw materials supplied to the intermediate vessel 1, collected using the line 13, and supplied to the DPrC recovery step. PrOH and CO ₂ are collected from the reaction solution and transferred to the buffer tank 1, respectively, through a liquid transfer line 19 from the top of the carbonate ester recovery column and a CO2 transfer line 15 from the top of the CO ₂ recovery column, thereby reusing them. At the beginning of this reaction, new 2-cyanopyridine is used, however, the 2-cyanopyridine recovered from 2-picolinamide is separated and purified in the amide separation column 6 and transferred to the intermediate vessel 1 through the upper liquid transfer line 21 from the top of the amide separation column, thereby reusing it.

[0052]

As a direct synthesis device for carbonate ester using CeO ₂ , ZrO ₂ etc. as the solid catalyst (carbonate ester reactor 2), any of the flow reactors such as a batch reactor, a semi-batch reactor, a continuous tank reactor and a tubular reactor can be used. If the catalyst is attached to the reactor, there is no need to filter and separate the catalyst. For this reason, a fixed bed reactor is preferred.

[0053]

(Reaction solution temperature)

The temperature of the reaction solution in the carbonate ester producing reactor 2 is preferably 50 to 300°C. If the temperature of the reaction solution is below 50° C., the reaction rate is low, the carbonate ester synthesis reaction and the hydration reaction with 2-cyanopyridine hardly occur, and the carbonate ester production efficiency is generally low. If the temperature of the reaction solution is above 300°C, the rate of each reaction is high, but the carbonate ester is easily decomposed or denatured, and 2-picolinamide easily reacts with alcohol. For this reason, carbonate ester yields are generally low. The temperature of the reaction solution is more preferably 100 to 150°C. However, since the ideal temperature of the reaction solution is believed to vary depending on the type and amount of solid catalyst and the amount and ratio of starting materials (alcohol and 2-cyanopyridine), it is advisable to set the optimal conditions appropriately. Since the preferred temperature of the reaction solution is 100 to 150° C., it is advantageous to preheat the starting materials (alcohol and 2-cyanopyridine) with steam or the like. at the stage before the reactor to obtain the carbonate ester.

[0054]

(Reaction pressure)

The reaction pressure in the carbonate ester producing reactor 2 is preferably 0.1 to 20 MPa (absolute pressure). If the reaction pressure is below 0.1 MPa (absolute pressure), a pressure reducing device is required. As a consequence, the equipment becomes more complex and the cost increases, and in addition, energy is required to reduce the pressure, which leads to a decrease in energy efficiency. If the reaction pressure is higher than 20 MPa, the hydration reaction with 2-cyanopyridine does not proceed easily, resulting in a decrease in the yield of carbonate ester. In addition, energy is required to increase the pressure, resulting in reduced energy efficiency. From the viewpoint of increasing the yield of carbonate ester, the reaction pressure is more preferably 0.5 to 15 MPa (absolute pressure), and even more preferably 1.0 to 10 MPa (absolute pressure).

[0055]

(Amount of 2-cyanopyridine)

The 2-cyanopyridine used for the hydration reaction is preferably used in a molar amount of 0.1 to 5 times the theoretical molar amount of water produced by the reaction of alcohol and CO ₂ as raw materials, and is preferably introduced into the reactor before the reaction. The molar amount of 2-cyanopyridine is more preferably 0.2 to 3 times, and particularly preferably 0.3 to 1.5 times the theoretical molar amount of water produced by the reaction of alcohol and CO ₂ as raw materials. If the molar amount of 2-cyanopyridine is too small because the amount of 2-cyanopyridine involved in the hydration reaction is small, the yield of carbonate ester may be reduced. However, if 2-cyanopyridine is introduced in an excess molar amount relative to the alcohol as a starting material, the side reaction of 2-cyanopyridine is increased and thus is undesirable. Since the ideal amounts of alcohol and 2-cyanopyridine relative to the solid catalyst are believed to vary depending on the type and amount of solid catalyst, the type of alcohol, and the ratio of alcohol to 2-cyanopyridine, it is advisable to set the optimal conditions appropriately.

[0056]

(Separation of reaction products)

Preferably, the separation of the reaction products is carried out entirely by distillation. After the reaction in the reactor 2 to produce carbonate ester, the reaction solution 13 is transferred to the column 3 to collect CO ₂ . A mixture of PrOH, DPrC, 2-cyanopyridine and 2-picolinamide is collected from the bottom of the CO ₂ recovery column 3 through a liquid transfer line 14 from the bottom of the CO ₂ recovery column, and CO ₂ is recovered from the top of the CO ₂ recovery column 3 through pipeline 15 for pumping CO ₂ from the top of the column to capture CO ₂ . The captured CO ₂ is transferred to intermediate vessel 1 and reused in the reaction in reactor 2 to produce carbonate ester.

[0057]

The mixture collected from the CO ₂ recovery column 3 is supplied to the dehydrating agent separation column 4 through a liquid transfer line 14 from the bottom of the CO ₂ recovery column. A mixture of 2-cyanopyridine and 2-picolinamide is collected from the bottom of the dehydrating agent separation column 4 through a liquid transfer line 16 from the bottom of the dehydrating agent separation column, and PrOH and DPrC are collected from the top of the dehydrating agent separation column 4 through a liquid transfer line 17 from the top parts of the dehydrating agent separation column.

[0058]

The mixture collected from the bottom of the dehydrating agent separation column 4 is transferred to the amide separation column 6 through a liquid transfer line 16 from the bottom of the dehydrating agent separation column. 2-picolinamide (20) is collected from the bottom of the amide separation column 6, and 2-cyanopyridine is collected from the top of the amide separation column 6. The collected 2-cyanopyridine is transferred to the intermediate vessel 1 through the liquid transfer line 21 from the top of the amide separation column and is reused in the reaction in the reactor 2 to produce the carbonate ester.

[0059]

PrOH and DPrC collected from the top of the dehydrating agent separation column 4 are transferred to the carbonate ester recovery column 5 through a liquid transfer line 17 from the top of the dehydrating agent separation column. DPrC is recovered from the bottom of the carbonate ester recovery column 5 through a liquid transfer line 18 from the bottom of the carbonate ester recovery column, and PrOH is recovered from the top of the carbonate ester recovery column 5 through a liquid transfer line 19 from the top of the carbonate ester recovery column . The captured PrOH is transferred to intermediate vessel 1 and reused in the reaction in reactor 2 to produce carbonate ester.

[0060]

(Second stage of reaction)

In the second stage of the reaction, 2-cyanopyridine is obtained through the dehydration reaction of 2-picolinamide in gas-phase reactor 8 for nitrile regeneration.

The 2-picolinamide recovered from the amide separation column 6 is transferred to the evaporator 7 through a liquid transfer line 20 from the bottom of the amide separation column. Preferably, it is mixed with an inert gas, which is nitrogen or the like, the resulting mixture is heated to a temperature near the boiling point of the amide to produce a gas or a mixed gas consisting of gas and droplets, and transferred to the gas-phase reactor 8 for nitrile regeneration through line 22 , connecting the gas-phase nitrile regeneration reactor and the evaporator. Evaporator form 7 for evaporation of amide compound, etc. is not particularly limited, and any ejector type evaporator, contact type evaporator, bubbler device, etc. can be used.

[0061]

In the apparatus for producing a nitrile compound used in the present invention (nitrile regeneration gas phase reactor 8), 2-picolinamide and preferably an inert gas which is nitrogen or the like, etc. contacted with a catalyst containing a transferred base metal oxide in the gas phase to cause a dehydration reaction of 2-picolinamide. This dehydration reaction produces 2-cyanopyridine. When transferring the amide compound, in order to prevent clogging problems, the amide compound may be dissolved in a transfer solvent to transfer the liquid. When using a transfer solvent for the amide, it is preferable that the solvent also evaporates along with the amide to conduct a gas-phase nitrile regeneration reaction. In this case, solvent vapor can be used instead of an inert gas.

[0062]

The shape of the gas-phase nitrile regeneration reactor 8 is not particularly limited. It is preferable to use a gas-phase reaction in which the amide compound in the form of a gas or mist is passed through a catalyst bed along with an inert gas or the like, and a fixed-bed, fluidized-bed, or the like gas-phase reaction apparatus can be applied to it.

Thus, to effectively promote the dehydration reaction by bringing 2-picolinamide into contact with a catalyst, etc. in the gas phase, the various reaction conditions described above relating to the dehydration reaction or the reaction conditions described in the examples below are respectively used.

[0063]

The mixed gas containing 2-cyanopyridine is transferred from the gas-phase reactor 8 to the H ₂ O separation device 9 through the pipeline 23 for pumping gas-phase reaction products. Water and nitrogen gas are separated from the mixed gas in the H ₂ O separation device 9, and the captured 2-cyanopyridine and 2-picolinamide are transferred from the H ₂ O separation device 9 to the amide separation column 6 through the high boiling point transfer line 24. Then, 2-picolinamide is recovered from the bottom of the amide separation column 6 through a liquid transfer line 20 from the bottom of the amide separation column and transferred to the evaporator 7, and 2-cyanopyridine is recovered from the top of the amide separation column 6. The collected 2-cyanopyridine is transferred to the intermediate vessel 1 through the liquid transfer line 21 from the top of the amide separation column and is reused in the reaction in the reactor 2 to produce the carbonate ester.

[0064]

Then, the nitrogen gas and water separated in the H ₂ O separating device 9 are transferred to the N ₂ collecting device 10 through the low boiling point media transfer line 25, and the water is separated in the N ₂ collecting device 10 to collect the nitrogen gas. The water separated in the N ₂ recovery device 10 is transferred to the outside of the carbonate ester production device through a water transfer line 26 from the N ₂ recovery device. Nitrogen gas captured in the N ₂ recovery device 10 is pumped to the evaporator 7 through a transfer line 27 from the N ₂ recovery device, and can be used in the gas-phase reaction. In the case of using a transfer solvent for the amide compound, the solvent capture step is used separately, thereby reusing the solvent to transfer the amide compound. The shape of each of the H ₂ O separating device 9 and the N ₂ collecting device 10 is not particularly limited, and any one of a cooling system, a membrane separating device, etc. can be used.

[0065]

As described above, in the present invention, dehydration of the amide compound can be promoted by a gas phase contact step, and further, the reaction product and recycled compounds can be separated by distillation or the like. without separation of solid and liquid phases. For this reason, according to the present invention, the carbonate ester can be efficiently produced in fewer production steps while simplifying the installation.

EXAMPLES

[0066]

The present invention is described in more detail below by way of examples, but the present invention is not limited to them. Below, examples and comparative examples of the method for producing cyanopyridine are first described.

[0067]

(Example 1)

SiO ₂ as a support (manufactured by Fuji Silysia Chemical Ltd., CARiACT, Q-6 (support diameter: 0.075 to 0.15 mm)) was pre-heat-treated at 700° C. for about 1 hour. Then, to transfer Cs as an alkali metal, an aqueous solution was prepared using Cs ₂ CO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) so that the final amount of Cs metal transferred was 0.5 mmol/g, and the aqueous solution was impregnated with SiO ₂ . The resulting material was then dried at 110° C. for about 6 hours and then heat-treated at 500° C. for about 3 hours to thereby obtain a Cs ₂ O/SiO ₂ catalyst.

A reaction tube 40 made of SUS 304 with an inner diameter of 10.7 mm and a length of 30 cm was filled with the catalyst obtained by the above-described production method (see FIG. 2). In addition, an evaporation chamber 42 made of SUS 304, with an inner diameter of 10.7 mm and a length of 30 cm, and filled with a Raschig ring, was placed directly above the reaction tube 40.

[0068]

10 g of 2-picolinamide (2-PA) was dissolved in 4-methylpyridine as a transfer solvent (90 g), and the resulting mixture was placed in the starting material container 44. The container 44 for the starting material was placed on a high-precision balance, a suction pipe with a filter was lowered into the solution of the starting material, and the scale was balanced.

Nitrogen was passed through the evaporation chamber 42 connected to the feed container 44 and the reaction tube 40 at a flow rate of 1000 ml/min, and the evaporation chamber 42 and the reaction tube 40 were heated to 230° C., respectively, using flask heaters 46 and 48. In addition, the nitrogen supply line 50 and the outlet side line of the reaction tube 40 were maintained at a temperature of 150°C. To capture the reaction product, a water-cooled collection vessel 52 is positioned in the first stage, a dry ice/methanol-cooled collection vessel 54 is positioned in the second stage, and a liquid nitrogen-cooled collection vessel (not shown) is positioned in the last stage.

[0069]

After the temperature of the catalyst bed became stable, the plunger pump 56 was turned on and the reaction was carried out for the time indicated in the catalyst contact time column in the table below. During the reaction, the pressure was prevented from increasing excessively by the pressure limiter 58, so that the pressure in the reaction system of the cyanopyridine producing apparatus shown in FIG. 2, did not exceed 506.5 (kPa).

[0070]

The conditions for the above-described contact reaction (dehydration reaction) were as presented in Table 1. After completion of the reaction, the resulting reaction product was captured and analyzed by GC-FID.

[0071]

The analysis conditions for the results of the contact reaction (dehydration reaction) were as shown below.

[Analysis conditions]

(GC-FID)

Shimadzu GC-2014, column: TC-17 (length: 30 m, internal diameter: 0.25 mm ID, liquid phase thickness: 0.25 μm)

Evaporation chamber temperature: 250°C, detector: 260°C, He carrier: 175 kPa, column flow rate: 2.5 ml/min, flow division: 50

Temperature program: [held at 70°C for 5 minutes] → [increased to 190°C, 12°/min] → [held at 190°C for 5 minutes] → [increased to 250°C, 12°C /min] → [kept at 250°C for 10 min]

[0072]

[24-hour yield per 1 g of catalyst (mmol/24 h⋅g)] =

(Amount of product recovered after 24 hour reaction (mmol))/(Amount of catalyst (g))

[Volumetric velocity: SV (hour ^-1 )] =

(Amount of gas passing through the catalyst layer (l⋅hour ^-1 ))/(Amount of catalyst (l))

Gas quantity: sum of volumes of nitrogen, 2-PA and solvent gases (l⋅h ^-1 )

[Catalyst filling height (height of the catalyst layer in the reactor)]: height of the catalyst filled in the reaction tube (cm)

[Duration of contact with catalyst (sec)] =

[Catalyst filling height (cm)]/[Linear velocity (linear gas velocity in the reactor) (cm/sec)]

[0073]

[Diameter of catalyst carrier]

The catalyst support diameter value was measured based on the screening method: Test screening - General requirements defined in JIS Z8815.

[0074]

(Examples 2-15)

In Example 2 onwards, the reaction was carried out in the same way as in Example 1, except that the conditions were changed as shown in Table 1. The results are shown in Table 1.

In each of the Examples and Comparative Examples, the active component of the catalyst was Cs ₂ O; the carrier used was CARiACT Q-6 (the main component is SiO ₂ ), manufactured by Fuji Silysia Chemical Ltd.; and the amount of active metal carried by the catalyst (transferred amount during metal conversion of active substances based on the total mass of the catalyst) was 0.5 mmol/g. Moreover, in each of the Examples and Comparative Examples, 2-picolinamide (2-PA) was used as the aromatic amide compound.

[0075]

(Example 16)

Unlike examples 1-15, in example 16 the contact reaction (dehydration reaction) of the aromatic amide compound was carried out under reduced pressure. In particular, it was performed as described below.

100 g of 2-picolinamide (2-PA) was dissolved in cyclopentanone as a transfer solvent (900 g), and the mixture was placed in a starting material container.

Nitrogen was passed through the reaction line (from ejector 62 to trap 64 shown in FIG. 3) connected to feed container 60 at a flow rate of 1000 ml/min. After stopping the supply of nitrogen, a vacuum pump 66 was connected to trap 64 and the pressure in the reaction system was reduced to 0.5 kPa. The evaporator 68 and the reactor 70 were heated to 220°C, respectively, using electric ovens (not shown). The conduit on the outlet side of the reaction line was then heated to 150° C. using a band heater (not shown). To collect the reaction product, a dry ice/methanol cooled trap 64 (first fraction trap 64A and trap 64B in FIG. 3) was positioned, and a liquid nitrogen cooled trap (not shown) was positioned adjacent thereto.

After the temperature of the catalyst bed (not shown) placed in the reactor 70 became stable, the plunger pump 72 was started and the reaction was carried out. Within 90 minutes from the time when the inside of the catalyst layer reached a steady state, the reaction product was collected using a collection trap 64B. During the reaction, the pressure in the reaction system of the cyanopyridine production apparatus shown in FIG. 3 was controlled by the pressure reduction regulator 74 and the needle valve 76. It should be noted that before the inside of the catalyst bed reaches a steady state and after the reaction product is captured by the trap 64B after the inside of the catalyst bed reaches a steady state, the reaction product captured using Trap 64A for the first fraction.

The conditions for the above-described contact reaction (dehydration reaction) were as presented in Table 1. After completion of the reaction, the resulting reaction product was captured and analyzed by GC-FID.

[0076]

(Examples 17-21)

In Example 17 onwards, the reaction was carried out in the same manner as in Example 16, except that the conditions were changed as shown in Table 1.

[0077]

The results of Examples 1-21 are presented below in Table 1.

Table 1

[0078]

(Comparative examples 1-9)

In Comparative Examples 1 to 9, a solvent was used to remove the reaction water to the outside of the reaction system, and a dehydration reaction was carried out in the liquid phase.

[0079]

(Comparative example 1)

SiO ₂ as a support (manufactured by Fuji Silysia Chemical Ltd., CARiACT, Q-6 (support diameter: 0.075 to 0.15 mm)) was pre-heat-treated at 700° C. for about 1 hour. Then, to transfer Cs as an alkali metal, an aqueous solution was prepared using Cs ₂ CO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) so that the final amount of Cs metal transferred was 0.5 mmol/g, and the aqueous solution was impregnated with SiO ₂ . The resulting material was then dried at 110°C for about 6 hours and then heat-treated at 500°C for about 3 hours to thereby obtain a Cs ₂ O/SiO ₂ catalyst.

[0080]

Then, a three-neck round-bottom flask was used as a reactor, and a magnetic stirrer, the above-described Cs ₂ O/SiO ₂ catalyst, 2-picolinamide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 1,3-dimethoxybenzene (manufactured by Tokyo Chemical Industry Co.) were introduced into the reactor. ., Ltd.).

A thermometer and an air-cooling tube containing 10 g of 4A molecular sieve were then attached to the reactor, and a Liebig condenser was attached to the upper end of the air-cooling tube to create a reaction device.

Then, the reaction solution was heated at normal pressure and kept in a boiling state, and the by-product water was adsorbed onto a molecular sieve without returning to the dehydration reactor, thereby carrying out the reaction.

The reaction was started when the reaction solution began to boil, and the reaction was carried out for 24 hours.

After the reaction, the temperature was lowered to room temperature. A sample was taken from the reaction solution and diluted twice with ethanol, and 1-hexanol was added to it as an internal standard substance. The obtained substance was subjected to qualitative analysis using GC-MS (gas chromatograph - mass spectrometer) and quantitative analysis using GC-FID.

[0081]

(Comparative examples 2-7)

In Comparative Examples 2 to 7, the reaction was carried out in the same manner as in Comparative Example 1, except that the conditions were changed as shown in Table 2.

[0082]

(Comparative examples 8-9)

In Comparative Examples 8-9, the conditions were changed as shown in Table 2, and further, the apparatus configuration and reaction conditions were changed as described below, thereby carrying out the reaction.

[0083]

SiO ₂ as a support (manufactured by Fuji Silysia Chemical Ltd., CARiACT, Q-6 (support diameter: 0.075 to 0.15 mm)) was ground to 100 mesh or less and pre-heat-treated at 700° C. for about 1 hour. Then, to transfer Cs as an alkali metal, an aqueous solution was prepared using Cs ₂ CO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) so that the final amount of Cs metal transferred was 0.5 mmol/g, and the aqueous solution was impregnated with SiO ₂ . The resulting material was then dried at 110°C for about 6 hours and then heat-treated at 500°C for about 3 hours to thereby obtain a Cs ₂ O/SiO ₂ catalyst.

[0084]

Then, a three-neck round-bottom flask was used as a reactor, and a magnetic stirrer, the above-described Cs ₂ O/SiO ₂ catalyst, 2-picolinamide (manufactured by Tokyo Chemical Industry Co., Ltd.) and diphenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) were introduced into the reactor. .).

Then, a thermometer and a first air-cooling pipe were attached to the reactor as a distillation column, a distillation head equipped with a thermometer was attached to the upper end of the first air-cooling pipe, and a second air-cooling pipe, a receiver, and a vacuum pump were attached to the distillation head to form a reactive distillation apparatus. It should be noted that a heater strip was wound around the first air cooling pipe to regulate the temperature. The cooling trap was then cooled with liquid nitrogen to capture the evaporated pyridine.

The pressure in the reactive distillation apparatus was then reduced to 13.3 kPa (100 Torr) using a vacuum pump. The first air cooling tube was heated to 60° C., which was above the boiling point of water and below the boiling point of diphenyl ether at the reaction pressure. The reaction solution was maintained in a boiling state at 184°C, which was equal to or above the boiling point of diphenyl ether and below the boiling point of 2-picolinamide at the reaction pressure. By adjusting the temperature in this manner, the partially vaporized diphenyl ether in the reaction system was cooled in the first air cooling tube and returned to the reactor, while the by-product water was distilled to the outside of the system without returning to the reactor, thereby carrying out the reaction.

The reaction was started when the reaction solution began to boil, and the reaction was carried out for 24 hours.

After the reaction, the temperature was lowered to room temperature. A sample was taken from the reaction solution and diluted twice with ethanol, and 1-hexanol was added to it as an internal standard substance. The obtained substance was subjected to qualitative analysis using GC-MS (gas chromatograph - mass spectrometer) and quantitative analysis using GC-FID.

[0085]

The results of Comparative Examples 1-9 are presented below in Table 2.

table 2

[0086]

Preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to these examples. Obviously, those skilled in the art pertaining to the present invention may propose any of various altered or modified examples within the scope of the technical idea set forth in the claims, it is understood that such altered or modified examples are duly included within the scope of the present invention. .

LIST OF ITEM NUMBERS

[0087]

1 intermediate tank (CO ₂ , PrOH, DPrC, 2-CP, 2-PA)

2 reactor for the production of carbonate ester (CO ₂ , PrOH, DPrC, 2-CP, 2-PA, fixed catalyst)

3 column for CO ₂ capture (CO ₂ , PrOH, DPrC, 2-CP, 2-PA)

4 dehydrating agent separation column (PrOH, DPrC, 2-CP, 2-PA)

5 column for carbonate ether recovery (PrOH, DPrC)

6 amide separation column (2-CP, 2-PA)

7 evaporator (N ₂ , 2-PA)

8 gas-phase reactor for nitrile regeneration (N ₂ , H ₂ O, 2-CP, 2-PA, catalyst)

9 _H2O separation device ( _N2 , _H2O , 2-CP, 2-PA)

10 device for collecting N ₂ (N ₂ , H ₂ O)

11 circulation pipeline of the first reaction solution (CO ₂ , PrOH, DPrC, 2-CP, 2-PA)

12 circulation pipeline of the second reaction solution (CO ₂ , PrOH, DPrC, 2-CP, 2-PA)

13 pipeline for removing the reaction solution (CO ₂ , PrOH, DPrC, 2-CP, 2-PA)

14 pipeline for pumping liquid from the bottom of the column to capture CO ₂ (PrOH, DPrC, 2-CP, 2-PA)

15 pipeline for pumping CO2 from the top of the column to capture CO ₂ (CO ₂ )

16 pipeline for pumping liquid from the bottom of the dehydrating agent separation column (2-CP, 2-PA)

17 pipeline for pumping liquid from the top of the dehydrating agent separation column (PrOH, DPrC)

18 pipeline for pumping liquid from the bottom of the column to capture carbonate ether (DPrC)

19 pipeline for pumping liquid from the top of the column to capture carbonate ether (PrOH)

20 pipeline for pumping liquid from the bottom of the amide separation column (2-PA)

21 pipelines for transferring liquid from the top of the amide separation column (2-CP)

22 pipeline connecting the gas-phase reactor for nitrile regeneration and the evaporator (N ₂ , 2-PA)

23 pipeline for pumping gas-phase reaction products (N ₂ , H ₂ O, 2-CP, 2-PA)

24 pipeline for pumping media with high boiling points from the H ₂ O separation device (2-CP, 2-PA)

25 pipeline for pumping media with low boiling points from the H ₂ O (N ₂ , H ₂ O) separation device

26 pipeline for pumping water from the N ₂ (H ₂ O) capture device

27 pipeline for pumping N ₂ from the N ₂ recovery device (N ₂ )

31 pipelines for supplying raw materials (CO ₂ , PrOH)

40 reaction tube

42 evaporation chamber

44 capacity for source material

46, 48 bulb heater

50 pipeline for supplying nitrogen gas

52 water-cooled catch tank

54 dry ice/methanol cooled catch tank

56 plunger pump

58 pressure limiter

60 capacity for starting material

62 ejector

64 trap

64A trap for the first fraction

64B catch trap

66 vacuum pump

68 evaporator

70 reactor

72 plunger pump

74 pressure reduction regulator

76 needle valve

Claims (20)

1. A method for producing an aromatic nitrile compound, comprising a dehydration reaction in which the aromatic amide compound is dehydrated, wherein the method includes a contact step for bringing the aromatic amide compound into contact with the catalyst in the gas phase during a dehydration reaction, wherein the catalyst includes an alkali metal and wherein the aromatic amide compound is 2-picolinamide, 3-picolinamide or 4-picolinamide; and the aromatic nitrile compound is 2-cyanopyridine, 3-cyanopyridine or 4-cyanopyridine. 2. A method for producing an aromatic nitrile compound according to claim 1, wherein the catalyst includes an alkali metal oxide. 3. A method for producing an aromatic nitrile compound according to claim 1, wherein the aromatic amide compound is 2-picolinamide, wherein the aromatic nitrile compound is 2-cyanopyridine. 4. A method for producing an aromatic nitrile compound according to any one of claims 1-3, in which, at the contact stage, an inert gas and/or a solvent in a vapor state is additionally brought into contact with the catalyst. 5. A method for producing an aromatic nitrile compound according to claim 4, wherein the inert gas comprises at least nitrogen gas. 6. A method for producing an aromatic nitrile compound according to claim 4 or 5, in which the boiling point of the solvent at normal pressure is from 20 to 300 °C. 7. A method for producing an aromatic nitrile compound according to any one of claims 4 to 6, wherein the solvent is compatible with the aromatic amide compound. 8. A method for producing an aromatic nitrile compound according to any one of claims 4 to 7, wherein the solvent is a pyridine compound and/or a ketone compound. 9. A method for producing an aromatic nitrile compound according to any one of claims 1 to 8, wherein in the contact step, the temperature at which the aromatic amide compound is brought into contact with the catalyst in the gas phase is 170 °C or higher but lower than 300 °C. 10. A method for producing an aromatic nitrile compound according to any one of claims 1 to 9, wherein the duration of bringing the aromatic amide compound into contact with the catalyst in the gas phase is 0.001 s or more but less than 10 s. 11. A method for producing carbonate ester, including: a first reaction step including: a carbonate ester production reaction in which the alcohol is reacted with carbon dioxide in the presence of an aromatic nitrile compound to produce a carbonate ester and water, and a hydration reaction in which the aromatic nitrile compound is hydrated with the resulting water to produce an aromatic amide compound; And a second reaction step in which the aromatic amide compound is separated from the reaction system of the first reaction step and then the aromatic amide compound is regenerated to obtain an aromatic nitrile compound through a dehydration reaction for dehydrating the aromatic amide compound according to the method according to any one of claims 1 to 10, wherein at least a portion of the aromatic nitrile compound recovered in the second reaction step is used in the first reaction step. 12. The method for producing a carbonate ester according to claim 11, wherein in the second reaction step, an aromatic nitrile compound is produced from an aromatic amide compound according to the method for producing an aromatic nitrile compound according to any one of claims 2 to 10 for regenerating the aromatic nitrile compound. 13. The method for producing a carbonate ester according to claim 11 or 12, in which a catalyst comprising cerium oxide is used in the reaction for producing the carbonate ester. 14. A method for producing a carbonate ester according to any one of claims 11 to 13, wherein the alcohol includes an alcohol containing from 1 to 6 carbon atoms.